Influence of Bacillus subtilis on the surface behavior and separation of talc and chlorite minerals

Abstract

Bacillus subtilis was used as a bio-surface modifier to improve the floatability of talc mineral (Mg₃Si₄O₁₀(OH)₂) in the talc ore. The surface behavior of chlorite mineral as the main associated gangue with talc mineral was studied in the presence of B. subtilis using zeta potential, scanning electron microscopy, and Fourier-transform infrared spectroscopy techniques. The floatability of both minerals was investigated as a function of pH, contact time, and concentration of B. subtilis. The results showed that the zeta potential of the talc mineral was strongly influenced by the treatment with B. subtilis. The maximum separation efficiency of talc from chlorite was achieved at pH 4. A talc concentrate with 98% quality and about 95% recovery was prepared from a binary talc-chlorite mixture containing 85% talc under optimum conditions of 8 × 10⁵ cells/mL B. subtilis, pH 4, 35°C, and a contact time of 10 min.