|About this Abstract
||Part C-1: Hydrometallurgy 2018
||Selection of microorganism for the bio-oxidation of a refractory gold-concentrate with focus on the behaviour of antimony sulphides.
||Liliane Carvalho, Suzimara Silva, Romeu Giardini, Lucas S. Magalhaes, Michael Rodrigues, Versiane A. Lećo
|On-Site Speaker (Planned)
||Versiane A. Lećo
In the current study, bio-oxidation tests were carried out in shaking flasks with a flotation concentrate containing the sulphides pyrite, arsenopyrite and gudmidite. The tests were performed with mesophilic microorganisms (At. ferrooxidans) at 30°C and also with the moderate thermophile S. thermosulfidooxidans, at 50°C. The effects of (i) previous adaptation of the microorganisms to the concentrate, (ii) ferrous iron concentration and (iii) pulp density (2%, 4% and 6% (w/v)) on the dissolution of the sulphide were studied through arsenic extractions. S. thermosulfidooxidans was more sensitive to the pulp density in comparison to At. ferrooxidans as a reduction in sulphide oxidation was observed with the increase in the solid content to 6%. Therefore, the mesophilic strain was selected for further work, which comprised a rolling bottle experiment at 10% solids. After 40 days of bio-oxidation, the solid material was subjected to cyanidation, which revealed 85% gold extraction as compared to 21% from the original concentrate. The antimony sulphide grains in the bio-oxidized product showed similarity to what was observed in the original sample, suggesting such particles were not susceptible to the bio-oxidation process.
||Planned: At-meeting proceedings