FR2499970A1 - PROCESS FOR THE PREPARATION OF FIRE RESISTANT OR REFRACTORY MATERIALS, GRANULAR, CONTAINING CERAMIC FIBERS, MATERIALS PREPARED ACCORDING TO SAID METHOD AND USE THEREOF - Google Patents

Abstract

PROCESS FOR THE PREPARATION OF FIRE-RESISTANT OR REFRACTORY MATERIALS, GRANULAR, CONTAINING CERAMIC FIBERS, MATERIALS PREPARED ACCORDING TO THIS PROCESS AND THEIR USE. THE PRESENT INVENTION CONCERNS A PROCESS CONSISTING OF PREPARING A FIRE-RESISTANT OR REFRACTORY MATERIAL, GRANULAR, CONTAINING CERAMIC FIBERS, CLAY, AN ORGANIC BINDER AND OPTIONALLY OTHER USUAL ADDITIVES, MIXING THESE PRODUCTS WITH WATER, TO COMPACT THEM TO A COMPACTION VOLUME OF AT LEAST 2, TO DRY THE PRODUCT TO BE COMPACTED AND TO GRIND IT TO THE REQUIRED GRANULATION USE OF THIS MATERIAL IN FIBROUS MASSES TO SPRAY OR AS AN ADDITIVE TO REFRACTORY CONSTRUCTION ELEMENTS SOLICITED BY CONSTRAINTS .

Description

"Process for the preparation of fire-resistant materials or

  refractory, granular, containing ceramic fibers, mat-

  prepared by this process and their use. "

  The present invention relates to a process for the preparation of fire resistant or refractory, granular materials,

  containing ceramic fibers, containing ceramic fibers

  clay, a binder and possibly other usual additives, the material prepared by this process and its

use.

  Heat-insulating ceramic fiber bodies consisting of refractory fibers, organic or inorganic binder having on the one hand reduced strength and high compressibility and, on the other hand, high values for strength, density

  and the resistance to deformation, are known. Thus, the

  German Patent Application No. 12 74 490, filed and accepted in Germany, discloses a furnace combustion chamber which is formed by forming the fibrous mass mixed with binder and wherein the binder concentration is to decrease through the cross-section. Wall. Suitable binders are clays, alkali silicates,

  aluminum phosphate, colloidal silica with a proportion

  weight ratio of 5 to 35%, preferably 10%. But the fibrous body is not suitable to a sufficient extent for high loads because of its thick and hard wall surface

  and the soft and flexible opposite wall surface.

  In the process according to the German patent application filed and accepted in FRG No. 27 32 387, the mineral fiber plate bonded with an organic synthetic binder must be consolidated by impregnation with an aqueous suspension of a

  binder clay then by annealing. In addition, we know by

  German Patent Application No. 26 18 813, filed and accepted, for fibrous masses to be sprayed which contain, in addition to a large quantity of mineral fibers, reduced amounts of binder or other inorganic additives as well as an additional chemical binder, these fibrous masses to be sprayed still containing 5 to 20% by weight of an oil to prevent the formation of dust. When using these masses

  fibers to be sprayed, it is formally indicated that the

  minerals such as mineral wool are introduced

picks in the disintegrated state.

  The object of the present invention is a method for

  preparation of fire resistant or refractory materials,

  nularcontaining ceramic fibers which have in the transformed state an increased resistance, in particular vis-à-vis

  mechanical constraints, which may in particular be

  tagously used in what are called 'fibrous rmasses to project'

  To achieve this object, a process characterized by

  in that in a mixer are carefully mixed: nt (a) 100 parts by weight of ceramic fibers, 2 to 15 parts by weight of clay and / or of very finely divided Al 2 O 3 and / or SiO 2 very finely divided and and / or very finely divided aluminum hydroxides and / or magnesia and / or very finely divided titanium dioxide and / or very finely divided chromium oxide, optionally up to 10 parts by weight of other additives and 1 to 10 parts by weight of organic binder, calculated in solid form, with about 25 parts by weight of water and (b) the mixture obtained in the

  stage (a) is compacted to a volume factor of atu minus 3.

  dried and ground to the desired granulation.

  The preferred embodiments of the process are

  characterized by the use of clay-like bentonite, disintegrated fibers such as ceramic fibers, and molasses. of

  sulphite waste liquor in solid form or as solu-

  methylcellulose in solid form and / or as a solution in water as binder, pulverized porcelain or Chamotte as a refractory additive and in that

  compaction in stage (b) is carried out at a factor of

  lume 5 to 8, or using a plodder but taking the precaution of using in stage (a) up to 100 narties by weight of water for the preparation of the mixture, or in a

- briquetting device.

