CA2435261C - Method for producing insulating materials from mineral fibers - Google Patents

Abstract

The invention relates to a method for producing insulating materials from mineral fibers, especially from glass and/or rock wool. A silicate melt is produced in a melting unit, especially a cupola melting furnace, and is disintegrated in a disintegration device to preferably microfine fibers. Preferably, a binder and/or proofing agent is added to the fibers and they a re placed on a conveyor means in the form of an unwoven material. The aim of th e invention is to improve said method and said melt in such a manner that the method can be carried out at lower costs or that an inexpensive melt is provided by using inexpensive starting materials. To this end, the silicate melt is at least partially produced from catalysts derived from oil refining that are especially no longer useful.

Description

Method for ProducingInsulating Materials from Mineral Fibers This invention relates to a method for producing insulating materials from mineral fi-bers, especially from glass and/or rockwool, wherein a silicate melt is prepared in a melting unit, especially a cupola furnace, and is disintegrated in a disintegration unit to preferably microfine fibers, and wherein a binder and/or proofing agent is added to the fibers and the fibers are placed on a conveyor means in the form of a fibrous web.

The invention further relates to a melt for producing mineral fibers for a mineral fiber web.

Insulating materials made from mineral fibers are produced from silicious melts. To this end a silicious starting material, e.g. glasses, natural or artificial stone, are fed for ex-ample to a cupola furnace or shaft furnace. The silicious melt thus obtained is then fed to a disintegration unit where the silicious melt is disintegrated to microfine mineral fibers. The mineral fibers which are thereafter supplied to a collecting chamber are as a rule wetted with binders and/or proofing agents and are placed on a conveyor means, usually a coveyor belt, arranged under the collecting chamber. The mineral fibers wet-ted with binder and/or proofing agents form on said conveyor means a mineral fiber web which is treated in a manner known per se in downstream thermal and/or mechani-cal devices, in order to produce insulating materials in the form of webs, boards, moulded bodies or the like.

With insulating materials made from mineral fibers a difference is made between those from glass wool and those from rockwool. Rockwool insulating materials usually have been melted open from stones like diabase, basalt and limestone, dolomite. In the meantime, these natural stones are increasingly replaced by artificial stones or are sub-ject to the melting process together with artificial stones. In this melting process, which mostly takes place in cupola furnaces, there exists a strong dependence between the viscosity and temperature. Moreover, the nucleation number and hence the tendency to crystallization are very high. At the formation of the mineral fibers on so-called cascade spinning machines these properties lead to relatively short mineral fibers which are swirled in themselves. The individual mineral fibers per se have a glassy solidified ap-pearance. Due to their composition the temperature resistance of mineral fibers pro-duced from a melt of rock is higher than that of insulating materials from glass wool.
Glass wool insulating materials contain as a network transformer overwhelmingly so-dium oxide and boroxide. The melt for glass wool insultating materials exhibits a weakly developed dependence of the viscosity from temperature. The disintegration of this glass melt does not take place on cascade spinning machines, but is effected with the aid of rotating bowl-shaped bodies, of which the walls include bores. Due to the centrifugal force which is produced in this case the glass melt is forced through these bores, so that mineral fibers are extruded from glass wool which have a longer length compared to those from rock wool.

An important factor at the production and evaluation of mineral fibers is the biosolubil-ity, i.e. the dwell time of the mineral fibers in the human organism. The biosolubility of insulating materials from rockwool is decisively influenced by the A1203 content. With increasing A1203 moieties the temperature resistence of the fibers increases on the one hand and, surprisingly, on the other hand also the biosolubility.

A typical composition of biosoluble mineral fibers from rockwool includes a moiety of Si02 between 35 and 43 % by weight, a moiety of A1203 of 17.5 to 23.5 % by weight, a moiety of Ti02 of 0.1 to 3 % by weight, a moitey of FeO of 1.7 to 9.3 % by weight, a moiety of CaO + MgO of 23.5 to 32 % by weight, and a moiety of K20 + Na2 of 1.3 to 7 % by weight.

