A tundish dam wall castable for low carbon steel and a preparation method thereof

Abstract

The application provides a tundish slag retaining wall castable suitable for low-carbon steel and a preparation method thereof. The tundish slag retaining wall castable is prepared from the following components in parts by mass: white corundum 60-70 parts, MgO.Al2O3 spinel and solid solution phase of magnesia-alumina spinel 27-35 parts, water reducing agent 0.1-0.3 parts, anti-explosion agent 1-1.5 parts, and hardening agent 3-4 parts. The tundish slag retaining wall castable has good slag corrosion resistance and small linear change rate, and has good strength, thereby meeting the production requirements of clean steel such as low-carbon and low-silicon steel.

Description

Technical Field

[0001] This invention belongs to the field of tundish castable technology, specifically relating to a tundish slag retaining wall castable suitable for low carbon steel and its preparation method. Background Technology

[0002] The tundish is a crucial step in the continuous casting process of steelmaking, and in recent years, an increasing number of scholars have conducted in-depth and extensive research on tundishes used in continuous casting. To fully utilize the tundish's volume and promote inclusion removal, slag-blocking walls are installed inside the tundish to eliminate dead zones, improve the flow direction of molten steel, and allow the molten steel to move along the steel-slag interface, shortening the distance that inclusions need to float. Simultaneously, the slag-blocking walls confine the molten steel flowing from the ladle to a localized area (impact zone), preventing slag inclusions and slag entrapment caused by turbulent diffusion, thus purifying the molten steel to a certain extent.

[0003] The slag retaining wall is fixed to the working lining at both ends, and both sides of the wall are in direct contact with the molten steel, subjecting it to prolonged immersion, scouring, and compression. Currently, most slag retaining wall materials used by refractory manufacturers are high-alumina, alumina-magnesia, magnesia-carbon, and alumina-magnesia-carbon, suitable for most steel grades. However, the requirements for steel purity are increasingly stringent, especially for clean steels such as low-carbon and low-silicon steels. Existing tundish slag retaining walls, due to their materials having a certain degree of wettability with molten slag and steel, have poor resistance to slag erosion, releasing alumina inclusions and adding carbon to the molten steel, thus contaminating it. Furthermore, they exhibit severe linear expansion and cannot meet the requirements for clean steels such as low-carbon and low-silicon steels. In addition, the strength performance of existing tundish slag retaining walls needs improvement. Chinese patent document CN106431438B discloses a castable refractory for slag retaining walls and its preparation method. The castable refractory comprises 45-75% fused white corundum and / or tabular corundum, 5-15% fused dense corundum, 1-10% fused magnesia powder, 1-5% spinel particles, 2-10% spinel micro powder, 2-10% activated alumina powder, 3-6% calcium aluminate cement, and 0.2-2% silica powder, water-reducing agent, and explosion-proof organic fiber. This castable refractory exhibits high room temperature strength and high-temperature hot strength, but its resistance to slag erosion is still relatively poor, and its strength performance needs further improvement. Summary of the Invention

[0004] The technical problem solved by this invention is to provide a tundish slag retaining wall castable suitable for low carbon steel and its preparation method. The tundish slag retaining wall castable has good slag erosion resistance and a small linear shrinkage rate. At the same time, the castable has good strength, which meets the production requirements of clean steel such as low carbon and low silicon steel.

[0005] To address the aforementioned problems, one aspect of the present invention provides a castable refractory for tundish retaining walls made of low-carbon steel, wherein the raw materials for its preparation, calculated by mass parts, comprise the following components:

[0006] 60-70 parts white fused alumina, 27-35 parts solid solution phase of MgO·Al2O3 spinel and magnesium allon, 0.1-0.3 parts water-reducing agent, 1-1.5 parts explosion-proof agent, and 3-4 parts hardening accelerator.

[0007] Preferably, the raw materials for preparing the solid solution phase of MgO·Al2O3 spinel and magnesium allon include MgO·Al2O3 spinel, α-Al2O3 micro powder, aluminum powder and magnesia; the mass ratio of MgO·Al2O3 spinel, α-Al2O3 micro powder, aluminum powder and magnesia is (6-10):(14-18):(4-8):(3-5).

[0008] Preferably, the grain size of MgO·Al2O3 spinel is >0 μm and ≤44 μm, and the Al2O3 content in MgO·Al2O3 spinel is ≥70 wt%, and the MgO content is ≥20 wt%.

[0009] The particle size of α-Al₂O₃ micro powder is >0 μm and ≤44 μm, and the Al₂O₃ content in the α-Al₂O₃ micro powder is ≥99 wt%.

[0010] The bulk density of aluminum powder is ≥1.03 g / cm³. 3 The aluminum powder contains ≥99 wt% Al.

[0011] The particle size of magnesia is >0μm and ≤74μm, and the MgO content in magnesia is ≥97.2wt%.

[0012] Preferably, the white fused alumina comprises white fused alumina particles with a particle size of >3mm and ≤5mm, white fused alumina particles with a particle size of >1mm and ≤3mm, and white fused alumina fine powder with a particle size of >0mm and ≤1mm; the mass ratio of white fused alumina particles with a particle size of >3mm and ≤5mm, white fused alumina particles with a particle size of >1mm and ≤3mm, and white fused alumina fine powder with a particle size of >0mm and ≤1mm is 3:5-6:4-5.

