High-aluminum long-life tundish protection plate and preparation method thereof

Abstract

The invention relates to a high-aluminum long-service-life tundish protection plate and a preparation method, and belongs to the technical field of steelmaking and casting. The tundish protection plate is prepared from the following raw materials: dry base powder and an aluminum dihydrogen phosphate solution, wherein the dry base powder comprises the following components in percentage by mass: 20%-40% of bauxite, 15%-46% of corundum, 15%-30% of electric smelting magnesium aluminate spinel, 2%-5% of kyanite powder, 2%-8% of silicon carbide powder, 1%-3% of electric smelting magnesium powder, 2%-4% of zirconite powder, 1%-3% of silica powder and 1%-3% of a composite antioxidant. The protective plate material with excellent comprehensive performance can be formed through the combined action of the raw materials such as the bauxite, the corundum and the electric smelting magnesium aluminate spinel, the protective plate is tightly attached to the outer surface of the tundish dry material, the protective plate and the tundish dry material form a composite working layer, multiple challenges of the tundish working layer material under the high-temperature working condition are effectively solved, and the service life of the tundish working layer material is prolonged. The comprehensive performance of the material is remarkably improved, the service life is prolonged, and substantive technical progress is brought to the steelmaking industry.

Description

Technical Field

[0001] The present application relates to the technical field of steelmaking and casting, and in particular to a high-aluminum, long-life tundish protective plate and a preparation method thereof. Background Art

[0002] As the core equipment of modern continuous casting process, the high-temperature service performance of the working layer material of the tundish has a decisive impact on the control of molten steel cleanliness, the continuity of continuous casting and the production cost of the entire process.

[0003] The current industry's primary materials are magnesia / aluminum-magnesium dry or smear systems. However, these materials face multiple service challenges under high-temperature conditions of 1500-1600°C: binder failure occurs at 800-1200°C, resulting in a "loose" structure. When the temperature rises to 1500-1550°C, Al2O3 and SiO2 in the matrix form a low-melting-point calcite feldspar phase around 1530°C. These changes, combined with the continuous erosion of molten steel, chemical attack from slag, and cyclical thermal stresses, lead to progressive structural spalling in the working layer. Simultaneously, cyclical thermal shock stress triggers microcrack propagation. The synergistic effect of these destructive mechanisms results in a short service life for traditional single-layer structures, severely restricting continuous casting production efficiency. Summary of the Invention

[0004] The present application provides a high-aluminum, long-life tundish protective plate and a preparation method thereof to solve the following technical problem: how to solve the problem of low life of existing tundish working layer materials under high-temperature working conditions.

[0005] In a first aspect, an embodiment of the present application provides a high-alumina long-life tundish protection plate, wherein the raw materials of the tundish protection plate include: dry powder and aluminum dihydrogen phosphate solution;

[0006] Among them, the dry basis powder is calculated by mass fraction as follows: bauxite: 20% to 40%, corundum: 15% to 46%, fused magnesium aluminum spinel: 15% to 30%, kyanite powder: 2% to 5%, silicon carbide powder: 2% to 8%, fused magnesium powder: 1% to 3%, zircon powder: 2% to 4%, silicon micropowder: 1% to 3%, and composite antioxidant: 1% to 3%.

[0007] Optionally, the mass of the aluminum dihydrogen phosphate solution is 5% to 14% of the total mass of the dry powder.

[0008] Optionally, the mass of the bauxite with a particle size less than 0.074 mm is 20% to 30% of the total mass of the bauxite, the mass of the bauxite with a particle size greater than or equal to 0.074 mm and less than 1 mm is 22% to 28% of the total mass of the bauxite, the mass of the bauxite with a particle size greater than or equal to 1 mm and less than 3 mm is 15% to 20% of the total mass of the bauxite, and the mass of the bauxite with a particle size greater than or equal to 3 mm and less than or equal to 5 mm is 25% to 30% of the total mass of the bauxite.

[0009] Optionally, the Al2O3 content of the bauxite is ≥ 75% by mass.

[0010] Optionally, the mass of the corundum with a particle size less than 0.074 mm is 30% to 35% of the total mass of the corundum, the mass of the corundum with a particle size greater than or equal to 0.074 mm and less than 1 mm is 34% to 42% of the total mass of the corundum, and the mass of the corundum with a particle size greater than or equal to 1 mm and less than or equal to 3 mm is 20% to 30% of the total mass of the corundum.

[0011] Optionally, the corundum is at least one of plate-like corundum and white corundum.

[0012] Optionally, the mass of the fused magnesia alumina spinel with a particle size less than 0.074 mm is 25% to 35% of the total mass of the fused magnesia alumina spinel, the mass of the fused magnesia alumina spinel with a particle size greater than or equal to 0.074 mm and less than 1 mm is 20% to 30% of the total mass of the fused magnesia alumina spinel, and the mass of the fused magnesia alumina spinel with a particle size greater than or equal to 1 mm and less than or equal to 3 mm is 40% to 50% of the total mass of the fused magnesia alumina spinel.

[0013] Optionally, the fused magnesia alumina spinel is one of 75 aluminum-rich magnesia alumina spinel and 80 aluminum-rich magnesia alumina spinel.

[0014] Optionally, the composite antioxidant is composed of metallic silicon powder and metallic aluminum powder, and the mass ratio of the metallic silicon powder to the metallic aluminum powder is 1:(0.8-1.2).

