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High-pressure coal injection in the zinc slag fuming process Cockcroft, Steven Lee 1986

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HIGH-PRESSURE COAL INJECTION IN THE ZINC SLAG FUMING  PROCESS  by STEVEN L E E COCKCROFT B.Sc,  University  B.A.Sc,  University  of B r i t i s h of B r i t i s h  C o l u m b i a , 1980 Columbia,  1984  A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS MASTER  FOR THE DEGREE OF  OF APPLIED SCIENCE in  THE FACULTY OF GRADUATE  STUDIES  (Department of M e t a l l u r g i c a l E n g i n e e r i n g )  We a c c e p t t h i s to  thesis  the required  as c o n f o r m i n g standard  THE UNIVERSITY OF BRITISH COLUMBIA December 1986  (§) S t e v e n L e e C o c k c r o f t , 1986  In  presenting  degree  thesis  in  partial  fulfilment  of  the  the  University of  British Columbia, I agree  freely available  for reference  and study. I further  copying  at  this  of  department publication  this or of  thesis for by  his  or  requirements that the  agree  scholarly purposes may be her  representatives.  It  this thesis for financial gain shall not  is  of  M Cf^LLUttGtI  The University of British Columbia 1956 Main Mall Vancouver, Canada V6T 1Y3  DE-6C3/81)  CfcL  an  granted  advanced  Library shall make  that permission for by the  understood  that  it  extensive  head  of  copying  my or  be allowed without my written  permission.  Department  for  IAJ£S£/KT6I  ii ABSTRACT  Zinc s l a g  fuming i s  on the d i r e c t r e d u c t i o n of the  a k i n e t i c a l l y c o n t r o l l e d process based  of s l a g by e n t r a i n e d  process are governed p r i m a r i l y by two  (1)  the  f r a c t i o n of c o a l e n t r a i n e d  (2)  the  r a t e of f e r r o u s  A series  iron  of high-pressure  coal.  were  facilitate  i n the  increased  improved.  injection  predictions  The  kinetics  Brimacombe*  3  process has  lead  been from  r e a c t i o n model has of l i q u i d modified  based  Fuming  rates  efficiencies  were  i n d i r e c t c o n t r a d i c t i o n to  mathematical  model  developed to  include  furnace.  by the 11  the  the  zinc  Richards reduction prill  account f o r  Analyses of the that  of  A lead  been formulated to  indicates  have been  equilibrium.  modified the  and  B r i t i s h Columbia i n  over-all  originally  m e t a l l i c lead. model  and are  of models based on  s l a g - fuming  removal of  results  trials  c o a l entrainment.  substantially These  slag,  oxidation.  coal  increased  kinetics  factors:  completed at Cominco's lead smelter i n T r a i l , order to  The  the  and  " - slag behaviour  t r i a l data with  significant  and  improvements  entrainment were achieved with high-pressure c o a l i n j e c t i o n .  the in  iii TABLE OF CONTENTS  ABSTRACT  i i  TABLE OF CONTENTS  i i i  LIST OF TABLES  vi  LIST OF FIGURES  vii  TABLE OF SYMBOLS  xi  ACKNOWLEDGEMENTS  xiv  CHAPTER 1 INTRODUCTION: 1.1 1.1.1 1.2 1.2.1  SLAGS AND SLAG PROCESSING Slag P r o c e s s i n g Slag Cleaning The Zinc Slag Fuming Process History  1  .  3 4 6 11  CHAPTER II LITERATURE REVIEW  15  2.1 2.1.1 2.1.1.1 2.1.1.2 2.1.1.3 2.1.1.4 2.1.2 2.1.3 2.2 2.2.1 2.2.1.1 2.2.1.2 2.1.1.3 2.1.1.4  15 16 17 17 21 21 21 22 22 23 23 26 27 29  P u l v e r i z e d Coal Transport Pneumatic Conveying of M a t e r i a l s M a t e r i a l - I n t o - A i r Systems A i r - M i x i n g Systems A i r - I n t o - M a t e r i a l System S e l e c t i o n of System Non-Pneumatic Transport Summary: Pneumatic Conveying The Zinc Slag Fuming Process Studies and M o d e l l i n g E q u i l i b r i u m Models E m p i r i c a l Models I n d u s t r i a l and Laboratory Studies The K i n e t i c Model of the Process  iv  v.  CHAPTER I I I OBJECTIVES  AND SCOPE OF THE RESEARCH  41  CHAPTER I V EXPERIMENTAL EQUIPMENT AND TECHNIQUES 4.1 4.1.1 4.1.1.1 4.1.1.2 4.1.1.3 4.1.1.4 4.2 4.2.1 4.2.1.1 4.2.1.2 4.2.1.3 4.2.2 4.2.3  43  I n d u s r i a l Equipment H i g h - P r e s s u r e C o a l D e l i v e r y / I n j e c t i o n System Design C r i t e r i a Summary o f D e s i g n C r i t e r i a System S e l e c t i o n The H i g h - P r e s s u r e D e l i v e r y S y s t e m Experimental Techniques Industrial Tests S l a g Sampling Operating Procedures Summary: I n d u s t r i a l T e s t i n g Procedure . . . C h e m i c a l A n a l y s i s o f S l a g Samples Uncertainty  43 43 43 49 50 52 57 57 58 59 61 62 62  CHAPTER V EXPERIMENTAL RESULTS AND PRELIMINARY ANALYSIS 5.1 5.2 5.2.1 5.2.2 5.2.3 5.3  Results P r e l i m i n a r y A n a l y s i s and D i s c u s s i o n H i g h - P r e s s u r e I n j e c t i o n Dynamics Normal Fuming P r a c t i c e a t Cominco High-Pressure Coal I n j e c t i o n Preliminary Analysis Summary  64 64 64 65 68 70 91  CHAPTER VI MATHEMATICAL MODEL OF ZINC FUMING PROCESS DISCUSSION OF MODEL F I T T I N G  AND  6.1 M o d i f i c t i o n s t o t h e R i c h a r d s Model 6.1.1 The K i n e t i c C o n c e p t u a l i z a t i o n o f t h e P r o c e s s 6.1.1.1 The C o a l P a r t i c l e - S l a g R e a c t i o n Model . . . . 6.1.1.1.1 Zinc Balance 6.1.1.1.2 Lead B a l a n c e 6.1.1.1.3 Carbon Balance 6.1.1.1.4 Oxygen B a l a n c e 6.1.1.1.5 Hydrogen B a l a n c e 6.1.1.1.5.1 E q u i l i b r i u m o f t h e Water-Gas R e a c t i o n 6.1.1.1.6 N Balance . 2  93 95 95 95 103 104 106 107 108 108 109  V  6.1.1.1.7 Bubble Radius 6.1.1.1.8 Char P a r t i c l e R a d i u s 6.1.1.1.9 Char P a r t i c l e Weight I 6.1.1.1.10 Gas Volume I 6.1.1.1.11 I n i t i a l Conditions 6.1.1.1.12 Thermodynamic D a t a . 6.1.1.1.13 Mass T r a n s f e r 6.1.1.1.13.1 Mass T r a n s f e r o f Pe "*- and F e * 6.1.1.1.13.2 Mass T r a n s f e r C o e f f i c i e n t s 6.1.1.1.14 B o u d o u a r d and C h a r - S t e a m R e a c t i o n s . . . 6.1.1.1.15 Model S o l u t i o n 6.1.1.2 The K i n e t i c s o f L e a d Removal 6.1.1.2.1 The L e a d P r i l l - S l a g R e a c t i o n Model . . . 6.1.1.2.1.1 Mass B a l a n c e on L i q u i d L e a d 6.1.1.2.1.2 Mass T r a n s f e r 6.1.1.2.1.3 Mass T r a n s f e r C o e f f i c i e n t s . 6.1.2 The F u r n a c e Model 6.2 D i s c u s s i o n o f Model F i t t i n g 6.2.1 R e s u l t s o f F i t t o Normal O p e r a t i o n 6.2.1.1 D i s c u s s i o n o f F i t t o Normal O p e r a t i o n . . . . 6.2.2 R e s u l t s of F i t t o High-Pressure Operation . . 6.2.2.1 D i s c u s s i o n of F i t t o High-Pressure Operation 6.2.2.2 F i t to High-Pressure Operation: Entrainment Factors 2  3  110 110 l l l l 112 113 113 116 120 121 122 122 123 124 124 127 127 128 129 134 136 136 151  CHAPTER V I I S E N S I T I V I T Y ANALYSIS  153  7.1 Sensitivity Analysis: Results 7.1.1 R e s u l t s and D i s c u s s i o n 7.1.1.1 The I n f l u e n c e o f L e a d on K i n e t i c s 7.1.1.1.1 The K i n e t i c s o f t h e Char P a r t i c l e - S l a g Model 7.1.1.1.2 The K i n e t i c s o f L e a d P r i l l O x i d a t i o n 7.2 Sensitivity Analysis: Discussion 7.3 Sensitivity Analysis: Summary CHAPTER  153 155 184 . .  VIII  SUMMARY AND CONCLUSIONS 8.1 8.2  Summary Sugguestions  190 . f o r Further  REFERENCES APPENDIX  184 186 186 189  I  Work  190 191 19 2  FUMING SAMPLING  DATA  196  LIST OF TABLES  Table 1. 1  Classification  Table 4. 1  Estimated U n c e r t a i n t y of A n a l y s i s  . . .  63  Table 5. 1  High-Pressure I n j e c t i o n Dynamics  . . .  66  Table 5. 2  Fuming Rates and E f f i c i e n c i e s  Table 6. 1  Thermodynamic Data f o r Reactions  Table 6. 2  Model F i t t i n g Parameters  Table 7. 1  Standard C o n d i t i o n s f o r S e n s i t i v i t y  of Pneumatic Conveyors .  18  77 . . . .  114  .  130  vi i  LIST OF FIGURES  F i g u r e 1.1  F i g u r e 4.1  F i g u r e 4.2  Schematic diagram showing the furnace i n c r o s s - s e c t i o n and the chemical r e a c t i o n s o c c u r r i n g i n the process . . .  7  Schematic diagram showing the pneumatic conveyor, high-pressure i n j e c t o r and the standard low-pressure tuyere . . . .  48  Schematic diagram showing the pneumatic conveyor i n d e t a i l  55  F i g u r e 5.1  Zn and Pb p r o f i l e s  F i g u r e 5.2  Fe "*- and F e 3  F i g u r e 5.3  Temperature  F i g u r e 5.4  Furnace o p e r a t i n g c o n d i t i o n s f o r Run 1  75  F i g u r e 5.5  Zn and Pb p r o f i l e s  80  F i g u r e 5.6  F e * and Fe3* p r o f i l e s  F i g u r e 5.7  Temperature  F i g u r e 5.8  Furnace o p e r a t i n g c o n d i t i o n s f o r Run  F i g u r e 5.9  Zn an Pb p r o f i l e s  F i g u r e 5.10  Fe  F i g u r e 5.11  Temperature  F i g u r e 5.12  Furnace o p e r a t i n g c o n d i t i o n s f o r Run  F i g u r e 6.1  The char p a r t i c l e - s l a g  F i g u r e 6.2  Photomicrograph of quenched  2  +  f o r Run  profiles  slag  and F e  72  f o r Run 1 . . . .  p r o f i l e f o r Run 1  f o r Run  2  3+  1  p r o f i l e f o r Run  3 +  f o r Run  profiles  74  2  f o r Run  2 . . . .  2  81 82  2  3  83 87  f o r Run  p r o f i l e f o r Run  73  3 . . . .  3  88 89  3  90  r e a c t i o n system  99  and p o l i s h e d  sample  100  F i g u r e 6.3  The lead p r i l l - s l a g r e a c t i o n system . . . 125  F i g u r e 6.4  I n d u s t r i a l data and model f i t to the Zn and Pb p r o f i l e s f o r normal o p e r a t i o n  131  viii  Figure  6.5  I n d u s t r i a l d a t a and model f i t t o t h e Fe "*" and F e * p r o f i l e s f o r n o r m a l o p e r a t i o n 132 2  3  Figure  Figure Figure  6.6  6.7 6.8  I n d u s t r i a l d a t a and model f i t t o t h e temperature p r o f i l e f o r normal o p e r a t i o n  133  I n d u s t r i a l d a t a and model f i t t o t h e Zn and Pb p r o f i l e s f o r Run 1  137  I n d u s t r i a l d a t a and model f i t t o t h e Fe and F e p r o f i l e s f o r Run 1 . . . . 2+  Figure Figure Figure  6.9 6.10 6.11  I n d u s t r i a l d a t a and model f i t t o t h e t e m p e r a t u r e p r o f i l e f o r Run 1 . . . . . I n d u s t r i a l d a t a and model f i t t o t h e Zn and Pb p r o f i l e s f o r Run 2 . . . . .  Figure Figure  6.12 6.13 6.14  140  I n d u s t r i a l d a t a and model f i t t o t h e F e * and F e * p r o f i l e s f o r Run 2 . . . .  141  I n d u s t r i a l d a t a and model f i t t o t h e t e m p e r a t u r e p r o f i l e f o r Run 2  142  I n d u s t r i a l d a t a and model f i t t o t h e Zn and Pb p r o f i l e s f o r Run 3  143  I n d u s t r i a l d a t a and f i t t o t h e Fe ''" and F e p r o f i l e s f o r Run. 3  144 145  3  2  3 +  Figure  6.15  I n d u s t r i a l d a t a and f i t t o t h e t e m p e r a t u r e p r o f i l e f o r Run 3  Figure  6.16  Predicted  Figure  6.17  Figure  6.18  Figure  7.1  Figure  7.2  function F L P O C  Figure  7.3  . 139 .  2  Figure  138  3+  F  e >  ,y  oxygen u t i l i z a t i o n a s a of bath temperature  as a f u n c t i o n o f b a t h t e m p e r a t u r e as a f u n c t i o n o f b a t h t e m p e r a t u r e  The e f f e c t Zn p r o f i l e The e f f e c t  of  Fs>sr.  on t h e p r e d i c t e d  of  Fs»»t.  on t h e p r e d i c t e d  Pb p r o f i l e  .  149 150  156  The e f f e c t o f Fe * profile 2  148  157 Fs»»r.  on t h e p r e d i c t e d 158  F i g u r e 7.4 F i g u r e 7.5 F i g u r e 7.6  Pb The e f f e c t of r on the p r e d i c t e d Zn p r o f i l e . . ? Pb The e f f e c t of r on the p r e d i c t e d Pb p r o f i l e . . ? Pb The e f f e c t of r on the p r e d i c t e d Fe + profile . ? The e f f e c t of Dz„o/Ds> o on the p r e d i c t e d Zn p r o f i l e 2  F i g u r e 7.7 F i g u r e 7.8 F i g u r e 7.9  F i g u r e 7.11  The e f f e c t of D o / D p o on the p r e d i c t e d Pb p r o f i l e Z n  The  effect  of Ozno /Dpto a +  F i g u r e 7.14  163 165  on the  profile  166  Z  The e f f e c t  of V . on the slag Zn p r o f i l e  of V . on the slag predicted F e p r o f i l e ,  167  168  The e f f e c t  2 +  F i g u r e 7.13  162  b  The e f f e c t of D no/Dpbo on the p r e d i c t e d temperature p r o f i l e  predicted F i g u r e 7.12  161  to  predicted F e F i g u r e 7.10  160  of V . on the slag p r e d i c t e d Pb p r o f i l e The e f f e c t of V . on the slag p r e d i c t e d temperature p r o f i l e  170  The e f f e c t  171  172  F i g u r e 7.15  The e f f e c t of F on the p r e d i c t e d Zn p r o f i l e  173  F i g u r e 7.16  The e f f e c t of Foxy on the p r e d i c t e d Pb p r o f i l e  175  F i g u r e 7.17  The e f f e c t of F y on the predicted F e * p r o f i l e  176  F i g u r e 7.18  The e f f e c t of F on the p r e d i c t e d temperature p r o f i l e  177  F i g u r e 7.19  The e f f e c t of F e 0 on the p r e d i c t e d Zn p r o f i l e  178  O X 3 r  O X  2  oxy  2  3  X  Figure  7.20  The e f f e c t o f Fea0 on predicted Fe * profile  the  3  179  2  Figure  7.21  The  effect  predicted Figure  7.22  The  effect  predicted Figure  7.23  The  effect  predicted Figure  7.24  The  effect  predicted  of  D F  e  0  /  o3  D F  e  2  o  n  t  h  Zn p r o f i l e of Pb  '  D F  e  0  . . . . .  D F  e  203  o  n  t  h  D P e 0  Fe *  D P e  181 203  o  n  t  n  e  profile  2  of  ''  D F  e  0  ^  182  D  o P  180  e  profile  of  e  e  temperature  2  0  n  t  h  e  3  profile  183  XI LIST OF SYMBOLS b  ,s  B  ,sl 'j ' ,i  1-5  ,B  E  bubble  m  Boudouard Reaction Rate pree x p o n e n t i a l constant  k Pa  1  S  Char-Steam Reaction Rate pree x p o n e n t i a l contant  k Pa  1  3  Boudouard Reaction Rate  k Pa  1  S  A c t i v i t y of Species j  k Pa  C o n c e n t r a t i o n of Species j i n secondary bubble  kg mole m  C o n c e n t r a t i o n of s p e c i e s j i n s l a g C o n c e n t r a t i o n of s p e c i e s j a t bubble s l a g i n t e r f a c e Diffusivity  D  F  Surface area of secondary  of s p e c i e s j  1  1  1  S  1  1  kg mole m -3 kg mole m -3 m  2  S"  1  Constants A c t i v a t i o n energy Boudouard Reaction  kJ kg mole  A c t i v a t i o n energy Char-Steam  kJ kg mole  LPCE  F r a c t i o n of low-pressure coal entrained  HPCE  F r a c t i o n of high-pressure coal entrained  LPCC  F r a c t i o n of low-pressure c o a l combusted  -1  -1  xii  xi i i f  r a t e of r e a c t i o n  Sh^  Sherwood Number os s p e c i e s j -1  S^  Rate of Char-Steam Reaction  k Pa  u  Slag v e l o c i t y  m s  Activity coefficient  of s p e c i e s j  s 1  xi v  ACKNOWLEDGEMENTS  I would  l i k e to express my s i n c e r e  Richards f o r h i s u n t i r i n g support and project.  I  would  also  like  to  indebtedness to Dr. Greg  f r i e n d s h i p throughout t h i s thank Dr. G. W. Toop, E. T.  DeGroot and G. Heney f o r t h e i r guidance and stay  at  Cominco  Cominco.  The  Ltd., Trail,  co-operation  B.C.,  was  during  my  and f i n a n c i a l support of  greatly  f i n a n c i a l support of the Science C o u n c i l  assistance  appreciated.  The  of B.C. a l s o was g r e a t l y  appreciated.  Many thanks are a l s o his  encouragement  i n order  throughout  the  h e l p f u l e d i t o r i a l suggestions during  to Dr.  Keith  entire  p r o j e c t and h i s very  the w r i t i n g of t h i s t h e s i s .  I t i s impossible to assess the c o n t r i b u t i o n i n the and  o f f i c e have made.  that  the "boys"  Many thanks to Dave T r i p p , Bob Adamic,  Barry W i s k e l .  Finally, wife, she  Brimacombe f o r  I  would l i k e  to express  my deepest  thanks to my  Susan, f o r the many s a c r i f i c e s she has made and the support  has given me throughout t h i s  project.  1  CHAPTER 1 INTRODUCTION;  SLAGS AND SLAG PROCESSING  Slags p l a y a v i t a l r o l e functions chemical  of  slags  i n p y r o m e t a l l u r g i c a l processes.  include:  i n s u l a t i o n of  melts  the thermal from  the  The  i n s u l a t i o n of melts,  surrounding atmosphere,  r e s i s t i v e heat  sources i n m e l t i n g processes, and the r e f i n i n g of  metals  both  through  unwanted l i q u i d components. of  the  chemical  and s o l i d  they remain  their  T h i s s i t u a t i o n can the  be  under  and t h i r d l y ,  the p r e v a i l i n g  have  in  t h e o r e t i c a l l y and not  to  three  main f a c t o r s :  which s l a g s form i n i n d u s t r i a l of i n d u s t r i a l  economics.  determining  i n the p r o c e s s i n g  i n industry.  processes; secondly, the complexity  played  importance  attributed  circumstances  a b s o r p t i o n of  the supply of d e s i r e d  p o o r l y understood  exploited to t h e i r f u l l p o t e n t i a l  firstly,  physical  components and  Yet i n s p i t e of  metals,  and  the  s l a g systems,  The r o l e these  technological  state  factors of s l a g  m e t a l l u r g y i s i n t e r e s t i n g and worthy of f u r t h e r d i s c u s s i o n .  With  regard  to  the  first  f a c t o r , s l a g s g e n e r a l l y form i n  p y r o m e t a l l u r g i c a l processes through sources.  These a r e :  the concentrate made d u r i n g  c o n t r i b u t i o n s from three main  gangue m a t e r i a l ,  or ore;  the s m e l t i n g  which i s introduced with  flux additions, stage; and  which are d e l i b e r a t e l y  o x i d a t i o n of  the metal or  2 matte.  A f o u r t h and more minor c o n t r i b u t i o n  chemical and/or mechanical e r o s i o n Of these  four only  deliberate  addition  physiochemical cases a l r e a d y therefore,  one, the made  exists  slags  of  an a  have  been  trial  and  error  contributions.  has  second f a c t o r , s l a g  as  efforts.  a  a  consequence  behaviour  which  of  than  ranges  polymeric or network solutions the  not  from  forming  dominated by  factors that melts;  fluxes.  and the  as  has been  the p r a c t i c e of s l a g  has  acted  to f u r t h e r  This  complexity  which  include:  ionic  melts to that of  the  fact  any one s p e c i e s ;  i n d u s t r i a l environment - such  gangue m a t e r i a l ,  of  Historically,  science.  complexity,  several  the  that  done r e s u l t i n g i n a  s l a g s are  and the r e a l t i e s of  natural  variation in  a v a i l a b i l i t y and changing economics of  there has been l i t t l e  profound lack  two f a c t o r s d i s c u s s e d  Not  experimental work  of fundamental thermodynamic,  physiochemical and r e a c t i o n k i n e t i c data on m e t a l l u r g i c a l  The  slag  These f a c t o r s have a l l hindered s l a g i n v e s t i g a t i o n .  surprisingly, therefore,  the  consequence of the  perpetuate the t r a d i t i o n a l unimaginate approach. is  optimize  Optimization  promoted  m e t a l l u r g y through t r a d i t i o n r a t h e r  The  to  which i n the m a j o r i t y of  present  which  i s the r e s u l t of a  attempt  slag  v i a other  process, not through d e l i b e r a t e by  of r e f r a c t o r i e s where present.  flux addition,  in  properties  i s made through the  slags.  so f a r have helped t o keep s l a g  m e t a l l u r g y i n a r e l a t i v e l y unenlightened s t a t e .  The t h i r d and  3 debateably most important c o n t r i b u t o r to t h i s trend i s economics. Not s u r p r i s i n g l y , made  through  the  t h e i r study i s electro-slag specialty  i f there i s l i t t l e exploitation  limited.  remelting  tool  A  of  example  (ESR)  Due  g a i n to be  s l a g s the d r i v i n g f o r c e f o r  classic  process  steels.  obvious monetary  to  of  this  which produces this  expensive  interest  there  c o n s i d e r a b l y more physiochemical data a v a i l a b l e on the - CaO  ternary  more p r e v a l e n t have  acted,  on which  ESR  s l a g s are based  s l a g systems. and  continue  It to  i s these  have  been  shown  is  CaF2-Al 0 2  3  industrially  three f a c t o r s which  a c t , to slow the e x p l o i t a t i o n of  s l a g s i n the i n d u s t r i a l work p l a c e . interest  than on  i s the  both  Recently,  however, s i g n s of  on the academic and  industrial  f r o n t s i n the s l a g c l e a n i n g p r o c e s s .  1.1  Slag P r o c e s s i n g  An  inherent  pyrometallurgical  problem processes  associated is  that  metal values a t the end of the p r o c e s s . slag  in  two  forms:  i s dissolved  chemical  potential;  i n t o the s l a g as and  entrainment.  d i s c a r d e d with  slags  in  unavoidably c o n t a i n  The metal appears  i n the  one, as s o l u t i o n or chemical l o s s e s i n which  the metal  mechanical  they  with  the s l a g  second, In and  to await an economic means of  as  many cases,  a result physical  of an  existing  losses  these metal  due  to  values are  l o s t , or stock p i l e d , with the s l a g recovery.  The d r i v i n g  the development of an economic means of r e c o v e r y may  force for  arise  from  4  s e v e r a l sources: contained metal decrease  in  f o r example, an brought  i n c r e a s e i n the p r i c e of the  about by an  increase i n  the grade of ore bodies, or the development of a new  technology r e q u i r i n g s l a g treatment process.  A good  processes use  as an  i n t e g r a l part  f o r the treatment  of lead c o n c e n t r a t e s .  continuous m u l t i - s t a g e  These  s i n g l e - v e s s e l r e a c t o r s and  t h e r e f o r e r e q u i r e improved methods of s l a g said  of the  example of the l a t t e r are the Q.S.L. and f l a s h  s m e l t i n g processes  can be  demand and/or a  treatment.  The same  f o r developments i n the s m e l t i n g of t i n , copper and  nickel.  1.1.1  Slag C l e a n i n g  H i s t o r i c a l l y , s l a g p r o c e s s i n g , when secondary  step  o u t s i d e the primary  mainly c o n s i s t s of s l a g c l e a n i n g . to  those  slags.  processes  To date  problem. reductive reducing  The  there have most  processes, agent,  concerned  such  values are then recovered example, i n  the z i n c  molten lead b l a s t  The term  with  predominant  as  been a  slag cleaning refers  the removal of metals  of  the  coal,  has  flow c h a r t of the smelter and  been three  involve  practiced,  main approaches these,  treatment  from  to t h i s  pyrometallurgical of  slag  with  n a t u r a l gas or p y r i t e s .  i n m e t a l l i c form or as s u l p h i d e s .  s l a g fuming process, c o a l i s i n j e c t e d  a  Metal For into  furnace s l a g to produce a m e t a l l i c vapour which  i s then o x i d i z e d and c o l l e c t e d  f o r subsequent  treatment.  5 The  second  facilitate is  c l e a n i n g technique  s e p a r a t i o n based on d e n s i t y d i f f e r e n c e s .  particularly  effective  contains a large example, This  for  amount  the  technique  treatment of  in  of  those  removal  of  often  used  is  the s l a g .  the K i v c e t  process  t h i s process relatively  zinc  In  circuit. process on  the  entrained  metal, f o r  in  conjunction  with  reductive  f a c t , a combination of s e t t l i n g i n the  and  developmental stage f o r  the treatment  of lead c o n c e n t r a t e s .  and  lead  bearing  slags  electric  arc  are  furnace  reacted  In in a  with coke to permit  reduction.  grinding  m e t a l l i c or  where the s l a g  copper d r o p l e t s i n copper s l a g s .  t h i r d c l e a n i n g process  involves  T h i s method  for  quiescent  both s e t t l i n g and  instances  mechanically  r e d u c t i v e treatment were a p p l i e d  The  ' s e t t l i n g ' employs g r a v i t y to  the  sulphide There  cold  s l a g followed  particles  are  i n comparison to particular  i s m i l l i n g and  in  a  floatation.  by s e p a r a t i o n of  standard  both advantages and  These  any  rougher-cleaner  disadvantages to t h i s  the p y r o m e t a l l u r g i c a l  application.  This  will  routes  depending  not be  discussed  f u r t h e r as they are beyond the scope of t h i s t h e s i s .  The  p o t e n t i a l f o r improvement i n the  appears to  be c o n s i d e r a b l e .  The  area  and  yet  i s poised  slag cleaning  f a c t o r s a l l u d e d to p r e v i o u s l y  have c o n t r i b u t e d to c r e a t e a technology which i s backward s t a t e  of  in a  relatively  to p l a y a c r i t i c a l r o l e i n the  6 newer non-ferrous  processes.  A good example of t h i s i s the  s l a g fuming process which i s o n l y j u s t beginning to be mechanistically. knowledge describe  Thermodynamic data,  of  process  k i n e t i c s have  the  process  in  detail  zinc  understood  physiochemical data and a been  for  brought  to  first  time.  the  bear to l a , b  The  r e s u l t s of t h i s a n a l y s i s could p o t e n t i a l l y have a great i n f l u e n c e on s l a g p r o c e s s i n g i n g e n e r a l .  The a p p l i c a t i o n  of high-pressure c o a l i n j e c t i o n to the  s l a g fuming process, the direct  result  of  the  focus  "kinetic"  However, before proceeding, to review and  1.2  the z i n c  fuming process,  order to  the  as a  process.  illustrative  in general, i t s history,  form,  whereas The  molten s l a g  recover contained z i n c and i s present  lead  process  r e c t a n g u l a r water-jacketed  may  of  i t i s both necessary and  p r e v a l e n t metal,  m e t a l l i c forms.  by 2.5m  conception  follows  i n the f u t u r e of s l a g p r o c e s s i n g .  zinc slag  reductively in  oxidic  thesis,  Zinc S l a g Fuming Process  In the  the more  this  s l a g fuming process  i t s potential role  The  of  zinc  usually  dissolved appears  i s c a r r i e d out  in  is  lead.  i n both o x i d i c  on a  diagram i n F i g . 1.1.  T y p i c a l l y batches  and  batch b a s i s i n  be made up e n t i r e l y of l i q u i d s l a g or a combination  and s o l i d m a t e r i a l s .  Zinc,  the s l a g i n  furnaces t h a t are, on average,  wide; see the schematic  treated  6m  long  The  charge  of  liquid  c o n t a i n i n g 50 tonnes are  C.CO — C 0 Zn, +1/2 0 — Z n Q (g) 2 (s) 2  %  o  Tertiary air (unregulated)  Primary air 05-33Nm /s Cool: I-1-5 kq/s 3  Water-jacketed Secondary air 3 3 - 7 5 Nm /s  Walls  3  Punching Valve  S  &  Tuyere Slag  Figure 1 . 1  Fuming  Process  Schematic diagram showing the furnace i n c r o s s - s e c t i o n and the chemical reactions occurring i n the process  8 processed a t  a time.  A  r e d u c t a n t , u s u a l l y c o a l , p u l v e r i z e d to  approximately 80%-200 mesh (B.S.S.), i s i n j e c t e d through a two  row of  long s i d e s .  i n t o the furnace  tuyeres l o c a t e d near the bottom of each of the The c o a l i s i n j e c t e d  r a t e s ranging from 50 - 75 kg/min.  i n t o the tuyeres a t o v e r a l l  conveyed  by "primary a i r " at 3  t y p i c a l o v e r a l l r a t e s of approximately 30 Nm  /min.  The  main or  "secondary b l a s t " e n t e r s the tuyeres behind the c o a l / a i r at o v e r a l l  r a t e s ranging  ambient temperature. variations example, about  in  In  furnace  from  300 -  some  operations  geometry  primary and secondary  200 Nm  3  /min  400 Nm  and blast  and secondary  /min  3  however,  operating  mixture  u s u a l l y at there are  practice.  flow r a t e s may  For  be equal at  b l a s t preheats of up to  700°C  have been used. Removal of  z i n c from the bath i s e f f e c t e d through r e d u c t i o n  of d i s s o l v e d z i n c oxide to m e t a l l i c z i n c vapour v i a the  s u r f a c e of  the bath.  lead e x i t s the bath, be i t c l e a r as  However, the vapour  as metal,  oxide or  form i n which  sulphide i s less  these compounds are present predominantly as l i q u i d s a t  s l a g fuming temperatures.  