An important criterion for the economy of insulating materials from rockwool as a mass product is the use of raw materials comprising a high moiety of A1203. Even though natural stones frequently include aluminosilicates, they are often not available in the required concentrations or only together with undesired minerals. Calcined bauxites, on the other hand, are comparatively expensive. For this reason, residual materials are fre-quently utilized which, up to present, were mostly only suitable for dumping and con-stituted a considerable risk to the environment because of their content of soluble sub-stances. At the same time these residual materials accrueing on the production of rock-wool, for example in the form of melt residues, separated non-fibrous particles, filtering dusts, misproductions or the like are almost completely recycled in a primary recycling system. These residual materials are conditioned prior to their recycling, so that they comply with the requirements of the machine equipment, particularly the melting unit.
For their recycling these residual materials are for example comminuted and mixed with each other or with other splintery raw materials at different grain sizes, compounded with binders such as cement and pressed to sufficiently large moulded bodies before these moulded bodies are supplied as lumpy raw materials to a shaft furnace or cupola furnace. From the EP 0 765 295 Cl for example it is known to bind suitable moulded bodies from fine-grained raw materials also with the aid of lignin. In WO
94/12007 cor-responding moulded bodies with molasses-containing binders are described.

In view of this prior art the invention is based on the problem of improving said method and said melt in such a manner that the method can be carried out at lower costs or that an inexpensive melt is provided by using inexpensive starting materials.

The solution of this problem provides that in a method of this kind the silicious melt is at least partly prepared from oil refining catalysts, particularly from those which are no longer usable.

Accordingly, the invention provides that in a method which is known per se the silicious melt is at least partly produced from oil refining catalsysts, particularly from those which are no longer usable.

Mineral oils consists of mixtures of high-molecular to low-molecular compounds. They serve as raw materials for a number of substances like fuels, base products for the pro-duction of polymers, or as starting material for bitumen and asphalts. At the different stages of processing a number of processes like the hydrating, dehydrating, oxidizing or reducing of intermediate products run in an economical way only under the use of cata-lysts.

In this respect the catalysts are classified in two classes. On one side, redox catalysts like chromic oxide or vanadium pentoxide, metals such as platinum, palladium or nickel are used which catalytically influence the hydrating, dehydrating and oxidizing pro-cesses. Here the metals are seated on e.g. aluminium oxide supporting materials. On the other side, acid-base-catalysts find use for isomerization, alkylation or cracking reac-tions that run via ion-like intermediate stages. Typical acid-base-catalysts consist of acidic aluminium oxides, aluminosilicates or zeolites. Those kinds of catalysts have a relatively long useful time, since they can be repeatedly regenerated. These catalysts need to be replaced for example in case of the addition of coke or of so-called catalyst poisons or in case of a decreasing specific surface area of noble metals as a conse-quence of recrystallization. At higher standards the noble metals contained in the cata-lysts can be economically recovered.

However, used catalysts accrueing on catcracking or hydrocracking are normally waste, of which the recycling is economical only in few other processes, in order to protect the environment.

For example, in order to obtain high-quality fuels from mineral oils, distillation prod-ucts from mineral oil are subject to a catalytic cracking process. The treatment mostly takes place in fluid-bed reactors. The catalytic cracking reactions take place in the pres-ence of acidic catalysts according to a carbonium ion mechanism. As usual catalysts aluminosilicates doped with protons are mostly used. These catalysts replace the for-merly used acid-treated clay minerals of the montmorillonite group which have been replaced because of their crystallinity and the present impurities caused for example by iron or by amorphous aluminosilicates. Commercially available amorphous aluminosili-cates contain approx 10 to 15 % by weight of A1203, but there are also known alumi-nosilicates having an A1203 content of between 20 to 30 % by weight.

Economically much more important and hence much more popular are catalysts from synthetic zeolites with the crystal structure of the mineral faujasite.
Suitable zeolites are for example produced by Union Carbide under the name Linde type X or Linde type Y.
The total formula of these two zeolite types is:

Linde type X: Na86[A102)86(SiO2)1o6] x H20 Linde type Y: Na56[Al02)56(SiO2)136] x H20 The chemical efficiency extremely increases with the exchange of the NA ions for tri-valent ions like for example lantane, lantanides or other rare earths.
Accordingly, as the most efficient catalysts so-called H-RE-faujasites are used, wherein "RE" is the abbre-viation for "rare earths".

