DD202040A5 - PROCESS FOR PRODUCING CERAMIC FIBERS CONTAINING, FIRE-RESISTANT OR FIRE-RESISTANT MASSES - Google Patents

Abstract

A method for producing fire-resistant or refractory masses containing ceramic fibers by sequentially mixing 100 parts by weight of ceramic fibers, 10-40 parts by weight of water, 5-20 parts by weight of clay and / or finely divided refractory oxides, 0.5-4 parts by weight of organic binders in solution, and 1-8 parts by weight of phosphate binder, the mixture optionally being dried and comminuted to a comminution. The mass is used as a spray mass, as filling material for expansion joints and for the production of components.

Description

7/0 1 / Berlin, 22.6.1982

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Process for the preparation of fire-resistant or refractory masses

Field of application of the invention

The invention relates to a process for the preparation of ceramic fibers containing, optionally granular, fire-resistant or refractory compositions, the masses prepared by the process or fiber granulations and their use,

C characteristic of the known technical solutions

Heat-insulating ceramic fiber bodies made of refractory fibers, organic or inorganic binder with low strength and high compressibility on the one hand and increased values for strength, density and dimensional stability on the other hand are known. .So describes the DE-AS 12 7.4 490 a combustion chamber for furnaces, which by Ausforraung the mixed with binder fiber. A suitable binder is clays, alkali metal silicates, aluminum phosphate, colloidal silica with a weight fraction of 5 to 35, optimally 10 % _t . However, the fiber body is not sufficiently suitable for high loads because of its dense hard wall surface and the opposite soft flexible wall surface.

In the process according to DE-AS 27 32 387 prebound with an organic plastic binder

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Mineral fiber board are impregnated by impregnation with an aqueous slurry of a binding clay and subsequent tempering. Furthermore, DE-AS 26 18 discloses fiber spraying compositions which, in addition to a larger proportion of inorganic fibers, contain small amounts of binder or other inorganic additives, or a chemical agent In order to avoid the formation of dust, these fiber spraying compositions also contain 5 to 20% by weight of an oil. [Fas Bei] When using these fiber spraying compositions, it is expressly stated that the inorganic fibers, such as rockwool, are used in a loosened state ,

Object of the invention

The aim of the invention is the provision of novel fire-resistant or refractory masses * which can be used as a main component in fiber spraying or "as a supplement in the production of refractory or refractory moldings and have particularly good properties, and, in the event that they are in moist form can be used as such »

Explanation of the essence of the invention

The invention has for its object * ceramic fibers containing, fire-resistant or refractory masses, optionally in the form of a fiber grain to produce.

According to the invention, ceramic fibers containing fire-resistant or refractory compositions, which are ceramic

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Fibers, clay and binders, produced in such a way that

a) 100 parts by weight of ceramic fibers with 10 to 40 parts by weight of water are mixed in a mixer,

b) the product obtained in step a) mixture is from 5 to 20 weight parts by _# clay and / or finely divided ^A l? ⁰ 3 ^uncl / or finely divided SiO ₂ and / or aluminum hydroxides and / or finely divided magnesia and / or finely divided titanium dioxide and / or finely divided chromium oxide, and 0 to 10 .We are added parts of solid organic binder and mixed therein .

c) 0.5 to 4 parts by weight of an organic binder, calculated as a solid, in solution, and 1 to 8 parts by weight of a phosphate binder, calculated as PpO, are added and mixed into the mixture obtained in step b), and

d) is obtained in step c) mixture is optionally dried and granulated.

It is advantageously as. Clay bentonite used; as ceramic fibers, pulped fibers are used; as organic binders methyl cellulose, sulfite waste liquor or molasses is used and as phosphate binder monoaluminium phosphate or sodium polyphosphate in dissolved and / or solid form.

The invention furthermore relates to the use of the granular, fire-resistant or refractory materials produced by the process according to the invention, in particular in fiber spraying compositions or as aggregate in the production of refractory materials or refractory forates ",

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The kera used in the inventive method ~ ^r. Mixing fibers or mineral fibers may be all conventional fibers of this type, for. As rock wool or fibers based on aluminum silicate with in particular high Al ₂ O content in the range of 45 to 95 wt .-%, Of course, mixtures of different ceramic fibers can be used.

