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The alkaline sulphide leaching of tetrahedrite concentrate Raudsepp, Rein 1981

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THE  ALKALINE  OF  SULPHIDE  TETRAHEDRITE  LEACHING  CONCENTRATE  by  REIN  B . S c ,  (Engineering  University,  A THESIS THE  RAUDSEPP  Kingston,  IN  Queen's  Ontario,  PARTIAL FULFILMENT  REQUIREMENTS MASTER  Chemistry),  FOR THE DEGREE  OF A P P L I E D  1975  OF OF  SCIENCE  in  THE  FACULTY  Department  of  OF GRADUATE  Metallurgical  STUDIES Engineering  We a c c e p t t h i s t h e s i s a s conforming to the required standard  THE  U N I V E R S I T Y OF B R I T I S H March  (c)  Rein  COLUMBIA  1981  Raudsepp,  1981  In p r e s e n t i n g t h i s t h e s i s i n p a r t i a l f u l f i l m e n t of the requirements f o r an a d v a n c e d d e g r e e at the U n i v e r s i t y of British C o l u m b i a , I a g r e e t h a t t h e L i b r a r y s h a l l make i t freely a v a i l a b l e for reference and study. I further agree that p e r m i s s i o n f o r e x t e n s i v e c o p y i n g of t h i s t h e s i s f o r scholarly p u r p o s e s m a y b e g r a n t e d b y t h e H e a d o f my d e p a r t m e n t or by his or her r e p r e s e n t a t i v e s . It is understood that copying or publication of t h i s t h e s i s for f i n a n c i a l gain s h a l l not be a l l o w e d w i t h o u t my w r i t t e n permission.  Rein  Department of M e t a l l u r g i c a l Engineering The U n i v e r s i t y of B r i t i s h Columbia 2075 Westbrook Mall Vancouver, B.C. Canada V 6 T 1W5 Date  Raudsepp  ii  Abstract  An  inv e s t i g a t i o n was made into the leaching of tetrahedrite concentrate  by strong sodium sulphide/sodium hydroxide solutions.  .  The experiments were  designed to avoid oxidation of the elements present and s o , s o l u b i l i z e antimony as antimony (III) - sulphide complexes.  A n a l y t i c a l techniques were developed 2 2 2 for the analysis of caustic and sulphur species (S , S , SO and S0„ ) £. J  X""" -L  J  i n antimony-containing solutions. The quantity of antimony extracted from the tetrahedrite was  found to be a  function of both the sulphide and hydroxide concentrations.  Sodium t h i o f e r r a t e ,  a reaction product of p y r i t e and sodium sulphide, was agent.  The s o l i d concentrate decomposition product was  colloidal. i t was  indicated as a leaching x-ray amorphous and  Though a p o s i t i v e i d e n t i f i c a t i o n of this material was  not possible  found that one iron and one sulphur were added to the product for each  antimony extracted from the tetrahedrite. An analysis of l i t e r a t u r e s t i b n i t e s o l u b i l i t y data was log [Sb\ (M) = -0.7  .  ^2^4  i s probably  done and showed that below  the predominant antimony (III) -  sulphide complex i n saturated soltuion at 25°C. 2Sb^S^ i s the most l i k e l y predominant complex.  Above log [sb]  (M) = -0.7  ,  The r e s u l t s of the leaching study are not d i r e c t l y applicable to commercial 1 tetrahedrite leach processes where the solutions contain oxidized sulphur i n p a r t i c u l a r polysulphide. (V) - sulphide complexes.  Antimony leached i n these processes  species,  exists as antimony  Table  of  Contents  Abstract. Table  of  ,  i i  Contents  List  of  Tables  List  of  Figures  i i i . . .  v i i ix  Acknowledgements  Chapter  1.  xi  Introduction  1  1.1  General  1  1.2  Tetrahedrite  3  1.3  Chemistry  5  1.3.1  Alkaline  Sulphur  1.3.2  Alkaline  Antimony-Sulphur  1.3.3  Miscellaneous  1.4  The  Chapter 2.1  Sunshine  2.  Leach  Chemistry  Alkaline  5 Chemistry  Sulphide  Process  Experimental  Chemistry  9 ..  13 18 22  Materials  22  2.1.1  Tetrahedrite  2.1.2  Reagents  2.2  Leaching  Apparatus  2.3  Leach  2.4  Sulphide  2.5  Evaporation  Procedure Oxidation  Concentrate  22 26 26 27 30 30  Chapter  3.  3.1  Analytical  Automatic  3.2. S o l u b l e 3.2.1  Chemistry  31  T i t r a t i o n  Sulphur  31  Species  Analysis  Sulphide,  Polysulphide  Sulphite  Determination  And 3.2.2  The  Effect  Of  33  Sulphur,  Thiosulphate 33  Antimony(111)  On  The  Sulphide  Determination 3.2.3  The  Effect  Polysulphide 3.3  The  3.4  Caustic  37 Of  The  Sulphide  And  Of  39  Sulphur  l a  Solids  41  Determination  Caustic  3.4.2  On  Determinations  Determination  3.4.1  Antimony(V)  The  41  Determination  Effect  Of  In  Sulphide  Solution  Antimony(111 )  On  The  .  41  Caustic  Determination 3.4.3  The  42  Effect  Of  Antimony(V)  On  The  Caustic  Determination 3.5  Atomic  Chapter  4.  .44  Absorption  Results  And  And  Leaching  Experiments  4.2  Antimony  Leaching  Antimony  Emmission  Analysis  ..  44  Observations  4.1  4.2.1  Flame  -  46  Considered Equilibrium  Leached  In  46 Results  Alkaline  Sulphide  46 Solutions 46  4.2.2 4.3  Antimony  Leaching Added  In  Leached Weak  In  Sodium  Caustic-Only Sulphide  Solutions  Solutions  Caustic  4.4  The  Excess  Of  4.5  F i l t e r a b i 1 i t y  .  50  Without 51  Concentrate Of  The  Used  Leached  Product  52 Slurry  '52  4.6  The  Change  In  Sulphide  4.7  The  Change  In  Caustic  4.8  Arsenic  4.9  The  Concentration  53  Concentration  55  Dissolution  Presence  58  Of  Oxidized  Sulphur  Species  And  Antimony(V)  60  4.10  Antimony  4.11  Appearance  4.12  X-ray  4.13  4.15  Of  Comparison By  Leaches  At  Low  The  Sodium  4.18  Silica-Iron  Tetrahedrite  And  5.1  Stibnite  5.2  Tetrahedrite  Of  Solids  63  Solids  The  63  Decomposition  Microanalysis  Pulp  Density  Of  Sodium  63 69  In  The  Concentrate  To  71  Antimony  Ratio  Of  The  Leached  Solids  74  Oxide Of  Particles Antimony  Solubility  The  74 Solubility  On  Sulphide 77  Plots  Solubility  Discussion  Review  60  Product  Dependency  Concentration  6.1  Product  Leaching  Ion  6.  The  Product  Time  72  Pyrite  Chapter  Of  And  Versus  Water  4.17  5.  Concentrations  Concentrate  Electron  Inconsistency  Wash  Chapter  The  Of  Decomposition 4.16  Sulphide  Diffractometry  Product 4.14  And  Results  Plots  .  77 83 91 91  6.2  Caustic  6.3  Sodium  6.4  Disintegration  6.5  The  6.6  Sulphide  6.7  Thioferrate  6.8  Sodium  6.9  The  6.10  Formation  And  Sulphide  Depletion  Thioferrate Of  94 The  Characteristics As  As  The As  The  Leach  Solids  Of  The  Leaching  Leach  98  Agent  101  Equilibrium Of  The  101  Chapter  7.  Conclusions  Chapter  8.  Recommendations  For  The  Equilibrium  at  99  Agent  Progress  A  96  Agent  The, L e a c h i n g Leaching  95  The  Appendix  93  Leach  ..104 105  HS~-S "-OH 2  Future  1 0 0 °C  Study  108  Calculation '  Appendix  B  X-Ray  Appendix  C  Concentrate  Appendix  D  Experimental  Results  Appendix  E  Antimony  Sulphide  109  Diffractometry  and  110  Stoichiometry.Calculations  112 114  Concentrations  versus  Time  117  Appendix  F  Analysis  Appendix  G  Calculation Data  References  from  of  the of  Stibnite Log  Dissolution  Antimony  Experimental  and  Results  Log  Data  ..118  Sulphide 122  128  List  Table  Table  Table  Table  1-1:  1-2:  1-3:  1-4:  of  Proposed Stibnite Reactions  Tables  and  Antimony(111) 11  Antimony-Sulphide Complex Reduction Potentials  14  Reactions Forming Soluble Sulphide Complexes  15  Solubility and Oxides Solution  16  of in  Metal Sulphides Sodium Sulphide  Table  1-5:  Sunshine  Leach  Table  2-1:  Chemical  Analysis  Concentrate  Plant  Balance  of  Sunshine  (Dry)  2-2:  Wet  Table  3-1:  Sulphide Determination in Antimony (III) Solution S u l p h i d e and Polysulphide Sulphur Determinations in Antimony (III) Solution  Table  3-2:  3-3:  Screening  23  Table  Table  Caustic  21  Results.  Analysis  in  ..  Antimony  38  . . . .  43  Table  4-1:  Microprobe  Table  4-2:  Data Pulp  Table  4-3:  5-1:  Analysis  Results  and R e s u l t s from Density Leaching  Results Washing  from  F i l t e r  Low Experiments....  Mean Antimony to Sulphide R a t i o s and S l o p e s taken from F i g u r e s 5-2 and 5-4  88 Ill  X-Ray  Table  D-l:  Data for Leaching C o n s i d e r e d in the  Experiments Study  Data for Leaching Not C o n s i d e r e d  Experiments  Table  E - l :  70 73  B - l :  D-2:  68  Cake  Table  Table  40  (V)  Solution  Table  24  Sb  and  Diffractometry  Na  S versus  Results  114  116 Time  Results  117  yiii Table  Table  F - l :  F-2:  R e s u l t s of L o g { S b } - L o g { F r e e Calculations Results  of  Equilibrium  S^"} 119  Constant  Calculations Table  F-3:  Results and  Table  Table  G - l :  G-2:  from  Ghosh  120 Calculations  (1962)  to  Sulphide  Data  :  from  Dubey  121  R e s u l t s of C a l c u l a t i o n s Log Antimony versus Log Plots Antimony  on  for Sulphide  Ratios  123 124  ix  List  1-1  Sulphur  Fiaure  1-2  Sulphur Oxidation 1 0 0 ° C , p H = 1 2 . . .'  State  F r a c t i o n of Added as the S " Ion at  Sodium 100°C  1-3  Diagram  Figures  Figure  Figure  E-pH  of  E  Figure  1-4  Structures for (111)-Sulphide  100°CDiagram  6 at 7  Sulphide 8  the Proposed Antimony Complexes (Plan Views)  12  Figure  2-1  The  Apparatus  28  Figure  3-1  The P o t e n t i a l and F i r s t Derivative Curves for the T i t r a t i o n of Sodium Sulphide with Hydrochloric Acid  34  The F i n a l A n t i m o n y Concentrations versus the F i n a l T o t a l Sodium Sulphide Concentrations - 0.5 and 2 M I n i t i a l Caustic  47  The F i n a l Antimony Concentrations versus the F i n a l T o t a l Sodium S u l p h i d e C o n c e n t r a t i o n s - 0 and 1 M I n i t i a l Caustic  48  The F i n a l A n t i m o n y Concentrations versus the F i n a l T o t a l Sodium Sulphide Concentrations - 1 M I n i t i a l C a u s t i c a n d Low S u l p h i d e  49  The D i f f e r e n c e s Between the I n i t i a l and F i n a l Sodium S u l p h i d e ConcentrationsAbsolute (Top) and R e l a t i v e (Bottom), versus the F i n a l Antimony C o n c e n t r a t i o n s . . . .  54  The D i f f e r e n c e s Between the I n i t i a l and F i n a l Sodium Hydroxide Concentrations versus the F i n a l Sodium Sulphide Concentrations.  56  The F i n a l A n t i m o n y Concentrations v e r s u s the P r o d u c t of the Final Sodium S u l p h i d e and Sodium Hydroxide Concentrations (1 M I n i t i a l C a u s t i c )  57  The A r s e n i c V e r s u s Concentrations  59  Figure  Figure  Figure  Figure  Figure  Figure  Figure  Figure  4-1  4-2  4-3  4-4  4-5  4-6'  4-7  4-8  Leaching  at  the  The S o l u t i o n Antimony as a F u n c t i o n of Time  Antimony  Concentrations 61  Figure  Figure  Figure  Figure  Figure  4-9  4-10  4-11  4-12  4-13  Figure'5-1  Figure  Figure  5-2  5-3  The Sodium S u l p h i d e Concentrations as a F u n c t i o n of Time  62  The T e t r a h e d r i t e Concentrate and the Leach Product S o l i d s at 2,100 x  (a) (b) 64  The T e t r a h e d r i t e Concentrate and the Leach Product S o l i d s at 21,000 x ..."  (a) (b)  SEM X - r a y A n a l y s e r S p e c t r a for the T e t r a h e d r i t e and the Decomposition Product Phases  66  SEM M i c r o g r a p h of a Silica-Iron Oxide P a r t i c l e (a) and the Corresponding Silicon (b) and I r o n .(c) X - r a y E n e r g y Maps  75  The L i t e r a t u r e Stibnite Leaching Data P l o t t e d Consider ingSb^S^." a t Low S u l p h i d e a n d S b i S ^ at High Sulphide (SbS£" Stablilty A r e a Shown )  79  Solubility Plot for Experimental Results  Tetrahedrite 84  Experimental Results t h e Sb S^.' I o n a t Low Ion at High S u l p h i d e  Plotted for ^ Sulphide; Sb4S^  Solubility Plot for Experimental Results  Tetrahedrite (High Sulphide)  e  Figure  Figure  Figure  5-4  5-5  G-l  65  86  The Antimony to Sulphide Corrected) Values versus Antimony  87  (Arsenic Log  The S t i b n i t e Solubility Data of Arntson et a l . ,(1966) Plotted C o n s i d e r i n g SbpS^" and Sb^Sa  89  127  ACKNOWLEDGEMENTS I w o u l d l i k e t o s i n c e r e l y t h a n k my s u p e r v i s o r , D r . E. P e t e r s , f o r t h e many, many h o u r s he s p e n t w i t h me i n c o n s u l t a t i o n on t h i s p r o j e c t . I w o u l d a l s o l i k e t o t h a n k a l l t h e members of t h e M e t a l l u r g y D e p a r t m e n t f o r t h e i r u n e n d i n g a s s i s t a n c e a n d support. I am g r a t e f u l t o t h e S u n s h i n e M i n i n g Co. f o r s u p p l y i n g t h e t e t r a h e d r i t e c o n c e n t r a t e u s e d i s t h i s s t u d y . The f i n a n c i a l support of t h e N a t i o n a l S c i e n c e and E n g i n e e r i n g C o u n c i l i s greatly appreciated.  1 Chapter  1.  Introduct  1.1  General  Tetrahedrite occurrence metallic  and  antimony  of  in  are  often  (along  with  That  during  dioxide-laden and  small  blister  tankhouse  against by  Antimony leaching  is  substituent  separate  from  is  which and  to  reasons the  processes  removed  two  by  elements  matte  which and  from  must  they  economic  and  copper largely a  sulphur  contamination.  electrorefining which  for  copper  is  from  environmental  v o l a t i l i z e d  antimony  in  separated  be  significant  copper  soluble  must  avoid  solution  custom  mineral.  portion  during  these  this  major  primary  significant  furnace-converter  dissolve  assessed  concentrates  to  these  For  with  d i f f i c u l t  of  stripped.  Its  economically  the  also  electrolyte  but  arsenic,  are  amounts  widespread  reverberatory  stream  arsenic  copper  is  of  substitution.  associated  converting  gas  sulphosalt  elemental  copper,  tetrahedrite)  v o l a t i l i z e d  antimony  is  conventional  Antimony  copper  varied  silver  pyrometallurgy.  and  a  of  Antimony  The  is  constituent  quantities  by  ion  smelting.  report  to  the  remain  in  the  be  purged  penalties  arsenic  content  or are of  smelters.  sulphide for  solution  • stibnite,  (as Sb S , 2  3  is  arsenic)  apply  this  2 chemistry.  Similar  tetrahedrite plant  based  1942.  leaving on  this  Another  Columbia  is  The  leach  of  and  this  so  strong  work  solutions.  leach  with  industrial  (which  contains  minerals  results  and  obtained  are  on  other  Sunshine  sulphur  species  not  considered  oxidants  in  the  thiosulphate  leaching  in in  chemistry.  nature are  100°C  in  done  chosen  Sunshine  solution  the  the to  solution,  was  in to  concentrate was  leached.  the  Sunshine  contains  oxidized  work.  particular,  to  of  operated  experiments  applicable  this  B r i t i s h  sulphide/sodium  tetrahedrite)  leach  since  investigate  the  equilibrium  than  A  1981.  processes  and  Idaho  Houston,  sodium  of  from  smelting.  concentration  directly  the  in  determine  practice,  since  and  to  temperature  not  copper  to  and  metal  process  polysulphide  was  antimony  Sunshine,  in  leaching  focused  conform  The  study  practical  A  in  operation  tetrahedrite  was  for  construction  Industrial  highest  extract  operated  begin  solutions,  products. the  has  this  can suitable  under  to  between  leach  produce  leach  expected  equilibrium  solids  plant  purpose  hydroxide  l i x i v i a n t s  These  species,  are  potential  3 1.2  Tetrahedrite  Sulphosalts formula  A T X  m Ag;  as  T:  their  bonded  to  vertex.  Sb,  Bi  minerals  elements  as  X:  there'  sulphurs  presence  singly  which  have  designated  as  the  general  A are:  Cu,  Pb,  or  of  in  S'(Takeuchi  is  a  to  form  and  trivalent a  these  anionic  complex  groups,  T  low TS  Sadanaga, species  pyramid  1962).  covalently  with  T  pyramids,  3  distinguishes  at  the  arranged sulphosalts  sulphides.  Cu  believed  to  ZnS,  1  Sb4S  2  be  which  However,  Above  and  4+v  dissociates  2  the  Sb S 4  The  by  95°C  1  3  w  into other  copper  structure  orderly zinc  of  In  h  e  r  to  two  to  sulphurs,  three  °-  i  :  Below  L  shows <  x  95°C  immisible  C u ^ S b ^ S ^  of  K  a i -  wide 7  7  /  the  ° -  each  a  fourth  relative  the  other. bond to  atoms  other  the are  half  are  1964).  solid 0  3  solid  tetrahedrite with  sphalerite,  copper  while  (Wuensch,  originally  of  form  the  nominal  about  vacancies half  the  was  sulphur to  sulphur  copper-rich,  atoms  and  antimony  four  has  substitution  tetrahedrite  e  1973).  and  crystal  tetrahedrite  13'  S  sulphosalt,  of  and  coordinated  antimony  an  tetrahedra  bonded  Morimoto,  poor,  Its  lattice.  trigonally-  b  .  3  inability  tetrahedrally  S  1  copper  distortions  sphalerite  12+x  a  derived  has  the  produces  1  and  structure three  formula  Cu  the  of  =  Tetrahedrite,  C u  class  n p  The  either  a  where  As,  Within  from  are  <  solution Y <  .30  range: (Tatsuka  solution phases:  compositions  one  readily copper-  approaching  ..  tetrahedrite  can  diffuse  rapidly  and  it  4 is  possible  cold  to  convert  pressing  with  1973).  immersing  the  containing  5% s u l p h u r  other  with  Morimoto,  more  Iron  one  usually for  and  is  the  18%  s i l v e r ,  chalcopyrite, s i l v e r ,  lead  Cu*  has The  the.other  be  upper  film.  and  antimony  stoichiometry observed  given  in  is  lead  copper  and  holds  tetrahedrite s i l v e r , l e a d  and  found zinc.  in  of for  is  natural  atom  when  and  in  most  there  is  tetrahedrite  is  both.  (1-13%)  and  mercury  substitute  as  zinc  freibergite,  1977).  often  and  by  found  (Tatsuka  hydrothermal  galena  (Hurlbut  0.8  is in  0.2  known  Klein,  It  sphalerite, minerals  and  variety,  (Hurlbut  usually  of  analogue  above  argentiferous silver  limit  by  disulphide  (CuS)  copper  than  and  obtained  carbon  less  by  (Tatsuka  can  sulphide  of  to  arsenic  commonly  pyrite, and  an  found  The to  limited  formula  less  Tetrahedrite copper,  copper  compositions  is  Fe.  (0-8%);  up  into  copper-poor  Cu*  always  copper.  contains  the  sulphur  tetrahedrite  a  to  (Cu,Ag)IQ ( F e , Z n , H g , C u * ) 2 ( S b , A s ) 4 S 1 3  specimens.  tennantite  or  substitution  the  1973).  