Novel composite submersed nozzle and manufacturing method thereof

Abstract

The invention discloses an integrated novel composite submersed nozzle and a manufacturing method thereof, and the integrated novel composite submersed nozzle comprises a nozzle body made of Al2O3-C; the slag line layer is embedded in the middle lower part of the nozzle body and is made of ZrO2-C; the anti-blocking lining is arranged on the inner wall of the nozzle body and is made of Al2O3-ZrO2-C; the breathable electrode is buried in the middle-upper part in the nozzle body and is a heat-resistant stainless steel pipe, and a plurality of air holes are formed in the pipe wall, close to one side of the anti-blocking lining, of the breathable electrode; the heat-resistant stainless steel pipe is made of heat-resistant stainless steel containing one or more of Cr, Ni, Mo and Al. In the continuous casting process, the technical effect that argon blowing and external electric field applying are conducted on the submersed nozzle at the same time is achieved, the problems of nodulation and blocking in the nozzle are effectively solved, and meanwhile the effect of inhibiting electrode oxidation is achieved. The preparation method is simple, the damage of traditional argon blowing and electric field applying to an original water gap structure is avoided, and the threat of the influence of manual operation to the safety of the water gap and continuous casting production is also avoided.

Description

Technical Field

[0001] The invention relates to the fields of continuous casting and refractory materials, and in particular to a novel composite submerged nozzle and a manufacturing method thereof. Background Art

[0002] As one of the three key functional refractory materials in continuous casting, the submerged nozzle not only serves as a connecting channel between the tundish and the mold, but also prevents oxidation and splashing of the molten steel, regulates the flow of the molten steel within the mold, and prevents slag entanglement. Therefore, the service safety and stability of the submerged nozzle are crucial to the entire continuous casting process and the quality of the cast strands. To meet the production requirements of continuous casting, the submerged nozzle must not only exhibit excellent performance such as resistance to high temperatures, thermal shock, slag intrusion, and erosion, but also possess a reasonable structure to ensure stable molten steel flow.

[0003] However, at present, submerged nozzles are very prone to internal nodules and blockages during continuous casting, which not only seriously affects the smooth flow and efficiency of continuous casting, but also poses a threat to production. In order to solve the problem of internal nodules and blockages in submerged nozzles during continuous casting, relevant technicians in this field have also carried out a lot of research work and technical attempts, such as changing the nozzle material, adding anti-clogging linings, optimizing the smelting process, and applying physical fields. However, the problem of internal nodules and blockages in submerged nozzles has not been effectively solved so far.

[0004] In recent years, relevant studies have found that applying an electric field or blowing argon on the inner wall of the immersed nozzle can effectively improve the nodule and blockage problems of the nozzle itself. However, the existing related technical methods are too complicated, and the nozzle needs to be processed twice and buried before continuous casting. And the process of constructing an electric field for the nozzle material is also very cumbersome. During the continuous casting process, professional technicians are required to specify the electric field circuit construction plan according to the actual production conditions on site, and the continuous casting workers must also complete the construction of the electric field under professional technical guidance. Even so, a lot of manpower and time are still required in the actual operation process, and once a mistake is made, it may cause fundamental damage to the nozzle, and it also brings potential safety risks to the safe production of the continuous casting site. Therefore, the original technical method is not suitable for existing continuous casting production, and cannot meet the large-scale promotion of this technology. Summary of the Invention

[0005] The purpose of the present invention is to provide a new type of composite submerged nozzle and a manufacturing method thereof. This method adds a spiral breathable steel pipe as a breathable electrode to the traditional submerged nozzle structure, thereby achieving the technical effect of simultaneously blowing argon and applying an external electric field to the submerged nozzle during the continuous casting process, thereby effectively suppressing the problems of nodules and blockages inside the nozzle, and at the same time, suppressing the oxidation of the breathable electrode.

