JP5907351B2 - Immersion pipe of molten metal refining equipment and method of constructing refractory in the immersion pipe - Google Patents

Description

  The present invention relates to a dip tube of a molten metal refining apparatus and a refractory construction method in the dip tube.

  Dipping pipes (immersion freeboards) used in molten metal refining equipment such as ladle refining equipment for refining hot metal and molten steel in the ladle (CAS method, SAB method, etc.) and vacuum degassing such as RH and DH The dip tube used in the processing apparatus usually has a structure in which a regular refractory and an irregular refractory are appropriately disposed inside and outside the core metal.

  By the way, the immersion part of the dip tube used in the above apparatus receives the heat of the molten metal, and the refractory and the cored bar each thermally expand, while the surface of the refractory is cooled after the treatment of the molten metal is finished. The refractory is prone to crack because it is placed in a harsh environment, and if the molten metal enters through the crack, the core metal may be lost or the refractory may fall off. It was a factor that hindered the extension of life span.

  In particular, in a vacuum degassing apparatus in which a dip tube for ascending and descending is suspended from the bottom of a vacuum treatment tank, at least the tip (lower end) of the trunk body of the dip tube is placed in the ladle. Since the molten metal in the ladle is immersed in the molten metal and the molten metal in the ladle is refluxed into the vacuum chamber to remove the gas components in the molten metal and adjust the components, the heat load on the dip tube is large. Combined with the fact that the mandrel easily expands, the refractory is likely to crack.

  As a prior art regarding this point, for example, Patent Document 1 discloses that each side surface of a refractory brick located in a lower stage is formed by stacking and arranging refractory bricks on the inner peripheral surface of a cylindrical amorphous refractory in which a metal frame is embedded. A structure has been proposed in which unevenness on a sine wave is formed on the surface, and the unevenness on the opposite side surfaces are engaged with each other and arranged in an annular shape to prevent the firebrick from falling off.

  Patent Document 2 discloses a double tube structure of an inner tube and an outer tube in which the lower end side of a cylindrical tubular metal bar is arranged at an interval, and a cooling heat medium is circulated above the double tube structure portion. A dip tube having a structure in which a cooling structure to be formed is formed and a refractory is filled thereunder has been proposed.

JP-A-8-291320 Japanese Patent No. 4361824

  However, the dip pipes disclosed in Patent Documents 1 and 2 have a complicated structure in any case, and it is difficult to efficiently construct a refractory, and an increase in cost is unavoidable. Yes, there is still room for improvement.

  An object of the present invention is to propose a dip tube of a molten metal refining apparatus and a method for constructing a refractory in the dip tube that can extend the life without complicating the structure and increasing costs.

  As a result of diligent research to overcome the above-mentioned problems of the prior art and realize the above object, the inventors have arrived at the present invention according to the following summary configuration. That is, the present invention is a dip tube of a molten metal refining apparatus, which is connected to a cylindrical metal core and one end of an open portion of the metal core, and connects the dip tube and the vacuum processing tank to each other. A flange and an indeterminate refractory layer surrounding the inner wall, tip, and outer wall of the cored bar and embedding the cored bar inside the flange, and of the amorphous refractory layer, the outer side of the cored bar A non-standard refractory layer surrounding the wall is provided with a butt joint that divides the non-standard refractory layer vertically along the axial direction of the core metal, and the butt joint has one end outside the core metal. The wall and the outer surface of the irregular refractory layer respectively reach at least two laterally abutting surfaces that form a step between them, and a longitudinally abutting surface that connects the other ends of the laterally abutting surfaces to each other Molten metal refining equipment A dip tube.

As a dip tube of a molten metal refining apparatus having the above-described configuration,
1) Of the lateral butt surfaces of the butt joint, the lateral butt surface reaching the outer surface of the irregular refractory layer is closer to the tip of the dip tube than the lateral butt surface reaching the outer peripheral wall of the cored bar. Be provided,
2) The dip tube of the molten metal refining device is a dip tube of a vacuum degassing device for molten steel, and is suspended at the bottom of the vacuum processing tank, immersed in the molten metal accommodated in the ladle and passed through the internal passage. In the case where the degassing treatment is performed by repeatedly refluxing the molten metal, the inner end of the flange is connected to the inside of the amorphous refractory layer, and at least the upper region of the amorphous refractory layer connected to the inner end of the flange. And a brick layer whose lower end surface is in contact with the upward surface formed in the amorphous refractory layer,
Is preferable as a specific means for solving the problems of the present invention.