  The present invention furthermore relates to the material

  both fireproof and granular refractory, containing

  prepared according to this process, which has properties

particularly good.

24999 70

  The ceramic fibers or the mineral fibers used in the process according to the invention may be any of the usual fibers of this kind, for example mineral wool or aluminum silicate fibers having a particularly high Al 2 O 3 content, in the range of 45 to 95% by weight. Of course, it is also possible to use mixtures of

different ceramic fibers.

  The clay used in the process according to the present invention may be a conventional clay or a binder clay

  special, for example bentonite. This clay is usually

  used in an amount of from 2 to 15 parts by weight per 100 parts by weight of ceramic fibers. In addition,

  it is possible in the process according to the invention to use up to

  than 10 parts by weight of other refractory additives such as for example pulverized porcelain and chamotte. The

  other very finely divided constituents

  in the composition of granular materials according to the invention such as very finely divided Al 2 O 3 and / or very finely divided SiO 2 and / or aluminum hydroxides and / or very finely divided magnesia and / or very finely divided titanium dioxide and / or very finely divided chromium oxide

  are constituents used as is known in the field of

  do refractories. By the expression "very finely divided" used here in relation to the constituents mentioned above, it should be understood that these constituents are in the very finely ground state or also in the colloidal state. In particular, when using these colloidal materials such as colloidal SiO 2 or colloidal aluminum oxide, it is possible to use only reduced amounts of binder, i.e. the lower limit value of a

part by weight of such a binder.

  Advantageously, the overall amount of clay and / or

  other very finely divided constituents plus other addi-

  refractories, amounts to 20 parts by weight per 100

  by weight of ceramic fibers.

  The organic binders used in the process of the present invention are the usual binders of the preferred type, which

  in the case of sulphite waste liquor and more particularly

especially methylcellulose.

  Organic binders are usually used in the form of a concentrated solution, a portion of the organic binder, preferably up to 50% by weight, but may also be used in finely divided solid form. In the case where methylcellulose is used as a binder, this is usually carried out in the form of a 5% by weight solution in water. The sulphite waste liquor can be used in the form of sulphite waste liquor with a solids content of about 50% by weight,

  but it is also possible to use the sulphidic waste liquor

only finely sprayed.

  The mixture of constituents of stage (a) of the process

  form of the present invention can be carried out in a mixer

  classic, for example in a mixer Drais.

  In an advantageous embodiment of the process according to the present invention, the ceramic fibers are

  used in the form of disaggregated fibers, in stage (a).

  For this, we put the current fibers of trade in their

  state of delivery, in a blender with a turbine (rapid mixer

  turbulent brand * Drais) or the fibers usually delivered-

  in the form of bundles of fibers are transformed into

  broken bones. This turbine mixer consists of a mixing unit with fast rotating milling cutters, thanks to which the aggregates, possibly present in the common fibers partly in compacted form, are broken up without

  that the fibers are strongly crushed or crushed

inadmissible.

  Naturally, it is also possible to mix the constituents to be mixed in stage (a), that is to say the clay and / or the other very finely divided constituents, optionally the other refractory additives and the organic binder if is used in solid form, with the fibers, in a turbine mixer of this type, which at the same time produces a disintegration of the fibers and a mixture particularly

  good and homogeneous with the constituents added in stage (a).

  Then, the eventually dissolved binder and the water are then

added and mixed.

  The mixture obtained in stage (a) of the process according to the present invention must be compacted to a volume factor of at least 3. This can be done advantageously in an extruder. In addition, this compacting can be carried out in a rotary press or in a conventional briquetting device, but it is also possible to use any other conventional press. In the process according to the invention, compaction must take place

  at a volume factor of at least 3, preferably the compaction

  This is done at a volume factor of 3 to 6. The maximum compaction volume factor is about 12 to 14. Then, the compacted product at a volume factor of at least 3 is dried, usually at between 110 and 1800C until the water contained is removed almost completely or completely. The pieces then obtained are ground to the desired granulation, the maximum size of the grains

  being usually 8 mm and advantageously 6 mm. How-

  Milling can also be adjusted in a given range, for example a product having a granulation of between 2 and 3 mm or a maximum grain size of up to 2 mm or 3 mm can be obtained simply by grinding in a milling device.

  usual and possibly by sieving to the desired granulations.

