Anti-nodulation and anti-blocking method suitable for built-in water gap and thin-wall water gap

Abstract

The invention belongs to the technical field of metallurgical continuous casting, and particularly relates to a nodulation and blockage prevention method suitable for a built-in water gap and a thin-wall water gap, a high-temperature-resistant stainless steel hoop is nested on the outer wall of the water gap during production of the water gap, and a high-temperature-resistant movable steel hoop with an adjustable support is matched with the high-temperature-resistant stainless steel hoop; during continuous casting field production, the high-temperature-resistant movable steel hoop is fixed above the crystallizer by the adjustable support on the high-temperature-resistant movable steel hoop; after the continuous casting platform is in place, the high-temperature-resistant movable steel hoop is clamped on the high-temperature-resistant stainless steel hoop of the water gap; conductive fire clay is coated between the high-temperature-resistant movable steel hoop and the high-temperature-resistant stainless steel hoop on the water gap; and connecting a lead, applying a positive electric field to the submersed nozzle, and applying a negative electric field to the tundish external electrode. The problem of nodulation and blockage of the water gap is effectively solved, the liquid level fluctuation qualification rate of the crystallizer is increased, large inclusions in a casting blank are reduced, and the quality of the casting blank is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of metallurgical continuous casting, and in particular relates to an anti-nodulation and clogging method suitable for built-in nozzles and thin-wall nozzles. Background Art

[0002] In my country's economic development, steel is an indispensable raw material, and its high-quality and efficient production is the basis for the efficient development of my country's economy; the emergence of continuous casting technology is a milestone in the development of the steel industry, and its development and application have greatly promoted the high-quality and efficient development of the steel industry; in the contemporary steel smelting process, continuous casting technology has become an indispensable link, which directly determines the efficiency and performance of steel production.

[0003] At present, the development level of high-quality steel in my country is inferior to that of developed countries. Many high-quality special steels still rely on imports. Compared with foreign countries, they mainly have poor quality consistency, unstable performance and low production efficiency. The main reason is the presence of many large inclusions in the steel.

[0004] The submerged nozzle is an important functional refractory material in continuous casting. It connects the tundish and the crystallizer, and plays an important role in preventing secondary oxidation of molten steel and stabilizing the flow field. Inclusions are an important factor affecting the quality of the ingot in the continuous casting process. However, in the continuous casting process of high-quality steel, inclusions such as alumina, magnesia spinel, and rare earth composite oxides easily react with the submerged nozzle, causing blockage of the inner hole and slag hanging on the outer wall. At the least, it causes a reduction in the pulling speed or uneven flow field, resulting in unstable continuous casting operation, and the fall of nodules and slag rolling seriously affect the quality of the ingot, and even complete blockage causes continuous casting interruption accidents, which has become a bottleneck problem for improving the production quality and efficiency of high-quality special steel in my country and needs to be solved urgently. Therefore, researchers have done a lot of work on the anti-blocking problem of submerged nozzles, which has greatly improved the blocking phenomenon of nozzles, but it is still not satisfactory, and related research is still ongoing.

[0005] At present, existing studies have shown that applying an electric field to an immersed nozzle can effectively prevent it from forming nodules and blockages. For example, CN104772452A, CN101176914A, CN106541123A, CN114082910A, CN114309571A, etc. all disclose methods of using an external electric field to prevent plug rods or nozzles from forming nodules. The principle is that applying an external electric field can effectively regulate the movement of inclusions in molten steel. However, existing studies have only focused on nozzles, and have not specified which type of nozzle. So far, no specific solutions have been found for applying an electric field to prevent nodules for built-in nozzles and thin-walled nozzles.

[0006] The internal nozzle is different from the external nozzle, combined nozzle and sliding nozzle. As the name suggests, it is a nozzle that passes through the base brick below the tundish and is fixed on the tundish. The outer diameter of the nozzle is required to match the inner diameter of the base brick, so there should be no protrusions on the outside of the nozzle. The wall of the thin-walled nozzle is thin. If an electrode is embedded in the nozzle wall, it is close to the inner cavity and will be severely heated during continuous casting, causing melting. Therefore, it is necessary to develop a method for preventing nodules and blockages with an external electric field suitable for internal nozzles and thin-walled nozzles. Summary of the invention

[0007] The purpose of the present invention is to provide an anti-nodulation and clogging method suitable for built-in nozzles and thin-wall nozzles, aiming to solve the problem that it is difficult to implement anti-nodulation measures of applied electric field for built-in nozzles and thin-wall nozzles.

