Upper structure of molten metal container

Abstract

To provide an upper structure of a molten metal vessel capable of suppressing damage of a brick and a castable in an upper part of the molten metal vessel more than a conventional structure.SOLUTION: Shaped bricks 4, 5 are piled up on the innermost side of the side part of a ladle 100 as a molten metal vessel. The shaped brick 4 at the uppermost stage has a first part 41 arranged at the lower part than the upper end of the ladle 100 and a second part 42 arranged at the working surface side of the ladle 100 to the first part 41. The upper end of the second part 42 is located at a position higher than the upper end of the first part 41 and constitutes a part of the upper end of the ladle 100. A pressing member 9 is arranged between the outermost iron shell 1 of the ladle 100 and the second portion 42 and above the first portion 41, and an amorphous castable 10 supported by the pressing member is present. The shaped brick 4 at the uppermost stage is a mag-carbon brick and contains an antioxidant.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a superstructure for a molten metal vessel. [Background technology]

[0002] Patent Document 1 describes an upper structure for a ladle as an example of an upper structure for a molten metal container. The upper structure for a ladle described in Patent Document 1 is described as follows: "In the upper structure for a ladle in which regular-shaped work bricks are provided inside the ladle and a pressing member is provided above the work bricks, irregular-shaped alumina-magnesia castable is provided from above the work bricks to the upper end of the ladle, and this castable is supported by a fastener of the pressing member located inside the castable" (claims of Patent Document 1, etc.). No. 6 (conventional structure) in Figure 5 schematically shows the upper structure of a ladle described in Patent Document 1 (excluding the fastener). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-297766 Summary of the Invention [Problem to be solved by the invention]

[0004] When molten steel is contained in a molten metal vessel such as a ladle, slag floats on the molten steel. The innermost wall of the molten metal vessel, the portion that comes into contact with the slag (the slag line) is prone to corrosion. Therefore, in the conventional structure of Patent Document 1, for example, corrosion-resistant bricks are used for the work bricks in the slag line. Furthermore, the freeboard section above the slag line is prone to oxidation and wear due to contact with the atmosphere. In the conventional structure of Patent Document 1, an oxidation-resistant alumina-magnesia castable is provided in the freeboard section.

[0005] In recent years, molten metal vessels have begun to contain larger amounts of molten steel than before. When the amount of molten steel in the vessel increases, the slag may be positioned higher than before, resulting in the slag line being located in the conventional freeboard section. Therefore, corrosion resistance is required not only in the conventional slag line but also in the conventional freeboard section. While it is possible to use bricks used in conventional slag lines in the conventional freeboard section, the conventional freeboard section contains a portion that is in contact with the atmosphere, whether the vessel contains the same amount of molten steel as before or a larger amount than before. Therefore, oxidation resistance is required. However, a conventional freeboard section structure that can achieve both corrosion resistance and oxidation resistance has not yet been realized.

[0006] SUMMARY OF THE INVENTION An object of the present invention is to provide an upper structure for a molten metal vessel that can suppress damage to the bricks and castables at the top of the molten metal vessel compared to conventional structures. [Means for solving the problem]

[0007] The upper structure of a molten metal vessel described in this specification has shaped bricks stacked on the innermost side of the molten metal vessel, the top shaped brick having a first portion positioned below the top end of the molten metal vessel and a second portion positioned on the working surface side of the molten metal vessel relative to the first portion, the top end of the second portion being positioned higher than the top end of the first portion and constituting part of the top end of the molten metal vessel, a pressing member being positioned between the outermost steel shell of the molten metal vessel and the second portion and above the first portion, and unshaped castable refractory being supported by the pressing member, the top shaped brick being a magnesium-carbon brick and containing an antioxidant.

[0008] In the above configuration, the antioxidant may contain 2 to 5 mass % of SiC, less than 5 mass % (excluding 0 mass %) of Al, and less than 2 mass % (excluding 0 mass %) of Si.

[0009] In the above configuration, the second part has an outer surface facing the amorphous castable and an inner surface that serves as a working surface opposite the outer surface, and the outer surface may be inclined with respect to a direction perpendicular to the top surface of the first part and may be inclined so as to become closer to the inner surface as it approaches the top end of the second part. [Effects of the Invention]

[0010] It is possible to provide an upper structure for a molten metal vessel that can suppress damage to the bricks and castables at the top of the molten metal vessel compared to conventional structures. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a cross-sectional view of a molten metal container according to a first embodiment. [Figure 2] 2 is an enlarged cross-sectional view of the upper end of the molten metal vessel shown in FIG. 1. [Figure 3] FIG. 6 is an enlarged cross-sectional view of the upper end portion of the molten metal container according to the second embodiment. [Figure 4] FIG. 1 is an enlarged cross-sectional view of the upper end of a molten metal container used in the experiment. [Figure 5] FIG. 1 is an enlarged cross-sectional view of the upper end of a molten metal container used in the experiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] In the following embodiment, the molten metal container is a ladle, for example. In this specification, the term "molten metal container" refers to a container that contains molten metal and on which refractory materials such as slag float, which are likely to cause corrosion of refractories.

