WO1995031412A1 - Process for producing mineral fibres - Google Patents

Abstract

To provice an economical process for producing mineral fibres in which no environmentally polluting exhaust gases are produced and the mineral fibres thereby produced do not adversely affect health, it is proposed to use a basic material in the form of artificial stone consisting of a composition of white fine chalk and/or burnt dolomite with sand, preferably in a ratio by quantity of 1:3.5 to 1:14.0 and, if necessary, other chemically acceptable additives, in which the components are previously ground to a grain size of 0.05 to 8 mm, the artificial stones are melted in a melting plant and the melt is taken to a defibrating plant.

Description

Process for the production of mineral fibers

The invention relates to a method for producing mineral fibers.

Mineral wool insulation materials, especially stone wool, have so far been produced almost exclusively on the basis of natural raw materials, e.g. Basalt rock, diabase rock and other rocks that are broken up in quarries and processed into pieces. In a broader sense, slags from various smelter processes must also be added to these raw materials. In accordance with the great need for insulating materials for the thermal and acoustic insulation of buildings, industrial plants and the like, extraordinarily large amounts of raw materials are required. These raw materials are in lumpy form, e.g. in shaft furnaces, layered with coke and lime in melting units, melted therein and finally shredded. Various furnace types are available as melting units, e.g. B. shaft furnaces, furnace furnaces, Elektro¬ melting furnaces and gas or oil-fired melting furnaces according to WO 92/042286.

This technique, which has been practiced for decades, has recently caused a number of problems. One problem is that the chemical-mineralogical composition of the fibers produced is based on the composition of the natural raw materials and is therefore subject to a certain natural fluctuation range with regard to the constituent components of the composition. These natural compositions of the raw materials can only be partially conditioned by the assembly of batches from different individual components or by correction components, such as. B. lime or raw glass. Another problem is that the Different types of melting furnaces require very special requirements for the grain or piece size of the raw materials. This piece size, which is suitable in each case for a relevant melting furnace, can hardly or only inadequately be achieved on the basis of natural raw materials. When breaking up large pieces of rock, it cannot be avoided that different piece sizes occur, in particular larger proportions of rock pieces that are much too small. However, since this cannot simply be separated out as waste, there are disadvantages in the mode of operation of the melting furnace in question.

Another essential problem with the use of natural raw materials arises from the fact that the chemical composition of the fibers produced is predetermined on the basis of the chemical constituents of the naturally occurring raw materials and can hardly be changed in practice. These mineral fibers made from natural raw materials have recently been suspected, however not scientifically proven, of being harmful to human health, in particular for craftsmen who handle mineral wool products, and may even be carcinogenic. There has been no lack of investigations and attempts to refute this suspicion or, if necessary, to confirm it. In any case, extensive investigations have shown that there are a few among the numerous natural raw materials for which it can be said with the greatest possible certainty that they are not harmful in any form to health. The harmlessness of these special mineral fibers is based on the one hand on the numerous tests carried out on test animals, in which large amounts of fibers have been injected directly into the peritoneum or pectoral skin, and on the other hand on the finding and realization that these special fibers have a low bio-resistance or have a high solubility in the body's own liquids, i.e. they simply dissolve or are excreted by the body, without leaving any health damage. These natural raw materials, if they can be obtained with the required purity, can only be found in a few non-European countries around the world, so that they cannot be considered for mass use in the mineral wool industry simply because of the high transport costs.

When using raw materials such as slag, there is another problem, namely that of a large environmental impact. The slag contains sulfur, so that sulfur dioxide S0 ₂ and sulfur hydrogen H ₂ S are formed in the melting process. Secondary measures must then be taken to desulfurize the flue gases generated during the melting process, after which the residues must be disposed of.

Artificial stones containing cement or clay as binders are known from the mineral wool industry. The problem here is that these binders adversely affect the desired chemical-mineralogical properties and are sources of additional emissions, e.g. due to the sulfur content of the cement. In the case of the clay content, additional energy is required to drive the moisture out of the clay.

The invention is therefore based on the object of providing a method which can be carried out inexpensively, in which as few environmentally harmful exhaust gases as possible occur and the mineral fibers produced therewith have no health-damaging effects.

According to the invention, a method for producing mineral fibers is thus proposed, with a starting material in the form of artificial stones, which consists of a

Composition of white fine lime and / or burnt dolomite with sand, preferably in a ratio of 1: 3.5 to 1: 14.0 and, if necessary, further chemically harmless additives are formed, the composition components being ground beforehand to a grain size of 0.05 to 8 mm, then the artificial stones are melted in a melting unit and the melt in a defibration unit be fed.