than  tetrahedrite  phase  forming  only  tetrahedrites:  natural  Copper-poor  partial  elements  of  powder  copper-rich  the  consistent  form  copper  Morimoto,  With  one  and  veins  associated various  Klein,  1977).  of with other  5  1.3 C h e m i s t r y  1.3.1  A l k a l i n e Sulphur  Sulphate 100°C  in  1.  should  be  alkaline  reasoning.  Chemistry  the  solution  on  The 100°C s u l p h u r  However,  product of s u l p h i d e the  b a s i s , of  E-pH d i a g r a m  for kinetic  reasons  oxidation at thermodynamic  i s shown i n F i g u r e  SO '  may  2  form  only  1at  4  potentials  up t o 0.5 v o l t  required. 1-2) be  The s u l p h u r  indicates that raised,  SO "  more  higher  thermodynamically (Figure  i f t h e p o t e n t i a l f o r SO^ " f o r m a t i o n  were t o  2  significant  concentrations  of  polysulphide,  insolution.  2  2 3  those  o x i d a t i o n s t a t e d i a g r a m a t pH 12  a n d SO " w o u l d e x i s t  2  than  3  Sulphide'oxidation observed with oxidants  t o sulphate  iodine, iodate, hypochlorite  (Blasius et a l .  oxidized  solution  (which  is  , 1968).  i s not  quite  equilibrium concentration a  very  determined  couple  and hydrogen  by t h e S " / S 0 ^ " 2  but  (Ferreira,  of p o l y s u l p h i d e  2  rather 1975).  i s small  r e v e r s i b l e e q u l i b r a t i o n with  When s o d i u m s u l p h i d e ,  peroxide  The p o t e n t i a l o f a p a r t i a l l y  irreversible),  sulphide/polysulphide  solution,  under a l k a l i n e c o n d i t i o n s i s  couple  by  the  Though  the  in alkaline  sulphide  occurs.  Na S-9H 0, i s d i s s o l v e d i n w a t e r , HS" 2  and  2  OH" a r e f o r m e d by h y d r o l y s i s ( E q u a t i o n 1 - 1 ) . nNa S + mNaOH + n ( F - l ) H 0. = nF Na S + n ( F - l ) N a H S + 2  2  2  {m + n ( F - l ) N a O H ) Figure at  1-3 shows t h e . f r a c t i o n  100°C  as  a  function  of  ...  (1-1)  of added Na S w h i c h e x i s t s as S " 2  2  the  initial  Na S  and  NaOH  6  1.6 1.2 Sulphur  0.8  Concentration  Decode = 0.073 V-Equiv  0.4 0  -0.4  -0.8 (VI  -1.2  -2  Figure  to  o E CO _J_  CVJ  CO  » CO  ™ to CO CO  to  to  I  1 _ L  0 1 2 . Sulphur Oxidation State 1-2: Sulphur O x i d a t i o n  to  ( Equiv )  S t a t e Diagram a t 100°C  , pH=12  8  Figure  1-3  F r a c t i o n of Added as the S2- ion at  Sodium 100*C.  Sulphide  9  concentrations. activity  coefficients  activity  1.3.2  Appendix  data  was  Alkaline  Sb  sulphide  the  Both  form  used.  Unit  species  as  no  ~ .  Chemistry  major  oxidized  binary  sulphur  valence  states,  compounds  1960)  sulphurs  in  a  is  bonded  square  argument  bonded  S^  to  three The  (Scavnicar,  to  an  octet  four  three  half  By  1960)  of  a  If  the  hybridization,  the  arranged  compound  Sb(III)  Sb  and  (III)  soluble  d  most electron  to  SbS  its  antimony as  sulphurs  in  hybridization  5  s p 2  valency  3  electron  trigonal  are  considered  5-coordinate  pairs pyramid  in  configuration a  S b ^ S ^  pyramid  3  five  electron  in  electrons  pairs:  the  arranged  bonds  probable  stibnite,  half  completes  tetrahedrally  two  is  trigonal  valence  covalent  configuration.  octagonally  other  pyramid.  forming  sp d 3  is  pyramid  2  six plus  pair.  Complex  L i ,  2  (Scavnicar,  a  These  S  structure  sulphosalts.  high  and  stibnite  Sb  lone  HS"  a l l  binary  in  a  for  for  (111)-sulphur  are  by  assumed  calculations  Sb  atoms  shell  two  the  complexes.  The In  were  available  has  (V).  shows  Antimony-Sulphur  Antimony and  A  sulphides  temperature salts K,  aqueous  Rb  are  salt  fusion  Na SbS ,  and  solution.  with  3  3  Cs  Na  a l k a l i  techniques 6  S b ^ S ^ and  analogues. A  metals  comparison  They of  have  (Moss NaSbS do the  2  been  and plus  not  prepared  Smith, some  1975). of  c r y s t a l l i z e  nuclear  by  their from  quadrapole  10  resonance  spectra  sulphosalt, were The  on  SbS  0  " ,  data  and  certain equilibria  been  Barner not  basis  data  are  are  large  sulphide single  the  available  sulphides  the  change  for  Figure  and  1-4  for  SbS  number is  and  structure (Scavnicar,  of  one  double  of  Sb^S^ " 2  1960).  of  4 5  bond shown  2  out  their  and  it  is  thermodynamic studies  Martell,  face  for  SbS  must  1964;  1952),  but  value.  For  3 3  "  remains  compiliation  of  have  activity  for  seems  seems  data formed  coefficient  or  (Vaughan based  six and on  the  Sb(IIl)-  unlikely  unlikely  sulphurs.  four  is  No  SbS " also  bonded two,  at  structures  "  Sb-  complexes.  above. 2  singly  capable  estimate.  S b S  and  AG°  which  listed  and  However,  Some  taken  the  AG°  the  1971).  proposed:  Latimer,  S b S ' s  possible  units.  3  1964;  1978  of  ,  solubility  Scheuerman's  any  shows  exist.  be  of  3  a l .  been  mapped  (Sillen  should  2  salts  SbS  have  stibnite  Butler,  original  complexes no  to  showed  been  them  estimate  sodium et  2  1-1)  1978;  1952  Barner  major  the  (Table  the  S b , S^ ' .  not  from  information  in  a  of  a l l  constants  Latimer's  unchanged despite  that  Scheuerman, this  example,  have  silver  1975).  and  stability  published  and  a l l  there  of  '  a  3  (Buslaev  complexes 4  r  Ag^SbS ,  of  K^S^S,,  Smith,  S b ^ S  2  domains  even  have  Sb„S„ -,  3  not  pyramids of  and  and  2  structures  trigonal  (Moss  NaSbS  Sb(111)-sulphide  S b S , " ,  relative  the  structure  S g r o u p s  Various  that  SbS  crystal  centered  Na^SbS^,  indicated  based x-ray  of  because  because  Covalently single Craig,  the  bonds  bonded or  1978).  stibnite  of  unit  four The c e l l  Table  1-1  1/2  :  Sb S 2  l/2Sb Sj 2  Sb  S (s) 2 3  Sb  S 2 3  SbS " 2  3  Proposed  (s)  (s)  +  +  +  S "  Stibnite  3/2S"  1/2S '  =  =  HSb  +  =  SbS "  • References:  2  S i l l e n  \  =  S 2 4  SbS  SbS " 2  Sb S " 2 4  + HS"  S "  2  2  2  =  2  and  2  (?)  3  3  and  Martell  \  2  J  Antimony(111)  Reactions*  K(298)  =  0.89  K(298)  =  0.45  K(303)  =  2.08  K(298)  =  "2.33  K(298)  =  0.44  (1964);  Butler  (1964)  12  Figure 1-4: S t r u c t u r e s f o r the Proposed A n t i m o n y ( I I I ) Complexes ( P l a n V i e w s )  Sulphide  13  The  simple  and  Smith,  are  stable.  1975)  Antimony shown and  to  Smith,  complex solid  3  only  Sb(III) +  S x  to  2  to  " =  basis  for  have  been  (x-l)SbS  metal  are  considered  sulphides to  in  magnitude  sulphide  if which  1-4  sulphides  shows  One  reported  in  1.1  M  solubility sulphide  of  be  be  in  sulphide for  (Baiborodov  9 ^ 0 ,  its The  1-2)  ...(1-2) and M u r t i ,  1966).  sulphide Various  complexes reduction  1-2).  Chemistry  low  solubility  insoluble.  raised are  by  formed.  alkaline  solution from et  However, many Table  of  2  ,  is  1-3  of shows  solution.  various  given  1975)  metal  orders  (presumably  Cu S  a l .  products  sulphide  s o l u b i l i t i e s  copper  (Moss aqueous  (Equation  antimony  v i r t u a l l y can  been  solution.  "  extremely  measured  in  Na^ SbS^  from  (Sevryukov  complexes  the  2  Sulphide  possible  and oxides  + S  (Table  have  solution  are  "  has  Sb(V)-sulphide  electrowinning.  measured  concentrations  reactions  3 4  example,  spectroscopy  polysulphide  reduction  Alkaline  Many  Table  S b ( V ) by  (Moss  for  2  by M o s s b a u e r  crystallized  industrial  SbC> "  thioantimonate,  be q u a n t i t a t i v e  Miscellaneous  and  be  electrolytic  potentials  1.3.3  can  detected  precipitated),  reported  Sodium  3  (as  5  The  been  oxy-anions,  s 2  1975).  reported  the  S b  Sb(III)  SbS^ ~.  has never  antimony  only  "  The  while  ion  3 +  contain  of 3  Sb  sulphide,  analogue,  (x-l)SbS  is  (V)  is  oxidation  is  aquated  metal  at  25°C).  as  0.014 M  whereas  its  Table  1-2: A n t i m o n y - S u l p h i d e  S b S " + 3e~ = Sb + 2 S "  Complex R e d u c t i o n  E° = - 0 . 8 5 V  2  2  SbS -  .+' 3e"= Sb + 3 S "  3  3  1/2  E° = -0.9 V  2  Sb S --« + 3e"= Sb + 2 . 5 S " 2  3  + 5e"= Sb + 4 S "  SbS, -  3  + 2e-= SbS "  4  4  2  5  SbS, -  *REFERENCES: L a t i m e r  o  3  Potential  E° = -0.78 V  2  + S-  (1952),  E° = -0.86 V  2  Baibordov  E° = - 0 . 6 1 V  et a l .  (1975)  15  Table  1-3:  Reactions Forming Soluble Sulphide  Complexes*  Log Ag  + S-  +  =  2  HgS( ) + S" s  AS S 2  SnS 2Au  2  3  2  (s)  *Rererences:  0. 58  = HgS -  2  2  + S"  + 2HS"  23. 9  AgS"  ( a ) + 1/2  S2  2  =  AsS  = SnS  + 1/20  Sillen  K(298)  1. 0  2  5. 04  "  2  3  (g) = 2AuS" +  and M a r t e l l  H 0 2  29. 7  (1964); B u t l e r  (1964)  16 Table  1-4:  Sodium  Solubility Sulphide  of  Metal  Metal  Cone.  (10'*  M)  Na  S 2 (M)  Cone.  0.368  1.10  ZnS  0.384  1.10  CdS  0.1  1.10  FeS  1 . 96  1.4-0  14.05  S  1.10 *  2 Cu  S  2 Mo.S 2 S  1.8  1.45  9  1.40  1  1.40  2 PbO  0.7  1.45  ZnO  5.5  1. 53  CdO  1.9  1.45  0.05  1.45  2.1  1.45  Bi  Fe 2 NiO  and  Solution*  PbS  Cu  *Reference:  Sulphides  0 3  Baibordov  et  a l .  (1975)  Oxides  in  17  The with  temperature.  created hot  solubility  by  the  natural  localized  Arsenic's  is  3.5  more  sulphide  solution  favour  As(III)  metal and  Shoesmith,  form  solution The  M MCI or  K.  pH  11-12.  25°C 1-3)  2 MFeS pH  11  and  solution.  in  )  2  is  addition had  an  an  equal  of  MFeS  2  as  be  a  In in  ions  a l k a l i (Taylor neutral  The  dispersed  to  sulphide  green-black  colour.  acetone, H 0  ' x  2  AsS "  1976).  to  ferric  of  Sb(III)  investigated  intense  KFeS2  to  structure.  volume  that  solution  reported  of  solid,  NaFeS2and  been  chain  n  Sb(V)  sulphide  that  analogue.  (Baiborodov,  recently  c o l l o i d a l  both  6H  =  +  2M  greater At  presence  As(V)  iron  (FeS  It of  a  to  from  to  shows  antimony  reduced  from  1978).  similar  1-3  be  2  decomposed  in  1 M MOH o r  1  where  M is  Na  acid  solution  .  +  2  a  the  addition  At  is  and  can  sulphides  Craig,  is  increases  deposits  solid  and  its  Thioferrate  with  flocculated  .(Equation  At  1978).  by  furthur  than  has  2  of  1-1  generally  mineral  chemistry  Tables  ferric  made at  of  MFeS ,  speci.es  was  solution  oxidation  of  sulphide  (Vaughan  antimony  thioferrate,  c o l l o i d a l  cooling  stable  existence  minerals  precipitation  comparison  times  The  by  sulphide  A  of  sulphide  Hydrothermal  waters  antimony.  of  of  +  2Fe  they  80°C HS"  +  +  2 +  were  NaFeS  2  (Equation  3H S  +  2  stable,  S° but  ...(1-3) only  decomposed  rapidly  1-4)  •  with  the  with even  HS'  in  in  the  formation  of  polysulphide. 2NaFeS Lithium  2  =  added  2Na  +  as  +  2Fe  2  +  1 M LiOH  +  S  2 2  "  +  2S "  dispersed  ...(1-4)  2  dry  solid  NaFeS  2  and  KFeS  2  18 and  ferric  1.4  The  oxide/hydroxide  Sunshine  Leaching is  carried  propeller a  tank  When  M)  leach  are  for  and  f i l t r a t i o n  14  The  clear  in  an  a  canvas  anolyte  The  is  fully  The  shipped  and  a  the  covered,  pumped  leaching  strength  up  into  cycle.  and  to  are  slurry  is  solids  are  wet  f i l t e r  solution  non-adherent  anodes,  Both  separate  used  to  a  caustic  300^/1  fed  pumped  (3.8  in.  The  to  a  batch  filtered  copper  cake  in  is  twice  smelter.  contains  an  electrowon  depost: of  the  anodic  95% S b ,  mild  separated  leaching by  is  made  storage  for  'de-sulphided' oxidized  also  which  diaphragm.  catholyte  is  settle.  and  solution  about  is  is  sulphur  concentrate  product  pregnant  circulated  which  the  ton,  100-103°C.  the to  solution  elemental  Na?S  20  1944)  The  .Na S 9  and  mild  steel  moisture.  producing Ag.  at  d i f f i c u l t  20%  oz/ton  hours  washing is  the  Holmes,  four  begin  95°C  tetrahedrite  allowed  than  10  of  bring  to  1973;  in  Barren  c o i l s  reaches  (Barr,  basis  tanks.  steam  to  plant  batch  steel  leaching,  water  cathodes  a  by  added  After  more  on  tons  goes  with  out  produced.  Process  Sunshine  solution  five  thickner  the  heated  the  and  at  agitated,  and  solution  Leach  was  tanks and  until to  autoclave.  the  and  The  are  the  up  The  plus  anolyte The  fresh spent  sodium  6-  immersed  catholyte  spent.  make  reactions.  5% A s ,  steel,  from  catholyte  on  by are spent  anolyte anolyte  antimonate  19  which is  is  'de-sulphided'  fully  oxidized  produced, liquid  sent  to  the  elemental  leach  sulphur  directly.  S  2  =  settled  solution ~ ,  °  s 2  2 3  1-5  2S " 2  (x-l)S°  ~  a n <  and  +  S  +  S  2  2  0 "  sodium  anolyte  antimonate  releached  while  the  pond.  generated  ^  spent  from  polysulphide,  caustic  S ^  2  " ,  are  and  formed  1-6) "  2 3  and  tailings  is  The  The  out  concentrator  (Equations +' 6 0 H -  reactions.  autoclave.  is  the  anodic  an  6  Since  4S°  in  NaSb(0H) ,  is  by  =  +3H 0  ...(1-5)  2  S  "  2  ...(1-6)  x Oxidation  produces  pentavalent  form  sulphate. as  The  SbS^ ~  leached  due  3  to  antimony  the  exists  oxidizing  in  power  the of  polysulphide. At  the  cathodes  thioantimonate SbS The  3 4  "  +  complex 5e"  current  reduction  =  Sb  is +  oxidized  the  electrowinning  reduced  4S  efficiency  of  (Equation  of  2  to  metal  c e l l s  (Equation  ~  the  .1-7) .  ...(1-7)  of  this  sulphur  process  species,  is  lowered  primarily  by  the  polysulphide  1-8). S  2  -  +  2(x-l)e"  =  x S "  ..(1-8)  2  x Sulphur caustic  oxidation  take  place  at  reactions  the  anode  which  consume  (Equations  1-9  sulphide  and  1-10,  and for  example). S "  +  1/2  S 0  2  30H2  2 3  "  The  anionic  the  diaphragm  =  1/2  +  50H-  anodic and  S  2  0 =  2 3  -  S0  +. 3 / 2 2 4  "  products  +  H 0 2  5/2  are  electrostatic  + H O  kept  4e" +  ...(1-9) 4e"  away  forces.  ...(1-10) from The  the  cathode  creation  by of  20  diaphragm adds t o i t as transport  number.  catholyte against A partial given  i n Table  the  OH"  ion  Sodium i o n s m i g r a t e  has  a  relatively  from t h e a n o l y t e  high to the  the anions.  mass b a l a n c e 1-5.  about the Sunshine  leach  plant  is  Table  1-5:  Sunshine  Wt (%) In:  Silver  Out:  Ag-Cu Sb  Cone  Residue  Solution  Discard  *Reference:  Anolyte  Barr  100  91  Cu (%) 25.0  27.5  Leach  Sb  Plant  Ag (OZ)  17.0%  1300  1.5%  1429  Balance*  % Distribution Cu Sb Ag 100  100  100  8.03  8.1  70  g/1  81.97  0.9  10  g/1  10.00  (1973)  100  100  22  Chapter  Exper  2.1  2.  imental  Materials  Tetrahedrite  2.1.1  Tetrahedrite Mining  Co.,  8-mesh  screen  Concentrate  concentrate  Sunshine,  concentrate  to  Idaho.  break  up  contained  was The  the  received  material  lumps,  from  was  mixed  approximately  the  passed and  7.5%  moisture  (shown  in  Sunshine  through  bagged. and  an The  was  used  Appendix  B)  wet.  X-ray indicated  diffractometer the  chalcopyrite,  presence pyrite,  Additional  phases  were  unassigned  lines,  but  designation  X-ray  results  of  tetrahedrite,  marcasite  and  undoubtedly the  large  fluorometry  indicated  arsenic,  zinc  and  atomic  number  greater  than  22  used).  A partial  partial  in  present  as  number  tetrahedrite,  the  concentrate.  represented of  lines  by  made  the their  d i f f i c u l t .  silver,  Table  galena  total  copper,  in  argentian  2-1. chemical  chemical Table  lead were  analysis  2-2  analysis  the  shows of  (only detected  of wet  each  presence  the  of  elements by  the  concentrate  screening fraction.  antimony, with  an  instrument is  results  shown with  Antimony  a  was  Table  2-1:  Chemical  A n a l y s i s of S u n s h i n e  Concentrate  % Cu  26.0  Fe  14 .6  Sb  13.1  S  29.1  As  1. 58  Zn  1. 67  Mn  0.19  Na  0.00  Ag  3.6*  * A n a l y s i s done by  third  year M e t a l l u r g y l a b students.  (Dry)  24 Table  Fraction (Mesh size)  2-2:  %  Wet  Screening  Results  Sb  Analys i s Cu  Retained  (%) Fe  +  100  2.0  11. 5  20.6  17.1  -100  +  140  5.7  11.1  20.8  19.1  -140  +  200  11.3  10 . 6  22 . 5  18.8  -200  +  270  13.6  10.2  24.2  17 . 3  -270  +  400  11.5  14.0  25.2  20.4  52.7  13.6  27.8  13.4  12.6  25.8  15.8  -400 Screen  Loss  Weighted  Mean  3.2  (96.8%)  25 slightly  more  A  concentrated  mounted  using  the  x-ray  microscope iron,  energy  sulphur.  The  zinc  The  and  tetrahedrite content.  However,  (galena)  were  phases  containing also  found.  atomic  The  number  Based  the  concentrate ( C u 4.6 (Fe  9  -  , F e  7  FeS 0  0  <  .  5 Z n f  natural  5  The 0  g  , C u *  in  a  and  8  1  0  0  )  7  of  copper  and  ) ( S b  sealed by  iron  3  >  is  in  large  sulphur  and  sulphur with  study.  the  Particles  manganese  oxides  elements  A s  4  0  with  shown  6  ) S  the  were  with  an  done,  the  described 1  1%  in  absorption  under  observed  its these  was at  as  3.0  indicated,  CuFeS  (Cu  g  Q  A g ^  compositions  The  Appendix  flask  of  +  3  1.2).  concentrate  atomic  analyses  be  agitated  dissolved  lead  conforming  mineralogical  (Section  and  and  dispersed  of  lead  detect  composition  conforms  the'  and  can  best  , A g  energy  the  only  contain  antimony  quantities of  to  9.  tetrahedrite  analysis  concentrate's Iron  i  lead  particles  analyser  chemical  calculation  sample  overnight solution  0  and  copper  studied electron  found  copper,  diffTactometer  than  tetrahedrites  composition  A  , Z n  was  because  as  iron,  can  as  small  well  SEM x - r a y  greater  on  well  was  scanning  phase  containing  the  and  concentrate a  sulphur  so  as  in  of of  undetectable  found,  s i l i c a ,  as  used  particles  determined  sample  arsenic  be  fractions.  tetrahedrite  overlap,  would  fine  analyser  commonly  virtually  the  polished  (SEM).  s i l v e r ,  peaks  and  in  + ) of  concentrate  C.  leached room  indicated  with  1%  temperature.  HC1 A  that  10% o f  had  been  extracted.  conditions  w i l l  copper  have  the  been  26 present as o x i d e s or s a l t s ,  2.1.2  but not as s u l p h i d e s .  