[0013] The Al2O3 content in white fused alumina is ≥99wt%.

[0014] Preferably, the water-reducing agent is a mixture of polycarboxylic acid and sodium hexametaphosphate; the mass ratio of polycarboxylic acid to sodium hexametaphosphate is 4:1; and the pH of the water-reducing agent is 7-8.5.

[0015] Preferably, the explosion-proof agent is a mixture of steel fibers and polypropylene fibers; the mass ratio of steel fibers to polypropylene fibers is 2:1.

[0016] The steel fiber is a nickel-chromium alloy heat-resistant steel with a refractoriness of 1450℃ and a specification of 0.3×1×25 / 30mm.

[0017] The polypropylene fiber has the following specifications: length 2.5-3.5 mm, diameter 20-40 μm, and melting point 173℃-178℃.

[0018] Preferably, the hardening accelerator is a mixture of 70g cement and silica fume, with a mass ratio of 70g cement to silica fume of 3:2.

[0019] The 70G cement contains 28wt%-30wt% CaO and 68wt%-70wt% Al2O3; the silica powder contains ≥92wt% SiO2, has a particle size >0μm and ≤0.620μm, and a specific surface area of ​​10-15m². 2 / g.

[0020] Another aspect of the present invention provides a method for preparing the above-mentioned tundish slag retaining wall castable suitable for low carbon steel, comprising the following steps:

[0021] White corundum, MgO·Al2O3 spinel and magnesium allon solid solution phase, water reducing agent, explosion retardant and hardening accelerator are mixed according to the selected mass proportions, and water is added to obtain a mixture; the mixture is placed in a mold, vibrated to form, then cured and baked to obtain the tundish slag retaining wall castable suitable for low carbon steel.

[0022] Preferably, the method for preparing the solid solution phase of MgO·Al2O3 spinel and magnesium allon includes:

[0023] MgO·Al2O3 spinel, α-Al2O3 micro powder, aluminum powder, and magnesia were mixed and kept at 1600℃-1700℃ for 1-5 hours in a nitrogen atmosphere to obtain a solid solution phase of MgO·Al2O3 spinel and magnesium aron.

[0024] Preferably, the curing temperature is 60-80℃ and the time is 16-18 hours;

[0025] The baking temperature is 240-260℃, and the time is 6-8 hours.

[0026] Compared with the prior art, the present invention has the following advantages:

[0027] The present invention relates to a tundish slag retaining wall castable for low carbon steel, which incorporates a solid solution phase of MgO·Al2O3 spinel and magnesium allon, wherein magnesium allon is a material formed by magnesium oxide being dissolved in the allon phase. On the one hand, MgO·Al2O3 spinel itself has excellent anti-permeation properties against slag, while magnesium allon also has good non-wetting properties against steel slag. Furthermore, after magnesium allon enters the glassy phase of the slag, it increases the viscosity of the glassy phase and reduces the permeability of the slag. At the same time, when magnesium allon reacts with FeO in the slag, gas is generated. Some of the gas exists in the pores of the sample, preventing the slag from further penetrating into the castable, thus significantly improving the anti-permeation properties of the castable. Therefore, adding the solid solution phase of MgO·Al2O3 spinel and magnesium allon can improve the slag erosion resistance of the castable, effectively improve the flotation and removal of inclusions in the steel, and reduce the source of foreign inclusions. On the other hand, since magnesium allon and magnesium aluminum spinel have similar crystal structures, they can be mutually dissolved. After solid solution, they are conducive to the densification and composite of the castable, resulting in a smaller linear change rate of the castable and improving the strength properties of the castable. Detailed Implementation

[0028] 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. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0029] One aspect of this invention provides a tundish slag retaining wall castable suitable for low-carbon steel, the raw materials for which are prepared by weight include the following components:

[0030] 60-70 parts white fused alumina, 27-35 parts solid solution phase of MgO·Al2O3 spinel and magnesium allon, 0.1-0.3 parts water-reducing agent, 1-1.5 parts explosion-proof agent, and 3-4 parts hardening accelerator.

[0031] The tundish slag retaining wall castable for low carbon steel in this embodiment of the invention incorporates a solid solution phase of MgO·Al2O3 spinel and magnesium allon, which is a material formed by magnesium oxide dissolved in the allon phase. On the one hand, MgO·Al2O3 spinel itself has excellent anti-permeation properties against slag, while magnesium allon also has good non-wetting properties against steel slag. Furthermore, after magnesium allon enters the glassy phase of the slag, it increases the viscosity of the glassy phase and reduces the permeability of the slag. At the same time, when magnesium allon reacts with FeO in the slag, gas is generated. Some of the gas exists in the pores of the sample, preventing the slag from further penetrating into the castable, thus significantly improving the anti-permeation properties of the castable. Therefore, adding the solid solution phase of MgO·Al2O3 spinel and magnesium allon can improve the slag erosion resistance of the castable, effectively improve the flotation and removal of inclusions in the steel, and reduce the source of foreign inclusions. On the other hand, since magnesium allon and magnesium aluminum spinel have similar crystal structures, they can be mutually dissolved. After solid solution, they are conducive to the densification and composite of the castable, resulting in a smaller linear change rate of the castable and improving the strength properties of the castable.

