MINOR ELEMENTS DISTRIBUTION BETWEEN IRON-SILICATE BASE SLAG AND NI3S2-FES MATTE UNDER HIGH PARTIAL PRESSURES OF SO2

As a fundamental study to elucidate the behavior of several minor elem ents in the oxygen-smelting process of nickel sulfide ore, equilibrium distributions of Cu, Ag, Co, As, Sb and Bi between the iron-silicate base slag with saturated silica and Ni3S2-FeS matte phases in a magnes ia crucible were investigated at 1573 K under controlled partial press ures of S-2, O-2 and SO2 with 10.1, 50.7 and 101.3 kPa. The distributi on ratio of X, L-X(s/m), defined as (mass%X in slag)/ (mass%X in matte ), were plotted in relation to the nickel content in the matte (matte grade) and compared with the available data. At a fixed p(SO2), the di stribution ratios of Cu, Co, As and Sb increase slightly with increasi ng matte grade, and in the cases of Ag and Bi, L-X(s/m) decrease with increasing matte grade up to about 45 mass%Ni and then increase in the higher range. When the matte grade is specified, the distribution rat ios of Co, As, Sb and Bi increase with increasing p(SO2) while L-Cu(s/ m) and L-Ag(s/m) are almost independent of p(SO2). The Raoultian activ ity coefficients of either metallic or sulfide species of the minor el ements in the matte phase were derived, based on a thermodynamic analy sis of the experimental distribution data. The sulfide species of coba lt in the matte was estimated to be CoS2/3.