JPH06293569A - Kneaded refractory - Google Patents

Abstract

PURPOSE:To provide a monolithic refractory for cast molding previously kneaded with water added used for the wall lining of various molten metal vessels such as a tapping spout, a tundish for a blast furnace. CONSTITUTION:This monolithic refractory is produced by adding and kneading 0.1-3.0pts.wt. aluminum tripolyphosphate hardly soluble in water and 4-10pts.wt. water based on 100pts.wt. monolithic refractory prepared by mixing an alumina cement with an insulating material as a binder. As a result, the refractory causes hydraulic reaction at a relatively low temp. heating after working and is uniformly hardened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a castable amorphous refractory used for lining various molten metal containers such as blast furnace tap gutters and tundish. It relates to kneading refractories.

[0002]

2. Description of the Related Art A castable amorphous refractory material is used to cast a hydro-kneaded refractory material into a mold such as a core to mold a construction body. The fluidity of the kneaded product does not change until it is applied, and it is desirable that it has a hardening strength such that the form can be quickly removed after the completion of the application. After removing the formwork from the construction body (hereinafter referred to as “demolding”), the binder contained in the kneaded product is heated by heating and drying to remove the water contained in the construction body. Harden and sinter.

As an amorphous refractory of this type, a hydraulic castable refractory containing alumina cement as a binder is predominant. And, in the past, generally, the refractory packed in a bag with powder was poured into the mold immediately after being hydro-kneaded at the construction site, and was cured by the hydration reaction of the alumina cement to form the construction body, In addition to deteriorating the working environment due to dust scattering during the mixing and kneading of refractory materials, the labor required for the work made it difficult to meet the recent demand for labor saving.

Against this background, it has been proposed to pack and ship the hydro-kneaded product in the refractory manufacturing stage. Alumina cement is more suitable than Portland cement, which is a binder for general concrete. However, the hydration reaction proceeds very quickly, and in the summer when the temperature is high, the fluidity is lost even 2 hours after the kneading with water, and it becomes unsuitable for casting.

Therefore, the present applicant has previously said that if alumina tricetiate phosphate, which is sparingly soluble in water, is used as the binder without using alumina cement, the fluidity after hydro-kneading is maintained for a long time. Based on the findings, a refractory material was proposed in which a mixture of refractory material with aluminum tripolyphosphate, which is poorly soluble in water as a binder, was kneaded with water (JP-A-55-85475). This kneaded refractory does not undergo a curing reaction for about one month when stored at room temperature, and retains the fluidity necessary for construction, which is satisfactory in terms of product life.

[0006]

However, since the development of strength after construction depends on the condensation reaction of aluminum tripolyphosphate by heating, in order to obtain sufficient curing strength for demolding, a high temperature of 300 ° C. or higher is required. It is necessary to heat the work piece in a complicated manner, and not only the work becomes complicated, but also the binder (aluminum tripolyphosphate) moves to the surface of the construction body that is susceptible to heat during heating, and it is condensed and causes phenomena such as foaming and cracks. There is a tendency that there is a tendency that the construction body tends to have a non-uniform and weak structure as a result.

In addition, in the high temperature heating of 300 ° C. or higher,
Even if the formwork is made of metal, it has been deformed, and it has become a problem that it cannot withstand repeated use.

The applicant of the present invention has proposed in JP-A-59-8673 a refractory material obtained by using alumina cement as a binder and adding a sparingly soluble aluminum tripolyphosphate to water as a hardening retarder. , This is basically a plan for hydro-kneading at the construction site, so no special consideration has been given to the amount of water to be added.

The present invention has been made in view of the above-mentioned circumstances, and an object thereof is a kneading refractory product which is kneaded and hydrolyzed in a manufacturing stage, and has a fluidity necessary for construction in a long time of 12 hours or more. It can be held for a long time, and after construction it can develop sufficient curing strength by heating at a relatively low temperature,
An object of the present invention is to provide a kneading refractory material capable of obtaining a construction body having a uniform structure.

[0010]

In order to achieve the above object, the kneading refractory material according to the present invention comprises 100 parts by weight of an amorphous refractory material obtained by mixing a refractory material with alumina cement as a binder. On the other hand, 0.1 to 3.0 parts by weight of aluminum tripolyphosphate, which is poorly soluble in water, is added, and water 4 to
It is characterized by adding 10 parts by weight and kneading.

