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An investigation to evaluate the relationship between rock quality index (RQI) and powder factor for… LeBel, J. R. Guy 1984

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AN  INVESTIGATION  BETWEEN  TO  EVALUATE  ROCK Q U A L I T Y FACTOR  FOR  INDEX  THE  RELATIONSHIP,  ( R Q l ) AND  SURFACE  POWDER  MINING  by J.R. B.A.Sc,  A THESIS THE  GUY  Laval  SUBMITTED  University,  OF  1981  IN PARTIAL FULFILMENT  REQUIREMENTS MASTER  LEBEL  FOR  THE  APPLIED  DEGREE  OF  OF  SCIENCE  in THE Department  FACULTY  of M i n i n g  We  accept to  THE  OF  and M i n e r a l  this  the  GRADUATE  thesis  required  UNIVERSITY  OF  June  (cT)  J.R.  GUY  STUDIES  Process  as  Engineering  conforming  standard  BRITISH  COLUMBIA  1984  LEBEL,  1984  In  presenting  requirements  this for  an  of  British  it  freely available  agree for  that  I  by  understood  that  his  that  or  be  her or  shall  f u l f i l m e n t of at  the  University  Library  shall  and  study.  I  copying  granted  by  the  of  publication be  of  allowed  this  It  this  without  of  Mining  and  The U n i v e r s i t y o f B r i t i s h 1956 Main M a l l Vancouver, Canada V6T 1Y3 August  13,  1984  Mineal  Process  Columbia  thesis  of  my  is  thesis my  permission.  Department  make  further  head  representatives.  not  the  the  extensive  may  copying  f i n a n c i a l gain  degree  reference  for  purposes  or  partial  agree  for  permission  scholarly  in  advanced  Columbia,  department  for  thesis  Engineering  written  i i  ABSTRACT  The problem costly  determination that  trial  suitable  Shortly  and  the  correlation  controlled project  was  engineers  constant  this  the  at  Rock  Rock  Quality  performance  data.  rock  mass  variations  in  the  rock  quality.  blast  Equity  determine  and  design  Silver,  evaluated  the  factors  It  was  found  of  the  relationship.  the  factors  process. Leighton locations  that  to  drill  in order  to  of  is a  are  easily  the  performance obtain  in  RQI  such  rotary numerical  relationship. data  were  relationship  affect  the  determination  mechanism  or  to  was  and  its definition.  two  data.  of  practical  in  accurate  research  from  Mines,  was  on  the  extent  and  control  recorder  report  reflects  the  data  mass  progress.  and  divided  drilling  a  single  simple  confirm  actually  drilling  a  empirical  i n f l u e n c e or  factors  the  as  Greenhills  to  the  is a  The  rock  this  i s obtained  an  and  in order  They  accuracy a  Lornex  on  the  (RQI)  Mine,  Defined  It  to  Leighton  Index  p r o p e r t i e s , the  based  that  many  related  The and  Quality  Index  in  the  determine  the  gathered  of  to  of  At  UBC,  mass  basis.  is constantly  e s t a b l i s h e d in order  drill  to  variations  Afton  The  rock  daily  at  estimation  approach  a  the  eventually lead  approach  publication,  factor  may  on  of  defined  correlation. blasthole  that  between  powder  blastability  approach  although  presume  after  the  blasting  error  design,  properties  the  faces  of  of  used  categories, the  blasting  concern at  two  to of  the  This  research  idea  of  c o r r e l a t i o n between  mass  blastability  is right.  site  specific  to  from  various  a  due  project  drilling  the  permits Rock The  equipment  conditions.  Since  both  drilling  and  blasting  proposed  in  to  the  Quality  Rock  Optimum higher  order  is  ratio,  maintenance  cost.  with  established  a  well  correlation  and  many  in  the  also  variables  success  of  and  this  values to  are  the  basic  rock time,  obtained specific  found  basic  the  the  i s , at  RQI  due  mechanisms,  the  Index  that  to  affect  guidelines  further  research  are on  Index.  blasting  stripping  assure  conclusion  Quality  difference  blasting the  the  the high  However, rock  key  to  improved  productivity optimum mass  and  blasting  slope  stability,  reduced i s achieved  characterization  only  program.  i v  TABLE  OF  CONTENTS Page  ABSTRACT  i i  T A B L E OF  CONTENTS  LIST  OF  TABLES  LIST  OF  FIGURES  iv ix x  ACKNOWLEDGEMENTS CHAPTER  1  xv  INTRODUCTION  1  1.1  The  1980-1982 R e s e a r c h  Project  5  1.2  The  1982-1984 R e s e a r c h  Project  9  1 .3  References  CHAPTER  2  2.1  ROCK Review  FRAGMENTATION o f Rock  Failure  Mechanisms  Rock  Mass C h a r a c t e r i s t i c s  2.1.2  The Coulomb-Navier  2.1.3  T h e Mohr T h e o r y  2.1.4  The G r i f f i t h  2.1.5  Hoek a n d Brown E m p i r i c a l Cr i t e r i o n  Drilling,  2.3  References  3.1  13  2.1.1  2.2  CHAPTER  12  3  Blasting,  of F a i l u r e  of F a i l u r e of F a i l u r e Failure  Grinding  16 17 18 21  26 29  THE D R I L L I N G Tricone  16  Theory  Theory  16  Rotary  3.1.1  Journal  3.1.2  Teeth  3.1.3  Bear ings  PROCESS  31  Bits  34  Angle  a n d Skew  and C a r b i d e  Angle  Inserts  38 40 43  V  Page  3.2  3.1.4  Gage  Design  3.1.5  Aircourses  Penetration 3.2.1  Stresses  of  and  Brittle  Beneath  The  Indexing  Tool  Indentor  Bauer Model  P a r i s e a u and t i o n Models  3.3  Specific  Energy  3.4  Rock  3.4.2  A n a l y s i s of t i e s of the  3.5.1  58  Sikarskie Penetration  and  Calder  Penetration  Fairhurst Penetra-  Drilling  62  65  72  Tests  Rotary  60  69  Drillability  Drilling  51 54  Models  Tricone  Indentor  58  Paul and Model  3.4.1  46  51  Geometry  3.5  Rocks  the  Penetration  Mass  Protection  48  3.2.2  Shirttail  72  the Mechanical Rock  Proper-  Drilling  73  79  Parameters  79  The  Weight  on  The  Rotary  Speed  The  A i r Pressure  The  Torque  84  Equations  84  Index  88  3.5.2  Drilling  3.6  Rock  Quality  3.7  Summary  the  Bit  79 82  and  Volume  82  92  vi  Page 3.8 CHAPTER 4.1  4.2  References 4  THE  BLASTING  Theory  PROCESS  97  of B l a s t i n g Expansion  103  4.1.1  Gas  4.1.2  S t r e s s Wave T h e o r y  4.1.3  Practical  The Major tion 4.2.1  4.3  93  Theory  Blasting  103 105  Theory  Factors Affecting  Rock  Mass  Properties  Structural  Failure  4.2.2  Design  4.2.3  The D e s i g n  Rock Mass  Fragmenta-  108  108  Geology  Behaviour  Parameters Powder  107  108 117 120  Factor  Blastability  137 142  4.3.1  Visual Determination Mass B l a s t a b i l i t y  o f t h e Rock  142  4.3.2  C h a r a c t e r i z a t i o n o f t h e Rock Mass by G e o p h y s i c M e t h o d s  143  4.3.3  C o r r e l a t i o n of the B l a s t a b i l i t y with one o r more Rock Mass P r o p e r t i e s , Measured i n Laboratory or I n - S i t u  144  4.3.4  Determination of the B l a s t a b i l i t y by S m a l l C r a t e r T e s t s  149  4.3.5  C h a r a c t e r i z a t i o n o f t h e Rock Mass from the Performance of P r o d u c t i o n Rotary D r i l l s  154  4.4  Summary  159  4.5  References  165  vii  Page CHAPTER  5  FIELD  RESEARCH  PROJECT  5.1  D r i l l Performance Industry  5.2  Equity  5.3  5.4  5.5  Silver  Summary  5.2.2  The B l a s t i n g Silver  5.2.3  Development B e t w e e n RQI  5.2.4  Analysis  Lornex  Recorder  Mine  5.2.1  171 i n the Mining  ^  185  of the Geology  185  Procedures at Equity  of the C o r r e l a t i o n a n d Powder Factor  of the Results  Mine  Summary  5.3.2  The B l a s t i n g  5.3.3  Development B e t w e e n RQI  5.3.4  Analysis  of the Geology  192  198  200  Procedures a t Lornex of the C o r r e l a t i o n a n d Powder Factor  of the Results  Mine  5.4.1  Summary  5.4.2  The B l a s t i n g Greenhills  5.4.3  Development B e t w e e n RQI  5.4.4  Analysis  Discussion  190 „  200  5.3.1  Greenhills  175  204 206  211 212  of the Geology  212  Procedures at  of the C o r r e l a t i o n a n d Powder Factor  of the Results  and I n f e r e n c e s of the Input  217  218  224 225  5.5.1  Accuracy  5.5.2  Drill  5.5.3  Drilling  Procedures  228  5.5.4  Blasting  Procedures  231  Performance  Data  Recorders  225 226  vi i i  Page 5.5.5  Rock Mass  5.5.6  Correlations Index  5.6  Suggested  5.7  References  CHAPTER  6  Conditions with  Further  and P r o p e r t i e s  t h e Rock Q u a l i t y  Research  233 234  236 240  CONCLUSIONS  242  BIBLIOGRAPHY  246  APPENDICES I II  III IV V  B I T COMPARISON RELATIONSHIP WEIGHT  260  BETWEEN DOWN P R E S S U R E  P O S S I B L E B E N E F I T S FROM R E V I E W OF  T.E. LITTLE  MODIFICATION  OF  AND  APPLIED  IMPROVED FRAGMENTATION REPORT ON  B L A S T I N G METHODS  RQI  262  266 268 273  ix  LIST  OF  TABLES  Table 1  A p p r o x i m a t e R e l a t i o n s h i p Between Q u a l i t y and M a t e r i a l Constants  2  E f f e c t on O v e r s i z e F r a g m e n t a t i o n o f Blasth o l e S p a c i n g , S, J o i n t S p a c i n g , S j , a n d Oversize Specification, M  3  Levels of B l a s t i n g on P i t W a l l s  4  Rock  5  Summary  6  C o r r e l a t i o n Between E q u i t y S i l v e r Mine  7  Summary o f RQI V a l u e s Lornex Mine  8  Rock  9  Summary  10  C o r r e l a t i o n Between G r e e n h i l l s Mine  11  R e l a t i o n s h i p Between Rotary B i t Diameter  Properties  Damage  Equity  o f RQI V a l u e s  Properties  Observed  Silver  a n d Powder  a n d Rock  Strength  at  at  Mine  a n d Powder  Rock  Mine  Factor  at Greenhills  RQI  Mass  Mine  at Equity  Greenhills  o f RQI V a l u e s  Commonly  Silver  RQI  Rock  Quality  Mine Factor  at  Index and  X  LIST  OF  FIGURES  Figure 1.1-1  Rock Q u a l i t y Index Ranked i n Order of  1.1-2  P r o p o s e d C o r r e l a t i o n Between Rock Q u a l i t y I n d e x and Powder F a c t o r a t A f t o n M i n e  2.1-1  G r a p h i c a l R e p r e s e n t a t i o n of Mohr S t r e s s C o n d i t i o n s f o r F a i l u r e of Rock  2.1-2  Mohr C i r c l e s f o r Quartzite Tested  2.1- 3  Graphical Representation Failure Criterion  2.2- 1  Comparison Various  of  V a l u e s f o r E a c h Domain Increasing Quality  F a i l u r e of by Hoek  Energy  Development  3.1-2  Roller  3.1-3  Nomenclature  Bit  History  of  Specimen  of  Hoek  Brown  Requirement  Fragmentation  3.1-1  of  Theory Intact  and  ^  for  Processes of  Rotary  Rock  Bits  Improvement of  Rotary  Bit  3.1-4  Tricone  3.1-5  V a r i o u s I n s e r t Shapes H o l e Rock B i t s  Bit Offset  3.1-6  Results  3.1-7  Effect  Loads  on  Bit  3.1- 8  C r o s s - S e c t i o n a l View  of  a  3.2- 1  S t r e s s P r o f i l e on A x i s of Symmetry  3.2-2  Media  3.2-3  C h a r a c t e r i s t i c Force-Penetration Curves C h a r c o a l Gray G r a n i t e Under S t a t i c B i t Loading  of of  Roller Side  After  Commonly  Bearing  Contact  Secondary  Used  in  Blast  Tests Bearings  Jet  Bit  Surface  Failure  Has  and  on.  Occured for  xi  3.2-4  Average F o r c e - P e n e t r a t i o n Curves f o r C a r t h a g e M a r b l e a s O b t a i n e d w i t h 30 a n d Degree Sharp B i t - T e e t h a t Atmospheric Pressure f o r Various Indexing Distances  60  3.2-5  T h e o r e t i c a l F o r c e - P e n e t r a t i o n Curve B r i t t l e C r a t e r Model  3.2-6  Rock P e n e t r a t i o n C o n s t a n t Compressive Strength  3.2-7  Assumed S t r e s s Situat ion  3.4-1  E s t i m a t e d D r i l l i n g R a t e o f New H u g h e s T r i c o n e R o c k B i t a t 60 r e v / m i n a s D e t e r m i n e d b y M i c r o b i t D r i l l i n g Rate T e s t s  3.4-2  Estimated Relative R a t e V e r s u s Number Metre Drill-Hole  3.4- 3  Correlation Rock  Field  vs  for  Uniaxial  f o r "False-Nose"  Increase in Penetration of Weakness P l a n e s p e r  of D r i l l i n g  Performance  with  Characteristics  3.5- 1  Drilling  Conditions  3.5- 2  R e l a t i o n s h i p Between Rock Compressive S t r e n g t h , P e n e t r a t i o n Rate, Weight and  3.6- 1  Drilling Diameter  4.0-1  Effect  4.0- 2  Output f o r D i f f e r e n t tion Single Crusher, Poor D i g g i n g  4.1- 1  Interaction t i n g Crack  4.2- 1  I l l u s t r a t i o n of the E f f e c t t u r e on C r a t e r F o r m a t i o n  o f Rock  Struc-  4.2-2  I l l u s t r a t i o n of the E f f e c t t u r e on C r a t e r F o r m a t i o n  o f Rock  Struc-  4.2-3  I l l u s t r a t i o n of the E f f e c t t u r e on C r a t e r F o r m a t i o n  o f Rock  Struc-  Rate  v s . Weight  of Fragmentation  per  on  Inch  Cost  of  RPM  of B i t  Mining  S h o v e l Truck CombinaGood C o n d i t i o n s and  of S t r a i n  Wave  with  Propaga-  xii  Page 4.2-4  Spectrum  of  4.2-5  T r e n d s of F r a g m e n t a t i o n L/B a n d S/B Ratios  4.2-6  Schematic B u r d e n on  4.2-7  E f f e c t of Water C o n t e n t V e l o c i t y o f AN/FO  4.2-8  Ratios  4.2-9  E f f e c t of D e l a y Time Between Average Fragment S i z e  4.2-10  Blasthole/Initiation Patterns S h o t s F i r e d t o an O p e n F a c e  4.2-11  P l o t of P a r t i c l e V e l o c i t i e s Induced at G i v e n D i s t a n c e s by P a r t i c u l a r C h a r g e s  136  4.2-12  S h o v e l P r o d u c t i o n on a Y e a r l y B a s i s a t One Operation Versus E x p l o s i v e Consumption in Rock o f 20,000 p s i C o m p r e s s i v e Strength  139  4.2- 13  A P l o t of G r o u n d V i b r a t i o n vs Powder F a c t o r M e a s u r e d From a S e r i e s of P r o d u c t i o n Blasts a t a L a r g e Open P i t M i n e S h o w i n g t h e A b r u p t I n c r e a s e of the L e v e l of G r o u n d Vibration as t h e Powder F a c t o r i s D e c r e a s e d  140  4.3- 1  Uniaxial  145  at  Rock  Behaviour  118  Index,  Fc,  with  123  of the E f f e c t of D e c r e a s i n g the S i m i l a r C h a r g e s F i r e d i n Rock on  the  Detonation  Benches  125  127  129 Shotholes  Compressive  Strength  Powder  with  vs  B=S  on  133  for  134  Powder  Factor 4.3-2  Acoustic  Velocity  4.3-3  Fracture  Frequency  4.3-4  Blastability  4.3-5  V a r i a t i o n of B r o k e n Rock Volume w i t h t h e D e p t h o f Embedment f o r a C o n c e n t r a t e d Charge  151  4.3-6a  Optimum  4.3-6b  Blastability  4.3-6c  Explosive Factor  Depth  vs  Factor  vs vs  Factor  Powder  147  Factor  Equivalent  148  RQD  150  Ratio  vs  Strain  Energy  Factor  153  Factor  vs  Strain  Energy  Factor  153  Consumption  vs  Strain  Energy  153  xi ii  Page 4.3- 7  Proposed Correlation Index  and  Powder of a  Between  Factor  Rock  at Afton  158  Mine  4.4- 1  Features  5.0- 1  L o c a t i o n s of Were C a r r i e d  5.1- 1  E f f e c t o f Mean D i s c o n t i n u i t y S p a c i n g on a) E a s e o f B l a s t i n g , b) P e n e t r a t i o n Rate  177  5.1-2  Recorded Chart  (Lornex)  179  5.1-3  Computer P l o t of t h e D i f f e r e n c e Between RQI-LOGS a n d RQI-REC a s a F u n c t i o n o f RQI-LOGS  182  5.1- 4  H i s t o g r a m of t h e Average D i f f e r e n c e Between RQI-LOGS a n d RQI-REC a s a F u n c t i o n of RQI-LOGS  183  5.2- 1  Schematic H i s t o r i c a l Mine  186  5.2-2  Equity  Blast  5.2-3  Rock Q u a l i t y Index V a l u e s f o r E a c h Domain Ranked i n O r d e r of D e c r e a s i n g Q u a l i t y , E q u i t y S i l v e r Mine  195  5.2- 4  P r o p o s e d C o r r e l a t i o n Between Rock I n d e x a n d Powder F a c t o r a t E q u i t y Mine  197  5.3- 1  L o r n e x Open  5.3-2  Lower-Hemisphere, Equal-Area Stereographic P r o j e c t i o n s of S t r u c t u r e s Mapped i n t h e L o r n e x Open P i t  203  5.3-3  Rock Q u a l i t y Lornex Mine  Index  of  208  5.3- 4  Relationship  Between  and  210  t h e M i n e s Where Out  Silver  Grinding  Satisfactory  Quality  Mine,  163  t h e RQI  Geology, Equity  1260m  Bench  Studies  Silver  Geology  191  Quality Silver  P i t Mine  Rate  173  201  in Different  Rock  Domains  Quality  Index  at Lornex  5.4- 1  Greenhills  Mine  Statigraphy  5.4-2  Greenhills  Cougar  Pit  213 214  xiv  Page 5.4-3  Rock Q u a l i t y Index V a l u e s f o r E a c h Domain Ranked i n Order of D e c r e a s i n g Q u a l i t y , Greenhills  221  5.4- 4  P r o p o s e d C o r r e l a t i o n Between Rock Q u a l i t y Index a n d Powder F a c t o r a t G r e e n h i l l s M i n e  223  5.5- 1  Influence of T r i c o n e Penetration Rate  230  Rotary  B i t Wear  on  XV  ACKNOWLEDGEMENTS  The  author  Professor and  CO.  pertinent  Mining their  addition,  cooperation  Young  Queen  The  Process  members  Engineering  unlimited  support  of the Department  are also  of  thanked f o r  Furnival  the author  has a p p r e c i a t e d  of their  employees  toward  -  Equity  Sliver  Mines L t d .  -  Lornex  Mining  Corp.  -  G r e e n h i l l s Mine  (Westar  technical assistance of Geolograph  and E r i c  t o M.C.  author  Preziozi  wishes  Scholarship  two y e a r s  Keyes  were  the author  Chris  Harbourne  (Westmin  Scholarship  was p r o v i d e d  of Dresser  which  project:  by Don  Paquette  Industries, of Prime  Gibson ofS I I ,  Alan  Bauer  Explosives.  f o r her encouragement.  made Fund  the financial  the project Scholarship,  Resources  also  spent  research  of  Mining Ltd.)  t o acknowledge  Council  this  Pioneer,  Chartrand  Cy a n d E m e r a l d  S. D i t m a r s  the involvement  and the a s s i s t a n c e and  B.C. S c i e n c e The  the  The f a c u l t y  U n i v e r s i t y and Jack  Thanks  the  for h i s dedication,  supervisor,  companies  Don C a m e r o n  Doug  h i s research  mining  Valuable  of  advice.  t o thank  encouragement.  following  and  wishes  Brawner,  and M i n e r a l  In the  first  very  from  possible. the Dr.  G.M.  L t d . ) and t h e L t . E r i c  much  a t U.B.C.  support  appreciated  during  1  CHAPTER 1  2  1.0  INTRODUCTION  Open factors: differ  p i t slope structural  than  engineering generally Although  some  blasting  outside  underload  when  t o a minimum,  there  a  urged  and w e l l  stripping  ratio  balance  blasting  blasting  and o p e r a t i n g  costs.  tough  does  slope.  an a r t ,  many In  to minimize  of a  high  t o the flatter  rock slope  the direct  engineer  digging  economic  will  occur.  often In  conditions  reduce  i n c e n t i v e toward the  practice.  muck  is  maintenance.  piles  costs.  and understood  sheet  resulting  blasts will  equipment  fragmented  the situation  profitable  damage,  careful  little  engineer  t o keep  over  inefficiently.  damage  the blasting  i s a major  o f optimum  than  the rock  causing  with  when  o f t h e same  science  They  control  very  him t o the u t i l i z a t i o n  hand,  and i n c r e a s e  better  However,  the excavation  therefore  to the p i t wall  walls  have  two.  breaking  major  and b l a s t i n g .  a p i t slope,  the b l a s t h o l e s and choked  achievement  minimum  leads  factor,  Therefore,  realized  designing  are s t i l l  the other  productivity  pit  the f i r s t  the p i t perimeter  costs  addition  when  operators  by t h r e e  the w i l l i n g n e s s of the b l a s t i n g  (energy)  blasting  do w i t h  downtime  On  groundwater  h a s became more a  operations  angle.  i s governed  mine  available during  production  mass  they  that  i s used  cases,  powder  geology,  i n the sense  blasting  mining  stability  Steeper represent  Many  the fact  not g e n e r a l l y  Consequently,  mine  they  and s t a b l e reduced  operators that  coincide  have  a more with  are planning  the blast  3  optimization  programs.  Blasting the  rock  mass.  blastability (energy) of  the  optimization  of  engineer  must  the  rock  allocate  to  Consequently,  blast  performed  trial  drawbacks personel general  or  practical A the  and  rotary  rock  b i t as  strength  of  rock  mass  body  of  Mineral  a  a  the  interpreted  available to  yield  The  is a  nature  very  in order  reduce  be  the  by  extent major  skilled  inacurate,  method  to  the  handicapped  i t requires  i t may  are  processes.  proposed  A l l are  a  a  Professor  has  been  practical  but to  and  too  i s just  therefore  the  useful  rather  It  CO.  not  directed method  of  blasthole d r i l l  indication  of  the  based  the  measure  of  into  is believed  the  assessing  i s not  takes  of  of  toward  utilizes a  Brawner  Department  method  evaluate  whole.  from  by  proposed  tool  mass,  p r o p e r t i e s as  data  and  property  testing rock  error  Engineering  Columbia,  simple  mass  powder  inhomogeneous  therefore  finally,  Process  blastability.  particular  and  project, directed  of  certain  operation.  British  determination  been  is costly,  or  the  o p t i m i z a t i o n programs  have  or  determine  blastability  and  equipment;  mining  and of  method  specific;  research  mass  the  c h a r a c t e r i z a t i o n of  i t a  the  trial  blastability  special  in a  Mining  costly  error approach.  as  site  University  rock  mass  such or  as  s e v e r a l methods  rock  of  of  generally  the  because  determination  task.  of  and  However,  difficult  determine  the  blasting  the  Nevertheless,  with  The  factor.  rock,  starts  on  any  tricone the  account  that  the  the  logs  could  rock  mass  a l l large be  4  blastability. purposes  data  by t h e d r i l l e r  additional depth  These  expense.  and d r i l l i n g  pressure).  From  are already  and consequently  It consists time)  these  collected  not r e q u i r e any  of the p e n e t r a t i o n  and the weight  data,  does  f o r other  t h e Rock  rate  (hole  o n t h e b i t (down  Q u a l i t y Index  (RQI) i s  defined as:  RQI  = W/PR  where W  = weight  PR  and  Afton for  Mine  on t h e b i t  = penetration  rate  t  = drilling  d  = hole  P  = h y d r a u l i c down  with  Very  = Wt/d - P t / d  W  depth pressure  = f(P) + Cte  good  results  when  perimeter  time  were  correlating  blasts.  obtained RQI  by J o h n  and optimum  C. L e i g h t o n a t design  powder  factor  5  1.1  THE  1980  This Leighton  extent  variable  of  analysis the  average  graph  shown  optimum each  summarizes  the  reports  published  by  program  and  In  a  the  while  domains the  the  was  powder  over  (energy) the  pit  drill  during  Leighton  1.1-1).  within  each  derived,  then  (energy)  factor  the  for  a l l o c a t e d to  only  The  design nine  showed  that  distribution.  The  representing  perimeter  the  in  to  statistical  domain  1.1-2  was  the  performance  of  RQI  Mine  s i x months,  representative  the  Afton  f a c t o r was  (Figure  distribution  in Figure  versus  of  at  c o n t r o l l e d b l a s t i n g procedure  monitoring  RQI  value  the  powder  of  performed  period  optimized  where  was  the  blasting  particular  in  domain  at  Mine. The  reported 1)  following by  The mass  "  field  design  domain  Afton  "  of  PROJECT  3  1981.  left  geological  briefly 1  first  summer  RESEARCH  1982 " .  standardized the  1982  section in  The the  TO  2)  is a  Leighton action  a  properties  reflect  the  basis.  "  rotary and  that  rate  carefully  blasthole,  the  will  serve  as  condition.  "  the  the  of  first  two  i s a f f e c t e d by  the  hydraulic  Rock a  drill  structural  competancy  Provided are  of  conclusions  :  1  of  quotation  monitored Quality  reliable  geology, rock  down when Index  on  a  causing  and  drilling  i n d i c a t o r of  rock  it  to  qualitative  pressure  can  major  be the  penetration  each  calculated rock  mass  and  6  c E i  s.  8-  c E i  (?) o_  350-  300-  x UJ  6-  Q  250-  Z  >_l <t ID O  o o oc  z <  200-  o < i  150-  I  i  >  3-  I00  O Q J  O Q  <  O Q  o Q  Q  m i  CD  >  z z < I  > Z  < 1  z< >  oo  4-  2.26- -  i  <  o Q  O Q  <  z <  O O  Q  > Z  o Q  o  DOMAINS  FIGURE 1.1 — I - ROCK QUALITY INDEX VALUES FOR EACH DOMAIN RANKED IN ORDER OF INCREASING QUALITY. ( after Leighton ) 1  7  FIGURE  1.1-2= PROPOSED  CORRELATION BETWEEN ROCK  QUALITY INDEX AND POWDER FACTOR AT AFTON MINE, (after Leighton ) 1  8  It  was  only  also  valid  (chisel  for  shape  discussion RQ I ,  the  obtaining RQI  to  specified  WC,  open  use  particular BE  on  of  a  the  40R).  topics drill  predict  grinding  rate.  mining  project.  site  and  the  the  and  at  this  drilling left  effect  recorder  as  possibility  Leighton  specific  and  Leighton  to  performance data  be  b i t design  related  accurate  may  r e l a t i o n s h i p was,  Finally,  more  relationship each  the  that  b i t wear means  of  considered  i t should  equipment  the  of a  be  time,  on  of  using  the  the evaluated  at  9  1.2  THE  1982  This  1984  research  following The  TO  the  RESEARCH  project  was  p u b l i c a t i o n of  objectives  Leighton's  the  2)  define  3)  i n v e s t i g a t e the  influence  i)  accuracy  the  iv) Backed  the  by  The  during  where  1)  field  The located 7/8  inch)  drills. situ  1982  report . 1  correlation  of of  (if  major the  any)  parameters  drilling  data  equipments designs  behaviour  during  literature of  Silver  Silver  229  Benches  rated  was  Mine  northern and  free  Geolograph  testing  fracturing  generally  the  blast  obtained,  the  Equity in  thesis  applicability  summer  September  drilling  review,  1983  in  the  three  & blasting  field open  program  pit  was  operations  Columbia.  from  Equity  mass  the  of  drilling  extensive  author  recorder  of  different rock  an  British  of  different  the  performed in  level  the  iii)  limits  in  following:  evaluate  the  validity  undertaken  1)  ii)  the  were  PROJECT  mm are  of  charge,  Pioneer  performed  (5  British  is a  were  The  performance three  mines  :  silver-antimony-gold  diameter  (16.4  They  are  bits  on  variable.  from  to  good.  The  using  property 200  mm  Bucyrus  Erie  The  intensity  of  blast  results  were  ft) high.  is highly fair  Company.  Columbia.  inch)  5 m  drill  weeks)  Mine  (9  a  Simple  modifications  of  (7 40-R  in-  the  10  blast  d e s i g n were  implemented  drill  performance  recorder  diameter  2)  The  inch)  Mine  (5  Lornex part  of  diameter  the bits  fracturing  modifies  the  optimum  performance  3)  The  is a  installed  and  large  the  on  45-R  drills.  five  BE  i s intense,  recorder  Westar  of  was  (3  Mining  the  also  project.  229  mm  (9  between  the  factors  could  managed  blasting  f o r the  problems recorder.  coal be  seams used  A inch)  ruled  out  The  at  this  this  (9  the  7/8  site,  alteration blast  used  Greenhills  bits  also  designs  The  were  d r i l l  site.  on  suggest from  seam was  property  Columbia. Reed  different  scale the  mass.  of  mm  in  weeks)  procedure  medium  degree  located  250 At  proposed.  inch) diameter the  using  were  (10  of  the  rock  in southeastern British  characteristics  producer  are  modifications  Mine  copper They  located  pile  on  province.  strength  Greenhills  5/8  research  weeks)  Mine  although  not  was  the  drill.  Lornex  central  during  to  of  installation  coal  They  are  using  drills.  seam.  270  powder  to produce  the  (energy)  a  fine  well  muck  Calibration  d r i l l  mm  rocks  N e v e r t h e l e s s , the  shovels. of  mine  The  sedimentary  different  designed  hydraulic  new  SK-60II  beds  that  is a  performance  11  Data each  approximately  Each  first  covers  part  of t h i s  a particular  undertaken.  Chapter  understanding  of the rock  the  different  parameters  The  different  failure  is  concerned  with  being  to review  rate,  from  factors  that  in  detail.  is  also The  results, program.  Two  contains  reviewed  that  failure  from  process. that  part  deals  rock  mass  part  of t h i s  analyses  development. Chapter  Three  objective  the operating  the t h e o r e t i c a l  i s always  with  behaviour  and  The p r i n c i p a l  the b l a s t i n g  during  analysis  present.  i n f l u e n c e the e x p l o s i v e consumption The  that  influence the penetration  between  process  review  reviewed.  p r o p e r t i e s through  drilling  chapters.  the  influence fracture  the d r i l l i n g  first  toward  behaviour  are also  mass  three  of the l i t e r a t u r e  i s directed  mass  relationship  the p r a c t i c a l of t h i s  aspect  a l l the factors  The  chapter  thesis  criteria  the rock  parameters. and  1200 b l a s t h o l e s w e r e  site. The  was  from  The  last  process.  are  The  presented  the blasting  process  covered. second  recommendations  thesis  presents  and c o n c l u s i o n s  the  procedures,  of the f i e l d  research  12  1.3 1.  REFERENCES LEIGHTON,  J.C.; Development  Drill  Performance  Factors, 2.  LEIGHTON, a  Master's  J . C . ; BRAWNER, Correlation  Controlled Bulletin, 3.  LEIGHTON,  Blasting  Degree  U.B.C.,  CO.;  Between  August  Thesis, STEWART,  Rotary D r i l l  Powder  Powder  for Controlled  Mechanics  D.;  Rotary  Powder August  Development  Performance  Factors  ,  Factors  from  1982 of and  C.I.M.  1982  J.C.; P r e d i c t i n g  Rock  Between  and C o n t r o l l e d  Blasting  Performance  of a C o r r e l a t i o n  Symposium,  Blasting, Vancouver,  Rotary  Drill  14th Canadian 1982  1 3  CHAPTER  2  '14  2.0  ROCK  The While  FRAGMENTATION  fracture  the design  eliminate blasting rock  of rock  of underground  fractures,  other  and g r i n d i n g  i s found  failure  mining  appropriate  of b r i t t l e  rock,  on  similitude  between them  drilling failure  i n rock  processes toward  should  to occur  in  mining " . 1  attempt  like  6  to  drilling,  the f a i l u r e  of the  Within  when  increasing  accepted  when  the shear friction  friction bridges  exceeds  thus  explanation developed  an  of a c t u a l empirical  behaviour  However,  of both  failure  is  load  the  t o sudden  failure.  failure,  Mohr's approach  He  predicts  failure  on  any  effect  of  cohesion  the combined stress  reviewed  failure  brittle  of  times  p a r t i c u l a r plane.  results.  of  First,  to resist  leading  t h e gap between t h e o r e t i c a l and It i s later  and the  : "Brittle  7  of the rock  minimum,  that  Hoek  of  mass  analysis  mass.  deformation."  ( e f f e c t i v e normal on  processes  the rock  Quoting  and p r a c t i c a l .  angle)  mass.  fracture  on  theories  stress  of the rock  to the d e t a i l e d  the a b i l i t y  the published  more  prior  action  i s usually  the p r i n c i p a l theories  the influence  be d e f i n e d .  with  deformation  to review  the d i f f e r e n t fracture  and b l a s t i n g  decreases  rock  openings  are directed  properties  and  consideration  mass. It  said  i s a prime  the tangent  i n order  strength  to obtain  a  Hoek  and  criterion  that  predicts  mass  and  concept  of the  Finally,  the rock  plane  of the  The G r i f f i t h  real  i s the  better  Brown  intact  the  rock  15  specimen. The and  small  stress the  s t r u c t u r a l c h a r a c t e r i s t i c s of scale  are  expected  distribution.  normal  cohesion  of  stress the  The  of  produce  stress  applied,  plane  to  the  the  rock  local  concentration  frictional  weakness.  on  both  anomolies is a  resistance  large in  the  function and  the  of  16  2.1  REVIEW  2.1.1  OF  Rock  Under  Mass  small rock in  This  large  mass  the  variation  in  nor  the On  a  inclusions,  and  The  thus  (Ex.  of  the  the  and  the  orientation crystal  in a  a  value,  both  function  of  discontinuities types,  the  in-situ  structure  stress  variations, orientation  influence  the  stability  or  history and  also  affects  makes  each  of  continuity rock  mass  site  Weathering) the  physical  Coulomb-Navier  critical  on  preferred  i t s behaviour,  generally  when  occurs  and  Geological  rock  i s mainly  properties  associated  Coulomb-Navier  material  of  usually  boundaries  are  The  of  engineering  is  Heterogeneity  position  the  The  rock  is a  structural imperfections.  2.1.2  the  other  propagation  internal rock  that  from  d i f f e r e n t rock  scale,  will  b r i t t l e n e s s of  variations  as  between  grain  growth.  different.  such  smaller  constituents  fact  Fracture  magnitude  voids,  properties  the  differs  isotropic.  boundaries  etc.  fracture  to  scale.  field,  mineral  behaviour  i s due  properties  space,  of  rock  homogeneous  and  MECHANISMS  Characteristics  stress,  materials. neither  ROCK F A I L U R E  the  Theory  theory maximum  i . e . , the  of  by  with  of  shear  the  i t s constituents  B r i t t l e n e s s and its  and  weakness  of  heterogeneity.  Failure  predicts  shear  caused  that  stress  strength  failure at  of  one the  will  point  occur reaches  material.  17  Moreover, angle  i t i s predicted  between  statement  t h e maximum  from  this  equals  the shear  occurs  in brittle He  failure  plane  internal  friction.  compressive  but  at a  ratio  the  shear  value,  a  largest the  Mohr  lower  stress function  material.  normal  stress  represented failure  on  The  that  the f a i l u r e  theory  stress  of  has  theory.  Note  that  and  on  between  with  will  on t h e  coefficient that  strength,  this  fracture a  the shear  when  limiting  plane,  the t e n s i l e  or  i f the  strength  stress  of  and the  e x p e r i m e n t a l l y and i s  failure.  is a  sedimentary  are illustrated  this  predicts  reached  The  i s r e p r e s e n t e d on a Mohr  envelope,  never  rock  the t e n s i l e  equals  determined  by t h e e n v e l o p e  line  that  experiment.  stress  relationship  straight  to  in tension  acting  a material  plane  of t h e normal  h a s t o be  by  possible  t o modify  of the  the  Failure  predicts  principal  criterion  sandstone  of  latter  introduces the  than  indicated  This  situation  stress  Coulomb-Navier  i s larger  than  Theory  theory  tensile  The  a  strength He  bisect  strength  proposed  the normal  the shear  strength  The Mohr  The  that  to i t smagnitude.  the  2.1.3  the shear  Navier  will  It i s also  i n compression,  material.  increases  proportionally of  strength  that  plane  stresses.  by e x p e r i m e n t .  theory  postulates  the f a i l u r e  a n d minimum  i s not v e r i f i e d  demonstrate  theory.  that  special  rocks  a curved  diagram  case  like  Coulomb-Navier with  a  o f t h e Mohr  l i m e s t o n e and  Mohr  envelope  whereas  18  more  brittle  rocks  envelopes.  The  the  plane  failure  failure.  