JP2596594B2 - Spray repair material for atmosphere furnace - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a spray repair material for extending the life of a refractory lining of an atmosphere furnace such as a steel heating furnace and a soaking furnace.

[Conventional technology]

The operation of the atmosphere furnace is a repetition of severe heating and cooling for refractory lining. Therefore, the wear of the refractory lining progresses as it is used for a long time, and it is necessary to replace the refractory lining periodically.

In the past, refilling work for lining refractories has often been carried out by casting, but frame setting, refractory kneading, pressure feeding,
It consisted of complicated work processes such as pouring, curing, drying and heating, and was not satisfactory in terms of construction time and repair cost.

For this relining work of refractory lining, it is conceivable to apply a spraying repair method that can easily repair in a short time.

The workability as a spraying material is that there is no peeling of the adhesion zone, the adhesion of the refractory lining is strong, the volume stability is good due to the repeated operation of heating and cooling, and 800 to 1400 ° C It is necessary that the material has excellent spall resistance even when repeatedly used in a high temperature range and has no strength deterioration.

However, conventional spray materials use a large amount of binders such as cement, phosphate, silicate, refractory clay, etc.
The above conditions cannot be satisfied, and no practical application is possible.

In addition, in order to improve the strength and structure of the sprayed construction, 1-10% by weight of clay, ultrafine silica particles, ultrafine alumina particles, etc., alumina cement, dispersant, and hardening accelerator are added to the refractory aggregate whose particle size has been adjusted. The addition is disclosed in JP-A-62-36071.

However, the material disclosed in the above-mentioned publication falls off early in an atmosphere furnace, particularly in a ceiling portion of the atmosphere furnace due to poor shape retention, and has a poor repair effect.

[Problems to be solved by the invention]

The problem to be solved in the present invention is to provide a lining repair material which is excellent in hot properties, adhesiveness and volume stability in a high temperature range and is particularly suitable for use in an atmosphere furnace. Another object of the present invention is to achieve shortening of construction time, extension of life, and reduction of furnace material cost by easily and surely spraying and repairing a material.

[Means for solving the problem]

According to the present invention, a low cement bond castable containing silica cement, a dispersant, and a hardening accelerator, which is obtained by adding ultrafine silica particles and ultrafine alumina particles to a refractory aggregate, has a high temperature range of hot properties, and an adhesive property with a base material. And found to have excellent adhesiveness with excellent volume stability, and completed the spray repair material of the present invention.

That is, spraying for an atmosphere furnace containing ultra-fine particles of silica and alumina in a total amount of 5 to 10% by weight and a hardening accelerator in a range of 0.2 to 2.0% by weight to a refractory having a controlled particle size containing alumina cement and a dispersant. It is a repair material, and it is desirable that the ultrafine silica particles and the ultrafine alumina particles are in the range of 1/1 to 3/2 by weight.

The refractory aggregate used in the present invention includes fused alumina,
Examples include high alumina raw materials such as sintered alumina and bauxite, but are not necessarily limited thereto.

For the matrix portion, ultrafine alumina particles and ultrafine silica particles are used from the viewpoint of hot properties in a high temperature range, adhesion to a base material, and volume stability.

By using ultrafine silica particles and ultrafine alumina particles for refractory materials whose particle size has been adjusted to include alumina cement and a dispersant, a spray material with phosphate, silicate, refractory clay as a binder in a small amount of alumina cement The adhesive properties with the base material can be obtained, and the hot properties and volume stability in a high temperature range, which are the drawbacks of the conventional cement bond spraying material, can be imparted.

Examples of the ultrafine silica particles include volatile silica produced as a by-product during the production of metallic silicon and silicon alloys and silica flour called white carbon produced by a wet or dry process. The primary particles have a particle size of 1 μm or less. Is preferred.

As the alumina ultrafine particles, calcined alumina having a particle size of 10 μm or less, more preferably 5 μm or less, is suitable.

The total amount of silica ultra-fine particles and alumina ultra-fine particles is in the range of 5 to 10% by weight, and the weight ratio of silica ultra-fine particles and alumina ultra-fine particles is in the range of 1/1 to 2/3. Excellent in properties and volume stability.

The total amount of silica ultra-fine particles and alumina ultra-fine particles is 5% by weight
If it is less than 10%, the adhesiveness is poor, and if it exceeds 10% by weight, the volume stability is poor. When the weight ratio of the ultrafine silica particles and the ultrafine alumina particles is less than 1/1, the adhesiveness is poor, and when it exceeds 3/2, the volume stability is poor. The reason for this is that since the particle size of the ultrafine silica powder is 1 μm or less, the silica ultrafine powder works extremely actively on the adhesion to the wall surface.

