A regenerative magnesium-aluminum-carbon-based high-thermal-shock-resistant tundish dam and a preparation method thereof

Abstract

The application discloses a regenerated magnesia-alumina-carbon-based high-thermal shock resistance tundish dam and a preparation method thereof, and belongs to the technical field of refractory materials. The tundish dam takes 30-38 parts of raw forsterite with a particle size of 15-8 mm as aggregate, takes 5-15 parts of regenerated magnesia-alumina-carbon with a particle size of 5-3 mm and 10-25 parts of regenerated magnesia-alumina-carbon with a particle size of 3-1 mm as core functional components, is supplemented with 10-20 parts of regenerated magnesia-alumina-carbon with a particle size of 1-0 mm and 10-20 parts of 180-mesh 97 electrically fused magnesia-dicalcium, 1-5 parts of metallic silicon and 2-6 parts of zircon-containing silica ash, and through the synergism of the residual carbon heat conduction, the zirconia phase change toughening and the dicalcium magnesia slag resistance mechanism, the thermal shock stability and the corrosion resistance are significantly improved. The tundish dam has a water-cooling thermal shock frequency of 1100 DEG C of 15 times or more, the comprehensive cost is reduced, the finished product rate is 98% or more, and the unification of solid waste high-value utilization and high performance is realized.

Description

Technical Field

[0001] This invention belongs to the field of refractory materials technology, specifically relating to a recycled magnesium-aluminum-carbon-based high thermal shock resistant tundish slag-blocking weir and its preparation method. Background Technology

[0002] The tundish is an important metallurgical vessel in a continuous casting system. Its slag weir is used to separate the pouring zone and the diversion zone, guide the flow of molten steel, promote the flotation of inclusions, and prevent slag entrapment. It is a key functional component for improving the cleanliness of molten steel. During operation, the slag weir must withstand the intense scouring of high-temperature molten steel, the chemical erosion of the slag line, and frequent temperature shocks (such as during pouring start-up, ladle change, and pouring stop). Therefore, extremely high requirements are placed on its thermal shock resistance, slag erosion resistance, and structural strength.

[0003] Traditional slag weirs mostly use magnesia or magnesia-alumina castables, but they have the following technical drawbacks: 1. Insufficient thermal shock stability: Ordinary magnesium materials have a high coefficient of thermal expansion and a large elastic modulus. Under rapid cooling and heating conditions, they are prone to thermal stress, which can lead to cracking, peeling, or even overall fracture, seriously affecting service life and slag-blocking effect.

[0004] 2. Resistance to slag erosion needs to be improved: Steel slag is rich in FeO, SiO2 and other components, which are easy to react with magnesia to form a low melting point phase, resulting in a loose structure and erosion.

[0005] 3. Raw material costs and environmental pressures: The extensive use of high-quality raw materials such as virgin fused magnesia and silicon carbide results in high costs and does not fully utilize waste refractory material resources.

[0006] Therefore, developing a tundish slag-blocking weir that combines excellent thermal shock resistance, superior slag resistance, and controllable cost is of great significance for improving continuous casting production efficiency and reducing refractory consumption. Patent application CN117800746A discloses a tundish slag-blocking wall castable suitable for low-carbon steel and its preparation method. This technology uses white corundum and MgO... Using Al2O3 spinel and magnesium allon as the main raw materials, the solid solution phase significantly improves slag erosion resistance and strength, but the raw material cost is high, and it does not involve the resource utilization of waste refractory materials. Patent application CN117226084A discloses a method for reducing alumina inclusions in molten steel in a tundish. This technology involves a magnesium oxide-silicon carbide slag weir, which reduces inclusions through electric field coupling with the material, but the improvement in thermal shock stability is limited, and the use of phenolic resin bonding poses a significant environmental challenge. Patent application CN118184313A discloses a low-cost continuous casting tundish slag weir. This technology adopts a composite layer structure design and utilizes waste magnesium-carbon bricks to reduce costs, but thermal stress concentration easily occurs at the junction of the core and the outer periphery, and the overall thermal shock stability still needs improvement. Patent application CN118184314A discloses a spinel slag weir for intermediate ladles. This technology utilizes waste cement kiln material and used magnesium aluminum spinel bricks to achieve resource reuse. However, the low-melting-point phase contained in the waste cement kiln material may reduce the high-temperature performance of the material.