2.1.4  failure  the  the  on  a  used  to  failure In  fracture  stresses  on  though  the  that  no  that  cracks  when  the  the  the  a  were  low of  larger  stress  value  of  local  fails  to  explain the  the  strain some  the  direction  the  material  strength  perfect  cracks  of  of at  i s due of  strength  worst  in  However,  predicts  theory rocks  the  He  is  compared  to  tensile oriented  concentration  material  Griffith  the  that  randomly  He  also  reached or  even  postulates assumed  Failure  material  rock  hypothesized  high  the  space.  energy.  an  to  cracks.  of  with  the  orientation  experimental  a  theory  explain  stress  of  lower.  the  oriented  to  small, a  the  Griffith  crystals.  create  i s much  consider  scale  strength  criterion  the  published  extremities  equally  than  in  straight  the  theories  whereas  materials  The  having  value  Mohr  microscopic  i s c a r r i e d across  crack  compressive  the  the  theoretical strength  applied  force  First,  at  cracks.  overcome  stress  Griffith  brittle  induced  microscopic that  of  of  predicts  possess  Failure  scale,  1921,  explain  of  and  theoretical strength  that  quartzite  also  state  Theory  macroscopic  the  and  2.1-1)  Coulomb-Navier  behaviour.  later  granite  criterion  and  Griffith  approaches mass  Mohr  (Figure  The  The  like  occurred a  a  Griffith  stress  limiting theory  results. an  increased  increase  of  confining  the  triaxial  pressure,  but  19  FIGURE 2.1-1 « GRAPHICAL REPRESENTATION OF MOHR THEORY OF STRESS  CONDITIONS FOR  FAILURE  ROCK!  OF INTACT  (after Hoek and Brown^)  20  many  scientists  predicted. Griffith  observed  Also,  with  criterion  increase.  Again,  the theory  the G r i f f i t h  strength  should  strength  ratio  distribution does  theory  be e i g h t  reported  values  between  t o be  McClintock possible  f o r the cracks  stresses  due t o f r i c t i o n .  strength  of the rock  ends  of the cracks.  pores  will  modified of  modify  theory  Walsh  between  will  increase.  compressive  the t e n s i l e " S t r e n g t h of the rock.  Even  cracks  developed  to close  that  carry  stresses will the stress under  distribution  p r e d i c t s a compressive  tensile  the theory  experiments.  the idea  fluid  to  when a n i s o t r o p i c  and thus  These  strength  i s considered,  with  by r e d u c i n g  rock  propagation  and B r a c e . crack  surfaces  across  develops  local  exceed  the strength  begins  t o grow,  the grain  i t  is  normal  and  shear  increase the  concentration pressure  i n the rock.  to tensile  at the  i n the This  strength  by t h i s  ratio  i s described shear  i s p r o p o r t i o n a l t o the normal  force  these  surfaces.  force  theory  resisting  Non-uniform  stresses at microcrack of the surrounding  but only  size,  explained  The f r i c t i o n a l  9  transmitted  of  the  of compressive  the stress  the  10. Fracture  by  indicates that  Similarly,  than  of the rock  the real  i n accordance 8  pressure,  the strength  5 a n d 22.  and W a l s h  of pore  of strength  underestimates  times  of the G r i f f i t h  n o t seem  augmentation  the presence  predicts that  Finally,  Experiments  a larger  to a length  and stops  when  tips  stress that  materials.  i n the order  i t intersects  i n the  eventually  The  crack  of magnitude  other  cracks.  21  The  direction  maximum less  of propagation  compressive  i s generally parallel  stress.  I f the load  favorably oriented microcracks  initiated. produces regions  However,  no  a macroscopic of high  crack  single  fracture, density  i s increased,  will  crack  be  initiated  other or r e -  grows c a t a s t r o p h i c a l l y  but under  will  to the  create  sufficient  and  stress,  a macroscopic  shear  plane. The  Griffith  parabolic the  Mohr  Griffith  envelope  2.1.5  that  envelop.  theory  on a Mohr  Hoek  As m o d i f i e d  both  the o r i g i n a l  point  dealing with  error.  They  correlate stress,  of  these  their  with  the o r i g i n a l  and the f a i l u r e  intact  of t h i s  derived  experimented  both  by a  by a  Walsh,  straight  data  Criterion  Griffith  the rock  Nevertheless  a n d Brown  and  and p r o p a g a t i o n  and m o d i f i e d  i n the development Hoek  representated  i s represented  initiation  d e s c r i b i n g the f a i l u r e 2.1-2).  be  by M c C l i n t o c k  Empirical Failure  studied crack  (Figure  may  diagram.  a n d Brown  when  criterion  of f a i l u r e  Hoek  satifactory when  failure  mass,  and  t h e o r i e s were but l e s s  laboratory  the  empirical failure criterion  i n order  Griffith  theory,  under  situations.  In s p i t e  of the absence  of a  relationship  between the e m p i r i c a l c o n s t a n t s  starting  by  fitting  under  1 0  criterion.  curve  produced  accurate  specimens  t h e o r i e s were  failure  concluded  trial  and  to  tensile  compressive  stress  fundamental included  i n the  22  Modified Griffith theory  O i l  -50 0  U  I  .  100  ILU  LJULi  200  300  EFFECTIVE  I"I  i  400  i  500  I  ii  i  600  NORMAL STRESS 0~:MPa  FIGURE 2.1-2 t MOHR CIRCLES FOR FAILURE OF SPECIMENS OF QUARTZITE TESTED BY HOEK. ENVELOPES INCLUDED IN THE FIGURE ARE CALCULATED BY MEANS OF THE ORIGINAL AND MODIFIED GRIFFITH THEORIES OF BRITTLE FRACTURE, (after Hoek ) 10  23  criterion  and any p h y s i c a l  criterion  adequately  criterion  defines  failure  as a  uniaxial mass  compressive  i s assumed on  principal  stresses  strength  the intermediate mechanism  are always  failure  criterion  of the rock  both  a n d NGI  rock  classification  permitting Table  1)  mass  the evaluation  rock  2.1-3)  and that  empirical CSIR  of the  principal stress  pressure  t h e major  and  constants.  minor  The  i s related  systems,  h a s no  obtained  i n the rock.  mass  of the e m p i r i c a l  at  the  the e f f e c t i v e stresses,  or j o i n t  The  principal stress  specimens  (Figure  the  behaviour.  principal stress,  intact  constants.  that  the pore  of  fracture  of t h e major  of the minor  the f a i l u r e  considering  rock  the magnitude  function  influence  by  predicts  a n d two e m p i r i c a l It  c h a r a c t e r i s t i c of t h e rock,  with  thus (See  24  T  Trlaxial compression  cr,' = o-3+VmCta +sq:  2  3  Mohr envelope  2.0 •Ocm Uniaxial compression tTcs  *rru  (Cot^'-Cospf,')^  CO CO LU CC \-  = \ /s e r f  co  U n i a x i a l  *—^tension CT-t = '/2 CT(m-\/m2+4s) i l L 0.5 L5 -0.5 MINOR PRINCIPAL STRESS O3' c  0.5 1.0 1.5 2.0 2.5 3D EFFECTIVE NORMAL STRESS 0~'  FIGURE 2.1 -3 • GRAPHICAL REPRESENTATION BROWN FAILURE CRITERION, (after Hoek ) 10  OF HOEK AND  25  TABLE 1 APPROXIMATE RELATIONSHIP BETWEEN ROCK MASS QUALITY AND MATERIAL CONSTANT  (after  t S <  Hoek and Brown  7  UJ  Empirical Oj t  failure  " 03  +  " A  0 c  criterion  /mo 03 c  ("/  0  -  +  so  c  T )B  where T - i(m - Jm* +~Tt)  1- >— o oc  I  u  OC  ui c i I- u i < a.  z o  O  _ l  CD  U J  ui oc > u < UJ <_> 0  < >  "g.3  ^1  _ l Ul  to u i _ i a .  o < a oc h- _ J V) UJ </i >- > 3 oc U J  o  I— u —o - J DC  o >oc o a Ul 1 /1 z 3 — a a.  <u  O U O l l J ui u  — tn X  X  .a  >- .< t1  <  » -1 < 1/1 tX in u >o a: c£ u  c 6  •8  (0  1/1  I SC < U H O U l oc 1 U l O Z Z — < - I _ l  • l/l < Z J Iz a in — u i v  5u 2  0  S£  o o — v> ui zu u o  V) 0 . O  1 UJ Z — a: >_l O o. ul  <_> u >- < -tS < 2 -I > B z o oc < "a U l DC O U l t? oc H o -1 Q <  )  J cc  i3  —  CC  CJ  u  Ul ( J — l/l — X OC _ l 0 . < - I  £ 8  *  -W C N O « H »Q » 3  oc o < a u oc r  INTACT ROCK SAMPLES  m - 7.0  m - 10.0  m - 15-0  ll.  tn - 17.0  m - 25.0  Laboratory free from  s - 1.0  s - 1.0  s - 1.0  s - 1.0  s - 1.0  A - 0.816  A - 0.918  A - 1. 0***»  A - 1.086  A - 1.220  B - 0.658  B - 0.677 >  B - 0.692  B - O.696  eize specimens joints  CSIR r a t i n g 100  B - 0.705  T - -0.0^0  NCI r a t i n g 500  T - -O.HO  T - -0.099  T - -0.067  T - -0.059  VERY GOOD QUALITY ROCK MASS  m - 3.5  m - 5.0  m - 7.5  m - 8.5  m - 12.5  Tightly interlocking undis turbed rook with unueather ed joints at ±3m.  s - 0.1  s - 0.1  s - 0.1  s - 0.1  5 = 0.1  A - 0.651  A - 0.739  A - 0.81(8  A - 0.883  A - 0.998  CSIR r a t i n g 85  B = 0.679  B = 0.692  B - 0.702  B •» 0.705  B - 0.712  NGI r a t i n g 100  T - -0.028  T - -0.020  T = -0.013  T = -0.012  T - -0.008  GOOD QUALITY ROCK MASS  m - 0.7  m - 1.0  m - 1.5  m - 1.7  m - 2.5  Freeh to slightly weathered rock, slightly distux-bed with joints at 1 to 3m.  s - 0.00 )  s - 0.00<i  s - 0.00*1  s - 0.00«l  s - 0.00*1  A - 0-369  A - 0.1127  A - 0.501  A - 0.525  A - 0.603  B = 0.669  B - 0.683  B - 0.695  B - 0.698  B - 0.707  T - -0.002 m - 0.50  CSIR r a t i n g 65  1  NGI r a t i n g 10  T - -0.006  T - -O.OOli  T - -0.003  T - -O.O02  FAIR QUALITY ROCK MASS  m » 0.1*1  m - 0.20  m » 0.30  m -  s » 0.0001  s - 0.0001  s - 0.0001  s - 0.0001  s - 0.0001  A - 0.295  A = 0.3'*6  Several sets of moderately weathered joints spaaed at 0.3 to lm. CSIR. r a t i n g kU NGI r a t i n g 1.0 POOR QUALITY ROCK MASS  numerous weathered joints at 30 to 500mm with some gouge - clean waste rook. CSIR r a t i n g 23 NGI r a t i n g 0.1 VERY POOR QUALITY ROCK MASS  0.3k  .**  0>+> 0  A - 0.198  A - 0.23^  A - 0.280  B - .0.662  B - 0.675  B - 0.688  B r 0.691  B - 0.700  T - -0.0007  T - -0.0005  T - -0.0003  T - -0.0003  T - -0.0002  m = 0.0't  tn  m » 0.08  tn «= 0.09  tn - 0. 13  s = 0.00001  s = 0.000O1  s - 0.00001  s - O.OOOOI  s - 0.00001  A = 0.115  A •» 0.129  A - 0.162  A » 0.172  A - 0.203  B - 0.6*16 T - -0.0002 tn - 0.007  - 0.05  B - 0.655  B - 0.672  B - 0.676  B - 0.686  T - -0.0002  T » -0.0001  T - -0.0001  T - -0.0001  m - 0.010  m - 0.015  in - 0.017  m - 0.025  Numerous heavily weathered joints spaced < SOnrn with gouge - waste with fines.  s - 0  S - O  S -0  A - 0.0*12  A - 0.050  A - 0.061  A - 0.065  A - 0.078  CSIR r a t i n g 3  B - 0.53*1  B - 0.539  B - 0.5^6  B - O.S>iB  B - 0.556  NGI r a t i n g 0.01  T - 0  T - 0  T » 0  T - 0  T -0  S »  0  s -  0  26  2.2  DRILLING,  In rock  the majority  mass  through of  to a  extraction  sizes. to  levels,  larger  fragments.  degree  intensity The function degree  in a  stress,  a very  The  on  relative  energy  to  t h e same when  1  1  used  "  1  .  field  size  of  fragments.  of the rock  under  brittle  type,  At  small  scale  in  function  of  scale.  in the fragmentation process of  fines  I t s h o u l d be  (Figure  produced  realised  rocks exceeds  2.2-1).  how  low-  resulting  and of the  a  and  non-efficient  on  amount  imagines  stress  This  is a  in drilling  rock  one  3  i s transmitted  of t h e fragments  larger  consumption  fragment  powder-like material.  i s of a  a  In a l l  However,  of  energy  failure  fine,  size  of the r e l a t i v e  understood  that  range  a non-homogeneous  the f a i l u r e  fineness  reduction  facilitates  i s the best. a  of t h e  i s done  the size  concentrated load.  result  of high  jointing  energy  and h a n d l i n g  limit  produce  under  of h e t e r o g e n e i t y of  of  blast  which  produces  stress  the  a certain  p r o c e s s and a non-uniform  the zones  the reduction  the plant,  to the fact  produces  distribution  compression  At  and g r i n d i n g  compression  load  fragmentation  for loading  of the product  i s related by  operations,  components or c h e m i c a l a c t i o n .  size  blasting  concentrated  In  size  below  of v a l u a b l e  the rock  energy  of mining  fragments  This  GRINDING  and b l a s t i n g .  a uniform  drilling,  AND  suitable  drilling  the rock  cases,  BLASTING  This  the size  and  that  their the  the energy  statement  of the rock  is a  used  i s well specimen  27  I 0,01  I  0,1  I  I  l  10  SIZE (mm)  I  100  I 1000  1 - DIAMOND CUTTING  2 3 4 5  - PERCUSSIVE DRILLING - ROLLER BIT BORING - GYRATORY CRUSHING - EXPLOSIVES  FIGURE 2.2-1 » COMPARISON OF ENERGY REQUIREMENTS FOR VARIOUS FRAGMENTATION PROCESSES, (after Page ) 12  28  to  be b r o k e n  the  influences  imperfections  increases continue note  that  processes such  in strength the size  the energy i s also  a  that  free  optimum c o n d i t i o n s need  the least  of  results.  The  of  the fragmentation  more  i s reduced, the  energy  material to  i t i s important  to  breakage  of other  in drilling  parameters  and the depth  of the  in blasting.  of d r i l l i n g  and b l a s t i n g a r e the  of energy  chapters  processes  and  i n a l l the rock  face  amount  following  needs  o f a number  geometry  of a  the size  Nevertheless,  consumption function  As  are reduced  and, t h e r e f o r e ,  reduction.  or presence  The ones  i n the s t r u c t u r e  as the i n d e n t o r ' s  charge  i t sstrength.  will  to produce deal  in drilling  and  with  a given  set  the analysis  in blasting.  29  2.3 1.  REFERENCES CLAUSING,  D.P.;  Comparision  Mohr's  Failure  Mechanics, of 2.  Mines,  TANDANAND,  S.;  N3,  3.  FAIRHURST,  July  F.  E.;  Brittle  22nd  Rock,  U.S.  W.I.;  in  School  editors,  F.A.;  Rock  and  John  WALSH,  on  Rock  1982 and  &  the  Sons,  Ground  Design  editor,  Control,  Engineering,  of 1967  Dept.  McGill  Excavation  in  Rock,  & M e t a l l u r g y , London,  Pressure,  W.F.;  Strength  1976  J.B.;  Berkeley,  BRACE,  AIME,  Underground Mining  Rock Technology,  Symposium  Metallurgical  of  of  Tensile  Wiley of  on  1981  Mechanics  Montreal,  Under  Mechanics,  U.S.  Rock  and  Institute  of  Philosophy  BROWN, E . T . ;  J.B.;  Rock  Mining  Symposium  editor,  i n Rock,  R.G.K.; A Mining  2 3rd  Goodman  DUVALL,  McCLINTOCK,  on  Given  Fracture  the  An  Institution  WALSH,  ; Rock  Examination  J.L.;  L.;  SME,  and  July  University,  9.  Cummins  Massachusetts,  of  8.  Drilling,  Cambridge,  MORRISON,  HOEK,  of  Handbook,  C;CORNET,  Structures  7.  Colorado  with  1973  Mechanics,  6.  the  Massachusetts  RATIGAN,  OBERT,  of  Symposium  Mechanics,  of  5.  ,3rd  Theory  1959  Principles  Fragmentation,  4.  Griffith's  Criteria  Quarterly  Engineering AIME,  of  Friction 4th  1962;  on  Griffith  National pages  Mechanics  of  1015 Rock  Congress -  1980 Cracks Applied  1021  Deformation,  30  Rock  Mechanics  Symposium,  Sikarskie  editor,  ASME,  1973 10.  HOEK,  E.; Strength V33,  11.  KHALAF,  N3,  of Jointed  1983; p a g e s  F . ; ABOUZEID,  and  Blasting  Symposium  on Rock  Missouri-Rolla, 12.  PAGE,  C.H.;  Blasting  report, 13.  YOUNG,  Rock  Utah  Mechanics,  Engineering  Between  Indentation  University  of  1980  Robertson  Fragmentation  on Rock  Geotechnique,  R o c k s , 2 1 s t U.S.  and Comminution,  fragmentation  Symposium  Analogy  on B r i t t l e  May  Steffen,  C.; R o c k  Masses,  187 - 2 2 3  A.Z.M.;  Tests  Rock  and  - Needs  session  Kirsten and  Possibilities,  o f t h e 1 7 t h U.S.  Mechanics, Experiment  unpublished  University Station,  of Utah,  1976  31  CHAPTER  3  32  3.0  THE  DRILLING  Drilling mining. and to  It  i s the  i s also  consequently the  and  site  initial one  the  of  the  the  process  are  overall  sequence  highest  Different  parameters  minimizes  operating  drilling  conditions.  operating  that  PROCESS  operating  in order  and  costs  i s optimized  combinations  tested  costs  i n open p i t  accordingly  of  to  maximizes  involved  bit  designs  define the  the  one  penetration  rate. The  rotary d r i l l s  the -knowledge useful  rock  The  use  not  new,  the  field  or  of  of  mass a  tricone  of  of  the  controlled  by  components  and  the  order  the  rock  have  to  tricone  derived  recently, to  the  a  part  of  a  pure of  s t r e s s e s a p p l i e d on  understand  penetration  proposed  and  them.  action  by are  the  to a  of  very a  review  is therefore These  single  presented  the  mass  overall  large. rotary bit  theoretical  tooth. in  bit  rock  the  Different second  an  design  problem  tricone the  is  drillability  The and  tool  restricting  different  b i t design  i t i s necessary  were  mechanical  s t r e s s e s are  the  testing  chapter  the  with  performance.  rock  of  and,  drilling,  considerations.  strength  the  drill  valid  this  mass  rotary  prediction  basically and  from  rock  scientists  b i t design  whereas  rock  been  of  i n f l u e n c e s the  mass, of  not size  process,  mechanisms models  the  be  first  tricone  behaviour  drilling In  The  are  undisturbed  r o t a r y b i t as  application  considerations  failure  can  until  abrasiveness.  the  principles  data  although  overview  on  the  face  33  section  of t h i s  specific In mass  energy  chapter.  in drilling  addition,  drillability  concerned  with  of  a wide two  drilled used  the mechanical  and the o p e r a t i n g  tricone covers  drillability rotary  on  number  that  influence  in this  of the rock  properties  rock  research  of s c i e n t i s t s  is available.  related  section  mass  have  been  drillability  These  of the rock  factors are mass  to the p a r t i c u l a r d r i l l i n g  i s followed  in practice.  formulas.  t h e Rock  of  being tool  parameters.  drilling  drilling  discussion  large  of l i t e r a t u r e  and the f a c t o r s  The  importance  the determination  body  types:  a  the concept  of the f a c t o r s  i s of prime  Fortunately,  on  follows.  the study  project.  and  A discussion  Finally,  Quality  This  by a  fifth  the chapter  Index.  review  of the  section concludes  also with  a  34  3.1  TRICONE  Howard August one 1)  ROTARY  R.  Hughes  10, 1 9 0 9 .  o f t h e most R o l l e r cone  years  because  BITS  patented  This  the f i r s t  invention  economical  rock  b i t improvements of s i g n i f i c a n t  was  later  were  over  design  steady  optimization  and of the b e a r i n g s .  bits  increased  rate  replaced  The is  principal  the space.  diameter  The s i z e  cases,  one p a r t  parts)  i s reduced  elements  b e made  in a  are properly  based  experience.  are  on p a s t  seldom  force  a l l parts  ultimate  tricone  rotary  importance  to give that  larger  mechanical  major  of a  life  roller  insert have  cone b i t  by t h e I n most  part (or  the various  over-all  the b i tdesign  stresses, than  i n the blasthole  rock  bits  in relation  the ones 3  i s mainly  of mechanical  i n which  designs .  component,  until  the best  i s t h e key t o r e l i a b i l i t y .  of each  carbide  i f another  conditions  of the m a t e r i a l ,  b i t used  twenty  of the c u t t i n g  components.  The f u n d a m e n t a l s  to withstand  i n other  the design  of other  claim  The severe  strength  encountered of  used.  3.1-  The s e l e c t i o n o f t h e optimum  balanced  Manufacturers  (Figure  3.1-2).  s e r i e s of compromises  performance.  t o become  i s determined  larger  b i t on  the past  and longer  (Figure  piece  and the s i z e  in size.  Today,  i n the design  of every  can only  results  bits  limitation  of the hole  dimensions  of penetration  milled-tooth  improved tools.  materials  largely  rock  penetrating  structure with  rotary  Also, Figure  design work to the  commonly the  simplicity  3.1-3 s h o w s a  industry.  The  r e l a t e d t o the rate of  OF DEVELOPMENT (arbitrary scale)  IMPORTANCE ro O  o  03  O  O O T " l —TI — i — I — r FIRST ROTARY ROCK BIT  cn  SELF-CLEANING CONES  CD CO  o o  o m  UNITIZED BIT BODY FIRST TRI-CONE BITS 01 "CONE OFFSETS AND SPECIFIC TYPES  >  OJ  H  o co m  O  01  on CD  -HARD ROCK -SOFT  FORMATION  -TUNGSTEN -JET  \ BITS BITS  CARBI  BITS  -SEALED  0> - S H A P E D  BEARINGS  INSERTS AVAILABLE  - S O F T INSERTS, JOURNAL BEARINGS"  co cn  37  WATER SEPARATOR SNAP RING AIR SCREEN A.P.I.R. TOOL JOINT RUBBER FLAPPER ASS'Y. CHECK VALVE SCREEN TUBE ASS'Y.  "0"RING NAIL LOCK RETAINING PIN JET NOZZLE GAGE COMPACT  MAIN AIR BLEED HOLE ROLLER BEARING PILOT PIN AIR HOLE TO PILOT PIN AIR HOLE TO BALL RACE APPLIED HARDMETAL SHIRTTAIL COMPACTS ARM JOURNAL ROLLER BEARING A  R  M  CUTTING STRUCTURE INSERTS BALL BEARING PILOT BUSHING APPLIED HARDMETAL APPLIED HARDMETAL THRUST BUTTON CONE  OUTER BALL RACE FLANGE  TUNGSTEN CARBIDE NSERTS  INNER BALL RACE FLANGE! JOURNAL ANGLE  FIGURE 3.1-3 » NOMENCLATURE  OF ROTARY BIT. (after Dresser Industries ) 4  38  penetration following  3.1.1  and  Journal  journal the  on  angle  hole the  journal or  journal  most  the  cone  diameter  Soft  rock  is defined  The  plane  defines  The  function  with  of  of  the  the  in  the  position  journal  in  of  journal  angle.  The  the  axis  the  i s the  of  bit  the  relation  the  size  is a  function  decreases  with  an  generally  the  the  point medium  on  drilling  rate  or,  drilling  rate.  the  formation wear  in  the  of is  the the  the  a  sliding  reduces  However,  the the  because  abrasive  For of  low  to  variation  in  skew  the  axis.  movement thrust amount  of  cones  formations  is  and  angle.  the a  by  The  angle.  axis.  offset result  introduce  and  for  scraping  a  the  given  function  of  accelerated side  a  designed  increases  is a in  is  and  cone  (Figure  offset  offset  gouging the  offset.  vertical  the  requirement of  the  bit  journal  bit  This a  is  angle.  subtended  provide  skewed  the  between  and  bit  journal  position  journal  rock  given  the  distance  angle  any  journal  journal  to  tricone  increase  journal  bits  a  angle.  horizontal  rock  slight  have  of  axis  angle  pin  of  cone  skew  to  element  termed  This  carbide  is described  Angle  position  design  action.  rock  bit,  also  as  through  soft  Skew  arm.  variation  pre-selected for  the  is a  position  bits  Another  3.1-4)  and  action  basic  angle  diameter,  plane  of  offset.  The  It  Angle  horizontal the  life  sections.  Bottom  of  the  load  to  39  DIRECTION OF ROTATION  FIGURE 3.1-4-TRICONE BIT OFFSET, (after Hughes Tool Co. ) 3  40  the  bearings.  3.1.2  Teeth  and  Tungsten drill  to  drill  structure high  cones  the  a  and  with  conventional  teeth  tungsten  first of  the  testing  carbide  a  this  carbide  footage. most  design.  Insert  of  manufacturers format i o n .  bits.  very  The  cutting  cylindrical  sintered  holes  in alloy  The  cost  after  cost  and  steel  differential  steel-toothed bit  utilized  bits  type  3.1-5).  rock  were  to  abrasion  bit.  a  1951  bit resists  is  labour,  component  spacing  to has  be  are  offset  drill  of  large  Tungsten  hemispherical  shape.  This  Information  and  achieved carbide  to  positioning Very  In  Appendix  as  a  1,  ended is by  upgrade  are  profitable  with  bits  shape  gained  manufacturers  drilled.  been  listed  were  this  permit  formations.  models  of  formations.  shape,  b i t performance  range  rock  of  blasthole  wide  of  b i t and  strength  of  (Figure  type  significant  functions  inserts  of  machined  inserts  number  the  insert  that  tooth  Nevertheless,  for hardest  large  steel  in  drilling.  inherent  best  into  introduced  formations  Components  of  carbide  the  were  abrasive  loads.  blasthole  The  their  the  bits  hard  c o n s t i t u t e the  because  insert  tungsten  increased  diameter  still  a  Inserts  carbide, pressed  form  between  bits  of  compressive  tungsten  by  carbide  extremely  costly  Carbide  shaped  are  now  carbide used  different  f u n c t i o n of  the  rock  in  a  41  I  \  |  Z7  CONICAL TOP INSERT  \  |  ~7  ROUND TOP INSERT  FIGURE 3.I-5' VARIOUS INSERT SHAPES COMMONLY USED BLAST HOLE ROCK BITS, (qfter Toll ) 5  42  Hard As  rock b i t : previously specified,  were  found  drilling. is  small  without cones wear  the  most  The  compact  and  r o t a t e on  and  action  on  indentation Medium-hard  rate  The rate  with Soft  over  on  movement are  these and  a  rock  cone  high  surface  impact bits  thus,  closely  by  fails  the  compacts  load  so  the  abrasive  spaced  on  the  crushing-chipping  under  pure  impact  and  elements . 6  inserts end  of in  in this  with  these the  more  bits  type  of  compact  is faster  medium-hard  b i t possess  a  projection. than  the  The  ball  formation.  rock b i t : the  of  chisel design  these  penetration  replaces  rock  in hard  resist  offset  compacts  cutter  bits  successfull  of  i s no  to  i s obtained  conical  case,  cones  compact  The  carbide  compact  this  the  durable  projection  rolling  The  penetration  Medium-soft  most  true  and  end  rock b i t :  shaped  of  nosed  In  a  rock.  of  tungsten  bullet  the  penetration the  nose  There  i s minimized.  cones  The  efficient  permits  breaking.  h e m i s p h e r i c a l l y shaped  the  harder  shaped in the  insert softer  b i t was plastic  bits  are  slightly  and  the  scraping-gouging  crushing-chipping formation  rock  type  skewed  of  rock  found  the  formations.  to  increase  action  the  slowly  breakage  found  rotary b i t are  broad  bits.  rock b i t :  The  teeth  of  a  and  thin,  deep  soft and  formation widely  tricone  spaced . 5  In  1933,  the  development  43  of  rollercone bits  the  use of  the  cone  utilize Also,  summary, with  each  enough  sufficient  3.1.3  life  load 3  more  carbide  softness  will  r e d u c t i o n of efficiently  f o r more  deeper,  compact  with  bits  of the  have  compacts The  hardness  of compacts t h e number  the teeth  long  formations.  of the formation.  number  wear.  skew i s  Provided  as the formation  still  Finally,  can  easily.  and the length  when  as the formation  become  h a s t o be must  be  high  few  worn, a  be a p p l i e d t o t h e f o r m a t i o n  t h e nose becomes  shape  and  increases in  harder.  Bearings  bearings  transmit  Tough and  unit  the rock  i s not too l a r g e , that  made p o s s i b l e  allowing  in the softest  i f the t o t a l  sure  bits  the cones,  the tungsten  increases  load  formation  the rock  teeth  a corresponding  penetrate  increased  failure .  The They  an  t o make  roundness  on  the spacing  Even  tooth  provoke  carbide  success  of compacts  increases. so  soft  the teeth  with  without  Thus,  bearings,  used  increase number  longer  inter-fitting  teeth  to dislodge  lasting  In  size.  since  needed  been  longer  with  drilling  thus, is a  lead  are important  the weight  parts  to the inserts  conditions will to the f a i l u r e  rapidly  by  tricone  shorten  contact.  the bearing  bit.  of the u n i t  t h e b i t and t h e n a t u r e  rotaryb i t .  at the rock  of the e n t i r e  f u n c t i o n of the i n t e n s i t y  transmitted  in a  The  bearing  loads  of the bottom  life,  hole  44  environment.  R o l l e r cone  large  loading  dynamic  However,  the  influence does .  In  7  air  on  a  the  the  bearings  than  the  air  was  best  have  made  until by  and  the  number  the  same  this  appropriate  design  the  the  are  The  to  resist  ball  load,  especially  i f some  pilot  pin,  most  clean,  hold  race  roller  bearings  size  of  race. thus,  the be  A  maximum  the of  the  be  some on  i s to  ball  bearings,  fulfilled.  This  occurred  function  and  load.  must  carry  be  the  diameter  to  breakage.  must  loading  for  has  3.1-3.  radial  and  the  and  The  roller  the  dry  life  in Figure  number  support  has  important  by  and  flow.  compromises  pin  hand,  bearings  wear  of  shown  loading  ball  that  air  constraint the  life  the  considerations  of  bearing  found  the  particles.  bearing  bearing  to  dust  loading  into  f o r maximum  i s taken  unit  dynamic  of  balanced.  other  enough  sides  i f the  their  the  greater  injected  rate  to  substantially.  much  on  He  again,  bearing.  another  thickness  even  bit  the  water  3.1-6.  but  the  reduces On  of  segments  well  is  formation  with  are  of  large  case,  of  on  water  fluid  functions,  friction  be  effect  bearing  wear.  the  in Figure  function  must  that  avoid  increases  weight  rollers  thickness  fact  life  nose  and  The in  the  of  rollers  to  a l l elements  is a  spalling  but  the  operations,  circulation  specific  caused  rollers  of  shown  different  They  by  life  line  are  The  life  have  results  that  bit  to  some m i n i n g  the  the  found  demonstrated  8  lower  occasionally subjected  was  his  also,  which  are  environment  circulation  Medlock  bits  of  The  an  i s due of  the  the  end  hold  to  the  radial of  the  the cones  on  45  FIGURE 3.1-6' RESULTS OF ROLLER BEARING TESTS, (after Medlock ) 8  46  the  arm  journals.  The pilot  into  faced  a bushing  of r o l l e r s .  made  on t h i s  diameter  3.1.4  In  gage  the recent  wear  premature  of  the weight gage.  the b i t .  the  However,  b i tshirttail.  rapid  wear  the unit  wear  smooth,  lining  load  to a  large  Protection  d e s i g n has been  makes  improved  bit.  i s important. rock  causes  drilling  the three  on f i g u r e  force  under  3.1-7.  The i n f l u e n c e o f The d u l l n e s s  along cones  i s directed  normal  that  part  up wear  drilling  until  o c c u r s on gage carbide  i n order  the wall  or of  to encounter  The p r e s s u r e comes  on t h e b i t c r e a t e s  Tungsten  of the lower  a  on t h e b i t i n c o m b i n a t i o n  thrust  of a  f o r another  metal  bearing,  of the t r i c o n e  b e a r i n g s and speeds abrasive  t o keep  with the  toward  b i tbearings are designed  produced  of inward  inner The  gage  This  applied  i s available  of f r i c t i o n  i s made  and ground  i s an a n t i f r i c t i o n  The r e s u l t i n g  thrust  presence the  compacts  thrust  i s required.  wear  p r e s s u r e s a s shown  outward  no s p a c e  on t h e b i t p e r f o r m a n c e  inefficient.  rounded  alloy  In order  years,  the  from  a special  and S h i r t t a i l  o f gage  inward  outward  since  length  breakage hole  resists  arrangement  Design  minimize  with  steel.  of adquate  Gage  which  The b u s h i n g  of s t a i n l e s s  minimum  to  bearing  p i n , hard  fitted row  nose  to withstand  conditions. large  inserts  failure.  also  a r e used  of the s h i r t t a i l .  The  p r e s s u r e s on  complete  inserts  the center  affects  to delay  Without  heavy  FIGURE 3.1-7- EFFECT OF SIDE LOADS ON BIT BEARINGS, (after Dresser Industries ) 4  48  protection  the chances  eventually  be e x p o s e d  3.1.5  Although  and allowed  a r e passageways  approximately  i s diverted  purposes, hole on  the r o l l e r t o drop  bearings  could  out, breaking  the b i t .  Aircourses  Aircourses  air  are that  through  drilling point,  percent  the bearings  the a i r i s f i r s t  bottom  this  twenty  f o r the c i r c u l a t i n g  used  of the t o t a l for cooling  to flush  The importance  performance  be d e s c r i b e d  only  the c i r c u l a t i o n  compressed  and c l e a n i n g  t h e c u t t i n g s from  to the surface. will  air.  of c u t t i n g in section  of a i r through  the  removal  3.5.1.  the b i t  At  i s  considered. Tricone far  rotary bits  are differentiated  as the a i rc i r c u l a t i o n  1.  Conventional  bits  i s  which  into  two t y p e s  as  concerned: direct  the a i r right  above t h e  cones. 2.  Jet bits between  which the  Conventional  direct  t h e a i r onto  the hole  cones. bits  have  long  been  standard,  replaced  by t h e j e t b i t s .  The p r i n c i p a l  the  that  medium i s p a s s e d  fact  before move the  the flushing  i t reaches  the hole  bottom,  t h e c u t t i n g s a n d , i n many cone  nozzles  shell  bottom,  and t e e t h  on t h e p e r i p h e r y  thus  cases,  at high  disadvantages around  reducing  causing  velocity.  o f t h e b i t body  but they  relate  to  the cones  its ability  severe  Jet bits  through  a r e now  to  erosion of have  which  three  the a i r  49  runs  directly  cleaning the  of  the  cutting  a  This  or  the them the  in  cone free cone  volume  shows  filters the  the  and of  in  at  This  minimizes  a  cross  the the  design  the  gives  superior  sandblasting  Then  the  ball  s e c t i o n a l view  bearings, entrances  bearings  air.  from the  race,  behind  through  the  the  the to  being  air  of  effect  bearing with  i s discharged  gage.  the  that  are  in  bearings  the  The  the  first  clogged  Finally  nozzles  air  the  cooling  foreign material.  openings,  flows  diameter.  bottom.  and  Through  prevents  carried  hole  chips  3.1-8  jet bit.  screens  the  on  structure.  Figure of  to  runs  through  diversion. debris the  nose  of  and  keeping  a i r escapes  through  major of  aircpurses  part  of  adjustable  the  air  50  NOZZLE  FIGURE 3.1-8' CROSS SECTIONAL VIEW OF A JET BIT. (after Steinke ) 9  51  3.2  PENETRATION  Drilling by  OF B R I T T L E  with  tricone  the combination  loaded the  under  crushed  sufficient  strength.  in a fine  concentration discrete  later  mode  bits  causes  weight,  compressive  carbide  inserts  The rock  powder-like  around  directly  material,  the crushed  fractures.  intersection  rotary  the rock  of crushing-chipping actions.  end of the tungsten  compressive  ROCK  zone  The p r o p a g a t i o n  of the hole  of f a i l u r e  bottom  forms  overcomes  developed  at  the material's  the stress  ultimately  develops  fractures  the d r i l l i n g  i s associated with  i s  the insert i s  whereas  of these  break  If the b i t  stress  below  to  to the  chips.  the t e n s i l e  or  This  shear  mode. Even been  though  these  demonstrated  that  simulated drilling  by s t a t i c  that  the  experimental  tooth  1  .  Thus,  they  and mathematical of rock  research.  has  rotary The  developed The  factors  penetration are the applied and t h e geometry of has been  simplifications,  of the d r i l l i n g  i t  t o be  tricone  has been  p e n e t r a t i o n models  i n c l u d e d some  S t r e s s e s Beneath  enough  a s an i n d e n t a t i o n p r o c e s s .  pentration process  Different  understanding  3.2.1  loading conditions.  the mechanics  0  i n nature,  slowly  the s t r e n g t h p r o p e r t i e s of the rock  Although the  a r e dynamic  are applied  of the rock  affect  force,  they  c a n be s i m u l a t e d  knowledge through  stresses  process.  the Indentor  they  proposed.  