Verfahren zur Verbesserung der Durchsatzgeschwindigkeit von Perlit-Filterhilfsmitteln

1,191,972. Perlite filteraids. GREFCO Inc. 26 Jan., 1968 [13 Feb., 1967], No. 4332/68. Heading C1A. The flow ratio characteristics of perlite filteraids is improved by treatment with a solution of an alkali metal silicate followed by heating below the fusion point of the filteraid to remove the solvent. The silicate may be sodium, potassium or lithium silicate and has a weight ratio SiO 2 : alkali metal oxide of greater than 1À5:1, preferably 2-4:1 and is used in an amount between 0À5 and 5% by weight of the filteraid. The solvent may be water, an alcohol or a ketone. The filteraid is uniformly wetted and mixed with the solution in, for example, paddle mixers, rotary mixers or vessels in which the filteraid is fluidized or otherwise conveyed into air and into which the solution is injected. The heating temperature may be 500-1000‹ F. The final product may be agitated to break up the agglomerates.