JP2009046756A - Gas blowing plug - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gas blowing plug which can reduce the possibility of impairing a gas-flowing property in a porous refractory layer by changing the cross sectional shape, and can efficiently blow the gas into molten metal. <P>SOLUTION: The gas blowing plug is provided with: the porous refractory layer 5; and a gas supplying pipe connected to the porous refractory layer at the bottom part side. The porous refractory layer is provided with: a first porous part 10, which has almost head-cutting quadratic shape, and is connected to the gas supplying pipe; and a second porous part 20 having almost head-cutting columnar shape, successively arranged from the first porous part through no adhesive layer. The porosity ratio of the first porous part is more than the porosity ratio of the second porous part. In the first porous part, the area of the bottom part-end surface 11 is larger than that of the first boundary part-end surface 12 at the boundary with the second porous part. In the second porous part, the area of the second boundary part-end surface 21 at the boundary with the first porous part is larger than that of the top end part 22 at the reverse side. The length of a diagonal line at the first boundary part-end surface is made almost equal to the diameter of the second boundary part-end surface. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to a gas blowing plug used for blowing gas into molten metal in a steelmaking process.

  In the steelmaking process, a gas blowing plug using a refractory with gas flowability is attached to the bottom of the pan, etc. for stirring the molten metal, adjusting the temperature, and promoting the removal reaction of non-metallic components. A process of blowing a gas such as nitrogen into the molten metal is performed. This gas blowing plug has contact with the molten metal at the tip, and the molten metal penetrates into the refractory through the holes that form the gas flow path. Compared to the refractory on the ladle lining, Therefore, erosion and wear due to molten metal are severe. Therefore, in order to avoid a serious accident that the molten metal leaks out of the ladle, it is necessary to replace it with a new gas blowing plug before the wear progresses remarkably. However, it is wasteful in terms of resources, labor, and economy if the gas blowing plug is replaced too early in fear of leakage of molten metal.

  Therefore, conventionally, as shown in FIG. 5, a gas blowing plug 100 in which a porous refractory brick is formed so that its cross-sectional shape changes midway has been proposed and implemented (see, for example, Patent Document 1). In the illustrated example, the gas-permeable porous refractory brick 110 has a shape in which a quadrangular prism-shaped portion 111 and a truncated cone-shaped portion 112 are combined, and at the bottom of the porous refractory brick 110. A gas supply pipe 108 for supplying gas to the gas blowing plug 100 through the iron skin 109 is attached. A dense refractory layer 106 is formed on the outer periphery of the porous refractory brick 110.

  In the gas blowing plug 100 having such a configuration, when the molten metal is discharged from the ladle, the porous refractory brick 110 that is easily cooled by the gas flow appears dark in the dense refractory layer 106 that is still red hot. Both can be identified visually. Then, as shown in the cross-sectional view along the line XX in FIG. 5 (b), the porous refractory brick 110, which was initially visible in a circular shape, is shown in FIG. 5 (c) as Y- As shown in the cross-sectional view along the Y line, it looks like a square. Therefore, by setting the position where the cross-sectional shape is changed in the porous refractory brick 110 in consideration of the remaining size to replace the gas blowing plug 100, the gas blowing is detected by detecting the change in the cross-sectional shape. The arrival of plug 100 replacement time can be known.

Japanese Utility Model Publication No. 57-122751

  However, a porous refractory brick with a complicated shape whose cross-sectional shape changes from the middle is conventionally formed by bonding bricks with a simple shape such as a truncated cone shape, a cylindrical shape, or a quadrangular prism shape with a refractory mortar or the like. There were many cases. For this reason, the bonded bricks are likely to fall off and end up with a short life. In addition, molten metal easily enters the adhesive layer, and the solidification of the molten metal blocks pores of the porous refractory brick, which may impair gas flowability.

  On the other hand, when integrally forming a porous refractory brick, there is a problem that it is difficult to perform uniform pressure molding in addition to the labor and cost for manufacturing the mold because of its complicated shape. . In particular, the porosity tends to vary from part to part of the porous refractory brick, which greatly affects the gas flowability of the gas blowing plug. For example, if the porosity near the bottom, which is the starting end side of the gas flow path, is low, the gas flowability of the gas blowing plug as a whole depends on the porosity near the bottom even if the porosity of other parts is appropriate. There was a problem that was fixed. In addition, when the porosity of the plug end, which is the rear end of the gas flow path, is higher than other parts, the high porosity does not contribute to gas flow and is not only wasted, but also melted. There was a problem that the metal easily penetrates and becomes a negative factor.