As the refractory material, usual materials conventionally used in castables, that is, aggregates such as alumina, silicon carbide, bauxite and graphite, and fine particles of silica and alumina are used. These refractory materials are appropriately selected according to the shape, size, thickness of the construction body and use conditions, that is, temperature, contact gas, molten metal, molten slag, etc., and the particle size is adjusted before use. Further, powdery pitch, kaolin clay, or the like may be added if necessary.

Aluminum tripolyphosphate, which is sparingly soluble in water, has a function of suppressing the hardening of alumina cement as a binder. The hardening is due to a hydration reaction. Specifically, the contact between alumina cement and water causes ion dissociation of the cement component, and the Ca ²⁺ ion concentration becomes supersaturated to form a hydrated compound and harden. . Therefore, in order to stop the hardening, it is necessary to control the Ca ²⁺ ion concentration, and an acid that lowers the pH of the hydrate is effective for this.

In the experiments conducted by the present inventors, it was found that the hydration reaction of alumina cement would not proceed if the pH was adjusted to 6 or less by a combination with an inorganic acid or an organic acid. However, with water-insoluble acids, the inhibitory effect cannot be obtained, and the fluidity of the kneaded refractory is rapidly lost. Conversely, with water-soluble acids such as aluminum phosphate, the dissolution rate is too fast. Probably because the hydration reaction is suppressed excessively, even if it is heated after construction, it will not cure uniformly.

In these studies, only when aluminum tripolyphosphate, which is poorly soluble in water, is adopted, the progress of curing of the kneading refractory material at room temperature is suppressed, and it is necessary for the pouring work even after 48 hours from the kneading. It was found that when the temperature was 80 ° C. to 90 ° C., the curing function was sufficiently restored, while maintaining sufficient fluidity, and when heated, the curing started at 70 ° C. Although the mechanism of curing inhibition by aluminum tripolyphosphate is not always clear, it can be considered as follows.

That is, since aluminum tripolyphosphate, which is poorly soluble in water, unlike other acids, does not dissolve immediately, it does not undergo a rapid reaction with cations and anions derived from the components of the refractory material. , Ca ²⁺ generated in the early stage of the hydration reaction of the most reactive alumina cement
After selectively reacting only with ions, it is believed that this reaction product coats the surface of the alumina cement particles and suppresses the subsequent hydration reaction. It is considered that the hardening by heating is due to the activated hydration reaction that was suppressed. As a result, the hydration reaction of the alumina cement, which is the binder, progresses, so that uniform strength development can be obtained in the entire construction body.

When the amount of aluminum tripolyphosphate added is 0.1 parts by weight or more with respect to 100 parts by weight of the amorphous refractory, the effect of suppressing the curing is recognized, but even if it exceeds 3 parts by weight, the effect of suppressing the curing is not improved. Not only does it hinder the hardening of the construction body after construction. Therefore, the amount of aluminum tripolyphosphate added is within the range of 0.1 to 3 parts by weight.

The kneading refractory material of the present invention is obtained by adding water to a powder mixture prepared by adding a poorly water-soluble aluminum tripolyphosphate to the above-mentioned amorphous refractory material, and kneading the mixture. It is set in the range of parts by weight. In the conventional cast refractory for casting, the amount of water required to obtain the fluidity suitable for the casting operation is generally in the range of 3 to 15 parts by weight, although it depends on the bulk specific gravity of the constituent material of the refractory. However, as in the case of the present invention, in which a sparingly soluble aluminum tripolyphosphate is added to water and kneaded with water in the production stage, segregation of fine powder parts due to vibration during transportation and separation of water due to standing for a long time occur. , Need proper water management. According to the research conducted by the present inventors, the amount of water required in the present invention is in the range of 4 to 10 parts by weight as described above.

In the practice of the present invention, a dispersant such as an organic polymer polysaccharide, methyl cellulose or sodium alginate may be added to separate water and prevent segregation of fine powder.

[0019]

EXAMPLES Examples will be described below. With the formulations shown in Table 1, Examples of the present invention and Comparative Examples were prepared. In Examples 1 to 3 and Comparative Examples 1 to 3, alumina as a refractory material having an average particle size of 1 to 8 mm and silicon carbide having an average particle size of 1 to 5 mm were used as aggregates, and an average particle size of 0.25 mm or less was used. Alumina fine powder and silicon carbide fine powder of 1 mm or less, and ultrafine powder of silicon carbide, powdered pitch, and refractory clay are mixed at the ratios shown in Table 1, respectively, and are composed of alumina cement as a binder and a small amount of peptized powder. The agent was added to obtain an amorphous refractory material. In Examples 4 and 5, the average particle size was 1 as a refractory material.
~ 8mm bauxite and spinel aggregate added,
Comparative Example 4 is a case where alumina cement was not used.

