Beneficiation of Coarse Coal Ore in an Air-Fluidized Bed Dry Dense-Medium Separator

The beneficiation of different size fractions (+5, -31mm) of coal using an air-fluidized bed dry dense-medium separator with silica/zircon sands as the fluidizing-bed medium has been studied. Particle size and bed height were found to strongly influence the efficiency of separation with the dry dense-medium separator. An increase in bubble size associated with increase in bed height to 15 cm results in density variations within the bed that increase the probable error for deeper fluidized beds for the smaller particles up to 0.19 from 0.06 for the shallower 10 cm bed. Good agreement was found between the theoretical yield and ash content obtained from washability curves (produced from conventional float/sink tests) and the actual yield from the dry fluid bed separation for the bulk coal sample. A comparison with industrial coal-washing unit operations indicates that dry dense-medium separations are a strong candidate as an energy-and resource-efficient alternative process.