Plastic and nonmetallic article shaping or treating: processes – Pore forming in situ – Of inorganic materials
Patent
1987-06-15
1989-05-16
Dixon, Jr., William R.
Plastic and nonmetallic article shaping or treating: processes
Pore forming in situ
Of inorganic materials
252378P, 252378R, 106DIG2, 501 84, B29C 2760
Patent
active
048307971
DESCRIPTION:
BRIEF SUMMARY
CROSS REFERENCE TO RELATED APPLICATIONS
This application is a National Phase Application corresponding to PCT/HU86/00028 filed 8 May 1986 and based, in turn, upon Hungarian application No. 1732/85 filed 8 May 1985.
FIELD OF THE INVENTION
The invention relates to a process for the production of granular material for use in industry and agriculture, such as in construction, as a synthetic material, in furniture, in mining, for blasting, in metallurgy, in fire-fighting, for electrical insulation, in heat and sound insulation, for filtration, etc.
The process according to the invention is suitable for the production by heat treatment of the granular material from starting materials available in large quantity in nature and/or exploitable at a low cost, e.g. from natural silicates, oxide minerals and intermetallic compounds, the beneficial properties of which provide versatile applicability and manifold value in use. The steps of the process are aimed at developing gas formation, and evolution of gas from the starting material with thermal load pulses, to make the starting material foamy. The material recovered from the heat treatment space is a granular material containing closed bubbles and gas cells. The size and number of the gas cells and the quantity, thickness of the surrounding material are variable over wide ranges, and can be planned in advance depending on the quality and grain size of the starting material and on the operating conditions of the heat treatment process.
BACKGROUND OF THE INVENTION
There are heat treatment processes in practice for the production of lightweight materials from natural or artificial silicates. One of the best known forms of such materials is the expanded perlite used more and more extensively today for its advantageous properties. Upon expansion of the perlite, gas develops in the starting material, but the rate of development of the gas is such that closed gas cells are not evolved; rather the grains explode. For this reason expanded perlite is of an open-pore structure. This gives rise in undesirable properties such that its range of application--though it is very wide--cannot be extended to certain fields. Such undesirable properties include: low mechanical strength and hydroscopicity. On account of these two drawbacks, the expanded perlite can be used in construction and in the construction-material industry only to a limited extent.
Glass-like materials consisting of small or large grains has been required for solving several technical problems in the practice. The applicability of such materials would be even more advantageous, if the grains could be of closed pore structure, i.e. the cells are filled with gas. Materials having such properties can be produced in different ways, but the common characteristic of all the known processes is that they are complicated and expensive and treatment of the surface is difficult. Thus these processes became economical only for special applications. The use of such materials in the construction industry is not profitable and not economical.
OBJECT OF THE INVENTION
The object of the invention is to provide a process for making a closed-cell product which meets the following requirements:
suitability for mass production,
yields a relatively inexpensive product from low-cost materials,
volume weight (bulk density), surface properties, and grain size which is variable within wide limits, or selectable in advance, depending on the field of application,
the material should not be hygroscopic,
the material should be heat- and fire-resistant,
the mechanical strength of the material should be relatively high, and the materials should be suitable for heat-, sound- and electrical insulation.
DESCRIPTION OF THE INVENTION
The object is achieved according to the invention by recognizing the fact, that if the material selected as the starting material has a chemical composition of which is similar to a glassy materials or a metal oxide mineral, but in raw condition contains constitutional water, or materials decomposing under hea
REFERENCES:
patent: 2021956 (1935-11-01), Gladney
patent: 2466001 (1949-04-01), Burwell
Hornyos Janos
Millei Gyula
Nemeth Laszlo
Wagner Otto
Dixon Jr. William R.
Dubno Herbert
Green Anthony J.
Myers Jonathan
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