An advantageous further development results from the fact that the composition constituent of white fine lime and / or burnt dolomite and / or magnesium oxide is added.

In terms of process, it has proven to be advantageous that the artificial stones are produced at a press moisture of 4 to 7% by mass and a specific hardening pressure of 10 to 25 N / mm and in an autoclave at a pressure of 10 to 20 bar over a period of four to be cured for six hours.

Depending on which furnace is available, the artificial stones are pressed so that they have a final strength of

5 to 60 N / mm - *.

As part of the further development of the method according to the invention, it is advantageous to add mineral wool, in particular waste mineral wool, to the composition components, the composition of which corresponds to that of the artificial stones.

The following are some beneficial alternatives for im

Additives which can be used within the scope of the invention and for preferred compositions of the artificial stones are listed. The mineral wool, whether waste mineral wool or used mineral wool, is advantageously admixed in a grain size of about 0.01 to 0.5 mm as an additive.

It is also to be regarded as advantageous that the artificial stones Contain 70 pound mass% mineral wool, 28 to 91 mass% sand, preferably quartz sand and 5 to 15 mass% white fine lime and / or burnt dolomite and / or magnesium oxide.

According to the invention it is further proposed that a chemical composition is selected for the artificial stones, which essentially consists of Si0 ₂ , Fe oxides, A1 ₂ 0 ₃ , Na ₂ 0, BaO, K ₂ 0, CaO, MgO, B ₂ 0 ₃ , the difference of the sum formed from the mass fractions of Na ₂ 0, BaO, K ₂ 0, CaO, MgO and B ₂ 0 ₃ minus the double mass fraction of A1 ₂ 0 ₃ > 30, preferably> 40 .

An expedient alternative is that a composition is selected for the artificial stones so that the melt consists of the following mass fractions:

49 to 52 mass% sio ₂

<ι mass% A1 ₂ 0 ₃

< ^• * ->,. 1 mass% τio ₂

<ι mass% FeO

28 to 35 mass% CaO

15 to 20 mass. MgO

<1 mass% Na ₂ 0 + K ₂ 0

A particularly cost-effective alternative is achieved by mass fractions of> 5 to 70 mass% recycled

Mineral wool, 28 to 91 mass% sand and 5 to 15 mass% white fine lime.

Another alternative within the scope of the invention is that a composition of the following mass fractions is selected for the artificial stones:

45 to 65 mass% sand with a grain size of 0.5 to 2 mm, 10 to 15 mass% white fine lime, burnt dolomite and / or magnesium oxide,

20 to 30% by mass of olivine sand and / or lime flour, It is also particularly advantageous that 1 to 10, preferably 5 to 8,% by mass of oxidic iron ore is added to the composition. In this way, particularly temperature-stable fibers can be produced for application temperatures greater than 700 ° C up to 1000 ° C.

For the charging of a melting furnace, it is also advantageous to add a lumpy addition of 20 to 30% by mass of soft lime to the artificial stones.

Another alternative is that the composition for the artificial stones consists of the following mass constituents:

60% by mass of finely ground rock wool with a grain size of 0.01 to 0.5 mm and one

Grain content of 30% by mass <0.1 mm, 33% by mass of sand with a grain size of 0.5 to 2.0 mm, 7% by mass of white fine lime.

In principle, the proposed solutions according to the invention are concerned with producing a melt for the production of mineral fibers on the basis of artificial stones in a cost-effective manner, using little energy for the melting process and it being possible for the artificial stones to be produced in a simple manner to give the desired lumpiness and strength. Furthermore, it has become possible according to the invention to return used mineral wool insulation materials and waste from mineral wool production to the melting process via the artificial stones without additional emissions, such as sulfur dioxide S0 ₂ or hydrogen sulfide H ₂ S being produced. The grain sizes of the finely ground components of the composition have already been mentioned above. These finely ground components are able to be incorporated into the Ca silicate lattice structure without the strength of the artificial stones being affected. In principle, the artificial stones are produced in the manner known in the construction industry for the production of lime sandstones. As an example, the following technical data are given in the context of the invention in the production of the artificial stones:

Fire water: 80%

Press moisture: 5.5% specific setting pressure: 9.0 to 25.0 N / mm ²

Hardness pressure: 16 bar

Hardening time: 4.5 hours.