[0008] The technical solution adopted by the present invention to achieve the above-mentioned purpose is as follows: A method for preventing nodules and blockages suitable for built-in nozzles and thin-walled nozzles. During nozzle production, a high-temperature resistant stainless steel hoop is embedded in the outer wall of the nozzle, and a high-temperature resistant movable steel hoop with an adjustable support is provided with the high-temperature resistant stainless steel hoop; during production at the continuous casting site, the high-temperature resistant movable steel hoop is fixed above the crystallizer by the adjustable support thereon; after the continuous casting platform is in place, the high-temperature resistant movable steel hoop is clamped on the high-temperature resistant stainless steel hoop of the nozzle; conductive fire clay is coated between the high-temperature resistant movable steel hoop and the high-temperature resistant stainless steel hoop on the nozzle to increase the bonding area between the high-temperature resistant movable steel hoop and the high-temperature resistant stainless steel hoop and prevent oxidation of the contact surface of the steel hoop; a connecting wire is used to apply a positive electric field to the immersed nozzle and a negative electric field to the external electrode of the intermediate package.

[0009] After the nozzle is formed, the nozzle is grooved by machining, and then a high temperature resistant stainless steel hoop is welded to the nozzle.

[0010] The high temperature resistant movable steel hoop is an openable and closable structure with two connecting posts; the inner surface of the high temperature resistant movable steel hoop is provided with a layer of high temperature resistant wire mesh.

[0011] During production at the continuous casting site, the adjustable support can flexibly move up and down to prevent the movable steel hoop from falling off; the bottom of the adjustable support is insulated from the crystallizer.

[0012] The intensity of the applied electric field is 50-300A and the frequency is 0-40000HZ.

[0013] The present invention proposes a method for preventing nodules and blockages in built-in nozzles and thin-wall nozzles. Based on the characteristic that the electric field can control the directional movement of inclusions in molten steel, a positive electric field is applied to the immersed nozzle to inhibit inclusions such as alumina in the molten steel from adhering to the nozzle wall, thereby preventing nodules and blockages in the nozzle, thereby improving the qualified rate of crystallizer liquid level fluctuations, reducing the generation of large-sized inclusions, and ultimately achieving the purpose of reducing large-sized inclusions in the ingot and improving the ingot quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 Schematic diagram of a water outlet with a high temperature resistant stainless steel hoop.

[0015] Figure 2 This is a schematic diagram of the structure of high temperature resistant movable steel hoops.

[0016] Figure 3 This is a schematic diagram of the field application.

[0017] Among them: 1-high temperature resistant stainless steel hoop; 2-water inlet; 3-high temperature resistant movable steel hoop; 5-power supply; 6-external electrode; 7-integral stopper rod; 8-covering agent in the tundish; 9-molten steel; 10-tundish; 11-water inlet; 12-insulating support; 13-crystallizer. DETAILED DESCRIPTION

[0018] The present invention is described in detail with reference to the accompanying drawings and specific embodiments: A method for preventing nodule clogging of built-in nozzles and thin-wall nozzles by applying an external electric field, the specific operation method is as follows: Step 1: Prefabricate a water inlet with nested steel hoops, a movable steel hoop, and a support that can be flexibly moved up and down according to the requirements mentioned in the invention content; Step 2: Install pulse power supply and lay lines on site; Step 3: At the continuous casting site, follow Figure 3 Assembling the device; Step 4: After continuous casting starts, turn on the power switch, adjust the parameters, and then click the output button; Step 5: Turn off the power switch after continuous casting. Example 1

[0019] Before continuous casting, fix the movable steel hoop on the insulating bracket and clamp it on the steel hoop on the nozzle. The submerged nozzle is connected to the positive pole of the power supply, and the external electrode is connected to the negative pole of the power supply. When continuous casting starts, turn on the power switch, and turn off the power switch when continuous casting ends.

[0020] The electric field parameters provided are: direct current with a strength of 50A.

[0021] Compared with the nozzle without electric field, the nodule degree of the submerged nozzle was lower during the casting process after the electric field was applied; after the casting was completed, it was found that the nodule thickness in the inner cavity of the submerged nozzle was reduced by 5%. Example 2

[0022] Before continuous casting, fix the movable steel hoop on the insulating bracket and clamp it on the steel hoop on the nozzle. The submerged nozzle is connected to the positive pole of the power supply, and the external electrode is connected to the negative pole of the power supply. When continuous casting starts, turn on the power switch, and turn off the power switch when continuous casting ends.

[0023] The electric field parameters provided are: direct current with a strength of 150A.

[0024] Compared with the nozzle without electric field, the nodule degree of the submerged nozzle was lower during the casting process after the electric field was applied; after the casting was completed, it was found that the nodule thickness in the inner cavity of the submerged nozzle was reduced by 9%. Example 3

[0025] Before continuous casting, fix the movable steel hoop on the insulating bracket and clamp it on the steel hoop on the nozzle. The submerged nozzle is connected to the positive pole of the power supply, and the external electrode is connected to the negative pole of the power supply. When continuous casting starts, turn on the power switch, and turn off the power switch when continuous casting ends.

