Cr₂O₃粒の固体炭素による溶融還元機構

抄録

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.