Pressure oxidation of a copper-rich pyritic gold concentrate

In this study, the acid pretreatment and pressure oxidation of a refractory copper-rich (0.3% Cu) pyritic gold concentrate (62 g/t Au, 110 g/t Ag, 19.3% pyritic S2-) prior to cyanide leaching was investigated. The effect of parameters i.e., temperature (180-220°C), oxygen pressure (pO2=5-10 bar), retention time (0.5-2 h) and acid concentration (20-50 g/L H2SO4) was examined on the removal of copper, pyritic sulphur oxidation and extraction of gold in the subsequent cyanide leaching. The increased levels of the parameters improved the gold extraction. The highest gold extraction (97.4%) in cyanide leaching was achieved by the pre-treatment of the concentrate i.e., acid washing (50 g/L H2SO4) followed by pressure oxidation under the conditions of 50 g/L H2SO4, 220°C, 10 bar and 1 h. The findings demonstrated that high gold recoveries in cyanide leaching can be achieved after pressure oxidation of the concentrate. © 2021 Union of Chambers of Engineers and Architects of Turkey. All rights reserved.