Bacillus subtilis is used as a bio-surface modifier to flocculate hematite mineral (Fe 2O 3). The effect of bacterial interaction on the behavior of hematite and apatite minerals, as the main source of phosphorous in iron ore, was investigated using zeta-potential, SEM, and FTIR measurements. The effects of pH, contact time, and Bacillus subtilis concentration on the flocculation of the two minerals were studied. The zeta potential of hematite is strongly affected by interaction with Bacillus subtilis, and maximum flocculation efficiency was achieved at pH 6. Hematite could be separated from its mixture with apatite in the presence of 8 - 12×10 5 cells of Bacillus subtilis at pH 6 and 35 °C for a 10-minute contact time.
