A tundish water inlet retaining steel groove, tundish water inlet and preparation method thereof

Abstract

The present invention provides a tundish water inlet retaining steel groove, a tundish water inlet and a preparation method. The tundish water inlet retaining steel groove comprises: a retaining steel groove body, which is an inverted groove-shaped structure with a circular arc cross section, and the two ends of the retaining steel groove body are closed, and the bottom edge of the retaining steel groove body is suitable for connecting with the working lining of the bottom of the tundish; a guide hole is provided on the circular arc side wall of the retaining steel groove body, and the retaining steel groove body is a refractory material; a blocking steel plate is arranged in the guide hole. The tundish water inlet retaining steel groove is provided with a guide hole, and a blocking steel plate is arranged in the guide hole, which can temporarily block molten steel from entering the water inlet to prevent the molten steel from freezing at the water inlet; it can also prevent large-sized inclusions from entering and blocking the water inlet; change the molten steel flow field around the water inlet to prevent eddy currents from appearing around the water inlet; avoid short-distance molten steel flow, and facilitate the inclusions in the molten steel to be adsorbed by the covering agent.

Description

Technical Field

[0001] The invention belongs to the technical field of steelmaking equipment, and in particular relates to a tundish water inlet steel retaining groove, a tundish water inlet and a preparation method thereof. Background Art

[0002] The tundish is the intermediate device that connects the ladle and the crystallizer in the steelmaking process. It has the functions of diversion, continuous casting, pressure reduction, protection and refining.

[0003] The tundish first receives the molten steel poured from the ladle, and then distributes it to each crystallizer through the tundish water outlet at the bottom. At present, in the steel casting process of the continuous casting machine, the tundish still has the following problems: 1. The molten steel from the ladle flows into the tundish through the long water outlet and flows into each tundish water outlet after being divided. The tundish often has a low online baking temperature or a low temperature of the molten steel in the ladle, resulting in cold steel at the tundish water outlet, causing the pouring to fail; 2. Large-sized inclusions in the tundish gather at the tundish water outlet, causing the tundish water outlet to be blocked; 3. The molten steel forms an eddy at the tundish water outlet, accelerating the erosion of the molten steel on the water outlet, causing the tundish to be offline early; 4. For multi-stream tundishes, the distances from the molten steel to each water outlet are not the same. For the short-distance molten steel flow, its flow path should be extended as much as possible so that the inclusions in the molten steel have enough time to float to the steel liquid surface and be adsorbed by the covering agent. The patent with publication number CN203371034U discloses a slag blocking device for the tundish water inlet, which is configured as a cylindrical structure that can be buckled on the outer ring of the water inlet bowl and is cast from magnesium oxide material. The device can prevent the residual steel slag on the cover of the tundish from falling into the water inlet due to heat during the baking process of the tundish, and at the same time avoid the problem of slag rolling at the water inlet at the initial stage of pouring, but it still cannot solve the above-mentioned problem.

[0004] Therefore, in order to improve the service life of the tundish and the quality of the ingot, a device is needed that can extend the flow path of the molten steel, prevent eddy currents from occurring at the nozzle, and avoid freezing of cold steel and inclusions blocking the nozzle. Summary of the invention

[0005] The technical problem solved by the present invention is to provide a tundish water inlet retaining steel groove, a tundish water inlet and a preparation method thereof. The tundish water inlet retaining steel groove is provided with a guide hole, and a blocking steel plate is arranged in the guide hole, which can temporarily block molten steel from entering the water inlet to prevent the molten steel from freezing at the water inlet; it can also prevent large-sized inclusions from entering and blocking the water inlet; change the molten steel flow field around the water inlet to prevent eddy currents from occurring around the water inlet; and avoid short-distance molten steel flow to facilitate the absorption of inclusions in the molten steel by a covering agent.

[0006] In order to solve the above problems, one aspect of the present invention provides a tundish water inlet retaining steel groove, comprising:

[0007] The retaining steel trough body is an inverted trough structure with a circular arc cross section, the two ends of the retaining steel trough body are closed, and the bottom edge of the retaining steel trough body is suitable for connecting with the working lining of the bottom of the tundish; the circular arc side wall of the retaining steel trough body is provided with a guide hole, and the retaining steel trough body is made of refractory material;

[0008] The blocking steel plate is arranged in the guide hole.

