JPH06335765A - Structure for filling plugging material into nozzle hole in molten metal vessel - Google Patents

Abstract

PURPOSE:To prevent the solidification caused by invasion of molten steel into a plugging material filled into a nozzle hole in a ladle and improve natural hole opening ratio. CONSTITUTION:The plugging material 10 in the upper layer filled into the nozzle hole is used to basic fine grains, and the plugging material 8 in the lower layer is used to basic coarse grains. As the plugging material 10 in the upper layer is the fine grains, the invasion of the molten metal can be prevented and the formation of solidified layer can be prevented. As the plugging material 10 in the lower layer is the coarse grains having large void volume, the heat insulation is good and the drop of molten steel temp. is prevented and the formation of solidified layer can be restrained. As the plugging materials 8, 10 are basic material and do not badly influence to the basicity of tundish slag, the cleanliness of the molten steel is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a filling structure for a nozzle hole provided in a molten metal container such as a ladle and a tundish.

[0002]

2. Description of the Related Art A sliding nozzle is generally used as a molten metal flow rate adjusting device provided in a molten metal container such as a ladle and a tundish. As shown in FIG. 5, this sliding nozzle comprises an upper nozzle 1 set in a nozzle brick 4, a fixed plate 2 fixed to an iron skin 5, and a slide plate 3, and the slide plate 3 is slid hydraulically or electrically. The flow of the molten metal in the molten metal container is adjusted or stopped by.

However, when a sliding nozzle is used, the molten metal infiltrates into the nozzle hole in the early stage of steel receiving, and the temperature in the nozzle hole is lower than the temperature in the ladle or tundish, so that the molten metal solidifies. However, there is a problem that the molten metal is prevented from flowing out even if the slide plate 3 is slid. Therefore, conventionally, the filling 6 is filled in the nozzle holes of the upper nozzle 1 and the fixing plate 2 to prevent solidification due to the invasion of the molten metal, and the filling 6 together with the molten metal is opened when the nozzle plate is opened by sliding the slide plate 3. Means for spillage are taken.

For example, the filling of a ladle nozzle when pouring molten steel in a ladle into a tundish is generally made of river sand or the like as disclosed in JP-A-57-58973 and JP-A-1-133663. Although natural silica sand is used, it is discharged into the tundish or mold when the ladle nozzle is opened. For example, silica sand discharged from the ladle nozzle into the tundish floats in the molten metal and is absorbed by the slag on the upper surface of the tundish. The tundish slag is adjusted to be basic to keep the molten steel clean, but the basicity decreases when silica sand is mixed. In continuous casting, since multiple ladles are used per tundish, the basicity decreases as the ladles change. Therefore, the harmful components captured in the slag on the upper surface of the tundish are
Due to changes in the slag composition, it moves into the molten steel and the cleanliness of the molten steel deteriorates.

Further, the change in the slag composition accelerates the reaction between the tundish refractory material and the slag, thereby shortening the refractory life. In the case of natural sand, it is difficult to control the water content, angle of repose, and particle size distribution. Yes, it may not flow out spontaneously when the nozzle is opened. If it does not spontaneously flow out, it will be opened by dissolving the solidified layer with oxygen,
The oxide generated at this time contaminates the molten steel. Further, in continuous casting, continuous operation will be interrupted unless natural outflow occurs.

[0006]

According to the prior art, when an acidic oxide mainly composed of silica sand is filled in a ladle nozzle as a filling, a tundish slag which is adjusted to be basic when discharged into a tundish is prepared. The basicity decreases and the cleanliness of molten steel deteriorates. Further, in the case of natural sand, since it is difficult to control the water content, angle of repose, and particle size distribution, a sintered layer or solidified layer is formed on the contact surface with molten steel at the top of the ladle nozzle,
The filler and molten steel filled in the ladle nozzle may not spontaneously flow out when the nozzle is opened. Therefore, oxygen is blown into the nozzle to open the hole by melting the solidified layer, which causes problems such as contamination of the molten steel by the generated oxide and interruption of continuous operation.

It is an object of the present invention to provide a filling structure for a nozzle hole of a molten metal container which can solve the problems of the prior art.

[0008]

In order to achieve the above object, the present invention provides a filling hole filling structure for a molten metal container nozzle hole having a sliding nozzle in which the nozzle hole is filled with two kinds of filling divided into upper and lower layers. , Grain size of upper layer is 0.5-5
mm is 90% or more of fine-grained basic refractory filling, and the lower layer has a grain size of 5 to 20 mm is 90% or more of coarse-grained basic refractory filling, and the upper layer thickness is 1/100 of the nozzle hole height. It is a filling structure for a nozzle hole of a molten metal container, characterized in that it is set to 5 to 1/10.

In the present invention, it is preferable that the upper layer padding and the lower layer padding be separated using a thin iron plate.

[0010]

In the case of the present invention, since the filling material to be filled in the ladle nozzle uses a basic material, for example, granules of magnesia or light burned dolomite, the basicity of the tundish slag is not lowered. Therefore, the cleanliness of the molten steel is not deteriorated, the reaction between the tundish refractory and the slag is suppressed, and the refractory life is not reduced.

The filling of the filling material into the ladle nozzle is divided into two layers in the height direction of the nozzle hole, and the upper layer is filled with fine-grained filling material to prevent the infiltration of molten steel, and the lower layer is filled. For the purpose of heat insulation, fill large-sized filling with a large porosity. Compared to silica sand, magnesia and light-burning dolomite have high fire resistance and are difficult to sinter. Furthermore, since there is a heat insulating layer in the lower layer, no solidified layer is generated.

