Utility of bioreagents in mineral processing

Biological processes have recently become more attractive in hydrometallurg y and mineral processing due to their lower operating costs, potential for processing low-quality ores and flexibility. Adhesion of microbes and their metabolic products can modify the particles to render them hydrophobic or hydrophilic. Such modifications of the surface properties are used in flota tion and flocculation of minerals. Microbes are also able to dissolve diffe rent precious metals from their ores. In this paper the role of microbes an d their metabolic products as surface modifying reagents in extraction proc esses is discussed. In addition, the ability of certain microbes to adsorb toxic metal ions or to degrade toxic chemicals discharged by industries is examined.