[0013] [First embodiment] FIG. 1 shows a schematic longitudinal cross section of the ladle 100 after construction. The ladle 100 is cylindrical and has a bottom. Hereinafter, the side of the ladle 100 that contains the molten metal will be referred to as the "inside" or "inside of the ladle 100," and the opposite side will be referred to as the "outside" or "outside of the ladle 100." The "inside" or "inside of the ladle 100" may refer to the radially inner side of the ladle 100. The "outside" or "outside of the ladle 100" may refer to the radially outer side of the ladle 100.

[0014] The outermost part of the ladle 100 is made up of a steel shell 1. Inside the steel shell 1, first permanent bricks 2 and second permanent bricks 3 are arranged in this order from the outside in. The first permanent bricks 2 and second permanent bricks 3 are used for a long period of time.

[0015] At the top of the side (body portion) of the ladle 100, shaped bricks (4, 5, 6, 7) are stacked inside the second permanent bricks 3 up to the top of the ladle 100. In FIG. 1, four shaped bricks (4, 5, 6, 7) are stacked, but the number of stacked shaped bricks is not particularly limited. In the portion other than the top of the ladle 100, unshaped castable refractory 8 is laid inside the second permanent bricks 3.

[0016] In this specification, "shaped bricks" are bricks that already have a predetermined shape when they are laid (lined). In this specification, "unshaped castable refractory" is a brick that does not have a predetermined shape when it is laid (lined), but is formed by pouring fluid castable refractory into a ladle and allowing it to harden. In this specification, "shaped bricks" and "unshaped castable refractory" are made of refractory materials.

[0017] Next, we will explain the upper structure of the ladle 100. The upper structure of the ladle 100 is the structure of the upper part of the side part (body part) of the ladle 100 shown in Figure 1. An enlarged view of II in Figure 1 is shown in Figure 2.

[0018] As shown in Figure 2, shaped bricks (4, 5) are stacked in the innermost part of the ladle 100. Below the topmost shaped brick 4, a shaped brick 5 is placed.

[0019] The topmost shaped brick 4 has a first portion 41 facing the second permanent brick 3 and a second portion 42 located inside the ladle 100 relative to the first portion 41. The first portion 41 and the second portion 42 are integral. The lower surfaces of the first portion 41 and the second portion 42 are flush with each other. The upper surface 41u of the first portion 41 and the upper surface 42u of the second portion 42 are located at different heights.

[0020] The first portion 41 is disposed below the upper end of the ladle 100. The upper surface 41u of the first portion 41 is flat. Here, the term "flat surface" includes a substantially flat surface.

[0021] The second portion 42 is located closer to the working surface of the ladle 100 than the first portion 41. The working surface of the ladle 100 is the innermost surface of the ladle 100, and includes the portion that comes into contact with the molten steel or slag in the ladle 100 during operation.

[0022] The upper end of the second portion 42 is located higher than the upper end of the first portion 41. The upper end of the second portion 42 is at the same height as the upper end of the ladle 100. The upper end of the second portion 42 forms part of the upper end of the ladle 100.

[0023] The second portion 42 has an outer surface 42o, an inner surface 42i, and an upper surface 42u.

[0024] The outer surface 42o is located at a higher position than the first portion 41 and faces the outer amorphous castable refractory 10 described later. The inner surface 42i is the surface opposite to the outer surface 42o and serves as the working surface of the ladle 100. The upper surface 42u forms part of the upper end of the ladle 100.

[0025] The outer side surface 42о is perpendicular to the upper surface 42u of the second portion 42. The angle θ2 between the outer side surface 42о and the upper surface 42u of the second portion 42 is 90°. The outer side surface 42о is perpendicular to the upper surface 41u of the first portion 41. The angle θ1 between the outer side surface 42о and the upper surface 41u of the first portion 41 is 90°. Although the outer side surface 42о is intended to be perpendicular to the upper surfaces 41u and 42u, a case in which the outer side surface 42о is slightly deviated from the perpendicular direction to at least one of the upper surfaces 41u and 42u due to manufacturing errors or the like is also included in this embodiment. Furthermore, although the angles θ1 and θ2 are intended to be 90° during the manufacturing process of the topmost shaped brick 4, a case in which at least one of θ1 and θ2 is slightly deviated from 90° due to manufacturing errors or the like is also included in this embodiment.

