Dry Beneficiation of Coarse Coal Using an Air Dense Medium Fluidized Bed (ADMFB)

A theory of the dry separation of coal by density difference is proposed. The mechanism and efficiency of separation of coal particles in an air dense medium fluidized bed (ADMFB) according to bed density and the density distribution in the fluidized bed is studied. The results show that the uniform and stable fluidized bed can be formed at specific conditions. The maximum of relative errors of bed densities is only 2%, and the raw coal of 50 by 6 mm size can be separated effectively with a high recovery of clean coal and a separation precision characterized by Ep value of 0.03. Only a small amount of misplacement of material between the light and heavy products was found. The view of "misplacing effect of viscosity" and "misplacing effect of motion" was proposed to explain the experimental results satisfactorily.