Microbial Treatment of Lateritic Ni-ore for Iron Beneficiation and Their Characterization

Abstract

Abstrac t Th is study aims at studying effect of anaerobic dissimilatory iron (III) reducing bacterial consortium on different phases of iron present in lateritic n ickel ore. Such conversion in lateritic nickel ore are helpful in better recovery of sorbed metal values like Ni and Co by subsequent bioleaching or acid leaching. Here properties of thermally and microbially reduced lateritic nickel ore are co mpared vis-a-v is orig inal ore. An anaerobic d issimilatory iron (III) reducing bacterial consortium capable of using glucose as carbon source and laterit ic n ickel ore as terminal electron acceptor was used for microbial reduction of ore under anaerobic condition. M icrobial reduction changes the initial light bro wn colour of the lateritic n ickel ore to dark bro wn. The change in colour is due to the conversion of goethite to magnetite, wh ich is confirmed fro m the XRD pattern. The FTIR spectra and the UV-Visib le spectra support the presence both goethite and hematite. The study shows that changes in phases brought about by microb ial treat ment are d ifferent than those by thermal treat ment. The carrier mediated exchange interaction between Fe 2+ and Fe 3+ ions in lateritic n ickel o re samp le treated with IRB consortium is responsible for higher ferro magnetic ordering. The thermal reduction of the same sample showed lowering of ferro magnetic ordering due to the decreasing percentage of Fe 2+ and Fe 3+ ions.