[0026] The distance (width) between the outer surface 42o and the inner surface 42i of the second portion 42 is constant in the height direction of the second portion 42. Although it is intended that the distance (width) between the outer surface 42o and the inner surface 42i be constant during the manufacturing process of the topmost shaped brick 4, this embodiment also includes cases where the distance is slightly deviated due to manufacturing errors or the like.

[0027] In the direction from the upper end to the lower end of the side of the ladle 100, the length of the inner surface 42i of the second portion 42 is longer than the length of the outer surface 41o of the first portion 41. The "outer surface 41o" of the first portion 41 is the surface facing the second permanent refractory brick 3. The "direction from the upper end to the lower end of the side of the ladle 100" may be a vertical direction or a direction inclined relative to the vertical direction.

[0028] A holding member 9 is disposed between the steel shell 1 and the second portion 42 of the uppermost shaped brick 4. The holding member 9 is disposed above the first permanent shaped brick 2, the second permanent shaped brick 3, and the first portion 41 of the shaped brick 4. The holding member 9 is fixed to the steel shell 1. The holding member 9 is spaced apart from the first portion 41 below it. The holding member 9 suppresses expansion of the shaped bricks (shaped bricks 4, 5, 6, and 7 shown in FIG. 1) stacked in the innermost part of the ladle 100 and also suppresses the falling off of these shaped bricks (4, 5, 6, and 7). The holding member 9 is made of, for example, metal.

[0029] Between the steel shell 1 and the second portion 42 of the uppermost shaped brick 4, the unshaped castable refractory 10 is present above the first permanent brick 2, the second permanent brick 3, and the first portion 41 of the shaped brick 4. The unshaped castable refractory 10 is present around the pressing member 9 so as to cover the pressing member 9. The unshaped castable refractory 10 is supported by the pressing member 9.

[0030] The second portion 42 of the uppermost shaped brick 4 is present inside the pressing member 9 and the unshaped castable refractory 10. The unshaped castable refractory 10 is not exposed to the innermost surface (working surface) of the ladle 100.

[0031] When the ladle 100 shown in FIGS. 1 and 2 contains a conventional amount of molten steel, the slag line is located lower than the pressure member 9 and the monolithic castable refractory 10 shown in FIG. 2. When the ladle 100 contains a conventional amount of molten steel, the slag line is located at the top end of the first portion 41 of the topmost shaped brick 4 or lower than the top end. The slag line is located in a height range S from the top end of the first portion 41 of the topmost shaped brick 4 to, for example, the bottom end. Hereinafter, "S" may be referred to as the "conventional slag line S." In the structure shown in FIG. 2, the lower portion of the second portion 42 of the topmost shaped brick 4 is located in the conventional slag line S. The "lower portion of the second portion 42" refers to the portion of the second portion 42 that is at a height below the top end of the first portion 41.

[0032] When the ladle 100 contains a conventional amount of molten steel, the freeboard portion is located in a height range F of the unshaped castable refractory 10 that covers the hold down member 9. When the ladle 100 contains a conventional amount of molten steel, the freeboard portion is located in a range F that is higher than the upper end of the first portion 41 of the uppermost shaped brick 4. Hereinafter, "F" may be referred to as the "conventional freeboard portion F." In the structure shown in FIG. 2 , the upper portion of the second portion 42 of the uppermost shaped brick 4 is located in the conventional freeboard portion F. The "upper portion of the second portion 42" refers to the portion of the second portion 42 that is higher than the upper end of the first portion 41. The upper portion of the second portion 42 is located inside the hold down member 9 and the unshaped castable refractory 10.

[0033] The topmost shaped brick 4 is a magnesium-carbon (MgO-C) brick. The topmost shaped brick 4 contains an antioxidant. The antioxidant may be added, for example, during the manufacturing process of the shaped bricks 4. The antioxidant is, for example, an antioxidant containing 2 to 5 mass% of SiC, less than 5 mass% (excluding 0 mass%) of Al, and less than 2 mass% (excluding 0 mass%) of Si.

[0034] The shaped bricks 5, 6, and 7 in the second and subsequent rows may be made of, for example, magnesium-carbon material or magnesium-chrome material.

[0035] The amorphous castable refractory 10 may be, for example, alumina magnesia or spinel magnesia.

[0036] The superstructure of the ladle 100 is obtained, for example, by the following method. As shown in FIG. 1, first permanent bricks 2 and second permanent bricks 3 are laid on the sides (body portion) of the shell 1. Permanent bricks are also laid on the bottom of the shell 1. After that, monolithic castable refractory 8 is laid from the bottom to the middle of the sides of the shell 1, and then shaped bricks (4, 5, 6, 7) are stacked on top of the monolithic castable refractory 8 up to the height of the top end of the shell 1. Then, as shown in FIG. 2, monolithic castable refractory 10 is laid between the shell 1 and the second portion 42 of the topmost monolithic brick 4, and above the first permanent bricks 2, second permanent bricks 3, and first portion 41. In this embodiment, no formwork or the like is required when laying the monolithic castable refractory 10. This is because the area where the amorphous castable refractory 10 is applied is surrounded by the steel shell 1, the second part 42 of the topmost shaped brick 4, the first permanent brick 2, the second permanent brick 3, and the first part 41.