Ceramic fibers, when delivered, are in the form of a loose volume. which, however, is in some cases highly compacted. In order to produce the compositions according to the invention, these fibers can advantageously be used in an open-ended form, whereby better bonding of the fibers by the binder used and excellent wetting of the surface by liquids in the lowest concentration becomes possible. For the digestion of the fibers, mixing units with rapidly rotating mixer heads, so-called turbomixers, can be used, whereby the larger agglomerates present in the as-delivered state of the fibers are digested without the fibers being smashed inadmissibly.

The clay used in the process according to the invention may be a common clay or a specific binder clay, eg, bentonite. This clay is usually used in an amount of 5 to 20 parts by weight per 100 parts by weight of the ceramic fibers. Advantageously, 8 to 15 parts by weight of clay are used.

The constituents optionally present in the composition of the compositions according to the invention are finely divided

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Al ₀ O and / or finely divided SiO ₂ and / or aluminum hydroxides and / or finely divided magnesia and / or Fe-Bt divided titanium dioxide and / or finely divided chromium oxide are components known to be used in the refractory art in the context of the abovementioned constituents, it is to be understood that these constituents are in the finely ground or in the colloidal state. In particular, when using such colloidal materials as colloidal SiO ₂ or »colloidal alumina, it is possible to use only small amounts of binder, namely close to the lower limit of 1.5 parts by weight of an organic binder and the Gew # part of a Phosphate binder to use. The use of about equal parts by weight of phosphate binder and methylcellulose as organic binder is particularly preferred. It is also particularly advantageous to use a mixture of clay and one or more of the previously mentioned other finely divided refractory components, the amount of these other, finely divided refractory constituents usually constituting 1 to 3 parts by weight and the remainder being clay, _ so that in total the specified in the claim amount of 5 to 20 parts by weight of refractory components is added «

The process of the invention uses an organic binder. For this purpose, all organic binders commonly used in this field may be used, for example methylcellulose, sulphite liquor or molasses. These organic binders are usually in the form of a solution in water or

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sometimes added in solid form, this is especially true for the use of methyl cellulose. Since 0.5 to 14 parts by weight of the organic binder is used on 100 parts by weight of ceramic fibers, and since methylcellulose is usually used in the form of a 5% solution, since higher-percent solutions become too viscous, the Addition of the solution of the organic binder introduced Wassermeng'e too large, so that in particular in the case of methyl cellulose up to 50 Gevu-% of this organic binder are added in solid form. -

In the process according to the invention, from 1 to 8 parts by weight and preferably from 2 to 6 parts by weight of a phosphate binder are used, the amounts stated in parts by weight being based on Pp ⁰ - in the particular binder.

Examples of such phosphate binders are sodium polyphosphate having a degree of polymerization of η 2 4 and preferably having a degree of polymerization of from 6 to 10. This sodium polyphosphate is usually used in dissolved form. Another phosphate binder is monoaluminum phosphate, which is a commercial product both in solid, milled form or as an aqueous solution, especially as a 50 wt% solution. The phosphate binder may be added either as a whole in the form of a solution, or the phosphate binder may be partially added in dissolved and partly in solid form *

In the manufacture of the ceramic fibers in a mixer, usually a drum mixer or a

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Ploughshare mixer mixed with 10 to 40 parts by weight of water per 100 parts by weight of the ceramic fibers used, the water is sprayed suitably.

In total, in the process according to the invention up to about 100 parts by weight of water are added, partly in step a) and partly in step c) when the organic binder is added in dissolved form and the phosphate binder, if this is added in dissolved form »

After mixing to homogeneous state, the clay and / or the other, previously mentioned, very finely divided refractory constituents, which are in dry, finely divided form, placed on this Geraisch in the mixer and also mixed homogeneously. In this case, the clay and / or the other, previously mentioned, most far-divided refractory components adhere to the surface of the wetted fibers »Also added in this stage, if necessary, added solid organic binder» Then the solution of the organic binder is applied to the previously obtained mixture , also the solution of the phosphate binder, wherein the possibly added amounts of solid, inorganic binder are entered simultaneously with the solution of the binder or 'after the addition of this binder in the mixer.

