Glass manufacturing – Processes of manufacturing fibers – filaments – or preforms – By slinging or rotary-centrifugal fiber distribution
Patent
1993-07-15
1995-11-21
Jones, W. Gary
Glass manufacturing
Processes of manufacturing fibers, filaments, or preforms
By slinging or rotary-centrifugal fiber distribution
65516, 65517, 65455, C03B 3705
Patent
active
054682746
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
It is known to make inorganic fibres from an inorganic melt using fiberising means comprising a set of rotors each mounted for rotation about a different substantially horizontal axis and arranged such that, when the rotors are rotating, melt poured onto the periphery of the top rotor in the set is thrown on to the periphery of the subsequent rotor (or onto the periphery of each subsequent rotor in sequence) in the set and inorganic fibres are thrown off the or each subsequent rotor.
This general process and apparatus can be used for different types of mineral melt. Success in the process depends critically upon the viscosity-temperature relationship and the surface tension of the melt at various stages in the process. Apparatus designed for a melt having one set of properties is wholly unsuitable for making fibres from a melt of a totally different properties.
2. Description of the Prior Art
In U.S. Pat. No. 4,238,213, Pallo describes the manufacture of ceramic fibres from such a fiberising means in which the set of rotors consists of two rotors that, in all the specific description, are described as having the same size and speed of rotation. In particular, the rotors have diameters of 150 to 300 mm and rotate at speeds of above 107 m/s and it is stated that these high speeds lead to fine average and effective fibre diameters than are obtained at lower speeds. However it is also stated that the process does lead to the presence of coarse shot in the fibre.
A particular problem with ceramic materials is that they do not melt until very high temperatures (typically around 1,800.degree. C.) but then change from a highly viscous state (at which they are too viscous to form fibres satisfactorily) to a highly fluid state (at which their viscosity is too low to form fibres) within a range typically of around 50.degree. C.
As a result, it is not practicable to operate such a process with more than two rotors since the melt on the third rotor would inevitably be too cool to form satisfactory fibres.
We are concerned with the production of mineral wool. Whereas aluminum silicate fibres consist of a minimum of 98% Al.sub.2 O.sub.3 and SiO.sub.2 and no more than 2% other oxides, the chemical composition of what we refer to herein as mineral wool is characterised by a large variety of oxides, where the sum of Al.sub.2 O.sub.3 and SiO.sub.2 is generally between 40 and 70%, and the rest is other common oxides from minerals, for instance CaO, MgO, Fe.sub.2 O, FeO, TiO.sub.2 or Na.sub.2 O, as described in U.S. Pat. No. 2,576,312 and in Danish Patent Application DK 4923/89. The raw material for this mineral wool, is normally composed of one or more of diabase, basalt, slag, lime-stone, dolomite, cement, clay, feldspart, sand or olivin or other relatively impure, usually iron-containing materials in which event the mineral wool is referred to herein as stone wool. Another type of mineral wool is glass wool, usually made from an iron-free melt containing expesive additives such as soda and borex. Both stone wool and glass wool can be produced at a much wider temperature range--about 200.degree. C.--typically 1,400 to 1,600.degree. C. Because of this fundamental difference in the melting and rheology properties and the demand for high output when making mineral wool, processes and apparatus suitable for ceramic fibres are not suitable for efficient and economic production of mineral wool.
Mineral wool, however, is made from rock (including slag) at lower temperatures and typically satisfactory formation of mineral wool fibres can be achieved through a range of as much as 200.degree. C. or more, typically 1,400 to 1,600.degree. C. Because of this fundamental difference in the melting and rheology properties, processes and apparatus suitable for ceramic fibres are not suitable for efficient production of mineral wool fibres.
Apparatus for making mineral wool fibres from a mineral melt of, for instance, slag or other stone comprises into mineral wool fibres and air supply m
REFERENCES:
patent: 2520168 (1950-08-01), Powell
patent: 2520169 (1950-08-01), Powell
patent: 2807048 (1957-09-01), Hedges
patent: 3159475 (1964-12-01), Chen et al.
patent: 4119421 (1978-10-01), Alenrot et al.
patent: 4433992 (1984-02-01), Debouzie et al.
Hoffmann John
Jones W. Gary
Rockwool International A/S
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