Obtaining of Pigment-Quality Magnetite from Sintering Process Red Mud

The limited availability of high-quality bauxite and, at the same time, the formation of a considerable amount of harmful red mud (bauxite residue) causes to develop cost-effective technologies for bauxite processing. Selective separation of iron from red mud allows solving this problem and producing marketable products in the form of pigment-quality magnetite. In this context, the possibility of the pigment-quality magnetite obtaining by the interaction of freshly precipitated iron hydroxide (III) of the sintering process red mud with ferrous iron ions in an alkaline medium is studied. It was found that the optimal parameters of the process are: temperature = 90°C; duration = 4 hours; a ratio of ferrous iron to stoichiometric quantity = 70 %. The yield of the magnetic concentrate under optimal conditions was 69.3 %, and the content of magnetite in concentrate was 47.7 %.