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The activity of zinc oxide in multicomponent slags Davenport, William George 1960

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THE ACTIVITY OP ZINC OXIDE IN MULTICOMPONEHT SLAGS  WILLIAM GEORGE DAVENPORT  A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF APPLIED SCIENCE IN THE DEPARTMENT OF MINING AND METALLURGY  We accept this thesis as conforming to the standard required from candidates f o r the degree of MASTER OF APPLIED SCIENCE  Members of the Department of Mining and Metallurgy  THE UNIVERSITY OF BRITISH COLUMBIA August, I960.  In the  presenting  requirements  of B r i t i s h it  this thesis f o r an  Columbia,  freely available  agree that for  Department  copying  gain  shall  Department  or  his  for reference  and  study.  I  for  extensive be  copying  granted  representatives.  publication allowed  of  w i t h o u t my  of  Mining and Metallurgy Columbia,  of  the  It  this thesis  be  15th, i960.  by  of  University shall  not  August  the  Library  The U n i v e r s i t y o f B r i t i s h V a n c o u v e r 8\ C a n a d a . Date  degree at the  p u r p o s e s may  o r by  that  advanced  fulfilment  I agree that  permission  scholarly  in partial  make  further this  Head o f  thesis my  i s understood for financial  written  permission.  i  ABSTRACT  The investigated.  a c t i v i t y o f z i n c oxide i n multicomponent s l a g s has been A c t i v i t i e s were determined  e x p e r i m e n t a l l y Toy e q u i l i b r a t i n g  i r o n saturated brasses with slags containing i r o n oxide.  Required  activities  i n the Zn-Cu-Pe system were o b t a i n e d from e x p e r i m e n t a l i r o n s a t u r a t i o n d a t a and a v a i l a b l e i n f o r m a t i o n on the Zn-Cu and Cu-Fe systems. Where measurement was not p o s s i b l e , thermodynamic a n a l y s e s o f s l a g systems were c a r r i e d o u t . R i g i d a c t i v i t y p a t t e r n s i n the ZnO-SiOg, ZnO-FeO-SiOg, ZnO-CaOSiOg and ZnO-FeO-CaO-SiOg systems have "been developed analytical  from e x p e r i m e n t a l and  data. Agreement w i t h the a c t i v i t y d a t a o f B e l l , T u r n e r and P e t e r s on  ZnO-FeO-CaO-SiOg and Okunev and B o v y k i n on ZnO-FeO-SiOg type s l a g s i n d i c a t e s t h a t the p r e s e n t measurement teohnique slag  investigations.  p r o v i d e s a good b a s i s f o r i n d u s t r i a l  ii  ACKNOWLEDGEMENT  The author g r a t e f u l l y acknowledges Dr. C. S. Samis and Mrs. A. M. Armstrong f o r t h e i r assistance and encouragement.  It i s a  pleasure to acknowledge Mr. G. W. Toop f o r many p r o f i t a b l e discussions of the work. The author wishes to thank the Consolidated Mining and Smelting Company of Canada Limited f o r kindly carrying' out the analyses of the slags investigated. Thanks are also due to the Defence Research Board and the National Research Council of Canada f o r f i n a n c i a l support of the research.  iii  TABLE OP CONTENTS Page I.  INTRODUCTION  1  Object and Scope of the Present Investigation II.  IV.  2 3  METHOD OP ACTIVITY MEASUREMENT A.  Iron A c t i v i t y  4  B„  Zinc A c t i v i t y  4  1. Methods of Thermodynamic Analysis  4  2. Discussion ... .  7  3.  III.  ....  Possible Errors Arising from the Use of Zinc A c t i v i t i e s i n the Zn-Cu-Fe System  C.  A c t i v i t i e s of Iron Oxide and Zinc Oxide  D.  Rearrangement of the Equilibrium Constant  9 9  ....  EXPERIMENTAL  11 12  A.  Materials  12  B.  Crucibles  12  C.  Furnace  12  D.  Temperature Control  E.  Procedure  16  F.  Assaying  16  .....  INVESTIGATION OP THE Zn0-Pe0-Si0 SYSTEM 2  A.  12  17  Auxiliary Systems  17  1. Fe0-Si0  2  17  2.  Zn0-Si0  2  20  3.  S i l i c a A c t i v i t i e s , Zn0-Fe0-Si0« System . . . .  25  iv TABLE OP CONTENTS  (continued) Page  Bo  Experimental Zinc Oxide Activity Determination, System ZnO-FeO-Si0  25  1. F i r s t Approximation, Zinc Oxide Aotivity Calculation  25  2.  Pinal Determination of Zinc Oxide Activity . .  28  C.  Accuracy of Experimental Zinc Oxide A c t i v i t i e s . .  28  D.  Summary of Thermodynamic Data, ZnO-FeO-Si0 System  31  2  V.  2  2  A.  B.  Auxiliary Systems  35  1.  Zn0-Pe0-Si0 System  35  2.  Fe0-Ca0-Si0 System  35  3.  Zn0-Ca0-Si0 System  36  2  2  2  Experimental Zinc Oxide A c t i v i t y Determination, System Zn0-Fe0-Ca0-Si0  VI.  VII.  35  INVESTIGATION OP THE ZnO-FeO-CaO-Si0 SYSTEM  47  2  52  COMPARISONS WITH OTHER INVESTIGATIONS A.  Richards and Thorne  52  B.  Okunev and Bovykin  52  C.  B e l l , Turner and Peters  54 58  DISCUSSION  VIII. CONCLUSIONS  59  IX.  REFERENCES  60  X.  APPENDICES I. II. III.  62  Calculations on the Zn-Cu-Fe System Calculation of A c t i v i t i e s , System ZnO-Si0 . . . .  64  Determination of Zinc Oxide A c t i v i t i e s , System ZnO-FeO-SiO,,  68  2  TABLE OP CONTENTS  (continued)  IV. Thermodynamic Analysis of the ZnO-FeO-SiOg System? Calculations  70  V. Thermodynamic Analysis of the ZnO-CaO-SiOg System} Calculations  73  VI.  Determination of Zinc Oxide A c t i v i t i e s , System ZnO-CaO-FeO-Si0 . 2  75  vi  LIST OP FIGURES F i g , No.  Page  lo  I s o a c t i v i t y Pattern, Zn-Cu-Pe System, 1300°C  5  2.  Zinc A c t i v i t y along Iron Saturation Line, Zn-Cu-Pe System, 1300°C  6  3.  Comparison of Regular Solution Plots of Zn-Cu and Fe Saturated Zn-Cu Systems, 1300°C  8  4.  Liquidus Curve, Cu-Pe System  10  5.  Iron Crucible  13  6.  Experimental Furnace  14  7.  Experimental Furnace, Construction D e t a i l s  15  8. 9.  A c t i v i t y of Ferrous Oxide i n Binary S i l i c a t e Melts at 1315°C A c t i v i t y of S i 0 , System FeO-Si0 , 1300°C, calculated from Schuhmann and Ensio  18  10.  Phase Diagram, ZnO-Si0 System  21  11.  The A c t i v i t i e s of ZnO and S i 0 , ZnO-SiOg System, 1300°C  12.  Regular Solution Plots of ZnO, FeO and CaO i n Binary S i l i c a t e Systems, l600°C  24  13.  S i l i c a I s o a c t i v i t y Pattern, Zn0-Fe0-Si0 System, 1300°C  26  14.  Experimental A c t i v i t y Coefficient System, 1300°C  15.  2  2  2  2  2  .  .  Ratios, ZnO-FeO-SiOp 7 . .  Experimental Zinc Oxide I s o a c t i v i t y Lines, ZnO-FeO-SiO_ System, 1300°C  19  22  27  .  29  15a.  Iron Oxide A c t i v i t y Pattern, ZnO-FeO-SiOg System, 1300°C .  30  16.  Summary of Zinc Oxide A c t i v i t y Data, ZnO-FeO-SiO,, System, 1600°C  32  d  17.  Summary of Iron Oxide A c t i v i t y Data, ZnO-FeO-SiO- System, 1600°C  33  d  18.  S i l i c a I s o a c t i v i t y Pattern, ZnO-FeO-Si0  19.  A c t i v i t i e s i n the C a 0 - S i 0  20.  Iron Oxide I s o a c t i v i t y Pattern, PeO-CaO-SiO, System, l600°C  2  2  System, l600°C  .  System, 1600°C  34 37 39  vii LIST OP FIGURES  (continued)  F i g . No.  Page CaO I s o a c t i v i t y Pattern, FeO-CaO-Si0  22.  S i l i c a I s o a c t i v i t y Pattern, FeO-CaO-Si0  23.  A c t i v i t i e s of ZnO and SiOg, ZnO-SiOg System, 1600°C . . . .  42  24.  Phase Diagram, ZnO-CaO-Si0  43  25.  Zinc Oxide I s o a c t i v i t y Pattern, ZnO-CaO-Si0  26.  