Influence of Oxidation-Reduction Potential on Bio-Oxidation of Olimpiada Flotation Concentrate with High Content of Pyrrhotite

The main sulphidic minerals, contained in the Olimpiada flotation concentrate, are pyrrhotite, arsenopyrite, pyrite and antimonite. Biooxidation of these minerals occurs in the following sequence: Pyrrhotite → Arsenopyrite → Pyrite → Antimonite. Oxidation of pyrrhotite requires acid consumption, oxidation of pyrite is followed by formation of sulphuric acid. The oxidation rate of pyrrhotite is higher and due to this, acid balance of the whole biooxidation process is shifted to the consuming side, and it is required to add acid to the process. The research work has demonstrated, that by regulating oxidation-reduction potential it is possible to reduce pyrrhotite oxidation rate and intensify pyrite oxidation rate; this allows to reduce consumption of sulphuric acid, reduce heating of the slurry inside the reactors and as a result maintain the stable process.