[0009] In the present invention, the cross section refers to a cross section perpendicular to the length direction or the axial direction of the groove of the groove-like structure.

[0010] The tundish water inlet retaining steel groove of the present invention is suitable for various tundishes that do not use stopper rods. The tundish water inlet retaining steel groove is arranged on the tundish water inlet. In the initial stage of pouring the tundish when the online baking temperature is not high or the temperature of the molten steel in the ladle is low, the molten steel with a low temperature enters the tundish that is not baked properly, causing the molten steel temperature to drop rapidly. After it is lower than the liquidus temperature of the molten steel, it will condense and cause blockage. The blocking steel plate on the guide hole provided in the tundish water inlet retaining steel groove can temporarily block the molten steel with a low temperature from entering the water inlet. The low-temperature molten steel will form cold steel outside the retaining steel groove. As a large amount of high-temperature molten steel enters, the subsequent molten steel gradually melts the cold steel and the blocking steel plate. The high-temperature molten steel can enter the water inlet through the guide hole to avoid pouring failure. At the same time, the tundish water inlet retaining steel groove is arranged on the tundish water inlet, which can also change the molten steel flow field around the water inlet, prevent the appearance of eddy currents around the water inlet, and avoid excessive erosion of the water inlet. For a multi-flow tundish in which the distances from the molten steel to each water outlet are different, the tundish water outlet steel retaining groove of the present invention can also avoid short-distance molten steel flow and extend the flow path of the molten steel as much as possible so that inclusions in the molten steel have enough time to float to the steel liquid surface and be adsorbed by the covering agent.

[0011] Preferably, the bottom edge of the steel retaining channel body is also provided with an anti-floating outer edge, and the anti-floating outer edge is suitable for being closely connected with the working lining of the bottom of the middle ladle.

[0012] The tundish water inlet retaining steel groove of the present invention is provided with an anti-floating outer edge, which is fixed on the working lining of the tundish bottom by cooperating with the fixed refractory material on the working lining of the tundish bottom, thereby compensating for the defects of easy floating and instability of the tundish water inlet retaining steel groove, and not only plays a role in the initial stage of pouring, but also can ensure stable operation in the middle and late stages of steel pouring.

[0013] Preferably, the thickness of the blocking steel plate is not greater than the thickness of the arc side wall of the steel blocking groove body, so as to avoid unnecessary extension of the tundish pouring time due to excessive thickness of the blocking steel plate.

[0014] Preferably, the bottom end of the guide hole is higher than the working lining of the tundish bottom, which can prevent large-sized inclusions from entering and blocking the water inlet, avoid the instability of the liquid level and flow field in the crystallizer, stabilize the continuous production of the continuous casting machine, and improve the quality of the ingot.

[0015] Preferably, the guide holes are in a plurality of pairs, and each pair of the guide holes are symmetrically arranged, and the symmetry plane is a plane perpendicular to the working lining of the bottom of the tundish where the axis of the steel retaining groove body is located.

[0016] Preferably, calculated by weight, the raw materials for preparing the steel retaining channel body include the following components:

[0017] 40-60 parts of forsterite particles; 30-50 parts of fused magnesium oxide particles; 7-20 parts of recycled magnesium carbon brick particles; 3-6 parts of silicon micropowder; 0.1-0.2 parts of organic fiber; 0.5-1 parts of steel fiber; 0.2-0.6 parts of water reducer.

[0018] The tundish water inlet retaining steel groove of the present invention has a main body made of the above-mentioned raw materials, which can obtain the best corrosion resistance and scouring resistance and has a longer service life.

[0019] Among them, the recycled magnesia carbon brick particles refer to the magnesia carbon brick particles obtained after the recycled waste magnesia carbon bricks are initially sorted and classified, and then the impurities attached to the bricks are removed, the slag layer and metamorphic layer of the materials are removed, crushed and ground, iron removed and homogenized, and then separated.

[0020] Preferably, the forsterite sand particles are: 20-30 parts of forsterite sand particles with a particle size of 3mm-5mm; 20-30 parts of forsterite sand particles with a particle size of 1mm-3mm.