[0015] Optionally, the particle size of the kyanite powder and the zircon powder are both 0.045 mm to 0.074 mm.

[0016] Optionally, the particle size of the silicon carbide powder is ≤0.074 mm.

[0017] Optionally, the particle size of the fused magnesium powder is ≤0.045 mm, and the MgO content of the fused magnesium powder is ≥97% by mass.

[0018] Optionally, the particle size of the silicon micropowder is ≤5 μm, and the SiO2 content of the silicon micropowder is ≥92% by mass.

[0019] In a second aspect, the present application provides a method for preparing the tundish protective plate described in the first aspect, the method comprising:

[0020] According to the mass fractions, the bauxite powder with a particle size of less than 1 mm, the corundum powder with a particle size of less than 1 mm, the fused magnesium aluminum spinel with a particle size of less than 1 mm, the kyanite powder, the silicon carbide powder, the fused magnesium powder, the zircon powder, the silicon micropowder and the composite antioxidant are first mixed to obtain a first mixture;

[0021] Adding the bauxite with a particle size of 1 mm to 5 mm, the corundum with a particle size of 1 mm to 3 mm, and the fused magnesia-aluminum spinel with a particle size of 1 mm to 3 mm to the first mixture for a second mixing to obtain a second mixture;

[0022] adding aluminum dihydrogen phosphate solution to the second mixed material, and performing a third mixing to obtain a mixed material;

[0023] The mixture is sequentially poured, cured and heat-insulated to obtain a finished tundish protective plate.

[0024] Optionally, the speeds of the first mixing and the second mixing are both 40 r / min to 60 r / min.

[0025] Optionally, the third mixing speed is 180 r / min to 220 r / min.

[0026] Optionally, the temperature of the heat preservation treatment is 200° C. to 300° C., and the time of the heat preservation treatment is 20 hours to 24 hours.

[0027] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0028] An embodiment of the present application provides a high-alumina long-life tundish protection plate, the raw materials of which include: dry basis powder and aluminum dihydrogen phosphate solution; wherein, the dry basis powder is, by mass fraction, bauxite: 20% to 40%, corundum: 15% to 46%, fused magnesia spinel: 15% to 30%, kyanite powder: 2% to 5%, silicon carbide powder: 2% to 8%, fused magnesium powder: 1% to 3%, zircon powder: 2% to 4%, silicon micropowder: 1% to 3%, and composite antioxidant: 1% to 3%. By constructing a high-alumina matrix system based on bauxite and corundum, the material's refractoriness and resistance to molten steel erosion are improved. The addition of fused magnesia-alumina spinel and silicon carbide creates a dual protective barrier, slowing slag penetration and enhancing resistance to slag erosion. The volume expansion effect of kyanite powder and the phase transformation toughening mechanism of zircon powder are utilized to absorb thermal stress and inhibit crack propagation. Composite antioxidants (metallic silicon powder and metallic aluminum powder) are used to prevent silicon carbide from destabilizing due to oxidation, extending the material's high-temperature service life. The tundish protective plate is tightly attached to the outer surface of the tundish dry material, forming a composite working layer. This effectively addresses the multiple challenges faced by the tundish working layer material under high-temperature conditions, significantly improving the material's overall performance and extending its service life, bringing substantial technological advancements to the steelmaking industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0030] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0031] Figure 1 A schematic flow chart of a method for preparing a high-aluminum, long-life tundish protective plate provided in an embodiment of the present application. DETAILED DESCRIPTION

[0032] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0033] Various embodiments of the present application may be presented in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity and should not be understood as a rigid limitation on the scope of the present application; therefore, the range description should be considered to have specifically disclosed all possible sub-ranges and single numerical values within the range; for example, the range description from 1 to 6 should be considered to have specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which apply regardless of the range; in addition, whenever a numerical range is indicated in this document, it is meant to include any cited number (fractional or integer) within the indicated range.

[0034] As used herein, the terms "including," "comprising," and the like mean "including but not limited to." Relational terms such as "first" and "second" are used solely to distinguish one entity or operation from another, and do not necessarily require or imply any actual relationship or order between these entities or operations. "And / or" describes the association relationship between associated objects, indicating that three relationships can exist. For example, "A and / or B" can mean: A exists alone, A and B exist at the same time, and B exists alone; where A and B can be singular or plural. "At least one" means one or more, "plurality" means two or more; "at least one," "at least one of the following" or similar expressions refers to any combination of these items, including any combination of single or plural items; for example, "at least one of a, b, or c" or "at least one of a, b, and c" can all mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can each be single or plural. "Parts" notation, such as parts by weight or parts by mass, indicates the proportional relationship between components. In this article, the parameters described by ratio should be understood as the first term of the proportional formula, in the order in which they are described, and the proportional figures should be understood as the second term. For example, if the mass ratio of substances A, B, and C is 1:2:3, then substances A, B, and C should correspond to the proportional figures in the proportional formula, in the order in which they are described: that is, the mass of substance A:the mass of substance B:the mass of substance C = 1:2:3.

[0035] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this article can be purchased from the market or prepared by existing methods.

