JPS63265869A - Refractory composition for spraying - Google Patents

Abstract

PURPOSE:To provide a titled compsn. which is improved in adhesiveness in hot application by using basic aluminum lactate as an essential component. CONSTITUTION:An alumina hydrate obtd. by bringing a water soluble aluminum salt and carbonic acid (carbonate) into reaction is brought into reaction with lactic acid to obtain the basic aluminum lactate having 0.3-2.0 Al2O3/lactic acid molar ratio. Outer 0.2-10wt.% basic aluminum lactate and if necessary, binder, hardener, hardening accelerator, etc., are compounded with refractory aggregate (e.g.: clay) having <=10mum grain size.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to large spray-resistant objects, and particularly to a spray-on fire-resistant composition that has significantly improved adhesion in hot spray construction.

[Conventional technology]

Conventional spray refractories are alumina cement bonded castable refractories, 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 and condensed aluminum phosphate. Generally, those using MgO or Ca (OH) z as a hardening agent have been used in combination with aluminum phosphate or various alkali phosphates. Ordinary castable refractories are mainly used in cold construction for structures, but because of poor adhesion, they are rarely used in hot spray construction. Water glass-based materials have problems with heat resistance and are often used as acid-resistant materials. Among these, phosphate-based materials have superior hot adhesion properties and are mainly used as repair materials.

However, it is not completely satisfactory in terms of heat resistance, corrosion resistance, strength, adhesion, etc. In addition, there is a tendency for more and more steel types to be uncontaminated by phosphorus components, and there are restrictions on the use of phosphoric acid binders.

In recent years, in the refractory industry, techniques for making refractories with low moisture, high density, and high strength by effectively utilizing ultrafine powders and dispersants have become commonplace. This technology is applied to castable refractories, which are commonly referred to as cementless or cement-free refractories by those skilled in the art.
A molded article with high density and high strength can be obtained. This cementless type castable refractory uses a dispersant to peptize the ultrafine powder, so it has high fluidity, and when it is sprayed, the deposits flow down from the sprayed surface, making it impossible to form an adhesive layer. In other words, it is difficult to use it as a spray material.

As a countermeasure to this, a technique is used in which a large amount of dispersant is used to move the system from the dispersion zone to the coagulation zone and used as a spraying material (Japanese Patent Application Laid-open No. 11275/1983), or by using a curing accelerator in combination. A technique (Japanese Unexamined Patent Publication No. 60-235770) has been disclosed in which the adhesive is cured immediately after adhesion to prevent apparent running down. In addition, the spraying material is divided into an aggregate part containing a hardening agent and a fine powder part containing an ultrafine powder and a dispersant, and the fine powder part is kneaded in advance.
A technique for obtaining a high-density, high-strength sprayed construction body by mixing the slurry with aggregate particles in a spray nozzle to fully demonstrate the effect of the joint (Japanese Patent Application Laid-Open No. 60-86079, Publication No. 101470/1984 @) has also been proposed. However, because this cementless spray material has high strength and high density, it has a low porosity, making it difficult to remove the mixing water (added water) from the construction material, and causing steam explosion when the construction material is rapidly heated. Waiting for possible shortcomings. This is because in the case of cold spraying, rapid heating and drying after construction will cause a steam explosion, and in hot spraying, spraying at an ambient temperature higher than the explosion temperature of the spraying material is in principle prohibited. means it's impossible. Furthermore, when spraying is performed on a high-temperature wall surface, the kneading water immediately evaporates due to the heat of the wall surface, and the adhering spray material peels off due to this pressure. As spraying continues, the wall surface is cooled by the mixing water and vaporization is suppressed, so adhesion begins gradually. However, if the heat capacity of the furnace is large, there is almost no drop in the furnace temperature itself, so the sprayed workpiece will be rapidly heated and the temperature will rise.
Large flaking occurs due to evaporation of internal moisture. In other words,
This cementless spray material inherently has the problem that it is not suitable for hot spray construction at high temperatures due to its adhesive properties. It is well known to those skilled in the art that the explosion temperature of cementless castable refractories is extremely low, and countermeasures to this problem include techniques to facilitate dehydration by adding AI lead powder to generate H22 gas and generate heat, or to use fibrous materials. In particular, techniques for adding organic short fibers are known.

