Anti-erosion tundish dry material

Abstract

This invention discloses an anti-erosion tundish dry material, relating to the field of tundish refractory materials technology. The mass percentage of each raw material component in the tundish dry material is as follows: 28-32% 3-1mm fused magnesia, 22-30% 1-0mm fused magnesia, 20-28% 200-mesh fused magnesia, 3-4.5% phenolic resin, 1-1.4% palygorskite powder, 0.2-0.3% SiO2 aerogel powder, and the balance being 5-3mm fused magnesia. This invention cleverly utilizes the special layered structure of palygorskite powder and the ultra-low thermal conductivity of SiO2 aerogel powder. The synergistic effect of the two enables the tundish dry material of this invention to successfully solve the problems of insufficient strength and poor heat insulation performance while maintaining the original good refractory properties, significantly improving the efficiency and economy of continuous casting process.

Description

Technical Field

[0001] This invention belongs to the technical field of tundish refractory materials, and specifically relates to an erosion-resistant dry tundish material. Background Technology

[0002] In the modern steel industry, the tundish, as a crucial link connecting the ladle and the crystallizer in the continuous casting process, directly impacts the purity of the molten steel, continuous casting efficiency, and production costs through the selection of its working lining material. Dry lining materials for tundishes, as a highly efficient and environmentally friendly working lining material, are favored due to their convenient construction, rapid curing, and excellent corrosion resistance. In particular, dry lining systems using fused magnesia as the main raw material and phenolic resin as the binder are widely used in the industry due to their superior refractory properties and suitable chemical stability.

[0003] However, although fused magnesia-phenolic resin type tundish dry linings meet the basic requirements of high-temperature operating environments to a certain extent, several technical problems still need to be solved in actual use. Specifically: 1. Insufficient strength: In specific temperature ranges, especially around 1100℃ and 1530℃, these dry linings exhibit a significant decrease in strength. This insufficient strength weakens the material's resistance to mechanical stress when subjected to the intense erosion of molten steel and slag, making it prone to cracking, deformation, and even localized spalling, severely affecting the service life of the tundish and the stability of the continuous casting process; 2. Increased heat loss and erosion: Due to the limited insulation performance of existing dry linings, unnecessary heat loss occurs during transmission, increasing energy consumption and potentially leading to uneven steel temperature, affecting continuous casting quality. Simultaneously, the erosive effect of molten steel and slag on dry linings is more significant at high temperatures, especially in the lower strength temperature range, where the material's erosion barrier is weak, further accelerating the damage process of the working lining.

[0004] Given the aforementioned technical challenges, although some targeted improvement measures have been implemented, such as adjusting the raw material ratio, optimizing the type and amount of binder, and adding specific additives, existing solutions often fail to simultaneously meet the two core requirements of improving strength at medium and high temperatures and optimizing thermal insulation performance. Furthermore, improving one aspect of performance may adversely affect other aspects. Summary of the Invention

[0005] To address the problems of severe erosion and spalling and poor thermal insulation performance caused by insufficient strength in existing fused magnesia-phenol resin dry-filled mortar during use, this invention provides an erosion-resistant tundish dry-filled mortar that improves the medium and high temperature strength and thermal insulation performance of the dry-filled mortar by adding attapulgite powder and SiO2 aerogel powder.

[0006] The solution adopted by this invention to solve its technical problem is: an anti-erosion tundish dry material, wherein the mass percentage of each raw material component in the tundish dry material is as follows: 28-32% of 3-1mm fused magnesia, 22-30% of 1-0mm fused magnesia, 20-28% of 200-mesh fused magnesia, 3-4.5% of phenolic resin, 1-1.4% of palygorskite powder, 0.2-0.3% of SiO2 aerogel powder, and the balance being 5-3mm fused magnesia.

[0007] Furthermore, the intermediate dry material contains 30% fused magnesia of 3-1 mm, 25% fused magnesia of 1-0 mm, 24% fused magnesia of 200 mesh, 3.5% phenolic resin, 1.2% palygorskite powder, 0.3% SiO2 aerogel powder, and the balance is fused magnesia of 5-3 mm.