[0036] In a first aspect, an embodiment of the present application provides a high-alumina long-life tundish protection plate, wherein the raw materials of the tundish protection plate include: dry powder and aluminum dihydrogen phosphate solution;

[0037] Among them, the dry basis powder is calculated by mass fraction as follows: bauxite: 20% to 40%, corundum: 15% to 46%, fused magnesium aluminum spinel: 15% to 30%, kyanite powder: 2% to 5%, silicon carbide powder: 2% to 8%, fused magnesium powder: 1% to 3%, zircon powder: 2% to 4%, silicon micropowder: 1% to 3%, and composite antioxidant: 1% to 3%.

[0038] The positive impact of limiting the mass fraction of bauxite to 20% to 40% is that, as an aluminum raw material, a mass fraction of bauxite within this range ensures the material's high refractoriness. Furthermore, combining 20% to 40% bauxite with other raw materials like corundum creates a high-aluminum matrix system. This system not only offers excellent resistance to molten steel erosion but also effectively resists chemical attack from molten slag, thereby extending the service life of the protective plate.

[0039] The positive effects of limiting the mass fraction of corundum to 15% to 46% are as follows: Corundum (Al2O3) is a material with high hardness and excellent wear resistance. Adding 15% to 46% corundum to the protective plate can significantly improve the material's overall hardness and wear resistance, thereby enhancing the plate's ability to resist molten steel erosion and mechanical wear. Furthermore, corundum has excellent chemical stability and can resist chemical attack from slag. In high-temperature environments, the corundum component can maintain structural stability, slowing the slag's erosion of the protective plate and extending its service life.

[0040] The positive effect of limiting the mass fraction of fused magnesia-alumina spinel to 15% to 30% is that fused magnesia-alumina spinel (MgAl2O4) can react with components such as FeO and CaO in steel slag under high temperature conditions to form high-melting-point phases such as magnesia-iron spinel. The formation of these high-melting-point phases can effectively slow the penetration of slag into the protective plate, thereby significantly enhancing the material's resistance to slag erosion. In addition, fused magnesia-alumina spinel has a low thermal expansion coefficient, which means that when the temperature changes rapidly, the thermal stress generated within the material will be relatively small. Therefore, adding 15% to 30% fused magnesia-alumina spinel helps improve the thermal shock resistance of the protective plate and reduce cracking and spalling caused by thermal stress.

[0041] The positive effect of limiting the mass fraction of kyanite powder to 2% to 5% is that kyanite powder converts to mullite at high temperatures, accompanied by a volume expansion of approximately 5%. This property effectively compensates for the shrinkage of the protective plate during sintering, reducing the internal stress caused by shrinkage, thereby preventing material cracking and improving the integrity and stability of the finished product. Furthermore, the volume expansion effect of kyanite powder at high temperatures can partially absorb thermal stress, reducing the impact of rapid temperature changes on the material. This is of great significance for improving the thermal shock resistance of the protective plate and helping to reduce cracking and spalling caused by thermal shock.

[0042] The positive effect of limiting the mass fraction of silicon carbide powder to 2% to 8% is that silicon carbide powder has an extremely high thermal conductivity, which can quickly disperse the heat generated within the protective plate. In high-temperature environments, this property helps reduce the temperature gradient within the material and alleviate the thermal stress caused by temperature differences, thereby improving the overall stability of the protective plate. In addition, during the high-temperature oxidation process, silicon carbide powder can form a dense SiO2 protective layer, which can effectively prevent further erosion of the protective plate by slag, thereby improving the material's resistance to slag erosion.

[0043] The positive effects of limiting the mass fraction of fused magnesium powder to 1% to 3% are as follows: The main component of fused magnesium powder is MgO, which has a high melting point. Adding 1% to 3% of fused magnesium powder to the protective plate can improve the material's overall high-temperature resistance, maintaining stability in environments exposed to high-temperature molten steel and slag corrosion. Furthermore, MgO reacts with certain components in the slag (such as SiO2) at high temperatures to form high-melting-point compounds. The formation of these compounds can slow the slag's erosion of the protective plate, improving the material's resistance to slag corrosion.

[0044] Limiting the zircon powder mass fraction to 2% to 4% has the following positive effects: The ZrO2 in the zircon powder undergoes a phase transformation at high temperatures, absorbing some thermal stress and thus improving the material's spalling resistance. This phase transformation and toughening effect is particularly pronounced during cyclic thermal shock, helping to reduce spalling on the protective plate surface caused by thermal stress. Furthermore, at high temperatures, zircon powder reacts with Al2O3 to form a high-melting-point zirconium corundum phase (ZrO2·Al2O3) with a melting point exceeding 1800°C. This high-melting-point phase effectively inhibits slag erosion of the protective plate, improving the material's resistance to slag erosion.

[0045] The positive effects of limiting the mass fraction of silicon micropowder to 1% to 3% are: As a fine powder, silicon micropowder can fill the gaps between other raw material particles, increasing the material's bulk density and compactness. This helps reduce apparent porosity and enhances the material's mechanical properties and corrosion resistance. Furthermore, at high temperatures, the SiO2 in silicon micropowder can react with other raw materials to form high-temperature stable phases such as mullite, improving the material's high-temperature stability.