  Furthermore, in the conventional gas blowing plug, since the cross-sectional area changes greatly with the change in the cross-sectional shape of the porous refractory brick, the gas flowability of the porous refractory brick has not been fully utilized. For example, in the conventional gas blowing plug 100 illustrated in FIG. 5, the cross-sectional area of the portion 111 is considerably smaller than the cross-sectional area of the portion 112, so that the gas flowability of the entire gas blowing plug 100 is determined by the area of the portion 111. It was something that would have been. On the contrary, as shown in FIG. 6, in the gas blowing plug 101 in which the cross-sectional area of the bottom portion 121 is considerably larger than the cross-sectional area of the tip portion 122 (an example shown in Patent Document 1 as another example). ), The gas that has risen in the portion 121 is prevented from further rising at the boundary 123 with the dense refractory layer 106, and there is a risk of generating stress.

  Accordingly, in view of the above circumstances, the present invention provides a porous refractory by changing the cross-sectional shape in a gas blowing plug in which the cross-sectional shape of the porous refractory layer is changed in order to detect the arrival of the replacement time. An object of the present invention is to provide a gas blowing plug that can reduce the gas flowability of the layer and can efficiently blow the gas into the molten metal.

  In order to solve the above-described problems, the gas blowing plug according to the present invention includes a porous refractory layer and a gas supply pipe connected to the porous refractory layer on the bottom side, and is melted in a steelmaking process. A gas injection plug for injecting a gas into a metal, wherein the porous refractory layer includes a first porous portion having a substantially truncated quadrangular pyramid shape connected to the gas supply pipe, and the first multi-layer. A substantially porous cone-shaped second porous portion continuously provided from the porous portion without an adhesive layer, and the porosity of the first porous portion is the same as that of the second porous portion. More than the porosity, the bottom end face in the first porous part is larger in area than the first boundary end face of the boundary with the second porous part, and in the second porous part The second boundary end surface of the boundary with the first porous portion has a larger area than the opposite end portion end surface, and the first boundary end surface The length of the rectangular wire is substantially equal "to the diameter of the second boundary end face.

  The kind of the refractory material constituting the “porous refractory layer” is not particularly limited. For example, alumina, spinel, alumina-silica, alumina-spinel, alumina-magnesia, alumina-carbon, magnesia Refractory materials such as carbonaceous, alumina-chromic, magnesia-chromic can be used.

  The configuration in which the second porous portion is “not connected through the adhesive layer” and “continuously provided from the first porous portion” is such that the first molded body is processed by cutting or other processing. Examples include a configuration in which the porous portion and the second porous portion are formed, and a configuration in which the first porous portion and the second porous portion are integrally formed. However, as described above, when a complicated shape is integrally formed, uniform forming is difficult and variation in porosity tends to increase. Therefore, it is preferable that a single formed body is processed afterwards.

  “Porosity” needs to be evaluated by the same method for the first porous portion and the second porous portion, but the measurement method is not particularly limited. For example, it can be measured using the apparent porosity measurement method, mercury intrusion method, and image analysis method defined in JIS R2205. In addition, as a method for setting “the porosity of the first porous portion is equal to or higher than the porosity of the second porous portion”, a method of adjusting the particle size of the refractory material filled in the mold according to the part is exemplified. can do. Alternatively, in the case where a single molded body is processed afterwards, a method of unidirectionally press-molding the original molded body and pressing from the side that constitutes the second porous portion is illustrated. Can do.

  With the above configuration, according to the present invention, at the boundary between the first porous portion and the second porous portion, the length of the diagonal of the truncated quadrangular pyramid and the diameter of the truncated cone are substantially equal. The cross-sectional shape can be discontinuously changed while minimizing the change in the cross-sectional area in the porous refractory layer. As a result, it is possible to clearly detect the replacement timing of the gas blowing plug by the discontinuous change from the circle to the square that can clearly distinguish the difference in shape, and the volume of the porous refractory layer that becomes the gas flow path The possibility that the gas flowability of the porous refractory layer is hindered is reduced.

