1990 Volume 23 Issue 4 Pages 485-490
An analytical method is presented for a variable-pressure/variable-rate process for expression of a semisolid material with medium resistance. It is assumed that the internal condition of expressed cake is uniquely determined by the instantaneous expression pressure and the amount of removed liquid at the moment, and is not related to the expression pressure history. This assumption is experimentally supported by the results of stress relaxation of expressed cake; an equilibrium cake stress is uniquely determined by the expression pressure and the average consolidation ratio at the instant of expression stoppage. Using these facts, the relation among instantaneous expression rate, expression pressure and amount of expressed liquid in the variable-pressure expression operation can be determined from equations for a constant-pressure expression process. Favorable agreement between experimental and calculated values was obtained for the expression of semisolid Sokla floc.
