Laugung lateritischer Nickelerze mit heterotrophen Mikroorganismen

Organic acids that are excreted by microorganisms dissolve nickel from lateritic ores. In chemical leaching experiments, fifteen organic acids were tested in the concentration range of 0.05–0.5 M. The most effective were hydroxycarboxylic acids. The leaching of nickel is dependent on the type of mineralization. With completely limonitized ore, no mobilization occurred, while up to 90% of the nickel was extracted from silicate-bearing laterites by 0.5 M citric acid. In biological leaching tests, Penicillium was found to be the most effective microorganism. After improvement of the leaching conditions, up to 70% of the nickel was extracted at considerably lower citric acid concentrations than with the chemical leaching process. Generally, leaching of nickel from lateritic ores with heterotrophic microorganisms is possible and seems to be promising. Possibilities for future investigations are discussed.