Thermodynamic premises of fire refining of blister copper considering the interaction parameters of the melt

The process of fire refining of copper is based on the removal of impurities that have a high affinity for oxygen through their oxidation by gaseous oxygen. Since the main component of blister copper is copper itself, according to the law of mass action and its affinity for oxygen, during air blowing the metal primarily reacts with the oxygen in the blast. The resulting copper (I) oxide is transported from the zone of direct contact with gaseous oxygen into the region of lower oxygen concentration, where the oxidation of impurities (Mei) occurs. In practice, the actual copper melt deviates from ideal behavior; therefore, it is necessary to consider the activities of the components and the interaction parameters of the system when evaluating the thermodynamic premises of fire refining. It is known that the oxygen activity in copper melts depends on the oxygen affinity of the impurities. Impurities with a high affinity for oxygen (e.g., Al, Si, Mn) significantly reduce the oxygen activity, whereas those with a lower affinity (e.g., Zn, Fe, Sn, Co, Pb) only partially decrease it. Thermodynamic calculations were performed to estimate the final concentration of impurities in the copper melt and to theoretically evaluate the influence of impurities on oxygen activity in blister and anode copper. The calculations showed that fire refining of copper by air blowing under a weighted ideal slag has thermodynamic limitations. The final impurity concentration depends on both the oxygen activity in the melt and the activity of the impurity oxide in the slag. A decrease in the impurity oxide activity in the slag enhances refining efficiency by shifting the oxidation reaction equilibrium toward the reaction products. The theoretical effect of impurities on the oxygen activity in copper is substantiated for two melts differing in chemical compositin.

1. Zhukov V.P., Skopov G.V., Kholod S.I., Bulatov K.V. Pyrometallurgy of copper. Moscow: IP Ar Media, 2023. Book 2. 324 p. (In Russ.).

2. Davenport W.G., King M., Schlesinger M., Biswas A.K. Extractive metallurgy of copper. 4th ed. Oxford: Elsever Sci. Ltd., 2002. 432 p.

3. Kozhanov V.A., Savenkov Yu.D., Shpakovsky V.A., Shutov I.V. Thermodynamic prerequisites for precision fire refining of copper from scrap and waste. In: Scientific works of Donetsk National Technical University. Donetsk: DNTU, 2012. P. 494–499. https://uas.su/conferences/2010/50let/55/00055.php,30.04.2025

4. Biswas A.K., Davenport W.G. Extractive metallurgy of copper. Oxford: Pergamon Press., 1996.

5. Gerlach J., Herfort P. The rate of oxyden uptake by molten copper. Metall. 1968;22(11):1068—1090.

6. Gerlach J., Schneider N., Wuth W. Oxyden absorption during blowing of molten Cu. Metall. 1972;25(11):1246—1251.

7. Frohne O., Rottmann G., Wuth W. Processing speeds in the pyrometallurgical refining of Cu by the top-blowing process. Metall. 1973;27(11):1112—1117.

8. Zhukov V.P., Mastyugin S.A., Khydyakov I.F. Absorption of oxyden by molten copper during top blowing with steam — air mixtures. Soviet Journal of Non-Ferrous Metals. 1986;14(5):371—375

9. Aglitsky V.A. Copper refining. Moscow: Metallurgiya, 1971. 184 p. (In Russ.).

10. Safarov D.D. Kinetics of oxidation of copper-based alloys by a gas phase of variable composition: Diss. Cand. Sci. (Chem.). Sverdlovsk: IMET UrO RAS, 1983. (In Russ.).

11. Belousov A.A., Pastukhov E.A., Aleshina S.N. Effect of temperature, partial pressure of oxygen on the kinetics of oxidation of liquid copper. Melts. 2003;(2):3—6. (In Russ.).

12. Martin T., Utigard T. The kinetigs and mechanism of molten copper oxidation by top blowing of oxygen. Journal of Metals. 2005;(2):58—62.

13. Belousov V.V., Klimashin A.A. High-temperature oxidation of copper. Uspekhii Khimii. 2013;(3):3—6. (In Russ.).

14. Barton R.G., Вrimасоmbе J.K. Influence of surface tensiоn-drivеn flоw оf the kinetics of охуgеn absorption in molten copper. Metallurgical Transactions B. 1977;8:417—427.

15. Lyamkin S.A., Tanutrov I.N., Sviridova M.N. Kinetics of oxidation of molten copper by gas phase oxygen. Melts. 2013;(2):83—89. (In Russ.).

16. Avetisyan A.A., Chatilyan A.A., Kharatyan S.L. Kinetic features of the initial stages of high-temperature oxidation of copper. Chemical Journal of Armenia. 2013;66(3):407—415. (In Russ.).

17. Kumar H., Kumagai S., Kameda T., Saito Y., Takahashi K., Hayashi H., Yoshioka T. Highly efficient recovery of high-purity Cu, PVC, and phthalate plasticizer from waste wire harnesses through PVC swelling and rod milling. Reaction Chemistry & Engineering. 2020;5(9):1805—1813. https://doi.org/10.1039/D0RE00303D

18. Lee B.J. Revision of thermodynamic description of Fe—Cr and Fe—Ni liquid phases. Calphad. 1993;17(3): 251—268. https://doi.org/10.1016/0364-5916(93)90004-u

19. Kubaschewski O., Geider K.H., Hack K. The thermochemical properties of iron-nickel alloys. Zeitschrift für Metallkunde. 1977;68(5):337—341.

20. Conard B.R., McAneney T.B., Sridhar R. Thermodynamics of iron-nickel alloys by mass-spectrometry. Metallurgical and Materials Transactions. 1978;9:463—468.

21. Fernandez Guillermet A. Assesment of the thermodynamic properties of the Ni—Co system. Zeitschrift für Metallkunde. 1987;78(9):639—640.

22. Jakob K.T., Fitzner K. This estimation of the thermodynamic properties of ternary alloys from binary data using the shortest distance composition path. Thermochim. Acta. 1977;18(2):197—206. https://doi.org/10.1016/0040-6031(77)80019-1

23. Fujita Y., Pagador R.U., Hino M., Azakami T. Thermodynamic investigation on molten Cu—Ni—Fe alloys by the double knudsen cell-mass spectrometer system. Journal of the Japan Institute of Metals and Materials. 1997;61(7):619—624. https://doi.org/10.2320/jinstmet1952.61.7_619

24. Tomiska J.Z. Ternary thermodynamics by computer-aided Knudsen cell mass spectrometry: Fee solid Fe—Ni—Co alloys. Zeitschrift für Metallkunde. 2004;95(3):136—141. https://doi.org/10.3139/146.017926

25. Tsymbulov L.B., Kolosova E.Yu., Tsemekhman L.Sh. Determination of the activities of components in metal melts containing Cu, Ni, Co, Fe, using calculation methods. Non-Ferrous Metals. 2011;(3):28—36. (In Russ.).