[0021] The fused magnesium oxide particles are: 10-20 parts of DMS-91 particles with a particle size of 0.083mm-1mm; 20-30 parts of DMS-95 particles with a particle size of ≤0.074mm. The DMS-91 particles and DMS-95 particles are fused magnesium oxide formed by heating and melting pure natural magnesia and light-burned magnesium powder in an electric arc furnace and naturally cooling the melt. DMS-91 and DMS-95 are two grades of products with different physical and chemical indicators such as magnesium content and bulk density.

[0022] The recycled magnesia carbon brick particles are: 5-15 parts of recycled magnesia carbon brick particles with a particle size of 0.083mm-1mm; 2-5 parts of recycled magnesia carbon brick particles with a particle size of ≤0.074mm.

[0023] When the above-mentioned particle size grading is adopted, the obtained tundish water inlet retaining steel trough product can have better corrosion resistance and scour resistance.

[0024] The water reducing agent is: 0.1-0.3 parts of sodium tripolyphosphate; 0.1-0.3 parts of sodium hexametaphosphate.

[0025] Another aspect of the present invention provides a method for preparing the above-mentioned tundish water inlet retaining steel groove, comprising the following steps:

[0026] Mixing the raw materials for preparing the steel retaining channel body according to the selected mass fractions;

[0027] In the mold, the blocking steel plate is pre-buried at the guide hole of the blocking steel groove body;

[0028] The mixed raw materials are cast into the mold after the blocking steel plate is pre-embedded to obtain the tundish water inlet blocking steel groove.

[0029] Another aspect of the present invention provides a tundish nozzle, comprising:

[0030] Tundish nozzle body;

[0031] The above-mentioned tundish water inlet retaining steel groove is arranged above the tundish water inlet body, and the bottom edge of the tundish water inlet retaining steel groove is connected to the tundish bottom working lining.

[0032] Preferably, the bottom edge of the steel retaining trough body is also provided with an anti-floating outer edge, the anti-floating outer edge is in contact with the working lining of the middle ladle bottom, and is connected to the working lining of the middle ladle bottom via a fixing member provided on the anti-floating outer edge.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] 1. The tundish water inlet retaining steel groove of the present invention is suitable for various tundishes that do not use stopper rods. The tundish water inlet retaining steel groove is arranged on the tundish water inlet. In the early stage of pouring the tundish when the online baking temperature is not high or the temperature of the molten steel in the ladle is low, the molten steel with a low temperature enters the tundish that is not baked in place, causing the molten steel temperature to drop rapidly. When it is lower than the liquidus temperature of the molten steel, it will condense and cause blockage. The retaining steel plate on the guide hole provided in the tundish water inlet retaining steel groove can temporarily prevent the molten steel with a low temperature from entering the water inlet. The low-temperature molten steel will condense on the outside of the retaining steel groove. With a large amount of high-temperature molten steel Entering, the subsequent molten steel gradually melts the cold steel and the blocking steel plate, and the high-temperature molten steel can enter the water inlet through the guide hole to avoid pouring failure; at the same time, the tundish water inlet retaining steel groove is set on the tundish water inlet, which can also change the molten steel flow field around the water inlet, prevent the appearance of eddy currents around the water inlet, and avoid excessive erosion of the water inlet; for a multi-flow tundish with different distances from the molten steel to each water inlet, the tundish water inlet retaining steel groove of the present invention can also avoid short-distance molten steel flow and extend the flow path of the molten steel as much as possible, so that the inclusions in the molten steel have enough time to float to the steel liquid surface and be adsorbed by the covering agent.

[0035] 2. The tundish water inlet retaining steel trough of the present invention is also provided with an anti-floating outer edge, which is fixed on the working lining of the bottom of the tundish by cooperating with the fixed refractory material on the working lining of the bottom of the tundish, thereby compensating for the defects of easy floating and instability of the tundish water inlet retaining steel trough, and not only plays a role in the initial stage of pouring, but also can ensure stable operation in the middle and late stages of steel pouring.