  The granular material obtained according to the process according to the present invention has a density of 0.7 to 1.75 g / cm 3 and has a pore volume of the order of magnitude of

from 35 to 75%.

  The granular material obtained according to the compliant process

  the present invention can be used in particular

  suitable for fibrous masses to be sprayed. To this effect

  The material can be either dried in the dry state at a spray nozzle at the top of which it is mixed with water and with another binder or other mineral additives, or be prepared as a suspension with water and at least one inorganic binder then sprayed. As such additives, either phosphate binders or even hydraulically-bound binders, such as Portland cement or

  Extremely refractory cements such as aluminous cement

  of the, can be used, also the addition of other customary additives is possible when using as a fibrous mass to be sprayed.Also a spray by

  addition of water, binder and ceramic fiber is possible.

  When using the granular material in accordance with the

  In the case of fibrous masses to be sprayed, it is advantageous for these fibrous masses to be sprayed to require little water for spraying, which can save up to 50%

  of water. In addition, fiber nebulization is largely

  cloud. When used in accordance with the present invention in fibrous masses to be sprayed, they are used in packings in particular for the insulating coating of ovens

  for heat treatment or as insulating protective layers

  These fibrous masses to be sprayed on refractory materials can also be used for the subsequent insulation against the fire of already existing packings, for example for repairs. In the case of this use, when spraying the fibrous masses to be sprayed, another binder resistant to high temperatures, for example a phosphate binder or a molten aluminous cement, must of course be used.

to be present in these masses.

  A particularly advantageous use of the fibrous masses to be sprayed relates to the spray application of

  boiler room ceilings. These ceiling heating coatings

  are described, for example, in the German patent application.

  In this case, the felts made of temperature-stable fibrous material are fixed by means of fasteners and the last layer of felt is then

  covered completely with a protective layer of

  light weight construction stable at high temperatures.

  In the use according to the invention, the fibrous masses

  For projecting, it is possible to spray such ceiling constructions with the fibrous masses to be sprayed of the present invention which, after drying, give a compact insulation layer which does not require any

cover plate.

  Another advantage of the fibrous granulation according to the invention lies in the fact that the organic binder during the use of these fibrous granules, whether they are

  as such or in the form of aggregates added to other

  The refractory or refractory shaped bodies burn at high temperatures partially or completely, for example at temperatures above 5000.degree. C., so that the elementary grains of this material no longer retain any binder, so that the elastic properties of the fibers ceramics

  reappear clearly. When using granular

  For example, in the form of an additive in a refractory mass, there is the advantage that, after the combustion of the organic binder, the elementary grains of the fibrous granulation are elastic so that, thanks to

  this, to fire-resistant or refractory building

  prepared from these masses, is conferred the property of

  It is advantageous that the internal tensions occurring can be balanced. This leads to the fact that these fire resistant or refractory construction elements

  the fibrous granulation according to the present invention,

  Feel less cracking1because tensions are removed

  by the elastic elemental grains of the granulation

fibrous.

  In the process according to the invention, different amounts of water are used in the preparation of the mixture

  in the stadium (a). The amount of water used depends critically

  the device in which the mixture obtained in the

  stage (a) is then compacted in stage (b). When this

  pumping is carried out in a briquetting device or in a rotary press, amounts of water of 5 to 25 parts in

  are sufficient, however, if the compaction is

  killed on a boudery, the amount of water to be added to the

  stage (b) is higher and can be up to 100

  by weight. Based on simple preliminary tests, the amount of water to be used can simply be

  determined. The amount of water used also depends on the

  of the quantities used in stage (a) of clay, of very finely divided Al 2 O 3 or of the other very finely divided constituents mentioned, so that in particular when using SiO 2 colloidal alum of colloidal Al 2 O 3,

  Larger amounts of water can be beneficial.

  The present invention is explained in more detail using the examples below. In these examples, ceramic fibers A having 47% Al 2 O 3 and 53%

  B fibers having 95% Al 2 O 3 and 5% SiO 2.

