JP2607757B2 - Basic nature coating material for tundish - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating material for covering the surface of a refractory lining of a tundish.

[0002]

2. Description of the Related Art A tundish which is one of continuous casting equipment for steel is provided with a thin layer of a coating material on a lining surface thereof and removing the coating layer each time the tundish is used, thereby contaminating molten steel. Prevention and protection of refractory lining.

A conventional coating material is disclosed in JP-A-59-579.
As proposed in JP-A-69-69, JP-A-63-95175, and the like, the basic properties of magnesia clinker as an aggregate are the mainstream. The basic property has excellent corrosion resistance and is effective in preventing molten steel contamination.

In order to reduce the number of man-hours and improve the operation rate of the tundish, the removal of the coating material must be carried out quickly. In order to satisfy this requirement, it is necessary that the strength after use is small and can be easily removed.

For example, Japanese Patent Application Laid-Open No. 63-95175 proposes a coating material using a lightweight magnesia clinker as an aggregate. This material has low strength due to the porous nature of the aggregate, and is easy to remove.

There is also known a material in which a large amount of organic powder is mixed and the strength of the material is reduced by making it porous due to disappearance of heat.

[0007]

In the use of a tundish, a plurality of tundishes are prepared, and when one is operated, the other is maintained. If the waiting time for the maintenance becomes longer, cooling proceeds, and the refractory lining may be damaged such as cracks due to temperature change. Therefore, recently, the maintenance time has been shortened to prevent the tundish from cooling. For this reason,
Removal of the coating material is required to be quicker and easier than ever before.

[0008] However, the conventional coating material using a lightweight magnesia clinker as an aggregate has low strength of the aggregate itself, but the strength is given by sintering of the aggregates, and it is not easy to remove. In addition, the light-weight magnesia clinker is more expensive than a normal magnesia clinker due to its complicated production, which results in an increase in the cost of the coating material.

[0009] On the other hand, the increase in the porosity due to the addition of a large amount of the organic powder deteriorates the working environment due to fumes caused by the disappearance of the heat, and also causes the molten steel to be contaminated by residual carbon. SUMMARY OF THE INVENTION An object of the present invention is to provide a basic nature coating material which does not have the above-mentioned problems and can be removed quickly and easily.

[0010]

Means for Solving the Problems The present invention, magnesia click
Linker, dolomite clinker, lime clinker or
Is one kind selected from brick waste mainly made of these or
This is a basic property coating material for tundish in which a water-absorbing resin is blended in an amount of 0.01 to 10% by weight with respect to 100% by weight of a refractory aggregate mainly composed of two or more kinds .

It is already known to add water-absorbing resins to refractories. By adding a water-absorbing resin, for example,
The invention of 8-176181 has obtained a porous heat-insulating castable refractory. The invention of Japanese Patent Application Laid-Open No. 62-132777 has an effect of improving nozzle transportability, adhesion rate, long-term storage property, etc. in sprayed refractory. JP 63
In the invention of No. 166770, the effect of promoting the reaction between water and a binder and exhibiting strength is obtained.

On the other hand, the water-absorbing resin in the coating material of the present invention retains a large amount of construction moisture,
In addition to making the refractory structure porous, sintering of the refractory structure was prevented due to the presence of construction moisture between the refractory aggregate particles, and the effect of removing the coating material quickly and easily was obtained. is there. A conventional coating material to which a water-absorbing resin is not added increases the flowability when the working moisture is increased, flows down from a wall surface, and cannot coat the lining surface. In the case of spraying construction, rebound loss increases.

In the conventional material, the amount of applied water is limited to 25% by weight with respect to the coating material, but the material of the present invention can be stably used even with 30 to 50% by weight.

[0014] In addition, coaching material of the present invention is, of 緻 dense matter
With anti-fire material as an aggregate, it is possible to improve the corrosion resistance as compared with the coating material using lightweight magnesia clinker.

[0015] The coating material of the present invention is characterized in that the refractory aggregate is made of a mug.
Nescia clinker, dolomite clinker, lime clink
1 selected from car or brick waste mainly made of these
The use of a refractory aggregate mainly composed of one or more species makes the removal of the coating material easier. This construction moisture is water retention in the water-absorbent resin is difficult to be evaporated, the aggregate surface _{Mg (OH) 2, Ca (} OH) 2 results generated hydrate is accelerated, such as the aggregate the mechanic It is considered that the sintering strength was reduced.

