Comparative Studies on Gold Extraction from Ores Using Cyanide and Thiourea

Studies were conducted on gold extraction from ore of a deposit in Tajikistan using cyanide and thiourea. Thiourea leaching was found to involve decomposition of the solvent, which increased its consumption and caused passivation of the gold surface by elemental sulfur, leading to a low extraction rate. The decrease in gold extraction with increasing thiourea leaching time was attributed to resorption of the gold complex by sorption-active minerals. Cyanidation achieved 98.1% gold recovery, whereas thiourea leaching gave 78.1%.