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The activity of zinc oxide in multicomponent slags 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 for the degree of MASTER OF APPLIED SCIENCE Members of the Department of Mining and Metallurgy THE UNIVERSITY OF BRITISH COLUMBIA August, I960. 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 o f the requirements f o r an advanced degree at the U n i v e r s i t y o f B r i t i s h Columbia, I agree t h a t the L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r r e f e r e n c e and study. I f u r t h e r agree t h a t permission f o r e xtensive copying of t h i s t h e s i s f o r s c h o l a r l y purposes may be granted by the Head of my Department or by h i s r e p r e s e n t a t i v e s . I t i s understood that copying or p u b l i c a t i o n of t h i s t h e s i s f o r f i n a n c i a l g a i n s h a l l not be allowed without my w r i t t e n p e r m i s s i o n . Department of Mining and Metallurgy The U n i v e r s i t y of B r i t i s h Columbia, Vancouver 8\ Canada. Date August 15th, i960. i ABSTRACT The a c t i v i t y of zin c oxide i n multicomponent slags has been investigated. A c t i v i t i e s were determined experimentally 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 a c t i v i t i e s i n the Zn-Cu-Pe system were obtained from experimental i r o n s aturation data and a v a i l a b l e information on the Zn-Cu and Cu-Fe systems. Where measurement was not possib l e , thermodynamic analyses of s l a g systems were c a r r i e d out. Ri g i d a c t i v i t y patterns i n the ZnO-SiOg, ZnO-FeO-SiOg, ZnO-CaO- SiOg and ZnO-FeO-CaO-SiOg systems have "been developed from experimental and a n a l y t i c a l data. Agreement with the a c t i v i t y data of B e l l , Turner and Peters on ZnO-FeO-CaO-SiOg and Okunev and Bovykin on ZnO-FeO-SiOg type slags i n d i c a t e s that the present measurement teohnique provides a good basis f o r i n d u s t r i a l s l a g i n v e s t i g a t i o n s . i i ACKNOWLEDGEMENT The author gratefully acknowledges Dr. C. S. Samis and Mrs. A. M. Armstrong for their assistance and encouragement. It i s a pleasure to acknowledge Mr. G. W. Toop for many profitable discussions of the work. The author wishes to thank the Consolidated Mining and Smelting Company of Canada Limited for 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 for financial support of the research. i i i TABLE OP CONTENTS Page I. INTRODUCTION 1 Object and Scope of the Present Investigation . . . . 2 I I . METHOD OP ACTIVITY MEASUREMENT 3 A. Iron Activity 4 B„ Zinc Activity 4 1. Methods of Thermodynamic Analysis 4 2. Discussion ... . 7 3 . Possible Errors Arising from the Use of Zinc Activities in the Zn-Cu-Fe System 9 C. Activities of Iron Oxide and Zinc Oxide 9 D. Rearrangement of the Equilibrium Constant . . . . 11 I I I . EXPERIMENTAL 12 A. Materials 12 B. Crucibles 12 C. Furnace 12 D. Temperature Control . . . . . 12 E. Procedure 16 F. Assaying 16 IV. INVESTIGATION OP THE Zn0-Pe0-Si02 SYSTEM 17 A. 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 i v TABLE OP CONTENTS (continued) Page B o Experimental Zinc Oxide Activity Determination, System ZnO-FeO-Si02 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 Activities . . 28 D. Summary of Thermodynamic Data, ZnO-FeO-Si02 System 31 V. INVESTIGATION OP THE ZnO-FeO-CaO-Si02 SYSTEM 35 A. Auxiliary Systems 35 1. Zn0-Pe0-Si02 System 35 2. Fe0-Ca0-Si02 System 35 3. Zn0-Ca0-Si02 System 36 B. Experimental Zinc Oxide Activity Determination, System Zn0-Fe0-Ca0-Si02 47 VI. COMPARISONS WITH OTHER INVESTIGATIONS 52 A. Richards and Thorne 52 B. Okunev and Bovykin 52 C. B e l l , Turner and Peters 54 VII. DISCUSSION 58 VIII. CONCLUSIONS 59 IX. REFERENCES 60 X. APPENDICES I. Calculations on the Zn-Cu-Fe System 62 I I . Calculation of A c t i v i t i e s , System ZnO-Si02 . . . . 64 I I I . Determination of Zinc Oxide Ac t i v i t i e s , System ZnO-FeO-SiO,, 68 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 Ac t i v i t i e s , System ZnO-CaO-FeO-Si02 . 75 v i LIST OP FIGURES Fig, No. Page lo Isoactivity Pattern, Zn-Cu-Pe System, 1300°C 5 2 . Zinc Activity 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 Details 15 8. Activity of Ferrous Oxide in Binary Silicate Melts at 1315°C 18 9 . Activity of Si0 2 , System FeO-Si0 2, 1300°C, calculated from Schuhmann and Ensio 19 10. Phase Diagram, ZnO-Si02 System 21 11. The Activities of ZnO and Si0 2, ZnO-SiOg System, 1300°C . 22 12. Regular Solution Plots of ZnO, FeO and CaO i n Binary Silicate Systems, l600°C 24 13. S i l i c a Isoactivity Pattern, Zn0-Fe0-Si0 2 System, 1300°C . 26 14. Experimental Activity Coefficient Ratios, ZnO-FeO-SiOp System, 1300°C 7 . . 27 15. Experimental Zinc Oxide Isoactivity Lines, ZnO-FeO-SiO_ System, 1300°C . 29 15a. Iron Oxide Activity Pattern, ZnO-FeO-SiOg System, 1300°C . 30 16. Summary of Zinc Oxide Activity Data, ZnO-FeO-SiO,, System, 1600°C d 32 17. Summary of Iron Oxide Activity Data, ZnO-FeO-SiO- System, 1600°C d 33 18 . S i l i c a Isoactivity Pattern, ZnO-FeO-Si02 System, l600°C . 34 19. Activities i n the Ca0-Si0 2 System, 1600°C 37 2 0 . Iron Oxide Isoactivity Pattern, PeO-CaO-SiO, System, l600°C 39 v i i LIST OP FIGURES (continued) Fig. No. Page 21. CaO Isoactivity Pattern, FeO-CaO-Si02 System, l600°C . . . 40 22. S i l i c a Isoactivity Pattern, FeO-CaO-Si02 System, l600°C . . 41 23. Activities of ZnO and SiOg, ZnO-SiOg System, 1600°C . . . . 42 24. Phase Diagram, ZnO-CaO-Si02 System 43 2 5 . Zinc Oxide Isoactivity Pattern, ZnO-CaO-Si02 System, 1600°C 44 26. Lime Isoactivity Pattern, ZnO-CaO-Si02 System, l600°C . . . 45 27. S i l i c a Isoactivity Pattern, ZnO-CaO~Si02 System, l600°C . . 