Microorganisms such as Bacillus polymyxa which occur indigenously associated with several ore deposits, bring about significant surface chemical changes on interacted minerals such as hematite, corundum,calcite, quartz and kaolinite. Bacterial interaction rendered quartz and
kaolinite surfaces hydrophobic, while hematite, corundum and calcite surfaces became more hydrophilic. Biotrearment of mineral mixtures containing the above minerals was found to result in selective _flocculation and selective flotation. It is shown that selective removal of silica and alumina from iron ores and bauxite can be brought about
by biological processes.Mechanisms behind such microbially induced beneficiation processes are illustrated with res-pect to processing of fine particles
