Electrically conductive weir plate for a tundish and method for removing inclusions

Abstract

The application discloses a power-on weir plate of a tundish and a method for removing inclusions, and belongs to the field of tundish technology. The power-on weir plate comprises a power-on weir plate body, a power supply and a conductive structure. The conductive structure is arranged on the power-on weir plate body. The power supply is connected with the conductive structure through a cable. The power-on weir plate body is arranged between a long nozzle and a submerged nozzle of the tundish. The cross-sectional shape of the power-on weir plate body is matched with the cross-sectional shape of the tundish. The bottom of the power-on weir plate body is provided with a steel passing hole. The application can effectively remove non-metallic inclusions in the molten steel of the tundish, prevents the inclusions from entering the crystallizer along with the molten steel, and influences the final quality of the cast slab.

Description

Technical Field

[0001] This invention relates to high-quality steel continuous casting technology, and more specifically, to an energized weir plate for a tundish and a method for removing inclusions therefrom. Background Technology

[0002] In high-quality steel products, especially those for automotive steel sheets, extremely high requirements are placed on the purity and surface quality of the molten steel. Therefore, strict control must be exercised over every step of the steelmaking and continuous casting process to prevent potential contamination of the molten steel. In the production of high-quality steel, blast furnace molten iron is smelted and refined into qualified molten steel. The molten steel is then poured from the ladle into the continuous casting tundish, flows through the tundish, and is poured into the crystallizer, finally solidifying into a qualified billet.

[0003] However, large non-metallic inclusions are more difficult to remove the closer they are to the crystallizer. Unremoved inclusions will enter the crystallizer with the steel flow and form oxide inclusions in the billet after solidification. This is more harmful to the steel quality of the billet and seriously affects the final quality of the billet.

[0004] The main method for removing inclusions in continuous casting is to optimize the molten steel flow field in the tundish to promote the flotation and removal of non-metallic inclusions. Summary of the Invention

[0005] In view of the deficiencies in the existing technology, the purpose of this invention is to provide an energized weir plate for a tundish and a method for removing inclusions therefrom, which can effectively remove non-metallic inclusions from the molten steel in the tundish and prevent inclusions from entering the crystallizer with the molten steel, thus affecting the final quality of the cast billet.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] The first aspect of the present invention provides an energized weir plate for an intermediate ladle, comprising an energized weir plate body, a power source, and a conductive structure;

[0008] The conductive structure is disposed on the energized weir plate body;

[0009] The power source is connected to the conductive structure via a cable;

[0010] The electrified weir plate body is located between the long water inlet and the submerged water inlet of the tundish;

[0011] The cross-sectional shape of the energized weir plate body is adapted to the cross-sectional shape of the through steel of the tundish;

[0012] The bottom of the electrified weir plate body is provided with a through-hole.

[0013] Preferably, the conductive structure includes a conductive hook and a ceramic conductive element;

[0014] The ceramic conductive element is a pair, symmetrically located on both sides of the through hole;

[0015] The conductive hooks are a pair, symmetrically arranged on the top of the energized weir plate body, respectively connected to the corresponding ceramic conductive elements, and also connected to the positive and negative terminals of the power supply through the cables.

[0016] Preferably, the material composition of the ceramic conductive element comprises the following components by mass percentage:

[0017] C: 20-35%;

[0018] Al2O3: 45-60%;

[0019] SiO2: 6-12%.

[0020] Preferably, the bulk density of the ceramic conductive element is ≥2.4 g / cm³. 3 Apparent porosity ≤19%, flexural strength ≥5.5MPa, compressive strength ≥40MPa.

[0021] Preferably, the material of the energized weir plate body comprises:

[0022] MgO ≥ 75 wt%, Fe2O3 ≤ 2 wt%.

[0023] Preferably, the bulk density of the energized weir plate body is ≥2.75 g / cm³. 3 Flexural strength ≥ 5.0 MPa, compressive strength ≥ 40 MPa.

[0024] A second aspect of the present invention provides a method for removing inclusions from an energized weir plate of an intermediate ladle as described in the first aspect of the present invention, comprising the following steps:

[0025] S1. The energized weir plate body is placed between the long water inlet and the immersion water inlet of the intermediate tundish, and the ceramic conductive element is connected to the positive and negative terminals of the power supply to form a conductive circuit.