[0006] To achieve the above objectives, the technical solutions of the present invention are as follows:

[0007] A novel composite submerged nozzle, comprising:

[0008] The nozzle body is made of Al2O3-C;

[0009] The slag line layer is embedded in the middle and lower part of the nozzle body and its material is ZrO2-C;

[0010] Anti-clogging lining, set on the inner wall of the nozzle body, its material is Al2O3-ZrO2-C;

[0011] The breathable electrode is buried in the middle and upper part of the nozzle body. The breathable electrode is a heat-resistant stainless steel tube. A plurality of air holes are provided on the tube wall close to the anti-clogging lining. The heat-resistant stainless steel tube is made of heat-resistant stainless steel containing one or more of Cr, Ni, Mo, and Al.

[0012] Preferably, the air-permeable electrodes are arranged in a spiral manner inside the nozzle body.

[0013] Preferably, the height of the air-permeable electrode in the nozzle body is 50 to 130 cm, the inner diameter of the heat-resistant stainless steel tube is 0.3 to 0.5 cm, and the outer diameter is 0.8 to 1.3 cm.

[0014] Preferably, the spacing between the pores on the air-permeable electrode is 2 to 4 cm, and the diameter of the pores is 0.1 to 0.5 cm.

[0015] Preferably, the anti-clogging lining has a thickness of 0.5 to 1 cm.

[0016] Preferably, the inner diameter of the water outlet is 5 to 15 cm.

[0017] The manufacturing method of the novel composite submerged nozzle of the present invention comprises the following steps:

[0018] 1) Lining molding

[0019] Determine the inner diameter of the nozzle according to the continuous casting conditions and requirements; add the anti-clogging lining material and the resin binder into the mold and press-form to obtain the anti-clogging lining;

[0020] 2) Pretreatment of breathable electrodes

[0021] A layer of phenolic resin binder is uniformly coated on the surface of the gas permeable electrode, and then graphite powder and metal powder are evenly mixed and pressed onto the phenolic resin as a protective layer; the mass ratio of the graphite powder to the metal powder is 0.1 to 0.2:1, and the metal powder is chromium, aluminum, or nickel, preferably chromium;

[0022] 3) Body and slag line forming

[0023] In the isostatic pressing equipment, anti-clogging lining, nozzle body material, slag line material and resin binder are sequentially added, and during the filling process, the pre-treated air-permeable electrode is placed inside the nozzle body, and pressed into shape to obtain a formed nozzle;

[0024] 4) Positioning grooving and installing external pipes

[0025] Determine the position and opening direction of the buried air-permeable electrode, open a hole on the side wall of the nozzle body to expose the air-permeable electrode port, then connect a heat-resistant stainless steel tube with the same material and diameter as the air-permeable electrode to the air-permeable electrode port, and then use alumina-based inorganic refractory glue to seal the groove to obtain the finished immersion nozzle.

[0026] Preferably, the coating thickness of the phenolic resin is ≤0.15 cm, and the thickness of the protective layer is 0.3-0.5 cm.

[0027] Preferably, the outside of the immersion nozzle is wrapped with insulation material with a thickness of 0.4 cm to 0.8 cm.

[0028] Preferably, the thermal insulation material is refractory wool made of alumina fiber.

[0029] Although the single nozzle argon blowing and electric treatment technology can improve the nozzle blockage problem to a certain extent, its control effect is still relatively limited and cannot be fully exerted when casting steel grades that are extremely prone to blockage.

[0030] The present invention installs a permeable electrode inside the submerged nozzle. During the continuous casting process, argon blowing and electric field application can be performed simultaneously through the permeable electrode. While the argon gas is generally at a relatively low temperature, the temperature of the argon gas blown into the nozzle's inner wall and contacting the molten steel increases during passage through the permeable electrode due to factors such as power supply and the nozzle's own thermal conductivity. This technical advantage effectively avoids the problems associated with traditional direct argon blowing, such as excessively low nozzle wall temperatures and the tendency of solidified steel to adhere to the inner wall. Furthermore, during this process, the blown argon gas also protects the permeable electrode, effectively preventing oxidation and ensuring that the electrode material temperature does not rise excessively.