contribute to  52  The field  force  beneath  distribution rock  under  is a  change  tension  the rock  fails  a point  material  Sikarskie  formation i)  ii)  has p u b l i s h e d  1 2  increasing  applied  fracture  increasing  During  vertical stresses  (top right).  stress,  induced  to the load mode  stress  The  center  insert.  tri-axial  i s found  of Poisson's  largest  at the  on t h e  (ie.,  and the  on t h e z  ratio  axis  of the  a description  of a  wedge  and the  chips: formation  Primary  a  condition  the insert  in quasi-static conditions  Initially,  with iii)  on t h e v a l u e  and the  (z/a = 0.5).  the rock  of  shear  and  between  i n the crushing  T h e maximum  dependent  penetrating  and equal  stress  proposed  1 1  the stress  the r a d i a l  stress  i s the v e r t i c a l  surface  Tandanand  tangential  However-,  tensile  The  3.2-1).  a t the boundary  stress  the contact  indented  (Figure  stress  of the indentor  to define  the r a d i a l ,  and i s the l a r g e s t  compression). at  indentor  are i n compression.  compressive  Here,  of the design  approach  a complex  compressive.  vs. irregular).  mathematical  into  creates  is essentially  (smooth  the surface,  stresses  by t h e i n s e r t  function  a spherical At  of  i t that  conditions  simplified  rock  applied  of crushed  fractures  forms  and extends  applied  material  are  a t wedge  t i p with  force,  the crushing  surrounding  material  virgin  material  force,  phase, mass,  initiated.  into  stresses until,  are increasing  a t some  point,  i n the  secondary  53  FIGURE 3.2-1 - STRESS PROFILE ON CONTACT SURFACE AND ON AXIS OF SYMMETRY, (after Tandanand" )  54  iv)  These load  fractures until  crack the  growth  types  Immediatly  of  type  of  not  or  said the type  broken  material/  failure  i s the  tensile  possesses  a  more  enough, The  crack  volume by  brittle  of  lateral  confinement.  The  Figure  Indentor  3.2-2  shows  Reichmuth  analysis,  he  has  Tan  p  (TT  <=  (TT  W h e r e ft = U  =  1 3  2U)/(2 -  extends  the .  insert, of  chip  occur the  the  unit  use  of  is  rock  formed.  an  of  energy  available  The  Away  the  from  and  tensile  in  powder-  energy).  the  indentor.  i s crushed  produces  decreases  If  force)  beneath  failure  second zone  the  of  rock  stress  is  occurs. to  tri-axial  geometry  graphical On  or  by  stress  can  reducing  the  be  b a s i s of  following  purely  a  model  elastic  relationship:  TTU)  +  semi-included coefficient  the  r e p r e s e n t a t i o n of  TTU)  +  2U)/(2  rock.  A  failure.  indentor  d e r i v e d the  -  in  increase  Geometry  by  /3 >  no  behaviour.  the  developed  Tan  rapid  material submitted  modifying  increasing  whereupon  confinement  initiation  with  i s reached,  to  optimize  the  manner  surface.  of  compression,  reduced  are  This  does  tri-axial  large  free  t i p of  compression.  volume  stable  little  the  the  m a t e r i a l and  (ie.,  (with to  in a  instability  failure  around  tri-axial like  crack  fracture  Two  grow  of  wedge  angle.  friction  between  the  tooth  and  the  55  SECONDARY FAILURE  ZONE OF TRIAXIAL COMPRESSION  INITIAL  ZONE OF TRIAXIAL COMPRESSION  SECONDARY FAILURE • (chip removed*  INITIAL FAILURE  FAILURE  FOR WIDE ANGLE WEDGES 2a  FOR NARROW ANGLE WEDGES 2b  FIGURE 3.2-2-- MEDIA AFTER SECONDARY FAILURE HAS OCCURED. (after Reichmuth ) 13  56  In  the case  2a, t h e s t r e s s  in  a  below  region  compaction The  insert the  angle  orientation  material  the  little  as i n case  noze  From  in  rock  that  when  result,  wedge  with  drills  insert  will  decreases  as  growth  on t h e with  a  are produced  In t h i s  was  case,  sharper closer  to  very  i s deveoped  shape  which  Moreover,  a change were  these  i n the  model.  greater  required to with  an  confirmed  a  sharp  manner whereas  are load  limited  (roller-bit)  wedge, with  not penetrate  as deep  as a  a  As a  on d r i l l i n g because  of  degrees,  i s more d u c t i l e . effect  also  behaviour  75 t o 90  With  sharp  this  experiments  i n c r e a s e d over  behaviour  h a s a much  have  i n the f a i l u r e  in a brittle  the rock  the force  increases rapidly  the Reichmuth  t o behave  that  Experiments  3.2-3).  angle  angle,  insert  angle.  there  wedge  i s belived  larger  for  p e n e t r a t i o n depth  (figure  1 5  accordance  rock  restraint  of the rock  .  4  and the  Conversely,  a r e formed.  1  the  the p r e f e r e n t i a l  fractures  i t i s concluded  i n t h e wedge  illustrated  angle.  and c r u s h i n g  the above,  conclusion  the  wedge  zone,  i s steeper  greater  of c h i p s  area.  a given  increase  to exert  s u r f a c e and c h i p s  the crushed  cracks  localized  t r a n s m i t t e d from  In a d d i t i o n ,  2b, s e c o n d a r y  compaction  tooth's  obtain  a wider  the formation  stress,  through  increases.  forces tend  under  free  rock  is effectively  c o n s i d e r a b l e c r u s h i n g and  and i n h i b i t i n g  of the secondary  frictional  causing  of the compressive  to the intact  wedge  wedge,  the tooth,  of the rock  intensity  distribution  a  rate large  one, r e s u l t i n g  in a  57  BIT PENETRATION, Inches  FIGURE 3,2-3= CHARACTERISTIC FORCE-PENETRATION CURVES FOR CHARCOAL GRAY GRANITE UNDER STATIC BIT LOADING. ( after Reichmuth ) 13  58  reduced  drilling  efficient,  larger  reasonable  interaction  adjacent  to  generally the  a  to  crater. for  slope  of  a  the  of  great  as  five  conducted  penetration  of  Tool  of  the  to  with  are  keep  more  wear  within  crater,  insert  the  and  The  the  Gnirk  i s of  individual angle  of  the  insert for  on  the  insert  importance a  various  chip  breaks  are  shown the  formed  distance In  per may  a  research  optimum  indexing  and  the  in determining  the  roller-bit  for  rock  in  with  material  depth. ,  fracture  efficient  indexing  1 8  loaded  decreases  crushed  Cheatham  formed  general,  i s more  optimum  width  In  curve  penetration  and  the  of  the  curves  penetration.  Indexing  is  tensile  force-displacement  rock.  tooth  previously  an  its direction  tooth  This  a  When  proportion  Penetration  although  tooth  formed  times  by  depth.  Theoretical tool,  indexing.  r e l a t e d to  spacing  selection  as  reduced broken  was  bit  distance.  of  distance  a  toward  volume  project  3.2.2  wedges  used  force-displacement  because  optimum  small  are  of  indexed  indexing  as  angles  Typical  decreasing  be  Although  previously  progresses  3.2-4  average  unit  .  wedge  is refered  figure  6  Indexing  The  into  1  limits.  crater  rate  and  the  types.  Models  analysis  simplified,  of  brittle  are  the  rock  basis  penetration of  our  by  a  rigid  understanding  of  59  -  2/3=30°  PENETRATION (In.)  FIGURE 3.2-4'AVERAGE FORCE PENETRATION CURVES FOR CARTHAGE MARBLE AS OBTAINED WITH 30 AND 60 DEGREE SHARP BIT-TEETH AT ATMOSPHERIC PRESSURE FOR VARIOUS INDEXING DISTANCES (after Cheatham and Gnirk ) 17  60  the  drilling  The predicts shallow i)  process.  Paul  and  rock  penetration  the  depth.  The  paragraph  Sikarskie  gross In  this  plane  the  f r a c t u r e s occur  tip  to  free  rock  by  under  Paul a  along  an  them.  and  Sikarskie insert  1 9  at  everywhere  on  the  failure,  planes  at  of  that;  is satisfied of  four  loaded  i t i s assumed  instant  surface  review  Model  proposed  of  model,  The  the  model  criterion  at  will  Penetration  behaviour  Mohr-Coulomb  failure ii)  This  extending  from  inclination  (to  the  the  insert surface)  of: ii  =  -  TT/4  with  0  =  iv)  The  force  of  penetration  is considered  rock  The in  sides  force figure  actual two  crushing  near of  omits  3.2-5  extreme  internal  angle  friction  are  linear  during  the  penetration, as  a  material  the  insert  the  penetrating  the  for  both  conditions. the  the  wedge,  exhibits  formation although  predicted  constant on  which  both  of  chips  the  model  model  are  on  zone.  curves  conditions  intersect  t i p and  crushed  penetration  loading  curves  of  wedge  curves  The  analysis  these  angle  phase  both  The  included  crushing  crushing  shown  + <(>)/2  half  <t> = iii)  (/3  load  by  the  and  constant  a  wedge  are  somewhere  The  chips  are  formed  failure  line.  The  rate.  between  when  crushing  the curves  61  WEDGE PENETRATION  FIGURE 3.2-5' THEORETICAL FORCE-PENETRATION CURVE FOR BRITTLE  CRATER  MODEL. (after Paul and Sikarskie ) 19  62  slope  k  slope  i s given  K  is experimentally  =  S  0  sin/3  where  S  0  = Uniaxial  is  Angle  be  the  depth  penetration  in  more  The  less  that  approximatively  only 120  crushing  will  degrees.  varieties  of  of  rock  and  -  line  s i n ( / 3 + tf>)) strength  angle  chip  upper  depth  the an  the of  surface bound  at  a  material the  by  and  wedge  solution  this  model  load.  phase  brittle  simultaneous  of  given  crushing  exact  and  type  predicted  obtained  the  angle since 30  of  the  high the  and is  This  the  model  the  fracture  t i p make  cessation  exceeds most  occur  i s 75  for  the to  Calder  a  the  chip  problem.  hydrostatic material  above  of of  degrees.  Penetration  on  Model  when  Cheatham angle  expression  angle range  formation  <j> ) .  exhibit  tooth  observed 90  of  ( TT/2 -  rocks  degrees,  However,  Bauer  failure  plastically.  predicts  Gnirk of  an  be  vicinity  tooth  noted  as  i s not  semi-included 1 7  the  friction  planar  Moreover,  nature  the  model  of  can  process  or  internal  viewed  that  (1  wedge  penetration  pulverized  behave  of  /  compressive  <t> =  can  stresses  sin0)  Semi-included  conservative.  The  -  |3 =  therefore, minimal  (1  assumptions  fracture  whereas  by:  2  The  determined  of  the  and friction  implies  that  approximatively value  for  numerous  63  The is  rock  based  on  concluded shapes  "seat"  also  a  i t was shell  increases.  becomes  becomes  It  constant  very  results as  that  Ka  where  F  =  total  K  =  rock  A  =  h o r i z o n t a l p r o j e c t i o n of  i s simply  not  3.2-6  linear, equal  shows The  shapes  i) ii)  the  to a  penetration  slope  divided K  or  plot  correlation of  indentor  constant  of  area  k  of  the by  of the  on  =  where  L  =  length  a  =  included  the  They  for  indentors  penetration  the  indentors  material  as  insert-rock  proceeds.  indentor  the  Paul  &  area  the  contact  Therefore,  area  curve  The  the  K  =  value  following  F/hA  2  wedge angle  of  depth  constant  wedge  (2/3)  Figure  strength  of  K  for  h  when i t  (ie., this  u n i a x i a l compressive  by  at  S i k a r s k i e model).  F/(Ltan(a/2)h ) of  rock.  2 0  indentor  contact  indentors:  K  as  force-penetration  is excellent.  wedges:  Calder  constant  the  i s given  and  force-penetration  that  penetration  force  in  compacted  =  applied  the  apparent  of  Bauer  tests that,  linear  dF/dh  becomes  K.  load  on  indentation  or  by  penetration  in drilling,  linear  addition,  proposed  indentor  employed  is either In  of  model  s e r i e s of  themselves  applied  is  study a  commonly  proceeds.  K  the  from  relation  area  penetration  versus  different  equations:  FIGURE 3.2-6 ROCK PENETRATION CONSTANT VS UNIAXIAL COMPRESSIVE STRENGTH, (after Bauer and Colder ) 20  65  iii)  hemispheres:  iv)  cones:  The into  10%  F/(7rh (r  caused  by  h),  and  beneath  obtained  from  the  load  (cylindrical  line  o b t a i n e d when i s made  of  an  r  indentor i s  two  portion  Firstly,  usually  less  caused  i n d e n t o r t i p (termed  following  forced  parts.  indentor penetration,  fracture  i)  <=  2  secondly a  the  h/3) ) f o r h  tan (a/2))  drilling  the  -  2  penetration  in rotary  (termed  =  3F/(TT h  =  total  rock  portion  K  K  by  d).  the  The  a  than  stress  value  of  d i.s  equations: envelope  of  diameter  d  caused  by  a  diameter  d  caused  by  a  to  the  wedge)  - 1 ) / ir S c  d = F(1 - s i n 0 ) ( w ii)  point  load  (spherical cone  d  =  3F(1  where  F  =  Sc  In stress  sin^Mw applied  = =  angle  w  =  tan  practice,  2  (45  geometry  or  Pariseau  and  rock  of  sphere)  1) /  47r S C  compressive internal +  sintf>  the  the  friction  depth  of  indentor could  indexing  rock be  failure  as  low  as  due 0.4d  effects.  Fairhurst  penetration  strength  (0/2) )  however,  beneath  envelope  load  of  indentor  The  a  -  uniaxial  0  field  or  sin0  models  Penetration  proposed  by  Models  Pariseau  and  due  to  66  Fairhurst  are derived  2 1  from  the a p p l i c a t i o n of  analysis  i n wedge p e n e t r a t i o n  approach  i s t h e one t h a t  composed  of f i n e l y  (see  Figure  such  a zone.  condition  material  Penetration  The most  practical  the existance a t t h e apex  tests confirm  The f o r c e - d i s p l a c e m e n t  i s given  by t h e f o l l o w i n g  of a  false-nose  o f t h e wedge the existence  characteristic  of  for this  equation:  = T a n / 3 / ( T a n 0 Tan/x) [ e x p ( 7rTan0) - T a n , u ]  F/hbSo and  considers  crushed  3.2-7).  of rock.  plasticity  2  thus h  = F /  where  MbSo  F = applied b So M  force  = b i t contact  edge  (= c t e =  = u n i a x i a l compressive = Tan/3/(TanQTanu)  /3 = s e m i - i n c l u d e d <j> = a n g l e  unity)  strength  [exp(rrTan0)  wedge  of i n t e r n a l  -  Tan /u3 2  angle friction  M = TT/4 - <j>/2 In  this  bit  face  the  plastic  the  rock  failure by  fact  however,  t o t h e rock region  surface.  surface.  region  It is likely dimension  Then  failure  brittle  penetration.  a non-linear  i s f o r many  a non-linear  the p l a s t i c  i s of f i n i t e  accompanies  assuming  envelope  model,  failure  rocks  failure  a  They  envelope,  that  as w e l l  from t h e  in practice,  and does  not extend  as  approached  criterion.  linear  extends  plastic this  Because  problem  t h e Coulomb  approximation  o f what  they  a  examined  to  isin  parabolic  FIGURE 3.2-7'ASSUMED STRESS FIELD FOR 'FALSE NOSE'SITUATION, (after Pariseau and Fairhurst ) 21  68  type  of f a i l u r e  criterion.  They  derived  the  following  relationship:  F/hbSo = Sin0 Tan/3/Sin0  [ l / 2 S i n 0 + (Sin(20+/3) )/Sin/3] +  o  (T Tan/3)/(2SoSin0 ) o  and  thus,  where  h =  o  F/M'bSo  F = applied b  M  force  = b i t contact  edge  (=cte=unity)  So  = uniaxial  compressive  To  = uniaxial  tensile strength  4>  0  = inclination the  point  strength 0  = variable  strength  of the y i e l d  i t touches stress  0  envelop  the uniaxial  to the S-axis at compressive  circle  = f(am)  1/2 ( a , +  am  =  a,  = major  principal  stress  a  = minor  principal  stress  3  T o <=  a ) 3  /3 = s e m i - i n c l u d e d  wedge  angle  M' =" [ ( S i n 0 T a n / 3 ) / S i n 0 ] [ l / 2 S i n 0 + S i n ( 20 + /3) / S i n/3 ] o  +  (T Tan/3/2S Sin0 ) o  o  o  6 = IT/2 + 1 / 2 ( 0 O " 0) + l / 2 ( C o t 0 The  problem  of  the major  area  this  and minor  of p l a s t i c  value and  with  equation  the magnitude  ( i e : beneath  by knowing  - Cot0)  i s the fact  principal stresses  behaviour  i s obtained  o  0 is a  encountered  the indentor).  the equation  of the s t r e s s e s .  that  function i n the This  of the f a i l u r e  envelop  69  3.3  SPECIFIC  The  ENERGY  concept  of  specific  fragmentation  processes  as  required  the  The on  energy  amount the  the  method,  of  of  total  energy  cleaning  broken  condition  is a  required  for  intensively to  minimum energy  studied  excavate quantity  will  be  difference  process  of  would  a  a of  by  the  of  not  only  in  hole,  is  dependent  the  drilling  In  on  such  the  as  cutting  removal  considers  a l l the  drilling  process,  formed,  occurs,  certain and  the  amount  chipping  Teale  given energy  the  measure  rock of  therefore,  measure  of and  energy 2 3  .  volume will of  the  is  the  specific  postulated  of  rock,  a  nature  of  the  the  work  2 2  in  .  has  been  that,  for  This  amount  rock  dissipated  a  given  theoretical  t h e o r e t i c a l requirements of  consumed  energy  rock  certain  required.  Such  energies  the  drilling  is  perfect  is also  specific  the  rock  reground.  energy  grinding in  the  because  He  be  the  but  strength  the  the  are  defined rock.  process.  parameters the  rock  of  During  function  a  depends  energy  specific  between be  that  volume  is  i n t e r f a c e and  collective  concept  certain  it  rock-bit  process  crushing,  a  2.2-1,  the  chips  a  figure  to a l l  at  never  that  comminution  tool,  and  applied  fragmentation  size  occuring  be  fracture  drilling  specific  losses.  drilling  the  b i t , the  The  implies  The  quantity on  to  the  can  in  fracture  and  also  failure  initially  a  the  etc.  modes  effect  but  to  shown  required  size  i t is a  rock,  geometry  in  energy  fragments  drilling, of  of  as  energy  in  of  mass, and the  the  and real  70  communition and/or  in friction  i n mechanical  difference In  high  that  below  losses  i s a measure  tricone  very  force  process,  at  low  a certain into  toward  value,  zero,  done  t o overcome  size  of p a r t i c l e s  broken  will  constitute a  rapidly  at high  into  and  lowest  will value  conditions  into  magnitude Tests  and  energy  n o t an  physical there  particular given  rock.  by  Teale  showed  to uniaxial  rock will  to  excavated still  be  loss  the t o t a l  energy  decrease. i s heavily  pushed  i n the e f f i c i e n c y to rise  again.  t h e maximum  quantity  of the  The  mechanical  i n the p a r t i c u l a r  This  fact  increases, the  the tool  of  the  the f r i c t i o n  will  energy  reaches  inadequate  p o r t i o n of  reduction  tool  and  this  process.  by  of  the thrust  compressive  2 3  be  rock  words,  energy  o f work  energy  the  operating  i s i n the order  strength  of  that  the r a t i o  compressive  strength  the of  of  rock.  minimum  ranges  between  1.6.  Although is  a  as  i s a measure  the u n i a x i a l  performed  specific 0.8  of  that  will  amount  values,  The  the  t h e volume  decreasing  thrust  of  i s caused  increases  the s p e c i f i c  obtained  of  also  clogs.  cause  efficiency  But  the s p e c i f i c  Nevertheless,  process  As  finite  friction.  Therefore,  the rock  a  This  and  In other  the s p e c i f i c  the t h r u s t  the rock.  tend  input.  the e f f i c i e n c y  thrusts.  will  the t o o l  i n the system.  rotary d r i l l i n g ,  values  the tool  of  between  Teale  absolute similarity  must  be  some  noted  that  measure  of  with kind  the uniaxial the rock  the d r i l l i n g of  compressive  strength process,  relationship  between  nor he  strength  possesses  suggested  the  two.  that  71  However  Mellor  2  4  published  examined  the v a l i d i t y of  strength  as a  compressive energy  process. strength  i n breaking oc  S.E.ucs  *  factor  He  3  and  research  out  that  the  proportional  in uniaxial  therefore  i n which  he  compressive  f o r the s p e c i f i c  pointed  i s actually  the rock  10~ )  of  the use of the u n i a x i a l  normalizing  fragmentation  the results  energy  in  uniaxial  to the s p e c i f i c  compression ( i e . ,  c a n be  used  as a  normalizing  factor. Even specific optimum 0.3  to  though,  according  energy/uniaxial operating  3.  to Teale,  compressive  conditions,  the r a t i o strength  in practice,  of  minimum  i s around  the values  one f o r  range  from  72  3.4  ROCK MASS  DRILLABILITY  Drillability to  penetration.  indexes  are  used  mass.  to predict  controlling  there  the d r i l l i n g  on t h i s  research  to define  For this  reason,  drillability  2 5  of the  a r e a s many  tests.  and i n c o n f u s i o n  performance  properties.  as the resistance  are d r i l l a b i l i t y  on norms  However,  drilling  this  Unfortunately,  as there  divergence  c a n be d e f i n e d  This  .  drillability  results  Drillability in' a g i v e n  project,  are using  an  index  of the rock  the review  has been  in a  wide  indexes  performance we  rock  rock the  mass  failure  of the f a c t o r s  undertaken  and presented  in  paragraph. Two  general  methods  exist  t o determine  the rock  mass  drillability: 1)  Drilling  the  2)  Analysis  of the mechanical  3.4.1  Drilling  This procedure bit  close  The b i t wear,  index.  different  b y many  of the  rock  The rock  I n some  degrees  down  drilling  drilled  scientists.  to the following.  rpm) u p - s i d e  f o r a given  drillability  used  i s selected.  (thrust,  conditions.  with  has been  i s generally  conditions  properties  Tests  method  arrangement  monitored  rock  depth  typical  is drilled to obtain  time  under  perfect  or energy  and e v e n t u a l l y  occasions,  of success,  A  with  the index physical  The drillstrict cleaning  input are result  as a  i s related, properties  of  73  the  rock.  not  only  and  the operating  on t h e r o c k  logical, the  Drillability  performed promote  procedure  are given  this  approach  with  other full  showing  the microbit  i s that  microbit size  are using  test.  Details  the results  have  an e m p i r i c a l  been  6  .  of t h i s  data.  The d r i l l i n g  modified  by e x p e r i m e n t a l  test  Figure  factors  from  drilling  results  of t h i s  test  are conservative.  be n o t e d  that  t h e r e s u l t s a r e a s good  representativity mass. the  of the tested  In a d d i t i o n ,  i s made  formations i s a  this  with chart  is  the  In general,  As a m a t t e r  over  on  chart  to reflect  of the b i t .  specimen  no a l l o w a n c e  are correlated  3.4-1  ( 0 . 5 t o 0.7)  f o r the l i f e  empirical  factor in  formations  obtained  scale.  of the t e s t  average  should  rate  rate  simulate  companies  a more  r e s u l t s of rock  used.  used  generally  The main  c o r r e l a t i o n o f known  microbit  are  some  others  2  depend  drillability  tests  Eventhough  drillability  bits  to closely  reliable  i n the l i t e r a t u r e  method  the procedure i s  drillability  test  this  on t h e e q u i p m e n t  have  in a  by b i t m a n u f a c t u r e r s .  called  but also  conditions  p i tdrilling,  from  Although  to result  the indentation  approach  which  conditions.  conditions  open  derived  properties,  the experimental  field In  indexes  the  of f a c t , i t  as the degree of the whole  rock  f o r the abrasiveness  of  rock.  3.4.2  Analysis One  According  of the M e c h a n i c a l  of the f i r s t  drillability  to Protodyakonov  2 5  ,  Properties indexes  of t h e Rock  was  a drillability  t h e Moh's  scale  based  scale. on  74  FIGURE 3.4-1 ESTIMATED DRILLING RATE OF NEW HUGHES TRICONE ROCK BITS AT 60 rev/min. AS DETERMINED BY MICROBIT DRILLING RATE TESTS, (after Rollow ) 26  75  standardized rocks to  is a  more  measure  1)  method  the  of  measuring  rational  approach.  s t r e n g t h of  Resistance  to  tension,  2)  Resistance  to  local  3)  Resistance  to  breakage  The  uniaxial  significant it  i s not  gave 214  the MPa  load,  example (31000  i s three  Although  no  strength  and  on  the  suggested  that  the  poor  magnitude  of  proportional  compression implies  strain  because  that  the  considered  too.  to  the  measure  the a  rock.  quantitative  a  exists  of  the  elastic  under  than  in  of  shore and  the  the  are  rock  classification  the  tests that  2 6  at  same  the  fact in in  weight 1 1  that  uniaxial  different. are  to  relates  to  It  be  deformations in order  the  drilling  scleroscope hardness  inelastic  indentation  both  .Tandanand  caused  failure  Rollow  granite.  process  strain  of  although  7  between  to  failure  a  compressive  exists  i s due  2  granite,  2  properties  suggested  hardness  modes  Gray  strength ".  failure  proposed  shows  drilling.  between  relation  with  two  rock  rate,  in dolomite  correlation  the  and  drilling  i n the  amount  Others  the  involved  the  indentation)  the  rotary  dolomite  compressive  elastic He  (hardness,  in tricone  rate,  the  stresses  percussive d r i l l a b i l i t y  relationship  and  not  with  greater  (W)  is  bit  elementary  s t r e n g t h of  Virginia  drilling  exist  shear)  p s i ) , where  close  techniques  of  (grindability)  reliable  times  properties  rock: by  compressive  of  mechanical Different  destruction  correlation  always  the  destruction  (compression,  the  to the  test of  obtain  76  resistance this  of  test  drilling  the  can  be  rate  The  rock used  (see  characteristics  of  easier  and  drill  structure  .  2 9  alteration,  In  Figure  3.4-2  to  number  the  the  rock  and  the  and  Raynal  (Fig  Finally, and  a  can  where  It  is  / K  the  the  a  from  the  type  angle  affect  a  reflects i s the  failure  index  was  which  the  rate  in  relation  d r i l l .  One  mechanical  sonic  and  of  Gstalder  drilling  sonic  that  behaviour 2 7  the  of  behaviour  velocity.  the  proposed  is  fracturing,  percussive the  structure  performance.  in penetration for  of  at  drill  c o r r e l a t i o n suggests the  structural  fine-grained  r e l a t i o n s h i p between  reflect  dS  and  Young's Modulus  good  defined =  and  planes  a  drillability  was K  the  The  degree  fracturing  published  of  coarse-grained than  increase  that  A  on  wear  drilled  properties  3.4-3).  mass.  the  weakness  rate,  performance  ago  of  dependent  material  the  Results  theoretical expression  less  addition,  i n t e n s i t y of  penetration  rock  are  penetration.  3.5).  causes  shows  3 1  a  the  planes  mass  with  tooth  is also  cementing  discontinuity  bit  section  drillability  to  to  velocity  the  drill  the  rock.  over  thirty  years  as:  d(W/D ) 2  =  drillability  S  =  penetration  W  =  weight  D  =  diameter  i n t e r e s t i n g to  note  rate  (in/min)  (lb) (in) the  similarity  between  K  and  the  RQI.  77  2 4 6 WEAKNESS PLANES PER  8 METRE  FIGURE 3.4-2'ESTIMATED RELATIVE INCREASE RATE VERSUS PER  NUMBER  10 DRILLED  12  IN PENETRATION  OF WEAKNESS  PLANES  METRE DRILL-HOLE ( after Blindheim ) 30  78  SOFT  8  ROCK BIT  i  i  SMF-T  i  i  (a)  WEIGHT ON BIT: TONNES  E  4-  i  or  0 8  MED. HARD BIT T  W4T  _  2 TONNES  2000  4000  I  - T -  4T V  1  1  6000 YOUNG'S  ,  0 2000 4000 MODULUS-Kg/mm^ 0  6000  1 (c)  o 2T -«  2000  4000  6000  ^  1  8000 2000 SONIC VELOCITY-m/sec.  4000  6000  8000  FIGURE 3.4-3'CORRELATION OF DRILLING PERFORMANCE WITH ROCK CHARACTERISTICS, (after Gstalder and Raynal ) 31  79  3.5  TRICONE  In the is  ROTARY  tricone  DRILLING  rotary drilling,  bit-rock interface supplied  hole  bottom  parameters (W), and  through  the  and in  to  size  type  rate  of  (RPM),  the  over  to  are  in a  the  the  costs  would  weight  torque  or  (T)  or  The  thrust  the  major on  the  and  the  air  inter-related  and  i t is  rock  condition  type.  Trial of  i t s effects  certainly  reduce  for a tests  the  on  the  the  to  Flushing a i r  c u t t i n g s at  surface.  understanding  others  pipe.  remove  operating  given  is transmitted  rotating  the  are  optimum  energy  to  the  the  parameters  bit  drilling  pipe  them  Nevertheless,  parameter or  speed  loaded  drill  process  define  performed. one  this  These  possible and  the  transport  rotary  volume.  via a  the  bit  pressure not given must  be  influence  of  penetration  extent  of  the  tests.  3.5.1  Drilling  Parameters  The  on  Weight  According important the  Fish  3  2  ,  Bit  the  v a r i a b l e s i n the  b i t by  mechanical reading  to  the  drilling  hydraulic pressure processes.  i s the  pressure  manufactuer  has  a  recommended  to  use  thru  i s one  in  the  cylinders  system  pressure  weight  of  process.  Consequently,  different the  thrust  rather  the  It or  since  weight  than  the  most  is applied by  hydraulic  and to  the  on  other pressure  every ratio,  down  i t is  pressure  when  80  comparing  drill  performances.  relationships  between  several  r i g models.  drill  The defines 3.5-1  intensity four  and  types  abrasive  2)  f a t i g u e phase:  pressure  of  the  of  drilling  described  1)  in  phase:  spalling  the the  phase:  loading  founder  phase:  at  3.3  gives  and  the  failure  sufficient  the  weight  on  bit-rock  the  bit  for  interface  shown  in  figure  : i s worn  formation  excess  II  c o n d i t i o n s as  formation  formation 4)  reading  section  rock 3)  Appendix  away  i s loaded  several  time  before  occurs amount  to  of  weight  fracture  weight  buries  causes  the  readily the  carbides  to  full  depth Although to  W**a  (where  relationship founder  weight  the  weights  The  per  excessive life  was  not on  to  weight  bits.  recognised  hole  to  mass,  cause are  study  that  the  4  the  bits  per  higher  inch) the  breakage  larger  and  thrust  on  rate.  and  a  the  mine  1.4  sufficient of  reduce  in  the  the  rock,  bearing  in hard  b i t was  to  diameter.  If  site  practice,  0.7  bit  load.  stronger  at  from  of  the  increasing  In  strength  insert  In  cleaned,  range  compressive  performed  the  conditions.  penetration  tons  the  that  improperly  carbide  overcome  a  is  tungsten (2  noted  optimum  the  rock  can  during  increases proportionally  be  increase  bearings In  i t should  the  centimeter the  penetration  valid  when  used  although  tricone it  or  i s needed  of  1<=a<=2),  will  stronger  load  rate  i s only  phase  the  tonnes  the  formation Labrador,  most  81  /I i»  /  /SOFT '  *  FORMATION /  / / /  r  I  / r  s  /ME:DIUM FO RMATIO  UJ  o <  rr »u z UJ CL  s  / /  L /  / FORMATION KEY  -ABRASION PHASE -FATIGUE PHASE -SPALLING PHASE -FOUNDERING PHASI  1— WEIGHT ON BIT  FIGURE 3.5-1 DRILLING CONDITIONS (after Dresser Industries ) 4  82  important  parameter  The  The  less  than  factors  Rotary  rate  increased,  of  when 1:1  that  bearing's  penetration  to  subjected  to  In  is  practice,  site  or  within  The changing  The  the  Air  increases,  forcing  procedure  will  air  volume  The  poor  using  is inversely carbide  at  opposite  the  slightly  cleaning * 5  are  drill  hard  rotary the  and  at  .  The  rotary  wear  can  rotary  constant  3  the  be  speed.  true  3  rig  inserts  is also  i n almost  ratio  p r o p o r t i o n a l to  and  high  a  speed  very  decrease  In  speed  hard as  the  (Figure  3.5-2).  a  mine  given  domains.  and  factor of  small more  Volume  of the  size  a i r to  g e n e r a l l y extend  i s reduced  bailing  is a  brittle  i s to  speed  and  by  hole  rotary  breakage  breakage  jet nozzles  by  maximum  life  Pressure  following:  is generally  proper  The  controllable the  bit  of  practice  rotary  rock  limits  i t is also  increased.  a  increased,  the  excessive the  of  is  tungsten  material,  drilling.  speed  insert  Bearing  resistant  weight  the  the  Although  rotary  Speed  determine  wear,  formations,  tricone  rotating  up  limitations. speed.  in  air  i s air' pressure,  bit.  The  nozzles, flow the  situation  modified is  the  the  air  pressure  through  the  bearings.  bearings  and  poor  bailing  velocity  will  cause  life.  velocity  poor  bottom  This  However,  would hole  by  result.  the  83  SELECTING THE RIGHT BIT  I+ ++ + + -H- + + RHYOLITE V+ -f + -t V+ + W WxWWW /"* I ISCH I P T IHSHTWxHxWxH x Wx x Wx Wx x I : xWx X x «r»x 1  ROCK COMPRESSIVE STRENGTH (psl  o o o  o o  8  8  °,  9. in  q  g  8.  in  §  o O  S Q  a 8 ° s s  I500H  •120  _ 2000w C 3  a  110  „  ^BBBBB  1BBBB  *mmu  2300-  •100  '«BB  Ul  2 < a  t m  3000-  mi. • BBBk  :  '  90  'BBBBBB ' ''BBBBB  80  4000-^  0000 X  o  z -  6000  UJ Q.  IX o  7000  UJ  8000  9000  in  ESTIMATED FIGURE 3 . 5 - 2 ' RELATIONSHIP PENETRATION  N  g  PENETRATION (feet/hr)  BETWEEN ROCK COMPRESSIVE STRENGTH, R A T E . WEIGHT AND RPM (afler Steinke ) 9  2 a.  '84  conditions, decrease other  a  to  drilling  high  wear  of  be  with  (sand  blasting).  the  hole  type  high  The  The  torque  application  the  rock  mass  rock  bit  t e e t h and  that  produce  with  the  the  high  the by  cause  thrust.  cone  optimum  the  or  erosion bailing  smooth  wet  On  or  the and  wall),  the  dry), etc.  bailing  generated  and  velocity  velocity  In  has  cuttings.  torque  between  1.6  to  thrust, developed  torque  i n the  bits, may  be  this  In  action  drills  joules this  per  are 10  amount  the  little  soft  effect  Kg  (10  to  by  proportional  to  tool  on  tricone is  a bit  formations, of  to 20  i s seldom  is  torque  is related designed  It  In  developed  3  of  of  system.  very  structure .  is directly  Equations  rotation  scraping-gauging  although  rate.  Drilling  gage  the  3.2  o p e r a t i n g parameter.  torque  Normally,  3  an  rolling  intensity  developed ".  3.5.2  b i t components  given  (shape,  and-the  the  true a  of  torque  torque  clear  thrust  the  is drilled  The  to  of  However,  the  l b s ) of  a  The  penetration rate,  exactly  i n t e n s e wear  100  can  cuttings  i s not  drilling,  developed.  at  the  Torque  the  rotary  of  c o n d i t i o n s (rough  of  increased in order  with  efficiency velocity  d e n s i t y , the case,  wear  bailing  too*  function  rock any  i n the  hand,  extreme is  therefore excessive  tricone with  the  sustain ft-lbs  per  neeessary .  the  6  penetration  85  Many  theoretical  and e m p i r i c a l d r i l l i n g  published  i n the past  thirty  be  published  proposed the  drilling  drilling The  equations  Many  In t h i s  paragraph,  a r e reviewed  others  will some  i n order  been  probably of the  to  summarize  drilling  equations a r e :  1 6  PR  =  (dV/dt)  where  Morris  PR  / A  = penetration  V  =  t  =  A  = area  rate,  volume, time, of the hole  1 0  PR  =  Np  where  N = rotary p  Although  those  drilling  equations  process.  The  concentration  loaded  inserts.  