Biooxidation pretreatment of low grade refractory gold tailings using a sulfur-oxidizing mixotrophic bacterium

Abstract

An inefficient gold leaching in the cyanidation process from refractory gold tailings was caused by gold particle locked in specific minerals. The aim of this study was to harness the ability of a sulfur-oxidizing bacterium to oxidize iron and sulfur and its behaviour on ferrous sulfate heptahydrate (FeSO4.7H2O) and pyrite (FeS2) as the medium in the biooxidation process for gold and silver extraction. The results showed that the gold extracted in ferrous sulfate medium was 20.48%, while that in pyrite medium tended to reduce from direct cyanidation to 14%. The silver extraction increased from 80.96% to 99.26% in ferrous sulfate medium and 91.30% in pyrite medium. This result indicated that ferrous sulfate heptahydrate was more suitable than pyrite, which resulted in the higher extraction of gold.