[0031] The existing technical solutions usually involve modifying and electrifying ordinary argon blowing nozzles, which are affected by human operation and pose a threat to the nozzle and continuous casting production safety.

[0032] During the nozzle preparation process, the present invention directly combines the nozzle argon blowing system with the powered electrode, which is then embedded in the nozzle to form an integral part. This effectively reduces the damage to the original nozzle structure caused by processes such as nozzle argon blowing and nozzle electrification in existing technical solutions. The method described in the present invention is also more convenient and precise to operate, effectively reducing errors caused by human factors and reducing the technical operational difficulty and complexity associated with on-site continuous casting processes. This method promotes the promotion, popularization, and application of related nozzle, nozzle argon blowing, and external electric field control of nozzle nodule blockage technologies in continuous casting processes.

[0033] During the preparation process of the present invention, a layer of phenolic resin binder is coated on the outside of the breathable electrode to adhere the graphite and metal powder protective layer, which can effectively improve the technical effect of applying an electric field during the continuous casting process and prevent the electrode material from being damaged by problems such as negative pressure in the nozzle and oxidation. During the continuous casting process, graphite and metal powder will also react with the electrode surface at high temperature to enhance the hardness, strength and heat resistance of the electrode itself, while also improving the compatibility between the electrode material and the nozzle material. These gain effects will also effectively resist the damage to the breathable electrode caused by problems such as high temperature and thermal shock, thereby ensuring that the nozzle material can serve stably and efficiently during the continuous casting process. It is ensured that a uniform and stable external electric field can be applied to the inner wall of the nozzle during the continuous casting process, thereby inhibiting the adhesion of inclusions in the steel to the inner wall of the nozzle, and the reaction of alloys in the steel on the inner wall of the nozzle, which may lead to nozzle nodules and blockage problems.

[0034] The present invention adopts a spiral breathable steel pipe as the nozzle argon blowing device and electrode material, which can not only effectively improve the nozzle argon blowing effect, but also improve the electric field effect. First of all, the submerged nozzle, as a carbon-containing refractory material, itself also has a certain air permeability. The spiral breathable steel pipe and the uniform air holes can effectively ensure that the blown argon flows out evenly on the inner wall of the nozzle, forming a uniform protective air film on the inner wall of the nozzle, and preventing inclusions from adhering to form nozzle nodules. Secondly, the spiral electrode can also ensure the electric field application effect and the uniformity of the electric field distribution during the continuous casting process, and this method can also ensure that the Joule heat generated by the electrode during the power-on process can be effectively dissipated, preventing the nozzle from being locally overheated, or the nozzle from being rapidly oxidized due to the temperature rise, or the nozzle from being thermally fractured due to excessive temperature difference.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] The gas-permeable electrode installed in the nozzle body of the present invention can simultaneously perform argon blowing and apply an electric field. Compared with the method of separately applying argon blowing and electric field application in the prior art, it can avoid the problem of the inner wall of the nozzle being too low due to direct argon blowing, which makes it easy for solidified steel to adhere to the inner wall of the nozzle, and further better solve the problems of nozzle nodules and blockages; at the same time, argon gas around the gas-permeable electrode can effectively prevent electrode oxidation, ensure that the temperature of the electrode material does not rise excessively, and extend the service life of the gas-permeable electrode.

[0037] During the nozzle manufacturing process, the present invention pre-buries a permeable electrode with argon blowing and electric field application functions inside the nozzle. This can avoid the damage to the original nozzle structure caused by existing technical solutions such as nozzle argon blowing and nozzle electrification. In the traditional modification process, it will be affected by human operation and pose a threat to the nozzle and continuous casting production safety. The method described in the present invention is more convenient and accurate to operate, effectively improving the errors caused by human factors and reducing the technical operation difficulty and complexity brought about by the on-site continuous casting process. It promotes the promotion, popularization and application of related nozzles, nozzle argon blowing, external electric field control of nozzle agglomeration and blockage technologies in the continuous casting process. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a schematic diagram of the overall structure of the nozzle of the present invention.

