Phase equilibrium and minor element distribution between FeO x -SiO2-MgO-based slag and Cu2S-FeS matte at 1573 K under high partial pressures of SO2

Abstract

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 SiO2-saturated 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 \(p_{SO_2 } \) when the matte grade was specified, and this behavior was ascribed to the constancy of \(\left( {{{p_{O_2 } } \mathord{\left/ {\vphantom {{p_{O_2 } } {p_{S_2 } }}} \right. \kern-\nulldelimiterspace} {p_{S_2 } }}} \right)\) against \(p_{SO_2 } \) at a given matte grade. When the distribution ratio of a minor element (X) between the slag and matte phases was defined as Lxs/m=(wt pct X in slag)/{wt pct X in matter}, Lxs/m for arsenic, antimony, and bismuth at a given matte grade increased with increasing \(p_{SO_2 } \). On the other hand, the distribution ratio of silver at a given matte grade was almost constant against \(p_{SO_2 } \).