JPH07115954B2 - Fireproof composition for spraying - Google Patents

Description

TECHNICAL FIELD The present invention relates to a spray refractory, and more particularly to a spray refractory composition with greatly improved adhesiveness in hot spraying.

[Conventional technology]

Conventional spray refractories are castable refractories with an alumina cement bond, or those to which hardening accelerators such as Li salt and sodium aluminate are added, and water glass with hardening agents such as sodium silicate fluoride and condensed aluminum phosphate. In general, those which are used in combination, or those which are used in combination with aluminum phosphate and various alkali phosphate salts and which use MgO or Ca (OH) ₂ as a curing agent have been generally used. The usual castable refractory materials are mainly used for structures in cold working, but they are hardly used in hot spraying because of their poor adhesion. Water-glass materials have problems in heat resistance and are often used as acid-resistant materials. Of these, phosphate-based materials excel in hot adhesion and are mainly used as repair materials. However, heat resistance, corrosion resistance, strength,
In terms of adhesion, etc., it is not completely satisfactory. Further, there is a tendency that the number of steel types that do not like to mix the phosphorus component increases, and there is a limit to the use of the phosphoric acid binder.

In recent years, in the refractory industry, a technique for effectively utilizing ultrafine powder and a dispersant to make refractory low in water content, high in density and high in strength has been generalized. The application of this technology to castable refractories is a castable refractory that is commonly called cementless type or cement-free type among those skilled in the art and has a low porosity,
A high-density, high-strength molded product can be obtained. This cementless castable refractory has a high fluidity because it disintegrates ultrafine powder using a dispersant, and when spraying this, deposits flow down from the spraying surface and an adhesive layer can be formed. That is, it is difficult to use as a spray material.
As a countermeasure, a technique of moving a system from a dispersion region to a coagulation region and using it as a spraying material by using a large amount of a dispersant (JP-A-60-11275), or by using a curing accelerator together,
There is disclosed a technique (Japanese Patent Laid-Open No. 60-235770) that cures immediately after adhesion to prevent apparent flow-down. Further, the spray material should be divided into an aggregate particle portion containing a curing agent and a fine powder portion containing ultrafine powder and a dispersant, and the fine powder portion should be kneaded in advance and mixed as a slurry with the aggregate particle portion by a spray nozzle. In this way, the effect of the joint portion is fully exerted, and a high-density and high-strength spraying construction body is obtained (JP-A-60-86079 and JP-A-61-101470).
Issue) is also proposed. However, since this cementless type spray material has high strength and high density, it has a low porosity, it is difficult for the kneading water (added water) to escape from the construction body, and steam explosion occurs when the construction body is rapidly heated. Waiting for an easy flaw. This is because in the case of cold spraying, steam blasting occurs when performing rapid heating and drying after construction, and in the case of hot spraying,
This means that, in principle, it is impossible to carry out spraying at an ambient temperature above the explosion temperature of the sprayed material. Furthermore,
When spraying is applied to a hot wall surface, the kneading water immediately evaporates due to the heat of the wall surface, and this pressure causes the spray material adhered to separate. If spraying is continued, the wall surface is cooled by the kneading water and vaporization is suppressed, so that the adhesion gradually starts. However, when the heat capacity of the furnace is large, the temperature of the furnace itself hardly decreases, so that the sprayed work body is rapidly heated and raised in temperature, and a large amount of flaking occurs due to evaporation of internal moisture. That is, this cementless type spraying material essentially has a problem that it is not suitable for hot spraying at high temperature from the viewpoint of adhesiveness. It is well known to those skilled in the art that the explosion temperature of cementless type castable refractories is extremely low, and as a countermeasure, a technique of adding Al powder to facilitate dehydration by H ₂ gas generation and heat generation, or Techniques for adding fibrous materials, particularly organic short fibers, are known. If these techniques are applied to spraying materials, H ₂ gas will be generated when Al powder is added, so there is a risk of explosion, and the difference in specific gravity between organic short fibers and fire-resistant aggregate is extremely large, and separation occurs during spraying. Is likely to occur, and the spray-constructed body tends to be uneven. The technique of adding Al powder is used in the above-mentioned JP-A-60-235770, and a recent example in which organic short fibers are used as a spraying material is JP-A-60-71577. It should be noted that the technique of the above-mentioned JP-A-60-86079 also has a description that the defect of explosive explosion upon rapid drying which is possessed by alumina cement has been removed, but the actual example is not shown and the reason is unclear. Therefore, it is difficult to confirm the degree of the effect. Also, in JP-A-60-15056, "Tundish hot spraying method", there is a problem of peeling due to rapid evaporation of water when the surface temperature is 300 ° C or higher, and it is proposed to arrange a wire mesh as a countermeasure against this. Yes, but this is just a convenience. As described above, the problem of adhesion in hot spraying has not yet been sufficiently solved in the industry.

