Thermodynamics of Copper Matte Converting: Part II. Distribution of Au, Ag, Pb, Zn, Ni, Se, Te, Bi, Sb and As Between Co
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IT is often said that steelmaking is a technique of slag-making, meaning that a quality steel results from a good control of the slag. This apparent paradox may be paraphrased for copper smelting by stating that copper-making is a technique of minor element control; a quality copper results from a controlled elimination of minor elements in the course of smelting and electrorefining. This is due to the mineralogical nature of sulfide concentrates which are normally accompanied with a number of minor elements such as Au, Ag (noble metals), Co, Ni, Pt, Pd (Group VIII), Zn, Cd, Hg (Group II-B), Sn, Pb (Group IV-A), Mo (Group VI-B), Bi, Sb, As (Group V-A), se, Te (chalcogens) and Cl (halogen) in addition to the gangue. Recently, additional importance has been given to the control of minor elements in copper smelting from the viewpoint of environmental protection. Reverberatory and blast furnace copper smelting processes have been highly perfected over many decades with respect to minor element control. These processes thus provide a high recovery of valuable byproducts such as Au, Ag, Se and Te to copper, while assuring an excellent elimination of detrimental elements such as Zn, Pb, Sn, Bi, Sb and As. When another copper smelting process is conceived, it is therefore essential to investigate and establish the behavior of minor elements in regard to their effects on the quality of the copper produced as well as their impact on economical and environmental factors. The reported M. NAGAMORI, formerly with Noranda Research Centre, Pointe Claire, Quebec, is presently with Centre de Recherche industrielle du Quebec, Ste-Foy , Quebec GIV 4C7, Canada, and P. J. MACKEY is Smelter Technical Superintendent, Noranda Mines Limited, Noranda, Quebec J9X SB6, Canada. Manuscript submitted December 23, 1977. METALLURGICAL TRANSACTIONS B
behavior l - 3 of minor elements for some other commercial processes is different from that in reverberatory or blast furnace smelting. The present study is a thermodynamic treatment of the problem to understand better and eventually predict the behavior of the minor elements as a function of process variables, thereby providing a theoretical basis for improved metallurgical control. The present thermodynamic model can be used in the analysis of any matte smelting process dealing with high grade mattes (or low iron mattes), insofar as the condensed phases are close to the equilibrium conditions and the partial pressures of sulfur and oxygen over the system are known. A thermodynamic analysis of the basic reactions in the Noranda Process producing copper or matte" has indicated the excellent agreement between the calculated and observed data as to the chemical composition of various phases. This supports the view that the actual Noranda Process operates very close to equilibrium. Values of sulfur and oxygen partial pressures have also been calculated for various operating modes of the process as a function of controllable process variables. Accordingly, in the behavior analysis of certain elements for w
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