An integrally formed gas curtain ceramic filter for a continuous casting tundish

Abstract

The application relates to an integrally-formed air curtain ceramic filter for a continuous casting tundish, which comprises a strip-shaped structure body, the strip-shaped structure body is internally provided with air chambers arranged along the length direction of the air, one end of the air chamber is closed, the other end is provided with a communicating port communicated with the outside, and an internally-threaded connecting port is embedded at the communicating port, and a diffusion air-permeable layer is embedded on one side of the strip-shaped structure body, and the diffusion air-permeable layer is on one side of the air chamber. The application further discloses a preparation method of the integrally-formed air curtain ceramic filter for the continuous casting tundish. In the application, the main body and the diffusion air-permeable layer are integrally formed by an isostatic pressing process, the two kinds of materials are tightly connected without any gap, in actual application, the two kinds of materials will not cause the defects of air leakage, air channeling, uneven air permeability, low bubble nucleation rate and the like due to the matching problems, and the product penetration problem of the air curtain ceramic filter produced by the prior art in actual application is solved.

Description

Technical Field

[0001] This invention belongs to the field of continuous casting tundish, and particularly relates to an integrally molded air curtain ceramic filter for continuous casting tundish and its preparation method. Background Technology

[0002] The principle of the gas curtain ceramic filter technology in continuous casting tundishes is to place a strip-shaped gas curtain ceramic filter perpendicular to the direction of molten steel flow at an optimal position at the bottom of the tundish. Argon gas is blown in, and the argon gas rises through the gas curtain ceramic filter, forming an argon bubble gas curtain barrier, which promotes the flotation and removal of non-metallic inclusions in the molten steel. However, traditional gas curtain ceramic filters are produced using a composite process of casting molding and ordinary machine pressing, forming an assembly structure of the permeable core and the base material. This is prone to defects such as gas leakage, gas cross-contamination, uneven permeability, and low bubble nucleation rate. These drawbacks result in low inclusion removal rates and short service life in practical applications of the gas curtain ceramic filter, and it is also highly likely to cause safety hazards such as steel seepage and leakage, becoming a key technical problem restricting the widespread application of this technology. Existing defects or shortcomings:

[0003] (1) The existing air curtain ceramic filter uses a composite process of casting and conventional machine pressing. Due to the requirements of the production process, there is a certain assembly gap between the machine-pressed dispersion material and the cast main material. Moreover, in the application environment, it needs to be immersed in molten steel above 1500 degrees for a long time. Due to the influence of different material combinations and production processes, the blowing of argon gas is prone to leakage, gas cross-flow, and uneven gas permeability, resulting in low bubble nucleation rate, which directly affects the removal of inclusions. At the same time, the gaps between different materials will also cause steel seepage under the influence of the static pressure of molten steel, which directly affects the product's performance and lifespan. In fact, steel leakage accidents may even occur due to steel seepage during long-term use. This is the main reason why this type of product cannot be widely promoted.

[0004] (2) Existing technology produces machine-pressed dispersed air curtain permeable materials with poor molding precision, low strength, poor resistance to erosion and scouring, and short service life. The service life cannot be synchronized with that of tundish refractory materials, which has a significant impact on the production cost of continuous casting refractory materials.

[0005] (3) In existing technology, the connection between the gas chamber and the argon pipeline of the gas curtain ceramic filter is usually achieved by directly inserting a metal pipe into the pre-reserved circular channel of the gas curtain ceramic filter, and then sealing the gap between the two with fire clay. In application, the shrinkage of the fire clay due to water loss creates an argon channel, causing most of the argon to be blown out from between the metal pipe and the argon channel of the gas curtain ceramic filter, resulting in a gas leakage problem, which affects the stability and continuity of the argon flow rate. At the same time, there is a risk of blowing through the working lining of the tundish, causing steel leakage accidents.

[0006] (4) The main material of the air curtain ceramic filter produced by the existing technology is generally castable. Although the porosity of the main material (5~20%) is much lower than that of the dispersed material (20~30%), the product has better high-temperature stability due to the carbon-bonded firing process. The permeability of the ceramic microporous structure is more stable and reliable, and the average diameter and number of nuclei formed by the bubbles are much greater than those of the traditional process. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the prior art and provide an integrally molded air curtain ceramic filter for continuous casting tundishes.