[0008] Furthermore, the MgO content in the fused magnesia is ≥91%.

[0009] Furthermore, the raphe powder has a particle size of 325 mesh and a purity of 98%.

[0010] Furthermore, the specific surface area of ​​the SiO2 aerogel powder is 700–750 m². 2 / g, with a bulk density of 40–45 kg / m³ 3 It has a porosity of 93.5%, a thermal conductivity of 0.012–0.014 W / (m·K), an average particle size of 25 μm, and a hydrophobic surface.

[0011] Furthermore, when the intermediate dry material is vibrated during molding, the working layer membrane vibrates for 120–150 seconds.

[0012] Compared with the prior art, the beneficial effects of the present invention are:

[0013] 1. This invention utilizes attapulgite powder to enhance the medium- and high-temperature strength and erosion resistance of the dry tundish material. As an innovative additive, attapulgite powder, with its unique layered silicate mineral structure, possesses natural interlayer water molecules and exchangeable cations, maintaining structural stability at high temperatures while providing excellent ion exchange and expansion properties. After adding attapulgite powder to the dry tundish material, its layered structure can form physical and chemical interactions with fused magnesia particles and other components at high temperatures. Specifically: First, the flaky particles of attapulgite powder can form a cross-network within the dry tundish material, enhancing the mechanical interlocking between particles and improving the material's shear and impact resistance. Second, the surface-active groups of attapulgite powder chemically bond with phenolic resin or other mineral components, enhancing interfacial bonding and improving the material's overall integrity. Finally, the micro-expansion generated by attapulgite powder during heating helps fill micro-cracks and voids, delaying crack propagation at high temperatures and improving the crack resistance and toughness of the dry tundish material. Through the above-mentioned effects, retardant powder significantly improves the compressive strength and erosion resistance of dry aggregates at medium and high temperatures, and can effectively prevent the spalling of dry aggregates caused by the scouring of molten steel and slag.

[0014] 2. This invention uses SiO2 aerogel powder to improve the thermal insulation performance of dry insulation materials. SiO2 aerogel powder has extremely low bulk density and a nanoscale porous structure, giving it an ultra-low thermal conductivity, making it an ideal high-temperature insulation material. The mechanism by which the addition of SiO2 aerogel powder modifies and improves the thermal insulation performance of dry insulation materials in this invention is specifically reflected in the following aspects: First, the nanoporous structure of the aerogel powder greatly increases the tortuosity of the heat transfer path, significantly increasing the thermal resistance when heat flows through the material, effectively reducing the heat conduction rate; second, the nanopores and particles inside the aerogel powder have a strong scattering and reflection effect on thermal radiation, reducing the possibility of thermal radiation directly penetrating the material, which can further reduce heat loss; finally, the pores of the aerogel powder can adsorb and store gas, forming a highly efficient thermal insulation layer, preventing convective heat transfer, and effectively improving the thermal insulation effect. The introduction of SiO2 aerogel powder in this invention significantly improves the heat preservation performance of dry materials, effectively suppresses the drop in molten steel temperature, ensures the temperature stability of the continuous casting process, and also reduces the thermal stress caused by temperature fluctuations, indirectly enhancing the overall strength of dry materials.

[0015] This invention ingeniously utilizes the special layered structure of attapulgite powder and the ultra-low thermal conductivity of SiO2 aerogel powder. Through scientific formulation design and process optimization, it achieves a performance upgrade of existing fused magnesia-phenolic resin type tundish dry material. The synergistic effect of the two enables the tundish dry material of this invention to successfully solve the problems of insufficient strength and poor heat preservation performance while maintaining the original good refractory properties, significantly improving the efficiency and economy of continuous casting process. Detailed Implementation

[0016] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0017] This invention provides a technical solution for erosion-resistant dry-mix tundish material:

[0018] An anti-erosion tundish dry material, wherein the mass percentage of each raw material component in the tundish dry material is as follows: 28-32% 3-1mm fused magnesia, 22-30% 1-0mm fused magnesia, 20-28% 200-mesh fused magnesia, 3-4.5% phenolic resin, 1-1.4% palladium powder, 0.2-0.3% SiO2 aerogel powder, and the balance being 5-3mm fused magnesia.

