Effect of Blaine Fineness on the Quality of Hematite Iron Ore Pellets for Blast Furnace

Abstract

Iron ore pellets are largely characterized by inherent physical and chemical properties of ore as well as pelletizing conditions including induration time, induration temperature, etc. These parameters essentially vary with types of ores. The production of high-quality pellets from hematite ore is challenging because of high level of fineness (Blaine number) and induration temperature requirement, ensuring severe degradation property during reduction, etc. In this work, the effect of Blaine number (Blaine fineness: expressed as the specific surface area of fines) on the pellets’ properties was studied. The paper presents the effect of Blaine number on green and dry strength, cold crushing strength, reducibility index, reduction degradation index, swelling index, apparent porosity, optical micro structure, etc. of the high alumina hematite ore pellets. The results showed improved properties of iron ore pellets at an optimum Blaine number (2150 cm2/g) but, reduction degradation index was found to be very poor for the given ore. Further investigation showed that when MgO containing flux viz. pyroxenite was added, the reduction degradation index and swelling index of the pellets were improved for identical Blaine number and other optimized process parameters.