[0007] A comprehensive analysis of the existing technologies reveals that recent research focus on magnesia slag weirs / walls for tundishes has primarily centered on the resource utilization of waste refractory materials, composite layer structure design, introduction of functional additives, and optimization of the bonding system. However, existing technologies still fall short in systematically improving thermal shock stability, particularly in the synergistic utilization of residual carbon from recycled raw materials, the toughening mechanism of zirconium oxide, and the slag-resistant properties of dicalcium magnesia sand. This lack of effective integration provides a technological space for innovation in this invention. Summary of the Invention

[0008] One of the objectives of this invention is to provide a recycled magnesium-aluminum-carbon-based tundish slag weir with high thermal shock resistance, which solves the problems of poor thermal shock stability, easy cracking and spalling, insufficient slag erosion resistance and short service life of traditional magnesium / magnesium-aluminum tundish slag weirs.

[0009] The second objective of this invention is to provide a method for preparing a recycled magnesium-aluminum-carbon-based high thermal shock resistant tundish slag weir, which is used to prepare the aforementioned magnesium-aluminum-carbon tundish slag weir with excellent thermal shock resistance.

[0010] The objective of this invention can be achieved through the following technical solutions: In a first aspect, a recycled magnesium-aluminum-carbon-based high thermal shock resistant tundish slag-blocking weir, comprising the following components by weight: 30-38 parts of raw magnesium olivine with a grain size of 15-8 mm; 5-15 parts of recycled magnesium aluminum carbon with a particle size of 5-3 mm; 10-25 parts of recycled magnesium aluminum carbon with a particle size of 3-1 mm; 10-20 parts of 97 electrofused dicalcium magnesium sand with a particle size of 1-0 mm; 10-20 parts of fused dicalcium magnesium sand with a particle size of 180 mesh and 97 mm. 1-5 parts of metallic silicon with a particle size <240 mesh; 2-6 parts of zirconium silicate ash with a particle size <2μm; And 0.1 to 0.15 parts of dispersant, 0.01 to 0.02 parts of retarder and 0.06 to 0.08 parts of explosion-proof fiber, accounting for 0.1 to 0.15 parts of the total weight of the above raw materials.

[0011] Raw magnesium olivine: MgO mass percentage ≥45%, as an aggregate, provides a stable magnesium matrix, while its low coefficient of thermal expansion helps improve the thermal shock resistance of the material.

[0012] Recycled magnesium-aluminum-carbon (MgA-C) bricks: These are obtained from waste MgA-C bricks (such as ladle molten pool bricks and ladle bottom bricks) recycled from steel mills through processes such as crushing, slag removal, iron removal, and shaping. This component not only achieves resource recycling, but its residual carbon content can effectively improve the material's slag wettability and thermal shock resistance, while the introduction of Al2O3 enhances the material's high-temperature strength.

[0013] 97 Fused dicalcium magnesia: In this sand, CaO and SiO2 preferentially form the high-melting-point dicalcium disilicate (C2S) phase rather than the low-melting-point silicate phase, thereby significantly improving the high-temperature erosion resistance of magnesium materials, especially their resistance to SiO2 erosion in slag.

[0014] Metallic silicon: At high temperatures, metallic silicon (Si) can react in situ to generate non-oxide reinforcing phases (such as SiC and Si3N4). These reinforcing phases fill the pores and matrix, significantly improving the strength, oxidation resistance and slag erosion resistance of the material. Their reinforcing effect is better than that of directly adding silicon carbide.

[0015] Zirconium-containing silica fume: Zirconium-containing silica fume combines the high fluidity and micro-filling effect of silica fume with the toughening mechanism of ZrO2. The phase transformation toughening effect of ZrO2 can effectively absorb the crack propagation energy generated by thermal shock, greatly improving the thermal shock stability of the material.

[0016] Dispersant: to reduce the amount of water added and increase the density of the material.

[0017] Retarder: Used to control construction time.

[0018] Explosion-proof fiber: It volatilizes at high temperatures to form microporous channels, preventing bursting during the baking process.

