Agitation Leaching of Gold with Thiourea and Cyanidation Methods

Abstract

In this study, preliminary laboratory test work to identify the relative agitation leaching response to cyanidation and thiourea leaching of an oxidized ore have been carried out. The ore deposits of Neishaboor area with gold grade of 4 ppm are rich enough for studies. The characterization studies shows that, the ore is oxidized and gold is present partly in the form of solution in quartz veins as well as in the form of free particles in iron hydroxide specially hematite which is the product of pyrite oxidation. Quartz, hematite, calcite and feldspar are the main minerals present in the order of abundances. Sieve analysis and distribution of gold particles in different sieve fractions shows gold particles are distributed below 2000 μ. Based on characterization studies, the potential of an alternative lixiviant like thiourea and cyanide leach have been determined and found that under optimized conditions thiourea leaching of the ore performs (extraction of 96.7 % after 16 h) better than cyanide leaching (extraction of 47.3 % after 16 h).