The c h a r a c t e r i z a t i o n  from the  bath i s  discussed  i n the s e c t i o n s that  and  any  of lead  removal  an important aspect of t h i s t h e s i s and w i l l  A f t e r e x i t i n g the s u r f a c e vapour  which then e x i t s  lead  bearing  " t e r t i a r y " or leakage a i r .  be  follow.  of  the  species  bath are  T h i s mixture of  the  metallic  zinc  then r e o x i d i z e d metal oxides  by  (fume),  9 combusted c o a l  and t e r t i a r y  and  i s collected  the  fume  processing. results  a i r i s then drawn up through a f l u e in  The exothermic  i n extremely  hot  off-gases.  some  An  attempt  i s made to  operations,  to  treat  however,  lead  i t has  blast  furnace  been  applied  s u c c e s s f u l l y t o the treatment of copper r e v e r b e r a t o r y only s i g n i f i c a n t and  difference  lead c o n c e n t r a t i o n s :  lead b l a s t  in  slags.  The  t h i s case i s i n the i n i t i a l  zinc  13-18 wt% z i n c and 1-3 wt% lead  furnace s l a g s ,  8 wt%  z i n c and  percent lead f o r the copper r e v e r b e r a t o r y then fumed  down to  0.02%  at  approximately 3 tapping.  tend t o  In both this  hours  f l u o r ine.  cases lead  point.  per kg of z i n c fumed.  be h i g h e r , near 100%.  such  as  These s l a g s are  contents are t y p i c a l l y  Complete  including  fume from lead b l a s t furnace species  l e s s than one weight  slags.  30  sulphur,  fuming  minutes  The r e c o v e r y of z i n c i s g e n e r a l l y  coal required  f o r the  between 1.5 and 2.5% z i n c a t which p o i n t the  furnace i s tapped. around  reactions  the baghouse.  fuming i s normally used At  f o r subsequent  heat by p a s s i n g the gases through a  steam b o i l e r p r i o r to e n t e r i n g  slags.  baghouse  nature of these o x i d a t i o n  recoupe some of t h i s s e n s i b l e  Slag  a  cycles  take  f o r charging and  85-90% with 1-2 kg of  In c o n t r a s t ,  lead  recoveries  In a d d i t i o n to z i n c and l e a d , the  slag  contains  t i n , cadmium,  traces  of v o l a t i l e  indium, c h l o r i n e and  10 Under i d e a l  c o n d i t i o n s a t some o p e r a t i o n s ,  i s broken down i n t o with charging an  initial  two periods  and tapping  "heating  In the heating  i n order  to approach  mixture coal. and  the furnace.  period"  fuming".  providing  distinct  the  highest  tend  increases  prevailing  in  the furnace.  an  heating  of  a  period  of "proper  to  of the a i r / c o a l  p o s s i b l e heat input per u n i t of bath temperature  rises,  zinc  be low, and the bath f e r r i c  iron  reflecting  the  oxidizing  conditions  There are s e v e r a l reasons f o r having  period.  s e n s i b l e heat  These may i n c l u d e :  the b u i l d up of a  which i s l a t e r consumed throughout the  fuming p e r i o d and/or, the a b i l i t y to or l a d l e s k u l l .  by  p e r i o d , the c o a l - t o - a i r r a t i o i s reduced  concentration  reserve  those a s s o c i a t e d  s t o i c h i o m e t r i c combustion  fuming r a t e s  initial  from  These may be d e s c r i b e d as  followed  Throughout t h i s p e r i o d , the  lead  the fuming c y c l e  The heating  period  process  solid  crushed s l a g  i s g e n e r a l l y terminated  when  o the  bath  onset of  temperature approaches approximately the fuming  period  c o a l - t o - a i r r a t i o causing reducing.  This period  1325  C .  The  i s i n i t i a t e d by an i n c r e a s i n g i n the  conditions  in  the  i s characterized  furnace  to become  by a steady d e c l i n e i n  bath temperature, high z i n c and lead fuming r a t e s , and a decrease in the bath c o n c e n t r a t i o n At other not p r a c t i c e d .  operations  of f e r r i c  however, t h i s two-stage fuming c y c l e i s  The e n t i r e fuming  coal-to-air ratio.  At  iron.  still  d i f f e r e n t approach i s taken.  cycle  other Instead  is  run  at  a constant  operations,  a significantly  of a  type  batch  operation,  11 slag  fuming  is  carried  out  on  a  continuous  g e o m e t r i c a l l y s m a l l e r furnace using f u e l o i l as the  1.2.1  basis  in  a  reductant.  History  The development of the z i n c s l a g fuming process the development  i s rooted i n  of the s i n t e r - l e a d b l a s t furnace process  s m e l t i n g of lead s u l p h i d e ores i n  the 1870's.  The  for the  presence  of  s i g n i f i c a n t amounts of z i n c s u l p h i d e i n a s s o c i a t i o n with the lead s u l p h i d e i n the concentrate meant that the process separation  between  the  two.  This  was  advantage of the d i f f e r e n c e i n s t a b i l i t y z i n c oxide.  By  c o n t r o l l i n g the  had  achieved  by  between lead  oxygen p o t e n t i a l  to e f f e c t taking  oxide  i n the  and  blast  furnace  i t i s p o s s i b l e to produce lead while h o l d i n g the m a j o r i t y  of  z i n c as  the  was slag  oxide  stock p i l e d and dumps  in  smelters the  containing  industrial setting  the s l a g phase.  up  f o r the  to  world 20%  zinc.  i n c e n t i v e and  technical expertise.  The  economic i n c e n t i v e was  the demand and zinc  for zinc  continued was  What was  through  realized.  immediately.  over  of  still  This a  process  required,  provided by  The  the  that could the economic  a sharp  increase in  of World War  the i n d u s t r i a l  technical  provided  was  which followed the outbreak the 1920's as  slag  began to accumulate  zinc.  emergence  recover t h i s  I n i t i a l l y , this  development  I,  p o t e n t i a l of began  almost  12 Some of lead  the e a r l i e s t  blast  furnace  work on  slags  was  the e x t r a c t i o n  carried  C o r p o r a t i o n a t Cockle Creek between 1906 experiments  in  molten s l a g . the s l a g .  1906  This resulted  A second  c o a l - a i r mixture patenting. 1908.  The  Other  treatment  appeared  In of  set  and  and  blowing  of experiments to be  of  was  i s s u e d to F.H.  experiments  included:  to be necessary  was  i n any  lead to the  i n s t a l l a t i o n of the second Smelting Company,  Trail,  slightly different. 3.66m ( 1 2 f t )  out using a  and  nodules.  slightly used  wider at newer  waste-heat b o i l e r .  The  only  furnaces  application.  application  Mont."^, and  to the  furnace by the C o n s o l i d a t e d Mining B.C.  i n 1930.  These two  furnace was  3.5m  whereas the  2.44m ( 8 f t ) by  Trail  burners furnace  ( 1 0 f t ) , s i g n i f i c a n t l y longer at  double-inlet  tuyeres,  from these  and  i n the  7.9m  incorporated a  d i f f e r e n c e s , the  were e s s e n t i a l l y the same and were both used  and  furnaces were  a tuyere d e s i g n borrowed from the  Apart  a blast  furnace being blown i n at the  The East Helena  used  McKay i n  limestone, and  water-jacketed  industrial  first  warrant  the r e v e r b e r a t o r y furnace  that  in c o a l - f i r e d r e v e r b e r a t o r y furnaces,  (20ft),  r a p i d f r e e z i n g of  the 1920's, i n v e s t i g a t i o n i n t o the commercial  the process  initial  a i r through  Evans and P.A.  Anaconda Copper Mining Company a t East Helena,  was  The  carried  of s l a g b r i q u e t t e s and  significance  from  Sulphide  s u c c e s s f u l enough to  patent was  any  the  1916.  i n some fuming and  proved  treatment  by  compressed  of s l a g by f i r i n g with coke and  furnace type result  involved  out  of z i n c  furnaces  treatment  of  13 solid  and  dumps.  liquid  material  As the dump  supply  s h i f t e d to the treatment  Since the  i n order to recover z i n c from of  zinc  of l i q u i d  1930's, there  exhausted,  lead b l a s t  furnace  have been l i t t l e  changes i n the process  despite i t s  lead smelter throughout  the world.  included:  was  adoption  slag  they were slag.  or no s i g n i f i c a n t  in virtually  every  I n d i v i d u a l m o d i f i c a t i o n s have  the adoption of secondary  b l a s t preheat a t the Broken 4  Hill  Associated  Smelters  of  fuming i n B u l g a r i a u t i l i z i n g  Port P i r i e  in  1967 ; continuous 5  f u e l o i l i n s t e a d of c o a l  ; and the  use of n a t u r a l gas as a reductant i n a Russian process.** As mentioned s m e l t i n g of treatment. processes  lead concentrates These  newer  technologies  r e q u i r e improved  technologies  the  example, n a t u r a l r e d u c t i v e zone. the  the  a l l employ  f o r the  methods of s l a g  continuous  smelting  i n c o r p o r a t i n g r e d u c t i v e s l a g c l e a n i n g stages w i t h i n the  main stream of  to  previously,  slag  process.  gas i s  In  i n j e c t e d through  In the K i v c e t surface  the  pilot  relatively  process f o r  submerged tuyeres i n a  process, coke  in a  QSL  a d d i t i o n s are made  quiescent e l e c t r i c arc  holding furnace.  Both of these  understanding  the k i n e t i c s of o x i d i c z i n c and lead r e d u c t i o n ,  of  processes r e q u i r e  and m e t a l l i c lead removal from these s l a g s i n be  economically  successful  z i n c s l a g fuming process metals  processes.  i n the  near  a fundamental  order f o r them to  The r o l e played by the  future  of the non-ferrous  i n d u s t r y must be t h a t of a t e s t i n g arena.  I t must be used  14 to i n v e s t i g a t e  k i n e t i c phenomena e s s e n t i a l t o the success of the  newer s m e l t i n g t e c h n o l o g i e s .  In  reflection,  practice,  the  the  lack  non-universal  of  consistency  adoption  in  of process  zinc  fuming  improvements,  such as b l a s t preheat and continuous o p e r a t i o n , and the f a c t the process point  to  remains e s s e n t i a l l y a  traditional  improvement.  The  unchanged s i n c e the 1930's, a l l  optimization  proposed  that  slag  approach  to  process  c l e a n i n g stages i n the newer  s m e l t i n g t e c h n o l o g i e s a l s o suggest the c o n t i n u a t i o n of t h i s trend in  thinking.  approaches reduction  In  taken  both  suggest  kinetic  a  QSL lack  phenomena.  e l u c i d a t i o n of these to the  the  and  Kivcet  of  understanding  The  of  the slag  economic i n c e n t i v e f o r the  phenomena now e x i s t s as  success of these p r o c e s s e s .  processes,  they are paramount  High-pressure c o a l  injection  f o l l o w s from an understanding of k i n e t i c s  and could  prove to be  of c o n s i d e r a b l e b e n e f i t to s l a g treatment  technology.  Taken one  step f u r t h e r ,  the phenomena  upon i n t h i s t h e s i s help forge active tools  i n metals  d e s c r i b e d elsewhere^" '^ 3  the way  extraction.  to the  use of  and b u i l t s l a g s as  15 CHAPTER II  LITERATURE REVIEW  This t h e s i s d e a l s with the a p p l i c a t i o n of high-pressure i n j e c t i o n to the i n d u s t r i a l z i n c s l a g to  outline  systems,  some  of  experimental  the  options  available  techniques  and  necessary to review .the l i t e r a t u r e . are presented  2.1  in this  fuming process.  data  coal  In order  for coal  injection  analysis,  i t is  The r e s u l t s of these  reviews  chapter.  P u l v e r i z e d Coal Transport  7-10 A g e n e r a l review of the l i t e r a t u r e are s e v e r a l  p r e c a u t i o n s which must be observed  transporting  pulverized  concentrations coal e x p l o s i v e mixture,  coal.  Firstly,  dust suspended extreme  caution  The  p r e c a u t i o n i s d i r e c t l y concerned  and  There  is  therefore strong  c o n d i t i o n s , such with l i t t l e can  be  charge  of  work  must  ensuring  coal  that  as d u r i n g  or no moisture  generated. can r e s u l t  The  because  in  certain  be  exercised  in i t s  areas are w e l l vented and c l e a n .  direct  evidence  when h a n d l i n g and  in a i r constitutes a highly  handling, second  i n d i c a t e s that there  with the t r a n s p o r t of  applicability  to  suggest  to t h i s  project.  under  certain  that  pneumatic t r a n s p o r t i n p l a s t i c present,  a significant  static  random u n c o n t r o l l e d grounding  i n i g n i t i o n of the c o a l / a i r mixture.  pipes charge  of t h i s  Since the  16 conditions  leading  m e t a l l i c pipes t r a n s p o r t as  to  this  phenomena are not w e l l documented,  and/or grounding  a general  precaution.  maintain proper a e r a t i o n  to  transporting  coal.  result  must be  pulverized  provided f o r pneumatic  Finally,  achieve  i t i s e s s e n t i a l to  fluid-like  behaviour when  S t i c k y s o l i d - l i k e behaviour can  from lack of a e r a t i o n as w e l l as from other  example,  high  moisture  contents  and/or  a  factors:  for  b u i l d up of s t a t i c  s u r f a c e charge.  2.1.1  Pneumatic  Conveying of M a t e r i a l s  Pneumatic historically  conveying into  gravity-feed  a  broad  systems,  systems,  light-phase  systems,  low-pressure  systems  have  range  of  low-velocity systems, systems,  been  classified  categories systems,  dense-phase  including:  high-velocity systems,  medium-pressure  vacuum  systems,  high-  7 8 9  pressure systems,  etc. ' '  have been used l o o s e l y types  of  In  classification  the  system  to  classify  engineering has  been  different  literature, developed.  a For  dense phase systems are considered to be those with mass  flow r a t i o s of s o l i d systems, frequently  have  below  to gas i n the hundreds;  ratios  being  classifications operating  manufacturers  equipment.  quantitative example,  by  In c e r t a i n i n s t a n c e s these terms  the  include:  below  about  division  one  between  light  hundred, the  phase or lean with  two.  eighty  Additional  vacuum systems, considered to be those  atmospheric  pressure;  low-pressure  systems,  17 between  atmospheric  and  82.73  systems, up to 310.23 kPa up  to  861.75  kPa  (45  (125  kPa  (12 p s i g ) ;  p s i g ) ; and  psig).  medium-pressure  h i g h - p r e s s u r e systems,  Unfortunately,  there are no  u n i v e r s a l l y adopted standards f o r c l a s s i f y i n g these is  clear,  however,  conveying 7 types  that  for  gas-solids  systems.  mixtures  It  pneumatic  systems e s s e n t i a l l y can be broken down i n t o three main  :  material-into-air,  air-mixing  and  air-into-material  systems. 2.1.1.1  Material-Into-Air  The systems  material-into-air in  which m a t e r i a l  Systems  systems enters a  are  classified  stream of  as  those  a i r under  either  negative or low pressure or, i s induced i n t o a stream This c l a s s i f i c a t i o n systems mentioned  by vacuum.  i n c l u d e s the vacuum systems and low-pressure  earlier.  Table 2.1 presents a  summary of some  of the advantages and disadvantages of t h i s type of system.  2.1.1.2  Air-Mixing  In the  Systems  a i r - m i x i n g systems  a i r are i n t i m a t e l y mixed conveying  line.  possible.  These  and  entering a  systems resemble the f i r s t  type except  and,  systems  The feeders used i n c l u d e :  to be conveyed  i n a s p e c i a l feeder p r i o r to  These  that a denser stream,  the m a t e r i a l  feeding  into  higher  p r e s s u r e s are  i n c l u d e the medium pressure systems. r o t a r y feeders,  F u l l e r Kinyon  pumps  18  TABLE 2.1 Classification of Pneumatic Conveyors Cluificatto  Material-into-air  Disadvantages  Advantages 1. Handles wides range of taterials,including irregular shapes.  1. Uses lower material-to-air ratios than other systems. 2. Requires larger equipment than other systeas-air movers, pipelines, dust filters, etc.  Positive-pressure  Negative-pressure  1. Delivers material through a single pipeline to several discharge points.  1. Requires an airlock feeder and blowback vent filter at each material entry point.  2. Uses smaller pipelines than comparable vacuum systems.  2. Requires large dust filter at each material discharge point.  3. Air leakage is outward so that moisture can not be drawn into equipment.  3. Transport unloading requires use of fixed or portable airlock feeder installation.  1. Transports easily unloaded using pickup hoppers or nozzles.  1. Material can be delivered only to a single discharge point.  2. Material can enter a single pipeline from several sources of supply without venting  2. Dust filter and airlock discharger required at the discharge point.  3. Material can enter line using airlock feeder, controlled-feed tank, or pickup hopper.  3.  Moisture and outside air can be drawn into equipment.  4.  Requires larger piping and equipment than positive-pressure systems, due to lower density air.  5. Air mover and receiver-filter requires location stop silos or building roof.  Negative-pressure (vacuum)with dustreturn loop  1. Delivers material to several discharge points.  1. Requires a collector and an airlock discharger at each discharge point.  2. Dust is returned to a single, conveniently 2. Requires diverter valves in the dust return and conveying lines at all but one dislocated dust filter for re-entry into concharge point. veying line or silo.  19  Combination vacuum/ pressure  Closed-loop, positive or negative pressure  1. See above for respective portions of syste 1. Permits pickup of materia) froi transvacuui or pressure side. ports by vacuui and simultaneous discharge to each of several discharge points 2. Requires larger-capacity and horsepower by pressure. air eover than for the vacuui or positivepressure system. 2. Dust from vacuut-side receiver is delivered into conveying line. 3. If air eover breaks down, two plant operations are affected - unloading and reclaiming. 1. Periits use of inert gas for conveying, with minimum uke-up requirement.  1. Same as for combination vacuum-pressure system.  2. Permits re-use of conveying air where air is dried or filtered to be free of contamination. 3.  Air-into-Mftriai  Eliminates the use of diverter valves on dust-return line at each discharge point.  1. Uses highest possible aaterial-to-air ratio compared to other systems.  1. Operation is intermittent.  2. Requires smaller equipment than other systems - air movers, pipelines, dust filters, etc.  2. High pressure systems (over IS psig) require ASHE-Code-constructed vessels.  Low velocity, dense mixture permits handling abrasive and friable materials.  4.  High-pressure units and systems permit delivery through very long pipelines.  4. A dust filter is required for venting surge hopper and blow tank.  5.  Delivers material to several discharge points using a single pipeline.  5. Haterial must be delivered to blow tanks at higher than pneuiatic conveying rates, due to 1iiited filling time between discharge cycles.  6. Each batch can be weighed before being conveyed. Free-feed blow tank  3. Surge hopper is reuired for rapid filling if auxiliary feed capacity is limited.  3.  1. Bottom-discharge units can handle lumpy, 1. Haterial-to-air ratio is variable - high non-fluidizable and fluidizable materials. at start and finish of each cycle. 2. Bottom-discharge units can be emptied 2. Top-discharge units leave residue in bottom of tank that may cause contamination completely when handling sanitary materials. of material.  20  Controlled-feed blov  1. Material-to-air ratio of discharge is uni- 1. Use is liaited to fluidizable, powdered fora. or aixed-granular aaterials. 2. Conveying-line velocity can be reduced to the slug flow liait. 3. Booster nozzles aay be installed in the conveying line to aaintain dense, low velocity flow.  Air-aixiaf  1. Haterial-to-air ratio is high, but not as 1. Use is liaited to fluidizable, powdered or aixed-granular aaterials. high as in air-into-aaterial systems. 2. Conveying is continuous.  2. Can not handle friable aaterial.  3. Delivers aaterial to several discharge points through a single pipeline.  3. Haterial must be delivered by aetered auxiliary conveyors.  4.  Feed-screw into air nozzles  High pressure peraits delivery through long, saall-diaaeter pipelines  4.  Feed hopper aust be level-controlled and vented to dust filters.  5.  Feed hoppers aust be aaintained full when handling abrasive aaterial. Subject to erosion and loss of capacity when handling abrasive aaterial.  1. Requires saaller auxiliary conveyors than blow tanks. 2.  Requires lower headrooa than blow tanks.  2.  Requires skilled aaintenance, as for high-grade aachinery. Must run fully loaded when handling abrasive aaterial - wear increases when idling.  Air-swept, double-entry rotary feeder  i.  Can be aade with cutting vane to handle tacky aaterial such as sugar or detergents.  4.  Requires high-prssure, sliding-vane or reciprocating air coapressor.  5.  Coapressors require cooling water. Oil separators aust be installed ahead of air nozzles.  1. Pressure liait is 20 psig. requiring lowvoluae, positive-displaceaent blowers in tandea.  2.  Capacity varies with head of aaterial in feed hopper.  21 and  any  other  type  of  pump  capable  of  delivering  m a t e r i a l - a i r mixture i n t o a p r e s s u r i z e d a i r stream. merits of t h i s system are summarized  2.1.1.3  Air-Into-Material  The  i n Table 2.1.  systems  are  classified  systems i n which a i r enters a mass of m a t e r i a l to the high-pressure  which are more g e n e r a l l y  The r e l a t i v e  Systems  air-into-material  These include  a dense  as  initiate  those flow.  systems and dense phase systems  termed  as  "blow-tank"  systems.  The  advantages and disadvantages of t h i s type of system are d e s c r i b e d i n Table 2.1.  2.1.1.4  S e l e c t i o n of System  The type of  system  economics, a p p l i c a t i o n , and the type of classification  selected the d e s i r e d  m a t e r i a l to is  narrowed  project,  a  number  on  volume and  be conveyed. down  capable of conveying p u l v e r i z e d this  depends  of  If  such  f a c t o r s as  mass flow r a t e s f o r example, the  to i n c l u d e only those systems  c o a l , as  would be  acceptable  systems  required for decreases.  U n f o r t u n a t e l y , no s i n g l e best system i s obvious.  2.1.2  Non-Pneumatic  Transport  In a d d i t i o n to a i r , water has a l s o been used as  a conveying  22 medium  to i n j e c t p u l v e r i z e d c o a l s u c c e s s f u l l y i n t o an  furnace.^  There are  coal-water s l u r r i e s : oxygen  injection,  pressures.  reduction and  the  in explosion  possibility  slurries  and  of  coal-steam  Summary:  achieving  be e s t a b l i s h e d before  the  applied  system  addressed  other a l t e r n a t i v e s  mixtures  aid  in  i n Chapter  t h a t design  information  The  conceptual  3  in  the  idea f o r high-pressure  from the work of R i c h a r d s . "*"  literature  be  T h i s endeavour w i l l  be  coal injection  l a t e r treatment by Richards,  Richards  minimize will  l a t e r than 1983 detailed  repetition,  material  review of r e l e v a n t  in  more  pre-1983  original  to t h i s t h e s i s .  previously  only r e c e i v e c u r s o r y treatment. w i l l be covered  his  follows  Brimacombe and Toop"'"^  are s t r o n g l y recommended as p r e l i m i n a r y reading  To  have to can  As a r e s u l t ,  a  the  process.  IV.  Zinc Slag Fuming Process  work"*" and  which might  criterion will  selection.  The  directly  higher  Pneumatic Conveying  In summary, i t i s evident  to  injecting  hazard, no gaseous  f u t u r e a p p l i c a t i o n i n the z i n c s l a g fuming  2.1.3  2.2  advantages to  Furthermore, t h i s b r i n g s to l i g h t  such as c o a l - o i l find  s e v e r a l obvious  iron blast  by  Relevant m a t e r i a l  detail.  material  covered  For the  a more  reader  is  23 r e f e r r e d to Richard's work.  2.2.1  S t u d i e s and M o d e l l i n g  Soon a f t e r of  thought  slag. was  the f i r s t  emerged on  The  first  furnaces were c o n s t r u c t e d two s c h o o l s  the mechanism  of z i n c  from  s c h o o l p o s t u l a t e d that c o a l e n t e r i n g the furnace  immediately combusted  mixture.  of r e d u c t i o n  The carbon  to  a  carbon  monoxide i n  monoxide-carbon d i o x i d e  t h i s gas stream then acted to  reduce  the d i s s o l v e d z i n c oxide and produce m e t a l l i c z i n c vapour 12 13 as the r e d u c i n g gas ascended through the bath. ' In c o n t r a s t the second s c h o o l p o s t u l a t e d that p a r t i c l e s of c o a l i n c o n t a c t 14 with the  slag act  as the s i g h t f o r r e d u c t i o n .  Surprisingly,  these d i f f e r e n t concepts remain the source of debate 2.2.1.1  today.  E q u i l i b r i u m Models  Historically, substantial  the  first  support i n 1954  school  from the  of  thought  classical  received  study of B e l l ,  15 Turn and P e t e r s . on mass  In t h e i r  balances and  investigation, a  the assumption  simple, model based  of i n t e r n a l e q u i l i b r i u m  developed to estimate the a c t i v i t y of z i n c oxide i n the three i n d u s t r i a l  runs d u r i n g which  a f u n c t i o n of bath authors  found  o v e r a l l furnace  zinc  that heat  model  balance.  s l a g for  fuming r a t e s were measured as  concentration.  their  was  With  accounted The  model  this  data, the  q u i t e w e l l f o r the also  was  used to  24 evaluate  the  effect  These i n c l u d e d : p r e h e a t i n g the  of  the i n j e c t i o n of n a t u r a l gas as a  of  evidence  iron to  shortcomings,  oxides  and  support  the  discrepancies.  by  observed  in  significance  and  In one  the  lack  as the e x c l u s i o n of the of  indirect  for observations  model  practice. because  it  as  the  with o n l y minor not the  reductant,  were  significantly  This  observation  alludes  experimental  of e q u i l i b r i u m ,  instance however, t h i s was  fuming with n a t u r a l gas  predicted  such  the fundamental assumption  the model reasonably accounted  During  reductant  blast.  Despite obvious role  v a r i o u s changes i n o p e r a t i n g p r a c t i c e .  fuming r a t e s  higher than is  case.  those  of c o n s i d e r a b l e  to the importance  of the  role  coal p a r t i c l e s play in slag reduction.  A d d i t i o n a l support build  in  1956  f o r the e q u i l i b r i u m approach continued to  when K e l l o g g conducted  a  " n o - c o a l " t e s t on No.  2  14 s l a g fuming furnace at Cominco L t d . , T r a i l , the c o a l  supply to  the furnace  f i v e minutes d u r i n g which temperature  were  that there was  recorded.  was  BC.  In t h i s  test  i n t e r r u p t e d f o r a p e r i o d of  time changes  in slag  composition  The a n a l y s i s of t h i s data  s u f f i c i e n t gas stream-slag  interface for  and  suggested i t to be  the "seat of the fuming r e a c t i o n " . Based on work  the r e s u l t s of t h i s experiment  by B e l l et a l ,  K e l l o g g developed  a  and  on the previous  comprehensive model of  25  the  zinc  slag  fuming  process  in  thermodynamics of the i r o n oxides as sulphur  were  balance slag  included.  well  the  water  cooled  o c c u r r i n g above the bath. lead,  sulphur  as  t h i s model, the  that  of  PbO and  In a d d i t i o n , the o v e r a l l furnace  was improved to i n c o r p o r a t e the  on  iron,  1 9 6 7 . I n  f r e e z i n g of  w a l l s and bottom, and the r e a c t i o n s  As  and  m e l t i n g and  heat  a result,  temperature  the r a t e s could  be  of change of predicted  in  a d d i t i o n to t h a t of z i n c .  