JPH09194927A - Plug for blowing gas - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the intrusion of molten steel into a gas passage and to improve the durability of a plug by combining in zigzag at least four pieces of bar-like refractories having square cross section and housing these refractories into a plug outer shell body. SOLUTION: The bar-like refractories 20 composed of dense refractory and having square cross section are combined in zigzag arrangement by shifting in each 1/2 width and the bar-like refractory assembled body 20A assembled in such way is housed in the plug outer shell body 21 to constitute the plug for blowing the gas. By this constitution, a part formed as the gas passage is fine cross-sectional area per one refractory and therefore, the intrusion of the molten steel is scarcely caused and the remarkable extension of the service life can be expected. Further, since the adjustment of flow rate of the gas can be executed by selecting the assembled number of the bar-like refractories 20, the plug having different flow rate of the gas without changing the outer size of the plug can be obtd.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a gas injection plug provided for injecting various gases into molten steel in a steelmaking process.

[0002]

2. Description of the Related Art In a molten metal container such as a ladle and a tundish used in a steelmaking process, various gases are blown to stir the molten steel inside.

In order to inject this gas, a gas injection plug 2 is usually provided at the bottom of a molten metal container 1 as shown in a partial cross section in FIG. Gas is blown into the molten steel in the molten metal container 1.

As shown in FIG. 10, a conventional gas injection plug 2 has a porous refractory material 5 loaded in a frustoconical metal case 4 having a lower end to which a gas supply pipe 3 is connected. A porous plug in which the outer periphery of the metal case 4 is covered with a dense refractory material 6, as shown in FIGS. 11 and 12.
The rectangular plate-like refractories 7, 7 ... Are superposed on each other, and the slits 8, 8 ...
A slit-type plug that allows gas to be blown in through the dense refractory 9 as shown in FIG.
0 ... Penetrate vertically, and these pores 10, 10 are formed.
Porous plugs that blow gas through them are used. 11 to 13, members common to those in FIG. 10 are designated by the same reference numerals. In FIG. 9, 11 is an iron skin of a molten metal container, 12 is a sleeve brick, 13 is an upper brick, 14 is a lower brick, 15 is a furnace bottom refractory, and 16 is a holding brick.

[0005]

However, in the porous plug (FIG. 10), the metal is likely to adhere to the tip surface of the porous refractory 5 to make it difficult to blow the gas. Porous refractory 5 after cleaning and removal
However, there is a problem that the useful life is lost at an early stage. In addition, when blowing a large amount of gas, a large-scale porous refractory is used or a coarse porous refractory is used to deal with it. There is a problem of becoming.

In the slit type plug (FIGS. 11 and 12), the number of the plate-shaped refractories 7, 7 ... Used is limited, so that the number of the slits 8, 8 ... Is naturally limited, so that a predetermined gas blowing is performed. The slit width must be increased in order to obtain the amount of intrusion, but if this is done, the intrusion of the ingot will be obstructed and the gas blow-in will be obstructed, and there will be the problem that continuous use will not be possible. As in the case described above, when the above is washed, melting loss occurs and the service life is shortened. Especially in the case of using the plate-like refractories 7, 7, ...
2, the thickness of the dense refractory material 6 at the corners of the plate-shaped refractory material 7 becomes small, and cracks are easily generated from this portion, which is one of the causes of shortening the service life. If the plate refractories 7, 7 ... are thinned and the number of slits 8, 8 ... is increased in order to increase the amount of gas blown, the strength of the plate refractories 7, 7 ,. If the gas flow characteristics are to be changed in addition to cracking and chipping, the entire gas injection plug must be changed, and the size and shape of the plug must be changed. There is the inconvenience that the relationship with

In the pore type plug (FIG. 13), it takes a lot of work to pierce the dense refractory material 9 with a large number of pores 10, 10 ..., The cost is high, and particularly, the gas injection amount is increased. Has to increase the number of pores, resulting in higher cost.
Since the pores 10, 10 ... Generally have a diameter of 1.0 mm or less and the required number of pores is 20 to 60,
There is a problem that the gap between the pores 10 is significantly narrowed, cracks are likely to occur, and cracks are likely to occur. Further, if the inner diameter of the pores 10, 10 ... Is increased to increase the gas flow rate, the intrusion of the metal is likely to occur as in the case of the slit plug (FIGS. 11 and 12). Will bring.

In addition to the above, there is also a type in which a slit is formed by an irregular refractory material, but since it has a slit, it also has the same problems as those of the slit type plug.

