Iron Recovery from Red Mud Using Carbothermic Roasting with Addition of Alkaline Salts

Red mud is a hazardous waste of alumina production by the Bayer method, which can be used for recovery of valuable elements such as iron, aluminum, titanium, and scandium. In this study, carbothermic roasting of red mud followed by dry or wet magnetic separation was applied with addition of alkaline salts to enhance iron extraction. A comparative influence of the use of sodium and potassium carbonates and sulfates, as well as the effects of roasting temperature and amounts of the additives on iron recovery and the iron concentrate grade were studied experimentally on two industrial red mud samples. The general mechanism of the roasting process in the presence of alkali metals was proposed in terms of temperature and iron extraction. Influence of the grinding fineness of the roasted samples and magnetic field strength during wet magnetic separation on iron extraction was also studied. It was shown that the addition of sodium and potassium carbonates and sulfates during carbothermic roasting of red mud improves the magnetic separation of metallic iron. The composition and microstructure of the separation products were examined, and their possible application was discussed.