theoretical  and  failure  K(NW /A)**s 2  and t h e o r e t i c a l l y  true,  detailed  evaluation  approach  i s based  of the rock  of the  of v a r i a b l e s that  of the  on t h e  beneath  the complexity  q u i c k l y d u e t o t h e number  1 6  =  a r e simple  Unfortunately,  considered. Maurer  per r e v o l u t i o n  r e q u i r e a more  stress  increases  speed,  = penetration  applicability  PR  years.  have  process.  simplest  Maurer  their  i n the f u t u r e .  equations  individual equations have  t o be  86  where  The  s  =  1 =  good  s  =  1/2  =  K  =  rock  W  =  weight  on  N  =  rotary  speed  A  =  area  following  Morri PR  s  1  cleaning  poor  cleaning  mass  of  constant the  the  equations  bit  hole  assume  perfect  cleaning  conditions.  0  =  where  Nb  (p'/E)  b  1 .8  (W/0.08C) and  converts  bit  rotary  speed  to  cone  rotary  speed. C  =  total  (p'/E)  =  number rock  of  penetration  hardness Gnirk PR  and =  where  Cheatham 0.l56mNl  i n s e r t s per  bit.  factor  from  indentation  tests.  1 8  (w/D)  2  ((W/wntlap)  m  =  number  of  N  =  rotary  speed  1  =  length  of  2  penetrations  cutting  -  75.69)  per  edge  of  revolution  a  single  bit-tooth  (inch) W  =  applied  D  =  b i t diameter  nt  =  number the  weigth  of  rock  (lbs) (inch)  bit-teeth effectively at  the  bottom  of  instant w  =  bit-tooth  flat  width  (inch)  the  in  drill  contact hole  at  with any  87  ap  = compressive pressure  Some and  scientists  derived  more  useful  Bauer  tool  and  PR =  Cunningham  W  = applied  N  = rotary  = N  where  in  equations.  practical These  approach  are usually  a  estimate:  Sc)  W N)  /  ( 2 5 0 D)  compressive  strength  weight speed  6  (W**a) / 0.424. ad = d r i l l i n g  = f ( a d ) and >  N  = rotary  the future Index.  od**1.5  strength  a  derivation  Quality  a more  diameter  W = applied The  1 0  Sc = u n i a x i a l  2  at differential  2 0  D = hole  PR  drilling  ((61 - 2 8 1 o g  where  preferred  i n engineering  Calder  of the rock  p (psi)  have  empirical  strength  1.1  speed weight  of t h e Cunningham section  because  equation  i s reviewed  of i t s s i m i l a r i t y  with  in detail t h e Rock  88  3.6  ROCK  It rate a.od  QUALITY  h a s been  INDEX  shown,  i sa function  i n this  chapter  of the operating  the rock  properties.  = W**a  (RPM)**b * f ( r o c k  that  the penetration  parameters,  The g e n e r a l  the b i t design  relationship  i s expressed  as: PR  *  mass  properties,  drilling  procedures) However,  a t a given  generally are  constant.  limited,  weight  mine  when  site,  In a d d i t i o n ,  compared  with  on t h e b i t , t h e l a t e s t  parameter.  thed r i l l i n g  The general  procedure i s  the variation  the variation  being  i n rotary  speed  in the applied  the principal  operating  relationship can therefore  be e x p r e s s e d  as: PR  = W**a  * f(rock  mass  properties)  and f(rock  mass  properties)  This  was t h e c o n c l u s i o n  Rock  Quality RQI  In directed the  (W**a)/PR  derived  by M a t h i s  3 5  .  He.defined the  Index a s :  = W/PR  a research toward  drilling  relationship one.  =  project  the expression  parameters, was a m o r e  Although  conducted  there  by C u n n i n g h a m  of a simple  i t was f o u n d workable  that  approach  i s no i n d i c a t i o n  that  2 6  and  relationship an than  between  empirical a theoretical  Cunningham  reviewed  89  the  work  of  Mathis,  relationship and  expressed  i s repeated PR  =  N  =  rotary  W  =  weight  PR  =  penetration  on  the  strength at  a  specific the  3.6-1).  Those  i s t r e a t e d as  numerical  drilling  expressed  K  and  and  a  as  rate  are  a  single  has  with  and  termed of  to  3.5  of  constructed the  applied  lines  PSI).  meaning the  tricone of  rock bits.  ad,  the  drill  of The  and  i n any mass  a a  family  drilling  drilling of  the  other  context.  behaviour  Cunningham the  during  then  relationship  became: PR  = W**a /  with  In  a  =  0.424(ad**1.5)  (0.178254  a d d i t i o n , the  ln(ad)  drilling  +  1.09793)  strength,  1.1  which  <=  of  weight  equal  physical property  little  functions  between  required  Cunningham  in thousand  expression  process,  relationship  weight  rate,  lines  expressed  drilled  the  penetration  strength  the  section  rate  general  and  (ad  is a  in  constant:  strength  It  given  The  speed  i s kept  relating  formation  was  similar.  constant  based  compressive  (Figure  Cunningham  quite  K(W**a)  Then,  lines  = =  if N  formation  by  are  here:  a,K  PR  conclusions  K(W**a)N  where  and  the  a  <=  is derived  1.9  from  90  WEIGHT  PER  INCH  BIT  DIAMETER / 1000 ( L B / I N )  FIGURE 3.6-1 = DRILLING RATE VS WEIGHT PER INCH OF BIT DIAMETER, (after Cunnihaham ) 28  91  drilling  tests,  strength  when  the tests  The  work  by C u n n i n g h a m  relationship expresses The  c a n be a p p r o x i m a t e d  proposed  numerous.  The  additional  costs  of  the entire  being also  very  nature. the  practical  or personnel  application  Quality  without  an u n b i a s e d  must  be d r i l l e d  because  i n the  coverage before  o f t h e RQI i s of  c o n s i d e r a t i o n when  of the index  Index a r e  obtained  determination  to understand  important  simple  ratio guantatively  and e a s i l y  since a l l rock  and easy  the  quality.  and p r o v i d e  The m a t h e m a t i c a l  i s an  T h e W/PR  o f t h e Rock  i s quickly  p i t area,  simple This  advantages  index  blasted.  i n rock  compressive  performed.  therefore confirms  by M a t h i s .  the variation practical  a r e not  by t h e u n i a x i a l  i t s empirical  dealing  field.  with  92  3.7  SUMMARY  Tricone It W  rotary  i s influenced and  rock  condition volume  mass  by  i s a complex  the t o o l  design,  properties.  corresponds  of broken  drilling  drilling  breakage  operating  However,  amount  of energy  in practice,  i s determined  by  a cost  process.  parameters  t h e o r e t i c a l optimum  to the l e a s t  rock.  condition  The  rock  the  mainly  drilling per  unit  optimum  evaluation  of the  process. DC  = ROC  where  +  DC  = drilling  B  = b i t cost  L  =  life  ROC with  ROC  drilling It  B/L  does  (ft)  operating  f(machine  cost,  cost  ($/ft)  operator  wages,  effective  rate)  i s possible  condition  ($/ft)  ($)  of b i t  = drill =  costs  that  t h e p r a c t i c a l optimum  not c o i n c i d e  Nevertheless, drill  performance  Index  provide  the rock  with  the t h e o r e t i c a l  mass  properties  and the e s t a b l i s h m e n t  a useful  drilling  method  of  rock  of  mass  optimum.  a r e r e f l e c t e d on t h e t h e Rock  Quality  characterization.  93  3.8 1.  REFERENCES ESTES,  J.C.; S e l e c t i n g of  2.  Rock  Petroleum  Fragmentation, Symposium Hakala  3.  Rotary  Drilling  Blasthole  TOLL,  a Report Rock  Bits,  Open  7.  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Drillability  Parameters,  Manual,  Rock  Press,  An  Technology,  on  Pergamon  School  Drilling  29.  Symposium  editor,  Colorado 28.  5th  S.A.,  Quality  France Index  Unpublished 1975  97  CHAPTER 4  98  4.0  THE  BLASTING  The  q u a l i t y of  productivity should  be  well  production the  "Mine  mining  fragmented  the  management  often,  cost  only  total  be  (Figure  shovel  twice tight  also  as  improved  In  rock  pile  in  maximize  hauling  Hagan on  rock  the  equipment,  as  a  and  Mercer : 1  minimizing  the  considering  the  operations.  A l l  single entry  in  or  even  isolation. as  a  total  for  cost  too the  to  mining  them. costs  should  use  determining  operation  such  of  effects  breaking  Management  basis  individual  angle  well as  and  fragmentation. are  to  s i g n i f i c a n c e i s attached  a  (Figure  wear  and  without  appear  an  a  appendix  equipment  from  dependent  slope  productive  muck  order  blasted  the  as  4.0-1)  digging  increased,  reduced.  large  the  is  costs  of  in  loading  blasting costs  considered  blasting." addition,  on  undue  production  the  I d e a l l y , the  concentrated  costs  cost-effectiveness  and  the  function  and  cost,  heaved  influences  (autogenous).  reduction  statement,  not  is  of  often  explosives  must  A  operation. and  mill  operating  Explosives  In  blasting results  following quotation  such  cost  the  and  individual of  the  capabilities  crusher  The  of  PROCESS  III  to  fragmented shovel 4.0-2).  tear  on  is a Mine  designed  has  The  of  operators to  handle  evaluated.  and  digging  every  list  be  displaced a  poorly  truck  piece  possible  larger  mass  fragmented  productivity is  of  should  rock  equipment benefits  is of  acknowledge volume  of  that  99  FIGURE 4.0-1« EFFECT  OF FRAGMENTATION  MINING. (after Hoek a Bray ) 2  ON COST OF  100  1000 £  800  POOR  DIGGING 5 Shovels  —  ^00*  ct  LU Q.  e S S : s :  ^ X ^ \ o ve1s  3 Shovels  600  to D  <  2 Shovels  —  °,  400  O  200  1 Shovel  1  1  1  6  1  8 TRUCK  1  10 FLEET  1  1  12 SIZE  1  1  16  18  1000  800  cc  UJ Q-  GOOD  DIGGING  3 or 4 Shovels  600  CO  < o  400  6  TRUCK  8  FLEET  FIGURE 4.0-2 ' OUTPUT FOR DIFFERENT NATIONS AND  SINGLE  10 SIZE  12  SHOVEL  14  TRUCK COMBI-  CRUSHER, GOOD CONDITIONS  POOR DIGGING, (after Bauer ) 3  16  101  materials,  not  larger  Nevertheless, when the  the  blasting  rock  mass  blasthole charge  the and  In  first  the  Leighton",  the  theoretical  of  blasting  on  heights,  therefore  the  this  mass  for controlled  present  report  are  will  avoided.  be  approached  importance  of  operations,  the  the  by  relating  effects  on  the  energy  requirement.  order core  this  to of  chapter,  chapter  has  the  degree  demonstrate the  mass  author  process  In  that  will  fragmentation.  influence  on  mining  and  between  of  stemming,  scientific increase  in  project, published  by  been  i n an  search  blasting. certain  the  field  concepts.  on The  a  to  blasting  of  design  of  can  mining  review  the  blasting  this  the  powder  be  subject  i s .  major  of  on  the  reviewed  subject  factor  still  their  indirectly,  the  the  the  the  to  in  repetition  of  with  is a  resulted  o b j e c t i v e s of  Because  and  the  design  theories will  concerned  operation  the  from  blasting  parameters  controversial  The  has  extend,  fragmentation decided  be  approached  and  fragmentation  two how  has  principal  of  affecting  the  research  to  different rock  ratios  more  result  detonic  Fortunately,  with  can  A  literature  considerations  be  relationships  only  profitability.  His  such  obtained  subdrilling  strengths.  process  rock  the  are  well-balanced  process  standpoint.  chapters  the  explosive  part  results  understands  bench  blasting  fragments.  blasting  engineer  and  productivity  two  optimum  distances,  to  of  p r o p e r t i e s and  lengths  approach  size  The  factors  and prime  its  in  1 02  importance. dictate will  variations  deal  review  However,  of  chapter.  with  i n some  i n t h e powder  the design  the rock  instances,  mass  powder  the mining  factor. factor  operations  A particular approach.  b l a s t a b i l i t y index  paragraph  Finally,  completes  this  a  1 03  4.1  THEORY OF  The during that  perfect  explanation  blasting,  predicts  achieved. is  BLASTING  supported  results  This  of  by  an  f o r any  field  the  rock  fragmentation  accurate  mathematical  conditions,  i s confused  and  process  is s t i l l  model  to  contradictory  be  literature  abundant. The  blasting  function stress  of  waves  process.  as  large  seldom  4.1.1  Gas  This  quickly  The  gases  of  to  working  specifically  massive  the  as  role  a of  the  in  homogenous  chosen  However,  and  joint  to  be  in  most  free  rocks  as  are  a  described  the  causing the  and  very  expansion of  Theory  The  5  compressive  function  when  classes  fragmentation  discontinuities.  Kihlstrom .  cause  mass,  i n the  obtained  blasts,  i s well  liberated  resistance  accorded  gases  i n rock  major  Expansion  sudden  or  i n two  encountered.  and  is  were  production  theory  Langefors  rock  of  grouped  importance  expanding  them  possible  scale  strong  the  plexiglass  very  This  or  relative  A l l of  materials, free  the  t h e o r i e s were  i n the  chemical  transformed  rapid  literature  energy  into  expansion  high  of  the  i s e v e n t u a l l y stopped  rock,  but  strain  i t has  wave,  limited  d e n s i t y and  6  the  nonetheless  which  damage .  by  then The  of  the  explosive  pressure borehole the  gases. volume.  elastic  generated  travels  wave  by  a  through  velocity  the  is a  g e o s t r u c t u r a l p r o p e r t i e s of  the  1 04  rock  mass.  (10,000  -  As the  radial  the velocity  affected believe  first  by  two  t h e medium,  from  up t a n g e n t i a l  tensile  stresses  These  travel  of the compressive i s reflected  stress  t h e shock  that  the t o t a l  i s actually wave,  while  t h e medium, The  final  pressurized open.  The  forward. pressure  wave  theoretical  energy shock  wave.  t h e shock  the blasthole.  wave.  at a  wave.  back  speed  towards  Slabbing  that of  At the  about  free  the  of the rock  surface  not being  that  responsible  the stage  only  in front  into  will  reach  When  the free  occurs. energy  face  Blasting just  i s distributed a l l 1/3  o f t h e wave  burden.  f o r the expanding  the r a d i a l  of the borehole  but tension  f o r 5 t o 15 %  Thus,  f o r the actual  of the breaking process  rushing  Kihlstrom  only  and  part  i s reduced  explosive  energy  a definite  However, as t h e f r o n t a l  mass  accounts  up  cracks  total  explosive  t o break  c o n t i n u e t o grow.  rock  energy  sets  gases rock  used  breaking process are  But L a n g e f o r d s and  I t supposes  cracks  the  cracks  stages of rock  around  of  through  occur. Those  of  travels  wave  as a t e n s i l e  second rock.  wave  faster  per  and massive  cracking.  the compressive  borehole may  i t sets  3000 a n d 4500 m e t e r s i n dense  the compressive  times  face,  between  15,000 f p s ) , b e i n g  blasthole,  create 0.4  I t ranges  surface  i s done by t h e  cracks, then  wedging  yeilds  moves  and  i s optimum,  in physically  uses  them moves  forward, the  and the complete generally  breakage  gases.  i s m a i n t a i n e d and the the burden  the  several  loosening  about  moving  radial  of  30% o f t h e  the r o c k . 7  105  4.1.2  Stress  This  Wave  theory  was  Later,  i t was  strain  wave  theory  was  Winzer  and R i t t e r  theory  of rock  first  developed  demonstrated  breakage .  that  may  soon  breakage.  lead  They  of the explosive  conjunction  with  considerably  the rock  greater  First,  role  t o an  tensile  wave  reaches  the free  its  maximum  This  Figure  4.1-1  tangential experiments certain Also, rock but  can i n i t i a t e  e f f e c t when  i s equally  valid  shows  face  theory,  have  extent,  shown  generally  craters  the G r i f f i t h  i t has been  observed  appeared  t o one o r b o t h  as a  sides  theory  of  i t  0  .  the  have  crack. cracks.  cracks Blasting  the b l a s t i n g visible  in front  They  will  135° and c o n f i r m ,  the f i r s t  1  stress  by  wave.  cracks.  or the r a d i a l  during  not d i r e c t l y  energy,  stress  i s 138.2°.  averaging  that  as the  tensile  subtended wave  a  by t h e  to the t i p of the  to the r e f l e c t e d s t r a i n  by  small  plays  sufficient  the t e n s i l e  the angle  work  m  wave  as a  Also,  with  f o r the microcracks  that  this  wave, i n  or r e - i n i t i a t e  tangential  by  though.  cracks.  the blasthole  to the G r i f f i t h  even  s t r a i n s caused  compressive  According  strain  previously  the r a d i a l  stresses  improved  the s t r a i n  solely  Recent  than  produce  tensile  theory.  that  1950's.  15 y e a r s ,  structural defects,  wave  The  formed  the last  observed  energy,  i n the  mass  the tangential  i s r e f l e c t e d toward  c a n be  gases  compressive  it  t h e USBM  a crater  to the expanding 9  by  However, d u r i n g  8  second  percentage  Theory  also  cracks  to a  process. i n the  of the b l a s t h o l e , noted  that  the  Mirror image of charge  Angle subtended by crater, 138.2°  FIGURE 4.1-1'INTERACTION  Crack propagating at 0,38 of sound velocity of rock.  OF STRAIN WAVE WITH PROPAGATING  (after Harries ) 10  CRACK,  107  fragments due from  to  stress  the  4.1.3  They  laboratory of  face  i n the  are  continue  block  But  developed,  and  more  scientists  process.  fragmentation  only  i n the  the  short a  This  each  field,  as  to  i t is  process have the of the  interval  break-up, detached  is explained  demonstrated two  mechanisms  them  by  by  that are  using  highly destructive during  which  i t  occurs  technological challenge.  sophisticated will  1 1  when  described  measurement as  blasting  Fairhurst  obtained  methods. blasting  the  and  well  Fortunately,  this  free  Theory  time,  have  accurate  blasting  Blasting  Kutter  results  present.  make  trapped  present  theories.  nature  the  face.  the  optimum  from  waves  Practical  At both  i n motion  acquire  will  mechanism.  instruments more  eventually  are  being  quantitative improve  our  data  on  knowledge  the of  108  4.2  T H E MAJOR  FACTORS  Fragmentation the  of the rock  FRAGMENTATION  mass  by e x p l o s i v e s  o p t i m i z a t i o n o f a c o n s i d e r a b l e number  However,  the rock  property  cannot  his  AFFECTING  design  structural This  influence  h a s t o be p l a n n e d  by  will  and rock on  project",  order  to highlight  their  i n f l u e n c e on t h e r e s u l t s  4.2.1  their  the  the p r i n c i p a l  process.  Although  with  factors  importance  on  of t h i s  with  part  have  design their  the  author  one o f  this  to be-reviewed  the b l a s t i n g  process  in and  project.  Rock Mass P r o p e r t i e s  Many their  in detail  of these  Thus,  mass.  the overlapping  some  important  engineer.  with  by  parameters.  and t h i s  properties in relation  the fragmentation to avoid  fractured  in conjunction  examine  mass  of design  the b l a s t i n g  p r o p e r t i e s of the rock  prefer  research  i s generally  be c o n t r o l l e d  section  parameters  would  mass  i s achieved  authors  have  relationship  Through  out t h i s  overshadow  The  effects  project,  There  and f a i l u r e  Structural  the rock  the fragmentation  research  the others.  characteristics  with  discussed  two  mass  p r o p e r t i e s and  during  blasting.  o f them have  appeared  to  are the geo-structural  behaviour  of the rock  mass.  Geology  of the rock  s t r u c t u r e on  the blasting  process  109  and  the  scale  fragmentation  and  studied that  macro-scale  by  are  the  also  in  the  rock  1  2  in  The  crack  wave.  energy  i n two  categories:  m i c r o - f i s s u r e s have  laboratory tests. i n two  initiation Secondly,  to  elastic  can  be  by  flaws drive  the  the of  by  been  ways.  First,  passage  of  the  Micro-  rock  large wave  the  branching  cracks.  induce  revealed  micro-  concluded  enhance  behaviour  oriented micro-structures  properties that  They  different  sites  the  requirement  i n f l u e n c e the  Preferentially  grouped  fragmentation  as  tensile  be  effects.  a l  improved  reducing  fissures  et  acting  reflected by  Dally  flaws  there  can  mass.  variations  velocity  anisotropy. Nevertheless,  macro-fissures  blasting  variable  override  any  of  rock  The  existing  1 3  .  conjunction previous The  cracks  that  the  blasting  and  the  1  terminates latter  planes,  defined  the  i s surrounded  as  least  the of  new  cracks  the where  a  where  new  are  or  of  shear  crack  i t intersects true  the  a  when  limits.  network for  of the  failure. to  immediate  tensile  radial  is especially  a  extended  in their  absence  from  r e s i s t a n c e path  tensile  cracks  by  the  in  fragmentation  cases,  these  prematurely statement  jointing  They  p r o p e r t i e s of  already  of  Even  and  i s concerned.  resulting  process,  development ".  mechanical  important  pattern  propagation  because  most  fracture  serve  of  the  fragmentation  and  bedding  i n many  formation  suppressed  of  physical  have  will and  degree  the  blasts,  development  This  the  with  blasthole,  as  are  great  During length,  vicinity  is  i s developed,  i t  stress  pre-existing these  crack.  pre-existing  110  cracks delay  have  periods.  throws the  been  them  In  into  by  those  the  gases  cases,  muck  pile  from  the  b l a s t h o l e s on  blast  with  very  loosens little  previous  the  blocks  improvement  and in  fragmentation. Another  in  major  to  premature  Despite the  This the  of  which  venting  depending  the  to  the  intersect of  on  mass  gases  the  faces  by  relative  the  the  the  or  This  mechanism.  fragmentation  and  dominant  control  engineer  practical  of  the  leads  stability  wedging  blasting  selection  expansion  must  design.  orientation  joint  be  planes,  of  bedding  1  easiest  direction  to  of  discontinuities.  generally  as  fine  allows  the  crater  shape of  between  the  a  i t would reduced  i n f l u e n c e d by  reduced  rock  spacing  direction  joints,  of  The be  i s along  factor.  structural  large should  blasting  burden  would  need  likely  occur  when  4.2-1).  correct  this  i s at  be  1 5  right  "  1 6  of  the  not but The  i t resulting  discontinuities  (Figure  improve to  is  directions,  (energy)  will  will  strike  fragmentation  in other  the  the  i t g e n e r a l l y r e q u i r e s more  fragmentation  the  blast  powder  b l a s t h o l e s i s too  the  instances,  as  fragmented  the  rock  of  is  and  When  but  use  poor  diameter  rock  flyrocks of  over  to  set  major  and  economical  the  gas  blasthole wall.  direction  most  i s the  etc .  The  areas  the  discontinuities,  produce  effective  major  the the  i s g e n e r a l l y done  planes,  macro-structure  c o n s t r a i n t s brought  rock  capable  effect  joints  problems,  by  widened  .  reduced  the  and  spacing  Smaller  problem. angles  energy In  to  to  move  some  in order  the  to  the  111  PREDOMINANT FRACTURING ALMOST PARALLEL TO DIRECTION OF BLASTING  FIGURE 4.2-I' ILLUSTRATIONS  OF THE EFFECT OF  ROCK STRUCTURE ON CRATER FORMATION, (after Bauer ) 3  11 2  assure often  the t o t a l result  especially  degree when  of the face  easier  because  t o e burden  blasting  will  attention  dealing should  fragmentation  with  a r e sometime  situation within  where  the height  premature  Coates  oversize  between  maximum  charges  beds  up-dip  1 8  be where  i s easier  than  1 7  beds  M. these  Table  where  poor  the c o l l a r .  increase also  dramatically  rock  charges  oversize.  The  i n the  seams,  a r e used,  result  i n poor  4.2-3).  a review  s p a c i n g S, 2 shows  situations,  a  Pocket  be n e e d e d  soft  will  (Figure  attempted  planes,  of the  joint  how cases  following  spacing Sj  there are  as the spacing of the b l a s t h o l e s  specified  will  detonation permits  would  the blasthole  Reviewing  area  I f column  bands have  bedding  l i e between  the soft  specification  to occur  However,  blasting  down-dip  toward  and w i l l  of the bench.  and G y e n g e  inter-related.  the  rock  of the hard  relationships  unlikely  Pocket  bottom  wave  necessary  venting through  fragmentation  and  hard  a t 45  But i n t h e case  blasting  although  charges  costs.  Blasting  to the c o l l a r  b u i l d - u p of t h e shock  blasting  The  the backbreak. careful  will  burden,  greater or equal  toe burden.  helpful  the  toe  40 t o 60 d e g r e e s .  quasi-horizontal  occur  down-dip  4.2-2).  be p a i d  may  and l a r g e  70 d e g r e e s ,  be e q u a l ,  (Figure  3  Blasting  reduce  slopes.  reduced  should  up-dip  When  and s t e e p of a  from  a t an a n g l e  the d i p i s greater than stable  slab.  break  the d i p ranges  to the d i p d i r e c t i o n  produces  the  of each  i n e x c e s s i v e back  when  development  breakage  2,3 a n d 5 a r e i s less  discussion  than is  1 13  -FACE  REDUCTION OF BURDEN PREDOMINANT FRACTURING AT RIGHT ANGLES TO DIRECTION OF BLASTING  PLAN  LESS DIFFICULT DUE TO SMALLER TOE BURDEN LARGE TOE  /•BURDENS,  EASIER  DIRECTION  SECTION  FIGURE 4.2-2' ILLUSTRATIONS  OF THE EFFECT OF  ROCK STRUCTURE ON CRATER FORMATION, (after Bauer ) 3  11 4  I  HORIZONTAL FRACTURING  SIMILAR TO (I) - E X C E P T AT THE -COLLAR  mm  ^Soft ilHord Soft Hard Soft I Hard  I  FIGURE 4.2-3' ILLUSTRATIONS OF THE EFFECT STRUCTURE  POCKET CHARGE  OF ROCK  ON CRATER FORMATION,  (after Bauer ) 3  11 5  TABLE 2 EFFECT ON OVERSIZE FRAGMENTATION OF BLASTHOLE SPACING, S, JOINT SPACING, S j , AND OVERSIZE SPECIFICATION, M ( a f t e r Coates and Gyenge  Case  .  Sy.S  Sj:M  S:M  18  )  Fragmentation Sensitive to Powder Factor ?  % Oversize  1  Sj >S  Sj >M  S >M  Yes  Medium  2  Sj >S  Sj >M  S <M  Yes  Low  3  Sj >S  Sj <M  S <M  Yes  Low  4  Sj <s  Sj >M  S >M  No  High  $  Sj <s  Sj <M  S <M  No  Low  <s  Sj <M  S >M  No  Low  6  Sj  1 16  quoted  from  Coates  "Of  the three  the  joint  likely  spacing  blastholes, obtaining the  S.  4,  that  of  size  o f m u c k , M,  fragments  factor than  than  size  pattern.  resolved  and  although  large  Case  6,  specified  size  than  factor.  S j , i s less  t h e maximum of  oversize  i n c r e a s i n g t h e powder a t t h e same be m o r e  breakage  spacing  o f muck  M,  spacing  powder  expensive  with  represents  joint  blastholes, large  either  powder  percentage  i t might  which  with  spacing,  spacing  of secondary  of  blastholes,  joint  by  as  of the  the problem  but greater  solvable  of the r e p r e s e n t a t i v e  diameter  the spacing  easily  of a  of holes  the cost  low p r o b a b i l i t y  and above average  the problem  t h e maximum  larger  be  spacing  effective,  accepting  than  i f i t occured,  t h e b l a s t h o l e s , S,  c a n be  1 i s of  the r e p r e s e n t a t i v e  Reduced  situation  case  larger diameter  i s not u s u a l l y  conventional  .  could  use of  where  1 8  S j , i s greater  large  than  factor.  cases,  fragmentation  conventional  case  Gyenge  However,  correspondingly In  and  t h e same  the  ideal  S j , being  permit and  low  less  the use of powder  factors." The be  used  authors only  situation. and to  their  a s a means Other  degree  the production Finally,  weakness  are not without  as  of quick  variables like of cementation of o v e r s i z e  a higher  evaluation  of the  the v a r i a t i o n are also  this  of  important  t a b l e can  site joint in  spacing relation  fragments.  the frequency  decreases,  specifying that  of d i s c o n t i n u i t i e s  energy  factor  will  be  and planes used  in  of order  117  to  create a  larger  by  generating  a more  density  slurries.  Failure  The rock  physical of  largely  brittle  also 1 9  process  relate  of E l a s t i c i t y  Generally,  have  .  high  a high  to the  their  .  The  ability  a r e of the  which  compressive  In a d d i t i o n ,  1 1  of the  i s a measure of  rocks  e v a l u a t i o n of the b r i t t l e n e s s  to failure.  was  found  fracturing failure  show  a  high  s t r e n g t h and  deformation  at  by L a n g  less  that  2 1  t h e shock  The more  the rock  i t violently. brittle  i s given  of the rock  4.2-4  shows  by t h e  in uniaxial  such  curves  from  rocks.  wave  rocks,  type  the rock  large  fragmentation however,  of energy  mass, wave.  amount  behaviour  of the rock the higher i s In t h i s  of energy  type and  i s g e n e r a l l y good.  plastic will  brittle  of f a i l u r e  of the s t r a i n  stores a  The  a c o n s i d e r a b l e amount  the e l a s t i c  brittle  effectiveness  mode,  curve  Figure  to creeping  blasting.  releases  and  of the rock.  a s s o c i a t e d with  In  by  absorption property  s t o r e and r e l e a s e energy  of the s t r e s s - s t r a i n  rock  It  of  as produced  the fragmentation  The modulus  to break  better  compression  the  i s g e n e r a l l y done  i s minimum.  analysis  during  wave,  and energy  influences  of E l a s t i c i t y  are harder  A  strain  This  p r o p e r t i e s of the m a t e r i a l that  brittleness  failure  was  behaviour  importance.  modulus so  powerful  the m a t e r i a l to absorb,  utmost the  of f r a c t u r e s .  Behaviour  failure  mass  number  deformation  be a b s o r b e d  occurs  during  this  1 18  BRITTLE DUCTILE. TRANSITION  BRITTLE' TYPICAL STRAIN BEFORE FRACTURE OR FAULTING (PERCENT)  <I  1-5  V  COMPRESSION  cr, > o- = 2  2-8  A  il  > 10  //  CT,  O3  5-10  DUCTILE  3  EXTENSION  <r< <r, = cr 3  2  TYPICAL STRESS-STRAIN CURVES  FRACTURE T Y P E I ELASTIC T Y P E m : PLASTIC T Y P E A P L A S T I C T Y P E ^ E L A S T I C TYPEJZHELASTIC ELASTIC PLASTIC PLASTIC ELASTIC • PLASTIC CREEP :  EXAMPLES  BASALT  TYPE  PLASTIC ELASTIC PLASTIC  \^ SCHIST  SILTSTONE  ROCK-SALT  SANDSTONE  MARBLE  FIGURE 4.2-4'SPECTRUM OF ROCK BEHAVIOUR, (after Hendron ) 20  119  stage  i n s t e a d of  2 2  mass.  Failure  associated pushing of  a  to  with  the  shear  blocks  and  but  looking where  burden  that  to  the long  rock  rather  like  in hard  types mass  of  effect  rocks  rock,  will of  from the  and  point  improved The  coarse  This  may  practice  in  inserts  under  chapter  3).  engineer  the  wave  the  type  of  retention  stemming so  that  b l a s t h o l e and  by  making  of  minimum  burden  fragmentation attenuation  burden  distance,  create  tensile  varies  inversely  of  the  stresses. the  reduces The  pit  3  i s easy  to  explained  medium scrape  when  formations, and  Because by  the  use  , the  shave  stress  the  fields  those  that  the  rock  the  expanding  of  an  gases,  adquate  careful  planning  of  freefaces are equidistant that  too  the  great,  wave  to  rate  break"  explosive  the  of  of  should  energy,  attenuation to  large  the p r e - c o n d i t i o n i n g  the 2  result  operators  consider  two  the  distance  mine  must  "uneasy  strain  with  dealing with  sure  i s not  in those  largely  with  any  gases  When  done  by  is  The  concentrated  of  material  pattern  to  burden.  is therefore entirely gas  their  teeth  i t fail  on  expanding  prompts  soft  rock  blasting,  g e n e r a l l y be  or  the  deformation.  within  type  of  fragmentation  i f any,  initiation the  outward  little,  strain  the  rock  blasting  o p t i m i z a t i o n of  length the  the  (see  during  of  experiment  fragmentation the  making  rock,  often  projection  than  fragment ion  situation  blast.  drilling  the  action  is a  given to  of  causing  This  a  for  shearing and  slabs.  used types  failure  uneasy  the  these  the  type  declare  drill  of  being  result  at in  rocks . 1  within  the  potential  the  power  yeild  strain of  1.4  to wave  in  strong  120  elastic  rocks  rocks ".  whereas  Attenuation  2  jointed  rock  largely  reduce  fracturing failure  4.2.2  mass  of  This  this the  rock of  pattern,  according  The  that  factor  pages  emphasises  experienced  over  CATEGORY  The and  degree  to  wave  presence  used  also of  in  less  occurs  in  grounwater as  the  less  brittle the  will  intensity  brittle  is  of the  mass.  the  of  to  different  the  the  work the  parameters have the  been degree  these  1:  design  the The  to  be  rock  geometric  parameters  done.  mass,  This  the  have  to  be  across  the  i s , after  the  second  most  fragmentation.  that  will  be  discussed  classified  by  the  of  charge  e x p l o s i v e energy,  control  the  B L A S T H O L E DIAMETER  of  of  in  author  blasting  the  in a  system  engineer  parameters.  category  bench  height.  control  these  parameters. to  importance  fragmentation.  allocate  the  bought  the  in determining  parameters  equipment  are  i n c r e a s e s , the  rock  p r o p e r t i e s of  design  following  2.5  Nevertheless,  mass  the  between  in order  important  the  examines  the  balanced  structural  strain  the  to  Parameters  on  relationships  of  effect.  paragraph  distribution  up  although  behaviour  Design  values  one  Generally,  match  There mine  AND  are  the have  design,  the  BENCH  blasthole  blasting been  HEIGHT  diameter  engineer  fixed  production  by  the  does' not type  of  requirements,  121  regulations that  include a  height  would  level.  not  of  size.  such  2 6  This the  the  poor  the  large  .  However, limit  the  i n the  fragmetation . i n an  large  the  achieved the  must  proposals  diameter  or  at  management  upper  understand  bench  the  fragmentation  process  the  diameter  intensely and  of  of  when  the into each  fractured the  use  must  limit  i n the  effective the  use  at  a  come  and  the  diameter  of  the  given  in  the  also  volume.  to  and  of  blastholes  likely  of  an  increase  blasthole  i s more  pattern  degree  40  In  because  site,  an  equals  height.  the  is  blasthole  burden  bench  with  maintain  occur  In when  used.  influence  rock  mass.  block rock  of  the  blasthole  is subordinated  large  of  the  Thus,  instability  the  upper  equals  large  are  blasthole  explosive across  to  fragmentation  burden  only  controlled  Design  i s generally coarser  factor  in order use  when  or  volume.  charges  characteristics divide  the  when  the  uneconomical  ponctual  of  of  energy  p i t wall  degree  .  enthusiasm  i s an  diameter  rock  Nevertheless, the  there  fragmentation  The  1  reduced  i s reached  diameter  addition,  on  2 5  blasthole  engineer  parameters  c o s t s are  collar  blasthole  results  blasting  distribution  increase  the  received with  the  blasthole  cases,  constraints  costs.  