[0026] S2. Open the slide plate of the ladle, and the molten steel flows into the intermediate ladle through the long nozzle, and then flows through the steel passage hole. Under the action of the conductive circuit formed by the ceramic conductive element, the non-metallic inclusions in the molten steel gather towards the negative electrode, thereby achieving the purpose of removing non-metallic inclusions.

[0027] S3. Molten steel with non-metallic inclusions removed then enters the crystallizer through the immersion nozzle.

[0028] Preferably, the flow rate of the molten steel is 2 to 10 t / min.

[0029] Preferably, the voltage of the power supply is 2 to 30V and the current is 10 to 350A.

[0030] Preferably, the current of the power supply is adjusted as follows:

[0031] I = 1800 * Q / U

[0032] In the formula, I is the current, in A; Q is the steel flow rate, in t / min; and U is the voltage, in V.

[0033] The energized weir plate for an intermediate ladle and its method for removing inclusions provided by the present invention have the following beneficial effects:

[0034] 1) The energized weir plate of the tundish of the present invention has a simple structure, is safe and reliable in use, and has no impact on production flow and safety;

[0035] 2) The ceramic conductive element in the energized weir plate of the tundish of the present invention has good conductivity, does not contaminate the molten steel, is resistant to corrosion and thermal shock, and ensures that its lifespan is synchronized with that of the tundish weir plate.

[0036] 3) The method for removing inclusions from the energized weir plate of the tundish of the present invention uses a safe voltage and the current is adjustable with the amount of steel passed and the voltage. It can effectively remove non-metallic inclusions from the molten steel in the tundish and prevent inclusions from entering the crystallizer with the molten steel, thus affecting the quality of the final billet. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the structure of the energized weir plate of the present invention;

[0038] Figure 2 yes Figure 1 Side view. Detailed Implementation

[0039] To better understand the above-mentioned technical solutions of the present invention, the technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0040] Combination Figure 1 and Figure 2 As shown, the present invention provides an energized weir plate for an intermediate package, comprising an energized weir plate body 1, a power supply 2, and a conductive structure.

[0041] The conductive structure is installed on the main body 1 of the energized weir plate.

[0042] Power source 2 is electrically connected to the conductive structure via cable 3.

[0043] The cross-sectional shape of the energized weir plate body 1 is adapted to the cross-sectional shape of the tundish steel passage, and a steel passage hole 4 is opened at the bottom. The energized weir plate body 1 is set between the long nozzle and the submerged nozzle of the tundish, and the molten steel can only flow through the steel passage hole 4.

[0044] The conductive structure includes a conductive hook 5 and a ceramic conductive element 6.

[0045] The ceramic conductive element 6 has a pair, symmetrically located on both sides of the through hole 4, forming positive and negative electrodes on both sides of the through hole 4.

[0046] The conductive hooks 5 are a pair, symmetrically arranged on the top of the energized weir plate body 1, respectively connected to the corresponding ceramic conductive elements 6, and also connected to the positive and negative poles of the power supply 2 respectively through cables 3.

[0047] The ceramic conductive element 6 is composed of the following components by mass percentage:

[0048] C: 20-35%;

[0049] Al2O3: 45-60%;

[0050] SiO2: 6-12%.

[0051] The C content of the ceramic conductive element 6 is 20-35%. This C content ensures a continuous distribution of C in the material, guaranteeing a resistivity of <0.5×10⁻⁴ Ω·m, which is particularly reliable for the function and efficiency of the applied electric field. However, an excessively high C content is also undesirable, as it reduces the strength of the ceramic conductive element 6, decreases its resistance to erosion by molten steel and slag in the tundish, and compromises its lifespan.

[0052] The bulk density of the ceramic conductive element 6 is ≥2.4 g / cm³. 3 Apparent porosity ≤19%, flexural strength ≥5.5MPa, compressive strength ≥40MPa.

[0053] The ceramic conductive element 6 is characterized by good conductivity, non-contamination of molten steel, corrosion resistance, thermal shock resistance, and lifespan synchronization with the energized weir plate body 1.