[0019] Furthermore, the raw magnesium olivine contains ≥45% MgO and ≤42% SiO2 by mass. This ensures the alkaline refractory properties and high-temperature structural strength of the aggregate, while preventing excessive SiO2 from reacting with other components to form a low-melting-point eutectic phase, thus ensuring the high-temperature stability of the slag weir matrix from the source of raw materials.

[0020] Furthermore, the recycled magnesium-aluminum-carbon alloy is obtained from waste steel ladle molten pool bricks or ladle bottom bricks recovered from steel mills through crushing, slag removal, magnetic separation for iron removal, shaping, and screening processes. The alloy contains MgO and Al2O3 with a combined mass percentage of ≥88%, a carbon content of 5-10%, and a bulk density of ≥2.8 g / cm³. 3 The recycled raw materials achieve both quality stability and functional effectiveness, while also balancing the material's thermal shock resistance and oxidation resistance, thus realizing the high-value utilization of solid waste resources.

[0021] Furthermore, the 97% fused dicalcium magnesia contains ≥97% MgO by mass, 1.5~2.5% CaO, and the CaO / SiO2 molar ratio is controlled between 1.8 and 2.2, with a bulk density ≥3.25 g / cm³. 3 This ensures that CaO and SiO2 preferentially react to form the high-melting-point dicalcium disilicate (C2S) phase, fundamentally avoiding the formation of the low-melting-point calcium magnesium olivine (CMS) phase, and significantly improving the slag-resistant weir's ability to resist slag erosion.

[0022] Furthermore, the mass percentage of Si in the metallic silicon is ≥98%, and the mass percentage of Fe2O3 is ≤0.5%. This ensures the purity and quantity of non-oxide reinforcing phases such as SiC and Si3N4 generated in situ at high temperatures, while avoiding the enrichment of low-melting-point ferrate phases such as Fe2O3 at grain boundaries, thus preventing a decrease in the material's high-temperature strength and corrosion resistance.

[0023] Furthermore, the zirconium-containing silica fume contains ≥92% SiO2 by mass, 1-3% ZrO2, ≤2% loss on ignition, and ≥15000 m² / g specific surface area. 2 / kg. It combines the highly active micro-filling effect of silica fume with the phase transformation toughening effect of ZrO2, which not only improves the material density but also effectively absorbs thermal shock crack propagation energy, while controlling raw material costs and high-temperature volume expansion.

[0024] Furthermore, the dispersant is at least one of sodium tripolyphosphate and sodium hexametasulfate.

[0025] Furthermore, the retarder is at least one of sodium citrate, sodium gluconate, and sodium tartrate.

[0026] Furthermore, the explosion-proof fiber is a polypropylene fiber with a diameter of 40μm and a length of 2~3mm.

[0027] The electrostatic repulsion of sodium tripolyphosphate / sodium hexametasulfate is used to reduce the amount of water added, the complexation effect of sodium citrate and other substances is used to regulate the construction time, and the melting and volatilization of polypropylene fibers forms an exhaust channel, which together ensures the construction performance and yield of the slag-blocking weir.

[0028] Furthermore, the shaping process of the recycled magnesium-aluminum-carbon is carried out using a ball mill for 15-20 minutes. This improves the particle bulk density and the flowability of the castable, increases the contact area between the particles and the matrix, and enhances the interfacial bonding strength.

[0029] Secondly, a method for preparing a recycled magnesium-aluminum-carbon-based high thermal shock resistant tundish slag-blocking weir includes the following steps: (1) Weigh all the raw materials according to the proportions; (2) Add 97 electrofused dicalcium magnesium sand with a particle size of 180 mesh, metallic silicon with a particle size of <240 mesh, zirconium-containing silica fume with a particle size of <2μm, as well as dispersant and retarder into a premixer and premix at a speed of 30~40r / min for 15-20 minutes. (3) Add raw magnesium olivine with a particle size of 15-8mm, recycled magnesium aluminum carbon with a particle size of 5-3mm and 3-1mm, 97 electrofused dicalcium magnesium sand with a particle size of 1-0mm, and explosion-proof fiber to the fine powder premixed in step (2), and mix and grind in a mixer at a speed of 20-30r / min for 2-3 minutes. (4) Add 3.9% to 4.1% of clean water by weight to the well-mixed material and continue stirring for 3 to 4 minutes until a wet castable with a flowability of 180 to 220 mm is formed; (5) Place the well-stirred material into the mold and vibrate it on a vibrating table with a vibration frequency of 50~60Hz to remove air bubbles until the surface of the material is covered with slurry and no more air bubbles are released. (6) After molding, place the preform and the mold together in a wet curing kiln with a temperature of 45~48℃ and a relative humidity of 50~60% for 12~14 hours, and then demold. (7) After demolding, the preform is placed in a dry curing kiln at 50~60℃ for 24~36 hours, and then sent to a baking kiln to be heated to 240~260℃ at a rate of 10~15℃ / h and baked for 24~36 hours to obtain the slag-blocking weir of the recycled magnesium aluminum carbon-based high thermal shock resistant intermediate ladle.