[0036] 3. The tundish water inlet retaining steel trough of the present invention can have the best corrosion resistance and scour resistance and a longer service life by optimizing the composition and particle size distribution of the raw materials used to prepare the steel trough body. At the same time, recycled magnesia carbon brick particles are also used in the preparation of the raw materials, which can greatly reduce the production cost of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 Schematic diagram of the tundish water inlet retaining steel groove after installation according to Embodiment 1 of the present invention;

[0038] Figure 2 is a side cross-sectional view of the tundish water inlet retaining steel groove according to Example 1 of the present invention;

[0039] Figure 3 1 is a front view of the tundish water inlet retaining steel groove according to Example 1 of the present invention;

[0040] Figure 4 It is a top view of the tundish water inlet retaining steel groove described in Example 1 of the present invention.

[0041] Among them: 1-steel trough body; 2-stop steel plate; 3-fixed refractory material; 4-anti-floating outer edge; 5-working lining of the bottom of the tundish; 6-main body of the tundish nozzle. DETAILED DESCRIPTION

[0042] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solution of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0043] Example 1

[0044] like Figure 1 , 2 As shown in , 3 and 4 , the tundish water inlet retaining steel groove described in this embodiment includes a retaining steel groove body 1 and a retaining steel plate 2.

[0045] The retaining steel trough body 1 is an inverted trough structure with an arc cross section. Both ends of the retaining steel trough body 1 are closed. The bottom edge of the retaining steel trough body 1 is provided with an anti-floating outer edge 4, and the anti-floating outer edge 4 is suitable for being fitted and connected with the working lining 5 of the bottom of the tundish. The arc side wall of the retaining steel trough body 1 is provided with 4 (2 pairs) diversion holes, and each pair of diversion holes is symmetrically arranged. The symmetry plane is the plane where the axis of the retaining steel trough body is located and is perpendicular to the working lining of the bottom of the tundish. The height of the bottom ends of the 4 diversion holes is higher than the height of the working lining of the bottom of the tundish.

[0046] The blocking steel plate 2 is arranged in the guide hole, and the thickness of the blocking steel plate is not greater than the thickness of the arc side wall of the blocking steel groove body.

[0047] Among them, the raw materials for preparing the steel retaining channel body include the following components calculated by mass:

[0048] 25 parts of forsterite sand particles with a particle size of 3mm-5mm; 20 parts of forsterite sand particles with a particle size of 1mm-3mm; 15 parts of DMS-91 particles with a particle size of 0.083mm-1mm; 20 parts of DMS-95 particles with a particle size of ≤0.074mm; 10 parts of recycled magnesia carbon brick particles with a particle size of 0.083mm-1mm; 3 parts of recycled magnesia carbon brick particles with a particle size of ≤0.074mm; 4 parts of silicon micropowder; 0.1 part of organic fiber; 0.7 part of steel fiber; 0.15 part of sodium tripolyphosphate; 0.15 part of sodium hexametaphosphate.

[0049] The method for preparing the tundish water inlet retaining steel groove of the present embodiment comprises the following steps:

[0050] S1. According to the selected mass fraction, the raw materials for preparing the steel trough body are mixed;

[0051] S2. In the mold, a blocking steel plate is embedded in the guide hole of the main body of the steel groove;

[0052] S3. The mixed raw materials are cast into a mold with a pre-embedded blocking steel plate to obtain a tundish water inlet blocking steel groove.

[0053] Example 2

[0054] The tundish water inlet described in this embodiment includes a tundish water inlet main body 6 and a tundish water inlet retaining steel groove. The structure of the tundish water inlet retaining steel groove is the same as that of Example 1. The tundish water inlet retaining steel groove is arranged above the tundish water inlet main body 6. The anti-floating outer edge 4 on the bottom side of the tundish water inlet retaining steel groove is in contact with the working lining of the bottom of the tundish, and is connected to the working lining 5 of the bottom of the tundish through the fixed refractory material 3 arranged on the anti-floating outer edge 4.