Reagents  Reagent used  in  grade  the  sodium  leaching  hydroxide  studies.  and sodium  Deionized  sulphide  water  were  was  used  throughout. A  100  ml s o l u t i o n  made up u n d e r species  gave  sulphur ^  (S°  0.945  ,) x-1  2  for  caustic  2  no  SO ': 2 3  was n o t d o n e . ) j s i m i l a r  p e r mole  of  the  " , 0.024 M  1.010  2  c o n t e n t - t h e s e cave  of c a u s t i c  2  ( 1 . 0 0 2 M) was  2  Analysis  M S " , 0.041 M SO  and  analysis  moles  24.07 g o f N a S ' 9 H 0  anaerobic conditions.  sulphate their  with  M  sulphur  polysulphide  total  sulDhur.(A  s o l u t i o n s were a s s a y e d  0.019,  0.026,  and  0.030  sulphide.  2.2 L e a c h i n g A p p a r a t u s  The  leach vessel  was a r o u n d  bottom.  The f l a s k  stirrer  shaft passed encased  The  stirrer  cm  per  the  narrow-necked  full  was a t r i a n g u l a r  side,  speed  2 cm l o n g . flasks  i n a 5 cm s e c t i o n section  This  and gave  when t h r o t t l e d  were t o o v i o l e n t  flask  with a f l a t  w i t h a r u b b e r bung t h r o u g h w h i c h a of glass  tubing.  of T e f l o n , a p p r o x i m a t e l y  stirrer good  of t h e Eberbach L a b - S t i r  were u n r e l i a b l e stirrers  was s e a l e d  150 ml p y r e x  was e a s y  to insert  m i x i n g a t 1400 motors  used.  t o lower speeds  a t 1400 rpm.  and  rpm,  These  1  into the  motors  conventional  27  The.leach steam a  m a i n t a i n e d by a v i o l e n t l y  b a t h e q u i p p e d w i t h an a u t o m a t i c w a t e r  large  Lindberg hotplate.  accomodated was  t e m p e r a t u r e was  Four  level  leaching  immersed t o t h e neck  r i n g s p l a c e d t o keep the exposed  with  control  2-1.  Each  the c o n c e n t r i c  boiling  s e t on  experiments could  s i m u l t a n e o u s l y a s shown i n F i g u r e  clamped  boiling  water  flask  steam  surface  be  bath  area to a  mi n imum. The  t e m p e r a t u r e of the l e a c h m i x t u r e  99.6°C.  This steady state  immersion  of t h e f l a s k  2.3  Procedure .  Leach  Four, initial by  leaching  solutions  diluting  sulphide  water  well-sealed oxidation  in sealed  bottles during  flasks  and  with  sample  of  stirrers water hours  were  bath,  flasks  each the  under  solid  was  flasks  were  were  clamped The  only  to  weighed  added  by The  into leaching  the  The or  avoid  dissolved  used  for analysis.  begun.  to  n i t r o g e n and  c o n c e n t r a t e was  retained  reagents  was • t a k e n  sulphide  solutions  the a g i t a t i o n  (± 15 m i n u t e s ) .  Care  reagent  Wet  pre-mixed  inserted, and  sodium  solid  storage.  leaching a  of  be  after  w e r e done s i m u l t a n e o u s l y .  solutions. The  to  achieved f i v e minutes  w e r e made up by d i s s o l v i n g  stronger  measured  the bath.  experiments  oxidation.  deaerated  into  v a l u e was  was  in  small  minimize into  the  pipette bungs  and  boiling  t i m e was  24  28  Figure  2-1  The  Leaching  Apparatus  29 The  leach  industrial was  temperature  practice  easy  to  concentrate  used  antimony  extraction  target.  Twenty-four  for  the leach After  15  ml  was  filtrates  S°  sample  of  The  was  initial 2  ".  glass  and  s o ", 2 3  and  Excess  equilibrium.  An  was  the  t o be an a d e q u a t e  time  were r e m o v e d  frit.  pressure  filtered  The  of  product  The  SO  2  were a n a l y s e d f o r Sb.  funnel  42).  The  OH',  Sb and  Buchner  for analysis along  solution  a n a l y s e s were done  weighed  and  of  solution  retained.  t h r o u g h would  with show  polysulphide. 2  leach  using  retained  s o l u t i o n s were a n a l y s e d f o r S *,  final ", 3  each  t h e f r i t s were p r e - f l u s h e d  not done, the f i r s t  leach  bulk  were d r i e d ,  colour  a  t a k e n and  (Whatman No.  solids  yellow  f r o m t h e b a t h and  w a t e r washed on a B u c h n e r  filtrates.  leach  The 2  x~* 1 '  bath.  equilibrium  considered  e a c h was  f i l t e r paper  characteristic  3  at  the  leach plant,  water  chemical  50%  pressure f i l t r a t i o n ,  If this  S0  than  the f l a s k s  pressure  Before  and  achieve  with  equilibrate.  fine  immediately.  conformed  boiling  w e r e made up t o 500 ml and  the  The  a  h o u r s was  dewatered  pre-weighed  the  to  through a fine  slurry  N^.  with  of l e s s  leaching,  slurry  under  with  to  100°C  o f t h e S u n s h i n e M i n i n g Co.  maintain was  of  s  2°3  s o l u t i o n s were a n a l y s e d f o r As.  The  Buchner  2  S ", 2  filtrates  30 2.4  Sulphide  To  Oxidation  investigate  were  bubbling  with  a  a  2  "  2 3  and  expected  2 . 5  was  observed .  be  ml  of  Over  in  0.855  85  two  taken was  per  minute  after  2  flasks  hours  result  ml  M Na S  solution  samples  (This  more  oxidation,  Both  bath.  S°  to  500  solution.  water  oxidation S 0  through  2 M NaOH  boiling  sulphide  of  were  immersed no  analysed  surprising  as  high  vapour  100°C. long.  after  with  leaching  average  weight  based  130  on  ml  was  the  considered of  flasks  was  their  were  well  bungs  and Of 11  12th.  was  appeared than  to a  be  general  problem in  the  sealed,  s t i r r e r s 12  because  leach the  leach  the  leach  immediately  -0.32 1 g  problem  g  g. of  2  " ,  was  phenomenon.  time  at was  flasks  before  and the  evaporation  water  only  the  taken,  (0.2%  (3.8%  of  solutions  measurements  with  -4.96 a  a  weighing  was  solution  Evaporation  rather  of  by  leach  the  be  water  measured  change of  to  the  experiments.  solution.)  experiments  S  "~  Evaporation  complete  for  reactive.)  pressure  Although  in  sulphide  sulphide  E v a p o r a t i on  Evaporation  air  pretreatment  aeration  and  of  per  ml  of  evaporation). in  specific  31  Chapter  Analytical  3.1  Automatic  The S  by  determination and  2  x-1  automatic  system f i r s t wit'h  respect  the  t i t r a t i o n  with  respect  at  constant  value  SO- " ) j 2  equipped  The of  end  a  a l .  ,  produced  when  the  indicator  are  an  in  the  species equation for  3-1  Equation  3-2  be  would  A  was  822  done  t i t r a t i o n  potential as  a  The  difference function  effectively  of  potential  titrations  as  defined true  t i t r a t i o n  curve  about  the  symmetric  of  were  is  the  The  by  the  done  (potential  equivalence  reversible reagent pH  maximum  stoichiometric  t i t r a t i o n  titrant  equation.  symmetric; not.  2  electrodes.  the  electrode  number  equivalence  would  the  1978).  equal  with  symmetrical  et  the  (S ~,  rate.  t i t r a t i o n  if  (Bassett  there  RTS  plotted is  species samples  reference  since  identical  is  and  derivative  A E / 4V,  only  volume)  solution  automatically  of  is  sulphur  Radiometer  addition  point  point  leach  a  This  volume,  A E / A V  of  was  titrant  the  and  indicator-reference  volume.  to  in  indicator  the  time  caustic  using  with of  to  equivalence function  of  t i t r a t i o n  derivative  a  Chemistry  Titration  ,S~0 ~ z j  0 ,  3.  potential  a  point  curve  is  and  and  t i t r a t i o n  as  when  reactant curve  t i t r a t i o n  for  curve  32 H* + OH" 5Fe *  ... ( 3 - 1 )  2  + MhO4- + 8H* = 5 F e *  2  + Mn * + 4 H 0  3  The  titration  the  equivalence point,  error,  equivalence standard  = H 0  point  analytical  2  the d i f f e r e n c e i s small  is  large  between t h e  end  point  and  when t h e p o t e n t i a l c h a n g e a t t h e (Bassett  titrations  ...(3-2)'  2  ef al. ,  have a  large  1978).  Most  equivalence  point  p o t e n t i a l .changes. A  titration  contains or  a species  reactant  symmetry.. for  the  in  error  reaction  the  reaction  i s with  titration  o f OH"  shows type  only of  As  and  ( A pKa  error  of the s p e c i e s as  indicator  titrant have  volume d i s p e n s e d .  to  (Bassett  constant  the  a n d an reaction  I f the interference may  be  difference  required  for  =  12.9)  of s i x  the  et a1. , 1978). (pKa  seen.  clean  The c o -  with  acid  In a l l c a s e s t h e magnitude of depends  heavily  on  the  this  relative  involved.  depending  electrode  for  strength  is  2  a c c u r a c y o f an a u t o m a t i c a l l y the  reactant.  6)  curve  (or the t i t r a n t )  constant  an a c i d  end p o i n t .  titrant  the t i t r a t i o n  a s e c o n d end p o i n t  =  the  when t h e e q u i l i b r i u m  ( p K a =.14.0) a n d S '  one  well  the  two end p o i n t s  titration  quantities  distorts  the reactant  titrations  o r d e r s of magnitude of  i s greatest  i f the s o l u t i o n  interferes with  so,  the t i t r a n t ,  pH  separation  be g e n e r a t e d  approaches the  titrant  acid-base  also  doing  between  species  between  can  which chemically  and  This  interfering  In  error  on s o l u t i o n c h e m i s t r y titrated  giving  end p o i n t  the correct  f a c t o r s , the  a l s o depends  p o t e n t i a l f o r the  The c o n t e n t s o f t h e t i t r a t i o n  be w e l l m i x e d a n d t h e e l e c t r o d e  on  vessel  must be i n e q u i l i b r i u m  33 with  the  solution.  For  the  stirrer dye  analytical  available  was  added  dispersed. used,  0.05-0.20  achieve was  At  the  end  ml  per  minute,  to  give  However,  not  expected  t i t r a t i o n  and  f i r s t  with  Sulphide,  it  of  to  are  Species  and  be  a  was a  drop  slow  that  rapid  the  slow  of  instantly  electrode  the  of  powerful  system  unlikely  rate  was  time  to  equilibrium changes  rates  in  used,  the  large..  derivative  HC1  the  the  to  Because  most  t i t r a t i o n  is  due  were  the  vessel  each  achieved  Sulphur  test  of  errors  Soluble  a  point  points.  sulphide  performed  t i t r a t i o n  end  sodium  3.2.1  the  In  at  The  3.2  used..  to  completely  potential  of  was  equilibrium.  ever  volume  t i t r a t i o n s  shown  curves in  for  Figure  the  t i t r a t i o n  3-1.  Analysis  Polysulphide  Sulphur,  Thiosulphate  And  Sulphite  Determination.  The by  determination  t i t r a t i o n  t i t r a t i o n  with  system  junction  reference  for  analysis  the  (Papp,  HgCl2 and  of  S  2  ' ,  solution  Orion  sulphur  , , x-1  S„ 0 " 2 3 a  specific The  species  method in  and  2  using  Ag/S  electrodes. of  S°  S O , 3  2  '  Radiometer ion  and  used  sulphide  was RTS  AgCl/Cl was  done 822  double  developed  pulping  liquors  1971).  The  active  element  of  a  Ag/S  specific  ion"  electrode  is  a  34  Figure  3-1  The P o t e n t i a l and F i r s t D e r i v a t i v e C u r v e s f o r t h e T i t r a t i o n of Sodium Sulphide with Hydrochloric Acid  35 solid  Ag^S  activities 10"  shows  a  Nerstian  range of of  2  With mercuric  response t o the  the s o l u t i o n junction o f  electrode double  would  plug  a  SO^ ",  is titrated  2  and  the sulphide S "  + Hg  anions:  with HgCl ,  S "  of S " next  filling  2  S ";  S ";S„0 "; x ' 2 3  2  reacts  2  first  (Equation 3-3),  (Equation 3-4).  2  S " + H g * = HgS + (x-l)S°  ...(3-4)  2  !  Though i t i s p o s s i b l e t o d e t e c t for  each p o l y s u l p h i d e ' s p e c i e s  is  best  determined  s e r i e s which the  S "  end p o i n t s  (the only  f o r f r e e s u l p h i d e and  (x = 2,3,...) t h e  on t h e . b a s i s  i s unambiguous.  ion  2  total  2  2 3  "  and SO^ ".  sulphide  o f . t h e f i n a l end p o i n t  Without e x t r a c a u s t i c i n  sulphur  ion  of t h e  solution  t h a t t h e Ag/S e l e c t r o d e  r e s p o n d s t o ) i s n o t s t a b l e e n o u g h t o be d e t e r m i n e d S 0  and  2  ... ( 3 - 3 )  2+  independently  The s o l u t i o n must be made up t o 0.1-1.0  2  a  solution  = HgS  2  of  this,  KOH.  of s u l p h u r  2  forms  reference  To a v o i d  i s u s e d w i t h an o u t e r  to  In sulphide  AgCl/Cl  2  1 0 % KNC"v> made up t o pH 12 w i t h When a m i x t u r e  normal  with p r e c i p i t a t e d Ag S.  junction electrode  10°  i o n i n s o l u t i o n a HgS f i l m  t h e membrane w h i c h must be o c c a s i o n a l l y r e m o v e d .  solution  of  which  o f Ag* a n d S ~ o v e r t h e a c t i v i t y  M i n each.  7  on  membrane  M  NaOH. After the  the  sulphide  end p o i n t  the t i t r a t i o n  i s s t o p p e d and  e x c e s s c a u s t i c i s n e u t r a l i z e d (pH 7.0-7.5) w i t h  acid.  The  determined  titration together  is  restarted  and  a t t h e n e x t end p o i n t  S 0 2  2  40%  ~ a n d SO^ " a r e  (Equations  2  3-5 a n d  6) . S  2'°3 " 2  +  H g 2  *  =  H(  3 ?°3 S  acetic  ...(3-5)  3-  36  S0 Although  S  detects  the  coupling  of  by  ~ does  2  Hg  + S0  2  "  +  not appear  "  + IT  can ^  n  u  sulphur  reported species  and S 0  and  S " and S O  2  The  Equation  3-1.  2  = S  2  2 3  -  as  + SC>  - +  after  to  sample  of  i s  solution  reagent  grade  are  warmed  to  oxidize  analyses  a n d made  3  the  determined  s  3-7).  ^  mild  heating  with  2 3  "  2 3  of  '  (S°  A  by by  into  species  100 m l .  difference); difference).  to  60 m l w i t h  The HgCl give  a  S  2  pads 2  as  follows:  beakers  and the  solution  " t i t r a t i o n  2  water.  microspatulas  for  of  with  deaerated  the beakers  two a s b e s t o s  i s  containing  5 ml a l i q u o t s  t i t r a t i o n  Two  total  determinations:  1 M Na S s o l u t i o n  up t o  would  incremental  S° . x-1  sets (S0  up t o  polysulphide.  and the  of  beakers  15  minutes  used of  in  the  5 ml  for  described.  practice  large,  three  immediately.  over  *  by t h e  ...(3-8)  sulphur  a r e added  on a h o t p l a t e  ~  2  a  are pipetted  was 0 . 0 5 M which  sample  In  a n d made  Na S0 2  for  the other  done  ~  sulphur,  requires 2  are  2 3  0 " 2 3  Na SO, t r e a t m e n t  10 M NaOH,  titrations  2  formaldehyde  2  taken  2 °  S  (Equation  ^ 0  (x-l)S  S * and S 0  of  the end point  3-8).  with  procedure  electrode  ...(3-7)  polysulphide  ';  2 3  the  SO "  oxidized  masked  analytical  diluted  ml  were  after  = CH OH  concentrations  5 ml  the  -  reactions,  formaldehyde  analysis  2  The  2  2  S '  the  s  these  present  (Equation  e  SO^ " i s  is  2  A  t  tn  ...(3-6)  3  3  S 0 ~ 2 3  small  ~ in  2  be  (x-l)SO  excess  2  2  and S  +  x The  Hg *  2  m  S  = HgS0  2  SO^ " with 2  2 ^ 3  3  2  3  Polysulphide N  + Hg *  excess  masking'the HCHO  '  7 3  sharp  the S  2  " end point  and easy  to  peaks  interpret.  of  the derivative  The  3*'  a  n  <  ^  plots ^2^3 " 2  37  +  S0^ ~ peaks  were  2  interpret greater  if  the  volume  than  0.2  ml.  structures Small  were  treatment.  A  volume,  the  shift.  to  be  by  Known S ^ ^  2  poly thionate,  and  S  The  titrant  2  0  2 3  "  end  "  additions or  which  2  X  volume  et  a l .  by  solutions  chemistry  this  "  peak  was  species  effects.  the a  Na SO small  immediately  after  this  suspect  peak  is  was  was  not  was  considered  similar  this  peak  very  that  has  but  2  to  the  in  representing  prime  ,1968),  consumed  oxidized  The  2  S  easy  interference  showed  SO^ ~.  S Ck, ~  (Blausius  always  some  the  differences  point,  in  s t i l l  from  suggesting  were  observed  but  them  smaller  complex  sulphide  was  broader  separating  reproducible  titrant  unaffected  of  and  With  often  quantities  pH  smaller  to  S  "  2  confirmed.  subtracted  where  relevant.  3.2.2  The  To  Effect  the  has  Various dissolved t i t r a t i o n : ratio  of  Antimony(111)  author's  determination solutions  Of  knowledge,  of  the  not  been  by  stoichiometric  ratio  Sb(111)-complexed  S  HgCl  Sulphide  Determination  t i t r a t i o n  2  species  of  technical  solution.  2  incremental  The  in  method  for  the  antimony-containing  reported.  Na S  antimony  a  sulphur  quantities in  On  atomic 2  "  of  to 1.50  sulphide  Sulphide  absorption Sb  was  grade was  1.60  (Table  3-1).  ±  0.13  The to  be  were  determined  analysis.  was  considered  stibnite  The  by  measured  versus  determination quantitative.  the of  Table  Sb  3-1:  S  Sulphide  Added  2 3 (g/lOOml)  Sb  Determination  Calc.  (g/D  Sb  in  Deter.  (g/D  Antimony(111)  s 2  A  (M)  0  1.0*1  0  1.08J  S  Solution  2  -  / ASb  (mole/mole)  .09  0 . 57  4 . 09  4.16  1.15  1.78  1 . 06  7 . 60  7 . 44  1.18  1 . 52  1 . 53  11. 0  10.8  1.21  1.43  2.00  14.3  14.2  1.26  1.53  2.62  18.8  18.6  1 . 34  1 . 64  3.12  22 . 4  22 .1  1.40  1.72  Mean  =  1.60+0.13 (95%  C.L.  39 3.2.3  The  E f f e c t Of  A n t i m o n y ( V ) On  The  Sulphide  And  Polysulphide  Determinations  Sodium  thioantimonate,  procedure, o u t l i n e d q u a n t i t i e s of S~ 2  and  s  this  ° _i  in Table  the  four  Sb(V)-S "  the antimony 3 4  "  + S0  results  2 3  -  3 3  equivalent  but  did  incremental  Sb  drop i n  sulphide  water while  and  Sb  was shown  drop S°  x - 1  were  determined  a quantitative analysis for  S „0_ " 2  2  '.  S 0  +  2  to  2 3  that 3  the  heating  of  affected a reduction  (S°  '  of  ...(3-8)  , a n a l y s i s and  the  to S ~  not  2 3  positive  Various  r e s u l t s are  antimony  added N a S 0  a p p a r e n t S°  c o n d i t i o n s were a p p a r e n t l y  A  a  3-8).  = SbS  show t h a t t h e  treatment  per  (1966) r e p o r t e d  with  (Equation  analysis  the  titration The  by  (1966).  deaerated  analysis.  sulphides  Murti  T h i s w o u l d p r o d u c e an  of  made  sulphide.  solutions  2  The  Murti  HgCl  analysis indicating  S e v r y u k o v and  2  was  3-2. •  Sb(V)-complexed  S"  and  were d i s s o l v e d i n  atomic absorption  sulphide  SbS  Sevryukov  salt  Approximately in  SbS^. 9H ^0,  3  were d e t e r m i n e d by  x  d e t e r m i n e d by  by  Na  amount of  a drop i n  the  present.  The  Sb(V)  r a t i o dropped a f t e r  2  reach  three.  