[0030] The beneficial effects of this invention are: (1) This invention achieves a breakthrough improvement in thermal shock stability by combining 30-38 parts of raw magnesium olivine with a particle size of 15-8 mm, 5-15 parts of recycled magnesium aluminum carbon with a particle size of 5-3 mm and 10-25 parts of recycled magnesium aluminum carbon with a particle size of 3-1 mm, and 2-6 parts of zirconium-containing silica fume with a particle size <2 μm. Among them, raw magnesium olivine, as the main aggregate, has a low coefficient of thermal expansion, which significantly reduces the overall thermal expansion rate of the material and reduces thermal stress under rapid cooling and heating conditions; the 5-10 parts of residual carbon contained in the recycled magnesium aluminum carbon have extremely high thermal conductivity, which can quickly transfer heat, making the temperature distribution inside the slag weir more uniform and effectively alleviating the concentration of thermal stress; the 1-3 parts of ZrO2 in the zirconium-containing silica fume, through monoclinic phase The reversible phase transformation of the tetragonal phase absorbs crack propagation energy, significantly improving the fracture toughness of the material. The synergistic effect of these three factors enables the slag weir of this invention to withstand more than 15 cycles of water-cooled thermal shock testing at 1100℃ without significant cracking, which is far superior to the 5-8 cycles of traditional magnesia castables.

[0031] (2) This invention significantly improves the slag erosion resistance of the material by using 10-20 parts of 1-0 mm particle size fused dicalcium magnesia sand and 10-20 parts of 180 mesh particle size fused 97 electrofused dicalcium magnesia sand, combined with recycled magnesium aluminum carbon and 1-5 parts of metallic silicon with a particle size <240 mesh. In the 97 electrofused dicalcium magnesia sand, CaO and SiO2 preferentially form the high-melting-point dicalcium disilicate (C2S) phase, avoiding the formation of the low-melting-point calcium magnesium olivine (CMS) phase, thus fundamentally improving the ability to resist SiO2 erosion in slag; the residual carbon in the recycled magnesium aluminum carbon has non-wetting properties, which can significantly reduce the penetration rate of steel slag into the material; the non-oxide reinforcing phases such as SiC and Si3N4 generated in situ at high temperature by metallic silicon fill the pores and grain boundaries, further improving the density and slag penetration resistance of the material. Under the combined effect, the slag erosion resistance of the slag weir of this invention is improved by more than 30% compared with the traditional scheme.

[0032] (3) This invention utilizes a large amount of recycled magnesia-alumina-carbon bricks from steel mills to prepare recycled magnesia-alumina-carbon raw materials, realizing the high-value utilization of solid waste resources. This not only reduces the consumption of high-quality raw materials such as virgin fused magnesia, but also reduces the environmental pollution caused by waste refractory materials. At the same time, through particle size distribution optimization and the use of efficient dispersants, low water addition and high density casting construction are achieved, reducing the overall cost by 15-20% compared with traditional solutions, resulting in significant economic and environmental benefits.

