Pore structure and permeability of filter cake in coal slurry filtration

Abstract

ABSTRACT The dewatering performance is dependent on the understanding of the pore structure and permeability of the filter cake in coal slurry filtration. In this paper, filter cakes were prepared from three different coal samples under the filtration pressure of 0.6 MPa with different filtration times, and the pore distribution and pore complexity of filter cakes were investigated using image processing technology and fractal theory, and the calculation of permeability of filter cakes were carried out on the basis of Darcy’s law. With an increase in filtration time, the filter cake is characterized by smaller pore diameter and porosity, narrower pore diameter distribution, and greater fractal dimension. The relationship between the permeability of filter cake and its thickness in filtration process obeys first-order exponential decay, and it could be expressed by . The critical thickness of filter cake is proposed and calculated using the maximum curvature point of K(Lc) curve, which provides theoretical support for achieving high-efficiency filtration of coal slurry.