[Problems to be solved by the invention]

The spray refractory has an essential problem that the kneading water is vaporized by the heat of the spraying place or the furnace heat of the atmosphere, especially in the hot spraying work, and the vapor pressure thereof prevents the spray refractory from adhering. is doing. This becomes a serious problem as the temperature of the construction site becomes higher. As described above, at present, the problem caused by the water vapor has not been sufficiently solved. The present invention relates to the improvement of the problems caused by the water vapor, and is intended to improve the adhesion in the hot working of the refractory material for spraying.

[Means for solving problems]

The present invention solves the above-mentioned problems by using a basic aluminum lactate to prepare a refractory composition for spraying. This also means that the above-mentioned problems can be improved by adding basic aluminum lactate to a conventionally known refractory for spraying.

[Structure of Invention]

The present invention is also effective for ordinary castable refractory-based, water glass-based, or phosphate-based spraying materials, but for high-density, high-strength cementless-type and cement-free-type spraying materials. Since they are especially effective, they will be mainly described below.

The spray refractory composition of the present invention is a particle size-adjusted refractory aggregate,
The basic composition of ultrafine powder, dispersant and binder is used in combination with basic aluminum lactate.
Since it is a spray material, it is general to use a curing agent (curing accelerator) in combination. As the refractory aggregate, known materials such as acidic, neutral, basic, natural and artificial are used alone or in combination of two or more kinds. In the case of sprayed materials, the grain size composition is generally finer than in the case of pouring construction. Ultrafine powder refers to particles of 10 μm or less, preferably 1 μm or less, which can be made by crushing refractory aggregates, but of materials such as clay, silica, alumina, zirconia, titania, chromia, and SiC. Things are on the market. These may be used alone or in combination depending on the purpose. Well-known dispersants are silicates, phosphates, carboxylates, sulfonates, acrylates, etc., but alkali salts are common, and they are also used alone or in combination. Basic aluminum lactate (hereinafter abbreviated as aluminum lactate) was developed by Taki Chemical Co., Ltd. and characterizes the present invention. Al ₂ O ₃ / lactic acid (molar ratio) obtained by reacting a water-soluble aluminum salt and carbonic acid, or an alumina hydrate obtained by reacting a carbonate with lactic acid
0.3 to 2.0 is of (JP 57-8034 JP), the general formula _{Al (OH) 3-x (} Lac.Acid) polymer electrolyte composed of a polynuclear complex represented by _x · nH ₂ O, the current It is marketed by the developer under the brand name Taxeram. The amount of aluminum lactate used is 0.2-10 wt%, preferably 0.3-
6wt% is good. This is because if the amount is 0.2 wt% or less, it is difficult to recognize the effect, and if the amount is 10 wt% or more, the strength is significantly reduced. Aluminum lactate also functions as a dispersant. As the binder, cement such as Portland cement, alumina cement, barium cement and ρ-alumina, phosphoric acid, aluminum phosphate, alkali phosphate, sodium silicate, colloidal silica, and as a curing agent and a curing accelerator, , MgO, Ca
(OH) ₂ etc. Alkaline earth metal oxides and hydroxides, alumina hydrates, aluminum sulfate, sodium aluminate, Li
Salts or the like can be used, and depending on the aggregate used, the binder, or the purpose, they may be used alone or in combination as appropriate. still,
It is possible to add Al powder, which is known as a technique for preventing the explosion of cementless castable refractories, and organic short fibers together, and steel fibers and other metal powders can also be added as needed. Among these, organic fibers, especially natural fibers, or synthetic fibers having a low softening and decomposition temperature (for example, JP-A-59-169985, JP-A-61-44772, and JP-A-61-7).
7673, 62-21767, etc.) or a material that has good wettability and dispersibility with water (for example, easily soluble vinylon fiber). The spraying is performed by using a known wet method or dry method. When premixing is performed by a wet method or a dry method, it is advisable to add a curing agent and a curing accelerator with a nozzle. Of course, the methods disclosed in JP-A-60-86079 and 61-101470 can also be used.