46 28. Isoactivity Patterns, Zn0-Fe0-Ca0-Si0? System, l600°C, 40$ S i 0 2 Cut 48 2 9 . Isoactivity Patterns, Zn0-Fe0-Ca0-Si0p System, l600°C, 34$ S i 0 2 Cut 49 30. Isoactivity Patterns, Zn0-Fe0-Ca0-Si0? System, l600°C, 21.5$ S i 0 2 Cut * 50 31. Isoactivity Patterns, ZnO-PeO-CaO-SiOp System, l600°C, 13$ S i 0 2 Cut 51 32. Comparison of Activity Data, ZnO-FeO-Si02 System, 1200°C . 55 33. Comparisons of Activity Data, ZnO-FeO-Ca0-Si09 System, 3 3 a . 1200°C d 56 , 57 3 4 . Integration Paths, Zn-Cu-Fe System 63 3 5 . Regular Solution Plot of S i 0 o Activity, System Zn0-Si0 o, 1600°C f f . . 66 3 6 . Integration Paths, Zn0-Fe0-Si02 System 71 3 7 . . Integration Paths, ZnO-CaO-Si09 System 74 v i i i LIST OP TABLES Table No. Page 1. Activities of ZnO and Si 0 2 , Zn0-Si02 System, 1300°C . . . . 23 2. Activities in the CaO-Si02 System, l600°C . 38 3. Comparison of the Data of Richards and Thorne and the Results of the Present Investigation 53 ( THE ACTIVITY OF ZINC OXIDE IN MULTICOMPONENT SLAGS INTRODUCTION The thermodynamic a c t i v i t y of zinc oxide i n m e t a l l u r g i c a l slags 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 zinc oxide are produced i n several lead and copper smelting processes. Zinc i s recovered from these slags "by s e l e c t i v e reduction processes. The a c t i v i t y of zinc oxide i n slags i s an important f a c t o r i n the rate of zinc e l i m i n a t i o n and the t o t a l zinc recovery. A review of the l i t e r a t u r e indicates that several i n v e s t i g a t i o n s of zinc oxide s l a g systems have "been made. The ZnO-SiOg and the ZnO-CaO-SiO,/ phase diagrams have been evaluated. The entropy of fusion^ and free energy of formation^ of Zn 2SiO^ have been estimated. Three i n v e s t i g a t i o n s i n t o the 5 6 7 a c t i v i t y of zinc oxide i n slags have been made ' ' . 5 B e l l , Turner and Peters investigated Zinc Fuming Furnace slags, making use of two equilibrium r e a c t i o n s : ZnO + CO g Zn + C0 2 . . . . ( l ) CO + H 20 £ C0 2 + H 2 . . . . (2) These authors c a l c u l a t e d zinc oxide a c t i v i t i e s from the instantaneous zinc e l i m i n a t i o n rates and f u e l compositions i n an operating zinc fuming furnace. A s i m i l a r i n v e s t i g a t i o n was c a r r i e d out by Okunev and Bovykin on the slags from copper and lead 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 operating conditions, the assumption that equilibrium i s reached i n these processes has been questioned^. An experimental i n v e s t i g a t i o n of zinc oxide s l a g systems was 7 c a r r i e d out by Richards and Thome . Two e q u i l i b r i a were involved: ZnO + CO Zn + C0 2 . . . . (3) PeO + CO + Pe + C0 2 . . . . (4) The slags investigated contained l e s s than two mol per cent zinc oxide. Object and Scope of the Present Investigation The object of the present i n v e s t i g a t i o n i s to evaluate the a c t i v i t y of zinc oxide i n systems which ( i ) are basic components of complex slags, or ( 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 are to be c a l c u l a t e d where experimental measurement i s not poss i b l e , due to ( i ) excessive melting point temperatures, ( i i ) high zinc vapour pressures, or ( i i i ) the lack of equilibrium information. The slags to be studied i n t h i s i n v e s t i g a t i o n are the ZnO-Si0 2, ZnO-PeO-SiO_, ZnO-CaO-SiO« and ZnO-Fe0-Ca0-Si0„ systems. - 3 - METHOD OF ACTIVITY MEASUREMEHT The method proposed f o r the measurement of zinc oxide a c t i v i t i e s was the e q u i l i b r a t i o n of i r o n oxide containing slags with an i r o n saturated Zn-Cu phase. The equilibrium r e a c t i o n chosen was: (FeO) + [Zn] -» (ZnO) + [Fe] . . . . (5) s l a g metal s l a g metal phase phase i The equilibrium constant f o r t h i s r e a c t i o n has been ca l c u l a t e d from e x i s t i n g thermodynamic data^'"*"^. ( aZnO n > We] A l i q u i d standard state f o r zinc oxide was chosen because i t provides a more useful c r i t e r i o n f o r the understanding of l i q u i d s l a g behaviour. Because no data on the entropy of f u s i o n of zinc oxide was a v a i l a b l e , an estimate of 2.85 entropy u n i t s was made on the basis of a c t i v i t y c a l c u l a t i o n s i n the ZnO-SiO^ system. Whereas the entropy of fu s i o n may he i n e r r o r , a l l a c t i v i t y information obtained i n the i n v e s t i - gation i s consistent with t h i s value. The accuracy l i m i t s assigned to the equilibrium constant are those determined from the source of e x i s t i n g thermochemical data. - 4 - The evaluation of zinc oxide by this equilibrium requires that-the ac t i v i t i e s of FeO, Fe and Zn be known. Experimental conditions were estab- lished to provide this information. A, Iron Activity The activity of iron was established at unity by the use of an iron crucible for the equilibrium measurements. At equilibrium the metal phase i s saturated with t iron. B. Zinc Activity Zinc a c t i v i t i e s i n the iron-saturated brass phase were evaluated from the shape and disposition of the experimental iron saturation line (Figure l ) in conjunction with existing activity information on the Zn-Cu^ 12 and Cu-Fe systems. Iron saturation data were obtained from the experimental metal phase compositions. Using this basic information, the system was evaluated thermodynami- cally by the application of Gibbs Duhem integration techniques, and the ac t i v i t i e s of zinc and copper were calculated along the experimental iron saturation line (Appendix I ) . The results are shown i n Figures 1 and 2. 1. Methods of Thermodynamic Analysis Three different methods of thermodynamic analysis were employed in the calculation of zinc a c t i v i t i e s . These techniques were also used in later examinations of ternary slag systems.  - 6 - 0 4 8 12 16 20 Mol i> Zinc Figure 2. Zinc Activity along Iron Saturation Line, System Zn-Cu-Fe, 1300°C. - 7 - l ) Schuhmann's graphical application of the Gibbs Duhem equation^. 2) Schuhmann1 s ternary intercept Gibbs Duhem integration^, i.e. Lna 2 = - / I /d \ dLna1 j 3) The "basic Gibbs Duhem integration application along an iso- activity 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 activity information could he u t i l i z e d i n the evaluation and verification 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 ac t i v i t i e s appears to be slight. 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 com- pletely regular. The calculation of the iron saturated system shows that although the zinc activity coefficient i s raised the system exhibits near regular solution behaviour. - 8 - 4 3 - CM do I a N 2 0 0 Gu-Zn System Everett, Jacobs and Kitchener, 1300°C 1 : L Present Investigation Iron Saturated Zn-Cu System 1300°C X" Points Calculated on I s o a c t i v i t y Diagram (Figure l ) 10 15 Mol f, Zn 20 25 30 re 3, Comparison of Regular Solution P l o t s of Zn-Cu and Fe Saturated Zn-Cu Systems, 1300°C. - 9 - 3. Possible Errors Arising from the Use of Zinc Activities i n the Zn-Cu-Fe System The total errors introduced by the use of zinc ac t i v i t i e s i n the ternary metal phase were estimated at - 16$. Everett, Jacobs and Kitchener''"''' report their experimental error to be less than - 1$. Assaying errors i n the present investigation are given at ±3$. ' Temperature errors have a twofold effect. Because of the high 15 temperature dependence of the Fe saturation composition in the Cu-Fe system (Figure 4)> the ternary Fe saturation line may vary up to - .8 mol per cent Fe with a - 10°C variation. Temperature variations also cause a small direct effect on zinc activity. Within the temperature accuracy given (- 10°C) the total temperature effect on zinc activities was estimated to be - 2$. Calculation errors were assigned on the basis of detectable v a r i - ations in the isoactivity 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 relatively small amounts of iron present, calculation error limits were estimated at — 10$. C. Activities of Iron Oxide and Zinc Oxide Because the activity 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 iron oxide. Prior to the interpretation of experimental results available information on auxiliary 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 calculation of zinc oxide a c t i v i t i e s from experimental and auxiliary infor- mation. This was accomplished by expressing the i n i t i a l results i n the form of acV̂ Q ratio, i.e. %FeO ZnO _ * FeO = h ™ L*ZnO Cs3 - 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 for several hours. Several blank runs were made i n each crucible before experi- mental use. C. Furnace A simple "Glo Bar" furnace was used (Figure 6). Construction details are shown in 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. Temperature accuracies were given at - 10°C. - 13 - - 14.- Figare 6« Experimental Furnace - 15 - Thermocouple s to Controller 20" Chamber Fire Clay Brick (3000°F) 16" Conductor Straps Terminals •§-" Aluminum Sheathing Depth: Furnace 16" Chamber 10" Heat Source: 2 sets of 3 "Glo Bars" i n parallel 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«2^3 a n ( * F e powders (Fe and Fe20^were mixed stoichiometrically to form FeO). 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 in 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 fa 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$. - 17 - Metal assays were c a r r i e d out by Mrs. A. M. Armstrong and the author. Samples were taken by d r i l l i n g completely through the metal buttons. Copper was determined e l e c t r o l y t i c a l l y , zinc by potentiometric t i t r a t i o n using the potassium f e r r o - f e r r i c y a n i d e couple, and i r o n by t i t r a t i o n with potassium dichromate. The accuracies of the assays were estimated to be: zinc - 2$, i r o n - 1$, Cu - 1%. INVESTIGATION OP THE Zn0-Fe0-Si0 o SYSTEM The most elementary system which could be studied by the present technique was the Zn0-Pe0-Si02 system. For t h i s reason an extensive i n v e s t i - gation of t h i s system was c a r r i e d out. Component PeO-SiOg and ZnO-SiOg systems were examined to provide the required a u x i l i a r y information. A. A u x i l i a r y Systems l ) PeO-Si0 2 lo* 17 18 The PeO-SiOg system has been studied extensively ' ' . The i n v e s t i g a t i o n s which give the most consistent r e s u l t s are those of Bodsworth and Davidson , and Schuhmann and Ensio , who measured the a c t i v i t y of 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 slags. The most recent information on t h i s system i s presented i n Figures 8 and 9, based on l i q u i d standard states f o r both FeO and SiOg. A l l recent i n v e s t i g a t i o n s give values i n close agreement with t h i s data.  - 19 - - 20 - 2) Zn0-Si0 2 System Because the present experimental technique could not he used to measure a c t i v i t i e s i n the Zn0-Si0 2 system, a c t i v i t i e s of zinc oxide were cal c u l a t e d from phase diagram and entropy of f u s i o n data. The phase diagram i n the ZnO-SiOg system has been investigated* (Figure 10). The entropy of f u s i o n of s i l i c a ^ and the entropy of f u s i o n of Z n 2 S i O ^ have been estimated. S i 0 2 A H f = 3600 - 1456 K c a l / m o l (1713°C) ( c r i s t o b a l i t e ) Zn 2SiO^ A S f = 10.5 E.U. (no accuracy l i m i t s given) Using t h i s data the a c t i v i t i e s of S i 0 2 and ZnO were ca l c u l a t e d by 20 means of the l i q u i d u s curve method of Chipman and the congruent melting 21 point method of Hauffe and Wagner (Appendix I I ) . The r e s u l t s of the a c t i - v i t y c a l c u l a t i o n s f o r t h i s system are shown i n Figure 11 and Table 1. (Liq u i d standard state f o r both ZnO and S i 0 2 ) . Regular s o l u t i o n p l o t s of FeO and ZnO i n t h e i r respective s i l i c a t e systems are shown i n Figure 11. These p l o t s provide the best means of i n t e r - p o l a t i n g data and a l s o demonstrate the s i m i l a r i t i e s i n behaviour patterns i n these systems. 