[0032] In some embodiments, the raw materials for preparing the solid solution phase of MgO·Al2O3 spinel and magnesium allon include MgO·Al2O3 spinel, α-Al2O3 micro powder, metallic aluminum powder and magnesia; the mass ratio of MgO·Al2O3 spinel, α-Al2O3 micro powder, metallic aluminum powder and magnesia is (6-10):(14-18):(4-8):(3-5). Under nitrogen atmosphere and high temperature reaction conditions, MgO in magnesia reacts with Al2O3 in α-Al2O3 micro powder to form MgAl2O4, which further forms magnesium-rich spinel in the MgO matrix of magnesia and aluminum-rich spinel in the Al2O3 matrix of α-Al2O3 micro powder. As the reaction temperature increases and the oxygen partial pressure decreases, MgO in the MgO matrix becomes unstable and decomposes into Mg(g) and O2(g). In the Al2O3 matrix, the amount of MgO decomposed is relatively small, and Al is transformed into Al(g), which reacts with N2(g), Mg(g), and O2(g) in the system to form MgAlON (i.e., magnesium allon). MgAlON and MgO·Al2O3 spinel are both spinel structures, and they can undergo solid solution to form a solid solution phase of MgO·Al2O3 spinel and magnesium allon. Therefore, it can be seen that the mass ratio of MgO·Al2O3 spinel, α-Al2O3 micro powder, metallic aluminum powder, and magnesia determines the amount of MgO·Al2O3 spinel and magnesium allon formed in the reaction products, as well as the ratio of the two in the solid solution phase. The content of both MgO·Al2O3 spinel and magnesium allon should not be too high or too low. Too little of either phase will reduce the slag erosion resistance of the castable, while too much of either phase will prevent them from forming a solid solution effectively and achieving proper densification, resulting in a larger linear shrinkage rate and reduced strength of the castable. Experiments have shown that using the above-mentioned proportions results in a suitable content of MgO·Al2O3 spinel and magnesium allon, giving the castable good slag erosion resistance, a small linear shrinkage rate, and high strength. The most preferred mass ratio of MgO·Al2O3 spinel, α-Al2O3 micro powder, metallic aluminum powder, and magnesia is 10:18:4:3.

[0033] In some embodiments, the particle size of MgO·Al2O3 spinel is >0μm and ≤44μm, and the Al2O3 content in MgO·Al2O3 spinel is ≥70wt% and the MgO content is ≥20wt%.

[0034] In some embodiments, the particle size of α-Al2O3 micro powder is >0 μm and ≤44 μm, and the Al2O3 content in α-Al2O3 micro powder is ≥99wt%.

[0035] In some embodiments, the bulk density of the aluminum powder is ≥1.03 g / cm³. 3 The aluminum powder contains ≥99wt% Al.

[0036] In some embodiments, the particle size of the magnesia is >0 μm and ≤74 μm, and the MgO content in the magnesia is ≥97.2 wt%.

[0037] In some embodiments, the particle size distribution of white fused alumina can be adjusted. To improve the bulk density and strength properties of the castable, preferably, the white fused alumina comprises white fused alumina particles with a particle size >3mm and ≤5mm, white fused alumina particles with a particle size >1mm and ≤3mm, and white fused alumina fine powder with a particle size >0mm and ≤1mm; the mass ratio of white fused alumina particles with a particle size >3mm and ≤5mm, white fused alumina particles with a particle size >1mm and ≤3mm, and white fused alumina fine powder with a particle size >0mm and ≤1mm is 3:5-6:4-5.

[0038] The Al2O3 content in white fused alumina is ≥99wt%.

[0039] In some embodiments, the water-reducing agent can be any type of existing water-reducing agent, such as polycarboxylic acid or sodium hexametaphosphate. Preferably, the water-reducing agent is a mixture of polycarboxylic acid and sodium hexametaphosphate. Using these two types of water-reducing agents in combination can significantly reduce the amount of water added to the castable, thereby increasing the strength of the castable. Preferably, the mass ratio of polycarboxylic acid to sodium hexametaphosphate is 3-5:1; more preferably, the mass ratio of polycarboxylic acid to sodium hexametaphosphate is 4:1. Preferably, the pH of the water-reducing agent is 7-8.5.

[0040] In some embodiments, the explosion-proof agent is one or a mixture of two of steel fibers and polypropylene fibers. Preferably, the explosion-proof agent is a mixture of steel fibers and polypropylene fibers. Steel fibers can enhance the toughness of the castable, improve its thermal shock resistance, and improve its resistance to cracking and spalling; at the same time, they inhibit the linear shrinkage of the castable after curing, drying, and heat treatment. After carbonization, polypropylene fibers form fine pore channels inside the castable, which is conducive to the removal of moisture from the castable. The combined use of the two can further improve the explosion-proof performance of the castable. Preferably, the mass ratio of steel fibers to polypropylene fibers is 1-3:1; more preferably, the mass ratio of steel fibers to polypropylene fibers is 2:1. The steel fibers are nickel-chromium alloy heat-resistant steel with a refractoriness of 1450℃ and a specification of 0.3×1×25 / 30mm; the polypropylene fibers have the following specifications: length 2.5-3.5mm, diameter 20-40μm, and melting point 173℃-178℃.

