Bioleaching of copper, zinc and gold from a polymetallic ore flotation concentrate from the Coka Marin deposit (Serbia)

Abstract

The aim of this study was to investigate the possibility of applying Acidithiobacillus sp. B2 to copper, zinc and gold recovery from a polymetallic ore flotation concentrate. The study was designed in two phases. The first phase was a classic biooxidation process in which the microorganisms oxidize sulfides, leaching copper and zinc while simultaneously concentrating gold in the ore. In the second phase, after elimination of the sulfide substrate, the rate of gold leaching by potassium cyanide was analyzed. The leaching was conducted using the shake flask testing technique during a period of 28 days at a temperature of 28 ?C. The percentage of copper and zinc leached at the end of this study was 37.63 % and 47.95 % respectively. The results obtained indicated 6- and 13-fold (for copper and zinc, respectively) higher metal leaching efficiency in the suspension with iron-oxidizing Acidithiobacillussp. B2 than in the control suspension. In the next phase of the study, after elimination of the sulfide substrate, gold was extracted with potassium cyanide from the remaining polymetallic ore concentrate. The results obtained showed that the efficiency of the gold extraction process was 80 %. According to the available data, this is the first study of the microbiological leaching of copper, zinc and gold from a polymetallic ore flotation concentrate from the Coka Marin deposit (Serbia).