[0046] The positive effect of limiting the mass fraction of the composite antioxidant to 1% to 3% is that the composite antioxidant, composed of metallic silicon powder and metallic aluminum powder, preferentially oxidizes at high temperatures, forming a dense glass phase. This glass phase effectively isolates oxygen, preventing silicon carbide from destabilizing due to oxidation, thereby maintaining its high-temperature stability and corrosion resistance. The addition of the composite antioxidant provides an additional layer of antioxidant protection for the protective plate material. In high-temperature environments, this layer of protection can slow the material's oxidation rate and extend its service life.

[0047] In some embodiments, the mass of the aluminum dihydrogen phosphate solution is 5% to 14% of the total mass of the dry powder.

[0048] Aluminum dihydrogen phosphate solution has a gelling effect at room temperature, which can bond dry powder particles together to provide initial strength for the protective plate, which helps to maintain the shape and integrity of the protective plate during subsequent processing and handling; at high temperatures, aluminum dihydrogen phosphate solution will dehydrate to form AlPO4 ceramic binding phase, which has excellent high-temperature stability and can further enhance the structural strength of the protective plate, making it stable in the environment of high-temperature molten steel scouring and slag erosion; the addition of aluminum dihydrogen phosphate solution makes the protective plate material have better fluidity and plasticity during the mixing and pouring process, facilitating construction operations, which helps to improve production efficiency and reduce construction difficulty.

[0049] In some embodiments, the bauxite has an Al2O3 content of ≥ 75% by mass.

[0050] The Al2O3 component in bauxite helps improve the material's high-temperature resistance, allowing it to remain stable in environments of high-temperature molten steel erosion and slag corrosion.

[0051] In some embodiments, the corundum is at least one of tabular corundum and white corundum.

[0052] Both tabular corundum and white corundum have high melting point characteristics and can withstand high-temperature molten steel erosion and slag erosion, ensuring the stability of the protective plate in high-temperature environments.

[0053] In some embodiments, the mass of the bauxite with a particle size less than 0.074 mm is 20% to 30% of the total mass of the bauxite, the mass of the bauxite with a particle size greater than or equal to 0.074 mm and less than 1 mm is 22% to 28% of the total mass of the bauxite, the mass of the bauxite with a particle size greater than or equal to 1 mm and less than 3 mm is 15% to 20% of the total mass of the bauxite, and the mass of the bauxite with a particle size greater than or equal to 3 mm and less than or equal to 5 mm is 25% to 30% of the total mass of the bauxite.

[0054] In some embodiments, the mass of the corundum with a particle size less than 0.074 mm is 30% to 35% of the total mass of the corundum, the mass of the corundum with a particle size greater than or equal to 0.074 mm and less than 1 mm is 34% to 42% of the total mass of the corundum, and the mass of the corundum with a particle size greater than or equal to 1 mm and less than or equal to 3 mm is 20% to 30% of the total mass of the corundum.

[0055] In some embodiments, the mass of the fused magnesia alumina spinel with a particle size less than 0.074 mm is 25% to 35% of the total mass of the fused magnesia alumina spinel, the mass of the fused magnesia alumina spinel with a particle size greater than or equal to 0.074 mm and less than 1 mm is 20% to 30% of the total mass of the fused magnesia alumina spinel, and the mass of the fused magnesia alumina spinel with a particle size greater than or equal to 1 mm and less than or equal to 3 mm is 40% to 50% of the total mass of the fused magnesia alumina spinel.

[0056] By precisely designing the particle size composition of bauxite, corundum and fused magnesia-aluminum spinel, close packing between particles of different particle sizes can be achieved, thereby optimizing the packing density of the material. Close packing helps to reduce voids in the material, improve the density of the protective plate, and thus enhance its mechanical properties and corrosion resistance; an appropriate proportion of coarse and fine particles can balance the fluidity and plasticity of the material. Coarse particles can provide skeleton support, while fine particles can fill the gaps, making the protective plate material easier to operate during the mixing and pouring process, thereby improving construction efficiency; the diversification of particle size composition helps to disperse the thermal stress generated by the material during thermal shock. Fine particles can absorb part of the thermal stress and slow down the expansion of cracks, while coarse particles can provide a stable skeleton structure and maintain the overall stability of the material; finally, particles of different sizes can be more evenly distributed during the mixing process, avoiding uneven performance caused by particles that are too large or too small in local areas. Uniform mixing helps to improve the overall performance and stability of the protective plate material.

[0057] In some embodiments, the fused magnesia alumina spinel is one of 75 aluminum-rich magnesia alumina spinel and 80 aluminum-rich magnesia alumina spinel.

[0058] 75 Al-rich Magnesium Aluminate Spinel indicates it contains 75% alumina (by weight), while 80 Al-rich Magnesium Aluminate Spinel contains 80% alumina. Both Al-rich Magnesium Aluminate Spinels have high melting points, excellent chemical stability, and thermal shock resistance. They can withstand high-temperature molten steel erosion and slag corrosion, ensuring the stability of the protective plate in high-temperature environments. This characteristic significantly improves the material's refractoriness, enabling it to operate for extended periods under harsh working conditions.

[0059] In some embodiments, the composite antioxidant is composed of metallic silicon powder and metallic aluminum powder, and the mass ratio of the metallic silicon powder to the metallic aluminum powder is 1:(0.8-1.2).

[0060] Mixing metallic silicon powder and metallic aluminum powder in a specific ratio (1:(0.8-1.2)) can exert a synergistic antioxidant effect. This ratio was optimized through experiments to ensure that the oxidation reaction of the two at high temperatures is neither too intense nor too weak, thus achieving the best antioxidant effect.