[0055] Example 3

[0056] The structure of the tundish water inlet retaining groove described in this embodiment is the same as that of the embodiment 1, except that the raw materials for preparing the retaining groove body include the following components calculated by weight:

[0057] 20 parts of forsterite sand particles with a particle size of 3mm-5mm; 30 parts of forsterite sand particles with a particle size of 1mm-3mm; 10 parts of DMS-91 particles with a particle size of 0.083mm-1mm; 30 parts of DMS-95 particles with a particle size of ≤0.074mm; 15 parts of recycled magnesia carbon brick particles with a particle size of 0.083mm-1mm; 5 parts of recycled magnesia carbon brick particles with a particle size of ≤0.074mm; 3 parts of silicon micropowder; 0.2 parts of organic fiber; 0.5 parts of steel fiber; 0.1 parts of sodium tripolyphosphate; 0.3 parts of sodium hexametaphosphate.

[0058] The preparation method is the same as that in Example 1.

[0059] Example 4

[0060] The structure of the tundish water inlet retaining groove described in this embodiment is the same as that of the embodiment 1, except that the raw materials for preparing the retaining groove body include the following components calculated by weight:

[0061] 30 parts of forsterite sand particles with a particle size of 3mm-5mm; 25 parts of forsterite sand particles with a particle size of 1mm-3mm; 20 parts of DMS-91 particles with a particle size of 0.083mm-1mm; 25 parts of DMS-95 particles with a particle size of ≤0.074mm; 5 parts of recycled magnesia carbon brick particles with a particle size of 0.083mm-1mm; 2 parts of recycled magnesia carbon brick particles with a particle size of ≤0.074mm; 6 parts of silicon micropowder; 0.15 parts of organic fiber; 1 part of steel fiber; 0.3 parts of sodium tripolyphosphate; 0.1 parts of sodium hexametaphosphate.

[0062] The preparation method is the same as that in Example 1.

[0063] Example 5

[0064] The structure of the tundish water inlet retaining groove described in this embodiment is the same as that of the embodiment 1, except that the raw materials for preparing the main body of the retaining groove include the following components calculated by weight:

[0065] 10 parts of forsterite sand particles with a particle size of 3mm-5mm; 40 parts of forsterite sand particles with a particle size of 1mm-3mm; 5 parts of DMS-91 particles with a particle size of 0.083mm-1mm; 35 parts of DMS-95 particles with a particle size of ≤0.074mm; 20 parts of recycled magnesia carbon brick particles with a particle size of 0.083mm-1mm; 1 part of recycled magnesia carbon brick particles with a particle size of ≤0.074mm; 8 parts of silicon micropowder; 0.05 parts of organic fiber; 1.5 parts of steel fiber; 0.2 parts of sodium tripolyphosphate; 0.4 parts of sodium hexametaphosphate.

[0066] The preparation method is the same as that in Example 1.

[0067] Example 6

[0068] The structure of the tundish water inlet retaining groove described in this embodiment is the same as that of the embodiment 1, except that the raw materials for preparing the main body of the retaining groove include the following components calculated by weight:

[0069] 40 parts of forsterite sand particles with a particle size of 3mm-5mm; 10 parts of forsterite sand particles with a particle size of 1mm-3mm; 25 parts of DMS-91 particles with a particle size of 0.083mm-1mm; 15 parts of DMS-95 particles with a particle size of ≤0.074mm; 3 parts of recycled magnesia carbon brick particles with a particle size of 0.083mm-1mm; 7 parts of recycled magnesia carbon brick particles with a particle size of ≤0.074mm; 2 parts of silicon micropowder; 0.25 parts of organic fiber; 0.2 parts of steel fiber; 0.4 parts of sodium tripolyphosphate; 0.05 parts of sodium hexametaphosphate.

[0070] The preparation method is the same as that in Example 1.

[0071] The production line of a small square billet casting machine in a steel plant adopts a quick-change slider without a stopper to control the flow. Because the molten steel is not refined, the temperature of the molten steel cannot be accurately controlled. In addition, the baking effect of the tundish baking device is not ideal. Before using the tundish water inlet retaining steel groove, the molten steel is often superheated or the lining temperature of the tundish is low, causing the molten steel to freeze at the upper end and inner wall of the water inlet 6, or large-sized refractory materials fall into the tundish to block the water inlet 6, resulting in an accident of failure to start pouring; or under normal steel pouring, the water inlet corresponding to the short-process molten steel is affected by the erosion of the molten steel and the eddy current around the water inlet, causing the water inlet to erode too quickly and the life is short, resulting in an average life of the tundish of less than 24 hours. After installing the tundish water inlet retaining steel groove of the present invention, the monthly tundish pouring rate of the casting machine has been greatly improved, and the average life has also been greatly improved, achieving considerable economic benefits. Among them, Examples 1, 3, and 4 are preferred implementations. Compared with Examples 5 and 6, their comprehensive strength performance is better and the life of the water inlet is longer. Specific test data are shown in Tables 1 and 2 below.

