JPH11171657A - Castable refractory - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a castable refractory capable of preventing variations in an amount of water mixed, fluidity, hardening time, a pot life, etc., caused by the variability of pH of refractory superfine powder, having excellent refractoriness and mechanical strength, by including refractory superfine powder and a hydrophilic organic compound. SOLUTION: This castable refractory is a composition comprising a refractory aggregate, a binder, refractory superfine powder and a hydrophilic organic compound. (A) The refractor aggregate is, for example, sintered alumina and sintered alumina having 5 to <=10 mm particle diameter is used. (B) The binder is, for example, an alumina cement and an alumina cement having 100-0.1 mm particle diameter is used. (C) For example, a silica fume having 0.01-1 μm particle diameter is used as the refractory superfine powder. (D) A compound containing a hydroxyl or a carboxyl, a carboxylic acid metal salt or the like is used as the hydrophilic organic compound. The blending ratio is 70-95 wt.% of the component A, 1-10 wt.% of the component B, 1-25 wt.% of the component C and <=1 wt.% of the component D based on the total of the castable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a castable refractory used for lining various kilns such as a rotary kiln, an air quenching cooler, a preheating furnace and an incinerator.

[0002]

2. Description of the Related Art Castable refractories (hereinafter, abbreviated as castables) are characterized by a large degree of freedom in construction. That is, since all types of work such as pouring, casting, pressure feeding, spraying, hand coating, compacting, etc. can be performed relatively easily, it has been widely spread in recent years and has greatly increased production. In addition, recently, there is a shortage of bricklayer workers who require special skills at construction sites, and the ease of construction conforms to modern circumstances. Further, the number of storage locations can be reduced, and there are advantages in terms of cost, such as quick delivery of production.

[0003] Conventional castables are generally obtained by adding 10 to 20% by weight of alumina cement as a binder. In such a castable, the amount of kneading water increases due to the large amount of alumina cement added, and
The embrittlement due to dehydration of the cement hydrate occurs in a medium temperature range of 0 to 1200 ° C., and a low-melting substance is generated in a high temperature range of 1200 ° C. or more to deteriorate the hot properties.

Therefore, in recent years, it has been practiced to reduce the amount of alumina cement to be added and to use refractory ultrafine powder having a central particle diameter of 1 μm or less, particularly silica fume, as a part of the binder. Such castables have the advantage that the amount of kneading water can be reduced and a high-strength refractory can be obtained. However, since silica fume is mixed with carbon and alkalis are present as impurities, its pH fluctuates, the amount of kneading water fluctuates, the quality is not stable, and the castable performance, especially after kneading, is hardened. Time and pot life are not stable, causing fluctuations in fluidity and causing problems in construction, as well as causing a decrease in fire resistance and mechanical strength.

As a method for improving such a problem,
A method using silica fume whose pH has been adjusted (see JP-A-61-158872) and a method of adding an ultrafine powder other than silica fume adjusted to be acidic (see Japanese Patent Publication No. 5-80431). Proposed. However, in these prior arts, since the pH adjustment is performed by a method in which the refractory ultrafine powder such as silica fume and the acid solution are measured, mixed, and then dried, the process is complicated, and it takes time and effort. There is a disadvantage that the cost is greatly increased.

[0006]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to simply and inexpensively eliminate the various disadvantages described above due to variations in pH of refractory ultrafine powder such as silica fume.

[0007]

This problem can be solved by blending a hydrophilic organic compound, particularly an organic compound having a hydroxyl group, a carboxyl group, or the like in a molecule.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
The castable of the present invention is a composition comprising a refractory aggregate, a binder, a refractory ultrafine powder, and a hydrophilic organic compound. As the refractory aggregate, one or more of sintered alumina, magnesia, bauxite, shammot, chromium oxide, silica, zircon, mullite and the like having a particle size of 5 to 10 mm or less are used. The amount of the refractory aggregate is about 70 to 95% by weight of the total castable.

Alumina cement, magnesia, or the like is used as the binder, and the particle size is 100%.
０．１0.1 μm. The blending amount of the binder is 1 to 10% by weight of the total castable. Furthermore, the refractory ultrafine powder functioning as a part of the binder has a particle size of 0.01 μm.
One or more kinds of silica fume, alumina, mullite, chromium, titania and the like having a size of m to 1 μm are used,
The compounding amount is 1 to 25% by weight of the total castable.

[0010] The hydrophilic organic compounds include methanol,
Ethanol, butanol, resorcinol, hydroquinone,
Phenol, cresol, ethylene glycol, diethylene glycol, propylene glycol, glycerin,
Organic compounds having a hydroxyl group (OH group) in the molecule, such as monoethanolamine, diethanolamine, and triethanolamine; organic compounds having a carboxyl group (COOH group) in the molecule, such as acetic acid, stearic acid, benzoic acid, and formic acid; stearin One or a mixture of two or more kinds of organic compounds having a ketone group in a molecule such as sodium carboxylate (COOM group) such as sodium acid and sodium acetate, and acetone are used. The amount of the hydrophilic organic compound added is 1% by weight or less, preferably about 0.1 to 0.3% by weight, based on the total amount of the castable.

