The contribution of direct and indirect actions in bioleaching of pentlandite

The mechanisms of bioleaching of pentlandite by mesophilic Acidithiobacillus ferrooxidans and thermophilic MLY were investigated. The experimental results showed that the mechanisms were different when pentlandite was bioleached by the two bacteria. It was found that the direct action of the attached bacteria was more important than indirect action of the free cells in the solution during the A. ferrooxidans leaching of pentlandite, and that only the indirect action was significant during the MLY leaching of pentlandite.