Lime I s o a c t i v i t y Pattern, ZnO-CaO-Si0  27.  S i l i c a I s o a c t i v i t y Pattern, ZnO-CaO~Si0  28.  I s o a c t i v i t y Patterns, Zn0-Fe0-Ca0-Si0 System, l600°C, 40$ S i 0 Cut  48  I s o a c t i v i t y Patterns, Zn0-Fe0-Ca0-Si0 System, l600°C, 34$ S i 0 Cut  49  I s o a c t i v i t y Patterns, Zn0-Fe0-Ca0-Si0 System, l600°C, 21.5$ S i 0 Cut *  50  I s o a c t i v i t y Patterns, ZnO-PeO-CaO-SiO System, l600°C, 13$ S i 0 Cut  51  2  System, l600°C  2  ...  40  21.  System, l600°C . .  2  System  2  System, 1600°C  44  System, l600°C . . .  45  2  System, l600°C . .  2  p  2  30.  ?  2  31.  46  ?  2  29.  41  p  2  32.  Comparison of A c t i v i t y Data, ZnO-FeO-Si0  33.  Comparisons of A c t i v i t y Data, ZnO-FeO-Ca0-Si0  33a.  1200°C  34.  Integration Paths, Zn-Cu-Fe System  35.  Regular Solution Plot of S i 0 1600°C  2  System, 1200°C 9  .  System, 5 6 , 57  d  o  55  63  A c t i v i t y , System Zn0-Si0 , o  f  f . .  66  36.  Integration Paths, Zn0-Fe0-Si0 System  71  37. .  Integration Paths, ZnO-CaO-Si0  74  2  9  System  viii  LIST OP TABLES Table No.  Page  1.  A c t i v i t i e s of ZnO and S i 0 , Zn0-Si0 System, 1300°C . . . .  23  2.  A c t i v i t i e s i n the CaO-Si0 System, l600°C .  38  3.  Comparison of the Data of Richards and Thorne and the Results of the Present Investigation  53  2  2  2  (  THE ACTIVITY OF ZINC OXIDE IN MULTICOMPONENT SLAGS  INTRODUCTION  The  thermodynamic a c t i v i t y o f z i n c oxide i n m e t a l l u r g i c a l s l a g s i s  of i n d u s t r i a l s i g n i f i c a n c e .  Slags containing  s e v e r a l l e a d and copper s m e l t i n g s l a g s "by s e l e c t i v e r e d u c t i o n i s an important  processes.  processes.  z i n c oxide a r e produced i n Z i n c i s r e c o v e r e d from  these  The a c t i v i t y o f z i n c oxide i n s l a g s  f a c t o r i n t h e r a t e o f z i n c e l i m i n a t i o n and t h e t o t a l  zinc  recovery. A r e v i e w o f the l i t e r a t u r e i n d i c a t e s t h a t o f z i n c oxide s l a g systems have "been made. phase diagrams have been e v a l u a t e d .  several  The ZnO-SiOg  investigations  and t h e ZnO-CaO-SiO,/  The entropy o f f u s i o n ^ and f r e e  o f f o r m a t i o n ^ o f Z n S i O ^ have been e s t i m a t e d . 2  energy  Three i n v e s t i g a t i o n s i n t o t h e  5 6 7 a c t i v i t y o f z i n c oxide i n s l a g s have been made ' ' . 5 B e l l , T u r n e r and P e t e r s making use o f two e q u i l i b r i u m  investigated  Z i n c Fuming Furnace  slags,  reactions:  ZnO + CO  g  Zn + C 0  CO + H 0  £  C0  2  2  + H  2  2  . . . .  . . . . (2)  These a u t h o r s c a l c u l a t e d z i n c oxide a c t i v i t i e s from t h e i n s t a n t a n e o u s e l i m i n a t i o n r a t e s and f u e l c o m p o s i t i o n s  i n an o p e r a t i n g  (l)  zinc  z i n c fuming f u r n a c e .  A s i m i l a r i n v e s t i g a t i o n was the s l a g s from copper and l e a d  c a r r i e d out by Okunev and B o v y k i n  on  processes.  As these i n v e s t i g a t i o n s were c a r r i e d out under complex o p e r a t i n g c o n d i t i o n s , t h e assumption  t h a t e q u i l i b r i u m i s reached i n t h e s e  processes  has been q u e s t i o n e d ^ . An e x p e r i m e n t a l i n v e s t i g a t i o n o f z i n c oxide s l a g systems  7  c a r r i e d out by R i c h a r d s and T h o m e .  The  ZnO  + CO  PeO  + CO  Two  +  was  e q u i l i b r i a were i n v o l v e d :  Zn + C 0  2  . . . . (3)  Pe + C 0  2  . . . . (4)  s l a g s i n v e s t i g a t e d c o n t a i n e d l e s s than two mol  p e r cent z i n c  oxide.  Object and Scope o f the P r e s e n t I n v e s t i g a t i o n  The  o b j e c t o f the p r e s e n t i n v e s t i g a t i o n i s t o e v a l u a t e the  activity  of z i n c oxide i n systems which ( i ) a r e b a s i c components o f complex s l a g s , o r ( i i ) represent i n d u s t r i a l s l a g compositions.  A c t i v i t i e s a r e t o be  where e x p e r i m e n t a l measurement i s not p o s s i b l e , due p o i n t temperatures,  calculated  to ( i ) excessive melting  ( i i ) h i g h z i n c vapour p r e s s u r e s , o r ( i i i ) the l a c k o f  equilibrium information. The  s l a g s t o be s t u d i e d i n t h i s i n v e s t i g a t i o n a r e the  ZnO-PeO-SiO_, ZnO-CaO-SiO« and ZnO-Fe0-Ca0-Si0„ systems.  ZnO-Si0 , 2  - 3METHOD OF ACTIVITY MEASUREMEHT  The method proposed was  f o r t h e measurement o f z i n c o x i d e  t h e e q u i l i b r a t i o n o f i r o n oxide c o n t a i n i n g  activities  slags with an i r o n  saturated  Zn-Cu phase. The  e q u i l i b r i u m r e a c t i o n chosen was:  (FeO) + [Zn] -» (ZnO) + [ F e ] slag  metal phase  slag  . . . . (5)  metal phase  i  The  equilibrium  c o n s t a n t f o r t h i s r e a c t i o n has been c a l c u l a t e d from e x i s t i n g  thermodynamic data^'"*"^.  ( ZnO > a  n  We]  A l i q u i d s t a n d a r d s t a t e f o r z i n c oxide was chosen because i t p r o v i d e s a more u s e f u l c r i t e r i o n f o r t h e u n d e r s t a n d i n g o f l i q u i d behaviour.  slag  Because no d a t a on t h e entropy o f f u s i o n o f z i n c oxide was  a v a i l a b l e , a n e s t i m a t e o f 2 . 8 5 entropy u n i t s was made on t h e b a s i s o f a c t i v i t y c a l c u l a t i o n s i n t h e ZnO-SiO^ system.  Whereas t h e e n t r o p y o f  f u s i o n may he i n e r r o r , a l l a c t i v i t y i n f o r m a t i o n o b t a i n e d i n the i n v e s t i gation  i s consistent  equilibrium  with t h i s value.  The a c c u r a c y l i m i t s a s s i g n e d t o t h e  c o n s t a n t a r e those determined  thermochemical  data.  from t h e source o f e x i s t i n g  - 4 The evaluation of zinc oxide by t h i s equilibrium requires that-the a c t i v i t i e s of FeO, Fe and Zn be known.  Experimental conditions were estab-  l i s h e d to provide t h i s information.  A,  Iron A c t i v i t y The a c t i v i t y of i r o n was established at unity by the use of an i r o n  crucible f o r the equilibrium measurements. saturated with  B.  t  At equilibrium the metal phase i s  iron.  Zinc A c t i v i t y Zinc a c t i v i t i e s i n the iron-saturated brass phase were evaluated  from the shape and d i s p o s i t i o n of the experimental i r o n saturation l i n e (Figure l ) i n conjunction with e x i s t i n g a c t i v i t y information on the Zn-Cu^ 12 and Cu-Fe  systems.  Iron saturation data were obtained from the experimental  metal phase compositions. Using t h i s basic information, the system was evaluated thermodynamic a l l y by the a p p l i c a t i o n of Gibbs Duhem integration techniques, and the a c t i v i t i e s of zinc and copper were calculated along the experimental i r o n saturation l i n e (Appendix I ) . The r e s u l t s are shown i n Figures 1 and 2. 1.  Methods of Thermodynamic Analysis Three d i f f e r e n t methods of thermodynamic analysis were employed i n  the c a l c u l a t i o n of zinc a c t i v i t i e s .  