Research on chlorination leaching of pressure-oxidized refractory gold concentrate

Abstract

The chlorination leaching of gold, one of the non-cyanide methods, has the advantages of higher reaction rate, less pollution, simple process, and low cost compared with the cyanide leaching. In this work, the hydro-leaching method consisting of the pressure oxidation pretreatment and chlorination leaching has conducted for the refractory gold concentrate with high sulfur content. XRD and SEM/EDC were used to characterize the refractory gold concentrate and the pretreated gold concentrate. Based on the thermodynamic studies for the gold leaching reactions and investigations for changes in redox potential during the leaching process, the influences of various factors on the percent leached have considered in this experiment. As a result, the optimum conditions of the chlorination leaching for the refractory gold concentrate pretreated by pressure oxidation are as follows: 4 of pH, above 1.0 V of the redox potential, 75 g/L of the NaCl concentration, 40 °C of the reaction temperature, 3:1 of the liquid-solid ratio and 2 h of the leaching time. Under these conditions, the percent leached of gold is 96.54%.