JPH1192239A - Thermally insulating blast plastic refractory - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the material that simultaneously satisfies the weight- lightening of the material and the shrinkage (cracking) prevention of the worked body by adding specific amounts of hydraulic alumina cement as a binding aid, a dispersant, a binding accelerator and a thickener to a formulation containing fire clay and a refractory aggregate containing a light-weight aggregate at a specific ratio. SOLUTION: To a formulation of refractory aggregate containing light-weight aggregate, containing 20-40 wt.% of fire clay and the rest part of refractory aggregate whose particle size is adjusted, are added 1-8 wt.% of a hydraulic alumina cement, 0.01-1.0 wt.% of a dispersant, and 0.01-3.0 wt. % of a binding accelerator and a thickener, respectively. The refractory aggregate is, for example, sintered alumina, fused alumina, bauxite, aluminous shale, mullite, Chamotte fireclay, agalmatolite, kyanite and the like. The light-weight aggregate is, for example, light-weight chamotte, light-weight thermally insulating brick dust, pearlite, vermiculite and the like. The ratio of the light-weight aggregate to the refractory aggregate is suitably 20/80-60/40. The dispersant is preferably sodium tripolyphosphate and the binding accelerator is preferably slaked lime.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an insulated sprayed plastic refractory which has high heat insulating properties, has little shrinkage after drying and heating, has excellent adhesion and shape retention without change over time.

[0002]

2. Description of the Related Art Plastic refractories are well known as lining materials for kilns because of their excellent spall resistance. The features of the construction using the irregular shaped refractory are that an integrated structure without joints can be obtained and continuous construction can be performed with a rammer. In recent years, there is a sprayed plastic refractory using a special spraying machine. However, conventional general plastic refractories are made of refractory aggregate, refractory clay, a small amount of adhesive, etc., and are kneaded by adding an appropriate amount of water to obtain a suitable softness. See JP-A-48-74514).

[0003] Conventional plastic refractories are mainly made of materials having a dry bulk specific gravity of 2.0 or more. Insulated plastic refractories having a low specific gravity, such as insulated castable refractories having a dry bulk specific gravity of 1.5 or less, have hardly appeared. Because, the refractory lightweight aggregate that is the main aggregate itself is very soft compared to general refractory aggregate, and the refractory lightweight aggregate itself is crushed or broken when driven with a rammer. Therefore, the specific gravity of the material increases. Also, the quality is not stable. In addition, in order to obtain lightweight refractory plastic refractories, unless a large amount of clay is used, workability during construction (plasticity,
(Shape retention) cannot be obtained. In other words, in order to reduce the weight,
Since it is composed of a mixture of a fire-resistant lightweight aggregate and a large amount of fire-resistant clay, the amount of added water becomes considerably larger than that of general plastic refractories, and the shrinkage (crack) of the construction body increases. For this reason, the conventional materials cannot simultaneously prevent the shrinkage required for the properties of the insulated plastic refractory and reduce the weight of the material.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a material which simultaneously satisfies the contradictory conditions of reducing the weight of the material required for the properties of the insulated plastic refractory and preventing shrinkage (cracking) of the construction body. With the goal.

[0005]

According to the present invention, a refractory clay 20 is provided.
A mixture of ４０40% by weight and a balance of refractory aggregate including light-weight aggregate, the particle size of which is adjusted to the balance, and 1 to 8% by weight of hydraulic alumina cement as a binding aid in an outer case, and dispersion. An insulated sprayed plastic refractory comprising 0.1 to 1.0% by weight of an agent and 0.01 to 3.0% by weight of a quick setting agent and a pressure-sensitive adhesive, respectively.

[0006] With this configuration, drying,
A material that is effective in preventing shrinkage after heating and that has low shrinkage, and that also sufficiently satisfies weight reduction and workability is obtained. Less than,
The present invention will be described in more detail.

The refractory clay in a plastic refractory composition is
The workability during construction largely depends on the plasticity.
The graph of FIG. 1 shows the relationship between the amount of refractory clay and the adhesion rate for vertical wall spraying. For the test, the hydraulic alumina cement was fixed at 3% by weight, slaked lime was 0.5% by weight as a quick setting agent, MC was 0.5% by weight as an adhesive, and 0.1% was used as a dispersant.
A sample to which 4% by weight was added was used. The lightweight aggregate of this sample was composed of 35% by weight of lightweight insulating brick waste (7-1 mm) and 5% by weight of pearlite.

