Filter cake compaction by oscillatory shear

Abstract

ABSTRACTIn cake filtration, low values of residual moisture are desirable. This can be achieved by filter cake compaction. The present work proposes a new method for filter cake compaction by applying oscillatory shear superimposed with normal pressure. An experimental setup for the application of oscillatory shear is presented and the influence of oscillation frequency and displacement as well as the number of cycles and the magnitude of superimposed normal pressure on the compaction behavior is investigated. It was found that the reduction of residual moisture with number of cycles follows an exponential decay law. The variation of displacement implies that displacement and oscillation frequency are not independent parameters, but the resulting mean shear rate determines the degree of compaction that can be reached. The compaction behavior with frequency or shear rate, respectively, was strongly influenced by the superimposed normal pressure. The effect of oscillatory shear on the compaction of the filter cake was compared to the compaction obtained by applying solely mechanical pressure. By applying oscillatory shear, a significant reduction of compaction pressure needed to obtain a certain value of residual moisture could be obtained.