[0019] This invention employs rapasite powder as an innovative additive, utilizing its unique layered silicate mineral structure to play multiple roles in the dry feedstock of the tundish: Firstly, the natural interlayer water molecules and exchangeable cations in rapasite powder maintain structural stability at high temperatures while providing excellent ion exchange and expansion properties; secondly, its layered structure can form physical and chemical interactions with other components in the dry feedstock at high temperatures, including physical interweaving to form a cross-network that enhances the mechanical interlocking between particles, chemical bonding to enhance interfacial bonding, and thermal expansion to fill micro-cracks and voids and delay crack propagation. Through these multiple effects, rapasite powder significantly improves the compressive strength and erosion resistance of the dry feedstock at medium and high temperatures, effectively preventing the spalling of the dry feedstock caused by the scouring of molten steel and slag.

[0020] This invention significantly enhances the thermal insulation performance of dry casting materials by introducing SiO2 aerogel powder. Utilizing its ultra-low bulk density and nanoscale porous structure resulting in ultra-low thermal conductivity, SiO2 aerogel powder significantly increases the tortuosity of the heat transfer path, thereby increasing thermal resistance and effectively slowing down heat conduction. Simultaneously, the scattering and reflection of thermal radiation by its internal nanopores and particles reduces heat radiation loss. Furthermore, the adsorption and storage of gases by the pores constructs a highly efficient thermal insulation layer, blocking convective heat transfer. These mechanisms work together to not only greatly improve the thermal insulation effect of dry casting materials, effectively curbing the drop in molten steel temperature and ensuring temperature stability during continuous casting, but also indirectly enhance the overall structural strength of the dry casting materials by reducing thermal stress caused by temperature fluctuations.

[0021] In a preferred embodiment of the present invention, the tundish dry material contains 30% fused magnesia of 3-1 mm, 25% fused magnesia of 1-0 mm, 24% fused magnesia of 200 mesh, 3.5% phenolic resin, 1.2% palygorskite powder, 0.3% SiO2 aerogel powder, and the balance being fused magnesia of 5-3 mm.

[0022] This invention uses 5-3mm fused magnesia. The larger-sized fused magnesia particles primarily act as a skeletal support in the dry charge of the tundish, enhancing the overall strength and erosion resistance of the material. This helps reduce shrinkage caused by temperature changes during sintering or use, maintaining material stability. Appropriate particle spacing also improves permeability, facilitating the flow of molten steel and uniform temperature distribution within the tundish. Using 3-1mm fused magnesia, together with the 5-3mm particles, forms a stable skeletal system. Through reasonable particle size matching, the bulk density and uniformity of the dry charge can be improved, porosity reduced, thereby enhancing the erosion resistance and erosion resistance of the dry charge. Using 1-0mm fused magnesia... Fused magnesia, with its smaller particle size, can fill the gaps between larger particles, improving the density and compactness of the dry material. By refining the particle size distribution, it can further improve the thermal shock resistance and erosion resistance of the dry material. At the same time, the 1-0 mm small particles have a larger specific surface area, which is beneficial to the diffusion and reaction of materials during sintering, accelerating the sintering process. Using 200 mesh fused magnesia, the ultrafine fused magnesia particles can significantly refine the microstructure of the material, improving the uniformity and compactness of the dry material. The refined structure helps to improve the strength, hardness, and wear resistance of the dry material, while enhancing its resistance to penetration and erosion, and can further form a denser and more uniform sintered body.

[0023] In a preferred embodiment of the present invention, the fused magnesia contains ≥91% MgO.