[0037] The above-described upper structure of the ladle 100 provides the following effects.

[0038] In the conventional structure, the upper part of the second part 42 of the top row of shaped bricks 4 shown in Figure 2 does not exist. In the conventional structure, the upper part of the second part 42 does not exist inside the holding member 9 and the amorphous castable refractory 10 shown in Figure 2, and the amorphous castable refractory 10 is installed up to the working surface. The conventional structure is shown in "No. 6 (conventional structure)" in Figure 5 of the experiment described below.

[0039] In the conventional structure ("No. 6 (conventional structure)" in Figure 5), when the conventional amount of molten steel is contained, the conventional slag line S is located in the range of the height of the shaped bricks below the unshaped castables. The shaped bricks present in the conventional slag line S are often made of a material that is resistant to wear and tear. Above the conventional slag line S is the conventional freeboard section F. Unshaped castables are present in the conventional freeboard section F, and unshaped castables are often made of a material that is resistant to wear and tear even when in contact with the atmosphere. However, if a ladle with a conventional structure ("No. 6 (conventional structure)" in Figure 5) contains more molten steel than before and the slag line is located in the conventional freeboard section F, there is a risk that the unshaped castable refractory in the conventional freeboard section F will be melted.

[0040] In this embodiment, as shown in FIG. 2 , the upper part of the second portion 42 of the uppermost shaped brick 4 is located in the conventional freeboard section F. The upper part of the second portion 42 is made of magnesium-carbon material, which has high resistance to erosion. Therefore, even if the slag line is located in the conventional freeboard section F, the upper part of the second portion 42 is unlikely to be eroded. Furthermore, when the ladle 100 contains more molten steel than before, the upper part of the second portion 42 is located in the part that becomes the freeboard section. Because the upper part of the second portion 42 contains an antioxidant, the upper part of the second portion 42 is unlikely to be worn away by oxidation. As described above, in the structure shown in FIG. 2, when the ladle 100 contains more molten steel than conventional ladle 100, the slag line is less likely to melt and the freeboard portion is less likely to wear.

[0041] Furthermore, when the ladle 100 contains a conventional amount of molten steel, the lower part of the second portion 42 of the uppermost shaped brick 4 is present in the conventional slag line S. The lower part of the second portion 42 is made of magnesium-carbon material, which is highly resistant to corrosion, and is therefore less susceptible to corrosion. Furthermore, when the ladle 100 contains a conventional amount of molten steel, the upper part of the second portion 42 is present in the conventional freeboard section F. The upper part of the second portion 42 contains an antioxidant, and is therefore less susceptible to oxidation-induced wear. As described above, in the structure shown in FIG. 2, even when the ladle 100 contains a conventional amount of molten steel, the slag line is less likely to melt and the freeboard portion is less likely to wear.

[0042] As described above, the structure shown in Fig. 2 has high corrosion resistance and oxidation resistance on the working surface of the upper part of the ladle 100. Furthermore, the structure shown in Fig. 2 can suppress damage to the bricks and castable refractories in the upper part of the ladle 100 more effectively than the conventional structure. The "upper part of the ladle 100" here refers to the area at the height of the conventional freeboard section F and the conventional slag line S.

[0043] The uppermost shaped brick 4 contains an antioxidant. Although the components of the antioxidant are not limited, the oxidation resistance of the uppermost shaped brick 4 can be reliably improved by using an antioxidant containing 2 to 5 mass% SiC, less than 5 mass% (excluding 0 mass%) Al, and less than 2 mass% (excluding 0 mass%) Si.

[0044] Second Embodiment Next, the upper structure of a molten metal vessel according to a second embodiment will be described below with reference to Fig. 3. The second embodiment differs from the first embodiment in the configuration of the second portion 242 of the uppermost shaped brick 204. Note that the same components as those in the first embodiment described above are designated by the same reference numerals, and their description will be omitted as appropriate.

[0045] 3 shows a schematic vertical cross section of the upper part of the ladle 200 after construction. At the top of the side (body part) of the ladle 200, shaped bricks 204 and 5 are stacked in the innermost part up to the top end of the ladle 200. Below the topmost shaped brick 204, shaped brick 5 is placed.