[0054] The ceramic conductive element 6 is formed by isostatic pressing and is pre-made into a long strip shape (similar to the production method of stopper rods). When the energized weir plate body 1 is cast, it is pre-embedded in the designed part of the weir plate mold and integrally formed into an energized weir plate body 1.

[0055] In the material of the energized weir plate body 1:

[0056] MgO ≥ 75 wt%, Fe2O3 ≤ 2 wt%.

[0057] The bulk density of the energized weir plate body 1 is ≥2.75 g / cm³. 3 Flexural strength ≥ 5.0 MPa, compressive strength ≥ 40 MPa.

[0058] A second aspect of the present invention provides a method for removing inclusions from an energized weir plate of an intermediate ladle provided in the first aspect of the present invention, comprising the following steps:

[0059] S1. The energized weir plate body 1 is placed between the long water inlet and the submersible water inlet of the intermediate tundish. The ceramic conductive element 6 is connected to the positive and negative terminals of the power supply 2 through the cable 3 to form a conductive circuit.

[0060] S2. Open the slide plate of the ladle. Molten steel flows into the tundish through the long nozzle and then through the through hole 4. Non-metallic inclusions in the molten steel also flow through the through hole 4. Since the non-metallic inclusions are positively charged, under the action of the conductive circuit formed by the ceramic conductive element 6, the non-metallic inclusions in the molten steel gather towards the negative electrode of the ceramic conductive element 6, thereby achieving the purpose of removing non-metallic inclusions.

[0061] S3. Molten steel with non-metallic inclusions removed enters the crystallizer through an immersion nozzle.

[0062] The flow rate of molten steel is 2 to 10 t / min.

[0063] The voltage of power supply 2 is 2-30V and the current is 10-350A.

[0064] The voltage of power supply 2 is generally set to a fixed value, while the current process parameter of power supply 2 is adjusted according to the changes in voltage and steel throughput. The calculation formula for adjusting the current parameter is as follows:

[0065] I = 1800 * Q / U

[0066] In the formula, I is the current, in A; Q is the steel flow rate, in t / min; and U is the voltage, in V.

[0067] Example 1

[0068] This embodiment is used in a 60t dual-flow tundish. The shape of the electrified weir plate body 1 is consistent with the cross-section of the 60t tundish steel passage, and the bottom of the electrified weir plate body 1 has a steel passage hole 4. Two electrified weir plate bodies 1 are placed between the long nozzle and the two submersible nozzles on both sides of the tundish. Molten steel injected into the long nozzle can only flow through the steel passage holes 4 of the two electrified weir plate bodies 1 into the submersible nozzles. Each electrified weir plate body 1 is provided with a conductive hook 5 at the top, and a ceramic conductive element 6 is connected to the bottom of the conductive hook 5. The ceramic conductive element 6 directly leads to both sides of the steel passage hole 4, forming positive and negative poles on both sides of the steel passage hole 4. The conductive hook 5 is connected to the positive and negative poles of the DC power supply 2 by cables 3.

[0069] The chemical composition of ceramic conductive element 6 is as follows:

[0070] C: 35%;

[0071] Al2O3: 58%;

[0072] SiO2: 7%.

[0073] Physical properties: Bulk density: 2.80 g / cm³ 3 Apparent porosity: 16%, flexural strength: 6MPa, compressive strength: 50MPa, resistivity: 0.2×10~4Ω·m.

[0074] Features: Excellent conductivity ensures the function and efficiency of the applied electric field; does not contaminate molten steel; resistant to corrosion and thermal shock; and ensures lifespan is synchronized with that of the energized weir plate body 1.

[0075] The ceramic conductive element 6 is formed by isostatic pressing and is pre-made into a long strip shape (similar to the production method of stopper rod). When the energized weir plate body 1 is cast, it is pre-embedded in the designed part of the mold of the energized weir plate body 1, and integrally formed into a whole energized weir plate body 1.

[0076] Physical and chemical property requirements for the body material of the energized weir plate:

[0077] MgO: 80%;

[0078] Fe2O3: 2.0%;

[0079] Bulk density: 2.75 g / cm³ 3 Compressive strength: 50MPa; Flexural strength: 6.0MPa.

