JPS5927272B2 - Molten metal container - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a container for containing molten metal, particularly molten steel, and more particularly to a container in which a worn lining material can be quickly repaired and the life of a durable lining refractory brick can be extended. It is something.

Molten steel storage containers, such as tanditshu, are used to stabilize the flow of molten steel when pouring it into the mold during continuous casting of molten steel, equalize the temperature of molten steel, and float and separate nonmetallic inclusions in molten steel between the ladle and the mold. This tundish has a durable refractory brick lining with a lining made of monolithic refractory material, and a durable refractory brick lining with fireproof insulation on the inner surface. The lining is made of a consumable lining material formed in the form of a flexible board.

The former is generally castable as a monolithic refractory, and is usually constructed to a thickness of 20 to 30 mm, depending on the location, to a thickness of 50 mm, on top of refractory bricks.Prior to use, the monolithic refractory is heated at 1100 to 1200℃ to dry it. Preheat for several hours.

The advantages are that material costs are low (particularly in converter factories, excess COG gas can be used for preheating), that the service life is long and can be used for about 10 consecutive castings, and that the thickness of the monolithic refractory layer is low during construction. can be increased to a certain extent, thereby making it possible to extend the service life more or less.

The disadvantage is that after using ζ, bare metal remains in the tundish, making it extremely difficult to repair the monolithic refractory layer that has been eroded by the molten steel.

That is, this metal is removed by oxygen lancing, but it takes a very long time to remove it.

Next, since the monolithic refractory and the refractory bricks undergo a solid phase reaction during hot use of the tundish and become stuck together, it becomes even more difficult to remove the monolithic refractory.

In addition, the refractory bricks will need to be replaced in areas with strong adhesion.

Furthermore, when oxygen is used in metal removal work, fumes and dust are generated, creating a very poor working environment.

In the latter type of tundish, the consumable lining material formed into a fire-resistant and heat-insulating board is generally made of fire-resistant aggregate such as silica sand, fibrous material such as pulp or asbestos, and binder such as phenolic resin or water glass. Usually, a board with a thickness of about 50 mm is used, but it does not require much preheating before use.

The advantage of fireproof and insulating boards is that they have better insulation properties than monolithic refractories, so preheating before use is almost unnecessary.

Secondly, the board and refractory bricks do not stick together, so repairs are easy.

Furthermore, due to the above reasons, there is also the advantage that the durable refractory brick has a long lifespan.

The disadvantage is that because it uses a board, its service life is short (about 3 to 5 continuous castings).

Another disadvantage is that the board is expensive.

In particular, these drawbacks can be avoided if continuous casting is performed more than 10 times in the future.
This is a major drawback in steel plants where excess converter gas can be used for preheating.

For example, the present invention makes use of the advantages of the former type of tundish as it is, and also quickly removes the bare metal inside the tundish, which is a disadvantage, and prevents the monolithic refractory from sticking to the refractory brick, making it easy to repair. As a result, it is an object of the present invention to provide a container for molten metal, such as a tundish, which eliminates all troubles associated with base metal adhesion and adhesion of refractories to bricks, and which allows repair work to be carried out on a low floor.

Therefore, the container of the present invention for achieving the above object includes a metal outer box (skin), a durable lining of refractory bricks adjacent to the outer box, and an organic fiber O12 adjacent to the refractory bricks.
~25% (rolling wheels), refractory powder 75-99.8% (rolling wheels)
It is characterized in that it is composed of a coating layer having a coating thickness of 1 to 5 mm by applying a slurry made of the same, and a consumable lining material made of a monolithic refractory adjacent to the coating layer.

The present invention will be explained in detail below.

Fig. 1 shows an example in which the present invention is applied to a tundish.The inner surface of a metal outer box (skin) 1 is lined with durable refractory bricks 2, and the inner surface of the refractory bricks 2 is lined with organic fibers and fireproof. A slurry made of powder is applied to form a coating layer 3 having a thickness of 1 to 5 mrIL, and the inner surface of the coating layer 3 is further formed with a consumable lining material 4 made of a monolithic refractory.

Note that 5 indicates a nozzle for pouring out molten steel.

Of course, the present invention is applicable not only to tundishes but also to other containers for storing molten metal, such as ladles.

