Novel approach for the beneficiation of ferruginous bauxite by microwave heating

Abstract

Performing a magnetizing roast in a fur nace or kiln is a well-established technology. However, the use of microwave heat for the magnetization of hematite in the beneficiation of ferruginous bauxite is a new approach. This paper reports on an investigation of this procedure, which is followed by comminution and magnetic separation. The results of this investigation indicate that a nonmagnetic product containing 80% Al2O3 and 2.5% Fe2O3, with a recovery of 80% can be made from a crude bauxite or-e containing 55.9% Al2O3 and 5.6% Fe2O3. This product is suitable for refractory use. The mechanism is explained by the ability of the microwave radiation to heat specific points within the bauxite. These heat-specific points al-e at the location of iron minerals. In a reduced atmosphere, the microwaves promote faster conversion of the iron minerals to a magnetic phase, which improves the magnetic-separation process.