These techniques were also used i n l a t e r  examinations of ternary slag systems.  - 6 -  0  4  8  12  16  20  Mol i> Zinc Figure 2.  Zinc A c t i v i t y along Iron Saturation Line, System Zn-Cu-Fe, 1300°C.  - 7 -  l)  Schuhmann's graphical application of the Gibbs Duhem equation^.  2) Schuhmann s ternary intercept Gibbs Duhem i n t e g r a t i o n ^ , i.e. 1  Lna  3)  2  = - / I /d  \  dLna j 1  The "basic Gibbs Duhem integration application along an i s o a c t i v i t y l i n e , i.e. dLnag = - N.. dLna. —(a^ = constant)  The employment of these three analytical techniques provided the means by which experimental iron saturation data and available "binary a c t i v i t y information could he u t i l i z e d i n the evaluation and v e r i f i c a t i o n of zinc a c t i v i t i e s i n the Zn-Cu-Fe system (Appendix i ) .  2.  Discussion The effect of iron saturation on zinc and copper a c t i v i t i e s appears  to be s l i g h t .  Figure 3 shows a comparison of regular solution plots of the  binary (Everett, Jacobs and Kitchener"*^, 1300°C) and iron saturated Zn-Cu systems. Everett, Jacobs and Kitchener showed the "binary system to he completely regular.  The calculation of the iron saturated system shows that  although the zinc a c t i v i t y coefficient i s raised the system exhibits near regular solution behaviour.  - 8-  4  3  Gu-Zn System E v e r e t t , Jacobs and Kitchener,  1300°C  1:L  CM  do  N a  2  Present  Investigation  Iron Saturated I  Zn-Cu System  1300°C  X" P o i n t s C a l c u l a t e d on I s o a c t i v i t y Diagram ( F i g u r e l )  0 0  10  15 Mol  re 3,  20  f,  25  30  Zn  Comparison o f R e g u l a r S o l u t i o n P l o t s o f Zn-Cu and Fe Zn-Cu Systems, 1300°C.  Saturated  - 9 3. Possible Errors Arising from the Use of Zinc A c t i v i t i e s i n the Zn-Cu-Fe System The t o t a l errors introduced by the use of zinc a c t i v i t i e s i n the ternary metal phase were estimated at - 16$. Everett, Jacobs and Kitchener''"''' report their experimental error to be less than - 1$. ±3$.  Assaying errors i n the present investigation are given at  ' Temperature errors have a twofold effect.  Because of the high 15  temperature dependence of the Fe saturation composition i n the Cu-Fe  system  (Figure 4)> the ternary Fe saturation l i n e may vary up to - .8 mol per cent Fe with a - 10°C variation. effect on zinc a c t i v i t y .  Temperature variations also cause a small direct  Within the temperature accuracy given (- 10°C) the  t o t a l temperature effect on zinc a c t i v i t i e s was estimated to be - 2$. Calculation errors were assigned on the basis of detectable v a r i ations i n the i s o a c t i v i t y pattern. Because of the r i g i d i t y of the pattern developed by the three Gibbs Duhem integration methods, and because of the r e l a t i v e l y small amounts of iron present, calculation error l i m i t s were estimated at — 10$. C. A c t i v i t i e s of Iron Oxide and Zinc Oxide  Because the a c t i v i t y values of iron oxide are required i n the measurements of zinc oxide a c t i v i t i e s , these two components must exist i n a common slag phase. A method was developed whereby available information on auxiliary slag systems could be used to evaluate zinc oxide a c t i v i t i e s i n  slags containing i r o n oxide.  P r i o r to the interpretation of experimental  r e s u l t s available information on a u x i l i a r y systems was examined.  D.  Rearrangement of the Equilibrium Constant  The equilibrium constant was rearranged i n order to f a c i l i t a t e the c a l c u l a t i o n of zinc oxide a c t i v i t i e s from experimental and a u x i l i a r y i n f o r mation. of  This was accomplished by expressing the i n i t i a l r e s u l t s i n the form  acV^Q r a t i o , i . e . %FeO ZnO * FeO  Cs3  _ =  h  ™  L*ZnO  - 12  BXPERTMTO1TAL  A.  Materials  Baker and Adamson reagent grade ZnO, CaO, SiOg, FegO-j, Pe, Cu and Zn materials were used throughout the investigation.  B.  Crucibles  The crucibles used were low carbon steel machined from 4" stock (Figure 5).  The carbon content was lowered by heating i n a i r at 1300°C f o r  several hours. Several blank runs were made i n each crucible before experimental use.  C. Furnace  A simple "Glo Bar" furnace was used (Figure 6).  Construction  details are shown i n Figure 7. The source of power was a 4.5 KVA transformer.  D.  Temperature Control  Temperature control was accomplished by means of a Platinum-Rhodium thermocouple attached to a "Wheelco" mercury switch controller. accuracies were given at - 10°C.  Temperature  -  - 13 -  -  Figare 6«  Experimental Furnace  14.-  - 15 -  Thermocouple s to Controller  Chamber  Conductor Straps 20"  Terminals  Fire Clay Brick (3000°F)  •§-" Aluminum Sheathing  16" Depth:  Furnace 16" Chamber 10"  Heat Source:  2 sets of 3 "Glo Bars" i n p a r a l l e l  Figure 7. Experimental Furnace, Construction Details.  - 16 E.  Procedure Slag and metal components were weighed and mixed. Blending was  obtained by passing the mixture through a 35 mesh Tyler screen, followed by remixing. The mixtures were placed i n the iron cruoible, dried, and oharged to the furnace. Experimental charges consisted of Cu, ZnO, CaO, SiOg, F« ^3 2  powders (Fe and Fe 0^were mixed stoichiometrically to form FeO). 2  an(  *  F e  During the  establishment of equilibrium zinc oxide was reduced by the iron oruoible, the resultant zinc entering the metal phase. Several experiments were oarried out with an excess of zinc i n the metal phase i n order to evaluate the effeot of the reverse reduotion mechanism. The results of the two experimental methods were found to be essentially identical. Experimental times were between 40 and 70 minutes.  Duplioates of  each distinct slag type were run at various times, ensuring that equilibrium conditions were attained. Material balances were oaloulated i n order to eliminate experiments with exoessive slag or metal losses. Observed losses were generally i n the order of 0 tb 3$. Metal and slag were quenched i n iron moulds, thus maintaining equilibrium conditions.  Slag-metal separations were also f a c i l i t a t e d by  using this quenohing technique.  F. Assaying  Slag assays were kindly oarried out by the Consolidated Mining and Smelting Company of Canada Limited, T r a i l , B. C. Their assays were reported at - .1$.  - 17 M e t a l assays were c a r r i e d out by Mrs. A. M. Armstrong and author.  Samples were t a k e n by d r i l l i n g c o m p l e t e l y through the metal  Copper was  determined  u s i n g the potassium potassium  buttons.  e l e c t r o l y t i c a l l y , z i n c by p o t e n t i o m e t r i c t i t r a t i o n  f e r r o - f e r r i c y a n i d e c o u p l e , and i r o n by t i t r a t i o n w i t h  dichromate.  The  z i n c - 2$, i r o n - 1$, Cu -  a c c u r a c i e s of the assays were e s t i m a t e d t o be: 1%.  