Phase Equilibrium and Minor Element Distribution between FeOX-SiO2-MgO-Based Slag and Cu2S-FeS Matte at 1573 K under High Partial Pressures of SO2

As part of a fundamental study of copper smelting processes using oxygen or oxygen-enriched air as a blowing gas, phase equilibrium and distribution of minor elements between copper matte and SiO2saturated FeOX-SiO2-MgO-based slag containing 5 to 10 wt pct MgO have been investigated at 1573 K under the SO2 partial pressures of 10.1, 50.7, and 101.3 kPa. The copper and sulfur solubilities in the slag were found to be independent of pSO2 when the matte grade was specified, and this behavior was ascribed to the constancy of (pO2/pS2) against pSO2 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)= (wt pct X in slag)/{wt pct X in matter}, L^s\m(x) for arsenic, antimony, and bismuth at a given matte grade increased with increasing pSO2. On the other hand, the distribution ratio of silver at a given matte grade was almost constant against pSO2.