[0041] In some embodiments, the hardening accelerator is a mixture of 70g cement and silica fume. When cement is added alone, the corundum in the castable reacts with the components in the cement to produce a large amount of CA6, resulting in significant volume expansion. This leads to increased porosity within the castable, reducing its erosion resistance and high-temperature volume stability. Adding silica fume results in the formation of a small amount of liquid phase within the castable at high temperatures, mitigating the volume expansion caused by the reaction between cement and corundum. Adding only a small amount of silica fume results in low castable strength. As the amount of silica fume increases, more liquid phase is formed at high temperatures, leading to decreased erosion resistance. Therefore, a combination of two hardening accelerators is used to effectively control the volume expansion of the castable at high temperatures and avoid the decrease in erosion resistance caused by excessive liquid phase formation. Preferably, the mass ratio of 70g cement to silica fume is 3:1-3; more preferably, the mass ratio is 3:2.

[0042] The 70G cement contains 28 wt%-30 wt% CaO and 68 wt%-70 wt% Al2O3; the silica powder contains ≥92 wt% SiO2, has a particle size >0 μm and ≤0.620 μm, and a specific surface area of ​​10-15 m². 2 / g.

[0043] Another aspect of the present invention provides a method for preparing the above-mentioned tundish slag retaining wall castable suitable for low carbon steel, comprising the following steps:

[0044] White corundum, MgO·Al2O3 spinel and magnesium allon solid solution phase, water reducing agent, explosion retardant and hardening accelerator are mixed according to the selected mass proportions, and water is added to obtain a mixture; the mixture is placed in a mold, vibrated to form, then cured and baked to obtain the tundish slag retaining wall castable suitable for low carbon steel.

[0045] In some embodiments, the preparation method of the tundish slag retaining wall castable suitable for low carbon steel specifically includes:

[0046] S1. Preparation of solid solution phase of MgO·Al2O3 spinel and magnesium allon;

[0047] S2. Mix MgO·Al2O3 spinel with the solid solution phase of magnesium allon, white corundum particles with a particle size of >3mm and ≤5mm, and white corundum particles with a particle size of >1mm and ≤3mm to obtain granular material.

[0048] S3. Mix the water-reducing agent, explosion-proof agent, and hardening accelerator to obtain a mixture of small materials;

[0049] S4. Pour the granular material, white corundum fine powder with a particle size of >0mm and ≤1mm, and small materials into the mixer in the following order, dry mix, add water, and stir to obtain the mixture.

[0050] S5. Place the mixture into the mold and vibrate to shape;

[0051] S6. Curing the molded mixture with the mold in place, and then removing the mold after curing to obtain the semi-finished product;

[0052] S7. Bake the semi-finished product to obtain a tundish retaining wall castable suitable for low carbon steel.

[0053] In some embodiments, the method for preparing the solid solution phase of MgO·Al2O3 spinel and magnesium allon includes:

[0054] MgO·Al2O3 spinel, α-Al2O3 micro powder, aluminum powder, and magnesia were mixed and kept at 1600℃-1700℃ for 1-5 hours in a nitrogen atmosphere to obtain a solid solution phase of MgO·Al2O3 spinel and magnesium aron.

[0055] Under nitrogen atmosphere and high temperature reaction conditions, MgO in magnesia reacts with Al2O3 in α-Al2O3 micro powder to form MgAl2O4, which further forms magnesium-rich spinel in the MgO matrix of magnesia and aluminum-rich spinel in the Al2O3 matrix of α-Al2O3 micro powder. As the reaction temperature increases and the oxygen partial pressure decreases, MgO in the MgO matrix becomes unstable and decomposes into Mg(g) and O2(g). In the Al2O3 matrix, the amount of MgO decomposed is relatively small, and Al is transformed into Al(g), which reacts with N2(g), Mg(g), and O2(g) in the system to form MgAlON (i.e., magnesium allon). MgAlON and MgO·Al2O3 spinel are both spinel structures, and they can undergo solid solution to form a solid solution phase of MgO·Al2O3 spinel and magnesium allon.

[0056] In some embodiments, the curing temperature is 60-80°C and the time is 16-18 hours.

[0057] In some embodiments, the baking temperature is 240-260°C and the baking time is 6-8 hours.

[0058] In the following embodiments, the Al2O3 content in white fused alumina is ≥99wt%; the particle size of MgO·Al2O3 spinel is >0μm and ≤44μm, the Al2O3 content in MgO·Al2O3 spinel is ≥70wt%, and the MgO content is ≥20wt%; the particle size of α-Al2O3 micro powder is >0μm and ≤44μm, and the Al2O3 content in α-Al2O3 micro powder is ≥99wt%; the particle size of metallic aluminum powder is >0μm and ≤74μm; and the bulk density of metallic aluminum powder is ≥1.03g / cm³. 3 The aluminum powder contains ≥99wt% Al; the magnesia has a particle size >0μm and ≤74μm, and a MgO content ≥97.2wt%; the steel fiber is a nickel-chromium alloy heat-resistant steel with a refractoriness of 1450℃ and a specification of 0.3×1×25 / 30mm; the polypropylene fiber has a length of 2.5-3.5mm, a diameter of 20-40μm, and a melting point of 173℃-178℃; the 70G cement contains 28wt%-30wt% CaO and 68wt%-70wt% Al2O3; the silica powder contains ≥92wt% SiO2, has a particle size >0μm and ≤0.620μm, and a specific surface area of ​​10-15m². 2 / g.

