Multilayer porous aluminosilicate ceramic

Abstract

Multilayer aluminosilicate materials used for treating drinking water were investigated. The basic results of the experimental studies obtained in developing the process conditions for fabrication of aluminosilicate filter elements are reported.Porous ceramics are widely used for technologies for treating liquids and gases. Ceramic filters are used for mechanical and biological treatment of water, treatment of liquids in the food and pharmaceutical industry, and for capturing valuable and toxic components in gaseous systems.Most multilayer filter ceramics are molded according to the following principle: one or more filtering layers of fixed porosity are applied on a macroporous support. The macroporous base provides for mechanical strength and has high permeability in sufficiently intensive flow of the filtered medium [1,2].Since application of the filtering (membrane) layer directly on a large-pore base is not always effective, an intermediate layer (mesolayer) is formed first. It can reduce clogging of the selective layer by small particles and serve as its support. The mesolayer should smooth the internal pressure differential in the membrane layer, reducing the filtered medium flow resistance.The membrane layer is responsible for the selectivity of the process and limits its productivity.An analysis of the published data shows the promise of using multilayer porous ceramic materials for production of filter elements based on a set of output -treatment quality characteristics. At the same time, the problem of increasing the work life of filter elements while preserving output and porosity is becoming acute. We investigated the effect of the conditions of molding the filter layers on the performance characteristics of multilayer aluminosilicate filter elements.The technology for manufacturing multilayer filter elements from aluminosilicate powder consisted of the following operations: mixing the initial components, molding and sintering the stock for the bases of the filter elements, fabrication of slip, and application of filtering (intermediate and membrane) layers followed by sintering.Aluminosilicate powder, kaolin raw material, and a blowing agent were used as the initial components for fabricating the bases of the filter elements.The large-pore bases of the filter elements were molded in a radial molding unit that ensured uniform compression of the stock over the entire length [3]; sintering was conducted in an electric furnace for sintering ceramic materials at a temperature of 1150°C. Aluminosilicate powder separated into 10 -50, 50 -100, 50 -200, and 100 -200 mm fractions was used for application of the filtering layers. The membrane layer was molded with the same powder with a particle size of less than 10 mm. The studies were conducted on cylindrical samples with an external diameter of 45 mm, height of 53 -56 mm, and wall thickness of 4 -5 mm. The open porosity of the materials was determined with the method reported in [1], and the pore size corresponded to GOST 26849-86.The lifetime of the filter ...

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