ABSTRACT
A common feature of all red muds is the presence of substantial levels of iron oxide. The iron oxide is not particularly valuable, but it reacts with the agents in most processing schemes, adding to their cost and complexity. As a result, many proposed red mud treatment schemes feature a preliminary iron-removal step. An approach proposed here is to reduce hematite to magnetite, which is ferromagnetic and can be recovered by low-gradient magnetic separation. This process would require low furnace temperatures, which would reduce energy costs and minimize interaction among the other constituents in the mud. The reduction of hematite in red mud to magnetite by varying the reduction temperature, reaction time and the choice and amount of reducing agents was investigated for three feed materials. It was determined that ferric iron is readily reduced to magnetite at temperatures below 500°C, and that sawdust and bagasse were more effective re-ductants than coal and charcoal.
