Irkutsk Research Institute of Precious and Reare metals and Diamonds, Irkutsk, Russia:
A. N. Seleznev, Junior Researcher, e-mail: lost.ofp@gmail.com
A. V. Epiforov, Senior Researcher, e-mail: epiforov@irgiredmet.ru
Yu. E. Emelyanov, Leading Researcher
S. V. Balikov, Chief Researcher

Heap biooxidation is the cheapest option to treat processing plants tailings and refractory ores containing non-ferrous and precious metals and sulfides. The tailings of copper ore processing (sample #1), the tailings of sulfide coppernickel ore processing (sample #2) and double refractory gold-bearing ore (sample #3) were studied. Heap biooxidation tests used the autotrophic microorganisms Аcidithiobacillus thiooxidans and Аcidithiobacillus ferrooxidans. The duration of heap biooxidation tests for samples 1, 2 and 3 was 6, 10 and 16 months, respectively. The recoveries of copper and zinc to the solution during heap biooxidation of sample #1 were 68% and 71%, respectively. The recoveries of copper and nickel from sample #2 were 50% and 75%, respectively. The solution obtained by heap biooxidation of sample #1 contained 0.74 g/l copper and 0.97 g/l zinc. Cementation on zinc was used for copper recovery from the productive solution. Copper recovery was 98%, and copper concentrate containing 54.3% copper were obtained. Zinc precipitation from the solution used sodium carbonate. Zinc concentrate contained 44.8% of zinc. The recovery of zinc was 98%. The solution obtained by heap biooxidation of sample #2 contained 4.3 g/l of nickel and 0.85 g/l of copper. Sodium carbonate and sodium sulphide were compared for this solution processing. A collective nickel-copper carbonate concentrate content of 16.1% nickel and 4.3% copper was obtained. Selective nickel concentrate (26.1% nickel, 5.5% copper) and copper concentrate (38.4% copper, 5.3% nickel) were obtained using sodium sulphide. Biooxidation tailings of samples 1 and 3 were leached using an alkaline sodium cyanide solution. The recovery of gold from sample #1 and sample #2 was 65% and 85%, respectively.

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