JP2908303B2 - Gas injection plug - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention 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 or a tundish used in a steelmaking process, various gases are blown to agitate molten steel in the container.

[0003] In this gas blowing, a plug 2 for gas blowing is usually provided at the bottom of a molten metal container 1 as shown in a partial cross section in FIG. The 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 metal refractory 5 loaded in a metal case 4 having a frustoconical shape with a gas supply pipe 3 connected to a lower end thereof. A porous plug in which the outer periphery of a metal case 4 is covered with a dense refractory material 6, as shown in FIGS.
The rectangular plate-like refractories 7, 7 ... are overlapped, slits 8, 8 ... are formed between the joining surfaces thereof, and these slits 8, 8 ...
A slit-type plug into which gas is blown through a plurality of pores 10, 1 in a dense refractory 9, as shown in FIG.
0... Are penetrated vertically.
A porous plug or the like that blows gas through is used. 11 to 13, the same members as those in FIG. 10 are denoted by the same reference numerals. In FIG. 9, reference numeral 11 denotes an iron shell of a molten metal container, 12 denotes a sleeve brick, 13 denotes an upper brick, 14 denotes a lower brick, 15 denotes a furnace refractory, and 16 denotes a holding brick.

[0005]

However, in the porous plug (FIG. 10), the metal tends to adhere to the tip end surface of the porous refractory 5 and it becomes difficult to blow gas. The porous refractory 5
Has a problem in that it is melted down and its useful life is early lost. In the case of injecting a large volume of gas, a large porous refractory or a coarse porous refractory is used to cope with the problem. Problem.

In the slit type plug (FIGS. 11 and 12), the number of slits 8, 8... Is naturally limited because the number of plate refractories 7, 7,. The slit width must be increased in order to obtain the penetration amount.However, this causes problems such as the infiltration of the slab, which hinders gas blowing, and makes it impossible to use the slab continuously. Is washed out as in the case described above, and the useful life is shortened. In particular, in the case of using the plate-like refractories 7, 7,.
As shown by the symbol a in FIG. 2, the thickness of the dense refractory 6 at the corners of the plate-like refractory 7 is reduced, and cracks are easily generated from this portion, which contributes to shortening the service life. If the number of slits 8, 8,... Is increased by thinning the plate-like refractories 7, 7,... In order to increase the gas blowing amount, the strength of the plate-like refractories 7, 7,. If the gas flow characteristics change in addition to cracking and chipping, the entire gas injection plug must be changed, and the size and shape of bricks and hearth refractories However, there is a disadvantage that the relationship with the company will change.

In the case of the porous plug (FIG. 13), it takes time and effort to penetrate the dense refractory 9 with a large number of pores 10, 10... Must increase the number of pores, which further increases the cost.
.. Are generally 1.0 mmφ or less, and the required number of pores is 20 to 60,
There is a problem that the interval between the pores 10 becomes extremely narrow, cracks are easily generated, and chips or the like are easily generated. If the inner diameter of the pores 10, 10,... Is increased to increase the flow rate of the gas, similar to the case of the slit plugs (FIGS. 11 and 12), the infiltration of the metal tends to occur. Will be brought.

[0008] In addition, there is a type in which a slit is formed by an irregular-shaped refractory. However, since the slit is used, the same problem as that of the above-mentioned slit-type plug also occurs.

[0009]

SUMMARY OF THE INVENTION The present invention reduces the cross-sectional area of a single gas passage, reduces the penetration of a molten steel, prolongs the service life, and facilitates the adjustment of gas flow rate. An object of the present invention is to provide a gas injection plug which can be obtained at a low cost. As a solution to this problem, at least four or more rod-shaped refractories having a rectangular cross section and a predetermined length are provided. The rod-shaped refractory assembly is housed in a plug outer shell in a staggered arrangement.
And preferably, a convex portion 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, a corner of the rod-shaped refractory is chamfered, and a corner of each rod-shaped refractory is used as a gas passage.
A configuration having a groove in the form of a bar, a configuration in which the surface roughness of the surfaces in contact with each other of the rod-shaped refractory is in the range of 25 to 100 in arithmetic average roughness (Ra), and a fire resistance between the surfaces in contact with each other of the rod-shaped refractory. The plug shell includes a structure in which a gas passage is formed by sandwiching paper, and the plug outer shell has a dense refractory layer surrounding the rod-shaped refractory assembly in common.

[0010]

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

FIG. 1 shows a cross section of an embodiment of a gas blowing plug according to the present invention, and FIG. 2 shows the same plane.
Rod-shaped refractories 20, 2 made of dense refractories and having a square cross section
0... Are combined in a staggered arrangement with each other being shifted by 互 い に, and the rod-shaped refractory assembly 20A thus assembled is housed in the plug outer shell 21 to constitute a gas blowing plug.

The refractory rod 20 has a rectangular bar shape having a cross-sectional dimension of 5 to 25 mm and an aspect ratio of 1: 2, preferably 1: 1.
Is preferably a square cross section. Refractory rod 2
The material 0 may be any material that is not easily eroded by the molten metal. For example, a material such as high alumina, alumina carbon, magnesia, and magnesia chrome is used.

