JPH11268962A - Castable refractory with thermal insulation property - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a castable refractory with excellent fluidity and no specific gravity segregation. SOLUTION: This castable refractory containing an alumina cement as binder is obtained by incorporating 100 pts.wt. of refractory aggregate with 0.05-7 pts.wt. of wet surface-treated gas-included spherical hollow particles consisting of acrylonitrile polymer and/or an acrylonitrile-rich copolymer and having an average size of 5-200 μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a heat-insulating castable refractory excellent in workability.

[0002]

2. Description of the Related Art In a conventional heat-insulating castable refractory, a part of refractory aggregate is replaced with a lightweight aggregate such as pearlite, vermiculite, alumina balloon or the like as a means of imparting heat insulation (Japanese Patent Application Laid-Open No. 56-50171). Ref.), Or burnout materials such as foamed resin, synthetic resin particles, and wood chips are added.

[0003]

However, in castable refractories, the addition of lightweight aggregates and burnt-out materials reduces the fluidity during construction. Further, since the specific gravity of the lightweight aggregate and the burnt-out material is small, it is difficult to obtain a uniform refractory construction body by the specific gravity separation from the refractory aggregate.

[0004] Light aggregates are more likely to be damaged by mechanical stress of the mixer during kneading performed before castable refractory construction. On the other hand, the burnt material is inferior in the effect of providing heat insulation due to insufficient void formation due to residual carbon.
An object of the present invention is to provide a heat-insulating castable refractory which has excellent heat insulating properties and does not have the above-mentioned conventional problems.

[0005]

The heat-insulating castable refractory of the present invention is characterized in that the weight of acrylonitrile having an average particle size of 5 to 200 μm, which is wet-treated, is applied to an amorphous refractory containing alumina cement as a binder. The object is to add gas-containing spherical hollow particles made of a copolymer having a high content of coalesced and / or acrylonitrile.

The gas-containing hollow particles used in the present invention have a low specific gravity separation from the refractory aggregate, and can provide a uniform refractory construction. This is because the gas-containing spherical hollow particles have an extremely fine particle size and are flexible, so that when the castable refractory is constructed, the matrix portion of the refractory structure is sheared by the presence of the hollow particles. This is probably due to the so-called pseudoplastic flow in which the viscosity decreases as the speed increases.

[0007] The gas-containing spherical hollow particles have a smooth surface.
In the present invention, in the wetting treatment of the gas-containing spherical hollow particles, the moisture present on the particle surface reacts with alumina cement as a binder, and the gas-containing spherical hollow particles are adhered and filled to the unevenness of the surface of the refractory aggregate, and the refractory To smooth the aggregate surface,
It is more effective for improving the fluidity during construction of castable refractories.

Further, the gas-containing spherical hollow particles used in the present invention have very little residual carbon due to the hollow particles, and voids required for heat insulation are reliably formed. further,
Due to its flexibility, the gas-containing spherical hollow particles do not break as in the case of lightweight refractory aggregates during kneading of castable refractories.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The gas-containing spherical hollow particles used in the present invention comprise a polymer of acrylonitrile and / or a copolymer having a high acrylonitrile content. Specific examples are copolymers obtained by copolymerizing acrylonitrile with (meth) acrylate monomers, styrene monomers, vinyl halide, vinylidene halide, vinyl acetate, butadiene, vinylpyridine, chloroprene, and the like. The polymer and / or copolymer may be used in combination with other comonomers or crosslinking agents (divinylbenzene, ethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate , 1,3-butylene glycol di (meth) acrylate, allyl (meth) acrylate, triacrylformal, triallyl isocyanurate, etc.).

[0010] The gas-containing spherical hollow particles are produced, for example, by heating with a foaming agent contained therein to expand the foaming agent. At that time, as the blowing agent, for example, hydrocarbons such as n-pentane, isopentane, neopentane, butane, isobutane, hexane, petroleum ether, chlorinated hydrocarbons such as methyl chloride, methylene chloride, dichloroethylene, trichloroethane, and trichloroethylene;
Trichlorofluoromethane, dichlorofluoromethane,
Specific freons such as dichlorofluoroethane and dichloropentafluoropropane and alternative freons are exemplified, but not limited thereto.

[0011] The gas-containing spherical hollow particles easily disappear due to the high temperature received during drying or use of the castable refractory, and provide heat insulation to the castable refractory by forming fine voids in the refractory structure. .

The average particle diameter of the gas-containing spherical hollow particles is 5 to 2
The thickness is set to 00 μm, more preferably 5 to 100 μm. The maximum particle size is preferably 300 μm or less. If the average particle size is less than 5 μm, the effect of imparting heat insulating properties to the castable refractory is inferior, and if it exceeds 200 μm, the effect of preventing specific gravity separation cannot be obtained. In addition, the particle diameter of these gas-containing spherical hollow particles can be measured by, for example, a microscopic method in which an image obtained by a stereoscopic microscope is analyzed by an image processing device.

The gas-containing spherical hollow particles used in the present invention comprise a polymer of acrylonitrile or a copolymer having a high acrylonitrile content, and are also available as commercial products. For example, "Trademark:
EXPANCEL (product code 551DE, 551WE,
461DE, 091DE etc.) ", Matsumoto Yushi Pharmaceutical Co., Ltd.
"Trademark: Matsumoto Microsphere (product code F-
30E, F-50E).

The wetting treatment for the gas-containing spherical hollow particles is as follows:
For example, with water. The degree of wetting of the gas-containing spherical hollow particles is preferably, for example, 400 to 600 parts by weight of water per 100 parts by weight of the gas-containing spherical hollow particles.