[0009]

SUMMARY OF THE INVENTION According to the present invention, the cross-sectional area of one gas passage is reduced to reduce the intrusion of molten steel, the service life is extended, and the gas flow rate can be easily adjusted and reduced. An object of the present invention is to provide a gas blowing plug that can be obtained at a cost. As a means for solving the problem, at least four rod-shaped refractories having a square cross section and a predetermined length are used. This is because the rod-shaped refractory aggregates were combined in a staggered arrangement and housed in the plug shell.
And preferably, a protrusion is provided on one side surface of the rod-shaped refractory which is in contact with each other, and a concave portion corresponding to the convex portion is provided on the other side surface, and the convex portion and the concave portion are fitted and combined with each other. Is good. In addition, the bar-shaped refractories are chamfered at their corners so that the corners of the bar-shaped refractories serve as gas passages, and at least 1 in the longitudinal direction of the surfaces of the bar-shaped refractories contacting each other.
A structure having grooved grooves, a structure in which the surface roughness of the surfaces of the rod-shaped refractory material in contact with each other is in the range of 25 to 100 in terms of arithmetic mean roughness (Ra), and a fire resistance between the surfaces of the rod-shaped refractory material in contact with each other The plug outer shell body commonly has a dense refractory layer that surrounds the rod-shaped refractory assembly, including a configuration in which a gas passage is formed by sandwiching paper.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the embodiments shown in the drawings.

FIG. 1 shows a cross section of an embodiment of a gas injection plug according to the present invention, and FIG. 2 shows the same plane.
Rod-shaped refractory 20,2 with a rectangular cross-section made of dense refractory
0 ... Are offset from each other by 1/2 and are combined in a zigzag arrangement, and the rod-shaped refractory aggregate 20A thus assembled is housed in the plug outer shell body 21 to form a gas injection plug.

The rod-shaped refractory material 20 has a dimension of one side in the cross section of 5 to 25 mm and a rectangular rod shape with an aspect ratio of 1: 2, preferably 1: 1.
It is preferably a square cross section. Also rod-shaped refractory 2
The material of No. 0 may be any material that is not easily melted by molten metal, and for example, materials such as high alumina, alumina carbon, magnesia, magnesia chrome are used.

In the embodiment shown in FIG. 1, the plug outer shell 21 has a frustoconical metal case in which the gas supply pipe 3 is connected to the center position of the bottom 4a as in the conventional case. 4, a porous refractory material 22 having a trapezoidal cross-section is inserted into the inner bottom portion, and the rod-shaped refractory aggregate 20A is placed upright on the upper surface of the porous refractory aggregate 20A. A dense refractory material 6 is filled between the inner peripheral surface of the metal case 4. The outer periphery of the metal case 4 is also surrounded by the dense refractory material 6.

With the above structure, the rod-shaped refractories 20, 20 ...
Since the gaps are gathered in a staggered arrangement, the gaps between them serve as gas passages and the gas supplied from the gas supply pipe 3 passes through the porous portion in the porous refractory 22 from the lower end of the rod-shaped refractory aggregate 20A. It is blown from the upper surface through the gap. The porous refractory material 22 does not necessarily have to be provided, and may be replaced with a means for preventing the rod-shaped refractory materials 20, 20 ... In addition, rod-shaped refractories 20
Even if it is made of a porous refractory, there is no support because the gas is not supplied through the porous portion, and it is not necessarily limited to the dense refractory.

FIG. 3 is a perspective view of a half portion of another embodiment of the present invention, which is used to prevent the rod-shaped refractories 20, 20 ... This means that, as shown in FIG. 4, only one projection is provided on one side surface of the rod-shaped refractory material 20 that is in contact with each other.
However, a concave portion 24 corresponding to the convex portion 23 is formed on the other side surface, and the convex portion 23 and the concave portion 24 are fitted and assembled. As a result, rod-shaped refractory 2
The rod-shaped refractories 20, 20 are restrained by mutually restraining the vertical displacement of the rod-shaped refractories 20, and the biting of the dense refractory 6 filled around the rod-shaped refractory aggregate 20A.
The escape of ... is prevented. The convex portion 23 and the concave portion 24
It is preferable that the shape of the arc is an arc shape as shown in the figure, but the shape is not necessarily limited to this, and the convex portion 23
The number of recesses 24 is not limited to one, and a plurality of recesses 24 may be provided. In FIG. 3, reference numeral 4 represents FIG.
3 shows a metal case having the same structure as the metal case 4 in FIG.

5 to 8 show the rod-shaped refractory assembly 20.
The means for increasing the total cross-sectional area of the gas passages formed by the gaps between the rod-shaped refractories 20, 20, ...

That is, in FIG. 5, chamfers 25 are formed at the corners of the rod-shaped refractories 20 so that the bar-shaped refractories 20 and 20 adjacent to each other are formed.
A gas passage having an isosceles triangular cross-sectional shape is formed between the corners. The chamfer 25 has a C dimension shown in FIG. 5 of about 0.1 to 0.8 mm.