[0061] In some embodiments, the particle size of the kyanite powder and the zircon powder are both 0.045 mm to 0.074 mm.

[0062] In some embodiments, the particle size of the silicon carbide powder is ≤0.074 mm.

[0063] In some embodiments, the particle size of the fused magnesium powder is ≤0.045 mm, and the MgO content of the fused magnesium powder is ≥97% by mass.

[0064] The MgO content in the fused magnesium powder is ≥97%, ensuring its high purity and excellent performance, providing a stable magnesium source for the protective plate. The particle size is controlled at ≤0.045mm, which helps the fused magnesium powder to be evenly distributed in the protective plate material, improving the overall homogeneity of the material.

[0065] In some embodiments, the particle size of the silicon micropowder is ≤5 μm, and the SiO 2 content of the silicon micropowder is ≥92% by mass.

[0066] The particle size of silicon micropowder is extremely fine (≤5μm), which can fill the gaps between material particles and improve the density of the material.

[0067] Figure 1 A schematic flow chart of a method for preparing a high-aluminum, long-life tundish protective plate provided in an embodiment of the present application.

[0068] See Figure 1 In a second aspect, the present application provides a method for preparing the tundish protective plate described in the first aspect, the method comprising:

[0069] S1. According to the mass fractions, the bauxite powder with a particle size of less than 1 mm, the corundum powder with a particle size of less than 1 mm, the fused magnesium aluminum spinel with a particle size of less than 1 mm, the kyanite powder, the silicon carbide powder, the fused magnesium powder, the zircon powder, the silicon micropowder and the composite antioxidant are first mixed to obtain a first mixture;

[0070] S2, adding the bauxite with a particle size of 1 mm to 5 mm, the corundum with a particle size of 1 mm to 3 mm, and the fused magnesia-aluminum spinel with a particle size of 1 mm to 3 mm to the first mixture for a second mixing to obtain a second mixture;

[0071] Grading and mixing raw material powders of different particle sizes is conducive to achieving uniform mixing of the powders. At the same time, it avoids excessive grinding of small particle raw materials by large particle raw materials during the mixing process, maintains the particle size distribution of the raw materials, helps to optimize the packing density, reduce sintering shrinkage, and thus enhance the density of the overall structure.

[0072] In some embodiments, the speeds of the first mixing and the second mixing are both 40 r / min to 60 r / min.

[0073] The speed of the first mixing and the second mixing is controlled at 40-60r / min, which can not only ensure the mixing effect but also avoid overheating and change of raw material properties.

[0074] S3, adding aluminum dihydrogen phosphate solution to the second mixed material, performing a third mixing to obtain a mixed material;

[0075] In some embodiments, the third mixing speed is 180 r / min to 220 r / min.

[0076] Increasing the mixing speed to 180-220 r / min helps the aluminum dihydrogen phosphate solution fully combine with the powder to form a uniform slurry, laying a good foundation for subsequent casting and molding. High-speed mixing (180-220 r / min) of the aluminum dihydrogen phosphate solution ensures that the binder quickly and evenly penetrates the powder, improving the molding properties of the mixture.

[0077] S4. Casting, curing and heat-insulating the mixture in sequence to obtain a finished tundish protective plate.

[0078] In the embodiment of the present application, during pouring, hanging rings can be symmetrically arranged on both sides of the top of the protective plate, which not only facilitates subsequent handling and installation operations, but also ensures the stability of the protective plate during curing and heat treatment, and reduces the risk of damage due to improper handling. After pouring, the formed blank is placed in a constant temperature and humidity curing room (the temperature can be 22°C to 28°C, and the humidity can be 50% to 60%) for 36h to 48h, which helps the water in the slurry to evaporate slowly and evenly, and reduces the internal stress concentration and cracking caused by drying too quickly. At the same time, the constant temperature and humidity environment is conducive to the gelling effect of aluminum dihydrogen phosphate solution and provides initial strength. After demoulding, it is transferred to the natural environment for continued curing for 20h to 24h, which further consolidates the strength of the material and allows it to gradually adapt to changes in the external environment. Finally, it is placed in a heat treatment furnace for insulation treatment for 20h to 24h.

[0079] In some embodiments, the temperature of the heat preservation treatment is 200° C. to 300° C., and the time of the heat preservation treatment is 20 h to 24 h.

[0080] The thermal insulation treatment helps to adjust and stabilize the internal structure of the material and improve the density and strength of the material. During the thermal insulation treatment, aluminum dihydrogen phosphate is dehydrated to form AlPO4 ceramic binding phase, which further enhances the high-temperature stability of the material.

[0081] In actual application, the protective plate of the embodiment of the present application is tightly fitted to the outer surface of the dry material in the tundish, and is kept flush with the upper mouth of the tundish. Its shape and size are fully adapted to the wall of the tundish, and the joint gap between two adjacent pieces can adopt an oblique or right-angled trapezoidal structure. The protective plate and the dry material in the tundish form a composite working layer, which can effectively delay slag penetration and structural peeling in the harsh environment of molten steel scouring and slag erosion, and significantly improve the overall service life of the tundish refractory material.

