JP2869881B2 - Spray material for kiln repair - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a blast furnace repair material having excellent adhesive strength.

[0002]

2. Description of the Related Art The lining of industrial kilns such as converters, ladles, tundishes, mixed iron wheels, vacuum degassing furnaces and the like has been repaired by spraying. The properties required of the spray material used for this repair are adhesion, adhesive strength and corrosion resistance. Unlike ordinary refractories, the spraying material must have excellent adhesion (adhesion rate) and adhesive strength (adhesion after adhesion). Various proposals have been made for the material of the spray material. For example, there is JP-B-55-6598 to which sodium hexametaphosphate and slaked lime are added.

[0003]

Even with conventional materials, there is a remarkable improvement in adhesion. However, the bond strength is still not sufficient. After spraying material adheres,
If the adhesive strength is low due to contact with high heat or molten metal due to the operation of the furnace, it will be removed. Therefore, no matter how excellent the adhesion and the corrosion resistance are, the life of a material having poor adhesive strength is short.

[0004]

SUMMARY OF THE INVENTION The present invention is to provide a spraying material having excellent adhesive strength without deteriorating adhesion and corrosion resistance. Alumina 2-50 wt%, binder 1-20 wt%, aluminum sulfate 0.5
It is a spray material for kiln repair consisting of about 7% by weight and a calcium salt.

When magnesia and alumina are used as aggregates, MgO.Al ₂ O ₃ spinel is generated by a reaction between the two due to a high temperature atmosphere generated by operating the furnace. MgO
· Al ₂ O ₃ spinel solid solution slag component acts on preventing slag penetration is effective in improving corrosion resistance. In the present invention, by further combining this with aluminum sulfate, the adhesive strength is significantly improved.

[0006] The improvement of the adhesive strength by aluminum sulfate is considered to be due to the following reasons. That is, aluminum sulfate loses a sulfuric acid component at a high temperature, and the remaining aluminum is oxidized to produce alumina. The alumina thus formed is fine particles. Moreover, due to its surface properties, it is extremely active, has an action of accelerating the reaction between magnesia and alumina as an aggregate, and rapidly generates MgO.Al ₂ O ₃ spinel in the structure of the spray material.

[0007] In the structure of the construction body made of the spray material, the inner surface side of the furnace is exposed to high heat. In the conventional spraying material, the inner surface of the furnace that receives high heat shrinks due to sintering and deforms so as to warp against the surface to be repaired. This is the cause of the decrease in adhesive strength. On the other hand, in the material of the present invention, the inner surface side of the furnace receiving high heat has M
Preventing warpage of the surface to be repaired due to expansion due to rapid generation of gO.Al ₂ O ₃ spinel has an effect on improvement of adhesive strength.

[0008] Even with the same aluminum compound, for example, the effect of the present invention cannot be obtained with aluminum lactate.
This is presumably because aluminum lactate has a low agglomeration rate and conditions for rapidly generating spinel are not established.

The magnesia used as the aggregate is natural magnesia, a sintered product of seawater magnesia or an electrofused product. If the proportion is less than 30 wt%, the effect of corrosion resistance of magnesia becomes insufficient. If it exceeds 97% by weight, the proportion of alumina decreases and the slag penetration resistance is poor.

Specific examples of alumina include fused alumina, sintered alumina, fused mullite, sintered mullite, shale, bauxite, and sillimanite. 3wt%
If it is less than 1, the amount of spinel produced is insufficient, and the slag penetration resistance is poor. If it exceeds 50% by weight, the proportion of magnesia decreases and the corrosion resistance decreases.

The particle size of each of magnesia and alumina is as follows:
It is adjusted to coarse, medium, and fine particles in consideration of the adhesive property, filling property, and the like. Alumina having a smaller blending ratio than magnesia is preferably made to be mainly composed of fine particles in order to promote the spinel formation reaction. As a refractory aggregate, if necessary, silica-alumina, spinel, calcareous, limestone, zircon, zirconia, carbide, nitride, boride, carbon, etc. may be used in combination as long as the effects of the present invention are not impaired. .

As the binder, alumina cement which is excellent in the strength of the construction body is most preferable. In addition, for example, silicate, phosphate and the like may be used. The ratio is 1w
If it is less than t%, the strength of the construction structure is inferior, and if it exceeds 20 wt%, the corrosion resistance decreases.

