Cells and metabolic products of Bacillus polymyxa were successfully used in flocculation and flotation to remove chalcopyrite from quartz and calcite with a view to environmental protection and ore beneficiation. Adsorption studies revealed that the magnitude of adsorption density of bacterial cells onto chalcopyrite was the highest in comparison to quartz and calcite. Electrokinetic behavior of the mineral surfaces before and after interaction with bacteria was investigated. Bacterial byproduct such as extracellular bacterial protein and extracellular bacterial polysaccharides were isolated and their individual effects on minerals were studied through flocculation and flotation. Selective separation of chalcopyrite from quartz and calcite was achieved through interaction with extracellular protein. Extracellular bacterial protein flocculated chalcopyrite and dispersed quartz. Subsequently, enhancement in the hydrophobicity of quartz surfaces on interaction with bio-protein resulted in higher separation from chalcopyrite through flotation. (C) 2003 Elsevier B.V. All rights reserved.