[0024] This invention uses high-purity fused magnesia as raw material. High-purity fused magnesia has large crystal grains and a dense structure during the melting process. The dry tundish material prepared from it also has good structural stability. Fused magnesia with high MgO content has strong resistance to slag erosion. The dry tundish material prepared from it also has good refractoriness and compressive strength. It can maintain stable performance in high-temperature environments and effectively extend the service life of the tundish.

[0025] In a preferred embodiment of the present invention, the raphe powder has a particle size of 325 mesh and a purity of 98%.

[0026] The invention utilizes high-purity and fine-grained patellar powder, which helps reduce the thermal conductivity of dry billets, thereby improving their heat retention performance. This helps reduce temperature loss of molten steel in the tundish and improves continuous casting production efficiency. During sintering, the fine patellar powder particles can react with other components more quickly, promoting mass transfer and densification during sintering. This helps form a more uniform and dense sintered body, improving the overall performance of dry billets in the tundish.

[0027] In a preferred embodiment of the present invention, the SiO2 aerogel powder has a specific surface area of ​​700–750 m². 2 / g, with a bulk density of 40–45 kg / m³ 3 It has a porosity of 93.5%, a thermal conductivity of 0.012–0.014 W / (m·K), an average particle size of 25 μm, and a hydrophobic surface.

[0028] This invention utilizes SiO2 aerogel powder with a high specific surface area, which can more effectively adsorb and fix other components in the tundish dry material, thereby improving the overall uniformity and stability of the material. The low bulk density of SiO2 aerogel powder significantly reduces the overall weight of the material during the preparation of the tundish dry material. While maintaining the same volume, the low bulk density material can fill more space, thus improving the filling rate and density of the tundish dry material. The high porosity of SiO2 aerogel powder results in extremely low thermal conductivity, effectively reducing heat transfer, improving the thermal insulation performance of the tundish dry material, and reducing heat loss. Meanwhile, an appropriate pore structure helps improve the material's permeability, reduce the pressure difference caused by gas accumulation, and improve the material's stability and service life; a low thermal conductivity can significantly reduce the rate of heat transfer in the material, improve the insulation effect of the tundish dry material, protect the temperature of molten steel, reduce energy consumption, and effectively improve the thermal insulation performance of the dry material; a smaller particle size helps fill the tiny voids in the material, improving the material's density and strength; after hydrophobic modification of SiO2 aerogel powder, the hydrophobic surface can reduce heat transfer through the interface, thereby reducing the thermal bridging effect and helping to improve the thermal insulation performance of the tundish dry material.

[0029] In a preferred embodiment of the present invention, when the intermediate dry material is vibrated during vibration molding, the vibration time of the working layer membrane is 120-150s.

[0030] The vibration time of the working layer membrane in this invention is 120-150 seconds, which helps to reduce the gaps between particles, increase the density of the material, thereby enhancing the overall strength and corrosion resistance of the working layer, improving the material structure, increasing construction efficiency and meeting process requirements.

[0031] Specific implementation examples:

[0032] The following provides a specific embodiment of the anti-erosion tundish dry material of the present invention.

[0033] Example 1:

[0034] This embodiment provides an anti-erosion tundish dry material, wherein the percentage of each component in the tundish dry material by mass percentage is as follows: 30% 3-1mm fused magnesia, 25% 1-0mm fused magnesia, 24% 200-mesh fused magnesia, 3.5% phenolic resin, 1.2% palladium powder, 0.3% SiO2 aerogel powder, and the balance being 5-3mm fused magnesia.

[0035] Example 2:

[0036] This embodiment provides an anti-erosion tundish dry material, wherein the percentage of each component in the tundish dry material by mass percentage is as follows: 29% 3-1mm fused magnesia, 28% 1-0mm fused magnesia, 23% 200-mesh fused magnesia, 3.9% phenolic resin, 1.3% palladium powder, 0.2% SiO2 aerogel powder, and the balance being 5-3mm fused magnesia.

[0037] Example 3:

[0038] This embodiment provides an anti-erosion tundish dry material, wherein the percentage of each component in the tundish dry material by mass percentage is as follows: 28% 3-1mm fused magnesia, 22% 1-0mm fused magnesia, 28% 200-mesh fused magnesia, 4.5% phenolic resin, 1.4% palladium powder, 0.2% SiO2 aerogel powder, and the balance being 5-3mm fused magnesia.