INVESTIGATION OP THE  The most elementary t e c h n i q u e was  the  o  SYSTEM  system which c o u l d be s t u d i e d by the p r e s e n t  the Zn0-Pe0-Si02 system.  g a t i o n o f t h i s system was  Zn0-Fe0-Si0  c a r r i e d out.  F o r t h i s r e a s o n an e x t e n s i v e  investi-  Component PeO-SiOg and ZnO-SiOg  systems were examined t o p r o v i d e the r e q u i r e d a u x i l i a r y i n f o r m a t i o n .  A.  A u x i l i a r y Systems  l)  PeO-Si0  2  18  lo* 17 The PeO-SiOg system has been s t u d i e d e x t e n s i v e l y  '  '  .  The  i n v e s t i g a t i o n s which g i v e the most c o n s i s t e n t r e s u l t s a r e those o f Bodsworth and Davidson  , and Schuhmann and E n s i o  , who  measured the a c t i v i t y o f  PeO  by r e l a t i o n s i n v o l v i n g oxygen s o l u b i l i t y i n i r o n under Fe0-Si02 s l a g s . The most r e c e n t i n f o r m a t i o n on t h i s system i s p r e s e n t e d i n F i g u r e s 8 and 9, based  on l i q u i d s t a n d a r d s t a t e s f o r both FeO and SiOg.  i n v e s t i g a t i o n s g i v e v a l u e s i n c l o s e agreement w i t h t h i s  data.  A l l recent  - 19 -  - 20  2)  Zn0-Si0  System  2  Because the p r e s e n t e x p e r i m e n t a l technique c o u l d not he used measure a c t i v i t i e s i n the Z n 0 - S i 0  2  to  system, a c t i v i t i e s o f z i n c oxide were  c a l c u l a t e d from phase diagram and entropy of f u s i o n d a t a . The (Figure  10).  phase diagram i n the ZnO-SiOg system has been The  entropy of f u s i o n of s i l i c a ^  investigated*  and the entropy o f f u s i o n  o f Z n S i O ^ have been e s t i m a t e d . 2  Si0  AH  2  f  = 3600 -  1456  K c a l  /  m o l  (1713°C)  (cristobalite) Zn SiO^ 2  AS  f  = 10.5  E.U.  (no a c c u r a c y l i m i t s g i v e n )  U s i n g t h i s d a t a the a c t i v i t i e s of S i 0 means o f the l i q u i d u s curve method o f Chipman  20  2  and ZnO  were c a l c u l a t e d  and the congruent  by  melting  21 p o i n t method o f H a u f f e and Wagner  (Appendix  II).  The  r e s u l t s of the  v i t y c a l c u l a t i o n s f o r t h i s system a r e shown i n F i g u r e 11 and T a b l e ( L i q u i d s t a n d a r d s t a t e f o r b o t h ZnO  and  R e g u l a r s o l u t i o n p l o t s o f FeO systems a r e shown i n F i g u r e 11.  acti-  1.  Si0 ). 2  and ZnO  i n t h e i r respective  silicate  These p l o t s p r o v i d e the b e s t means o f i n t e r -  p o l a t i n g d a t a and a l s o demonstrate the s i m i l a r i t i e s i n b e h a v i o u r p a t t e r n s i n t h e s e systems. 22 A regular  s o l u t i o n p l o t of CaO-Si0  2  a c t i v i t y data  23 '  t o show the r e l a t i v e p o s i t i o n of z i n c oxide a c t i v i t i e s i n b i n a r y systems.  i s included silicate  -  - 21 -  - 22 -  Figure 11.  The A c t i v i t i e s of ZnO and S i 0 , Zn0-Si0 System,.1300°C. 2  2  T a b l e 1.  A c t i v i t i e s o f ZnO and  N  sio  0  ZnO  1  ol  087  .2  .70  .3  .47 .26  .4 .5 .6 .7 .8 •9 ]  a  2  S i 0 , ZnO-SiO, System, 1300°C. 9  - sio a  0 .008 .029 .11 .295 .70 .946 .946 .946 .946  .13 .08 .073 .073 .073 0  1  N  2  ZnO  1 •9 .8 .7 .6 .5 .4 .3 .2 .1 0  - 24 -  - 25 3)  S i l i c a A c t i v i t i e s , ZnO-FeO-Si0  The  silica  isoactivity  2  System  p a t t e r n i n the ZnO-FeO-Si0  2  o b t a i n e d from the above ZnO-SiCv, and FeO-SiO^ i n f o r m a t i o n . l i n e s were o b t a i n e d by two  joining  points of i d e n t i c a l  Iso-silicate  silica activity  phase diagram i n f o r m a t i o n on the Z n 0 - F e 0 - S i 0  a b l e t o e s t a b l i s h the c u r v a t u r e consistent with F i g u r e 275  of the s i l i c a i s o a c t i v i t y  observed i s o a c t i v i t y  FeO-CaO-Si0 , F i g u r e 22) 2  Experimental  Z i n c Oxide A c t i v i t y  p a t t e r n s of s i m i l a r were a s s i g n e d  s i l i c a concentration levels. v a r i e d a t each  the  system was lines.  values.  ZnO//„  n  Z i n c oxide and  iron  avail-  Curvatures  13).  System ZnO-FeO-Si0  out a t  oxide compositions  5  three were  level.  The  ZnO  on  systems (ZnO-CaO-SiO,  (Figure  Determination,  o  Experiments on the ZnO-FeO-SiO^ system were c a r r i e d  a ^  was  binaries. No  B.  system  c a l c u l a t e d from measured  experimental The  ratios  results  are shown i n F i g u r e 14 and Appendix I I I .  were found t o v a r y l i n e a r l y w i t h ZnO  c o n c e n t r a t i o n a t each  Two  a c t i v i t i e s from  The  approximation steps  were employed.  l)  F i r s t A p p r o x i m a t i o n , Z i n c Oxide A c t i v i t y  The  calculation  Calculation  o f z i n c oxide a c t i v i t y was  i n i t i a t e d by  first  42# S i 0  O 2256 S i 0  2  + 39* S i 0  2  O 4256 S i 0  2  J  I  I  I  I  L  I  L  2  3  4  5  6  7  Mol $> ZnO  2  1  Figure 14. Experimental A c t i v i t y Coefficient Ratios, ZnO-FeO-Si0 System, 1300°C. 2  ro  - 28 making the assumption that iron oxide a c t i v i t y i s constant at constant s i l i c a concentration over the experimental range.  Iron oxide a c t i v i t y values were  evaluated from the binary FeO-SiOg system (Figure 8) and were projected along the s i l i c a concentration lines.  The FeO a c t i v i t y coefficients were then  evaluated f o r the experimental ZnO concentrations. These a c t i v i t y coefficients were applied to the experimentally determined coefficient r a t i o s , giving approximate ZnO a c t i v i t y values. Points of identical a c t i v i t y were then joined, creating tentative ZnO i s o a c t i v i t y lines.  2) ' Final Determination of a„ZnO n  From the tentative ZnO i s o a c t i v i t y model precise values of a^Q were evaluated. Using available s i l i c a i s o a c t i v i t y lines (Figure 13), more accurate tfp Q values were obtained by thermodynamic analysis of the system. e  three methods employed are outlined on page 7.)  (The  Zinc oxide a c t i v i t i e s were  then recalculated on the basis of the re-evaluated o'- « data. FeO T  The technique of successive approximations produced mutually consistent a c t i v i t y values for FeO and ZnO and created a thermodynamically r i g i d i s o a c t i v i t y pattern over the experimental range.  The results are shown i n  Figures 15 and 15a and Appendix I I I . C. Accuracy of Experimental Zinc Oxide A c t i v i t i e s  The accuracy of the experimental zinc oxide a c t i v i t i e s was e s t i mated to be - 43$. The possible errors involved i n the use of the equilibrium constant (- 15$) and z i n c a c t i v i t i e s i n the Zn-Cu-Fe system (- 16$) have been discussed (Schuhmann and Ensio ^ report their a_, values are accurate to within - 2$). 1  n  Figure 1 5 .  Experimental Z i n c Oxide I s o a c t i v i t y L i n e s , ZnO-FeO-SiO_  System, 1 3 0 0 ° C .  - 31 -  The errors i n the approximation techniques were estimated to he i 10$. This estimate was made on the basis of a c t i v i t y variations detectable in: the application of the Gibbs Duhem equation to the experimental values.  