Effect of agitation intensity on the biooxidation process of refractory gold ores by Acidithiobacillus ferrooxidans

Various views persist about the effect of the agitation intensity on the mineral biooxidation process, but the mechanism remains unclear. In this study, the effects of the agitation intensity on the biooxidation process of refractory gold ores by Acidithiobacillus ferrooxidans were investigated in experimental stirred tank bioreactors (STRs). The results demonstrated that both the biooxidation rates and the concentration of cells decreased with the agitation intensity. The higher agitation intensity not only damaged the suspended cells but also prevented the adsorption of cells onto the mineral surface. The oxygen uptake rate (OUR), the Fe2 + oxidation activity and the rus gene expression of A. ferrooxidans decreased with the agitation intensity during the biooxidation process, which might be responsible for the decrease of the biooxidation rates with the agitation intensity.