[0080] The inclusion removal method based on the electrically conductive weir plate in this embodiment includes the following steps:

[0081] 1. Preparations before pouring

[0082] The energized weir plate body 1 is placed between the long water inlet and the submersible water inlet of the tundish, and the ceramic conductive element 6 is connected to the positive and negative terminals of the DC power supply 2 by the cable 3.

[0083] 2. Steel casting

[0084] Open the ladle's slide plate, and control the single-flow steel pouring rate at 3t / min. The molten steel in the ladle flows into the tundish through the long nozzle, and then flows through the steel passage hole 4 of the electrified weir plate body 1 and enters the crystallizer through the submerged nozzle.

[0085] 3. Process for removing inclusions from the main body of the electrified weir plate

[0086] With the DC power supply turned on, the voltage of ceramic conductive element 6 is set to 24V and the current to 300A. The voltage is generally set to a fixed value, while the current process parameter is adjusted according to changes in voltage and steel flow rate. The calculation formula for adjusting the current parameter is as follows:

[0087] I = 1800 * Q / U

[0088] I - Current (A), Q - Steel flow rate (t / min), U - Voltage (V)

[0089] Molten steel passes through the through-hole 4, forming a conductive circuit between the positive and negative electrodes of two ceramic conductive elements 6 on the sidewall of the through-hole 4. Non-metallic inclusions in the molten steel also flow through the through-hole 4. Because the non-metallic inclusions carry a positive charge, under the action of the conductive circuit formed by the two ceramic conductive elements 6 on the sidewall of the through-hole 4, the non-metallic inclusions migrate towards the negative electrode of the ceramic conductive elements 6, and are eventually adsorbed and aggregated at the negative electrode, thus achieving the purpose of removing non-metallic inclusions from the molten steel.

[0090] Example 2

[0091] This embodiment is used in a 60t dual-flow tundish. The shape of the electrified weir plate body 1 is consistent with the cross-section of the 60t tundish steel passage, and the bottom of the electrified weir plate body 1 has a steel passage hole 4. Two electrified weir plate bodies 1 are placed between the long nozzle and the two submersible nozzles on both sides of the tundish. Molten steel injected into the long nozzle can only flow through the steel passage holes 4 of the two electrified weir plate bodies 1 into the submersible nozzles. Each electrified weir plate body 1 is provided with a conductive hook 5 at the top, and a ceramic conductive element 6 is connected to the bottom of the conductive hook 5. The ceramic conductive element 6 directly leads to both sides of the steel passage hole 4, forming positive and negative poles on both sides of the steel passage hole 4. The conductive hook 5 is connected to the positive and negative poles of the DC power supply 2 by cables 3.

[0092] The chemical composition of ceramic conductive element 6 is as follows:

[0093] C: 35%;

[0094] Al2O3: 58%;

[0095] SiO2: 7%.

[0096] Physical properties: Bulk density: 2.80 g / cm3, Apparent porosity: 16%, Flexural strength: 6 MPa, Compressive strength: 50 MPa, Resistivity: 0.2 × 10~4 Ω·m.

[0097] Features: Excellent conductivity ensures the function and efficiency of the applied electric field; does not contaminate molten steel; resistant to corrosion and thermal shock; and ensures lifespan is synchronized with that of the energized weir plate body 1.

[0098] The ceramic conductive element 6 is formed by isostatic pressing and is pre-made into a long strip shape (similar to the production method of stopper rod). When the energized weir plate body 1 is cast, it is pre-embedded in the designed part of the mold of the energized weir plate body 1, and integrally formed into a whole energized weir plate body 1.

[0099] Physical and chemical property requirements for the body material of the energized weir plate:

[0100] MgO: 80%;

[0101] Fe2O3: 2.0%;

[0102] Bulk density: 2.75 g / cm3, compressive strength: 50 MPa, flexural strength: 6.0 MPa.

[0103] The inclusion removal method based on the electrically conductive weir plate in this embodiment includes the following steps:

[0104] 1. Preparations before pouring

[0105] The energized weir plate body 1 is placed between the long water inlet and the submersible water inlet of the tundish, and the ceramic conductive element 6 is connected to the positive and negative terminals of the DC power supply 2 by the cable 3.

