Glass manufacturing – Processes – With shaping of particulate material and subsequent fusing...
Patent
1991-04-29
1992-06-23
Lindsay, Robert L.
Glass manufacturing
Processes
With shaping of particulate material and subsequent fusing...
65136, 65DIG4, C03B 3704
Patent
active
051239418
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a method of producing mineral wool, wherein mineral raw material is introduced into a melting unit, preferably a cupola furnace, for heating the mineral raw material in such a manner that molten mineral material is formed on the bottom of the melting unit, whereafter the molten mineral material is discharged from the melting unit, heated further and introduced along at least one tapping chute into a spinning machine in which the mineral material is converted into fibre form. The invention is also concerned with an apparatus for the production of mineral wool, comprising a feeding device, a melting unit, preferably a cupola furnace, a transport device comprising a tapping chute, an additional heating device and a spinning machine, the feeding device being intended for the supply of mineral raw material into the melting unit, the melting unit for heating the mineral material into molten mineral material, the transport device for transporting the molten mineral material from the melting unit to the spinning machine, the additional heating device for further heating the molten mineral material from the melting unit prior to its introduction into the spinning machine, and the spinning machine being intended for producing mineral material in fibre form.
In the production of mineral wool it is important that the molten material to be introduced into the spinning machine is homogeneous, which requires that the melt should have accurately defined temperature and viscosity as well as a composition such that it is formed into fibres of desired length and thickness in the spinning machine. In practice, even and homogeneous raw materials are used in an attempt to achieve a homogeneous melt, whereby the viscosity of the melt depends on temperature which should kept as even as possible.
The cupola furnace, which is the most frequently used melting unit in the production of mineral wool, does not, however, melt the raw material evenly, which is partly due to the fact that the melt stays only about two minutes on an average on the furnace bottom before it is discharged from the furnace. Therefore it is not possible to obtain a homogeneous melt in the cupola furnace, which, however, is necessary for carrying out the spinning operation successfully. It is even more difficult to obtain a constant temperature in the melt before its introduction into the furnace since so called iron tappings have to be carried out intermittently during the process and since the molten mineral material cools when it flows in the tapping chute between the cupola furnace and the spinning machine. The cooling affects adversely the fibre formation properties of the molten mineral material.
The temperature of the melt from a cupola furnace normally varies from 1400.degree. to 1500.degree. C. with a melt composition of about 60% of Al.sub.2 O.sub.3 +SiO.sub.2. In a normal case, a temperature of about 1460.degree. C. is a preferred operating temperature for spinning.
It is known that instead of trying to at once obtain the right operating temperature, it is usually easier to first melt the material to a lower temperature ranging from 1400.degree. to 1460.degree. C. and then raise the temperature to the required operating temperature by supplying additional energy. This is carried out, e.g., by means of an intermediate container provided with an oil or gas burner, whereby the melt is heated by the hot flame primarily through radiation. However, such an intermediate container has to comprise a heat transfer surface of several square meters to be able to raise the temperature of 5 tons of melt by 100.degree. C. in one hour.
FI Patent Application 2943/68 discloses the use of an intermediate container connected between a spinning machine and a furnace in which the mineral material is to be melted. The intermediate container comprises an electrode furnace and its function is to eliminate variations in the composition of the mineral material. A problem with the intermediate container is that it has to possess a high capacity i
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Lauren Henning J. E.
Solin Peter A. H.
Lindsay Robert L.
Oy Partek Ab
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