Experimental study and thermodynamic modeling of distribution of elements among slag, matte and metal in the Cu–Fe–O–S–Si–(Zn)–(Al, Ca, Mg) system for copper slag cleaning applications

Abstract

The distributions of zinc and other elements in the Cu–Fe–S–Si–O–(Zn) system among slag, matte and metal phases were determined experimentally at 1200 °C (1473 K). The experimental procedure involved high-temperature equilibration, quenching of the samples and measurement of the phase compositions using the electron probe X-ray microanalysis. Conditions of experiments were planned using thermodynamic calculations and the experimental results were used to further develop thermodynamic models. Matte grades from 0 to 80 wt. pct Cu were investigated, concentrations of 3, 6 and 8 wt. pct Zn in slag were targeted. Additional set of experiments was undertaken to study the effects of Al2O3, CaO and MgO on the distribution of zinc and other elements. All samples were in equilibrium with tridymite (SiO2). Metal phase was either liquid copper or solid metallic iron. Conditions of equilibrium with metal phase are of practical importance for the development of smelting reduction technologies for the copper slag cleaning and recycling.