合成クロマイト(Fe<SUB>0.5</SUB>Mg<SUB>0.5</SUB>)(Cr<SUB>0.8</SUB>Al<SUB>0.2</SUB>)<SUB>2</SUB>O<SUB>4</SUB>の溶融還元速度

Abstract

The kinetics of smelting reduction of (Fe0.5Mg0.5)(Cr0.8Al0.2)2O4 in molten silicate flux with graphite has been investigated at temperatures from 1773 to 1973 K. The reduction rate was described with a first-order-type rate equation: log (1−R)=−k·t. In the early stage of reduction, in which FeCr2O4 component was preferentially reduced, the rate constant k was virtually independent of the flux composition and the wetting of the flux to the graphite. The activation energies were 200∼250 kJ/mol. The reduction rate was controlled by the dissolution of the chromite into the flux.In the late stage of reduction, Mg(Cr0.6Al0.4)2O4 component was reduced. The wider contact of the flux with the graphite increased k. The dependences of k on the flux composition and temperature were complicated. The reduction in the flux with a low melting point at a higher temperature was controlled by the chemical reaction at the flux-graphite interface. The reduction in the flux with a high melting point at a lower temperature was mixed-controlled by both the dissolution and the interfacial reaction.