  Further, the present invention reverses the cored bar by grounding the flange and holds it in an upright posture, and then arranges a brick layer on the inner side of the cored bar, and an annular recess surrounding the cored bar outside the cored bar. A first amorphous refractory layer is provided, and a second amorphous refractory layer is provided to connect the first amorphous refractory layer and the brick layer to each other, and the core is disposed inside the first refractory layer. It is the construction method of the refractory material in the dip tube of the molten metal refining apparatus characterized by burying gold.

  According to the dip tube of the molten metal refining apparatus according to the present invention having the above-described configuration, the one end of the outer wall of the core metal and the amorphous refractory layer of the core metal surround the outer wall of the core metal. The amorphous refractory layer is formed by at least two laterally abutting surfaces that respectively reach the outer surface and form a step therebetween, and a longitudinally abutting surface that connects the other ends of the laterally abutting surfaces to each other. However, even if there is a difference in thermal expansion between the amorphous refractory layer and the core metal during immersion in the molten metal, the butt joint is provided. The regular refractory layer has only a gap variation at the butt joint and does not crack.

  Moreover, even if the gap at the butt joint varies, the vertical butt surface always maintains a contact state, so that the molten metal that has entered through the gap is blocked by the vertical butt surface. Gold erosion and loss of amorphous refractories are avoided.

  Further, according to the dip tube of the molten metal refining apparatus according to the present invention, of the lateral butt surfaces of the butt joint, the lateral butt surface that reaches the outer surface of the irregular refractory, the lateral direction that reaches the outer wall of the core metal Since it is provided closer to the tip of the dip tube than the butt surface, the lateral butt surface of the irregular refractory that reaches the outer wall of the cored bar is located above the lateral butt surface that reaches the outer surface. As a result, the insertion of molten metal can be avoided more reliably.

  Further, according to the dip tube of the molten metal refining device according to the present invention, when the dip tube of the molten metal smelting device is applied as a dip tube of a vacuum degassing device, the flange is disposed inside the amorphous refractory layer. Since the brick layer is disposed so as to surround at least the upper region of the amorphous refractory layer connected to the inner end of the refractory layer and the lower end surface thereof is in contact with the upward surface formed in the amorphous refractory layer. The durability of the dip tube can be improved.

  Furthermore, according to the refractory construction method in the dip tube of the molten metal refining apparatus according to the present invention, the tip of the core metal is connected from the inner end of the flange to the flange while the core is inverted and held in an upright position. A brick layer is disposed on the inside of the metal core, and a first amorphous refractory layer having an annular recess surrounding the metal core is provided on the protruding end on the outer side of the metal core. Since the refractory layer is provided and the protruding portion of the first irregular refractory layer and the brick layer are connected to each other and embedded in the inside thereof, it is relatively simple without complicating the structure. Refractories can be constructed under the procedure.

It is the figure which showed typically the dip tube of the molten metal refining apparatus according to this invention about the cross section. It is the external appearance perspective view which showed the dip tube shown in FIG. 1 in the reverse state. It is the figure which expanded and showed the principal part of the dip tube shown in FIG. (A)-(e) is the figure which showed the construction point of the refractory according to this invention. It is the figure which showed typically other embodiment of the dip tube of the molten metal refining apparatus according to this invention about the cross section. (A)-(f) is the figure which showed the construction point of the refractory material of the dip tube shown in FIG. It is the figure which showed typically the further embodiment of the dip tube of the molten metal refining apparatus according to this invention about the cross section.

Hereinafter, the present invention will be specifically described with reference to the drawings.
FIG. 1 is a diagram schematically showing a cross section of a dip tube of a molten metal refining apparatus according to the present invention, and FIG. 2 is an external perspective view showing the dip tube shown in FIG. 1 in an inverted posture. .

