Lowering of Thermal Reserve Zone Temperature in Blast Furnace by Adjoining Carbonaceous Material and Iron Ore

Abstract

The improvement in the efficiency and the decrease in the temperature of reactions in the blast furnace have been required. Among the reactions, the solution loss reaction (C+CO2=2CO) is an intensive endothermic reaction and controls the overall reaction inside the blast furnace. To realize the increase in the rate and the decrease in the temperature of the solution loss reaction, a technology to improve the reactivity of carbonaceous material by mixing it into packed ore bed, i.e. a technology to improve the reactivity by adjoining carbonaceous material and iron ore was fundamentally investigated.Various kinds of carbonaceous materials were mixed into the packed ore bed and the starting temperature for the endothermic reaction equivalent to the solution loss reaction was measured on the basis of the principle of differential thermal analysis. Small size coke and carbon composite iron ore agglomerate as carbonaceous materials were mixed into the ore bed and the effect of carbon content in the ore bed and the effect of the degree of contact between carbonaceous material and iron ore were investigated. The following results were obtained.(1) With the increase in the amount of carbonaceous material mixed into the ore bed, namely, in the carbon content in the ore bed, the starting temperature of the reaction is lowered.(2) When the carbon content in the ore bed is constant, with the increase in the degree of contact between carbonaceous material and iron ore, the starting temperature of the reaction is lowered.(3) Accordingly, it is expected that even when the carbon content in the ore bed is low, by mixing carbonaceous material into the ore bed to increase the degree of contact between carbonaceous material and iron ore, the temperature in the thermal reserve zone is lowered considerably. This results in the improvement of CO gas utilization efficiency and, as a result, the decrease in the reducing agents rate. The use of carbon composite iron ore agglomerate is promising as a means to realize the above expectation.