Experimental study on strengthening the hydrogen reduction process of pyrite in the presence of alkaline oxide

In this study, an innovative approach is proposed for the hydrogen reduction of pyrite in the presence of alkaline oxide, suitable for desulfurisation of high-sulfur bauxite and iron extraction from pyrite. This approach has the advantage of efficiently utilising high-sulfur bauxite, solving the issue of SO2 flue gas pollution. Stirred fluidised beds were used as reactors to promote uniform particle distribution. The impact of hydrogen concentration and spatial velocity of the gas on the reduction process of pyrite and the sticking behaviour between particles in a side-stirred fluidised bed were investigated using a single-factor experimental method. The effects of various experimental conditions on the pyrite reduction percentage, sticking ratio, phase composition, and microstructure of the reduction products were examined using chemical, XRD, and SEM analyses. The results demonstrated that, when agitated, modifying the hydrogen concentration and spatial velocity of the gas significantly enhanced the reduction of pyrite in the presence of alkaline oxide and increased the reduction efficiency. A hydrogen concentration of 37.5% and spatial velocity of the gas of 0.115 m·s−1 were the ideal values, respectively. In addition, kilogram-scale experiments were performed to confirm the viability of the approach.