China Nonferrous Metallurgy

The form of sulfur in high-sulfur bauxite is complex， mainly sulfide. If it is not effectively desulfurized， it will not only cause corrosion and loss to the production equipment， but also reduce the quality of alumina products. At present， the desulfurization method has the problems of high cost， high energy consumption， limited desulfurization efficiency and environmental pollution. In this study， a method of base hydrogen reduction roasting desulfurization was proposed. During the roasting process， calcium oxide in the alkaline medium reacted with sulfide FeS2 to form calcium sulfide （CaS）， which played a role in desulfurization and sulfur fixation. At the same time， under the reduction of hydrogen， Fe2+ is further promoted to generate elemental iron （Fe）， which can be recovered. The influence of process parameters on the desulfurization effect was investigated， and the microstructure and crystal structure of the ore were analyzed by various characterization techniques to verify the roasting desulfurization mechanism. The results show that the optimal process parameters are reduction temperature of 700℃， reduction time of 80 min， alkalinity of 1 and hydrogen flow rate of 1. 4 m3 /h. Under these conditions， the reduction rate of high-sulfur bauxite reaches 95. 83%， and the desulfurization rate reaches 99. 72%. SEM and EDS characterization results show that the surface of the roasted ore is densified， and the removal effect of sulfur is significant， which verifies the desulfurization mechanism of the method. Compared with the traditional pretreatment process of high-sulfur bauxite， the base hydrogen reduction method increases the recovery of iron resources while effectively desulfurization and sulfur fixation， which provides an economic and feasible technical way for the clean and efficient utilization of high-sulfur bauxite.