Reduction of Acid Iron Ore Pellets under Simulated Wall and Center Conditions in a Blast Furnace Shaft

Abstract

The operational conditions, including temperature and gas composition, vary along the radial position in a blast furnace. Nevertheless, very few studies can be found in the literature that discuss how the reduction behavior of the ferrous burden varies along the radial position. In this study, the effect of the radial charging position on the reducibility of acid iron ore pellets was investigated using a laboratory-scale, high-temperature furnace in CO-CO2-N2 and CO-CO2-H2-H2O-N2 atmospheres up to 1100 °C. The experimental conditions were accumulated based on earlier measurements from a multi-point vertical probing campaign that was performed for a center-working European blast furnace. The main finding of this study is that the pellet reduction proceeded faster under simulated blast furnace conditions resembling those in the center area, compared to the wall area, because of a higher share of CO and H2 in the gas. Therefore, the pellet charging position affects its reduction path in a blast furnace. Additionally, it was shown that the presence of H2 and H2O in the reducing gas enhanced the progress of reduction reactions significantly and enhanced the formation of cracks slightly, both of which are desirable in blast furnace operation. The reducibility data attained in this study are important in understanding how temperature and gas composition is connected to the reduction degree under realistic process conditions.