[0039] Figure 2 This is a schematic diagram of the installation position of the air-permeable electrode in the nozzle of the present invention. DETAILED DESCRIPTION

[0040] The present invention will be further described below with reference to the embodiments and accompanying drawings.

[0041] See also Figure 1 、 Figure 2 The novel composite submerged nozzle of the present invention comprises:

[0042] The nozzle body 1 is made of Al2O3-C;

[0043] Slag line layer 2, embedded in the middle and lower part of the nozzle body, its material is ZrO2-C;

[0044] The anti-clogging lining 3 is arranged on the inner wall of the nozzle body 1 and its material is Al2O3-ZrO2-C;

[0045] The air-permeable electrode 4 is buried in the middle and upper part of the nozzle body 1. The air-permeable electrode is a heat-resistant stainless steel tube, and a plurality of air holes are provided on the tube wall close to the anti-clogging lining. The heat-resistant stainless steel tube is made of heat-resistant stainless steel containing one or more of Cr, Ni, Mo, and Al.

[0046] Preferably, the air-permeable electrodes 4 are arranged in a spiral manner inside the nozzle body.

[0047] Preferably, the height of the air-permeable electrode 4 in the nozzle body is 50-130 cm, the inner diameter of the heat-resistant stainless steel tube is 0.3-0.5 cm, and the outer diameter is 0.8-1.3 cm.

[0048] Preferably, the pore spacing on the air permeable electrode 4 is 2 to 4 cm, and the pore diameter is 0.1 to 0.5 cm.

[0049] Preferably, the anti-clogging lining 3 has a thickness of 0.5 to 1 cm.

[0050] Preferably, the inner diameter of the water outlet is 5 to 15 cm.

[0051] Example 1

[0052] This embodiment takes the submerged nozzle of slab continuous casting in a steel plant as the object. During the experiment, the submerged nozzle of control group 1 adopts the normal casting nozzle to blow argon through the conventional argon blowing method, the submerged nozzle of control group 2 adopts the normal casting nozzle to apply the electric field through the conventional electric field application method, the submerged nozzle of control group 3 adopts the normal casting nozzle to simultaneously blow argon and apply the electric field, and the experimental group adopts the nozzle described in the present invention to simultaneously blow argon and apply the electric field.

[0053] The inner diameter of the nozzle is determined according to the continuous casting conditions and requirements, and the anti-clogging lining material and resin binder are added to the mold for pressing and molding to obtain the anti-clogging lining; wherein, the thickness of the anti-clogging lining is 0.7 cm, the inner diameter of the nozzle is 10 cm, and the anti-clogging lining material is Al2O3-ZrO2-C.

[0054] A layer of phenolic resin binder is uniformly coated on the surface of the breathable electrode, and then graphite powder and metal powder are evenly mixed and pressed onto the phenolic resin as a protective layer to obtain a pretreated breathable electrode; the coating thickness of the phenolic resin is ≤0.15 cm, and the thickness of the protective layer is 0.45 cm; the mass ratio of the graphite powder to the metal powder is 0.1:1, and the metal powder is metallic chromium, metallic aluminum, or metallic nickel, preferably metallic chromium. The breathable electrode is a 06Cr25Ni20 heat-resistant stainless steel tube with an inner diameter of 0.4 cm, an outer diameter of 0.95 cm, and a height of 65 cm. The pore spacing on the stainless steel tube is 2.5 cm, and the pore diameter is 0.5 cm.

[0055] The anti-clogging lining, nozzle body material Al2O3-C, slag line material ZrO2-C and resin binder are added to the isostatic pressing equipment in sequence. During the filling process, the pretreated breathable electrode is placed inside the nozzle body and pressed into shape to obtain a formed nozzle.

