METHOD FOR PRODUCING MINERAL WOOL

Abstract

The present invention relates to a method for producing mineral wool having a chemical composition, expressed as a percentage by weight of oxides, comprising:

TABLE-US-00001 SiO2 30-50%  Al2O3 15-35%  CaO 5-25% MgO 1-25% Fe2O3 2-15% Na2O + K2O  >10%
said method comprising providing a mixture of raw materials, melting said mixture of raw materials to obtain a molten material, and fiberizing the molten material; characterized in that the mixture of raw materials comprises at least 8.5% by weight of a recycled raw material comprising at least 3% of magnesium, expressed by weight of oxides, said recycled raw material being substantially free of carbonates, and in that the mixture of raw materials is free of dolomite and magnesia.

Claims

1. A method for producing mineral wool having a chemical composition, expressed as a percentage by weight of oxides, comprising: TABLE-US-00009 [[SiO2]] SiO.sub.2 30-50%;  Al.sub.2O.sub.3 15-35%;  CaO 5-25%; MgO 1-25%; Fe.sub.2O.sub.3 2-15%; and Na.sub.2O + K.sub.2O  >10%, said method comprising: melting a mixture of raw materials to obtain a molten material; and fiberizing the molten material; wherein the mixture of raw materials is in pulverulent form and comprises at least 8.5% by weight of a recycled raw material comprising at least 3% of magnesium, expressed by weight of oxides, said recycled raw material being substantially free of carbonates, and wherein mixture of raw materials is free of dolomite and magnesia.

2. The method according to claim 1, wherein the chemical composition of the mineral wool comprises less than 0.1% by weight of halogen.

3. The method according to claim 1, wherein the recycled raw material comprises less than 0.9% by weight of halogen.

4. The method according to claim 1, wherein the recycled raw material is free of fluorine.

5. The method according to claim 1, wherein the recycled raw material comprises up to 2% by weight of aluminum metal.

6. The method according to claim 1, wherein the recycled raw material has a chemical composition, expressed by weight of oxides, comprising: TABLE-US-00010 Al.sub.2O.sub.3 50 to 80%;  [[SiO2]] SiO.sub.2 2 to 25%; MgO 3 to 20%; Fe.sub.2O.sub.3 0.5 to 10%..sup. 

7. The method according to claim 1, wherein the recycled raw material has a chemical composition, expressed by weight of oxides, in which a weight ratio of Al.sub.2O.sub.3/MgO is greater than 8.

8. The method according to claim 1, wherein the mixture of raw materials does not comprise briquettes.

9. The method according to claim 1, wherein the mixture of raw materials comprises at least 1% by weight of bauxite.

10. The method according to claim 1, wherein the mixture of raw materials is melted in a fuel-fired furnace and/or by electric melting.

11. The method according to claim 1, wherein the fiberizing is carried out by internal centrifugation.

12. The method according to claim 1, wherein the recycled raw material comprises less than 0.6% by weight of halogen.

13. The method according to claim 1, wherein the mixture of raw materials is melted in a submerged combustion furnace.

Description

EXAMPLES

[0040] Productions of mineral wool having a target chemical composition as presented in table 1 were carried out starting from different mixtures of materials. The mixture of raw materials of comparative example C1 is a conventional mixture comprising dolomite as magnesium carrier. In example l1 according to the invention, the dolomite was entirely substituted by a recycled material according to the invention. The compositions of the mixtures of raw materials are detailed in table 2. Table 3 presents the chemical composition of the recycled material.

TABLE-US-00006 TABLE 1 SiO.sub.2 Al.sub.2O.sub.3 CaO MgO Fe.sub.2O.sub.3 Na.sub.2O K.sub.2O TiO.sub.2 Other % by 42.7 22.9 14.4 1.7 5.6 6.7 4.0 1.0 1.0 weight

TABLE-US-00007 TABLE 2 Composition of the mixture of raw materials (kg) C1 I1 Dolomite 63 — Recycled raw material — 100 Bauxite 135.4 45 Limestone 209 238.4 Phonolite 606 606 Nepheline syenite 65 65 Iron oxide 37.5 34.7 Sodium carbonate 36 33

TABLE-US-00008 TABLE 3 SiO.sub.2 Al.sub.2O.sub.3 CaO MgO Fe.sub.2O.sub.3 Na.sub.2O Cl F Other % by 11.3 68.8 3.2 7.5 4 1.7 0.05 0 3.4 weight

[0041] During the various production runs, no decrepitation was observed during the melting of the mixtures of raw materials of example I1. This results in a significant reduction in the amount of substances given off and the risk of obstructing the regenerators, compared to the use of a mixture of raw materials of example C1. The stability of the composition of the molten bath is also improved compared to example C1. Finally, a reduction of 2 to 5% in the CO2 emissions during the melting of the mixtures of raw materials of example I1 was observed compared to that of example C1.