FR2499971A1 - PROCESS FOR THE PREPARATION OF FIRE RESISTANT OR REFRACTORY MASSES CONTAINING CERAMIC FIBERS, MASSES PREPARED ACCORDING TO SAID METHOD AND THEIR USE - Google Patents

Abstract

THE PROCESS CONCERNED BY THIS INVENTION CONSISTS OF MIXING CERAMIC FIBERS WITH WATER, THEN OF ADDING CLAY OR OTHER VERY FINALLY DIVIDED REFRACTORY ADDITIVES AS WELL AS A SOLID ORGANIC BINDER, THEN ON THE MIXTURE OBTAINED, ADD A ORGANIC BINDER IN SOLUTION AS WELL AS A PHOSPHATE BINDER, TO DRY THE NEW MIXTURE OBTAINED AND TO GRIND THE DRY MIXTURE. USE OF THE REFRACTORY MATERIAL OBTAINED, IN FIBROUS MASSES TO BE SPRAYED, OR AS AN ADDITIVE FOR CONSTRUCTION ELEMENTS STRESSED BY TENSIONS DURING THEIR USE, OR AS A PADDING MATERIAL FOR EXPANSION JOINTS IN THE FORM OF WET MASS IN PLASTIC SHEET OR LAYER OF SYNTHETIC MATERIAL.

Description

Process for the preparation of fire-resistant or refractory masses

  containing ceramic fibers. The present invention relates to a method for

  preparation of fire-resistant or refractory masses, possibly

  granular, containing ceramic fibers, the masses or fibrous granules prepared according to this

  process and their use.

  The ceramic fiber cores consisting of refractory fibers, an organic or inorganic binder, having on the one hand low strength and high compressibility and on the other hand high values for strength, density and resistance to deformation are known . Thus, the German patent application filed and accepted in FRG No. 12 74 490 describes a furnace combustion chamber which is formed by forming the fibrous mass with added binder, and in which the concentration of binder must decrease through the cross-section. Wall. As a suitable binder, clays, alkali silicates, aluminum phosphate, colloidal silica, with an amount by weight of 5 to 35, more preferably 10%, are indicated. But the fibrous body is not suitable to a sufficient extent for high loads because of its thick and hard wall surface, and the wall surface

opposite soft and flexible.

  In the process according to the German patent application filed and accepted in R.F.A. 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 and then by annealing. In addition, according to the German patent application filed and accepted in FRG No. 26 18 813, fibrous masses are known to be sprayed which, in addition to a large amount of mineral fibers, small amounts of binder or other additives minerals, still contain a binder

  these fibrous masses to be projected

  still 5 to 20% by weight of an oil for pocketing the formation of dust. When using these fibrous masses to be sprayed, it is formally indicated that the mineral fibers, such as mineral wool, are introduced in the disintegrated state. The object of the present invention is the preparation of fire-resistant or refractory masses containing ceramic fibers, possibly in the form of a fibrous granulation, which can be used as the main constituent in the fibrous mass to be sprayed or also as additive for the

  manufacture of refractory masses or refractory moldings

  which have particularly good properties. In the case where the mass exists in wet form, it

can be used as it is.

  To achieve this object, use is made of the process according to the present invention which is characterized in that: a) 100 parts by weight of ceramic fibers are mixed in a kneader with 10 to 40 parts by weight of water, b) at mixture obtained in stage a) 15 to 20 parts by weight of clay and / or of very finely divided Al 2 O 3 and / or of very finely divided SiO 2 and / or of aluminum hydroxide and / or magnesia very finely divided and / or very finely divided titanium dioxide and / or very finely divided chromium oxide, as well as 0 to 10 parts by weight of a solid Organic binder are added and mixed therein, c) on the resulting mixture in step b), 0.5 to 4 parts by weight of an organic binder calculated as solids, in solution, and 1 to 8 parts by weight of a phosphate binder, calculated as P2O5, are added and mixed, and

  (d) the mixture obtained in stage (c) is

dried and granulated.

  Advantageous embodiments of the process according to the present invention are characterized by the fact that bentonite is used as clay; disintegrated fibers as ceramic fibers; methylcellulose, sulphite residual solution or molasses as organic binder, aluminum monophospite or sodium polyphosphate, in the form of

  dissolved and / or in solid form, as phosphate binder.