The water-absorbing resin used in the present invention has been conventionally used as a water retention agent for disposable diapers, sanitary products, disposable rags and the like, and can be obtained from commercial products. Specifically, it is a powdery resin such as an ethylene oxide partial polymer, an acrylate polymer or a vinyl alcohol-acrylate polymer. Above all, acrylate polymers such as potassium acrylate polymer and sodium acrylate polymer having excellent water absorption ability and water absorption rate are preferable.

The particle size of the water-absorbing resin is not particularly limited. The average particle size is preferably 10 to 1000 μm, but it can be used even if it is larger or smaller.

Further, a water-absorbent resin containing an ultrafine inorganic powder having an average particle diameter of 0.001 to 10 μm, such as silica, titanium oxide, or alumina, of about 30% by weight or less and having improved gel strength can be used. Good.

The amount of the water-absorbing resin is 100 w
If the amount is less than 0.01% by weight, the effect of the present invention is not obtained. If the amount exceeds 10% by weight, the sintering strength of the coating material becomes too small and the corrosion resistance becomes insufficient.

The basic refractory raw material is, as in the case of the conventional coating material, one or two or more selected from electrofused or sintered magnesia clinker, dolomite clinker, lime clinker, or brick waste mainly composed of these. And Among them, magnesia clinker excellent in digestion resistance is preferable. Dolomite clinker and lime clinker are inferior in digestion resistance. Therefore, when they are used, it is preferable to mix magnesia clinker in the fine particles. In terms of steel cleaning, lime clinker is the best. As the lime clinker, it is preferable to use a digestion-resistant treated product having a CaCO ₃ film formed on the surface thereof by CO ₂ gas treatment.

Although not preferred in terms of cost and corrosion resistance, a lightweight magnesia clinker having a bulk specific gravity of, for example, 2.0 or less may be used for part or all of the aggregate.

Most preferably, the aggregate comprises only a basic refractory raw material. If necessary, a refractory raw material such as spinel, limestone, silicon carbide, alumina, silica, etc., other than the refractory raw material described above, is blended as long as it does not affect the cleaning of the steel and does not promote sintering of the coating material. May be. Since a basic refractory raw material such as limestone does not contaminate molten steel, a relatively large amount may be blended.

As for the preparation of the coating material, a binder is externally added to about 100 wt% of the refractory aggregate and about 1 to 5 wt% is blended as usual. If necessary, a curing agent, a short fiber, a thickener, a lightweight aggregate, a foaming agent and the like are added in appropriate amounts.

The type of the binder is not limited.
For example, various phosphates such as sodium phosphate, calcium phosphate, magnesium phosphate, potassium phosphate, and aluminum phosphate, various silicates such as sodium silicate, potassium silicate, lithium silicate, magnesium sulfate, and aluminum sulfate. One or two or more selected from sulfates or alumina cement are used.

As the curing agent, for example, calcium hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, lithium carbonate, gypsum, Portland cement,
One or more selected from dicalcium silicate, sodium fluoride, various calcium phosphates, and the like. The mixing ratio is 10 wt% or less, preferably 0.5 to 5 wt%, based on 100 wt% of the refractory aggregate.

Short fibers are effective in improving adhesion. For example, one or more selected from organic fibers such as cotton, synthetic fiber, and pulp, ceramic fibers, glass fibers, asbestos, sepiolite, and slag fibers. The compounding ratio is 5% by weight or less, preferably 0.01 to 3% by weight, based on 100% by weight of the refractory aggregate.

The thickener is, for example, one or more selected from clay, bentonite, organic paste, various silicates, various phosphates and the like. The mixing ratio is 10 refractory aggregates.
It is 10% by weight or less, preferably 0.1 to 5% by weight, based on 0% by weight.

The coating material of the present invention is obtained by mixing a composition having the above composition, adding water for application to the mixture, and then applying a thickness of 5 mm to the surface of the lining by ironing or spraying.
It is constructed with a thickness of ５０50 mm. The latter spraying is preferable from the viewpoint of labor saving of construction and work safety. This spraying is, for example, a wet method of adding construction moisture from the beginning, a dry method of adding moisture or a liquid binder in a nozzle, a semi-dry method of adding moisture or a liquid binder in a nozzle to a moistened material, and the like. A method is also acceptable.

