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With vacuum filtration the following apply: For dewatering the effluent (drainage) residue the concentration of the original suspension should be not less than 700 g/liter. The suction method can be used to dewater only residues based on chamotte dust or mixtures of chamotte and clay (not more than 20%); on the drum vacuum filter even with a mixture of chamotte and clay (not more than 20%) we obtain unsatisfactory results. To dewater suspensions containing chamotte and clay dust it is possible to use vacuum-filters with a residue feed using the overflow method, but such vacuum-filters are not being made by Soviet industry. Vacuum filtration as a method of dewatering residues from drainage contaminated with chamotte and clay is not recommended. Using centrifuging: The residues of the effluents can be dewatered on centrifuges; it is best to dewater residues formed from the coagulation of drainage water than residues formed from noncoagulated drainage. Centrifuging is affected by the nature of the formation of the original material. It is necessary to continue the research into laboratory and production centrifuges.

The residue formed from effluent contaminated with chamotte dust, with coagulation and without coagulation, is thoroughly dewatered on vacuum equipment with concentrations of more than 700 kg/m3 of suspended particles in the residue. Residues obtained from effluent contaminated with mixtures of chamotte and clay dust in the ratio 4∶1, 1∶1, and 1∶4 are dewatered less effectively than chamotte residues. The residue from a mixture of chamotte and clay 4∶1 is dewatered with a minimum concentration of 809 kg/m3; the residue from the mixture of chamotte and clay 1∶1 can be satisfactorily dewatered only with a high vacuum (640 mm Hg) and with a filter cycle time longer than that used in existing equipment. With a filter cycle of 30 min the thickness of the skin of uncoagulated residue was 13 mm. The coagulated residue from a mixture of clay and chamotte 1∶1 even after 14 days holding had too low a concentration, and in practice cannot be dewatered on a vacuum filter. The residue from mixtures of 1∶4 chamotte and clay is dewatered very ineffectively. The thickness of the cake with a filter cycle time of 20 min for uncoagulated residue was only 4 mm.