The  model was f i t t e d  slag a c t i v i t y  to average i n d u s t r i a l data by a d j u s t i n g  c o e f f i c i e n t s and h e a t - t r a n s f e r c o e f f i c i e n t s .  This  p o t e n t i a l l y could have r a i s e d concern but the r e s u l t i n g values of the c o e f f i c i e n t s were reported to be w i t h i n expected  The study  Kellogg"''*' model represented  of  the  conclusively  zinc  that  quantitatively  to  slag the  fuming  account  for  a s i g n i f i c a n t advance i n the process.  assumption  limits.  It established  of e q u i l i b r i u m could be used the  behaviour  of  zinc  and  q u a l i t a t i v e l y to account f o r the behaviour of i r o n , lead and bath temperature.  In the e a r l y 1970's the K e l l o g g model was modified  by Grant  17 and  Barnett  Australia.  a t the Broken H i l l The heat balance  A s s o c i a t e d Smelters,  the handling  Pirie,  i n the model was upgraded to include  waste heat b o i l e r s and r e c u p e r a t o r s . made i n  Port  Some improvements a l s o were  of input parameters, such as changing c o a l  26 rates  and  variations  in  charge  additions.  As with the o r i g i n a l  model  fitted  was  coefficient  to  with  respect  to hot and c o l d  K e l l o g g model  ^  the modified  i n d u s t r i a l data by a d j u s t i n g the a c t i v i t y  of z i n c oxide i n the s l a g .  I t i s i n t e r e s t i n g to note  that Grant and Barnett needed a value 2.6 times greater than that used by K e l l o g g , and, that t h i s any independent  thermodynamic  i n c r e a s e was not s u b s t a n t i a t e d by data.  p o i n t because  i t means that the  the a c t i v i t y  of ZnO  i n the  This becomes a s i g n i f i c a n t  v a l i d i t y of  s l a g which  the model  r e s t s on  is effectively a fitting  parameter.  From a process point of view there i s  a fundamental  problem  with the assumption of e q u i l i b r i u m - i t negates the c o n s i d e r a t i o n of process k i n e t i c s . influence example,  of  kinetic  i t could  removal to  In so doing, i t i s impossible to assess the phenomena  prove  more  on  furnace  efficient  performance.  with  respect  operate the process i n such a manner that  For  to z i n c  equilibrium  i s not a c h i e v e d .  2.2.1.2  Empirical  Models  H i s t o r i c a l l y , support f o r the been l e s s  s c i e n t i f i c a l l y based. 18 20 —  process by Quarm value  in  phenomena.  , Sundstom  elucidating Even  21  second s c h o o l The  and Ivanov  fundamental  though  they  empirical  have  22  thermodynamic been  shown  of thought has models are and  of the  of l i t t l e kinetic  to reproduce  27 observations quite they  have  been  w e l l , p a r t i c u l a r l y f o r the furnace from which derived,  they  lack  broad  applicability  and  t h e r e f o r e u n i v e r s a l acceptance.  N e v e r t h e l e s s , the for  e m p i r i c a l models  the i d e n t i f i c a t i o n of  kinetic  can be  and  u s e f u l at l e a s t  thermodynamic phenomena.  In p a r t i c u l a r , some of the v a r i a b l e s that have been i d e n t i f i e d by Sundstrom and Ivanov to be of c r i t i c a l could be negative of  i n t e r p r e t e d as  kinetic effects.  i n f l u e n c e of bath weight, and  operating  evidence  importance  tuyeres.  In  the  t h a t i n j e c t i o n dynamics  fuming process.  to the process  These  include:  the e f f e c t  latter  play a  case, vital  the  of the number this  role  i s strong  i n the s l a g  Indeed, t h i s a l s o has been c o r r o b o r a t e d by the  f i n d i n g s of G l i n k o v et a l . ^ 3  2.1.1.3  I n d u s t r i a l and Laboratory  Additional  support  for  Studies  the  kinetic  modelling has been r e c e i v e d from 25-29 atory s t u d i e s of s l a g fuming. at  the Non-Ferrous  considerably  from  fuming, furnace  Metal  Works  standard  using  fuel  in  approach  to process  2 3 24 ' and l a b o r 5 In one instance , engineers industrial  Plovdiv,  B u l g a r i a departed  p r a c t i c e and developed  a  continuous  o i l as the r e d u c t a n t .  The furnace,  2 which  has  a  c r o s s - s e c t i o n a l area  of  s m e l t i n g furnace s l a g v i a an intermediate furnace.  Of p a r t i c u l a r  5.85 m , r e c e i v e d s h a f t e l e c t r i c arc s e t t l i n g  i n t e r e s t , apart from the s i g n i f i c a n c e of  28 the  approach  rate  i s 50%  taken,  lower  is  than  that a c c o r d i n g that  predicted  statement i s f u r t h e r corroborated  to Abrashev, the by  by the  fuming  equilibrium.  This  fact that a reduction in 2  c r o s s - s e c t i o n a l area  from 8.9  to 5.95  brought about  a two-fold  increase  and  unchanged.  This  a i r rates  furnace  i s l i m i t e d by  in  was  reported  furnace  is  strong  to have  c a p a c i t y with o i l evidence  that  the  have suggested that  the  kinetics.  Industrial p i l o t - p l a n t studies coal-slag  m  interaction  may  be  '  of fundamental importance to s l a g 25-29  reduction.  Other  these f i n d i n g s and  laboratory  experiments  have  confirmed  suggest that the r e d u c t i o n a c t u a l l y occurs  the  gaseous i n t e r m e d i a t e s ,  that  kinetic  phenomena,  CO and  such as  CO^. the  via  These s t u d i e s i n d i c a t e rate  of  the  Boudouard  26-29 reaction s l a g may In a  o c c u r r i n g on carbon and  on  more recent  a  series  nitrogen  injection  present.  The  study on  through  the  reduction.  the mechanisms of s l a g r e d u c t i o n  Denholm^, the r o l e of carbon i s l e s s c l e a r . of  experiments which i n v o l v e d coke, CO  i n t o z i n c - b e a r i n g s l a g s , with and  authors  proposed  reduced from i r o n c o n t a i n i n g s l a g s . appear to  diffusion  be r a t e c o n t r o l l i n g depending on the stage of  by Malone, Floyd and Based  oxide  a  mechanism  by which ZnO  Unfortunately  be a number of d i f f i c u l t i e s  in their  without  and iron is  however, there  i n t e r p r e t a t i o n of  29 the  r e s u l t s p a r t i c u l a r l y f o r the case where fuming was  achieved 2+  with  only n i t r o g e n i n j e c t i o n .  r a t i o was  r e p o r t e d to  constant  d u r i n g fuming  proposal  that  FeO  In t h i s experiment  have i n c r e a s e d i n i t i a l l y and which  is  the  source of  the  of ZnO  Substantial  and  proof f o r  e q u i l i b r i u m process was in 1983.  In  the z i n c  coal p a r t i c l e s  the  of  dynamics  One  1  present p r i o r  of n i t r o g e n  fuming  an exhaustive  process r e v e a l e d  injection  3  to  injection.  process as  a  non-  not provided u n t i l the work of R i c h a r d s  t h i s work,  possibility  with the  reductant. " "  i r o n was  the i n i t i a t i o n  /Fe  then remained  is c l e a r l y inconsistent  plausible explanation i s that m e t a l l i c the a d d i t i o n  the Fe  3+  internal was  i n d u s t r i a l study of the  entrained i n equilibrium.  also  used  to  1 3  the s l a g  negating  A n a l y s i s of tuyere  further  support  these  findings.  2.1.1.4  The  K i n e t i c Model of the  Based  on  industrial  Process  findings,  a  mathematical  i n c o r p o r a t i n g thermodynamic data, physiochemical data and phenomena was entrained  in  developed the  M e c h a n i s t i c a l l y , the  by  slag  Richards"'' as  model i s  the  3  based  on c o a l  site  formulated around  dividing  input c o a l i n t o the f o l l o w i n g f r a c t i o n s :  in  slag,  the  that  combusted  for  model kinetic  particles reduction.  the concept  of  that e n t r a i n e d  i n the tuyere gas column and  the  30  balance which i s assumed to pass through the furnace  In terms of model f o r m u l a t i o n ,  this  coal  p a r t i t i o n i n g that the furnace has e f f e c t i v e l y been separated  into  two  r e a c t i o n zones.  which e n t r a i n e d  The  first  coal reacts  it  follows  unconsumed.  of these  tuyere gas  with i n j e c t e d c o a l and the surrounding  overall  furnace  r e d u c t i o n zone i n  d i r e c t l y with the s l a g .  then i s an o x i d a t i o n zone i n which the  The  is a  from  model  The  second  column r e a c t s  slag.  can be broken down e s s e n t i a l l y  i n t o a s e r i e s of heat and mass balances  around  zones  Of these balances, those  and  the  furnace  as  a  unit.  the  a s s o c i a t e d with the r e d u c t i o n zone are of p a r t i c u l a r because  they  concepts.  are  the  r e d u c t i o n zone  particles,  from  reaction  significance  fundamentally based  kinetic  They w i l l be d i s c u s s e d i n c o n s i d e r a b l e d e t a i l .  Within  reaction  formulated  two  model,  heat  and  were formulated around  system  which  entrained  pyrolysis  and  "secondary  bubble"  have  c l u s t e r or char was r a d i u s of around  the  80  represents in  the  become  assumed  cluster after  surrounded  c o n t a i n i n g the by  balances  on  the  an e l a b o r a t e c o a l - g a s - s l a g  a  slag,  mass  by  to  several  coal  they have undergone an  products of  Richards  of  intermediate or pyrolysis.  have  an  This  effective  um.  Within t h i s system,  the f o l l o w i n g r e a c t i o n s were c o n s i d e r e d :  31  Z  n  0  (sl)  Fe-O2 3  C  (s)  CO  Kinetic oxide  +  +  C 0  ( s l )  C  0  (g)  =  Z n  (g)  2 _ (g)  2 C 0  °2  CO  interface,  CO_  2  . . .  included:  (Fe 0 ) 3  the  of  to the  wustite  (Eq. 2.3) on the char p a r t i c l e .  secondary bubble coefficients empirically valid  for  ascending  for  diffusing  bulk of  (FeO)  the Boudouard r e a c t i o n  based  on  spheres  species  dynamics  the  found i n  slag  fuming  were  taken  of z i n c  the  transfer from  from  an  l i t e r a t u r e , which i s The v e l o c i t y of these assuming  Stokes law.  f o r ZnO and FeO i n s l a g systems approximating  The d i f f u s i o n interface  from  r i s e of the  Mass  the  oxide and f e r r i c  those  literature.  d i f f u s i v i t y of Fe20^ was assumed to be one tenth that  slag  secondary  Diffusion  calculated  from the  i n c r e e p i n g flow.  of  slag.  were  bubbles r e l a t i v e to the s l a g was c a l c u l a t e d Diffusivities  3 )  the s l a g , and the rate of  the  through  based equation, taken rigid  '  d i f f u s i o n of z i n c  i n the s l a g  diffusion  estimated  ( 2  . . . (2.4)  to the  were  (2.2)  (g)  bubble-slag interface  rates  1 }  { g )  + HO  2  '  ( 2  • • •  (g)  and hematite  ' ' •  ( g )  (g)  phenomena c o n s i d e r e d  bubble-slag  C  + CO, . = 2FeO, ,,+ (g) (si)  + H = (g) (g)  (ZnO)  +  The  of FeO.  i r o n to the bubble-  i s a consequence of the reducing  c o n d i t i o n s which  32 prevail  in  the secondary bubble.  z i n c oxide  and  equations 2.1 were  ferric and  assumed  Equilibrium  2.3,  to was  iron  d i c t a t e d by equation  rapid  literature.  an  As  a  The r a t e  of  these  in  rises  bath.  reduced.  result  of the secondary  secondary bubble as  generated by  based  the  a c c o r d i n g to  Boudouard r e a c t i o n  equation  taken  the gas phase was  was  from the  assumed to be  the  r e a c t i o n s , the p a r t i a l pressure of secondary  bubble  Concurrently,  increases  ferric  9  iron also is  reactions  and r^O, and an increase  as i t  proceed i s The net  i n the volume  bubble.  tendency  secondary bubble  equilibrium.  on the r e l a t i v e r a t e s of m a s s - t r a n s f e r .  i s an i n f l u x of C0  The  of the  The r a t e at which these r e d u c t i o n  s o l e l y dependent  reactions  limiting.  m e t a l l i c z i n c vapour the  the  at  i n the gas phase,  empirically  result  through  reduced v i a  reduction  therefore  within  Mass-transfer within  r a p i d and not r a t e  These  be  r e a c t s with the char p a r t i c l e  the Boudouard r e a c t i o n . by  to  2.4.  reactions,  determined  assumed  and  assumed  Within the bubble, CO^ reduction  were  respectively.  be also  Upon a r r i v a l at the i n t e r f a c e ,  for  the  oxygen  potential  to  i s negated to a c e r t a i n extent  reaction occurring  on the  char p a r t i c l e s .  r a t e of the Boudouard r e a c t i o n  is  dependent  rise  i n the  by the Boudouard  However, because on  the  the  amount of  33  carbon remaining i n the char, the extent to which an o v e r a l l r e d u c t i o n p o t e n t i a l Consequently,  the  oxygen  decreases as  potential  of  r e d u c t i o n proceeds.  the  i n c r e a s e s and moves towards  e q u i l i b r i u m with  Within the  was  model, r e a c t i o n  assumed  i t can maintain  secondary that of  bubble  the s l a g .  to cease when the char-  secondary bubble reaches the s u r f a c e of the bath and the contents of the secondary bubble are r e l e a s e d to the furnace atmosphere.  Despite support  inherent  complexity,  of t h i s c o n c e p t u a l i z a t i o n  Richards^  from  3  samples. around  its  Zinc bubbles  and  and  iron  in  ferric  of the process  was  concentration  these  samples  iron  as  which  the the  profiles  i s c o n s i s t e n t with the  surrounding diffusing  slag,  and oxygen d i f f u s i o n  r e d u c t i o n zone, Richards  l a  the mathematical  3+  was  calculated  based  circulation velocity.  b a s i s of  the  a  path  system over the  i n the bath.  a unit  r e s i d e n c e time on  small.  conducted a heat and mass balance on  r e s i d e n c e time of the secondary bubble  The  couple  f o r m u l a t i o n of  the char p a r t i c l e secondary b u b b l e - s l a g r e a c t i o n  were c o n s t r u c t e d on the  zinc  Thus the  /Fe  i n i r o n r e d u c t i o n appears to be  to complete  and  species.  p o s s i b l e r o l e of e l e c t r o n t r a n s f e r between the Fe  coal p a r t i c l e .  by  were observed  2+  In order  found  e l e c t r o n microprobe a n a l y s i s of quenched s l a g  bubbles a c t i v i l y r e a c t i n g with oxide  s u b s t a n t i a l evidence i n  weight  of  of the p a r t i c l e length  and  an  The balances the  initial  i n the bath assumed s l a g  The path length of the p a r t i c l e ,  in turn,  34 was  calculated  tuyere  gas  based on  column,  estimates of  slag  porosity  the v o i d and  f r a c t i o n of  slag  circulation  the flow  patterns.  M u l t i p l y i n g the  conservation  which c o a l i s e n t r a i n e d of change  of z i n c ,  equations by the t o t a l rate at  i n the s l a g gives the  f e r r i c and  ferrous  instantaneous  iron concentrations,  the r a t e of heat consumption i n the r e d u c t i o n these r a t e s constant  over a given  In comparison to the r e d u c t i o n tuyere  gas  column were  b a s i s without invoking mass balances  combusted, as consumed by Richards"''  that  w i t h i n the  ferrous  tuyere  gas  iron  associated  on a more e m p i r i c a l and  determined e s s e n t i a l l y by  two  parameters:  reacts  and  question.  the  and  the  The  with  would  be  column because  The  fraction  of c o a l  f r a c t i o n of oxygen  latter  f r a c t i o n of oxygen i n the which  holding  heat  iron oxidation.  as the  unconsumed by c o a l reasoned  formulated  previously described,  3  By  zone, the balances  zone were  adjustable  ferrous  in  s p e c i f i c k i n e t i c mechanisms.  for t h i s  e x t e r n a l l y set  zone.  and  increment of time, the heat  mass balances are determined f o r the p e r i o d  with the  rates  was  defined  tuyere  ferrous  gas  iron.  by  stream It  o x i d i z e d to f e r r i c  was iron  the p r e v a i l i n g c o n d i t i o n s  g e n e r a l l y would be o x i d i z i n g .  By  specifying  balances for the  these  tuyere  gas  two  parameters,  column  the  heat  were determined  and  for a  mass given  35 overall  coal  and  air  f o l l o w i n g assumptions  [ i ] the c o a l and H 0  rate  and  The  temperature,  were made:  i s assumed to be completely combusted to CO v i a equations 2.5 and 2.6,  9  C + 0  H  injection  2  = CO  2  + 1/2 0  respectively;  (2.5)  2  =  2  H0  (2.6)  2  [ i i ] any ash accompanying the combusted c o a l  i s assumed to  enter the bath as s i l i c a ;  [iii]  ferrous  iron oxidation  i s assumed to proceed v i a equation  2.7; 2Fe0 + 1/2 0  2  = Fe 0 2  (2.7)  3  and  [ i v ] the tuyere gas and any unburnt the bath at the s l a g  In a d d i t i o n fraction Richards^ that  the  evaluated.  to e x i t  temperature.  to these balances, the f r a c t i o n of c o a l combusted and  of oxygen 3  c o a l are assumed  reacted  with  ferrous  to p r e d i c t oxygen u t i l i z a t i o n . underlying For  kinetics  example,  of a  the  value  iron  were  used  by  I t i s with t h i s number tuyere less  gas  than  column are 100%  oxygen  36  utilization of the  indicates  a kinetic  l i m i t a t i o n to complete r e a c t i o n  input oxygen with c o a l and/or s l a g .  The  t h i r d and  associated Kellogg **  ,  1  slag  with  on  final  the  taken  from  the  taken from thickness freeze  the  layer  walls  freeze  S i m i l a r l y to  on  and  bottom.  thermal  based  l i t e r a t u r e , and  was  and  balances were  bottom.  Assumptions  point  mass  the m e l t i n g  and  literature.  of the w a l l  and  walls and  capacities  s p e c i f i c s l a g melting  heat  considered  l a  furnace  c o e f f i c i e n t s , heat  of  furnace  Richards the  set  f r e e z i n g of Heat-transfer  c o n d u c t i v i t i e s were made  averaged  included: melting  a  ranges  a uniform composition through layer.  determined  by  The  composition  averaging a through  the  of  the  thickness  assay of a c t u a l f r o z e n wall m a t e r i a l taken from the w a l l of No. furnace  at Cominco.  In  order  to  close  the  furnace  heat balance  Richards assumed that the o x i d a t i o n r e a c t i o n s bath do not c o n t r i b u t e  to the  different  from the  considers  these r e a c t i o n s .  The  model  previously f r a c t i o n of ferrous  2  approach  was  mentioned  fitted  o c c u r r i n g above the  o v e r a l l s l a g heat balance. taken  in  the  Kellog  This i s  model which  to i n d u s t r i a l data by a d j u s t i n g  parameters  c o a l combusted  completely,  and  (fraction  of  coal  the  entrained,  f r a c t i o n of oxygen r e a c t i n g with  i r o n ) u n t i l good agreement was  obtained  between measured  37  and  predicted  particular carried  p r o f i l e s of  significance  bath composition and is  that  this  fitting  out on a c y c l e - t o - c y c l e b a s i s , and  data as was  temperature. procedure  not on averaged  the case with the Kellogg'''^ model and  l a t e r the  Of was  plant Grant  17  and  Barnett  entrained,  model.  Fitted  fraction  of  coal  utilization,  bath  depth  obtained f o r  five  different  cycles.  values  of  combusted,  and  fraction  total  of c o a l  furnace oxygen  n o n - s t o i c h i o m e t r i c f a c t o r , x, were furnaces  and  a  total  of eleven  These r e s u l t s permitted a comparison to be made between  c y c l e s and  furnaces so  that  trends  could  be  delineated  as a  f u n c t i o n of o p e r a t i n g p r a c t i c e . Despite k i n e t i c and  a  lack  of  p h y s i c a l data,  the behaviour  accurate  fundamental  the model  of z i n c , f e r r o u s and  has been  ferric  thermodynamic, shown to p r e d i c t  i r o n and,  approach q u a n t i t a t i v e p r e d i c t i o n of bath temperature. excludes  lead,  however t h i s  i s not  Of p a r t i c u l a r of the f i t t i n g  1  to 0.92.  model  low lead  content - l e s s  wt%.  significance  parameters.  The  f r a c t i o n of c o a l e n t r a i n e d was combusted, 0.45  The  a problem provided that the  fuming s l a g s under c o n s i d e r a t i o n have a than approximately  at l e a s t , to  to 0.60,  and  i s the c o n s i s t e n c y i n the values o v e r a l l ranges  0.29  to 0.39,  obtained for the  f o r f r a c t i o n of c o a l  f o r furnace oxygen u t i l i z a t i o n ,  In the case of the l a t t e r ,  i t was  u t i l i z a t i o n could be c o r r e l a t e d to bath  0.67  found that the oxygen  depth.  38  As coal  argued  entrained  approximately of  the  furnace the  model  for  three  profiles of  the  for  concern  were  not  generating  heat  model  consumed  sensitive  to  bath  accuracy  parameters,  oxygen  To were  the  to  the  iron  the  general  are  B  and  ferrous  are  from  applicability  of  which  temperature  the  only  through  oxidation This  p r e d i c t i o n s with furnace  mechanisms either  and will  respect  coal  that  the  fraction be  places  in to  oxygen  represent  there  utilization  combusted  profiles.  cycles  vary  i t is anticipated  coal  iron  furnace  oxygen  for  since  model  of  rate,  which  lack  process  self-consistent,  E,  Clearly,  fraction  rate,  have  The  other  coal  p r e d i c t i o n s of  A,  system.  of  foundations.  oxidation,  offending  some  of  flow  fraction  furnaces  to  preheat,  model  the  model  utilization  necessary  with  a l l  injection  blast  the  therefore,  the  evaluate  of  temperature  and  Unfortunately, the  of  the  its theoretical  within  in  since  parameters  indicative  available.  ferrous  i n the  blast  and  companies  predictions for  oxygen  the  or  type,  results  furnaces,  combustion  fitting  composition  supports  Although cause  coal  is  consistency  low-pressure  the  furnace, and  , the  expected  same  as  slag  to  be  of  such  dimensions,  Richards  i s to  sensitivity  variables  is  by  of  highly question  these  two  utilization.  seventy  percent  of  data.  of  the  formulate  more  the  questionable  model,  a  assumptions  sensitivity  analysis  that was  39 performed  with  respect  velocity,  coal  particle  factor, d i f f u s i v i t i e s  to  the  effect  cluster  of wustite  of  size, and  slag  wustite  z i n c oxide,  circulation  stoichiometric the  wustite-to-  hematite d i f f u s i v i t y r a t i o , bath s l a g p o r o s i t y , s l a g d e n s i t y , the v o i d  f r a c t i o n of  (%Zn/min) and  the  tuyere  gas  fuming e f f i c i e n c y  Remarkably, the  model was  column  (kg Zn  on the  and  fuming r a t e  fumed/kg c o a l i n j e c t e d ) .  shown to be r e l a t i v e l y  i n s e n s i t i v e to  these parameters.  F i n a l l y the p r e d i c t i v e c a p a b i l i t y of the k i n e t i c compared  to that of the  model  thermodynamic models of K e l l o g g " ^  was and,  17  Grant  and  f a c t o r was cycles  Barnett.  For  held constant  investigated),  these comparisons, the  at and  0.33 the  (the  average  fraction  entrainment  of  the  of c o a l combusted  oxygen u t i l i z a t i o n were c a l c u l a t e d w i t h i n the model based c o r r e l a t i o n s with eleven  bath depth.  cycles described  i s at l e a s t as accurate  The  e a r l i e r and  eleven  comparison was shows t h a t the  and  on  the  made for  the  k i n e t i c model  as the more widely accepted thermodynamic  models. Having process  e s t a b l i s h e d the  behaviour,  predictive tool.  Richards This  a b i l i t y of 1 3  turned  y i e l d e d the  a  i n c r e a s i n g the  particularly  significant  to  of the work-  i n both fuming r a t e  f r a c t i o n of c o a l e n t r a i n e d . result  simulate  to using the model as a  major f i n d i n g  the p r e d i c t i o n of a simultaneous increase e f f i c i e n c y by  the model  because  it  and  This i s  implies that a  40  s u b s t a n t i a l ,improvement  in  furnace performance  through manipulation of i n j e c t i o n be p r e d i c t e d  2.1.1.5  can be obtained  dynamics which  by an e q u i l i b r i u m based  clearly  cannot  model.  Summary  In summary, the i n v e s t i g a t i o n of R i c h a r d s " has c o n c l u s i v e l y 1  proved  that the z i n c s l a g  internal equilibrium.  fuming  process  least  as  well  as  the  profound.  and  understanding  based k i n e t i c  based  i n terms of p o t e n t i a l slag  operate at  p r e d i c t process  thermodynamics  s i g n i f i c a n c e of these f i n d i n g s improvement  not  In a d d i t i o n , a fundamentals  model of the process has been shown to at  does  reduction  in  behaviour  models.  The  f o r process general  is  41  CHAPTER I I I  OBJECTIVES AND SCOPE OF THE RESEARCH  It i s clear process a  from  the l i t e r a t u r e  t h a t the z i n c s l a g  i s governed by k i n e t i c f a c t o r s .  ±la,b  has  fuming  The work of Richards et  established conclusively  that the process does not  operate a t i n t e r n a l e q u i l i b r i u m and t h a t c o a l p a r t i c l e s e n t r a i n e d i n the s l a g are the major s i t e  The  objective  of  this  i n c r e a s e d c o a l entrainment furnace.  This  was  for reduction.  thesis  on  process k i n e t i c s  facilitated  p r e s s u r e " c o a l stream d i s t i n c t furnace.  The  data  taken  was to study the e f f e c t of  through  the  i n an i n d u s t r i a l use of a "high-  from the normal c o a l supply to the d u r i n g the high-pressure t r i a l s was  analyzed to e s t a b l i s h the e f f i c a c y of  increased coal  entrainment  quantitatively.  The o v e r a l l  p r o j e c t can  be broken  down i n t o three phases.  Phase one i n v o l v e s the d e s i g n and a c q u i s i t i o n of coal  delivery/injector  system  s p e c i f i e d performance c r i t e r i a Phase two  was comprised  pressure system. bath temperature,  which  was  a high-pressure  capable  of  meeting  f o r a s e r i e s of i n d u s t r i a l  trials.  of the i n d u s t r i a l t r i a l s with the h i g h -  During the high-pressure runs s l a g  composition,  furnace o p e r a t i n g parameters and high-pressure  42  coal  system  operating  parameters  were  recorded  measure furnace performance q u a n t i t a t i v e l y . on  data a n a l y s i s  Richards et a l entrained  l a  ''  and involved 3  f a c t o r s f o r the high-pressure  for this project,  were l i m i t e d . trials  Thus  undertaken  preliminary  the  three  order to focused  mathematical  of  i n order to process furnace data and c a l c u l a t e  It must be emphasized that available  modifying  Phase  in  coal.  the f i n a n c i a l and human resources  conducted  in  an i n d u s t r i a l s e t t i n g ,  the scope of the r e s e a r c h and the number of were  investigation.  necessarily  restricted  to  that  of a  43  CHAPTER IV  EXPERIMENTAL EQUIPMENT AND  4 .1  TECHNIQUES  I n d u s t r i a l Equipment  The  acquisition  and  design  of  d e l i v e r y / i n j e c t i o n system c o n s t i t u t e d project  because  achieving  i t s successful  increased  present the  coal  steps taken  the  coal  a major p a r t of the o v e r a l l  performance  entrainment. f o r the  high-pressure  The  was  critical  following  a c q u i s i t i o n and  to  sections  design of the  system.  4.1.1  High-Pressure Coal D e l i v e r v / I n - i e c t i o n  Because the was to increase increase be  used  to  At delivery  objective  of t h i s  s e r i e s of t r i a l s  c o a l entrainment i n the s l a g s i g n i f i c a n t l y and to  reduction  consideration  4.1.1.1  underlying  System  avoid  r a t e s , a minimal amount of c a r r i e r oxidation  of  the  i n e s t a b l i s h i n g design  Design  Criteria  first  glance,  systems  would  i t would be  slag.  a i r was to  This was a b a s i c  criteria.  