[0059] Example 1

[0060] The refractory material for tundish retaining walls made of low-carbon steel in this embodiment comprises the following components, calculated by mass percentage:

[0061] 15 parts of white fused alumina with a particle size of 5-3 mm, 25 parts of white fused alumina with a particle size of 3-1 mm, 20 parts of white fused alumina with a particle size of 1-0 mm, 35 parts of solid solution phase of MgO·Al2O3 spinel and magnesium allon, 0.3 parts of water-reducing agent (0.24 parts of polycarboxylic acid and 0.06 parts of sodium hexametaphosphate), 1 part of explosion-proof fiber (0.67 parts of steel fiber and 0.33 parts of polypropylene fiber), and 4 parts of hardening accelerator (2.4 parts of 70G cement and 1.6 parts of silica fume).

[0062] The raw materials for preparing the solid solution phase of MgO·Al2O3 spinel and magnesium aron include MgO·Al2O3 spinel, α-Al2O3 micro powder, metallic aluminum powder and magnesia sand; the mass ratio of MgO·Al2O3 spinel, α-Al2O3 micro powder, metallic aluminum powder and magnesia sand is 10:18:4:3.

[0063] The preparation method of the tundish retaining wall castable for low carbon steel in this embodiment includes the following steps:

[0064] S1. Preparation of solid solution phase of MgO·Al2O3 spinel and magnesium allon: Weigh MgO·Al2O3 spinel, α-Al2O3 micro powder, aluminum powder and magnesia according to the mass ratio, mix and stir evenly, and place under nitrogen atmosphere, keep at 1600℃ for 3h to obtain solid solution phase of MgO·Al2O3 spinel and magnesium allon.

[0065] S2. Weigh out the solid solution phase of MgO·Al2O3 spinel and magnesium allon, white corundum particles with a particle size of >3mm and ≤5mm, and white corundum particles with a particle size of >1mm and ≤3mm according to the weight parts, mix and stir evenly to obtain granular material.

[0066] S3. Weigh out the water-reducing agent, explosion-proof agent, and hardening accelerator according to the weight proportions, mix and stir evenly to obtain a small mixture;

[0067] S4. Pour the granular material, white corundum fine powder with a particle size of >0mm and ≤1mm, and small materials into the mixer in the following order. After dry mixing for 4-5 minutes, add 4.6% of the total weight of clean water and stir for 5 minutes to obtain the mixture.

[0068] S5. Place the mixture into a steel mold, vibrate to form, until the surface of the casting material swells and no gas escapes, and let it stand until it solidifies and forms.

[0069] S6. Push the molded mixture and mold into the curing kiln and cure with the mold at 70°C for 17 hours. After curing, remove the mold to obtain the semi-finished product.

[0070] S7. Place the semi-finished product in a baking kiln at 250℃ and bake for 7 hours to obtain a tundish slag retaining wall castable suitable for low carbon steel.

[0071] Example 2

[0072] The refractory material for the tundish retaining wall of low-carbon steel in this embodiment differs from that in Example 1 in that the mass ratio of MgO·Al2O3 spinel, α-Al2O3 micro powder, aluminum powder, and magnesia in the raw materials for preparing the solid solution phase of MgO·Al2O3 spinel and magnesium allon is different. The mass ratio of MgO·Al2O3 spinel, α-Al2O3 micro powder, aluminum powder, and magnesia is 10:15:7:3. The remaining components and contents are the same as in Example 1.

[0073] The preparation method of the tundish retaining wall castable for low carbon steel in this embodiment is the same as that in Embodiment 1.

[0074] Example 3

[0075] The refractory material for the tundish retaining wall of low-carbon steel in this embodiment differs from that in Example 1 in that the mass ratio of MgO·Al2O3 spinel, α-Al2O3 micro powder, aluminum powder, and magnesia in the raw materials for preparing the solid solution phase of MgO·Al2O3 spinel and magnesium allon is different. The mass ratio of MgO·Al2O3 spinel, α-Al2O3 micro powder, aluminum powder, and magnesia is 8:14:8:5. The remaining components and contents are the same as in Example 1.

[0076] The preparation method of the tundish retaining wall castable for low carbon steel in this embodiment is the same as that in Embodiment 1.

