Study on particle dynamics in different cross sectional shapes of air dense medium fluidized bed separator

Dry coal washing is gaining popularity on account of its ability to produce clean coal without the use of water which is becoming to be a costly resource for beneficiation. Air dense medium fluidized bed separation (ADMFBS) is one of the dry beneficiation techniques which is used for cleaning of coal. Fine magnetite particles are used as medium to make pseudo-fluid by fluidization method. The effectiveness of ADMFBS depends on stability of the fluidized bed. In the present work, an attempt has been made to study the stability characteristics of different cross-sectional shapes of fluidized bed having same cross-sectional area. Different indicators like fluidization index, particulate expansion function, pressure drop of bed and distributor, minimum fluidization and bubbling velocities were used to characterize the stability of fluidized bed. The effect of different operating and design parameters on the homogeneity and stability of the fluidized bed was studied. It was observed that cross sectional shape of the fluidized bed column has a significant effect on the stability of the bed. Moreover, rectangular cross-sectional shape provides better stability properties compared to square or circular shape.