The dissolution of a Transvaal chromite in liquid silicate slags under an inert atmosphere at 1550 celcius degrees and 1650 celsius degrees.

Curr, Thomas Robert
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The role of chromite dissolution in the smelting of ferrochromium was investigated with the object of improving the throughput and chromium recovery of the process. The solubility of a typical Transvaal chromite in silicate slags with cao/si02 ratios from 0,03 to 0,55 at 1550·C and 1650·C was determined. Synthetic slags were melted in porous chromite crucibles and the slag underwent repeated reactions with the chromite grains as it penetrated the crucible wall. Finally the slag came into equilibrium with -''the ,original chromite towards the outer part of the crucible wall. Microprobe analysis of this slag yielded the maximum or saturated solubilities of the chromite constituents in the slag. The solubility of cr203 was found to be low (-1 per cent) while the remaining components' solubilities (A1203 -16 per cent, FeO)T 12 per cent and MgO-8 per cent) were significantly higher. CaO/Sio2 ratios greater than 0,1 lowered the solubility of Mg0 significantly (e.g. from 14,1 per cent to 5,8 per cent at 1650·C). The complete dissolution of this chromite in these slags requires the slag to contain less than the solubility limits of each of these species simultaneously. It was recommended that the best way to achieve this in practice would be a well-stirred slag bath containing suspended carbon particles, in which a cao/Sio2 ratio of less -than 0,1 was maintained. Further work to investigate the effect of slag composition (including Na20 and CaF2) on the kinetics of chromite reduction in such a system was recommended.
A dissertation submitted to the faculty of Engineering, University of the Witwatersrand, in fulfillment of the requirements for the degree of Master of Science in Engineering.
Iron -- Metallurgy -- Research., Iron alloys -- Electrometallurgy., Chromium-iron alloys.