Pretreatment Of Bauxite With High Sulfur And Organics And Recovery Iron From Red Mud Technology Research

Pretreatment technology of bauxite with high sulfur and organics and utilization of red mud were studied, both of which were widely noted in the alumina industry. The main point includes the following two parts:(1) To address the problem of the high sulfur and organics of bauxite in the bayer process of alumina production in Guizhou and other places in China, in which the sulfur content was more than1.2%and the organic content was more than0.2%, roasting pretreatment technology was put forward. The effect of roasting condition on sulfide and organics removal efficiency of the bauxite was researched scientifically. The alkali dissolution properties of the bauxite and sedimentation performance of red mud after roasting process were evaluated. The results show that because of diaspor dehydration being avoided at low roasting temperature, the aluminium dissolution rate was not affected when the bauxite roasted at450-620℃. The organic content of the bauxite roasted at the temperature higher than450℃was less than0.03%. At the same time, red mud sedimentation performance was improved due to the removal of organics. In short, roasting pretreatment of bauxite at low temperature can remove sulfer and organics efficiently, and improve red mud sedimentation performance without affecting the aluminium digestion.(2) Due to the high iron content of red mud limiting its large-scale application in producing refractory materials, we put forward that roast the red mud mixed with pyrite (FeS2) under anaerobic condition to transform hematite (Fe2O3) in red mud into magnetite (Fe3O4), and separate magnetite by magnetic separation technology to reduce iron content of red mud and realize the recycling of useful resource. The reaction mechanism of the transformation process is discussed in detail with thermal analysis technique, which confirmed that the decomposition products (FeS and S) of pyrite in anaerobic condition could transform hematite to magnetite. The lowest roasting temperature was600℃, and the minimum ratio of pyrite and hematite was1:16. Red mud samples from different production technology in domestic were tested in the application research and the effect of iron recovery could meet the requirement.