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Biooxidation of an auriargentiferous arsenical pyrite concentrate by means of mesophilic and thermophilic bacteria

Minerals & Metallurgical Processing , 2010, Vol. 27, No. 4, pp. 212-218

Pecina, E.T.; Castillo, P.; Martinez, D.; Orrantia, E.


 Bioleaching is a viable option for the processing of auriargentiferous refractory ores with high arsenic content. The application of mesophilic (A. ferrooxidans and “L. ferrooxidans”) and thermophilic bacteria of the genus Sulfolobus (S. solfataricus and S. acidocaldarius) as oxidant treatment before the cyanidation of an industrial arsenical pyrite concentrate is presented. The results show that extraction of gold and silver increases due to biooxidation caused by mesophilic bacteria and results in a maximum gold recovery of 68%. In all strains studied, biooxidation resulted in an average silver recovery of 50%. The results showed that all evaluated strains were sensitive to solids content (5 to 20%) and average particle size (75 and 38 μm) of the concentrate.