[0082] The embodiment of the present application constructs a high-aluminum matrix system based on bauxite and corundum to ensure that the material has high refractoriness and excellent resistance to molten steel erosion. By precisely designing the gradation of coarse and fine particles, the packing density is optimized, the sintering shrinkage is effectively reduced, and the density of the overall structure is enhanced. In terms of corrosion resistance, a strategy of synergistic action of fused magnesium-aluminum spinel and silicon carbide is adopted. Under high temperature conditions, fused magnesium-aluminum spinel reacts with FeO and CaO in steel slag to generate high-melting-point magnesium-iron spinel and other phases, slowing down the penetration rate of slag; its low thermal expansion coefficient significantly improves the thermal shock resistance of the material. At the same time, silicon carbide quickly disperses thermal stress due to its high thermal conductivity, and forms a SiO2 protective layer during high-temperature oxidation, further enhancing its resistance to slag erosion, and forming a double protective barrier together with fused magnesium-aluminum spinel. In order to compensate for sintering shrinkage and inhibit crack propagation, the scheme introduces kyanite powder, utilizing the volume expansion effect produced when it is converted into mullite at high temperature. In addition, the phase transformation toughening mechanism of ZrO2 in zircon powder absorbs thermal stress and improves the material's anti-spalling properties. By generating a high-melting-point zirconium corundum phase (ZrO2·Al2O3) with a melting point exceeding 1800°C, the eutectic reaction is effectively suppressed. A composite antioxidant is also used to preferentially oxidize the silicon carbide to form a dense glass phase, preventing the silicon carbide from becoming unstable due to oxidation and significantly extending the material's high-temperature service life. In terms of the bonding system and sintering aids, the gelling effect of aluminum dihydrogen phosphate is utilized at room temperature to provide initial strength. At high temperatures, it dehydrates to form an AlPO4 ceramic bonding phase, balancing construction convenience with high-temperature stability. The introduction of nano-scale SiO2 in the silicon micropowder fills the intergranular spaces and reacts with Al2O3 at high temperatures to form mullite, promoting sintering densification and reducing apparent porosity.

[0083] The present application is further described below with reference to specific examples. Experimental methods in the following examples where specific conditions are not specified are generally measured in accordance with national / industry standards. If there are no corresponding national / industry standards, the methods are carried out in accordance with commonly used international standards, conventional conditions, or conditions recommended by the manufacturer.

[0084] Example 1

[0085] A high-alumina long-life tundish protective plate, the raw materials of which, calculated by mass fraction, include: 40% bauxite, 26% corundum, 15% fused magnesia-alumina spinel, 5% kyanite, 5% silicon carbide, 1% fused magnesium powder, 3% zircon powder, 2% silicon micropowder, and 3% composite antioxidant. The mass of the added aluminum dihydrogen phosphate solution is 8% of the total mass of the above-mentioned dry powder; the composition of bauxite is: particle size <0.074mm accounts for 25%, 0.074mm≤particle size <1mm accounts for 28%, 1mm≤particle size <3mm accounts for 18.5%, 3mm≤particle size ≤5mm accounts for 28.5%; the composition of corundum is: particle size <0.074mm accounts for 34%, 0.074mm≤particle size <1mm accounts for 40%, 1mm≤particle size ≤3mm accounts for 26%; the composition of fused magnesia alumina spinel is: particle size <0.074mm accounts for 25%, 0.074mm≤particle size <1mm accounts for 25%, 1mm≤particle size ≤3mm accounts for 50%. The bauxite is special-grade bauxite with Al2O3≥75%, the corundum is plate-shaped corundum, and the fused magnesia-alumina spinel is 75% aluminum-rich magnesia-alumina spinel; the mass ratio of the metal silicon powder to the metal aluminum powder in the composite antioxidant is 1:1.

[0086] The preparation method of a high-alumina long-life tundish protective plate comprises the following steps: 1) placing bauxite, corundum, fused magnesium aluminate spinel, kyanite powder, silicon carbide powder, fused magnesium powder, zircon powder, silicon micropowder and a composite antioxidant with a particle size of less than 1 mm in a mixer in proportion and kneading at 50 r / min for 6 minutes; 2) adding bauxite with a particle size of 1 mm to 5 mm, corundum of 1 mm to 3 mm and fused magnesium aluminate spinel of 1 mm to 3 mm to the uniformly kneaded fine powder mixture, and continuing to knead at 50 r / min for 3 minutes; 3) adding aluminum dihydrogen phosphate solution to the mixture, mixing at high speed for 6 minutes until uniform, and immediately pouring it into a mold for casting and molding, and symmetrically setting rings on both sides of the top of the protective plate during casting; 4) placing the formed blank in a constant temperature and humidity curing room for 48 hours, transferring it to a natural environment after demoulding and continuing to cure for 24 hours, and finally placing it in a heat treatment furnace at 200°C to 300°C for insulation treatment for 20 hours to obtain a finished product.