FIG. 6 shows that at least one groove 26 (having an arbitrary cross-sectional shape) is formed in the longitudinal direction of the side surfaces of the rod-shaped refractories 20, 20, ... , 26 are combined to form the gas passage, but the grooves 26 may not necessarily face each other to form the gas passage. The width of this groove 26 is 0.4
The depth is about 10 to 10 mm and the depth is about 0.2 to 0.8 mm.

FIG. 7 shows the surface roughness of the surfaces of the rod-shaped refractories 20, 20, ...
A rough surface 27 is formed to some extent, and a fine gas passage is formed by joining these rough surfaces 27, 27.

Further, in FIG. 8, a refractory paper 28 is sandwiched between the surfaces of the rod-shaped refractories 20, 20 ... Which are in contact with each other, and a gap portion 29 corresponding to the thickness of the refractory paper 28 is formed as a gas passage. Is. In this case, the fireproof paper 28 has a width of 5 to 20 mm and a thickness of 0.2 to 0.4 mm.

In any of the above-described embodiments, the gas passage portion has a very small cross-sectional area per piece, so that there is almost no intrusion of molten steel, and it is expected that the service life will be greatly extended. it can. Further, the gas flow rate can be adjusted by selecting the number of rod-shaped refractories 20 to be used, and plugs having different gas flow rates can be obtained without changing the outer dimensions of the gas blowing plug.

[0022]

As described above, according to the present invention, bare metal infiltration into the gas passage is hardly caused, so that the work of removing the bare metal by oxygen cleaning is remarkably reduced and melting damage of the plug is prevented. The service life can be greatly extended. Moreover, since a dense refractory can be used as the rod-shaped refractory, the durability is remarkably higher than that of the conventional porous refractory that depends on the porosity. Since it is formed, the constituent material is not cracked or broken, and the durability can be improved also from this point. Furthermore, because it is constructed by combining rod-shaped refractories, there is no need to process gas passages with holes or grooves,
The manufacturing cost of the plug can be significantly reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a plan view of the same.

FIG. 3 is a perspective view with a half section showing another embodiment of the present invention.

4 is an enlarged perspective view showing one of the rod-shaped refractories in FIG.

FIG. 5 is a partial plan view showing an example of forming gas passages.

FIG. 6 is a partial plan view showing another formation example of the same.

FIG. 7 is a partial plan view showing still another formation example of the same.

FIG. 8 is a partial plan view showing still another formation example of the same.

FIG. 9 is a partial cross-sectional view showing a portion where a gas blowing plug is provided.

FIG. 10 is a sectional view showing a conventional gas injection plug.

FIG. 11 is a sectional view showing another conventional example.

FIG. 12 is a plan view of the same.

FIG. 13 is a sectional view showing still another conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Molten metal container 2 Gas injection plug 3 Gas supply pipe 4 Metal case 20 Rod-shaped refractory material 20A Rod-shaped refractory material assembly 21 Plug outer shell body 23 Convex portion 24 Recessed portion 25 Chamfer 26 Groove 27 Rough surface 28 Fireproof paper 29 Gap portion

Claims (7)

[Claims] 1. A combination of at least four rod-shaped refractories having a square cross section and a predetermined length in a zigzag arrangement,
A plug for gas injection characterized in that the rod-shaped refractory assembly is housed in a plug shell. 2. A rod-shaped refractory is provided with a convex portion on one side surface which is in contact with each other and a concave portion corresponding to the convex portion on the other side surface, and the convex portion and the concave portion are fitted to each other. The gas injection plug according to claim 1, which is combined. 3. The chamfered corners of the rod-shaped refractory material, and the corner portions of each rod-shaped refractory material are gas passages.
The described gas injection plug. 4. A gas passage having at least one groove in the longitudinal direction of the surfaces of the rod-shaped refractory which are in contact with each other, and a gas passage is formed by the union of the grooves of the rod-shaped refractory which are in contact with each other.
The described gas injection plug. 5. The plug for gas injection according to claim 1, wherein the surface roughness of the surfaces of the rod-shaped refractory material that are in contact with each other is in the range of 25 to 100 in terms of arithmetic average roughness (Ra). 6. The gas injection plug according to claim 1 or 2, wherein refractory paper is sandwiched between the surfaces of the rod-shaped refractory which are in contact with each other, and a gap portion corresponding to the thickness thereof is a gas passage. 7. The gas blowing plug according to claim 1, wherein the plug outer shell body has a dense refractory layer surrounding the rod-shaped refractory assembly.