  The present invention furthermore relates to the use of fire-resistant or refractory, granular materials prepared according to the process according to the present invention, in particular to fibrous masses to be sprayed or in the form of an additive for the manufacture of refractory masses or

refractory profiles.

  The ceramic fibers or mineral fibers used in the process of the present invention may be any such conventional fibers, for example mineral wool or aluminum silicate fibers having in particular

  high levels of A1203 of the order of 45 to 95% by weight.

  Of course, mixtures of various ceramic fibers can

also be used.

  The ceramic fibers in the delivery state exist in the form of a bulk wool, but which is partly heavily compacted. For the preparation of the masses according to the present invention, these fibers can be advantageously used in disaggregated form, whereby a better binding of the fibers by the binder used and a remarkable wetting of the surface by the liquids in lower concentration is

  possible. For the breakdown of fibers,

  langeurs can be used with a fast-rotating mixing head, called a turbine mixer, by means of which the large agglomerates existing in the delivery state of the fibers are broken up, without the fibers being strongly

crushed in an inadmissible way.

  The clay used in the process of the present invention may be a conventional clay or a special binder clay, for example bentonite. This clay is usually used in an amount of 5 to 20 parts by weight per part by weight of ceramic fibers, more

  3) advantageous 8 to 15 parts by weight of clay are used.

  The constituents possibly present in the composition of the masses in accordance with the present 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 titanium dioxide very finely divided and / or very finely divided chromium oxide, are the constituents used as is known in the field of refractories. By the expression "very finely divided" used here in relation to the above-mentioned constituents, it is necessary to

  understand that these constituents are in a very

  In particular, when using these colloidal materials, such as colloidal SiO 2 or colloidal aluminum oxide, it is possible to use only reduced binder, that is to say near the lower limit value of 1.5 parts by weight of an organic binder and a part by weight of a phosphate binder. The use in substantially equal parts by weight of phosphate binder, and methylcellulose as organic binder, is particularly preferred. It is particularly

  advantageous to use a mixture of clay and one or more

  other refractory components very finely divided

  above, the amount of these other very finely divided refractory constituents being usually from 1 to 3 parts by weight and the remainder being clay, so that in all the amount indicated in this process is from 1 to 3 parts by weight; parts by weight of refractory component is added. In the process according to the present invention,

  uses an organic binder. For this purpose, all binders

  Commonly used in this field can be used, for example methylcellulose, sulphite waste liquor or molasses. These organic binders are usually added as a solution in water

  or even partially in solid form, this is especially

  valid for the use of methylcellulose. Since for 100 parts by weight of ceramic fibers, 0.5 to 14 parts by weight of the organic binder are used and since methylcellulose is generally used in the form of a 5% solution, since

  high concentration are viscous, the amount of water introduced

  the addition of the solution of the organic binder is then too great, so that especially in the case of methylcellulose, up to 50% by weight of this organic binder

are added in solid form.

  In the process of the present invention, moreover 1 to 8 parts by weight and preferably 2 to 6 parts by weight of a phosphate binder are used, the amounts given in parts.

  by weight being calculated as P2O5 in the binder in question.

  Examples for this phosphate binder are poly-

  sodium phosphate having a degree of polymerization of n> 4,

  and preferably having a degree of polymerization of 6 to 10.

  This sodium polyphosphate is usually used in dissolved form. Another phosphate binder is aluminum monophosphate, which is a commercial product both in solid ground form and as an aqueous solution, particularly as a 50% by weight solution. The phosphate binder can be added either totally in the form of a solution, or partly in dissolved form and partly in the form of a solution.

solid form.

  During the preparation, the ceramic fibers are mixed in a kneader, generally a barrel mixer or a ploughshare mixer with 10 to 40 parts by weight of water per 100 parts by weight of ceramic fibers put into place.

  the water being preferably sprayed onto the fibers.

  In the process according to the present invention, up to 100 parts by weight of water in total are added, partly in stage a) and partly in stage c), during the addition of the organic binder under dissolved form and

  phosphate binder, if added in dissolved form.

  After mixing to a homogeneous state, the clay and / or the other finely divided refractory components mentioned above, which are in the finely divided dry state, are added to this mixture in the catalyst and , also mixed in a homogeneous manner. Thus, the clay and / or the other refractory components very finely divided,

  mentioned above, they adhere to the surface of

  fied. Also in this stage, an additional solid organic binder is optionally added. Then, the solution of the organic binder is added to the mixture obtained and the solution of the phosphate binder, so that in this case the additional amounts of solid inorganic binder at the same time as the solution of Addition of this binder is added to the mixer. The mixture is further homogenized by mixing, so that

  the mixing process can take up to 30 minutes.