appear  superior  that  the c o a l - s l u r r y  to the pneumatic d e l i v e r y  44  systems owing However,  to a  in  lack  order  entrainment due  to  of gaseous oxygen i n the isolate  to high-pressure  maintain as  much s i m i l a r i t y as  Richards et  a l  l  a  /  b  on  the  first  to-air  effect  of  i n j e c t i o n , i t was possible  to the  restricted  to minimize s l a g o x i d a t i o n  to  l o a d i n g s are  air injection.  This  Under normal o p e r a t i n g c o n d i t i o n s  about 0.15  (wt.  coal/wt.  to  o r i g i n a l work of  delivery  established  o v e r a l l system design c r i t e r i o n - maximization of  loading.  coal  essential  pneumatic  by a i r .  fluid.  increased  c o n v e n t i o n a l low-pressure  Therefore c o n s i d e r a t i o n s were systems and  the  carrier  a i r ) for  the  coal-  coal-to-air No.  2 slag  the  design.  fuming furnace of Cominco.  Injection It  has  dynamics a l s o  been e s t a b l i s h e d  fuming process bubbles. attached for  the  to  the  previously  gas  It f o l l o w s  figure  importantly in that  l a  d i s c h a r g e s from  then, that  tuyere, the  the  zinc  tuyeres as  slag  discrete  under c o n d i t i o n s when a bubble i s  following  a c o a l p a r t i c l e e x i t i n g the  the  in  events must occur i n order  tuyere to become e n t r a i n e d  in  the  slag:  [i] [ii]  The  c o a l p a r t i c l e s must t r a v e r s e  Upon impingement with the have  sufficient  t e n s i o n at the  The  probability  of a  momentum  bubble s l a g  the  s l a g , the to  bubble unconsumed. c o a l p a r t i c l e s must  overcome  the  surface  interface.  coal p a r t i c l e surviving  the  traverse  under  45 normal o p e r a t i n g c o n d i t i o n s has Richards  and,  1 3  With  will  respect  been d i s c u s s e d  not be repeated  to  improving  obvious t h a t gains could  in d e t a i l  here.  entrainment,  be r e a l i z e d  however,  through a  of c o a l p a r t i c l e combustion and/or an  probability  of  particle  entrainment.  example,  possible  method  would  be  to increase p a r t i c l e e x i t  which has  the advantage  of  both  increasing  particle  increase c o a l this  has  higher  p a r t i c l e mass  the  advantage  particle  avoid the that  due  Therefore,  while m a i n t a i n i n g  of  a  study was  to  practical  alternative  constraints  coal  particle  size  means of  through the use  and  and some  the d e s i r e to  would  not  was  be  decided feasible.  i n c r e a s i n g c o a l entrainment  of high e x i t v e l o c i t i e s .  This  t h e second o v e r a l l design c r i t e r i o n - maximization of  exit  velocity.  For  r e f e r e n c e , under normal  c o n d i t i o n s a i r volume flow r a t e s and coal p a r t i c l e furnace.  to  Again  probabilities  third  and  would be  velocity.  greater s u r v i v a l As  time  used.  the only v i a b l e  established tuyere  approach  one  velocities  traverse  i n t r o d u c t i o n of an a d d i t i o n a l v a r i a b l e , i t  increasing  in the  Another  momentums.  combination could be  However,  momentum.  is  increase in the  For  decreasing  it  decrease i n the  probability  coal  by  exit velocities  This i s  tuyere  exit  operating  diameters place  at between 40-50 m/sec i n the  c a l c u l a t e d based  on the  assumption that  No.2 the  46 c o a l p a r t i c l e s are t r a v e l l i n g 100% of the gas v e l o c i t y .  Considering r e a d i l y apparent  these  system  design  criteria  that the d e s i r e f o r high stream  further, exit  i t is  velocities  (high volume flow r a t e s ) i s i n c o n s i s t e n t with the d e s i r e f o r high stream to  coal-to-air  this  dilemma  s e c t i o n a l area. criterion  in  is  to  employ i n j e c t o r s having a small c r o s s -  Q u a l i t a t i v e l y , t h i s e s t a b l i s h e d the t h i r d  tuyeres on the No.2  in.) resulting  furnace have an I.D. of 38.1 mm 2  i n a c r o s s - s e c t i o n a l area of  11 cm  (1.73  ) . Having e s t a b l i s h e d the design c r i t e r i a  i n j e c t o r and  d e l i v e r y system,  i t is  q u a l i t a t i v e l y f o r the  p o s s i b l e to a r r i v e a t some  q u a n t i t a t i v e s p e c i f i c a t i o n s b e a r i n g i n mind p r a c t i c a l of  design  - m i n i m i z a t i o n of c r o s s - s e c t i o n a l area of the i n j e c t o r .  The standard (1.53  l o a d i n g s (low volume flow r a t e s ) . The s o l u t i o n  facilities  and time.  In the i n i t i a l  high-pressure  was decided to i n c r e a s e the c o a l entrainment by no more than 100%.  From the a n a l y s i s  furnace by Richards et a l low-pressure  injection  the r a t e d maximum of approximately  46  l a  /b^  t  i s roughly the  kg/min  h  g  c o a  -^  trials i t  r a t e of No.2  of the  furnace  Cominco  entrainment  feed  lbs/min)  system  No. 2  rate for  23 kg/min (50 l b s / m i n ) .  high-pressure (100  limitations  Thus  should be  f o r continuous  coal  delivery.  In a d d i t i o n , i f the furnace  i s not w e l l  mixed, i t would be  47 necessary to i n s t a l l s e v e r a l high-pressure l o c a t i o n s , eg. two i n j e c t i o n system  on e i t h e r s i d e had to  of  i n j e c t o r s at d i f f e r e n t  the  furnace.  be s u f f i c i e n t l y  Hence the  f l e x i b l e to  facilitate  this option.  I n t u i t i v e l y the o p e r a t i n g pressure has  to  be  high  in  order  to  of  the  overcome  d e l i v e r y system  the l a r g e l i n e l o s s e s  a s s o c i a t e d with the high i n j e c t i o n v e l o c i t i e s and  high c o a l - t o -  2 air  loadings.  Turning  A practical  to  l i m i t was  injector  690  design,  kN/m  the  (100  psig).  overriding  practical  c o n s i d e r a t i o n s were c o m p a t i b i l i t y with the e x i s t i n g tuyere (the i n j e c t o r s were to be existing tuyeres),  s i m p l i c i t y of  construction materials. length of  inserted  i n t o the  standard s t r a i g h t  pipe as  The  upper l i m i t to the i n s i d e diameter  mm  (0.824  in)  based  accepted  by the b a l l  nominal,  schedule  in).  The  which  was  nominal, in).  valve on  40S,  determined  From  40S,  arguments  area,  the  by  injector  of the  the  was  was  tuyere  6.83  smallest  on  mm  =  inch 1.050  (0.269 in) (1/8  injector  diameter  20.92  (3/4  = 0.269 i n , O.D.  earlier  4.1.  pipe which i s  the s m a l l e s t pipe a v a i l a b l e  presented  using a  = 0.824 i n , O.D.  I.D.  s t e e l pipe, I.D.  however,  met  diameter  s t e e l pipe, I.D.  by  were  of the  the end  the  the a v a i l a b i l i t y of  an i n j e c t o r , see F i g .  maximum  l i m i t to the i n j e c t o r  schedule  sectional needed.  lower  on  furnace through  design and  These requirements  design  inch  = 0.405 cross-  injector  was  From  storage  hopper  Primary air-coal Secondary V air 1  Upper  /  f luidizer  Standard  /  tuyere  box  High - pressure injector  I /  / / /) ) ) ) ) ! } X  J// I *I 1  1  1  1  Standard  }  1  1  1  7 T  1  tuyere  Continuous fluidizer  Figure  4.1  Schematic diagram showing the pneumatic conveyor, the i n j e c t o r and the standard low-pressure tuyere.  high-pressure ^  OB  49 F i n a l l y , because was  to  be  the e f f i c a c y of increased  established,  it  parameters, p a r t i c u l a r l y pressure  system be both  f o l l o w s that the  was  essential  coal rates  and  measured and  operating  pressure  Summary of Design  delivery/injector  q u a l i t a t i v e design  [i]  and  and/or pressure  It  differentials  to be measured.  was  based  of the on  high-pressure the  following  Maximization of stream c o a l to a i r l o a d i n g than 0.15  (wt coal/wt a i r ) ,  Maximization of i n j e c t o r e x i t v e l o c i t i e s  These c r i t e r i a could constraints  by  delivery/injection  [ii]  high-  criterion.  s i g n i f i c a n t l y greater  [i]  operating  a i r r a t e s , of the  acquisition  system  s i g n i f i c a n t l y greater [ii]  the  Criteria  In summary, the design coal  that  independently v a r i e d .  necessary to achieve these r a t e s a l s o had  4.1.1.2  c o a l entrainment  the  within  the  framework  specifications  system:  c o a l feed r a t e - 45.5 multiple  than 40-50 m/sec.  be met,  following  -  kg/min.  injector capability  for  of  local  the  coal  50 [iii]  high-pressure a i r flow - upper l i m i t approximately 690 kN/m  2  [iv]  small i n j e c t o r c r o s s - s e c t i o n a l areas  - initial  trials  with 6.83 mm I.D. pipe [v]  variable and  [vi]  o p e r a t i n g parameters - c o a l r a t e s , a i r r a t e s ,  pressures  measurement of o p e r a t i n g parameters - c o a l r a t e s , a i r r a t e s , and pressures  4.1.1.3  System S e l e c t i o n  By  comparing  the  design  criteria  solids  i n j e c t i o n systems (see Chapter  Table  2.1), the  pressure t r i a l s or  choice  systems  of t h i s p r o j e c t  pressures and  II pgs.  , particularly  c o a l d e l i v e r y system for the h i g h -  becomes obvious.  air-into-material  requirements  of  with the l i t e r a t u r e on  It i s clear are  best  because  of  c o a l - t o - a i r loadings.  that the blow-tank  suited the  to  meet  the  highest o p e r a t i n g  U n f o r t u n a t e l y , before t h i s  p r o j e c t was i n i t i a t e d , the system s e l e c t i o n was based more on the overriding purchased  economics by  Cominco  performance was extent that  a  Ltd.  As  unacceptable  i n s p i t e of  an  hose  anticipated,  pump the  was  system  t o such an  f o r the high-pressure  the o v e r a l l  t e s t s , some v a l u a b l e experience c o a l was gained.  peristaltic-type  shown t o compromise design o b j e c t i v e s  i t proved  Nevertheless,  and  trials.  f a i l u r e of the hose pump  on the t r a n s p o r t i n g  of p u l v e r i z e d  51  Having  established  that  the  general  classification  of  pneumatic d e l i v e r y system would have to be a blow-tank system, i t now  became  a question  compromises  of s p e c i f i c a t i o n s verses  had to be made.  Initially  economics.  there  was  Again  considerable  i n c e n t i v e to b u i l d a blow-tank system using s u r p l u s equipment on s i t e personnel. pressure  vessels  pressure  vessels,  c o s t l y and time  It  was  However, and the i t was  because  lack  of s u i t a b l e  r e g u l a t i o n s governing m o d i f i c a t i o n s decided  that  determined  that  the  t h i s route  decision. some  best  r e n t a l of a blow-tank  with on s i t e personnel and equipment.  compromised  the  to  would be too  consuming.  circumstances was  financial  of  and  Not  of  solution  system, and  under  the  installation  Again t h i s was p r i m a r i l y a  surprisingly,  the  rental  system  the p r e v i o u s l y e s t a b l i s h e d s p e c i f i c a t i o n s .  Of p a r t i c u l a r concern, f o r  example,  was  the absence  of c o n t r o l  over c o a l - t o - a i r l o a d i n g , and the lack of a b i l i t y to measure c o a l and  air  according critical  The  delivery to  rates.  specifications  criteria  performance  operation  Thus i t  general  was  however,  capable  of  of  the  high-pressure  t h a t some  of t h i s system would be  pressures.  high-pressure  detailed discussion  valuable.  system,  pneumatic conveyor  the d u r a t i o n and scope of the  is felt  the  meeting the more  of d e l i v e r y c a p a c i t y and o p e r a t i n g  essentially dictated trials.  In  of the  52  4.1.1.4  The High-Pressure D e l i v e r y System;  The  pneumatic  v e s s e l s mounted 4.2.  The  is  Continuous  on top  vessel  of the  or  material  at  operation  is  fluidizer  charged with  one  pressure  delivered  c y c l i n g the upper it  e s s e n t i a l l y consisted  vertically,  lower  continuously pressure.  conveyor  Operation  a  of two pressure other, see F i g .  continuous  fluidizer,  relatively  constant  achieved  by p e r i o d i c a l l y  between atmospheric  pressure (where  the m a t e r i a l  to be conveyed) and a pressure  s l i g h t l y above that of the continuous f l u i d i z e r the continuous  fluidizer).  upper  c y c l e s a c c o r d i n g t o the r a t e of which m a t e r i a l i s  fluidizer  being conveyed,  By a d j u s t i n g  (where i t charges  i t i s p o s s i b l e to maintain continuous  Starting at  time t=0  delivery.  with the d e l i v e r y system empty and a t  atmospheric p r e s s u r e , i t i s p o s s i b l e cycle  the r a t e a t which the  to  break  down  a complete  i n t o the f o l l o w i n g steps (see F i g . 4.2 f o r r e f e r e n c e ) :  [ i ] t=0;  The a i r to the upper (Valve No.  fluidizer  lower  switched on  6) and a t the same time the dome valve  (No. 5) moves up and i s the  is  fluidizer  closed.  The pressure i n  begins t o i n c r e a s e u n t i l i t  reaches P^, the d e l i v e r y pressure - a i r conveyed.  i s being  53 [ i i ] t=t^; The b u t t e r f l y valve (No. 1) opens and p u l v e r i z e d coal  falls  through  under  gravity  the conveyor  feed  from a storage hopper funnel  into  the upper  fluidizer.  [iii]  t = t ; The b u t t e r f l y valve c l o s e s - the upper  fluidizer  2  is  full.  [ i v ] t=t^; The a i r t o the upper f l u i d i z e r (Valve No. (No.  i s switched on  3) and s i m u l t a n e o u s l y the dome valve  2)  closes  -  the  pressure  fluidizer  begins  to increase.  has reached approximately 5) opens.  i n the  When the pressure  the  dome value (No.  The pressure i n the upper  continues t o r i s e  until  upper  i t reaches P  fluidizer 2  (several p s i  g r e a t e r than P^) - m a t e r i a l i s being conveyed t o the lower  fluidizer.  At  approximately  the same  time m a t e r i a l begins t o be conveyed from the lower fluidizer.  [v] t=t^; The a i r t o the upper f l u i d i z e r (Valve No. 3) and (No.  4) opens.  5) c l o s e s . drops t o  i s switched o f f  simultaneously  Almost immediately  The  the  dome valve (No.  pressure i n the upper  atmospheric  and  the dome  vent valve  fluidizer  valve  (No. 2)  54  opens.  The  continuous  approximately m a t e r i a l at  [ v i ] t=t(.; The  half  fluidizer  full  and  is  now  continues to convey  P^.  b u t t e r f l y v a l v e (No.l) opens and  repeated as from time  the  cycle i s  t=t^.  From a l o c a l i z e d c o n t r o l panel the operator has c o n t r o l upper and continuous the timers  f l u i d i z e r pressures, P  which d i c t a t e t^-  time), t ^ - t ^  (upper  2  and P^  respectively,  t ^ ( b u t t e r f l y v a l v e open or  f l u i d i z e r a i r on time) and,  over  charge  t^- t^  (time  to c y c l e r e p e a t ) .  With  respect  to  injection  note t h a t there i s a s l i g h t coal-to-air behaviour  loading  p a r t i c u l a r , the  variation  over the  i s a consequence variation  dynamics, i t i s i n t e r e s t i n g to  course of  of the in  in  conveying  a complete c y c l e .  mechanics of  conveying  pressure  the c y c l e .  pressure and  and  P  2  In  a i r from  d u r i n g those p e r i o d s when the upper f l u i d i z e r a i r i s on  i s e f f e c t i v e l y the source of conveying a i r .  In order to measure high-pressure a i r and c o a l is  This  coal-to-air  l o a d i n g that are a s s o c i a t e d with s w i t c h i n g the conveying P^to  and  fundamental  necessary  to  modifying  it.  to  the  instrument With  objectives the  r e s p e c t to  rental  of  this delivery  r a t e s , which  project, system  it  was  without  c o a l r a t e measurement, t h i s  achieved by p l a c i n g a s m a l l intermediate feed hopper on a 0 -  was  55  From  #4)  Vent valve upper fluidizer to  feed  hopper Butterfly  valve ( # |)  vent Dome  valve  lower  fluidizer  Upper air  (#2)  fluidizer ( # 3 )  D o m e valve ( # 5 ) continuous fluidizer  Continuous air ( # 6 )  to  Figure  4.2  Schematic diagram showing in d e t a i l  H.R  fluidizer  injector  the pneumatic  conveyor  56 227.3 kg (0-500 l b ) t e n s i o n l o a d c e l l each c y c l e was  captured  necessary  fluidizer charged  Coal vented a  the  system  fluidizer  g a l l o n drum.  had  a  charged ( a t t,.) T h i s was  tendency  t o vent  v a l v e No. 4, s e e F i g . 4.2, when t h e u p p e r By  measuring  the  amount  of c o a l  t o t h e d e l i v e r y s y s t e m a n d t h e amount o f c o a l v e n t e d , t h e  measured  reporting to  with  a  the furnace  a i r flow r a t e  0 - 2.83 Nm  3  Nm /min 3  c o u l d be to the  determined.  delivery  /min (0 - 100 Scfm)  ( O r i - F l o w Meter, Tokyo K e i s o  High-pressure 11.3  forty-five  rental  was d e p r e s s u r i z e d .  high-pressure  meter  from t h e upper  modified  c o a l through  amount  total  in  because  pulverized  net  (tj-t^).  t o measure t h e c o a l  a i r t o the  The  s y s t e m was  orifice  flow  Ltd.).  d e l i v e r y s y s t e m was s u p p l i e d by a  (400 Scfm) p o r t a b l e d i e s e l  compressor.  This  proved 2  t o be t h e o n l y means o f a t t a i n i n g (100  psig) a i r .  a reliable  Unfortunately, moisture  source  levels  o f 690 kN/m  i n the a i r supply  were h i g h a n d e v e n t u a l l y n e c e s s i t a t e d t h e u s e o f a 11.3 Nm /min 3  (400  Scfm) i n l i n e The  passed  pulverized  through  intermediate  pulverized  trap.  coal  a 2 ram (0.08 feed  T h i s was n e c e s s a r y  diameter  water  coal  hopper  from  high-pressure  Cominco s t o r a g e  inch) screen and  due t o t h e which  the  charging  presence  could injector.  not  be  prior  to  h o p p e r was  e n t e r i n g the  to the d e l i v e r y of  large  tolerated  lumps by  system. i n the  the small  57 The (1.25  transport  inch) I.D.  pipe  (1 inch)  length.  I.D.  rubber  c o u p l i n g with the  pressure  high-pressure  4.2.1  injector  to  used p r i o r  facilitate  to  rapid  assembly.  efficacy  increased  as  of  f u n c t i o n of  trials  coal  was  entrainment  to achieve t h i s , s p e c i f i c i n f o r m a t i o n  must  be  operating conditions during obtained.  The  techniques used  following  to o b t a i n t h i s  Tests  decided t h a t i n the i n i t i a l  c o a l would be i n t r o d u c e d p a r t of the way c y c l e " , and  material-on-material  data.  Industrial  It was  m (4 f e e t ) i n  o b j e c t i v e of t h i s p r o j e c t  s e c t i o n s d i s c u s s the experimental industrial  8  25.4  the u n d e r l y i n g  In order  on furnace behaviour the  mm  Techniques  the  quantitatively.  1.2  f l e x i b l e rubber hose was  removal of the i n j e c t o r  Experimental  establish  The  high  As d i s c u s s e d , to  hose, approximately  In a d d i t i o n , three 90°, high-wear,  i n s t a l l a t i o n and  s e c t i o n s of 31.75  l e n g t h , and a small s e c t i o n of f l e x i b l e  elbows were employed.  4.2  of two  drawn-over-mandrel s t e e l t u b i n g , approximately  m (26 f e e t ) i n t o t a l mm  consisted  that simultaneously  i n j e c t i o n , the normal low-pressure  trials,  the  high-pressure  through a "normal fuming  with the onset of high-pressure c o a l r a t e would be  reduced  by  58 an  amount  approximately  injection rate.  equivalent  I t was reasoned  to  the high-pressure  that t h i s  procedure  r e v e a l the e f f e c t of i n c r e a s e d c o a l entrainment. was a l s o decided that used to  o n l y one  high-pressure  coal  would best  Furthermore, i t  injector  would be  i n these t r i a l s because t h i s would a l l o w v a l u a b l e experience  be gained,  both  in  terms  of  furnace  behaviour  and h i g h -  pressure system o p e r a t i o n .  Since basis,  the  the  behaviour  effect  can  composition  zinc  slag of  increased  be determined  changes as a  fuming  process coal  from the  f u n c t i o n of  operates on a batch  entrainment manner i n  the high  on furnace  which the s l a g  and  low-pressure  c o a l and a i r r a t e s .  4.2.1.1  Of  Slag  Sampling  particular  interest  in  the  trials  change of z i n c , l e a d , f e r r o u s  and  bath temperature.  i n f o r m a t i o n on s l a g composition, a  To o b t a i n  ferric  were the r a t e s of  technique employed p r e v i o u s l y by Richards m (4.95  f t ) bar was i n s e r t e d  was withdrawn 3 - 4  l  a  composition and  was adopted.  A 1.5  i n t o the s l a g through a tuyere  then  seconds l a t e r and quenched with water.  To a s c e r t a i n the degree e f f e c t of  iron  i n j e c t i n g the  of  longitudinal  high-pressure c o a l  was measured by t a k i n g two s l a g  bath  mixing, the  in a localized  samples s i m u l t a n e o u s l y ;  area  one i n  59 the v i c i n i t y  of the  high-pressure  removed from i t as  possible.  d u r i n g the  run.  initial  i n j e c t o r and the other as f a r  T h i s procedure  In  was  followed only  subsequent t e s t s , a l l s l a g samples  were taken from tuyeres l o c a t e d d i r e c t l y opposite from pressure  the h i g h -  injector.  Under normal o p e r a t i n g c o n d i t i o n s the temperature Ltd.'s No.  2  slag  furnace  is  monitored  i n Cominco  continuously  with a  thermocouple p l a c e d i n the s l a g through a n o n - o p e r a t i o n a l t u y e r e . For  the  retrieved  high-pressure  coal  runs  this  from the c h a r t s on which i t was  Furnace  charge  constitution  details,  with  respect  in  to  temperature routinely  particular  hot  and  was  recorded.  total  cold  data  weight and  additions,  were  obtained from p l a n t p e r s o n n e l .  4.2.1.2  Two  Operating  Procedures  s e t s of o p e r a t i n g parameters had to be recorded over  course of a high-pressure run. the  The  measurement  of  i n c l u d e the  normal low-pressure  coal rate  achieved by  percent)  over  and  the  low-pressure  In order to measure the normal c o a l  2 furnace Omega c o a l feeder  T h i s was  group encompassed the  standard furnace o p e r a t i n g parameters which  a i r - b l a s t volume flow r a t e s . r a t e , the No.  first  the  had to  be  calibrated.  r e c o r d i n g feeder b e l t c u r r e n t (measured i n  measured  time  intervals  starting  with  a  full  60  storage hopper.  The  then was measured. Omega feeder  amount of c o a l needed to r e f i l l  Once c a l i b r a t e d , a r e c o r d  under normal  of No. 2  Blast  volume flow  r a t e s are recorded  operating conditions.  second  set  high-pressure coal injection  was kept  s e t t i n g s f o r the high-pressure runs and these were  converted to c o a l r a t e s .  The  the hopper  rates  of  d e l i v e r y system and  mentioned, were  operating  which i n c l u d e d  pressures.  determined  by  c o n d i t i o n s p e r t a i n e d t o the c o a l and a i r  High-pressure c o a l r a t e s , as  measuring  the  amount of m a t e r i a l  charged to the d e l i v e r y system and the amount of c o a l vented i t as  described e a r l i e r .  was f i l l e d periods  from the  when  filling,  the  the  output  delivery  This  from  instrumented  l a r g e r Cominco system  intermediate  d e l i v e r y system. The  The  hopper  load  cell  the  delivery  recorded.  was  system  per  From the load c e l l  not  then  charging.  After  was used to charge the  repeated f o r every c y c l e .  on the intermediate hopper was  recorded on a s t r i p c h a r t r e c o r d e r . from  intermediate hopper  storage hopper d u r i n g those  procedure was  the  from  The  cycle  amount of  was  coal  collected  output the t o t a l amount  vented  and a l s o charged to  the d e l i v e r y system over the course of h i g h - p r e s s u r e run could be determined. vented  then  determine average  The d i f f e r e n c e could  the average  amount  be  between t h i s  divided  high-pressure  of high-pressure  furnace with the c o a l  by  was  amount and  the amount  length  the run to  the coal  of  injection  rate.  conveying a i r i n j e c t e d  assumed  to  be  equal  to  The  i n t o the the h i g h -  61 pressure a i r continuous  flow r a t e  measured d u r i n g  a period  f l u i d i z e r a i r supply was on ( t ^ - t ^ ) ,  when o n l y the  see S e c t i o n  4.1.1.4.  4.2.1.3  Summary:  The  I n d u s t r i a l T e s t i n g Procedure  procedure  during  a  high-pressure  coal  run  can  be  summarized as f o l l o w s :  [i]  A f t e r the furnace had been f u l l y charged to reach  a temperature  of 1280-1300° C, normal fuming  o p e r a t i o n was s t a r t e d . every 5-10  [ii]  and allowed  Slag sampling  was c a r r i e d out  minutes.  After  15-20 minutes of normal fuming,  coal  was  injected.  c o a l r a t e was reduced  high-pressure  Simultaneously, the low-pressure and the s l a g subsequently  sampled  every 5 minutes.  [iii]  F o l l o w i n g the t e r m i n a t i o n of h i g h - p r e s s u r e i n j e c t i o n , the  s l a g was  sampled  coal  f o r a p e r i o d of 10-15  minutes.  [iv]  A l l p e r t i n e n t o p e r a t i n g data was c o l l e c t e d .  Unfortunately, f a i l u r e system  generally dictated  of  the  high-pressure  coal  the l e n g t h of the high-pressure  delivery runs.  62 4.2.2  Chemical A n a l y s i s of Slag  Chemical a n a l y s i s  of the  assay labs of Cominco. oxides  (CaO,  s i 0  2'  A 1  emission spectrography. out by a wet mate.  The  a n d  n o n  all  ~metal  Analysis for  determined  iron  reported  in  (Zn,  Pb  (S) were done by ferrous  the Fe),  7  X-ray  i r o n was  carried  this  1 3  thesis  is  i r o n determined by X-ray a n a l y s i s and  by wet  ferrous  chemistry.  iron  The  assay has  Ferrous i r o n assays reported require c o r r e c t i o n for  the  difference  ferrous  e f f e c t of s l a g s u l p h i d e  been i n v e s t i g a t e d  in t h i s  t h e s i s are  iron iron  elsewhere.  1 3  assumed not  to  estimated  by  sulphur.  Uncertainty  The Richards  uncertainty through  1 3  in a  slag  assays  Cominco  assumed that l a b o r a t o r y procedures and appreciably presented Table  and  therefore  has  been  process of s u b m i t t i n g  samples f o r a n a l y s i s at the  see  metals  procedure i s summarized elsewhere.  between t o t a l  4.2.3  for  performed by  chemical o x i d a t i v e technique using potassium d i c r o -  Ferric  on the  s l a g samples was  Assays  2°3^  Samples  that  assay  sixteen  laboratory.  It is  equipment have not  the u n c e r t a i n t i e s  changed  f o r the  i n t h i s t h e s i s are the same as those found by 4.1.  duplicate  assays  Richards,  TABLE Estimated  Average Absolute Difference  4.1  Uncertainty  of A n a l y s i s  Average Relative Difference  E s t imated Uncertainty  Zn  0.25  pet  7.8  pet  ± 4  pet  SiO,  3.00  pet  10.0  pet  ± 5  pet  CaO  0.7 4 p e t  4.1  pet  ± 2  pet  Pe  0.74  pet  2.6  pet  i  1.3  pet  0.39  pet  1.9  pet  i  l  pet  0.71  pet  34.0  pet  - 17  Pe Fe  2+ 3+  pet  64  CHAPTER V  EXPERIMENTAL RESULTS AND PRELIMINARY ANALYSIS  Problems with number of t r i a l s results  from  the high-pressure  to three  these  runs  runs  d e l i v e r y system l i m i t e d the  with  will  be  a  single  discussed  injector.  The  i n the f o l l o w i n g  chapter.  