The particle size of the filling material in the upper layer is 0.5 to 5 mm and the particle size distribution is 90% or more.
It is preferable to fill the one having good fluidity of 50 degrees or less. Outside this range, the penetration depth of molten steel increases,
In addition, there is a risk that it is difficult for the filler to spontaneously flow out. In addition, the filling of the lower layer has a particle size distribution of 5 to 20 mm 90% or more,
Similarly, the angle of repose is preferably 50 degrees or less. If it is out of this range, the thermal conductivity will increase, a solidified layer of molten steel will be generated, and it will be difficult for the filler to spontaneously flow out.

Further, the height of the upper layer is 1 / the height of the nozzle hole.
It must be 5 to 1/10. This is because if it is larger than ⅕, the lower coarse particle layer becomes thin and the degree of heat insulation becomes insufficient, and if it is smaller than 1/10, intrusion of molten metal cannot be sufficiently prevented. Further, in order to prevent the fine grain filling of the upper layer from entering between the coarse grain filling of the lower layer, it is desirable to separate them with a thin iron plate.

In order to separate the upper layer and the lower layer, as shown in FIG. 2, a cylindrical basic container 7 having a size substantially equal to the inner diameter of the nozzle hole is first filled with a coarse-grained basic refractory filling material 8 for forming the lower layer. A thin iron plate 9 having a thickness of 1.0 mm or less is covered thereover, and a fine-grained basic refractory filling 10 forming an upper layer is filled on the thin iron plate 9 to separate the lower layer and the upper layer. preferable. The material of the cylindrical container 7 is, for example, paper and is inserted into the nozzle hole. When the molten metal is injected, the cylindrical container 7 made of paper inserted in the nozzle hole is burned, and the coarse particle filler 8 in the lower layer and the fine particle filler 10 in the upper layer are filled in the nozzle hole.

[0015]

EXAMPLE To form a filling structure for a ladle nozzle according to the present invention, first, as shown in FIG. 1, a ladle nozzle hole formed by a fixed plate 2 closed by a slide plate 3 and an upper nozzle 1 is formed. First, a basic refractory filling material 8 having a coarse-grained magnesia as a main component for forming a lower layer is filled. Next, the surface of the lower layer 8 is covered with a thin iron plate 9 having a thickness of 0.3 mm, and the basic refractory filling material 10 mainly composed of fine-grained magnesia forming the upper layer is formed thereon.
To fill.

As described above, the coarse grain filling 8 forming the lower layer, the thin iron plate 9 and the fine grain filling 10 forming the upper layer may be separately charged in the ladle nozzle hole at the site. As described above, if the coarse-grained basic refractory filling 8 and the fine-grained basic refractory filling 10 separated by the metal foil are filled in the cylindrical container 7 made of paper as described above, it can be set in the nozzle hole with one touch. You can

According to the present invention, even if the basic refractory filling material filled in the ladle nozzle enters the tundish, the slag properties in the tundish do not change, so that silica sand is used as shown in FIG. The cleaning degree of molten steel can be improved as compared with the example. In addition, since the upper layer is filled with fine-grained basic refractory filler 10, it is possible to prevent the formation of a sintered layer and the formation of a solidified layer due to the infiltration of molten steel, and the lower layer has a high porosity and heat insulation. Since the basic refractory filling material 10 having a good grain size is filled, it is possible to prevent the action of accelerating the solidification of the molten steel due to the temperature decrease. As a result, as shown in FIG. 4, according to the present invention, the natural aperture ratio due to the opening operation of the sliding nozzle can be improved as compared with the conventional example.

[0018]

As described above, according to the present invention, since the basic material is used as the filling of the nozzle hole, the slag basicity in the molten metal container is not lowered, so that the cleanliness of the molten metal can be improved. it can. In addition, since the filling has an upper and lower two-layer structure consisting of an upper layer of fine grains and a lower layer of coarse grains, the formation of a sintered layer and a solidified layer on the molten metal contact surface is suppressed, so that the filling is discharged from the nozzle hole. Can be facilitated and the natural porosity can be improved.

[Brief description of drawings]

FIG. 1 is a sectional view showing a filling structure for a nozzle hole of a molten metal container according to the present invention.

FIG. 2 is a perspective view schematically showing a filling structure using the cylindrical container of the present invention.

FIG. 3 is a graph showing a comparison between molten steel cleanliness indexes of the present invention and a conventional example.

FIG. 4 is a graph showing a comparison of the natural hole opening rate of the present invention and a conventional example.

FIG. 5 is a cross-sectional view showing a conventional filling structure for a nozzle hole of a molten metal container.

[Explanation of symbols]

 1 Upper nozzle 2 Fixed plate 3 Slide plate 4 Nozzle receiving brick 5 Iron skin 6 Filling (conventional) 7 Cylindrical container 8 Coarse grain filling 9 Thin iron plate 10 Fine grain filling

Claims (2)

[Claims] 1. A filler filling structure of a molten metal container nozzle hole having a sliding nozzle in which two kinds of fillers are separately filled in upper and lower two layers into a nozzle hole, and the upper layer has a grain size of 0.5 to 0.5.
5mm is 90% or more of fine-grained basic refractory filling, the lower layer is 5-20mm of coarse-grained basic refractory filling of 90% or more,
A filling filling structure for a nozzle hole of a molten metal container, wherein the thickness of the upper layer is set to 1/5 to 1/10 of the height of the nozzle hole. 2. The filling filling structure for a nozzle hole of a molten metal container according to claim 1, wherein the filling of the upper layer and the filling of the lower layer are separated by using a thin iron plate.