Slide gate lower nozzle and slide gate lower nozzle plate

Abstract

To provide a lower nozzle plate for a slide gate, in which a refractory layer is formed to have a double-layered structure of a shaped refractory on an inner peripheral side and an unshaped refractory on an outer peripheral side, and which can prevent the unshaped refractory on the outer peripheral side from peeling away.SOLUTION: A lower nozzle plate 1 for a slide gate comprises: a shaped refractory 4 in which a circulation hole 4a for molten metal is formed; an unshaped refractory 5 that is provided around the shaped refractory 4; and a steel shell 7 that covers an outer periphery of the unshaped refractory 5. The steel shell 7 is provided with an embracement section 7c for holding a downstream-side end of the unshaped refractory 5 by covering at least a part 5a of a downstream-side end surface of the unshaped refractory 5.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a slide gate lower nozzle and a slide gate lower nozzle plate used in a vessel for accommodating molten metal, such as an electric furnace, a ladle, or a tundish. [Background technology]

[0002] A slide gate for opening and closing an outflow hole for the molten metal is attached to a vessel for accommodating molten metal, such as an electric furnace, a ladle, or a tundish. The slide gate includes an upper nozzle plate attached to the vessel, and a lower nozzle plate that slides relative to the upper nozzle plate. An outflow hole for the molten metal is formed in each of the upper nozzle plate and the lower nozzle plate. The upper nozzle plate includes an upper nozzle and an upper plate. The lower nozzle plate includes a lower plate that slides relative to the upper plate, and a lower nozzle fixed to the lower plate.

[0003] As a conventional lower nozzle, a slide gate lower nozzle (see Patent Document 1) has been disclosed that includes a shaped refractory in which a flow hole for molten metal is formed, an unshaped refractory provided around the shaped refractory, and an iron shell covering the outer periphery of the unshaped refractory. With this lower nozzle, the refractory layer is formed into a two-layer structure of a shaped refractory on the inner periphery side and an unshaped refractory on the outer periphery side, so that the corrosion resistance of the refractory layer can be improved. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 6-142899 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the slide gate lower nozzle described in Patent Document 1, the shaped refractory on the inner circumference expands more than the monolithic refractory on the outer circumference in the early stages of use, and the monolithic refractory on the outer circumference is pushed apart by the monolithic refractory on the inner circumference, which may cause the downstream end of the monolithic refractory on the outer circumference to peel off. When the downstream end of the monolithic refractory on the outer circumference peels off, the monolithic refractory on the inner circumference in that area is exposed, and the exposed monolithic refractory on the inner circumference oxidizes and deteriorates before it reaches its end of life.

[0006] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a lower nozzle for a slide gate and a lower nozzle plate for a slide gate in which the refractory layer is formed in a two-layer structure of a shaped refractory on the inner circumference and an amorphous refractory on the outer circumference, which can prevent the amorphous refractory on the outer circumference from peeling off. [Means for solving the problem]

[0007] In order to solve the above problems, one aspect of the present invention is a lower nozzle for a slide gate, the lower nozzle comprising: a shaped refractory having a flow hole for molten metal; an unshaped refractory having refractory aggregate provided around the shaped refractory; and an iron shell covering the outer periphery of the unshaped refractory, the iron shell having at least a part of a downstream end face of the unshaped refractory. only and a downstream end of the unshaped refractory material is provided. The shaped refractory is made of magnesia-carbon shaped refractory. This is a lower nozzle for a slide gate.

