Effect of Organic Nutrients and Elevated Temperature on Bioleaching of Sulfide Copper Concentrate

Abstract

The goal of the work was to study the effect of addition of organic carbon source required for microorganisms oxidizing sulfide minerals in the nutrient medium on the rate of copper concentrate bioleaching. The concentrate containing 31.6% Fe, 19.2% Cu, and 2.9% Zn was bioleached in a batch mode for 30 days using mixed culture of acidophilic microorganisms. In the first reactor, biooxidation was performed at 45°C without additional carbon sources. In the second and in the third reactors, biooxidation was performed at 45°C and 55°C and nutrient medium was supplemented with 0.02% of yeast extract. Biooxidation without yeast extract allowed extracting 47 and 92% of copper and zinc. During biooxidation at 45°C using the medium supplemented with yeast extract, 54 and 94% of copper and zinc were extracted. During bioleaching at 55°C, 48% and 84% of copper and zinc were extracted. Thus, yeast extract allowed increasing copper bioleaching rate at 45°C, but temperature increase up to 55°C led to decrease in bioleaching efficiency. It may be explained by the fact that yeast extract increased activity of acidophilic microorganisms, which may consume organic carbon sources, while high temperature may inhibit some microorganisms and, therefore, does not allow increasing bioleaching rate.