Thiourea is unstable in alkaline solution and is easily decomposed into sulfide and cyanamide. But thiourea is relatively stable in acidic medium. Therefore, considering the stability of thiourea, the dilute sulfuric acid solution of thiourea is used as the leaching agent when extracting gold with thiourea, and attention should be paid to adding acid before adding thiourea, so as to avoid the failure of thiourea hydrolysis due to the local temperature of the pulp being too high. Thiourea is a special gold reducing agent.
Gold extraction by thiourea method is a new low-toxic gold extraction process that is being perfected day by day. The leaching of gold in thiourea acid solution has the characteristics of high leaching speed, low toxicity, easy regeneration and recovery of chemicals, and small harmful effects of copper, arsenic, antimony, carbon, lead, zinc, sulfur, etc. Gold is extracted from gold-bearing mineral raw materials.