Phase Equilibrium and Minor Elements Distribution between SiO<SUB>2</SUB>–CaO–FeO<I><SUB>x</SUB></I>–MgO Slag and Copper Matte at 1573 K under High Partial Pressures of SO<SUB>2</SUB>

Abstract

Phase equilibrium between copper matte and SiO 2 -CaO-FeO x -MgO slag with Q=0.35 (Q=mass%CaO/ (mass%CaO + mass%SiO 2 )) was investigated at 1573 K under the SO 2 partial pressures of 10.1, 50.7 and 101.3 kPa as a fundamental study for thermodynamically discussing oxygen-smelting processes to produce copper. The copper and sulfur solubilities in the slag were found to be independent of pso 2 when the matte grade was specified, and it was considered that this behavior was ascribed to the constancy of (p o2 /ps 2 ) against pso 2 at a given matte grade. When the distribution ratio of a minor element, X, between the slag and matte phases was defined as L s/m X =(mass%X in slag)/{mass%X in matte}, L( s/m X for As, Sb and Bi at a given matte grade increased with increasing pso 2 . This behavior was explained reasonably by assuming a mutual reaction between a metallic species in the matte and an oxidic species in the slag. The distribution ratio, L Ag s/m , at a given matte grade was almost constant against pso 2 . This was considered to be ascribed to the sulfidic species of AgS 0.5 prevailing in the matte phase and the constancy of (po 2 /Ps 2 ) against pso 2 .