LAUGUNG VON KUPFERKARBONAT-UND KUPFERSILIKAT-ERZEN MIT HETEROTROPHEN MIKROORGANISMEN

Abstract

Leaching of carbonate and silicate ores with Thiobacilli under laboratory conditions has not been very successful. We have tested the leaching effects of organic acids and of acid producing heterotrophic microorganisms upon a low-grade copper ore, containing carbonates and silicates, from Timna, Israel. Good results were obtained with citric, lactic, glycollic, and tartaric acids. Citric acid, 0.05 M, for instance, solubilized 82% Cu. By lowering the pH with sulphuric acid to pH 2, lactic, eitric, and glycollic acids yielded almost 100% Cu. Citric acid producing strains of Aspergillus niger, growing in surface cultures on a Ssucrose fermentation medium, leached more than 80% Cu. Sulphite liquor may be used with fair results as a fermentation medium for A. niger. Anaerobic leaching experiments with whey, containing homofermentative lactobacilli, yielded 83% Cu.