[0046] The topmost shaped brick 204 has a first portion 41 facing the second permanent brick 3 and a second portion 242 located inside the ladle 200 relative to the first portion 41. The first portion 41 and the second portion 242 are integral. The lower surfaces of the first portion 41 and the second portion 242 are flush with each other. The upper surface 41u of the first portion 41 and the upper surface 242u of the second portion 242 are located at different heights.

[0047] The second portion 242 is located closer to the working surface of the ladle 200 than the first portion 41 .

[0048] The upper end of the second portion 242 is located at a higher position than the upper end of the first portion 41. The upper end of the second portion 242 is at the same height as the upper end of the ladle 200. The upper end of the second portion 242 forms part of the upper end of the ladle 200.

[0049] The second portion 242 has an outer surface 242o, an inner surface 242i, and an upper surface 242u.

[0050] The outer surface 242o is located higher than the first portion 41 and faces the outer amorphous castable refractory 10. The inner surface 242i is the surface opposite to the outer surface 242o and serves as the working surface of the ladle 100. The upper surface 242u forms part of the upper end of the ladle 100.

[0051] The outer surface 242o is inclined with respect to a direction perpendicular to the upper surface 242u of the second portion 242. The outer surface 242o is inclined with respect to a direction perpendicular to the upper surface 41u of the first portion 41. The outer surface 242o is inclined so as to approach the inner surface 242i of the second portion 242 as it approaches the upper end of the second portion 242. The angle θ formed between the outer surface 42o of the second portion 242 and the upper surface 41u of the first portion 41 21 The angle θ between the outer surface 242o of the second portion 242 and the upper surface 242u of the second portion 242 is an obtuse angle. 22 is an obtuse angle.

[0052] The distance (width) between the outer surface 242o and the inner surface 242i of the second portion 242 becomes shorter (narrower) as it approaches the upper surface 242u of the second portion 242.

[0053] In the direction from the upper end to the lower end of the side of the ladle 200, the length of the inner surface 242i of the second portion 242 is longer than the length of the outer surface 410 of the first portion 41. The "direction from the upper end to the lower end of the side of the ladle 200" may be a vertical direction or a direction inclined relative to the vertical direction.

[0054] Between the steel shell 1 and the second portion 242 of the topmost shaped brick 204, a pressing member 9 is arranged above the first permanent brick 2, the second permanent brick 3 and the first portion 41 of the shaped brick 4, and an unshaped castable refractory 10 is present.

[0055] The second portion 242 of the uppermost shaped brick 204 is present inside the pressing member 9 and the unshaped castable refractory 10. The unshaped castable refractory 10 is not exposed to the innermost surface (working surface) of the ladle 200.

[0056] When the ladle 200 shown in FIG. 3 contains a conventional amount of molten steel, the conventional slag line S and the conventional freeboard section F are in the same range as the conventional slag line S and the conventional freeboard section F shown in FIG. 2 of the first embodiment. The conventional slag line S includes the lower part of the second portion 242 of the uppermost shaped brick 4. The conventional freeboard section F includes the upper part of the second portion 242 of the uppermost shaped brick 4. The "lower part of the second portion 242" refers to the part of the second portion 242 that is at a height below the upper end of the first portion 41. The "upper part of the second portion 242" refers to the part of the second portion 242 that is higher than the upper end of the first portion 41.

[0057] The topmost shaped brick 204 is a magnesium-carbon (MgO-C) brick. The topmost shaped brick 204 contains an antioxidant. The antioxidant may be added, for example, during the manufacturing process of the shaped bricks 4. The antioxidant is, for example, an antioxidant containing 2 to 5 mass% of SiC, less than 5 mass% (excluding 0 mass%) of Al, and less than 2 mass% (excluding 0 mass%) of Si.

[0058] The superstructure of the ladle 200 can be obtained, for example, in a manner similar to that of the superstructure of the ladle 100 of the first embodiment.

[0059] The upper structure of the ladle 200 shown in FIG. 3 provides the following effects, similar to the upper structure of the ladle 100 of the first embodiment.

[0060] As shown in FIG. 3 , the upper part of the second portion 242 of the uppermost shaped brick 204 is located in the conventional freeboard section F. The upper part of the second portion 242 is made of magnesium-carbon material, which has high resistance to corrosion. Therefore, even if the ladle 100 contains more molten steel than before and the slag line is located in the conventional freeboard section F, the upper part of the second portion 242 is less likely to be corroded. Furthermore, when the ladle 200 contains more molten steel than before, the upper part of the second portion 242 is located in the freeboard section. Because the upper part of the second portion 242 contains an antioxidant, the upper part of the second portion 242 is less likely to be worn due to oxidation. As described above, in the structure shown in FIG. 3, when ladle 200 contains more molten steel than conventional ladle 200, the slag line is less likely to melt and the freeboard portion is less likely to wear.

