Kinetics and mechanism of the bacterial and ferric sulphate oxidation of galena

Abstract

The bacterial oxidation of galena (PbS) has been studied, largely due to its relevance to the bioleaching of sphalerite (ZnS) and other sulphide minerals. Ferric sulphate oxidation experiments were first conducted as an analog to the indirect biooxidation mechanism, and the process was found to be diffusion-controlled due to the presence of a product layer. The bacterial oxidation of galena by a mixed culture of iron- and sulphur-oxidising bacterium was found to proceed according to a diffusion-controlled indirect mechanism, in which the primary role of the bacteria is the re-generation of ferric iron. Using quantitative XRD analysis, it was demonstrated that the oxidation product layer cons..