[0008] The present invention also provides a method for preparing an integrally molded air curtain ceramic filter for continuous casting tundish.

[0009] In this invention, the main body and the diffused air-permeable layer are integrally formed using an isostatic pressing process. The two materials are tightly packed without any gaps. In practical applications, this avoids the drawbacks of air leakage, air cross-contamination, uneven air permeability, and low bubble nucleation rate caused by the mismatch between the two materials. This solves the problem of steel seepage in the air curtain ceramic filter produced by the prior art in practical applications.

[0010] An integrally molded gas curtain ceramic filter for continuous casting tundish includes a strip-shaped structure with a gas chamber arranged along the length of the gas. One end of the gas chamber is closed, and the other end has a communication port that communicates with the outside, with an internal threaded connection port pre-embedded at the communication port. A diffused permeable layer is embedded on one side of the strip-shaped structure, and one side of the diffused permeable layer is the gas chamber.

[0011] A method for preparing an integrally molded gas curtain ceramic filter for continuous casting tundish includes the following steps:

[0012] (1) Weigh the main material and the dispersion material: The main material includes the following raw materials by mass percentage: 65-85% alumina particles, 10-30% graphite, and 2-8% binder; The dispersion material includes the following raw materials by mass percentage: 50% alumina particles, 25% microporous nano-ceramic particles, 15% graphite, 5% binder, and 5% antioxidant;

[0013] (2) Place the main material and the dispersed material in the mold, seal the mold, and press it into shape using the equal diameter pressing process. During the isostatic pressing process, control the molding pressure to 30~120Mpa and the holding time to 30 seconds~5 minutes. Press and demold to obtain the blank.

[0014] (3) Curing: The green body is cured at 150~300℃ for 8~12 hours to obtain a cured green body;

[0015] (4) Firing: The solidified green body is fired at 800~1200℃ for 2~6 hours to obtain the fired green body;

[0016] (5) The blank is machined and fired to the required size to obtain a preliminary blank;

[0017] (6) In the preliminary blank, the main material forms the air curtain ceramic filter body and the dispersion material forms the dispersion permeable layer. The air curtain ceramic filter body is impregnated or coated with a high-temperature sealing coating, and the dispersion permeable layer is impregnated or coated with an anti-oxidation erosion coating. After drying at 100~300℃ for 3~5 hours, the finished product is obtained.

[0018] Furthermore, the high-temperature sealing coating comprises the following raw materials by mass percentage: 60-90% nano-sized ceramic powder and 10-40% high-temperature resistant inorganic binder, wherein the high-temperature resistant inorganic binder is aluminosilicate.

[0019] Furthermore, the high-temperature sealing coating is produced using a high-speed asymmetric mixing process.

[0020] Furthermore, the antioxidant erosion coating comprises the following raw materials in weight percentages: 30-50% high-temperature frit, 10-30% microporous nano-ceramic particles, 10-20% feldspar, and 10-30% aluminosilicate solution.

[0021] Furthermore, the antioxidant erosion coating is produced using a high-speed asymmetric high-speed mixing process.

[0022] Furthermore, the particle size of the alumina particles is ≤1.5mm.

[0023] Furthermore, the particle size of the microporous nanoceramic particles is 10~850 μm.

[0024] Furthermore, the binder is a modified phenolic resin, and the antioxidant is a magnesium-aluminum alloy or an aluminum-silicon alloy.

[0025] Furthermore, the air chamber is formed by adding a wax model to the mold and having the wax model melt and disappear during the curing and firing process.

[0026] The beneficial effects of this invention are:

[0027] 1. In this invention, the main body and the diffused air-permeable layer are integrally formed by isostatic pressing. The two materials are tightly packed without any gaps. In practical applications, there will be no defects such as air leakage, air cross-flow, uneven air permeability, and low bubble nucleation rate caused by the mismatch between the two materials. This solves the problem of steel seepage in the air curtain ceramic filter produced by the prior art in practical applications.

