Fundamental experiments on the H2 gas injection into the lower part of a blast furnace shaft

Abstract

It is necessary to reexamine basically an ironmaking process in order to reduce CO2 emission and energy consumption in a blast furnace. Especially, direct reduction from wustite (FeO) to iron (Fe) stage of iron ore sinter with solid carbon in the blast furnace is a strong endothermic reaction. H2 injection from the lower part of the shaft at temperatures from 1173 to 1373 K can be considered more effective for the increase of the reduction degree from FeO to Fe. The effective conditions of H2 ratio in CO-CO2-H2-N2 mixture and the reduction temperatures have been investigated in the bed packed with sinter by comparing the reduction degrees from FeO to Fe between one method blown all the gases into the alumina ball bed (all gas mixed injection method or Method A) and the other method blown only H2 through another nozzles into the lower end of the sinter bed without mixing (H2 non-mixed injection method or Method N). In the gas composition (CO+H2)/(CO+CO2+H2)=0.75 at 1173 K determined by taking into account those in the blast furnace, the reduction rate was enhanced in the case of Method N. From comparison between the reduction degree after 90 min in the case of Method N and that in the case of Method A, the reduction degree of Method N is about 1.2 times higher than that of Method A under each condition of H2/(CO+H2)=0.1 or 0.3. Under the condition of (CO+H2)/(CO+CO2+H2)=0.75 at the reduction temperature of 1273 K, the reduction rate in the case of Method N is also higher than that in the case of Method A.