D. Summary of Thermodynamic Data, ZnO-FeO-Si02 System  A comprehensive thermodynamic treatment of the ZnO-FeO-SiOg system was obtained from the experimental results. Extensions of the experimental data were obtained by a thermodynamic analysis of the system (Appendix IV). The auxiliary FeO-SiOg and Zn0-Si02 systems were also consulted. Because considerable slag information i s reported at l600°C, the experimental data was extrapolated to this temperature using the regular solu24 tion model. Eey  has pointed out that this model i s applicable over large  ranges of s i l i c a t e systems. One assumption was made during the calculations.  The ^ZnO/^p Q e  ratio data at 41$ Si02 was extrapolated l i n e a r l y to 15$ ZnO. made possible the extension of the SL^aO  =  # 1  i s o a c  "  t i v i  ' y t  l i n e  This assumption t o  ZnO-SiOg  binary, thus f a c i l i t a t i n g the analysis of the system. The results of the calculations are shown i n Figures 16, 17 and 18.  - 35 INVESTIGATION OP THE ZnO-FeO-CaO-Si0  Because the ZnO-FeO-CaO-Si0 compositions was made. silica,  2  2  SYSTEM  system c l o s e l y approximates t h e  o f i n d u s t r i a l s l a g s , a n e x t e n s i v e i n v e s t i g a t i o n o f t h i s system  Z i n c oxide a c t i v i t i e s were measured over e x t e n s i v e ranges o f  l i m e , and i r o n oxide Examinations  compositions.  o f t h e component t e r n a r y systems were made t o p r o v i d e  the a u x i l i a r y i n f o r m a t i o n r e q u i r e d f o r t h e d e t e r m i n a t i o n o f z i n c oxide vities.  The t e r n a r y systems examined were t h e ZnO-FeO-Si0 , FeO-CaO-Si0 2  and ZnO-CaO-Si0  A.  Auxiliary  l)  acti-  9  systems.  Systems  ZnO-FeO-Si0  The  2  2  System  a c t i v i t i e s i n t h e ZnO~FeO-Si0  2  system were e v a l u a t e d and  summarized e a r l i e r i n t h e i n v e s t i g a t i o n ( F i g u r e s 16, 17 and 18).  2)  Fe0-Ca0-Si0  2  System  The FeO-CaO-Si0  25  and Chipman  2  system has been s t u d i e d e x t e n s i v e l y by W i n k l e r  , T a y l o r and Chipman  2T  26"  , Turkdogan a n d Pearson  , and o t h e r s .  28 Elliot  has made a comprehensive review o f t h e s e s t u d i e s and, by a p p l i c a -  t i o n o f the Gibbs Duhem e q u a t i o n , has determined e n t s i n t h e system.  a c t i v i t i e s o f a l l compon-  The s l a g s i n v e s t i g a t e d c o n t a i n e d s m a l l amounts o f MgO,  but a c c o r d i n g t o E l l i o t , t h e s i m i l a r b e h a v i o u r  o f CaO and MgO a l l o w s t h e  r e s u l t s t o be i n t e r p r e t e d a s a c t i v i t i e s i n t h e simple system.  Fe0-Ca0-Si0  2  ternary  More recent information on the CaO-SiO^ system  (Figure 19 and  '  Table 2) was applied to the FeO-CaO-SiCv, system and E l l i o t ' s results were 29  re-evaluated i n co-operation with G. W. Toop  . The re-evaluated a c t i v i t y  pattern i s shown i n Figures 2 0 , 21 and 22. 3)  ZnO-CaO-Si0 System 2  At the outset of the investigation, i t was hoped that the a c t i v i t y of ZnO i n the ZnO-CaO-Si0  2  system could be measured by a slag metal e q u i l i -  brium technique. Tv/o main d i f f i c u l t i e s were encountered.  F i r s t l y , slag melting  points were prohibitive over the low ZnO range of compositions. Secondly, no satisfactory equilibrium reactions could be established.  For these reasons,  the system was analyzed thermodynamically by the methods outlined on page 7 . The data used i n the calculation of a c t i v i t i e s were: i)  Zinc oxide and s i l i c a a c t i v i t i e s i n the ZnO-Si0  2  system  (Figure 2 3 ) . 22 23  ii)  Lime and s i l i c a a c t i v i t i e s i n the CaO-Si0  2  system  '  (Figure 1 9 ) . iii)  Lime, s i l i c a and zinc oxide saturation lines i n the ZnO-CaO-Si0 system  (Figure 2 4 ) .  The ZnO-CaO-Si0  2  system was analyzed thermodynamically on the basis  of this data and a r i g i d i s o a c t i v i t y pattern was developed (Figures 25, 26 and 27).  2  Table  2.  A c t i v i t i e s i n t h e CaO-SiCL System, l600°C.  N  Si0  -CaO a  2  .07 .18 .26 .33 .39 .45 .48 .49 .52 .54 .58 .62 .67  a  sio  N 2  .92  .000015  .69 .48 .28  .000105 .00038  .14 .04 .013 .0068 .0031 .0021 .0012 .0005 .00005  .0013 .005 .03 .10 .20  CaO  .93 .82 .74 .67 .61 .55 .52  .90  .51 .48 .46 .42 .38  .95  .33  .40 .60 .80  - 42 -  - 43 -  Si0  Weight #  F i g u r e 24.  Phase Diagram,  2  ZnO  Zn0-Ca0-Si0  2  System Showing  of S a t u r a t i o n L i n e s a t 1500°C.  Shapes  30' Silica  40  ZnO  Saturation  60  .023  50 Mol $ CaO  Mol $ SiO„  60 / /  70  /  /  '/'//  /  /  Lime Saturation  //////  Extrapolations of C a l c u l a t e d Data  'HI ///// CaO  "A"  10  TV  20  F i g u r e 25.  "TV 30  A 50  To  TV  70  Mol fo ZnO  Z i n c Oxide I s o a c t i v i t y  P a t t e r n , System ZnO-CaO-SiO,,, l600°C.  TV  90  70 30  S i l i c a Saturation - Si0 a  40'  = 2  '  9 5  .9 .8 .7 .6 .5 .4 .3  .2  Mol $ CaO  .1  .05  70.  80  90j  CaO  Mol # ZnO Figure  21.  0-CaC~SiO„ System, 1600 C. S i l i c a Isoactivity Pattern Zn  - 47 B.'  Experimental  Z i n c Oxide A c t i v i t y D e t e r m i n a t i o n , System ZnO-FeO-CaO-SiO,  E x p e r i m e n t a l measurements on the ZnO-FeO-CaO-Si0 carried  out a t f i v e  s i l i c a concentration levels,  c e n t r a t i o n s b e i n g v a r i e d a t each l e v e l .  The  system were  2  the CaO,FeO, and ZnO  experimental o'znO/^  con-  ratios  Fe0  at  each s i l i c a l e v e l a r e t a b u l a t e d i n Appendix V I . Z i n c a c t i v i t i e s were i n t e r p r e t e d by e f f e c t i v e l y quaternary  system a t each e x p e r i m e n t a l  represented a  'pseudo-ternary'  silica level.  'slicing*  Each ' s l i c e '  the then  cut.  On each cut the i n t e r c e p t s o f the FeO and ZnO  isoactivity  lines  were known from e v a l u a t i o n s o f the ZnO-CaO-Si0 , Z n 0 - F e 0 - S i 0 , and FeO-CaO-Si0 2  2  2  systems. It  was  found t h a t on both the ZnO-FeO-Si0  the i r o n oxide i s o a c t i v i t y T h i s meant t h a t on the of almost  l i n e s were  'pseudo-ternary'  constant a c t i v i t y  coefficient  ratios.  o o u  I t was  systems  2  p a r a l l e l t o the s i l i c a  c u t s FeO a c t i v i t i e s appeared  of FeO  simplified  slices.  as  planes  ^^  ^  e  &2,n0'  the d e t e r m i n a t i o n of  a c t i v i t i e s c o u l d be a s s i g n e d w i t h good a c c u r a c y over the  r e g i o n on each c u t , and  que  and FeO-CaO-Si0  over the e x p e r i m e n t a l r e g i o n s .  T h i s a c t i v i t y behaviour FeO  nearly  2  experimental  e v a l u a t e d from the e x p e r i m e n t a l  activity  e s t i m a t e d t h a t the use o f t h i s c a l c u l a t i o n  techni-  i n the d e t e r m i n a t i o n of z i n c oxide a c t i v i t i e s i n t r o d u c e d p o s s i b l e e r r o r s  of - 10$.  