[0008] The present invention can also be configured as a lower nozzle plate for a slide gate, comprising the above-mentioned lower nozzle for a slide gate and a lower plate. Effect of the Invention

[0009] According to the present invention, an embracing portion is provided in the steel shell which covers at least a portion of the downstream end face of the amorphous refractory and holds the downstream end of the amorphous refractory, thereby preventing the amorphous refractory on the outer periphery from falling off during use. [Brief description of the drawings]

[0010] [Figure 1] 1A and 1B are diagrams showing a lower nozzle plate for a slide gate according to one embodiment of the present invention (FIG. 1(a) is a plan view, and FIG. 1(b) is a vertical cross-sectional view). [Diagram 2] FIG. 2 is an enlarged view of part II in FIG. [Diagram 3] FIG. 13 is a diagram showing an example in which the lower nozzle plate of this embodiment is used in a slide gate of an electric furnace. [Figure 4] FIG. 2 is a vertical cross-sectional view showing a lower nozzle for a slide gate according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, the slide gate lower nozzle and the slide gate lower nozzle plate of the embodiment of the present invention will be described in detail with reference to the accompanying drawings. However, the slide gate lower nozzle and the slide gate lower nozzle plate of the present invention can be embodied in various forms and are not limited to the embodiments described in this specification. The present embodiment is provided with the intention of enabling those skilled in the art to fully understand the invention by fully disclosing the specification. (Lower nozzle plate for slide gate)

[0012] Fig. 1 shows a lower nozzle plate 1 for a slide gate according to one embodiment of the present invention. Fig. 1(a) is a plan view, and Fig. 1(b) is a vertical cross-sectional view taken along the center line of the outlet hole. The lower nozzle plate 1 is held by equipment 2 that moves the lower nozzle plate 1.

[0013] The lower nozzle plate 1 for a slide gate (hereinafter simply referred to as the lower nozzle plate 1) comprises a refractory layer 3 and an iron shell 7 made of a steel material covering the refractory layer 3. The refractory layer 3 is disc-shaped and comprises a plate portion 3a which is slidable relative to the upper plate, and a cylindrical nozzle portion 3b extending downward from the plate portion 3a. The iron shell 7 comprises a box-shaped portion 7a which covers the side and bottom surfaces of the plate portion 3a, and a cylindrical portion 7b which covers the nozzle portion 3b. The box-shaped portion 7a and the cylindrical portion 7b of the iron shell 7 are connected by welding.

[0014] The refractory layer of the nozzle portion 3b is formed in a two-layer structure of a shaped refractory 4 on the inner peripheral side and an unshaped refractory 5 on the outer peripheral side. That is, the refractory layer of the nozzle portion 3b includes the shaped refractory 4 in which the flow holes 4a for the molten metal are formed, and the unshaped refractory 5 provided around the shaped refractory 4. Both the shaped refractory 4 and the unshaped refractory 5 are cylindrical.

[0015] The plate portion 3a includes a plate-shaped refractory 6 in which a flow hole 6a for the molten metal and a sliding surface 6b are formed. The plate-shaped refractory 6 is surrounded by the unshaped refractory 5.

[0016] The plate-shaped refractory 6 and the cylindrical shaped refractory 4 are connected by mortar. The unshaped refractory 5 is produced by casting a fluid refractory material (castable) between the shaped refractories 4, 6 and the steel shell 7.

[0017] As shown in the enlarged view of FIG. 2, a portion 5a (outer diameter portion 5a) of the downstream end face of the monolithic refractory 5 is covered by the embedding portion 7c of the iron shell 7. The remaining portion (inner diameter portion 5b) of the downstream end face of the monolithic refractory 5 is exposed from the iron shell 7. The inner diameter portion 5b and the end face of the embedding portion 7c are substantially on the same plane. A step is formed between the inner diameter portion 5b and the outer diameter portion 5a by the thickness of the embedding portion 7c.

[0018] The embedding portion 7c of the shell 7 is formed by welding a ring-shaped, plate-shaped embedding portion 7c to the downstream end of the cylindrical portion 7b of the shell 7. In the cross-sectional view of FIG. 2, the cylindrical portion 7b of the shell 7 and the embedding portion 7c are at a substantially right angle.