[0056] A metal detection device is used to determine the position and opening direction of the buried air-permeable electrode, and a groove is opened from the outside of the water outlet to expose the air-permeable electrode gate. Then, a steel pipe with the same material and diameter as the air-permeable electrode is connected to the air-permeable electrode gate, and then an alumina-based inorganic refractory adhesive is used to seal the groove and the connection point to obtain an immersed water outlet.

[0057] Finally, refractory wool made of alumina fiber is wrapped around the outer wall of the submerged nozzle to protect the entire nozzle during the continuous casting process. The thickness of the refractory wool is 0.7 cm.

[0058] During the experiment, the experimental and control groups were subjected to identical control conditions, except for the application of an electric field and the use of argon. After the experiment, nozzle sampling and analysis revealed that the thickness of the internal nodule layer in the experimental group was reduced by 24-51%, 15-30%, and 15-20%, respectively, compared to control groups 1, 2, and 3. The thickness of the electrode oxide layer in the experimental group decreased by 50-70% and 45-65%, respectively, compared to control groups 2 and 3.

[0059] Example 2

[0060] In this embodiment, the nozzle in the continuous casting process of small square billets in a certain steel plant is taken as the research object. The control group 1 submerged nozzle adopts the normal casting nozzle to blow argon through the conventional argon blowing method, the control group 2 submerged nozzle adopts the normal casting nozzle to apply the electric field through the conventional electric field application method, the control group 3 submerged nozzle adopts the normal casting nozzle to simultaneously blow argon and apply the electric field, and the experimental group adopts the nozzle described in the present invention to simultaneously blow argon and apply the electric field.

[0061] First, according to the on-site production requirements, the anti-clogging lining material and the resin binder are added to the mold and pressed into shape to obtain the anti-clogging lining; wherein the thickness of the lining is 0.5 cm, the inner diameter of the nozzle is 8 cm, and the anti-clogging lining material is Al2O3-ZrO2-C;

[0062] The surface of the permeable electrode is evenly coated with a phenolic resin binder. Graphite powder and metallic chromium powder are then mixed and pressed onto the phenolic resin as a protective layer. The graphite powder and metallic chromium powder are mixed in a mass ratio of 1:10. The phenolic resin coating is no thicker than 0.15 cm, and the protective layer is 0.35 cm thick. The permeable electrode is primarily constructed from a spiral, permeable steel tube with an inner diameter of 0.3 cm, an outer diameter of 0.8 cm, and a height of 60 cm. Air holes are provided every 3 cm, each with a diameter of 0.5 cm. The steel tube is made of 06Cr25Ni20 high-performance, heat-resistant steel.

[0063] The anti-clogging lining, nozzle body material Al2O3-C, slag line material ZrO2-C and resin binder are added to the isostatic pressing equipment in sequence. During the filling process, the pretreated breathable electrode is placed inside the nozzle body and pressed into shape to obtain a formed nozzle.

[0064] A metal detection device is used to determine the position and opening direction of the buried air-permeable electrode, and a groove is opened on the side wall of the nozzle body to expose the air-permeable electrode port. Then, a heat-resistant stainless steel tube with the same material and diameter as the air-permeable electrode is connected to the air-permeable electrode port, and then an alumina-based inorganic refractory glue is used to seal the groove to obtain the finished immersion nozzle.

[0065] After forming, a metal detector is used to determine the location and opening direction of the buried permeable electrode. A spiral groove is then cut from the outside of the nozzle. A steel pipe with the same material and diameter as the permeable electrode is then inserted into the nozzle, and the spiral opening of the permeable electrode is connected.

[0066] Finally, the outer wall of the nozzle is wrapped with refractory wool made of alumina fiber to protect the nozzle as a whole during the continuous casting process. The insulation material is wrapped with a thickness of 0.5 cm.