[0028] 2. The air chamber of the one-piece molded air curtain ceramic filter in this invention is formed by an advanced lost-wax molding process, which provides the product with a larger inner cavity, a larger air permeability area, and a more uniform air permeability argon channel, thus solving the problem of uneven air output in different areas of the air curtain ceramic filter produced by the prior art.

[0029] 3. In this invention, the argon tube of the integrally formed gas curtain ceramic filter is connected by a pre-embedded threaded part, which is connected to the argon tube by thread, avoiding the gas leakage problem caused by the original assembly method, and can efficiently and leak-free blow argon into the product.

[0030] 4. The high-temperature sealing coating on the main surface of the integrally molded gas curtain ceramic filter in this invention can protect the product from oxidation and prevent argon from escaping from the main body at both room temperature and high temperature, effectively ensuring that the blown-in argon is blown out from the dispersion material part as much as possible.

[0031] 5. The anti-oxidation and erosion coating on the surface of the diffused air-permeable material of the integrally molded air curtain ceramic filter in this invention can improve the ability of the diffused air-permeable material to resist the erosion of molten steel, and ensure that the service life of the product is synchronized with the service life of the tundish. Attached Figure Description

[0032] Figure 1 This is a cross-sectional schematic diagram of the present invention.

[0033] Figure 2 This refers to the air bubbles blown out of products made of high-alumina refractory castable as the outer casing, filled with press-formed permeable material, or directly tamped permeable material, in the existing technology.

[0034] Figure 3 These are the bubbles blown from the product made in Example 3.

[0035] Figure 4 For detecting the back pressure of the air curtain ceramic filter. Detailed Implementation

[0036] The present invention will be further described below with reference to embodiments. The following description of the embodiments is only for the purpose of helping to understand the present invention.

[0037] Example 1: An integrally molded gas curtain ceramic filter for continuous casting tundish includes a strip-shaped structure 1. The strip-shaped structure 1 contains a gas chamber 2 arranged along its length. One end of the gas chamber 2 is closed, and the other end has a connecting port that communicates with the outside, with an internally threaded connection port 3 pre-embedded at the connecting port. A diffused permeable layer 4 is embedded on one side of the strip-shaped structure 1, and one side of the diffused permeable layer 4 is the gas chamber. This invention connects to an argon gas pipeline via the internally threaded connection port, allowing argon gas to be blown into the tundish at a constant pressure and quantity during continuous casting. This improves the likelihood of inclusions flotation and removal during the continuous casting process, activates local molten pools, and reduces dead zones and slag crust formation on the tundish surface.

[0038] Example 2: A method for preparing an integrally molded gas curtain ceramic filter for continuous casting tundish, comprising the following steps:

[0039] (1) Weigh the main material and the dispersion material: The main material includes the following raw materials by mass percentage: 65% alumina particles, 30% graphite, and 5% binder; The dispersion material includes the following raw materials by mass percentage: 50% alumina particles, 25% microporous nano-ceramic particles, 15% graphite, 5% binder, and 5% antioxidant. The particle size of the alumina particles is ≤1.5mm, the particle size of the microporous nano-ceramic particles is 10~850 μm, the binder is modified phenolic resin, and the antioxidant is magnesium-aluminum alloy.

[0040] (2) Place the main material and the dispersed material in the mold, seal the mold, and press it into shape using the equal diameter pressing process. During the isostatic pressing process, control the molding pressure to 30 MPa and the holding time to 30 seconds. Press and demold to obtain the blank.

[0041] (3) Curing: The green body is cured at 150℃ for 8 hours to obtain a cured green body;

[0042] (4) Firing: The solidified green body is fired at 800℃ for 2 hours to obtain the fired green body;

[0043] (5) The blank is machined and fired to the required size to obtain a preliminary blank;

[0044] (6) In the preliminary blank, the main material forms the air curtain ceramic filter body and the dispersion material forms the dispersion permeable layer. The air curtain ceramic filter body is impregnated with a high temperature sealing coating and the dispersion permeable layer is impregnated with an anti-oxidation erosion coating. After drying at 100°C for 3 hours, the finished product is obtained.

