Vibro-fluidization of fine boron nitride powder at low pressure

At low pressure (less than atmospheric), a vibro-fluidized bed was constructed for the fluidization of fine BN powder. This powder exhibits the characteristics of a Geldart C type powder, with significant cohesive behavior. Fine BN particles form lightly bonded agglomerates that remain in the bed during fluidization. The agglomerate size was measured in situ during fluidization using a pulsed laser coupled with a CCD camera. An increase in the vibrational force causes a corresponding decrease in the size of the agglomerates. Vacuum level does not affect agglomerate size. A balance of forces model is used to derive an equation that predicts the minimum fluidization velocity (umf), taking into account the forces due to vibration, cohesion, gravity and drag.