[0077] Example 4

[0078] The refractory material for tundish retaining walls made of low-carbon steel in this embodiment comprises the following components, calculated by mass percentage:

[0079] 15 parts of white fused alumina with a particle size of 5-3 mm, 30 parts of white fused alumina with a particle size of 3-1 mm, 20 parts of white fused alumina with a particle size of 1-0 mm, 30 parts of solid solution phase of MgO·Al2O3 spinel and magnesium allon, 0.3 parts of water-reducing agent (0.24 parts of polycarboxylic acid and 0.06 parts of sodium hexametaphosphate), 1 part of explosion-proof fiber (0.67 parts of steel fiber and 0.33 parts of polypropylene fiber), and 4 parts of hardening accelerator (2.4 parts of 70G cement and 1.6 parts of silica fume).

[0080] The raw materials for preparing the solid solution phase of MgO·Al2O3 spinel and magnesium allon include MgO·Al2O3 spinel, α-Al2O3 micro powder, metallic aluminum powder and magnesia; the mass ratio of MgO·Al2O3 spinel, α-Al2O3 micro powder, metallic aluminum powder and magnesia is 6:14:5:5.

[0081] The preparation method of the tundish retaining wall castable for low carbon steel in this embodiment is the same as that in Embodiment 1.

[0082] Example 5

[0083] The refractory material for tundish retaining walls made of low-carbon steel in this embodiment comprises the following components, calculated by mass percentage:

[0084] 15 parts of white fused alumina with a particle size of 5-3 mm, 30 parts of white fused alumina with a particle size of 3-1 mm, 20 parts of white fused alumina with a particle size of 1-0 mm, 31 parts of solid solution phase of MgO·Al2O3 spinel and magnesium allon, 0.3 parts of water-reducing agent (0.24 parts of polycarboxylic acid and 0.06 parts of sodium hexametaphosphate), 1 part of explosion-proof fiber (0.67 parts of steel fiber and 0.33 parts of polypropylene fiber), and 4 parts of hardening accelerator (2.4 parts of 70G cement and 1.6 parts of silica fume).

[0085] The raw materials for preparing the solid solution phase of MgO·Al2O3 spinel and magnesium aron include MgO·Al2O3 spinel, α-Al2O3 micro powder, metallic aluminum powder and magnesia; the mass ratio of MgO·Al2O3 spinel, α-Al2O3 micro powder, metallic aluminum powder and magnesia is 8:15:5:3.

[0086] The preparation method of the tundish retaining wall castable for low carbon steel in this embodiment is the same as that in Embodiment 1.

[0087] Example 6

[0088] The refractory material for tundish retaining walls made of low-carbon steel in this embodiment comprises the following components, calculated by mass percentage:

[0089] 15 parts of white fused alumina with a particle size of 5-3 mm, 30 parts of white fused alumina with a particle size of 3-1 mm, 25 parts of white fused alumina with a particle size of 1-0 mm, 27 parts of solid solution phase of MgO·Al2O3 spinel and magnesium allon, 0.3 parts of water reducing agent (0.24 parts of polycarboxylic acid and 0.06 parts of sodium hexametaphosphate), 1 part of explosion-proof fiber (0.67 parts of steel fiber and 0.33 parts of polypropylene fiber), and 4 parts of hardening accelerator (2 parts of 70G cement and 1 part of silica fume).

[0090] The raw materials for preparing the solid solution phase of MgO·Al2O3 spinel and magnesium aron include MgO·Al2O3 spinel, α-Al2O3 micro powder, metallic aluminum powder and magnesia; the mass ratio of MgO·Al2O3 spinel, α-Al2O3 micro powder, metallic aluminum powder and magnesia is 6:14:4:3.

[0091] The preparation method of the tundish retaining wall castable for low carbon steel in this embodiment is the same as that in Embodiment 1.

[0092] Example 7

[0093] The refractory material for the tundish retaining wall of low-carbon steel in this embodiment differs from that in Example 1 in that the mass ratio of MgO·Al2O3 spinel, α-Al2O3 micro powder, aluminum powder, and magnesia in the raw materials for preparing the solid solution phase of MgO·Al2O3 spinel and magnesium allon is different. The mass ratio of MgO·Al2O3 spinel, α-Al2O3 micro powder, aluminum powder, and magnesia is 4:13:10:8. The remaining components and contents are the same as in Example 1.

[0094] The preparation method of the tundish retaining wall castable for low carbon steel in this embodiment is the same as that in Embodiment 1.

[0095] Example 8

[0096] The refractory material for the tundish retaining wall of low-carbon steel in this embodiment differs from that in Example 1 in that the mass ratio of MgO·Al2O3 spinel, α-Al2O3 micro powder, aluminum powder, and magnesia in the raw materials for preparing the solid solution phase of MgO·Al2O3 spinel and magnesium allon is different. The mass ratio of MgO·Al2O3 spinel, α-Al2O3 micro powder, aluminum powder, and magnesia is 12:18:3:2. The remaining components and contents are the same as in Example 1.

[0097] The preparation method of the tundish retaining wall castable for low carbon steel in this embodiment is the same as that in Embodiment 1.

[0098] Example 9

[0099] The refractory material for tundish retaining walls of low-carbon steel in this embodiment differs from that in Example 1 in the particle size distribution of the white fused alumina. In this embodiment, the white fused alumina consists of: 13 parts of white fused alumina with a particle size of 5-3 mm, 26 parts of white fused alumina with a particle size of 3-1 mm, and 21 parts of white fused alumina with a particle size of 1-0 mm. The remaining components and their contents are the same as in Example 1.

