Equilibrations of copper matte and fayalite slag under controlled partial pressures of SO2

Equilibrium distributions of Cu, S and O between silica saturated fayalite slags and copper mattes (25 to 79 pct Cu) have been examined experimentally under controlled partial pressures of SO₂. The temperature range of the experiments was 1423 to 1573 K and pSO₂ was varied between 0.1 and 1 atm. Concentrations of copper in the experimental slags were found to be low (<1 pct Cu) under these conditions, as long as the grade of the coexistent matte was below 60 pct copper. Copper in slag concentration rose dramatically, however, when matte grade was increased above this level. The work also showed that whereas FeS has a high solubility for oxygen and is itself soluble in slag under oxidizing conditions, Cu₂S and slag are almost completely immiscible. Cu-Fe-S mattes behave in an intermediate manner. Formerly graduate student with the Department of Mining and Metallurgical Engineering, McGill University.