The  the  reduction  Na SO^ 2  reaction  inadequate to complete Equation . ) accounted  f o r o n l y about  3-8.  one-half  x-1  sulphide. in S " 2  assay a f t e r  determination  solution  that  the  Na SO^  treatment  2  i s the author  only has  coupled  with  i n d i c a t o r of Sb(V) found.  However,  a in  the  Table 3-2: Sulphide and Polysulphide Sulphur Determinations In Antimony (V) Solution Polysulphide Sulphur Analysis_  Sulphide Analysis Na.SbS,- 9JL0  L  H  I  Sb c a l c  Sb d e t e r .  S'  (g/1)  (g/D  (M)  5.54  2.19  S° . / S b A S /Sb* s 7sb s 7sb x-1 (mole/mole) (mole/mole) ( m o l e / m o l e ) ( m o l e / n 2  2  2  5.20  0.173  4.05  3.35  0.70  0.35  9.58  0.328  4.17  3. 51  0.66  0.36  4 .08  10.3  8.48  21.5  19.9  0.676  4.15  3.56  0.59  ^ 0.34  16. 50  41.8  38.9  1.33  4.17  3.13  1.04  0.54  * k S ~ i s the d i f f e r e n c e between the sulphide a n a l y s i s and the sulphide a n a l y s i s 2  a f t e r treatment with  fta^i®?.  41 r e d u c t i o n procedure used appears o n l y A  Sb(V).  treatment  proper  analysis  w i t h Na,, SO  would  u n d e r an i n e r t  3  to  be  an  have  to  involve a boiling  gas cover  indicator  to  prevent  of  S " 2  oxidation.  3.3 The D e t e r m i n a t i o n  The  sulphur  products sulphur  Of S u l p h u r  content  of  to barium sulphate,  1  —  1  Caustic  t o take  observed.  In Sulphide  RTS 822 t i t r a t i o n  pH/reference electrode.  With  The  the  conversion  of  1971).  away t h e H S 2  and s u l p h i d e  OH"  2  Polysulphide  s y s t e m and a C a n l a b beaker  found d u r i n g  caustic  and S "  w i t h HC1 s o l u t i o n u s i n g  titrate  in solution,  simultaneously titrates  titrates  as  S " 2  the t i t r a t i o n  chemistry.  combination  was  put  under  the determination. two e n d p o i n t s a r e ( S e c t i o n 3.1)  w i t h an e n d and  decompose, but i t i s not c e r t a i n whether E q u a t i o n describes  the leach  Solution  titration  e n d p o i n t a t pH 7.5 w h i l e HS" 4.5.  (Young,  was d e t e r m i n e d by t i t r a t i o n  Radiometer  suction  BaSO^  by  and  —-•  3.4,1 C a u s t i c D e t e r m i n a t i o n  pH  concentrate  Determination  ;  an  the  was d e t e r m i n e d g r a v i m e t r i c a l l y  3.4 C a u s t i c  a  In S o l i d s  is  point  with at  observed to  3-9  or  3-10  42 S  "  2  + H*  = HS  x S  x  *-  + H*  Since the  S  weak  titrant  points  =  2  "  +  2  determined  by  S° . x-1  bases,  volume  (S "  "  =  HS"  +  S°  . x-1  +  S°  x  + H*  such  as  difference  and  HS")  may  the  result  of  = HS"  S0  ~,  2 3  not the  be  ...(3-10)  x-1  tend  between  ...(3-9) •  to  t i t r a t e  the  two  meaningful.  f i r s t  end  performed  by  with  sulphide Caustic  point  HS",  minus  is  end best,  the  S  2  "  determination.  The sample with  titrations  into  a  were  t i t r a t i o n  beaker,  diluting  pipetting to  60  ml  1  or  and.  2 ml  of  t i t r a t i n g  1 M-HC1.  3.4.2  The  Effect  The with  in  A f i r s t  Table  end  solution,  end  point  second  The  in  Caustic  Section  previous  Determination  3.3.2  section.  were  The  titrated  results  are  3-3.  complex  consistent caustic  minus  the  the  f i r s t  from end  the  2  in  After  in  Sb(IIl):S "  point  On  considered  described  2:1  varying  Antimony(111)  solutions  HC1 a s  given  Of  S  orange  point.  2  is "  with  appeared  to  be  SbS "  or  Sfc^S^ ".  determined  by  the  2  determination  end  to  point  the  black-and  present With  2  plus  result  twice  solutions  at  the  of Sb  developed  Sb^S^ precipitated  the  Sb(III) the  f i r s t  assay.  colours after  the  43 Table3-3:  S  b  Caustic  ml)  in  I deter. A S " /Sb* (mole/ (g/D mole)  Sb  2 %  (g/100  Analysis  2  Antimony  (III)  Solution  I-II  II •1st. E . p . A S2- / S b * * e'qui v . (mole/ (M) mole)  0  1.141  0  •1.12 1.10 j  (mole/ mole)  0 . 57  4 .16  1.78  1 .12  -  -  1 . 06  7 . 44  1 . 52  1 . 09  -0.43  1.95  1 . 53  10.8  1.43  1 . 08  -0.42  1.85  2 . 00  14 . 2  1 . 53  1 . 07  -0.45  1.98  2 . 62  18 . 6  1 . 64  1 . 04  - 0 . 51  2.15  3 .12  22 .1  1 . 78  1 . 03  - 0 . 50  2.22  m e a n .=  *  taken  from  1.99x0.15  Table3-1  ** i\ S 2is the point t i t r a t i o n of  equivalent d i f f e r e n c e between the blanks and the sample  the  f i r s t  end  44 3.4.3  The E f f e c t Of A n t i m o n y ( V ) On The C a u s t i c D e t e r m i n a t i o n  The pH  s o l u t i o n s o f S e c t i o n 3.3 were t i t r a t e d  dropped  instantly  ions appeared  Sb S 2  3.5 A t o m i c  determined  on  after  immediately  t h e 'second'  HC1.  The  No f r e e  S ~  Sb(V)  2  complex,  t u r n e d orange and  end p o i n t .  A b s o r p t i o n And F l a m e E m m i s s i o n A n a l y s i s  Copper,  Elmer  The s o l u t i o n s  precipitated  5  was b e g u n .  t o be p r e s e n t c o n s i s t e n t w i t h t h e  SbS^-3, i n s o l u t i o n . and  as the t i t r a t i o n  with  iron,  by a t o m i c  antimony,  a r s e n i c a n d manganese were  absorption spectrophotometry  306 i n s t r u m e n t .  t h e same  zinc,  S o d i u m was d e t e r m i n e d  on  a  by f l a m e  Perkinemmission  spectrophotometer.  F o r a l l t h e a n a l y s e s , s t a n d a r d s were made up t o a p p r o x i m a t e t h e c o m p o s i t i o n of t h e unknowns. product and  a n a l y s e s two s e t s were u s e d :  antimony,  manganese  in  a  strong  greatly  solution  reduced  standards w h i l e compensating unknowns.  The  taken  of the f i r s t time  sodium and  three  required  to  elements. make  up  f o r t h e flame m a t r i x e f f e c t s of the  antimony  Samples of t h e l e a c h were  arsenic,  iron  unknown a n d s t a n d a r d s o l u t i o n s were a l l made up  2 0 % HC1 t o p r e v e n t  standards  the  leach  one c o n t a i n i n g c o p p e r ,  and t h e o t h e r c o n t a i n i n g z i n c ,  This procedure  in  F o r t h e c o n c e n t r a t e and  hydrolysis.  solutions  and  the  antimony-arsenic  made up i n 0.2 M N a S a n d 0.2 M NaOH.  to avoid mixing  2  t h i s Na~S w i t h t h e a c i d s  usually  Care  was  present  45 in  the burner  head d r a i n  Flexibility absorption length.  having  co-linear  sample d i l u t i o n  b u r n e r head The  concentration by  in  linear  with  is  rotated  burner  be  increased  normal  i s a v a i l a b l e i f the  to  p o r t i o n of e a c h  curve can the  reservoir.  to the  change  element's  the  atomic  flame  absorption  path versus  by a p p r o x i m a t e l y  20  times  lamp beam l i n e  rather  than  i t . Fewer s a m p l e d i l u t i o n s a r e so  required.  46  Chapter  Results  4.1 L e a c h i n g E x p e r i m e n t s  Forty-seven total, the many  but  of  following  and O b s e r v a t i o n s  Considered  equilibrium  leaching  done  in  these, only  t h e r e s u l t s o f 28 a r e c o n s i d e r e d  in  sections.  inconsistencies  experiments  were  and  the  considered  4.2 A n t i m o n y L e a c h i n g  g r o u p o f 16 c o n t a i n e d  results  of  leached  4-1 t o  show  Four l e v e l s  investigated:  interpolated concentrations  0,  through varied.  subsequent  Data  f r o m a l l 47  Results  the  Solutions  concentration  a f t e r 24 h o u r s a t 100°C a s a f u n c t i o n  concentration.  too  D.  - Equilibrium  4-3  three  t o be a n o m a l o u s .  Antimony Leached In A l k a l i n e S u l p h i d e  Figures  were  e x p e r i m e n t s were  A preliminary  r u n s a r e shown i n A p p e n d i x  4.2.1  4.  of  0.5, the  initial  points  caustic  as  antimony  of t h e f i n a l  1.0, a n d 2.0 M .  data  of  Na S 2  concentration C u r v e s were n o t  the  final  NaOH  40 36 h  Initial NaOH v 05 M • 2 M  0.4  0.8 1.2 1.6 Final N a S ( M )  2.0  2  F i g u r e 4-1  The F i n a l A n t i m o n y C o n c e n t r a t i o n s v e r s u s t h e F i n a l T o t a l Sodium S u l p h i d e C o n c e n t r a t i o n s - 0.5 and 2 M I n i t i a l Caustic  48  0.4  08  1.2  1.6  Final Na S ( M ) 2  F i g u r e 4-2  The F i n a l A n t i m o n y C o n c e n t r a t i o n s v e r s u s t h e F i n a l T o t a l Sodium S u l p h i d e C o n c e n t r a t i o n s - 0 and 1 M I n i t i a l Caustic  49  0.02  0.04  0.06  Final Na S 2  Figure 4 - 3  0.08  o i  (M)  The F i n a l A n t i m o n y C o n c e n t r a t i o n s v e r s u s t h e F i n a l T o t a l Sodium Sulphide Concentrations - 1 M I n i t i a l C a u s t i c and Low S u l p h i d e  50 4.2.2  Antimony Leached In C a u s t i c - O n l y  Leaching solutions. found  be  of t h e  caustic  showed two  end  final  = SbCl  2  The  volume  corresponded  to  same f o r a l l  three  solution.  The  approximately Since of  a  antimony  oxide  leaching  of  an  c o n c e n t r a t i o n , and  the  final  and  another  Sb0 " 2  difference  sulphide  was  solutions with  HC1  which appeared  ion (Equation  between  ratio  titrant  leached  suggesting  volume at the  two  initial and  0.3  to  4-1).  not  end 4 and  g/1  caustic  points was  the  Sb  in  point  was  of  s e c o n d end  concentration.  solution  charged  to  results  suggest  that  the  from the c o n c e n t r a t e .  would  t h i s was  the  of a p p r o x i m a t e l y  of c o n c e n t r a t e  oxide  M NaOH  ...(4-1)  were i d e n t i c a l ,  was  no  2.0  2  e q u i v a l e n t to the  experiments  and  " + 2H 0  solutions  the q u a n t i t i e s  these  of  of the  Sb:H*  total  a d d e d and  f o r OH"  4  titrant  1.0  solutions.  p o i n t s : one  " + 4HC1  not  titrations'  f o r the n e u t r a l i z a t i o n SbO  were done i n 0.5,  S o d i u m s u l p h i d e was  i n any The  experiments  Solutions  increase observed.  the  However, net  each an the  caustic  51  4.3  Leaching  I n Weak S o d i u m S u l p h i d e S o l u t i o n s W i t h o u t  Added  Caust i c  Four Na S 2  experiments  without  added  were done a t 0.03, 0.06, 0.09 a n d 0.12 M caustic.  The  resultant  slurries  were  unfilterable  by t h e p r e s s u r e a n d vacuum t e c h n i q u e s d e s c r i b e d i n  Section  After  2.3.  the excess  c o n c e n t r a t e was a l l o w e d t o s e t t l e  t h e s o l u t i o n s were t h e d e e p g r e e n - b l a c k thioferrate. presumably  Added a c e t o n e  Arsenic,  result  was o b t a i n e d by SEM x - r a y a n a l y s i s on a d r o p  silicon,  solution  antimony,  s u l p h u r were p r e s e n t .  the copper  evaporated  onto a  i r o n and copper  The i r o n peak was  peak a g a i n s u g g e s t i n g t h e p r e s e n c e  The  0.12 M N a S p r o d u c t 2  the black f i l t r a t e  experiment.  The  thioferrate  thioferrate  solution  supernatents present  would  have  was  produced  of p o l y s u l p h i d e ( S e c t i o n  deceptive  result solution.)  as w e l l much  as sodium  larger  than  of NaFeS . 2  M  were c o l o u r l e s s stable.  carbon > stub.  e v e n t u a l l y f l o c c u l a t e d as  f r o m a 0.45 M Na S / 0 2  indicative  alkaline  material,  t h e s e s o l u t i o n s were n o t q u a n t i t a t i v e l y a s s a y e d , a  of 0.12 M Na^ S p r o d u c t  the  a  2  qualitative  did  to flocculate  N a F e ^ • xH 0 .  Although  and  appeared  c o l o u r c h a r a c t e r i s t i c of  The  NaOH  leaching  indicating  decomposition  a yellow supernatent 1.3.3).  that  (This  of  solution  may  be  a  s i n c e p o l y s u l p h i d e i s not a s t a b l e s p e c i e s i n  52  4.4 The E x c e s s Of C o n c e n t r a t e U s e d  Excess in  c o n c e n t r a t e was c h a r g e d t o e a c h  an e f f o r t  Antimony the  to  e x t r a c t i o n s of l e s s  antimony  35%.  equilibrate  the  one  extraction  During material  the  with  solutions.  In a c t u a l i t y  i n Appendix  Of The L e a c h e d  Product  The e x t r a c t i o n s a r e  D.  Slurry  the leach the concentrate d i s i n t e g r a t e d  into  finer  to f i l t e r .  These  fines,  t h e e x c e s s c o n c e n t r a t e used produced  a very  thick  which  together  experiment  b e t w e e n 8 a n d 6 2 % w i t h a mean o f  was a b o v e 5 0 % .  tabulated with the leach data  4.5 F i l t e r a b i 1 i t y  with  t h a n 5 0 % were s o u g h t .  extractions varied  Only  solids  leaching  p r o v e d t o be d i f f i c u l t  I  product  slurry,  concentrations. to  be i m p o s e d  particularly A practical  i n those runs which had h i g h Na S 2  experimental limit  to achieve a s o l i d / l i q u i d  of 2 M  N a 2  S  had  s e p a r a t i o n a t t h e end of  leaching. The produce funnels for  10 ml  filtration  of  filtrate  were u s e d  fine  analyses  solids  of  (flocculated)  5-10  25 p s i g  minutes.  of n i t r o g e n t o Large  Buchner  t o a c h e i v e r e a s o n a b l e vacuum f i l t r a t i o n  the f i l t r a t i o n  solids  required  in  the bulk of the s o l u t i o n s .  leached be  pressure  During  water  r a t e s dropped  broke through t h e f i l t e r  these  solids  indicated  that  when iron,  they  washing  rates  of  the  a n d what a p p e a r e d t o paper.  The SEM x - r a y  eventually  sodium  and  settled  s u l p h u r were  53  present.  When t h e  caustic  solution  leached  solids  the  washed  with  i n s t e a d of w a t e r , t h e f i l t r a t i o n  drop, nor d i d m a t e r i a l break and  were  SEM a n a l y s e s  seem  through.  This  indicative  a  weak  r a t e d i d not  filtration  behavior  of t h e p r e s e n c e of sodium  thioferrate. As w e l l a s f i l t e r i n g settle liquid  well.  If  poorly,  allowed  were p r o d u c e d o v e r 10 cm o f s l u r r y  Figure  4-4  concentrations against  in  leached  shows  the f i n a l  sulphide  and f i n a l  a n d on a r e l a t i v e  the  total  Na S 2  solutions plotted-  The d i f f e r e n c e s  basis.  e x c e p t one.  The a b s o l u t e  d r o p was u n r e l a t e d  one  At  low  a l l the  antimony  are  A small net drop  in  concentration extraction  in  was o b s e r v e d  l o s s rose  The  differences  the i n i t i a l  antimony c o n c e n t r a t i o n . relative  of c l e a r  concentration  experiments  not  i n 10 m i n u t e s .  antimony c o n c e n t r a t i o n s .  on an a b s o l u t e  5 mm  did  Concentration  the  between  solids  to s i twhile hot, only  4.6 The Change I n S u l p h i d e  shown  the  (low  equilibrium to the  sulphide)  the  sharply.  run  which  was t h e o n l y  e x c e e d e d 50%.  showed experiment  a  net in  increase which  the  in  Na^S  antimony  I n t h i s c a s e t h e e x t r a c t i o n was 6 2 % .  54  "  A  A  •  V  ?°  V  -©  i 5  -  °  °  o  1  1  10  15  * Q  I 20  Sb  °.  25  <  35  30  (g/1)  -o  Initial NaOH A 0 M v 05 M o 1 M o 2 M  •  A  "  °A  ° o °  O A  -  V  —1>—  o *  o  •  O  o  -  0  *  °A  5  i 10  1  15  Sb F i g u r e 4-4  1  20  25  30  , i 35  (g/1)  The D i f f e r e n c e s Between t h e I n i t i a l and F i n a l Sodium S u l p h i d e C o n c e n t r a t i o n s A b s o l u t e (Top) and R e l a t i v e ( B o t t o m ) , v e r s u s t h e F i n a l Antimony C o n c e n t r a t i o n s  55 4.7 The Change I n C a u s t i c  Concentration  Fi'gure 4-5 shows t h e d i f f e r e n c e s i n t h e NaOH between t h e f i n a l  s o l u t i o n s and those  solutions  as  f u n c t i o n of t h e f i n a l  ascending  solid  and the  a  line  2.0 M i n i t i a l points If  against  was f i t t e d  a p p e a r t o be  t h r o u g h t h e p o i n t s f o r 0.5,  1.0  the broken l i n e  NaOH p o i n t s o f F i g u r e  corresponding associated  Figure  4-6  data with  shows  concentrations  and t h e f i n a l  4-2 a r e s e l e c t i v e l y  fitted  through  slope. 4-2  are  compared  ( A p p e n d i x D ) , t h e 'low p o i n t s '  smaller a  concentrations plotted against  Figure  An  2  f o r no a d d e d c a u s t i c h a d a n e g a t i v e  the  points'.  c a l c u l a t e d f o r the i n i t i a l Na S c o n c e n t r a t i o n s .  c a u s t i c , while  the 1 M i n i t i a l  concentrations  plot  the  ^OH's of  than  the  product  of  leach the  NaOH c o n c e n t r a t i o n s . shifted  producing  the  'high  antimony  final  Na S 2  The p o i n t s o f  Figure  4-6, a p l o t  w i t h much l e s s s c a t t e r . j  The rather of  initial calculated  NaOH  concentrations  from t h e added c a u s t i c .  t h e N a S was d e t e r m i n e d t o be  (Section  2  2.1.2).  were  A  leach s o l u t i o n caustic  0.02  -  not  measured  The c a u s t i c 0.03  mole  but  content  per  mole  c o r r e c t i o n was n o t a p p l i e d t o t h e i n i t i a l assays.  56  0.4 V  O  0.3  O o  ^  0.2  ._ x  n u  •  V  V.  1  0.1  O  (o)  Initio! NoOH  0  A 0 M V 0.5 M O 1M O 2M  -0.1  \  \  "A !  0  0.5  1.0  1  1.5  2.0  Na S ( M ) 2  F i q u r e 4-5  The D i f f e r e n c e s Between t h e I n i t i a l and F i n a l Sodium H y d r o x i d e C o n c e n t r a t i o n s v e r s u s t h e F i n a l Sodium S u l p h i d e Concentrations  Final Figure 4 - 6  Na S x Na OH 2  ( M ) 2  The F i n a l A n t i m o n y C o n c e n t r a t i o n s v e r s u s t h e P r o d u c t of t h e F i n a l Sodium S u l p h i d e and Sodium H y d r o x i d e Concentrations (1 M I n i t i a l Caustic)  58  4.8  Arsenic Dissolution  Figure  4-7  shows t h e a r s e n i c  solutions plotted against 4-2  was  fitted  through  A s ( g / 1 ) = 0.21 The by  broken  experimental due  to  + 0.068 S b ( g / 1 )  cross their  ratio  i s less  than  available  the c o n c e n t r a t e  the  At  arsenic-sulphide  higher  through  The  slope  is  represented  slope  of t h e  low  of  concentrate  sulphide  these  the line  lines  c o m p l e x e s a r e more s t a b l e  and  because  of a r s e n i c a v a i l a b l e a t t h e At  Equation  i n s o l u b l e a r s e n i c - c o n t a i n i n g phase -  antimony c o u n t e r p a r t s  surfaces.  leach  ...(4-2)  2.1.1).  a r s e n o p y r i t e , AsFeS ,  because  quantities  of  (Section  t h e p r e s e n c e of an  most l i k e l y  .12  the p o i n t s .  