[0039] Example 4:

[0040] This embodiment provides an anti-erosion tundish dry material, wherein the percentage of each component in the tundish dry material by mass percentage is as follows: 31% 3-1mm fused magnesia, 26.5% 1-0mm fused magnesia, 20% 200-mesh fused magnesia, 4.2% phenolic resin, 1% palladium powder, 0.3% SiO2 aerogel powder, and the balance being 5-3mm fused magnesia.

[0041] Example 5:

[0042] This embodiment provides an anti-erosion tundish dry material, wherein the percentage of each component in the tundish dry material by mass percentage is as follows: 32% 3-1mm fused magnesia, 30% 1-0mm fused magnesia, 22% 200-mesh fused magnesia, 3% phenolic resin, 1.1% palladium powder, 0.2% SiO2 aerogel powder, and the balance being 5-3mm fused magnesia.

[0043] Example 6:

[0044] This embodiment provides an anti-erosion tundish dry material, wherein the percentage of each component in the tundish dry material by mass percentage is as follows: 30% 3-1mm fused magnesia, 27% 1-0mm fused magnesia, 25% 200-mesh fused magnesia, 4% phenolic resin, 1.2% palladium powder, 0.3% SiO2 aerogel powder, and the balance being 5-3mm fused magnesia.

[0045] Comparative Example 1:

[0046] This comparative example provides an anti-erosion tundish dry material. The percentage of each component in the tundish dry material by mass percentage is as follows: 29% 3-1mm fused magnesia, 28% 1-0mm fused magnesia, 23% 200-mesh fused magnesia, 3.9% phenolic resin, 0.2% SiO2 aerogel powder, and the balance being 5-3mm fused magnesia. This comparative example does not contain attapulgite powder.

[0047] Comparative Example 2:

[0048] This comparative example provides an anti-erosion tundish dry material. The percentage of each component in the tundish dry material by mass percentage is as follows: 28% 3-1mm fused magnesia, 22% 1-0mm fused magnesia, 28% 200-mesh fused magnesia, 4.5% phenolic resin, 1.4% palladium powder, and the balance being 5-3mm fused magnesia. This comparative example does not contain SiO2 aerogel powder.

[0049] Comparative Example 3:

[0050] This comparative example provides an anti-erosion tundish dry material. The percentage of each component in the tundish dry material by mass percentage is as follows: 31% 3-1mm fused magnesia, 26.5% 1-0mm fused magnesia, 20% 200-mesh fused magnesia, 2% phenolic resin, 1% palladium powder, 0.3% SiO2 aerogel powder, and the balance being 5-3mm fused magnesia. In this comparative example, the phenolic resin content is relatively low, only 2%.

[0051] Comparative Example 4:

[0052] This comparative example provides an anti-erosion tundish dry material. The percentage of each component in the tundish dry material by mass percentage is as follows: 32% fused magnesia of 3-1mm, 30% fused magnesia of 1-0mm, 32% fused magnesia of 200 mesh, 3% phenolic resin, 1.1% palladium powder, 0.2% SiO2 aerogel powder, and the balance being fused magnesia of 5-3mm. In this comparative example, the content of fused magnesia of 200 mesh is relatively high, reaching 32%.

[0053] This invention uses a dry-type erosion-resistant tundish material from Examples 1-6 and Comparative Examples 1-4. Sample preparation was performed according to GB / T4513.5-2017 "Unshaped Refractories - Part 5: Sample Preparation and Pretreatment". Flexural strength and compressive strength were tested according to the methods in GB / T 4513.6-2017 "Unshaped Refractories - Part 6: Determination of Physical Properties". The cladding temperature was measured using an infrared thermometer. All tests in Examples 1-6 and Comparative Examples 1-4 were conducted using the same new permanent layer "rectangular" tundish. The location and time of the cladding temperature tests were identical. The erosion rate was calculated from the remaining thickness of the dry material after measurement. The test results are shown in Table 1.