[0011] The hydrophilic organic compound may be added during the production of castables, for example, when pulverizing refractory ultrafine powder, or may be added during kneading of castables. When the hydrophilic organic compound is liquid at room temperature, it is desirable to add the compound at the time of kneading. In any case, it is preferable to minimize dilution with water, and to add as undiluted solution or undiluted solution without diluting as much as possible.

In the castable of the present invention, a deflocculant, a hardening accelerator, a hardening retarder and the like can be appropriately selected and blended as required. The deflocculant improves the fluidity of the castable, and for example, sodium tripolyphosphate, sodium hexametaphosphate, aluminum phosphate, sodium borate and the like are used. In addition, calcium oxide (raw coal), carbide, and the like are used as the oxidation promoter, and citric acid, oxalic acid, boric acid, and the like are used as the curing retarder.

The castable of the present invention is kneaded with water and used for kneading.
The amount is about 2 to 8 parts by weight with respect to 00 parts by weight, but fluidity is improved by blending the hydrophilic organic compound, and the amount of kneading water can be reduced.

In such a castable, the hydrophilic organic compound has an effect of masking impurities mixed in with the refractory ultrafine powder such as silica fume and buffering a variation in pH caused by silica fume and the like. ,
Such an action prevents a change in the amount of kneading water and can reduce the amount of kneading water, whereby a dense and strong refractory can be obtained. In addition, there is no separation or segregation between the aggregate and the refractory ultrafine powder and the binder during kneading, so that the fluidity is improved and the workability is improved. Furthermore, since it is only necessary to simply add the stock solution and the stock solution of the hydrophilic organic compound, there is no need for a special facility or an extra manufacturing process, and the cost is slightly increased.

Hereinafter, specific examples will be described. The castables having the composition shown in Table 1 are kneaded, and the fluidity, pot life,
The cure time was measured. Further, the compressive strength, flexural strength and bulk specific gravity of the refractory after curing were measured. The results are shown in Table 1. Fluidity, the diameter of the bottom surface is 100mm, the diameter of the top surface is 50mm, the height is 150mm, put the kneaded material into a frusto-conical slump cone, withdraw the slump cone upwards, after standing for 60 seconds Diameter of the kneaded material (m
m) was measured.

The pot life was evaluated as the time (minutes) until it was determined that the kneaded material had lost fluidity due to the tactile sensation. For the curing time, pack the kneaded material in a suitable container, level the surface, lower the needle as much as possible according to the Vicat needle test specified in JIS R5201, lower the needle, and check the trace of the tip of the needle. The point at which it disappeared was regarded as curing, and the evaluation was made based on the time (hour) so far. Compressive strength, flexural strength, and bulk specific gravity were measured according to JIS R2553.

[0017]

[Table 1]

In the composition of Example A in Table 1, a mixture of ethylene glycol and acetone (3: 1 (weight ratio)) was used as a hydrophilic organic compound at a ratio of 0.1% by weight, and the amount of kneading water was adjusted. The kneaded material was examined by the same method as above while changing the kneaded material. The results are shown in FIG. FIG. 1 also shows the fluidity when no hydrophilic organic compound is added.

[0019]

As described above, in the present invention, it is possible to prevent fluctuations in the amount of kneading water, fluidity, curing time, pot life, and the like due to variations in the pH of ultrafine powder such as silica fume. A refractory having excellent fire resistance and mechanical strength can be obtained without increasing the cost.

[Brief description of the drawings]

FIG. 1 is a chart showing the results of Examples, in which the horizontal axis represents the amount of kneading water and the vertical axis represents the fluidity.

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[Procedure amendment]

[Submission date] January 23, 1998

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0012

[Correction method] Change

[Correction contents]

In the castable of the present invention, a deflocculant, a curing accelerator, a curing retarder and the like can be appropriately selected and blended, if necessary. The deflocculant improves the fluidity of the castable, and for example, sodium tripolyphosphate, sodium hexametaphosphate, aluminum phosphate, sodium borate and the like are used. Further, the hardening accelerator, calcium oxide (Oishi ash), such as carbide is, the retarder, citric acid, tartaric acid, and boric acid.

Claims (3)

[Claims] 1. A castable refractory comprising a refractory ultrafine powder and a hydrophilic organic compound. 2. A refractory aggregate, a binder, a refractory ultrafine powder,
Castable refractories made of hydrophilic organic compounds. 3. The method according to claim 1, wherein the hydrophilic organic compound has a hydroxyl group in the molecule.
3. The castable refractory according to claim 1, which contains any of a carboxyl group, a metal carboxylate group, and a ketone group.