Winogradsky Institute of Microbiology, Research Center of Biotechnology of the Russian Academy of Sciences (Moscow, Russia):

Bulaev A. G., Head of Laboratory, Leading Researcher, Candidate of Biological Sciences, bulaev.inmi@yandex.ru

Saint Petersburg Mining University (Saint Petersburg, Russia):
Boduen A. Ya., Deputy Head of Chair, Associate Professor, Candidate of Engineering Sciences

JV CJSC «IVS» (Saint Petersburg, Russia):
Ukraintsev I. V., Director of the Department, Candidate of Chemical Sciences

The aim of the work was to establish the feasibility of processing refractory gold-bearing pyrite-arsenopyrite flotation concentrate of ore taken from the Bestobe deposit using vat biooxidation. The concentrate contained 31.38 % of pyrite and 15.6 % of arsenopyrite. The recovery of gold in cyanidation was 43 %. For the biooxidation, a mixed culture of acidophilic microorganisms was used. Respective concentrate biooxidation was carried out continuously in laboratory reactors at 40 °C; the residence time was five days. The liquid to solid ratio of the slurry was 6.7 in the first option and 5 in the second option. The concentrate was subjected to cyanidation after biooxidation to establish its effect on gold recovery, and the chemical composition of the product was analyzed. In the first option, the oxidation degree was 78.9 % for sulfide sulfur and 77.8 and 84.1 % for pyrite and arsenopyrite, respectively. The oxidation degree in the second option was 62.4 % for sulfide sulfur and 58.4 and 82.4 % for pyrite and arsenopyrite, respectively. Cyanidation of 48 hours allowed recovering 92.5 and 93.5 % of gold from the bio-cakes obtained for the first and second options, respectively. The cyanide consumption was 26 and 32 kg/t. The results indicate that vat biooxidation is a promising technology for the processing of refractory sulfide ore concentrates from the Bestobe deposit, since it allows significantly increasing gold recovery by cyanidation while maintaining the process parameters of the biooxidation process (temperature, slurry density, residence time) used at existing industrial enterprises.
This work was carried out as part of joint research project No. 07-01-17 of ZAO SP IVS and the Federal Research Centre «Fundamentals of Biotechnology» of the Russian Academy of Sciences with the support of the Russian Ministry of Education and Science.

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