In Examples 1 to 6 and Comparative Example 2, aluminum tripolyphosphate, which is poorly soluble in water, was added in an amount of 100 parts by weight to 100 parts by weight of the amorphous refractory material, while Comparative Example 3 was used. Is the addition of water-soluble aluminum phosphate, and Comparative Example 4 is the addition of sodium silicate which is a thermosetting binder. In addition, Comparative Example 1 is an example of a conventional general castable refractory material.

[0021]

[Table 1] As is clear from Table 1, in each of Examples 1 to 6, the hydration reaction after hydrolysis and kneading was stopped, and after 48 hours at room temperature (20 ° C.), it was uncured and was suitable for casting. At the same time, it is cured by heating at a relatively low temperature of 90 ° C. to develop strength. The amount of water added is from Example 1
3 and 5 are 5.5 parts by weight, and in Example 4, the addition amount is increased from the bulk specific gravity of bauxite to 8.0 parts by weight.
In Example 6, the amount of water added was adjusted to 6.0 parts by weight and methyl cellulose was added as a dispersant. However, the effect of the present invention was obtained by using it together with aluminum tripolyphosphate, which is poorly soluble in water.

On the other hand, in Comparative Example 1, the hydration reaction is progressing at room temperature, and the time from the hydro-kneading to the use for construction is very short, and the hydro-kneading work at the construction site is required. I understand. Further, in Comparative Example 2 as well, since the amount of aluminum tripolyphosphate added was too small, the curing at room temperature was not stopped.

In Comparative Example 3, as a result of adding water-soluble aluminum phosphate, it became clear that the fluidity was drastically decreased, and the function as a casting construction was lacking and proper molding could not be carried out. The survey was discontinued. Further, although Comparative Example 4 has a storage property at room temperature, it does not cure by heating at 90 ° C., and even when it is cured at a high temperature, it exhibits poor strength development and is inferior in performance as a lining material for a molten metal container.

The fluidity and flow value are JIS R 5
The fluidity after kneading was measured by the method specified in paragraphs 9 and 7 of 201.

The curing strength is 90 after pouring each kneading material into a cylindrical mold having a diameter of 50 mm and a height of 50 mm and sealing it.
After curing for 12 hours at a temperature of ° C, the uncured Comparative Example 3 was removed, and the bending strength of each was measured.

Regarding the physical properties of firing, each kneading material is JIS
Pour into a mold defined by R 2653, Example 1
~ 6 at 90 ° C for 24 hours, Comparative Examples 1 and 2 at room temperature (20
C.) for 24 hours, and Comparative Example 4 was cured by curing at 300.degree. C. for 24 hours. The bending strength and the porosity of each of the test pieces were measured by drying the test pieces at a temperature of 110 ° C. for 24 hours and then firing at 1450 ° C. for 3 hours.

The corrosion resistance test was carried out by using a molding die for erosion test of a predetermined shape and curing in the same manner as in the above-mentioned test article for fired physical properties, followed by drying treatment at 110 ° C. for 24 hours. The smaller the value, the smaller the amount of erosion.

[0028]

As described above, the kneading refractory material according to the present invention retains the fluidity necessary for casting for a long time in a hydro-kneaded state. Can be shipped. Therefore, it is useful for suppressing the generation of dust at the construction site and improving the working environment.
In addition, since sufficient hardening strength is developed by heating at a relatively low temperature after construction, the structure of the construction body can be made uniform without the risk of brittleness associated with high temperature heating, and the construction mold It has an excellent effect that the frame can be repeatedly used.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tadahiko Yoshida 5-3 Tokai-cho, Tokai City, Aichi Prefecture Nippon Steel Co., Ltd., Nagoya Steel Works (72) Inventor Noriyuki Inoue 4-3-Misato, Aichi Prefecture 3 (72) Inventor Ryuji Shimizu 5-20-48 Aoki-cho, Toyota-shi, Aichi (72) Inventor Fumiaki Osawa 2-107-3 Aoki-cho, Toyota-shi, Aichi

Claims (1)

[Claims] 1. Aluminum tripolyphosphate, which is sparingly soluble in water, with respect to 100 parts by weight of an amorphous refractory made of a mixture of a refractory material and alumina cement as a binder.
A kneading refractory material, which is obtained by adding 3.0 parts by weight and kneading by adding 4 to 10 parts by weight of water.