  Furthermore, since the bottom end face has a larger area than the first boundary end face, and the second boundary end face has a larger area than the tip end face, the first porous part also has a second porous part. However, the cross-sectional area decreases from the start end side to the rear end side of the gas flow. As a result, like the conventional gas blowing plug with a smaller cross-sectional area on the start end side of the gas flow passage, the overall gas flow property is regulated by the cross-sectional area on the start end side, and the gas flow property on the rear end side is reduced. There is no risk of being wasted.

  In addition, if the first porous portion has a truncated cone shape and the second porous portion has a truncated quadrangular pyramid shape, the area of the second boundary end face is naturally the area of the first boundary end face. Since the gas becomes smaller, the gas that has risen in the first porous portion may lose its destination at the boundary surface with the second porous portion and generate stress. On the other hand, in the present invention, by adopting a configuration in which the first porous portion has a truncated quadrangular pyramid shape and the second porous portion has a truncated cone shape, there is no such a risk, and the front end from the bottom end face Gas can be circulated smoothly toward the end face of the part.

  In addition, if the porosity of the first porous portion is smaller than the porosity of the second porous portion, the overall gas flow may be regulated by the porosity on the gas flow start side. There is. On the contrary, when the porosity of the second porous portion is larger than the porosity of the first porous portion, there is a pore that cannot contribute much to the gas flow at the rear end side of the gas flow, which is useless. In addition, there is a large risk of molten metal entering. On the other hand, in the present invention, since the porosity of the first porous portion is equal to or higher than the porosity of the second porous portion, the gas supplied from the gas supply pipe is efficiently contained in the porous refractory. It is possible to flow well and gas can be efficiently blown into the molten metal, and the risk of the molten metal entering at the tip side of the second porous portion can be reduced.

  In addition, since the first porous portion and the second porous portion are integral and there is no adhesive layer between them, there is a risk that molten metal may enter through the adhesive layer, However, there is no possibility of dropping from the first porous portion.

  According to the gas blowing plug of the present invention, “the length of the diagonal line of the bottom end face extends virtually the height of the first porous part from the second porous part toward the bottom end face. The diameter of the end face on the bottom side in the provided virtual head cone is substantially equal. "

  With the above configuration, according to the present invention, the first porous portion and the second porous portion can be obtained by creating a truncated cone-shaped molded body in advance and performing subsequent processing such as cutting and excision. When forming a porous refractory layer having a `` virtual mounting in which the second porous portion is virtually extended by the height of the first porous portion toward the bottom end surface ''. By adopting a “conical shape”, it is possible to perform a simple and lean process while minimizing a portion to be cut and excised.

  As described above, as an effect of the present invention, in the gas blowing plug in which the cross-sectional shape of the porous refractory layer is changed to detect the arrival of the replacement time, the porous refractory layer is changed by changing the cross-sectional shape. The possibility that the gas flowability of the gas is impaired is reduced, and a gas blowing plug capable of efficiently blowing gas into the molten metal can be provided.

  Hereinafter, a gas blowing plug according to the best embodiment of the present invention will be described with reference to FIGS. Here, FIG. 1 is (a) longitudinal sectional view, (b) AA sectional view, (c) BB sectional view of the gas blowing plug of this embodiment, FIG. FIG. 3A is a perspective view of a porous refractory layer in a gas blowing plug, FIG. 3B is a cross-sectional view taken along the line CC, and FIG. 3 is an explanatory view illustrating a method for forming the porous refractory layer of FIG. .

  As shown in FIGS. 1A and 2, the gas blowing plug 1 of the present embodiment includes a porous refractory layer 5 and a gas supply pipe 8 connected to the porous refractory layer 5 on the bottom side. The porous refractory layer 5 includes a first porous portion 10 having a substantially truncated quadrangular pyramid shape connected to the gas supply pipe 8 and an adhesive layer from the first porous portion 10. The first porous portion 10 has a porosity that is equal to or higher than the porosity of the second porous portion 20. In the porous portion 10, the bottom end surface 11 has a larger area than the first boundary portion end surface 12 at the boundary with the second porous portion 20, and the first porous portion 10 in the second porous portion 20. The second boundary portion end face 21 has a larger area than the opposite end portion end face 22, and the diagonal length of the first boundary end face 12 is the length of the second boundary end face 21. It is set to substantially equal to the diameter.

