Experimental Investigation and Thermodynamic Modeling of the Distributions of Ag and Au Between Slag, Matte, and Metal in the Cu–Fe–O–S–Si System

Abstract

To assist in improving the recoveries of gold and silver in both primary production and metals’ recycling, the distributions of Ag and Au between slag, matte, and metal in the Cu–Fe–O–S–Si system have been investigated using an integrated experimental and thermodynamic modeling approach. The experimental technique involved high-temperature equilibration at selected temperatures and gas atmospheres, and rapid quenching followed up by measurement of phase compositions using microanalysis techniques. Electron probe X-ray microanalysis was used to measure the major element concentrations in the condensed phases. The laser ablation inductively coupled plasma mass spectrum technique was used to measure the concentrations of Ag and Au in slag. The experimentally determined distribution coefficient of Ag between matte and slag decreases with the increasing matte grade below approximately 70% Cu, but then increases with the increasing matte grade between 70 and 80% Cu. The experimentally determined distribution coefficient of Au between matte and slag decrease from log L = − 2.8 for approximately 63% Cu to approximately log L = − 3.8 at 76% Cu. Thermodynamic model parameters describing Ag and Au distributions have been derived following consideration of available data on slag/matte, slag/metal, and slag/matte/metal systems.