5.1  Results  Assays of the s l a g samples and o p e r a t i n g c o n d i t i o n s three high-pressure  runs are  presented  in  f o r the  F i g s . 5.1 - 5.12 and  are t a b u l a t e d i n Appendix I.  It should be noted supply were  that problems with the high-pressure  encountered i n  two of the three t r i a l s .  of the p e r i o d of high-pressure short  by  parameters  injection  delivery  system  failure.  remained  within  acceptable  coal  The length  i n Runs 2 and  3 was cut  Fortunately,  operating  limits  until  failure  occurred.  5.2  P r e l i m i n a r y A n a l y s i s and D i s c u s s i o n  Before  the e f f e c t of high-pressure  performance can be d i s c u s s e d  it  is  c o a l i n j e c t i o n on furnace  necessary  to  evaluate the  65 high-pressure  injection  dynamics to e s t a b l i s h  key parameters have i n f a c t been a c h i e v e d . are the  magnitudes of  stream c o a l - t o - a i r  5.2.1  v e l o c i t i e s have are presented the  Injection  been estimated  of c o a l  injector  conveyed  v e l o c i t i e s were  per  loadings  e x i t v e l o c i t y and  and  tuyeres  presented  and  calculated  exit  used  v e l o c i t i e s t y p i c a l of in  the Cominco No. 2  i n Table 5.1  l o a d i n g s are expressed weight  stream  f o r three high-pressure runs and  Loadings  low-pressure  fuming furnace a l s o are High-pressure  injector  importance  Dynamics  coal-to-air  i n Table 5.1.  standard  Of primary  loading.  High-Pressure  High-pressure  high-pressure  i f improvements i n  of  conveying  assuming the c o a l  f o r comparison.  i n terms of weight air.  Stream e x i t  to be t r a v e l l i n g a t  the a i r v e l o c i t y .  The  resulting  i n c r e a s e s i n stream  area f o r the high-pressure  are i n c l u d e d  i n Table  the momentum i n c r e a s e s ( f a c t o r and  momentum  per u n i t  tuyere r e l a t i v e to the standard low-  pressure tuyeres have been c a l c u l a t e d runs and  exit  f o r the three high-pressure  5.1.  Based on the magnitude of  of 171 f o r Run  1, 249  f o r Runs 2  222 f o r Run 3 ) , i t i s e v i d e n t that a c o n s i d e r a b l e g a i n i n the  driving  force f o r slag  with the high-pressure  entrainment injector.  (momentum)  has been achieved  66  TABLE 5.1 High-Pressure  Run No.  Coal rate (kg/min)  Air rate (NraVmin)  Injection  Dynamics  Coal to (wt./wt.)  Estimated coal exit velocity (m/s)  "Estimated momentum increase  Run 1  12  0.37  25  ~114  ~171x  Run 2  18  0.37  36  ~116  ~249x  Run 3  16  0.37  32  ~115  ~222x  Normal Operation (low pressure tuyere)  /  /  0.16  ~42  "These numbers r e p r e s e n t an e s t i m a t e f o r t h e i n c r e a s e i n momentum p e r u n i t a r e a for the high-pressure i n j e c t o r r e l a t i v e to the standard low-pressure tuyeres.  /  67  Having  established  consistent  with  assessing  the  the  that  the  original  effect  of  objectives,  high-pressure  performance can now be addressed. was r e a l i z e d there i s a  injection  dynamics  the  injection  associated  on  of  furnace  At the onset of the p r o j e c t i t  that t h i s would not be an easy t a s k . problem  question  are  with  defining  In p a r t i c u l a r , "normal" furnace  performance a g a i n s t which the h i g h - p r e s s u r e runs can be compared.  Originally, the  this  problem was  to be  avoided by i n t r o d u c i n g  h i g h - p r e s s u r e c o a l part of the way through  stage of  the fuming  procedure). direct  cycle  By adopting  comparison  (see Chapter IV  t h i s procedure  between  furnace  f o r o u t l i n e of t h i s  i t was  basis.  calculating efficiencies  The  comparison  simply  would  the c o r r e s p o n d i n g fuming r a t e s (kg  zinc  fumed  per  reasoned that a  performance  o p e r a t i o n and h i g h - p r e s s u r e i n j e c t i o n could be run  the proper fuming  kg  coal  made on be  (%  during  Zn  normal a run by  an e x e r c i s e of per  min) and  i n j e c t e d ) which are  normally used to measure furnace performance.  U n f o r t u n a t e l y , p r a c t i c a l c o n s t r a i n s prevented t h i s procedure from  being  fully  implemented.  As  a  o p e r a t i o n and performance must be c a r e f u l l y v a l i d comparison to be made.  result,  normal  d e f i n e d to  fuming  permit a  68 5.2.2  Normal Fuming P r a c t i c e a t Cominco  At the  Trail  ( see Appendix  Smelter of Cominco under  I, Table  broken down  I f o r approximate s l a g composition with  3+  2+  r e s p e c t t o Pb, Fe  "normal" c o n d i t i o n s  , Fe  , CaO and S i 0 ) , the fuming c y c l e can be 2  i n t o two stages,  as p r e v i o u s l y d e s c r i b e d  i n Chapter  I.  During Stage 1, the h e a t i n g p e r i o d , the secondary b l a s t  and  coal rate  are g e n e r a l l y  kg/min  of 340-400 Nm /min 3  Scfm),  respectively.  T y p i c a l l y , t h i s stage ends when the bath  (100-120  lbs/min), temper-  1300-1325°C.  Not s u r p r i s i n g l y , dependent  46-55  range  (12,000-14,000  ature reaches  and  i n the  rate  the length  of the h e a t i n g p e r i o d  i s very  on the charge c o n s t i t u t i o n with r e s p e c t t o hot and c o l d  additions.  For example,  hot charge,  t h i s period  50:50 h o t - c o l d h a l f a normal  under c o n d i t i o n s may l a s t  when there i s a 100%  15-20 minutes,  whereas f o r a  charge, the p e r i o d may l a s t upward of 75 minutesfuming c y c l e .  In t h i s  s i t u a t i o n , cold  granulated  s l a g may be c o n t i n u a l l y charged t o the furnace over the course of the h e a t i n g p e r i o d . heating  period  heating period  At  are t y p i c a l l y  16-14  wt%.  of  the  second  rate i s fixed at  the c o a l r a t e i s r a i s e d t o  between  stage,  the end  of the  However, when the  i s long, c o n c e n t r a t i o n s may f a l l  the onset  secondary b l a s t  Bath z i n c c o n c e n t r a t i o n s a t  to 8-10 wt%.  proper  fuming,  the  340 Nm /min (12,000 Scfm) and 3  64  and  68  kg/min (140-150  69 lbs/rain). are  During t h i s stage,  typically  about  approximately 0.7 one  month of  calculated  0.082  %  kg Zn/kg  operation  from  f o r a 100%  the z i n c  should  calculated  be  in  this  and  50%  initial  that  manner  temperature of the charge. of 30%  hot  appear  c o l d m a t e r i a l , the  coal respectively.  As the p r o p o r t i o n  decrease.  rates  to  be  fall  to 0.55  is believed  to be  which these q u a n t i t i e s are c a l c u l a t e d . (cold) z i n c - r i c h m a t e r i a l melts during tend to i n f l u e n c e the s l a g greater be an  than  increase  decrease i n The rich  that of  the  same should  zinc  also  hold  for  to  the  charges c o n s i s t i n g  and  0.48  kg  r a t e and  zinc/kg  the  efficiency  to the manner i n  Clearly,  if  any  fuming p e r i o d ,  because  concentration  fuming r a t e and  efficiencies  sensitive  due  the bulk of the bath.  the  and  its The of  zinc  solid  i t will  content i s  net r e s u l t w i l l the  bath  and  a  e f f i c i e n c y based on z i n c assays. lead i f  the melting  material is  in lead.  Taken one rate  in  assay  were  of c o l d m a t e r i a l charged to  i n c r e a s e s , the c a l c u l a t e d fuming This e f f e c t  and  fuming r a t e f a l l s to 0.067 and  efficiencies  furnace  only,  on  bath w e i g h t ) .  example, f o r  0.055 % Zn/min. and  the  are  fuming e f f i c i e n c i e s were  fuming  For  efficiencies  charges  assays; z i n c  noted  and  (values are an average based  100%  c a l c u l a t e d assuming a constant  It  Zn/min.  coal  for  hot charge, fuming r a t e s  step  further, this  (kg z i n c r e p o r t i n g to fume)  i m p l i e s that the a c t u a l fuming and  fuming  efficiency  (kg z i n c  70 reporting to  fume/kg c o a l  i n j e c t e d ) d u r i n g the p e r i o d of proper  fuming should be i n s e n s i t i v e set  of  operating  accordance  conditions.  with what would be  As a appears  t o charge  final  note,  necessary  to  temperature  This  for  behaviour  is  a given more  in  expected.  based  on  the  preceding  discussion i t  i n c l u d e i n f o r m a t i o n on charge  temperature  p r i o r to q u a n t i f y i n g normal furnace performance.  Having  e s t a b l i s h e d normal o p e r a t i o n and performance  f o r the  Cominco No.  2 fuming furnace, i t i s p o s s i b l e t o proceed  with the  p r e l i m i n a r y a n a l y s i s of the high-pressure  5.2.3  High-Pressure  In and  Coal I n j e c t i o n P r e l i m i n a r y A n a l y s i s  Run 1, the charge  consisted  to the furnace was 50,909 kg (56 t o n s ) ,  of 50% hot s l a g and 50% c o l d crushed m a t e r i a l .  anticipated, this resulted low bath of  however, i s  or  a prolonged  heating period  As  and a  (approximately 9 wt %) at the onset  normal fuming  period.  the e f f e c t t h a t the charge  r a t e and e f f i c i e n c y . the  in  zinc concentration  the proper  runs.  T h i s must  Of p a r t i c u l a r temperature  be c o n s i d e r e d  concern,  had on fuming  when i n t e r p r e t i n g  results.  Analysis  of  Run  1  which were experienced with  i s complicated charging the  f u r t h e r by d i f f i c u l t i e s high-pressure  delivery  71 system i n  the i n i t i a l  stages of  high-pressure  result,  from 15 to 25 minutes elapsed time,  to the  furnace  (low-pressure  F i g . 5.4.  to  61.4  (135  between  l e s s than normal f o r the fuming  p e r i o d , the  kg/min  As a  coal rate  In a d d i t i o n , because the bath  leveled o f f during t h i s raised  the t o t a l  p l u s high-pressure) ranged  4.5 and 9 kg/min. (10-20 lbs/min) stage, see  injection.  low-pressure  lbs/min)  for  temperature  coal  r a t e was  approximately  five  minutes.  The  simultaneous  interpretation  of  e f f e c t of a l l of  the  results  these  i n Run 1.  factors  complicates  Qualitatively,  does not appear to be any c o n s i s t e n t i n c r e a s e i n e i t h e r or  lead  elimination  rates  with  the  onset  of  there  the z i n c  high-pressure  i n j e c t i o n , see F i g . 5.1.  I t i s worth  maximum r a t e  of z i n c c o n c e n t r a t i o n c o i n c i d e s e x a c t l y  of decrease  n o t i n g , however,  with the p o i n t a t which steady s t a t e high-pressure  that the  i n j e c t i o n was  achieved.  If the  f e r r i c and  F i g . 5.2, the e f f e c t c l e a r l y seen.  ferrous iron  of  There  with  steady  c o n s i s t e n t with  high-pressure  is a  l e v e l and a corresponding  c o n d i t i o n s i n the s l a g .  coal  injection  i s more  general increase i n the f e r r o u s i r o n decrease  high-pressure increased  assays are c o n s i d e r e d , see  coal  in  ferric  injection. entrainment  level coincident  This and  behaviour  is  more reducing  Figure 5.1  Zn  and  Pb p r o f i l e s  for Run 1  WT. P E R C E N T F E 2 + , F E 3 +  JO  c  vj o-  3  b CO  o  -  to  J  b  p  b  •  •  •  (B  n  •  •  •  •  -B- -B-  •  •  LEGEND • = NORMAL COAL(LBS/MIN) 0=HIGH P.COAL(LBS/MIN) A = 0.1*SECOND. BLAST. VOL.(NM3/MIN) + =O.WEMP. SECBLAST(C) X = OXY.ENR ICHMENT  A  A-  o •  0.0  10.0  20.0  30.0  •A  IIIIII n * i • 11  •O •X  -©-  40.0  50.0  60.0  ELAPSED TIME(MIN)  Figure 5 . 4  Furnace o p e r a t i n g c o n d i t i o n s f o r Run 1  70.0  80.0  90  76 The  temperature  p r o f i l e , see  Fig.  continuous d e c l i n e d u r i n g high-pressure noted t h a t  the maximum  the short  term  r a t e of  increase  In  quantitative  been c a l c u l a t e d injection  for  (30-65  These values  terms, the  I t should be  drop c o i n c i d e d with  low-pressure  coal  r a t e and not  decrease.  a  fuming r a t e and e f f i c i e n c y have  period  of  minutes elapsed  can be  e x h i b i t s a roughly  injection.  temperature  i n the  with the p e r i o d of maximum z i n c  5.3,  s t e a d y - s t a t e , high-pressure  time) i n Run 1, see Table 5.2.  compared with  the average  e f f i c i e n c y f o r a 50:50 h o t - c o l d charge  fuming r a t e and  - a l s o shown i n Table 5.2.  From t h i s  comparison i t  i s clear  that s u b s t a n t i a l  have been  achieved with  high-pressure  injection  improvements  ( f a c t o r of 1.69  increase i n fuming r a t e and 1.68 i n c r e a s e i n fuming e f f i c i e n c y ) .  It should tests  be noted  (procedure  there  is  a  differences  that the  r e s u l t s of  described e a r l i e r  i n Chapter  high  degree  of  longitudinal  the double  IV) i n d i c a t e that  bath  mixing.  i n the z i n c c o n c e n t r a t i o n s of the double  Appendix I, Table 1) are w i t h i n -0.04 weight percent. i t can  be concluded  sample  that the s l a g samples taken  The  samples (see Therefore,  i n the v i c i n i t y  of the high-pressure tuyere are r e p r e s e n t a t i v e of the e n t i r e  bath  composition.  It evidence  is  worth  to  suggest  mentioning t h a t the  that  in  melting  F i g . 5.1 there i s some of  zinc  a  lead-rich  77  TABLE Fuming R a t e s and  Fuming rate  Fuming efficiency  Run No.  Run 1  5.2 Efficiencies  *Estimated increase in fuming rate  *Estimated increase in fuming efficiency  Predicted fuming efficiency  %Zn min  kg. Zn kg.coal  kg.Zn+ka.Pb kg.coal  0 .10  0.635  ~1.69x  ~1.68x  0.77 **0.92  Run  2  0.124  1.02  ~1.85x  ~1.86x  1.2  Run  3  0.150  1.27  ~1.85x  ~1.89x  1.4  * T h e s e numbers r e p r e s e n t i n c r e a s e s i n f u m i n g r a t e r e l a t i v e t o normal f u r n a c e performance. ** T h i s v a l u e was o b t a i n e d f r o m t h e model u s i n g a t e r m to a c c o u n t f o r the m e l t i n g of z i n c - r i c h m a t e r i a l .  78 material is  o c c u r r i n g throughout  a n o t i c e a b l e decrease  toward the of  was  the  furnace  operating  of t h i s  result  results  at  and zinc  in  light  t h e low  t o the  a final  maximum o f the  to  and  period  the  point  this  It  they  was p o s t u l a t e d excessive  This  made Run 2  both  of z i n c  bath  that  low-pressure  approximately  slag  charge  16  bath  increased  i n Run 1.  In f a c t ,  exceeded that  and  required  of  the r a t e d was due t o  high-pressure i n the b o i l e r .  c o a l r a t e s would i n subsequent  have  runs.  was 52,727 k g . (58 t o n s )  30%  hot  pot  a relatively  zinc concentrations  well  this  and c o m b u s t i n g  injection  wt% a t  particularly  2 boiler  amounts  the  hot  and a s a r e s u l t ,  -  the a d d i t i o n  injection  the charge t o the furnace  high  the v a l i d i t y  Nevertheless,  i n No.  where  high-pressure  c o n s i s t e d o f 70%  surprisingly,  the behaviour  and t h e r e f o r e , t h e m e l t i n g o f  high-pressure  i t was d e c i d e d  I n Run 2,  involved.  steam g e n e r a t i o n  through  t o be l o w e r d u r i n g  to  u n c e r t a i n t i e s i n assay  c o n s i s t e n t with  r a t e s and/or  stripping  Therefore,  the r e l a t i v e  of the bath,  the b o i l e r .  high-fuming  coal  are  regard  by a change i n  material.  note,  increased  of  there  lead elimination rates  for questioning  concentrations  bulk  substantially during levels  With  i s some j u s t i f i c a t i o n  and l e a d - r i c h  As  parameters.  observations  lead  z i n c and  In p a r t i c u l a r ,  end o f t h e r u n w h i c h was u n a c c o m p a n i e d  lead, there  of these  i n the  the r u n .  the onset  shell. short  were  testing  heating  relatively  o f t h e fuming  suited for  Not  period.  the high-  79 pressure  injection.  Unfortunately, still the  prevailed.  problems  In  this  magnitude of the c o a l  preceding Although rate  the s t a r t not  was  of  with  run,  representative  of  the problem  high-pressure  normal  in fuming  is  t o note  interesting  the  more  response  the i n i t i a l  injection  As a r e s u l t , c o u l d not  p r o b l e m was taken  P i g . 5.8.  plant  e x c e s s i v e steam  more  furnace  be compared fuming.  a direct  by  coal  those  p e r i o d of low-pressure  approach  t o the problems with  with  practice.  that t h i s  conservative  see  fuming  the low-pressure  comparison  performance d u r i n g high-pressure to  was a s s o c i a t e d w i t h  injection,  be o x i d i z i n g ,  low  quantitatively  of the r e s u l t s  r a t e d u r i n g t h e p e r i o d of normal  considered to  definitely  interpretation  result  It of  operators i n  generation  i n Run  1.  Qualitatively, the  elimination  high-pressure evident the  with  behaviour  Fig.  5.6,  rate  of  direct appears in  i n Run 2 t h e r e was a c o n s i d e r a b l e i n c r e a s e i n  r a t e s of  coal  both  injection,  and l e a d  s e e F i g . 5.5.  r e s p e c t to the behaviour of the  there appears ferrous iron  contradiction  ferric  with with  This  of l e a d .  decrease  high-pressure  the  behaviour  with  Interestingly,  with  - ferrous couple  t o be a s l i g h t  t o be i n c o n s i s t e n t  the s l a g .  zinc  the  of  is particularly In  contrast, i f  i s c o n s i d e r e d , see i n the g e n e r a t i o n  injection. observed  This  i n Run  c o n d i t i o n s b e c o m i n g more  the d i f f e r e n c e  onset  isin 1, and  reducing  i n low-pressure  coal  WT. P E R C E N T ZN,PB 0.0  p b  08  2.0  4.0  6.0  8.0  10.0  12.0  14.0  16.0  18.0  20.0  WT. PERCENT FE2+,FE3+  p  b T8  J  Z8  o d IT)  -e-  •eo d o  r  -s-  -B  -e- -B- -sLEGEND • = NORMAL C0AL(LBS/MIN) 0=HIGH P.COALrLBS/MIN) A=0.1*SEC0ND. BLAST. V0L.(NM3/MIN) + = 0.1*TEMP. SECBLAST(C) X= OXY.ENRICHMENT  ID  o _  10.0  30.0  40.0  50.0  60.0  90.0  ELAPSED TIME(MIN)  Figure  5.8  Furnace operating c o n d i t i o n s f o r Run 2  oo  84 rates  between  Runs  1  and  2  provides  seemingly c o n t r a d i c t o r y behaviour. discussion  before  Following the  is  iron  practice, iron  for  generation  by e n t r a i n e d  oxidation  with  by t h e  coal,  tuyere  gas  where one i s n o t  t h e model  pressure  c o a l source,  this  t o support  this  lead  was i n c r e a s e d generation  i n the tuyere  i n Run 1 i s p r o b a b l y  pressure  coal rate during  pressure  coal rate  ferrous  iron  off-set  by  (105  Under n o r m a l  at  no l o n g e r  the  to  from  due t o  lbs/min)  in  (increase  a n a l y s i s presented  highThere case,  (increased oxidation  i n the  rate of  b e h a v i o u r was n o t  the d i f f e r e n c e  (120 l b s / m i n )  i n t h e lowt h e low-  i n Run  1 to  Run 2, t h e r a t e o f o x i d a t i o n o f  by an amount w h i c h  the higher-reduction  of the  In t h i s  Moreover, by r e d u c i n g  54.5 kg/min  b  envisage  the case.  injection  that t h i s  ,  of ferrous  a second  i n Run 2.  high-pressure  a  operating  expense  with be  l  f o r consumption  and o x i d a t i o n  inference  fuming.  was i n c r e a s e d  modelling  et a l  i s r e d u c t i o n of  I t i s impossible  The f a c t  observed  the  column.  g a s column  iron).  this  of further  e l i m i n a t i o n r a t e s ) and s i m u l t a n e o u s l y ,  of f e r r i c  kg/,om  iron  i s correct,  should  r e d u c t i o n was i n c r e a s e d d u r i n g  47.7  ferrous  increased  However, i f  and  worthy  and t h e mechanism  other.  zinc  of  proceed are i n v e r s e l y r e l a t e d .  evidence  is  into  a n a l y s i s of the r e s u l t s .  the r a t e s a t which r e d u c t i o n  a situation  is  This  f r o m t h e m a t h e m a t i c a l model o f R i c h a r d s  mechanism  ferric  proceeding  some i n s i g h t  rate.  was n o t  This w i l l  i n a later  completely  be b o r n e o u t by  Chapter.  85 Additional temperature is clear during  evidence  f o r these  p r o f i l e , see F i g . 5.7.  that there  isa  high-pressure  mechanisms  Qualitatively,  net decrease  injection.  i n F i g . 5.7 i t  i n the bath  This  c o n s i s t e n t with normal fuming p r a c t i c e . and magnitude of the temperature  comes from the  trend  temperature  is  in  itself  However, the c o n s i s t e n c y  drop are l e s s than that expected 4 4  with an e q u i v a l e n t fuming r a t e obtained under normal o p e r a t i o n . This  behaviour,  in particular  the  magnitude  c o n s i s t e n t m e c h a n i s t i c a l l y with increased  of the drop, i s  ferrous iron oxidation  which i s a source of heat. The  results  of  a  performance i n Run 2 are pressure  fuming  compared  with  rate  o p e r a t i o n f o r a 70:30 Based on  this  presented  and  average  quantitative  i n Table  efficiency  values  r e a l i z e d with high-pressure  representative  5.2.  furnace  The h i g h -  of  low-pressure  shown a l s o i n Table 5.2.  substantial injection  of  obtained i n Run 2 can be  h o t - c o l d charge,  comparison,  analysis  gains  have  again been  ( f a c t o r of 1.85 i n c r e a s e i n  fuming r a t e and 1.86 i n c r e a s e i n e f f i c i e n c y ) .  and  In Run 3, the charge  t o the furnace was 58180  consisted  hot  attempt  of  100%  was made to a v o i d  slag.  kg. (64 tons)  In t h i s p a r t i c u l a r run an  excessive  generation  of  ferric  iron  d u r i n g the h e a t i n g p e r i o d (as i n the case of Run 2) by m a i n t a i n ing a secondary 5.12.  As a  b l a s t r a t e of 340 Nm /min  r e s u l t , the  3  heating period  (12,000 Scfm), see F i g . was a  little  longer i n  86 comparison with  Run  normal fuming was  2.  z i n c c o n c e n t r a t i o n at the onset of  approximately  with i n t e r p r e t a t i o n of  The  13 wt.%,  fuming p r i o r to high-pressure  Qualitatively,  from  ferrous  pressure  in  are  temperature Moreover, observed  comparison  drop the  i n Run  bath  The Table  again  Run  was  with  observed  at the  a t 30 mins. elapsed  2.  The  slowed the  time.  5.10,  was  r a t e of i n c r e a s e i n  during  preceding  high-pressure  period  of  low-  i s c o n s i d e r e d , see F i g . 5.11,  consistent  with  the p e r i o d  magnitude  of  the  of  of  high-pressure  injection.  drop,  the  by Richards et  r e s u l t s of a These  behaviour give f u r t h e r  al.  1 3  '*  net  50°C i s s i m i l a r to that fuming r a t e .  of the f e r r o u s - f e r r i c support  Both of couple  to  the mechanism  are  summarized i n  3  quantitative can  a  the  expectations  2 - s m a l l f o r the observed  temperature,  5.2.  profile  over  observations,  proposed  was  fuming.  results  and  lead  injection  concentration  If the temperature  these  a c o n s i d e r a b l e i n c r e a s e i n the  and  observations i n  because  5.12.  of the f e r r o u s - f e r r i c couple, see F i g .  iron  injection  i n j e c t i o n , see F i g .  zinc  high-pressure  c o n s i s t e n t with  Problems  c o a l r a t e d u r i n g the p e r i o d of  F i g 5.9,  e l i m i n a t i o n r a t e s of both  The behaviour  5.9..  of the r e s u l t s are a g a i n encountered  the r e l a t i v e l y low low-pressure  i n i t i a t i o n of  see F i g .  be  analysis  compared  with  average  values  Figure  5.11  Temperature p r o f i l e  f o r Run 3  oo  o O  O  •e- -B-  d o  -B-  -e-  •e-  LEGEND • = NORMAL C 0 A L ( L B S / M I N ) 0 = H I G H P.C0AL(LBS/MIN) A= 0 . 1 * S E C 0 N D . B L A S T . V 0 L . ( N M 3 / M I N ) + =0.1»TEMP. S E C . B L A S T ( C ) X= OXY.ENR ICHMENT  CO  o_| m  o d  A  A  A  A  -A-  A-  )(  )(  X-  )(  )(  —X-  a—6—a—r- ,a—a-  0.0  20.0  10.0  T  30.0  40.0  T  50.0  60.0  —T  H—i!r"rt"680.0  70.0  90.0  ELAPSED TIME(MIN)  Figure  5.12  Furnace o p e r a t i n g  conditions  f o r Run  3  10  o  91 r e p r e s e n t a t i v e of low-pressure presented  i n Table  substantial achieved in  5.2.  fuming f o r a 100% hot charge,  Again, as with the two previous  improvements  in  with high-pressure  furnace  injection  performance  (a f a c t o r  trials,  have  been  of 1.83 increase  fuming r a t e and a 1.89 i n c r e a s e i n fuming e f f i c i e n c y ) .  Before analysis, made  proceeding  with  a  with  Emphasis between  summary  of  the  preliminary  i t must be emphasized t h a t the q u a n t i t a t i v e comparisons normal  low-pressure  p l a n t data which i s assumed t o has  been  operating  particular, considered.  the  placed  operation  are based on average  best represent  on  conditions  i n j e c t i o n and those  maintaining prevailing  normal o p e r a t i o n . as  much s i m i l a r i t y  during  high-pressure  runs used to e s t a b l i s h normal o p e r a t i o n s .  importance  It i s felt  of  charge  temperature  has  i s the o n l y v a l i d approach p o s s i b l e .  5.3  Summary  In summary, the p r e l i m i n a r y a n a l y s i s of the r e s u l t s 1 t o 3 r e v e a l s t h a t c o n s i d e r a b l e improvement i n both  1, the  been  i n Runs  fuming r a t e s  e f f i c i e n c i e s have been r e a l i z e d with high-pressure  In Run  In  t h a t i n terms of a p r e l i m i n a r y a n a l y s i s ,  this  and  also  injection.  z i n c fuming r a t e and e f f i c i e n c y were increased by  f a c t o r s of 1.69 and 1.68 over normal o p e r a t i o n , r e s p e c t i v e l y . In Run  2,  the i n c r e a s e was a f a c t o r of 1.85 and 1.86, while,  3, the f a c t o r s were 1.83 and  1.89, r e s p e c t i v e l y .  i n Run  These r e s u l t s  92  are  in  direct  contradiction  e q u i l i b r i u m model.  to  any  predictions  I t remains to be e s t a b l i s h e d  on k i n e t i c s can account f o r these r e s u l t s .  based on an  i f a model based  93 CHAPTER VI MATHEMATICAL  MODEL OF ZINC FUMING PROCESS AND  DISCUSSION OF MODEL F I T T I N G  As  mentioned  injection  i n the zinc  of  Richards  of  the process.  kinetic  et a l  the  model  involve  runs  b  is  would be used an assumed  logical  analyze  attempt  to  coal. of  doing  coal  t h e Cominco No. 2  predict  coal  This  the i n d i v i d u a l factor  entrained.  The  by f i t t i n g under  of the three  form  procedure  would  combined  the furnace f o r information coal  t o estimate  then  r a t e s and the factor  low-pressure  entrainment  t h e model t o d a t a  normal  factors  the k i n e t i c  f o r the t o t a l  supply to  model  the Richards  entrainment  The  runs.  entrainment  furnace  that  coal  t h e work  mathematical  the results  factors  high-pressure  be o b t a i n e d  their  this.  i n conjunction with  high-pressure  f o l l o w e d from  In i t s present  and h i g h - p r e s s u r e ) three  of high-pressure  therefore,  of entrainment  low-pressure  could  fuming p r o c e s s  to further  capable  the  concept  and i n p a r t i c u l a r ,  i n an  calculation  of  factor  ,  slag  high-pressure  (low-pressure  of  a  It  is fully  each  l  model be used  high-pressure for  previously, the  taken  low-pressure  from  operating  conditions.  At  the  existing  outset,  program  supply d i s t i n c t that  this  by from  separation  however,  i t was  including the  normal  would  a  decided  separate  low-pressure  simplify  the  to  modify the  high-pressure  coal  coal.  felt  fitting  I t was  procedure.  Moreover, two  coal  it  would s e r v e  supplies  r e d u c t a n t , and was  within  the  t o emphasize the the  furnace:  o t h e r as  a source  l a r g e l y a book k e e p i n g e x e r c i s e  different roles  one of  and  acting  heat. does  as  the  a source  This not  of  of  modification  warrant  further  discussion.  The model  opportunity  i n a more  improvement bath.  