[0087] Example 2

[0088] A high-alumina long-life tundish protective plate, the raw materials of which, calculated by mass fraction, include: 35% bauxite, 30% corundum, 20% fused magnesia-alumina spinel, 3% kyanite, 5% silicon carbide, 1% fused magnesium powder, 2% zircon powder, 2% silicon micropowder, and 2% composite antioxidant. The mass of the added aluminum dihydrogen phosphate solution is 9% of the total mass of the above-mentioned dry powder; the composition of bauxite is: particle size <0.074mm accounts for 30%, 0.074mm≤particle size <1mm accounts for 24%, 1mm≤particle size <3mm accounts for 20%, 3mm≤particle size ≤5mm accounts for 26%; the composition of corundum is: particle size <0.074mm accounts for 33%, 0.074mm≤particle size <1mm accounts for 40%, 1mm≤particle size ≤3mm accounts for 27%; the composition of fused magnesia alumina spinel is: particle size <0.074mm accounts for 30%, 0.074mm≤particle size <1mm accounts for 25%, 1mm≤particle size ≤3mm accounts for 45%. The bauxite is first-grade bauxite with Al2O3≥75%; the corundum is white corundum; the fused magnesia-alumina spinel is 80% aluminum-rich magnesia-alumina spinel; and the mass ratio of the metal silicon powder to the metal aluminum powder in the composite antioxidant is 1:1.2.

[0089] The method for preparing a high-alumina long-life tundish protective plate comprises the following steps: 1) placing bauxite with a particle size of less than 1 mm, corundum, fused magnesia alumina spinel, kyanite powder, silicon carbide powder, fused magnesium powder, zircon powder, silicon micropowder, and a composite antioxidant in a mixing mill in proportion and mixing at 40 rpm for 5 minutes; 2) adding bauxite with a particle size of 1 mm to 5 mm, corundum with a particle size of 1 mm to 3 mm, and fused magnesia alumina spinel with a particle size of 1 mm to 3 mm to the uniformly mixed fine powder mixture; , continue mixing at 40r / min for 4min; 3) add aluminum dihydrogen phosphate solution to the mixture, mix at 220r / min for 8min until uniform, and immediately pour it into the mold for casting and molding. During casting, set rings symmetrically on both sides of the top of the protective plate; 4) place the molded body in a constant temperature and humidity curing room for 36h, and after demolding, transfer it to the natural environment for further curing for 24h, and finally place it in a heat treatment furnace at 200℃~300℃ for insulation treatment for 20h to obtain the finished product.

[0090] Example 3

[0091] A high-alumina long-life tundish protective plate, the raw materials of which, calculated by mass fraction, include: 30% bauxite, 39% corundum, 16% fused magnesia-alumina spinel, 2% kyanite, 4% silicon carbide, 3% fused magnesium powder, 3.5% zircon powder, 1% silicon micropowder, and 1.5% composite antioxidant. The mass of the added aluminum dihydrogen phosphate solution is 11% of the total mass of the above-mentioned dry powder; the composition of bauxite is: particle size <0.074mm accounts for 30%, 0.074mm≤particle size <1mm accounts for 25%, 1mm≤particle size <3mm accounts for 20%, 3mm≤particle size ≤5mm accounts for 25%; the composition of corundum is: particle size <0.074mm accounts for 32%, 0.074mm≤particle size <1mm accounts for 38%, 1mm≤particle size ≤3mm accounts for 30%; the composition of fused magnesia alumina spinel is: particle size <0.074mm accounts for 33%, 0.074mm≤particle size <1mm accounts for 27%, 1mm≤particle size ≤3mm accounts for 40%. The bauxite is first-grade bauxite with Al2O3≥75%; the corundum is plate-shaped corundum; the fused magnesia-alumina spinel is 70% aluminum-rich magnesia-alumina spinel; and the mass ratio of metallic silicon powder to metallic aluminum powder in the composite antioxidant is 1:0.8.

[0092] The method for preparing a high-alumina long-life tundish protective plate comprises the following steps: 1) placing bauxite with a particle size of less than 1 mm, corundum, fused magnesium aluminate spinel, kyanite powder, silicon carbide powder, fused magnesium powder, zircon powder, silicon micropowder, and a composite antioxidant in a mixing mill in proportion and mixing at 40 rpm for 3 minutes; 2) adding bauxite with a particle size of 1 mm to 5 mm, corundum with a particle size of 1 mm to 3 mm, and fused magnesium aluminate spinel with a particle size of 1 mm to 3 mm to the uniformly mixed fine powder mixture; , continue mixing at 40r / min for 5min; 3) add aluminum dihydrogen phosphate solution to the mixture, mix at 220r / min for 6min until uniform, and immediately pour it into the mold for casting and molding. During casting, set hanging rings symmetrically on both sides of the top of the protective plate; 4) place the molded body in a constant temperature and humidity curing room for 40h, and after demolding, transfer it to the natural environment for further curing for 20h, and finally place it in a heat treatment furnace at 200℃~300℃ for 24h to obtain the finished product.

[0093] Comparative Example 1

[0094] A tundish magnesium dry material comprises, by mass fraction, 74% fused magnesia, 20% 95% sand ≤0.074 mm, and 6% powdered resin, wherein the fused magnesia is composed of: 23% with a particle size <0.074 mm, 30% with a particle size ≤0.074 mm and <1 mm, 38% with a particle size ≤1 mm, and 9% with a particle size ≤3 mm and ≤5 mm.

[0095] The physical and chemical properties of the finished products in the examples and comparative examples were tested under different temperature conditions. The results are shown in Table 1.

[0096] Table 1

[0097]

[0098] It can be seen from the data in Table 1 that the key indicators such as volume density, compressive strength, and flexural strength of the ladle protection plate prepared by the method provided in the examples of the present application are better than those of the traditional dry materials; the re-burning line change rate is reduced, indicating that the thermal shock resistance of the material is improved; the apparent porosity is reduced, indicating that the material is denser and the corrosion resistance is enhanced.