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

With the above configuration, the rod-shaped refractories 20, 20,...
Are arranged in a staggered arrangement so that the gaps between them become 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. Is blown out from the upper surface through the gap. The porous refractory 22 need not always be provided, and may be replaced with a means for preventing the rod-like refractories 20, 20,... From falling down. In addition, rod-shaped refractory 20
Even if is made of porous refractory, there is no support since gas is not supplied through the porous portion, and the gas is not necessarily limited to dense refractory.

FIG. 3 is a perspective view of a half part of another embodiment of the present invention, which means that the rod-shaped refractories 20, 20,... As shown in FIG. 4, only one protrusion is formed on one side of the rod-shaped refractory 20 which 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. This makes the refractory rod 2
.. Are restrained from each other, and the dense refractory material 6 filled around the rod-shaped refractory assembly 20A is bitten by the rod-shaped refractory materials 20, 20.
… Escape is prevented. The projection 23 and the recess 24
Is preferably an arc shape as shown in the figure, but is not necessarily limited to this shape.
Also, the number of recesses 24 to be provided is not limited to one, and a plurality of recesses 24 may be provided. In FIG. 3, reference numeral 4 denotes FIG.
5 shows a metal case having the same structure as the metal case 4 in FIG.

FIGS. 5 to 8 show the rod-shaped refractory assembly 20.
Means for increasing the total cross-sectional area of the gas passage formed by the gaps between the rod-shaped refractories 20, A of FIG.

That is, FIG. 5 shows that the bar-shaped refractories 20 are formed with chamfers 25 at the corners of the bar-shaped refractories 20, 20.
Are formed so that a gas passage having a cross-sectional shape of an isosceles triangle 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 (arbitrarily shaped in cross section) is formed in the longitudinal direction of the side surfaces of the rod-shaped refractories 20, 20... , 26 are formed to form a gas passage, but the gas passages may be formed without the grooves 26 necessarily facing each other. The width of the groove 26 is 0.4
And a depth of about 0.2 to 0.8 mm.

FIG. 7 shows the surface roughness of the surfaces of the rod-shaped refractories 20, 20...
The rough surface 27 is of such a degree that a fine gas passage is formed by joining these rough surfaces 27, 27.

Further, FIG. 8 shows a structure in which a refractory paper 28 is sandwiched between surfaces of 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. It is. In this case, the width of the refractory paper 28 is suitably 5 to 20 mm, and the thickness is suitably 0.2 to 0.4 mm.

In any of the above embodiments, the portion serving as the gas passage has a small cross-sectional area per one portion, and therefore, there is almost no infiltration of the molten steel, and it is expected that the useful life is 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 external dimensions of the gas injection plug.

[0022]

As described above, according to the present invention, since there is almost no infiltration of the metal in the gas passage, the operation of removing the metal by oxygen cleaning is remarkably reduced, and the erosion of the plug is prevented. As a result, the service life can be greatly extended. In addition, since a dense refractory can be used as the rod-shaped refractory, the durability is much higher than that of the conventional porous refractory which depends on the porous material, and the gas passage is formed by collecting the rod-shaped refractory. Since it is formed, cracks and cracks do not occur in the constituent material, and the durability can be improved from this point as well. Furthermore, since it is configured by combining rod-shaped refractories, processing for forming gas passages by holes and grooves is unnecessary,
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 showing a half section of another embodiment of the present invention.

FIG. 4 is an enlarged perspective view showing one of the bar-shaped refractories in FIG. 3;

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

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

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

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

FIG. 9 is a partial cross-sectional view showing a place where a gas injection 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]

 REFERENCE SIGNS LIST 1 molten metal container 2 plug for gas injection 3 gas supply pipe 4 metal case 20 rod-shaped refractory 20 A rod-shaped refractory aggregate 21 plug outer shell 23 convex part 24 concave part 25 chamfer 26 groove 27 rough surface 28 fire-resistant paper 29 gap

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) C21C 7/072 B22D 11/10 360 B22D 41/42 C21C 5/48 F27D 3/16

Claims (7)

(57) [Claims] At least four or more rod-shaped refractories having a square cross section and a predetermined length are combined in a staggered arrangement,
A plug for gas injection, wherein the rod-shaped refractory assembly is housed in a plug outer shell. 2. A bar-shaped refractory is provided by providing a projection 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 on the other side surface. 3. The gas injection plug according to claim 1, wherein the plug is combined. 3. The rod-shaped refractory corner is chamfered, and each rod-shaped refractory corner is formed as a gas passage.
Plug for gas injection as described. 4. The rod-shaped refractory has at least one groove in the longitudinal direction of the surfaces in contact with each other, and the rod-shaped refractory forms a gas passage by combining the grooves of the rod-shaped refractory with each other.
Plug for gas injection as described. 5. The gas injection plug according to claim 1, wherein the surface roughness of the surfaces of the rod-shaped refractories that are in contact with each other is in the range of 25 to 100 in arithmetic average roughness (Ra). 6. The gas injection plug according to claim 1, wherein a refractory paper is sandwiched between surfaces of the rod-shaped refractory which are in contact with each other, and a gap corresponding to the thickness of the refractory is a gas passage. 7. The plug according to claim 1, wherein the plug shell has a dense refractory layer surrounding the refractory rod assembly.