When these techniques are applied to sprayed materials, if Al is added, H2 gas is generated, which poses the risk of explosion, and the difference in specific gravity between aluminous short fibers and refractory aggregate is extremely large, and the Separation occurs and the sprayed work tends to become uneven. The technique of adding A1 powder is utilized in the above-mentioned Japanese Patent Application Laid-Open No. 60-235770, and a recent example of using organic short fibers in a spray material is JP-A No. 60-71577. Incidentally, the technique in the above-mentioned Japanese Patent Application Laid-Open No. 60-86079 also states that the drawback of alumina cement, which is explosion during rapid drying, is eliminated, but no actual example is shown and the reason is unclear. Therefore, it is difficult to confirm the extent of the effect. or,
JP-A-60-15056 ``Hot spraying construction method for tanditshu'' has a problem of peeling due to rapid evaporation of water when the surface temperature is 300°C or higher, and proposes placing a wire mesh as a countermeasure. However, this is just a convenience. As described above, the problem of adhesion in hot spraying has not yet been satisfactorily resolved in the industry.

[Problem that the invention seeks to solve]

Sprayed refractories have an essential problem, especially in hot spraying construction, where the kneading water is vaporized at the spraying location or by the furnace heat in the atmosphere, and the vapor pressure prevents the adhesion of the sprayed refractories. are doing. This becomes a more serious problem as the temperature at the construction site becomes higher. As mentioned above, at present, this problem caused by water vapor has not been satisfactorily solved. The present invention relates to improving the problems caused by this water vapor, and aims to improve the adhesion of spray-on refractories during hot construction.

[Means to solve problems]

The present invention solves the above problems by using basic aluminum lactate to create a sprayable fireproof composition. This also means that the above-mentioned problems can be improved by adding basic aluminum lactate to conventionally known spray refractories.

[Structure of the invention]

The present invention is effective for ordinary castable refractory-based, water-glass-based, or phosphate-based spray materials, but it is also effective for cementless and cement-free spray materials that have high density and high strength. Since these methods are particularly effective, we will mainly discuss them below.

The fireproof composition for spraying of the present invention basically consists of a fireproof aggregate whose particle size has been adjusted and basic aluminum lactate, but since it is a sprayable material, it is common to use a binder and a hardening agent (hardening accelerator) in combination. It is. Further, as mentioned above, it is more preferable to use ultrafine powder or a dispersant.

Refractory aggregates include acidic, neutral, basic, natural,
Known artificial materials may be used alone or in combination. In the case of sprayed materials, the particle size structure is generally finer than in the case of pouring construction. Ultrafine powder refers to powder of 10 μm or less, preferably 1 μm or less. Although it can be made by crushing refractory aggregate, it can also be made from 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. Silicates, phosphates, carboxylates, sulfonates, acrylates, and the like are well known as dispersants, but alkali salts of each are common and are used alone or in combination. Basic aluminum lactate (hereinafter abbreviated as aluminum lactate) was developed by Taki Chemical Co., Ltd. and is a feature of the present invention. Alumina hydrate obtained by reacting a water-soluble aluminum salt with carbonic acid or a carbonate with lactic acid 1□03/lactic acid (molar ratio) 0.3-2
°0 (Japanese Unexamined Patent Publication No. 57-8034), and has the general formula AI (OH) 3-x (Lac, Ac1d) x
It is a polymer electrolyte consisting of a polynuclear complex represented by -nH2O, and is currently commercially available from the developer under the trade name Taxeram. The amount of aluminum lactate used is 0 for the fireproof composition.
．． 2 to 10-1%, preferably 0.3 to 6 wt%. This is because if it is less than 0.2 wt%, no effect is observed, and if it is more than 10 wt%, the strength will be significantly lowered. Note that aluminum lactate also acts as a dispersant or a binder. As the binder, hardening agent, and hardening accelerator, cements such as Portland cement, alumina cement, and barium cement, M
g'0, alkaline earth metal oxides and hydroxides such as dolomite, ρ-alumina, alumina hydrate, chromic acid, phosphoric acid, aluminum phosphate, alkali phosphate, aluminum sulfate, sodium silicate, sodium aluminate , Li salt neck, colloidal silica, etc. can be used, and they may be used alone or in combination as appropriate depending on the aggregate, binder, or purpose. Incidentally, it is possible to add Al powder or organic short fibers, which are known techniques for preventing explosion of cementless castable refractories, in combination, and addition of steel fibers or other metal powders can also be used as necessary. Among these, organic fibers, especially natural fibers, and synthetic fibers that have low softening and decomposition temperatures (for example, JP-A-59-169985, JP-A-61
-44772 publication, 61-77673 publication, 61-77673 publication
2-21767, etc.) or materials with good wettability and dispersibility with water (for example, easily soluble vinylon fiber).

