JPH09239502A - Method for repairing tundish tuyere - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely, easily and safely repair the damaging part of a tuyere opened in a hot-circulating tundish for fitting an immersion nozzle in a short time. SOLUTION: After sticking repairing material 5 on the outer peripheral surface of a thermal plastic forming material 8 for masonry joint, this repairing material is coated on the immersion nozzle 7 preheated at about 1000 deg.C and inserted into the tuyere 3 in this condition. The filling and the burning of the repairing material 5 to the damaging part 6 and the joining of the immersion nozzle 7 with a tuyere brick 2 are simultaneously executed. As the other way, after repairing the damaging position 6 by inserting a jig sticking the repairing material 5 on the outer peripheral surface into the tuyere 3, the immersion nozzle 7 coated with the forming material 8 for masonry joint is inserted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for repairing tuyere in a hot rotary tundish used in a continuous steel casting operation.

[0002]

2. Description of the Related Art Immersion nozzles used for continuous steel casting operations are for supplying molten steel from a tundish to a mold, and are attached to tuyere opened at the bottom of the tundish. A joint material is filled between the tuyere of the tundish and the dipping nozzle so that molten steel does not enter and an accident such as a leak of molten metal does not occur. This joint material is usually composed of mortar that has been kneaded with water, and apply this mortar to the joint surface with the tuyere of the dipping nozzle with a trowel,
Next, the immersion nozzle is attached to the tuyere, and the tundish and the immersion nozzle are preheated to a predetermined temperature to form a dry joint. By this joint,
The tundish and the immersion nozzle are joined together, and the gap between them is sealed.

Tundish of the continuous casting process
Since the final step between the immersion nozzle and the mold is the final step in which the molten steel solidifies to become a steel material, it is important to prevent contamination of the molten steel. For this reason, the tundish and the dipping nozzle are used as one body, and usually, after casting 5 to 10 charges followed by the same steel type, they were discarded together with the change of steel type. However, it is not preferable in terms of cost to discard and replace the tundish and the immersion nozzle each time the steel type is changed. Therefore, it has been attempted to improve the life of the tundish by improving the lining material of the tundish, improving the residual hot water in the tundish, and improving the slag removal method.

However, while the life of the tundish can be improved considerably, the life of the immersion nozzle is limited and only 5-10 charges can be used. Therefore, it is necessary to be able to replace only the immersion nozzle. This exchange needs to be performed hot from the viewpoints of energy saving, operation loss suppression, and the like. In order to enable such hot exchange of the immersion nozzle, the inventors of the present invention have disclosed in Japanese Laid-Open Patent Publication No. 5-1556.
No. 66 and Japanese Patent Application No. 4-210284 proposed the following joint molding.

That is, this joint molding is formed into a thin wall that fits tightly between the inner peripheral surface of the tuyere and the outer peripheral surface of the dipping nozzle in a tundish. It is composed of a thermoplastic binder such as thermoplastic synthetic resin or pitch, and this joint molding is attached to the tuyere while it is attached to the dipping nozzle, and the joint forming is held by the dipping nozzle. It is characterized in that it is softened by heat and then baked, thereby closing the gap between the tuyere and the dipping nozzle and joining them together.

[0006]

By replacing the dipping nozzle by using this joint formation, it has become possible to continuously operate the hot rotary tundish at 500 charges or more. By the way, in the hot rotary tundish,
After pulling out the soaking nozzle, which had reached the end of its life, a small amount of metal or slag remaining on the bottom of the tundish fell into the tuyere, or the joint formation did not completely peel off, and part of it did not It may remain adhered to the inner peripheral surface, and for this reason, using a tuyere inner peripheral surface cleaning machine or the like, the metal or joint formation on the inner surface of the tuyere is peeled off. At that time, the tuyere refractory is also damaged. That is,
The inner surface of the tuyere is damaged.

Since the damage to the tuyere gradually increases each time the dipping nozzle is replaced, if this is left unattended, a gap between the tuyere and the dipping nozzle will be formed even if the joint forming body is used. There is a high risk that a molten metal will leak from the gap between the tuyere and the dipping nozzle without being completely blocked. For this reason, it is necessary to repair the tuyere refractory after the number of tundish charges exceeds 200. However, in the hot rotating tundish, the tundish cannot be cooled and repaired at room temperature. The repair material must be applied directly to the tuyere of the.

As a repairing method, it is possible to apply mortar, patching material or the like from below the tundish by a method such as iron coating, or to repair by spraying, but the temperature of the tuyere is usually 1000 to 1400
Due to the high temperature of ℃, the repair material at room temperature is not only difficult to attach to the tuyere, but also has a safety problem. Another problem is that it is difficult to restore the tuyere to its original size by applying a uniform thickness regardless of whether it is a trowel coating method or a spraying method. In particular, the ironing method doubles this difficulty. If the accuracy of the repaired surface is poor, a problem arises in that the dipping nozzle equipped with the joint forming body is caught in the tuyere and cannot be inserted, for example.

The present invention has been made in view of the above problems of the prior art, and an object of the present invention is to provide a method for easily, accurately and safely repairing the tuyere of a hot rotary tundish. is there.