FIG. 1 is a diagram showing the relationship between the weight ratio of ultrafine silica particles and ultrafine alumina particles and the adhesive shear strength, and FIG. 2 is a graph showing the weight ratio of ultrafine silica particles and ultrafine alumina particles to 1,400.
It is a figure which shows the relationship with the expansion coefficient when it heats up to ° C.

As shown in FIG. 1, the adhesive shear strength increases as the weight ratio between the ultrafine silica particles and the ultrafine alumina particles increases. However, when this weight ratio is increased, the sinterability is improved, and as shown in FIG. 2, the tendency of shrinkage is increased, and the adhesion to the wall surface is deteriorated.

Furthermore, it is necessary to add a curing accelerator in order to maintain the workability as a spray material. Examples of the flocculant include anionic flocculants such as potassium nitrate, aluminum sulfate, magnesium sulfate, potassium chloride, calcium hydroxide, and calcium hydroxide as a flocculation hardening accelerator, which do not increase the sprayed water content.

FIG. 3 is a graph showing the addition amount of a curing accelerator, the bending strength one hour after spraying, and the amount of sprayed water necessary for obtaining the maximum sprayed thickness.

Referring to FIG. 3, the addition amount of the curing accelerator was 0.
2 to 2.0% by weight is preferable. As shown in FIG. 3, if it is less than 0.2% by weight, sagging occurs during spraying and a sufficient work thickness cannot be secured, and if it exceeds 2.0% by weight, a large amount of spray water is required. In addition, the structure of the construction body is deteriorated, and it is difficult to obtain sufficient strength, and the adhesion to the base material is deteriorated.

〔Example〕

Examples A and B of Table 1 show examples of the present invention, and show measured values of physical properties required as spray repair materials for atmosphere furnaces.

None of the conventional spraying materials (E to G) satisfy all the physical property values, and are not suitable because of any of adhesiveness, hot physical properties, and volume stability.

In Comparative Example C, the amount of ultrafine silica particles was large, the hot physical properties and the volume stability were poor, and the adhesion was significantly deteriorated in a high temperature range.

In Comparative Example D, there were many alumina ultrafine particles and the hot properties were good, but the amount of silica ultrafine particles was insufficient and the adhesive strength was deteriorated.

Thus, in the case of Comparative Examples C and D in which the weight ratio of silica ultra-fine particles / alumina ultra-fine particles was out of the range of 1/1 to 3/2, there was a problem in adhesiveness as an atmosphere furnace spray repair material. .

Experimentally, spraying was performed with a thickness of 100 mm on the ceiling in the furnace shown in FIG.
Heating and cooling were repeated and a test was performed.

 Table 2 shows the number of times until the peeling of the construction body occurs.

As shown in Fig. 6, the material of the present invention (A in Table 1) was used in the heating zone of the heating furnace and the damaged portion of the refractory lining on the soaking roof.
Was sprayed while mixing with water at the nozzle using a dry spray machine.

As a result, the adhesion rate exceeded 85%, and there was no problem with workability. The repair material was still healthy one year after the repair.

〔The invention's effect〕

 The present invention has the following advantages.

(1) Long life of refractory lining can be measured and refractory cost can be reduced.

(2) Excellent in hot properties (strength, volume stability) and adhesion to refractory lining.

(3) Spraying can be performed in a short time, and no special drying is required.

[Brief description of the drawings]

FIG. 1 and FIG. 2 show the silica / metal in the repair material of the present invention.
FIG. 3 shows the effect of the weight ratio of alumina on the construction body, and FIG. 3 shows the effect of the curing accelerator. 4 to 6 are diagrams showing test conditions of the repair material of the present invention.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tadashi Yoshimura 1-1, Higashihama-cho, Yawatanishi-ku, Kitakyushu-shi, Fukuoka (72) Inventor Masanori Koga 1-1-1, Higashihama-cho, Yawatanishi-ku, Kitakyushu-shi, Fukuoka Kurosaki Ceramics Co., Ltd.

Claims (2)

(57) [Claims] 1. A refractory aggregate whose particle size has been adjusted, ultrafine silica particles having a particle diameter of 1 μm or less and a particle diameter of 10 μm.
5 to 10% by weight of the following ultra-fine particles of alumina, 2 to 6% by weight of alumina cement, 0.1 to 1.0% by weight of dispersant, and 0.2 to 2.0% by weight of hardening accelerator A spray repair material for atmosphere furnaces. 2. The spray repair material for an atmospheric furnace according to claim 1, wherein the weight ratio between the ultrafine silica particles and the ultrafine alumina particles is 1/1 to 3/2.