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Selective biodissolution of calcium and iron from bauxite in the presence of Bacillus polymyxa

Deo, Namita and Vasan, SS and Modak, Jayant M and Natarajan, KA (1999) Selective biodissolution of calcium and iron from bauxite in the presence of Bacillus polymyxa. In: Biohydrometallurgy and the Environment Toward the Mining of the 21st Century - Proceedings of the International Biohydrometallurgy Symposium, JUN 20-23, 1999, Madrid, Spain.

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Official URL: http://dx.doi.org/10.1016/S1572-4409(99)80047-9


A bacterium Bacillus polymyxa was found to be capable of selective removal of calcium and iron from bauxite. The bioleached residue was found to be enriched in its alumina content with insignificant amounts of iron and calcium as impurities. The developed bio- process was found to be capable of producing a bauxite product which meets the specifica- tions as a raw material for the manufacture of alumina based ceramics and refractories. The role of bacterial cells and metabolic products in the selective dissolution of calcium (present as calcite) and iron (present as hematite and goethite) from bauxite was assessed and possi- ble mechanisms illustrated. The effect of different parameters such as sucrose concentra- tion, pH, pulp density and time on selective biodissolution was studied. It was observed that periodic decantation and replenishment of the leach medium was beneficial in improving the dissolution kinetics. Calcium removal involves chelation with bacterial exopolysaccha- tides and acidolysis by organic acid generation. Hematite could be solubilized through a reductive dissolution mechanism.

Item Type: Conference Paper
Publisher: Elsevier B.V.
Additional Information: Copyright of this article belongs to Elsevier B.V.
Department/Centre: Division of Mechanical Sciences > Chemical Engineering
Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Date Deposited: 16 Mar 2012 09:02
Last Modified: 16 Mar 2012 09:02
URI: http://eprints.iisc.ac.in/id/eprint/43906

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