[0026] The electric field parameters provided are: direct current with a strength of 300A.

[0027] Compared with the nozzle without electric field, the nodule degree of the submerged nozzle was lower during the casting process after the electric field was applied; after the casting was completed, it was found that the nodule thickness of the inner cavity of the submerged nozzle was reduced by 15%. Example 4

[0028] Before continuous casting, fix the movable steel hoop on the insulating bracket and clamp it on the steel hoop on the nozzle. The submerged nozzle is connected to the positive pole of the power supply, and the external electrode is connected to the negative pole of the power supply. When continuous casting starts, turn on the power switch, and turn off the power switch when continuous casting ends.

[0029] The electric field parameters provided are: average current 50A, pulse current 100A, frequency 10000Hz.

[0030] Compared with the nozzle without electric field, the nodule degree of the submerged nozzle was lower during the casting process after the electric field was applied; after the casting was completed, it was found that the nodule thickness of the inner cavity of the submerged nozzle was reduced by 13%. Example 5

[0031] Before continuous casting, fix the movable steel hoop on the insulating bracket and clamp it on the steel hoop on the nozzle. The submerged nozzle is connected to the positive pole of the power supply, and the external electrode is connected to the negative pole of the power supply. When continuous casting starts, turn on the power switch, and turn off the power switch when continuous casting ends.

[0032] The electric field parameters provided are: average current 50A, pulse current 100A, frequency 40000Hz.

[0033] Compared with the nozzle without electric field, the nodule degree of the submerged nozzle was lower during the casting process after the electric field was applied; after the casting was completed, it was found that the nodule thickness of the submerged nozzle inner cavity was reduced by 20%. Example 6

[0034] Before continuous casting, fix the movable steel hoop on the insulating bracket and clamp it on the steel hoop on the nozzle. The submerged nozzle is connected to the positive pole of the power supply, and the external electrode is connected to the negative pole of the power supply. When continuous casting starts, turn on the power switch, and turn off the power switch when continuous casting ends.

[0035] The electric field parameters provided are: average current 150A, pulse current 300A, frequency 10000Hz.

[0036] Compared with the nozzle without electric field, the nodule degree of the submerged nozzle was lower during the casting process after the electric field was applied; after the casting was completed, it was found that the nodule thickness of the submerged nozzle inner cavity was reduced by 20%. Example 7

[0037] Before continuous casting, fix the movable steel hoop on the insulating bracket and clamp it on the steel hoop on the nozzle. The submerged nozzle is connected to the positive pole of the power supply, and the external electrode is connected to the negative pole of the power supply. When continuous casting starts, turn on the power switch, and turn off the power switch when continuous casting ends.

[0038] The electric field parameters provided are: average current 150A, pulse current 300A, frequency 40000Hz.

[0039] Compared with the nozzle without electric field, the nodule degree of the submerged nozzle was lower during the casting process after the electric field was applied; after the casting was completed, it was found that the nodule thickness in the inner cavity of the submerged nozzle was reduced by 30%.

Claims

1. A method for preventing nodule blockage for built-in nozzles and thin-wall nozzles, characterized in that: During the production of the water nozzle, a high-temperature resistant stainless steel hoop is embedded in its outer wall, and the high-temperature resistant stainless steel hoop is matched with a high-temperature resistant movable steel hoop with an adjustable support; during the continuous casting on-site production, the high-temperature resistant movable steel hoop is fixed above the crystallizer by the adjustable support thereon; after the continuous casting platform is in place, the high-temperature resistant movable steel hoop is clamped on the high-temperature resistant stainless steel hoop of the water nozzle; conductive fire mud is coated between the high-temperature resistant movable steel hoop and the high-temperature resistant stainless steel hoop on the water nozzle to increase the bonding area between the high-temperature resistant movable steel hoop and the high-temperature resistant stainless steel hoop and prevent oxidation of the contact surface of the steel hoop; connecting wires to apply a positive electric field to the immersed water nozzle and a negative electric field to the external electrode of the intermediate package.

2. A method for preventing nodule blockage for built-in nozzles and thin-wall nozzles as claimed in claim 1, characterized in that: After the nozzle is formed, the nozzle is grooved by machining, and then a high temperature resistant stainless steel hoop is welded to the nozzle.

3. The method for preventing nodule blockage for built-in nozzles and thin-wall nozzles as claimed in claim 1, characterized in that: The high temperature resistant movable steel hoop is an openable and closable structure with two connecting posts; the inner surface of the high temperature resistant movable steel hoop is provided with a layer of high temperature resistant wire mesh.

4. The method for preventing nodule blockage for built-in nozzles and thin-wall nozzles as claimed in claim 1, characterized in that: During production at the continuous casting site, the adjustable support can flexibly move up and down to prevent the movable steel hoop from falling off; the bottom of the adjustable support is insulated from the crystallizer.

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