[0033] (4) This invention achieves excellent construction performance and high yield by precisely controlling the addition of dispersant, retarder and explosion-proof fiber. The dispersant controls the water addition at an extremely low level of 3.9 to 4.1 parts, which improves the density and strength of the material; the retarder precisely controls the construction time at 30 to 45 minutes, which fully meets the needs of on-site pouring construction; the explosion-proof fiber volatilizes during the baking process to form microporous channels, which quickly releases water vapor pressure and prevents the precast parts from bursting, so that the yield reaches more than 98%. Detailed Implementation

[0034] The specific embodiments of the present invention will be described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0035] In all embodiments of the present invention, the mass percentage of MgO in raw forsterite is ≥45%; Regenerated magnesium-aluminum-carbon bricks are obtained from recycled magnesium-aluminum-carbon bricks from scrap steel ladles at steel mills through crushing, slag removal, magnetic separation for iron removal, shaping, and screening processes. The total mass percentage of MgO and Al2O3 is ≥88%, and the carbon content is 5~10%. The MgO content in 97 fused dicalcium magnesia is ≥97% by mass, and the CaO / SiO2 molar ratio is controlled between 1.8 and 2.2. The mass percentage of Si in metallic silicon is ≥98%; The zirconium-containing silica fume contains ≥92% SiO2 by mass and 1~3% ZrO2; The explosion-proof fiber is made of polypropylene fiber with a diameter of 40μm and a length of 2~3mm.

[0036] The present invention includes 6 embodiments and 4 comparative examples, and the weight percentage of each component is shown in Table 1.

[0037] Table 1. Distribution ratio of the examples and comparative groups (by weight %)

[0038] All examples and comparative examples used the same preparation method, and the specific steps are as follows: (1) Weigh all raw materials according to the proportions in Table 1; (2) Add the fine powder components (180 mesh dicalcium magnesia / ordinary magnesia, metallic silicon / silicon carbide, zirconium-containing silica fume / ordinary silica fume) and dispersant and retarder into a premixer and premix for 18 minutes at a speed of 35 r / min; (3) Add the coarse particles (raw magnesium olivine, recycled magnesium aluminum carbon / spinel, 1~0mm dicalcium magnesium sand / ordinary magnesium sand) and explosion-proof fibers to the premixed fine powder and mix and grind in a mixer at a speed of 25r / min for 2.5 minutes. (4) Add clean water to the mixture and stir for 3.5 minutes, controlling the flowability at 200±20mm; (5) Pour the material into the mold, vibrate it on a 55Hz vibrating table for 6 minutes, and use a vibrating rod to help compact it; (6) After curing in a wet curing kiln at 46℃ and 55%RH for 13 hours, the mold is removed; (7) After demolding, it is placed in a dry curing kiln at 55℃ for 30 hours, and then sent to a baking kiln. The temperature is raised to 250℃ at a rate of 12℃ / h and kept warm for 30 hours to obtain the slag-blocking weir of the recycled magnesium-aluminum carbon-based high thermal shock resistant intermediate ladle.

[0039] Performance testing The performance test results of each embodiment and comparative example are shown in Table 2. Among them, the slag erosion resistance index was tested by the static crucible method, with the erosion depth of Example 1 as the benchmark (index = 1.0). The larger the index, the worse the slag erosion resistance. The thermal shock stability was tested by the 1100℃ water cooling method, and the number of cycles when obvious cracks appeared in the sample was recorded.

[0040] Table 2 Performance test results of the examples and comparative examples

[0041] As shown in Table 1, the total content of recycled magnesium-aluminum carbon in Example 4 was 25% (lower than 27% in Example 1), and the number of thermal shocks decreased to 16. Comparative Example 4, using carbon-free recycled magnesium-aluminum spinel, only experienced 9 thermal shocks. This is because the residual carbon in the recycled magnesium-aluminum carbon has extremely high thermal conductivity, enabling rapid heat transfer and resulting in a more uniform temperature distribution within the sample, reducing the thermal stress gradient. Simultaneously, the low coefficient of thermal expansion of the residual carbon reduces the overall thermal expansion rate of the material. From Example 1 to Example 6, the number of thermal shocks significantly increased with the increase in zirconium-containing silica fume content. This is because ZrO2 in the zirconium-containing silica fume undergoes monoclinic phase changes upon temperature variations. The reversible phase transformation of the tetragonal phase, accompanied by volume changes, absorbs crack propagation energy, forming a dual protection system of "thermal conductivity and stress reduction + toughening and crack resistance" with the residual carbon thermal conductivity mechanism of recycled magnesium aluminum carbon. Comparative Example 2, using ordinary silica fume (without ZrO2), only underwent 8 thermal shock cycles, fully demonstrating the synergistic effect of the two. Comparative Example 1, using ordinary fused magnesia instead of dicalcium magnesia, reduced the number of thermal shock cycles to 12. Ordinary fused magnesia has a slightly higher coefficient of thermal expansion than dicalcium magnesia, and it is prone to generating low-melting-point phases at high temperatures, leading to a decrease in material toughness, thus resulting in poor thermal shock stability.

