PHASE-EQUILIBRIUM AND MINOR ELEMENTS DISTRIBUTION BETWEEN SIO2-CAO-FEOX-MGO SLAG AND COPPER MATTE AT 1573 K UNDER HIGH PARTIAL PRESSURES OFSO2

Phase equilibrium between copper matte and SiO2-CaO-FeOx-MgO slag with Q=0.35 (Q=mass%CaO/(mass%CaO+mass%SiO2)) was investigated at 1573 K u nder the SO2 partial pressures of 10.1, 50.7 and 101.3 kPa as a fundam ental study for thermodynamically discussing oxygen-smelting processes to produce copper. The copper and sulfur solubilities in the slag wer e found to be independent of p(SO2) when the matte grade was specified , and it was considered that this behavior was ascribed to the constan cy of (p(O2)/p(S2)) against p(SO2) at a given matte grade. When the di stribution ratio of a minor element, X, between the slag and matte pha ses was defined as L-x(s/m)=(mass%X in slag)/{mass%X in matte}, L-x(s/ m) for As, Sb and Bi at a given matte grade increased with increasing p(SO2). This behavior was explained reasonably by assuming a mutual re action between a metallic species in the matte and an oxidic species i n the slag. The distribution ratio, L-Ag(s/m), at a given matte grade was almost constant against p(SO2). This was considered to be ascribed to the sulfidic species of AgS0.5 prevailing in the matte phase and t he constancy of (p(O2)/p(S2)) against p(SO2).