  The mass thus obtained can be used such that, for example, it can be delivered to the user transfused into

barrels in the form of rammed earth.

  But, by the way, this wet mass can be -

  also further transformed into a fibrous granulation, as described below. After mixing the mixture, the mixture is finished and dried, usually at temperatures above 1000 ° C., for example at 1100 ° C.-1800 ° C. The duration of

  drying is advantageously from 2 to 24 hours.

  Then, the solid cake thus obtained is milled in a conventional grinding device, for example a hammer mill or a roll mill at the desired grain size. The grinding is generally carried out up to a grain size of 8 mm maximum, advantageously 6 mm, but it is also possible, depending on the intended field of use of the material

  prepared, set a maximum grain size of 2 or 3 mm.

  Depending on the area of use, it is also possible to sieve desired particle size fractions from the material prepared by the process of the present invention. The granular material obtained according to the process of the present invention has a bulk density of 0.12 to 0.50 and has an overall porosity of the order of 95 to 80 Ait. Thanks to the large amount of organic binder in the granular material, this granular material is

  low density, that is to say, that the effect of the increase

  the density which is given by the addition of the clay and / or other very finely divided refractory constituents,

  again deleted or largely compensated. When using

  sation of the granular material obtained according to the process of the present invention, that is to say as soon as this material is heated to high temperatures, for example greater than 5000Cp

  the organic binder it contains grows completely or partially

  depending on the temperature reached, so that a still porous product is obtained, which in particular has good

heat-insulating properties.

  Another advantage of the granular material obtained according to the process according to the invention rests on the fact that after complete or partial roasting of the organic binder, the elastic properties of the ceramic fibers are maintained in the elementary grains, so that a material wherein the granular material obtained by the process of the present invention is

  used as an additive, acquires partially elastic properties

  because the individual grains remain elastic by themselves. This is achieved by the fact that in the process of the present invention is applied first the clay and / or the other refractory components very finely divided on the wet fibers, and that is added only the phosphate binder, of so that this phosphate binder remains largely on the surface of the particles of fibers almost covered with clay, so that within the grain there remains only a small amount of seeds containing the phosphate binder, so that

  that the fibers remain elastic by themselves.

  The granular material obtained according to the process of the present invention can, as already described, be used in a perfect way in fibrous masses to be sprayed. For that,

  the material is either brought in the dry state to a spray nozzle.

  It is mixed with water and optionally with other binders or other additives, either prepared in suspension with water and optionally with other additives, and then sprayed. Other customary additives of this kind may be, for example, water-hardening binders, such as Portland cement or aluminous cement, or even other additives. In addition, the ceramic fibers can be

  also sprayed together with water, with granular

  according to that of the present invention.

  When using the compliant granular material

  to the present invention in fibrous masses to be sprayed, the advantage

  is that these fibrous masses to be projected require

  less water than conventional fibrous sprays for spraying, which saves

up to 50% water.

  In a particularly advantageous manner, the wet mass of the present invention can be used in the form of an elastic and deformable expansion joint filling material. Such use is particularly advantageous between rotary tubular furnace bricks, since mass retains elastic partial properties at temperatures of use. Another advantage lies in the fact that ceramic fibers, unlike asbestos fibers often used in these materials for

  Expansion joints, are not dangerous for health.

  In this use, the mass is advantageously sandwiched between sheets of synthetic material in the desired thickness, for example in a thickness of 2 to 8 mm, and can be incorporated in the form of a plastic layer with the sheets which embedded in the walls of the brickwork of an oven, as an intermediate layer, that is to say as a packing of expansion joints. In this case, it may be for example

  of a linen-free roll of a plastic layer of the emer-

  quetée between the sheets of synthetic material but it can also be elementary packs prefabricated and adjusted e n dimensions of the plastic mass in the form of inserted layer, or even possibly welded inside, between the sheets of synthetic material. From the rolls, the

  desired lengths can be cut.

  The present invention is explained in detail at

using the following examples.

  In the examples, ceramic fibers A and B are used and have the following chemical composition: Fibers A) Al 2 O 3 = 47%; SiO2 = 535;

  Fibers B) A1203 = 95% f; SiO2 = 5%.

