Thermodynamic Study of the Equilibrium Distribution of Platinum Group Metals Between Slag and Molten Metals and Slag and Copper Matte

Secondary materials, that contain relatively high concentrations of platinum group metals, (PGMs) are treated in copper smelting process. The PGMs lost in the slag is increasing with increasing quantities of scrap treated amount. To determine the portion of the PGMs chemically dissolved and that associated with the mechanically trapped matte in the slag will be a key factor to improve the recovery of those metals. An experimental study was carried out to determine the distribution of palladium between the FeO_x–SiO₂ slag and the liquid Cu₂S–FeS matte at 1573 K and a fixed partial pressure of SO₂ of 0.1 atm. It was found that the distribution ratios are around 10⁻³ for platinum and palladium. The distribution ratios show a tendency to increase when the grade of matte is increased above 60 mass% Cu. In addition, the solubility of platinum in FeO_x–SiO₂ slag equilibrated with a pure palladium and the Pd-Cu alloy was determined at 1573 K and the range of oxygen partial pressure from 10⁻⁹ to 10⁻⁷ atm. The solubility of palladium in the slag tends to increase with increasing oxygen partial pressure and activity of CuO_0.5 in the slag.