22 23 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 ' i s included to show the r e l a t i v e p o s i t i o n of zinc oxide a c t i v i t i e s i n binary s i l i c a t e systems. - 21 - - 22 - Figure 11. The Activities of ZnO and Si0 2, Zn0-Si02 System,.1300°C. Table 1. A c t i v i t i e s of ZnO and Si0 9, ZnO-SiO, System, 1300°C. N s i o 2 aZnO - a s i o 2 NZnO 0 1 0 1 ol 087 .008 • 9 .2 .70 .029 .8 .3 .47 .11 .7 .4 .26 .295 .6 .5 .13 .70 .5 .6 .08 .946 .4 .7 .073 .946 .3 .8 .073 .946 .2 • 9 .073 .946 .1 ] 0 1 0 - 24 - - 25 - 3) S i l i c a A c t i v i t i e s , ZnO-FeO-Si0 2 System The s i l i c a i s o a c t i v i t y pattern i n the ZnO-FeO-Si0 2 system was obtained from the above ZnO-SiCv, and FeO-SiO^ information. I s o - s i l i c a t e l i n e s were obtained by j o i n i n g points of i d e n t i c a l s i l i c a a c t i v i t y on the two b i n a r i e s . able to e s t a b l i s h the curvature of the s i l i c a i s o a c t i v i t y l i n e s . Curvatures consistent with observed i s o a c t i v i t y patterns of s i m i l a r systems (ZnO-CaO-SiO, Figure 275 FeO-CaO-Si0 2, Figure 22) were assigned (Figure 13). B. Experimental Zinc Oxide A c t i v i t y Determination, System ZnO-FeO-Si0 5 Experiments on the ZnO-FeO-SiO^ system were c a r r i e d out at three s i l i c a concentration l e v e l s . Zinc oxide and i r o n oxide compositions were varied at each l e v e l . a ^ values. The r e s u l t s are shown i n Figure 14 and Appendix I I I . The ZnO//„ n r a t i o s were found to vary l i n e a r l y with ZnO concentration at each No phase diagram information on the Zn0-Fe0-Si0 o system was a v a i l - The experimental c a l c u l a t e d from measured ZnO a c t i v i t i e s from Two approximation steps were employed. l ) F i r s t Approximation, Zinc Oxide A c t i v i t y C a l c u l a t i o n The c a l c u l a t i o n of zinc oxide a c t i v i t y was i n i t i a t e d by f i r s t  42# Si 0 2 O 2256 S i 0 2 + 39* S i 0 2 O 4256 Si 0 2 J I I I I L I L 2 3 4 5 6 7 Mol $> ZnO Figure 14. Experimental Activity Coefficient Ratios, ZnO-FeO-Si02 System, 1300°C. 1 ro - 28 - making the assumption that iron oxide activity i s constant at constant s i l i c a concentration over the experimental range. Iron oxide activity values were evaluated from the binary FeO-SiOg system (Figure 8) and were projected along the s i l i c a concentration lines. The FeO activity coefficients were then evaluated for the experimental ZnO concentrations. These activity coefficients were applied to the experimentally determined coefficient ratios, giving approximate ZnO activity values. Points of identical activity were then joined, creating tentative ZnO isoactivity lines. 2) Final Determination of a„ n ' ZnO From the tentative ZnO isoactivity model precise values of a^Q were evaluated. Using available s i l i c a isoactivity lines (Figure 13), more accu- rate tfpeQ values were obtained by thermodynamic analysis of the system. (The three methods employed are outlined on page 7.) Zinc oxide act i v i t i e s were then recalculated on the basis of the re-evaluated o'T- « data. FeO The technique of successive approximations produced mutually con- sistent activity values for FeO and ZnO and created a thermodynamically r i g i d isoactivity pattern over the experimental range. The results are shown i n Figures 15 and 15a and Appendix I I I . C. Accuracy of Experimental Zinc Oxide Activities The accuracy of the experimental zinc oxide act i v i t i e s was e s t i - mated to be - 43$. The possible errors involved i n the use of the equilibrium constant (- 15$) and zinc ac t i v i t i e s i n the Zn-Cu-Fe system (- 16$) have been discussed (Schuhmann and Ensio 1^ report their a_, n values are accurate to within - 2$). Figure 1 5 . Experimental Zinc Oxide I s o a c t i v i t y Lines, ZnO-FeO-SiO_ System, 1 3 0 0 ° C .  - 31 - The errors i n the approximation techniques were estimated to he i 10$. This estimate was made on the basis of activity 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 solu- 24 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/^peQ ratio data at 41$ Si02 was extrapolated linearly to 15$ ZnO. This assumption made possible the extension of the SL^aO = # 1 i s o a c " t i v i ' t y l i n e 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-Si02 SYSTEM Because the ZnO-FeO-CaO-Si02 system c l o s e l y approximates the compositions of i n d u s t r i a l slags, an extensive i n v e s t i g a t i o n of t h i s system was made. Zinc oxide a c t i v i t i e s were measured over extensive ranges of s i l i c a , lime, and i r o n oxide compositions. Examinations of the component ternary systems were made to provide the a u x i l i a r y information required f o r the determination of zinc oxide a c t i - v i t i e s . The ternary systems examined were the ZnO-FeO-Si0 2, FeO-CaO-Si0 2 and ZnO-CaO-Si09 systems. A. A u x i l i a r y Systems l ) ZnO-FeO-Si0 2 System The a c t i v i t i e s i n the ZnO~FeO-Si0 2 system were evaluated and summarized e a r l i e r i n the i n v e s t i g a t i o n (Figures 16, 17 and 18). 2) Fe0-Ca0-Si02 System The FeO-CaO-Si0 2 system has been studied extensively by Winkler 25 26" 2T and Chipman , Taylor and Chipman , Turkdogan and Pearson , and others. 