Influence of high-iron bauxite on phase composition, microstructure, and properties of bauxite-based homogenized grogs

Abstract

Investigation on the occurrence state of Fe₂O₃ in bauxite and its effect on the bauxite-based homogenized grogs (BHG) is crucial for the utilization of high-iron bauxite resources. BHG with different Fe₂O₃ contents incorporated in the form of high-iron bauxite was prepared by maintaining the Al₂O₃ content around 82%. The effect of high-iron bauxite addition (0, 25, 50 75, 100 wt.%) on the phase composition and microstructure evolution was studied using X-ray diffractometer, scanning electron microscope, and Factsage software. The results show that part of the Fe₂O₃ in BHG is dissolved into crystalline phases, while the other part is present as a glass phase. The addition of high-iron bauxite, coupled with a reduction in the SiO₂ content, results in a rise in the corundum content within BHG from 55.0% to 93.6% and a decrease in the mullite content from 44.0% to 2.8%. This change results in a decline in the refractoriness under load of T0.6, dropping from 1593.5°C in the sample without high-iron bauxite to 1430.7°C in the sample with 100% high-iron bauxite addition. The microstructure of BHG evolves from the interconnected network of corundum and mullite phases to the structure of corundum bonded by the glass phase.