The mixture is then mixed homogeneously, but this mixing process can take up to 30 minutes. «

The mass obtained in this way can be used as such, for example "B, to which users are delivered in barrels as ramming mass"

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Alternatively, however, this wet mass can also be converted into a fiber grain, as described in more detail below. After homogeneous mixing, the finished mixture is dried, usually at temperatures above 100 ⁰ C, z. B, 110 ⁰ C to 180 ⁰ C. The drying time is advantageously 2 to 24 hours. Subsequently, the thus-obtained solid cake in a conventional crushing device ,, ζ. Β. a hammer mill or a roll crusher, crushed to the desired particle size. Comminution usually takes place up to a maximum grain size of 8 mm, advantageously 6 mm, but it is also possible to set a maximum grain size of 2 or 3 mm depending on the intended use of the material produced * Oe according to intended use, it is also possible desired sieve size fractions auszusieben from the material produced by the process according to the invention.

The granular material obtained by the process according to the invention has a density of 0.12 to 0.50 and has a total porosity of the order of 95 to 80 % .

The high proportion of organic binder in the granular material makes it possible for the granular material to have a lower density, so that the effect of density increase, which is given by the addition of clay and / or other finely divided refractory components , becomes canceled or largely compensated * When using the granular material "d * h" obtained by the process according to the invention as soon as it reaches higher temperatures such as 3; is brought above 500 C, the organic binder obtained in it burns completely or partially depending on the temperature reached

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so that an even more porous product is obtained which has particularly good heat insulation properties.

Another advantage of the obtained / inventive granular material is that after complete or teilveveisen burning of the organic binder, the elastic properties of the ceramic fibers are retained in the individual grains, so that a material in which obtained by the process according to the invention , granular material was used as a "surcharge, partially elastic properties obtained because the individual grains remain elastic in itself. This is achieved in that in the inventive method to the moistened fibers, first the clay and / or the other very finely divided refractory components are applied and then, first the phosphate binder is added, so that this phosphate binder remains largely on the surface of the clay particles almost enveloped with clay, so that either no or only a small amount of phosphate binder is contained inside the grain the core remains so that the fibers remain elastic.

The granular material obtained by the process according to the invention can - as already described - be used particularly well in fiber spraying masses. For this purpose, the material is mixed either in the dry form of a spray nozzle at the top of which it is mixed with water and optionally other binders or additives. supplied, or it is a slurry of the granular material with water and optionally other additives prepared and sprayed. Such conventional, further additives can

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For example, be hydraulically setting binders such as Portland cement or alumina or other additives. Furthermore, ceramic fibers and water can be scribed together with such a grain according to the invention. *

When using the granular material according to the invention in fiber spraying compositions there is the advantage that these. Fiber spraying masses require less water than conventional fiber spraying compounds during spraying / whereby the water savings can amount to up to 50 % »

Particularly advantageous is the invention, wet mass used as elastic and resilient Dehnfugenfüllmasse. Such use is particularly advantageous between the stones of the rotary kiln, as this mass retains partial elastic properties at the application temperatures. "Another advantage is that the ceramic fibers, unlike too often used in such expansion joint materials, are not harmful to health."

In this application, the mass is advantageously packed in the desired thickness, between 2 to 8 mm thick, between plastic films and can be used as a plastic layer with the films enveloping it when lining a furnace as an intermediate layer, ie, expansion joint filling , be inserted. This can be, for example, an endless role of the plastic film wrapped between plastic sheets of the mass, but it can also be prefabricated and fixed in their dimensions individual packs of wrapped between the plastic films or possibly

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also act as shrink-wrapped plastic mass in layer form. From the roll, the desired lengths can be cut.

Ausführuncjsbeispiel

The invention will be explained in more detail with reference to the following examples.