The  the  unusually  secondly, reduction  was  in  high  in  order  The  regard  behaviour  the  area  reduction  at  elucidate  to  of  the  3  former,  wt%,  the  to complete  a valid  (Run  include  latter  technologies,  with  concentration  could  to  The  p r e c i p i t a t e d by  to  m o d i f y the  manner.  lead  efficiencies  technologies  cleaning  lead  however, t o  Richards  for of  potential  lead  in  the  i n a k i n e t i c model two  the  factors:  start  the  of  firstly,  o f Run  mechanisms  3, of  and lead  general.  pressure data modified  include  desire  concentration and  to  largely  the  With  rates  associated  desire  process  arise  fundamental  was  the  did  3) lead  the  no  longer  existing  of  of  felt lead  that on  zinc  neglected. one  model  third would  at  a  fuming  Therefore, of  the  have  highto  be  reduction.  the  smelting  s t a g e s and  be  analysis  follows  as  was  influence  reason  for  it  indicated  from the of  lead  previously,  i n p a r t i c u l a r the  emergence o f  the  concentrates. rely  removal of  heavily lead  newer These  on  slag  from  high  lead  content  slags.  It  mechanisms s u r r o u n d i n g understood that  the  would  aid  in  in  As  kinetic  1 3  The  the  obvious that limited  to  At is  The  the  model o f t h e  zinc  two  well  i n mind, i t was  felt  i n the  lead  the  z i n c fuming  model  lead reduction  and  Model  the  the  gas  the  of the  key  zones:  column  modification reduction  Particle  or  to very  i s the  the  zone  and  in by  - Slag Reaction  separation  zone.  lead  particular  due  the  reduction  reduction  Richards  of  Thus  i t is  will  the  et a l .  be  coal * 'k a  Model  becomes e n t r a i n e d  rapid heating  mechanistic  1 3  s l a g b a t h or  oxidation  surrounding  instant a coal particle  subjected  made t o  Process  to R i c h a r d s  the  r e a c t i o n system developed  Coal  modifications  process.  fuming process  reaction  tuyere the  particle-slag  6.1.1.1  Richards  previously,  the  into  z o n e , and  this  of  that be  mechanisms o f  Kinetic Conceptualization  discussed  furnace  removal  reduction  the  therefore,  general.  breakdown o f  it  elucidating  and  With  following sections discuss  Richards  6.1.1.  reduction  lead  M o d i f i c a t i o n s t o the  The  essential,  these processes.  i n c o r p o r a t i o n of  removal  6.1  in  the  is  to d i r e c t  i n the  slag  contact  with  the  slag.  Under  pyrolysis  these  occurs  conditions,  virtually made  according  instantaneously.  in  the  The  following  were  characterize  t h e e x c e e d i n g l y complex p y r o l y s i s p r o c e s s .  a l l proximate  volatile  hydrogen  i s released  as  H ,  (b)  a l l proximate  volatile  nitrogen  i s released  as  N^,  (c)  a l l  (d)  proximate  volatile  Following particle and  reacts  pyrolysis  resides  CO.  The  This  char  interface  following  ZnO  PbO  (si)  (si)  with  volatile  carbon p r e c i p i t a t e s  assumed t h a t  surrounded  particle  on  -  the remaining char  by an a t m o s p h e r e o f  secondary  bubble  ,  then  slag.  prevailing  o f ZnO,  (formerly only  bubble-slag  i t is  conditions  the d i f f u s i o n  interface  2  and  i n the s l a g  reducing  initiate  to  particle.  begins r e a c t i o n with the  the  oxygen  the remaining proximate v o l a t i l e the char  via  i n an a t t e m p t  (a)  c a r b o n t o f o r m CO,  2  model  Richards,  assumptions  N  original  to  ZnO  PbO  and  and  FSjO^  i n the secondary  Pe 0 2  3  t o the  bubble  bubble-slag  were c o n s i d e r e d ) .  t h e s e s p e c i e s t h e n a r e r e d u c e d by CO  At or  the H  reactions:  +  +  CO  CO  (g)  (g)  =  Zn  Pb  (g)  (v)  + CO  . . .  (6.1)  . . .  (6.2)  (g) + CO(g)  2  97 Fe,0  + CO.  1  (sl)  J  =  2FeO,  { q )  + CO(g)  '  l S A  . . .  (6.3)  . . .  (6.4)  Z  and ZnO.  ,. {  p b 0  s  l  + H(g)  )  /=i\ '  +  H  o  ( s l  2  Fe 0^ + (sl)  The  C0  diffuses via  the  J  and  2  Zn  H0  Pb  through the  H_0  '  + H„0  . . .  (v)  2  =  (g)  2  2FeO, {  S  X  + H„0 (g)  1  gas  (6.5)  . . .  (6.6)  1  produced v i a R e a c t i o n s  2  following  =  (g)  +  t g  H, ^(g)  9  Z  =  2  phase t o r e a c t  with  (6.1) the  -  char  (6.6)  then  particle  reactions:  Boudouard C  . (char)  Char -  Steam  (  r  h  a  (^=>T\  C  This  (char)  marks t h e  + CO,  r  2  +  H  ?°  2  the char  slag,  =  particle  Boudouard the  partial  and  H»  second divergence  initial the  2C0.  ( g )  r e a c t i o n model w h i c h o n l y  In the  =  ( q )  gradually  •  t  CO.  from the  this  the  .  original  Boudouard  (6.7)  .  (6.8)  Richards  1 3  reaction.  r e a c t i o n system  rises  through  pressures  of  Zn  and  Pb  increase,  and  the  shrinks  as  carbon  is  consumed  by  the  Char - Steam r e a c t i o n s .  pressure  (g).  ( g )  considers  s t a g e s as  vapour  2  . . .  ( g )  o f CO^  and  H^O  are  The a  rate  of  f u n c t i o n of  increase the  in  rates  98  at  which  they are  r a t e s a t which  An arises with  the s l a g .  The  lead.  zinc  which  will  partial  a  at the temperature  =  ( v )  point  bubble  precipitated  -  Pb  on,  at  vapour  1 7 4 0 ° C)  lead  unlike  (m.pt. 419.58, b . p t ? 907  that  the  vapour  C).  p r e s s u r e of until  the  metallic  . . .  lead  vapour  rate  (6.9)  c o n t i n u e s t o be p r o d u c e d  liquid  lead  at  i s simultaneously  s o a s t o m a i n t a i n R e a c t i o n (6.9) a t  liquid  lead  produced  collects  The  reaction  system  6.1.  C,  of  of the s l a g bath, i e .  interface,  such a  in Fig.  1200-1325°  b.pt.  react  the form  i n equilibrium with l i q u i d  For the purpose  illustrated  the  formulation  i n the secondary bubble  equilibrium.  bubble.  with  ( 1 )  as  slag  model  associated  327.50,  rise  pressure reaches that  From t h i s the  to  to  temperatures,  i t c a n be a r g u e d  continue  Pb  is  (m.pt. is  respect  - secondary bubble c o n t i n u e s to  problem  a liquid  Mechanistically,  lead  with  At slag; fuming  s t a b l e as  lead  problem  as the c h a r p a r t i c l e  metallic  ( 6 . 1 ) - ( 6 . 6 ) , and  t h e y a r e consumed by R e a c t i o n s ( 6 . 7 ) - ( 6 . 8 ) .  interesting  metallic is  generated v i a Reactions  o f m o d e l l i n g i t i s assumed t h a t in which  the bottom develops  of the  the  secondary  i s schematically  Liquid  Figure  6.1  The  lead  char p a r t i c l e - s l a g  r e a c t i o n system  *°  100  As in  discussed  support  Similar  previously  of  evidence  this  Cominco l e a d inclusion,  blast or  reaction  f o r the lead  from aphotomicrograph  i n Chapter  of a  reduction  (secondary b u b b l e s ) as  prill,  provided  by  in  F i g 6 . 2 shows a contact  with  evidence  Richards^"  modification  quenched and p o l i s h e d  furnace s l a g .  lead  was  I I , substantial  3  i s available  s l a g sample o f white  black  metallic gas p o r e s  postulated.  Note: Course s t u b b y inclusions a r e more Fe rich than s l a g . Metallic inclusion c o n t a i n s a f a i r l y p u r e Pb c o r e w i t h a r i m m i n g o f Cu, S and m i n o r F e . The s l a g and s t u b b y i n c l u s i o n s a r e Zn and S rich. R e f l e c t e d l i g h t , x 160 m a g n i f i c a t i o n s .  Fig  6.2  P h o t o m i c r o g r a p h o f quenched a n d p o l i s h e d  slag  sample  101 In  this  electron  transfer  significant Evidence II.  role  to this  The  reaction  system of  The  assumed t h a t  ferric  the  diffusion  i s identical better  of  iron  has been d i s c u s s e d p r e v i o u s l y of  processes  to that  rheological  data.  T h i s assumption  relative and  rates  of  surrounding  3  ) .  +  i n Chapter  except  Equilibrium  bubble  (Fe  i n and a r o u n d t h e  of R i c h a r d s  of the secondary  f o r the  i s assumed  and l o c a l l y a t t h e  was j u s t i f i e d mass-transfer slag.  f r o m an  1 3  w i t h i n the  Mass-transfer  were e s t i m a t e d a s f o l l o w s .  terminal rise  to Stoke's  is  reduction  bubble  coefficients  i t  in effect  assessment of the  Richards,  c o u p l e does n o t p l a y a  interface.  secondary  with  ferric-ferrous  t h e g a s phase  bubble-slag  as  v i a the  treatment  inclusion within  system,  velocity  of the secondary  bubble  according  Law i s : = ^ A p / l S ^  terminal  35  where a c c o r d i n g t o A l t m a n e t a l  • • • (6.10)  , f o r lead  c o n  log p  = 0.0160 l o g (CR) +  blast  furnace  slag  -jo  y*^  0  '  3  9  8  8  1  • • •  ( -H) 6  where, % SiO CR =  + % Al 0  + % MgO . . . (6.12)  1  % CaO + % FeO + % ZnO + % S  (percentages  a r e i n weight  percent).  102 From C l i f t  et a l  36  , for rigid  spheres i n creeping  flow, f o r  species i : Shj * 1 + where Pe  i s the P e c l e t Pe  and,  Sh  must be made.  Number;  1 3  is spherical,  (b)  the char p a r t i c l e  reacts  (c)  the system  CO*  the  by R i c h a r d s . C  £o ' 2  C  H* ' 2  t h r e e time-dependent  C  H 0' 2  i s the molar  incorporation  of l e a d  C  2  r  p  a  n  d  r  b'  is  the r a d i u s of  amount o f c a r b o n  H^O,  and  s y s t e m has  unknown t i m e - d e p e n d e n t  S'  also  temperature.  i  n  W^, V  , i s the c o n c e n t r a t i o n p  and  reaction  m o d e l l i n g parameters,  the secondary bubble, r c  original  Eight  been c o n s i d e r e d where  c  o n l y w i t h CO^  i s isothermal at bath  model o f  assumptions  , these are:  the char p a r t i c l e  C  M  from R i c h a r d s  (a)  developed  and  . . . (6.15)  of m o d e l l i n g , a d d i t i o n a l  Following  A sample  Zn'  . . . (6.14)  = 2k.r./D, i b i  the purpose  (6.13)  Number;  i s t h e Sherwood  For  . . .  1 7 3  - Zr^/Dj  i  Sh. i  C  (1+Pej)  variables,  addition g  and of  been  to  M^,  have  species  the secondary  bubble,  i n the char p a r t i c l e .  r e d u c t i o n a d d s two  more v a r i a b l e s :  i in  C  The p f a  v  103 and  M  , the c o n c e n t r a t i o n of lead  p b  bubble  and  t h e molar  makes a t o t a l equations  The by  the  their  The  n  respectively.  dependent q u a n t i t i e s .  This  Thirteen  lead  equations reduction  is sufficiently to warrant  changed  a repeat of  Balance  characterized  ZnO  lead  here.  mass-transfer  fx  time  of these  c o n s i d e r a t i o n of  Zinc  liquid  i n the secondary  developed.  development  derivation  A zinc  thirteen  must be  6.1.1.1.1  be  of  amount o f  vapour  of z i n c  oxide  by t h e e m p i r i c a l  - A. k  mass b a l a n c e  ZnO  (C  SI ZnO  -  to the secondary  bubble can  equation:  ciZnO  on t h e s e c o n d a r y  bubble  (6.16)  yields:  ZnO  Thus (6.18)  104 6.1.1.1.2  The be  Lead  Balance  mass-transfer  characterized  of lead  by t h e e m p i r i c a l  A = A k ic PbO b PbCT^PbO s  n  For  A  conditions  bubble  (C  dt  For  Pb  =  v  in  v  of P b with  i n the secondary  v  liquid  lead,  a mass  C Pb  c  Pb  .  fe<V  v  .  ( ~ (V )  u  v  dt V  . (6.20)  . . (6.21)  g  equilibrium  serves  +  v  b  when t h e  partial  with  pressure  liquid  lead,  i n t e r f a c e ends up to  equilibrium with into  c  PbO  the bubble-slag  portion  < Pb >  1  v  >  v  conditions  that at  ( C  )  b  pressure  yields:  d V P b V =g dT c  (6.19)  1  i n equilibrium  on t h e g a s phase  n PbO  ^  than that  equation:  - c ) ^PbO '  l  K  when t h e p a r t i a l  i s less  balance  oxide t o the secondary bubble can  maintain  liquid  the  lead.  of lead  a portion  in  the  partial  Separating  vapour of lead  gas  equals reduced  phase.  pressure the t o t a l  This  of lead a t flux  o f PbO  two c o m p o n e n t s : n^.o. PbO n  = portion  PbO f l u x  reporting  t o gas phase,  v  Pb0  =  From E q u a t i o n follows  of t o t a l  that  P  o  r  t  i  o  (6.9),  n  o  t  t  o  t  a  l  p  b  0  flux  reporting  to l i q u i d .  a s s u m i n g one a t m o s p h e r e t o t a l  pressure, i t  105  K  6.9  "  P  Pb  "  ^  v  Rearranging Equation  C  Pb  "  K  p  • ' '  ( 6  '  2 2 )  g  (6.22)  6.9  Pg  • ' '  ( 6  '  2 3 )  and d i f f e r e n t i a t i n g g i v e s  dt  d dt  < Pb > v C  m < 6.9 g K  A mass balance f o r lead  — dt  n PbO  (C * Pb  D  > "  (6.24)  0  i n the gas phase y i e l d s :  . (6.25)  V ) g' ^  b  v  Expanding and r e a r r a n g i n g ,  dt  1  lt (C° W v)  Substituting  Vg  PbO v "  n  Equations  C  ™b Pb v  d ,„ .  dt V ^ (  (6.23) and (6.24) i n t o Equation  (6.26)  (6.26),  and r e a r r a n g i n g ,  •  "PbO  u =  v  K  6.9  Pg  n\  d  . .  d t V* * (  (6.27)  106 This the  then  gas p h a s e .  liquid  lead  Pb  A  of  The p o r t i o n  the total  of the t o t a l  dV  f l u x o f PbO w h i c h  enters  f l u x o f PbO r e p o r t i n g t o  ^Pb^  • • • < 6  a mass b a l a n c e on t h e t o t a l  lead  2 8 )  ( v a p o u r and l i q u i d ) i n  system y i e l d s :  *PbO  "PbO  =  Substituting  A  PbO -  6.1.1.1.3  +  gas  1  Equations  6 . 9 Pg  reactions  (6.27) and (6.28) i n t o  dt< g> V  not leave  phase (6.7)  •  r  ' ' '  x  *  dt  + (  M  (6.29)  Pb,l>  (  6  >  3  0  '  3  )  gives:  ' ' *  (  6  0  )  Carbon Balance  input  where &  PbO  Equations  K  f c  n  v  Carbon does the  portion  i s simply  -  0 l  Finally, the  i s the  and*?  by  the  the secondary bubble.  Boudouard  and  and ( 6 . 8 ) r e s p e c t i v e l y .  B  +  r  Carbon  char-steam  enters  reactions,  Thus  S  . . .  (6.31)  r  are the rates  respectively.  A  o f t h e B o u d o u a r d and c h a r - s t e a m  mass b a l a n c e  f o r carbon  i n t h e gas  107  phase  yields  V  , fe «  C  CO» * fe < CO C  > I  c  <V  fe  b  + c  b  .  (6.32)  rearranging,  dt  ( C  CO  )  +  dt  ( C  C0  dt * g '  }  CO  v  2  CO, (6.33)  6.1.1.1.4  Oxygen B a l a n c e  Oxygen (6.3).  t h e gas  phase v i a R e a c t i o n s  T h e r e i s no g e n e r a t i o n  2 where n  enters  p  1 . 2 ZnO n  input e  Q  • r  or consumption.  1*  2 PbO n  + T  (6.1), Thus:  1 A 2  .  Fe 0 2  i s t h e r a t e o£ mass t r a n s f e r  (6.2) and  . . (6.34)  3  of F e 0 2  3  to the  secondary bubble.  A mass b a l a n c e  1 2,  input  2  f o r oxygen  d_ _ b dt C0 (  l U  „ . g'  i n t h e g a s phase  d_ b dt C 0 ( c  +  v  t u  9  . g'  yields  1 d_ 2 dt  ( C l u  b H 0  v  9  .  . g' (6.35)  108 rearranging,  A  ZnO  +  PbO  n  +  n  2  d_ b dt CO u  +  is  C + 2C + C CO ^ C0 H 0 b  b  C  +  b  C  +  L  2  2  i _ b dt H 0  U  (6.36)  U  2  Hydrogen  There  St <V  3  d_ b *^dt C 0  c  6.1.1.1.5  Fe 0  2  Balance  no n e t i n p u t ,  output, g e n e r a t i o n or consumption of  hydrogen  i n the  secondary  bubble.  hydrogen  i n the secondary bubble  dV<% H c  Thus  a  mass  balance f o r  yields  + 2  ^  (  g  V  c  (6.37)  H,O  Rearranging, 0  =  C H 0  (V ) g  T T  at  b  C  +  2  + C H  b  C  J  ) + V  2  3- c  (6.38)  +  b  c  b  dt H d t ^H 0 o f t h e Water-Gas R e a c t i o n U  6.1.1.1.5.1  2  Equilibrium  Following  from the assumption  secondary bubble  a fourth  ^  (C  (C  b  )  and  b Q  it  + H 0 = H  follows  K  2  6.39  of t h e water-gas  P  2_  CO  b Q  ),  ^  (C  b Q  reaction: .  2  that; H  (C  within the  ), c a n be d e v e l o p e d .  + C0  2  of e q u i l i b r i u m  equation i n  From t h e e q u i l i b r i u m CO  2  CO, P  H 0 2  c  b  c  b  C  (6.39)  b  (6.40)  c CO  b  H 0 2  109 Differentiating b d_ ''CO d t  b H 0  c k  6.32  and r e a r r a n g i n g d_ dt  2  b CO  =  C  b C0  d _ _b dt H C  2  b +  2  H  d b dt C0 r  C  2  2  (6.41) Combining E q u a t i o n s equilibrium,  (6.33),  Equation  (6.36) a n d (6.38) w i t h t h e Water-Gas  (6.41)  gives  four  equations  in  four  unknowns;  K A  h  Q— " ir  6.32 C O C  - '>  ( D i  D  +  K  6 . 3 2 H^O > C  " CO 2  D  C  \  dt^coj "  C  dt^co'  D  > H >  C  C0  +  K  2  6.32 H 0 C  +  K  2  D  +  D  '>  6.32 C 0 C  C  D  2  + 2  D  3 " fe< So>  b  ( c ( C  dt  H  < * " * 2  .  . . (6.42)  .  . . (6.43)  i - 2 3 ar <co> D  + D  +  c  (6.44)  2  and, dt  U  H 0  dt  2  U  .  C0,  . . (6.45)  where D„  *dt  1  V 1 V  g  9  ) V  (V 1  d dt  n  (6.46)  'H,  ZnO  +  n . + Pbo n  A  Fe o;  St <V  2  C CO D  C  + 2C + C ^ C0 H 0 b  +  C  b  +  L  2  (6.47) and D_  B  6.1.1.1.6 There nitrogen.  +  S  fe <V  c  co  +  'CO  .  . (6.48)  Na B a l a n c e i s no i n p u t , o u t p u t , Thus:  g e n e r a t i o n or consumption of  110 d_ dt  N  2  (6.49)  g  -C S i -  dt  (  (C  b  N > C  — V  )  2  6.1.1.1.7  (6.50)  — (V ) dt q' K  Bubble Radius  Following  from the assumption of s p h e r i c a l geometry, the gas  volume c a n be w r i t t e n a s 4 3  4 — 3  Differentiating  and  d_  3 P  (6.51)  rearranging  7 Jr(V ) + 4 dt g  6.1.1.1.8  Char P a r t i c l e  Relating follows  r  the radius  r  2  dt  (6.52)  r j  Radius  of the char  particle  to  i t s weight, i t  that: .  It  is  assumed t h e  of t h e o r i g i n a l  d_ dt  , p'  t r  d e n s i t y of the char  coal.  1 4  p  i s equal  to that  Differentiating  2 r  particle  . . (6.53)  1 d_ . p c d t p' l  (6.54)  111 6.1.1.1.9  Char  Assuming to  the rate  Particle  that  Weight  the char  particle  o f t h e Boudouard  loses  and c h a r - s t e a m  weight  i n proportion  reactions  i n follows  that:  TZiV)  at  = -(B„ +  p  S )  W ,  * 12.01  r pwp  r  J  C  A  P  . . . (6.55)  where  =  CAP  the weight after  J  =  PWT  of carbon remaining i n the char  pyrolysis,  the i n i t i a l  particle  weight  after  pyrolysis  (carbon plus a s h ) . The  f a c t o r 12.01  6.1.1.1.10  The reduction For  of carbon  i n kg/kg.mole.  Gas Volume  s e c o n d a r y b u b b l e g a s volume c h a n g e s reactions  conditions  bubble  i s the m o l e c u l a r weight  a n d , t h e Boudouard  when t h e p a r t i a l  i s below t h a t  2  ''gen  A  ZnO  2 A  PbO  char-steam  pressure of lead  in equilibrium  +  and  as a f u n c t i o n  with l i q u i d  2B + 2S. r  of the  reactions.  i n the secondary lead:  (6.56)  112  g, "cons  ZnO  A mass b a l a n c e  ZnO  PbO  r  f o r the secondary  PbO  r  r  (6.57)  r  bubble  dt  g  yields: (6.58)  g  Rearranging,  dV<V £•  n„ _ + n „ . _ + B + S ZnO PbO r r  =  (6.59)  g  where P  i s t h e m o l a r gas d e n s i t y a t  g  For  c o n d i t i o n s when t h e p a r t i a l  in e q u i l i b r i u m with bubble  temperature.  liquid  pressure  of lead  l e a d , a mass b a l a n c e  equals  that  f o r the secondary  yields  n„ _ + n . ZnO PbO n  + B  n  v  r  + S  It  r  ( P  a  dt Substituting  Equation  g  .  V  . . (6.60)  g  (6.27) i n t o E q u a t i o n  (6.60) and r e a r r a n g i n g  gives  dT V (  6.1.1.1.11 The the  =  Initial  initial  original  ZnO  m  r  r  .  . (6.61)  Conditions  g a s volume  procedure  and c o m p o s i t i o n  of Richards  la  are calculated  Equations  using  (6.7) and (6.8)  113 a r e assumed on  t o be  the v o l a t i l e  This yields  a t e q u i l i b r i u m and  constituents,  five  equations  a mass b a l a n c e  oxygen,  and  five  nitrogen  unknowns, C  is  and , C  b  L.U  b C„ # 2° rt  H  b C„ 2  .  The  and  lead  vapour  hydrogen. ,  b  C„ "9  ^^9  concentrations  are  N  assumed t o  be  the  gas  initial  zero.  and  initial  values  initial  amount o f  6.1.1.1.12  The  carbon of r  liquid  necessary  found.  The  follow  from  r ^ a l s o may lead  be  initial a  charge  particle  mass b a l a n c e .  calculated.  i s assumed  t o be  The  Finally,  the  zero.  Data  thermodynamic  data  together with  references  6.1.  calculation straight  r a t e s o f FeO  A review  of the  a significant s l a g s may  be  gas c o n c e n t r a t i o n ,  Mass T r a n s f e r  a relatively transfer  and  p  Thermodynamic  6.1.1.1.13  e s t a b l i s h e d the  content  shown i n T a b l e  The  Having  volume c a n  weight  are  zinc  conducted  be  of the  mass-transfer  forward and  Fe °3  the  associated with was  l  s  m  o  r  accounted  Calculation  by R i c h a r d s ferric  ZnO  and  PbO  of the  is  mass-  complex.  e  2  literature  p o r t i o n of  This behaviour  exercise.  r a t e s of  iron  has  indicated  that  present  in zinc  fuming  l a  non-stoichiometric wustite f o r i n the  original  (Fe  Richards  1 3  x  0). model  114  TABLE Thermodynamic Data  6.1  for Reactions.  AG°  =  & H ° - T As°  H° Reaction Z n  <9)  (J)  + 1 2 °2  =  Z n 0  (s)  1 2 °2  =  P  ( l )  =  C 0  2(g,  c o  (g)  + c  +  c  +  1 2 °2  =  +  1 2 °2  =  +  1 2 °2  3  3 2  =  H  2  P e  2  P  (s, e  (s )  +  °2  °2  H  b  0  2°(g)  FeO. . (s) P e  2°3(s)  -460240 -181167 -395350  S° (JK  )  -198.3 -68.03 0.544  Reference 36 36 36  -114390  85.75  36  -247484  -55.86  36  -264889  -65.35  42  -814123  -250.66  36  'Standard states f o r gases a r e the pure gas at 1 a tin a t t e m p e r a t u r e , f o r t h e l i q u i d s , t h e p u r e l i q u i d a t t e m p e r a t u r e and f o r the s o l i d s , the pure s o l i d a t temperature.  115  TABLE 6.1 CONT'D  Activity Coefficient of Slag Species  Species  Activity Coefficient  ZnO  InV  PoO  In^nun PbO  ^  V  F  e  Q  -  7 n  3 (1)  1 6 4 0 0  ^ ? I" T  "1  (S  "  1 2 0 0 0  - 10.75 (S-) • 8.8  (XCaO/XSiO,) - .37<XFe/Hi0J • 0.27 2 2  Reference  la.37,43  39  a n d V p ^ ^ have been c a l c u l a t e d usLng the t h r e e - s u f f i x Margules model e  0  44 developed by Goel et a l . Fe 0 2  3  where S* = the eolar ratio of Ca0/Si0  2  •Standard states for liquids are the pure liquid at teiperature and for solids, the pure solid at tenperature.  116 by r e w r i t i n g E q u a t i o n Pe 0 2  +  3  (6.3)  i n the  form:  (3 - 2/X)CO = ( 2 / X ) P e 0  + (3 -  x  2/X)C0  (6.62)  2  In a d d i t i o n  t o making m a s s - t r a n s f e r c a l c u l a t i o n s more cumbersome,  there  some  are  problem,  as  fundamental  indicated  by  problems Richards,  with t h i s approach. is  the i m p l i c a t i o n  One that  2+ diffusion  of  Pe  i s occurring  c l e a r l y not p o s s i b l e . influence  that  the  A second  F o r example,  for  (6.64) c l e a r l y  following  modified  problem,  section  tends to  not  has on  i s the chemical  0.667 t h e d r i v i n g  force  zero.  i s necessary to resolve discusses  gradient-  considered  factor  as x approaches  A d i f f e r e n t approach The  a concentration  non-stoichioroetric  potentials. Reaction  against  the  method  these  problems.  followed  i n the  model.  6.1.1.1.13.1  Mass T r a n s f e r  To a c c e s s  the  o f F e * and 2  influence  on t h e m a s s - t r a n s f e r  of F e 0 2  3  b r o k e n down i n t o t h e f o l l o w i n g  2Fe  °  2  3+ (si)  " < s i r  +  1/2  0,  3  of the n o n - s t o i c h i o m e t r i c and  FeO,  Reaction  more f u n d a m e n t a l  2Fe  2e  Fe *  2+  + 2e  (si)  factor  (6.3) must  x be  reactions:  (6.63)  (6.64)  117  and, CO. (  On  the  . + 1/2 g  2  basis  reaction  0  )  of  =  o  this  between  force  the  is  breakdown  the  3+ established  by t h e Fe  secondary  that  the  reaction.  difference  Moreover,  i n oxygen  bubble.  overall  The  potential former  is  latter  by  2+ /Fe  r a t i o i n the  t h e CO2/CO r a t i o i n t h e s e c o n d a r y  s l a g and  the  bubble.  From t h i s s i m p l i s t i c a n a l y s i s Firstly,  i t is clear  oxygen exchange  s i m p l y the  s l a g and  . . . (6.65)  2  e s s e n t i a l l y i s an  the d r i v i n g  CO,. (g)  (g)  several  comments  i s expressed  can  i f the  s l a g composition  , then  c l e a r l y the s t o i c h i o m e t r y of R e a c t i o n  be  i n terms of  made. Fe  3 +  2+ and  Fe  a p p l y and case,  would be  independent  Reaction  (6.3)  o f x.  is  Since  applicable  Secondly,  i t i s evident that  of  must  calculated  transfer need  slag rates.  be  For  for t y p i c a l zinc [i] [ii] fiii] [iv]  the  t h i s purpose, fuming  slag  in the  is in  for  calculations. the  this  the  order  (6.3)  fact  potential  to determine  slags:  c o e f f i c i e n t of  the a c t i v i t y c o e f f i c e n t the e q u i l i b r i u m  constant  of  Fe O, x  Fe 0 , 2  3  f o r the  mass-  information i s  composition,  the a c t i v i t y  the  mass-transfer oxygen  following  would  reaction:  118 P e O = 1/2 0 x  2  + xPe  . . . (6.66)  and, [v]  the e q u i l i b r i u m constant Fe 0 2  Clearly  • 2Pe + 3/2 0  3  two o f t h e s e  coefficient (6.65).  of  F  e x  of w u s t i t e  ° /  a  n  The b e s t in  the e q u i l i b r i u m  d  slags  the case,  these  approximating t o FeO  relative  thermodynamically.  alternative  other  n  From  F e  2°3  Fe0 "  the  positive  interface  =  A  A  b  zinc  b  k  k p e  2  in  3  through  i n the  coefficient (see Table  state.  f o r Reaction  Therefore,  2  This  (6.66) a l s o  order  there  is  to  be  little  calculations.  the s l a g  to the  may be c h a r a c t e r i z e d e m p i r i c a l l y a s  3  stoichiometry  direction  f o r Reaction  fuming s l a g s  . . (x=l) (s)  o f FeO and F e 0  ,sl -Fe 0  2°3  Fe 0  FeO  (6.67)  the a c t i v i t y  are not a v a i l a b l e  t o s e t x=l f o r mass-transfer  mass t r a n s f e r  bubble s l a g  "  than  constant  , .as t h e s t a n d a r d (s)  to  consistent  on x:  f o r the a c t i v i t y  the e q u i l i b r i u m constant  must be e v a l u a t e d  The  values  reported data  6.1), a r e g i v e n r e l a t i v e ' * being  . . .  2  q u a n t i t i e s a r e dependent  Unfortunately,  literature.  f o r the r e a c t i o n :  2  'FeO  of  '  3  F e  ,sl 'FeO  Reaction  .  . . (6.68)  .  . . (6.69)  2°3  (6.3)  and  t o be away f r o m t h e b u b b l e s l a g  assuming  the  interface, i t  119 follows  A  that  FeO  "  Pe 0  2 A  2  Substituting  .  . . (6.70)  3  Equations  (6.68) and  (6.69) w i t h E q u a t i o n  (6.70)  yields 2k - ^ 3 FeO  'FeO  (C  k  P e  - C  s l  2°3  F e  ) +  1  2°3  C F  e  s l 0  (6.71) Since Equation  (6.3) i s a t e q u i l i b r i u m  at the bubble-slag  interface 2 K  6.6  a p e  P FeO  3  C 0  2°3  P  Combining E q u a t i o n s  c  2  (6.72)  0  (6.71) and  ( 6 . 7 2 ) , and  solving  f o r C_ F e  _ 2°3  yields  -  0  "  D  6  " 5 D  ( C  (6.73)  Fe 0 ) 2  3  where D. = K, _ P* * 2°3 4 b. o s i H FeO F  e  x  2k  Fe 0 2  5  D  6  D  C S  Fe 0 2  C  (6.74)  0  PCO,  .  3  kFeO  "  P  + 3  C  FeO  . . (6.75)  (6.76)  120  Equation  (6.69)  C*  _ and 2°3 c a l c u l a t e n„  can  then  be  solved a n a l y t i c a l l y  substituted  back  into  or  numerically  Equation  for  (6.68)  to  F e  rt  2°3  F e  6.1.1.1.13.2  In  Mass T r a n s f e r  order  necessary  to  Richards.  The  characterized  The  diffusivities  ,  Ap # b 0  method o f c a l c u l a t i o n  and  A  p e  sphere,  the  it  is identical  The  be  calculated  from  are  those  by R i c h a r d s .  used  ,  coefficients:  mass-transfer  (6.13)-(6.15).  Q  k  is  znO'  t o t h a t of  secondary  bubble  coefficients necessary  Equations Due  are  physico-  (6.10)-(6.12). to a l a c k of  f o l l o w i n g a s s u m p t i o n s have been made:  D  Zn0 " FeO  ' ' '  (  6  '  7  7  )  D  Pb0 * Fe0  ' ' •  (  6  '  7  8  )  '  (  6  '  7  9  )  D  D  D  Fe 0 2  p e 0  Z n Q  the mass-transfer  by E q u a t i o n s  data can  d a t a , the  D  A  S i n c e , as d i s c u s s e d p r e v i o u s l y , the  behaves as a r i g i d  chemical  calculate  to calculate  k..,,, k_ _ . PbO Fe_0^ Ia  Coefficients  * ' 0  3  1 D  FeO  i s assumed t o be  equation  f o r the  a temperature  empirically  self-diffusivity  r a n g e o f 1250  to  c h a r a c t e r i z e d by t h e f o l l o w i n g of  iron  1540°C.  3 6  i n a CaFeSiO^ melt  over  121  log  2  where D Fe^ 9  +  =  5450^t- $20.  