Spraying is carried out using known wet or dry methods. When premixing is performed by a wet method or a dry method, the curing agent and curing accelerator are preferably added through a nozzle. Of course, methods such as those disclosed in Japanese Patent Application Laid-open Nos. 60-86079 and 61-101470 can also be used.

[Effect]

Dense, high-strength cementless and cement-free castable refractories that use ultrafine powders and dispersants have low porosity when heated and dried after construction, so they do not release moisture easily and can be violently heated due to rapid heating. As mentioned above, aluminum lactate can cause steam explosions, but after discovering that aluminum lactate has a significant improvement effect on this explosion, the applicant previously filed a patent application (Japanese Patent Application No. 60-239047 issue). The reason for this effect was thought to be that minute cracks that are difficult to see with the naked eye occur in the molded body (constructed body) to which aluminum lactate is added, and water vapor generated by heating is released through these cracks. As seen in the experimental examples below, it was discovered that aluminum lactate has a great effect on cementless castables for spraying, and not only improves the explosion temperature but also significantly increases the hot adhesion rate, and has developed the present invention. reached.

Experiment I A spraying refractory composition consisting of 77-t% of fused bauxite of 95% AIZ, 10 wt% of calcined alumina, 4 wt% of silica flour, 8% of high alumina cement, and 1 wt% of a sodium phosphate dispersant was prepared in JP-A-60. It was created according to Publication No.-11275. Aluminum lactate "Taxeramt 160P" was added to this composition, and explosion temperature and hot blowing tests were carried out, and the results are shown in Table 1.

Table 1 * Explosion temperature is based on a 5 x 5 x 5 cm cubic sample. As the constructed body becomes thicker (as it becomes harder to release water), the explosion temperature tends to be lower.

It is impossible to completely eliminate the temperature drop on the sprayed wall surface. Therefore, both the explosion temperature and the deposition rate are relative values.

Experimental example ■ Sintered alumina, fused alumina, magnesia clinker, spinel clinker, zircon, silica, chamotte, cordierite as aggregates, alumina flour, silica flour, zircon flour as ultrafine powder, polyphosphoric acid as dispersant Soda, carboxylic acid dispersant, aluminum lactate, high alumina cement, aluminum phosphate, aluminum lactate as a binder, fused magnesia powder, calcined magnesia powder, aluminum sulfate powder, sodium aluminate powder as a hardening accelerator, and water injection. Four types of spray compositions were prepared using soluble vinylon staple fibers, and the hot adhesion rates were tested with and without aluminum lactate (M-160P).
Shown in the table.

〔effect〕

From Experimental Examples I and (2), the effect of aluminum lactate 160P is clear, and a remarkable improvement in spray adhesion in hot conditions is observed regardless of the type of aggregate, binder, or hardening accelerator. In Experimental Example ■, the dispersion effect of aluminum lactate appears, resulting in a slight sag. When a curing accelerator is used in combination, the adhesion is further improved. Although specific usage examples are not shown here, blast furnaces, gutters,
Appropriate and effective for hot spray repair of converters, pig iron mixers, electric furnaces, degassing equipment, pots, tundishes, lance vibrators, iron making equipment, steel making equipment, coke ovens, AI furnaces, incinerators, etc. It will be apparent to those skilled in the art that combinations of materials may be used.

Patent applicant Mizo, representative of Nippon Tokushu Rozai Co., Ltd.
Minoru Kuchi

Claims (1)

[Claims] A spray-on fireproof composition characterized by containing basic aluminum lactate as an essential component.