As a result of the test, the adhesion ratio is preferably in the range of 20 to 40% by weight. In consideration of this and the workability, in the present invention, the lower limit of the blending amount of the refractory clay with the refractory aggregate is 20% by weight, and the upper limit is 20% by weight. Was 40% by weight. If it exceeds 40% by weight, the adhesive strength is high and the shrinkage ratio is large. On the other hand, if it is less than 20% by weight, the adhesive strength is poor, and the workability is reduced.

The refractory aggregate is, for example, one or more selected from sintered alumina, electrofused alumina, bauxite, ban shale, mullite, chamotte, rolite, kyanite and the like, and as a lightweight aggregate. One or more selected from lightweight chamotte, lightweight insulated brick debris, perlite, vermiculite and the like are used in combination with particle size adjustment and blending. The ratio of lightweight aggregate to refractory aggregate is 20: 8
0-60: 40 is appropriate. If the weight of the lightweight aggregate is less than 20, the specific gravity becomes heavy, and if it is more than 60, the plasticity becomes poor and the workability decreases.

In the present invention, the mixture of the above refractory clay and the refractory aggregate including the lightweight aggregate is externally applied, 1 to 8% by weight of hydraulic alumina cement as a binding aid, and 0.1 to 0.1% of a dispersant.
1.0% by weight, 0.01% each
-3.0% by weight.

FIG. 2 shows the effect of adding hydraulic alumina cement as a binding aid. In other words, a material obtained by using a grain size-adjusted chamotte, lightweight insulating brick debris and perlite as a main aggregate and blending 25% by weight of refractory clay therewith,
0.4% by weight of sodium tripolyphosphate as a dispersant, 0.5% by weight of slaked lime as a quick setting agent, and 0.5% by weight of MC as an adhesive, and a hydraulic alumina cement up to 10% by weight as a binding aid. Was added. FIG. 2 shows a change in shrinkage with respect to the amount of hydraulic alumina cement added at this time.

From FIG. 2, it can be confirmed that shrinkage of the plastic refractory to which hydraulic alumina cement is added is reduced by adding hydraulic alumina cement. A plastic refractory to which no hydraulic alumina cement is added has a good shape retention but a large shrinkage. When the shrinkage ratio is 6% by weight or more, there is not much difference, but when it exceeds 8% by weight, the material is agglomerated quickly and loses shape retention. Therefore, in view of certainty, the upper limit of the hydraulic alumina cement was set to 8% by weight on the outside.

As the dispersing agent, sodium tripolyphosphate which is hardly changed with time due to hydrolysis or the like under the influence of moisture among several kinds of polymerized sodium phosphate is preferable. The dispersing power of sodium tripolyphosphate is somewhat low, and it is excellent in sodium hexametaphosphate dispersing power, but it is easily hydrolyzed and unstable, so sodium tripolyphosphate is more advantageous, especially in combination with an adhesive such as MC. Is also effective. The dispersant has a water reducing effect, and has an effect of improving workability with a small amount of water. If the content is less than 0.1% by weight, the effect is not sufficient.
If it is more than 0% by weight, the strength and the like will be affected.

A quick setting agent and an adhesive are used in combination. Examples of the quick setting agent include slaked lime, Portland cement, sodium aluminate, gypsum, blast furnace cement, etc., but slaked lime having a high cohesive force is preferred. However, since the adhesiveness is poor, it is better to use the binder as a binder than to add a quick-linking agent alone. Gum arabic, tracant gum, textulin, British gum, carboxymethyl cellulose (CM
C), methyl cellulose (MC), sodium alginate and the like. By adding such an adhesive, the adhesiveness of the material is moderately increased and stabilized, excellent in shape retention, surface treatment after construction,
Trimming also becomes easy.

The method of applying the heat-insulating plastic refractory of the present invention is by spraying. Before the application, an appropriate amount of water is added to the mixture excluding the quick-setting adhesive and the adhesive at the spraying site, and a slurry-like fluidity can be obtained with a small amount of water by the dispersant contained in the mixture. In the range of 20 to 40% by weight of the refractory clay, the slurry viscosity of the mixture is appropriate, and the slurry can be smoothly transported by spraying material and transporting in a hose for air pressure feeding.