In the present invention, between the firebrick and the monolithic refractory, 1
Since the above-mentioned coating layer with a thickness of ~5 cm is interposed, it prevents the refractory bricks and monolithic refractories from causing a solid phase reaction and sticking together during hot use, and prevents the monolithic refractory layer from peeling off. Removal can be facilitated.

For this purpose, it is preferable that the coating layer maintains a brittle bond without causing a melt or solid phase reaction and sticking to the refractory brick or monolithic refractory at the operating temperature of the container. .

Furthermore, when a coating layer of 1 to 5 m71 L is formed on the inner surface of a refractory brick, and furthermore, a monolithic refractory is applied on top of the coating layer, the coating layer must not be damaged.

From the above point, the coating layer consists of the following elements.

In other words, the organic fibers are blended to prevent the container from causing a solid phase reaction and sticking during hot use, and to make the coating layer brittle after use, making it easier to remove the monolithic refractories. Pulp,
Beaten waste paper etc. are suitable.

In addition, the composition ratio of organic fibers was set at 0.2 to 25% (rolling wheel) because if it is less than 0.2%, the effect will decrease, and if it exceeds 25%, a large amount of gas will be generated, making it unusable. This is because it is unsuitable, and also because the strength of the coating layer decreases, and it is unfavorable in relation to the blending ratio of the refractory powder.

The particle size of the refractory powder is preferably 200 mesh or less, and 1500 mesh or less, from the viewpoint of slurry stability and coating layer strength.
Silica sand, alumina, magnesia, which can withstand high temperatures of °C.
Zircon etc. are suitable.

The composition ratio was set at 75-99.8% (rolling wheels) because
This is because if it is less than 75%, the fire resistance of the coating layer decreases, and if it exceeds 99.8%, it is unsuitable due to the blending ratio of organic fibers.

The composition described above may be made into a slurry with water and applied, but if polyvinyl alcohol (P-VA), starch paste, etc. are added to this, a slurry with good dispersibility can be obtained.

The reason why the thickness of the coating layer is set to 1 to 5 mm is that if it is less than 1 mm, it is difficult to obtain the desired effect, and if it is thicker than 5 mm, the effect will only become saturated and the strength of the coating layer will decrease. by.

Next, examples of the present invention will be shown.

Example 1 A blended composition of 75% silica sand (rolling wheel) (particle size 200 mesh or less) and 25% pulp containing 98% SiO2 was made into a slurry with an aqueous solution containing 0.1 wt% PVA, and the fire resistance (SK) was 30. #On the inner surface of the refractory brick, 2
Spray it thickly and then add irregular shape resistance.

After installing 5K30# castable as a thick item, COG
A tundish was prepared by preheating with gas at 1200°C for 4 hours.

After using this for 10 consecutive castings, the base metal was hoisted up and removed using a hook and crane without oxygen lancing, and the part of the castable to which the base metal was attached was removed along with the base metal at the coating layer. Ta.

In addition, other parts to which the base metal was not attached could be easily removed from the coated layer, so the repair was very easy.

However, in conventional tundishes without the coating layer of the present invention, the castable and refractory bricks stick together, which takes time to repair, and the refractory bricks are also partially damaged, requiring replacement. .

Example 2 A blended composition containing 99.8% magnesia powder (transfer) and 0.2% beaten product of waste paper,
A slurry made with water was sprayed to a coating thickness of 5 mm to make a tundish under the same conditions as in Example 1. After 8 consecutive castings, the tundish was turned over and the base metal and castable were completely removed from the coating layer. I was able to peel it off.

As described above, when the molten metal container of the present invention is used, the base metal and castable can be easily removed after the casting work is completed, and repairs can be performed quickly and easily.

Moreover, various effects can be expected such as the lifespan of the durable refractory bricks being significantly extended.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a specific example of the present invention. 1...Outer box, 2...Firebrick, 3...
... Coating layer, 4... Monolithic refractory, 5...
····nozzle.

Claims (1)

[Claims] 1. A metal outer box, a durable lining of refractory bricks adjacent to the outer box, and 0.2 organic fibers adjacent to the refractory bricks.
~25% (rolling wheels), refractory powder 75-99.8% (rolling wheels)
A molten metal storage container comprising: a layer coated with a slurry of 1 to 5 TnrIL to a coating thickness of 1 to 5 TnrIL; and a consumable lining material made of a monolithic refractory adjacent to the coated layer.