Drilling  times  be  these  operating  increased  dilution  m o d i f i c a t i o n of  However,  influence on  and/or  Where  blocks, is  the  fragmentation  diameter  joint  fragmentation by  a  on  structural  pronounced  intercepted  mass,  larger  good  to  diameter  planes  will  blasthole. is  blastholes  be In  structurally causes  122  relatively The bench  small  geometric  height  Persson ratio  reduction  and  and  2 6  of  30  relationships (effective)  Bergmann  to  i n the  obtain  good  of  between  burden  suggest  2 7  degree  a  are  fragmentation.  the  blasthole  well  documented.  burden/blasthole  results  within  a  diameter,  cost  diameter  effective  design. Although diameter  up  studied  the  higher  was  that  This  the  burden,  coarse  fragmentation, H/Be  was  CATEGORY  The and  the  control  the  of  are  variables.  these  narrow  was  and  and  Ash  two  the  process.  is  parameters. bench  times  same  size  have  2 8  when  conditions  toe  charge  blasting  over  being  blasting  the  improved  values  medium  the  (Figure  4.2-  developed They  formation  in  observed situations  one.  SPACING  category  variables the  Smith  bending  explosive properties. over  since  between  else  backbreak to  expensive,  breakage  to  the  BURDEN,  parameters  eventually spacing  by  during  equal  2:  one  everything  the  more  blasthole.  from  within  where  better  relationship  is explained burden  slightly  fragmentation  increased  (effective) 5).  be  i n the  geometric  showed  height  may  blastholes give  brought  They  these  range  often  considered  There  are  AND  two The  are  the  blasting  although of  EXPLOSIVE  spacing/burden engineer  important,  the  has  ratio more  economic c o n s t r a i n t s  alternatives.  as  PROPERTIES  principal  indeed,  but  The  burden  blast the  and  design  initiation  1 23  FIGURE 4.2-5« TRENDS OF FRAGMENTATION INDEX, F , WITH L/B c  AND S/B RATIOS, (after Smith and Ash ) 28  1 24  sequence burden  can  and  effective  totally  spacing spacing  are  effective  burden  the  blasthole  and  which  detonates the  volume  6).  When  the  strain  uneven vent  the  .  a  material.  and  The  should  carefully  optimum,  results  mine too  and  The  and  the  are  face  developed mass.  will  When  the  with  cracks  the an  of  and gases  stemming aggravated  first  expanding  dealing  4.2-  efficient  row  effective  and  for  (Figure  expanding  face  the  the  attenuation  increases.  flyrocks  generally  The  and  between  burden  radial  for  thus  fracturing  instant  the  ejecting  the  distance  the  large,  Therefore,  as  at  (Be)  process.  i s maximum  inadequate  of  blasting  effective  rock  by  Consequently, burden  shortest  optimum  escape  venting  burden This  gases  is  less  usually  through  airblasts. too  burden  the  However,  large  rather  than  burden.  dimension  s u g g e s t s Se/Be  is a  ratio  exercises  optimum  the  the  rock  holes  wave  such  effective spacing  the  cracks  effective  i s too  designed.  problems  relationship  of  pattern.  to  free  in less  reaction).  i n premature  small  3  of  strain  operators  Bauer  burden  subsequent  (chain  as  i s an  generally  situation be  related  fragmented  results  network  fragmentation  burden  well  effective  energy  t o as  effective  pre-conditioning  into  than  when  There  of  drilling  i s defined  the 2 9  the  referred  (Se)  The  charge  alter  a  function  between  dominant  i s therefore  2 and  control  depending  of  the  5.  This  over  upon  burden  the  and  geometric  radial rock  cracking mass  structure. Finally,  on  the  practical  aspect  of  drilling  and  blasting,  125  BURDEN  4 \ Doming of ^ the surface  a) COMPLETLY CONTAINED, ONLY FAILURE IS PULVERISATION NEAR THE CHARGE AND RADIAL TENSILE FAILURE RUNNIG OUT FROM IT.  b) START OF SURFACE FAILURE BURDEN NOT BROKEN.SOME DOMING OF THE SURFACE. c) SURFACE AND SUBSURFACE FAILURE ALMOST MEET THERE WILL BE A SHELF OF UNBROKEN ROCK BETWEEN THE TWO, DOMING OR SURFACE BULGING. d) FULL CRATER, BURDEN COMPLETLY BROKEN OUT. SURFACE AND SUBSURFACE FAILURES RUN THROUGH TO THE SURFACE.  . e)'FULL CRATER, LOWER ' VOLUME THAN OPTIMUM •• FINE FRAGMENTATION NOISE, FLYROCK, BOWL 7 SHAPED CRATER.  FIGURE 4.2-6'SCHEMATIC OF THE EFFECT  OF DECREASING  THE BURDEN ON SIMILAR CHARGES FIRED IN ROCK; ( after Bauer ) 3  126  mine in  operators  case  the  of  of cave-in,  spacing  always  rather  done  balance The  emphasize  the d r i l l e r than  during  cost  about  hole  the detonation  as expensive  are  expensive  products.  lining  procedures  reduce  the total  with  w e t ANFO  smoke  during  the importance  operations, makes  blasting  Massive  provided  expanding  also  formation by h i g h  will gases  need  form,  of pre-pack  on  i n wet h o l e s a n d  in Figure by  3 0  .  a maximum  slurries  whereas  b y ANFO.  In  orange-  t o note  that,  efficiency  The e x p l o s i v e  the rock  of bubble  4.2-7.  downstream  require  a maximum  i n strength of  2 0 % o f t h e ANFO  alternative  They  pumping and  indicated  results  slurries-are  t o a minimum.  i s shown  has t o c o n s i d e r  as provided  a  I t i s important  of only  density  to minimize  Utilization  be e v e n t u a l l y  will  'E x p l o s i v e s a r e  In such  content  an e c o n o m i c a l  process  rock  mass  results.  The r e d u c t i o n  of b l a s t i n g  become o u t  p r o p e r t i e s , the rock  t h e u s e o f ANFO  blasting.  the reduction  slurries  selection  will  i s not  function of the  In a d d i t i o n , hole  cost.  i n c r e a s i n g water  field,  given  i s a  h a s t o be kept  can permit  on  process.  a s ANFO.  products  yellow  holes  costs.  or custom  ANFO  the adjacent  the explosive  and h a n d l i n g  h i s new This  b u l k - d e l i v e r e d on t h e p a t t e r n  twice  very  attempt  dimensions.  of the explosive  slurries  rock  should  i s that  alternatives,  transportation  as  practice:  p r o p e r t i e s and the expected  generally  the  the following d r i l l i n g  the burden  and the r e s u l t  selection  relative mass  should  mass p r o p e r t i e s .  of s t r a i n highly  energy  fissured  from t h e  Practically,  energy  mine  127  3500 UJ  a.  £5 H UJ 5  < a *  E E  3000 .  < i E >- —  o o _J  2500 -  Ul  >  z o Si z  g  NO  UJ  o  DETONATION  2000 2  4  WATER  FIGURE 4.2-7'EFFECT  6  CONTENT t %  8  1  BY WEIGHT)  OF WATER CONTENT ON THE  DETONATION  VELOCITY OF AN/ FO.  (after Leighton ) 4  10  1 28  operators  are  problems of  using  and/or  engineer there  i s given should  i s an  collar  optimum  height. of  suggests  a  Buchta  suggests  his  own  the  to  tests  subdrilling  function  the  the  of  the  blasthole  time  extra the  two  is  of  5  of  .  serious the  advantages  explosive  The  blasting  blasting situation,  COLLAR  are  the  (Figure  4.2-8).  Page  between  range the  the  sludge  at  to  0.4 of  in  2 9  density  Be  good or  the  practice  drill  blasthole.  and  Be, Hoek  of  performing role  of  etc.  is the  blasthole), Where  b l a s t i n g of  to  drill  a  cuttings  which  may  However,  of  the  subdrilling  foot  2  criteria  c h a r a c t e r i s t i c s of per  a  1 7  0.5  p i t . ' The  optimum  and as  whereas  between  e f f e c t i v e burden,  drilling  and  design  the  grade  Hagan  0.0  importance  ( i e . , energy  the  subdrilling defined  wide  to  the  usually  0.1  rock  HEIGHT  are  d i f f e r e n t domains  it is a  the  AND  three  engineer  explosive  for  3  from  s t r u c t u r a l and  long,  "  each  ranging  This  according  between  distance bottom  Be.  break  of  1  parameters  height  diameter,  interval  blasthole  category  interval  the  to  3  for  SUBDRILLING  of  an  Thus  type  that  until  demonstrate  discussion  literature  blasting  in  is  blastholes.  rock,  3:  0.3  the  possible  studies  e f f e c t i v e burden  to  as  explosive.  subdrilling  0.2  signifies  the  These  function  suggests  cost  acknowledge  parameters  3 6  much  Complete  in  CATEGORY  The  as  detailed  slurry explosives.  selection  in  ANFO  the  the  certain accumulate  over-drilling  should  1 29  «» v. «A  <U ••-  30Charge height is about one-half the bench height  £  x o Ul h-  X  c E E CO  20-  o z Ul X  CD  Column zone  10-  /  Bottom exp osive charge  Floor  -5-  Subdrilled zone 10 20 BURDEN (meters)  FIGURE 4.2-8 • RATIO AT BENCHES (after Buchta  130  be  minimized.  It  may  cost  operations.  In  such  proper  to  avoid  depth  vibrations  and  insufficient those  practice the  row  The  can  stemming  the  damages  be  length  venting  has  of  to  the  in a  waste  such  poor  fragmentation,  subsequent  collar the  height  bench.  material cheapest  2 3  may  there  material  CATEGORY  4:  create though are  to  backfilled  other  floor  the  improve and  ground  and  toes  increase  to  hand, blasting  on  each  subdrilling  on This  careful  of  rock  design  Finally,  mass,  in  the  nothing. be  kept  long  gases  and  and  the  0.7  force  them  to  in  push  column  problems  free  hand,  not  because  a  Be.  the  stemming  of  fragmentation  used  1.0  associated  other  are  and  resist  the  absence  cuttings  generally  to  through  and On  blocky  enough  energy  toes etc.  between  face  for  a  too  long  the  top  part  the  there  best are  POWDER  INTERVAL, FACTOR  INITIATION  S E Q U E N C E AND  of  stemming the  available.  DELAY  in  displacement.  alternative.  venting  drill  large  excessive  pit  fractured  explosive  blasthole,  Even ,  of  the  bench  expanding  Premature  like  in  be  i n more  to  next  be  must  high  2 7  blast  should  results  the  a  better  reduced  On  results  in highly  height  burden.  as  load.  the  is a  $750,000/year  effects  causes  multi-row  burden  collar  premature out  collar  b l a s t s or  subdrilling  The  of  row  perimeter  adverse  Some o p e r a t o r s  severly  front  to  blastholes  eventually  shot.  front  cases,  subdrilling  conditions  successive the  poor  up  DESIGN  131  The  parameters  of  category  four  initiation  sequence  and  the  parameters  on  which  the  blasting  Variations  in  the  on  the  the  drilling  degree  cost.  The  limited  by  The  on  initiation  and  delay  the  of  the  blasting  quality of  fragmentation, on  ratio.  and  created,  in multi-row  in  the  following are  poor  initiation  to  next  take  row.  row  choked.  If  the  delay  occur,  unless  is  used.  Thus,  be  used  being  holes  rock  et  along  a  prone a l  3  one  best  cut-off  mass  7  by  line  delay  interval  tight caused  period delay  were  by  down  the  It  in  i s too  on  only  the  free  of  is  movement the  of  charges  the The  The  shot  results  becomes  are  initiation longest  experiments between  likely system  that  can  dependant  fissured  to  face  short,  is generally  regard  face  problems,  i s the  intervals  is  delay  cut-offs  hole  In  free  burden.  toe  highly  disruption.  effect  blasting,  sufficient  long,  interval  delay  by  cratering.  i s too  is  bench  initiation  pile,  problems.  tested  design  previous  muck  control.  production  effective  allowing  the  the  are  i t s influence  effective  to  different  row  of  prior  by  These  crew.  The  the  the  total  total  controlled  characteristics,  to ,  are  interval  long  the  without  more  Bergmann  the  flyrocks  to  the  place  with the  interval,  significant  in open'pit  sequence.  i s overloaded  and  If  Both  no  pattern  availability  blasts,  fragmentation,  backbreaks  upon  the  have  reduce  the  Se/Be  burden  can  exerts  but,  of  interval  the  costs,  delay  factor.  engineer  originality  dependent  the  blasting  the  powder  sequence  fragmentation,  degree  strongly and  of  design  are  rock  mass  carried adjacent  fragmentation  by  1 32  optimization between  3  ( F i g u r e 4.2-9).  and  6 millisecond  effective  burden,  designing  a  system.  The  initiation stress of  of  holes  delay .row,  ratio with  an  9 ms/m  limit  infrequently  jointed  equal  to  or  holes  in a The  two  a  square  simple  V1  the  as  pattern  before  a  Be  the  uniform  smaller  of  i n the  Andrews  the next  suggests  3 8  holes  along  of  i n massive  interval ratio  number  fragmentation.  charge  (5 m s / f )  delay  simultaneous  development  between  delay  Be  between  used  the  the  between  pattern  height/effective  of  the  burden  breakage  with  VI  i t i s easy  initiation  However,  in V  give  ratio  stated previously.  because  Therefore,  patterns  because  additional  full  initiation  more  in a  s p a c i n g / e f f e c t i v e burden  square  patterns  15 and  tie-up  and  the  ms/m  ( F i g u r e 4.2-10).  V  resulting  of  considered  the  a  of  fragmentation,  drill.  the  produces  ms/f)  times  hole  when  or  rows  the  row.  drilling  to  the  sequential blast,  rock;  three  effective  influences  (3  down  of  point  row)  on  hole  a  starting  t h e r e f o r e poorer  depends  For  upper  and  no  interval  2 ms/f)  that  rock,  each  good  and  delay  consider  in  the  (1  that  must  one  around  of  a  with  engineer  fractures  i s detonated.  be  blast  suggests meter  (along  fragmentation  network  per  would  row  blasting  defined  Optimum  hole  per  distribution  well  crack  row  this  It  rather  better  than  in-flight  i n V1.  the  two  mines  lay-out  pattern  fragmentation  These  Many  i t is often  m o d i f i c a t i o n of ratio.  to  also  and  should more In  than  use  be  simple  a l l cases, in-line  bench  patterns  collision  3  9  .  to  also  cause  1 33  65  •  o Ul N  = Square pattern, 13-in. burden, 13-ln. spacing.  A= 50-  Rectangular pattern I, 11.0-in. burden, 15.5-in. spacing.  O = Rectangular pattern II, 9.2-in. burden, 18.4-in. spacing.  CO  2  52  35  n- 30 ui o 25 rr ui 20 <  Best commercial delays  J  I  0.2  L  0.4  J  0.6  L  (according to Langefors)  0.8  I  I  1.0  DELAY RATIO, MILLISECONDS  I  PER  I  1.2  I  I  1.4  I  L  1.6  FT. OF BURDEN  FIGURE 4.2-9'EFFECT OF DELAY TIME BETWEEN SHOTHOLES AVERAGE FRAGMENT SIZE. THE SAME FACTOR WAS  USED  1.8  ON  POWDER  FOR ALL SHOTS, (after Bergman 8 all ) 37  1 34  F•ACE "—  i— • 0  •  *  A o  B  •  o  *  •  •  -#—---m  -•  2 -•—---•  •  I  •  •  -•-  C  \  •  • \  V \  \ V  N  X  A / /  * \/ n \i A B  % tV\  B  e  -V  •  F  R  A  /  /  y A  2,.  / A  ».^G«2  •!  H»5 -•• 10  "~  ~ D  •!  «2 ,J»  a-'  «5 ,J»  ~  (g) SQUARE V2  1. 2. 3. 4  SQUARE Pattens in-line V VI V2  ;  7  \  \  /i  /  /  6  v  /»  Q C  V  \ ? \ \ / / / j  B  (f)STAGGERED VI [•  -a  °  r j*  ^  7  D  \m  ,^a .|:0  /  V J J J J c —'D ;K f /  Y ^-i--"/  ^--"'Ifi 7  (h) STAGGERED V2 STAGGERED Pattens I. in-line 2. V 3. VI 4. V2  FIGURE 4.2-10' BLASTHOLE/ INITIATION PATTENS FIRE  \  0»X ~fF ~f J^Jf  A  R  •  0  F  PATTENS Se/Be 1.0 2.0 5.0 quasi 10.0  a—-•  (b)STAGGERED IN-LINE °  \  8  -  •—--•  Y R\ <AB> ^ \ 2 (d)STAGGERED  F  »0  •  •2 --—a  •  k 3Y 2V \ * J»  4  -  c  a—-•  I  -a  8  $ .  ' > "  (e) SQUARE VI  B  a  \  1  A  SQUARE V "<^<\D^'>'V'' (c)  #-—-m •  -•  -  •  0  •  E  -  7 . - - •  - •  / / "/ AT^  \ <g*  \ \  •  D A  (a) SQUARE IN-LINE  °  8  •  FACE'  —-- —  0  •  A  —  WITH  TO AN OPEN FACE, (after Hagan j 39  PATTENS Se/Be 1.0 1.25 3.25 quasi 7.25  B = S FOR SHOTS  .  135  Delay pit  slope  interval stability  simultaneously Figure  4.2-11  instantaneous blast. used  and  On  V  reducing  the important  charge  initiation values  the following  = K  With  the  maximum  the  p i t limits.  values are  V  = particle  velocity  W  = weight  of e x p l o s i v e  R  = radial  distance  field  charge  by u s i n g  is  face. the  and B = -1.5  from have  the been  general  engineer  constants  delay  of  detonation  to  determine  specific)  as a  specific  per  tool  pattern  must  and that  are easily  moves  remember only  toward  that  average  determined  the values  i n the  seismograph.  of  i n the f i e l d covered  free  at distance  the point  as the b l a s t  blasting  Those  a  between  detonated  from  (site  be u s e d  per delay  The  here.  Because and  should  toward  fired  equation:  (USBM)  of K and B a r e s i t e  given  = 200  i n f l u e n c e the  of e x p l o s i v e  and damages  (R/W**-2)**/3  figure  also  relationship  of K  K,/3 = c o n s t a n t s  This  the blast  shows  figure,  sequence  t h e amount  a n d by d i r e c t i n g  this  to solve  by  initiation  i t sintrinsic of t h i s  importance  investigation,  in a particular  paragraph.  i n the b l a s t i n g the design  powder  process factor  136  Distance from blast - metres  I  5  I  10  •  i  20  50  '•  i  100 2 0 0  i  500  1  1  «  5000  1000  1  •  ,  20000  Distance from blast - feet  FIGURE 4.2-11  PLOT AT  OF PARTICLE  GIVEN  DISTANCES  VELOCITIES INDUCED BY  PARTICULAR 2,  CHARGES  (after  Hoek and Bray)  1 37  4.2.3  The D e s i g n  The  powder  misunderstood operators numbers  to  a r e now  consistent  multiplying  explosives  (energy)  straight  ANFO  be  poured  i n each  as  uniform  generally free  facing  factor of  this  factor  the problem  research  project  by d e f i n i n g  a n d t h e Rock  There  a  powder  i s an optimum  factor  powder  However,  weight  of  the  into  and thus, i s  factor  that  the t r i a l  include  engineer i s powder  i n the p i t .  relationship  to  does take  t h e optimum  domain  loading  distribution  the blasting  i s to simplify reliable  leads  by  of e x p l o s i v e  of the b l a s t h o l e  blasting  Quality  factor  and type  of determining  different  i t srelative  rationalizes  the accounting  and overbreak.  f o r each  procedure  than  content  t o keep t h e energy  The d e s i g n volume  energy  i s done  fact  a s 100.  therefore  i n order  the burden  higher  fixed  blasting The  This  by  tool,  product.  strength  the quantity  as possible.  digging  still  hole  used  The weight  engineer  by d e t e r m i n i n g  only  factor.  of explosive  procedure  account  different  many  design  of the  and c o n t r o l l e d  i s arbitrarely  blasting  as an a c c o u n t i n g  understanding  possess  factor.  Although  i t as an e f f i c i e n t  o f t h e powder  the weight  strength  The  a good  a n d y e t most  of b l a s t i n g .  factor  using  results  the normalization  widespread  in the f i e l d  t h e powder  I t permits  different  Factor  i s t h e most  statistic  consider  quantity.  that  factor  o f them  process,  Powder  The  and  between  scope  error t h e powder  Index.  powder  factor  f o r each  rock  mass a n d  1 38  blasting  conditions.  fragmentation miximum factor  has  further  been  from  improves  i s reached  deteriorate  level  4.2-13).  This  final shot  wall. by u s i n g  balance  this  reduction, range A  against  wide  factor,  f r e e f a c e s and  on a t r i m  t o be c h o k e d  p r e v i o u s l y - s h o t muck  are concerned of f l y r o c k  with  There  related the cost  hazards.  design the delays  counter  level.  The  perimeter  shot  i sin  0  i s said  "freeface".  of the  * .  The shot  and disadvantages  because  1 9 +  However,  t h e powder  shall  vibration  (Figure  8  primacord  of down-the-hole  effective  i n the ground  by a  3  i s reduced.  engineer  p i tmining  the v e r t i c a l  operators  advantage  20%  obtained  the integrety  i n open  into  c a n be  i s that  practice  of rock  of 2 or 3  factor  rule  the blasting  to create  increase  factor  to maintain  o f 35 t o 50 p e r c e n t  advantages  out  i n order  by a b o u t  p i t , the ground  output  the general  to  However, i t  i s reduced  i s side-initiated  the energy  i n t h e powder  situation. firing  case  t h e maximum  i n order  open  a  t h e powder  the fragmentation  i n t h e powder  ANFO  Therefore  systems  the  when  i s increased until  Increasing  i n c r e a s e d by a  blasting,  i s reduced  factor  factor  i n a given  reduction  In t h i s  perimeter  factor  c a n be  constant,  of e x p l o s i v e energy.  i f t h e powder  value,  intention  kept  e v e n t u a l l y causes  that  vibration  in  a s t h e powder  and i s a waste  1 0  shown  downline.  everything  ( F i g u r e 4.2-12).  then  t h e optimum  without  With  i s the choked when which  i t deals lies  with the  directly  i s a number o f  to this  practice.  of moving  Others  blasting  want  Some  equipment  to minimize  i n and the  139  0.4  0.5  0.6  EXPLOSIVE CONSUMPTO IN  0.7 (lbs/ton  0.8  EQUIVALENT AN/FO)  FIGURE 4.2-I2' SHOVEL PRODUCTION ON A YEARLY BASIS AT  '  ONE OPERATION VERSUS EXPLOSIVE CONSUMPTION IN ROCK OF 20,000 PSI STRENGTH, (after Bauer ) 3  COMPRESSIVE  140  0.5 POWDER  0.6 FACTOR-1b/LT  FIGURE 4.2-l3 = A PLOT OF GROUND VIBRATION VS POWDER FACTOR MEASURED FROM A SERIES OF PRODUCTION BLASTS AT A LARGE OPEN PIT MINE SHOWING THE ABRUPT INCREASE OF THE LEVEL OF GROUND VIBRATION AS THE POWDER FACTOR IS DECREASED, (after Andrews ) 38  141  movement in  of d r i l l i n g  the p i t .  drilling also  Further  close  practice  orebody  equipment  or to accumulate  blasted  advantage  i s the increase  in safety  to the crest choked  in relation  also  be t h e r e s u l t  mine  planning.  blasting  of blending  In any c a s e , First,  floor  rock  to assist  result  i n an uneven  higher  ground  effect  on  increased  fragmentation Hagan need  2 9  factor  constant.  acknowledges  f o r an  propose  p i t floor.  powder  increase  any numerical  mechanisms  which  the  rocks.  buffer  displacement intervals satisfying  rely  results.  i n order  value. on  Only  by c h o k e d chocked t o keep a  requirement  the breakage Lang"  1  blasts  shots  i s the  and i t s  necessitate  the degree of factor  of  1.1  reduction  while  and the  b u t he d o e s n o t  In h i s o p i n i o n , wave  i t may  disadvantages  fragmentation  the strain  to maintain  second  suggests  0  an o v e r a l l  are altered.  i n order  caused  Finally,  i n energy  the following  at the toe region,  The  Bauer"  inadequate  i s no n a t u r a l p a r t i n g a t t h e p i t  displacement  stability.  I t can  or simply face  may  of the  requirements.  will  when  operators  of the width  operators  level  Mine  requirements  i f there  vibration  slope  because  to the production  disadvantages.  an  of the bench.  reserves  the  fracturing  a r e n o t i n f l u e n c e d by  mechanisms  proposes  that  longer  the fragmentation  require  delay and  obtain  142  4.3  ROCK MASS  The blasting under  characterization and  been  This  The  developed  by  blasting  the rock  e v a l u a t i o n of  will  of  mass  in regard  t h e optimum  review  the b l a s t a b i l i t y  scientists  during  and c r i t i q u e  with  powder  c o n d i t i o n s a r e the main  a t t e m p e d by many  section  The  of  the determination  specific  project. has  BLASTABILITY  of  factor  subjects  of  the rock  mass  the l a s t  typical  20  this  years.  relationships  recently. determination  of  rock  mass  blastability  the  blastability.  c a n be  obtained  the f o l l o w i n g methods: 1) v i s u a l 2)  determination  geophysics, production  by  laboratory, 4)  blastability  5)  rock  4.3.1  Visual  This amount  of  site  one  in-situ index  or  o r more or  rock  drilled  p r o p e r t i e s , measured i n  both. small  characterization  with  production  of  i s f a r from  specific  range  in  Western Canada. he  with  Determination  method  boreholes  from  a wide  that  special  derived  in  hopes  using  blastholes.  3) c o r r e l a t i o n  mass  of  of  will  rock By  t h e Rock  optimum  experience mass. trial  or a  This and  and  crater rotary  requires a great  tests. drills.  Blastability  deal  i s t h e method  error,  eventually define  Mass  scale  certain of  generally  the b l a s t i n g  t h e optimum  experience used  engineer  powder  factor  143  in  each  and  process.  every  Trial  evaluated. performed for  a  shots  Several before  detailed  strongly  domains have  shots  filing  test  blasts.  cost  operations  are-very  final  and/or  more  4.3.2  costly.  possible  Those  data  variations density, useful, the  Using to  are  i n rock  primer energy. because  mass  can  and  determine  optimize  These of  data  their  monitored design  and  must  T h i s method  use  of  when  the  variability  photographs  on  the  the  caused  conservative slope  of  Rock  By  Geophysics  known  of  the  in the  and  rock  form  of  softer Based the  type  or on  location  of  or  can  used  relationship  be with  are  optimize.  Methods  as  be  sonic  show velocity,  i n f o r m a t i o n can  the  of  rocks  charge,  reduce  only  as  wastage  rarely  be along  blasting  booster of  blastability  one,  i t  blasted.  that  layers  and  technicians,  i n f o r m a t i o n , the  fragmentation hardly  to  logs  of  harder this  skill  mass  p r o p e r t i e s such This  the  exploration geologists  equipment on  to  unit  angle  want  Mass  to  rock  performing  we  the  are  downstream  damage  asks  i n the  is continually  procedure  a  be  situation  etc.  length.  slow  the  operation  of  is a  i s the  data  identifying  blasthole  and  It  parameters.  Moreover,  well  presented  tested  any  such  special  resistivity, in  engineer  are  obtain  carefully  of  design  This  methods  geophysists. is  of  Characterization  These  be  every  the  high.  the  property.  However,  properties i s high,  even  of  system  mass  The  the  to  alteration  recommended.  wall  on  a  and  explosive index few,  rock  144  mass  properties,  principal  In  increases,  in  needed  cost  efficient  for  can  Correlation  This Various the  be  attempts  rock  mass  compressive  strength whereas Casayus  have  index  has  strength  Those  of  rock  properties  and,  in  addition  the  rock  mass.  properties  and  do  not  experiments such  as  with  a  the  work  relate as  the  or  a  were  in  carried  More  the  of  these  Rock  In-Situ  One  of  done.  first  strength/tensile behaviour  the  Munozrock  (Figure poor  of  uniaxial  the  behaviour.  static  by  blasting.  been  plastic  generally  of  blastability  etc.  factor  the  use  or  has  r e l a t i o n s h i p between powder  amount  Young's Modulus,  brittle  measured  material  The  One  The are  balanced  Laboratory  indicates  consider  sonic  be  u n i a x i a l compressive  the  were  the  result.  strength,  r e l a t i o n s h i p are  that  Other  a  to  of  They  p i t production  of  such  indicates  published  In  most  tensile  value  compressive  open  made  low  value  types  been  the  high  4 2  where  was  A  would  Measured  used.  is cost.  hardly  Blastability  properties  ratio. a  the  are  d i r e c t i o n , the  will  in  strength,  blastability  shot  justified  field  with  dip  that  of  methods  variability  design  Properties,  i s the  the  and/or  daily  blast  d i f f e r e n t logs  these  as  strike  each  not  Mass  in  addition, the  data  4.3.3  several  consideration  expensive.  methods  unless  uniaxial  4.3-1).  due  to  the  laboratory  fact  tests  structural properties  on  v e l o c i t y were  the  site.  related  Rock  with  the  of  mass powder  1 45  O  40  tsd  ro  35  *  •— x.  ho  z UJ  30  cc  \-  (/)  Ul  >  if)  </)  Ul tr Q_  25 20  o o  15  < X <  10  _l  z  5h  0.2  0.3 P0WDED  0.4  0.5  0.6  FACTOR ( Ib/S.ton)  0.7  FIGURE 4.3-1 UNIAXIAL COMPRESSIVE STRENGTH VS !  POWDER FACTOR.( after Munoz-Casayus ) 42  1 46  factor. in  the  mass in  Velocities rock  mass  showing  the  a  Coppor and  of  The  blastability  and  are  by by  the  Figure  Heinen  is also  and  4.3-2  of  the  directly  Because same  a  related.  rock  reduction  Kennecott  both  rock  in  the  of  3  fractures  reduced  shows  Dimock*  Broadbent.  are  number  accordingly with  f u n c t i o n s of  there  as  velocity  behaviour,  developed  Corporation  velocity  mass  T h i s method  has  disadvantages: 1.  Soft  m a t e r i a l ; shows  higher 2.  than  Shooting  The  Heinen  and  savings  line  survey  uniform  claimed  surveys  cost  area  m/s  (2000  fps)  frozen. must  be  i s not  done  when  the  o p e r a t i n g due  to  hard  anomalies  could  result  below  the  in velocities  mining higher  normal.  Dimock  seismic  of  surveyed  than  when  600  noise.  presence  level  velocities  lines  i n the  background 3.  normal  seismic  equipment  the  decrease  elasticity.  characteristics, few  to  increase.  plastic  modulus  relationships  tend  that  performed  the are  cost  of  the  seismograph  insignificant  compared  to  the  operation.  However,  per  120  meters  (400  ft)  is sufficient  times  more  are  needed  structure,  4  i f only  one  and to  seismic  in areas  in areas  the  of  of  high  variability. When  the  controlled, and  powder  fracture  process  relationships factor  is believed  between  ( F i g u r e 4.3-3)  the or  to  be  intensity  blastability  structurally of  fracturation  index  147  0.6  /*  0.4  / AVERAGE OF BLASTS  c o  0.3  (A  \  JQ  /  tr  /  /  / /  *  '  /  /  /  '  /  (D i  it  u. rr ui  0.2  /  S  /  /  VELOCITY BROKEN ROCK "  1  i  J  A  / / I  /  /  © : HEINEN AND DIMOCK (|): BROAD BE NT  /  Q  /  /  i  1  IUJ  S|£ 5l§  II 3  UJIt  I4 I  5  1 6  I I 7  8  ACOUSTIC VELOCITY (1000 ft/s)  FIGURE 4.3-2' ACOUSTIC VELOCITY  VS POWDER FACTOR,  (after Heinen and Dimock ) 43  1  10  0.3 h  b  0.4h  0.1 h  26 FRACTURE FREQUENCY  FIGURE 4.3-3 • FRACTURE FREQUENCY VS POWDER FACTOR.(after Ashby ) 30  90 FRACTURES/METRE 2,8 FRATURES/F00T  1 49  (Figure  4.3-4) h a v e  Finally, and  Olsen"  to  6  tunnelling. measuring function  an  of  analysis,  the  given  they and  jointing  intensity  claimed  a  to point  could  developed  be  4.3.4  a  rock  evaluate  of  the  mass  is certainly Bauer  et  b l a s t a b i l i t y index  In  energy crater  factor  to diameter  depths  and  scaled  volume  at  a  ratio  scaled  depth  occurs  of  depth using  velocity,  laboratory  0.9367.  mass  the  of the  of  by  a l "  7  based  computed  tests,  length  the  in  blasting  Then,  Christensen  results as  a  regression  tensile and  This  the They  example  classification  rock  by  was  system  mass b l a s t a b i l i t y .  Small  Scale  Tests  rock  by  blasting  B l a s t a b i l i t y by  l o g i c a l method  out  by  b l a s t a b i l i t y index.  coefficient how  taken  drilled  sonic  i n the  field  most  strain  the  to  the  of  charge.  rock's  The  carried mass  out  Determination Crater  the  to  to  e v a l u a t e the  measured  correlation  reviewed  they  the  been  resistance  normalized  density,  has  in percentage  related  strength  the  field  advance  a  developed.  o r i g i n a l approach  evaluate  In  the  been  determining  blasting at  I.O.C.  on  the  from  spherical less  crater  embedment optimum  optimum  charge,  volume  6,  developed depth  of  were a  ratio  rock and  the  tests. approximated  i s detonnated  is plotted  (Figure  b l a s t a b i l i t y of  Experiments  They  crater  than  depth  i t .  the  4.3-5). embedment  as  a  The Zo.  by  at  a  different  function maximum The  of  1 50  1.6 1.5 1.4 1.3 K = 1.96-0.27 Ln(ERQD)  1.2 I.I i.o  2  ac. P 0.9 o >-  0.8  m 0.7 3 0.6 CD  0.5 0.4 0.3  CORRECTION FACTORS FOR ESTIMATING JOINT STRENGTH ESTIMATION OF QUALITY STRONG MEDIUM WEAK VERY WEAK  0.2 0.1 0.0 * 0  ALTERATION FACTOR  10  20  30  1.00 0.90 0.80 0,70  40  50  JL 60  I  70  ERQD = R Q D * ALTERATION FACTOR  80  90  FIGURE 4.3-4 BLASTABILITY FACTOR VS EQUIVALENT RQD. :  (after Borquez  4 5  )  100  151  FIGURE 4.3-5 VARIATION OF BROKEN !  ROCK VOLUME  WITH DEPTH OF EMBEDMENT FOR A CONCENTRATED CHARGE, (after Coates and Gyenge ) 18  1 52  explosive at  the  is  completely  critical  following  depth,  Zc  =  E(W)**l/3  Zo  =  AOE(W)**1/3  types  to  this this  of  Figure  =  critical  Zo  =  optimum strain  energy  W  =  charge  weight  optimum  they  shows  the  relations  are  harder  (brittle).  relationship  values  developed  of  requires a  the  any  crater  expressed  by  the  E,  energy  the  taking  into  factor  account  per  between  (Figure  results,  This  material  energy  the  Moving to  existance  and  shear  factor the  the  two  the  ton the  4.3-6c). major  figure very  of  and  That  low  rocks  used get  get is  the  strain  that  at  both  blastability Finally,  factor  and  relationship  properties  two  be  they  the  characteristics  structural  can  however,  shows  rock.  powder  (E)  right  of  (plastic).  left,  result,  shows  AoE.  the  to  interesting  4.3-6b).  more  energy  going  constant)  b l a s t a b i l i t y as  brittle  strain  mass  Zo/Zc  b l a s t a b i l i t y index  relationship  strain  blasting  most  =  confirmed  failure.  The  (Figure  the  blasting:  conversely  between  factor  thus  and  also  (rock  ratio  defined  the  of  factor  depth  they  how  type  (plastic)  the  =  research,  softer  and  produce  depth  =  basis,  4.3-6a  extreme  not  depth  E  f a i l u r e during  predict  energy  does  These  Zc  Ao  During  Zc.  and  equations:  with  On  choked  that  and  the  they  the is influence failure  153  1.0  • >\,\* f  0.8 Ao 0  6  0.4 0.2  _SHEAR FAILURE  °C)  FIGURE  i 1  i 2  4.3-6a••  BRITTLE FAILLURE DRILLING COST ——»i l l 4 5 6  i 3  OPTIMUM ENERGY  DEPTH FACTOR,  RATIO, A © E  VS  STRAIN  (after Bauer et al ) 47  A E2 0  FIGURE-4.3-6b-  BLASTABILITY ENERGY  FACTOR,  FACTOR , E  0.9 5 o £j  0.8  £  0.6  0  E , V S  STRAIN  (after Bauer et al ) 47  HARD -BRITTLE ROCKS «  SOFT ROCKS  0.7  oT Q 5 P  £ o-  4  2 LU  a £  03 0.2 0,1  o  FIGURE  3.0  3,5  4.3-6C ' P O W D E R FACTOR,  FACTOR E  4.0  VS  STRAIN  4.5  ENERGY  (after Bauer et al ) 47  1 54  behaviour.  However,  factor  long  is a  Although now  in this  the  rock  and c o s t l y  the rock  mass,  their  such  structural  mapping  every  blasting  information  back  rock  hole  a r e minimum i n rock  mass  In  brittle  hard  In  cases,  both  stresses. compressive  of  from  that  tensile  stress  the s t r u c t u r a l  complex.  of  additional measurement,  from  Performance  the  high  degree  is a  so t h e r e  of  and  in  Micro-scale discontinuities  draw  blasting.  non-uniform  force,  the  is finely  in a brittle strength.  