[0010]

The present invention is a method for repairing a tuyere formed at the bottom of a tundish for inserting a submerged nozzle, the outer peripheral surface of which substantially conforms to the inner peripheral surface of the tuyere before use. After applying the kneading clay-like repair material to the outer peripheral surface of the jig formed as described above, insert the jig into the tuyere and then pull it out to attach the repair material to the damaged part of the tuyere. Next, a feature is that an immersion nozzle equipped with a joint molding having a shape that fits into the tuyere is inserted into the tuyere.

Further, according to the present invention, a repair material is attached to an outer peripheral surface of a joint forming body having an inner peripheral surface formed into a shape to which a submerged nozzle is fitted, and the repair material is attached to the submerged nozzle and inserted into the tuyere. Also includes.

[0012]

DETAILED DESCRIPTION OF THE INVENTION In the method of claim 1, a jig is used whose outer periphery is formed into a shape that substantially matches the inner peripheral surface of the tuyere before use, and the outer peripheral surface of the jig is formed into a kneaded clay shape. Repair by attaching a repair material, inserting it into the tuyere, and then pulling it out. The amount of repair material attached depends on the degree of damage to the inner surface of the tuyere. Generally, the width and length should be the same as the damaged area, and the thickness should be about 1.5 times the depth of the damaged area. Is appropriate.

The repair material used may be so-called amorphous refractory material such as refractory mortar, castable refractory material, plastic refractory material, spray refractory material, patching material and coating material, and the material is not particularly limited. Therefore, as the aggregate of the refractory material, alumina, magnesia,
Various materials such as silica, zirconia, zircon, titania, bauxite, shale and wax stone can be used. Carbonaceous materials such as phosphorus-like graphite, earth-like graphite, and coke may be used together. It is also possible to use a mixture of two or more refractory materials.

In general, the refractory material preferably has the same composition as that of the nozzle refractory and tuyere refractory to be joined.
Regarding the particle size of the aggregate, a finer one is preferable in order to enter the narrow joints during filling, and it is suitable to mainly make fine particles of about 1 mm or less. As the binder, an inorganic binder such as water glass (sodium silicate), sodium phosphate, or alumina phosphate, an organic binder such as phenol resin, or the like is used in combination with the aggregate.

An appropriate amount of water is added to the aggregate and the binder to make a kneading clay-like repair material, which is attached to the outer peripheral surface of the jig in a required amount, and then the jig is inserted into the tuyere. To do. Then, the damaged surface of the tuyere is filled with the repair material, and since the tuyere is usually 1000 to 1400 ° C., the repair material is baked on the tuyere. When the jig is pulled out from the tuyere, the damaged part of the tuyere is filled with a repair material, and the tuyere is restored to the same inner peripheral surface shape as before use. Then, when the joint formation is attached to the preheated dipping nozzle and inserted into the tuyere, the joint formation is softened and then baked, so that the gap between the tuyere and the dipping nozzle is surely secured. Will be blocked.

Therefore, until the life of the tundish is exhausted, the immersion nozzle can be repeatedly replaced and the operation can be continued without causing a water leak accident. The dipping nozzle may be attached to the tuyere and then preheated. The method of claim 2 is a simple one in which a jig is not used and a joint forming body having a repair material adhered to the outer peripheral surface thereof is put on a dipping nozzle and then inserted into a tuyere. The immersion nozzle is preheated to such an extent that the joint forming body can be softened.

Japanese Patent Application Laid-Open No. 5-155666 and Japanese Patent Application No. 4-2
When the joint forming body proposed in No. 10284 is used, it has the property of being softened and plasticized by the heat retained by the immersion nozzle, so that it is filled in the regular joint gap between the tuyere and the immersion nozzle. . At the same time, the damaged portion of the tuyere is filled with the repair material, and the repair material is baked on the tuyere, so the repair is completed at the same time.

The specific material of the repair material is the same as that described in the embodiment of claim 1.

[0019]

Embodiments of the present invention will now be described with reference to the drawings. [Embodiment 1] FIGS. 1 and 2 are views showing this embodiment,
Reference numeral 1 is a tundish, reference numeral 2 is a tundish 1
A tuyere brick as an example of a tuyere refractory in
Indicates a tuyere. The tuyere 3 is formed in a tapered shape that spreads downward.

Reference numeral 4 indicates a jig with a handle, and the outer peripheral surface of the jig 4 is formed so as to fit almost exactly on the tuyere 3 of the tuyere brick 2 before being manufactured and used. Code 5
Indicates a repair material. 230 tundish 1 of hot rotation
When the immersion nozzle was removed after removing the immersion nozzle by continuous use, the width of the inner surface of the tuyere 3 was reduced to 10 mm as shown in FIG.
The damage 6 having a size of 0 mm and a maximum depth of about 10 mm was formed in a band shape.