  More specifically, the outer peripheral surface of the porous refractory layer 5 is covered with a dense refractory layer 6, and the gas supply pipe 8 is provided with a gas pool portion 7 by an iron skin 9 covering the dense refractory layer 6. It is being fixed to the porous refractory layer 5 via. In addition, the height of the 1st porous part 10 is set in consideration of the remaining dimension which should replace | exchange the gas blowing plug 1 for a new thing, and is about 100-150 mm normally.

  If the gas blowing plug 1 is attached to the bottom of the pan or the like and used to blow gas into the molten metal, the porous refractory layer 5 and the dense refractory layer 6 are worn from the tip side. When the molten metal is discharged from the ladle, the porous refractory layer 5 that appears dark in the red refractory dense refractory layer 6 is shown in FIG. The shape changes from a circle showing a line cross section to a quadrangle showing a BB line cross section in FIG. At this time, the cross-sectional shape changes discontinuously, and the difference between the square shape and the circular shape can be clearly identified. Therefore, the arrival of the replacement time can be detected without overlooking this change.

  In addition, as apparent from a comparison between FIG. 1B and FIG. 1C, in this embodiment, even if the cross-sectional shape of the porous refractory layer 5 changes, the change in the cross-sectional area is small. Therefore, a sufficient volume of the porous refractory layer 5 serving as a gas flow path is ensured.

  In addition, as shown in FIG. 4, if the porous refractory layer 50 is configured by the first conical-shaped first porous portion 51 and the second quadrangular pyramid-shaped second porous portion 52, The gas that has risen in the first porous portion 51 is blocked at the boundary surface 53 with the second porous portion 52 by the dense refractory layer, and stress may be generated there. On the other hand, in this embodiment, since the first porous portion 10 has a truncated quadrangular pyramid shape and the second porous portion 20 has a truncated cone shape, there is no possibility that such stress occurs, Gas smoothly flows through the refractory layer 5.

  Next, an example of a method for forming the porous refractory layer 5 of the present embodiment will be described with reference to FIG. The porous refractory layer 5 can be formed by post-processing a cone-shaped shaped body 30 as shown in FIG. Here, as shown in FIG. 3B, the shape of the original molded body 30 is virtually equal to the height of the first porous portion 10 with the second porous portion 20 facing the bottom end face 11. It can be made into the virtual head-on-cone extended in the direction. Thereby, the diameter of the virtual bottom end surface 31 which is the end surface on the bottom side in the virtual mounting cone is equal to the length of the diagonal line of the bottom end surface 11 of the first porous portion 10. In addition, in FIG.3 (b), the part which extended the 2nd porous part 20 virtually is shown with the dashed-two dotted line.

  And the porous refractory of this embodiment by which the 2nd porous part 20 was connected with the 1st porous part 10 by cutting or excising the part shown with the dashed-dotted line in FIG.3 (c). Layer 5 can be formed. Here, in the case of a simple conical cone shape, since a uniform shaped body of tissue can be stably produced, a complicated shape including the first porous portion 10 and the second porous portion 20 is provided. Compared with the case where a mold corresponding to the above is made and the porous refractory layer 5 is integrally molded using the mold, a molded body 30 with less variation in porosity can be obtained. Furthermore, by forming the molded body 30 by one-way pressure molding while applying pressure from the side that becomes the end portion end surface 22, the first porous portion 10 is obtained while having a substantially uniform porosity as a whole. It is possible to mold the molded body 30 having a slightly higher porosity on the side than the porosity on the side that becomes the second porous portion 20. Thereby, the porous refractory layer 5 whose porosity of the 1st porous part 10 is more than the porosity of the 2nd porous part 20 can be obtained by processing the molded object 30 afterwards. .

  As described above, according to the gas blowing plug 1 of the present embodiment, the cross-sectional shape of the porous refractory layer 5 changes discontinuously into a clearly identifiable shape from a circle to a square. Since the cross-sectional area of the refractory refractory layer 5 is not greatly changed, the gas flowability is hardly hindered by changing the cross-sectional shape.

  Further, since the diagonal line of the bottom end face 11 is substantially equal to the diameter of the virtual bottom end face 31, the area of the bottom end face 11 is large, and the cross-sectional area of the gas flow passage on the start end side is small. As described above, the overall gas flowability is not limited by the cross-sectional area on the start end side.

  In addition, since the first porous portion 10 has a truncated quadrangular pyramid shape and the second porous portion 20 has a truncated cone shape, the first porous portion 10 and the second porous portion 20 There is no risk of stress due to gas pressure at the boundary.