[0061] Furthermore, when the ladle 200 contains a conventional amount of molten steel, the lower part of the second portion 242 of the uppermost shaped brick 4 is present in the conventional slag line S. The lower part of the second portion 42 is made of magnesium-carbon material, which is highly resistant to corrosion, and is therefore less susceptible to corrosion. Furthermore, when the ladle 200 contains a conventional amount of molten steel, the upper part of the second portion 42 is present in the conventional freeboard section F. The upper part of the second portion 42 contains an antioxidant, and is therefore less susceptible to oxidation-induced wear. As described above, in the structure shown in FIG. 3, even when the ladle 200 contains a conventional amount of molten steel, the slag line is less likely to melt and the freeboard portion is less likely to wear.

[0062] As described above, in the structure shown in FIG. 3, the upper part of the ladle 200 has high corrosion resistance and oxidation resistance, and therefore damage to the bricks and castable refractories in the upper part of the ladle 200 can be suppressed more effectively than in the conventional structure.

[0063] The uppermost shaped brick 204 contains an antioxidant. Although the components of the antioxidant are not limited, the antioxidant contains 2 to 5 mass% SiC, less than 5 mass% (excluding 0 mass%) Al, and less than 2 mass% (excluding 0 mass%) Si, thereby reliably improving the oxidation resistance of the upper end of the ladle 200.

[0064] Furthermore, metal and slag are firmly attached to the top of the ladle 200. To remove the metal and slag, the ladle 200 is impacted by a demolition machine or the like. However, for L-shaped bricks such as the shaped brick 204, the impact may cause cracks to form at the corners. An "L-shaped brick" refers to a brick that is L-shaped in the longitudinal cross section of the ladle 200. For example, in the case of the topmost shaped brick 204 shown in FIG. 3 , the "corner" of an L-shaped brick refers to the corner between the top surface 41u of the first portion 41 and the outer surface 242o of the second portion 242. A crack that begins at the corner may cause the second portion 242 to break or the topmost shaped brick 204 to fall off.

[0065] 3, the outer surface 242o of the second portion 242 is inclined. The outer surface 242o is inclined so as to approach the inner surface 242i as it approaches the upper surface 242u. The angle θ between the outer surface 242o and the upper surface 41u of the first portion 41 is 21 is an obtuse angle. With this shape, even if an impact is applied to the topmost shaped brick 204, the stress applied to the corner portion is dispersed, making it less likely for cracks to occur in the corner portion. As a result, the second portion 242 is less likely to break. In addition, the topmost shaped brick 204 is less likely to fall off.

[0066] The inclination amount of the outer surface 242o of the second portion 242 is not particularly limited. For example, the angle θ between the upper surface 41u of the first portion 41 and the outer surface 242o of the second portion 242 is 21 The angle may be greater than 90° and less than 111°, or greater than 94° and less than 107°. Furthermore, when the "distance (width) between the outer surface 242о and the inner surface 242i at the top end of the second portion 242" is L1 and the "distance (width) between the outer surface 242о and the inner surface 242i at the same height as the top surface 41u of the first portion 41" is L2, for example, L1 / L2 may be greater than 0.48 and less than 1, or L1 / L2 may be greater than 0.57 and less than 0.90. With such an inclination angle, even if an impact is applied to the topmost shaped brick 204, the second portion 242 is less likely to break and the topmost shaped brick 204 is less likely to fall off. Regardless of the inclination angle, damage to the bricks and castables can be reduced compared to conventional structures for the reasons described above.

[0067] Next, an experiment conducted to obtain the above findings will be described.

[0068] (experiment) The corrosion resistance and oxidation resistance of the upper part of the ladle were investigated for six different upper structures of ladles (Nos. 1 to 6). Figures 4 and 5 show the upper structures of ladles Nos. 1 to 6. Figures 4 and 5 also show the upper structures of the ladles after construction. Table 1 shows the conditions of the upper structures of ladles Nos. 1 to 6.

[0069] [Table 1]

[0070] The upper structure of ladles No. 1 to 6 will be explained.

[0071] No. 6 is the conventional structure shown in Figure 5. In the conventional structure of No. 6, unshaped castable refractories exist in the conventional freeboard section F, and shaped bricks exist in the conventional slag line S.

[0072] In Nos. 4 and 5 shown in Figure 5, tapered shaped bricks were placed in the conventional freeboard section F to improve the corrosion resistance of the conventional freeboard section F compared to the conventional structure of No. 6. To accommodate the tapered shaped bricks, a holding member with a partially inclined lower surface was used. Note that unshaped castable granules are present above the tapered shaped bricks, and although they are exposed on the working surface, they are near the top of the ladle and do not come into contact with the slag, even when the amount of molten steel is increased. The conventional slag line S has a portion of the tapered shaped brick and a shaped brick below it. The lower shaped brick is similar to the shaped brick in the conventional structure of No. 6. As shown in Table 1, the tapered shaped bricks in No. 4 are high-alumina, and the tapered shaped bricks in No. 5 are magnesia-chromium (magnesia-chromium).