  In the figure, reference numeral 1 denotes a cored bar having an opening at both ends, and 2 denotes a plurality of anchors (V-shaped or Y-shaped anchors) installed and fixed around the cored bar 1. This anchor 2 fixes and holds the irregular refractory to the metal core 1.

  Further, reference numeral 3 is a flange connected to one end 1a of the open part of the core metal 1, and connects the dip tube and the treatment tank (not shown) to each other, 4 is an inner wall 1b of the core metal 1, a tip 1c, An unshaped refractory layer (castable) that surrounds the outer wall 1d and is held by the flange 3 and in which the core metal 1 is embedded. Configure. A substantially cylindrical internal space M is formed inside the amorphous refractory layer 4. Further, the upper portion of the outer wall 1 d of the core metal 1 that is not immersed in the molten metal and the molten slag may be a structure exposed from the amorphous refractory layer 4.

  Reference numeral 5 denotes a butt joint formed in the amorphous refractory layer 4 that surrounds the outer wall of the core 1 among the amorphous refractory layer 4. The butt joint 5 divides the amorphous refractory layer 4 in the vertical direction along the direction of the axis L of the core metal 1, and one end is outside the outer wall of the core metal 1 and the amorphous refractory layer. The horizontal abutting surfaces 5a and 5b that respectively reach the surface and form a step t therebetween, and the vertical abutting surfaces 5c that connect the other ends of the lateral abutting surfaces 5a and 5b to each other. Here, the level difference t is preferably set to about 10 to 100 mm from the viewpoint of reliably preventing the molten metal from entering and the engagement (arrangement) with the anchor.

  The dip tube according to the present invention has a butt joint even if there is a difference in expansion amount between the core metal 1 and the amorphous refractory layer 4 when they are thermally expanded by receiving heat from the molten metal or contracted by cooling. The portion 5 absorbs the difference in the expansion amount due to the variation in the gap between the lateral facing surfaces 5a and 5b. This causes a large crack in the amorphous refractory layer 4 to reach the cored bar from the outer periphery, and the dip tube It is possible to avoid shortening the service life.

  The most likely cause of large cracks is that when the surface of the refractory on the outer periphery of the dip tube is cooled after the treatment of the molten metal, the outer periphery of the dip tube is affected by the difference in thermal expansion between the refractory and the core metal in the center. This is a case where a large tensile stress acts on the refractory on the side, and from the viewpoint of preventing this, the butt joint 5 is preferably provided at a position immersed in the molten metal of the dip tube. When the gap fluctuates in the butt joint 5 as shown in FIG. 3, the intrusion of the molten metal from that portion must be allowed, but the vertical butt surface 5c is maintained in a contact state (sliding). Yes, the metal core 1 and the molten metal are surely cut off.

  As shown in FIG. 1, the lateral facing surface 5b reaching the outer surface of the amorphous refractory layer 4 is closer to the tip of the dip tube than the lateral facing surface 5a reaching the outer peripheral wall of the core metal 1. It is good to provide, and this can further enhance the intrusion prevention effect of the molten metal.

The specific composition of the _{castable, Al 2 O 3: 3~98mass%} , MgО: 0~70mass%, _{other, Cr 2 О 3: 0~60mass%} , SiО 2: advantageously consist 0～10Mass% Fits.

  Of the amorphous refractory layer 4 divided by the butt joint 5, the amorphous refractory layer 4 (first amorphous refractory layer 4-1) located on the flange 3 side and the tip side of the dip tube Although it can be composed of a different composition from the positioned amorphous refractory layer 4 (second amorphous refractory layer 4-2), the same composition is used to suppress the expansion of the gap due to the difference in thermal expansion. It is preferable to use a castable.

  4 (a) to 4 (e) are diagrams showing a construction procedure of a refractory to produce a dip tube according to the present invention.

  In order to construct a refractory material on the core metal 1, first, as shown in FIG. 4 (a), the flange 3 is installed on the base, the core metal 1 is inverted and held in an upright position, and its tip is moved upward. Turn to.