Aluminum sulfate is powdered, and Al ₂ O ₃
Preferably, the component is 10 wt% or more. Conventionally, aluminum sulfate is also known as a hardening accelerator for amorphous refractories, but the present invention improves the adhesive strength, which is an important property of sprayed materials, by combining with a specific type of aggregate. Has an effect. The same effect can be obtained by using either aluminum salt or hydrate of this aluminum sulfate.

FIG. 1 is a graph showing a change in the adhesive strength of a spray material comprising the composition of Example 1 described below, in which only the ratio of aluminum sulfate is changed. 0.5 wt.% In outer weight to the combined amount of refractory aggregate and binder
%, No remarkable effect is seen in the improvement of the adhesive strength.
If it exceeds 7% by weight, the adhesive strength is sufficient, but the alumina component in the matrix portion becomes excessive and the corrosion resistance is reduced.

The calcium salt has an effect as a hardening agent. Specific materials include slaked lime, quicklime, calcium carbonate, and the like. The ratio may be the same as in the case of the conventional spray material, and is not particularly limited, but is, for example, 0.05 to 5% by weight, based on the total amount of the refractory aggregate and the binder. If it is less than 0.05% by weight, the curing speed is inferior, and it tends to run off after spraying. If it exceeds 5% by weight, the porosity is increased and the strength tends to decrease.

[0016] In addition to the above, for example, pitch, phenolic resin, borate, silica flour, silica sol, alumina sol, aluminum lactate, refractory ultrafine powder, CMC, sepiolite, which are known as additives for conventional spraying materials , Sodium alginate, clay, bentonite, organic fibers, inorganic fibers, metal fibers, water-absorbing polymers, metal powders and the like may be added in small amounts.

In the spraying operation, the sprayed material of the present invention can sufficiently exhibit its effects in both cold repair when the furnace wall temperature is low and hot repair in which the furnace wall temperature is around 1000 ° C. it can.

[0018]

EXAMPLES Table 1 shows examples of the present invention and comparative examples.
The test method is as follows. Corrosion resistance: Moisture was added to the composition at an external rate of 17 wt%, mixed, cast into a slurry, dried, and measured by a rotary erosion test. It is indicated by an index with the erosion dimension of Example 1 as 100. The smaller the index value, the better the corrosion resistance.

Adhesiveness; on a furnace wall having a surface temperature of about 700 ° C.
Spraying was performed by a dry spraying method to determine the adhesion rate. Adhesive strength: The composition was made into a slurry by adding water at 15 wt% and cast into a 40 mm thick brick surface. After drying, it was put in an electric furnace at 1500 ° C. while being attached to the brick and heated. Thereafter, a pressure stress was applied to the spray material in parallel with the spray material attachment surface, and the shear adhesive stress was measured. Actual machine test: A spray repair of a 200-t molten steel ladle was tested, and its service life was measured.

[0020]

[Table 1]

The embodiment of the present invention has the required properties of the spraying material such as corrosion resistance, adhesion and adhesive strength. The effect can be confirmed from the service life in the actual machine test. In Comparative Example 1, no aluminum sulfate was added, and the adhesive strength was poor. Comparative Example 2 in which the addition amount of aluminum sulfate was too large was inferior in corrosion resistance. Although aluminum sulfate was added, Comparative Example 3 in which the refractory aggregate was only magnesia and Comparative Example 4 in which only alumina was used had poor adhesive strength. Comparative Example 5, in which aluminum lactate was added instead of aluminum sulfate, had insufficient adhesive strength.

[0022]

As is clear from the above test results, the spray material for repairing a kiln of the present invention has excellent adhesive strength, which is an important characteristic of the spray material. There is no color in adhesion and corrosion resistance. As a result, it shows extremely excellent durability.

[Brief description of the drawings]

FIG. 1 is a graph showing the relationship between the ratio of aluminum sulfate and the adhesive strength of a spray material.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kozo Yamada 1-3-1 Shinhama, Arai-machi, Takasago City, Hyogo Prefecture Inside Harima Ceramics Co., Ltd. (72) Inventor Taizo Taihiro 1-3-1 Shinama, Arai-machi, Takasago City, Hyogo Prefecture Harima Ceramics Co., Ltd. (56) References JP-A-62-148354 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C04B 35/66

Claims (1)

(57) [Claims] 1. A spray material for repairing a kiln, comprising 30 to 97% by weight of magnesia, 2 to 50% by weight of alumina, 1 to 20% by weight of a binder, 0.5 to 7% by weight of aluminum sulfate and calcium salt on an outer surface.