From various technical reasons like increasing the resistance to abrasion, thermal sta-bility and for a better distribution of the active substances it is useful that the zeolite catalysts are distributed in a matrix of silica gel, amorphous aluminosilicates or clays.
The H-RE-faujasite is, for example, embedded at relatively small amounts in amor-phous aluminosilicates. Zeolite catalysts work more selectively than amorphous alumi-nosilicates, the latter boosting the formation of olefines. Such catalysts have a high open porosity and a large specific surface area, which are favourable and necessary for their function as a catalyst in the catcracking process. By the separation of coke the active centers of the catalysts are deactivated. Cleaning of the expensive catalysts is effected, for example, by a careful burning-off of the coke depositions. However, any complete cleaning cannot be guaranteed, so that the service life of such a catalyst is limited even though it is regularly cleaned.

A permanent deactivation of the catalysts can be caused in addition by metal com-pounds in the distillates. Such metals in distillates are in the first line vanadium, nickel and/or iron which themselves act as catalysts and cause undesired reactions.
Due to a decrease in the catalytic activity and in selectivity catalysts become unusable and need to be exchanged. As a rule, such catalysts are dumped as waste material, unless they can be recycled in an economical way in other processes.

Catalysts herein described are used in so-called fixed-bed reactors and are available in the form of particles having a good flowability and a grain size of 3 to 4 mm.
If fluid-bed reactors are used, catalysts will be selected, of which the particles have an average diameter of approx 50 to 70 m.

Methods for the refining hydration of mineral oil fractions are part of the so-called hy-drotreatings, of which the various techniques are used for example in order to separate harmful or inhibiting tramp materials. To this end catalysts are used which are based among others on the use of cobalt and molybdenum oxides with aluminium oxide as a supporting medium. Such catalysts are available in the form of extrudates and have an initial length of approx 2.5 to 3 mm.

Finally, for the breaking hydration of mineral oil fractions hydrocracking methods are applied in which typical hydrocrack catalysts are used that contain tor example metals like nickel or tungsten in amounts of approx 15 to 25% by weight or CoO + MoO3 with moieties of approx 22 to 28% by weight as well as support medium. The support medium either consists of almost pure A1203 or of aluminium silicates.

Surprisingly it has shown now that the above-described catalysts in the used state are particularly suited as supplementary raw materials fiir the production of insulating mate-rials from mineral wool.

According to a further feature of the invention it is advantageous to use as catalysts those from cracking and hydrocracking processes which are very well suited as substi-tute raw materials, particularly for the production of rockwool insulating materials. As a characteristic parameter Si02 in moieties of approx 30 to approx 55 % by weight and A1203 in moieties of between about 30 to 50 % by weight can be mentioned as main constituents.

However, also catalysts can be used which consist of zeolite, wherein the above-de-scribed zeolites of the type Linde are of interest when the sodium content is reduced in order to avoid an excessive content of alkalies in the insulating material.
All the other constituents of the catalysts are of minor importance and can thus be added to the melt without any negative effects.

A further feature of the invention provides that metals which precipitate during the melting-open of the catalysts are collected and periodically drained.
Preferably, the metals are collected and periodically drained together with the metallic iron reduced from the raw materials. Here it is advantageous that the melting units, for example the cupola furnaces, have no fire-resistant liniiig in their actual shaft region, so that the me-tals present in the catalysts are no danger for the melting unit.

According to an advantageous further improvement of the method according to the in-vention it is provided that oxidic components contained in the melt, such as rare earths like La203, CeOz, Pr6011, are dissolved in the melt.

A further feature of the invention provides that the melt is prepared from the catalysts and the usual raw materials for the production of insulating materials from mineral fi-bers, particularly diabase, basalt and limestone as well as dolomite, and/or from the re-sidual material obtained during the production or recycling. Accordingly, it is provided in this embodiment that the catalysts are merely a constituent of the melt of which the moiety within the melt is adjusted corresponding to the required quality level of the insulating materials.

According to a further feature of the invention the fine-grained catalyst masses are pressed to lumpy bodies before they are melted. Preferably, the fine-grained catalyst masses are mixed together with the residual material from the primary waste cycle and stones used as supporting grain as well as binders like hydraulic cements, latent-hy-draulic materials, lime and/or lignin, molasses or the like, and pressed to lumpy bodies.

mg_ After they have hardened, these lumpy bodies together with lumpy stones and coke are fed to a melting unit where they are melted open. In this connection it is advantageous that the constituents of the melt are thoroughly mixed before they are supplied to the melting unit.