[0067] During the experiment, the experimental and control groups were subjected to identical control conditions, except for the applied electric field and argon blowing. After the experiment, nozzle sampling and analysis revealed that the thickness of the internal nodule layer in the experimental group was reduced by 30-45%, 20-35%, and 10-15% compared to control groups 1, 2, and 3, respectively. The thickness of the electrode oxide layer in the experimental group decreased by 40-60% and 36-52% compared to control groups 2 and 3, respectively.

Claims

1. A new type of composite submerged nozzle, characterized in that: include: The nozzle body is made of Al2O3-C; The slag line layer is embedded in the middle and lower part of the nozzle body and its material is ZrO2-C; Anti-clogging lining, set on the inner wall of the nozzle body, its material is Al2O3-ZrO2-C; The breathable electrode is buried in the middle and upper part of the nozzle body. The breathable electrode is a heat-resistant stainless steel tube. A plurality of air holes are provided on the tube wall close to the anti-clogging lining. The heat-resistant stainless steel tube is made of heat-resistant stainless steel containing one or more of Cr, Ni, Mo, and Al.

2. The novel composite submerged nozzle according to claim 1, characterized in that: The air-permeable electrodes are arranged in a spiral manner inside the nozzle body.

3. The novel composite submerged nozzle according to claim 1 or 2, characterized in that: The height of the air-permeable electrode in the nozzle body is 50-130 cm, the inner diameter of the heat-resistant stainless steel tube is 0.3-0.5 cm, and the outer diameter is 0.8-1.3 cm.

4. The novel composite submerged nozzle according to claim 1, 2 or 3, characterized in that: The air hole spacing on the air permeable electrode is 2-4 cm, and the air hole diameter is 0.1-0.5 cm.

5. The novel composite submerged nozzle according to claim 1, characterized in that: The anti-clogging lining has a thickness of 0.5 to 1 cm.

6. The novel composite submerged nozzle according to claim 1, 2, 3, 4 or 5, characterized in that: The inner diameter of the water outlet is 5 to 15 cm.

7. The method for manufacturing the novel composite submerged nozzle according to any one of claims 1 to 6, characterized in that: The steps include: 1) Lining molding Determine the inner diameter of the nozzle according to the continuous casting conditions and requirements; add the anti-clogging lining material and the resin binder into the mold and press-form to obtain the anti-clogging lining; 2) Pretreatment of breathable electrodes A layer of phenolic resin binder is uniformly coated on the surface of the gas permeable electrode, and then graphite powder and metal powder are evenly mixed and pressed onto the phenolic resin as a protective layer; the mass ratio of the graphite powder to the metal powder is 0.1 to 0.2:1, and the metal powder is chromium, aluminum, or nickel, preferably chromium; 3) Body and slag line forming In the isostatic pressing equipment, anti-clogging lining, nozzle body material, slag line material and resin binder are sequentially added, and during the filling process, the pre-treated air-permeable electrode is placed inside the nozzle body, and pressed into shape to obtain a formed nozzle; 4) Positioning grooving and installing external pipes Determine the position and opening direction of the buried air-permeable electrode, open a hole on the side wall of the nozzle body to expose the air-permeable electrode port, then connect a heat-resistant stainless steel tube with the same material and diameter as the air-permeable electrode to the air-permeable electrode port, and then use alumina-based inorganic refractory glue to seal the groove to obtain the finished immersion nozzle.

8. The method for manufacturing the novel composite submerged nozzle according to claim 7, characterized in that: The coating thickness of the phenolic resin is ≤0.15 cm, and the thickness of the protective layer is 0.3-0.5 cm.

9. The method for manufacturing the novel composite submerged nozzle according to claim 7, characterized in that: The exterior of the submerged nozzle is wrapped with heat-insulating material with a thickness of 0.4 cm to 0.8 cm.

10. The method for manufacturing the novel composite submerged nozzle according to claim 8, characterized in that: The thermal insulation material is refractory wool made of alumina fiber.

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