The quick-setting adhesive and pressure-sensitive adhesive are pumped by a hose different from the above-mentioned mixture, and mixed with the mixture at the tip of the spray nozzle. Due to these additions, they aggregate immediately after the construction. That is, the adherence is good, the construction body does not sag from the vertical wall surface, and is excellent in shape retention.

In the conventional materials, water is added and kneaded in order to obtain plasticity in advance, so that there is a problem in storability. In particular, there is a drawback in that the quality varies greatly due to aging of the material during storage in the summer and freezing during the severe cold season. On the other hand, since the plastic refractory of the present invention does not add moisture until immediately before spraying on site, there is no change with time and a construction body more stable in quality than conventional products can be obtained.

[0018]

Next, specific compositions will be described with reference to examples and comparative examples of the present invention. Table 1 shows Examples and Table 2 shows Comparative Examples. The shrinkage in the table is a value measured according to JIS R2554.

[0019]

[Table 1]

[0020]

[Table 2]

Examples of the present invention shown in Table 1 have a refractory clay content of 20 to 40% by weight, which is optimal for spraying, and a vertical wall adhesion rate of 88% or more. In addition, construction body is dry,
Low firing shrinkage. When the amount of the refractory clay is less than 20% by weight, the shrinkage becomes small, but the plasticity and the shape retention deteriorate.

On the other hand, Comparative Example 2 in which the proportion of CMC is larger than the range of the present invention has too high adhesive strength, and Comparative Example 1 in which the proportion of slaked lime is larger than the range of the present invention contains hydraulic alumina cement. The results are not good because of the high proportion of fireclay. The other comparative examples do not contain hydraulic alumina cement as a binding aid, so that the shrinkage is large. In Comparative Example 9 in which no hydraulic alumina cement was added and various additives were not added, the workability was good but the shrinkage was also large.

When the relationship between the drying and heating shrinkage ratios of the actual sprayed articles is compared with the material of Example 5 in Table 1 and Comparative Example 9 in Table 2 corresponding to the conventional material, the material of Comparative Example 9 is 5
It can be seen that the shrinkage is large and the adhesion rate is poor as compared to In Example 5, the drying shrinkage was small and the adhesion rate was excellent.

It can be said from the results that the shrinkage of the conventional material is mainly governed by the amount of refractory clay and the added moisture, but in the present invention, the addition of hydraulic alumina cement and the amount of clay cause cohesion and self-hardening. It can be confirmed that there is an action, thereby suppressing the contraction. Furthermore, the materials of Example 5 and Comparative Example 9 were actually applied to the side wall of a large panel (2.0 mx 1.0 m), and the change in the score line width of 1.0 mm was observed to test the shrinkage of the applied wall. did. The result is shown in FIG. In Example 5, the shrinkage was smaller than that of Comparative Example 9, and the sprayability was excellent, and the vertical wall had a high adhesion rate of 93%.

[0025]

According to the present invention, the workability required for a lightweight heat-insulated sprayed plastic refractory is obtained, the shrinkage of the construction body is small, there is no change with time, and the thermal conductivity is lower than that of the conventional product. It is made of a material with excellent heat insulation. further,
Since it is a sprayed plastic refractory construction material, it is possible to reduce the number of repair steps and improve the work efficiency.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the amount of refractory clay added and the adhesion rate to a vertical wall during spraying according to the present invention.

FIG. 2 is a graph showing the relationship between the amount of hydraulic alumina cement added and the drying shrinkage.

FIG. 3 is a graph comparing the shrinkage rate between the execution wall score lines between the embodiment and the comparative example.

Claims (1)

[Claims] 1. A mixture of 20 to 40% by weight of a refractory clay and a refractory aggregate containing a light weight aggregate, the balance of which is adjusted to a particle size, and a hydraulic alumina cement as a binding aid, 8% by weight, and 0.1 to 1.0% by weight of a dispersant, and 0.01 to 3.0% of a quick-setting adhesive and a pressure-sensitive adhesive, respectively.
Insulating sprayed plastic refractories, characterized in that they contain by weight.