28 E l l i o t has made a comprehensive review of these studies and, by a p p l i c a - t i o n of the Gibbs Duhem equation, has determined a c t i v i t i e s of a l l compon- ents i n the system. The slags investigated contained small amounts of MgO, but according to E l l i o t , the s i m i l a r behaviour of CaO and MgO allows the r e s u l t s to be interpreted as a c t i v i t i e s i n the simple Fe0-Ca0-Si02 ternary system. 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 activity pattern i s shown i n Figures 20, 21 and 22. 3) ZnO-CaO-Si02 System At the outset of the investigation, i t was hoped that the activity of ZnO in the ZnO-CaO-Si02 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 acti v i t i e s were: i ) Zinc oxide and s i l i c a a ctivities in the ZnO-Si0 2 system (Figure 2 3 ) . 22 23 i i ) Lime and s i l i c a a c t i v i t i e s in the CaO-Si02 system ' (Figure 1 9 ) . i i i ) Lime, s i l i c a and zinc oxide saturation lines i n the ZnO-CaO-Si02 system (Figure 2 4 ) . The ZnO-CaO-Si02 system was analyzed thermodynamically on the basis of this data and a r i g i d isoactivity pattern was developed (Figures 25, 26 and 27).  Table 2. A c t i v i t i e s i n the CaO-SiCL System, l600°C. NSi0 2 - aCaO a s i o 2 NCaO .07 .92 .000015 .93 .18 .69 .000105 .82 .26 .48 .00038 .74 .33 .28 .0013 .67 .39 .14 .005 .61 .45 .04 .03 .55 .48 .013 .10 .52 .49 .0068 .20 .51 .52 .0031 .40 .48 .54 .0021 .60 .46 .58 .0012 .80 .42 .62 .0005 .90 .38 .67 .00005 .95 .33    - 42 - - 43 - S i 0 2 Weight # ZnO Figure 24. Phase Diagram, Zn0-Ca0-Si02 System Showing Shapes of Saturation Lines at 1500°C. 30' S i l i c a Saturation Mol $ CaO 70 60 40 ZnO .023 60 50 / / / / '/'// / / / / / / 'HI / / Lime Saturation Extrapolations of Calculated Data / / / / / Mol $ SiO„ CaO " A " 10 T V 20 "TV 30 A 50 Mol fo ZnO To T V 70 TV 90 Figure 25. Zinc Oxide I s o a c t i v i t y Pattern, System ZnO-CaO-SiO,,, l600°C.  30 S i l i c a Saturation 4 0 ' Mol $ CaO - a S i 0 2 = ' 9 5 . 9 . 8 .7 . 6 . 5 .4 .3 .2 .1 70 70. .05 80 90j CaO Mol # ZnO Figure 21. S i l i c a Isoactivity Pattern Zn 0-CaC~SiO„ System, 1600 C. - 47 - B.' Experimental Zinc Oxide A c t i v i t y Determination, System ZnO-FeO-CaO-SiO, Experimental measurements on the ZnO-FeO-CaO-Si02 system were c a r r i e d out at f i v e s i l i c a concentration l e v e l s , the CaO,FeO, and ZnO con- centrations being varied at each l e v e l . The experimental o'znO/^ F e 0 r a t i o s at each s i l i c a l e v e l are tabulated i n Appendix VI. Zinc a c t i v i t i e s were interpreted by e f f e c t i v e l y ' s l i c i n g * the quaternary system at each experimental s i l i c a l e v e l . Each ' s l i c e ' then represented a 'pseudo-ternary' cut. On each cut the intercepts of the FeO and ZnO i s o a c t i v i t y l i n e s were known from evaluations of the ZnO-CaO-Si0 2, Zn0-Fe0-Si0 2, and FeO-CaO-Si0 2 systems. I t was found that on both the ZnO-FeO-Si0 2 and FeO-CaO-Si0 2 systems the i r o n oxide i s o a c t i v i t y l i n e s were nearly p a r a l l e l to the s i l i c a s l i c e s . This meant that on the 'pseudo-ternary' cuts FeO a c t i v i t i e s appeared as planes of almost constant a c t i v i t y over the experimental regions. This a c t i v i t y behaviour of FeO s i m p l i f i e d the determination of &2,n0' FeO a c t i v i t i e s could be assigned with good accuracy over the experimental region on each cut, and o o u ^ ^ ^ e evaluated from the experimental a c t i v i t y c o e f f i c i e n t r a t i o s . I t was estimated that the use of t h i s c a l c u l a t i o n t e c h n i - que i n the determination of zinc oxide a c t i v i t i e s introduced possible errors of - 10$. These l i m i t s were based on a p e Q accuracy l i m i t s i n the FeO-CaO-Si0 2 and Zn0-Fe0-Si0 2 systems and possible a p e Q v a r i a t i o n s on the 'pseudo-ternary' cuts. Zinc oxide a c t i v i t i e s were calculated (Appendix VI)and plotted at each experimental point, and i s o a c t i v i t y l i n e s were drawn i n c l u d i n g the i n t e r - cepts on the ZnO-FeO-Si0 2 and ZnO-CaO-Si0 2 systems. The r e s u l t s are shown i n Figures 28, 29, 30 and 31. CaO Mol $ ZnO Figure 28. Isoactivity Patterns, ZnO-FeO-CaO-Si02 System, l600°C. 40$ Si0 2 Cut CaO Mol $ ZnO Figure 29. Isoactivity Patterns, ZnO-FeO-CaO-SiO? System, 1600°C. 34$ S i 0 2 Cut CaO Mol $ ZnO Figure 30. Isoactivity Patterns, ZnO-FeO-CaO-Si02 System, l600°C. 21.5$ S i 0 2 Cut Figure 31. Isoactivity Patterns, 2toO-FeO-CaO-Si02 System, l600°C. 13$ Si0 2 Cut - 52 - Because of the number of components in the system, no extension or check of the data was possible. The data is presented, therfore, without thermodynamic verification. COMPARISONS WITH OTHER INVESTIGATIONS The results 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 activity data of previous investigations i s reported with reference to a solid standard state, a liquid 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 in Table 3. Their reported zinc oxide a c t i v i t i e s are generally lower than the results of the present investigation but are within the suggested accuracy limits. B. Okunev and Bovykin Two slag types were studied by Okunev and Bovykin: (i) slags essentially 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 ZnO Slag Assays (Mol $) Richards and Thome a_ * ZnO 1 Present a +  ZnO s i o 2 CaO FeO 1.4 33 — 66 .0135 .010 1.5 27 33.5 38 .021 .030 1.5 40 21.5 37 .0165 .015 1.3 24 18 57 .016 .024 1.3 27 18 54 .0145 .021 1.3 34 10.5 53 .0115 .0145 1.6 39 26.5 • 33 .0185 .018 * Liquid Standard State 1" Obtained from S i l i c a Cuts ZnO-FeO-CaO-SiO,, System and adjusted to 1200°C. The r e s u l t s o f t h e p r e s e n t i n v e s t i g a t i o n were f o u n d t o he i n r e a s o n a b l e agreement w i t h t h e i r a c t i v i t y d a t a on t h e ZnO-FeO-SiCv, s y s t e m ( F i g u r e 3 2 ) . A c t i v i t y 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 t h e p r e s e n t r e s u l t s on t h e ZnO-FeO-CaO-SiCv, s y s t e m by a s s u m i n g t h a t s ( i ) MgO and CaO, and ( i i ) S iO^ and A l ^ O ^ behave s i m i l a r l y i n b a s i c s l a g s . On t h i s b a s i s t h e p r e s e n t r e s u l t s were 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 d a t a r e p o r t e d b y Okunev and B o v y k i n ( F i g u r e 3 3 ) . 