In the examples ceramic fibers A and B were used, which had the following chemical composition:

Fibers A) Al ₂ O ₃ = 47 %; SiO ₂ = 53 %; Fibers B) Al ₂ O ₃ = 95 %; SiO ₂ = 5 % »

Examples 1 to 3

The following approaches were used, the data refer to weight steep ":

Fibers A. 100 100 100 H ₂ O 30 15 40 bentonite 10 - 15 Al ₂ O ₃ 5 5 - TiO ₂ - 2 1 Methylcellulose 4 - 3.5 Sulphite waste liquor solid - 5 - SuIfitablauge solution 10 weight 9hic! 2 _

Methylcellulose solution-

5% w / w 0 _# 5 - 3

fionoaluminium phosphate solid 4 -. , 8th

Sodium polyphosphate solid - 2.5 - -

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First, the ceramic fibers were placed in an Eirich mixer and sprayed on the indicated amounts of water and 10 Hinuten mixed * Then the bentonite, the Al ₂ O or, TiO_, and the solid methylcellulose or the solid sulfite liquor was on this mixture and vveit -mixed for 8 minutes. Thereafter, in the mixer, the indicated solutions of sulfite liquor or, methyl cellulose, to which the finely divided, solid phosphate binder had been added, sprayed and mixed for a further 10 minutes.

The resulting crumbly mixture was taken out of the mixer.

The crumbly mixture of Examples 1 and 2 was dried for 6 hours at 120 C and then comminuted in a roll crusher to a maximum grain size of 4 mm. The crumbly product of Example 3 was used as a plastic mass, for this purpose it was spread to a plastic, 5 mm thick layer, which was wrapped in plastic films. Such a plastic layer, which is packed in plastic films, could be successfully used as Dehnfugenfüllmaterial between burned stones -in rotary kiln in the delivery of such rotary kiln.

The properties determined on the products wareo as follows:. -

Eg, - · 1_ 2 3

Rough weight, g / cm. 0.22. 0.14 0.40

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Example 4 to 5 "

The procedure of Examples 1 to 3 was repeated, but here, digested, ceramic fibers B were used. The fibers were pulped in a turbo-blender (manufactured by Drais), for which the fibers were treated in this cutter-equipped high-speed mixer for 5 minutes. These disrupted fibers B were then transferred to an Eirich mixer, into which the further components correspond were added to the batches of Examples 1 to 3.

From the products of Examples 4 and 5, a fiber grain was also prepared, the Pro.dukt the example was used as ramming mass »

The properties determined on the products were as follows:

Ex. ^ _ 4 5 6

Density, (g / cm ³ ) 0.25 0.17 0.45

Claims (3)

7 42 1L ²²·⁶·¹⁹⁸² AP C 09 K / 237 421/4 - 14 - 60 421/18 Erfindu s ngsan Pruch 1 «process for the production of ceramic fiber-containing, fire-resistant or refractory compositions containing ceramic fibers, clay and binder, characterized in that a). 100 parts by weight of ceramic fibers are mixed with 10 to 40 parts by weight of water in a mixer, b) to the mixture obtained in step a) 5 to 20 parts by weight of clay and / or finely divided A1_O and / or finely divided SiO ₂ and / or aluminum hydroxides and / or finely divided magnesia and / or very fine. divided titania and / or finely divided chromium oxide, and from 0 to 10 parts by weight of solid, organic binder are added and mixed therein, c) to the mixture obtained in step b) 0.5 to 4 parts by weight of an organic binder, calculated as a solid, in solution, and -1 to 8 parts by weight of a phosphate binder, calculated as P ₂ O ^, are charged and mixed, and d) the mixture obtained in step c) is optionally dried and granulated. 2 _t method according to item 1, characterized in that bentonite is used as the clay. 3. The method according to item 1, characterized in that fibers used as ceramic fibers are " 22.6.1982 AP C 09 K / 237 421/4 - 15 - 60 421/18 4 »Process according to item 1» characterized in that deQ is used as organic binder methylcellulose. 5 »Process according to item i, characterized in that the organic binder used is sulfite waste liquor or molasses, 6. The method according to item 1, characterized in that is used as the phosphate binder Monoaluminiuniphosphat or sodium polyphosphate in dissolved and / or solid form. 7 «Ceramic fibers containing, optionally granular, fire-resistant or refractory mass, characterized in that it is prepared by the method according to one of the items 1 to 5 _# 8 * Use of granular, fire-resistant or refractory mass containing ceramic fibers, characterized in that it is used in fiber-spraying masses » 9 »Use of granular, fire-resistant or refractory mass containing ceramic fibers, characterized in that it is used as aggregate in fire-resistant or refractory components subject to stress in operation» 10 * Use of the wet fiber containing ceramic fibers, characterized in that it is used as DehnfugenfQllmaterial, optionally as a wrapped in plastic films, plastic layer.