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Technical Report

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Filter Cake Washing, Saturated Washing, Unsaturated washing


The washing of a solute from filter cakes was investigated for both saturated and unsaturated washing conditions. Systems used in this experimental study were 0.065 NaCl solution as the filtrate in an aluminum hydrate filter cake and 0.1 Normal HCL solution as the filtrate in a column packed with glass beads. The filtrate concentration as a function of the flow rate of wash water and of the volume of effluent from the packed bed was measured. The amounts of filtrate removed from the bed during saturated washing, and washing employing repetitive steps of saturation followed by evacuation were compared. Also, the amounts of wash water required to lower the filtrate concentration to essentially zero were contrasted. It was determined that the saturated wash condition was more efficient in removing the filtrate from compressible cakes, while the reverse was true for porous, incompressible cakes. Computer programs were developed to simulate both saturated and unsaturated washing conditions.

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