MINERAL FIBRES

Abstract: Fibres with the following composition: SiO2 47-54 % by weight, Al2O3 4-7.5 % by weight, Fe2O3 1-8.5 % by weight, CaO 10-24.5 % by weight, MgO 10-21 % by weight, Na2O 0.1-10 % by weight, K2O 0.1-1.5 % by weight soluble in salt solutions.

Description: Mineral fibres The present invention relates to a novel type of mineral fibres. Conventional mineral fibres are produced from naturally occuring materials and therefore the costs of raw materials are relatively low. Such known mineral fibres typically have the following composition: The known mineral fibres are characterized by their high temperature resistance, but they are only slightly affected by salt solutions. Therefore they degrade very slowly when deposited at a tip or in other places in nature after use. The specification of NO patent application No. 874323 (Manville Corporation) describes inorganic fibres serving as a substitute for conventional mineral wool fibres and containing MgO in an amount of 0.1-30 % by weight and A O., in an amount of 0-10 % by weight in addition to Si0 2 and CaO. According to the above-mentioned patent application said fibres, which are mainly characterized in having a relatively low content of AKO,, are considerably more soluble in salt solutions than conventional mineral fibres, e.g. in the so- called Gamble's solution, i.e. an aqueous solution containing the following salts in a dissolved form: Component Concentration g/1 MgCl 2 , 6H 2 0 0.160 NaCl 6.171 KCl 0.311 a 2 HP0 4 0.149 Na 2 S0 4 0.079 CaCl 2 , 2H 2 0 0.060 NaHC0 3 1.942 NaC 2 H 3 0 2 1.066 An essential drawback of the known soluble fibres is that they are produced from relatively expensive oxides and not from naturally occur ng raw materials. Furthermore some of the known fibres have a relatively poor heat resistance and are consequently unsuitable for use at high tempera¬ tures. Surprisingly it has been found that mineral fibres with a consider¬ ably greater solubility in salt solutions than the above-mentioned known mineral fibres, and which at the same time exhibit an accept¬ able high temperature resistance can be produced from naturally occuring raw materials and other inexpensive raw materials. Mineral fibres according to the invention are characterized in having the following composition: Si0 2 Al 2 0 3 Fe 2 0 3 CaO MgO Na 2 0 K 2 0 the total content of Si0 2 , A1 2 0 3 and Fe 2 0 3 not exceeding 65 % by weight. Mineral fibres of the above-mentioned composition can be produced from naturally occuring raw materials and other readily obtainable and inexpensive materials such as waste products from the production of mineral wool fibres and glass. Examples of such raw material compositions are listed in Table I. Tabl e I Raw material composition Diabase 70 % Cement briquettes ' 30 % Diabase 20 % Clay briquettes 2') 80 % Cement briquettes 3)' 80 % Olivine-containing diabase 20 % Clay briquettes consisting of: Clay briquettes consisting of: 5 Clay 50 % Rock wool waste 10 % Lime 20 % Sand 10 % Olivine sand 10 % Clay briquettes consisting of: 6 Clay 50 % Lime 20 % Sand 10 % Olivine sand 10 % Soda 10 % Cement briquettes consisting of: Olivine 53 % Glass waste from the produc¬ tion of glass bottles 35 % Cement 12 % 1) Consisting of 12 % cement, 40 % mineral wool waste, 5 % dolomite and 43 % diabase. 2) Consisting of 50 % clay, 30 % mineral wool waste, 15 % olivine sand and 5 % iron oxide slag. 3} Consisting of 15 % cement, 23 % mineral wool waste, 22 % sand, 10 % olivine sand, 30 % olivine-containing diabase. The solubility of the mineral fibres of the invention and known fibres has been examined by storing fibre samples weighing 830 mg in 250 ml of said Gamble's solution for 5 hours at a temperature which was increased from 37°C to 60 β C and by measuring the SiO ^ -concentration of the solution at the end of the test. The results obtained will appear from Table II. Solubi¬ lity, ppm Si0 2 3.74 1.84 8.22 4.79 12.88 10.80 As will appear from the above Table II the mineral fibres according to the invention have a considerably higher solubility in the salt solution than the conventional known fibres. A fibre sample according to NO patent application No. 874323 was subject to a similar examination. The fibres had the following composition: Si0 2 50.2 % by weight A1 2 0 3 10.0 - Ti0 2 0.3 - Fe 2 0 3 0.7 - CaO 27.9 - MgO 6.8 - Na 2 0 0.2 - K 2 0 0.7 - A solubility corresponding to a Si0 2 -concentration of 3.16 ppm was measured which is also considerably less than the solubility of the fibres of the invention. It could be feared that mineral fibres with a relatively high solubility in salt solutions would be sensitive to heat and therefore would be unsuitable for use at high temperatures and that they lack the necessary fire resistance. However, tests have shown that this fear is groundless in respect of the fibres according to the invention. The tests were carried out with mineral fiber samples weighing from 0.5 to 1 g. These samples were placed on a refractory plate and then inserted into an oven which was preheated to a given temperature. After 30 minutes in the oven at this given temperature the fibre samples were removed from the oven and examined. If the dimensions, structures and elasticity of the fibres were unchanged this was taken as an indication of the fibres being resistant at the given temperature. If it was found that the fibres were brittle (sintered), a new sample was subject to a similar treatment at a temperature which was 25°C below the one tried first. If necessary the test was repeated with a further reduction of the temperature until the fibres remained unchanged. The examination of the mineral fibres according to the invention (tests 3-6) listed in Table II showed that they were all resistant at a temperature higher than 750 β C which corresponds to the tem- perature resistance of the mineral fibre sample according to NO patent application No. 874323. Mineral fibres according to the invention with a composition within the following limits: 47-51 % by weight 5-7 2-4 15-21 10-15 0.5-7 0.5-1.5 exhibit a particularly high solubility in salt solutions.

Claims: Patent claims 1. Mineral fibres, c h a r a c t e r i z e d in having the following composition: Si0 2 47-54 % by weight A1 2 0 3 4-7.5 - Fe 2 0 3 1-8.5 - CaO 10-24.5 - MgO 10-21 - Na 2 0 0.1-10 - K 2 0 0.1-1.5 - 2. Mineral fibres according to claim 1, c h a r a c t e r i z e d in having the following composition: Si0 2 47-51 % by weight A1 2 0 3 5-7 Fe 2 0 3 2-4 CaO 15-21 MgO 10-15 - Na 2 0 0.5-7 - K 2 0 0.5-1.5 -

Inventors: MOGENSEN GURLI, MOGENSEN, GURLI
Applicants: ROCKWOOL INT, ROCKWOOL INTERNATIONAL A/S
Application year: 1989
Main classification: C03C13
IPC codes: C03C13