line  line  of  the antimony c o n c e n t r a t i o n s .  a r s e n i c to antimony the  concentrations  sulphide levels  the d e c o m p o s i t i o n  there  were  exposed m i n e r a l  t h e a r s e n i c was of  than  adequate particle  . only  made  tetrahedrite. <?  The artifact The  zero-intercept created  true value  by  the  of  the  linear  i s probably  fitted  least  smaller.  line  squares  (0.21  g/1  As)  i s an  f i t w h i c h was  done.  0  4  8  12  16  Sb F i g u r e 4-7  20  24  28  (g/1)  The A r s e n i c V e r s u s t h e Concentrations  Antimony  32  60 4.9 The P r e s e n c e Of O x i d i z e d S u l p h u r  and  The  results  so  for  pattern.  of t h e a n a l y s e s  Sb(V)  quantities  oxidized  the o x i d a t i o n problems  separation  determination  for  And A n t i m o n y ( V )  (Section  2.3)  these  species  were  species systematic  identified and  ( S e c t i o n 3.2..1), i t i s u n l i k e l y  of  sulphur  ( S e c t i o n 3.2.3) d i d n o t show any  Considering  solid/liquid  Species  present  in  that  i n the  the  S° _i x  significant  a t t h e end o f t h e  leaches.  4.10 A n t i m o n y And S u l p h i d e  Figures  .4-8  concentrations time.  of  curves  4-9  four  The a n t i m o n y  sulphide given  and  show  the  leaching  curves  are  i n A p p e n d i x E.  Concentrations  show  V e r s u s Time  antimony  experiments a  more c o m p l e x .  and  sulphide  plotted, against  regular  rise,  while  The d a t a  f o r these  the  runs i s  32  0  /  I  1  0  300  1  600  .  1  900  1 1200  1  1500  Time (min.) '  Figure  4-8  The S o l u t i o n Antimony as a F u n c t i o n of Time  Concentrations  ^  I.55T-  10 CM O  0.85$-  co  0.75  (M  o  0.65 0.55  200  400  600  800  1000  1200  1400  Time ( M i n ) Figure 4 - 9  The Sodium S u l p h i d e C o n c e n t r a t i o n s as a F u n c t i o n o.f Time  t-o  63  4.11 A p p e a r a n c e Of The C o n c e n t r a t e And P r o d u c t  Figures concentrate times. Table while  and  and  4-11  show  SEM  the leached product  4-2,'  leach  the product than  4.12 X - r a y  The  solids  s o l i d s are not.  The  concentrate consistent  is  leached  described  diffraction to  the  line  pattern  decomposition with i t s 'fuzzy'  tetrahedrite  spectra, and  are  Solids  pattern.for for  product  the was  the product  solids  concentrate. x-ray  The  . amorphous,  appearance.  Product  By  Microanalysis  Figure  polished  in  particles  4.13 C o m p a r i s o n Of T e t r a h e d r i t e And The D e c o m p o s i t i o n Electron  the  in size.  P i f f r a c t o m e t r y Of The P r o d u c t  identical  of  2.) The c o n c e n t r a t e i s o b v i o u s l y c r y s t a l l i n e  1 um  x-ray  micrographs  s o l i d s a t 2,100 a n d 21,000  (The p r o d u c t i o n o f t h e p r o d u c t  much l e s s  was  4-10  Solids  4-12 and  shows SEM x - r a y decomposition  analyser  superimposed  differences tetrahedrite  are  500,000  and t h e l a r g e  from  ( l e a c h 2, T a b l e  4-2).  The  c o u n t s e a c h , a r e shown s e p a r a t e l y  to accentuate t h e i r the  taken  p r o d u c t a r e a s on a m o u n t e d a n d  sample of l e a c h e d m a t e r i a l containing  spectra  differences.  disappearance  of  i n c r e a s e of i r o n  the  The  greatest  antimony  i n the product.  from The  (a) F i g u r e 4-11  (b) The T e t r a h e d r i t e C o n c e n t r a t e (a) and t h e L e a c h P r o d u c t S o l i d s (b) a t 21,000 x U1  66  A: Tetrohedrite  *  •x •  ***** . • B : Decomposition Product  * A *v-v .  A.  A and B Superimposed A i i  Cu As Na Si  I  Ag ^  Mn Fe Fe  CU  Zn  t Cu  F i g u r e 4-12 SEM X-ray. A n a l y s e r S p e c t r a f o r t h e T e t r a h e d r i t e and t h e D e c o m p o s i t i o n P r o d u c t Phases  67 product  also  gained  tetrahedrite and  zinc  lost  found  qualitat  analysis  on  error  limits  antimony  light  it  on.  the  a  tetrahedrite.  the  tie,  stated,  manganese show  (These  results and  while  both  the  spectra  these  results  one  iron  The  microprobe  that  the  and  one  sulphur  element  analysed  a  decomposition not  was  possible  the silver  are  only  decomposition the  minute  to  give  exactly  the  beam valid  lead  analyses. and  the  areas to  the  had  within  added  for  This  the each  program,  incorrect  due  occurs  to  when  matrix.  of  varying  density  the  beam .was  focused  were  rough  poor  Tetrahedrite  sample  analysis.  100%.  what  areas.  computer  were  and  that  are  element  fine  product  factors  product  a  heavy  to  These  microprobe  than  microprobe  product  indicate  analysis  was  know  electron  sulphur  product  polishing  soft.  in  an  analyses  more  is  of  decomposition  correction,  Despite  under per  as  warned  was  product  and  products  absorption  The so  The  tetrahedrite  extracted.  IV,  a  the  shows  the  copper  high  arsenic.  in  4-1  With  a  s i l i c o n  ive.)  Table  Magic  sodium,  to  be  since  the  precision  in  was  not  moved  stable a t 50jj.m  68 T a b l e 4-1: M i c r o p r o b e A n a l y s i s  Tetrahedrite (atom %) v  No. o f P o i n t s Analysed  Tetrahedrite* Cu-tie ( a t o m %)  Decomp. Product (atom %) (atom %)  8  S  4 6.4+0.4  39.8  50+6  + 10  Cu  3 5.0±0.5  30 . 0  30+6  0  Fe  5.3±0.3  4.5  20 + 3  + 15  Sb  13.3+0.4  11 . 4  0+0  -11  *The t e t r a h e d r i t e a n a l y s e s were a d j u s t e d  )  Results  t o use a copper t i e .  69 4.14 L e a c h e s A t Low P u l p  Table  4-2  Density  shows  t h e l e a c h i n g c o n d i t i o n s and r e s u l t s  three  low p u l p d e n s i t y l e a c h i n g e x p e r i m e n t s .  were  d u p l i c a t e s done a t 100°C.  before  the  tetrahedrite  shaking  autoclave.  concentrations  were  corresponding  excess  2.27 well  versus  2.73  below  those  concentrate  However, t h e e q u i l i b r i u m e x p e r i m e n t concentrate in  for  t h e low p u l p  leaches  1  runs.  2  only  and  unrealistically  were  low i n view o f  observed  experiment,  The  12  their  in  the  g/1  Sb.  of  wet  g  a g a i n s t 5 g i n 125 ml  antimony  and  antimony  The a n t i m o n y  was done w i t h 50  42  these  completely  different g/1 Sb.  130 ml o f l e a c h s o l u t i o n density  2  was a t t a i n e d .  L e a c h e s 1 and 2 p r o d u c e d s i g n i f i c a n t l y results,  and  In  s h o u l d have d e c o m p o s e d  e q u i l i b r i u m with the solution  dissolution  1  L e a c h 3 was done a t 200°C u n d e r  200 p s i g o f n i t r o g e n i n a s m a l l experiments  Leaches  from  46%,  extractions  of  f i g u r e s which are  apparent  departure  from  equilibrium. All too  high  solution. %  leach  filtered but  the leach product to  justified  on  the  basis  of e n t r a i n e d  T h e s e s o l i d s a p p e a r e d t o have c o n t a i n e d s o l u t i o n w h i l e wet t h o u g h t h e y a n d washed.  contained The  be  s o l i d s c o n t a i n e d q u a n t i t i e s of sodium  t h e most  Cu:Fe  and  The 200°C p r o d u c t  25 -  a l l h a d been was  easiest  the  leached  leach  60  wt.  thoroughly to  filter  sodium. S:Fe  ratios  dropped compared t o t h e c o n c e n t r a t e  of  - slightly  solids  both  f o r the.100°C a n d  70  Table  4-2: D a t a a n d  Results  Low  f  Pulp  Density  "Leaching  Exper intents  Leach  2  1  3  Temp ( C) Time ( h r ) Cone ( g - w e t ) Cone ' ( g - d r y )• Leach v o l (ml) N a S (M)  100 24 5.00 4.63125 0/964  100 24 5.0 0 4.63 125 0.967  200 4 5.0 0 4.63 50 0.972  Product (g-dry) Sb(%) Cu(%) Fe (%) S (%) Na(%) S o l u t i o n Sb(g/1) F i n a l Na S (M)  4.38 6.7 26.7 15.4 30.1 1.09 2.27 1.031  4.40 6.1 26.7 15.6 30.2 1.33 2.73 0.996  (3.84)* 3.9 28.8 17.6 32.2 2.84 9.32 0.975  Sb ( o u t ) / S b ( i n ) Sb ( s o l i d s ) / S b ( i n )  0.95 0.48  1.01 0.44  1.02 0.25  Na ( s o l i d s ) / S b ( s o l ' n ) (mole/mole) Leach Soln equiv t o Na ( m l ) S o l i d s Cu/Fe ( g / g ) S o l i d s S/Fe ( g / g )  0.89  0.91  1.1  1.3  2.5  1.73 1.94  1.71 1.96  1.64 1.83  *weight  Fe b a l a n c e ;  2  2  calculated  from  '  portion  Concentrate  13.1 26.0 14.6 29.1 0.0  1.24  1.78 1.99  of sample  lost.  71  significantly while  the  4.15  f o r t h e 200°C l e a c h .  s u l p h u r may  The  have o x i d i z e d  I n c o n s i s t e n c y Of  copper  may  have_  leached  to sulphate.  S o d i u m I n The  Concentrate  Decomposition  Product  S o d i u m m i c r o a n a l y s e s were a t t e m p t e d , uniformly  dispersed  decomposition  and  product  was areas.  sodium a r e a s changed each polishing  was  such  attempted was  considered  areas  the  by  4-11. found  taking  where t h e  t o be  t h e minimum f o r a v a l i d  difficult  weak and  the background.  to  some  was  r e a d i l y absorbed  sample s u r f a c e i s e s s e n t i a l  of  t h e use  SEM  of  x-ray  sodium  the (The  water.) analyser  analysis x ray _  was  count  Twice the background  is  analysis.  flat.  soft  Sodium  that  detection.  these  x-rays  by h e a v i e r e l e m e n t s ,  to t h e i r  the  repolished.  so f i n e and  polish  not  number of  When a m i c r o p r o b e  twice  were  in  without  than  product  only  s a m p l e was  grit  made  Figure  decomposition  relatively flat  as  were  no a r e a c o u l d be  more  The  time  t h e s o d i u m was  A l s o the apparent  done down t o 5^m  These o b s e r v a t i o n s spectra  observed  but  are so  a  72  The  4 .16  S o d i u m To A n t i m o n y  R a t i o Of  The  Leached  Solids  Wash  Water  To of  investigate  the leached s o l i d s ,  funnel  and  As a c o n t r o l with  the  similar  water  The  increased liberated for  this  filtered proved were  the  Each  relative  leach  to  the  controls.  result. solids  filter  leaching  phase  after  t o d i s p e r s e and  papers. washes  experiments  solid  were  repulped  impossible  to f i l t e r .  Solid  was and  Sodium  each the Solids  up  Sb.  experiments.  must  attempted  cake.  made  wash s o l u t i o n s  breakthroughs  4.5).  Buchner  washed i n a  and  washing  r e p o r t e d a b o v e and  (Section  pulp  f o r Na  the  washing  on a  clearly  have  i n the l e a c h e d m a t e r i a l  Experiments were  displacement  of  the  through the  filtered  assayed  the  t o be d i f f i c u l t  fine  was  of  from a s o l i d  filtered  filtering  .then  shows t h e r e s u l t s  ratio  virtually  and  solution  was  during  ml were s u c k e d  of c e l l u l o s e  filtrate  manner.  of sodium  slurry  washes o f 100  leach  Na:Sb  a leach  a slurry  T a b l e 4-3  two  the d i s p o s i t i o n  in  to  been  account  which  wash.  The  resultant  the. solids  slurries  broke  through  were  observed  i n the  even in  equilibrium  73  Table  Leached  4-3  :  from  F i l t e r  Cake  Washing  Sb(ppm)  Na(ppm)  Na/Sb  14500  293000  20.2  760  16000  21.1  Solids Leach  Cellulose  Results  Solution  Wash  1  Wash  2  2.8  546  195  Wash  3  1. 0  280  280  F i l t e r  Pulp  Leach  (control):  Solution  10400  200000  19.2  1390  25700  18.5  Wash  1  Wash  2  22.5  590  Wash  3  0.8  20  .  26.2 25.0  74  4.17 P y r i t e  A  Leaching  sample  of  coarse  Na S f o r s i x h o u r s green-black  c r u s h e d p y r i t e was l e a c h e d i n 0.03 M  a t 100°C.  The r e s u l t a n t  rinsed  and  t h o r o u g h l y with, water.  immediately  turned  100°C t h e s o l u t i o n a  hot  solution  polysulphide drop  sample  yellow  silicon  thioferrate  black.  had darkened  of f l o c c u l a t e d  sulphur,  was a  c o l o u r s u g g e s t i v e of sodium t h o i f e r r a t e .  s a m p l e o f p y r i t e was t r e a t e d w i t h c o l d and  solution  was  12 h o u r s  significantly. the  observed.  and i r o n .  upon c o o l i n g  A 1 M Na S s o l u t i o n  flocculated  solution  A similar  1% HC1 t o remove  After  was a d d e d  Acetone  added t o  thioferrate  and  analysis  the presence  of  The b u l k o f t h e s o l u t i o n but appeared  oxides,  of l e a c h i n g a t  A SEM x - r a y  indicated  deep  no  on a  sodium,  flocculated  t o r e d i s p e r s e when  heated  to b o i l i n g .  4.18 S i l i c a - I r o n O x i d e  Figure particle The  Particles  4-13 shows a SEM m i c r o g r a p h  peaks  bright  a r e a s on e a c h  grey area while  manganese manganese  silica-iron  oxide  i n t h e c o n c e n t r a t e and i t s S i a n d Fe x - r a y e n e r g y map  indicate  f o r t h e element under c o n s i d e r a t i o n . dark  of a  showed s i l i c o n the  light  in  the  t h e ' s o u r c e s of t h e x - r a y s spectrum,  from a  w i t h much s m a l l e r i r o n a n d  copper  grey  ( b u t no s u l p h u r ) .  area  The x - r a y  showed  T h i s phase  concentrate  manganese i n t h e d e c o m p o s i t i o n  maps.  iron,  i s the  only  and i s presumably product.  copper source  and of  the source of  P a r t i c l e s such as t h e s e  (b) Figure  (c) 4-13  SEM M i c r o g r a p h of a Silica-Iron Oxide P a r t i c l e (a) and the Corresponding Silicon (b) and I r o n (c) X - r a y Energy Maps  76  were n o t  found  in  the l e a c h e d  material.  77  Chapter  5.  D e p e n d e n c y of A n t i m o n y S o l u b i l i t y  on  5.1  Stibnite  Solubility  Although '  Sulphide  Ion  Concentration  Plots  there  is  a n t irnony (111 ) - s u l p h i d e  a  lack  of  complex(es)  agreement is  as  formed  to  which  from  Sb  S 3  2  dissolution  in  experimental  sulphide  r e s u l t s which merit  Sb2S3 d i s s o l u t i o n If  SbS ~ 2  solution, ion  then  versus  solutions,  data  was  further analysis.  produced  l o g of t h e a c t i v i t y  of t h e  log  of  (Equations  activity any  than  activities  coefficient  5-1  has  of  the  SbS ~ 2  of t h e s u l p h i d e i o n ( l o g  a  straight  t o 5-3).  are  data  Sb(111)-sulphide 1/2  be  2  original  s t a b l e S b ( l I I ) complex i n  the a c t i v i t y  slope  0.5  the  No  gives  study.  a plot  log a(S ~) should  rather  in this  t o be  a(SbS ") versus of  literature  i s considered  the  2  the  line  with  However, c o n c e n t r a t i o n s  experimentally  determined  not  been p u b l i s h e d f o r HS~,  S"  = SbS  complex.  Sb S 2  3  + 1/2  K(SbS ") = 2  2  a(SbS a  0 5  " 2  2  ...(5-1)  -)  (S -) 2  a  ...(5-2)  and S~ 2  or  78  l o g a(SbS On  ")  = 1/2  a concentration  log a(S ') + log KfSbS^)  ...(5-3)  2  basis Equation  5-4  i s analogous  to  Equation  5-3. l o g { S b S " } = 1/2  log{S "} + log v 2  9  0 5  (S  - ) + logK(SbS  2  ")  ...(5-4)  Y(SbS ") 2  Since  each  ionic  strength  device  t o add  reagent  the  f a c t o r s ) i t i s a common  a large concentration coefficients  stibnite  ( 1 9 6 6 ) was for  (among o t h e r  activity  The  c o e f f i c i e n t , Y , i s a f u n c t i o n of  activity  species:  the  SbS  same a n t i m o n y  proven  that  both  bonding argument scheme  and  2 _  ,  the  and  r e s u l t s are was  and  s u l p h i d e per  then  Figure  1-3,  results  S /"  r a t i o as  and  2  Sb S 2  et a l .  log plot  format  Sb 2  S ".  the  SbS  2  '.  " 2  No  the  one  has by  a  calculation The  the  m o l e of a n t i m o n y  parallels  the  Arntson  ' seems more l i k e l y  subtracting  the  keep  4 7  A summary of  by  calculating  This c a l c u l a t i o n Section  by  2 5  Sb^S  experimental to  shown i n A p p e n d i x F.  obtained  25°C.  The  4  to sulphide  ions e x i s t  number of m o l e s of  given  2  2  total  constant.  S b „ S . ~ , Sb  ( S e c t i o n 1.3.2).  ion c o n c e n t r a t i o n  considered  data  ions  into a concentration-based 3  has  inert  virtually  solubility  converted  of  the  free  S" 2  appropriate  f o r the  complex  HS"-S "-OH" e q u i l i b r i u m a t 2  one  that  was  used  for  1.3.1  i n d i c a t e t h a t SbS  3  ~  cannot e x i s t  in high  free  3  S"  s o l u t i o n - the  2  electrochemical SbS  3  "  was  total  study  S ":Sb. r a t i o 2  Shestiko  s t a b l e i n the  region  and  fell  Demina  below t h r e e .  In  (1971) s u g g e s t e d  shown i n t h e  lower  right  an that  hand  3  corner  of  Figure  5-1.  The  dashed  line  only  connects  their  0 -0.2 h -0.4  O  Arnstonet.al.(l966)  •  Dubey and Ghosh (1962)  V  Shsstiko and Demina (1971)  cP  _-0.6  Sb4Sf  O  --0.8  cP  sb s|2  - -I O 0  in  t  IXJ  cn  sbs;  /  5-1.2 -1.4 -1.6 -1.8  /  20  2.4  1.6  1.2  0.4  0.8  0  L o g [ F r e e S "] ( M ) 2  F i g u r e 5-1: The L i t e r a t u r e S t i b n i t e L e a c h i n g Data C o n s i d e r i n g S b S " a t Low S u l p h i d e and S b S 2  2  (SbS  3 _ 3  4  S t a b l i l i t y Area Shown)  2  2 7  Plotted  " a t High Sulphide  80  experimentally relationship Sb  S  2  4  "  d e r i v e d p o i n t s and between  SbS^ "  were i n d i c a t e d t o be  not  other  complexes.  s t a b l e to the  mean  left  to  of  s  k  infer s 2  ~  4 5  this  a a n <  ^  region.  7-  This  work  the  i n d i c a t e s that SbS^ " could  s o l u t i o n s s t u d i e d by  metallic  and  the  of  lines  'knees' at  the  Arntson  electrode sulphide  on  level  erratic 2.5.  at high The  dubious  Sb S "(Appendix 0.7.  to  at  2  high  low  sulphide  complex  as  to  for  the  caustic titrations  For  The  both species  the  These  S *' 2 5  became  fall  below to  (1966).  the  Sb^S^ "  complexes  2  a t l o g {Sb}  if  the  predominant  data  f o r Sb  S " 2  4  ?  be  and = for at  Sb(111)-sulphide  f r o m S b ^ S ^ " t o Sb^S  t h e more c o m p l e x  S b ( I I I ) to sulphide  ". 3  Arnson et a l .  i s prl o t t e d w i t h t h e d a t a  change  3  f o r Sb  show d i s c o n t i n u i t i e s  ( F i g u r e 5-1).  appears  transition, A 1:2  s u l prh i d e  SbS  i s also considered  However, t h i s d i s c o n t i n u i t y d i s a p p e a r s  Sb 2S 4 "  Sb(111)-sulphide  2  t h i s complex  both  2  slopes  p l o t showed  S ":Sb r a t i o d i d not  log plots  F)  2  2  S " 4 7  a  various  The  sulphide  dominant  Sb  s o l u t i o n s s t u d i e d by  solubility  total  of  containing  calculation  2  of  rest potential  5-1.  