Indirect bioleaching of low-grade nickel limonite and saprolite ores using fungal metabolic organic acids generated by Aspergillus niger

摘要

AbstractThe objective of the present study was to investigate the indirect bioleaching of low-grade nickel limonite and saprolite ores using fungal metabolic organic acids generated byAspergillus niger. The indirect bioleaching experiments were carried out in a 2000ml five-neck glass vessel containing 500ml of the culture filtrate comprising fungal metabolic organic acids (which were obtained from organic acid biogeneration experiments after filtration) supplemented with limonite or saprolite ores. For the organic acid biogeneration experiments, the highest generation of organic acids byA. nigerwas achieved for cassava starch as carbon source in the presence of KH2PO4, (NH4)2SO4and MgSO4under aeration condition, which were subsequently employed for the indirect bioleaching experiments. The highest nickel leaching efficiencies from saprolite and limonite ores were 88.9% and 84.9%, respectively, which were obtained at leaching temperature of 95°C, stirring speed of 400rpm, ore particle size of -177+149μm, and leaching time of 4h (for saprolite) and 24h (for limonite). Most importantly, the leaching using the biogenerated organic acids in this study is highly selective to magnesium (Mg) and is relatively selective to iron (Fe), thus supporting their potential industrial applications with respect to economic and environmental concerns.Highlights?Organic acids can be generated byA. nigerin a medium of cassava starch, nitrogen and phosphate under aerated condition.?Indirect bioleaching of saprolite ores was highly selective to Mg with extraction of 1.5% after 24h of bioleaching test.?Organic acids generated byA. nigerwere more effective in bioleaching nickel saprolite ores than nickel limonite ores.]]>