Alternatively, the catalysts can be fully or at least partly blown as a fine-grained mass into the melting unit, particularly a shaft furnace, through blast forming. To avoid or reduce a decrease in temperature within the melting zone of the furnace it has proved that preheating the catalyst particles is advantageous, wherein a maximum preheating temperature of 600 C should be striven for.

In addition to the above-described method the present invention is also concerned with a melt for producing mineral fibers for a mineral fiber web, particularly from rockwool, which can be further made into insulating materials. The melt according to the invention is characterized by oil refining catalysts that are no longer usable.

Preferably, the catalysts originate from cracking and/or hydrocracking processes which have shown to be very good substitute raw materials for the production of rock wool insulating materials.

A further feature of the melt according to the invention provides that the catalysts are mixed with residual materials from the primary waste cycle and/or recycling materials from mineral fiber production. Such a mixture is particularly suited for the production of rock wool insulating materials of sufficiently high quality.

Preferably, the melt according to the invention includes 20 to 60 % by weight of Si02 and 10 to 60 % by weight, particularly 10 to 30 % by weight of A1203.

The catalysts available in the melt preferably have a grain size of between 2 and 6 mm, particularly of between 3 and 4 mm, so that the same are suitable for being pressed to lumpy bodies to be fed to a melting unit on the one hand, and for being blown into a shaft furnace on the other hand. To this end catalysts from fixed bed reactors can be used, for example, which are available in the form of particles exhibiting good flow-ability. But alternatively also catalyst particles are suited which are used in fluid bed reactors and which have an average diameter of 30 to 100 m and preferably of between 50 and 70 m.

Another alternative are catalysts that are used in processes for the refining hydration of mineral oil fractions. With such catalysts a configuration as extrudates can be deter-mined, of which the length preferably is between 1 and 5 mm, particularly between 2.5 and 3 mm.

Finally, a further feature of the invention provides that the catalysts include 10 to 30 %
by weight, particularly 15 to 25 % by weight of metals like nickel or tungsten or 15 to 35 % by weight and preferably 22 to 28 % by weight of cobalt oxide and molybdenum oxide. As a supporting material in such catalysts aluminium oxide is provided.

Further features of the method according to the invention or of the melt according to the invention become apparent from the following description of preferred embodiments.
First Embodiment For producing a melt a cupola furnace is charged with lumpy material that consists at 15% of a catalyst material and at 85% of artificial stones. As catalyst material amor-phous aluminium silicate catalysts from hydrocracking processes with 12.5% by weight of A1203 are used. The artificial stones consist at 60% of recycling material and at 40%
of re-built mineral fiber insulating materials, wherein the recycling material is taken from the production process in the form of cuttings or low-quality products.
The mate-rial to be fed is pressed from fine-grained catalyst material and the test material required for the artificial stones together with stones used as supporting grain with latent-hy-draulic materials to lumpy bodies.

Second Embodiment For producing a silicious melt which serves for producing fibrous insulating materials a cupola furnace is charged with lumpy material that consists at 25% of a catalyst mate-rial, at 20% of natural stone, and at 55% of artificial stones. As a catalyst material cata-lysts from mineral ol refining which are no longer usable are chosen, of which the main constituents are Si02 and A1203, wherein the catalyst material includes a moiety of 45%
by weight of Si02 and 40% by weight of A1203 as well as further oxidic constituents like rare earths and metal. As natural stone diabase, basalt and limestone as well as dolomite are used. The artificial stone is composed of residual materials accrueing on the production of fibrous insulating materials or on the re-building of fibrous insulating rnaterial, the proportion of the recycling material as a result of manufacturing being 70%, and the proportion obtained from re-building being 30%.

The catalyst material and the residual material that is to be made into artificial stones are prepared into a fine-grained material and are mixed with lime and lignin and pressed to lumpy bodies. Thereafter, the feeding material is fed to the cupola furnace as a frac-tion mixed from natural stone and lumpy bodies consisting of catalyst material and arti-ficial stone and melted therein and is subsequently fed to a disintegration unit in which the melt is disintegrated to microfine fibers which are then placed on a conveyor belt in the form of a mineral fiber web. Therafter, the mineral fiber web is mechanically and thermally treated, in order to produce the desired mineral fiber insulating materials.

Third Embodiment Also in the third embodiment catalyst material, natural stones and artificial stones are fed as charging material to a cupola furnace, with a mixture of 45% catalyst material, 20% natural stone, and 35% artificial stones being provided. The artificial stones are composed of 80% of recycling material and 20% of re-building material, said recycling material and re-building material being prepared into a fine-grained structure together with the catalyst material and pressed to lumpy charging material. To this end a binder is used including hydraulic cement. The production of the mineral fiber insulating mate-rial then takes place in the above-described way.