[Action]

Dense and high-strength cementless type and cement-free type castable refractories that use ultrafine powder and dispersant have low porosity when processed and dried after construction, so it is not easy to release water and is violent due to rapid heating. Although vapor explosion is caused as described above, the applicant of the present invention has previously filed a patent application, finding that aluminum lactate exhibits a remarkable improvement effect against this explosion (Japanese Patent Application No. 60-239047). issue). The reason for the effect is
It was considered that the molded product (constructed product) containing aluminum lactate had fine cracks that were hard to see with the naked eye, and the steam generated by heating was released through the cracks.
As can be seen from the following experimental examples, the effect of aluminum lactate is great even for cementless type castables for spraying, and it is found that not only the explosion temperature is improved but also the hot adhesion rate is remarkably increased. Came to.

Experiment I Al ₂ O ₃ 95% electrofused bauxite 77 wt%, calcined alumina 10
wt%, silica flour 4wt%, high alumina cement 8
%, And a spray-resistant refractory composition consisting of 1% by weight of a sodium phosphate dispersant (this is in accordance with JP-A-60-11275). Aluminum lactate "Taxeram M-160P" was added to this composition, and an explosion temperature and hot blow test were conducted. The results are shown in Table I.

Experimental Example II As aggregate, sintered alumina, fused alumina, magnesia clinker, spinel clinker, zircon, silica stone, chamotte, cordierite, alumina powder as ultrafine powder, silica flour, zircon flour, sodium polyphosphate as a dispersant, Carboxylic acid-based dispersant, aluminum lactate, ρ-alumina, high alumina cement, aluminum phosphate as a binder, electrofused magnesia powder, aluminum sulfate powder, sodium aluminate powder as a curing accelerator, and easily water-soluble vinylon short fibers. Table II shows the results of testing four types of spraying compositions prepared by using the above, and testing the hot adhesion rate with and without aluminum lactate (M-160P).

[Effects] From Experimental Examples I and II, the effect of aluminum lactate M-160P is clear, and a remarkable improvement in spray adhesion during hot is recognized regardless of the types of aggregate, binder, and curing accelerator. . In Experimental Example I, the dispersion effect of aluminum lactate was exhibited, and it was slightly dull. If a curing accelerator is used in combination, the adhesion will be further improved. Although no specific use example is shown here, blast furnace, gutter,
Appropriate and effective for repairing hot-spraying in converters, mixed pigs, electric furnaces, degassing equipment, pots, tundish, lance pipes, pig iron, steelmaking equipment, coke ovens, Al furnaces, incinerators, etc. It will be apparent to those skilled in the art that various materials can be used in combination.

Claims (1)

[Claims] 1. A refractory composition for spraying, characterized in that 0.2 to 10% by weight of basic aluminum lactate is used together with a composition consisting essentially of refractory aggregate, ultrafine powder, dispersant and binder. object.