Reduction Behavior of Iron Ore Agglomerates of FeO-CaO-SiO₂-Al₂O₃ and Influence of Al₂O₃

Abstract

In order to utilize lower quality of iron ores with high Al₂O₃ contents, it is important to understand the influence of Al₂O₃ contents on reducibility of iron ore agglomerates. Reduction behavior of iron ore agglomerates of FeO-CaO-SiO₂- Al₂O₃ were investigated under 30vol%CO-70vol%N₂ gas mixture at temperatures from 1000 to 1200°C at 5°C/min. The samples contained Al₂O₃ contents of 0, 2, 4 mass%. The reducibility of iron ore agglomerate decreased by Al₂O₃ contents of 2, 4 mass% over 1100°C. This result was caused by lowering the reducing gas diffusion rate into an unreacted region of agglomerate. Considering this, it was suggested that initial melt formation started and some pores of agglomerate was blocked by the initial melt over 1100°C. In-situ observation of initial melt formation behavior in an iron ore agglomerate was performed from 1000°C to 1310°C at 5°C/min by using a scanning laser microscope. The initial melt formation shifted to lower temperatures with increasing Al₂O₃ contents, and the amount of melt also increased.