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 and t h e r e s u l t s o f t h e p r e s e n t 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 r a n g e ( F i g u r e 3 3 a ) . T h i s agreement i n d i c a t e s t h a t t h e b e h a v i o u r o f t h e i r i n d u s t r i a l s l a g s i s c l o s e l y a p p r o x i m a t e d b y t h e s y n t h e t i c s l a g s o f t h i s i n v e s t i g a t i o n . 4 » • H > •r l - P O <! O ,20 .15 .10 Average Compositions: Si0 2 or (Si0 2 + A l ^ ) - 32 Mol # CaO or (CaO + MgO) Remainder 1 Mol $ (assumed negligible) ZnO + PeO »05 Present Investigation Obtained from Isoactivity Lines 1300°C. Okunev and Bovykin 10 Mol $. ZnO Figure 32. Comparison of Activity Data, Z n 0 - P e 0 - S i 0 2 System, 1200°C. Basis: Liquid Standard State. 15 VJ1 .20 .15 - -H> •H >• •rl •P O <J O .10 _ .05 - Average Compositions: S i 0 2 or (Si0 2 + A l ^ ) CaO or (CaO + MgO) Remainder 31 Mol $ 21 Mol i ZnO + PeO Present Investigation Obtained from I s o a c t i v i t y Patterns, = .215 ' S i 0 2 and .34 Cuts (Figures 2$ and 30) Mol % ZnO Figure 33. Comparison of A c t i v i t y Data, ZnO-PeO-CaO-Si02 System, 1200°C. Basis: L i q u i d Standard State. 15 ON . 2 0 .15 4> + » O <-o 3 .10 . 0 5 Average Compositions S i 0 2 or ( S i 0 2 + A l ^ ) » 38 Mol $ CaO 13 Mol $ Remainder ZnO • FeO Present Investigation Obtained from I s o a c t i v i t y Patterns ̂ Q^Q • »34 and .40 Cuts (Figures 28 and 29) B e l l , Turner and Peters" 10 Mol # ZnO Figure 33a. Comparison of A c t i v i t y Data, ZnO-FeO-CaO-SiOg System, 1200°C. Basis: L i q u i d Standard State. 15 i —i I . 58 - DISCUSSION Ce r t a i n inherent problems e x i s t i n the measurement of zinc oxide a c t i v i t i e s . Because of high vapour pressures of zi 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 lead oxide determinations are not pos s i b l e . A l l i n v e s t i g a t i o n s ( i n c l u d i n g the present) have had to r e l y , therefore, on two phase equilibrium measurements f o r the determination of zinc oxide a c t i v i t i e s . The technique used i n the present i n v e s t i g a t i o n has one major disadvantage. Because the FeO-Fe equilibrium was used to e s t a b l i s h the oxygen pressure of the system, the a c t i v i t y of i r o n oxide i n the s l a g had to be evaluated. In the i n v e s t i g a t i o n of the ZnO-FeO-SiOg and ZnO-FeO-CaO- Si02 systems approximation techniques had to be developed to make the experimental determination of zinc oxide a c t i v i t y p o s s i b l e . Since zinc oxide concentrations were r e l a t i v e l y low, information on the component systems could be s u c c e s s f u l l y used i n the evaluation of ZnO a c t i v i t i e s . The scope of the present i n v e s t i g a t i o n was l i m i t e d to brass compositions which are l i q u i d at 1300°C. Above a zinc a c t i v i t y of .07 the vapour pressure exceeds one atmosphere and b o i l i n g occurs. Measurements were l i m i t e d to zinc oxide compositions corresponding to zinc a c t i v i t i e s l e s s than t h i s value. - 59 - CONCLUSIONS A slag-metal equilibrium technique has been developed for the measurement of zinc oxide a c t i v i t i e s i n slags. By this method ZnO slags containing FeO were equilibrated with iron saturated brasses. Zinc oxide ac 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 iron oxide slags. Thermodynamic analyses of the ZnO-SiOg and ZnO-CaO-SiOg systems have been carried out using available thermochemical information. Combi- nations of the experimental and calculated data have produced r i g i d iso- activity patterns for the systems studied. The experimental and analytical results are best summarized by reference to Figures 11, 15, 16, 25, and 28 to 31, i n which isoactivity patterns for the systems investigated are shown. The agreement of these results on synthetic slag systems with the industrial 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 for the investigation of zinc oxide activity behaviour in industrial slags. _ 60 - REFERENCES 1. E. N. Bunting, J. Am. Ceram. Soc.} 13, [1] 8 (1930). - ._. 2. E. R. Segnit, J. Am. Ceram. Soc.} 3J_, [6] 274 (1954). 3. F. D. Richardson, "The Physical Chemistry of Melts", Inst. Min. Met., London (1953) p. 87. 4. J. A. Kitchener and S. Ignatowitz, Trans. Faraday Soc.} 4J,, 1278 ( l95 l ) . 5. R. C. B e l l , G. H. Turner and E. Peters, J. Metalsj 6, 472 (1955). 6. A. I. Okunev and V. S. Bovykin, Proc. of the Academy of Sciences of the U.S.S.R., Chemistry Section, 112, 77 (1957). 7. A. W. Richards and D. J. Thorne, "The Activities of Zinc Oxide and Ferrous Oxide in Liquid Silicate Slags", unpublished. 8. H. H. Kellogg, Eng. and Mining J.} 158. [3] 90 (1957). 9. G. L. Humphrey, E, G. King and K. K. Kelley, U.S. Bureau of Mines Report of Investigations No. 487O (1952). 10. C. G. Maier, G. S. Parks and C. T. Anderson, J. Am. Chem. Soc.} 4j3, 2564 (l926)o 11. L. H. Everett, P. W. M. Jacobs and J. A. Kitchener, Acta Met.; J5_, 28l (1957). 12. J. D. Morris and G. R. Zellars, J. Metalsj 8_, 1086 (1956). 13. R. Schuhmann, Jr., Acta Met.} 3_, 220 (1955). 14. R. Schuhmann, Jr., Acta Met.