drilling  i s no  between the  concentrated,  the rock  The  inhomogeneity.  similitude  the t e n s i l e  p r o p e r t i e s on  h i s design.  of the a p p l i e d  fails  blasted,  of a l lthe  percussive)  under  being  to optimize  i s overcome and the rock  before  a r e numerous,  there  fails  reaches  the degree  velocity  advantage  stage  to the v i c i n i t y  zone,  Mass  drilled  (roller-bit,  strength  of  a l lrequire  seismic  take  present  rock,  the rock  Close  t o be  the data  that  the b l a s t a b i l i t y  Drills  at this  and  to  as  proposed  tests.  should  available  in drilling  the  testing,  has  engineer  failure  Away  In a d d i t i o n ,  Rotary  up  i s as v a r i a b l e  or c r a t e r  Production  Since  costs  accuracy  methods,  evaluate  C h a r a c t e r i z a t i o n of t h e Rock of  the  as  energy  process.  numerically  of the rock.  operations  of the s t r a i n  characterization  paragraph,  homogeneity  4.3.5  the determination  manner The  and b l a s t i n g  influence  rock  crushed. where  influence i s more  drilling  155  performance  by  acting  discontinuities mechanism  i s improved. on  investigation.  the On  this  using  mass  design provide  rock  strength.  and  three  open  First,  sufficient  the  accuracy enough  to  the  to  of  the  the  rock  by  T.E.  drill  fragmentation. Quality  quality,  of  that of  in  1975.  rock  mass  8  the  with  toward  the  the  RQI  would  the  rock  slope,  geology  and  determine  The  that  input  found  would  study  obtain  a  critical  was  performed  Columbia.  valuable  s t r e n g t h but  Index  Little"  performance,  for predicting  also  of  drilling  structural  measures.  data  level  geotechnical engineering  in British  the  effect  detailed  directed was  failure  macro-  certain  Rock  idea  the  rock  permit  Little  a  the  overall  improve  was  report concluded enough  more  improve  lithology,  case,  of  characterization  The  remedial  p i t mines  behaviour.  related  of  cases,  future behaviour  with  monitoring  reliable the  the  macro-scale  the  the  performed  the  such  implement  a  from  to  performance  on  measure  However, not  In  that,  correlate  p i t slope.  data  by  quantitative areas  drills  correlated  department,  mass  was  useful  being  was  behavior  stable  when  in  to  research project,  of  and  need  said  as  influence  discontinuities are  such both  performance  is believed  attempt  blasthole  In  the  blastability  Micro-flaws  first  rock  However,  macro-scale  performance. The  It  planes  blasting.  drilling  m i c r o - f i s s u r e s on  intensity,  weakness  influence  discontinuities of  as  the was  Rock slope  Quality  d e f i n e d as  to  the  RQI  actual  Index  behaviour.  interpretation  that  not  the  was  not of  the  rock  primarily  structure.  1 56  Higher while  values lower  o f RQI  values  Unfortunately, even  though  there  was  Finally,  with  when  predicted  RQI  were  although,  complexity.  He  believed  that  predicting  zones. a high  RQI  The r e p o r t  stated  that  RQI  and  values in  drill  when  b y t h e same  drilled  that  steel  tooth  insert  bits,  report  only  remain  performance  but a t higher that  basic  the best  Quality  major  requirements  cost  trends design  and  geotechnical  in drilling,  as  IV.  recorder  would  bits  of the c o n c l u s i o n s  alternative.  Index  equipped  different  i t s a p p l i c a t i o n to slope  data,  adjacent  models  i n Appendix  because  geology.  a t one s i t e ,  carbide  are given  that,  t h e Rock  energy  found  A detailed  concluded  therefore  RQI  rocks  showed  obtained  different  The use o f a d r i l l input  between  tungsten  project  fault  intense.  i t was  than  suggested  quality  methods  with  Moreover,  by t h e RQI,  limited. better  values  by t h e t h e o r y .  Little  was  competent  a t one s i t e ,  relationship  drilled  research  detected  rocks,  y i e l d e d t h e same  higher  this  dyke  RQI  i n hard  c o r r e l a t e d with  b i t sizes,  holes  model.  produce  enountered  the f r a c t u r i n g  different  drill  of  hard  different  diameter  were  no d i r e c t  blastholes  were  are was  would  produce  increased data  gathering  However,  be a u s e f u l blasting  Little  tool in  and  grinding. No  other  Leighton" Based  research  revived  on L i t t l e ' s  derived:  this  was  done  concept  conclusions,  on t h e Rock  Quality  i n the current three  major  Index  research  until  project.  modifications  were  157  1)  Improve  quality  and  accuracy  of  drill  performance  records. 2)  Rather  than  it  simply  was  the  domain  using  the  used  RQI  to  to  determine  classify  boundaries  already  the  domain  rock  boundaries,  quality  established  by  within  conventional  methods. 3)  Keep  domain  wear,  shift  Leighton  then  Quality  Index  (Figure  4.3-7).  blasthole  hydraulic index  of  within  of  a  down the  the His  study  reflects that,  mass  domain  was  driller  the  investigation  a  the  to  minimize  bias,  effect  powder that  rock  when  factor the  and  Afton  Mine  performance  results  rate  that  representative  research  at  Rock  of  have  in  the  the  the produce  average  RQI  an value  the d i s t r i b u t i o n .  prompted  project.  i s produced  the  would  of  and  c a r e f u l l y monitored,  condition  bit  the  mass p r o p e r t i e s  penetration  of  etc.  r e l a t i o n s h i p between  showed  and  encouraging of  enough  controlled  pressure  continuity  present  changes,  rock  very  large  developed  geology;  each  The  and  drills  structural  areas  The  the  report  following  development of  the  chapters.  158  c  E 12 -  (A a  500 _  S.I.: in (powder factor)= Imperial In (powder factor) =  RQ  ' ~ 7  2 4  '  9  RQI-885 315  10-  400  8300  200  100  0-L  0.025  0.050  Q075  POWDER  OJOO  FACTOR  0.125 kg.ANFO Tonne  FIGURE4.3-7' PROPOSED CORRELATION BETWEEN ROCK QUALITY INDEX AND POWDER FACTOR AT AFTON MINE.(after Leighton ) 4  159  4.4  SUMMARY  The  author  would  blasting  procedure  any  p i t mining  open  like  t o emphasize  directly  influences  operation:  productivity  and the equipment  cost  small  i s very  costs.  Therefore,  justified The  optimum  function the  increase  savings  energy  o f a wide  design  always  a  powder  appreciate  factor  explosive  distribution  is  the blast  also  important  explosive a  relative  weight  Good permit The  energy  strength  This  of b l a s t  and/or  Mine  is a why  operators  apply in  i tto  uniform  t h e domains  boundaries.  strength  t h e powder  procedures  and a p p r e c i a t e  of the blast  It  of the  f a c t o r c o n s i s t a n t l y on  (ie., relative  are very  t o ANFO,  the design  to obtain  results  c a n be  a  important.  view  of b l a s t  pattern  s e t of black justified.  (bench  They  modifications.  contains:  - plan  domain  i s the reason  results  t h e domain  i n the industry  use of a p o l a r o i d camera  1)  i n a given  i s successful.  over  c a n be  result.  the weight  and express  one t o r e v i e w  also  will  the pattern  extends  basis  operation  = 100).  records  photographs file  within  blasting  i n the b l a s t i n g cost  factor aproach  to consider  utilized  The d i r e c t total  of  the  p r a c t i c e s b u t few o f them  powder  pattern  the a c t u a l  t o be u s e d  approach  aspects  stability,  of parameters.  standard  The d e s i g n  when  factor  range  blasting.  that  that the  other  maintenance.  with  by o v e r a l l  three  the slope  compared slight  the fact  plan)  and  white  The b l a s t i n g  160  -  type  -  explosive  -  of  explosives load  --  front  --  production  —  buffer  and d e s i g n  powder  factor  row rows  row(s)  n e t powder  factor  (total  blast  volume  including  free  digging)  2)  -  delay  pattern  -  drilling  -  choked  -  location  -  short  or  free  faced  description type,  —  majors  fracture  intensity,  discontinuities  groundwater  - blast  of the g e o l o g i c a l  features  alteration  in relation  with  the  direction  blasting  holes,  3)  sequence  or domain  rock  --  initiation  records  —  of  and  (number  o f wet  holes,  pumped  holes,  slurry  etc.)  evaluation  form  Excessive  Throw Lift(heave) Fragmentation  and  photographs  Good  Fair  Poor  N i l  161  Present  Occasional  N i l  Cratering Toe(s) Oversizes Shotguns  Very  Good  Fair  Tough  Digging  Misfire  Number  Smoke  Color  4) - P i t w a l l  5) -  next,  defined  1 to 5  (see Table  3)  Remarks  Since the  conditions  Explanation  good from  blasting  results  one e v a l u a t o r  relative  to a certain  features  of a  satisfactory  criteria  must  be met:  seems  to vary  to the other, standard.  production  from  rating  Figure  blast.  one  site  h a s t o be  4.4-1  shows  The f o l l o w i n g  162  TABLE 3 LEVELS OF BLASTING DAMAGES COMMONLY OBSERVED ON PIT 30 WALLS  ( a f t e r Ashby  )  Observed Conditions of the Wall  Arbitrary Damage Level  Slight  Moderate  3  Heavy  4 Severe  5 Extreme  J o i n t s & Blocks  Dip Angle Appearance and Condition of Face  Digging Condition at Face ( E l e c t r i c Shovel)  Joints closed, infilling still welded.  >75° c i r c u l a r sections of w a l l c o n t r o l holes seen.  Scars of shovel teeth seen i n s o f t e r formation, f u r t h e r digging not p r a c t i c a l .  Weak j o i n t i n filling ia broken, o c c a s i o n a l blocks and joints slightly displaced. '  >65° Face i s smooth, some hole sections seen. Minor cracks.  Some f r e e digging p o s s i b l e , but teeth " c h a t t e r . "  Some j o i n t s d i s l o c a t e d and displaced.  >65° Minor s p a l l s from face. Radial cracking seen.  Free digging possible for <1.5m « 5 f t ) with some e f f o r t .  Face s h a t t e r e d , >55' j o i n t s d i s l o c a t e d . Face i r r e g u l a r , Some blocks some s p a l l s , some backbreak cracks. Blocks d i s l o c a t e d and d i s o r i e n t e d . Blast-induced f i n e s or crushing observed.  Free digging possible f o r <3m « 1 0 f t ) .  55°>37° Extensive free Face h i g h l y digging possible i r r e g u l a r , heavy f o r >3m (>10 f t ) . s p a l l i n g from face. Large backbreak cracks.  FIGURE 4.4-1 •• FEATURES OF A SATISFACTORY BLAST, (after Hoek and Bray ) 2  1 64  1) U n i f o r m , flyrock 2) A  rise  surface slight  drop  5) No  broken  6) No  digging  7) U n i f o r m  Appendix  V  along  of the t o e burden  t h e muck  cratering  controlled  8) A c l e a n  movement  without  rubble.  slight  3) No 4) A  moderate  along  or f l a t the last  pile  crest.  areas. row  of holes  (buffer  blast) ground  beyond  the f i n a l  digline.  problems.  fragmentation.  wall  lists  a  with  minimum  simple  blast  ravelling  potential.  modification  procedure.  holes  165  4.5 1.  REFERENCES MERCER,  J . K . ; HAGAN, Blasting  T.N.; P r o g r e s s  - a Key t o I n c r e a s e d  Profitability, Metallurgical 2.  HOEK,  E . ; BRAY, J.W.; Edition,  3.  BAUER, A . ; D r i l l i n g  LEIGHTON,  LANGEFORS,  M.Sc.  blasting  Notes,  Colorado STARFIELD,  A.M.;  C.  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Strength  techniques,  explosive  of  1981  explosive  Selection  Society  of Minnesota,  Communication,  1983  o f Open  on Rock  ASCE,  1977  170  41.  42.  LANG,  L.C.;  Buffer  Second  Open-pit  Annual  Meeting  MUNOZ-CASAYUS, des ,  J.M.;  3eme  44.  HEINEN,  DIMOCK,  to  Determine  of  the  the  The  la  Determination  l e s Mines  a  l e s Techniques  Ciel  1980  Use  of  Blastability  Seismic  of  Rock,  Proceedings  1976  C.;  Predictable Mining  Int. A.,  and  a l ; How  Engineering  Rotary  Mech., I.O.C.  and  E v a l u a t i o n of Drill  Geological  On  a  In-Situ  Seismic  April  1974  Blasting  Costs  Engineering  the  Resistance  Proceedings, Belgrade, Puts  Mining  blasting  -  An  and  1981  R.S.;  in Tunneling,  and  Model,  January  OLSEN,  Rock.  with  E n g i n e e r i n g , SME,  Prediction  Journal,  Soc.  T.E.;  Blasting  Estimating D r i l l i n g  J.B.;  et  e x p l o s i v e and  Measurements  Louisville,  of  Ouvert  de  Explosives Engineers,  CHRISTENSEN,  LITTLE,  R.R.;  de  1978  Society  Blasting  48.  dans  sur  Third  technique,  BORQUEZ, G.U.;  BAUER,  d^Etude  Mines,  S i x , October  Technique  Sautage  and  on  Mining  47.  District  Pit  conference  BROADBENT,  2nd  Analysis  46.  de  i n Open  Conference  Laval University,  Surveys, 45.  CIM  Approche  Session  R.H.;  Techniques  Operators of  Parametres  Sautage, 43.  Blasting  Congress  1970  Crater Research  Journal, Rock  Performance,  2nd  September  Quality  B.A.Sc.  E n g i n e e r i n g , U.B.C.,  to  Work,  1965 Based  on  T h e s i s , Dept.  of  1976  Index  to  171  CHAPTER  5  1 72  5.0  FIELD  RESEARCH  During Quality sites  t h e summer  Index  majors  sections. with  quality.  The next  three  was  work,  section  performance  mine  sites.  the sites,  blasthole, records  within  (driller  t h e Rock  Quality  the b l a s t i n g logs)  and/or  Index  t o t h e work  was  a s r e p r e s e n t a t i v e o f t h e RQI  taken  domains. enough, The mass  2  matter  wall  although author  were this  only  controlled of f a c t ,  control  perimeter,  the  cases,  the  last  was  t o keep  many  with  starts  operators they  blasts  two  cover  f o r every  the b i t performance charts.  or average  distribution  value  of the  domains  large  possible.  blasting. with  shoot  down-the-hole  data  of the  was c o m p i l e d  from  a  in the area,  According  that  four  delays. wall  of t h e rock  production  consider  t h e damage t o t h e f i n a l  production  The l a s t  the determination  to perimeter  when  improved  the blasting  not always  blasting  blasting  the  made  on  the results  t h e mean  1  d i d not r e s t r i c t  blastability  Ashby , a  Efforts  of L e i g h t o n ,  into s i x  investigation  the recorded  According  which  research.  domains, from  mine  chapter,  the  recorder  t h e Rock  i n three  i s divided  sections present  at the three  between  This  reviews  d i s c u s s i o n , i n f e r e n c e s and f u r t h e r At  tested  5.0-1).  of the f i e l d  the d r i l l  project  factor  (Figure  The f i r s t  performed  the  1983, t h e c o r r e l a t i o n  Columbia  the findings  research  of  a n d t h e powder  of B r i t i s h  reports  PROJECT  to  blasting.  they  As  are doing  row p a t t e r n ,  along  In the m a j o r i t y of  were  already  including  c r e a t e d by  t h e ones  on  173  FIGURE 5.0-h LOCATIONS OF THE MINES WHERE THE RQI STUDIES WERE CARRIED OUT.  174  the  p r e v i o u s benches.  approach Moreover,  should  i t was  also  be  applied  the extent  of  the c o r r e l a t i o n  range  of rock  size.  Blast  overloaded.  0  Consequently,  mass  with  to production was  various combinations  performances  were  felt  rated  that  the  RQI  blasting.  tested  over  of d r i l l  as underloaded,  a  wide  model/bit optimum  and  1 75  5.1  DRILL  PERFORMANCE  RECORDERS  IN THE MINING INDUSTRY  Drill  performance  recorders  a r e being  industry  f o r many  installation  by  as a d r i l l i n g  operator  and  thus  The  principal  bit  depth,  torque as  with  pulldown  thrust  and p e n e t r a t i o n  rate.  acceleration  The p r i n c i p a l  well  provides  of the d r i l l  speed,  other pipe  of d r i l l  the  programs.  c a n be m o n i t o r e d rotary  accepted  procedure  optimization  In a d d i t i o n ,  advantages  operations.  of the d r i l l i n g  that  or weight,  i n mining  recorder  drilling  parameters  drill  are generally  record  comprehensive  The  blasthole  performance  a permanent  drilling  the v e r t i c a l  there  i n the mining  reliable.  investment  tool,  A drill  permits  monitored.  to monitor  i s a cost-saving  the personnel.  mine  and a r e h i g h l y  of a recorder  performance Introduced  years  used  are the  developed  parameters  can a l s o  such  be  performance  recorders a r e : 1 ) to assist 2)  the d r i l l e r  t o be u s e d new  to control  a s an i n s t r u c t i o n a l  the  tool  operation  f o r the t r a i n i n g  operators  3)  to permit  4)  to provide  5)  to avoid  6)  to characterize logging,  assesment early  of the d r i l l i n g  warning  crews  of mechanical  failure  over-drilling  blast  the rock  mass  optimization  being  drill  or grinding  for geological  rate  evaluation  purposes  The  of  first  four  advantages  are well  covered  i n the  176  literature easy  to  and  3  is  a  drill  of  the  mass  Hagan"  adjacent  monitoring blasthole  of  each  reflect  the  explosives  and  considered  that  exhibit  equal  spacings  between  that ease  with  obtain  data  at on  the the  top  of  rock  of  a  of  but  Although  blocks  be  of  will  he not  which  dissimilar  characterize  mean  stem .  the  drill  pipe,  the  d'Aquitaine  the  drill  creation, the By  5  drilled.  he  rate can  blasthole, rates  the  5.1-1)  Petroles on  the  along  b l a s t i n g rocks  the  being  torque  in  of  penetration  the  (Figure  based  proposed  distribution  a v a i l a b l e to des  consists  various  l o n g i t u d i n a l v i b r a t i o n s and  v i b r a t i o n s through  vibrations  the  strength  theory  the  penetration  discontinuities also  He  the  within  ease  substance  Nationale  these  of  recorders  engineering.  optimum  of  relative  Societe  b i t , of  which  the  The  tricone  and/or  blast  materials  dynamic  cost  characterization  strata  variations in  are  a  is  application  performance  strength.  rate  the  methods  developed  drill  variable  Other mass.  point  the  The  drilling  overburden  comparison  rock  the  the  optimize  the  fifth  installation rig.  where  stemming  reflect  drill  of  b l a s t i n g and  usually  of  use  fact  a  cost  to  The  p i t operations,  the  relative by  here.  recent.  penetration  to  the  fragmented  recorder  highly  the  depth  acknowledged  has  in  i s more  of  open  recorder  mining  beds  major  the  suggested  coal  reviewed  of  performance  rock  surface  In  be  in excess  performance  of  not  understand.  over-drilling drill  will  (France) by  the  transmission  analysing  i t is possible The  rock  information  the to is  of  177  O.I  0.2  MEAN SPACING  0.3  BETWEEN  0.4  DISCONTINUITIES (m)  FIGURE 5.l-l= EFFECT OF MEAN DISCONTINUITY A) EASE OF BLASTING B) PENETRATION RATE (after Hagan ) 4  0.5  SPACING ON  1 78  related  to the hardness  c h a r a c t e r i s t i c s of the rock.  This  logging  method  to pick-up  that  obscured The  was  in the averaging  application  permit  this  rock  mass  by  t h e mine  of  the accuracy  suggested when  using At  a  Erie  i t was  of the applied  a  of time  to  compute  t h e Rock  to  compare  i t with  Many  to  has not y e t been  i s available in  mining  on t h e RQI.  sites,  model  MOR  on  Index;  t h e RQI-LOGS  the e f f e c t  Leighton would  i t was  be  has  1  improved  on a c h a r t ,  to  attach  the  the b i t and the b i t depth The o b t a i n e d then  termed  computed  interesting observations  possible  I I I t o one o f t h e B u c y r u s  recorded,  5.1-2).  Quality  input  collected  recorder.  weight  (Figure  are normally  to investigate  of the data  instrument  variations function  industry  the c h a r a c t e r i z a t i o n of  that  decided  input  pen r e c o r d e r The  consumption  although  performance  two o f t h e t h r e e  drills.  i n the sonic l o g .  t o the blasthole  on p a r a m e t e r s  the q u a l i t y  "Geolograph"  are  6  of the data  a drill  streaks  to t e s t .  management,  that  hard  the instrumentation  project,  i s based  thin,  involved  of e x p l o s i v e  and ready research  process  technique  However,  America In  the  of t h i s  the p r e d i c t i o n  demonstrated. North  able  from  data  were  are derived  used  RQI-RECORDER the d r i l l e r from  as  and  logs.  this  invest igat ion. A.  From  a practical  charts  point  i s lengthly.  recorded principal  and simple variable  of view,  the i n t e r p r e t a t i o n of the  The d r i l l i n g to compile.  time  i s generally  The a p p l i e d  in the d r i l l i n g  process,  well  weight, produces  a  FIGURE 5.1-2 : RECORDED  CHART ( Lornex)  180  graph  that  value  introduces  depth,  is less  from  the  p r e f e r r e d to  bit  performance  highly  a  the  data  In  recorded  i f the  was  also  these  the  drilled  moved  wide  is  drill  a  pipe  stand-by  upward  direction  variation  combined  the  not  the  to  i n the  c o n d i t i o n s , the  is  i t  on  produced  recorder  a  average  drillers  graph  recorded  an  consequently,  the  driller  produced  of  procedure  the  performance  depth  of  and  by  drilling  blasthole,  drill  situations  difficult  the  Moreover,  in  the  effects  made  useless.  Technically,  the  useful  of  have  piece  drilling  of  slightly  compiled toughness the  while,  the a  from of  a  presence  compiled  the  than  drill rock.  recorded  in reality,  of  the  data  the  the  is a  rig.  Many  depth  meter  to  the  the  Rock  shows  that  performance  logs  This  i s due  to  the  larger  down  average  nearest  down In  drillers and  the  the RQI  Index, RQI-LOGS values  overestimate  the  fact  that  pressure  pressure  addition,  five  very  their  Quality  RQI-RECORDER.  i s g e n e r a l l y lower.  i s rounded  drill  Concerning  higher  the  on  recorder  g r a p h i c a l r e p r e s e n t a t i o n of  the  drillers  blasthole time  of  performance  equipment  practice.  comparison are  drill  appreciated  availability  of  depth  given  Estimation  determination  i s very  When  drilled  weight.  interpret. The  the  logs.  within  Caving  applied  B.  use  b r i n g i n g the  position,  the  bias.  irregular.  without  too.  a  to  charts,  was  continuous  easy  minutes  over the by  the most  applied a  given^  drilling the  181  majority LOGS is  of the d r i l l e r s .  a n d RQI-RECORDER  a plot  to  as a  and  relationship  bias,  them  quality Equity  seems  logs  However,  mine  shows  the  domains c o n s i d e r e d  accurately the  for  combine  an  superflous.  automatic  f u n c t i o n of the  Index  compilation the system  pipe  i s moved  rate  intervals sec).  data  the  be  of the should  b r i n g the up.  For  integrates  and weight  during  The  that  data  should  the d r i l l  penetration  60  of v a l u a b l e  system  from  performance  will  instantaneous  ( i e . , A t = l 5 , 30,  However,  that  RQI  time  values  device  monitoring  process  when  although  recorders  Quality  In a d d i t i o n ,  a computerized  at regular  RQI  procedure.  example,  collected  to the other,  performance  on  from  RQI-LOGS/RQI-  the gathering  control  rock  of the r e s u l t s  allocated  recorder  from  stand-by  or  t h e manual  up  The  the overestimation,  were  where  the  of  o f t h e Rock  to a point  that  o f RQI-LOGS  the use of a d r i l l  with  5.1-3  the histogram  domain  Drill  experience,  the determination  becomes  a  RQI-  RQI-  slightly.  the r a t i o  the d r i l l i n g  in relation  simplified data  t o 44.  monitor  author's  recorder  36  from  and  I t seems  on  analysis  i s constant  from  RQI-LOGS  the value  is a  that  one.  reduced  that  RECORDER  ranging  Figure  with  t o be  I t suggests  itself.  four  simple  represented  the d r i l l e r  Silver  between  between  increase  i s better  5.1-4. from  relationship  f u n c t i o n o f RQI-LOGS.  difference  a peak  figure  i s not a  of the d i f f e r e n c e  RECORDER average  The  data  drilling  could  be  stored  182  o o o  o o o c  E I  vi  si O  d -i -  d  to  I  o d  o d  0  (0  UJ  o  z oc Ul  CD  o  6 ro  o  CM  ui u. u.  rm  °  0  m O  o  H  00  o d o  I  O  o d  d  I  ro i  °Q  CD CD  CD  © C D  0  o  CD  O  .  Q  |  I  0 0 D.D  i 0.0  _  J  20.0 _J  <  30.0  j  , 40.0 . I  60.0  RQI  (  |  60.0  80.0  <  • l  L  120.0  90.0  AS  _, 150.0  kg-mln m.  LOGS  FIGURE 5.1-3 ; COMPUTER PLOT OF THE BETWEEN  "1 lbs-min , 100.0 — — ( t l O O O )  RQI-LOGS  A FUNCTION  OF  DIFFERENCE  AND RQJ.-REC RQI-LOGS  (tlOOO)  183  o o o  8 O  c  £ i  28-  oc I  24-  o  DC O  I  20-  O  o DC  (ft  20-| 18-  o  UJ  1I  161412-  16-  z  10-  UJ O  8-  UJ  oc  Ul u. u. Q  8-  64-  UJ O <  Ul  2-  3 0-  20 •2  30  40  50  60  70  80  90  Ibs-mln {XI000) ft.  J  0  30  60  90  FIGURE 5.1-4= HISTOGRAM OF THE AVERAGE DIFFERENCE BETWEEN  RQI-LOG AND RQI-REC AS A  FUNCTION OF RQI-L0G.  1 84  on  diskettes  office  or  tapes  micro-computer.  in a  format  that  i s compatible  with  an  185  5.2  EQUITY  5.2.1  Summary  The of  SILVER  miles)  of the Geology  Equity  t h e town  MINE  Silver  of Houston,  north-northeast  site  i s approximately  into  two z o n e s ,  Mining  rate  scheduled The occurs rocks  t o be m i n e d geology  i n an  intruded  zone  Tail  orebody  antimony-gold tabular  zone  (6060  quartz  described  overlies  the c l a s i c  breccias  dykes  S.ton/day)  pyroclastic age.  unit  and reworked  i s divided zone. 1980  with  I t was  on t h e e a s t  crosscut Figure  rocks are side and a  west-dipping  mineralization andesitic  the cretaceous 5.2-1  shows  debris  rocks  and the  the regional  The p y r o c l a s t i c thickness  of i n t e r c a l a t e d  pyroclastic  010  Copper-silver-  an e l o n g a t e Post  The d e p o s i t  strike  on t h e west side.  .  and v o l c a n i c  Strata  a n d h a s a maximum  consist  7  The s e d i m e n t a r y  as d e s c r i b e d above.  The r o c k s  o f t h e mine  in April  by C y r e t a l  stock  the stocks.  complex.  of the area  f t ) .  west.  m i n e r a l i z a t i o n forms  gabbro-monzonite geology  complex  latitic  Tail  (360  o u t by t h e e n d o f 1983.  monzonite  between  The d e p o s i t  commenced  of sedimentary,  by a q u a r t z  The e l e v a t i o n  f t ) .  southeast  580 a i r Km  and the Southern  tonne/day  a n d d i p 45 d e g r e e s  gabbro-monzonite  (3200  (4265  b e l i e v e d t o be o f c r e t a c e o u s  degrees  and  of Vancouver.  has been  inlier  (22 m i l e s )  B.C., a n d a p p r o x i m a t e l y  the Main  o f 5500  i s l o c a t e d 35Km  1300 m  of the Southern  millfeed  Mine  o f 975 m  subaerial  a l l showing  unit  tuffs,  wide  grain  1 86  I. JURASSIC - L O W E R  CRETACEOUS  North  South  2. U P P E R  CRETACEOUS  South  North Nechako Trough  Skeeno Arch Bowser Basin  Nechaho Trough Deposition of "Goosly Sequence"  Topley Intrusions  _Volconic  Deposition af Marine Claslics (Clastic Division)  FIOK_—_-_  0:'. '•Sedimentary- Volcanic v.-. - . Pyrcjclosllc  i  Zone of Crustal Weakness  .+ O i, 0 9 •* M 0 w  f l l O jlU»  *•* *:*.Clastic -.;:r;*: n  0  100  i_  10 _t  Km  20 i  4. PRESENT East  •«  « * !  Gobbro- £r> Monzonite Complex */j  East  West  Quartz Monzonite Volcanics Stock  0 i_  FIGURE  6 Km  5.2-1 : SCHEMATIC HISTORICAL EQUITY SILVER  GEOLOGY,  MINE (after Pease ) 9  187  size  variation.  tuff  i sbased  and  50mm  size  The d i s t i n c t i o n  o n t h e maximum  (0.02,  particle  0 . 2 0 , 2.0 i n c h )  v a r i a t i o n s over  between  relatively  dust,  a s h and l a p i l l i  diameters  o f 0.5mm,  respectively.  Dramatic  short  h a s been  distance  5.0mm  particle  observed . 9  There  i s an occurence  o f dykes  compositions  on t h i s  property.  groups,  grained  andesite  fine  Southern south  from  andesite generally The region  strike  6 t o 10 m  dykes  narrow  scale  exposed  faults  The s t r i k e  f t ) with  a down  The  o r e zone  thickness  The  pyroclastic division,  characterized intensity the  mineralized  the  dust The  greatly areas.  from  dips  since the There a r e  i n form  i s about than  15 t o 30 m t h e dust  generally  300m  (980  tuffs, i s The f r a c t u r e  increases  Tail  f t ) .  ( 5 0 t o 100 f t ) .  areless  of t h e Southern  a  750 m e t r e s  closer to  fractured  (Table 4 ) .  mineralization  with  30 t o 50 d e g r e e s  o f more  The a s h t u f f s  and they a r e  simple  Tabular  fracture pattern.  but i t  many  arenot mineralized.  o f t h e o r e zone  including  by a r e t i c u l a t e  varies  tuffs  varies  Width  arealso deposit  the  north-  deformations.  on t h e p r o p e r t y .  d i p extension  In  strike  i srelatively  t o intense  length  dykes  Tail  The dykes  thedeposit  two m a j o r s  porphyry.  There  t h e Southern  of thedeposit  into  theorehorizon.  ( 2 0 t o 30 f t ) .  o f 025 d e g r e e s ,  westerly.  porphyry than  different  areclassed  and feldspar  steeper  and e r r a t i c .  structure  They  feldspar  throughout  h a s n o t been  large  (2460  deposit,  and d i p s l i g h t l y  ranges  no  Tail  of several  deposit i s  than  TABLE 4 ROCK PROPERTIES EQUITY SILVER MINE  ROCK TYPE  HARDNESS  APPROXIMATE RANGE OF UNIAXIAL COMPRESSIVE STRENGTH (MPa)  Quartz L a t i t e Dyke  Dust  Ash  Tuff  Tuff  Mineralized Tuff  R4-R5  DENSITY (g/cc)  RQD  (psi)  89-166  13000-24000  2.58  48% 62% o f t h e d a t a between 41-70%  R4  55-111  8000-16000  2.78  29% 55% o f t h e d a t a l e s s t h a n 30%  R3  27-55  4000-8000  2.78  35% 55% o f t h e d a t a between 21-50%  20-62  3000-9000  3.00 increasing w i t h grade  10% 60% o f t h e d a t a l e s s t h a n 30%  R2-R3  189  structurally  controlled.  fillings  their  and  fracturing. minerals is  and  sulfides  The  present  mineralization over  short more  ore  However,  as  local  is erratic,  distances.  subjected  to  deposited with  are  the  In  veins  pods.  and The  leading  to  than  as  most  copper  dissemination  wide  the  mineral  of  massive and  variations in wall  eastern  of  silver  i s narrow  western  space  common  principal  orebody  open  intensity  principal  a d d i t i o n , the  alteration  the  the  t e t r a h e d r i t e i s the  occurs as  increased  arsenopyrite  deposit.  chalcopyrite while  mineral.  was  abundance  Pyrite  i n the  S u l f i d e s were  of  wall.  the  grade the  pit  190  5.2.2  The  At  Blasting  Equity  operate  with  Silver,  10 m e t e r  constraints, the  pit  became  working  faces  frequent. oriented place  closer  was  During  reduced  this  research  Moreover,  pattern will  blasts  In such  designed  many  i n c l u d e many  dilution  (16 f t ) as the  of the b l a s t s  conditions,  were  taking  controlled  i n the highly  configuration, rock  of  more  the b l a s t i n g  different  to  t h e number  became  especially  in this  to  In a d d i t i o n ,  (across the p i t ) , with  well,  due  p i t limit,  project,  direction.  selected  to 5 metres  depth.  and choked  i s not performing  mass.  was  was  However,  to the designed  reduced  i n the s t r i k e  blast  (33 f t ) b e n c h e s . height  Silver  equipment  (5 f t ) s u b d r i l l  east-west  blasting rock  1.5m  at Equity  the mining  the bench  excluding floor  Procedures  a  types  broken  given  (see Figure  5.2-2) . The  blast  the  2 2 9 mm  16  f t ) with  geometry  p a t t e r n s were  (9 i n c h )  practice  return,  was  differs  degree  function  a given from  variations  was  based  rock  in hole  inch)  on  depth  (16 f t by and  4 m  diameter  the c o l l a r  of the h o l e  type  5m  highly  to caving,  of  fracturing  of the rock  affecting  the energy  distribution  mass  f t ) with  5m  Because  as  and  within a  the  in  factor,  the rock  by  blast  the  which,  In a d d i t i o n , caused  (13 f t by  The  t h e powder  variable  to the next.  due  by  height,  diameter,  16  holes.  disadvantageous.  p a t t e r n , was  one  by  blastholes  (7 7/8  t h e r e f o r e very  loading  within  diameter  t h e 200 mm  was  5 m  density  the high  the groundwater, given  rock  type.  were The  191  7200 N  ASH TUFF DUST TUFF 7000 N  6800 N  QUARTZ LATITE DYKE MINERALIZED TUFF  6600 N  0 0  250 ^ 50  100 m  FIGURE 5.2-2= EQUITY SILVER MINE 1260m BENCH GEOLOGY, scale 1=5000  ft  192  groundwater  has  distribution. restricted cannot were  be  the  more  amount  blast  per  lined  delay  bulk  plastic  energy  energy  ANFO was  groundwater.  with  minimize  the  initiation  sequence  on  explosive  detonating  geometric  ratios  fragmentation  of  i n f l u e n c e on  sometimes  When  the  sleeves,  distribution  blastholes  slurry was  explosives  seldom  uniform  patterns.  to  row  direct  of  Consequently,  order  row  hole  the  a  utilization  properly  the  In  The  by  used.  within  also  on  were  of  the  still  non-uniform.  5.2.3  Development  a  p o s s i b l e damage  system  V1  same  improved  of  well  was as  the  to  Therefore,  delay  as  pile.  the  modified  pattern.  the  muck  was  to  a  hole  the  reduced, the  per  amount  the  RQI  of  the  displacement  Nevertheless,  C o r r e l a t i o n Between  pit walls,  and  results  and  were  Powder  Factor  The  different  differentiated 1.  Rock  by  type:  blasting the  domains  following  dust  tuff,  mineralized quartz 2.  Degree  of  east  degree At to  the  Equity, width  of  ash  of  p i t at  tuff,  quartz  latite  dyke, tuff,  tuffs  wall  were  zones,  also  divided  according  to  into  the  alteration.  some d o m a i n s the  were  dyke.  the  west  pit  t u f f , m i n e r a l i z e d dust  porphyry  and  the  characteristics:  ash  alteration:  within  did  the  not  1260  cover m  (4134  very  large areas  ft) elevation.  due  1 93  Consequently, of  data  limited,  the p i t (ash t u f f ) .  domain,  5,  drills  were  diameter 7/8  Figure  operating  on  occasions  that  pattern.  I t was  conditions,  inch)  analysed  diameter with  Since  changes  within  1  within  taking  allocated  from  times  mm  was  by  t h e RQI  side  were  on  the e f f e c t  BE  40-R  200  mm  (7  in a  few  same  rock  size  compiled  data  generally  the  set of  observation  on  given  inches)  drilling  the smaller  This  (9  they  for a given  procedures  blasts data  this  blastholes  from has  t h e 229  mm  t o be  of b i t s i z e  to permit  analysis.  