[0029]

EXAMPLES Examples of the present invention and comparative examples are shown below in Tables 1 and 2.

As the water absorbing resin, a potassium acrylate polymer and a sodium acrylate polymer were used. The ratio of the construction moisture was indicated by an outer coat with respect to the entire coating material. The test method for each example is as follows.

Adhesion: A vertical spray gun was used to spray a vertical wall made of alumina-silica amorphous refractory, and the adhesion was evaluated on a three-point scale.

…: Good, 普通: normal, ×: poor Worked body strength: After casting, the bending strength of a test piece obtained by heating at 1500 ° C. for 3 hours was measured, and the strength of the worked body after use was measured. Was assumed. When the strength of the construction body after heating is low, peeling and removal becomes easy after the use of the coating material.

Erosion test: A test piece obtained in the same manner as described above was subjected to a rotary erosion method. After repeating the molten steel temperature 1600 ° C. × 30 minutes six times, the erosion dimension was measured. It is indicated by an index with the erosion dimension of Comparative Example 1 as 1, and the smaller the numerical value, the better the corrosion resistance.

[0034]

[Table 1]

[0035]

[Table 2]

The embodiment of the present invention is excellent in adhesion due to the water retention of the water-absorbing resin even if the working moisture is large. The strength of the construction body is small, and the removal is quick and easy. Further, the corrosion resistance is not so deep as compared with the conventional type of Comparative Example 1.

On the other hand, in Comparative Example 1 in which the water absorbing resin was not added and the working moisture was set to the usual ratio, the strength of the working body was large. Comparative Example 2 is inferior in corrosion resistance due to too much water absorbent resin. In Comparative Example 3, a light-weight magnesia clinker was used as a main aggregate without adding a water-absorbing resin, and the construction body had high strength and poor corrosion resistance. Comparative Example 3
Since the adhesion was poor when the construction moisture was increased, the construction moisture was set to 25 wt% of the conventional type. In Comparative Example 4, since the water-absorbent resin was not added, when the working water content was increased, splashing at the time of spraying was large, and the adhesion was poor.

The comparative example shown in Table 2 is a material using a non-base refractory raw material as a main aggregate. In Comparative Example 5, the water retention was increased by the addition of the water-absorbing resin, and the adhesion was excellent even when the working moisture was increased. However, compared to Comparative Example 6 in which no water-absorbing resin was added, there was no remarkable difference in the reduction in strength of the construction body as seen in the basic material. As is clear from these results, it is a phenomenon peculiar to the basic coating material that the water-absorbing resin significantly lowers the strength of the construction body after use.

A part of the Examples and Comparative Examples was used as a 30 t tundish coating material lined with an alumina-silica amorphous refractory, and a time required for removing the coating material after the tundish was operated. Was measured. The results are as shown in Table 3.

[0040]

[Table 3]

In the actual machine test, a dry spray gun was used for the construction, and the refractory lining was sprayed to a thickness of about 20 mm on the surface. Examples 2, 4 and 5, off Haku only by inverting the tundish, there is no particular need to remove the work.

[0042]

As described above, the coating material of the present invention is extremely easy to remove without impairing the cleaning and corrosion resistance of steel having basic properties. As a result, it is effective in reducing the number of work steps for removing the coaching material and improving the operation rate of the tundish. In addition, the quick removal can shorten the maintenance time of the tundish, and can prevent cooling damage to the tundish lining.

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Taizo Taizo 1-3-1, Shinhama, Arai-machi, Takasago City, Hyogo Prefecture Inside Harima Ceramics Co., Ltd. (72) Inventor Manabu Kimura 1-3-1, Shinhama, Arai-machi, Takasago City, Hyogo Prefecture No. Harima Ceramics Co., Ltd. (56) References JP-A-62-132777 (JP, A) JP-A-58-176181 (JP, A) JP-A-1-157749 (JP, A)

Claims (3)

(57) [Claims] 1. Magnesia clinker, dolomite
Coal, lime clinker or
100% by weight of a refractory aggregate mainly composed of one or more selected from waste chips , and a water absorbent resin,
A basic property coating material for tundish which contains 10 to 10% by weight. 2. The basic coating material for tundish according to claim 1, wherein the water-absorbing resin is an acrylate polymer. 3. The tan according to claim 1, wherein the short fiber is further blended in an amount of 5 wt% or less with respect to 100 wt% of the refractory aggregate.
Basic property coating material for dishes .