The addition ratio of the gas-containing spherical hollow particles to the castable refractory is preferably 0.05 to 7 parts by weight based on 100 parts by weight of the refractory aggregate. If the addition amount is small, the fluidity and the effect of preventing specific gravity separation at the time of construction of castable refractories tend to decrease. Also, the heat insulating effect becomes insufficient.
If the amount of addition is large, the castable refractory is inferior in the strength of the construction body.

The refractory aggregate is not particularly different from that used for conventional castable refractories. For example, magnesia, spinel, alumina, silica, silica-alumina,
The main material is at least one selected from zircon, calcia, and the like. If necessary, one or more selected from chromia, carbon, silicon carbide, silicon nitride, boron carbide, and the like are combined. Further, in order to further improve the heat insulating property, a part of the refractory aggregate may be made of lightweight alumina, lightweight chamotte, lightweight magnesia, perlite, vermiculite, alumina microballoon, alumina-silica microballoon, or the like.

The addition ratio of the alumina cement as a binder is 1 to 30 parts by weight based on 100% by weight of the refractory aggregate. If the amount is less than 1 part by weight, the strength of the construction body is inferior and 3
If it exceeds 0 parts by weight, the corrosion resistance and spalling resistance decrease.

[0018] In addition, dispersants known as additives of castable refractories, clay, bentonite, CMC, volatile silica, fly ash, organic fibers, ceramic fibers, metal fibers, surfactants, collectors, water reducing agents Agent, metal powder (for example, Al, Si or alloy thereof), foaming agent,
Antioxidants, digestion inhibitors, curing retarders, curing accelerators, coarse refractory particles and the like may be added. In addition, as long as the effect of the present invention is not impaired, a void-forming material other than the gas-containing spherical hollow particles used in the present invention, such as sawdust, resin pieces, or foamed resin, may be added.

For example, the dispersant may impart fluidity during construction of the castable refractory, and specific examples thereof include inorganic silicates, carbonates, phosphates, organic polycarboxylates, and anhydrous carboxylate. It is at least one selected from acid polymer, aromatic polycyclic condensate sulfonate, melanin resin sulfonate, lignin sulfonate, polyacrylate and the like. The preferable addition amount is 100 g of the refractory aggregate.
It is 0.01 to 1 part by weight based on parts by weight.

The method for applying a heat-insulating castable refractory according to the present invention may be applied directly to a portion to be applied, or may be applied using a pre-cast product formed in advance.

[0021]

Examples Examples of the present invention and comparative examples are shown below. Table 1 shows the quality of the fine void forming material used in each example. Table 2 shows the composition and test results of the castable refractories of each example. The wet-treated product among the spherical fine particles shown in Table 2 is:
The surface of the particles was wetted with water, and the ratio of water to the weight of the particles was 85% by weight.

The details of the test method are as follows. Fluidity: After kneading each compound with a mixer, the inner diameter of the lower end is 10
The measurement was performed using a 0 mm cone-shaped mold. The state where no flow occurs at all is 100 mm, and the larger the size, the better the flowability.

Specific Gravity Degree of Separation: The composition obtained by kneading the composition with a mixer and pouring was dried by heating at 500 ° C. for 8 hours, and the apparent porosity of each of the upper and lower parts was measured. The degree of specific gravity separation was determined from the difference in hanging porosity. That is, the greater the difference in apparent porosity, the greater the degree of specific gravity separation.

Tissue strength: After kneading the composition with a mixer,
The cast body obtained by casting was heat-dried at 110 ° C. for 24 hours, and the flexural strength was measured at room temperature. Insulation properties; JI
S: Thermal conductivity was measured according to R2618-79 (test method for thermal conductivity of refractory insulated brick by hot wire method).

[0025]

[Table 1]

[0026]

[Table 2]

The castable refractories of Examples 1 to 5 in Table 1 are all excellent in structural strength, heat insulation and workability. On the other hand, Comparative Example 1 is inferior in heat insulation and workability because the spherical hollow particles containing gas used in the present invention are not added. In Comparative Example 2, although the gas-containing spherical hollow particles were added, since the gas-containing spherical hollow particles were not subjected to the wet treatment, the fluidity was inferior to that of the examples of the present invention.

Comparative Example 3 uses alumina-silica spherical hollow particles as fine spherical particles, and is inferior in fluidity.
In Comparative Example 4, the particle diameter of the gas-containing spherical hollow particles was larger than the limited range of the present invention, and the specific gravity separation prevention and the fluidity were poor. Comparative Example 5 uses sodium silicate as a binder, and is inferior in fluidity.

The heat-insulating castable refractory of the present invention is constructed by pouring, press-fitting, spraying and the like. Its applications are, for example, converters, blast furnace gutters, blast furnace gutter covers, mixed iron cars, mixed iron furnaces, electric furnaces, electric furnace furnace lids, vacuum degassing furnaces, ladle, pan lids, tundish, tundish covers, soaking furnaces It is used as a lining material for non-ferrous metal furnaces, chemical industrial furnaces, incinerators, boilers, glass furnaces, cement industrial furnaces, ceramic kilns, etc. or as a backing material for lining materials. Also,
It can also be used as a coating material on the surface of lining materials.

[0030]

As described above, according to the present invention, a heat-insulating castable refractory having both heat-insulating properties and workability can be obtained.

Claims (2)

[Claims] 1. A castable refractory containing alumina cement as a binder, wherein a gas-filled spherical hollow made of a polymer of acrylonitrile and / or a copolymer having a high acrylonitrile content having an average particle size of 5 to 200 μm whose surface is wet-treated. Insulation castable refractory with added grains. 2. The refractory aggregate according to claim 1, wherein the amount of the gas-containing spherical hollow particles is 1.
The amount is 0.05 to 7 parts by weight based on 00 parts by weight.
A heat-insulating castable refractory as described.