Enhancement of colloidal filtration: a new combined approach based on cake and suspension destabilization

Abstract

Pressure and vacuum filtration experiments using A16SG alumina with and without homogenization of formed cake and suspension are carried out. Homogenization involving mixing of formed cake with the suspension on top of the cake enhances filtration process performance in terms of reduction in filtration time without any alteration in the equilibrium solids volume fraction. A model is developed and validated based on the Mean-Phi model of pressure filtration to simulate the filtration behavior in the presence of continuous and intermittent homogenization. It is demonstrated that a single batch pressure filtration experiment is sufficient to provide the necessary information to simulate an enhanced pressure filtration process involving homogenization. Simulations for situations involving increasing numbers of homogenization and continuous homogenization are also carried out. Advantages regarding time and equilibrium solids fraction can be availed where homogenization along with change in the state of suspension aggregation by using additive(s) or pH change is carried out. Under such a scheme, a filtration process should start with a flocculated/aggregated condition along with mixing. With progress of the process, the suspension should be gradually converted to dispersed type by modulating the slurry chemistry, to achieve a maximum equilibrium solids volume fraction.