Experimental Investigation of Hematite Fines Reduction to Magnetite with Coal and Coke Fines

Abstract

In this current investigation, we aimed to comprehensively examine how various key processing parameters influence the reduction of hematite particles enveloped by coal and coke fines. This reduction process took place in an externally heated cylindrical steel container, which we will call the "work tube." This work tube had a diameter of 70 mm and a height of 300 mm and was situated within a pot furnace. For the experimentation, we employed Jhama coal and coke fines as solid reductants, both of which were finely ground to a size of -100 mesh. The study encompassed an analysis of factors such as the carbon/Fe2O3 molar ratio in the mixture, the temperature of the pot furnace, and the duration of the reduction process. Prior to the actual experiment, the hematite powder, with a particle size of approximately 27 µm, as well as the Jhama coal and coke fines, were sifted through a 100-mesh sieve. Our primary aim was to assess the extent of transformation from hematite to magnetite, with the ultimate objective of applying this transformed material in heavy media separation for coal beneficiation. The process of reducing hematite fines, which have a particle size of 27 µm, was carried out at three different temperatures: 700°C, 750°C, and 800°C, under the protection of an inert gas atmosphere. Nitrogen or argon were the preferred gases used for this purpose. This allowed us to analyze the reduction of hematite powder by Jhama coal and coke fines individually. We determined the degree of reduction of hematite fines at specific time intervals of 30, 60, and 90 minutes, once the furnace had reached the designated reduction temperature. To ensure the reliability of our findings, the experiments were meticulously designed in a manner that enabled a quantitative assessment and comparison of the impact of each variable. Notably, at a furnace temperature of 800°C, we achieved a remarkable reduction degree of over 80%.