Examples 1 to 3

  The following compositions, the parts of which are expressed by weight, are used: Examples 1 2 3 Fibers A 100 100 100

H20 30 15 40

Bentonite 10 - 15

A1203 5 5 -

  Ti02 - 2 1 Methylcellulose, solid 4 - 3.5 Sulphite wastewater, solid 5

  Sulphite waste liquor, - 2 -

  10 wt.% solution Methylcellulose, 0.5 - 3 wt.% solution by weight Aluminum amonophosphate, solid 4 - 8

  Sodium polyphosphate, solid - 2,5 -

  The ceramic fibers are first introduced into an Eirich mixer, then the indicated amounts of water are sprayed and mixed for 10 minutes. Then, bentonite, Al 2 O 3 or TiO 2, solid methylcellulose or solid sulphite waste liquor are added to this mixture and the mixture is further mixed for 8 minutes. The indicated solutions of sulphite residual liquor or

  methylcellulose, to which the phospholitic binders have been added

  solid pulp finely pulverized, are added by pulveri-

  in the blender and mix for another 10 minutes.

  The lumpy mixture obtained is removed from the mixer.

  The lumpy mixture of Examples I and 2 is dried for 6 hours at 1200 ° C. and then milled in a roll mill at a grain size of up to 4 m. The lumpy product of Example 3 is used as a plastic mass to

  this is applied in a plastic layer having 5 mm thick

  which is packaged in sheets of synthetic

  tick. A plastic layer of this kind, which is packaged in sheets of synthetic material, can be successfully used as a filler for expansion joints between the bricks fired in the rotary kiln during

coating of this oven.

  The properties determined on the products are as follows: Examples 1 2 3 Apparent density, g / cm3 0.22 0.14 0.40

Examples 4k 6

  The procedure of Examples 1 to 3 is repeated, but

  using here disintegrated ceramic fibers B. The

  Fibers are mixed in a turbine mixer ("Draij" brand), for which the fibers are treated for a minute in this fast kneader equipped with cutters.

  Eirich mixer in which the other constituents correspond to

  from the compositions of Examples 1 to 3 are added.

  From the products of Examples 4 and 5 is also prepared a fibrous granulation; the product of example b

is used as rammed earth.

  The properties determined on the product are as follows: Exceptions 4 _5 6_.

6 Bulk density, g / cm3 0.25 0.17 0.45

Claims (10)

  Process for the preparation of fire-resistant or refractory masses, containing ceramic fibers, clay and a binder, characterized in that a) 100 parts by weight of ceramic fibers are mixed with 10 to 40 parts by weight (b) at the mixture obtained in stage a), 5 to 20 parts by weight of clay and / or of very finely divided Al 2 O 3 and / or of very finely divided SiO 2 and / or of hydroxides of aluminum and / or magnesia very finely divided and / or of titanium dioxide very finely divided and / or of very finely divided chromium oxide, and 0 to 10 parts by weight of solid organic binder are added then (c) 0.5 to 4 parts by weight of an organic binder, calculated as solids, in solution, and 1 to 8 parts by weight of a binder are added to the mixture obtained in stage b)) phosphated, calculated as P205, are added and mixed, and   (d) the mixture obtained in stage (c) is dried and granulated.   2. Process according to claim 1, characterized by   the fact that bentonite is used as clay.   3. Process according to claim 1, characterized in that the disintegrated fibers are used as ceramic fibers. 4. Process according to Claim 1, characterized in that the methylcellulose is used as organic binder. 5. Process according to Claim 1, characterized in that the sulphite waste liquor or molasses is used as organic binder.   6. Process according to claim 1, characterized in that the aluminum monophosphate or sodium polyphosphate in the dissolved state and / or in solid form is used as phosphate binder.   7 Fire-resistant or refractory granular, possibly granular, containing ceramic fibers, prepared in accordance with   method described in any one of claims 1 to 6.   8. Use of the fire-resistant or refractory mass   granular, containing ceramic fibers in masses fibrous to be projected.   9. Use of fire-resistant or refractory mass, granular, containing ceramic fibers as an additive in fire-resistant building elements or   refractory, stressed by stress during their use. tion. -   10. Use of the wetted mass containing e-ceramics as a filling material for expansion joints, possibly in the form of a packaged plastic layer   in sheets of synthetic material.