[0042] Comparative Example 1, using ordinary fused magnesia, achieved a slag erosion resistance index as high as 1.45, 45% higher than Example 1. This is because CaO and SiO2 in ordinary fused magnesia readily form a low-melting-point CMS phase, which softens and melts at steel slag temperatures, leading to rapid slag penetration. In contrast, CaO and SiO2 in dicalcium magnesia preferentially form a high-melting-point C2S phase, creating a dense reaction layer that prevents further slag erosion. Comparative Example 4, using recycled magnesium aluminate spinel, achieved a slag erosion resistance index of 1.28, 28% higher than Example 1. This is because the residual carbon in recycled magnesium aluminate carbon exhibits non-wetting properties, significantly reducing the slag penetration rate. In contrast, carbon-free spinel is easily wetted by the slag, resulting in faster erosion. Comparative Example 3, using silicon carbide instead of metallic silicon, achieved a slag erosion resistance index of 1.12, 12% higher than Example 1. This is because the non-oxide phase generated in situ by metallic silicon bonds more tightly to the matrix, and the resulting dense layer can more effectively block the penetration of slag liquid; while the directly added silicon carbide has a weaker bond with the matrix interface and is more likely to become a channel for slag liquid penetration.

[0043] In Example 2, the zirconium-containing silica fume content was 4%, and the room temperature compressive strength reached 60.5 MPa, the highest among all examples. This is because the micro-filling effect of the zirconium-containing silica fume effectively fills the voids between particles, increasing the material density; simultaneously, at high temperatures, ZrO2 particles can pin grain boundaries, inhibiting grain growth and improving high-temperature strength. In Example 3, the water content was 4.1%, and the room temperature compressive strength decreased to 51.3 MPa. In Example 5, the metallic silicon content was 2%, and the high-temperature compressive strength decreased to 50.6 MPa. This is because the reduced metallic silicon content decreases the number of non-oxide reinforcing phases generated in situ at high temperatures, weakening the reinforcing effect on the matrix, thus reducing the high-temperature strength.

[0044] The flowability of all embodiments was controlled between 195 and 210 mm, with an operable time of 35 to 40 minutes, fully meeting the requirements for on-site construction. This is because the dispersant significantly reduces the friction between particles, improving flowability; the retarder slows down the rate of the MgO-SiO2-H2O bonding reaction through complexation, ensuring sufficient construction time. The yield of all embodiments was above 98%, while the yield of Comparative Example 1 was only 95.5%. This is because the explosion-proof fiber volatilizes at 150-200°C during baking, forming continuous microporous channels that rapidly release water vapor pressure, preventing the precast component from bursting; while in Comparative Example 1, the hydration reaction of ordinary magnesia is more intense, generating greater water vapor pressure and making it more prone to bursting.

[0045] The above-disclosed embodiments are merely a few specific examples of the present invention. However, the embodiments of the present invention are not limited thereto, and any variations that can be conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. A recycled magnesium-aluminum-carbon-based high thermal shock resistant tundish slag-blocking weir, characterized in that, By weight, it includes the following components: 30-38 parts of raw magnesium olivine with a grain size of 15-8 mm; 5-15 parts of recycled magnesium aluminum carbon with a particle size of 5-3 mm; 10-25 parts of recycled magnesium aluminum carbon with a particle size of 3-1 mm; 10-20 parts of 97 electrofused dicalcium magnesium sand with a particle size of 1-0 mm; 10-20 parts of fused dicalcium magnesium sand with a particle size of 180 mesh and 97 mm. 1-5 parts of metallic silicon with a particle size <240 mesh; 2-6 parts of zirconium silicate ash with a particle size <2μm; And 0.1 to 0.15 parts of dispersant, 0.01 to 0.02 parts of retarder and 0.06 to 0.08 parts of explosion-proof fiber, accounting for 0.1 to 0.15 parts of the total weight of the above raw materials.