[0073] The structures of Nos. 1 to 3 shown in Fig. 4 are similar in shape to the upper structure of the ladle of the second embodiment shown in Fig. 3. In Nos. 1 to 3, the upper part of the L-shaped bricks is present in the conventional freeboard section F. In the conventional slag line S, the lower part of the L-shaped bricks is present.

[0074] As shown in Table 1, No. 1 L-shaped brick was a magma-carbon brick containing an antioxidant. The antioxidant contained 2 to 5 mass% SiC, less than 5 mass% Al (excluding 0 mass%), and less than 2 mass% Si (excluding 0 mass%). No. 2 L-shaped brick was a magma-carbon brick containing no antioxidant. No. 3 L-shaped brick was a high-alumina brick.

[0075] Ladles No. 1 to No. 6 were repeatedly used for one year in the usual manner for those skilled in the art. The amount of molten steel contained in the ladle was not constant; sometimes it was the conventional amount and sometimes it was a larger amount than the conventional amount. The slag line was sometimes located in the conventional slag line S, sometimes in the conventional freeboard area F, and sometimes in both areas. The upper structure of the ladle was evaluated using the following method.

[0076] (Evaluation 1: Erosion resistance and oxidation resistance of conventional freeboard section F) When ladles are used repeatedly over an extended period of time, they will need to be repaired for a variety of reasons, including erosion, oxidation, or loss of shaped bricks or castables, and exposure of the holding members. The period from one repair to the next is considered one cycle, and the number of cycles in one year is taken as the total number of cycles. In conventional freeboard section F, as erosion or oxidation of shaped bricks or castables progresses, the holding members become exposed and repair becomes necessary. The frequency of exposure of the holding members in conventional freeboard section F was calculated using the following formula from the number of cycles in which the next repair was performed due to exposure of the holding members and the total number of cycles.

number

[0077] (Evaluation 2: Erosion resistance of conventional Slagline S) The wear rate [mm / ch] of the most worn part (most worn part) of conventional slag line S was investigated.

[0078] (Overall evaluation: Evaluation of the upper part of the ladle) In comparison with the conventional structure, if the frequency of exposure of the pressing member was lower than that of the conventional structure No. 6 in evaluation 1 and the wear rate was slower than that of the conventional structure No. 6 in evaluation 2, it was marked as "Good", otherwise it was marked as "Poor". "Good" means that the corrosion resistance and oxidation resistance of the conventional freeboard section F are higher than that of the conventional structure No. 6, and the corrosion resistance of the conventional slag line S is higher.

[0079] Furthermore, in the conventional freeboard section F and conventional slag line S, as corrosion and oxidation of shaped bricks or castables progresses, shaped bricks etc. fall off, making it necessary to repair the ladle. The number of cycles that required further repair due to the fall-off of shaped bricks etc. was counted in the same way as the number of cycles in Evaluation 1, and the brick fall-off rate [%] was calculated from this number of cycles and the total number of cycles using the following formula.

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[0080] Table 1 shows the results of Evaluation 1, Evaluation 2 and overall evaluation.

[0081] From Table 1, it can be seen that No. 1 had higher corrosion resistance and oxidation resistance of the conventional freeboard section F than No. 6 with the conventional structure, and the corrosion resistance of the conventional slag line S was also higher. This shows that No. 1 was able to suppress damage to the bricks and castables above the ladle compared to No. 6 with the conventional structure. Also, in No. 1, the bricks above the ladle did not fall off for one year.

[0082] On the other hand, in Nos. 2 to 5, the corrosion resistance and oxidation resistance were lower in the conventional freeboard section F or the conventional slag line S than in No. 6, which has a conventional structure.

[0083] In No. 2, the retaining members in the conventional freeboard section F were frequently exposed. The L-shaped bricks on the top row of No. 2 were made of magnesium carbon, which is highly resistant to corrosion, but they are easily oxidized and are thought to have worn away. No. 2 bricks did not fall off, but the bricks in the conventional freeboard section F were damaged more quickly than in No. 6, which had a conventional structure.

[0084] In No. 3, high-alumina L-shaped bricks were used to improve the oxidation resistance of the conventional freeboard section F. This reduced damage to the conventional freeboard section F, but the wear rate of the conventional slag line S was rapid. As the wear progressed in the conventional slag line S, bricks fell off.

