PS helps Murdoch University scientists to demonstrate the role of sessile bacteria in pyrite bio-oxidation.

• The oxidation of pyrite and other mineral sulphites is often necessary as a pre-treatment for the refractory ores before metals of value can be released from the mineral matrix. The bio-oxidation mechanisms are complex and not fully understood. Of particular interest is the role played by planktonic, freely suspended cells compared with that of sessile cells absorbed to the mineral surface.


• A Murdoch University research team has demonstrated the importance of the sessile cells in the bio-oxidation of pyrite by examining the surface and sub-surface products and structures produced by the action of lithotrophic (rock digesting) bacteria colonising a pyrite surface.


• Collected XPS data from a Kratos Axis Ultra spectrometer helped to identify the concentration of sulphur, oxygen and carbon from the surface of each sample.


• The researchers demonstrated the ability of cells in a surface film to provide the reactants and mass transport to the pyrite surface. This suggests that improvements in process concentration and rate may be found by maximising sessile populations and improving the selective formation of bio-films on desired surfaces.

Techniques: XPS and SEM (scanning electron microscopy).

Source: Blight K., Ralph D. E. & Thurgate S.; (2000); "Pyrite Surfaces after Bio-Leaching: A Mechanism for Bio-Oxidation"; Hydrometallurgy, Vol 58, Issue 3; pp. 227-237