[0019] As shown in Fig. 1 again, the shaped refractory 6 of the plate portion 3a is made of zirconia shaped refractory. The shaped refractory 6 of the plate portion 3a plays a role like scissors to cut the molten metal, so it needs to have strength, corrosion resistance against the molten metal (or slag), and wear resistance against the flow of the molten metal. For this reason, the shaped refractory 6 of the plate portion 3a is made of zirconia.

[0020] The zirconia-based shaped refractory 6 is manufactured by adding a binder to stabilized zirconia to which a stabilizer has been added, kneading the mixture, putting the mixture into a mold and pressing it, and then demolding, drying, and firing it. The stabilizer is one or more of yttrium oxide (Y2O3), magnesium oxide (MgO), and calcium oxide (CaO). The manufactured zirconia-based shaped refractory 6 contains 90 to 98 mass % of zirconia (ZrO2) and 2 to 10 mass % of the stabilizer. In addition to stabilized zirconia, powders of zirconia ore and stabilizer may be used as the raw material. After adding a binder, the raw material may be granulated and then press molded.

[0021] The shaped refractory 4 of the nozzle portion 3b is made of magnesia-carbon shaped refractory. Considering strength, corrosion resistance against molten metal (or slag), and wear resistance against the flow of molten metal, it is desirable to use the above-mentioned zirconia shaped refractory. However, if a zirconia shaped refractory is used as the refractory of the long nozzle portion 3b, cracks will occur in the shaped refractory due to the influence of thermal expansion and contraction during firing. In the case of a zirconia unshaped refractory with high porosity (unshaped refractory manufactured by casting), although the pores present in the refractory mitigate the development of cracks due to thermal expansion and contraction, it is not possible to completely prevent melting damage due to the flow of molten metal. For this reason, the shaped refractory 4 of the nozzle portion 3b is made of magnesia-carbon.

[0022] The magnesia-carbon shaped refractory 4 is manufactured, for example, by adding additives such as metals for preventing oxidation and binders such as resins to magnesia (MgO) and carbon (C), kneading the kneaded mixture, pressing it in a mold, and then removing it from the mold and drying it. If necessary, firing and impregnation may be performed. The manufactured magnesia-carbon shaped refractory contains 75 to 95 mass % magnesia (MgO) and 5 to 25 mass % carbon (C).

[0023] The unshaped refractory 5 is produced by casting a refractory material (castable) having fluidity between the shaped refractories 4, 6 and the steel shell 7. There are no particular limitations on the castable, and for example, an additive such as graphite, a binder such as alumina cement, and water are added to refractory aggregate, and the mixture is kneaded and then cast. The unshaped refractory 5 serves to integrate the shaped refractories 4, 6 and the steel shell 7. The unshaped refractory 5 also serves to reduce the amount of expensive shaped refractories 4, 6 used, and has a lower bulk density than the shaped refractories, so it also serves to reduce the overall weight.

[0024] 3 shows an example in which the lower nozzle plate 1 of this embodiment is used in a slide gate 12 of an electric furnace 11. Reference numeral 13 denotes an upper nozzle plate, and 1 denotes a lower nozzle plate. The upper nozzle plate 13 is fixed to the electric furnace 11. The upper nozzle plate 13 is formed by integrating an upper nozzle 13a and an upper plate 13b. The upper nozzle plate 13 is formed with a flow hole 13c for the molten metal.

[0025] The lower nozzle plate 1 is slidable relative to the upper nozzle plate 13. A flow hole 4a for the molten metal is also formed in the lower nozzle plate 1. When the electric furnace 11 is tilted to connect the flow hole 13c of the upper nozzle plate 13 with the flow hole 4a of the lower nozzle plate 1, the molten metal is tapped into the ladle 14.

[0026] As in this example, the directions in which the flow holes 13c and 4a of the upper nozzle plate 13 and the lower nozzle plate 1 extend may be substantially horizontal. In this case, the upper nozzle plate 13 is on the upstream side, and the lower nozzle plate 1 is on the downstream side.