} 3,, 223 (1955). 15. B. N. Daniloff, "Metals Handbook", American Society for Metals (1948). 16. C. Bodsworth and I. M. Davidson, "The Activity of Ferrous Oxide i n the Fe0-Si0 2 System", to be published. 17. R. Schuhmann, Jr., and P. J. Ensio, J. Metals} 3,, 401 ( l95 l ) . 18. N. A. Gocken and J. Chipman, Trans. A.I.M.E.} 194. 171 (1952). 19. P. B. Richardson, "Physical Chemistry of Melts", Inst. Min. Met., London, (1953) p. 93. 20. J. Chipman, Discussion Faraday Soc; _4_, 23 (1948). 1 - 61 - 21 . Hauffe and Wagner, Z. Elektrochem.} 4 6 , 160 ( 1940) . 2 2 . F. D. Richardson, "The Physical Chemistry of Melts", Inst. Min. Met., London (1953) p. 8 3 . 2 3 . F. C. Langenherg and J. Chipman, Trans. A.I.M.E.; 215. 958 (1959) . 2 4 . M. Rey, "The Physical Chemistry of Melts", Inst. Min. Met., London (1953) P. 6 3 . 2 5 . T. B. Winkler and J. Chipman, Trans. A.I.M.E.} 167. I l l ( 1946) . 26 . C. R. Taylor and J. Chipman, Trans. A.I.M.E,} 154, 228 (1943). 27. E. T. Turkdogan and J. Pearson, J. Briti s h Iron and Steel Inst.} 173, 217 ( 1 9 5 3 ) O 2 8 . J. F. E l l i o t , J. Metals; 6, 485 (1955). 2 9 . G. W. Toop, private communication. APPENDIX I Calculations on the Zn-Cu-Fe System A. Simple Gibbs Duhem Integration aCu Statement: Lna„ ̂  = Lna„ * HCu I T ^ C u Zn cu Path: Iron Saturation Line Point (Fig. 34) lCu Cu N Zn 1 1 • "Zn I (calculated) °Zn 1300°C 1 2 3 4 5 .922 .894 .830 .766 .700 .883 .853 .809 .769 .732 .008 .045 .100 .149 .196 2.01 3.00 3.54 3.91 .001 .0065 .0175 .030 .046 .001 .0065 .0170 .030 .047 From Graphical Integrations B. Schuhmann's Intercept Integration 14 Statement: Lna, Cu Path: NCu Zn \ dLna Z n ( a Z n > N p e ) / ^ u Fe N. Fe = 19 Point (Fig. 34) lZn N Zn N, Cu II dCu (calculated "Cu 1300°C A B C D E .0009 .0065 .017 .030 .047 .009 .053 .125 .193 .264 .061 .152 .236 .338 .97 .92 .84 .77 .69 .97 .92 .85 .775 .70 From Graphical Integrations  APPENDIX II C a l c u l a t i o n of A c t i v i t i e s , System ZnO-SiGVj Ao Liq.uid.us Curve Method 20 ( T - Tm \ Statement: Lna g iQ « - S i 0 2 1 2 V T j A S f (Si0 2) - 1.8 E.U. A S f (sio 2) R * S i 0 9 1 Liquidus temperature ( K) L n a s i o 2 a s i o p T a S i O * * 1613°C 066 .60 o55 .525 1968 1853 1753 1705 =.00713 -.0559 -.1037 -.1310 .993 .946 .902 .877 °992 .918 .852 .807 Regular Solution Temperature Adjustment B. Congruent Melting Point Method' 21 Symbols: A H f = Heat of Fusion of ZngSiO^ = 18.7 Kcal/mol Q = Melting Point of Z n 2 S i 0 4 = 1784°K ^ZnO' x S i O . = Compositions of ZnO and S i 0 2 i n Zn 2SiO^ ( xZnO = ° 6 6 6 ' r « n = * 3 3 3 ) SiO„ ^' ^ZnO* ^SiO ~ ^iquidus Temperature, Compositions Lna Statement I I SiO r = L n a S i o " + A H f NZnO ( e ~ T ) + @ ' N S i 0 2 - X S i 0 2 ZnO r \±o2 (0 - T) SiO„ - 6 5 - Appendix I I (continued) N S i 0 2 T°K N x 1 NSi0 2 - *SiC f 3 i 0 2 2 S i 0 2 a S i % # a s i o ? 2 1 9 8 6 . 5 2 5 1 7 0 5 . 8 7 7 . 8 0 7 . 5 2 5 1 7 0 5 + 1 9 8 + 4 5 8 . 8 7 7 . 8 0 7 . 5 0 1 7 2 9 + 1 6 8 + 4 0 6 . 6 7 6 . 6 5 0 o 4 5 1 7 5 7 + 1 3 2 + 3 0 6 .45 . 4 5 0 . 4 0 1 7 7 5 + 8 9 . 6 + 2 0 1 . 3 0 5 . 3 1 4 . 3 5 1 7 8 4 + 3 8 . 2 + 60.3 . 1 8 3 . 1 9 5 . 3 3 3 1 7 8 5 0 0 . 1 4 0 . 1 5 4 o 3 0 0 1 7 8 4 r- 2 1 . 2 - 8 3 . 1 0 8 . 1 2 0 o 2 ol LnU Extrapolations from SiCv, Plot (Figure 3 5 <NZnO^ ) . 0 4 4 . 0 1 6 Regular Solution Temperature Adjustment C. Calculation of a„ n from a q . n Data, Gibbs Duhem Binary Integration ( 1 9 8 6 K) Statement ! LnSfZnO = L n*SiO, - fNZnO L n * S i O ? . - P J I d NZnO (*W NZnO = 1 <NZnO> ®ZnO L n S f S i 0 2 n̂7 F i r s t Term L n ZnO a Z n 0 1 9 8 6 1 08 . 6 .4 .3 o2 .1 0 - 2 . 4 3 - 2 o 3 7 - Q.67 + 2 . 7 0 + 3 . 9 0 + 5 . 3 6 + 9 . 5 + . 3 7 9 + . 1 6 1 - . 6 4 8 - . 8 1 9 - . 8 5 8 - . 8 5 5 0 - . 4 8 7 - . 8 3 2 - . 6 3 6 - . 3 0 3 + . 1 5 0 + . 8 5 0 0 - . 1 0 8 - . 6 7 1 - 1 . 2 8 4 - 1 . 1 2 2 - . 7 0 8 - . 0 0 5 1 . 7 2 .31 oil . 9 8 . 9 8 . 9 8 0  - 67 - Appendix I I (continued) D. Tabulation of Activities at 1573°K and l873°K obtained by Regular Solution Conversion NZnO H S i o 2 a Z n 01573 a S i 0 9 1573 aZnO l 8 7 3 1 a s i o P *1873 1 0 1 0 1 0 .9 .1 .87 .008 .875 .012 .8 .2 .70 .029 .72 .04 .7 .3 .47 .11 .50 .117 .6 .4 .26 .295 .295 .31 .5 .5 .13 .70 .165 .66 .4 .6 .08 .946 .10 .95 .3 .7 .073 .946 .09 .96 .2 .8 .073 .946 .10 .96 .1 .9 .073 .946 .10 .96 0 1 0 1 0 1 APPENDIX I I I Determination of Zinc Oxide Ac t i v i t i e s , System ZnO-PeO-SiO, A. Activity Coefficient Ratios Point- NZnO Slag Assays N N aFeO EiS±02 KFeO NZnO Metal Assays N N N aZn "Fe ^Cu aZn J ii ^ (1300°C FeO 1 .025 .558 .417 22.32 .051 .100 .849 .0075 .872 2 .040 .536 .423 13.40 .077 .097 .826 .012 .840 3 .046 .544 .409 11.83 .086 .095 .819 .014 .861 4 .067 .512 .420 7.54 .111 .094 .795 .020 .783 5 .071 .506 .422 7.13 .119 .090 .791 .022 .820 6 .044 .566 .390 12.86 .084 .095 .821 .0135 .904 7 .050 .559 .391 11.18 .090 .098 .812 .015 .875 8 .066 .539 .395 8.16 .112 .102 .786 .020 .861 9 .082 .521 .397 6.35 .130 .090 .780 .025 .830 10 .043 .623 .334 14.48 .076 .102 .822 .012 .908 11 .050 .615 .335 12.30 .084 .103 .813 .0135 .867 12 .021 .751 .227 35.76 .044 .105 .851 .006 1.122 13 .027 ,.747 .224 27.67 .052 .100 .848 .0075 1.080 14 .039 .741 .218 19.00 .073 .104 .823 .011 1.091 15 .049 • 730 .219 14.89 .087 .092 .821 .014 1.091 16 .054 .721 .223 13.35 .091 .097 .812 .015 1.044 17 .065 .709 .224 10.91 .105 .102 .793 .0185 1.054 - 69 - Appendix I I I (continued) B. Calculation of Zinc Oxide Activities Point (see Part A) SZnO *Fe01300°C *FeO (Thermodynamic Analysis) tfFeO KZnO aZnO 1 .872 .41 .735 .64 .016 2 .840 .40 .745 .63 .025 3 .861 .41 .755 .65 .029 4 .783 .39 .76 .60 .040 5 .820 .39 .77 .63 .045 6 .904 .435 .77 .695 .030 7 .875 .43 .77 .675 .034 8 .861 .42 .78 .67 .0445 9 .830 .41 .785 .655 .054 10 .908 .57 .915 .83 .036 11 .867 .575 .935 .81 .0405 12 1.122 .81 1.08 1.21 .0255 13 1.080 .815 I.09 1.18 .032 14 1.091 .81 1.09 1.19 .047 15 1.091 .805 1.10 1.20 .059 16 1.044 .795 1.10 1.15 .062 17 1.054 .79 l . l l 1.17 .076 APPENDIX IV Thermodynamic Analysis of the ZnO-PeO-Si02 System} Calculations A. Schuhmann"s1^ ternary intercept integrations of a ^ and a^Q were performed along paths as shown i n Figure 36. B. Sample calculation, ternary intercept integration of ZnO activ i t i e s Statement: Lna„ n =• ZnO N. ZnO dLna, SiO,. N, Path: ZnO N FeO ZnO/. N, FeO Point (Figure 36, , a S i 02 L n a S i 0 2 *Si0 2 NZn0 aZn0 Expected * aZnO 1 .83 - 0.185 1.25 0 0.10 0.10 2 .73 - 0.315 1.08 0.150 0.115 0.11 3 .60 - 0.51 0.96 0.348 0.140 0.135 4 .38 - 0.97 0.75 0.738 0.21 0.20 5 .25 - 1.39 0.61 1.023 0.28 0.27 6 .16 - 1.83 0.52 1.269 0.35 0.335 7 .10 - 2.30 0.41 1.473 0.435 0.435 * 13 Expected from graphical integrations , 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: Lna™ n « - \ ZnO ,T J *FeO **> ̂ aSi0 3 constant) P a t h s a s i o 2 a « 3 Point (Figure 3 6 ) NZnO NFeO aZnO L n aZnO 1 ^eO Expected * ^eO A B C D E 0 o 3 9 0 . 8 6 1 . 6 2 3 o 5 0 5 o 6 0 . 1 6 . 2 3 . 2 ? . 2 9 . 3 0 - 1 . 8 3 - 1 . 4 7 - 1 . 3 2 - 1 . 2 4 » 1 . 2 1 0 0 . 2 3 0 . 1 9 0 . 2 0 0 . 1 6 0 . 5 5 0 . 4 2 5 0 . 3 6 0 . 2 9 0 . 2 4 . 5 5 . 4 2 . 3 7 . 3 0 . 2 4 5 Expected from ternary intercept and graphical integrations. 73 APPENDIX V Thermodynamic Analysis of the ZnO-CaO-SiOg System; Calculations A. Schuhmann"s ternary intercept^ and simple Gibbs Duhem integrations were performed along paths as shown in Figure 37• B. For examples of integration procedures see Appendix IV. Simple Gibbs Duhem Integrations Intercept Integrations 30 70 Mol % CaO 70_ 50 60' 40 CaO ZnO Mol $ Si0 o ZnO ZnO 80> 90. 10 7 V 20 7 V 40 7V~ 50 Mol $ ZnO CaO T V 70 Figure 37. Integration Paths, Zn0-Ca0-Si02 System. ~7V 90 ZnO 75 - APPENDIX VI Determination of Zinc Oxide Acti v i t i e s , System ZnO-CaQ-FeO-SiO, A. Activity Coefficient Ratios Point NZnO Slag Assays N S i 0 2 NFeO NZnO Metal Assays I . 1 NCaO NFeO NZn N-, Fe aZn * (i3oo°C FeO 1 . 0 3 3 O203 . 3 8 0 . 3 8 3 1 1 . 5 2 . 0 7 1 . 0 9 8 . 0 1 1 0663 2 .036 . 2 0 4 . 3 7 2 . 3 8 6 1 0 . 3 3 . 0 7 6 . 1 0 4 . 0 1 2 . 6 4 7 3 . 0 6 8 o l 4 2 .394 . 3 9 4 5.79 . 1 2 5 . 0 9 1 o 0 2 3 5 . 7 1 0 4 .071 .144 . 3 8 3 .400 5.39 . 1 2 5 . 0 8 9 • . 0 2 3 5 ,663 5 . 0 9 3 . 0 7 9 .411 . 4 1 7 4.40 . 1 4 8 . 0 7 6 .030 . 7 0 2 6 . 0 9 5 5 .077 . 4 2 2 . 4 0 6 4.40 . 1 5 0 . 0 7 8 . 0 3 1 . 7 1 2 7 .023 . 2 7 2 .381 . 3 2 2 1 6 . 5 7 . 0 7 6 . 0 9 8 . 0 1 2 . 9 7 6 8 . 0 6 2 . 2 1 0 . 3 9 2 . 3 3 4 6 . 3 2 . 1 3 0 . 0 9 1 . 0 2 5 . 8 2 5 9 . 0 6 3 .178 . 4 0 1 . 3 5 8 6 . 3 8 . 1 1 7 . 0 7 9 . 0 2 1 5 . 7 1 5 1 0 . 0 6 4 „ 2 0 6 . 3 9 6 . 3 3 1 6 . 1 8 . 1 4 5 . 0 8 5 . 0 2 9 » 9 3 4 1 1 . 0 7 3 . 1 6 8 . 4 1 1 . 3 4 8 5-63 . 1 4 4 . 0 8 2 . 0 2 8 5 . 8 4 3 1 2 .077 o l 4 6 .437 . 3 3 8 5.67 . 1 4 5 . 0 9 0 . 0 2 9 . 8 5 6 13 . 0 8 7 . 1 4 8 . 4 2 5 . 3 3 8 4.88 . 1 5 0 . 0 8 6 . 0 3 0 5 . 7 7 8 14 . 0 9 0 0O89 .489 . 3 3 3 5.47 .137 . 0 7 7 . 0 2 7 .772 1 5 . 1 0 4 . 0 8 9 .473 . 3 3 4 4.55 . 1 5 3 . 0 8 2 . 0 3 1 . 7 3 6 1 6 . 0 3 1 . 2 4 0 . 5 1 7 . 2 0 6 1 6 . 3 8 . 0 9 3 . 0 8 3 . 0 1 5 5 1 . 3 2 6 17 . 0 5 2 . 2 4 6 .480 . 2 2 2 9.21 . 1 4 8 . 0 7 9 .030 1 . 4 4 1 1 8 . 0 6 3 . 2 6 0 . 4 5 7 . 2 2 0 7.23 . 1 6 1 . 0 7 6 . 0 3 3 5 1 . 2 6 3 1 9 .069 . 1 6 4 .566 . 2 0 0 8 . 2 4 . 1 2 7 . 0 8 0 0O24 1 . 0 3 4 2 0 . 0 7 7 . 2 0 1 . 5 1 1 . 2 1 0 6.69 . 1 4 9 . 0 7 6 .030 1 . 0 4 9 2 1 . 0 7 8 . 0 7 3 .645 . 2 0 6 8 . 2 7 . 1 2 7 , 1 0 0 . 0 2 4 1 . 0 3 4 2 2 . 0 8 0 . 1 5 1 .565 . 2 0 4 7.02 . 1 4 6 . 0 7 6 . 0 2 9 I.O65 2 3 . 0 8 1 . 0 7 8 . 6 3 6 . 2 0 5 7.84 . 1 2 3 . 0 9 5 . 0 2 3 . 9 4 0 2 4 . 0 8 3 5 . 1 3 8 . 5 5 2 . 2 2 8 6 . 7 3 . 1 4 6 . 0 7 4 . 0 2 9 1 . 0 1 8 2 5 . 0 8 4 5 .131 . 5 6 8 . 2 1 8 6 . 7 1 . 1 5 2 . 0 8 2 . 0 3 1 1 . 0 8 6 2 6 . 0 3 7 . 2 4 3 . 5 9 4 . 1 2 5 1 6 . 1 9 . 0 9 9 . 1 2 3 . 0 1 7 1 . 4 3 6 2 7 . 0 5 2 . 0 5 1 . 7 6 6 .131 14.68 . 1 2 0 . 1 0 3 . 0 2 2 5 1 . 7 2 3 28 . 0 5 2 . 0 8 9 . 7 3 5 . 1 2 4 14.22 . 1 2 0 . 1 0 2 . 0 2 2 5 1 . 6 7 0 2 9 . 0 5 9 . 0 6 1 . 7 5 3 . 1 2 6 1 2 . 6 8 . 1 2 0 . 1 0 7 . 0 2 2 5 I . 4 8 8 30 . 0 7 0 . 0 7 4 . 7 2 3 . 1 3 4 10.30 . 1 2 5 . 0 9 3 . 0 2 3 1 . 2 3 7 31 . 0 7 2 . 1 2 9 . 6 7 3 . 1 2 6 9-39 . 1 4 8 . 0 8 2 . 2 9 5 1.434 32 . 0 7 3 . 1 7 6 .620 . 1 3 2 8.49 . 1 4 6 . 0 7 9 . 0 2 9 1 . 2 8 4 33 . 0 7 4 . 1 8 8 . 6 0 3 . 1 3 6 8 . 0 9 . 1 5 2 . 0 7 9 . 0 3 1 1.310 34 . 0 7 5 .224 . 5 7 2 . 1 3 0 7.64 . 1 6 1 . 0 7 3 . 0 3 3 5 1 . 3 3 6 J -16- Appendix VI (continued) B. Calculation of Zinc Oxide Activities Point (see Part A) XZnO KPe01300°C * P e 0i3oo°c ? ZnO,» «^ o„ 1300 C a Z n 0l600°C 1 .663 .46 1.25 .83 .028 2 .647 .46 1.29 .83 .031 3 .710 .45 1.17 .84 .058 4 .663 .45 1.21 .79 .058 5 .702 .45 1.11 .78 .081 6 .712 .45 1.08 .78 .081 7 .976 .55 1.54 1.50 .032 8 .825 .525 1.42 1.17 .072 9 .715 .53 1.39 1.00 .063 10 .934 .525 1.40 1.30 .080 11 .843 .525 1.34 1.13 .081 12 .856 .525 1.24 1.06 .081 13 .778 .52 1.28 1.00 .087 14 .772 .53 1.10 .85 .078 15 .736 .52 1.13 .83 .089 16 1.326 .795 1.66 2.20 .061 17 1.441 .785 1.79 2.58 .118 18 1.263 .775 1.88 2.38 .130 19 1.034 .785 1.48 1.53 .099 20 1.049 .78 1.65 1.73 .123 21 1.034 .79 1.27 1.31 .096 22 1.065 .785 1.49 1.58 .118 23 .940 .79 l.?9 1.21 .095 24 1.018 .785 1.52 1.55 .121 25 1.086 .785 1.47 1.60 .125 26 1.436 .86 1.56 2.22 .072 27 1.723 .885 1.19 2.05 .095 28 1.670 .885 1.24 2.07 .095 29 1.488 .885 1.21 1.80 .097 30 1.237 .88 1.27 1.57 .102 31 1.434 .875 1.37 1.96 .127 32 1.284 .865 1.48 1.90 .128 33 1.310 .86 1.52 1.99 .132 34 1.336 .845 1.59 2.12 .141 Regular Solution Temperature Adjustment t Prom Auxiliary Ternary Systems

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