Thermodynamics of Copper Matte Converting: Part II. Distribution of Au, Ag, Pb, Zn, Ni, Se, Te, Bi, Sb and As Between Copper, Matte and Slag in the Noranda Process

Abstract

The solubility of minor elements in fayalitic slags was assessed thermodynamically assuming exclusively oxidic dissolution for Pb, Zn and Ni, metallic dissolution for Au and Ag, molecular and monatomic dissolution for Se and Te, and monatomic dissolution for Bi, Sb and As. Based on these assumptions as well as the thermochemical data in the literature, an analytical method was developed to calculate the distribution equilibria of minor elements between copper, matte and slag phases. As an example of the application, the method was demonstrated for the analysis of behavior of minor elements in the Noranda Process producing metallic copper or high grade matte. The distribution of minor elements was expressed in terms of concentration ratios of an element for copper/matte, copper/slag and matte/slag phases. Using the concentration ratios and also formulae compensating for mechanical suspension, apparent distribution coefficients of the minor elements in the actual process were calculated as a function of the process parameters: temperature, partial pressure of SO2, magnetite activity and matte grade. An excellent agreement was observed between the calculated and observed data, thus providing logical basis for interpreting operating data of the Noranda Process. The behavior of minor elements under various operating conditions can also be predicted by the present model.