EXAMPLES 1 to 5

  The following compositions are used:

Example

Si02 is used) or

4 5

  Ceramic Fibers A B Ceramic Fibers Binder Clay (35%

A1203)

  Chromium oxide Z-_ 63 ym SiO2 colloidal A1203 colloidal Methylcellulose, solid Sulphite wastewater, solid Chamotte flour Water -

--- 100 100

6

--- 50

50

4 -

2 __

1

7 2

0 15

2 4

4 1

12 25

  In an Eirich mixer, the ceramic fibers are

  the binder clay or with the other constituents for 5 minutes, then the organic binder or the binder mixture is added and finally the water is added. The mixture

lasts a total of 20 minutes.

  This mixture is compacted in a briquetting device (KHD brand) to the volume units indicated and is dried for 12 hours at 120 ° C. and then milled to a maximum grain size of about 6 mm. On the fibrous granulations obtained, the following properties are determined:

Example

  Apparent Density, R, (g / cm3) Compaction Factor Pore Volume, Pg, (% by volume)

EXAMPLES 6 to 10

1 2 3

1, -25, 4 1.09 7.2

49.5 69.7

1.15 6.8

4 5

1.20 6.0 1, 23 6.5

68.0 53.8 62.6

  The operations of Examples 1 to 5 are repeated, but in use

  here reading broken fibers. The disintegration of the fibers takes place in a turbine mixer (brand "Drais") for 5

  minutes. Then the usual additives are added and mixed

for 2 minutes.

  The compaction is carried out in a hydraulic press, in bricks of 250 x 125 x 30 mm, these are dried 12 hours at 120 C and then crushed to a maximum grain size

  6 mm. The fibrous granulations obtained are determined

  the following properties: Example 6 7 8 9 10 R (g / cm3) 1.10 0.95 1, 01 1.04 1.04 Compaction factor 6.0 7.9 7.2 6.9 7.3 Pg (% in volum.e) 56.0 73.5 71.7 59.9 66.6

EXAMPLE 11

  The procedure of Example 6 is repeated except that 80 parts by weight of water are mixed. The compaction is carried out in a plodder, the cross section of the die being 250 x 190 mm. The raw cakes coming out of the extruder are

  cut into appropriate length and dried for 24 hours at 120 C.

  Then, the dried patties obtained are ground to a size

  maximum grain size of 3 mm. On the fibrous granulation obtained

  the following properties are determined: R (g / cm3) 0, 95 Compaction factor 3.2 Pg (% by volume) 62.7

Claims (13)

  1.- Process for the preparation of resistant materials   with fire or granular refractories, containing ceramic fibers   comprising ceramic fibers, clay, a binder and possibly other conventional additives, characterized by the fact that:   a) 100 parts by weight of ceramic fibers, 2 to 15 parts   by weight of clay and / or Al 2 O 3 very finely   divided and / or very finely divided SiO2 and / or hy-   very finely divided aluminum and / or magnesia droxyds and / or very finely divided titanium dioxide   and / or very finely divided chromium oxide, possibly   up to 10 parts by weight of other additives   refractories and one to 10 parts by weight of organic binder   the solid form, with about 5 to 25 parts by weight of water are mixed well in a kneader, and b) the mixture obtained in stage (a) is compacted to a volume factor of at least 3, dried, then ground to the desired granulation.   2. A process according to claim 1, characterized by   Bentonite is used as clay.   3. A process according to claim 1, characterized by   disintegrated fibers are used as CERAMICS.   4. A process according to claim 1, characterized by   the fact that molasses is used as a binder.   5. Process according to any one of the claims   1 to 3, characterized in that the sulphurous waste liquor   tick; in solid form or in the form of a solution, is used as a binder.   6. Process according to any one of the claims   1 to 3, characterized by the fact that methylcellulose, under   solid and / or as a solution in water, is used as a binder.   7. A process according to claim 1, characterized in that the pulverized porcelain or the chamotte is used as another refractory material. 1l   8. Process according to any one of the claims   preceding, characterized by the fact that compaction in   stage (b) is carried out at a volume factor of 5 to 8.   9. A process according to claim 1, characterized in that in stage (b) the compaction is carried out by extruders but then using in stage (a) up to 100 parts by weight of water for the preparation of the mixture. 10. A process according to claim 1, characterized in that in stage (b), compaction is carried out in a briquetting device.   11.- Fire-resistant or granular refractory material   re, containing ceramic fibers prepared according to the process   described in any one of claims 1 to 10.   12.- Use of fireproof or refractory material   tarygranular containing ceramic fibers in to project.   13.- Use of fire-resistant or refractare material, granular> containing ceramic fibers, as an additive in fire-resistant or refractory construction elements}   subject to tension during use.