These l i m i t s were based  and Z n 0 - F e 0 - S i 0  2  on a p Q a c c u r a c y l i m i t s e  i n the FeO-CaO-Si0  systems and p o s s i b l e a p Q v a r i a t i o n s on the e  2  'pseudo-ternary'  cuts. Z i n c oxide a c t i v i t i e s were c a l c u l a t e d each e x p e r i m e n t a l p o i n t , and c e p t s on the ZnO-FeO-Si0 F i g u r e s 28,  29,  30 and  2  31.  isoactivity  (Appendix V I ) a n d  plotted at  l i n e s were drawn i n c l u d i n g the  and ZnO-CaO-Si0  2  systems.  The  results  inter-  a r e shown i n  CaO  Mol $ ZnO Figure 28. Isoactivity Patterns, ZnO-FeO-CaO-Si0 System, l600°C. 2  40$ S i 0 Cut 2  CaO  Mol $ ZnO Figure 29.  I s o a c t i v i t y Patterns, ZnO-FeO-CaO-SiO System, 1600°C. ?  34$ S i 0 Cut 2  CaO  Mol $ ZnO Figure 30.  Isoactivity Patterns, ZnO-FeO-CaO-Si0 System, l600°C. 2  21.5$ S i 0 Cut 2  Figure 31. Isoactivity Patterns, 2toO-FeO-CaO-Si0 System, l600°C. 2  13$ Si0 Cut 2  - 52 Because of the number of components i n the system, no extension or check of the data was possible.  The data i s presented, therfore, without  thermodynamic v e r i f i c a t i o n .  COMPARISONS WITH OTHER INVESTIGATIONS  The r e s u l t s of the present investigation were compared with the data  7 S *5 of Richards and Thorne , Okunev and Bovykin , and B e l l , Turner and Peters . Comparisons of data were made by interpolating a c t i v i t i e s on the basis of Figures 15, 28, 29 and 30.  Temperature adjustments were accomplished  20 by means of the regular solution model  . Because the a c t i v i t y data of previous  investigations i s reported with reference to a s o l i d standard state, a l i q u i d standard state adjustment  corresponding to a zinc oxide entropy of fusion of  2.85 entropy units was applied.  7 A.  Richards and Thome  The data of Richards and Thorne are presented i n Table 3.  Their  reported zinc oxide a c t i v i t i e s are generally lower than the r e s u l t s of the present investigation but are within the suggested accuracy l i m i t s .  B.  Okunev and Bovykin  Two slag types were studied by Okunev and Bovykin:  ( i ) slags  e s s e n t i a l l y represented by the Zn0-Fe0-Si02 system, and ( i i ) multicomponent slags.  - 53 -  Table 3.  Comparison of the Data of Richards and Thorne and the Results of the Present Investigation  Slag Assays (Mol $) ZnO  sio  1.4 1.5  1.5 1.3 1.3 1.3 1.6  Richards and Thome a_ * ZnO  1  Present  CaO  FeO  33  —  66  .0135  .010  27 40  33.5 21.5 18  38  .021  .030  37  .0165 .016  18  54  .015 .024 .021  10.5 26.5 •  53  2  24 27 34 39  57  33  .0145 .0115 .0185  aZnO  +  a  .0145  .018  * Liquid Standard State 1" Obtained from S i l i c a Cuts ZnO-FeO-CaO-SiO,, System and adjusted t o 1200°C.  The r e s u l t s  of the present  i n v e s t i g a t i o n w e r e f o u n d t o he  reasonable agreement w i t h t h e i r a c t i v i t y (Figure  system  32). Activity  present  d a t a o n t h e ZnO-FeO-SiCv,  in  results  d a t a on t h e m u l t i c o m p o n e n t  s l a g s were compared w i t h  o n t h e ZnO-FeO-CaO-SiCv, s y s t e m b y a s s u m i n g t h a t s  (i)  a n d CaO, a n d ( i i )  SiO^ and A l ^ O ^ behave s i m i l a r l y  basis the present  r e s u l t s w e r e f o u n d t o be h i g h e r t h a n t h e a c t i v i t y  r e p o r t e d b y Okunev a n d B o v y k i n ( F i g u r e  i n basic slags.  the MgO  On t h i s data  33).  5 C.  B e l l , T u r n e r and P e t e r s  The d a t a o f B e l l , T u r n e r a n d P e t e r s a n d t h e r e s u l t s  of the  present  i n v e s t i g a t i o n were f o u n d t o be i n good agreement o v e r t h e e x p e r i m e n t a l ( F i g u r e 33a). slags i s  T h i s agreement  indicates that  the behaviour of t h e i r  c l o s e l y approximated by the s y n t h e t i c  slags of t h i s  range  industrial  investigation.  ,20  Average Compositions: Si0  2  or (Si0  2  + Al^) -  32 Mol #  1 Mol $ (assumed negligible)  CaO or (CaO + MgO) .15  ZnO + PeO  Remainder  4» •H > •rl -P O  <! O  .10  »05  Present Investigation Obtained from Isoactivity Lines 1300°C. Okunev and Bovykin  10  15  Mol $. ZnO Figure 32.  Comparison of Activity Data, Basis:  Zn0-Pe0-Si0  Liquid Standard State.  2  System, 1200°C.  VJ1  .20 Average  31  Mol $  CaO o r (CaO + MgO)  21  Mol i  Remainder  ZnO + PeO  Si0  .15  -  .10  _  Compositions:  2  or (Si0  2  +A l ^ )  -H> •H >• •rl •P O <J O  Present Investigation Obtained from I s o a c t i v i t y Patterns, = .215 ' Si0 and .34 Cuts 2  .05  -  ( F i g u r e s 2$ and 30)  15 Mol % ZnO F i g u r e 33.  Comparison Basis:  o f A c t i v i t y Data, ZnO-PeO-CaO-Si0  L i q u i d Standard  State.  2  System, 1200°C.  ON  .20 Average Si0  .15  2  Compositions or ( S i 0  2  + A l ^ )  »  38 Mol $  CaO  13 Mol $  Remainder  ZnO • FeO  4>  +» O  <-  o 3  .10 Present I n v e s t i g a t i o n Obtained from I s o a c t i v i t y P a t t e r n s ^Q^Q • »34 and . 4 0 Cuts ( F i g u r e s 28 and 29)  .05  B e l l , T u r n e r and P e t e r s "  i  10 Mol # ZnO F i g u r e 33a.  Comparison Basis:  o f A c t i v i t y Data, ZnO-FeO-CaO-SiOg System, 1200°C.  L i q u i d Standard S t a t e .  15  —i I  . 58 DISCUSSION  Certain activities.  i n h e r e n t problems e x i s t i n the measurement of z i n c  Because o f h i g h vapour p r e s s u r e s o f z i n c , d i r e c t oxygen s o l u -  b i l i t y measurement such as those employed i n i r o n oxide and l e a d d e t e r m i n a t i o n s a r e not p o s s i b l e .  A l l investigations  have had t o r e l y , t h e r e f o r e , on two phase e q u i l i b r i u m d e t e r m i n a t i o n o f z i n c oxide The disadvantage.  oxide  oxide  ( i n c l u d i n g the  present)  measurements f o r the  activities.  t e c h n i q u e used  i n the p r e s e n t i n v e s t i g a t i o n has one major  Because the FeO-Fe e q u i l i b r i u m  was  used t o e s t a b l i s h  the  oxygen p r e s s u r e o f the system, the a c t i v i t y o f i r o n oxide i n the s l a g had t o be e v a l u a t e d .  I n the i n v e s t i g a t i o n o f the ZnO-FeO-SiOg and ZnO-FeO-CaO-  Si02 systems a p p r o x i m a t i o n  t e c h n i q u e s had t o be developed  t o make the  e x p e r i m e n t a l d e t e r m i n a t i o n o f z i n c oxide a c t i v i t y p o s s i b l e .  Since  zinc  oxide c o n c e n t r a t i o n s were r e l a t i v e l y low, i n f o r m a t i o n on the component systems c o u l d be s u c c e s s f u l l y used i n the e v a l u a t i o n of ZnO The  scope o f the p r e s e n t i n v e s t i g a t i o n was  compositions which are l i q u i d a t 1300°C.  activities.  l i m i t e d to brass  Above a z i n c a c t i v i t y of .07  vapour p r e s s u r e exceeds one atmosphere and b o i l i n g o c c u r s .  Measurements  were l i m i t e d t o z i n c oxide c o m p o s i t i o n s c o r r e s p o n d i n g t o z i n c l e s s than t h i s v a l u e .  the  activities  - 59 -  CONCLUSIONS  A slag-metal equilibrium technique has been developed f o r the measurement of zinc oxide a c t i v i t i e s i n slags.  By t h i s method ZnO slags  containing FeO were equilibrated with i r o n saturated brasses.  