Dewatering of non-uniformly structured wet compacts under additional compressive pressure: Predictive model

Predictive model is developed to simulate the dewatering of non-uniformly structured wet compacts formed at different filtration pressures PF and then compressed under additional compressive pressure P-E > P-F. This model is based on the filtration-consolidation equation in which compressive pressure PS is replaced by the special power law theta-function theta(1/1-n ) = 1 + P-S/P-a = P* considering pressure dependence of the specific cake resistance, and transforming Darcy law to the linear form. Proposed model permits to cover industrially important dewatering processes, for which filtration pressure PF differs from the compression pressure P-E, and 0 <= P-F <= P-E. In the particular cases of P-F = 0 (uniformly structured semi-solid material) and P-E = P-F (filter cake formed and compressed at the same pressure) obtained analytical solutions are transformed to the previously obtained results. Several examples of the application of proposed model are presented for the highly and moderately compressible cakes (silica, activated sludge and CaCO3,). The profiles of 0- function and dimensionless compressive pressure P* are simulated and compared for different wet compacts based on the analytical and numerical solutions of the model. It is shown that the behavior of mechanical dewatering depends on the cake structure obtained after filtration. Consolidation ratio U of wet compacts with initially non-uniform structure formed by filtration differs from that of materials with initially uniform structure. Dryness of studied wet compacts d was also predicted based on the proposed model. (C) 2022 Published by Elsevier B.V.

Automated summary

A predictive model is developed to simulate the dewatering process of non-uniformly structured wet compacts under different filtration pressures and additional compressive pressure. The model takes into account the pressure dependence of the specific cake resistance and can cover industrially important dewatering processes. The study shows that the behavior of mechanical dewatering depends on the cake structure.