  Next, a mold (not shown), a mold 6 and the like are installed to surround at least the upper area (flange 3 side) outside the core metal 1 and its core as shown in FIGS. A first amorphous refractory layer 4-1 having an annular recess 7 extending around the core metal 1 is formed at the end of the gold 1 on the front end side.

  When the amorphous refractory layer 4-1 is formed, a formwork or the like is further arranged in FIG. 4D without interposing a step of drying the amorphous refractory layer 4-1. As shown, a second amorphous refractory layer 4-2 that abuts the end of the first metal refractory layer 4-1 on the front end side of the metal core 1 and that embeds the metal core 1 therein is provided. What is necessary is just to form. The construction of the refractory is completed by forming the amorphous refractory layer 4-2, and then the dip tube is held in an inverted posture as shown in FIG.

  In the construction procedure of the refractory, in order to form the butt joint portion 5 on the irregular refractory layer 4, the first irregular refractory layer 4-1 is formed when the first irregular refractory layer 4-1 is formed. A die (ring) 6 (see FIG. 4B) for forming an annular recess 7 along the circumference of the core metal 1 is disposed at the end of the layer 4-1 on the front end side of the core metal 1 and the second Prior to the formation of the irregular refractory layer 4-2, the mold 6 may be removed, and the anchor 2 may be disposed at the site as necessary. Moreover, although the case where the second amorphous refractory layer 4-2 is provided without passing through the drying process for the amorphous refractory layer 4-1 has been described, a drying process can be incorporated as necessary.

  FIG. 5 is a view showing another embodiment of the dip tube according to the present invention. This dip tube is provided with a brick layer (standard refractory material) 8 arranged on the inner side of the core bar 1 from the inner end 3 a of the flange 3 toward the tip end 1 c of the core bar 1. The brick layer 8 surrounds the inner end 3a of the flange 3 and the upper area of the amorphous refractory layer 4 located inside the cored bar 1. The lower end surface 8a of the brick layer 8 faces the upward surface of the amorphous refractory layer 4. A substantially cylindrical inner space M is formed inside by contacting with 4a.

  The dip tube having the above configuration is particularly advantageously adapted as a dip tube of a vacuum degassing apparatus. In the case of the RH vacuum degassing apparatus, the substantially cylindrical inner space M constitutes a flow path for circulating the molten steel between the ladle and the vacuum degassing tank, and the molten steel in the flow path is inactive for circulation. It is desirable to install a gas pipe (not shown) for injecting the gas so as to penetrate the dip pipe from the outer peripheral side of the dip pipe and open to a position facing the internal space M of the brick layer 8.

  FIG. 6 shows a procedure for producing a dip tube provided with the brick layer 8. In order to construct a refractory material on the metal core 1 in order to produce a dip tube having such a configuration, the flange 3 is first installed on the base in the same manner as described above with reference to FIG. 1 is inverted and held in an upright position with its tip facing upward.

  Next, as shown in FIG. 6 (b), a brick layer 8 is arranged on the inner side from the inner end 3a of the flange 3 toward the tip of the core bar 1, and then a mold, a mold 6 and the like are installed. 6 (c) and 6 (d), it surrounds at least the upper region (flange 3 side) outside the metal core 1 and surrounds the metal core 1 around the end of the metal core 1 on the tip side. A first amorphous refractory layer 4-1 having an annular recess 7 is formed.

Further, without interposing the step of drying the amorphous refractory layer 4-1, a formwork or the like is arranged and the first amorphous refractory layer 4-as shown in FIG. A second amorphous refractory layer 4-2 is formed between the end of one cored bar 1 and the brick layer 8 so as to embed the tip and lower areas of the cored bar 1.

  In the present invention, it is also possible to configure a dip tube as shown in FIG. 7 having a configuration in which the installation position of the brick layer 8 is moved toward the tip of the dip tube. The installation position is not limited to the illustrated one.