Claims (35)

1. An improved method for producing insulating materials from mineral fibers, wherein a silicate melt is prepared in a melting unit, and disintegrated in a disintegration unit, and the fibers are placed on a conveyor means in the form of an unwoven material, the improvement comprising preparing the silicious melt at least partly from oil refining catalysts.

2. A method as claimed in claim 1, wherein the mineral fibers are selected from glass, rock wool and mixtures of both.

3. A method as claimed in claim 1, wherein the melting unit is a cupola furnace.

4. A method as claimed in claim 1, wherein the disintegration unit produces microfine fibers which are mixed with binders, proofing agents or mixtures thereof.

5. A method as claimed in claim 4, wherein the oil refining catalysts are no longer usable.

6. A method as claimed in claim 1, wherein catalysts from cracking and/or hydrocracking processes are used.

7. A method as claimed in claim 1, wherein the catalyst is a zeolite with a reduced sodium content.

8. A method as claimed in claim 1, wherein metals precipitated during a melting of the catalysts are collected and periodically drained.

9. A method as claimed in claim 8, wherein the metals are collected and periodically drained together with metallic iron reduced from raw materials.

10. A method as claimed in claim 1, wherein the melt is prepared from the catalysts and usual raw materials for the production of insulating materials from mineral fibers.

11. A method as claimed in claim 10, wherein the mineral fibers are selected from diabase, basalt, limestone, dolomite and raw materials obtained during production or recycling.

12. A method as claimed in claim 1, wherein oxidic constituents contained in the melt are dissolved.

13. A method as claimed in claim 12, wherein the oxidic constituents are at least one of the rare earths La2O9, CeO2 and Pr6O11.

14. A method as claimed in claim 1, wherein fine-grained catalyst masses are pressed to lumpy bodies before they are melted open.

15. A method as claimed in claim 14, wherein residual materials taken from a primary waste cycle and/or silicious stones are used as supporting grain and/or binders and are added to the fine-grained catalyst masses.

16. A method as claimed in claim 15, wherein the constituents of the melt are mixed before they are fed to the melting unit.

17. A method as claimed in claim 1, wherein the catalysts are blown through blast forming into the melting unit.

18. A method as claimed in claim 17, wherein the blast forming is performed in a shaft furnace.

19. A method as claimed in claim 1, wherein the catalysts are preheated before they are fed to the melting unit.

20. A method as claimed in claim 19, wherein the preheating temperature is 600° C at maximum.

21. A melt for producing mineral fibers for a mineral fiber web, which can be made into insulating materials, wherein oil refining catalysts that are no longer usable are used to prepare a silicious melt.

22. A melt as claimed in claim 21, wherein the catalysts originate from cracking and/or hydrocracking processes.

23. A melt as claimed in claim 21, wherein the catalysts are mixed with residual materials from a primary waste cycle and/or recycling materials from the mineral fiber production.

24. A melt as claimed in claim 21, wherein 20 - 60% by weight of SiO2 and 10 - 60% by weight of Al2O3 are present.

25. A melt as claimed in claim 24, wherein 10 - 30% by weight of Al2O3 are present.

26. A melt as claimed in claim 21, wherein the catalysts have a grain size of between 2 and 6 mm.

27. A melt as claimed in claim 21, wherein the catalysts have a mean diameter of between 30 and 100 µm.

28. A melt as claimed in claim 21, wherein the catalysts are formed as extrudates.

29. A melt as claimed in claim 21, wherein the catalysts comprise 10 - 30% by weight of metals Ni or W.

30. A melt as claimed in claim 26, wherein the grain size is between 3 and 4 mm.

31. A melt as claimed in claim 27, wherein the mean diameter is between 50 and 70 µm.

32. A melt as claimed in claim 28, wherein the length of the extrudate is between 1 and 5 mm.

33. A melt as claimed in claim 28, wherein the length of the extrudate is between 2.5 and 3 mm.

34. A melt as claimed in claim 29, wherein the catalysts comprise 15 - 25% by weight of the metals Ni or W.

35. A melt as claimed in claim 21, wherein the catalysts comprise 15 - 35% by weight of CoO and MoO3.