Zinc oxide  a c t i v i t i e s were thus determined i n the ZnO-FeO-SiOg and ZnO-FeO-CaO-Si02 systems, u t i l i z i n g a c t i v i t i e s of zinc i n the Zn-Cu-Fe system and available information on i r o n oxide slags. Thermodynamic analyses of the ZnO-SiOg and ZnO-CaO-SiOg systems have been c a r r i e d out using available thermochemical  information.  Combi-  nations of the experimental and calculated data have produced r i g i d i s o a c t i v i t y patterns f o r the systems studied. The experimental and a n a l y t i c a l r e s u l t s are best summarized by reference to Figures 11, 15, 16, 25, and 28 to 31, i n which i s o a c t i v i t y patterns f o r the systems investigated are shown. The agreement of these r e s u l t s on synthetic slag systems with the i n d u s t r i a l data of B e l l , Turner and Peters on ZnO-FeO-CaO-Si02 type slags, and Okunev and Bovykin on ZnO-FeO-Si02 type slags, i s reasonable and shows that the present technique of a c t i v i t y measurement provides a good basis f o r the i n v e s t i g a t i o n of zinc oxide a c t i v i t y behaviour i n i n d u s t r i a l slags.  _ 60 -  REFERENCES  1.  E. N. Bunting, J . Am. Ceram. Soc.} 13,  2.  E. R. Segnit, J . Am. Ceram. Soc.} 3J_,  3.  F. D. Richardson, "The Physical Chemistry of Melts", Inst. Min.  [1]  8 (1930).  [6] 274  - ._.  (1954). Met.,  London (1953) p. 87. 4.  J . A. Kitchener and S. Ignatowitz, Trans. Faraday Soc.} 4J,, 1278  5.  R. C. B e l l , G. H. Turner and E. Peters, J . Metalsj 6,  6.  A. I. Okunev and V. S. Bovykin, Proc. of the Academy of Sciences of the  7.  U.S.S.R., Chemistry Section, 112, 77 (1957). A. W. Richards and D. J . Thorne, "The A c t i v i t i e s of Zinc Oxide and Ferrous Oxide i n Liquid S i l i c a t e Slags", unpublished.  8.  H. H. Kellogg, Eng. and Mining J.} 158.  9.  G. L. Humphrey, E, G. King and K. K. Kelley, U.S. Bureau of Mines Report of Investigations No. 487O (1952).  [3]  472  (l95l).  (1955).  90 (1957).  10.  C. G. Maier, G. S. Parks and C. T. Anderson, J . Am. (l926)o  Chem. Soc.} 4j3, 2564  11.  L. H. Everett, P. W. M. Jacobs and J . A. Kitchener, Acta Met.; J5_, 28l  12.  J . D. Morris and G. R. Z e l l a r s , J . Metalsj 8_, 1086  13.  R. Schuhmann, J r . , Acta Met.} 3_, 220 (1955).  14.  R. Schuhmann, J r . , Acta Met.} 3,, 223 (1955).  15.  B. N. D a n i l o f f , "Metals Handbook", American Society f o r Metals (1948).  16.  C. Bodsworth and I. M. Davidson, "The A c t i v i t y of Ferrous Oxide i n the  (1957).  (1956).  Fe0-Si0 System", to be published. 2  17.  R. Schuhmann, J r . , and P. J . Ensio, J . Metals} 3,, 401  18.  N. A. Gocken and J . Chipman, Trans. A.I.M.E.} 194.  19.  P. B. Richardson, "Physical Chemistry of Melts", Inst. Min. Met., London,  (1953) 20.  p. 93.  J . Chipman, Discussion Faraday S o c ; _4_, 23 (1948). 1  171  (l95l). (1952).  - 61 -  21.  Hauffe and Wagner, Z. Elektrochem.} 4 6 , 160 ( 1 9 4 0 ) .  22.  F. D. Richardson, "The Physical Chemistry of Melts", Inst. Min. Met., London (1953)  p. 8 3 .  23.  F. C. Langenherg and J . Chipman, Trans. A.I.M.E.; 215. 958 ( 1 9 5 9 ) .  24.  M. Rey, "The Physical Chemistry of Melts", Inst. Min. Met., London (1953)  P. 6 3 .  25.  T. B. Winkler and J . Chipman, Trans. A.I.M.E.} 167. I l l ( 1 9 4 6 ) .  26.  C. R. Taylor and J . Chipman, Trans. A.I.M.E,} 154, 228 ( 1 9 4 3 ) .  27.  E. T. Turkdogan and J . Pearson, J . B r i t i s h Iron and Steel Inst.} 173, 217  (1953)O  28.  J . F. E l l i o t , J . Metals; 6, 485 ( 1 9 5 5 ) .  29.  G. W. Toop, private communication.  APPENDIX I  Calculations on the Zn-Cu-Fe System  A. Simple Gibbs Duhem Integration Cu Cu IT ^ C u Zn a  Statement:  Lna„ ^ = Lna„ *  H  cu Path: Iron Saturation Line Point (Fig. 34) 1 2 3 4 5  • "Zn °Zn (calculated) 1300°C  1 1  NZn  Cu  Cu  .922 .894 .830 .766 .700  .883 .853 .809 .769 .732  l  I  .008 .045 .100 .149 .196  .001 .0065 .0175 .030 .046  2.01 3.00 3.54 3.91  .001 .0065 .0170 .030 .047  From Graphical Integrations B. Schuhmann's Intercept Integration14 Zn \ dLna  Statement: Lna, Cu  (a  Z n >  Zn  N )/^u p e  Fe  Path: Cu = 19 N. Fe N  Point (Fig. 34) A B C D E  l  Zn  .0009 .0065 .017 .030 .047  NZn N,Cu .009 .053 .125 .193 .264  From Graphical Integrations  II  .061 .152 .236 .338  Cu  "Cu  (calculated  1300°C  .97 .92 .84 .77 .69  .97 .92 .85 .775 .70  d  APPENDIX I I  C a l c u l a t i o n o f A c t i v i t i e s , System ZnO-SiGVj  Ao  Liq.uid.us Curve Method Statement:  20  Lna Q 1  A  *Si0  S  f  V  2  f  S  2  (sio ) 2  R  j  T  ( S i 0 ) - 1.8 E.U.  Liquidus  9  ( T - Tm \A Si0  « -  g i  1temperature  2  ( K)  L n a  sio  a 2  sio  a  p  T  66  1968 1853 1753 1705  0  .60 o55 .525  SiO * * 1613°C  °992 .918 .852 .807  .993 .946 .902 .877  =.00713 -.0559 -.1037 -.1310  R e g u l a r S o l u t i o n Temperature Adjustment  B.  21  Congruent M e l t i n g P o i n t Method'  AH  Symbols:  = Heat o f F u s i o n o f ZngSiO^ = 18.7 Kcal/mol  f  Q  = Melting Point of Z n S i 0 2  4  = 1784°K  = Compositions o f ZnO and S i 0  ^ZnO' S i O . x  (x  ZnO  °  =  6 6 6  ' « SiO„ n r  =  *  2  i n Zn SiO^  3 3 3 )  ^' ^ZnO* ^ S i O ~ ^ i q u i d u s Temperature, Compositions  Statement Lna  SiO  II r  =  r L n a  Sio"  A +  H  f @  N  ZnO ( 'Si0 N  e  ~  T  )  - Si0  \±o  (0 - T ) ZnO  +  X  2  2  2  SiO„  2  -  65  Appendix I I (continued)  N  Si0  T°K  2  N 1N  x S i 0 - *SiC 2  f3i0 2  S  i  0  # 2  aSi  %  a  sio  ? 2  2  1 9 8 6  .525  1705  .877  .807  .525  1705  +  198  +  458  .877  .807  .50  1729  +  168  +  406  .676  .650  o45  1757  +  132  +  306  .45  .450  .40  1775  +  89.6  +  201  .305  .314  .35  1784  +  38.2  + 60.3  .183  .195  .333  1785  0  .140  .154  o300  1784  83  .108  .120  0  r-  21.2  -  LnU Extrapolations from  SiCv, Plot (Figure 3 5) < ZnO^ N  o2  .044  ol  .016  Regular Solution Temperature Adjustment  C. Calculation of a„ from a . n  Statement  q  n  Data, Gibbs Duhem Binary Integration ( 1 9 8 6 K)  Ln !  LnSf  ZnO  =  * S i O , - f ZnO P J N  (*W L n S f  ®ZnO  1  .6 .4  0  2  ^n7  ZnO  First Term  =1  *SiO  . I ZnO  ?  d N  < ZnO> N  L n  ZnO  a  Z  n  0  1 9 8 6  2.43  0  0  -  2o37  +.379  -.487  -.108  .72  -  Q.67  +.161  -.832  -.671  .31  -.648  -.636  -1.284  oil  -1.122  .98 .98  -  08  Si0  N  L n  +  2.70  .3  +  3.90  -.819  -.303  o2  +  5.36  -.858  +.150  -.708  .1  +  9.5  -.855  +.850  -.005  1  .98  0  -  - 67 Appendix I I (continued)  D.  