Fluidization of powders showing degrees of cohesiveness—II. Experiments on rates of de-aeration

Experiments have been done on the de-aeration characteristics of 18 powders with mean sizes of 3–125 μm and densities 364–5000 kg m−3. Powders in Geldart's Group A de-aerate at a constant rate analogous to sedimentation in a liquid, and a standardised de-aeration time has been correlated with the powder and gas properties. Cohesive Group C powders de-aerate exponentially with time similar to the final solids consolidation stage observed in solid/liquid systems.