Overcome organic solvent inhibition from acidophilic microorganisms in PLS by addition of isolated heterotrophic degraders

摘要

In biohydrometallurgy process, copper separation from Pregnant Leach Solution (PLS) takes place using solvent extraction. This is a necessary step prior to electrowinning processes. Then, the copper free PLS solution called "Raffinate" recycles to the copper heap. However, during the solvent extraction process, part of the organic compounds (such as kerosene and organic extracts) may be entrapped in the Raffinate solution and this can decrease substantially the activity of autotrophic acidophilic microorganisms such as Acidobacilus ferroxidans, Leptospirilium ferroxidans (Mazuellos et al. 1999, Waiting et al. 2009). Several studies propose various strategies for alleviating this effect such as organic solvent pre- treatment with activated carbon or adaptation of acidophilic microorganisms (Collinson et al. 2011, Bo et al. 2010, Davis-Belmar et al .2012). The aims of this research was firstly to isolate heterotrophic microorganisms that can biodegrade organic compounds from the organic phase at low pH. Secondly, to add the isolated strains within PLS and to test if they can alleviate organic compounds inhibition from autotrophic acidophiles when exposed to copper sulphide ore.