[0072] Table 1: Physical and chemical parameters of the water inlet retaining steel groove in some embodiments

[0073]

[0074] Table 2: Usage parameters of the water inlet retaining steel groove in some embodiments

[0075]

[0076] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. A tundish water inlet retaining steel groove, characterized in that: include: The retaining steel trough body is an inverted trough structure with a circular arc cross section, the two ends of the retaining steel trough body are closed, and the bottom edge of the retaining steel trough body is suitable for connecting with the working lining of the bottom of the tundish; the circular arc side wall of the retaining steel trough body is provided with a guide hole, and the retaining steel trough body is made of refractory material; A blocking steel plate is arranged in the diversion hole; The bottom edge of the steel retaining groove body is also provided with an anti-floating outer edge, and the anti-floating outer edge is suitable for being closely connected with the working lining of the bottom of the tundish; Calculated by weight, the raw materials for preparing the steel retaining channel body include the following components: 40-60 parts of forsterite particles; 30-50 parts of fused magnesium oxide particles; 7-20 parts of recycled magnesium carbon brick particles; 3-6 parts of silicon powder; 0.1-0.2 parts of organic fiber; 0.5-1 parts of steel fiber; 0.2-0.6 parts of water reducer; The forsterite sand particles are: 20-30 parts of forsterite sand particles with a particle size of 3mm-5mm; 20-30 parts of forsterite sand particles with a particle size of 1mm-3mm; The fused magnesium oxide particles are: 10-20 parts of DMS-91 particles with a particle size of 0.083 mm-1 mm; 20-30 parts of DMS-95 particles with a particle size of ≤0.074 mm; The recycled magnesia carbon brick particles are: 5-15 parts of recycled magnesia carbon brick particles with a particle size of 0.083mm-1mm; 2-5 parts of recycled magnesia carbon brick particles with a particle size of ≤0.074mm; The mixed raw materials are cast into a mold with a pre-embedded blocking steel plate to obtain a tundish water inlet blocking steel groove.

2. The tundish water inlet retaining steel groove according to claim 1, characterized in that: The thickness of the blocking steel plate is not greater than the thickness of the arc side wall of the blocking steel groove body.

3. The tundish water inlet retaining steel groove according to claim 1, characterized in that: The height of the bottom end of the guide hole is higher than the height of the working lining of the tundish bottom.

4. The tundish water inlet retaining steel groove according to claim 1, characterized in that: The guide holes are in pairs, and each pair of the guide holes is symmetrically arranged, and the symmetry plane is the plane where the axis of the steel retaining groove body is located and is perpendicular to the working lining of the bottom of the tundish.

5. The tundish water inlet retaining steel groove according to claim 1, characterized in that: The water reducing agent is: 0.1-0.3 parts of sodium tripolyphosphate; 0.1-0.3 parts of sodium hexametaphosphate.

6. A method for preparing the tundish water inlet retaining steel groove as claimed in any one of claims 1 to 5, characterized in that: The following steps are involved: Mixing the raw materials for preparing the steel retaining channel body according to the selected mass fractions; In the mold, the blocking steel plate is pre-buried at the guide hole of the blocking steel groove body; The mixed raw materials are cast into the mold after the blocking steel plate is pre-embedded to obtain the tundish water inlet blocking steel groove.

7. A tundish nozzle, characterized in that: include: Tundish nozzle body; The tundish water inlet retaining steel groove as described in any one of claims 1 to 5 is arranged above the tundish water inlet body, and the bottom edge of the tundish water inlet retaining steel groove is connected to the tundish bottom working lining.

8. The tundish nozzle according to claim 7, characterized in that: The bottom edge of the steel retaining trough body is also provided with an anti-floating outer edge, which fits the working lining of the middle ladle bottom and is connected to the working lining of the middle ladle bottom through a fixing piece provided on the anti-floating outer edge.

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