to each  of b l a s t s  initiation  account  were  only  the s t r i k e  were  sequence  compilation  Table  factors  variables,  along  and  into  were  performed  group  and  analysis  powder  229  p i t , two  i t occurred,  side  findings  3  Tail  one  in a  and  RQI.  the p a t t e r n .  optimum  0.60  i n the delay  performed,  that,  compiled,  end  f o r the recorded  Although  drilling  compiled  the b l a s t i n g  result  drilling  patterns,  blastholes.  sufficient  conditions  Blast  on  production  provided  Index  were  Little's  and  the other  blast  observed  t h e RQI  model  choked  was  i n the northern  were  In the Southern One  different both  values  blastholes.  i n the average,  drill  RQI  b l a s t h o l e s whereas diameter  especially  b i t diameter  5.2-3).  operating.  inches)  was,  The  f o r the d i f f e r e n t  (Table  (9  were  direction  However, not  being  tested.  rock  domain  compared with  (Figure  5.2-4).  factors  were  types/domains  6 summarizes the r e s u l t s . then  the  constant,  of t h e powder  the d i f f e r e n t  the  The  t h e Rock  Quality  TABLE 5 SUMMARY OF RQI VALUES AT EQUITY SILVER  DOMAINS  ROCK QUALITY INDEX RQI  (229mm-•9 i n c h )  kg-min/m (*1000)  RQI  lbs-min/ft (*1000)  (200mm- 7 7/8  kg-min/m (*1000)  inch)  RQI-REC^  Lbs-min/ft (*1000)  kg-min/m (*1000)  15  (229rnm-9 i n i lbs-min, (*1000  I  Dust T u f f ,  east  61.0  40.9  35.6  23.9  50.2  33.7  II  Dust T u f f , west  55.8  37.5  34.7  23.3  41.1  27.6  III"  Ash  Tuff,  east  75.3  50.6  IV  Ash  T u f f , west  66.1  44.4  30.8  20.7  V  Q u a r t z L a t i t e Dyke  65.6  44.1  37.5  25.2  51.3  34.5  M i n e r a l i z e d DT, e a s t  54.3  36.3  32.9  22.1  43.9  29.5  31.5  21.2  33.0  22.2  VI  >  VII  M i n e r a l i z e d DT, west  VIII  M i n e r a l i z e d AT, e a s t  77.7  52.2  IX  M i n e r a l i z e d AT, west  72.6  48.8  X  Q u a r t z Porphyry Zone  (1)  Recorder  (2)  One p a t t e r n  (3)  12 d a t a p o i n t s  only only  ( 2 )  195  FIGURE 5.2-3' ROCK QUALITY INDEX VALUES  FOR EACH  DOMAIN RANKED IN ORDER OF DECREASING ORDER, EQUITY  SILVER.  196  TABLE 6 CORRELATION BETWEEN RQI AND POWDER FACTORS AT EQUITY SILVER MINE  DOMAINS  ROCK QUALITY INDEX (229nim-9 i n c h ) kg-min/m (*1000)  lbs-min/ft (*1000)  POWDER FACTOR (choked) kg/tonne  lbs/s.ton  I  61.0  40.9  0.105  0.21  II  55.8  37.5  0.100  0.20  III  75.3  50.6  IV  66.1  44.4  0.110  0.22  V  65.6  44.1  0.110  0.22  VI  54.8  36.8  0.095  0.19  VII  53.6  (36.0)  0.095  0;19  VIII  77.7  52.2  IX  72.6  48.8  X  54.9  (36.9)  0.095  0.19  no optimum powder f a c t o r a l l o c a t e d t o domains I I I , V I I I , IX  197  _ © 0  O o o  1 * c  E i  i  75 r  60  x UJ o c o 0>  _i < E E O o> 30 CVJ o CVJ o or 15  CH-  0.  0.30 - S.ton 0.025  0.050  0.075 ENERGY  0,100 FACTOR  0.125  0.150 kg Tonne  FIGURE 5.2-4' PROPOSED CORRELATION BETWEEN ROCK QUALITY INDEX AND POWDER FACTOR AT EQUITY SILVER MINE.  198  5.2.4  Analysis  No Equity  real  of the  Results  optimization  Silver.  The  o f t h e powder  optimum  powder  determined  from  the evaluation  calculated  from  the b l a s t  blasting  procedure,  comparison  between  Consequently, blasts types  would  of b l a s t  gathering sinking good.  performed  blasts.-  One Equity  was  The  holes  on  on 5 m  length  makes  powder  factor  thus  that  difficult.  the production  research Silver  choked  project.  during  the  Other data  and c u t  in regard  t o the  t o be  reducing  a t bench  guidelines  of  that  the b l a s t i n g ratio.  a  slight  and  the explosive values  6.5  m  i n the  will  allocated  and  elevation,  possesses  higher  the the  easily  efficiency.  to each  of the p i t , correspoding  charge  cause  t o be more  confinement  very  (21.3 f t )  Increasing  (length)  therefore,  slope  at  results are  variation  rapidly.  the charge  reduced  side  With  very  were s p e c i f i e d .  the b l a s t i n g procedure  change very  o f t h e RQI  the eastern  rocks  was  the b l a s t i n g procedure  increasing  examinaton  i n the  were  the r a t i o  ejected,  t o the v a r i a t i o n s  performed  (16 f t ) b e n c h e s ,  by  r e s u l t s and  blasts  as design  at  were  ramp c o n s t r u c t i o n  few p e r i m e t e r  the c o l l a r / c h a r g e  column  altered  for this  performed  the r e s u l t s and the  only  at Equity  i s the fact  stemming  The  that  perimeter,  improved  Silver,  of  factors  of the p e c u l i a r i t i e s  dependent  shows  were  In g e n e r a l ,  stability  decided  considered  period  Due  was  listed  of the b l a s t  the evaluation  i t was be  factors  reports.  t h e powder  factor  domain  to the  RQI  than  less the  199  western  domains.  This  degree  of a l t e r a t i o n .  levels  were  Due no  higher  suggests  that  However,  i t was  close  t o the absence  r e l a t i o n s h i p between  obtained values group ones  to the east of  part  a l l o c a t e d to those  obtained  and  should  n o t be  i n the southern  i n t e r p r e t a t i o n of the data  mass  blastability  Leighton . 1  and  t h e powder  that  t h e Rock  the data  is a  Quality  observations, were  In a d d i t i o n , from  a  Index  RQI  as the  o f t h e p i t where  gathering  trend  the  smaller  as a c c u r a t e  r e l a t e d to these  there  groundwater  factor  and c e n t r a l p a r t  The  that  result  considered  mined out d u r i n g  I t shows  blast  domains a r e d e r i v e d  b e n c h e s were  5.2-4.  observed  of the p i t .  two  Figure  and  i s s e n s i t i v e to the  wall.  sufficient  t h e RQI  in the northern  of data,  t h e RQI  period.  domains  between  yields  the  as p r e d i c t e d  rock by  200  5.3  LORNEX  5.3.1  MINE  Summary  of the Geology  The  Lornex  copper-molybdenum  Highland  Valley  of B r i t i s h  of  Kamloops.  1060 has  m  (3478  t o be m i n e d  production designed The  deposit a  mill  h a s been  northwest  striking  (6890  i n excess  with v a r i a b l e  of the property,  I n some a r e a ,  defined  of the a l t e r a t i o n  Diorite.  because  The west  Gronodiorite The  Zone  part  s.ton/day).  et a l  o f 750 m  quartz  .  0  The  (SQD)  rock.  a n d 750 m  (2460  dip.  On  porphyry  of t h e dyke  of a d j o i n i n g  (2460 f t )  minerals  toward  The  fault the southeast dyke  trends  a r e not well  Skeena  Quartz  the Bethsaida  5.3-1).  sulphide  zone,  The o r e  ft).  by t h e L o r n e x  westward  contacts  1  30 t o 40 d e g r e e s  of the p i t i s within  (Figure  predominent  o f 1983, t h e  Quartz D i o r i t e  f t ) long  side  a pre-mineral  northwesterly.  Full  (83000  by W a l d n e r  t o plunge  on t h e w e s t  orebody  : 1.0.  t h e Skeena  i s believed  i s truncated  the Lornex  medium t o c o a r s e - g r a i n e d  t o a depth  northerly  2.2  southwest  i s approximately  t h e summer  tonne/day  described  within  porphyric,  The d e p o s i t  orebody  end  75300  i s a p p r o x i m a t e l y 2100 m  wide. the  was  i s around  is.entirely  slightly  zone  rate  site  t o be p r o f i t a b l e .  i n 1972 a n d d u r i n g  ratio  geology  scale  in the  (46 m i l e s )  o f t h e low grade,  on a l a r g e  feed  i s situated  74 Km  o f t h e mine  Because  stated  stripping The  Columbia,  The e l e v a t i o n ft).  deposit  are chalcopyrite,  FIGURE 5.3-1 LORNEX :  OPEN PIT MINE, scale 3/4"=l000'  202  bornite,  molybdenite  fracture  fillings  average  5  ranging  from  exceed  to  200  15 a  with  by  (656  produced  5.3-2.  The  three  central  and  attitudes, mineral  sulphide  argillic  porphyry The  of  one of  grade  degree  dyke  of  there  have  1  chalcopyrite  type  in  In  of  on  length  Lornex  is  in  in  The  hydrothermal  vein  post-  with  most  which  strength  the  pit.  associated  increasing  rock  veins  a l l three  the  montmorillonite an  Figure  a d d i t i o n , two  from  may  Structural  of  deposit.  alteration  width,  Strike  although,  overlap  recognized  this  in  p l o t t e d on  orebody,  alteration  a f f e c t e d by  sulphides  the  molybdenite  inches)  veins  copper-molybdenum  the  been  as  results  and  the  chlorite.  intensity  of  decreases  with  alteration.  The  alteration. the  Lornex  deposit  are  quoted  0  principal in  points  grades.  with  statements  et a l  0.6  meter.  i s an  original  any  is less  following  bornite  of  kaolinite,  and  to  distribution.  data  zones  argillic  alteration  a  attitudes for  increases  primarily  fracture coatings,  inches  and  hydrothermal  sericite,  occur  M i n e r a l i z a t i o n at  in higher  i s the  as  than  11000  zones,  resulting  Waldner The  more  m i n e r a l i z a t i o n occur  increasing  "1.  major  western  general,  from  over  in distinct  types  important presence  (0.2  f t ) .  f r a c t u r e systems  Four  In  to  They  and  fracture density  has  dominant  quartz  hairline  mapping  are  pyrite.  millimeters  meters  controlled  and  center,  zone  form  concentric  pattern  chalcopyrite outside  overlapping  zones.  a  Pyrite  portions forms  a  of  halo  the  with  bornite bornite  around  the  and and ore  an  Cu-Mp VEINS  3a  1 MOST PROMINENT Cu-Mo VEIN TRENDS  FRACTURES  r~"^^  3b  3c  MOST PROMINENT FRACTURE TRENDS  N22°E/55° S.E. N64 E/57°S.E. N90°E/58°S.  N86°W/52° S.W. N08°W/ 64° S.W. N2 1 °W/ 46° S.E. N63°W/57° S:W.  0  POLES TO 3152 FRACTURES CONTOURS AT 2 , 3 , 4 % PER 1% AREA  FIGURE 5.3-2 : LOWER  1— MOST PROMINENT FAULT TRENDS  N32°E /54°S.E. N8S°W/62°S.W. N44 V//66°S.W. N08°W/68°S.W. N68°W/69°S.W.  0  POLES TO 5835 VEINS CONTOURS AT 2, 4. 5, 8, 12% PER 1% AREA  FAULTS  POLES TO 1564 FAULTS CONTOURS AT 2 . 3 , 4 , 5 % PER 1% AREA  HEMISPHERE , EQUAL AREA STEREOGRAPHIC  PROJECTIONS OF STRUCTURES MAPPED IN THE 10 LORNEX OPEN PIT  (after  Waldner et al. )  204  Zone. 2.  Copper  grades  outward 3.  from  Sulphide shallow  Zones  of  a  and At  Lornex,  30  to  i s one  of  the  therefore the  time  method  was  a  to  vast  to  capacity  Production perimeter zone  choked,  of  28  ft)  by  36  the  even  in ft)  at  patterns the in  waste the  north  and  orebody,  argrillic  alteration  grades."  at  Lornex  of  on  material  and  size  project  shovel units  was  the  maintain  choked  only  part  of  operations  of  equipment  the of  on  east  the  every in  the  and to  south obtain  time  eastern  day.  Canada  are  used.  mining  p i t having  stripping  the  the  place,  one  benches  most  i s moved  taking  stage  several  free-faced  wall  the  the  intense  large  southern  in  periphery.  plunge.  truck  to  b l a s t s were blasts  Blast  and  its  northwest  back  accomplished  to  deep of  decrease  degree  pushing  Mining  are  portions  The  were  content  orebody  zones  forward.  they  blending  the  quantity  research  excavated,  ore  40  largest  straight  was  of  higher  numerous  the  sulphide  southern  B l a s t i n g Procedures  At It  core  moderate  correspond  5.3.2  total  alteration  the  indicating 4.  the  and in  and  been  walls. optimum  ratio. while  the  wall.  p i t , a l l the  In  blasts  the were  contact. were  ranging  rock  on  soft  ore  the  zones.  from east  8.5 wall  m to  by 11  Subdrilling,  8.5 m on  m by the  (28 11  ft m  12.2  by  (36 m  ft  205  (40ft) ore to  benches,  zones. fair.  weight  was  The The  also  blast  powder  strength  results factor  Therefore,  pattern  not uniform.  and  variations  noted.  indicating  wet  shot  in-line  they  were  due  o r on  energy  t h e rows.  the practice  in  250  mm  initiation ineffective The m  (20  longer because  of using  was  delays of  themselves. were  two  inches)  factor  between  was  25 ms  delay  i t was  walls  and  period  shown primacord  side was  a  very  The  last  available. was  poor. were  allocated  pattern.  d i d not look  a  permitting However,  the b l a s t s  propagation  6  The  c o n d i t i o n s of the rock  not s u f f i c i e n t  when  themself  of r e i n f o r c e d  blasts  the V  blasts,  but  choked  producing  were  common,  of the p a t t e r n .  underloaded  The  was  they  to the wall,  of  accurate  dimensions  a down-the-hole system  V i b r a t i o n s and crack damaging.  energy  control  t h e rows  the general  not  column and c o n s e q u e n t l y  the rest by  was  project,  b l a s t h o l e was  the  production  the short  downlines  closest  than  performed  that  the research  of the w a l l  displacement  slopes  and/or  poor  the  g e n e r a l l y choked,  factor  use of the e x p l o s i v e  energy  initiation  were  observed  of the e x p l o s i v e  design  within  smoke The  soft  AL-ANFO,  and depth  mix.  i t was  During  ( 9 7/8  (ANFO,  yellow/orange  pattern  f t ) of the p a t t e r n ,  higher  the  a V  free-faced,  that a  Finally,  from  d i d not consider  In a d d i t i o n , d r i l l i n g spacing  i n the  ranging  distribution  ANFO o r n o n - o p t i m u m  t o t h e low  between  used  the energy  nonexistant  generally  calculation  of the burden,  frequently  being  were  of the e x p l o s i v e s  Slurries). was  variable,  were  toward good.  the  mass, choking rock  Design  206  modifications It  should  performed results well  concerning energy be  noted  at Lornex  that  during  o b t a i n e d were  distribution  three Hercudet  this  partly  research  due  were test  suggested. blasts  project.  t o the system,  The  were very  but a l s o  good  to the  engineered design.  5.3.3  Development of the C o r r e l a t i o n  Between  RQI  and  Powder  Factor  It Rock  half  being  blast  south  four  logs three  to derive  t h e powder of u s e f u l  monitored  results  were  and  the recorded charts. generally tooth  bits  variation  were  Rock  blasting  were  Blasts  compilation  steel  factor  side  improving  The  were  a correlation  of  t h e RQI  operating were  used  i n t h e Rock  observed. error.  were  However, The  data.  results  The  On  the  progressed described  Degree of a l t e r a t i o n  toward  underloaded.  v a l u e s was Of  the f i v e  on  any  done  i n the soft Quality  Diorite  from  Bucyrus  given  domains were  of  east  in chapter  Index  45-R  shift.  from  drills,  no  t h e WC  source  insert  of  from  or Quartz  the Skeena Quartz  driller  Although  ore zones,  defined (SQD)  the  (QPP) b)  main  Approximatively  initiated.  i t i s a potential  t y p e s : Skeena Quartz  between the  at Lornex.  as mining  but the s a t i s f a c t o r y  not reached.  interpretation a)  and  the lack  end,  were  dramatic bits  Index  of the b l a s t s  wall,  some  not p o s s i b l e  Quality  reason  the  was  Diorite  Porphyry  207  Some o f limited  in  southern other  the  surface  end  of  drilling  quantity  domains,  of  to  the data  data was  correlation  between  alteration In pit,  a  of  rate  or  two  from  previous  the  f u n c t i o n of  the  Rock  Quality  addition,  i n the  ore  was  to  on  12.2 a  ore  with m  (40  larger  domain  area.  factor,  Diorite  and  the  block  the  average  f t ) deeper. scale.  the  the  the  southern the A  RQI  plan  The  on  the  same  no  analysed,  of  and  the  Although  there  preceeding  RQI  the  is a  degree  ( F i g u r e 5.3-3,  blasthole plan on  were  Because  were  (Figure 5.3-4).  over  In  months  Index  of  wall,  larger.  powder  zones  east  patterns.  e s t a b l i s h e d between  rock  an  compared  projection, performed  the  superimposed  allocated  directly  was  the  the  Quartz  the  were  with  Skeena  of  blast  areas  derived  correlation  on  p i t , the  the  grindability bench  one  is a  correlation  especially  of  and  the  the the  bench  good of  Table  end  no  7).  the  previous grinding was  block's e x e r c i s e was  also  FIGURE 5.3-3 ROCK QUALITY INDEX IN DIFFERENT DOMAINS OF LORNEX :  MINE.  TABLE 7 SUMMARY OF RQI VALUES AND ROCK STRENGTH AT LORNEX MINE  DOMAINS  ROCK QUALITY INDEX (250mm-9 7/8inch) D r i l l e r logs Recorder kg-min/m lbs-min/ft kg-min/m lbs-min/ft (*1000) (*1000) (*1000) (*1000)  ESTIMATED UNIAXIAL COMPRESSIVE STRENGTH (MPa) (psi) ( 1 )  SQD massive t o weakly a l t e r e d  49.3  33.1  40.6  27.3  261  37800  II  SQD a l t e r e d and f r a c t u r e d  33.6  22.6  29.8  20.0  111  16100  III  SQD moderate argillic alteration  29.6  19.9  24.6  16.5  IV  SQD weak t o intense a r g i l l i c a l t .  26.3  17.7  24.1  16.2  179  26000  V  QPP weakly altered  24.9  16.7  VI  SQD Intense argillic alteration  20.4  13.7  VII  SQD moderate t o intense a r g i l l i c a l t .  24.0  16.1  V I I I QPP weakly altered  28.4  19.1  132  19200  IX  26.3-  17.7  50  7200  SQD moderate t o intense a r g i l l i c a l t . (1) from p o i n t - l o a d tests  M O  o o  o 025 o  *  II  • 9 B L A S T HOLES AVERAGE A 25 B L A S T H O L E S A V E R A G E  E i  cn  30F  20  4 15  X —  II ~  00  • o> <  I  15  »  10  Is  0-1-  10  12  14 13 GRINDING  FIGURE  5.3-4= RELATIONSHIP  20 15 RATE  17  19  21 TONNE HR  moo)  B E T W E E N ROCK QUALITY INDEX AND GRINDING RATE AT LORNEX.  21 1  5.3.4  A n a l y s i s of the Results  It the  i s impossible  relationship  domain  ore zones,  The  fact  variations confirmed  The  explosives  i n accordance  when  the rock  with  the general  between  mass  be o f  interest  the v a r i a t i o n s second  i n rock  i n rock  interesting  at this  time,  grindability transfered investigate  rating  directly this  quality  subject  with  to the  mass i s  and the degree the lesser  In t h i s from  down.  i n more  t h e RQI. to  depth.  although of the  research  very grindability both  project,  the previous  bench  The mine g e o l o g i s t  detail.  of  i n order  I t i s not a coincidence,  obtained  one b e n c h  in the  relationship.  engineering,  i s the variation  processes. was  slope  relationship,  t h e Rock Q u a l i t y Index. fragmentation  mass,  s i d e of  mass i n  i s sensitive  t h e RQI  the rock  one  the rock  than  t h e Rock Q u a l i t y Index  The more a l t e r e d  approximative  being  Nevertheless,  by t h e c o r r e l a t i o n  could  monitor  that  a correlation  of the s t r e n g t h p r o p e r t i e s of the rock  alteration.  with  i s missing.  I r e q u i r e s more  southern  This  to derive  the and  will  212  5.4  GREENHILLS  5.4.1  Summary  The  MINE  of the Geology  Westar  Minin'g  miles)  north  region  of southeastern  presently shops  expose sent  2000m  yearly  ( 2 . 2 t o 3.3 M  expanded  t o 4.0 M  identified  major  on t h e p r o p e r t y ,  which  syncline  d i p between  are in has  plunges  t o 60 d e g r e e s also  present.  Figure  5.4-1.  been  exposed features  continuous  to B r i t c h  1  1  ,  During  concentrated  of the Cougar  (Figure  a t 20  structure  O u t o f t h e 29  1, 7,  10 a n d 16  i s a broad  The limbs  on t h e west  limb  and l o c a l  project,  p i t where  5.4-2).  p i t i s the presence  M  i t c a n be  of the s t a t i g r a p h y  the research  was  the property.  Regional  outlook  i n the Cougar  limb  o f them,  to  2.8 a n d 3.0  although  to the north.  20 t o 40 d e g r e e s  A general  between  throughout  limb.  shipment  s.ton/year).  the major  gently  on t h e e a s t  on t h e west  coal  i s  i n order  i s estimated  range  four  facilities,  The p r o p e r t y  the ridge,  life  (4.4 M  (22  Kootenay  loadout  The f i r s t  of clean  tonnes/year  syncline  20  of c o a l .  production  s.ton)  and g e n e r a l l y  According  along  35km  The p i t e l e v a t i o n i s  elevations.  or p i t s ,  tonnage  i n the east  the coal  1982 a n d t h e p r o j e c t  The a c t u a l  tonnes  seams  zones  i s located  Columbia.  f t )although  a r e a t lower  a sufficient  i n August  of Sparwood,  British  (6562  in several  years.  are  o f t h e town  and o f f i c e s  divided  G r e e n h i l l s Mine  One of  data seams  open  of the and  from  faulting i s given  gathering 16 t o 29 a r e  of t h e major crossfaults  213  SANDSTONE SILTSTONE »**«»* MUDSTONE mm COAL 600-H»»*u vl&  ELKMEMBER SANDSTONE SILTSTONE MUDSTONE 60 m +  E  L  K  MEMBER  SEAM 29 SEAM 28 SEAM 27  COAL BEARING MEMBER  SEAM 2 5 - 2 6  500  SEAM 22 Z  g co O UJ o Ul or c_>  < CE O U. > <  SANDSTONE SILTSTONE MUDSTONE COAL  2-7 m  SEAM 2 0 SEAM I 9 SEAM I 8  5-llm 4 0 0  SEAM I6-I6L  550 m  SEAM 13  z  300-  UJ ho o  j£C<S SEAM 11  5-Mm  SEAMIO-IOL ™F3  7-llm 200-  MOOSE MOUNTAIN MEMBER  SEAM 9 SEAM 9-1 SEAM 9-2 SEAM 7  CHERT SANDSTONE l2-25rn  100'  o CO CO < or  "3  z  II si  u.  SANDSTONE SILTSTONE SHALE 245 m +  FIGURE 5.4-1 = GREENHILLS  SEAM 5 SEAM 3  10-16 m  \  SEAM I SEAM M MOOSE MTN MEMBER  MINE STATIGRAPHY (after Britch")  214  6  FIGURE 5.4-2= GREENHILLS  COUGAR  PIT  scale 1=5000  50  lOOm  215  striking areas  easterly  exhibit  and d i p p i n g  o x i d i z e d m a t e r i a l s of very  addition,  the sedimentary  rock  mass  i s more  pit,  the rock  the  different  70° t o t h e s o u t h .  sequence  fractured.  shows a more strength  In the n o r t h e r n  parameters  i  altered part  behaviour.  of the  faulted  low s t r e n g t h .  is slightly  competent  The  rocks.  In and the  of the Cougar  Table  8  shows  TABLE 8 ROCK PROPERTIES GREENHILLS MINE  ROCK TYPE  HARDNESS  APPROXIMATE RANGE OF UNIAXIAL COMPRESSIVE STRENGTH  (MPa)  Sandstone  R4  DENSITY (q/cc)  SHEAR STRENGTH OF DISCONTINUITY  (psi)  115-155  17000-23000  2.70  28  Siltstone  R3-R4  40-152  6000-22000  2.70  33.5  Mudstone  R2-R3  60-99  9000-14000  2.70  31  217  5.4.2  The B l a s t i n g  At  Greenhills  and  evenly  and  high  and  the geology  free  mine,  fragmented  additional  row(s)  f o r optimum  Because  of holes  a l l blasts  perimeter  blast  the  a n d t h e r e f o r e f a r away  Benches 270  mm  15.5 ft)  are designed  ( 1 0 5/8  metres  inches)  areas  14 m e t r e s  i n diameter  and b l a s t h o l e s  may  i n c r e a s e d by t h e p r e s e n c e within  deeper  than  burden  volume  with  free  slightly The NONEL the  allocated  than  are drilled  a r e kept  7.0  b y 8.1  (51 f t ) .  powder  eliminates side to avoid  Blastholes  ANFO.  of  (23 f t by 26.5 occurs  the real  Even  cases,  a t bench though  powder  holes  factor  no  at the t o p of  of  the  factor  added,  when  blastholes  there  explosive load.  powder  i s straight  t o 50 ms  m  by t h e p r e s e n c e  to the extra  to  wall.  redrilled.  In both  a  time,  t o a depth  Caving  of f i l l e r  the net design  e x p l o s i v e used which  the f i n a l  i s used,  the p a t t e r n and/or  digging, the overall  system  rows  approach  15.5 m e t r e s  less  At the present  (46 f t ) h i g h .  a r e then  powder  needed,  factor  at the toe location  by t h e s u r v e y o r s .  design be  from  toward  i s reduced,  the operation being  (51 f t ) o n a s t a g g e r e d  pattern laid-out  crest  shot,  fine  of the operation  of t h e beds  are required  a  loading conditions  are directed  and d i s p l a c e m e n t .  has been  t o produce  of the nature  as the d i p angle  fragmentation  ridge  Greenhills  are designed  pile  of t h e mine,  However,  at  blasts  muck  productivity.  face.  improve  Procedures  i s no However,  i s generally  factor. Initiation  initiation.  Delays  the p r o b a b i l i t y  of  i s by t h e between  218  disruption parting design based the as  powder on  the  the  factor  performance  0.59  i n the  kg/m  3  the  allocated  Blast  Development  different  the beds  of  (0.44  lbs/s:ton)  0.55  blast  p i t , was results  of  the  the  drill the  kg/m  to  0.47  reduced still  very  Correlation  zones,  powder  lbs/s.ton) the  the  3  down  1983 the  faulted  kg/m  such  seams  p i t , the  program,  as  foreman  benches,  upper  during  such  The  blast  hard  20  (0.41  optimization  areas,  are  the  and  used  beds.  and  Cougar 3  defined  previous  In  16  of  to  well  sedimentary  the  fixed  soft  the  cuttings.  northern part  the  Cougar  lbs/s.ton).  and  same  to  along  h i s e x p e r i e n c e on  sanstone  During  southern  the  column  i s e v a l u a t e d by  geology,  is presently  summer.  5.4.3  factor  walls,  the  factor  explosive  between  competent  hanging  the  the  planes  drill  from  of  powder zones  in  (0.35  good.  Between  RQI  and  Powder  Factor  At  Greenhills,  starts  from  Cougar  P i t are  18  16.  and  called 16  seam  access  east  The  to  degree  the from of  29,  waste  hanging  28,  to  that  i s the  the  fracturing  The  lies of  as  The 22,  has  20  domains function  sedimentary  be are of  20  seams seam  that  seams  upper,  the  to  sequence  minable  following  that  a  in a  between  the  blasting  the  benches  25-26,  waste  next, of  on  westward.  27,  number  seam).  one  29)  rock  the  wall  16  i s mined  (seam  seams  according to  different and  the  coal  lower,  are  ( i e . , the  moved  to  gain  therefore the  sequence.  in  rock The  very  types  219  nature  of t h e domains  next.  However,  the  p i tslightly  the  striking  fracturing  from  RQI  permitted  (Table Since  easy  9, F i g u r e  of  results  d i s p l a c e d muck  considered  powder project  factor took  consumption  gathered. has been place. 3  generally drilling and  The a l l o c a t i o n  data blasting  of the  i n the following  i s the only  t o produce that  equipment.  RQI  this  Table  evaluation  evenly the no  blast  10 a n d F i g u r e  and energy  factor  t o note  at Greenhills since  i s also  kept  of Lornex  optimizes  G r e e n h i l l s expresses unit  a  Therefore,  It i s interesting reduced  variable,  As t h e o p p o s i t e  pile  between  Since  i n kg/m ,  were  at Greenhills are  underloaded.  the relationship  the data  a  the d r i l l i n g  i s summarized  are designed  results  from  analysed;  seams i n  the northern  was n o t o p e r a t i n g ,  simple.  of the l o a d i n g  describe  of the domains  factor  productivity were  between  p a r t of  of  Therefore,  necessary,  procedures  was made  Greenhills blasts well  to the  5.4-3).  the blasting  fragmented,  were  domains  a n d t h e powder  Mine,  the intensity  interpretation.  constant blast  when  Areas  bench  to the different  pages  one b e n c h  i n the southern  of the rocks.  as the r e c o r d e r  the previous  records  from  of f a u l t s  and increases  i s done,  domains.  Also,  constant  d i s t u r b s the c o n t i n u i t y of the coal  and a l t e r a t i o n  southern  large.  the presence  direction,  differentiation and  remains  included  5.4-4  derived  that the the research  the explosive i n the table.  220  TABLE 9 SUMMARY OF RQI VALUES AT GREENHILLS MINE  DOMAINS  ROCK QUALITY INDEX (270mm-10 5/8 inch) kg-min/m (* 100.0)  lbs-min/ft . C*1000) r  I  Seam 28 HW  32.3  21.7  II  Seam 21 HW  33.6  22.6  III  Seam 25-26 HW  37.4  25.1  IV  Seam 22 HW  29.2  19.6  V  Seam 20up HW north  62.9  42.3  VI  Seam 20up HW south  39.7  26.7  VII  Seam 201w HW north  39.1  26.3  25.9  17.4  V I I I Se;  HW south  IX  Seair.  . HW north  48.7  32.7  X  Seam 16 HW south  42.1  28.3  221  O O  o  o o o  c  i I  75-1  50-i  60- 40-  o E •' n to  30-  to < O  I  E E  30- 20-  * O o rO CM  or — 15- 10-  o o o 5  0  X  0-  O O  Q  o Q  < z o o o o o o o o o Q  DOMAINS  FIGURE 5.4-3' ROCK QUALITY INDEX VALUES RANKED IN ORDER GREENHILLS,  OF  FOR EACH DOMAIN  DECREASING QUALITY,  222  TABLE 10 CORRELATION BETWEEN RQI AND POWDER FACTORS AT GREENHILLS MINE  DOMAINS  ROCK QUALITY INDEX (270mm-10 5/8inch)  POWDER FACTOR  kg-min/m (*1000)  lbs-min/ft (*1000)  kg/tonne  kg/m~  lbs/s.ton  I  32.3  21.7  0.155  0.42  0. 31  II  33.6  22.6  0.155  0.42  0.31  III  37.4  25.1  0.160  0.43  0.32  IV  29.2  19.6  0.150  0.41  0.30  V  62.9  42.3  0.195  0.53  0. 39  VI  39.7  26.7  0.160  0.43  0.32  VII  39.1  26. 3  0.160  0.43  0.32  VIII  25.9  17.4  0.150  0.41  0.30  IX  48.7  32.7  0.175  0.47  0.35  X  42.1  28.3  0.165  0.45  0.33  223  o o o  o o o  E I  75-  60- 4 0 -  x 1.1  -~r 4 5 -  _J  o  '31  30  30 - 20  15-  10-  0-L  0  050 lbs  0.150  FIGURE 5.4-4-PROPOSED  0.175 0.200 ENERGY FACTOR  CORRELATION  0.225  S.ton 0.250  BETWEEN ROCK QUALITY  HMDEX AND POWDER FACTOR AT GREENHILLS MINE.  224  5.4.4  Analysis  The to  the  drilling  three  domains for  and  Results  the  factors: data  of  were  other  sites,  factor  Therefore,  values  that  it  is  correlation  domains  boundary  enough  procedure the  yields  known  was  powder  allocated  still  not  good  numerous  blasting  The  a  the  the  optimized. powder  the  determination  due  as  of  good  i f the  within kept  each  well  each  is  defined,  of  the  constant.  However,  were  not  really  domain  are  the  blasting  powder  Greenhills  were  factors  to  at  minimum  results.  factors  can  be  further  reduced. The as The  the  two  domains,  toughest  domains  to  are  with  easier  blast,  The Quality of  sandstone. possess  relationship Index  and  development.  suggested however  blast  described  siltstone to  in  are  described  the  very  to  showed as  faulted  lower  fine-tune  encouraging.  and Rock  sandstone end  of  blast  foreman  Quality and  these  Index.  competent two  domains,  RQI. at  this  factor  testing  drill  highest  competent  The  powder  the  the  developed  Further  order  by  and the  is  site still  data  between at  an  early  evaluation  correlation.  the  The  Rock stage  are results  225  5.5  DISCUSSION  5.5.1  Accuracy  In the  AND  data  establishment Afton  of the Input  previous  input  Mine,  INFERENCES  s t u d i e s on Rock  was c o n s i d e r e d of a v a l i d  methods  Index  within  these  areas  were  RQI  with  data  i s needed  available.  practice  departure  variations ranging  between that  t o make  the average These  are not only  of the rock  t o the nearest t o t h e upper a s t h e maximum  of the hole  five  mass,  minutes,  reading  was d r i l l e d  of v a r i a t i o n project,  between  the  This  high  amount o f value  are not always  caused  by t h e by t h e  crew  time i s  generously  T h e down p r e s s u r e ( i e . , 4.1 MPa  drilling  in reporting  the d r i l l i n g  sometimes  a t 3.4 MPa  i n the  50 t o 200 %  o r peak  but also  Generally,  limit.  However,  a considerable  of the d i s t r i b u t i o n .  The domain  25 t o 140 % .  and the d e d i c a t i o n of the d r i l l i n g  rounded-up specified  ranging  Quality  results.  research  At  by  numerous.  degree  In t h i s  suggests  i n order  nature  index.  boundaries  good  data  by t h e h i g h  o p e r a t i o n a l parameters.  reported  o f domain  of  inthe  charaterization  has y i e l d e d  The v a r i a t i o n s  inhomogeneous  most  maximum  of v a r i a b i l i t y  representative  the  domain  blastholes.  observed  a common  degree  mass  l a r g e and t h e d r i l l i n g  i n adjacent  author  rock  factor  the accuracy  and t h e e v a l u a t i o n o f t h e Rock  was c o n c e r n e d  1  Q u a l i t y Index,  a major  the determination  conventional  Leighton  Data  i s usually  (600 p s i )  while  (500 p s i ) ) o r a s a  range  226  3.4  MPa  to  most  of  more  feet  4.1  the  MPa  time  to  Rock  be  (500  on  the  the  is  to  be  implemented  aware  of  the  would  Quality  Index  follows.  that  the  accurate  data  so  drill that  Lornex  were  during  the  period  of  considering the  was  old  Cougar  seems  that  5.5.2  The of  compiled  from  and  the  use  time RQI  the  the  drilling  Accurate  a  drill  variation from  uncertainities  the  of  and  for  project,  be making problems i t  was  provide domain at  very would  Equity  data  gathered  at  each  site,  recorder  from  data the  would  Greenhills, records  i n almost  extensive  real  would  At  obtained  must  the  the  correlation.  benches  no  compiled  spent  from  few  ground).  decision  in every  from  a  every are  up  backthe to  domain  six of  important.  wide  RQI  It  variations.  Recorders  performance the  recorded  carried  only  compensates  Performance  research  values  drill  crew  the  recorder  author  data  two  quantity  of  RQI  accurate  mass c h a r a c t e r i z a t i o n  on  needed  is  in caving  drilling  present  obtained  of  to  believes that  quantity The  rock  the  depth  prefer  reports  author  computed  covering  pit.  Drill  degree  the  establishment  compiled  months the  that  to  performance  d r a m a t i c a l l y reduced.  hole  (especially  site,  the  the  and  side  their  In  Silver  up  one  The  drillers  approach  The  encountered.  believed  be  safe  at  psi).  some  i n f l u e n c e of  that  be  600  although  If  process  -  by  drilling charts the  do  recorder  partly  data.  The  not  include  driller's  method  RQI  of  reduces  the  values the reporting  the  227  operating factors, For  parameters. reducing  example,  and/or  the  pressure  However,  the  accuracy  b i t wear, between  drilling  practice,  etc.  recorder  may  new  on  the  add  a  bit varies  estimation  of  the  (average)  i n c l u d e s an  data  not  was  experienced  corresponding were  shift.  all  the  holes  recorded  data.  the  drill  a  rigs. the  computerized  operators calculator the  The  author of  idea  of  system  should  can and  office,  technicians.  be  provide teach data The  a  the  chart  applied  b l a s t h o l e depth,  In  file.  for  that  weight the  particular  the  worst  cases,  the  One  other  problem  that  first  and  records  the  last  sometimes  that  there  installation  to  rock  In  mass  the  crew  to  besides  the  the  many i n c e n t i v e s  such  a  s t o r e and  with the  use  on of  time, a  on  blasthole  device  is  Rock  the  mine pocket  Quality  computer a  data,  release  $10.00  a  of  relate  characterization  filed the  drillers  Finally,  recorder  mean  compute  of  are  of  compile,  easily  investigation  difficult  available.  performance  the  b l a s t h o l e number  b l a s t h o l e number  drilling  be  a  charts,  would  how  of  the  developed.  would  use  the  On  gathering  them  in  data.  feels  i f the  the  variations  b l a s t h o l e number  drill  that  velocity  the  the  write  recorded.  