Gold Extraction from Oxide Ore using Copper Ethylenediamine Thiosulfate

Abstract

Thiosulfate leaching is considered a green gold extraction approach and a gold mine in Laos was subjected to such treatment in this study. A single factor test was undertaken to determine the optimal leaching conditions, leading to the following parameters: thiosulfate concentration of 0.2 mol L^–1; copper ion concentration of 0.005 mol L^–1; ethylenediamine concentration of 0.01 mol L^–1; pH value of 10; leaching time of 4 h; stirring speed of 200 rpm. After leaching, the remaining ion concentrations were relatively low, positively affecting gold recovery. To further enhance the leaching rate, the impact of cetyltriethylammonium bromide (CTAB) on the leaching rate of gold was investigated, revealing that the addition of CTAB can increase gold’s leaching rate while reducing thiosulfate consumption. In conclusion, a comparison was made between thiosulfate and cyanide leaching, where copper-ethylenediamine-thiosulfate leaching exhibited a shorter duration compared to cyanidation, establishing its potential as a more environmentally sustainable approach.