free S "  though the  2  existence  i n the  The  S"  the  * and  2 5 Figure  shown on  r e s u l t s of  4  in  (1966).  d i s s o l v e d antimony.  where t h e S  have been p r e s e n t  solutions  a p o t e n t i a l versus  ulphide  'knee' p o i n t s a r e  in  and  c o m p l e x ( e s ) c h a n g e d f r o m Sb  The  et a l .  Denina(1971) s t u d i e d the  antimony  concentrations of  not  3  Shestiko  in  and  3  does  2  2  ~;  a  logical  i o n forms i n s t r o n g e r s o l u t i o n s .  complex at studies  low  free S "  (Section  idealized  slopes  2  was  suggested  3.4.2). of  the  corresponding  81  log plots  s h o u l d be  one  Sb s  (Equations  + S "  5-9). ...(5-5)  0  = {Sb  S "}  x 2  2  ...(5-6)  3  2  l o g ( { S b S }x2) 2 4  to  = Sb s/'  2  {Sb}  5-5  = log{S '}  + logK(Sb  S ") + l o g 2 + 4 7 ' log (S -)  2  2  2  Y  Y (Sb.S, ")  ... (5-7)  2  4  2  2 Sb  S  + S " = S b S " 3 4 7 2  2 log({Sb S }  x 4) = l o g { S - }  2  4  + l o g K(Sb  2  ?  ...(5-8)  2  log  S ")  + log 4  J  (S -) 2  Y  Y (Sb S ") 4 7  . . .(5-9)  2  The  Sb  S '  r e g i o n has  2  2  a s l o p e of  4  a total  t h e Sb  between these  effects. ionic  s l o p e s and  Even the weakest  s t r e n g t h of  0.12  u n i t y can  solution  molal  0.95  a  concentration  ± 0.15  level)  term  solution. not  (1966)  However, the K(Sb  comparable to the  for Equation 2 Sb S ?  3  5-10 + HS"  result  2  + OH"  Their quoted K ( S b S y  2 7  = Sb  " ) value  value  a b o v e as  assuming the  total  S " 2  of  attributed series  to had  first  range.  2  believed  S ") 4 7  The  S , ") was c a l c u l a t e d t o be 2 4 i n t h e low s u l p h i d e r a n g e and also  2  et a l .  be  in this  K ( S b , S " ) was 0.34 ± 0.01. The K v a l u e s may 4 7 by a c t i v i t y c o e f f i c i e n t c h a n g e s . Arntson  0.97.  7  - a s t r e n g t h h i g h enough t o  b a s i s K(Sb  (95% c o n f i d e n c e  -;  2  4  r e q u i r e c o r r e c t i o n s b e y o n d t h e Debye H u c k e l On  S  "  differences activity  0.81;  t h a t Sb given  their  be  affected  S " existed in 4 7 i n t h e i r paper i s 2  v a l u e was  h y d r o l y s i s of  + H _0 5 translated  calculated  S ". 2  ...(5-10). t o 0.42  t h e r m o d y n a m i c s of A p p e n d i x F a p p l i e d t o E q u a t i o n  5-8.  using  the  82  The  results  F i g u r e 5-1 a f t e r done  of  Dubey  and Ghosh  calculations given  ( 1 9 6 2 ) a r e a l s o shown on  i n A p p e n d i x F.  a t 30°C ( a n d c a l c u l a t e d a s i f a t 25°C), was  t e r m s of t h e S b S "  with  a  K(Sb  The  K ( S b S, ") 2  4  value  2  of  the l i n e  value  2  S ") 2  slope  was  of  120  2.01  based  ± on  be  Their  accepted  constant  hydrolysis  same d a t a  reported  erroneous  sulphide  study,  results  and  coefficients  those  of  and G h o s h  ( 1 9 6 2 ) u s e d two l e v e l s  1.0,  however,  the  seems a n o m a l o u s i n  view  of of  the  currently of  Arntson of  added  et a l . KC1:  d i f f e r e n c e between t h e s e the  difference  1.2.  of t h e s p e c i e s i n  r e s p o n s i b l e f o r t h e poor  Dubey  lack  of 2  a n d was u n d o u b t e d l y  their  i n terms  y i e l d s a FUSb^S^ ") v a l u e  KC1 was a d d e d t o f i x t h e a c t i v i t y  studies.  1.22  ^  The  between  in  r e s u l t s was  0.13. an  to  4 -  hydrolysis constant.  their  from t h e i r  work,  interpreted in  i o n - the s p e c i e s they b e l i e v e d  2  2  solution.  Their  between  match (1966).  0.5  and  two  sets  the  two  83  5.2 T e t r a h e d r i t e  A  Solubility  treatment  stibnite  analogous  to  t h e one u s e d  data i n the preceeding section  tetrahedrite  results  s u l p h i d e complexes the  Plots  generated." i n  are  this  The  higher  at  Na S},  log{free  2  considering  the complexes: ^  ^  AsS '  equilibrium  S "}  results since  to  be  the S ':Sb 2  25°C i s more s o l u b l e  than  for  /  2  '  free  and the  scatter  2  arsenic  2  'in  4.8).  3  5  3  solution The H S  to determine  -  under  made  - S ~  - OH'  2  the  number o f m o l e s  complex  was  free  of  2  2  consideration. G.  p r o d u c e d was n o t v e r y u s e f u l .  by v i r t u e  S "  of S " per  a n d t h e i r r e s u l t s a r e shown i n A p p e n d i x  excluded  S '}  2  2 4  the appropriate  of the l o g p l o t s  were  were  l o g {Sb} v e r s u s  log{residual  2  m o l e o f Sb were d e d u c t e d f o r t h e  Analysis  studies  S b , S _ " , Sb S ' , Sb S " a n d S b S " .  was p r e s e n t ( S e c t i o n  after  calculations  format with  and  2  a t 100°C was c a l c u l a t e d  concentration  solutions  The S b ( I I I ) -  equilibrium  log plot  4  In a l l c a s e s a c o r r e c t i o n  complexes  the  a t 100°C).  into a solubility  log{total  assuming  (Sb S  r e s u l t s of the t e t r a h e d r i t e  converted  work.  p r e s e n t i n s o l u t i o n were n o t e x p e c t e d  much  tetrahedrite  The  was u s e d t o a n a l y s e  same a s t h o s e f o u n d i n t h e s t i b n i t e  ratios  f o r the published  No  of t h e S ":Sb r a t i o s of t h e 2  the  points  on  each  plot  was  comparable. For data  1  (Figure  log{Sb}  =  M  initial  caustic  there  5-2) a n d a d i s c o n t i n u i t y -1.05  or  log{Sb}  is a full  range of  a p p e a r s t o be  =• -1.35  log-log  present  depending  on  at the  0.4 h Line Fitted for I M initiol NoOH, Discontinuity ot Log ISbJ — —  1.05 1.35  Initiol NoOH A V O D  -2.4  -2.0  -1.6  -1.2  -08  -0.4  0 M 05 M I M 2 M  0  Log [Total No S ] ( M ) 2  Figure  5-2  Solubility Plot for Tetrahedrite Experimental Results  0.4  85  interpretation appears  as a gap  assigning the  chosen.  different  that  intersect  up  the  first  the  data  Figure  of  5-3  the  but  discontinuity  a gap  so w i d e  s i d e s cannot c l o s e  f o r m s two  regardless  pair.  case  lines,  complexes to the  case,  making  the  between p a r a l l e l  second  lines  In  intersecting  the  choice Sb  low  S -;  Sb  2  S " 4  Figures corrected results Table  at high  2  7  5-2  for  lines,  but  complexes assumed  2  4  S '. 2  *  and  5-4  AsS^".  r a t h e r than 5-1  In  S ~ 2  at  i t .  of  i s a plot with  that  gives  These  to  the  show l o g { S b } v e r s u s plots  express  are  an  s l o p e s and  log  {total  intended  equilibrium  Na^S}  t o show  the  relationship.  mean Sb/Na S v a l u e s  for  various  2  ' p o r t i o n s of t h e decrease  with  increase.  of  data  5-5  is  a  the  The  the 1 M  -1.0.  points  initial (The  information.) the  c a u s t i c and be  real,  effects.  dominant  concentrat ion.  p l o t of the  unadjusted  antimony c o n c e n t r a t i o n s that  initial  to a c t i v i t y  antimony c o n c e n t r a t i o n s and  s l o p e s above log{Sb}  =  -1.05  t h e mean Sb/Na^S  due  t o the  scatter  A l l the  slopes  measured  unity.  Figure  large  The  T h e s e e f f e c t s may  o r due  approximated  figures.  increasing  values the  two  the  Sb/Na S v e r s u s  log{Sb}.  2  a r s e n i c c o r r e c t i o n s were values data  for different  are  are  c a u s t i c p o i n t s show an  A c h a n g e s u c h as  in  upward  Figure  5-2  complex  gives if a  occured  high so  intermixed.  'jump' a t  t h i s would occur  Sb(111)-sulphide  At  scattered  c a u s t i c s are  low  relatively  shown.  sufficiently  initial  discontinuity  also  At  log{Sb} the  change at  same in this  -0.4  •0.8  -1.2  -1.6 CO I  I  O  -J  -2.0  -2.4  -2.8 -1.6  -1.2 Log  F i g u r e 5-3  -0.8  [ F r e e S "] 2  0.4  -0.4 (M)  Experimental Results P l o t t e d for the S b s l " Ion at Low S u l p h i d e ; Sb S^~ Ion a t High S u l p h i d e a  4  00  -0.4  Log [Total Na S ] ( M ) 2  Figure  5-4  Solubility Plot for Experimental Results  Tetrahedrite (High Sulphide)  oo  88  5 - 1 : Mean Antomony t o S u l p h i d e  Table  Ratios  and  Slopes  from F i g u r e s 5 - 2 and 5 - 4  Initial (M)  *  NaOH  log{Sb}  Mean S b / N a S *  (log  (As C o r r e c t e d ) (mole/mole)  M)  2  Slope  0  >-l.05  0.111  1.19  0.5  >-l. 05  0.115  1.37  1.0  >-l.05  0.120  2.0  >-l . 0 5  0.190  1.0  <-l . 0 5  0.145  0.014  0.89  1.0  >-l. 3  0.134  0.020  1.26  95% c o n f i d e n c e l i m i t s  given  0.019  1.00 0.89  taken  0.25  Initiol NoOH  0.20  0 M v 0.5 M O I M • 2M  A  0.1 5 P CO  o  CVJ  ^  —  0.10 p  -  q  l  §  —  £  y  CO  0.05  —  As Corrected Not As Corrected  °2.8  -2.4  -2.0  -1.6  -1.2  -0.8  -0.4  Log [Sb] ( M ) Figure 5-5  The Antimony t o S u l p h i d e ( A r s e n i c C o r r e c t e d ) V a l u e s v e r s u s Log Antimony 00  90 If  Figures  different the  temperatures) the d i s c o n t i n u i t y  experimentally  Figure the  5-1 and 5-3 a r e c o m p a r e d  5-1.  leached  determined  border  T h i s a c t s a s a weak p i e c e antimony  species.  (though in Figure  they 5-3  of t h e SbS^ ~ 3  are  at  falls  on  region i n  o f e v i d e n c e f o r SbS^ ~ a s 3  91 Chapter  6.  Discussion  6.1  R e v i e w Of  The  The  Results  f o l l o w i n g r e s u l t s are  the  processes  occurring during  i)  Antimony  was  solution. and,  to  The  extracted  on  4.2.1).  ii)  antomony d i s s o l u t i o n  by  against  the  The  net  concentrate the  sodium s u l p h i d e  for 1  M  initial  factor (Section  were  were  d u r a t i o n of to  iv)  both  fall  The  except  net  negative  (Section  experiments the and  caustic smoothed  changes over the Most  However,  sodium s u l p h i d e  sulphide  24  of  the  within  the  l e v e l s were  observed  rise.  caustic  i n these  4.6).  in  4.7).  h o u r e q u i l i b r i u m l e a c h i n g e x p e r i m e n t s were s m a l l . changes  held  concentration  concentrations  sodium s u l p h i d e c o n c e n t r a t i o n  and  sodium  sodium h y d r o x i d e  results  a d d i t i o n of a sodium h y d r o x i d e  iii)  the  d e p e n d e d on  the  understanding  leach.  from  (Section  plotted  significance in  the  quantity leached  a lesser extent,  The  of  with  concentration sulphide  rose  concentrations  in  a l l  experiments  of g r e a t e r  than 1 M  92  w i t h o u t added c a u s t i c  v)  An  increased  (Section  concentration  concentrate decomposition phase.  The  product  tetrahedrite, and  from  and  the  4.7).  of  product  Lron  was  r e l a t i v e to  contained  zinc  manganese, s i l i c o n  other phases present  the  and  and  found  the  tetrahedrite  silver  sodium  in  from  from  i n the 'concentrate  the  solution (Section  4.13) .  vi)  Sodium t h i o f e r r a t e  solids  (Section  extracted  vii)  4.3).  by w a t e r  Pyrite  was  The  dissolved was  concentrate  x - r a y amorphous. t h i s product microprobe  For  was  not  analysis.  j  t o be p r e s e n t  Sodium, presumably  washing  sodium t h i o f e r r a t e  viii)  appeared  (Section  sodium  observed  t o form  decomposition reasons  possible  from  the  leached  thioferrate,  was  4.16).  by  these  in  by  sulphide (Section  product  a positive x-ray  solution  and  4.17).  was  very  fine  and  i d e n t i f i c a t i o n of  diffraction  or  by  93  6.2  Caustic  The confirmed and  F o r m a t i o n And  Sulphide  presence  of  by  observation  direct  2.1.1).  oxide  I f these  corresponding  (and  oxides  sulphides  p o s s i b l y o x i d i z e d phases)  and  would  sulphide  (Equations  and  6-2).  = MO  2  6-1  + 20H-  occur  "  + S"  2  i  experiments.  species;  Fe,  Cu  unstable  in  silicon  forming  In  the  concentration mechanism In  and  i n c r e a s e was provided  caustic  Mn  contact  Cu,  as  + 40H"  Mn  have s t a b l e  a decrease  in  ...(6-2)  and  the  caustic-only i n c r e a s e was  sulphides.  Since  experiments  sulphide  experiments at  caustic  {Na^S} was  is  the p o s s i b i l i t y  no  o b s e r v e d c o n s i s t e n t w i t h the  only  sodium s i l i c a t e  SiS^  of  seems r e m o t e .  leaching  sulphide-only  necessary  equilibrium  S i have c a u s t i c - s o l u b l e  w i t h aqueous s o l u t i o n ,  a mixed s u l p h i d e  d e p l e t i o n at high  in  ...(6-1)  i n t h e m a j o r i t y of  Fe,  observed  the  increase  2  ( S e c t i o n 4.2.2) as no the  to  if  2  T h e s e c h a n g e s were o b s e r v e d leaching  coupled  + 2H 0 = MS  2  (Section4.18  an  " + H 0  2 2  leaching  were more s t a b l e , t h e n  concentration  MO  acid  was  w e r e t o d i s s o l v e i n c a u s t i c and  caustic  MO  Depletion  low  where  ( S e c t i o n 1.3.1).  solids.  due  proposed  present.  ( S e c t i o n 4.7)  -{Na^S}  most l i k e l y i n the  was  NaOH  to the  a caustic hydrolysis The  caustic  r e t e n t i o n of  94  6.3  Sodium  The to  Thioferrate  i n f e r r e d p r e s e n c e of  this  leaching  weak s u l p h i d e product  study.  more  leach  solution  from  'Also d u r i n g  washing  This  b e h a v i o u r can  filter  observed  4.3).  4.14)  The the  and  as  the  s o d i u m and  basis  (Section  r a t e s d r o p p e d and  of was  4.16).  there  were  (Section  4.5).  deflocculation  clogging  in  leach  sodium  water washing  interpreted  thioferrate, be  oxides  dissolution  derived  and  extractable of  a  this  ferric  from  pyrite.  (Section  shown t o be  (Section  was  iron-containing material  the  ubiquitous  the  of  channels  of  cake.  conceivably ferric  of be  (Section  (Section  filtering  mobilizing  Sodium  was  the  colloid  s o d i u m t h a n e x p l i c a b l e on  t h e s e s o l i d s by  breakthroughs  thioferrate the  dispersed  caustic-free solutions  extractable  small  The  contained  entrained  s o d i u m t h i o f e r r a t e was  10%  iron could  .  An  a  sources  of  2.1.1)  p r o d u c e d by  4.17)  two  iron  the  and  compound, i n the  total the  Na S  leach  2  i n t e r n a l redox  concentrate:  iron  was  alkaline  produce t h i o f e r r a t e . on  reaction  could  acid  sulphide  Thioferrate  crushed  pyrite  (Equation  6-3)may  occur. 2FeS This  + N a S + S " = 2NaFeS 2  2  reaction  is  speculative  + S "  ...  2  2  and  has  never  been  (6-3) previously  reported. The  literature  stable with (Sect ion  respect  1.3.3).  indicates  that  to decomposition  t h i o f e r r a t e should at  100°C  (Equation  not  be 6-4)  95 2NaFeS  = 2Na* + 2 F e *  However, sodium solids and  + S "  2  2  + 2S '  2  (presumably  thioferrate  o f t h e 100 a n d 200°C l e a c h i n g  thioferrate Equation  depletion.  was p r o d u c e d 6-3  provides  6.4  react with a s o l i d  + 80H"  2  2  appear  crystalline  leach  (less  mechanism  for  solution  since  ( E q u a t i o n 6-7)  ...(6-5)  f i n e , more t h a n 5 0 % -400 mesh a n d  product,  on  the o t h e r hand, d i d not  line  broadening  The  lack  ( a s no  Particles  of t h i s  of  product  were p r o d u c e d ) i n d i c a t e d a l o w c r y s t a l  t h a n 0.01 u m ) .  or,  present.  a t 21,000x and was e v e n f i n e r .  lines  sulphide  could disproportionate  phase(s)  decomposition product d i f f r a c t i o n diffraction  4.14  Solids  The c o n c e n t r a t e was q u i t e . The  i n the  a t 100°C.  2  Of The  found  of S e c t i o n  = 7 S " + SO " 4  Disintegration  crystalline.  experiments  another  the s p e c i e s i s u n s t a b l e i n a l k a l i n e  4S 2  s o d i u m ) was  from p y r i t e  The p o l y s u l p h i d e f o r m e d  more l i k e l y ,  ...(6-4)  2  9  order  size are c o l l o i d a l .  SEM x - r a y a n a l y s e s w e r e done on a number o f  product  areas  of a m o u n t e d , p o l i s h e d  s a m p l e o f l e a c h e d s o l i d s a t 80,000x u s i n g  a  observation.  reduced  similar at fine  field  of  t o F i g u r e 4-11.  high magnification and  everywhere (Section  well  4.18).  The c o n s i s t e n t suggest  mixed.  though  E a c h a r e a showed a  their  that  Manganese sources  results  spectrum  o v e r many  areas  the decomposition product i s and are  silicon  were  found  not i n the t e t r a h e d r i t e  S o d i u m was n o t f o u n d e v e r y w h e r e ,  but  this  may  96  be  an  error  (Section  Because  of  decomposition  4.13).  the  indicated  product  identification  of  and  not  not  The  possibility  that  c o n t a i n i n g Na S explain  the  experiments  The  the  lack  low  appears  to  a  between  the  two.  clear  the  data  scatter  and  definitive  increased effect  of  product  be  a  or e l e c t r o n reasons  has.a  mixture  product  it  definite  of  binary  There  is a  i n c l u d e s compounds  N a F e S ). 2  This  would  Leach  concentration correlation  as  w o u l d be  at  high  caustic  may  be  to  there  difference  0.5  there  a  the  great  deal  in  of  solution  concentrations. activity  t h i s does not M and  where  t o make.  antimony  the  and  equilibrium  concentration  difficult  increase  between the  was  caustic  t o the a n t i m o n y complex, but  5-2)  between the antimony  sulphide  {Na^S} and  (Figure  e x p e c t e d f o r an  statements are  with both s u l p h i d e  of  relative  The  were c o l l e c t e d ,  general  same  nature,  i n s o l u t i o n i n the c a u s t i c - o n l y  However, at h i g h  most of  In  the  the  4.2.3).  sodium s u l p h i d e be  diffraction  colloidal  sulphide  sulphide concentrations  lack  to  C h a r a c t e r i s t i c s Of  At  may  of  amorphous  For  decomposition  of  (Section  x-ray  size  of more c o m p l e x compounds.  (similar  2  x-ray  decomposition  product  s u l p h i d e s ' or a c o l l e c t i o n  particle  possible.  c e r t a i n whether the  compostion at a l l .  6.5  its  t h e m a t e r i a l by  m i c r o p r o b e a n a l y s i s was is  fine  of  The  sulphide  explain  caustic free  the  results  97 over  the  same More  4.2.1).  