IMPROVEMENT TO SILVER AND GOLD LEACHING METHOD WITH THIOUREA SOLUTIONS

摘要

The invention relates to an improvement to the silver and gold leaching method with thiourea solutions, which is intended for use in the mining and mineral-processing industry. More specifically, the invention relates to a solution composition which enables the use of thiourea. In particular, the invention relates to a method of forming a solution, which improves both (i) the speed of extracting silver and gold from minerals and other materials containing same, thereby improving the stability of the thiourea in the lixiviant solution, and (ii) the direct electrorecovery of the metals from said solution. The invention makes use of a leaching solution which is subjected to prior or simultaneous controlled electrooxidation in order to produce formamidine disulphide (FADS) which acts as an oxidising agent for the mineral phases containing gold and silver. In the preferred embodiment of the invention, the FADS forms in a proportion of between 10 and 30 % of the total thiourea contained in the solution and the electrodeposition of the metals is performed in the same cell (cathodic compartment) as that in which the FADS forms (anodic compartment).