As the repair material 5, alumina powder having a particle diameter of 0.5 mm or less is used as an aggregate, 8% of sodium silicate as a binder and 20% of water are added to 100% of the aggregate, and these are stirred by a universal mixer. Manufactured by. As shown in FIG. 1, the repair material 5 is applied to the outer peripheral surface of the jig 4 with a width of 100 mm,
After adhering all over the circumference with a thickness of 15 mm, as shown by the arrow in FIG.
It was inserted tightly and then pulled out.

Then, the damage 6 of the tuyere 4 was filled with the repair material 5 and baked, and the inner peripheral surface of the tuyere 4 had the same inner peripheral surface shape as before the damage. Next, as shown in FIG. 2, the joint forming member 8 was attached to the preheated dipping nozzle 7 and was inserted into the tuyere 3. Then, as shown in FIG. 3, since the joint forming body 7 is softened by the heat of the dipping nozzle 7 and the heat of the tuyere brick 2 and then baked,
The gap between the tuyere 3 and the dipping nozzle 7 is tightly closed, and the dipping nozzle 7 is joined to the tuyere brick 2.

The above method is repeated for about 40 charges or every time the repair material 6 is stripped off during cleaning of the tuyere inner peripheral surface, and the immersion nozzle 7 is replaced, so that the tundish 1 of 500 times can be run without accident such as hot water leak. Got durable. [Example 2] When the tundish 1 of hot rotation was continuously used for 235 times and then the immersion nozzle was pulled out to remove the metal and the like from the tuyere 3, the inner circumference of the tuyere 3 was shown as shown in FIG. A damage 6 having a width of 100 mm and a maximum depth of about 10 mm was formed on the entire surface.

The repair material 5 of this embodiment is composed of 50% magnesia powder having a particle diameter of 0.5 mm or less and 50 alumina powder as an aggregate.
%, To which 25% of liquid phenolic resin was added as a binder, and these were stirred by a universal mixer for purification. As shown in FIG. 4, this repair material 5 is 100 mm wide × 15 m on the outer periphery of the joint forming body 8.
After being attached to a thickness of m, the dipping nozzle 7 preheated to 1000 ° C. was covered, and in that state, the tuyere 3 at 1000 ° C. was inserted and fitted. Then, the repair material 5 is filled in the damage 6 and baked on the tuyere 3 to repair the damage 6. At the same time, the joint forming body 8 is softened and then baked, so that the tuyere 4
The gap between the soaking nozzle 7 and the soaking nozzle 7 was sealed, and the soaking nozzle 7 was joined to the tuyere brick 2, resulting in a state similar to that shown in FIG.

This method is used for about 50 charges or repair material 6
By repeating the replacement of the dipping nozzle 7 every time it peels off when cleaning the inner surface of the tuyere, there is no accident such as hot water leak.
I got the durability of tundish 1 of 00 charge. In the case of the second embodiment, since the time required for the repair is included in the replacement time of the immersion nozzle 7, the time does not substantially increase.

[0026]

According to the present invention, in any of claims 1 and 2, compared to the conventional method in which an operator directly applies a trowel, a precise shape similar to that of a tuyere before use is obtained. -Repair to the size can be done easily and surely in a short time. Further, since the worker does not have to work near the tuyere of high temperature, the safety of work can be remarkably improved.

According to the second aspect of the present invention, there is an advantage that the working efficiency can be further improved because the submerged nozzle is replaced and refitted and the damaged portion of the tuyere is repaired at that time.

[Brief description of drawings]

FIG. 1 is a diagram showing a first half of a process according to a first embodiment of the present invention.

FIG. 2 is a diagram showing the latter half of the process of Example 1 of the present invention.

FIG. 3 is a diagram showing a state in which the immersion nozzle has been replaced.

FIG. 4 is a diagram showing a procedure of a second embodiment of the present invention.

[Explanation of symbols]

 1 Tundish 2 Tuyere brick 3 Tuyere 4 Jig 5 Repair material 6 Damaged site 7 Immersion nozzle 8 Joint formation

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Yoichi Yokoyama, 1-3-1, Niihama, Arai-cho, Takasago, Hyogo Prefecture Harima Ceramics Co., Ltd. (72) Masami Nishikawa 1-3-1, Niihama, Arai-cho, Takasago, Hyogo Prefecture Harima Ceramic Co., Ltd.

Claims (2)

[Claims] 1. A method for repairing a tuyere opened at the bottom of a tundish for inserting a submerged nozzle, the outer circumferential surface being formed so as to substantially match the inner circumferential surface of the tuyere before use. After applying the kneading clay-like repair material to the outer peripheral surface of the jig, insert the jig into the tuyere and then pull it out to attach the repair material to the damaged part of the tuyere, and then A method of repairing a tundish tuyere, which comprises inserting an immersion nozzle equipped with a joint molding having a shape fitting into the mouth into the tuyere. 2. A method for repairing a tuyere opened at the bottom of a tundish for inserting a submerged nozzle, the outer peripheral surface of a thermoplastic joint forming body having an inner peripheral surface formed into a shape to which the submerged nozzle fits. A method of repairing a tundish tuyere, characterized in that a repair material is attached to a surface, the dipping nozzle is attached to the surface, and the tundish tuyere is inserted.