China Nonferrous Metallurgy

There is still 44.93% of iron in the tailing, which is generated during the treatment of high-iron bauxite by the novel reductive Bayer process. This study adopted a magnetization roasting-magnetic separation process for enhanced recovery of Fe-bearing minerals in the tailing. The effects of process parameters on the products were investigated through single-factor experiments. The roasted products, magnetic concentrate, and tailings were characterized to analyze the magnetization roasting behavior and magnetic separation behavior. The main conclusions are as follows: the main mineral in the tailings is hematite, with particle size mainly distributed in the range of 0~10 μm and an average particle size of 1.98 μm. The magnetization roasting results shows that prolonging roasting time and temperature both promote the directional conversion of hematite into magnetite in the tailing. Under the roasting temperature of 600°C and roasting time of ≥40 min, the dominant phase in the product is magnetite. At a grinding fineness of D(90) = 16.36 μm and a magnetic field intensity of 1 000 Gs, a concentrate with yield of 57.99%, iron grade of 52.57% and iron recovery of 70.69% was obtained, which increased the resource utilization ratio of high-iron red mud from 55% to 80%. The incomplete recovery of magnetite is attributed to the agglomeration of fine particles during grinding, which hinders the efficient separation of magnetite from aluminosilicate minerals. In subsequent work, the introduction of a dispersant during grinding is being considered to further improve the iron recovery in the magnetic concentrate.