Resumo

BHALLA, A.; KUCUKKARGOZ, C.S.  e  ERIC, R.H.. Solid-state reduction of an ilmenite concentrate with carbon. J. S. Afr. Inst. Min. Metall. [online]. 2017, vol.117, n.5, pp.415-421. ISSN 2411-9717.  http://dx.doi.org/10.17159/2411-9717/2017/v117n5a2.

The solid-state reduction of ilmenite concentrate with graphite was studied under argon atmosphere at temperatures between 1050°C and 1350°C. The rate of reduction increased with increasing temperature and decreasing particle size, with the maximum extent of reduction found to be 80% at 1350°C with a particle size in the range of -106 +90 μm. The activation energy for the reduction reaction was calculated to be 257 kJ/mole. The trivalent iron oxide was reduced first to divalent iron oxide and then to metallic iron. An annular ring of a partially reduced oxide phase containing metallic nuclei was formed around the core of ilmenite, which grew in size as the original ilmenite core shrank with progressive reduction. The reduction of titanium dioxide also took place during this stage, which produced the Magnéli oxides in the form of Ti_nO_2n-1. The metallic phase had very high Fe and low Ti contents throughout the reduction, whereas the partially reduced oxide phase adjacent to the metallic phase was high in Ti and depleted in Fe. The metallic phase globules formed during this stage were small and are considered suitable only for leaching and not for other concentration processes. The core of the particle generally retained the composition of the original ilmenite. The purpose of this work was to remove iron and increase the titanium oxide content of the ilmenite to produce a high-titanium containing charge for subsequent smelting

Palavras-chave : ilmenite; carbon; solid-state reduction; activation energy.

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