Compositions: ceramic – Ceramic compositions – Pore-forming
Patent
1987-07-08
1989-04-25
Dixon, Jr., William R.
Compositions: ceramic
Ceramic compositions
Pore-forming
501155, 119 1, 252 62, C04B 3800
Patent
active
048248100
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to highly porous ceramic material for adsorption and absorption purposes, particularly for animal litter or bedding, a process for the production thereof and the use thereof.
There is a continual need for highly porous, non-rotting materials for adsorption or absorption of liquids and gases and more particularly for use as animal litter.
Calcium silicate granules have hitherto been advantageously used for this purpose as described in European Pat. No. 00 13 935 and 0 014 343, as well as German Pat. Nos. 31 21 403 (U.S. Pat. No. 4,509,457) and 29 02 079 (U.S. Pat. 4,275,684)
The known calcium silicate granular material advantageously has a microporous structure which, as a result of its capillary action, is able to absorb oleophilic and hydrophilic liquids, and also gaseous substances.
The known calcium silicate granular material with a microporous structure from finely ground silicon dioxide-containing material, such as quartz flour, is intimately mixed with calcium oxide-containing material, such as lime and water, accompanied by the addition of an anionic surface-active agent (surfactant). It is then foamed, followed by autoclave hardening and subsequent crushing with classification, then drying and optionally cooling. The absorbent produced according to this known process has proved highly suitable.
The object of the present invention is to provide a material or adsorption and absorption purposes, particularly for use as animal litter which, whilst retaining the favorable characteristics of the known, aforementioned material, can be produced less expensively and with greater flexibility with respect to product parameters, and particularly by means of a continuous process.
According to the invention, these advantages are achieved with a highly porous ceramic material, which is characterized by a porosity of 50 to 300% preferably 200 to 250%; a water absorption capacity of 50 to 200%, preferably 100 to 150%; a pH-value in the range 5 to 9, preferably 7 to 8; a bulk density of 400 to 700 g/l; an internal surface (BET-N.sub.2) between 20 and 200 m.sup.2 /g, preferably between 80 and 150 m.sup.2 /g; which can be produced by firing a foamed mixture of clay or clays, optionally containing aggregate or aggregates, anionic or cationic surfactant or surfactants and deflocculant or deflocculants. The process according to the invention for producing such porous ceramic materials is characterized by mixing 45 to 80 parts by weight of clay, 0 to 50 parts by weight of additives with a high specific surface, 15 to 30 parts by weight of water and 0.01 to 0.03 parts by weight of deflocculant; preparing a foamed mixture accompanied by the addition of surfactants; shaping and drying the foamed mixture to give shaped clay members; crushing the dried shape clay members; screening the crushed shape clay members and returning the fines to the starting mixture; and firing the crushed shaped clay members with a chosen particle size range at a product temperature in the shaped clay member between 600.degree. and 1000.degree. C., preferably 700.degree. to 800.degree. C.
It is particularly advantageous to use as the aggregates inorganic or organic materials with a high specific surface, such as e.g. calcite, quartz sand, dolomite, feldspar, chomatte, kieselguhr, sepiolite, bentonite and/or organic materials, such as sawdust or coal.
As a result of the process according to the invention it is possible to economically produce highly porous ceramic products with porosities greater than 100% and preferably 200 to 250%, whereby the pore size and type can be significantly controlled.
Advantageously the time from clay preparation up to the fired product in the case of porosities over 100% amounts to up to 2 hours and less, the short process time largely resulting from the brief drying and firing time.
Normally the process according to the invention takes place in such a way that clay is mixed with water and deflocculant to give a low water content, thixotropic suspension. This suspension can be produced with
REFERENCES:
patent: 1963030 (1934-06-01), Powell
patent: 2543987 (1951-03-01), Ramsay
patent: 3993498 (1976-11-01), Koekemoer
patent: 4123284 (1978-10-01), Rieger
patent: 4275684 (1981-06-01), Kramer et al.
patent: 4318996 (1982-03-01), Magder
patent: 4424280 (1984-01-01), Malric
patent: 4509457 (1985-04-01), Durbye
Modde et al., American Ceramic Society Bulletin, vol. 47/3), (Mar. 1968), pp. 264-5.
Lang Rudiger
Meyer Bernd
Dixon Jr. William R.
EFFEM GmbH
Group Karl
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