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. / 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. / AC 2018
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:wits/oai:wiredspace.wits.ac.za:10539/24333 |
| Date | January 1990 |
| Creators | Curr, Thomas Robert |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | application/pdf |
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