In the following, further advantageous exemplary embodiments of the method according to the invention are specified. The use of the respective exemplary embodiment depends on the technical requirements placed on the mineral fibers to be produced in practice, ie. H. whether the mineral fiber product ultimately produced from the mineral fibers primarily for thermal insulation or for

Sound insulation is used or whether fire resistance is particularly important, for example. Further aspects are the melting point and the melting time of the artificial stones, which are directly related to the fine-grained nature of the ground starting material. A further criterion for the selection of one or the other exemplary embodiment of the method according to the invention is the availability of the raw materials in question on the market and their costs.

The mineral fibers to be produced according to the invention can be further processed into a wide variety of mineral fiber products, for example mineral wool sheets or panels for thermal and acoustic insulation and for fire protection of buildings, industrial plants and the like. Furthermore, the mineral fibers can be used as a plant growth substrate. The mineral fibers can also be used as loose, if necessary, fluffy wool for filling voids, ie used as fillers. Another application example is the use as reinforcing fibers in other building materials, e.g. B. as reinforcing fibers in cement or similar products.

Finally, the mineral fibers can also be used as fillers in cement, plastic or similar products.

It is also proposed that a composition be selected for the artificial stones, so that the melt consists essentially of SiO ₂ , FeO, Al ₂ O ₃ , Na ₂ O, BaO, K ₂ O, CaO, MgO, B ₂ O ₃ consists, the difference of the sum formed from the mass fractions of Na ₂ 0, BaO, K ₂ 0, CaO, MgO and B ₂ 0 ₃ minus the double mass fraction of A1 ₂ 0 ₃ ,> 30, preferably> 40 , is.

An alternative to a previously specified exemplary embodiment is that a composition is selected for the artificial stones so that the melt consists of the following mass fractions:

40 to 64% by mass ^s - * - ° 2 <4% by mass, preferably <2% by mass Al ₂ 0 ₃ <1.5% by mass ^τ - * - ⁰ 2 1 to 12% by mass FeO + Fe ₂ 0 ₃

10 to 38 mass. CaO 7 to 20 mass% MgO 0 to 6 mass% Na ₂ 0 + K ₂ 0.

Another method is characterized by such an addition to the artificial stones that the melt contains 1 to 10% by mass, preferably 5 to 8% by mass, of iron oxide.

It is also proposed that additives such as P ₂ ° 5 ' ^B 2 ° 3 ^oc * - * ^er BaO be added to match the desired solubility, so that their mass constituent in the melt is <20% by mass, preferably <10% by mass , is. Under certain circumstances, a lumpy addition of <50% by mass of natural stone material or waste mineral wool or waste glass is also possible. The lumpy addition can also take the form of briquettes, e.g. B. egg briquettes.

Another advantageous embodiment of the method is that a composition is selected for the artificial stones, so that the melt consists of the following mass fractions

48 to 60 mass% ^si0 2 <4 mass%, preferably <2 mass% A1 ₂ 0 ₃ <1.5 mass% ^τ - * - ° 2

1 to 10 mass% FeO + Fe ₂ 0 ₃ 20 to 38 mass% CaO

7 to 20 mass% MgO

0 to 6 mass% Na ₂ 0 + K ₂ 0 10 mass% ^P 2 ° 5 ' ^B 2 ° 3' ^Ba0 -

It has proven to be advantageous that glass, olivine sand, titanium oxide (Ti0 ₂ ), magnesite, magnetite, brucite, fly ash, kettle ash or slag are used as additives to the artificial stones, either alone or in combination. Alternatively, soft aggregate lime, diabase or pyroxenite can be used as additives to the artificial stones, either alone or in combination.

Finally, a further alternative is proposed, namely that a composition is selected for the artificial stones, so that the melt consists of the following mass fractions:

48 to 60 mass% ^S; * - ⁰ 2

<4 mass%, preferably <2 mass% ^A1 2 ⁰ 3 <1.5 mass% ^τ - * - ° 2 <1.5 mass% FeO + Fe ₂ 0 ₃

25 to 35 mass% CaO

8 to 18 mass% MgO 10

0 to 6 mass% Na ₂ 0 + K ₂ 0

<10 mass% ^P 2 ° 5 ' ^B 2 ° 3' ^Ba0 *

The constituent components of the artificial stones as well as the possibly additionally lumpy components of the batch usually have a very high melting point, which can vary depending on the component. Typical melting points are 1250 ° C or 1300 ° C or 1375 ° C. Other melting points are above 1450 ° C. It has been found that the smaller the grain size of the raw material, the shorter the dwell time until melting and the melting time. No flux is normally required and the strength properties of the artificial stones are not affected. Regardless of the different melting points, a uniform melting process takes place. This is particularly important when using cupola furnaces, but also to a corresponding extent with electric furnaces. In the context of the invention, it is therefore proposed as particularly advantageous that the composition components of the artificial stones are ground to a grain size of <2 mm, preferably up to 80% to <0.5 mm.