[0099] One or more technical solutions in the embodiments of the present invention may have at least the following technical effects or advantages:

[0100] In the embodiment of the present application, the service life of the intermediate refractory material is increased from the original 5 hours to more than 26 hours, which greatly improves the continuous casting production efficiency.

[0101] The foregoing is merely a list of specific embodiments of the present application, intended to enable those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application is not limited to the embodiments shown herein, but rather is intended to conform to the broadest scope consistent with the principles and novel features claimed herein.

Claims

1. A high-aluminum, long-life tundish protective plate, the raw materials of which include: Dry basis powder and aluminum dihydrogen phosphate solution; Among them, the dry basis powder is calculated by mass fraction as follows: bauxite: 20% to 40%, corundum: 15% to 46%, fused magnesium aluminum spinel: 15% to 30%, kyanite powder: 2% to 5%, silicon carbide powder: 2% to 8%, fused magnesium powder: 1% to 3%, zircon powder: 2% to 4%, silicon micropowder: 1% to 3%, and composite antioxidant: 1% to 3%.

2. The tundish protection plate according to claim 1, characterized in that: The mass of the aluminum dihydrogen phosphate solution is 5% to 14% of the total mass of the dry powder.

3. The tundish protection plate according to claim 1, characterized in that: The mass of the bauxite with a particle size of less than 0.074 mm is 20% to 30% of the total mass of the bauxite, the mass of the bauxite with a particle size greater than or equal to 0.074 mm and less than 1 mm is 22% to 28% of the total mass of the bauxite, the mass of the bauxite with a particle size greater than or equal to 1 mm and less than 3 mm is 15% to 20% of the total mass of the bauxite, and the mass of the bauxite with a particle size greater than or equal to 3 mm and less than or equal to 5 mm is 25% to 30% of the total mass of the bauxite; Calculated by mass fraction, the Al2O3 content of the bauxite is ≥ 75%.

4. The tundish protection plate according to claim 1, characterized in that: The mass of the corundum with a particle size less than 0.074 mm is 30% to 35% of the total mass of the corundum, the mass of the corundum with a particle size greater than or equal to 0.074 mm and less than 1 mm is 34% to 42% of the total mass of the corundum, and the mass of the corundum with a particle size greater than or equal to 1 mm and less than or equal to 3 mm is 20% to 30% of the total mass of the corundum; The corundum is at least one of plate-shaped corundum and white corundum.

5. The tundish protection plate according to claim 1, characterized in that: The mass of the fused magnesia alumina spinel with a particle size of less than 0.074 mm is 25% to 35% of the total mass of the fused magnesia alumina spinel, the mass of the fused magnesia alumina spinel with a particle size greater than or equal to 0.074 mm and less than 1 mm is 20% to 30% of the total mass of the fused magnesia alumina spinel, and the mass of the fused magnesia alumina spinel with a particle size greater than or equal to 1 mm and less than or equal to 3 mm is 40% to 50% of the total mass of the fused magnesia alumina spinel; The fused magnesia alumina spinel is one of 75 aluminum-rich magnesia alumina spinel and 80 aluminum-rich magnesia alumina spinel.

6. The tundish protection plate according to claim 1, characterized in that: The composite antioxidant consists of metallic silicon powder and metallic aluminum powder, and the mass ratio of the metallic silicon powder to the metallic aluminum powder is 1:(0.8-1.2).

7. The tundish protection plate according to claim 1, characterized in that: The particle sizes of the kyanite powder and the zircon powder are both 0.045 mm to 0.074 mm; and / or, The particle size of the silicon carbide powder is ≤0.074 mm; and / or, The particle size of the fused magnesium powder is ≤0.045 mm, and the MgO content of the fused magnesium powder is ≥97% by mass; and / or, The particle size of the silicon micropowder is ≤5 μm, and the SiO2 content of the silicon micropowder is ≥92% by mass.

8. A method for preparing the tundish protective plate according to any one of claims 1 to 7, comprising: According to the mass fractions, the bauxite powder with a particle size of less than 1 mm, the corundum powder with a particle size of less than 1 mm, the fused magnesium aluminum spinel with a particle size of less than 1 mm, the kyanite powder, the silicon carbide powder, the fused magnesium powder, the zircon powder, the silicon micropowder and the composite antioxidant are first mixed to obtain a first mixture; Adding the bauxite with a particle size of 1 mm to 5 mm, the corundum with a particle size of 1 mm to 3 mm, and the fused magnesia-aluminum spinel with a particle size of 1 mm to 3 mm to the first mixture for a second mixing to obtain a second mixture; adding aluminum dihydrogen phosphate solution to the second mixed material, and performing a third mixing to obtain a mixed material; The mixture is sequentially poured, cured and heat-insulated to obtain a finished tundish protective plate.

9. The method according to claim 8, characterized in that The speeds of the first mixing and the second mixing are both 40 r / min to 60 r / min; and / or, The speed of the third mixing is 180 r / min to 220 r / min.

10. The method according to claim 8, characterized in that The temperature of the heat preservation treatment is 200° C. to 300° C., and the time of the heat preservation treatment is 20 hours to 24 hours.

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