[0085] In No. 4, high-alumina tapered bricks were used to improve the oxidation resistance of the conventional freeboard section F. As a result, damage to the conventional freeboard section F was small, but the wear rate of the conventional slag line S was rapid. As corrosion progressed in the conventional slag line S, bricks fell off.

[0086] In No. 5, the tapered shaped bricks were changed to magnesia-chrome to improve the oxidation resistance of the conventional freeboard section F. As a result, damage to the conventional freeboard section F was small, but the wear rate of the conventional slag line S was fast. As the wear progressed in the conventional slag line S, the bricks fell off.

[0087] In the conventional structure of No. 6, the retaining member in the conventional freeboard section F was frequently exposed. This is thought to be because the ladle contained more molten steel than before, and when the slag line was located in the conventional freeboard section F, the unshaped castable refractory was eroded by the slag. In the conventional structure of No. 6, the erosion of the conventional freeboard section F progressed, causing bricks to fall off.

[0088] From the above, the following was found: As shown in Figure 4, the upper part of the L-shaped bricks is placed in the conventional freeboard section F, and the lower part of the L-shaped bricks is placed in the conventional slag line S. The L-shaped bricks are made of magnesium carbon and contain an antioxidant. As a result, when the molten metal vessel contains more molten steel than before and the slag line is located in the conventional freeboard section F, the conventional freeboard section F is less likely to melt and be worn away by oxidation. Furthermore, when the molten metal vessel contains the conventional amount of molten steel, the conventional slag line S is less likely to melt and be worn away by oxidation. From the above, it was found that the structure shown in Figure 4 has high corrosion resistance and oxidation resistance in the upper part of the molten metal vessel, and can suppress damage to the bricks and castables in the upper part of the molten metal vessel more than the conventional structure.

[0089] Although the structure shown in Figure 4 was used in the experiment No. 1, the structure shown in Figure 2, i.e., the structure in which the corner angle (θ1) of the topmost shaped brick 4 is 90°, also has high corrosion resistance and oxidation resistance in the upper part of the molten metal vessel for the same reasons as above, and can suppress damage to the bricks and castables in the upper part of the molten metal vessel compared to the conventional structure.

[0090] Although the embodiments of the present invention have been described above with reference to the drawings, it should be understood that the specific configurations are not limited to these embodiments. The scope of the present invention is defined by the claims rather than the above description, and includes all modifications within the meaning and scope of the claims.

[0091] For example, in the structure shown in Figures 2 and 3, the lower end of the conventional slag line S is located at the height of the lower end of the second portion (42, 242) of the uppermost shaped brick (4, 204). However, the lower end of the conventional slag line S does not have to be at the lower end of the uppermost shaped brick (4, 204). For example, the lower end of the conventional slag line S may be located at a height above the lower end of the uppermost shaped brick (4, 204), or may be located at a height below the lower end of the uppermost shaped brick (4, 204). When the lower end of the conventional slag line S is located at a height below the lower end of the uppermost shaped brick (4, 204), it is preferable that the shaped brick located at the lower end of the conventional slag line S be a shaped brick having the same corrosion resistance as the shaped bricks in the conventional slag line S of the conventional structure. [Explanation of symbols]

[0092] 1 Ironhide 2. First Perm Brick 3. Second Perm Brick 4, 5, 6, 7, 204 Regular bricks 8, 10 Unshaped castable 9. Retaining member 41 Part 1 41о (First part) outer surface 41u (First part) top surface 42, 242 Part 2 42i, 242i (second part) inner surface 42о, 242о (second part) outer surface 42u, 242u (second part) top surface 100, 200 ladle S Conventional slug line F Conventional freeboard section

Claims

1. Shaped bricks are stacked on the innermost side of the molten metal vessel, the uppermost shaped brick has a first portion disposed below the upper end of the molten metal vessel and a second portion disposed on the working surface side of the molten metal vessel relative to the first portion; an upper end of the second portion is located higher than an upper end of the first portion and forms a part of an upper end of the molten metal container; a pressing member is disposed between the outermost shell of the molten metal vessel and the second portion and above the first portion, and amorphous castable refractory is supported by the pressing member; The uppermost shaped brick is a magnesium-carbon brick and contains an antioxidant.

1. A molten metal vessel upper structure comprising:

2. The antioxidant contains 2 to 5 mass% of SiC, less than 5 mass% (excluding 0 mass%) of Al, and less than 2 mass% (excluding 0 mass%) of Si.

2. The upper structure of a molten metal vessel according to claim 1.

3. The second portion has an outer surface facing the amorphous castable refractory and an inner surface serving as a working surface opposite the outer surface, The outer surface is inclined with respect to a direction perpendicular to the upper surface of the first portion, and is inclined so as to approach the inner surface as it approaches the upper end of the second portion.

3. The upper structure of a molten metal vessel according to claim 1 or 2.

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