Abstract
In relation to the smelting reduction of chromite ore, the mechanism of dissolution of Cr2O3 particles in silicate slags and subsequent reduction by solid carbon was studied. The reduction rate of Cr2O3 particles melted in a graphite crucible with the slag was measured by means of thermogravimetry under an argon atmosphere, and the dissolution of Cr2O3 was examined by microscopic observation and chemical analysis. The dependence of the reduction rates on flux/Cr2O3 ratio, particle size of Cr2O3, temperature and slag composition were investigated. The rate was markedly affected by the wettability of the slag to the graphite. In early stage of the reduction, Cr2O3 particles were attacked by the slag and were broken into smaller ones. Thereafter, they dissolved in the slag from their surface. Carbide was mainly formed on the graphite, but the fine particles of carbide also was observed inside Cr2O3 melted with some silicate slag containing Al2O3 and MgO. The rate determining step was not a single process but varied with the conditions of the reduction.