[0045] The high-temperature sealing coating comprises the following raw materials by weight percentage: 60% nano-sized ceramic powder and 40% high-temperature resistant inorganic binder, which is aluminosilicate. The high-temperature sealing coating is produced using a high-speed asymmetric mixing process.

[0046] The anti-oxidation erosion coating comprises the following raw materials by weight percentage: 30% high-temperature fused silica, 30% microporous nano-ceramic particles, 20% feldspar, and 20% aluminosilicate solution. The anti-oxidation erosion coating is produced using a high-speed asymmetric high-speed mixing process; the microporous nano-ceramic particles have a particle size of 10~850 μm. The air chamber is formed by adding a wax model to a mold, which melts and disappears during curing and firing.

[0047] Example 3: A method for preparing an integrally molded gas curtain ceramic filter for continuous casting tundish, comprising the following steps:

[0048] (1) Weigh the main material and the dispersion material: The main material includes the following raw materials by mass percentage: 85% alumina particles, 13% graphite, and 2% binder; The dispersion material includes the following raw materials by mass percentage: 50% alumina particles, 25% microporous nano-ceramic particles, 15% graphite, 5% binder, and 5% antioxidant. The particle size of the alumina particles is ≤1.5mm, the particle size of the microporous nano-ceramic particles is 10~850 μm, the binder is modified phenolic resin, and the antioxidant is aluminum-silicon alloy.

[0049] (2) Place the main material and the dispersed material in the mold, seal the mold, and press it into shape using the equal diameter pressing process. During the isostatic pressing process, control the molding pressure to 50 MPa and the holding time to 1 minute. Press and demold to obtain the blank.

[0050] (3) Curing: The green body is cured at 200℃ for 9 hours to obtain a cured green body;

[0051] (4) Firing: The solidified green body is fired at 900℃ for 3 hours to obtain the fired green body;

[0052] (5) The blank is machined and fired to the required size to obtain a preliminary blank;

[0053] (6) In the preliminary blank, the main material forms the air curtain ceramic filter body and the dispersion material forms the dispersion permeable layer. A high-temperature sealing coating is applied to the air curtain ceramic filter body and an anti-oxidation erosion coating is applied to the dispersion permeable layer. After drying at 150°C for 3.5 hours, the finished product is obtained.

[0054] The high-temperature sealing coating comprises the following raw materials by weight percentage: 70% nano-sized ceramic powder and 30% high-temperature resistant inorganic binder, which is aluminosilicate. The high-temperature sealing coating is produced using a high-speed asymmetric mixing process.

[0055] The anti-oxidation erosion coating comprises the following raw materials by weight percentage: 50% high-temperature frit, 10% microporous nano-ceramic particles, 10% feldspar, and 30% aluminosilicate solution. The anti-oxidation erosion coating is produced using a high-speed asymmetric high-speed mixing process; the microporous nano-ceramic particles have a particle size of 10~850 μm. The air chamber is formed by adding a wax model to a mold, which melts and disappears during curing and firing.

[0056] Example 4: A method for preparing an integrally molded gas curtain ceramic filter for continuous casting tundish, comprising the following steps:

[0057] (1) Weigh the main material and the dispersion material: The main material includes the following raw materials by mass percentage: 82% alumina particles, 10% graphite, and 8% binder; The dispersion material includes the following raw materials by mass percentage: 50% alumina particles, 25% microporous nano-ceramic particles, 15% graphite, 5% binder, and 5% antioxidant. The particle size of the alumina particles is ≤1.5mm, the particle size of the microporous nano-ceramic particles is 10~850 μm, the binder is modified phenolic resin, and the antioxidant is magnesium-aluminum alloy.

[0058] (2) Place the main material and the dispersed material in the mold, seal the mold, and press it into shape using the equal diameter pressing process. During the isostatic pressing process, control the molding pressure to 100 MPa and the holding time to 3 minutes. Press and demold to obtain the blank.

