Compositions: ceramic – Ceramic compositions – Glass compositions – compositions containing glass other than...
Patent
1998-10-26
2000-06-13
Group, Karl
Compositions: ceramic
Ceramic compositions
Glass compositions, compositions containing glass other than...
501 28, 501 29, 501 36, 65469, 65144, 65 19, C03C 602, C03C 608, C03C 1306
Patent
active
060749679
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention concerns the production of rock wool.
BACKGROUND TO THE INVENTION
Rock wool (referred to incorrectly as mineral wool in our earlier British Patent Applications Nos 9600164.9 and 9614048.8) comprises glassy fibres having good thermal insulation properties, which may be in the form of a mat or loose wool or may be compressed to form eg boards and pipe sections. Rock wool is used as a growing medium in the technique of hydroponics, and is used in the construction industry as a thermal and acoustic insulating material, eg under the name Rocksil (Rocksil is a Trade Mark of Owens Corning).
Rock wool is typically produced by smelting minerals containing silica, alumina, magnesium, calcium and iron, which are mixed with coke fuel. The mixture is smelted to a high temperature, about 1500.degree. C., generally in a special furnace known as a cupola. The resulting melt is blown in a fibrous form over rollers. It is a characteristic of the known production process that as much as 30% of all production is sub-standard and is in globular or spherical form, known as shot or overshot, rather than the desired fibrous form. The shot is relatively dense and sandy in consistency, and its particulate nature is such that it cannot be mixed with the cupola input material for reprocessing. This arises because the cupola based process only functions properly when the size of the raw materials is such as to permit the free passage of air and gases through the cupola during the smelting process. As a result, the shot currently constitutes a non-reusable waste material that requires disposal.
At present waste rock wool shot is mainly disposed of by landfill, but in the current climate of rising environmental standards and the imminent increase in the cost of landfill, this approach is becoming less attractive.
It has been proposed to compress the waste material into solid blocks such as briquettes, weighing 125 to 250 grams or more, but the sandy consistency has meant that the resulting briquettes have possessed very poor strength and have tended to crumble without the addition of a binder. Binder materials so far proposed comprise molasses, dextrin and natural latex, which also create further environmental problems and do not contribute thermal stability. Moreover, the cost of these binder materials is not insignificant which would add to the cost of the overall process and would inevitably be reflected in the price of the rock wool.
The present invention is based on use of alternative binder materials that enable, inter alia, an alternative approach to be taken to the treatment and handling of rock wool shot.
SUMMARY OF THE INVENTION
In one aspect, the present invention provides a method of processing material for use in production of rock wool, comprising providing the material in finely divided form; mixing the finely divided material with a fibrous binding agent; and forming the mixture into solid blocks.
The resulting blocks (lacking fines) are in a form suitable for use in the production of rock wool, and may be fed to a smelting furnace, together with other ingredients as appropriate, for processing in conventional manner. On heating in the furnace, the blocks melt without breaking up before entering the melt zone, releasing the ingredients in an appropriate form for production of rock wool.
In a further aspect, the present invention thus provides a method of producing rock wool, wherein at least one of the raw materials is supplied to the smelting furnace in the form of solid blocks comprising an agglomerate of the raw material in finely divided form, admixed with fibrous binding agent.
The invention also includes within its scope a solid block comprising an agglomerate of material for use in the production of rock wool, in finely divided form, admixed with fibrous binding agent.
The material may be any appropriate ingredient for rock wool production. If the material is not initially in finely divided form, the material is suitably processed as a preliminary step to produce the ma
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patent: 4430125 (1984-02-01), Hascic
patent: 4518432 (1985-05-01), Hess et al.
patent: 4617045 (1986-10-01), Bronshtein
patent: 5100840 (1992-03-01), Urabe et al.
patent: 5472917 (1995-12-01), Talling et al.
Asset Associates Limited
Group Karl
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