Activities of Cu,Fe and Ni in Cu–Fe–Ni–S mattes

Abstract

The equilibrium distribution of Cu, Fe and Ni between Cu–Ni–Fe mattes and Pt alloy was examined as functions of the sulphur partial pressure (pS₂), oxygen partial pressure (pO₂), temperature and Fe content of the matte. The distribution ratios of Cu, Fe and Ni between matte and alloy were independent of oxygen pressure when the pS₂ was fixed at 2˙5 × 10⁻⁵ atm and pO₂ was varied between 10⁻¹⁵ atm and 10⁻¹² atm. The distribution ratio of Cu, Fe and Ni increased as the sulphur partial pressure increased. The Cu and Ni distribution ratios decreased with increasing temperature and the Fe distribution ratio increased slightly over the temperature range of 1350–1500°C. For mattes where the proportions of Cu and Ni were kept constant, the distribution ratio of Cu increased as the Fe content in the matte increased. The Fe and Ni distribution appeared to be independent of the iron content in the matte and had a value of 1·2 and 1·6, respectively. The activity of Cu, Fe, Ni in the matte was calculated using a regular solution model for solid Pt–Fe–Ni–Cu alloy. The activity coefficient of Cu, Fe and Ni decreased as pO₂ and pS₂ increased. The activity coefficients also appeared to be independent of the Fe content and temperature over the range of 36–54 wt% iron and 1350–1500°C, respectively.