Abstract

ERWEE, M.W.; GELDENHUYS, I.J.; SITEFANE, M.B.  and  MASIPA, M.. Fluxing of South African chromite ore with colemanite. J. S. Afr. Inst. Min. Metall. [online]. 2018, vol.118, n.6, pp.661-670. ISSN 2411-9717.  http://dx.doi.org/10.17159/2411-9717/2018/v118n6a15.

South African chromite ores are smelted using SiO₂- and CaO-containing fluxes, normally as quartz and limestone respectively. The purpose of SiO₂ is to lower the melting point of the ore, while CaO is added to ensure that the slag that forms on smelting is fluid enough to enable slag/alloy separation and tapping from the furnace. Colemanite is a borate mineral originating primarily from Turkey, and has the nominal, ideal composition CaB₃O₄(OH)₃.H₂O. B₂O₃ readily fluxes chromite, and low amounts of this compound can yield a lowering of the melting temperature similar to that obtained using SiO2. In addition, colemanite already contains CaO, which aids in making the resulting slag more fluid. Laboratory-scale smelting tests were conducted at Mintek over the course of 18 months. The work included evaluation of a variety of boron-containing materials to replace conventional fluxes. The results of the tests and modelling work are presented in this paper.

Keywords : chromite; smelting; ferrochrome; colemanite; boron; energy.

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