[0106] 2. Steel casting

[0107] Open the ladle's slide plate, and control the single-flow steel pouring rate at 3t / min. The molten steel in the ladle flows into the tundish through the long nozzle, and then flows through the steel passage hole 4 of the electrified weir plate body 1 and enters the crystallizer through the submerged nozzle.

[0108] 3. Process for removing inclusions from the main body of the electrified weir plate

[0109] With the DC power supply turned on, the voltage of ceramic conductive element 6 is set to 5V and the current to 100A. The voltage is generally set to a fixed value, while the current process parameter is adjusted according to changes in voltage and steel flow rate. The calculation formula for adjusting the current parameter is as follows:

[0110] I = 1800 * Q / U

[0111] I - Current (A), Q - Steel flow rate (t / min), U - Voltage (V)

[0112] Molten steel passes through the through-hole 4, forming a conductive circuit between the positive and negative electrodes of two ceramic conductive elements 6 on the sidewall of the through-hole 4. Non-metallic inclusions in the molten steel also flow through the through-hole 4. Because the non-metallic inclusions carry a positive charge, under the action of the conductive circuit formed by the two ceramic conductive elements 6 on the sidewall of the through-hole 4, the non-metallic inclusions migrate towards the negative electrode of the ceramic conductive elements 6, and are eventually adsorbed and aggregated at the negative electrode, thus achieving the purpose of removing non-metallic inclusions from the molten steel.

[0113] Those skilled in the art should recognize that the above embodiments are merely illustrative of the present invention and are not intended to limit the present invention. Any variations or modifications to the above embodiments that are within the spirit and essence of the present invention will fall within the scope of the claims of the present invention.

Claims

1. A power supply weir plate of a tundish, characterized by: The electric weir plate body, the power supply and the conductive structure are included. The conductive structure is arranged on the electric weir plate body. The power supply is connected with the conductive structure through the cable. The electric weir plate body is arranged between the long nozzle and the submerged nozzle of the tundish. The cross-sectional shape of the electric weir plate body is matched with the cross-sectional shape of the tundish. The bottom of the electric weir plate body is provided with a through-hole, The conductive structure includes the conductive hook and the ceramic conductive element. The ceramic conductive element has a pair of elements which are symmetrically arranged on the two sides of the through-hole. The conductive hook has a pair of hooks which are symmetrically arranged on the top of the electric weir plate body and are respectively connected with the corresponding ceramic conductive element and the positive and negative poles of the power supply through the cable. The material composition of the ceramic conductive element includes the following components in percentage by mass: C：20~35%； Al2O3: 45-60%; SiO2: 6-12%, The material of the electric weir plate body includes: MgO≥75wt%, Fe2O3≤2wt%, Under the action of the conductive loop formed by the ceramic conductive element, the non-metallic inclusions in the molten steel gather to the negative pole, so as to achieve the purpose of removing the non-metallic inclusions.

2. The power dam of a tundish according to claim 1, characterized in that Bulk density of the ceramic conductive element is ≥ 2.4 g / cm 3 , apparent porosity is ≤ 19%, bending strength is ≥ 5.5 MPa, and compressive strength is ≥ 40 MPa.

3. A method of inclusion removal based on the electrically conductive weir plate of the tundish according to one of claims 1-2, characterized in that, The method includes the following steps: S1, arranging the electric weir plate body between the long nozzle and the submerged nozzle of the tundish, connecting the positive and negative poles of the power supply with the ceramic conductive element to form a conductive loop; S2, opening the slide plate of the ladle, and the molten steel flows into the tundish through the long nozzle, and then flows through the through-hole, under the action of the conductive loop formed by the ceramic conductive element, the non-metallic inclusions in the molten steel gather to the negative pole, so as to achieve the purpose of removing the non-metallic inclusions; S3, the molten steel with the removed non-metallic inclusions enters the crystallizer through the submerged nozzle.

4. The method of claim 3, wherein: The through-steel amount of the molten steel is 2-10t / min.

5. The method of claim 4, wherein: The voltage of the power supply is 2-30V, and the current is 10-350A.

6. The method of removing inclusions according to claim 5, wherein The current of the power supply is adjusted as follows: I=1800*Q / U In the formula, I is the current, unit A; Q is the through-steel amount, unit t / min; U is the voltage, unit V.

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