The role of Acidithiobacillus ferrooxidans in Fe(II) oxidation of pyrite in bioleaching processes

Abstract BACKGROUND Microbial leaching is an emerging ore extraction technology, especially for low‐grade ores. In sulfide and oxide ore bioleaching systems, Acidithiobacillus ferrooxidans is becoming a widely applied microorganism for mineral processing. Many studies are currently focusing on the vital role of A. ferrooxidans in facilitating the efficiencies of sulfur and iron species transformation for sulfide ore bioleaching. Existing research usually investigates the composite action of A. ferrooxidans and Fe(III) for ore bioleaching, the effect of A. ferrooxidans alone being investigated to a lesser extent. An important effect is the role of A. ferrooxidans in the oxidative conversion of Fe(II) in pyrite bioleaching. RESULTS The oxidative dissolution of pyrite in an imitated A. ferrooxidansbioleaching system was investigated in this work, particularly concerning the effects of bacteria on Fe(II) oxidation of the pyrite. Results of the dissolution performance test, cyclic voltammetry and polarization analysis indicated that the preceding oxidation of Fe(II) has control over the pyrite dissolution rate in the imitated bioleaching system. The semiconductor properties and carrier density of the passivation films of pyrite formed under a variety of conditions indicated that the oxidative leaching of ferrous disulfide is subject to the movement of the holes of the Fe 2+ species and the oxygen vacancy of H 2 O at the interface. Acidithiobacillus ferrooxidans promotes pyrite bioleaching by accelerating the preferential oxidation of Fe(II) caused by movement of the electron hole of Fe 2+ to H 2 O at the solid–liquid interface. COCLUSION The oxidation process of pyrite in this study turns out to involve hole movement. © 2022 Society of Chemical Industry (SCI).