Compositions: ceramic – Ceramic compositions – Glass compositions – compositions containing glass other than...
Patent
1980-06-06
1982-06-01
McCarthy, Helen M.
Compositions: ceramic
Ceramic compositions
Glass compositions, compositions containing glass other than...
65 22, 65 214, 106 75, 106 97, 106288B, 501155, C03C 1100
Patent
active
043329071
DESCRIPTION:
BRIEF SUMMARY
CROSS REFERENCE TO RELATED CASE
This application is related to the commonly assigned, copending United States application Ser. No. 196,552, filed June 2, 1980, entitled "BLOWING AGENT FOR PRODUCING GLASS FOAM FROM PULVERIZED GLASS AND MANUFACTURING PROCESS THEREOF", and listing as the inventor OTTO ANTON VIELI.
The invention relates to a granulated foamed glass, produced by furnace blowing, as well as to a process for the production thereof.
Some processes are already known (cf. Swiss Patent Specifications Nos. 426,601 and 473,741; U.S. Pat. No. 3,321,414) for producing granulated foamed glass from glass powder by addition of a blowing agent which is releasing gas at higher temperatures. Such granulated material is mainly used as a component in lightweight concrete.
Further, a process for producing foamed products from silica gel is known (cf. French Published Application No. 2,242,561), wherein silica gel, without any additional agent, is pre-baked at 500.degree. to 900.degree. C., whereafter baking is completed at 1000.degree. to 1450.degree. C. Depending on the raw material used and the more costly production, the products obtained are considerably more expensive than granulated foamed glass, so that their use is restricted. They are used where, for chemical or thermic reasons, an essentially water-free silicon dioxide is needed.
It has been proved by tests that the compressive strength of such granulated foamed glass mentioned above increases almost linearly with the number of cavities per unit of volume produced in the granulated material by blowing. So, e.g., for 10.sup.6 cavities per cm.sup.3, a compressive strength of 120 kg/cm.sup.2 was found, whereas for 0.3.times.10.sup.6 cavities per cm.sup.3 a compressive strength of only 40 kg/cm.sup.2 was found.
It is the object of the invention to produce granulated glass foam which has a considerably improved compressive strength, as compared with granulated glass foam known so far, and which can be used as a filler for plastics as well as for lightweight concrete.
The granulated glass foam, produced by furnace blowing, in accordance with the invention is characterized in that it has a granulometry of 0.2 to 3 mm, 10.sup.6 to 10.sup.7 cavities per cm.sup.3, and a bulk density of 100 to 500 g/liter, and that the diameter of the largest cavities essentially is smaller than 0.1 mm.
Appropriately, the cavities are by the majority, and preferably essentially exclusively, closed cells of the same order of magnitude.
It may contain, besides glass, in addition up to 85% by weight of pumice, lava and/or tuff.
A further subject matter of the invention is a process for producing such granulated foam glass, which is characterized in that the raw materials are ground down to a powder, that this powder is mixed with an organic and/or inorganic blowing agent releasing gas in the heat, that granules having a diameter of 0.1 to 1.5 mm are formed from this mixture, and that these granules are heated in a fluidized bed furnace or a vibrating furnace for 5 to 180 seconds to 600.degree. to 900.degree. C., whereby the obtained granulated glass foam is removed from the furnace before the small cavities primarily formed by the blowing had time to combine into larger cavities to a considerable extent.
Appropriately, glass powder is produced by melting glass wastes, blowing the melt into glass fibers, and grinding the glass fibers so obtained.
As a blowing agent, preferably use is made of a colloidal dispersion comprising water, water glass, and an organic hydrocarbon compound soluble in water glass, preferably glycerol, and preferably also an alkali bentonite, particularly sodium bentonite (cf. Swiss Patent Application No. 10,441/78-1).
In carrying out the process according to the invention, preferably the raw granules together with a parting agent, e.g. aluminium oxide, metallurgical alumina, fireclay, bentonite or a mixture of bentonite and fireclay, are preheated in a furnace or on a drying belt to 450.degree. to 650.degree. C., and thereafter blown in a fluid bed furnace or a
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patent: 4143202 (1979-03-01), Tseng et al.
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Webster's Third New Int'l. Dictionary-(1976), p. 1780, "Pozzolana".
Kleeman Werner W.
McCarthy Helen M.
Millcell AG
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