Tabulation of A c t i v i t i e s at 1573°K and l873°K obtained by Regular Solution Conversion  N  ZnO  1  H  S i  0  2  .9 .8 .7 .6  .1 .2 .3 .4  .4 .3 .2 .1  .6 .7 .8 .9  .5  0  o  a aZn0  1573  1  .5  1  .87 .70 .47 .26  Si0  0  9  ZnO  a l 8 7 3  sio  0  1  .008 .029 .11 .295 .70 .946 .946 .946 .946  1  0 .875 .72  .50  0  .295 .165 .10 .09 .10 .10  1 P  *1873  1573  .13  .08 .073 .073 .073  a  .012 .04 .117  .31  1  .66 .95 .96 .96 .96  APPENDIX I I I  Determination of Zinc Oxide A c t i v i t i e s , System ZnO-PeO-SiO, A. A c t i v i t y Coefficient Ratios Slag Assays  PointN  ZnO  N  FeO  a  K  N Ei  S±0  N  Metal Assays  FeO ZnO  2  a  Na  Zn  N  N  "Fe  ^Cu  Zn  J^  ii FeO  (1300°C  1 2 3 4 5  .025 .040 .046 .067 .071  .558 .536 .544 .512 .506  .417 .423 .409 .420 .422  22.32 13.40 11.83 7.54 7.13  .051 .077 .086 .111 .119  .100 .097 .095 .094 .090  .849 .826 .819 .795 .791  .0075 .012 .014 .020 .022  .872 .840 .861 .783 .820  6 7 8 9  .044 .050 .066 .082  .566 .559 .539 .521  .390 .391 .395 .397  12.86 11.18 8.16 6.35  .084 .090 .112 .130  .095 .098 .102 .090  .821 .812 .786 .780  .0135 .015 .020 .025  .904 .875 .861 .830  10 11  .043 .050  .623 .615  .334 .335  14.48 12.30  .076 .084  .102 .103  .822 .813  .012 .0135  .908 .867  12 13 14 15 16 17  .021 .027 .039 .049 .054 .065  .751 ,.747 .741 • 730 .721 .709  .227 .224 .218 .219 .223 .224  35.76 27.67 19.00 14.89 13.35 10.91  .044 .052 .073 .087 .091 .105  .105 .100 .104 .092 .097 .102  .851 .848 .823 .821 .812 .793  .006 .0075 .011 .014 .015 .0185  1.122 1.080 1.091 1.091 1.044 1.054  - 69 Appendix I I I  (continued)  B. Calculation of Zinc Oxide A c t i v i t i e s  Point (see Part A)  SZnO * 1300°C Fe0  *FeO (Thermodynamic Analysis)  tfFeO  KZnO  a  ZnO  1 2 3 4 5  .872 .840 .861 .783 .820  .41 .40 .41 .39 .39  .735 .745 .755 .76 .77  .64 .63 .65 .60 .63  .016 .025 .029 .040 .045  6 7 8 9  .904 .875 .861 .830  .435 .43 .42 .41  .77 .77 .78 .785  .695 .675 .67 .655  .030 .034 .0445 .054  10 11  .908 .867  .57 .575  .915 .935  .83 .81  .036 .0405  12 13 14 15 16 17  1.122 1.080 1.091 1.091 1.044 1.054  .81 .815 .81 .805 .795 .79  1.21 1.18 1.19 1.20 1.15 1.17  .0255 .032 .047 .059 .062 .076  1.08 I.09 1.09 1.10 1.10 l.ll  APPENDIX IV  Thermodynamic Analysis of the ZnO-PeO-Si0 System} Calculations 2  A.  Schuhmann"s ^ ternary intercept integrations of a ^ and a^Q were 1  performed along paths as shown i n Figure 36.  B.  Sample calculation, ternary intercept integration of ZnO a c t i v i t i e s dLna, SiO,.  Statement: Lna„ ZnO=• n  Path:  Point (Figure 36,,  a S i 0  2  N,  ZnO  ZnO/.  N,  N.  ZnO N FeO  L n a  Si0  *Si0  Zn0  a  2  2  Zn0  N  1 2 3  4 5  6  7  .83 .73 .60 .38  .25  .16 .10  FeO  -  0.185 0.315 0.51 0.97 1.39 1.83 2.30  1.25 1.08 0.96 0.75 0.61 0.52 0.41  0 0.150 0.348 0.738 1.023 1.269 1.473  0.10 0.115 0.140 0.21 0.28 0.35 0.435  Expected * ZnO a  0.10 0.11 0.135 0.20 0.27 0.335 0.435  * Expected from graphical integrations13,  C. Simple Gibbs Duhem integrations were performed along paths as shown i n Figure 36.  Appendix IV (continued)  D.  Sample Calculation, Simple Gibbs Duhem Integration along a S i l i c a Isoactivity Line.  Statement:  P a t h s  Point (Figure 3 6 ) A B C D E  N  N  ZnO FeO  a  Lna™ « - \ ZnO , J *FeO n  sio2  a  a  T  **> ^ S i 0 a  3  constant)  «3  ZnO  Lna  ZnO  1  ^eO  Expected * ^eO  3 9  .16  -  1.83  0  0.55  .55  0.86  .23  -  1.47  0.23  0.425  .42  1.62  .2?  -  1.32  0.19  0.36  .37  3o50  .29  -  1.24  0.20  0.29  .30  5o60  .30  »  1.21  0.16  0.24  .245  0  o  Expected from ternary intercept  and graphical  integrations.  73  APPENDIX V  Thermodynamic Analysis of the ZnO-CaO-SiOg System; Calculations  A. Schuhmann"s ternary i n t e r c e p t ^ and simple Gibbs Duhem integrations were performed along paths as shown i n Figure 37•  B. For examples of integration procedures see Appendix IV.  Simple Gibbs Duhem Integrations Intercept Integrations  30  70  40  50 Mol % CaO  Mol $ Si0  o  60'  70_  ZnO  CaO  ZnO  ZnO  80>  90.  CaO  10  7 V  20  7 V  40  7V~  T V  70  50 Mol $ ZnO Figure 37. Integration Paths, Zn0-Ca0-Si0 System. 2  ~7V 90  ZnO  75  -  APPENDIX VI  Determination of Zinc Oxide A c t i v i t i e s , System ZnO-CaQ-FeO-SiO, A. A c t i v i t y Coefficient Ratios Slag Assays  Point N  1 2  3  ZnO  N  CaO  N  FeO  N  N  N  S i 0  FeO ZnO  2  Metal Assays a  I .  3  N  Zn  N-,  Fe  203  .380  .383  11.52  .071  .098  .011  0663  .204  .372  .386  10.33  .076  .012  .647  .068  ol42  .394  .104  .394  5.79  .125  .091  5.39  o0235  .125  .089  4.40  .148  .076  .030  .150  .078  .031  .712  .033  .036  O  4 5  .071  .144  .093  .079  6  .0955  .077  7  .023  8  .062  9  .063  10  .064  11 12  .383  .411  .400 .417  4.40  1  (i oo°C Zn * FeO  •  .0235  .710  ,663 .702  .422  .406  .272  .381  .322  16.57  .076  .098  .012  .976  .210  .392  6.32  .130  .091  .025  .825  .178  .334  .401  .358  6.38  .117  .079  .0215  .715  „206  .396  .331  6.18  .145  .085  .029  »934  .073  .168  .411  .348  .144  .082  .0285  .843  ol46  .437  5-63  .077  .338  .145  .090  .029  .856  .087  .148  .425  .338  5.67 4.88  .150  .086  .778  .090  0O89  .137  .077  .027  .772  15  .104  .089  .489 .473  .0305  .153  .082  .031  .736  16  .031  .240  17  .0155  .052  .246  18  .063  19  13 14  .333 .334  5.47 4.55  .206  16.38  .480  .093  .083  .222  9.21  .148  .079  .030  1.441  .260  .220  7.23  .161  .076  .069  .457  1.263  .164  .566  .0335  .200  8.24  .080  20  .077  .201  .511  .210  6.69  .127 .149  .076  .030  21  .078  .073  .206  8.27  .127  ,100  .024  1.034  22  .080  .151  .645 .565  .204  7.02  .146  .076  .029  I.O65  23  .081  .078  .636  .205  7.84  .123  .095  .023  .940  24  .0835  .138  .552  .228  .146  .074  .029  1.018  25  .0845  .131  6.73  .568  .218  6.71  .152  .082  .031  1.086  26  .037  .243  .594  .125  .017  1.436  .051  .766  .120  .103  .0225  28  14.68  .123  .052  .131  .099  27  1.723  .052  .089  .735  .124  14.22  .120  .102  .0225  1.670  29  .059  .061  .753  .126  12.68  .120  .107  .0225  I.488  .070  .074  .723  .134  10.30  .125  .093  .023  1.237  .072  .129  .673  .126  .082  .295  .176  .132  8.49  1.434  .073  .620  .148 .146  .079  .029  1.284  .074  .188  .603  .136  .152  .031  1.310  .572  .130  7.64  .079  .075  .224  8.09  .161  .073  .0335  1.336  30 31 32 33 34  .517  16.19  9-39  0O24  1.326  1.034 1.049  J  -16Appendix VI (continued)  B. Calculation of Zinc Oxide A c t i v i t i e s  Point XZnO (see Part A) K 1300°C  * i3oo°c Pe0  ? ZnO,» «^ o„  1300 C  aZn0  l600°C  Pe0  1 2 3 4 5 6  .663 .647 .710 .663 .702 .712  .46 .46 .45 .45 .45 .45  1.25 1.29  7 8 9 10 11 12 14 15  .976 .825 .715 .934 .843 .856 .778 .772 .736  .55 .525 .53 .525 .525 .525 .52 .53 .52  16 17 18 19 20 21 22 23 24 25  1.326 1.441 1.263 1.034 1.049 1.034 1.065 .940 1.018 1.086  26 27 28 29 30  1.436 1.723 1.670 1.488 1.237 1.434 1.284 1.310 1.336  13  31  32 33 34  .83 .83 .84 .79 .78 .78  .028 .031 .058 .058 .081 .081  1.54 1.42 1.39 1.40 1.34 1.24 1.28 1.10  1.50 1.17 1.00 1.30  .032 .072 .063 .080 .081 .081 .087 .078 .089  .795 .785 .775 .785 .78 .79 .785 .79 .785 .785  1.66 1.79 1.88 1.48 1.65 1.27 1.49  2.20 2.58 2.38 1.53 1.73  .86 .885 .885 .885 .88 .875 .865 .86 .845  1.56 1.19 1.24 1.21 1.27 1.37 1.48 1.52 1.59  Regular Solution Temperature Adjustment t Prom Auxiliary Ternary Systems  1.17  1.21  1.11  1.08  1.13  l.?9  1.52 1.47  1.13  1.06 1.00 .85 .83  1.31  1.58 1.21 1.55 1.60 2.22 2.05 2.07 1.80  1.57 1.96 1.90 1.99 2.12  .061 .118 .130 .099 .123 .096 .118 .095 .121 .125 .072 .095 .095 .097 .102 .127 .128 .132 .141  

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