[0059] (3) Curing: The green body is cured at 250℃ for 11 hours to obtain a cured green body;

[0060] (4) Firing: The solidified green body is fired at 1000℃ for 4 hours to obtain the fired green body;

[0061] (5) The blank is machined and fired to the required size to obtain a preliminary blank;

[0062] (6) In the preliminary blank, the main material forms the air curtain ceramic filter body and the dispersion material forms the dispersion permeable layer. The air curtain ceramic filter body is impregnated or coated with a high-temperature sealing coating, and the dispersion permeable layer is impregnated or coated with an anti-oxidation erosion coating. After drying at 200°C for 4 hours, the finished product is obtained.

[0063] The high-temperature sealing coating comprises the following raw materials by weight percentage: 90% nano-sized ceramic powder and 10% high-temperature resistant inorganic binder, which is aluminosilicate. The high-temperature sealing coating is produced using a high-speed asymmetric mixing process.

[0064] The anti-oxidation erosion coating comprises the following raw materials by weight percentage: 40% high-temperature fused silica, 20% microporous nano-ceramic particles, 15% feldspar, and 25% aluminosilicate solution. The anti-oxidation erosion coating is produced using a high-speed asymmetric high-speed mixing process; the microporous nano-ceramic particles have a particle size of 10~850 μm. The air chamber is formed by adding a wax model to a mold, which melts and disappears during curing and firing.

[0065] Example 5: A method for preparing an integrally molded gas curtain ceramic filter for continuous casting tundish, comprising the following steps:

[0066] (1) Weigh the main material and the dispersion material: The main material includes the following raw materials by mass percentage: 70% alumina particles, 23% graphite, and 7% binder; The dispersion material includes the following raw materials by mass percentage: 50% alumina particles, 25% microporous nano-ceramic particles, 15% graphite, 5% binder, and 5% antioxidant. The particle size of the alumina particles is ≤1.5mm, the particle size of the microporous nano-ceramic particles is 10~850 μm, the binder is modified phenolic resin, and the antioxidant is magnesium-aluminum alloy.

[0067] (2) Place the main material and the dispersed material in the mold, seal the mold, and press it into shape using the equal diameter pressing process. During the isostatic pressing process, control the molding pressure to 120 MPa and the holding time to 5 minutes. Press and demold to obtain the blank.

[0068] (3) Curing: The green body is cured at 300℃ for 12 hours to obtain a cured green body;

[0069] (4) Firing: The solidified green body is fired at 1200℃ for 6 hours to obtain the fired green body;

[0070] (5) The blank is machined and fired to the required size to obtain a preliminary blank;

[0071] (6) In the preliminary blank, the main material forms the air curtain ceramic filter body and the dispersion material forms the dispersion permeable layer. The air curtain ceramic filter body is impregnated or coated with a high-temperature sealing coating, and the dispersion permeable layer is impregnated or coated with an anti-oxidation erosion coating. After drying at 300°C for 5 hours, the finished product is obtained.

[0072] The high-temperature sealing coating comprises the following raw materials by weight percentage: 80% nano-sized ceramic powder and 20% high-temperature resistant inorganic binder, which is aluminosilicate. The high-temperature sealing coating is produced using a high-speed asymmetric mixing process.

[0073] The anti-oxidation erosion coating comprises the following raw materials by weight percentage: 48% high-temperature fused silica, 24% microporous nano-ceramic particles, 18% feldspar, and 10% aluminosilicate solution. The anti-oxidation erosion coating is produced using a high-speed asymmetric high-speed mixing process; the microporous nano-ceramic particles have a particle size of 10~850 μm. The air chamber is formed by adding a wax model to a mold, which melts and disappears during curing and firing.

[0074] Laboratory simulation experiments showed that, under the same gas pressure of 5 bar and gas flow rate of 5 L / min, existing technologies using high-alumina refractory castables to make the outer casing, filled with machine-pressed permeable material or directly tamped permeable material, exhibited uneven gas blowing, characterized by large bubbles in some areas and no bubbles in others. In contrast, the product produced in Example 3 produced evenly and densely distributed bubbles with numerous small-diameter bubbles. (Refer to Appendix) Figure 2 and attached Figure 3 .

[0075] The products from Examples 2-5 were practically applied in a well-known special steel enterprise in East China. The steel used was bearing steel, the casting temperature was 1560-1580 degrees Celsius, the casting time was 320 minutes, and the argon gas pressure connected to the gas curtain ceramic filter was 7 bar with a flow rate of 5 L / min. Throughout the casting process, the back pressure of the product remained stable between 1 and 1.4 bar. See details... Figure 4 This indicates that the product can stably provide an argon gas curtain during application, without any gas leakage or escaping issues.

