MINERAL LEACHING OF NON-SULFIDE NICKEL ORES USING HETEROTROPHIC MICROORGANISMS

Laboratory studies were conducted on microbial leaching of non-sulphid e nickel ores not amenable to conventional mineral processing operatio ns. The results showed that extensive low-grade laterite domestic sour ces are generally amenable to bioleaching when micro-organisms were cu ltivated in the presence of the ore. Nickel recoveries were as high as 60% using hydroxycarboxylic acid producing strains of Aspergillus and Penicillium codes A3, P2. Cobalt recovery achieved was around 50%. Lo sses of soluble nickel in the fungal biomass were found to be 3.5-10.8 %. Chemical analysis of the leach liquors showed the presence of signi ficant amounts of citric, oxalic and other organic acids, indicating t hat leaching may be ascribed to the production of these metabolic prod ucts of fungal activity.