Evaluation of biotechnological potential for treating of a one gold ore from a mine of Amapa state

The aim of this work was to study the best biotechnology route for the pretreatment of the gold ore in order to reduce cyanide consumption during the conventional cyanidation and increasing the gold recovery. For this purpose, biological tests have been investigated at laboratory scale on a gold ore sample coming from Estado do Amapa, Brazil (90 g/ton). Bacterial cultures utilized in the biological tests of 20 days consisted of Acidithiobacillus ferrooxidans LR and Acidithiobacillus thiooxidans FG01. The bio oxidated samples were submitted to cyanidation tests for gold recovery and tests of consumption of cyanide. Experimental studies demonstrated that after 24h leaching time by direct cyanidation, the gold recovery was 93% (32 mg/L) with a cyanide consumption of 2,84 kg.t^-1, while the best gold extraction between biooxidated samples was from bioreactor R2 with 87% (30 mg/L), and the cyanide consumption of 2,64 kg.t-1. Experimental results have shown the technical feasibility of the bio oxidative prior to conventional leaching for reducing the consumption of reagent cyanide. (author)