[0100] The preparation method of the tundish retaining wall castable for low carbon steel in this embodiment is the same as that in Embodiment 1.

[0101] Example 10

[0102] The refractory material for tundish retaining walls of low-carbon steel in this embodiment differs from that in Example 1 in the particle size distribution of the white fused alumina. In this embodiment, the white fused alumina consists of: 10 parts of white fused alumina with a particle size of 5-3 mm, 25 parts of white fused alumina with a particle size of 3-1 mm, and 25 parts of white fused alumina with a particle size of 1-0 mm. The remaining components and their contents are the same as in Example 1.

[0103] The preparation method of the tundish retaining wall castable for low carbon steel in this embodiment is the same as that in Embodiment 1.

[0104] Example 11

[0105] The refractory material for tundish retaining walls of low-carbon steel in this embodiment differs from that in Example 1 in the particle size distribution of the white fused alumina. In this embodiment, the white fused alumina consists of: 20 parts of white fused alumina with a particle size of 5-3 mm, 20 parts of white fused alumina with a particle size of 3-1 mm, and 20 parts of white fused alumina with a particle size of 1-0 mm. The remaining components and their contents are the same as in Example 1.

[0106] The preparation method of the tundish retaining wall castable for low carbon steel in this embodiment is the same as that in Embodiment 1.

[0107] Example 12

[0108] The refractory material for tundish retaining walls made of low-carbon steel in this embodiment differs from that in Example 1 in the mass ratio of polycarboxylate to sodium hexametaphosphate in the water-reducing agent. In this embodiment, the polycarboxylate content is 0.225 parts, and the sodium hexametaphosphate content is 0.075 parts. The remaining components and their contents are the same as in Example 1.

[0109] The preparation method of the tundish retaining wall castable for low carbon steel in this embodiment is the same as that in Embodiment 1.

[0110] Example 13

[0111] The refractory material for tundish retaining walls made of low-carbon steel in this embodiment differs from that in Example 1 in the mass ratio of polycarboxylic acid to sodium hexametaphosphate in the water-reducing agent. In this embodiment, the polycarboxylic acid content is 0.25 parts and the sodium hexametaphosphate content is 0.05 parts. The remaining components and their contents are the same as in Example 1.

[0112] The preparation method of the tundish retaining wall castable for low carbon steel in this embodiment is the same as that in Embodiment 1.

[0113] Example 14

[0114] The refractory material for tundish retaining walls made of low-carbon steel in this embodiment differs from that in Example 1 in the mass ratio of polycarboxylate to sodium hexametaphosphate in the water-reducing agent. In this embodiment, the polycarboxylate content is 0.15 parts, and the sodium hexametaphosphate content is 0.15 parts. The remaining components and their contents are the same as in Example 1.

[0115] The preparation method of the tundish retaining wall castable for low carbon steel in this embodiment is the same as that in Example 1. In step S4, 5% of the total weight of the material is added as clean water.

[0116] Example 15

[0117] The refractory material for tundish retaining walls made of low-carbon steel in this embodiment differs from that in Example 1 in the mass ratio of polycarboxylate to sodium hexametaphosphate in the water-reducing agent. In this embodiment, the polycarboxylate content is 0.27 parts and the sodium hexametaphosphate content is 0.03 parts. The remaining components and their contents are the same as in Example 1.

[0118] The preparation method of the tundish retaining wall castable for low carbon steel in this embodiment is the same as that in Example 1. In step S4, 5% of the total weight of the material is added as clean water.

[0119] Example 16

[0120] The refractory material for tundish retaining walls made of low-carbon steel in this embodiment differs from that in Example 1 in the mass ratio of 70g cement to silica fume in the hardening accelerator. In this embodiment, 70g cement is 3 parts and silica fume is 1 part. The remaining components and their contents are the same as in Example 1.

[0121] The preparation method of the tundish retaining wall castable for low carbon steel in this embodiment is the same as that in Embodiment 1.

[0122] Example 17

[0123] The refractory material for tundish retaining walls made of low-carbon steel in this embodiment differs from that in Example 1 in the mass ratio of 70g cement to silica fume in the hardening accelerator. In this embodiment, 2 parts of 70g cement and 2 parts of silica fume are used. The remaining components and their contents are the same as in Example 1.

[0124] The preparation method of the tundish retaining wall castable for low carbon steel in this embodiment is the same as that in Embodiment 1.

[0125] Example 18

[0126] The refractory material for tundish retaining walls made of low-carbon steel in this embodiment differs from that in Example 1 in the mass ratio of 70g cement to silica fume in the hardening accelerator. In this embodiment, 70g cement is 3.2 parts and silica fume is 0.8 parts. The remaining components and their contents are the same as in Example 1.

[0127] The preparation method of the tundish retaining wall castable for low carbon steel in this embodiment is the same as that in Embodiment 1.

[0128] Example 19

[0129] The refractory material for tundish retaining walls made of low-carbon steel in this embodiment differs from that in Example 1 in the mass ratio of 70g cement to silica fume in the hardening accelerator. In this embodiment, 70g cement is 1 part and silica fume is 3 parts. The remaining components and their contents are the same as in Example 1.

