Microwave roasting desulfurization pretreatment of high-sulfur bauxite and high-pressure dissolution performance of roasted ore

In this paper, microwave roasting method was used to study the desulfurization effect of high-sulfur bauxite, and the roasted ores after roasting and desulfurization were dissolved by Bayer method, and the influence of microwave roasting conditions on the dissolution rate of alumina was studied. The results showed that as for microwave roasting desulfurization of high-sulfur bauxite, its roasting temperature had a more significant effect on the desulfurization rate than the roasting time. When the roasting temperature increased from 100 ℃ to 600 ℃, the desulfurization rate could increase by about 30% on average. When the time was extended from 2 min to 20 min, the desulfurization rate only increased by about 12% on average. Roasting at 600 ℃ for 20 min could remove the total sulfur content of bauxite from 3.875% to 0.223 5%, and the desulfurization rate reached 95.11%. At the same time, the microwave roasting temperature had a significant effect on the dissolution rate of alumina. As the microwave roasting temperature increased, the relative dissolution rate of alumina tended to increase first and then decrease. When the microwave roasting temperature was 400 ℃, the relative dissolution rate of aluminum in the roasted ore reached the maximum up to 94.77%; when the temperature was higher than 400 ℃, a large amount of corundum (Al₂O₃) phase would appear in the roasted ore, which was the main factor leading to the decrease of the relative dissolution rate of alumina.