Reduction Behaviour of Olivine Iron Ore Pellets in the Experimental Blast Furnace

An experimental study was conducted to determine the reduction behaviour of olivine iron Ore pellets and associated reduction mechanisms in the experimental blast furnace (EBF) located at Lulea. Two sets of EBF samples, namely slowly annealed excavated samples and rapidly quenched probe samples of olivine bearing iron ore pellets were examined in detail. Pellet samples were analysed using SEM, XRD and SIROQUANT analysis to quantitatively determine iron ore phase transformations during descent in the EBF. In the tested EBF campaign, up to 75% of reduction occurred at less than 1100 degrees C, i.e. before the pellet reached the cohesive zone while rest of 25% reduction was completed when pellets reached a temperature of 1300 degrees C and hence within the cohesive zone. The reduction degree of pellets was found to have a linear correlation with distance from the stock line of the EBF This study showed that the presence of olivine did not have a significant effect on reduction degree for temperatures less than 1100 degrees C in the upper zone of the EBF However, olivine increased the reduction rate in the final stage of reduction for temperatures in excess of 1100 degrees C in the cohesive zone, which was attributed to the formation of an increased amount of molten FeO containing slag within the pellet. This study is expected to make important contributions towards further improvements in the pellet design as well as the optimization of blast furnace operation and efficiency.