Additional recovery of gold from waste after processing of gold-containing ores of Kazakhstan

Abstract

The one of the important activities of gold mining industry is the involvement of refractory hard-to-enrich gold-containing raw materials into retreatment, as well as the tailings dams, which occupy huge areas and worsen the ecological state of the regions.The studies are aimed at re-extraction of gold out of technogenic raw materials possess not only scientific and practical, but also social and environmental significance. The pre-oxidation procedures are applied in the retreatment of raw materials, one of which is bio-oxidation of gold-containing raw materials method using A.Ferrooxidans bio-leaching solution.This method makes it possible to intensify the process of bio-oxidation extraction of gold from gold-containing raw materials due to the deeper development of sulphides. Therefore, the studies aimed at increasing the efficiency of gold re-extraction out of technogenic raw materials are of current interest. The results of researches regarding the extraction of gold out of stale tailings of gold extraction plant Altyntau Kokshetau using A.Ferrooxidans bio-leaching solution are performed in the article. The chemical, mineral and X-ray phase matter of sample was studied. It has been shown that the sample has a silicate base, represented by quartz, albite-anorthite mixture, muscovite and kaolinite.It has been found that the sample contains 8.49 g / t Au and 2.4 g / t Ag. The different leaching options were carried out: 1) re-grinding is followed by cyanidation; 2) cyanide leaching with preliminary sulfuric acid washing; 3) bio-oxidation using A.Ferrooxidans bacterial solution. It has been shown that the use of preliminary bio-oxidation makes it possible to increase the gold extraction. As a result, it was found that re-extraction of gold out of the stale tailings of sorption by two-stage leaching – bacterial opening of the raw materials, and then cyanidation are the most effective one.The best indicator of gold extraction in solutions as regards the first option resulted in 62.7% of gold, at the second option with the use of sodium chloride and the subsequent cyanidation was 79%, and at the third option of biochemical technology with sodium cyanide was 82.8% of gold.