As a component of the brick layer (standard refractory) 8, magnesia-chrome brick can be used, and when slag erosion resistance is important, magnesia-carbon brick is used, etc. It can be selected as appropriate according to the conditions. In addition, the members constituting the amorphous refractory layer 4 include high alumina, Al ₂ O ₃ —MgO—Cr ₂ O ₃ , Al ₂ O ₃ —Cr ₂ O ₃ , and Al ₂ O ₃ —MgO. Or the like can be used.

Core metal: diameter 1064 mm, length 628 mm (made by SS400),
Flange outer diameter: 1500mm,
The outer diameter of the main body of the dip tube: 1330 mm,
Inner diameter of dip tube body: 660 mm,
Immersion tube length (excluding flange thickness): 753 mm
Butt joint at the portion of the refractory tube outside the refractory layer that is immersed in the molten steel of the refractory layer (length of the lateral butt surface: 30 mm on the core metal side, 36 mm on the outer side, length of the vertical butt surface: 50 mm) As shown in FIG. 5 above (the brick layer is made of MgO—Cr ₂ O ₃ brick, and the amorphous refractory layer (castable) is made of Al ₂ O ₃ —MgO. Was used in an RH vacuum treatment tank to degas the molten metal, and the durability of the dip tube was investigated.

  As a result, in the conventional dip tube that does not have a butt joint, the use limit was reached with an average of 118 charges, whereas when the dip tube according to the present invention was used, the core metal was melted or formed into an irregular refractory. As a result, it was confirmed that it was possible to use up to an average of 128 charges and to extend the life of the dip tube.

  ADVANTAGE OF THE INVENTION According to this invention, the use life can be extended and the dip tube which can perform a refractory construction with a comparatively simple procedure, and its construction method can be provided.

DESCRIPTION OF SYMBOLS 1 Core metal 1a Open part 1b Inner side wall 1c Tip 1d Outer side wall 2 Anchor 3 Flange 3a Inner end 4 Amorphous refractory layer 4a Upward surface 4-1 First Amorphous refractory layer 4-2 Second Amorphous refractory Material layer 5 Butt joint 5a Lateral abutment surface 5b Lateral abutment surface 5c Vertical abutment surface 6 Type (ring)
7 annular recess 8 brick layer 8a lower end surface L axis t step

Claims (4)

A dip tube of a molten metal refining device,
Surrounding the inner wall, the tip, and the outer wall of the cored bar, a flange connected to one end of the open part of the cored bar, and connecting the dip tube and the vacuum processing tank to each other And an indeterminate refractory layer embedded in the cored bar,
Among the amorphous refractory layers, a butt joint for dividing the amorphous refractory layer vertically along the axial direction of the core metal is provided on the amorphous refractory layer surrounding the outer wall of the core metal. ,
The butt joint has one end reaching the outer wall of the cored bar and the outer surface of the irregular refractory layer to form a step between them, and the lateral butt surface A dip tube for a molten metal refining apparatus, characterized in that it comprises a longitudinal facing surface that connects the other ends to each other.   Of the lateral butting surfaces of the butted joint, the lateral butting surface reaching the outer surface of the irregular refractory layer is closer to the tip of the dip tube than the lateral butting surface reaching the outer peripheral wall of the cored bar. The dip tube of the molten metal refining apparatus according to claim 1, wherein the dip pipe is provided. The dip tube of the molten metal refining device is a dip tube of a vacuum degassing device,
An upward surface that is arranged inside the irregular refractory layer and surrounds at least the upper region of the irregular refractory layer connected to the inner end of the flange and the lower end surface of the irregular refractory layer. A dip tube for a molten metal refining device according to claim 1, further comprising a brick layer abutted on the molten metal. In the construction method of the refractory in the dip tube of any one of Claims 1-3,
After the flange is grounded and the cored bar is inverted and held in an upright position, a first amorphous refractory layer having an annular recess surrounding the cored bar is provided outside the cored bar, The molten metal refining apparatus is provided with two amorphous refractory layers, the first amorphous refractory layer and the brick layer are connected to each other, and the cored bar is embedded inside the molten metal smelting device. Refractory construction method for pipes.

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