of  i t was  with  to  However,  information  In  asked  installation  with  the  are  in bailing  When  bias.  determination  register  the  the  data  recorded  drilled  were  slight  bias.  some e x t e r n a l  that  a p p l i e d weight  i n the  Nevertheless,  drillers  made  the  required to  the  to  i s the  to  of  estimator  included  RQI,  addition,  source  still  difference  drill,  In  are  the  constantly along  blasthole were  of  the  the  there  drill  by  Index.  228  performance  recorder  development  o f t h e optimum  in  eliminating  the  data  when  is  various  drilling  units  review  been  covered  the basic  The  with  more a t t e n t i o n  than  to the d r i l l be c h e c k e d  drills  are operating  will  drills  not perform  manufacturer units in  i s as  important  such factor  Quality  i n order level  o f t h e same m o d e l  the r e l a t i o n s h i p s  It  the e f f i c i e n c y of and/or the  t h i s paragrph  crews  will  T h e same  The c o m p a r i s o n than  between  a s t h e age o r wear  pressure  Many  of trucks  operations and  of  pay  shovels  and r o t a r y  to determine  motors  i fthe  of e f f i c i e n c y .  bought i s true  at different with  o f t h e Rock eliminates  hydraulic  of the  i n the establishment  Compressors  a t t h e same  rather  Index.  of the d r i l l i n g  Index.  to the maintenance  equally.  Quality  factors.  and compared  units.  of weight  data  due t o t h e d r i l l e r  The e f f e c t  maintenance.  should  that  and t h e r e f o r e ,  t h e Rock  much  Generally,  varies  of the d r i l l s ,  i s an o t h e r  correlations  useful  mass.  t h e Rock  operation,  mechanical  condition  components  the  i f the q u a l i t y of  of valuable  the rock  of the equipment.  already  are d e f i n i t i v e l y  However,  efficiency influences a given  has  bias.  to permit  Procedures  within  conditions  i n order  They  the quantity  possible,  the  system.  characterizing  Drilling  Drilling  be c o n t i n u e d  the d r i l l e r ' s  i s important,  important  5.5.3  should  system  times  different Quality the  Index i n  differences  pressure  and  229  applied  weight  which  (manufacturer) the no  pressure drill A  to the other. gage  very He  was  may  normal any  of the type  Nevertheless,  left  open  v a r i a b l e s kept  5.5-1  to  illustrates  o f wear.  readings  bits  does  when  Although the three  of the penetration B i t maufacturers insert  very situations rate  will  rate  until  the very  the graph  that  some  variations  suggests  the compilation  o f numerous  t o smooth  This  claim  bits  are a  that  under  n o t show last  hours.  will  drilling  o f f these  inh i s  1  influence  constant.  i n the penetration  i s recommended  calibrate  by L e i g h t o n  of tricone  conditions, carbide  Therefore, domain  was  The v a r i a t i o n s  drilling  occur.  accurate  model  i s used.  t h e wear  other  Figure  reduction  every  rate,  arise.  function  how  suggested  i n v e s t i g a t e d by t h e a u t h o r .  approximative, that  t o ensure  question  wondered  penetration  question  recorder  important  one d r i l l  It i s also  i n the cabin  performance  report. the  a r e v a r i a b l e s from  data  in  variations in  RQI • Finally, Mine,  obtained  review would  the  a given  rock  diameter  constant.  drilling  o f t h e RQI  the different 1  3  bits  diameter  of the l e v e l conditions.  at Equity  RQI  when  of d r i l l i n g  complex  problem  of d r i l l i n g The d r i l l i n g  and c o n c e r n i n g  Silver  b l a s t h o l e s and a  the following  t o t h e same  i f the degree  i s a very  the b i t manufacturers  values  f i n d i n g s prompt  mass y e i l d  This  determination  optimum by  from  of the L i t t l e ' s  different kept  the comparison  question:  drilled  with  efficiency  related  efficiency guidelines  is  t o the and provided  the a p p l i e d weight per  230  TIME OR FOOTAGE  0  : CUTTER SHAPE  (g) : CUTTER SHAPE CUTTER  (D  CHANGES (more Blunt) STAYS CONSTANT WITH TIME  AND CONE MATRIX WEAR  :CONE MATRIX WEARS  EQUALLY (normal)  FASTER THAN CUTTERS  FIGURE 5.5-h INFLUENCE OF TRICONE ROTARY BIT WEAR ON PENETRATION RATE (after Paquette ) 12  231  inch  of b i t diameter  Burke  1 4  ,  they  penetration added:  penetration capacity  the  a constant  may  increase  the exception rate  i s reduced,  removal  i s reduced,  to  relationship  values  obtained  11).  from  of  a b i tmanufacturer  be  appreciated.  5.5.4  Blasting  It  design  field  research  powder  factors  constant. results  that  rate,  that  velocity  different company  i s reduced.  He  the  the.bailing  increases  improved. Quality  research  would  the  As t h e d i a m e t e r  t h e Rock  Further  by  and t h e  Therefore, Index  The  research  as  decreases  conversion  b i t diameters. and i t s  of the  i s suggested  permit  to  although  formations,  only  shown,  i n chapter  four,  of a c o r r e l a t i o n i s only  between  p o s s i b l e when  V a r i a t i o n s i n the design impossible  on a c o n s t a n t  a correlation  how  design  p r o j e c t has demonstrated  a n d make  performance  limited  i n f l u e n c e t h e optimum  establishment  According  i n order o f RQI  involvement  facilities  would  Procedures  has been  blast  hard  i s generally  (Table  a  of very  the b a i l i n g  accordingly obtain  penetration  equipment."  process  b i t diameter  on e x p e r i e n c e .  as the diameter  i s generally  of the d r i l l i n g  blasthole cutting  yield  rate  "With  a r e based  c a n be o b t a i n e d  factor.  fact.  parameters  This  The  and optimum  the blast  the evaluation  basis.  powder  this RQI  the variations i n  design  design remains  influence the  of the b l a s t  Nevertheless, f o r any b l a s t  i t i s believed design  as  long  232  TABLE 11 RELATIONSHIP BETWEEN ROCK QUALITY INDEX AND ROTARY B I T DIAMETER  BIT DIAMETER  APPLIED WEIGHT  1  311mm - 12 1/4 inches  i  I  reduced  152mm - 6 inches  PENETRATION RATE  I  reduced  com;I ant or s l i g h t increase  i  233  as  they  are  kept  Choked  constant  blasting  damages  the  walls.  becomes  the  only  should  be  present  walls  walls. good  can In  wall  5.5.5  with  are be  failure  the  strength  the  RQI  values  are  a  can  correlated  model.  of  Then,  by  using  mass  been  relationships  their  rock the  Even  concept blasting  if  the  stripping  stable  the  and  and  steeper  testing  the  design  1 5  ,  Rock  a  properties  on  RQI  RQI.  fractured  s t o r e RQI  methods the  mass  work  with  geostatistical  project,  for  more  domain,  to  In  noticed  of  optimum  be  research  control  p i t walls,  in highly  interest  between  Wall  and  where i t  factor  blasts.  reflects  properties could this  powder  development  correlates  the  averaging  inefficient  of  Properties  blasting  with  be  or  and  review  reduced  would  variograms the  rock  is  occasions  producing the  It  procedures.  A  predetermined  few  design  i t permits  blasting  the  very  interim  by  domain.  avoided.  production  Conditions  Within  It  the  behaviour.  given  implemented.  Q u a l i t y Index  of  a  The  postponed  Mass  Rock  are  considered  control  its  be  and  addition,  Rock  The  There  be  solution.  starts  expenses  should  understood  procedure  within  shows In  rock  masses.  Quality  powder  factor.  in a  Quality  complete Index  Index  geological  r o u t i n e s , such more  that  addition,  Rock  data  and  as  picture  and  the  of  rock  obtained.  effect  two on  rock  RQI.  mass In  conditions  intensely  have  fractured  234  rock  masses,  caving  the  ground  explosive  drilling  and  therefore  requirements  fracturing.  time  The  increase  increase  reduce  second  may  with  factor  the  the  slightly  due  values  while  RQI  increase  i s groundwater.  to the  in  the  degree  It  affects  of  the  41  RQI  in  two  different  ways.  groundwater  increases  groundwater  affects  column In  of  both  water  cases,  increases  5.5.6  the  It  guidelines site  of  to  of A  over  Quality  be  with  the  a  sense  distinct  blast  relationships  and  the  the  area.  degree  of  of  This  precision  Finally,  caving.  the  the  drill  when  bottom  changes  the  penetration  Rock  RQI  Quality  and in  this  that  it  the  any  of  the  a  hole.  rate  and  is  not nor As  in  powder  the  factor  i f the  basic  correlations  possible  to  powder  more  data  at  Lornex  are  compare  the  factors are  obtained,  develop.  of  the  ore.  relationship  required  design  the  established  rate  Index  operation  time,  designs.  constraint  variations  Finally,  the  At  also  the  of  the  Index.  should  grinding  accuracy  domain  was  rocks,  at  d i f f e r e n t operations  correlation  RQI  bit  established  followed. in  broken  bailing capacity  groundwater  Rock  are  values  range  that  the  can  specific  applied  the  stands  highly  i n t e n s i t y of  r e l a t i o n s h i p between  exists.  RQI  the  Correlations  A  the  In  has by  the  to  the Rock  However,  is also be  Mine  a  Quality  appears  function  evaluated  milling  it  between  with  of  the  the  operation. Index  in  adjacent  a  235  holes  are large  loading  approach  comparison allocated on  enough may  that  n o t be p r a c t i c a l .  of the b l a s t t o t h e domain  a day t o day b a s i s .  many  drilling  used  when  factors  the data  i t suggests  average could  lead  However influence  a r e few.  RQI  that  a hole  per  Nevertheless,  with  t h e Rock  to a better  i t should  a  Quality  loading  be remembered  t h e RQI, t h e r e f o r e  hole  care  Index  practice that must  be  236  5.6  SUGGESTED  The the  results  Mining  summarize of  enough  Quality  a  design  Rock  practical.  powder  -  that  influence  Index  be  understood.  a)  be  on  to  the d e f i n i t i o n  Quality  Index  and the  that  require  forgotten  that  mass c h a r a c t e r i z a t i o n  of a c o r r e l a t i o n  design  The a u t h o r  these  factors  i s affected  powder  believes  and t h e i r  and b l a s t i n g mechanisms  the operator  permit  wishes  the determination  and t h e optimum  reviewed  T h e RQI  t o rock  of the research  are the points  never  are  the has t o  between  factors  Quality  drilling  t h e Rock  established in  o f U.B.C.  the author  would  f o r the establishment  The f a c t o r s  report  that  I t should  and  simple  well  section,  included  approach  and design  1)  Also  Index  Guidelines RQI  Engineering  c o r r e l a t i o n between factor.  project  the continuation  guidelines  investigation.  Quality  remain  Process  In t h i s  the basic  powder  further  i n the research  to permit  Index.  fruitful  RESEARCH  obtained  and M i n e r a l  interesting Rock  FURTHER  o f t h e Rock factor  that  this  influence  have  to  thesis on t h e  in detail.  by  skill  and honesty  i n producing  accurate  reports b)  the d r i l l i n g i)  weight,  parameters rotary  speed  and compressor  capabilities,  237  although almost ii) c)  ii)  d)  a)  mass  micro  behaviour:  Young's  Modulus  eventually  remain  wear.  and macro uniaxial  and P o i s s o n  and q u a l i t y  energy  the mining i)  and  failure  optimum  should  properties  structural:  the quantity  The  two  constant,  the b i t design  the rock i)  the last  factor  of the  scale, compressive  strength,  ratio. data.  i s i n f l u e n c e d by  method  direction  of b l a s t i n g  in relation  t o t h e major  discontinuities, ii)  presence  b) t h e b l a s t i)  design  ratios  iii) c)  ii)  a)  free  faces.  diameter,  bench  height,  burden,  subdrilling.  and  initiation  sequence,  explosive properties.  the rock i)  In  delays  of  parameters  of hole  spacing, ii)  or absence  mass  properties  structural:  micro  failure  behaviour:  Young's  Modulus  the f i e l d , Define  and macro uniaxial  and P o i s s o n  the following procedure  blasting  domains.  scale, compressive  strength,  ratio.  is  suggested:  238  b)  Standardize design  c)  blasting  powder  Average  RQI  domain.  their d)  Mine  RQI  a  benches  in drilling  factor.  an  possess  advantage.  optimum  optimum  in  every  practice  t o pay  Look  at  t h e powder  and  attention  the  to  possibility  factor  is a  from  basic drill  I f such  be  interesting  to  obtain  of  according  to  the  rock  mass  use  of moving  would a  data  on  average  should  practice  blasting  understand on  with  t h e methods operations  of  the  the  operation  the design  recorder  base simple  The  and  and  powder  i n order  on  the establishment  of  available,  t h e Rock on  could  a  long  permit  RQI  development  their  geostatistic  Moreover,  of  use  i s already  between  techniques  comparison  i s needed  relationship.  simplify  correlations  properties.  They  and  asset.  performance  to perform  other  good  general  rigs  drilling  familiarity  different  or  good  blasting  Their  investigation  drill  base.  that  approach  computerized blasthole  three  drillers  o p t i m i z a t i o n of  of  obtained  establish  powder  stability.  Further  data  vs  have  influence  values  the  relationship.  records  factor  last  changes  Encourage  operators  slope  f o r the  Consider  further  3)  define  reports.  Plot  the  and  factor.  data  equipment.  procedures  routines Quality term to  a  to of  large  i t would in  order  Index  basis,  a  and the  e v a l u a t i o n of  239  the  trends  powder  i n Rock  factor  that  Quality w o u l d be  Index  and p r e d i c t  required  on  t h e optimum  future  benches.  design  240  5.7 1.  REFERENCES LEIGHTON,  J.C.;  Drill  Development  Performance  Master's  Degree  Columbia, 2.  ASHBY,  J.P.; Pit  Conference  3.  4.  SCARTACCINI,  HAGAN,  3rd  International  Stability  Hole  AIME,  of  I.W.;  in Surface Mining,  Drill  Meeting St.  Recorder  of  of  Open  Brawner  Drills  Efficiency,  the  Utilization,  Society  of  Louis, Missouri,  Performance  Blasthole  Quarrying  Development  1982  Engineers  and  British  Proceedings,  Fall  Blasting  of  Rotary  Factors,  the  Blast  Production  Powder  and  AIME,  Reid,  Controlled  Between  1982  Proceedings,  T.N.;  Correlation  Blasting  on  T.E.;  a  Thesis, Univeristy  Production  editor,  and  August,  Slopes,  of  Means  Proceedings,  Symposium,  1970  Monitoring - A  Bristol,  2nd  Mining  of  of  Increasing  Surface  England,  Mining  October  1 983 5.  LUTZ,  J . , et  a l ; Instantaneous  Theory V24, 6.  Manuel  of  Drilling,  June,  S.A.  7.  CYR,  J.B.;  Vibralog,  (France).  Consultants et  Silver  District  Six  on  a  Petroleum  P u b l i s h e d by  Available  Inc,  a l ; Geology Mine,  J o u r n a l of  Based  Dynamic Technology,  1972  d Information: v  Logging  Lutz,  ( i n E n g l i s h ) from  S a i n t - L a u r e n t , P.Q. and  Jean  Mineralization  Houston,  B.C.,  Meeting,  Smithers,  H4T at  1E3  Equity  Proceedings, B.C.,  Solroc  8th  1983  CIM  241  8.  PEASE,  R.B.;  Geological  Silver 9.  ROTHERHAM,  Mine  D.C.;  Mapping,  Property,  Geology  Silver-Copper  and  1982  Field  unpublished Ore  I,  Equity  report  Reserves  D e p o s i t s Volume  Season,  of  the  1979,  Sam  Goosly  unpublished  report 10.  11.  WALDNER,  BRITCH,  G.D.;  et  a l ; Lornex  Canadian  Cordillera,  no.  1976  15,  C ; CIM  12.  PAQUETTE,  13.  LITTLE,  The  Greenhills  Bulletin, C;  T.E.; Rotary  March  Personal  paper  Surface  of  a  Columbia,  1976  J.R.;  15.  RAYMOND, G.;  Personal Ore  Orebody,  CIM  Coal  special  Mining  B.A.Sc.  the  volume  Project,  1983  Index  Based  on  thesis,  Dept.  of  University  Problems CIM  August,  Quality  Communication,  Estimation  Mineralized  Rock  Performance,  Engineering,  BURKE,  D e p o s i t s of  1981  Geological  14.  13,  Communication,  Evaluation Drill  , Porphyry  of  British  June,  1984  i n an  Erratically  Bulletin,  June,  1979  242  CHAPTER 6  243  6.0  CONCLUSIONS  The  excavation  methods  i s an  results  on  such  that  design. all  the  slope  task.  classification a  whole.  and  is  factor  followed.  design pit.  reflects  the  between  can  be  the  Rock  established  First,  the  blast costs  optimum take  process  into  of  is  blast  an  account . open  is a  very  is a  simple  rock  rock  mass  rotary  the  powder  easily factor  drilling  and  constant. quantity this  properties.  pit  mass  properties  drills,  point, As  performance. also  is also  the  accurate the  when  held  this  it  as  is  that  an a  same  the  the  be  the  these  i s not  blast  within  the  the factors  possible  i s needed  left  rock  are  mass  properties  empirical  procedure  only  upon  data  design  right  constant  parameters  i n t e r a c t i o n of  appears  to  dependent  drilling  r e s u l t s , the  and  the  equipment,  only  Consequently,  Index  has  being  Practically,  of  blasting  It  the  operating  can  Quality  the  practice  defined.  blasting  expensive.  RQI  the  and  of  process  the  blasthole  the  influence  be  that  since  At  theory  Index  Secondly,  averaged.  drill  Quality  others  a  reach  optimization  the  therefore,  total  design  left,  maintained  mass  to  the  drilling  influence  the  blasting  Rock  from  and  made  in  using  The  variable  drilling be  be  the  system  Correlation  to  rock  The  not  slope  task.  included  Obtained  practical  powder  no  Consequently,  difficult  rock  stability  e f f o r t s have  variables  blast.  a  engineering  However,  the  of  must and  and  the  rock  properties  affect  the  relationship  c o r r e l a t i o n between  Rock  can  244  Quality  Index  Based following 1)  on  and  grindability  two  years  conclusions A  powder  practices,  defined  maintained  constant  It  that  appears rock also  muck  mass a  determined.  the  a  Rock  factor  and  is  4)  the  are  blasting  on  be  subject,  the  presented:  between  design  also  research  correlations  the  3)  are  correlation  optimum  2)  of  can  exists.  for as  Q u a l i t y Index  the  long  throughout  f u n c t i o n of  the  this  different as  there  the  point,  drilling  are  the p i t .  correlation  grindability  At  and  can  be  although size  of  established with the  the  grinding  fragments  rate in  the  pile.  Accurate  monitoring  needed.  The  in  of  units  of  downpressure applied  Considerable  the  data  representative  of  drilling readings  parameters should  be  is  recorded  weight.  are  needed  the  rock  in order  mass  to  be  properties within  each  domain. 5)  Groundwater Quality  6)  Rock  Drill tool.  Q u a l i t y Index  However,  digital  data  computer  performance  gathering by  caving  b l a s t h o l e s i n f l u e n c e the  Rock  Index.  geological 7)  and  could  model  to  recorders  when  programs,  used  stored  facilitate are  a  useful  in conjunction  recorded  information.  be  charts  within  the  analysis. drilling with  should  be  RQI  data  replaced  245  Even  with  approach Blasting i)  improved may  per hole  loading  practical.  approach  t o be made  powder ii)  n o t be  a hole  procedures:  T h e RQI has  monitoring,  factor  t o rock  mass  in conjunction approach  Controlled blasting  characterization with  to blast  commences  the design  engineering,  with  production  blasts. iii)  Sequential  blasting  techniques  improve  slope  stability. iv)  Choked the  v)  blasts  blast  Blast  decrease  the slope  and  performance,  evaluations are also  engineer's  stability  task.  part  of the  blast  246  BIBLIOGRAPHY  247  BIBLIOGRAPHY 1.  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WALSH,  15,  J.B.;  Rock  57,  and  Drilling, Mining  1965  Aluminized  Society  Blasting on  Agents,  blasting  and  of E x p l o s i v e s  1981  P i t Rotary  Drilling  the A u s t r a l i a n  Course  Technology, 102.  pp  Phoenix,  1 of  Workshop  - A  USBM,  i n Rock  Mechanics  of the 7th conference  Open  Chapter  1973  Determination  Energy  J o u r n a l o f Rock  techniques,  Engineers,  AIME,  for Percussion D r i l l s ,  GUNK, A . G . ;  Proceedings  101.  Drillability  of S p e c i f i c  V o l . 2,  THORNBY, G.M.;  editor,  1975  International  100.  F.H.;  Index  8073,  and G i v e n  of  Mineral  Manual, D r i l l i n g  Adelaide,  Foundation  and  Blasting .  1977  et a l ; Lornex, Cordillera,  Blastholes,  Porphyry  paper  Deposits  of the  Special  Volume  13, C I M  1975 BRACE,  Mechanics  W.F.;  Mechanics  Symposium,  o f Rock  Sikarskie  Deformation,  editor,  ASME,  1 973 104.  WHITE,  C.G.;  the 105.  Colorado  WILLIAMSON, 6.3,  A Rock  T.N.;  Pfleider  Drillability  Index,  School  of Mines,  V  Rotary  Drilling,  Surface Mining,  editor,  AIME,  1972  64,  Q u a r t e r l y of N  2,  1969 Sect.  259  106.  WINZER,  S.R.;  RITTER,  Discontinuities Fragmentation Symposium Rolla, 107.  YOUNG,  C ;  Rock on  A.P.; The R o l e i n Rock  i n Large  on Rock  of Stress  Fragmentation: Limestone  Mechanics,  Waves a n d  A Study  Blocks,  University  of  2 1 s t U.S. of  Missouri-  1980 Rock  Fragmentation  Fragmentation  Rock  Mechanics,  Engineering  - Needs  session  Possibilities,  o f t h e 1 7 t h U.S.  University  Experiment  and  of Utah,  Station,  1976  Utah  Symposium  260  4>  APPENDIX  I  261  APPENDIX I BIT  Soft  COMPARISON  rock Hughes Reed Security Smith  HH33 M52J S8M Q4  Medium-soft rock Hughes Reed Security Smith Varel  HH44 M62 M8M Q5 AMC8  Medium-hard rock Hughes Reed Security Smith Varel  HH77 M73 - M74 H8M Q7 QMCS  Hard  rock Hughes Reed Security Smith Varel  HH99 M83 H10M Q9 QMCH  262  APPENDIX  II  2 63  APPENDIX I I R E L A T I O N S H I P BETWEEN DOWN P R E S S U R E AND A P P L I E D WEIGHT MANUFACTURER AND MODEL  MAXIMUM PULLDOWN HYDRAULIC PRESSURE  Bucyrus 30-R  Erie  30,000 l b s @ 1,000 l b s . g a g e pressure  Bucyrus 40-R  Erie  50,000 l b s ,  Bucyrus 45-R  Erie  70,000 l b s . @ 1,300 l b s . g a g e pressure  Bacyrus 50-4  Erie 75,000 l b s ,  Bacyrus E r i e 60-R & B u c y r u s E r i e 61-R  110,000 l b s . @ 1,200 l b s . g a g e pressure  Gardner-Denver GD-60  60,000 l b s .  WEIGHT RATIO FACTOR  S e r i e s 45 m o t o r 21 p r e s s u r e + 3,800 l b S e r i e s 6 0 m o t o r 27 p r e s s u r e + 3,800 l b  x gage s. x gage s.  S e r i e s 4 5 m o t o r 57 p r e s s u r e + 7,000 l b S e r i e s 60 m o t o r 72 p r e s s u r e + 7,000 l b  x gage s. x gage s .  45 x g a g e p r e s s u r e 10,000 l b s .  +  S e r i e s 45 m o t o r 49 x g a g e p r e s s u r e + 9 , 0 0 0 l b s . , 60 m o t o r 62 x g a g e p r e s s u r e + 9,000 l b s . , 7 5 m o t o r 82 x g a g e p r e s s u r e + 9,000 l b s . 80 x g a g e p r e s s u r e 14,000 l b s .  +  The a c t u a l w e i g h t on t h e b i t c a n be r e a d f r o m t h e h y d r a u l i c gage o n t h e GD-60,  GD-80,  and t h e  GD-120  G D - 1 3 0.  Gardner-Denver GD-80  80,000 l b s .  Same a s G D - 6 0  Gardner-Denver GD-120  12 0 , 0 0 0 l b s .  Same a s GD-60  Gardner-Denver GD-130  130,000 l b s .  Same a s GD-60  264  Marion  M-4  105,000 l b s . @ 3,500 l b s . g a g e pressure  24.3 x gage p r e s s u r e + 20,000 l b s . H y d r a u l i c gage i n d i c a t e s a c t u a l weight on t h e b i t  Marion  M-5  120,000 l b s . @ 3,500 l b s g a g e pressure  28.6 x gage p r e s s u r e + 20,000 l b s . H y d r a u l i c gage i n d i c a t e s a c t u a l weight on t h e b i t  C h i c a g o P n e u m a t i c 30,000 l b s . @ T-650 2,300 l b s . g a g e pressure  13.  C h i c a g o P n e u m a t i c 50,000 l b s . @ T-750 2,300 l b s . gage pressure  21.75 x gage  C h i c a g o P n e u m a t i c 60,000 l b s . @ C-850 2,300 l b s . g a g e pressure  26 x g a g e  pressure  C h i c a g o P n e u m a t i c 90,000 l b s . @ 2,700 l b s . g a g e C-950 pressure  33 x g a g e  pressure  C h i c a g o P n e u m a t i c 100,000 l b s . @ C-975 3,200 l b s . g a g e pressure  31.25 x gage  Robbins  RR  R o b b i n s RR  x gage  pressure  pressure  pressure  10-S  65,000 l b s .  30.6 x g a g e p r e s s u r e + 6,000 l b s .  11  70,000 l b s .  30.6 x g a g e p r e s s u r e + 7,500 l b s .  Robbins  RRT-50  50,000 l b s .  30.6 x g a g e p r e s s u r e + 5,000 l b s .  Robbins  RRT-60  60,000 l b s .  30.6 x g a g e p r e s s u r e + 6,000 l b s .  Robbins  RRT-7 0  70,000 l b s .  3 0.6 x g a g e p r e s s u r e + 8,000 l b s .  265  41.28 x g a g e + 3,000 l b s .  pressure  R o b b i n s H100 Horizontal Drill  80,000 l b s .  Schramm T985H  38,000 l b s . @ 2,000 l b s . g a g e pressure  19.  x gage  pressure  Schramm T64HB  30,000 l b s . @ 2,000 l b s . g a g e pressure  15,  x gage  pressure  Schramm C985H  50,000 l b s . @ 2,500 l b s . g a g e  Schramm C9120  50,000 l b s . @ 2,500 l b s . g a g e pressure  20 x g a g e  pressure  20 x g a g e  pressure  266  APPENDIX  III  267  APPENDIX I I I P O S S I B L E B E N E F I T S FROM  Increased Reduced —  shovel shovel  IMPROVED  FRANGMENTATION  capacity maintenance:  p a r t l y due t o l o n g e r bucket and t e e t h s h o v e l w o u l d n o t be a b u s e d i n d i g g i n g on h a r d bottoms  Increased  truck  capacity  (reduced loading  Reduced t r u c k maintenance: — p a r t l y due t o f i n e r m a t e r i a l -- p a r t l y d u e t o l a r g e o v e r s i z e body Increased Reduced  crusher crusher  l i f e because t h e oversized boulders time)  flows better boulders not s t r i k i n g the  capacity maintenance  Increased  mill  capacity  Decreased  or eliminated  Decreased  p i t clean-up  secondary  cost  costs  Decreased t r u c k t i r e wear: -- p a r t l y b e c a u s e f i n e r m a t e r i a l s surfaces Decreased v e h i c l e cost (pick-ups, maintenance  breaking  provide  better  from b e t t e r p i t f l o o r s trucks, etc.)  travel  268  ( APPENDIX  IV  269  APPENDIX I V R E V I E W OF T . E . L I T T L E R E P O R T ON  Shortly  after  being  I n d e x was i n v e s t i g a t e d design and  the  attempts  i)  w e r e made  with  o f Rock Q u a l i t y  i t sa p p l i c a b i l i t y RQI v a l u e s w e r e  to correlate  and p h y s i c a l  carried  contour  patterns  properties of the rock.  o u t a t Endako, K a i s e r and G i b r a l t a r  summer o f 1 9 7 5 .  variables  1.  i n regard  t h e concept  o f open p i t s l o p e by L i t t l e .  mechanical were  proposed,  RQI  I t was f o u n d  that several  to the  contoured with  The s t u d i e s mines  during  independant  c a n h a v e a n i n f l u e n c e o n RQI v a l u e s .  Conclusions Recorded Little  o f t h e Endako  drilling  observed  RQI i s t o t a l l y data  on d r i l l  was n o t e d  field  work:  data:  that the accuracy  of calculated  dependant on t h e accuracy b i tperformance  records  t h a t t h e RQI c o n t o u r s  movements o f t h e d r i l l s . show t h a t f o r many w o r k have been  allocated  addition,  drilling  minutes  Mine  Drill shifts,  tend  of recorded  (driller  records,  t h e same d r i l l i n g  parameters  i n one s h i f t .  to the nearest  a n d t h e h y d r a u l i c down p r e s s u r e  I t  with the  b i tperformance  was r e c o r d e d  data  logs).  to relate  to a l l holes d r i l l e d time  values of  In  five  t o the nearest  50 t o 1 0 0 p s i . ii)  Drill At and  type  and  size:  E n d a k o , B u c y r i u s BE 40-R d r i l l i n g Marion  used.  M-4  drilling  9 7/8  inches  9 inches diameter diameter  holes  holes  were  270  A  comparison of  drilling 0.6  -  iii)  equipment  0.7  varies  adjacent  (9  RQI  shows t h a t  7/8").  significantly  Lithology  and  Generally,  higher  high  It  was  strength  hardness  or  Recorded was  observed and  In  of  drill  steel.  and  was  different equal  that  drill  to  the  RQI  used,  i n the  fractured  has  RQI  or  a  low  not  Little  Mine  rock  where the  to  rock  be  tried  is  field  generally strength.  related to  to  RQI  but  were  correlate with  also  of  mass,  compressive  appeared  may  vicinity  Lower v a l u e s  fracturing with  that  high speed  the  the  relate  without  rock success.  work:  due  to  sandstone  and  siltstone  the This  therefore  v a r i a t i o n s i n the are  a d d i t i o n , the  included  the  data:  beds of  feet  rate  the  Kaiser  rotary  40  occured  strength.  w h i c h may  the  type of  zone area  degree of  of  alternating seam.  that  drilling  pressure  ...  fault  (9")  RQI  concluded  highly  structure.  and  Conclusion  It  in a  concluded  lithology  i)  a  with  geology:  f r a c t u r e d , a l t e r e d and  rock  II.  as  the  the  values  compressive  encountered well  with  RQI  drilled  I t was  structural  dyke c h a r a c t e r i z e d have.a  holes  drilling  time  the  time  required  to  p r a c t i c e reduces  increased  the  RQI.  hydraulic  presence  add the  a  of  above the  for holes  deeper  second real  down  coal than  piece  penetration  271  ii)  B i t design Extremely steel  and  size:  high  tooth  values  bits  were  ranged  from  1.5  Little  also  observed  drilled  by  for  9  the  icantly  to  the 7/8  of  RQI  used.  8.0  times  that,  same m o d e l  of  those  obtained  obtained  i n areas  The  RQI  for  steel  the  RQI  for  insert  even  inch diameter  from  were  though  drill,  where  tooth  bits  bits.  a l l b l a s t h o l e s were-  the  RQI  bits  did  not  with  the  12  values  differ 1/4  obtained  signif-  inches  diameter  bits. iii)  L i t h o l o g y and  structural  Areas  RQI  of  stones. allel RQI  III. i)  In  with  the  values  Recorded  a  were  addition,  also  from  was  Drill  type  As (9  7/8")  showed the  range  and  RQI  and that (12  trend  geological  Gibraltar  zones of  of  the  strike  Mine  field  hard  RQI was  in faulted  h y d r a u l i c down p r e s s u r e ( i e . , 500  probably  f o r Endako  general  with  sand-  subpart noted.  Low  areas.  work  data:  G a b r a l t a r , the  value  a  encountered  the  drilling  standard  correlated  structural  were  Conclusions  At  . i i )  high  geology:  around  -  100  650  psi)  was  while  recorded  the  as  actual  psi.  size: Mine,  Marion the  RQI  1/4).  two M4 (9  models (12  1/4")  7/8)  was  of  drill  were  Comparison equal  to  0.5  used: of to  RQI 0.7  BE  45R  values times  272  iii)  L i t h o l o g y and s t r u c t u r a l High  RQI v a l u e s  of  broken  of  fracturation  lower,  were r e c o r d e d  and f a u l t e d  rock.  i n areas In areas  of low  percentage  where t h e i n t e n s i t y  i n c r e a s e d , t h e RQI v a l u e s w e r e g e n e r a l l y  indicating  fracturing  geology:  a r e l a t i o n b e t w e e n RQI a n d t h e d e g r e e o f  of the rock.  Summary o f L i t t l e ' s  Conclusions  1  are limited  - interpretations  by t h e r e l i a b i l i t y  of the data  input. - some t i m e s , any  other  - averaging these  t h e RQI i s r e l a t e d  - there  techniques  techniques  the  similar steel as  drills  i n rock  quality.  s t r e n g t h , however,  rocks  relationship  showed a l o w RQI.  b e t w e e n RQI a n d  produce  faulted  higher  RQI  geology. (note  that  models were d i f f e r e n t ) . size  b i t s o n t h e same t y p e  of d r i l l  produced  RQI v a l u e s .  tooth b i t s produced  those  changes  t o rock  fractured  b i t s on l a r g e r  drill  to  f o r the inaccurate data, but  the real  related  i s no d i r e c t  - different  -  compensated  masked  and i n t e n s e l y  3 - larger  movement more t h a n  factors.  2 - RQI i s p r i m a r i l y areas  to drill  f o r tungsten  RQI v a l u e s  carbide insert  u p t o 8.0 t i m e s bits.  as  high  273  APPENDIX  V  274  APPENDIX M O D I F I C A T I O N OF  When i t i s e v i d e n t obtained should a  that  from a p a r t i c u l a r  be m o d i f i e d ,  series of t r a i l s  i n order  whenever p o s s i b l e , o n l y  the  the type cost  unsatisfactory results  to arrive  and,  of  factors  which  are relevant  being  t h e method  have t o embark  on As  of each b l a s t i s e s s e n t i a l  f o l l o w i n g sequence o f t e s t  sequences could  may  one v a r i a b l e a t a t i m e  effectiveness of using test  and t h a t  are  a t an optimum d e s i g n .  c a r e f u l documentation  of experiment which would  Similar  METHODS  the b l a s t i n g engineer  any t r i a l s ,  The  BLASING  b l a s t i n g method  with  changed.  V  work  i s an  be c a r r i e d  a higher  be c a r r i e d  energy  should  illustration  out to  evaluate  explosive.  f o r each of the  i n a particular  be  other  situation.  Rationalization: a.  Document using that  the weight  powder  f a c t o r s on an e q u i v a l e n t  strengths  of the explosive  should are  present  be o b t a i n e d  of various  i n current use.  from  explosives  energy  basis  compared t o  Weight strength  the explosives manufacturer  data  i f these  not already available.  Evaluation: b.  For a blast with the  behaviour  condition  the explosive  currently i n use,  of the blast during  of the resulting  muck  initiation  pile.  document  and t h e  2 75  c.  Document  rate  and c o n d i t i o n s  d.  Document  fragmentation  material  requiring  based  secondary  of  digging.  upon t h e r a t i o  of  oversized  blasting to the total  blast  tonnage.  e.  document d r i l l i n g  and b l a s t i n g  costs.  Experimentation: f.  Select  a s i m i l a r area  higher  powder  energy  explosive  a  of ground  f a c t o r which  and c a r r y  i s obtained  e.g. by i n c r e a s i n g  out a blast with  by u s i n g  a  a  higher  the aluminum content  of  slurry.  Evaluation: g.  Document  t h e r e s u l t s as f o r steps  h.  Carry  i.  Repeat the experiment  out a cost-benefit  ment s u g g e s t i n g  b t o e.  study.  before  preparing  a modification  a statement  or a retention  t o mange-  of the existing  method.  It blast long of  should  performance trial  be n o t e d  that  on a computer.  and e r r o r  process  possible modifications  reduction in  also  i t i s now This  of f l y r o c k s , toes,  N o r t h /America i s a v a i l a b l e t h r o u g h  Military  College  i n St.-Jean,  Quebec.  simulate a  one t o n a r r o w t h e  to a target  etc.).  to  approach eliminates  and p e r m i t s  i n regard  possible  objective  The m o s t p u b l i c i z e d R.F.  field  (ie., system  Favreau of the Royal  


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