In order to further improve the quality of the mineral fibers to be produced, it is proposed that 50 to mass constituents, the constituent components of the artificial stones, consist of inorganic materials, such as quartz sand, olivine sand or limestone, which have a melting point of over 1450 ° C.

It has already been mentioned above that the procurement of raw materials essentially depends on which materials are available on the market, and the procurement costs also play a major role. On the other hand, it also depends on the intended use of the mineral fibers to be manufactured or the mineral fiber end product, which requirements are made in practice. From these In practice, it is often not necessary for the furnace batch to consist of 100% artificial stones. It is therefore proposed that <50%, preferably 30%, lumpy and harmless natural stone material, such as limestone, dolomite, titanium oxide (Ti0 ₂ ), magnesite, magnetite, brucite, pyroxenite, olivine sand or glass alone or to the furnace batch in combination, and / or waste mineral material is added. The addition can also be in the form of briquettes, e.g. B. egg briquettes.

Claims

Claims 1. Process for the production of mineral fibers with a starting material in the form of artificial stones, which consists of a composition of white fine lime and / or burnt dolomite with sand, preferably quartz sand, in a ratio of 1: 3.5 to 1: 14.0 and If necessary, further chemically harmless additives are formed, the composition components being ground beforehand to a grain size of 0.05 to 8 mm, then the artificial stones are melted in a melting unit and the melt is fed to a defibration unit. 2. The method according to claim 1, characterized in that the composition component of white fine lime and / or burned dolomite and / or magnesium oxide is added. 3. The method according to claim 1 or 2, characterized gekenn¬ characterized in that the artificial stones at a press moisture of 4 to 7 mass% and a specific hardening pressure of 10 to 25 N / mm ² produced and in an autoclave at a pressure of 10 to 20 bar can be cured over a period of four to six hours. 4. The method according to any one of the preceding claims, characterized in that the artificial stones have a final strength of 5 to 60 N / mm ² . 5. The method according to any one of the preceding claims, characterized in that the composition components mineral wool, in particular waste mineral wool is added, the composition of which corresponds to that of the artificial stones. 6. The method according to claim 5, characterized in that the mineral wool in a grain size of about 0.01 to 0.5 mm is added as an additive. 7. The method according to any one of the preceding claims, characterized in that the artificial stones <70 mass% mineral wool, 28 to 91 mass% sand, preferably quartz sand, and 5 to 15 mass% white fine lime and / or burnt dolomite and / or contain magnesium oxide. 8. The method according to any one of the preceding claims, characterized in that a chemical composition is selected for the artificial stones, which consists essentially of Si0 ₂ , FeO, A1 ₂ 0 ₃ , Na ₂ 0, BaO, K ₂ 0, CaO, MgO, B ₂ 0 ₃ exists, the difference of the sum formed from the mass fractions of Na ₂ 0, BaO, K ₂ 0, CaO, MgO and B ₂ 0 ₃ minus the double mass fraction of A1 ₂ 0 ₃ ,> 30 , preferably> 40. 9. The method according to claim 1, characterized in that a composition is selected for the artificial stones, so that the melt consists of the following mass fractions: 49 to 52 mass% sio ₂ <1 mass% ^A l ₂ ° ₃ 0.1 mass% τio ₂ <1 mass% FeO 28 to 35 mass% CaO 15 to 20% by mass of MgO <1 mass% Na ₂ 0 + K ₂ 0 10. The method according to claim 8 or 9, characterized by mass fractions of> 5 to 70 mass% recycled Mineral wool, 28 to 91 mass% sand and 5 to 15 mass% white fine lime. 11. The method according to claim 1, characterized in that a composition of the following for the artificial stones Mass proportions is selected: 45 to 65 mass% sand with a grain size of 0.5 to 2 mm, 10 to 15 mass% white fine lime, burnt dolomite and / or magnesium oxide, 20 to 30% by mass of olivine sand and / or lime flour. 