[0054] Table 1. Test results of Examples 1-6 and Comparative Examples 1-4

[0055]

[0056] Comparative Example 1 is based on Example 2, except that the addition of attapulgite powder is removed and 5-3 mm of fused magnesia is added accordingly. As can be seen from Table 1, compared with Example 2, the flexural strength and compressive strength of Comparative Example 1 are significantly reduced, and the erosion rate is increased to 2.14 mm / h, which is significantly lower than the test results of Example 2.

[0057] Comparative Example 2 is based on Example 3, except that the addition of SiO2 aerogel powder is removed and 5-3 mm of fused magnesia is added accordingly. As can be seen from Table 1, compared with Example 3, Comparative Example 2 shows a significant increase in the cladding temperature of the slag line and bottom of the impact zone, and the slag line and bottom of the buffer zone. The cladding temperature increase ranges from 17 to 20°C, and the erosion rate also increases slightly to 1.51 mm / h, which is significantly lower than the test results of Example 3.

[0058] Comparative Example 3 is based on Example 4, but with a reduction in the addition of phenolic resin and a corresponding increase of 5-3 mm of fused magnesia. As can be seen from Table 1, compared with Example 4, the flexural strength and compressive strength of Comparative Example 3 are significantly reduced, and the erosion rate is increased to 1.78 mm / h, which is significantly lower than the test results of Example 4.

[0059] Comparative Example 4 is based on Example 5, with an increase of 200-mesh fused magnesia and a corresponding reduction of 5-3 mm of fused magnesia. As can be seen from Table 1, compared with Example 5, the shell temperature of the slag line and bottom of the impact zone and the slag line and bottom of the buffer zone in Comparative Example 4 is slightly higher, and the erosion rate is also increased to 1.66 mm / h, which is significantly lower than the test results of Example 5.

[0060] In summary, adding attapulgite powder can effectively improve the flexural strength and compressive strength of dry tundish material, while adding SiO2 aerogel powder can significantly enhance the thermal insulation performance of dry tundish material. At the same time, each raw material needs to be scientifically formulated and work together to effectively improve flexural strength, compressive strength and thermal insulation performance while ensuring the original refractoriness.

[0061] The above description is only a preferred embodiment of the present invention and does not limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A dry-type tundish material with erosion resistance, characterized in that: The mass percentage of each raw material component in the intermediate dry material is as follows: 28-32% fused magnesia of 3-1mm, 22-30% fused magnesia of 1-0mm, 20-28% fused magnesia of 200 mesh, 3-4.5% phenolic resin, 1-1.4% palladium powder, 0.2-0.3% SiO2 aerogel powder, and the balance being fused magnesia of 5-3mm.

2. The erosion-resistant tundish dry material according to claim 1, characterized in that: The intermediate dry material consists of 30% fused magnesia of 3-1 mm, 25% fused magnesia of 1-0 mm, 24% fused magnesia of 200 mesh, 3.5% phenolic resin, 1.2% palygorskite powder, 0.3% SiO2 aerogel powder, and the remainder is fused magnesia of 5-3 mm.

3. The erosion-resistant tundish dry material according to claim 1, characterized in that: The fused magnesia contains ≥91% MgO.

4. The erosion-resistant tundish dry material according to claim 1, characterized in that: The raptor powder has a particle size of 325 mesh and a purity of 98%.

5. The erosion-resistant tundish dry material according to claim 1, characterized in that: The SiO2 aerogel powder has a specific surface area of ​​700–750 m². 2 / g, with a bulk density of 40–45 kg / m³ 3 It has a porosity of 93.5%, a thermal conductivity of 0.012–0.014 W / (m·K), an average particle size of 25 μm, and a hydrophobic surface.

6. The erosion-resistant tundish dry material according to claim 1, characterized in that: When the intermediate dry material is vibrated during molding, the working layer membrane vibrates for 120-150 seconds.

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