[0027] The lower nozzle plate 1 of this embodiment can be used not only for the slide gate 12 of the electric furnace 11 but also for the slide gate of a ladle or a tundish. In this case, a submerged nozzle may be connected to the nozzle portion 3b (see FIG. 1) of the lower nozzle plate 1.

[0028] The above has described the configuration of the lower nozzle plate 1 of this embodiment. According to the lower nozzle plate 1 of this embodiment, the following effects are achieved.

[0029] The steel shell 7 is provided with an embracing portion 7c that covers at least a portion 5a of the downstream end face of the amorphous refractory 5 and holds the downstream end of the amorphous refractory 5, thereby preventing the amorphous refractory 5 on the outer periphery from falling off during use.

[0030] The lower nozzle plate 1 of this embodiment is particularly effective when the shaped refractory 4 on the inner peripheral side is a magnesia-carbon shaped refractory 4 having a large thermal expansion coefficient.

[0031] A zirconia plate-shaped refractory 6 is arranged in the plate portion 3a, and a magnesia-carbon shaped refractory 4 is arranged in the nozzle portion 3b, and these are surrounded by unshaped refractory 5, so that an appropriate refractory structure can be created to match the function and structure of the plate portion 3a and the nozzle portion 3b. (Lower nozzle for slide gate)

[0032] 4 shows a slide gate lower nozzle 21 (hereinafter simply referred to as the lower nozzle 21) according to one embodiment of the present invention. In the lower nozzle plate 1 of the above embodiment, the plate portion 3a and the nozzle portion 3b are integrated, whereas in the lower nozzle 21 of this embodiment, the nozzle portion is separated from the plate portion. The lower nozzle 21 is connected to a lower plate (not shown) by mortar or the like.

[0033] The lower nozzle 21 of this embodiment also includes a shaped refractory 4 in which a flow hole 4a for molten metal is formed, an unshaped refractory 5 provided around the shaped refractory 4, and a shell 7 covering the outer periphery of the unshaped refractory 5. The unshaped refractory 4 is a magnesia-carbon shaped refractory. The unshaped refractory 5 is produced by casting a refractory material (castable) having fluidity between the shaped refractory 4 and the shell 7. A part (outer diameter portion 5a) of the downstream end face of the unshaped refractory 5 is covered by the embrace portion 7c of the shell 7.

[0034] In the lower nozzle 21 of this embodiment as well, the shell 7 is provided with the embracing portion 7c, so that the monolithic refractory 5 on the outer periphery can be prevented from falling off during use. [Explanation of symbols]

[0035] 1…Lower nozzle plate for slide gate 4... Shaped refractories (magnesia-carbon shaped refractories) 4a…Flow hole 5…Unshaped refractories 5a…Part of the downstream end face of the unshaped refractory material (outer diameter part) 6... Shaped refractories (zirconia-based shaped refractories) 6a…Flow hole 6b…Sliding surface 7...Ironhide 7c…Embrace 21…Lower nozzle for slide gate

Claims

1. a shaped refractory material in which flow holes for molten metal are formed; A monolithic refractory material having a refractory aggregate and provided around the monolithic refractory material; A lower nozzle for a slide gate comprising: an iron shell covering an outer periphery of the monolithic refractory material; a casing provided with an embedding portion for covering only at least a portion of the downstream end surface of the monolithic refractory and holding the downstream end of the monolithic refractory; The lower nozzle for a slide gate, wherein the shaped refractory is made of magnesia-carbon shaped refractory.

2. A slide gate lower nozzle according to claim 1; and a zirconia plate-shaped shaped refractory material in which a flow hole for the molten metal and a sliding surface are formed, A lower nozzle plate for a slide gate, characterized in that the unshaped refractory is arranged around the plate-shaped shaped refractory.

3. A lower nozzle for a slide gate as described in claim 1, characterized in that the inner diameter portion of the downstream end face of the unshaped refractory material and the downstream end face of the embedding portion are substantially in the same plane.

Images