[0076] It should be noted that those skilled in the art can make various modifications to this invention without departing from its principles, and these modifications and improvements also fall within the scope of protection of the claims of this invention.

Claims

1. A one-piece molded air curtain ceramic filter for continuous casting tundish, characterized in that, The device includes a strip-shaped structure, which contains an air chamber arranged along the length of the air. One end of the air chamber is closed, and the other end has a connecting port that communicates with the outside. An internal threaded connection port is pre-embedded at the connecting port. A diffused air-permeable layer is embedded on one side of the strip-shaped structure, and one side of the diffused air-permeable layer is the air chamber.

2. A method for preparing an integrally molded gas curtain ceramic filter for continuous casting tundish as described in claim 1, characterized in that, Includes the following steps: (1) Weigh the main material and the dispersion material: The main material includes the following raw materials by mass percentage: 65-85% alumina particles, 10-30% graphite, and 2-8% binder; The dispersion material includes the following raw materials by mass percentage: 50% alumina particles, 25% microporous nano-ceramic particles, 15% graphite, 5% binder, and 5% antioxidant; (2) Place the main material and the dispersed material in the mold, seal the mold, and press it into shape using the equal diameter pressing process. During the isostatic pressing process, control the molding pressure to 30~120Mpa and the holding time to 30 seconds~5 minutes. Press and demold to obtain the blank. (3) Curing: The green body is cured at 150~300℃ for 8~12 hours to obtain a cured green body; (4) Firing: The solidified green body is fired at 800~1200℃ for 2~6 hours to obtain the fired green body; (5) The blank is machined and fired to the required size to obtain a preliminary blank; (6) In the preliminary blank, the main material forms the air curtain ceramic filter body and the dispersion material forms the dispersion permeable layer. The air curtain ceramic filter body is impregnated or coated with a high-temperature sealing coating, and the dispersion permeable layer is impregnated or coated with an anti-oxidation erosion coating. After drying at 100~300℃ for 3~5 hours, the finished product is obtained.

3. The method for preparing an integrally molded gas curtain ceramic filter for continuous casting tundish according to claim 2, characterized in that, The high-temperature sealing coating comprises the following raw materials by weight percentage: 60-90% nano-sized ceramic powder and 10-40% high-temperature resistant inorganic binder, wherein the high-temperature resistant inorganic binder is aluminosilicate.

4. The method for preparing an integrally molded gas curtain ceramic filter for continuous casting tundish according to claim 2, characterized in that, The high-temperature sealing coating is produced using a high-speed asymmetric mixing process.

5. The method for preparing an integrally molded gas curtain ceramic filter for continuous casting tundish according to claim 1, characterized in that, The antioxidant erosion coating comprises the following raw materials in the following mass percentages: 30-50% high-temperature frit, 10-30% microporous nano-ceramic particles, 10-20% feldspar, and 10-30% aluminosilicate solution.

6. The method for preparing an integrally molded gas curtain ceramic filter for continuous casting tundish according to claim 2, characterized in that, The antioxidant erosion coating is produced using a high-speed asymmetric high-speed mixing process.

7. The method for preparing an integrally molded gas curtain ceramic filter for continuous casting tundish according to claim 2, characterized in that, The alumina particles have a particle size of ≤1.5mm.

8. The method for preparing an integrally molded gas curtain ceramic filter for continuous casting tundish according to claim 2, characterized in that, The microporous nanoceramic particles have a particle size of 10~850 μm.

9. The method for preparing an integrally molded gas curtain ceramic filter for continuous casting tundish according to claim 2, characterized in that, The binder is a modified phenolic resin, and the antioxidant is a magnesium-aluminum alloy or an aluminum-silicon alloy.

10. The method for preparing an integrally molded gas curtain ceramic filter for continuous casting tundish according to claim 2, characterized in that, The air chamber is formed by adding a wax model to a mold and having the wax model melt and disappear during the curing and firing process.

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