FSUE Central Research Geological Exploration Institute of Non-ferrous and Noble Metals (FGUP “TSNIGRI”)

G. V. Sedelnikova, Deputy Director, e-mail: gsedelnikova@mail.ru

E. E. Savari, Head of Laboratory

P. A. Zaulochniy, Researcher

E. A. Koshel, Senior Researcher

Biohydrometallurgical technology is used for recovery the ultra fine gold in sulfides, the main of its are arsenopyrite and pyrite. Bacterial leaching is used for sulfide oxidation of refractory gold ores and concentrates, then the gold extraction from biooxidation residues is going by cyanidation. The process of bacterial leaching of refractory gold gravity-flotation sulfide concentrates with high sulfide content 80–90% and pyrite:arsenopyrite ratio equals 3:1 and 7:1 was studied in this paper. Sulfide biooxidation was carried out with pneumomechanical stirring and aeration, temperature — 36–38 ^оC, pulp density — 17.6% using mixed bacteria Acidithiobacillus ferrooxidans, Acidithiobacillus thiooxidans, Sulfobacillus, Leptospirillum and Ferroplasma which previously proved effective to leach refractory pyrite-arsenopyrite concentrates. It was shown that microorganism adaptation to the composition of the concentrates required prior to bioleaching. According to results of analysis conducted for bacterial solutions and concentrate biooxidation residues, sulfide biooxidation rate depends on sulfide ratio. The concentrate with high pyrite:arsenopyrite ratio is much slower oxidized than the one with lower sulfide ratio though it contains twice as much arsenopyrite. Refractory nature of the concentrate is determined by high pyrite, not arsenopyrite, content. The use of mixed bacteria ensured high degree of sulfide oxidation. Gold recovery from biooxidation residues after their aeration and cyanidation was 86.1% for concentrate with high pyrite : arsenopyrite ratio and 96.7% for concent rate with lower sulfide ratio.

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5. Zaulochny P. A., Sedelnikova G. V., Savari E. E., Kim D. H., Pivovarova T. A. Kinetic dependence of refractory gold sulphide biooxidation using different microorganism association. Proc. XXV International Mineral Processing Congress. Australia, Brisbane, 2010. рр. 527–536.

6. Sedelnikova G. V., Savari E. E., Kim D. H., Zaulochny P. A., Pivovarova T. A. Biohydrometallurgical gold extraction from carbonaceous pyrite-arsenopyrite concentrate by the microorganisms including moderate termophilic. Proc. XXIV International Mineral Processing Congress. China, Beijing, 2008. pp. 2846–2853.

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