  In addition, in this embodiment, since the porous refractory layer 5 is formed by post-processing the single molded body 30 formed into a virtual conical cone, the porous refractory layer is formed. The porosity of the first porous portion 10 is slightly larger than the porosity of the second porous portion 20 due to the unidirectional pressurization. ing. Thereby, while being able to distribute | circulate the gas supplied from the gas supply pipe | tube 8 efficiently in a porous refractory, the possibility that a molten metal permeates into the front end side of the 2nd porous part 20 may be reduced. it can.

  In addition, since the single molded body 30 is processed afterwards, there is no adhesive layer between the first porous portion 10 and the second porous portion 20, so that the molten metal is interposed through the adhesive layer. Is not likely to enter, and the second porous portion 20 may not fall out of the first porous portion 10.

  In addition, the diagonal length of the bottom end face 11 is substantially equal to the diameter of the virtual bottom end face 31, and the diagonal length of the first boundary end face 12 is substantially equal to the diameter of the second boundary end face 21. As a result, the portion to be cut and cut when the molded body 30 is processed afterwards is minimized. Thereby, processing is easy and the waste of resources is reduced.

  The present invention has been described with reference to the preferred embodiments. However, the present invention is not limited to the above-described embodiments, and various improvements can be made without departing from the scope of the present invention as described below. And design changes are possible.

  For example, an amorphous refractory layer, a dense regular refractory layer, or a porous regular refractory layer is provided on the outer peripheral surface of the dense refractory layer 6 of the gas blowing plug 1 having the above-described configuration via an iron skin 9. A sleeve layer composed of a physical layer can be provided. Normally, when a gas blowing plug is attached to a ladle, the gas blowing plug is fitted in a hole provided in a tuyere brick (receiving brick) at the bottom of the ladle. The gas blowing plug can be fixed to the tuyeres brick while protecting the refractory layer. In addition, in the present embodiment, since the first porous portion 10 has a quadrangular pyramid shape, the iron skin 9 is provided on the outer peripheral surface of the dense refractory layer 6 rather than directly attached to the porous refractory layer 10. Although it is easy, since the iron skin 9 does not directly contact the inner wall of the hole portion of the tuyere brick by providing the sleeve layer, damage to the hole portion of the tuyere brick can be suppressed.

It is the (a) longitudinal cross-sectional view of the gas blowing plug of this embodiment, (b) AA sectional view, (c) BB sectional drawing. It is the (a) perspective view and (b) CC sectional view taken on the line of the porous refractory layer in the gas blowing plug of FIG. It is explanatory drawing which illustrates the shaping | molding method of the porous refractory layer of FIG. It is a perspective view of the porous refractory layer of another invention compared with the porous refractory layer of FIG. It is (a) longitudinal cross-sectional view, (b) XX sectional view, (c) YY sectional view of the conventional gas blowing plug. It is a longitudinal section of other conventional gas blowing plugs.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Gas blowing plug 5 Porous refractory layer 6 Dense refractory layer 7 Gas pool part 8 Gas supply pipe 9 Iron skin 10 1st porous part (porous refractory layer)
11 bottom end face 12 first boundary end face 20 second porous part (porous refractory layer)
21 End surface 22 of the second boundary portion End surface 30 of the tip portion Molded body 31 End surface of the virtual bottom portion

Claims (2)

A porous refractory layer, and a gas supply plug connected to the porous refractory layer on the bottom side, for injecting gas into the molten metal in a steelmaking process,
The porous refractory layer includes a substantially truncated quadrangular pyramid-shaped first porous portion connected to the gas supply pipe, and a substantially continuous connection from the first porous portion without an adhesive layer. A second conical portion having a conical shape;
The porosity of the first porous portion is equal to or higher than the porosity of the second porous portion;
In the first porous portion, the bottom end surface has a larger area than the first boundary end surface at the boundary with the second porous portion, and the first porous portion in the second porous portion. The second boundary end face of the boundary with the area is larger than the end face on the opposite end,
The length of the diagonal line of said 1st boundary part end surface is substantially equal to the diameter of said 2nd boundary part end surface, The gas blowing plug characterized by the above-mentioned.   The length of the diagonal line of the bottom end face is the bottom side in the hypothetical truncated cone shape in which the second porous part is virtually extended by the height of the first porous part toward the bottom end face. The gas blowing plug according to claim 1, wherein the diameter is substantially equal to the diameter of the end face of the gas blowing plug.

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