5  i n units  are the  occurring  rates  on t h e  „  _+ 37  ( .80)  0 >  6  2 of m / s .  terms t o e v a l u a t e d  model  reactions  »  p e Q  Boudouard and Char-Steam  last  reaction  log D  i s expressed  6.1.1.1.14  The  +  Reactions  in  of  the  the  char  particle  - slag  Boudouard and char-steam  char p a r t i c l e .  From  Skinner  and  37 Sraoot  , for a pulverized  mesh),  the rate  quantity as  bituminous  coal  o f t h e Boudouard r e a c t i o n  of carbon  left  char  (70% through  is first  u n r e a c t e d and t h e p a r t i a l  order  pressure  -200  i n the of C 0  2  follows B  =  r  where A  B  o  A® e x p (E® /RT)  = 3.13 x 1 0  6  E® = 1*6200  As a n a d d i t i o n  . . . (6.81)  ( k g mole  ( k J kg  to Richards  1 3  kg m o l e "  mole  - 1  1  kPa  - 1  S  - 1  )  )  model, t h e c h a r - s t e a m  r e a c t i o n has  37 been  included.  bituminous first  Again  from  coal char, the  order  in  the  S k i n n e r a n d Smoot rate  quantity  of  the  of carbon  , for a  char-steam left  pulverized reaction i s  u n r e a c t e d and t h e  122 partial  pressure  S = A* exp o  where A*  E  = 1.0  of  ( E * /RT) a  x 10  = 183739  s  K^O:  P„  2  (kg mole kg  6  (kJ kg.  . . .  ft  mole  - 1  kPa  (6.82)  S )  - 1  _ 1  mole" ) 1  £1  6.1.1.1.15  The of  Model  r e s u l t i n g model  thirteen  using  a  ordinary  fourth  available  6.1.1.2  Solution  The  UBC  Having completed reaction  mass b a l a n c e s  on  problem  equations.  Runga-Kutta technique  K i n e t i c s of  particle-slag  initial-value  differential  order  through the  i s an  Computing  Lead  the  a  system  T h e s e were  solved  i n double  percision  Centre.  Removal  addition  m o d e l , an  operating  in  of  lead  reduction  t o the  i n t e r e s t i n g problem a r i s e s  furnaces  indicate that  a l l of  the  38 reports  to  fume.  removed  from the  The  question  furnace?  i s how  i s the  liquid  lead  char since lead  123 W i t h i n the be  left  are  behind  after  released  prill" by  then  slag  to  will  i n the  will  react  Pe 0, ^ ^(si) o  By  this  bulk as  the be  c a r r i e d back down i n t o  slag.  I t i s proposed,  with  the s l a g v i a the  + Pb.,. ' '  metallic  Obviously,  the  at  rate  reaction  In  which  model has  6.1.1.2.1  The  order  the  i n the  Lead  be  therefore, following  with  play  an  that  to account  will the  removed,  role  proceed.  bath be  lead  reaction:  secondary  (6.83)  into in  bubble  the  part, slag  in determining  A lead  f o r these  prill-slag kinetics.  Model  mathematics  lead  lead  i s oxidized and  "lead  of the  . . .  important  Reaction  present  of s p h e r i c a l  the  will  been d e v e l o p e d  Prill-Slag  prill  re-reduced  oxidation  lead  bulk  will  bubble  resulting  the m e t a l l i c  lead  as  t o s i m p l i f y the  metallic form  will  The the  lead  secondary  = 2PeO. + PbO. (si) (si)  o f t h e s l a g where i t c a n  kinetics  liquid  of the  atmosphere.  Thermodynamically  reactions,  is  furnace  mechanism, t h e  vapour.  that  o f t h e p r e s e n t model t h e  the gaseous c o n t e n t s  motion.  unstable prill  context  involved,  i t i s assumed  i n the  f u r n a c e a t any  prills  w i t h an  average  given  time  radius,  124 Diffusion step.  This  place  within  r a p i d l y at system  the  i s assumed t o  itself  and,  Mass B a l a n c e  lead the  establishes  i n the  the  lead  6.1.1.2.1.2  The  rate can  be  Mass  ft  rates  e m p i r i c a l l y by  =  k  n  PbO  K  n  Fe 03  k  PeO "  K  2  A_  P b O , P b *Pb  Pe 0 , 2  of  Fe 0 2  of  determine the  oxidation 3  i n the  liquid the  at a  slag.  lead  per  overall  3  c  ifPh  furnace.  1  u  PbO,  FJ  PeO  F e ° 3 and 2  following C  -  PbO  C  Pb  F e O , P b T>b  the  [ C  1  of  u  g  "  u  equations:  * ' '  J  C  can  1  s l  PbO  PeO  i£$  FeO  J  1  • •• * ' *  rate This prill  rate  Transfer  mass-transfer  proceed  Lead  rate  within  take  resulting reaction  i s consumed by  to  need  6.3.  back o x i d a t i o n  used  the r a t e - l i m i t i n g  (6.83) s h o u l d  The  Liquid  prill  of  oxidation  characterized  on  be  mass-transfer  Reaction  in Pig.  mass - t r a n s f e r  therefore,  metallic  no  fuming t e m p e r a t u r e s .  i s shown s c h e m a t i c a l l y  to  n  slag  unreasonable since  prill  slag  Liquid  and,  the  i s not  6.1.1.2.1.1  equal  in  be  of  126 From t h e s t o i c h i o m e t r y Fe 0  n  2  "  3  PbO  A  of Equation "  =  n  (6.83) i t f o l l o w s  FeO  that:  * * * < - > 6  a n d , f r o m t h e assumption- o f l o c a l  8 7  e q u i l i b r i u m a t the p r i l l - s l a g  interface,  FgQ  ( C  ^  P b  °PbQ  Combining E q u a t i o n s  =  b  K  6.78 ^  P e  2°3  ( P  "j  . . (6.88)  ) 2  (6.84) - (6.88) a n d s o l v i n g f o r C „ r e  i t can  n  2 3 u  be shown t h a t  o=i  D  9  -  D  (  7  c*;*^ ,  )  2  i  D  1  -  0  D  (c*;^)i -  8  4 ^D e  .  liy  . . (6.89)  where 2 k  D  Fe  -  ?  2"3 k  D  =  g  k F e  k  9  - 7  10  " 8  D  D  D  D  X 1  D  Equation .  n  2  3  . . . (6.90)  FeO 2°3  . . . (6.91)  PbO  ( C  ?e 0 2  )  C  2  = "6.78 2  (6.89)  +  C  3  < Fe 0 >  #  ci Fe 0  O  3  +  FeO  C  ' * *  P*0  ' « '  "2"3 ^ s l ' Fe O  (  6  < 6  *  9  2  '>  )  3 )  . . . (6.94)  o*PbO  c a n be s o l v e d  analytically  The r e s u l t i n g v a l u e o f C* Fe 0  numerically  for  t h e n c a n be s u b s t i t u t e d  rt  2  or  3  into Equation be  (6.85).  Only  coefficients  remain  determined.  6.1.1.2.1.3  On  k  Mass-Transfer  the b a s i s t h a t  creeping  Coefficients  the  lead  prills  behave a s  flow, the m a s s - t r a n s f e r c o e f f i c i e n t s ,  , are c h a r a c t e r i z e d F e  the m a s s - t r a n s f e r  empirically  k  p  rigid b 0  by E q u a t i o n s  spheres  *  k  FeO'  a  in n  d  (6.13)-(6.15).  2°3  The  necessary  Equations used  physico-chemical  (6.10) -  (6.12).  i n the c h a r - p a r t i c l e  6.1.2  The  The kinetics  Furnace  the m e l t i n g  a r e unchanged by interested of R i c h a r d s  The  1 3  the  of s l a g  is referred  furnace heat  f o r the  review  column,  be  are  calculated  the  same a s  from those  model.  bubble  and  on t h e  incorporation  of  to the  and  residence time,  f u r n a c e w a l l s and reduction.  original  lead. will  the  characterization  bottom  Thus  mathematical  of  the  model  material.  mass b a l a n c e s  e x e r c i s e and  of the mathematics  the  lead  of t h i s  r e d u c t i o n of  l a r g e l y a book k e e p i n g general  reaction  f o r the treatment  overall  to account  slag  gas  freezing  reader  Diffusivities  of the secondary  tuyere  and  can  Model  calculation of the  data  must  be  modified  These m o d i f i c a t i o n s are n o t be d i s c u s s e d .  i n v o l v e d i n the  overall  For  a  furnace  128 heat  and  treatment  6.2  mass b a l a n c e s of  the  t h e model  pressure coal  of normal  furnace.  There  model  in  entrainment  The until  procedure  as t h e  of bath  fraction  fraction  of  two  in  original  was  for  Cominco  low-pressure  low-pressure  coal  the  for this:  r e d u c t i o n has  on  fraction  The  of  latter  was  calculation  of  coal.  L  P  C  /  E  F  LPCC  a  between measured and temperature. coal  2 to  the  slag.  No.  firstly,  to determine  to adjust P  and  high-  to f i t i t to a  a b a s i s f o r the  obtained  the  necessary  f o r the h i g h - p r e s s u r e  adopted  analyze  of l e a d  the  provide  composition of  to  main r e a s o n s  secondly,  to  good a g r e e m e n t was  profiles  i t was  practice  entrained  order  factors  trials,  and  coal  applied  t h a t the a d d i t i o n  predictions,  low-pressure  be  fuming  were  the e f f e c t  necessary  t o the  Fitting  could  injection  run t y p i c a l  elucidate  is referred  Richards.  D i s c u s s i o n o f Model  Before  reader  F  LPCE  entrained,  c o m b u s t e d ; and  F  f  n  d  oxy  F  predicted I  S  A  LPCC  i s the  E  I  S  F  I  N  T  E  N  A  E  fraction  oxy of  remaining  oxygen is  oxygen which  unconsuroed b y c o a l  oxy  iron  i s d e f i n e d as t h a t p o r t i o n o f t h e t o t a l  Within the F  oxidizes ferrous  can  be  (the  remaining  i n p u t oxygen  which  combustion.)  computer p r o g r a m , v a l u e s  for  p  LPCE'  F  LPCC'  input f o r each s e t of o p e r a t i n g c o n d i t i o n s ( c o a l  A  N  D  rate  and  secondary  blast  is a variation corresponding this  way,  rate).  Therefore,  i n the  the best p o s s i b l e f i t  Three analyzed  be  fitted  run  not  low-pressure l  a  runs,  p r e v i o u s l y analyzed  indicative  primary  fitting  for  given  a  It  is  two  there have a  parameters. set  In  of o p e r a t i n g  o f w h i c h have been p r e v i o u s l y  were a v a i l a b l e  to a l l three runs;  discussion.  where  obtained.  by R i c h a r d s  was  runs  i n operating, c o n d i t i o n s , i t i s p o s s i b l e to variation  c o n d i t i o n s can  f o r those  felt  for analysis.  however,  by R i c h a r d s that  of normal o p e r a t i o n  o n l y the  the  and,  will  1 3  results  be  other  The  two  therefore,  model f o r the  presented  for  runs  not  do  were  not  warrant  detailed discussion.  6.2.1  R e s u l t s o f F i t t o Normal  The presented fitting with the the of  of  in Figs.  6.4-6.6  parameters,  fitting The  ^pcg/  * " L P C C  p r e d i c t e d furnace  purpose  should  the  by R i c h a r d s  be  also  mentioned  n e c e s s i t a t e d the  use  the average r a d i u s of the  the  model  to a  3  n  d  F  oxy  results  a  r  e  s  u  m  r  a  f o r the a  r  i  of the  inclusion  additional  lead p r i l l s  (r  Pb  z  d  e  i n Table  are  primary  together 6.2.  For  original analysis  have been p r e s e n t e d  t h a t the  o f two  "normal" run  predicted values  oxygen u t i l i z a t i o n  of comparison,  the process  It has  results  Operation  of  fitting ), and  i n Table  6.2.  lead reduction parameters: the  initial  TABLE 6.2 130 Model F i t t i n g Parameters  Normal Operation F r a c t i o n of low-pressure coal entrained (Richards) F r a c t i o n of high-pressure coal entrained F r a c t i o n of low-pressure coal combusted (Richards) F r a c t i o n of high-pressure c o a l combusted F r a c t i o n of uncombusted oxygen to f e r r o u s iron oxidation (Richards) Radius of Pb p r i l l (ra)  Run 1  Run 2  Run 3  0.27  0.27  0.27  -  0.75*  0.65  0.90  0.40-0.65  0.50-0.54  0.2-0.32 (0.29)  0.70-0.50  0.70  (0.54)  -  0  0.03-0.30  0  0  0.15-0.50  0.75-0.10  0.55-0.30  1 x 10~  1 x 10~  1 x 10~  (0.04)  1 x 10"  3  3  3  I n i t i a l fraction of Pb as metal  0.10  0.10  0.90  0.50  Slag c i r c u l a t i o n v e l o c i t y (m/sec) (Richards)  3 (1)  3  3  3  P r e d i c t e d oxygen utilization  0.55-0.75  0.62-0.85  0.65-0.95  3  0.78-0.92  * T h i s value was obtained using a term to account f o r the melting of z i n c - r i c h m a t e r i a l at a r a t e of 0.3 x 10 kg mole Zn/s  Figure  6.4  I n d u s t r i a l data and model f i t to the Zn and Pb p r o f i l e s for normal operation  q to  FE2»/FE3«  CU UJ L 1 NES-MOOEL  . b  P O I NT S = A S S O T  q IT)  q d 0.0  i 10.0  i  i  20.0  30.0  i 40.0  i 50.0  i 60.0  ELAPSED  Figure  6.5  I 70.0  I 80.0  I 90.0  I 100.0  I 110.0  I 120.0  I 130.0  140.0  TIME(MIN)  I n d u s t r i a l d a t a and model f i t t o t h e Fe p r o f i l e s f o r normal o p e r a t i o n  2+  and  Fe  3+  LINES=MOOEL P O I NT = o s s n r  o  XL  -©  e-  0~  -r0.0 0.0 1  T  20.0 30.0 40.0  T  6.6  T  T  <)  50.0 60.0 70.0 80.0 90.0 100.0 110.0 120.0 130.0 140 ELAPSED  Figure  T  O  TIME(MIN)  I n d u s t r i a l d a t a and model f i t t o t h e t e m p e r a t u r e p r o f i l e f o r normal o p e r a t i o n  134 fraction  of  m e t a l l i c l e a d Fpg^  •  The  latter  necessary since a s i g n i f i c a n t portion  of  the  of  t h e s e was  lead charged  deemed to  the  39 f u r n a c e may  be  present  i n m e t a l l i c form.  The  values  for  Pb Tp  Fp k  and  6.2.1.1  also provided  Discussion  The  f i t of  good, see three  are  B  of  F i t t o Normal  model  prediction  6.4-6.6.  Figs.  primary f i t t i n g  of  t o 0.32  one  F  run,  Q  x  ),  y  0.37  (0-20  and/or  the  suggest  under r e d u c i n g p  zinc  F  be  a real effect.  C  K  are  variations  fuming  in  the  coincident Not  F „ „ ^ and T  behaviour  could  model, r e a l e f f e c t s , or  t o be 0  ,  3  8  t  o  varied 0  •  6 5  P  on  the  rates  on  f a c t o r of is  (20-40  the  in coal  basis  is  conditions; elapsed  fuming  rates  changes  i t could  the  F  is  the  of  weaknesses w i t h i n  there  of  model  surprisingly, -  same  d  of  predicted  rate  n  factor  rains,  overestimating  Moreover, s i n c e  a  the  the  oxidizing  0.23  the  implications  indicate that  under  over  LPCC  higher entrainment  w i t h changes  urLL  their  n o t e d , however, t h a t a l l  to speculate  model  i s reasonably  Unfortunately,  time} c o u l d  conditions.  in  be  LPCE'  F  example, t h e  lower entrainment  time) could  L  For  mine, e l a p s e d  underestimating  measurement  6.2.  Table  difficult  these v a r i a t i o n s .  to  p a r a m e t e r s have had  see  i t is  Operation  It should  course of the run ( 0 . 2 3 t o 0.37 0.03  6.2.  i n Table  holds  for  possibility  also the that  OXy  be  the  result  some c o m b i n a t i o n  of  the  two.  the  135 Having alternative can  stated other than  be a d o p t e d  fore,  this,  i t appears  t o assume a n a v e r a g e  i n the analysis  the r e s u l t s  previous  finding  of t h i s  o b s e r v a t i o n s c a n be made. that  there  is a  t o lm/s  significant  difference  This  be  and a s  such  until  Secondly,  the v a l u e s  predicted for coal  there  t h e two m o d e l s , s e e T a b l e kinetic  the  partitioning  Having now  of coal  to f i t  is a  6.2.  foundations  completed  possible  e  t  into  e  g  u  a  for P p L  little which  C B  There-  t o 0.30.  A  6.2) is  a  some  i n the s l a g  some  remarkable ( F  model  this  is a  justification. analysis  c a n be  c o n s i s t e n c y between L  p  This continues  on w h i c h b o t h  circulation  Clearly,  sensitivity  utilization  obvious  i n the present  model.  the  interesting  immediately  warrants  c  E  and  p L  to lend  p  C  C  )  with  soundness  models a r e based,  r e d u c t a n t and s o u r c e  ie.  of heat.  f i t t i n g ; t h e model t o n o r m a l o p e r a t i o n i t i s t h e model t o t h e h i g h - p r e s s u r e  mentioned p r e v i o u s l y , the v a l u e of F this exercise.  i t  Richards  completed.  the  s  difference  i n the  is  e x e r c i s e a r e compared t o  Firstly,  postponed  to  value  i n t h e two m o d e l s - 3m/s  a s compared  will  1 3  (see Table  1 9  significant  v e l o c i t i e s employed  ^PCB  fitting  of R i c h a r d s  there  of the high-pressure data.  f o r a l l subsequent a n a l y s i s  If  that  L  P  C  E  i s s e t equal  trials.  As  t o 0.30 f o r  136 6.2.2  R e s o l t a of P i t t o High-Pressure  The  results  of  fitting-  o p e r a t i o n , Runs  1-3,  predicted  f o r the primary  P __  values  and P,„  r n  urCL  are  the  Operation  model  presented  to  in  the high-pressure  Pigs.  6.8-6.19.  f i t t i n g parameters P  L p c g  ,  The F^pcE*  a r e summarized t o g e t h e r w i t h t h e p r e d i c t e d o x y g e n  OXy  utilization  i n Table  high-pressure  coal  6.2  (  p  i H  P  C  defined  s  E  entrained i n  as the f r a c t i o n of  the slag).  A summary  of the  Pb values  f o r the secondary  presented  i n Table  Before high-pressure discuss  the  f i t t i n g parameters r  proceeding injection ability  of  with  an  on c o a l  assessment o f the i n f l u e n c e of entrainment,  t h e model  trials.  t o be  This w i l l  help  of the r e s u l t s  6.2.2.1  D i s c u s s i o n of P i t t o High-Pressure  measurements  three runs quite  fuming  rate.  The  m a t e r i a l was m e l t i n g  in  i s necessary to to  each of t h e  e s t a b l i s h i n g the  analysis.  Operation  t h e model p r e d i c t i o n s a r e s e e n  well,  concentration profiles, Run 1, t h e model was  o f t h e model  i t  fitted  validity  all  a l s o are  p f i L  6.2.  three high-pressure  In  and F  p  see  Pigs.  6.8-6.19.  however, a r e t h e l e a s t  initially most  unable  likely  i n the furnace  t o f i t the  to  The  satisfactory.  account  for  the run.  In  t h e low  explanation i s that zinc throughout  zinc  rich  This i s  o L I NES = MODEL PO I N T S =  I  0.0  1  10.0  1  20.0  1  30.0  1  40.0  ELAPSED  Figure  6.7  1  1  50.0  60.0  1  70.0  flSSAY  1  80.0  TIME(MINS)  I n d u s t r i a l d a t a and model p r o f i l e s f o r Run 1  fit  t o t h e Zn and Pb  1  90  FERROUS  B  " A *  ^  2  A  L INES^MODEL PO I NT S =  i  FERRIC  - - - ,  0.0  10.0  20.0  30.0  4-0.0  ELAPSED  Figure  flSSPY  6.8  50.0  60.0  70.0  80.0  90.0  TIME(MINS)  2+ I n d u s t r i a l d a t a and model p r o f i l e s f o r Run 1  fit  t o t h e Fe  3+ and Fe  Figure  6.9  I n d u s t r i a l d a t a and p r o f i l e f o r Run 1  model f i t t o t h e  temperature  Figure  6.10  I n d u s t r i a l d a t a and model f i t p r o f i l e s f o r Run 2  to the  Zn and Pb  2+ Figure  6.11  I n d u s t r i a l d a t a and model p r o f i l e s f o r Run 2  fit  t o t h e Fe  3+ and  Fe  q d o  Figure  6.12  I n d u s t r i a l d a t a and p r o f i l e f o r Run 2  model f i t t o t h e  temperature  Figure  6.14  I n d u s t r i a l d a t a and model f i t p r o f i l e s f o r Run 3  t o t h e Fe  and  Fe  Figure  6.15  I n d u s t r i a l d a t a and p r o f i l e f o r Run 3  model f i t t o t h e  temperature  consistent averaged  with  plant  fuming r a t e  both  data which  of  from the was  0.75  to the  rate  of  introduction efficiency which and with  is  1.4  H  p  c  E  t o be  was  of  this  the  term  i s that  i s increased  (Kg  Zn  line  + Kg  theory  1  the  different  predicted  respectively.  observed  The  to  of  of  i n the  conditions  behaviour model  melting  model  (0-30  is  periods  operation,  This  and  the  model the  for  the  fuming coal  3,  1.2  consistent the  the  act  apparent  d i f f e r e n t under is  are see  to  at  occurring.  considered, Pigs.  6.10  account  for  a and the  of t r a n s i t i o n from o x i d i z i n g  w i t h what see  be  evident, unable  is  and  3  bath.  Pb)/Kg  V that  material  minutes elapsed  is consistent  to normal  is  and  + Kg  to  arrived  f o r Runs 2 and  assays) w i l l  zinc-rich  model  3)  Zn  i n Chapter  2  the  by a d j u s t i n g  predicted)  Runs  fuming r a t e s d u r i n g  to reducing  (Kg  Pb)/Kg c o a l r e s p e c t i v e l y .  zinc profiles  weakness  0.92  proposed  into  (value  6.7,  added  average p r e d i c t e d  with  originally  when t h e  the  to  that  measured  Justification  f r o m 0.77  ( t h a t b a s e d on  conditions  Pig.  bath.  fuming e f f i c i e n c y  the  zinc  f o r Run  see  into  the  c o r r e c t , a t e r m was  assumed  (equivalent  This  in  and  V).  i n t r o d u c t i o n of  fuming e f f i c i e n c y  6.13,  Chapter  zinc profile,  zinc  more i n  the  If  decrease  r e s u l t s o f model a n a l y s i s o f Runs 2 and  fitted  melt  (see  f o r the  for P  make-up, 50:50 h o t - c o l d ,  indicates a  explanation  model t o a c c o u n t  A value  charge  for c o l d charges  Assuming t h i s the  the  Pig.  time  was  in  both  observed  6.4.  in  runs). fitting  Therefore,  it  appears  that  the  underestimate  model,  fuming  in  rates  general,  has  a  ( b y a p p r o x i m a t e l y 1 wt%  tendency  to  Runs 2  and  in  3) under c o n d i t i o n s when t h e b a t h c o n c e n t r a t i o n o f f e r r i c relatively this  high.  There  behaviour  coefficient validity  including  of FejO^  of  are  several for  any  It  left  until  should  be  an  that  incorrect  model.  both P  T n  the  Therefore, discussion  will  can  over  2+  the c o u r s e  be  „ „ and  of the t h r e e  completed.  ' have had  to  be  oxy  runs  in  order  t o f i t the  3+  Pe  /Fe  and  Run  2 and  0.68  Run  2 and  0.30-0.50 Run  consistent  resulting bath  temperature t o 0.70  also  operation.  3; P  3),  Q x y  see  (  it  is  p L  :  p  c  a plot  see F i g .  oxygen  6.16.  of  coefficient  o f r=0.85.  parameters,  P  and/or  F  Q x y  and  F  o  plots  of both P  Pigs.  6.17  and  L  p  c  c  6.18,  x  , y  are  R  U  1  '  °' 1,  to  utilization  note  7  is  normal  that  the  with decreasing on a  run-to-run temperature  of the d a t a  To d e t e r m i n e  f o r the yields  which of the for  versus temperature on  °"  behaviour  versus  responsible  ~  0.1-0.75  o p e r a t i o n run  Based  5  t h e model t o  the c o r r e l a t i o n  respectively.  n  Run  decrease  the normal  correlation  5  This  fitting  Linear regression  h i g h - p r e s s u r e r u n s and  L p c c  °*  interesting  assess  of p r e d i c t e d  :  6.2.  v a l u e s f o r oxygen u t i l i z a t i o n To  c  0.15-0.5  Table  the r e s u l t s  Moreover,  made,  three  profiles  Run  with  temperature.  basis, was  owing  the  to  Lifoo varied  activity  to assess  explanation,  a sensitivity analysis  noted  explanations for  It is d i f f i c u l t  other  c o m p l e x i t y of the mathematical have t o be  example,  i n the s l a g .  this,or  possible  iron is  this  two  trend,  were made, this,  a  see  i t appears  1.0  §  Z  0.9  0.5  A  Normal  • O O  Run I Run 2 Run 3  operation  0.4  0.3' 1200  1  1 1250 Bath  Figure  6.16  1300  temperature  1350  (°C )  P r e d i c t e d oxygen u t i l i z a t i o n of bath temperature  as a  function  i  i  r  T  0.9  0.8  o o  0.7  0.6 (J  u  Q_  0.5  •  AO  0.4  0.3  A  Normal  • O O  Run I " 2 " 3  operation  0.2  J 1200  1250 Bath  Figure  6.17  I  P, , Df  r  I 1300  temperature as a f u n c t i o n  L 1350 (°C)  of bath  temperature  1  0.8  1  1  1  1  O  0.7 o 0.6 O  o  0.5 > x o LL-  0.4  •  —  —  /u A ,00  —  A  /  —  A  Normal  •  Run  O  Run  2  O  Run  3  0.2 CK  0.1  /  o  1  1 1250  1200  Bath  Figure  y /  An  —  o 0.3  o  6.18  F  oxy  1  operation  1  1  1 1300  1350  temperature ( ° C )  as a f u n c t i o n  of bath  temperature  151 t h a t the r a t e of o x i d a t i o n of  ferrous iron  (established  by F  ) oxy  is  sensitive  that  the  t o bath  kinetics  temperature. resulting increase  the  the be  reaction  example,  an  in  bath  diameter  possible explanation i s are  sensitive  increase  in  of the  bubbles  of tuyere  sensitive  t o bath depth.  investigation  gas  of  to  bath  temperature  kinetics  original  bath  viscosity  could  cause  i n the tuyere  This trend  was  process  gas  If this  o x i d a t i o n of f e r r o u s  the  an  is  iron  observed  by R i c h a r d  et  b  al*  '  data  to either  Unfortunately, there  Having  completed  influence  high-pressure  essence  of t h i s  6.2.2.2  data,  for  the  a significant  Predicted  values for  3 respectively. predictions  The  experimental  findings.  o f t h e model a n a l y s i s now  injection  possible on c o a l  to  of  the  assess  the  entrainment  P  C  r  e  E  It is felt for  value  Entrapment  high-pressure  a H  Operation;  improvement  P  high-pressure  behaviour.  is  enough  -  the  study.  indicate  uniform  it  P i t to High-Pressure  Predictions  since  lack of  a discussion  trials  of  is a  c o n f i r m or r e f u t e t h e i r  high-pressure  and  One  therefore, a reduction i n mass-transfer.  should  la  Por  this  i n the average  the case,  in  of  from a decrease  c o l u m n and,  also  temperature.  0.70  that these rates  injection 1,  entrainment  i n entrainment,  0.75,  fuming  f o r Run  coal  and  0.90  however,  see  those  well  factors  Table  f o r Runs  valves are  during  agree  Factors  1,2  reasonable periods  with  i s suspect  6.2.  of  furnace  in light  of  152 the a d d i t i o n material.  of a  tern to  The d i f f e r e n c e  3 is  believed  depth  (mass) and t h e l o w e r  is  reasoned  to  that  high-pressure coal  be due  this  account  f o r the m e l t i n g of z i n c - r i c h  i n the v a l u e s p r e d i c t e d to a  combination  high-pressure coal  of  f o r Runs  the g r e a t e r bath  rate  combination acted t o reduce  s t r i p p i n g through  the bath  2 and  i n Run  3.  It  the p o r t i o n of  unconsumed.  153  CHAPTER V I I  S E N S I T I V I T Y ANALYSIS  For  reasons  the R i c h a r d s of  lead  from  kinetic  1 3  prior  the  stated  to  t h e model  the  estimated.  use  of  potentially  the  as  Table  7.1  significant  low-pressure  a standard.  modify  This  parameters i t  was  t o these  whose  aid  to  e s t a b l i s h the  In a d d i t i o n , the  in  identifying  any  phenomena w i t h i n t h e p r o c e s s .  o p e r a t i o n a l data  run p r e v i o u s l y analyzed The  has  v a l u e s c a n o n l y be  parameters. to  data  modification  necessary  necessary kinetic  to the i n d u s t r i a l  data  from  this  run  i n Chapter  from  VI was  are presented i n  7.1  Sensitivity Analysis;  The to  was  fitted  c a r r y out the s e n s i t i v i t y a n a l y s i s ,  normal  used  of  t h e model  sensitivity analysis  being trials.  Consequently,  sensitivity  to  model t o i n c l u d e t h e r e d u c t i o n and r e m o v a l  high-pressure  necessitated  To  p r e v i o u s l y , i t was n e c e s s a r y  Results  s e n s i t i v i t y o f t h e o r i g i n a l model  the kinetic  previously.  l a  '  D  modified  model  kinetics  of lead  conception  of the process  Therefore, focussed  the  only  reduction  and  t o parameters  has been d e m o n s t r a t e d  sensitivity  analysis  on t h e p a r a m e t e r s r e l a t e d removal  central  from  the bath.  of the to the These  TABLE 7.1 Standard Conditions for Sensitivity Analysis  Operating Parameters: F  - 0.23 - 0.37  L p c E  LPCC  F  Slag Data:  -  = 0  F v  4 0  Initial  15.01 Zn  Composition  -°- 5 6  2+ 21.51 Fe  PBL  F  =  (  U  Assay (wt.Z)  50! Fixed Carbon 25X Vol at lies 11 Moisture  Volatile Coip. (vt.X)  501 Fixed Carbon 20Z Hydrogen 10Z Oxygen  LSI Pb  =0.03-0.32  0X  Coal Data:  0  7.01 Fe * 11.71 CaO 3  r P  Pb  Mxio' . 3  23.21 Si0  2  Furnace Dimensions: L = 8.00 •  *  4.01 A1 0  %  1.0Z S  2  Furnace Operating Conditions (see Appendix I - Normal Operation)  3  U = 3.10 •  Injection Dynamics:  Initial Teaperature = 1250°C  Slag Circulation Velocity  = 3.0 i/s  No. Tuyeres  * 74 1  E = 196200 a  -1 -1 kPa S kJ kg.mole  -1  Char-steam Reaction: 6  = 30X  D  Boudouard Reaction:  6  Porosity  3  Tuyere Column Vord Fr. = 0.600  A = 3.13 x 10 o  = 50,000 kg.  -3 Density Liquid Slag = 3600 kg.m_ Density Solid Slag = 3900 kg.m" 10.0 FE0 F E *  ii  Bubble Frequency  Initial Height  A = 1.0 x 10 o  kPaV  E = 183739 a  kJ kg.mole  1  -1  / 0  155 parameters are:  the  initial  fraction  of  lead  as  metal, F  p f i L  ,  the  Pb radius  of  the  diffusivity However,  of  in  analysis  metallic PbO  i n the  light  has  lead  of  prill,  slag the  relative  include  lij  the  circulation  velocity  (i1]  the  fraction  remaining  iron [iii]  the  oxidation,  P  p  question  been e x p a n d e d t o  of  r  Q x y  of  and  the  m a g n i t u d e of  to  that  raised other the  of  ZnO,  /  D Z  i n Chapter  n  the  C  D P  VI,  bo the  parameters:  slag,  V j g s  a  o x y g e n consumed by  ferrous  /  activity coefficient  of  Pe 0j 2  i n the  slag,  and, [iv]  7.1.1  and  PbO  0.1  - 7.3.  