contribution be  by  caustic  and  (Section  4.7). of  associated  sulphide  reasonably, to  verified  source  sodium  the  the  dependence  If  Leaching  in  the  caustic with  to  reactions  follow.  carefully  matched,  yet  antimony  than  other.  the  short  heat-up  may  have  i n i t i a l than was  antimony  one-half taken.  the  the  a  result  the  antimony  1 M  i n i t i a l  of  (Section  a  chemical  makes  chemistry, of  range  oxides  dissolution  seems  leached caustic  to  of  which  on  to  both  experiments  sulphides  antimony  may  is  a  also  be  conversion.  appears  be  The  the  caustic  conversion  then  this  been  the  leaching  sulphide  concentration  and  one  sensitive  two  duplicates  product Small  responsible.  complete  after  of  solution  period Figure  rate 30  the  can  of  in  minutes  high when  that 4.14  20%  higher  mixing  in  during  leaching  tests  leach  the  were  or  indicates -  the  Section  the  4-8 be  path  was  differences  i n i t i a t i o n  dissolution  to  that 3 was  f i r s t  the more  sample  98  6.6 S u l p h i d e  If  As The L e a c h i n g  Agent  t e t r a h e d r i t e leached  stibnite  (Equation  established  between  i n a manner a n a l o g o u s  6-6) the  there  mineral,  would  be  sulphide  to  an  and  that  of  equilibrium the  antimony  complex. Cu  Sb S 12  + S ' 2  = Sb S " + 5Cu S + CuS  ...(6-6)  2  4 13  4 7  2  (In a l l the l e a c h i n g r e a c t i o n s w r i t t e n , the antimony complex leach  products  rather  than d e s c r i b e the a c t u a l s p e c i e s .  formed  is  written  serve  only  unknown a n d t h e s o l i d  occurring  conversions equilibrate relative  and  in  thioferrate  reliably  The r e s u l t s d i s c u s s e d  6.4)).  leach  fast  the  long  process  specific  complex  i s not l i k e l y t o the  oxide-to-  Equation  s e c t i o n suggest that  )  would  duration  (Section  which leads t o antimony  other  sulphide  6-11  experimental  leaching rates  i n the previous  the equation  Despite  flask,  production,  given  to the apparently  i s a more c o m p l e x  the  The.  leach product  be a d i s c r e e t c o m p o u n d ( s ) ( S e c t i o n reactions  to i l l u s t r a t e  and  4.10). there  dissolution.  99  6.7  T h i o f e r r a t e As The  The is  L e a c h i n g Agent  major p i e c e s of e v i d e n c e t h a t  suggest that  the l e a c h i n g agent a r e i t s presence  increased relative  to the  one  the  leach  of  two m e c h a n i s m s .  thioferrate  l e a c h c a n be s e e n  In the f i r s t  w o u l d come i n t o c o n t a c t w i t h  the  iron  (FeS  ) ° chain 2  as  would  react  displacing  + 4NaFeS  = 4Na  +  SbS, group  + 2Sb S "  2  2  process i s a s o l i d - c o l l o i d a l  It  would  be  favoured  4  and of  (Equation  reaction  chains.  Iron  seems more r e a s o n b l e t h a n e x t r a c t i o n  Fe S 12  by t h e r m a l and  the t h i o f e r r a t e  + Cu  2  The  SbS  tetrahedrite  an a n t i m o n y , o r a s e c t i o n  w o u l d d i s p l a c e an e n t i r e  4 13  shorten  c h a i n s of n  6-  J  Sb S 12  operating  t h e (FeS ) the  n  Cu  the  tetrahedrite.  ^  7) .  and  i r o n c o n t e n t of the c o n c e n t r a t e d e c o m p o s i t i o n p r o d u c t  A thioferrate-tetrahedrite by  in  thioferrate  4  ...(6-7) 13  w h i c h seems  difficult.  shear f o r c e s which  replacement o f an SbS  for  would  antimony  g r o u p as a l l t h e  s u l p h u r s a r e bound t o n o n - l e a c h i n g e l e m e n t s . By  the  second  mechanism f e r r o u s  iron  t h e t h i o f e r r a t e w o u l d be t h e a c t i v e a g e n t  in equilibrium  ( E q u a t i o n s 6-8  and  with 6-  9). 2NaFeS  = 2Na  +  + 2Fe  2 +  2  Cu  Sb S 12  + S "  + 2S '  2  ...(6-8)  2  2  + 6Fe  2 +  + 8S " 2  = 2Sb S  4 13  2  2  4  - + Cu  Fe S 12  4  13  ...(6-9) The  process  is a solid-solute  r e a c t i o n w h i c h w o u l d be f a v o u r e d  100 by  conditions  given  t o be Both  decompose  temperatures  charge  balance.  ( M e c h a n i s m 1,  tetrahedrite The sulphur  to  (Section  the  this  sulphur  and  indicated  sulphur  is  maintain  2)  t h a t one  product  Leaching  extracted.  to  Mechanism  or  was  the  i n the in  the  Neither  t o the p r o d u c t . polysulphide  for  i r o n and  each  Mechanism 1 has  w h i l e M e c h a n i s m 2 w o u l d add  atom  of t h e s e  2).  leach  4.13).  p o s t u l a t e d adds s u l p h u r of  1  analysis  were a d d e d  One  sulphur could o r i g i n a t e  ( M e c h a n i s m 1, O p t i o n  stoichiometry antimony  leach  The  Option  microprobe  extracted  thioferrate.  a b o v e 80°C ( S e c t i o n 1 . 3 . 3 ) .  mechanisms p r e s e n t e d  solution pyrite  that  1.5  of The  formed  iron  the  two  antimony this  Fe~Sb  atoms  per  mechanisms  most l i k e l y during  one  source  thioferrate  prouduction. The  pure  product  would  sulphur  t o 1:2.  analysis  of  mixing tend  of to  thioferrate raise  into  from the microprobe  ( S e c t i o n 4.13)  results  decomposition  the r a t i o of added i r o n  However, the e r r o r i n h e r e n t the product  the  in general.  in  takes  the  t o added microprobe  significance  away  101  6.8  S o d i u m As  Since  The  the  Leaching  changes  l e a c h were r e l a t i v e l y possible Cu  Sb 12  + 12Na  (Equation  + 8S "  +  =  2  the  product  o n l y one  sodium per  (Section  4.14) .  6.9  The  the  S  from the  hypothesised  S  + 2Sb  S "  as  a  ...(6-10)  2  .12 12 13 2 4 found to c o n t a i n too  was  a n t i m o n y was  seems  the  to  experimental  thioferrate  from  be  the  6-10).  Cu  three a l t e r n a t i v e s  thioferrate  that  concentration during  added v e r s u s  the  little  sodium;  expected  three  Leach E q u i l i b r i u m  Of  iron  questioned  results  i s not  from the  thioferrate  seems  to  solid-solution  the  nature  examine  of the the  though the  first  chains  this  leaching  overwhelming.  more p l a u s i b l e ,  to support  case the  e x p e r i m e n t s done.  which  the  Equilibrium  i s achieved  dissolution.  solid by In  hypothesises  again  antimony  there  l e a c h e q u i l i b r i u m has validity  phase  of  the  i s no  The  totally  three  simplest enters  precipitation  to  be  equilibrium  the a p p r o a c h - t o - e q u i l i b r i u m leach  two  view.  r e a c t i o n morphologies.  i.e.  the  displaces but  agent, evidence  Of  In c o n s i d e r i n g l e a c h i n g t h e r e are  dissolution,  this  t h e most l i k e l y ,  presented,  evidence  I n any  be  p o s s i b l e f o r the  mechanisms  tetrahedrite  compelling  of  sulphide  4 13  However,  of  in  s m a l l , sodium can  l e a c h i n g agent  S  Agent  a  is  types simple  solution. kinetics dissolved  102  component  precipitates  controlled  by  kinetics. initial  the  In  and  the  substrate  ±  The  kinetics  affected the  by  the  selective The  to  dissolution  colloidal  (Section  two  of  residue. (as  4.5))  substrate  of  decomposition The  leaching  cause  it  is  Alternatively r e a g e n t due  may  is  the  its  i t to  and  affects  may  resemble  rapid. leaching  is  a  to  to  non-adherent most  likely  characteristic over  thioferrate  is extracted  a colloid  respect  coating  the  itself  is  a  settling  form  mechanism  With  colloid  by  than grossly  this  occurs leaving  iron  process  and  the leach-  enters  i s the  the  p r o d u c t of  which mixes i n  a  with  product.  not  i s complex  certain  reached e q u i l i b r i u m available  the  r e s i d u e which  r e s i d u e and  With respect  s i t u a t i o n presented  complexity  of  i n t h i s case are  the  course t h i o f e r r a t e  precipitation  is  dissolution  portion  morphologies.  demonstrated  Of  a  the  Leach-precipitation  However,  w h i c h may  as  surface  dissolution  o c c u r s where t h e  leach product.  the  a  equilibrium  m o l a l volume change i s l e s s  the  tetrahedrite.  precipation  as  only  if precipitation  selective  flocculated  tests  of  to  -well  proposed t h i o f e r r a t e - t e t r a h e d r i t e  tetrahedrite  the  i f the  equilibrium.  a c o m b i n a t i o n of  leach-  leaving  characteristics  approach  as  dissolution  dissolves  adhere to 40%.  approach  precipitation,  selective  solid  the  or  thioferrate  t o d i l u t i o n by  whether the  whether the  tetrahedrite may the  and  surface have  view  of  this  experimental  leach  reactions area  become  product.  in  just  stifled  became  blinded.  unavailable  as  a  103  The  term  between  a  'equilibrium'  forward  seems u n l i k e l y t h a t the  final  and  thioferrate  appears  and  the  reaction  is controlled  on  a  t h i s case i t added  that  the  Excess  thioferrate  (by  the  thioferrate The  as  leach the the  not  extent  of  dissolution  in solution  reaction. a  true  support such a  leaching  To  sodium  does  achieves  results  to  tetrahedrite  thioferrate-tetrahedrite  s o l u b i l i z e d i s 1:2. 2  complex  of  balance  be  tetrahedrite.  thioferrate  log{Sb}-log{S •}  antimony  the  In  leached s o l i d s  i s in question  With ratio  2 _  the  possibility  equilibrium  possibility.  the  a  incremental  product.  production  of by  of  a n t i m o n y were t o  the'  in  the  leaching  Though t h e chemical  be  present  control  concept  mixtures that  would  be  the  backward r e a c t i o n .  i f dissolved  assay) i n d i c a t i n g that  Sb(III):S  a  'equilibrium'  to  evokes  agent  the  show a s l o p e of  unity  plot  (Section  w o u l d h a v e t o be  5.2),  SbS^  the  (Equation  3 -  6-11). Cu  Sb 12  As  S 4  + 4NaFeS 12  + 4S ' 2  +  + 4SbS  2  discussed previously  tetrahedrite  = 4Na  data  falls  3  " + Cu  3  (Section close  to  5.2)  the  the  Fe 12  Sb 4  discontinuity  b o r d e r of  SbS  3  13  ...(6-11)  ~  in  the  stability  3  as  d e t e r m i n e d by  3)  though  the  tetrahedrite  field.  the  S h e s t i k o and  Demina  (1971) ( F i g u r e s  temperatures c o n s i d e r e d are data c o l l e c t e d occurs  i n the  5-1  different. SbS  3 _  3  and  5-  Most  of  stability  104  6.10 The P r o g r e s s  Of The L e a c h  E x a m i n a t i o n o f t h e Sb a n d , i n p a r t i c u l a r , time In  curves each  of S e c t i o n  phase  thioferrate  the  The  concentrate  immediately  g i v i n g the f i r s t  The  'catches  surface area  to  ^  versus  A  sulphide  up' r a i s i n g always  and  phase.  the sulphide rises.  of f i n e s which have  (and r e a c t i v i t y ) . Coarser  a  The f i n e s r e a c t material  reacts  the second.  caustic concentrations  been t h e y  2  the s u l p h i d e c o n c e n t r a t i o n and  has a l a r g e f r a c t i o n  high  to give  oxides  The a n t i m o n y c o n c e n t r a t i o n  relatively  slower  of  deplete  then the t e t r a h e d r i t e l e a c h i n g concentration.  N a  4.10 i n d i c a t e s t h e l e a c h h a s two p h a s e s .  conversion  production  the  w o u l d h a v e showed a  were n o t m e a s u r e d .  steady  rise  much  I f they had like  the  Sb  concentrations. The slightly given  negative  the  sulphide were  observation  t h a t most o f t h e n e t s u l p h i d e  i s a result  of t h e  e x c e s s of c o n c e n t r a t e  extent  of  changes were  the  reactions  used.  B e l o w 5 0 % Sb e x t r a c t i o n  consuming r e a c t i o n s dominated.  Above 5 0 % n e t i n c r e a s e s  observed.  105  Chapter  7. .  Conclusions  An  experimental  l e a c h i n g ' of hydroxide  for  the  a n t i m o n y , and  and  From t h e  Analytical  determination,  and  extraction  to i n v e s t i g a t e  chemistry of  the  sulphide-sodium  procedures  -sulphur  the  e l e c t r o n microscopy  solid  results  the  leached  species,  were caustic,  antimony  of  X-  were u s e d t o s t u d y  the  product.  following  l e a c h i n g of a n t i m o n y  i ) The  developed  a r s e n i c i n . t h e s o l u t i o n s under c o n s i d e r a t i o n .  diffraction  concentrate  was  t e t r a h e d r i t e . c o n c e n t r a t e i n sodium  solutions.  adapted  ray  technique  c o n c l u s i o n s can  does  not  proceed  from t e t r a h e d r i t e  be made :  by  the  simple  leaving solid  copper-  sulphides.  i i ), The with  l e a c h s o l u t i o n s r e a c t , not  . other  colloidal, nature  iii) of  of  phases  x-ray  in  It is unlikely  i n the  t h a t the  leaching represent  tetrahedrite, producing  Identification  r e s i d u e was  hindered  the d e c o m p o s i t i o n  by  a  of t h e  but fine, exact  not p o s s i b l e .  s o l u t i o n s produced a f t e r  a true chemical  r e a c t i o n ( s ) a p p e a r s t o be and  concentrate  amorphous r e s i d u e .  the p r o d u c t s  thioferrate  the  only with  24  hours  equilibrium.  The  the c o l l o i d a l  character  present.  leaching of  106  iv)  Sulphur  In  t h e range of p u l p d e n s i t i e s i n v e s t i g a t e d , s u l p h i d e  reactions  v)  i s solubilized  with  kept the net s u l p h i d e  Caustic  lead  along  i s directly  the t e t r a h e d r i t e antimony.  concentration  involved  depleting  changes  i n the chemical  small.  reactions  which  t o antimony d i s s o l u t i o n .  v i ) The t r e a t m e n t o f p y r i t e w i t h  a weak s o d i u m s u l p h i d e  solution  produces sodium t h i o f e r r a t e .  vii) of  In the l e a c h i n g  t h i o f e r r a t e makes a  sulphide  Though obtained  in  leaching  equilibrium and  the  contribution  chemistry.  tetrahedrite  The  of t e t r a h e d r i t e c o n c e n t r a t e  The  leaching many  agent c o u l d  condition  antimony  complex  contained  interlocking  reactions.  The  Sunshine leaching leaching sulphur leaching  formed  The  produced process.  solutions species  at  which  mixtures.  The  results  an  were  unambiguous  decomposition not  reactive  product  identified.  phases  conclusions  The  engaging produced  in are  i s possible. a  l i m i t e d a p p l i c a t i o n t o the  As s t a t e d  were  as t h e  t o meet i t s o b j e c t i v e s .  were  have  the  caustic-  thioferrate  acheive  firm  t h o u g h much s p e c u l a t i o n results  failed not  several  overall  unexpected  and b o t h t h e s o l i d  concentrate  sparse,  and  did  of  production  n o t be made c o n c l u s i v e l y .  s t u d y t h e work  experiments  the  designation  interesting  this  to  the  Sunshine not  in  the  plant  added  sodium s u l p h i d e  to  introduction contain the  the  oxidized  experimental  concentrations  of t h e  107  Sunshine work  leach  s o l u t i o n are  the  extractions  and  experimentally t h e y w e r e not The  observed well  are  s h o u l d be  than those higher.  The  of  the  literature  below log{Sb} =  Above  log{Sb]  predominant comolex.  -0.7  ,  Sb  The  =  -0.7  S "  minor  species  features but  in stibnite-saturated  data  probably  the  7  S 4 "  c o m p l e x e s SbS  solubility  is  2  , Sb 2  are  this  applicable,  stibnite  predominant a n t i m o n y ( 1 1 1 ) - s u l p h i d e complex 25°C.  in  chemical  industrially  4  at  studied  quantified.  analysis  showed t h a t  higher  in saturated 2  - i s the  solution  most  likely  7 SbS  " 3 solutions. 3  and  Sb  S 2  5  108  Chapter  8.  Recommendations f o r F u t u r e  Much f u r t h e r sulphide of  work i s w a r r a n t e d  leaching  Study  i n the study of the a l k a l i n e  of t e t r a h e d r i t e .  The f o l l o w i n g  i s a summary  recommendations.  i) prepare  "pure" t e t r a h e d r i t e  s u l p h i d e and t h i o f e r r a t e  ii)  investigate  the  and  on t h i s  production  s u l p h i d e , b o t h c h e m i c a l l y and  iii)  investigate  antimony  the  extraction  tetrahedrite  effect and  concentrate  investigate  the  effect  of  material  of t h i o f e r r a t e  f r o m p y r i t e by  electrochemically  of the  oxidized other  sulphur  phases  species  present  in  on the  109 A p p e n d i x A: The HS - S ~ - O H 2  The d a t a was t a k e n coefficient  data  _  Equilibrium  from F e r r e i r a  was  available  Calculation  (1975).  f o r HS  No and  a t 100°C  activity S^"  to  make  c o r r e c t i ons.  . ..(A-l)  K,  =  {H + H O H - }  =  10-^2.21  H+ + S ~ .=  . . . (A-2)  2  K  K K 1  zOH  2  {HS- } {HTTTS^-}  2  = 10 10.98  = {OH-}{HS") = 10- 1 . 2 3 {S ~}  = 0.0589  2  + y S ~ + x H 0 = xHS" + ( y - x ) S 2  2  2 -  +  (z+x)OH"  ( z + x ) ( x ) = 0.0589 y-x x =-(z + 0.058 ) +  Fraction as  S~ 2  V(z 2 added  + 0.058 )  Na2S  = y-x  + 0.2355y  N  110  Appendix  B: X - r a y  Table B - l :  Diffractometry  Diffractometry Results*  X-Ray  A s s i g n m e n t **  Measured 2 e(deg)  c*>  RI (%)  11.99  7.38  .5  AT  16.90  5.24  5  24 .08  3.69  25. 95  L i t d. (A)  hkl  Oil  7.3  T  002  5.2  15  T  022  3.69  3.43  5  M/G  110/111  3.44/3. 43  29. 62  3.01  100  222//112  3.00//3 .03  31. 99  2.79  15  AT  123  2.80  33.02  2 . 71  20  M/P  020/200  2.71/2. 71  34 . 26  2.61  15  T  004  2.61  36. 50  2.56  10  36. 95  2 .43  5  003210  2.46/2. 42  38.48  2.34  5  4 0.73  2.21  5  P  43'.10  2.10  5  G  44.25  2 . 05  5  T  44.72  2.03  5  44.70  1.91  5  '• '  AT/T//C  T/P  . 211 ;  .  2.212  220  2.099  015,134  2.04  Table B - l : X-ray D i f f r a c t o m e t r y  RI  Results*  Assignment**  (cont)  Lit. (A)  hkl  d  Measured 2 (deg)  d (A)  4905  1.91  15  C  024  1.8 54  49.49  1.86  25  AT  044  1.855  51. 06  1.79  5  M  211  1.76  54.03  1.70  5  T.  116,234  1.687  56.25  1.63  5  T/P  026/311  •1.65/1  57 .75  1. 60  5  C  132  1. 59  58 . 65  1.57  10  AT  226  1.58  65.05  1.43  5  e  (%)  * s p e c t r u m t a k e n a t 40 KV a n d 20 mA, **Assignment AT C G M P  Legend  Cu Ka  radiation  ASTM F i l e Argent ian Tetrahedrite Chalcopyr i te Galena Marcasite Pyrite Tetrahedrite  11-101 9-423 5- 0592 3-0799 6- 0710 11-107  #  112  Appendix  C:  Concentrate  Calculation  was  based  composition  given  Element  %  100  g  of dry c o n c e n t r a t e  i n the t a b l e below. MW  Moles  (g/mol)  63.55  0.409  Fe  14-. 