Empress Catherine II St Petersburg Mining University, Saint Petersburg, Russia

O. V. Cheremisina, Head of Department of General and Physical Chemistry, Doctor of Technical Sciences
R. E. Vasiliev, Postgraduate Student, e-mail: vasilroman2308@yandex.ru

Polymetal Engineering JSC, Saint Petersburg, Russia
A. O. Netrusov, Senior Engineer
A. K. Ter-Oganesyants, Principal Specialist, Candidate of Technical Sciences

This paper describes the results of a laboratory study that examined hydrometallurgical processing of high-arsenic silver-copper concentrates, the cyanide leaching of which fails to provide the required recovery of target components while entailing high processing costs. The process involves pressure oxidative leaching of the primary material and application of the following processes to autoclave slurry: hot curing and lime boiling, plus cyanide leaching to enable transfer of gold and silver from POX cakes to the liquor. The process of pre ssure oxidative leaching was studied in the temperature range of 200 to 240 ^oC. The problem of low recovery of silver (less than 10% for each concentrate) was identified when concentrates with high concentrations of silver, iron and arsenic were subjected to pressure oxidation without additional conditioning. The authors analyzed the available literature and used the results of mine ralogical and chemical analyses of the primary material and the products to establish that the above problem could be due to the formation of compounds that can hardly be processed by cyanide leaching and that encapsulate silver – i. e. argentojarosites. It is proposed to solve this problem by decomposing silver-containing non-cyanidable compounds. The paper also describes some additional conditioning operations aimed at raising the recovery of valuable components into the final product. It was found that hot curing at 98 ^oC for 2 and 6 hours and lime boiling at 95 ^oC for 2 hours helped to significantly raise the recovery of silver into the cyanide liquor (up to 95%).

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