has  no  7.2.  influence  in  and the  of  the  obvious  both the  zinc  in F  is opposite  for  on  p B L  and  in F  fuming rate an  from  the  shown.  zinc  initial  model  effect  A decrease  i n the  to  FeO,  ZnO  Discussion  p r o f i l e , not  initial  Fe^O^  d i f f u s i v i t y of  D p . ^ -  /  p e Q  obvious e f f e c t  7.3.  decrease effect  on  the  A decrease  Mo  temperature  7.1  (D  sensitivity  Figs.7.1  Fig  magnitude of  R e s u l t s and  The  to  the  F  the  also  standard  was  T h e r e was  p f i L  is illustrated  p f i L  predicted  ferrous  lead  and  iron  in F  on a  the  p r o f i l e s , see slight  ferrous to  0.9.  in 0.5 see  bath  noticeable  simultaneously  D n r  of  profile,  however,  g e n e r a t i o n of  increase  value  observed  brought about a  rate of  to  decrease a  iron. It  Figs.  is  slight The worth  Figure  7.1  The  e f f e c t of F  D n r  on the p r e d i c t e d  Zn  profile  LEGEND INT. FRAC. PB AS METL.=0.50(STD.) • = STD.*0.2 o= A = STD.*1.8 K)  -  in <N -  CD  |  0.0  1  1  10.0  20.0  1  1  1  I  I  I"  30.0  40.0  50.0  60.0  70.0  80.0  |U  90.0  TIME(MINS)  Figure  7.2  The  effect  of F  on  the p r e d i c t e d  Pb  profile  IJi  100  Figure  7.3  The  effect  of F  p  B  L  on  the  predicted  Fe  2+  profile  159  noting only  that  short  model  of  for F  be  the  in  a short  i s high,  L  the  for  the  to  r a t e of generation  i n the  be  ferrous  not an  of the  of  ferrous  unexpected  iron is  since  the  amount  s l a g concentration i f the  oxidation rate ferrous  elevated. i n the  of  equilibrium  a given  rate  relative  also will  is  F o r example,  term r a p i d decrease  increase  concentration  toward  conditions.  lead p r i l l  and value  of m e t a l l i c  lead  reduction  and,  of iron  Since  via  oxidation  this will  amount o f  iron generation  initial  of  result  m e t a l l i c lead,  rate should  only  be  lived.  It  is  profiles This  B  move  furnace  elevated  of  short  p  the  behaviour  to  i n the  operating  therefore,  the  This  tend  lead  selected will  i n f l u e n c e on  term.  should  metallic set  the  i n t e r e s t i n g to  for  *p  -  B L  indicates that  amount o f  liquid  .l  ft  F p  B L  note t h a t and =  0.9 0.5  the  zinc  bound t h a t is  and  for F  c l o s e r to  p  ferrous B  =  L  the  iron 0.5.  equilibrium  lead.  Pb Model s e n s i t i v i t y  to r  is illustrated  7.4  in Figs.  -  7.6.  P Both  the  sensitivity In the  lead  and  to  this  case of  the  marked d e c r e a s e  iron  profiles  p a r a m e t e r , F i g s . 7.5  model p r e d i c t i o n s  i n the  a p p r o x i m a t e l y 0.75 ferrous  ferrous  wt%  iron profiles  removal for a  and  7.6,  a  moderate  respectively.  f o r lead removal, there  rate at bath  f a c t o r of ten  i n d i c a t e an  show  initial  lead contents  increase decrease  in r  P  i n the  b  is a below  •  The  rate  of  Pb generation  for  an  increase  in r  .  The  long  term  effect,  Figure 7 . 5  The effect of r  on the predicted Pb p r o f i l e  Figure  7.6  The  effect  of  r^  b  on  the  predicted  Fe  2 +  profile  Figure  7.7  The  e f f e c t of D_  Mrt  /D___  on the p r e d i c t e d  Zn  profile  164 however,  Is  only  minimal.  The z i n c  profiles,  Pig.  7.4, i n d i c a t e  Pb little was  sensitivity  investigated  worth  noting  to  (not  that  r  .  p  Temperature  sensitivity  shown) a n d was f o u n d t o be m i n i m a l . in  a l l three cases,  zinc,  lead  also It is  and f e r r o u s Pb  iron,  there The  D  sensitivity  is  p B 0  i s no e f f e c t o b s e r v e d  shown  temperature (D  Z N O  example, a wt% Fig. D  ZMO  o f t h e model  i n Figs.  profiles  ) constant,  of four  7.7 - 7.10.  The  generation  As  r e s u l f  -s  n a  n  change  in Bp  increase  mentioned p r e v i o u s l y ,  Model s e n s i t i v i t y  of  inclusion  the  of lead  circulation Richards  1 3  results  B 0  and / pg D  Z N Q  i n only  The f e r r o u s to D  p  B  Q  .  i n the predicted  the questions  an i n v e s t i g a t i o n  parameters not d i r e c t l y  One  D  of  iron  0  For a 0.5  profile,  An i n c r e a s e i n ferrous  iron  rate.  have n e c e s s i t a t e d several  *  lead  7.7, 7.8 a n d 7.10, r e s p e c t i v e l y .  7.9 shows a m o d e r a t e s e n s i t i v i t y D  zinc,  insensitive to  change i n b a t h z i n c c o n c e n t r a t i o n .  ^ PBO  i nr  t o t h e r e l a t i v e magnitude  are relatively  see F i g s .  factor  for a decrease  associated  obvious  reduction  velocity  -  was a from  i n C h a p t e r VI  o f t h e models s e n s i t i v i t y t o  t o these parameters  more  raised  with  lead  i s described  changes  Im/sec  below.  brought  substantial  about  increase  previously  t o 3m/sec i n t h e p r e s e n t m o d e l .  reduction.  by t h e i n slag  assumed  by  Model s e n s i t i v i t y t o  "1 ~  LEGEND • = DZNO/DPBO=1.0(STD.) 0 = DZNO/DPBO=0.5 |A = DZN0/DPB0=2.0  t n  Q  in CN -  q  CN -  TIME(MINS)  Figure 7.8  The  e f f e c t of D  /D  Dnr  .  on the p r e d i c t e d Pb p r o f i l  q d  o o to  O  Q  o o  CN  LEGEND • = DZNO/DPBO=1.0(STD.) C = DZNO/DPBO=0.5 A = DZNO/DPBO=2.0  O o  o o o  0.0  Figure  7.10  10.0  20.0  The e f f e c t  30.0  40.0  50.0  60.0  70.0  80.0  90.0  100.0  TIME(MINS)  o f D...,- / D  D n A  on t h e p r e d i c t e d  temperature  profile  cri -J  Figure  7.11  The  effect  of V  ,  on  the  predicted  Zn  profile  169 the  parameter  mentioned velocity in  the  is  that,  within  the  in Pigs.  context  7.11-7.14.  the  It should  model, s l a g  char p a r t i c l e  be  circulation  residence  time  bath.  be  i n mind, t h e  moderately  zinc  sensitive  decrease  i n the  zinc  time, for '  lm/sec decrease  in V  a  effect  elapsed  of  a  of  this  , . slag in V  furnace cycle  can  0 -  20  , slag  becomes mins.  times  the  Fig.  7.12,  be  seen  There  is a  mins  I t s h o u l d be  t h a n a p p r o x i m a t e l y 80  overall  7.11,  parameter.  fuming r a t e ,  2ro/sec v a r i a t i o n  times greater  predictions  profile, Fig.  to  significant  the  of  i s e f f e c t i v e l y a measure o f  With t h i s to  illustrated  elapsed  noted  that  minimal  for  Therefore,  effect  should  for be  minimal.  Ferrous  iron  more s e n s i t i v e i n the an  b a t h . The  increase  opposite Figs. the  to  7.13  slag  predictions, V  , slag  rate  in slag  to  that and  of  than p r e d i c t i o n s generation  circulation  of  zinc.  7.14,  circulation  a  of  h i g h d e g r e e of  less,  zinc,  The  to  F  lead  and  show no  considerably  zinc  concentration  iron  i s reduced  by  This  behaviour  is  temperature  profiles,  obvious s e n s i t i v i t y  to  is i l l u s t r a t e d in Figs.  0.5  7.15-7.18.  oxy lead,  ferrous  s e n s i t i v i t y to  approximately  ferrous  are  velocity.  J  profiles  of  for  velocity.  respectively,  Model s e n s i t i v i t y The  see  wt%,  and  F  Q  x  iron y  .  and  The  opposite.  t e m p e r a t u r e a l l show  s e n s i t i v i t y of An  increase  in  lead F  is  Figure  7.12  The  effect  of V  slaq  2+ o  n  t  n  e  predicted  Fe  profile  ZINC  S L A G FURNACE  MODEL  LEGEND SLAG CIR. VEL.=3.0(M/S) •= o = SLAG CIR. VEL.=2.0 A = SLAG CIR. VEL.=4.0  TIME(MINS) Figure  7.13  The  effect  of V  on t h e p r e d i c t e d  Pb  profile  q d o  q d o  -  LEGEND CIR. V E L . = 3 . 0 ( M / S ) CIR. VEL.=2.0 o= A = SLAG CIR. VEL.=4.0 SLAG • = SLAG  o  O H  o o o I  0.0  10.0  I  I  20.0  30.0  I  I  I  I  50.0  60.0  70.0  80.0  I  40.0  I  90.0  100.0  TIME(MINS) Figure  7.14  The e f f e c t  of V  s  l  a  g  on t h e p r e d i c t e d  temperature  profile  Figure  7.15  The  effect  of F  on  the  predicted  Zn  profile  oxy  Ul  174 results An  i n an i n c r e a s e  increase  the  in F  predicted  predicted  o  x  also gives  y  ferrous  bath  i n t h e fuming r a t e rise  to a significant  iron concentration,  temperature,  o f Pb, s e e P i g .  see  decrease i n  and a n i n c r e a s e  Pigs.  7.16.  7.17  i n the  and  7.18,  respectively.  Model s e n s i t i v i t y is  illustrated  little  t o the s l a g a c t i v i t y c o e f f i c i e n t  i n F i g s . 7.19 a n d 7.20.  Figs.  and  temperature p r e d i c t i o n s t o  (not  7.19 a n d  7.20 r e s p e c t i v e l y . P e  2°3  P e  2°3  As c a n be s e e n , t h e r e i s  o r no o b v i o u s e f f e c t on t h e z i n c o r f e r r o u s  see  of  iron  profiles,  The s e n s i t i v i t y o f l e a d '  w  e  r  e  a  l  s  investigated  o  shown) a n d f o u n d t o be m i n i m a l .  Finally, magnitude  the  of  D „  sensitivity was  n  2 3 Figs.  of  the  model  investigated.  to  The  the r e l a t i v e results  are  r e  illustrated ferrous of  iron profiles  the  D„ Fe 0  zinc  7.21-7.24.  Both t h e p r e d i c t e d  show a m o d e r a t e  profiles,  results  n  2  in  sensitivity.  F i g . 7.21, a f a c t o r o f f o u r  i n a 1 wt% d e c r e a s e  i n predicted  bath  z i n c and  In the case increase i n concentra-  3  t i o n a t about time the  35 m i n u t e s e l a p s e d  variation is  iron, decreasing  D „ P e  decrease predicted  in  down t o rt  profile,  rt  0.5 wt%.  minutes  elapsed  In the case of f e r r o u s  by a f a c t o r o f f o u r  results in a  iron concentration, F i g . 7.22, c a n  i n s e n s i t i v e , and t h e temperature i n s e n s i t i v e t o D_ . 2°3 P e  A t 100  2 wt  2°3  the ferrous  lead  time.  be s e e n  profile,  s e e F i g 7.23.  The  t o be  relatively  F i g . 7.24,  completely  LEGEND 02 TO FE2O3=0.20(STD.) 0 = STD.«0.5 A = STD.»2.0  • = FRAC.  TIME(MINS)  Figure  7.16  The e f f e c t  of F  on t h e p r e d i c t e d Pb  profile  2 +  Figure  7.17  The  e f f e c t of F  oxy  on the p r e d i c t e d  Fe  profile  q d  o —i  q d  o  Q  o o <N  • = FRAC. 02 0 = STD.»0.5 A = STD.*2.0  q d o  LEGEND TO FE2O3=0.2(STD.)  o o o  0.0  10.0  ^  20.0  1  1  I  1  I  I  1  30.0  40.0  50.0  60.0  70.0  80.0  90.0  100.0  TIME(MINS)  Figure  7.18  The e f f e c t  of F  Q  x  y  on t h e p r e d i c t e d  temperature  profile  -4  to  -i  100 TIME(MINS)  F i g u r e 7.19  The  effect  of  X  Fe  Q  on  the  predicted  Zn  profile  IT) .  rO  rO . rO O ro  O or  S  cn  z> q  o  or  iri. CN  q  ro.  LEGEND • = ACT. COEFF. FE203=STD. 0 = STD.»0.5 A = STD.*2.0  q CN '  o  q q 0.0  10.0  20.0  30.0  40.0  50.0  60.0  70.0  80.0  90.0  100  TIME(MINS)  Figure  7.20  The  effect  of  ^  P  e  0  on  the  predicted  Fe  2 +  profil  F i g u r e 7.21  The  e f f e c t of D_  /D_,  n  on the p r e d i c t e d Zn  profile  CO  O  LEGEND • = DFEO/DFE2O3=10.0(STD.) 0 = DFEO/DFE2O3=5.0 A = DFEO/DFE2O3=20.0  -T«-  0.0  10.0  20.0  30.0  40.0  50.0  60.0  70.0  80.0  90.0  100.0  TIME(MINS)  figure 7 . 2 2  The e f f e c t  of D  Feo  /D  Fe 0 2  on the p r e d i c t e d Pb p r o f i l e 3  Figure  7.23  The  effect  of  D  p e Q  /D  pe  Q  on  the  predicted  Fe  2+  profil*  o  LEGEND • = DFEO/DFE2O3=10.0(STD.) 0 = DFEO/DFE2O3=5.0 A = DFEO/DFE2O3=20.0  0.0  10.0  20.0  30.0  40.0  50.0  60.0  70.0  80.0  90.0  100.0  temperature  profi  TIME(MINS)  Figure  7.24  The  effect  of  n p  e  Q  /D  p e  Q  on t h e p r e d i c t e d  184 Having presented is  worthwhile  reduction  the r e s u l t s of the s e n s i t i v i t y a n a l y s i s , i t  t o assess the i n f l u e n c e  has  had on  the p r e d i c t i o n  proceeding with a discussion  7.1.1.1  The  Influence  As d e s c r i b e d there are char  reaction the  model.  At  reactions  at a  sufficiently  potential, rate  of  rates  lead  the influence on  kinetics  lead:  the  prill-slag of lead i n of  the  two  of  Boudouard  f i x the  o f ZnO,  PbO  and  rates  and P e  0 2  or r e d u c t i o n  3  w  i  l  1  bubble  char-steam of  reaction  secondary bubble  of these species  of mass-transfer  Model  - secondary  I f t h e combined  as t o  p a r t i c u l a r oxides mobility  slag.  lead  the  char p a r t i c l e  maximum.  then reduction  rates  and  model,  established.  l i m i t e d by m a s s - t r a n s f e r  relative  which i n v o l v e  t o assess  the  high so  lead  before  furnace  o f t h e Char P a r t i c l e - S l a g  initialization  are  the o v e r a l l  model,  must be  with the s l a g ,  of process k i n e t i c s  k i n e t i c models  reaction  The K i n e t i c s  the  reaction  first  i n c l u s i o n of  Kinetics  within  Therefore,  models  7.1.1.1.1  the  on  o v e r a l l model, the e f f e c t of  reaction  are  o f Lead  two d i s t i n c t  the  of the r e s u l t s .  previously,  particle-slag  that  oxygen  proceed a t a  i n the s l a g .  will  and thermodynamic  The  be d e p e n d e n t stability  on  i n the  185 As  reaction  consumed, t h e begin  to  combined  slow.  reactions  can  reduction  is  reduction  no  This  to  this  of  time  source  of  Kinetic Fe^O^  on,  (slag residence possible. w i t h the of F e 0 2  slag of  in  char  until,  in  t o be  k i n e t i c s of  a  is  with  t i m e s ) the  which  rate  the  As  oxygen p o t e n t i a l in  the  the  the  the  oxygen  of  rate  of  potential  eventually  where  into  last  of  longer PbO  the Prom  z i n c and  lead,  reaction  z i n c and  the  residence  set  of  lead  i s no  and  the  with  predicted  time of  the  times longer  proceed  with  the  the  and  reduction  equilibrium that  the  slag.  b o t h PbO  reaction  I t i s worth n o t i n g  bubble  the  reaction  also  s t a g e s of  time p e r m i t s ,  achieved.  char  rates  combined  back  still  reduction  i f residence  from t h i s  at  v a p o u r e f f e c t i v e l y becomes  re-oxidized  of metal  amount o f  reactions  thermodynamically p o s s i b l e .  is  is  the  decrease  As  char  these  the  reacted  reduced.  for a given  In summary, the  in  coal  r e a c h e d where  i s s h i f t e d back t o s l a g d i f f u s i o n as  particle-secondary  slag  up"  the  char-steam  is  therefore,  point  and  s o l e l y d e p e n d e n t on the  point  metallic zinc  eventually  the  a  and  longer  back o x i d a t i o n  3  B o u d o u a r d and  "keep  From t h i s t i m e on,  therefore, are  a  reductant  continue  within  i n k i n e t i c c o n t r o l to  i s no  the  control  carbon  char-steam r e a c t i o n s .  rise, ZnO  of  results  a shift  B o u d o u a r d and  reduction  longer  occurring,  and  continues  rate  and  Eventually  begins to r i s e .  the  proceeds  extent  slag,  t o be  the  and  reduced  char p a r t i c l e  reaction kinetics.  d e s c r i p t i o n , the particle/sag  influence  model  are  of  PbO  clear.  on In  186 e s s e n c e , PbO in  so  competes  f o r reductant with both  d o i n g , e f f e c t i v e l y d e c r e a s e s the  a given  char-particle slag residence  7.1.1.1.12  In  The  K i n e t i c s of  comparison,  the  is  d e p e n d e n t on  FeO  (Fe 0 2  the  t o the  3  and  The  several  rate  will  be  lead of  of a  each reduced  prill  for  oxidation of  rates  of P e 0 ,  PbO  and  rates  2  of  3  FeO  lead  PbO  and  away  from  of  mass-transfer  are  relative mobility  p a r t i c u l a r oxide.  function  are  oxidation  i n c l u d i n g the the  and  back  i n t e r f a c e and  quantities  thermodynamic s t a b i l i t y  mass t r a n s f e r  of  rate  relative  Pe^O^  Oxidation  mass-transfer  prill-slag  interface).  d e p e n d e n t on  the  The  and  time.  kinetics  s t r a i g h t forward.  solely  amount o f  Lead P r i l l  relatively  ZnO  the  The  radius  of  overall the  lead  prill.  Having description model  7.2  reaction  a  sensitivity  kinetics, i t is  Sensitivity Analysis:  those  model  parameters  removal n  of  both  now  analysis  possible  to  and  a  discuss  sensitivity.  The  F_ _ PBL  completed  and  within D  PBO  approximations.  has  been  used the  Discussion  shown t o be  i n the  model.  i n the  model  relatively  formulation  Therefore, may  be  the  of  lead  i n s e n s i t i v e to reduction  v a l u e s used  assumed t o be  for  and Pb r p  reasonable  187  It the  is  i n t e r e s t i n g to  normal  Figs.  low-pressure run  6.4,  resemble  note t h a t  6.8, the  6.12,  profile  and  and  i n d u s t r i a l lead  three  6.16,  predicted  p r o f i l e s for  high-pressure  respectively,  w i t h the  runs,  see  more c l o s e l y  model u s i n g  the  larger  PR  lead  prill  seem  to  size  ( r "  indicated  limits  the the  rate  oxidation  80  that  rate  Within  =  of  model,  E - 04  there  lead  M),  See  Fig.  7.2.  This  would  i s some k i n e t i c phenomenon w h i c h  elimination  at  lower bath  lead  levels.  t h i s behaviour  i s a r e s u l t of d e c r e a s i n g  the  (increasing  the  Pb of  of  lead  prill  r  ) to  such  an  P extent  that  i t eventually  removal of  lead.  Virtually a l l  metallic  lead  within  oxidation  in  order  If  this  design  collection and  on  waste o f One  is  the  the to  the  b o t t o m , and  of  the  more  justification  modified  kinetics increase  of  remove avoid  hence,  and  points the the  lead  lead  the  in  await  from the  need  for  in liquid  recycling  the  i s reduced  must  removed  to  step  of  to re-  bath. proper  form,  liquid  eg. lead  reductant.  f r o m l m / s e c , assumed the  to  it  limiting  oxidic  and,  re-reduced  case,  in order  rate  the  furnace  be  i s i n f a c t the  reactor  becomes t h e  the  troublesome questions for  increasing  in Richards  model.  From  1 3  the  clear  -  it  is  i n Chapter  VI  slag circulation velocity original preceding  char p a r t i c l e r e a c t i o n  becomes  raised  model, t o  3m/sec i n  discussion  system, the  necessary to  reason  on  the  for  the  reduce the  char  188 particle zinc the  r e s i d e n c e time  from the secondary value  doing  of  3m/sec.  this.  a d o p t an  Starting sensitivity model F  T D  __  and  with  .  n  follows  that the  fit.  the  there  i s no  direct  alternative  On  balance,  previous  profile  it  is  justify  method  other  than  clear  work o f R i c h a r d s  i s only sensitive  this  least  be  basis, the values  f i t  close  t o two used  the  ferric  a F  e 2  ° 3  time  or  i s through slag  profiles  -  a  n  d  adjustment  for  this  argument comes f r o m t h e  fit  with  original  has  PbO,  of  temperature,  rate?  velocity  of to  1 3  from  the  that  the  parameters-  for  F_„„  and  been  Richards  1 3  exhibit  a  reasonable  i t simply  becomes a  coal  circulation  found.  This  The  and  particle  ferrous  to f i t a l l -  the  A d d i t i o n a l support  velocity also  for a  residence  iron  t h a t a l l of the  was  to  o n l y means o f  reiterate,  correct.  fact  the model,  data.  To  zinc  slag  model.  must a l s o be c o r r e c t  within  the  o f r e d u c t i o n must be  necessity, i t  reduction rate relative  velocity.  relative  a constant  0 2 3  zinc profile,  thermodynamic  circulation  By  profiles  correct zinc  g i v e n s e t o f k i n e t i c and this  iron  remaining  of o b t a i n i n g  doing  to correct.  r a t e o f r e d u c t i o n o f Fe  r e d u c t i o n r a t e s of  three  is little  heat  and  f e r r o u s and  To  question the  however, t o  OXjf  most a t  since  I t remains there  lead to d i s p l a c e  OXY  LPCC  P  bubble.  the  analysis  F  of  approach.  temperature  u E r ww  the a b i l i t y  Unfortunately,  Therefore,  indirect  to o f f s e t  runs  can  be  once t h e c o r r e c t  the  case  with  the  189  Finally, the apparent Based  to  incorrect  assume t h a t  thermodynamic  o f t h e model the  Pb and D„„_./D_._ , p ZNO PBO lP  observed  are reasonable approximations.  including general  high-pressure  validity.  model  A general  indicates  m o d e l s have been f i t t e d  x  c a n be  y  Fe 0 , 2  effect  3  i t  addressed. i s unjust-  i s associated  with  Summary  the modified  R i c h a r d s model.  to  Q  to  data.  Sensitivity Analysis:  original  i n C h a p t e r VI w i t h r e s p e c t  t e m p e r a t u r e dependence of F  To s u m m a r i z e ,  r  question raised  on t h e s e n s i t i v i t y  ifiable  7.3  the  to a coal  that The  i s at least  as v a l i d  as the  lack  of s e n s i t i v i t y t o F  the  values  fact  wide r a n g e injection  that  B L  /  u s e d i n t h e model the k i n e t i c s  of o p e r a t i n g builds  p  support  based  conditions for their  190  CHAPTER V I I I  SUMMARY AND  8.1  Summary  The  results  of  on  the  Cominco  demonstrated  that  injector  and  efficiency  This  is  in  equilibrium  The modified slag  direct  based  bath.  This  include  of  were a c h i e v e d high-pressure  2  a  single  zinc  achieved  with  contradiction  high-pressure  fuming  improvements  furnace  has  fuming  rate  i n both  high-pressure  to  model b y the  Richards  reduction  and  d i r e c t "lead  a s s u m i n g mass t r a n s f e r  that  incorporated  the  injection.  predictions  substantial  coal  was p r e d i c t e d  behaviour  f o r proper  reactor  et  a l  l  a  removal  prill"  -  control  of the  t o have lead  from t h e  s l a g r e a c t i o n has i n the s l a g  in  injection.  design.  h a s been  b  furnace  high-pressure  improvements  of m e t a l l i c  '  of lead  into the o v e r a l l  with high-pressure  The c y c l e  t h e need  No.  with  t h i s model t o t h e i n d u s t r i a l  confirmed  slag.  be  A model o f  model h a s been  Pitting  runs  models.  mathematical to  three  substantial  can  been d e v e l o p e d  has  CONCLUSIONS  coal  phase. model.  trial  data  entrainment  R o u g h l y 80% o f t h e  been e n t r a i n e d i n the bath  i n the  points to  191 8.2  Suggestions  for Further  Work  A t o t a l of three runs with a s i n g l e a p r e l i m i n a r y study better slag  probe  of high-pressure  the l i m i t s  fuming  process  injector represents  coal  injection.  of high-pressure  further  only  In order t o  i n j e c t i o n i n the z i n c  industrial  tests  are  needed,  including:  (a)  more  single  pressure  coal  injector rates  trials and  - v a r y i n g l o w and h i g h -  high-pressure  coal  to a i r  loading; (b)  a series  (c)  a  of m u l t i - i n j e c t o r  series  water/coal  of  trials  with  t r i a l s , and; high-pressure  and o i l / c o a l s l u r r i e s .  i n j e c t i o n of  192  REFERENCES 1 a) R i c h a r d s , " K i n e t i c s of the zinc T h e s i s , U.B.C., 1983.  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Height F r a c t i o n F i x e d iCarbon: 0 .500  Volatiles:  Height F r a c t i o n Carbon : 0.500  Volatilea:  Hydrogen:  0.250  0.200  Moisture:  Oxygen:  0.100  0.01 Nitrogen:  Primary Blast Time (min) 0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0 80.0 90.0 100.0 110.0 120.0 130.0 140.0  Temp CC)  Zn %  Pb %  Fe*» %  Fe * \  1250 1254 1260 1250 1246 1243 1240 1237 1228 1214 1201 1195 1191 1190  15.0 14.7 14.1 13.2 12.4 11.5 10.3 9.5 8.4 7.4 6.5 5.7 4.9 4.3  1.90 1.50 1.12 0.80 0.53 0.43 0.30 0.23 0.16 0.10 0.10  21.5 22.7 23.7 24.6 25.4 26.1 26.8 27.8 28.7 29.2 29.8 30.4 30.9 31.4 31.7  7.0 6.1 5.3 4.7 4.3 4.0 3.7 3.4 3.0 2.7 2.5 2.3 2.0 1.7 1.5  U?Q  3,7  a  CaO \ 11.7 11.3 11.6 11.9 12.0 12.1 12.5 12.4 12.5 12.6 12.6 12.7 12.9 13.1 13.2  SiOa % 23.2 22.9 23.0 23.1 23.4 23.7 24.3 24.9 25.2 25.5 25.5 25.4 25.9 26.4 26.7  A1,0, \ 4.0  3  \  0.1  0.0  Secondary Blast  Coal rate  H.P - C o a l rate  tmi  mi  min  min  lbs min  lbs min  40  330  104  0  140  *E  »E  T I M A T E  T I M A T E  3  3  -  154  ^1  Bath C o m p o s i t i o n :  50909 k g .  Coal Composition:  Weight F r a c t i o n Fixed Carbon: 0.500  Coal V o l a t i l e s :  Time (min) 0.0 5.0 10.0 15.0 17.0 20.0 25.0 30.0 35.0 40.0 45.0 50.0 55.0 60.0 65.0  Weight F r a c t i o n Carbon: 0.500  Temp (-C)  Zn  1330 1325 1320 1305  8.7 8.3 -7.6-7.9 7.2  1300 1300 1280 1260 1255 1250 1240 1230 1225  6.8 "6.3-6.5 6.1 5.3 -4.8-4.9 4.4 3.9 "3.5-3.5 3.1 3.Q  1225  Pb %  Fe * a  Volatiles: Hydrogen:  Fe"*  0.250  0.200  CaO  SiO  %  %  Moisture:  Oxygen:  a  %  %  0.21 0.12 0.12 0.09  28.7 28.0 29.0 28.6  3.1 3.6 3.0 3.4  12.8 13.0 13.0 12.0  25.0 26.0 26.0 26.2  0.08 0.07 0.05 0.04 0.03 0.02 0.02 0.02 0.02 0.07  27.7 28.4 28.2 29.5 29 .6 29.6 30.6 31.6 30.7 30.1  4.3 3.6 4.0 3.0 2.7 2.9 2.4 1.0 2.0  13.0 13.1 13.2 13.3 13.5 13.6 13.4 13.6 13.7  2.7  13.7  26.6 27.0 27.2 27 .6 28.4 28.6 27.8 29.1 29.5 29.5  0.100  A1 0* 2  S  %  %  4.0  *note: the two numbers r e p r e s e n t s a m p l i n g procedure (procedure  -E  S T I M A T E 1  0.1  0.01 Nitrogen:  0.0  Primary Blast  Secondary Blast  Coal rate  mi  HM min  ibjL min  min  330  150  0  min 40.0 40.0  -E S T I M A T E  1  the r e s u l t s of the d o u b l e is explained in text)  J  120 120 135 120  H.P.-Coal rate  l b B  16 16 20 26  .  Run 2 Bath Weight:  52727 k g .  Coal Composition:  Weight F r a c t i o n F i x e d C a r b o n : 0.500  Coal V o l a t i l e s :  Weight F r a c t i o n Carbon: 0.500  Volatiles: Hydrogen:  0.250  0.200  Moisture:  Oxygen:  0.01  0.100  Nitrogen:  Primary Blast Time (min) 0.0 -iufl  10.0  20.0 25.0 30,0 35.0 1Q.Q 15_J2 5JL-Q 51x3 60.0 iS^O IIU 75.Q 80.0 85.0  Temp (*C) 1275 1310 UL2J 1325 1310 1215 1285 1285 1215 1215 1255 1265 127J} 1215 1212 1255 1240  Zn % 16.0 15.7 15.2 14.8 11x2 13.6 13.0 12.4 11.7 11.0 10.5 9_J 9.3 8.6 7.6 6.9  Pb % JL.9J JL-9JI !L_8_5  fUM  0x15 fLM 0.50 0.40 0.35 0.30 0.21 0.25 0-15 0.13 0.10 0.12 0.03  Fe % a  2Li 1^2 2U. 2.LS 22x4 22J 25.4 25.2 25.7 26.2 26.2 26.6 27.1 28.0 28.2 28.4 29.4  Fe % a  6 J J  fL& LJ, L J L J 5_J 4.0 4.3 L i 4.8 4.0 3.9 3-J) 3J3 3.1 3.4 2.2  CaO % L U LLJ LUfi 11*5 m 12J 12.5 12.4 12x5 12.6 12.6 12.6 12J 12.7 12.9 13.1 13.2  SiO* % 22^2 2JLJ 2 U 2AJ. 22J 22x2 U J 21x2 25x2 2^_5 25.5 25.4 2iJ 26.4 26.7 27.0 27.2  AlaO, \  S %  "ro* min  UJ  JLJ  15  0.0  Secondary Blast  Coal rate  Nm min  lbs. min  3  liLQ  J£ i J. J M A. T  Q  115 ;  "_£ 3 I I t) & J g  IhS. min  Lft5  112  :  H . P . - Coal rate  UL5  ip__  UQ  2fi_  U5  <L_  m  g  :  10 10  Run 3 B a t h Weight:  58182 k g .  Coal Composition:  Weight P r a c t i o n F i x e d Carbon: 0.500  Coal  Volatiles:  Weight ; F r a c t i o n Carbon >: 0.500  Volatiles: Hydrogen:  0.250  0.200  Moisture:  0.01  0.100  Oxygen:  Nitrogen:  Primary Blast Time (min) 0.0 5.0 10.0 15.0 20.0 25.0 30.0 35.0 38.0 40.0 45.0 50.0 55.0 60.0 65.0 70.0 72.0 75.0 76.0 60.0 81.0 85.0  Fe»«-  Secondary Blast  Coal rate  %  CaO %  SiO  %  3.30 3,10 2.90 2.70 2.70 2.50 2,10 1.70  21.9 21.1 21.2 21.6 20.3 22.1 24.2 24.9  6.8 7.8 7.8 7.8 8.8 7.6 5.9 5.4  10.6 10.6 10.7 10.7 10.8 10.8 10.8 11, i  23.1 23.2 23.3 23.3 23.3 23.2 23.6 24.0  11.0 10.5 10.0 9.3 8.4 7.9 7.1  1.20 1.00 0.85 0.62 0.40 0.33 0.25  26.5 26.1 26.7 28.1 28.0 28.5 28.4  4.3 4.9 4,6 3.6 3.8 3.5 3.7  11.3 11.5 11.6 11.8 11.9 12.0 12.1  24.4 25.0 25.5 26.0 26.4 26.9 27.4  1255  6.8  0.21  28.5  3.9  12.15  27.6  1260  6.3  0.15  29.6  3.0  12.2  27.7  12P 120 135  126p  5.7  P-12  29-8  3.2  12.2  27.8  135  CO  Zn %  Pb %  J.265 1270 J.272 1275 1280 1290 1300 1290  13.5 13.4 13.2 13.0 12.9 12.5 12.4 11.8  1275 1265 1255 1252 1250 1255 1255  Temp  a  A l o3  0.0  a  4.0  "E S T  I M A T E  S %  .01  H.P.-Coal rate  Nm» min  min  ML  lbs min  min  40 40  330 330  105 105  0 0  120 120 105  35  Iks.  "P  s  T J  M A T  e  0  O  o  

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