12. The method according to any one of the preceding claims, characterized in that the composition 1 to 10 mass%, preferably 5 to 8 mass%, oxidic iron ore is added. 13. The method according to any one of the preceding claims, characterized by a lumpy addition of 20 to 30% by mass of soft lime to the artificial stones. 14. The method according to claim 1, characterized in that the composition for the artificial stones consists of the following mass constituents: 60% by mass of finely ground rock wool with a Grain size from 0.01 to 0.5 mm and a grain size of 30 mass. <0.1 mm, 33 mass% sand with a grain size of 0.5 to 2.0 mm, 7 mass. White fine lime. 15. The method according to claim 1, characterized in that a composition is selected for the artificial stones, so that the melt consists essentially of Si0 ₂ , FeO, A1 ₂ 0 ₃ , Na ₂ 0, BaO, K ₂ 0, CaO, MgO, B ₂ 0 ₃ , the difference of the sum formed from the mass fractions of Na ₂ 0, BaO, K ₂ 0, CaO, MgO and B ₂ 0 ₃ minus 15 twice the mass fraction of A1 ₂ 0 ₃ ,> 30, preferably> 40. 16. The method according to claim 1, characterized in that a composition is selected for the artificial stones, so that the melt consists of the following mass fractions: 40 to 64 mass% ^s - * - ⁰ 2 <4 mass%, preferably <2 mass% A1 ₂ 0 ₃ <l / 5 mass% ^τ - * - ° 2 1 to 12 mass% FeO + Fe ₂ 0 ₃ 10 to 38 mass% CaO 7 to 20 mass. MgO 0 to 6 mass. Na ₂ 0 + K ₂ 0. 17. The method according to claim 1, characterized by such an addition to the artificial stones that the melt contains 1 to 10% by mass, preferably 5 to 8% by mass, of iron oxide. 18. The method according to any one of the preceding claims, characterized in that additives such as ₂ 0 ₅ , B ₂ 0 ₃ or BaO are added to match the desired solubility, so that their mass component in the melt is <20% by mass, preferably <10 mass%. 19. The method according to any one of the preceding claims, characterized by a lumpy addition of <50 mass% of natural stone material or waste mineral wool or waste glass. 20. The method according to claim 1, characterized in that a composition is selected for the artificial stones, so that the melt consists of the following mass fractions: 48 to 60 mass% SiO, <4% by mass, preferably <2% by mass A1 ₂ 0 ₃ <1.5 mass% ^τ - * - ° 2 1 to 10 mass% FeO + Fe ₂ 0 ₃ 20 to 38 mass% CaO 7 to 20 mass% MgO 0 to 6 mass% ^Na 2 ° ^{+ K} 2 ° <10 mass% ^p 2 ° 5 ' ^B 2 ° 3' ^Ba0 ' 21. The method according to claim 1, characterized in that as additives to the artificial stones alone or in combination optionally glass, olivine sand, titanium oxide (Ti0 ₂ ), magnesite, magnetite, brucite, fly ash, Kessel¬ ash or slag are used. 22. The method according to claim 1, characterized in that soft aggregate lime, diabase or pyroxenite are used as additives to the artificial stones alone or in combination. 23. The method according to claim 1, characterized in that a composition is selected for the artificial stones, so that the melt consists of the following mass fractions: 48 to 60% by mass SiO '2- <4% by mass, prefix <2% by mass A1 ₂ 0 ₃ <1.5% by mass τio ₂ <1.5% by mass. FeO + Fe ₂ 0 ₃ 25 to 35 mass% CaO 8 to 18 mass% MgO 0 to 6 mass% Na ₂ 0 + K ₂ 0 <10 mass% ^P 2 ° 5 ' ^B 2 ° 3' BaO. 24. The method according to any one of the preceding claims, characterized in that the composition components of the artificial stones to a grain size of <2 mm, preferably up to 80% to <0.5 mm. 25. The method according to any one of the preceding claims, characterized in that 50 to mass% of the constituent components of the artificial stones consist of inorganic materials, such as quartz sand, olivine sand or limestone, which have a melting point of over 1450 ° C. 26. The method according to any one of the preceding claims, characterized in that to the furnace batch <50%, preferably 30%, lumpy and harmless Natur¬ stone material such as limestone, dolomite, rutilite, magnesite, magnetite, brucite, pyroxenite, olivine sand or glass alone or in combination, and / or waste mineral material is added.