Centrifugal drum filtration: II. A compression rheology model of cake draining



A compression rheology model for the final capillary compression and draining stages of the batch centrifugal filtration of a compressible cake is presented. The initial stage of cake formation and drainage of the supernatant fluid have been treated in a companion paper up to the point tc, where the supernatant first contacts the top of the cake. The compressional rheology model uses the compressive yield stress py(ϕ), the hydrodynamic resistance R(ϕ), and the maximum capillary stress Pmath image(ϕ). Analysis of these final stages indicates that the system can remain fully saturated if the solids network can sustain the capillary stress and, if not, will partially unsaturate. The controlling parameters are elucidated and the state of the system for tc < t < ∞ is illustrated graphically for the previously treated model system. © 2005 American Institute of Chemical Engineers AIChE J, 2006