Bioflocculation of (Iron oxide – Silica) system using Bacillus cereus bacteria isolated from Egyptian iron ore surface

In mineral bio-beneficiation, it is very important to understand the microbial surface characteristics and its behaviour onto the mineral surface. Bacillus cereus bacterium has never been used before as a bio-reagent for separation of different mineral systems. In this work, complete characterization of such type of bacteria, isolated from Egyptian iron ore surface, including gram stain, growth curve, Biolog microbial identification, Zeta potential characterization, Fourier Transform Infrared Spectrometer, FTIR characterization as well as protein and polysaccharide analysis have been studied. The results confirmed that Bacillus cereus is a gram positive bacterium, rod shaped, smooth and circular with different types of by-products as polysaccharides, carboxylic acids and amino acids that gives an amphoteric behaviour on the cell surface. The results of zeta potential showed that the iso-electric points (IEP) of iron oxide (≈6.3) and silica (≈1.8) were significantly displaced to low values (≈2.2) and (≈1) respectively after treatment with the bacterial isolates. The results obtained showed a better affinity of Bacillus cereus to hematite mineral surface rather than silica surface and could be used in separation of such mineral from its associated gangue minerals. On applying B. cereus bacterial strain as a sole flocculating agent, to selectively separate hematite from its mixture with silica, succeeded in the removal of 80% of SiO₂ as a concentrate containing about 2% SiO₂ and 98% Fe₂O₃ with 82% flocculated by Wt. and a good recovery of 89.20%.