Influence of suspension concentration on cast formation time in pressure filtration

Expressions for the formation rate of an incompressible cast in batchwise pressure filtration are formally derived from Darcyʹs law and Kynch-theory for pure filtration and filtration with sedimentation and compared with experimental results from the filtration of submicron α-alumina dispersed in water. The influence of suspension concentration on the cast formation time is investigated numerically. A maximum cast formation time is found at a certain suspension concentration φs for pure filtration and a constant filling height. The value of the maximum cast formation time depends solely on the cast concentration if the filter resistance is negligible. For a constant final cast thickness, the cast formation time always decreases with increasing φs. The cast formation time in a filtration set-up decreases when particle sedimentation is important, especially when sedimentation and filtration have the same direction.