Effect of Residual Volatile Matter on Reduction Reaction between Semi-coal-char and Iron Oxide

Abstract

Carbon composite pellets intentionally including residual volatile matter (V.M.) were proposed to decrease the starting temperature for reduction reaction of carbon composite iron ore agglomerate under a rising temperature condition, such as in a blast furnace shaft. The carbonization of coal (Newcastle blend coal) under a rising temperature condition was interrupted at a certain temperature, T_C,max=823, 1073 and 1273K, to obtain semi-coal-char including some residual V.M. The semi-coal-char was mixed with reagent grade hematite in the mass ratio of one to four, together with Bentonite of 1 mass% as a binder. Carbon composite pellets using the semi-coal-char were prepared by hand rolling. From the TG-DTA analysis, the weight of carbon composite pellet at T_C,max=823K decreased largely from 823K because of release of residual V.M. Isothermal reductions of thus obtained pellets were done in N₂ gas atmosphere. Fractional reductions of the carbon composite pellets using the semi-coal-char at T_C,max=823K were higher than any other pellets (T_C,max=1073 and 1273K) by about 10% at reduction temperatures: T_R=1073 and 1173K. Furthermore, it was confirmed by the XRD analysis after reduction of pellets that the carbon composite pellets at T_C,max=823K have the highest reducibility; the original Fe₂O₃ was mainly reduced to Fe₃O₄ and FeO at T_R=1073K for 60 min, to FeO and Fe at T_R=1173K for 90 min and to Fe at T_R=1273K for 60 min.