6  55.85  0.261  Sb  13.1 '  121.75  0.108  32.06  0.908  29.1  As  1. 58  74 . 92  0.021  Zn  1. 67  65.38  0.026  Ag  3. 6  107 .87  0.033  a l l t h e a r s e n i c and a n t i m o n y a r e c o n t a i n e d  t e t r a h e d r i t e . The moles. Assuming  Sb  +  As:S  ratio  i s 4:13  A l s o Sb+As:Ag+Zn+Cu+Fe i s 4:12 that the  and 2 calculated.  with the  Mn was n o t c o n s i d e r e d .  26.0  Assuming  Let:  on  Calculations  Cu  S  CuFeS  Stoichiometry  in  s o S must be  so Cu+Fe i s 0.328  the 0.419  moles.  o n l y o t h e r F e , Cu a n d S c o n t a i n i n g p h a s e s a r e  FeS ' t h e 2  distribution  of  these  x = Cu i n ^ t e t r a h e d r i t e y = Fe i n t e t r a h e d r i t e a = relative  moles  of CuFeS  b = relative  moles  o f FeS  2  2  elements  was  113  Equations:  x + y = 0.328 a = 0.409 - x b = 0.261 - a - y 2a + 2b = (0.908 - 0.419)  Solving:  x = 0.3115 y = 0.0165 a = 0.0975 b = 0.147  Result:  (Cu , Fe 9.7 0.5  Ag  1.0  3.0 CuFeS  Zn  0.8  +4.6  ) ( Sb  Since  As  ) S  13  +  2  was t h e o n l y s u l p h i d e m i n e r a l e l e m e n t n o t d e t e r m i n e d .  i t w o u l d t i e up e x t r a s u l p h u r a s g a l e n a ,  s m a l l e r and t h e Fe:Cu r a t i o example,  0.6  FeS  2  Lead  3.4  if  the  2a + 2b w o u l d  of t h e t e t r a h e d r i t e would r i s e .  concentrate  were  9.4  Fe  0.7  Zn  0.8  Ag  1.0  ) (Sb As ) S 3.4 0.6 13  3.2 CuFeS A lead content  2  For  3% l e a d t h e a n a l y s i s w o u l d  yield: (Cu  be  + 4.1 FeS  2  a s h i g h a s 3% i s u n l i k e l y .  +  0.4  PbS  +  Appendix Table  D  :  D-l :  Experimental Data  f o r Leaching Experiments  lutlon . A  Sb  Oil"  Results Considered  i n the  Study  Analysis ' s°  s 2  (H)  (H)  *s 2  (H)  Aa (g/D  Extraction (I)  cm" (H)  (M)  Inlt l a l ^ Cond It lone U a c h Vol (ml)  Cone (g-vet)  (M)  («)  0.202  (1.03)  0 0168  1  0.0278  0.556  (1.03)  0 .0398  2  0.0593  1.07  (1.03)  0 .0659  5  0.0943  1.08  (1.03)  0 .0834  5  0.124  2.63  1.06  0 .230  11  0.265  5.75  1.11  0 .48  -  0.01  22  0.48  9.58  1.23  0 .77  4  *  ft  0.03  41  0.79  10.2  1.12  0 .93  ft  •  *  0.02  44  0.96  11.9  1.22  0 .780  -  -  -  '0.04  1.13  26  0.793  16.1  1.24  0 .901  0.05  0.01  0.03  1.36  35  0.947  21.2  1.27  1 .18  0.03  0.07  0.07  46  1.26  22.2  1.21  1 .44  0.12  0.02  48  1.46  2B.0  1.30  1 .42  42  1.48  75  28.9  1.04  1 .06  62  1.73  50  (g/1  0.01 0.07  0.01 *  -  ft  0.01  *  A  *  0.06  ft  ft  *  0.06  0.38  2.18  (l  03)  1 )0  25 I  Cone HjO (X) 7. 24  7. 50  (0 99)  50  \  Table D - l :  Data f o r Leaching Experiments  Considered i n the Study (cont)  F i n a l Solution Analysis  /  Sb (g/1)  2S (H)  OUCH)  2°3 " (n)  S  2  S  °3 " (H? 2  S  ° (")  *S  (")  An (8/1.)  s 1  (X)  (H) 0.505  11.5  2.19  0.470  0.04  0.02  0.03  25  18.5  2.12  1.01  0.05  0.04  0.03  40  34.0  2.17  1.46  0.62  0.510  12.2  0.64  0.987  18.6  0.69  1.54  31.2  0.82  1.92  0.02  0.15  0.446  0.03  12.3  0.05  0.979  18 .4  -0.02  1.49  0.02  0.01  28.4  -0.09  1.96  0.06  0.04  5.75  1.90.  0.33  10.45)  0.54  10.96]  0.35  [2.08]  Legend i  49  0.03  1.02  50  1.54  75  12  0.55  0.02  1.08  26  1.06  50  0.03  1.25  40  1.50  50  0.02  2.25  45  1 99  75  0.29  8  0 587  1.13  24  1 08  50  1.48  40  1.52  50  2.13  41  2 .10  75  0.09 A  0.04  1  (-)  2 1  (  )  Indicates value calculated  [  ]  value equivalent to 2nd end point (Section 4.2.2) •  -  value of zero determined  *  result Impossible to Interpret difference between normal [S2- ] determination and 2IS  ] determination after Na^SO^ treatment; potential  measure of Sb (V)  25  (0 50)  0.53  >  *S2-  I.each v o l Cone- Cone.11^0 (g-»et) (X) (H) (•"!) 50 7.50 (1.98) 130 Oil  0.01  0.01 0.04  Initial OndUlnns  Extrnctlon from solids  ,  (-)  0 .52  130  130  25  25  1.03  25  2 .08  25  7.50  7.50  7.42  Table D-2:  •  Data for Leaching Experiments Not Consider  s(H) 2  1.07  0.42  2°3 " (M) 0.04  13.9  1.09  0.85  14.1  1.14  23.3  1.17  Sb (g/D 6.75  Initial Conditions  Flnnl Solution Analysis Oil" (11)  31.3  S  2  (H)  s° (11)  s—  - - ••  (M)  Oil" Leach Vol . Cone (g-wet) (ml) (H)  0.03  0.48  (1.02)  180  50  0.06  -  0.96  (1.01)  . 200  75  0.84  0.10  0.01  0.96  (1..00)  180  75  1.33  0.14  1.45  (1.00)  200  100  1.60  -  0.03  1.95  (1.,00)  200  125  0.11  2.4 5  1.,15  140  75  -  1.78  1..14  120  60  0.09  2.51  1..17  120  75  0.08  2.83  1 .04  120  85  0.02  0.99  (2.00)  200  75  0.02  0.97  2 .00  120  60  0.19  1.35  2 .25  140  60  0 05  1.92  2 .08  120  60  ' -  31.6  1.35  2.32  0.16  37.3  1.42  1.83  46.1  1.20  2.59  49.7  1 .25  2.83  -  17.8  1.17  0.87  0.12  22.9  2.24  0.94  0.10  27.3  2.75  1.30  0.16  38.6  2.22  1.86  -  41.7  2.90  1.87  0.22  0.02  1.88  2 .92  120  75  44.1  2.64  1.94  0.24  0.02  1.98  2 .14  120  75  54.8  5.96  1.57  -  0.09  0.92  3.89  120  60  10.6  1.68  0.43  0.34  0.05  0.32  0.99  40.7  1.59  2.53  0.10  1.94  0.97  36.2  2.79  2.05  2.07  1.98  0.10  0.01  0.06  117  Appendix  All  E: A n t i m o n y  and S u l p h i d e  t h e l e a c h e s were s t a r t e d  wet c o n c e n t r a t e . : 2 M NaOH  Leaches  (calculated,  was 100 C.  Each  sample  Concentrations  versus.Time  w i t h 170 ml o f s o l u t i o n  1 a n d 3 were 1 M i n i t i a l  not measured).  The  a n d 75 g o f  NaOH; 2 and.4  leach  temperature  was 10 m l .  T a b l e E - l : Sb a n d Na S v e r s u s 2  Time R e s u l t s  Leach 1  Leach 2  Time (min)  Sb ( g / 1 ) Na S (M) 2  Sb ( g / 1 )  Na S (M) 2  0 30 . 60 120 240 480 1440  0 3.60 5.20 7.18 10.1 14.7 16.3  0 6.50 9.33 13.6 15.8 19.5 20.9  0.862 0.667 0.698 0.750 0.736 0.776 0.781  Time (min) 0 30 60 120 240 480 1440  Leach 3 Sb ( g / D 0 15. 8 18. 6 20. 3 21. 5 25. 0 28. 2  0.848 0.627 0. 595 0.660 0.663 0.701 0.726 Na S (M) 2 1.56 1.46 1. 52 1.48 1.51 1.54 1.57  Leach 4 Sb ( g / D  Na S (M) 2  0 18. 6 20. 3 22. 3  1.45 1.42 1.53 1.48  27. 3  1.52  -  -  -  118  Analysis  A p p e n d i x F:  The weight Sb  Arntson  et a l .  (1966)  was  molality.  the molarity  Sb were s u b t r a c t e d  considered determine to that constants  and  from  the  in  the  total  of f r e e A  S" .  was  used  K  = {H }{OH~} = +  1  = {HS-}/{H }  2 K K = 0.0838 1 2  +  lCf {S  2 -  1 3  -"  } =  with  7  id " 2  and  p e r mole complex  was c a l c u l a t e d t o  (25°C): K  2  A calculation  2  from  t o be e q u a l t o  f o r the  equilibrium  2  Appendix  of S  number o f m o l e s o f S~  HS"-S~ -OH~  the concentration shown  of t h e s e s o l u t i o n s  The a p p r o p r i a t e  Data  converted  p e r c e n t Na S, Sb S a n d H 0 t o c o n c e n t r a t i o n s 2 2 3 2  by c o n s i d e r i n g  their of  data of  of t h e S t i b n i t e D i s s o l u t i o n  9  2  the  parallel following  Results of Log (Sb) - Log (Free S" ) Calculations ?  Table F - l :  f r o m  D a t a  A r n t s o n  e t  a l .  C o m p l e x  C o n s i d e r e d  2 l o g  sb s  Na,S  2  2  ( m o l / k g  s o l n )  "2°  3  ( m o l / k g  e o l n )  (Z/100)  F r e e  (M)  l o g [ S b ]  (H)  [  S b  4 7 " S  2  S b  S  ~ 1  A  2 4 " S  2  sb s *-  SbS ~  2  5  3  3  0.058  0.0138  0.9908  -1.559  -1.809  -1.907  -2.167  -2.612  0.09A  0.0250  0.9842  -1.294  -1.502  -1.608  -1,905  -2.505  0.155  0.0426  0.9734  -1.058  -1.193  -1.297  -1.594  -2.234  0.241  0.0683  0.9580  -0.046  -0.932  -1.035  -1.332  -2.023  0.0712  0.9563  -0.827  -0.911  -1.014  -1.313  -2.016  0.315  0.1080  0.9307  -0.630  -0.791  -0.920  -1.352  -2.837  0.464  0.1667  0.9072  -0.434  -0.570  -0.720  -1.166  0.496  0.1766  0.9013  -0.407  -0.530  -0.660  -1.107  0.629  0.2325  0.8719  -0.273  -0.393  -0.527  -1.010  -  0.250  .  -  0.672  0.2576  0.8600  -0.223  -0.357  -0.4 97  -1.028  0.728  0.2602  0.8521  -0.201  -0.307  -0.438  -1.909  -  0.830  0.3205  0.8236  -0.098  t-0.232  -0.376  -0.948  -  0.917  0.3694  0.8029  -0.036  -0.171  -0.318  -0.917  -  T a b l e F-2: R e s u l t s  Na  S  0  Constant  Sb S ,  K(Sb S ')  2  . 4 7  2  (mol/kg  of E q u i l i b r i u m  s o l n ) (mol/kg  K(Sb. S  2  3  soln)  free  Calculations  1  S " 2  basis  2  free S  0.058  0.0138  0.444  1 .114  0.094  0.0250  0.404  1.030  0.155  .0.0426  0.341  0.867  0.241  0.0683  0.305  0.773  0.250  0.0712  0.303  0.946  0 . 315  0.1080  0. 356  0 . 957  0.464  0.1667  0. 341  0 . 965  0 .496  0.1776  0.332  0.895  0 . 629  '0.2325  0.330  0.897  0.672  0.2576  0.340  0.940  0 .728  0.2682  0.319  0 .863  0.830  0.3285  0.340  . 0.948  0.917  0.3694  0.341  0.957  Mean K ( S b S ' ) l a s t 2  8 = 0.337±0.008 ( 9 5 % c o n f i d e n c e  4 7  Mean K ( S b S " ) 2  first  5 = 0.95±0.15  ~)  4  level)  121  T a b l e F-3: R e s u l t s from C a l c u l a t i o n s Ghosh (1962)  L i t e r a t u r e Data Sb S 2formed Res N a S (M) (M) 2  l o g Sb (M)  log {free (M)  4  9  Z  on  Data  from  „ ^  2-  0.5 M KC1: 0.00985  0.02563  •-1.706  -2.296  1.949  0.01081  0.02974  -1.665  -2.189  1.672  0.01503  0.03059  -1.522  -2.169  2. 219  0.01793  0.03276  -1.445  -2.121  2.367  0.01965  0.03611  -1.406  -2.053  2.217  0.01009  0.02722  -1.695  -2.253  1.806  0.01264  0.03000  -1.597  -2.183  1.927  0.01413  0.03170  -1.549  -2 .144  1.968  0.01518  0.03279  -1.518  -2.120  2.001  0.01690  0.03640  -1.471  -2.047  1.882  0.02054  0.03808  -1.386  -2.015  2.130  1 M KC1:  All  R e s u l t s Mean K = 2.01±0.13 ( 9 5 % c o n f i d e n c e  0.5 M KC1: Mean K = 2 .08±0.31 1.0 M KC1 Mean K = 1. 9 5 ± 0 . 1 1 *the  c o m p l e x Sb S 2 4  2  was  •  considered  Dubey  level)  and  122  A p p e n d i x G: C a l c u l a t i o n o f L o g A n t i m o n y a n d from E x p e r i m e n t a l  The and  experimental  r e s u l t s were c o n v e r t e d  form.  calculated:  {residual  Sulphide  Sixdifferent  log 2-  free  S  {total  S  2  into  l o g antimony  forms of l o g s u l p h i d e  },  l o g {free  S  2  }  considering  the  complexes  log  -  -  i n Section  G-l). As(M)  HS-S~ -OH _  d e t e r m i n e the, number  and  Sb S ~ , A 7 I n a l l c a s e s a c o r r e c t i o n was made  S , Sb S ~ a n d SbS ~ . 2 4 2 5 _ 3 f o r a r s e n i c a s AsS u s i n g t h e r e l a t i o n s h i p d e t e r m i n e d 2  The  }  data  7  Sb  4.8 ( E q u a t i o n  Data  Results  l o g sulphide  were  Log  = 0.110 Sb(M) + 0.000278  equilibrium free  of . moles  S~ of  S"  a t 100°C ( A p p e n d i x A) was c a l c u l a t e d t o  concentration  2  2  complex under c o n s i d e r a t i o n .  ...(G-l)  after  the  appropriate  p e r mole o f Sb were d e d u c t e d  f o r the  C a l c u l a t i o n s f o r Log  R e s u l t s of  Table G - l :  Antimony v e r s u s  Log  Sulphide Plots 2 -  l o g  O i l "  S b  (M)  (M)  s " 2  l o g  [ S b ]  l o g  (M)  ( H )  [ T o t a l  S  2  ~ ]  A  S b . S , • 4 7  (M)  2  ~  [ F r e e  S b  s " 2  S  ] *  ( H ) 4 S b . S , .  S b S ,  3  "  L j  - 2 . 1 4 6  - 2 . 1 9 6  - 2 . 2 5 4  - 2 . 7 8 0  - 2 . 1 2 3  0 . 0 1 6 8  - 1 . 9 8 8  ( 1 . 0 3 )  - 1 . 9 6 4  0 . 0 0 1 6 6  - 2 . 3 4 0  - 1 . 4 7 8  - 1 . 6 4 2  - 1 . 6 6 1  - 1 . 7 3 4  0 . 0 3 9 8  - 1 . 6 2 2  ( 1 . 0 3 )  - 1 . 5 0 3  0 . 0 0 4 5 7  - 2 . 0 5 6  - 1 . 2 3 4  - 1 . 4 1 3  - 1 . 4 6 1  - 1 . 5 1 8  0 . 0 6 5 9  - 1 . 3 9 0  ( 1 . 0 3 )  - 1 . 2 5 6  0 . 0 0 8 7 9  - 2 . 0 5 2  - 1 . 1 2 0  - 1 . 2 5 0  - 1 . 2 9 3  - 1 . 3 3 1  0 . 0 8 3 4  - 1 . 2 4 3  ( 1 . 0 3 )  - 1 . 1 4 3  0 . 0 0 8 8 7  - 1 . 6 6 6  - 0 . 6 5 8  - 0 . 7 6 3  - 0 . 0 0 4  - 0 . 8 3 3  0 . 2 3  - 0 . 7 7 7  1 . 0 6  - 0 . 6 8 1  0 . 0 2 1 6  - 1 . 3 2 6  - 0 . 3 3 3  - 0 . 3 5 5  - 0 . 4 5 4  - 0 . 4 8 3  - 0 . 5 1 4  1 . 1 1  0 . 4 8  - 0 . 4 4 1  0 . 0 4 7 2  - 1 . 1 0 4  - 0 . 1 2 7  - 0 . 2 3 5  - 0 . 2 7 9  - 0 . 3 1 2  0 . 7 7  - 0 . 2 4 9  1 . 2 3  - 0 . 1 4 6  0 . 0 7 8 7  - 1 . 0 7 7  - 0 . 0 4 3  - 0 . 1 4 1  - 0 . 1 7 9  - 0 . 2 0 6  0 . 9 3  - 0 . 1 5 3  1 . 1 2  - 0 . 0 6 4  0 . 0 8 3 8  0 . 7 8 0  - 1 . 0 1 0  - 0 . 1 2 3  - 0 . 1 4 3  - 0 . 2 7 4  - 0 . 3 1 4  - 0 . 3 5 8  1 . 2 2  - 0 . 2 5 5  0 . 0 9 7 7  0 . 9 0 1  - 0 . 8 7 8  - 0 . 0 6 3  - 0 . 2 1 9  - 0 . 2 4 2  - 0 . 2 9 3  - 0 . 3 5 1  1 . 2 4  - 0 . 0 0 2  0 . 1 3 3  1 . 1 8  - 0 . 7 5 9  0 . 0 5 5  - 0 . 0 9 9  - 0 . 1 2 3  - 0 . 1 7 3  - 0 . 2 3 1  1 . 2 7  0 . 0 3 6  0 . 1 7 4  1 . 4 1  - 0 . 7 3 9  0 . 1 3 5  0 . 1 1 5  - 0 . 0 2 0  - 0 . 0 6 1  - 0 . 1 0 7  1 . 2 1  0 . 0 0 0  0 . 1 8 2  1 . 4 2  - 0 . 6 3 8  0 . 1 3 5  - 0 . 0 3 6  - 0 . 0 6 3  - 0 . 1 2 2  - 0 . 1 9 0  1 . 3 0  0 . 1 1 6  0 . 2 3 0  - 0 . 6 2 5  0 . 2 5 6  0 . 1 2 0  0 . 1 0 1  0 . 0 1 5  1 . 8 6  0 . 0 6 0  1 . 0 4  0 . 2 3 4  0 . 2 3 7  s u l p h l d o  v a l u e s  c o r r e c t e d  f o r  a r s e n i c  ( A s S ^  )  Table G-l: Sb  Results of Calculations f o r Log Antimony versus Log Sulphide Plots (con Oil  s 2  l o g  Sb  ( H )  ( M )  ( H )  l o g  l o g , [ T o t a l  (M)  S  [  F r e e  S  2  ) * ( M )  1 *  4 -  Sb,  (HJ  S  4  b  2  S  Sbs " 3  3  5  2 . 1 9  0 . 1 7 0  - 1 . 0 2 5  - 0 . 3 5 3  - 0 . 3 6 4  - 0  . 5 6 7  - 0 . 6 0 6  - 0 . 6 9 5  - 0 . 8 0 7  0 . 1 5 2  2 . 1 2  1 . 0 1  - 0 . 8 1 8  - 0 . 0 1 3  0 . 0 2 5  - 0  . 1 6 4  - 0 . 1 8 8  - 0 . 2 4 0  - 0 . 3 0 0  0 . 2 7 9  2 . 1 7  1 . 4 6  - 0 . 5 5 4  - 0 . 1 4 4  0 . 1 3 3  - 0  . 0 5 5  - 0 . 0 9 0  - 0 . 1 6 9  - 0 . 2 6 6  0 . 0 1 7 2  0 . 6 2  0 . 5 1 0  - 1 . 3 2 6  - 0 . 3 0 6  - 0 . 3 4 3  - 0  . 4 2 3  - 0 . 4 3 6  - 0 . 4  - 0 . 4  0 . 0 9 9 0  0 . 6 4  0 . 9 9  - 1 . 0 0 1  - 0 . 0 1 7  - 0 . 0 4  9  - 0  . 1 3 9  - 0 . 1 5 3  - 0 . 1 8 2  - 0 . 2 1 4  0 . 1 5 4  0 . 6 9  1 . 5 4  - 0 . 8 1 1  0 . 1 7 6  0 . 1 4  5  - 0  . 0 5 9  0 . 0 4  0 . 0 1 5  - 0 . 0 1 6  0 . 2 5 6  0 . 8 2  1 . 9 2  - 0 . 5 9 1  0 . 2 6 9  0 . 2 4 4  0 . 1 2 2  0 . 1 0 2  0 . 0 5 8  - 0 . 0 1 0  0 . 0 1 5 6  0 . 1 5  0 . 4 4 6  - 1 . 8 0 7  - 0 . 3 5 6  - 0 . 4 5 2  - 0 . . 4 0 1  - 0 . 4 0 5  - 0 . 4  0 . 1 0 1  0 . 0 5  0 . 9 7 9  - 0 . 9 9 5  - 0 . 0 2 1  - 0 . 1 1 7  - 0 . . 2 1 5  - 0 . 2 3 1  - 0 . 2 6 4  - 0 . 3 0 0  0 . 1 5 1  - 0 . 0 2  1 . 4 9  - 0 . 8 2 2  0 . 1 6 2  0 . 0 6 1  - 0 . . 0 3 9  - 0 . 0 5 5  - 0 . 0 8 9  - 0 . 1 2 6  0 . 2 3 3  - 0 . 0 9  1 . 9 6  - 0 . 6 3 2  0 . 2 7 9  0 . 1 5 6  0 . . 0 2 7  0 . 0 0 6  - 0 . 0 4 1  - 0 . 0 9 4  0 . 0 9 ' .  5  * e u l p l i l d c  v a l u e s  c o r r e c t e d  f o r  n r n e n l c  ( A s  S  ~)  5  6 2  94  9 1  - 0 . 5 0 3  125  Table G-2:  Antimony  t o S u l p h i de  Ratios  Sb/S {As C o r r } (mole/mole) 2  ?  Sb (M)  OH  0 .00166  (1.03)  or 0168  0 .0109  0 .153  0 .00457  (1.03)  0. 0398  0 . 0333  0 .138  0 .00879  (1.03)  0. 0659  0 . 0583  0 .151  0 .00887  (1.03)  0. 0834  0 .0759  0 .117  (M)  S  2-  (M)  S (M) {As C o r r }  0 .0216  1.06  0 . 23  0 . 22  0 .098  0 . 0472  1 .11  0 . 48  0 .46  0 .102  0 . 0787  1 . 23  0 . 77  0 .75  0 .105  0 . 0838  1.12  0 . 93  0 .91  0 .093  0 .0977  1 .22  0 . 78  0 .75  0 .130  0 .133  1 . 24  0 . 90  0 .87  0 .154  0 .174  1.27  1 . 18  1 .14  0 .153  0 .182  1 . 21  1. 41  1 . 36  0 .133  0 . 2,3 0  1 . 30  1. 42  1 . 36  0 .169  0 . 237  1.04  1. 86  1 .80  0 .131  Table  G-2: A n t i m o n y  to Sulphide  Ratios  (cont.)  OH (M)  2-  S (M)  2S (M) {As C o r r }  , 2Sb/S {As C o r r } (mole/mole  0.0945  2.19  0.470  0.44  0. 213  0.152  2.12  1.01  0.97  0.157  0.279  2..17  1.46  1.39  0.200  0.0472  0.62  0.510  0.49  0.0.95  0.0998  0.64  0.99  0.96  0.104  0.154  0.69  1.54  1.50  0.103  0.256  0.82  1.92  1.86  0.138  0.0156  0.15  0.446  0.44  0. 035  0.101  0.05  0.979  0.95  0.106  0.151  -0.02  1.49  1.45  0.104  0.233  -0.09  1.96  1.90  0.123  Sb (M)  Log [Free S "] 2  Figure  G-l  (M)  The S t i b n i t e Solubility Data of Arntson et a l . (1966) Plotted C o n s i d e r i n g S b ^ S ^ and Sb4S " 7  128  REFERENCES  A r n t s o n , R.H., F.W. 153 , p. 1673.  Dickson  and  G.  Tunell.  Science  B a i b o r o v , P.P., A.P. E z h k o v and S. I s h a n k h o d z h a e v . Redk. T s v e t n . Met. ( 1 9 7 5 ) . pp. 7 1 - 1 0 9 . B a i b o r o v , P.P.  T s v e t n . Met.  (1975).  (1966) Khim.  pp.25-27.  B a r n e r , H.E. And R.V. S c h e u e r m a n . Handbook of T h e r m o c h e m i c a l D a t a f o r Compound and A q u e o u s S p e c i e s (New Y o r k , 1 9 7 8 ) . John W i l e y & Sons. B a r r , L.N. Idaho,  S u n s h i n e M i n i n g C o . - M e t a l l u r g y Summary 1973) , S u n s h i n e M i n i n g Co.  (Sunshine,  B a s s e t t , J . , R.C. D e n n e y , G.H. J e f f e r y and J . Mendham. Vogel's T e x t b o o k of Q u a n t i t a t i v e I n o r g a n i c A n a l y s i s , ( L o n d o n , 1978 ) ,• Longman . ' B l a s i u s , ^ E . , G. H o r n / A. K n o c h e l , J . Munch and H. Wagner. I n o r g a n i c S u l p h u r C h e m i s t r y , G. Nickless (ed.), ( A m s t e r d a m , 1 9 6 8 ) , E l s e v e i r P u b l i s h i n g Co., pp. 199-239. B u s l a e v , Y.A., E.A. K r a u c h e n k o , I.A. K u z ' m i n , V.B. L a z a r e v , and A.B. Salov. Russian J . Inorg. Chem. (1971) 6 , pp. 1 7 8 2 - 1 7 8 4 . B u t l e r , J.N. Ionic E q u i l i b r i u m : A Mathematical Approach . ( R e a d i n g , M a s s a c h u s e t t s , 1964) , A d d i s o n W e s l e y P u b l i s h i n g Co. D u b e y , K.P., and S. G h o s h . 31 , pp. 2 0 4 - 2 0 7 .  Z. A n o r g .  Allg  Chem.  (1962)  F e r r e i r a , R..C.H. L e a c h i n g and R e d u c t i o n i n H y d r o m e t a l l u r g y , A.R. B u r k i n ( e d . ) , ( L o n d o n , 1 9 7 5 ) , IMM, pp. 6 7 - 8 3 . Homes, W.C.  EMJ  (1944),  145  , pp.  54-58.  L a t i m e r , W.E. The O x i d a t i o n S t a t e s of t h e E l e m e n t s and T h e i r P o t e n t i a l s ~ ~ i n Aqueous S o l u t i o n s (2nd. Ed. ) , ( Englewood C l i f f s , New J e r s e y , 1952) , P r e n t i c e H a l l I n c . M o s s , K.C. And'M.A.R. Smith.. I n o r g a n i c C h e m i s t r y : S e r i e s Two. Vol. 2: M a i n G r o u p E l e m e n t - G r o u p s IV and V , D.B. Sowerby ( e d . ) , ( L o n d o n , 1 9 7 5 ) , B u t t e r w o r t h s pp. 2 2 1 - 2 6 7 . Papp, J . -Scavnicar,  Cell. S.  Chem. T e c h .  ( 1 9 7 1 ) _5  Z. 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