Bioleaching Process for the Recovery of Metals: A Review

Abstract

Bioleaching is a modest and operative technology for extracting metals from low-grade ores and mineral distillates, based on the metabolic action of microbes. In sulfide reserves, chemolithotrophic bacteria such as Thiobacillus thiooxidansandThiobacillus ferrooxidans oxidize insoluble metal sulfides into soluble metal sulfates, allowing metal recovery, while heterotrophic bacteria and fungi that solubilize metals through the production of organic acidstreated non-sulfide ores. Presently, bioleaching is usefulmostly for the recovery of copper, uranium, and gold, with heap, dump, and in-situ leaching being the principal industrial techniques, while stirred-tank bioleaching is used for dealing refractory gold ores. In addition to mineral extraction, bioleaching also holds important potential for metal retrieval and detoxification of industrial wastes, sewage sludge, and heavy-metal-contaminated soils.