2. The recycled magnesium-aluminum-carbon-based high thermal shock resistant tundish slag-blocking weir according to claim 1, characterized in that, The raw magnesium olivine contains ≥45% MgO and ≤42% SiO2 by mass.

3. The recycled magnesium-aluminum-carbon-based high thermal shock resistant tundish slag-blocking weir according to claim 1, characterized in that, The recycled magnesium-aluminum-carbon alloy is obtained from waste steel ladle molten pool bricks or ladle bottom bricks recovered from steel mills through crushing, slag removal, magnetic separation for iron removal, shaping, and screening processes. The alloy contains ≥88% MgO and Al2O3 by mass, 5-10% C, and has a bulk density ≥2.8 g / cm³. 3 .

4. The recycled magnesium-aluminum-carbon-based high thermal shock resistant tundish slag-blocking weir according to claim 1, characterized in that, The 97% fused dicalcium magnesia contains ≥97% MgO by mass, 1.5-2.5% CaO, and the CaO / SiO2 molar ratio is controlled between 1.8 and 2.2, with a bulk density ≥3.25 g / cm³. 3 .

5. The recycled magnesium-aluminum-carbon-based high thermal shock resistant tundish slag-blocking weir according to claim 1, characterized in that, The silicon metal contains ≥98% Si by mass and ≤0.5% Fe2O3 by mass.

6. The recycled magnesium-aluminum-carbon-based high thermal shock resistant tundish slag-blocking weir according to claim 1, characterized in that, The zirconium-containing silica fume contains ≥92% SiO2 by mass, 1-3% ZrO2, ≤2% loss on ignition, and ≥15000 m² / g specific surface area. 2 / kg.

7. The recycled magnesium-aluminum-carbon-based high thermal shock resistant tundish slag-blocking weir according to claim 1, characterized in that, The dispersant is at least one of sodium tripolyphosphate and sodium hexametasulfate.

8. The recycled magnesium-aluminum-carbon-based high thermal shock resistant tundish slag-blocking weir according to claim 1, characterized in that, The retarder is at least one of sodium citrate, sodium gluconate, and sodium tartrate; the explosion-proof fiber is polypropylene fiber with a diameter of 40 μm and a length of 2-3 mm.

9. The recycled magnesium-aluminum-carbon-based high thermal shock resistant tundish slag-blocking weir according to claim 1, characterized in that, The shaping process of the recycled magnesium-aluminum-carbon is carried out using a ball mill, with a milling time of 15-20 minutes.

10. A method for preparing a recycled magnesium-aluminum-carbon-based high thermal shock resistant tundish slag-blocking weir as described in any one of claims 1-9, characterized in that, Includes the following steps: (1) Weigh all the raw materials according to the proportions; (2) Add 97 electrofused dicalcium magnesium sand with a particle size of 180 mesh, metallic silicon with a particle size of <240 mesh, zirconium-containing silica fume with a particle size of <2μm, as well as dispersant and retarder into a premixer and premix at a speed of 30~40r / min for 15-20 minutes. (3) Add raw magnesium olivine with a particle size of 15-8mm, recycled magnesium aluminum carbon with a particle size of 5-3mm and 3-1mm, 97 electrofused dicalcium magnesium sand with a particle size of 1-0mm, and explosion-proof fiber to the fine powder premixed in step (2), and mix and grind in a mixer at a speed of 20-30r / min for 2-3 minutes. (4) Add 3.9% to 4.1% of clean water by weight to the well-mixed material and continue stirring for 3 to 4 minutes until a wet castable with a flowability of 180 to 220 mm is formed; (5) Place the well-stirred material into the mold and vibrate it on a vibrating table with a vibration frequency of 50~60Hz to remove air bubbles until the surface of the material is covered with slurry and no more air bubbles are released. (6) After molding, place the preform and the mold together in a wet curing kiln with a temperature of 45~48℃ and a relative humidity of 50~60% for 12~14 hours, and then demold. (7) After demolding, the preform is placed in a dry curing kiln at 50~60℃ for 24~36 hours, and then sent to a baking kiln to be heated to 240~260℃ at a rate of 10~15℃ / h and baked for 24~36 hours to obtain the slag-blocking weir of the recycled magnesium aluminum carbon-based high thermal shock resistant intermediate ladle.

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