[0130] The preparation method of the tundish retaining wall castable for low carbon steel in this embodiment is the same as that in Embodiment 1.

[0131] Comparative Example 1

[0132] The intermediate ladle retaining wall castable in this comparative example, calculated by mass parts, comprises the following raw materials:

[0133] 15 parts of white fused alumina with a particle size of 5-3 mm, 25 parts of white fused alumina with a particle size of 3-1 mm, 20 parts of white fused alumina with a particle size of 1-0 mm, 10 parts of MgO·Al2O3 spinel, 18 parts of α-Al2O3 micro powder, 4 parts of metallic aluminum powder, 3 parts of magnesia, 0.3 parts of water-reducing agent (0.24 parts of polycarboxylic acid and 0.06 parts of sodium hexametaphosphate), 1 part of explosion-proof fiber (0.67 parts of steel fiber and 0.33 parts of polypropylene fiber), and 4 parts of hardening accelerator (2.4 parts of 70G cement and 1.6 parts of silica fume).

[0134] The intermediate ladle slag retaining wall castables of the above embodiments and comparative examples were prepared into samples, and their static slag resistance, porosity, bulk density, flexural strength, compressive strength and other properties were tested. The test results are shown in Table 1 below.

[0135] As can be seen from Table 1 below, the difference between the tundish slag retaining wall castable of Comparative Example 1 and the tundish slag retaining wall castable of Example 1 of the present invention is that in Example 1, the raw materials for preparing the castable are directly added to the solid solution phase of synthesized MgO·Al2O3 spinel and magnesium allon, while in Comparative Example 1, the same mass fractions of magnesium aluminum spinel, alumina, metallic aluminum, and magnesia are added. Since the temperature at which the solid solution phase of MgO·Al2O3 spinel and magnesium allon is not reached under the steel casting conditions, i.e., the tested temperature of around 1500°C, is not reached, and there is no nitrogen atmosphere, the above raw materials cannot react to form the solid solution phase of MgO·Al2O3 spinel and magnesium allon. Therefore, the slag erosion resistance, flexural strength, and compressive strength of the castable of Comparative Example 1 at room temperature and high temperature are not as good as those of the castables of the various embodiments of this application.

[0136] In comparison, the difference between Examples 1-3, 7, and 8 of this application lies in the different proportions of magnesium aluminum spinel, alumina, metallic aluminum, and magnesia. Examples 1-3 exhibit higher slag resistance and strength properties than Examples 7 and 8, indicating that the mass ratio of magnesium aluminum spinel, alumina, metallic aluminum, and magnesia in Examples 1-3 is within the preferred range. The difference between Examples 1 and 9-11 lies in the different particle size distribution of white fused alumina. Examples 1 and 9 exhibit higher slag resistance and strength properties than Examples 10 and 11, indicating that the particle size distribution of white fused alumina in Examples 1 and 9 is within the preferred range. Compared to Examples 1 and 12-15… The difference lies in the ratio of polycarboxylic acid to sodium hexametaphosphate in the water-reducing agent. In comparison, Examples 14 and 15 require more water, and their strength properties are significantly worse than those of Examples 1, 12, and 13, indicating that the ratio of polycarboxylic acid to sodium hexametaphosphate in Examples 1, 12, and 13 is within the preferred range. Compared with Examples 1 and 16-19, the difference lies in the mass ratio of steel fiber to polypropylene fiber in the explosion-proof agent. In comparison, the strength properties and slag erosion resistance of Examples 1, 16, and 17 are significantly better than those of Examples 18 and 19, indicating that the ratio of steel fiber to polypropylene fiber in Examples 1, 16, and 17 is within the preferred range.

[0137] Table 1

[0138]

[0139] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A tundish dam wall castable suitable for low carbon steel characterized in that, The preparation raw materials include the following components in mass fraction: white corundum 60-70 parts, solid solution phase of MgO-Al2O3 spinel and magnesia-alumina spinel 27-35 parts, water reducing agent 0.1-0.3 parts, explosion-proof agent 1-1.5 parts, hardening agent 3-4 parts; the preparation raw materials of the solid solution phase of MgO-Al2O3 spinel and magnesia-alumina spinel include MgO-Al2O3 spinel, α-Al2O3 micro powder, metal aluminum powder and magnesia; the mass ratio of MgO-Al2O3 spinel, α-Al2O3 micro powder, metal aluminum powder and magnesia is (6-10):(14-18):(4-8):(3-5); the preparation method of the solid solution phase of MgO-Al2O3 spinel and magnesia-alumina spinel includes: mixing MgO-Al2O3 spinel, α-Al2O3 micro powder, metal aluminum powder and magnesia, and keeping the mixture at a temperature of 1600-1700℃ for 1-5h in a nitrogen atmosphere to obtain the solid solution phase of MgO-Al2O3 spinel and magnesia-alumina spinel.

2. The tundish slag stopping wall castable suitable for low carbon steel according to claim 1, wherein: the particle size of MgO-Al2O3 spinel is >0 μm and ≤44 μm, the Al2O3 content in MgO-Al2O3 spinel is ≥70 wt%, and the MgO content is ≥20 wt%; the particle size of α-Al2O3 micro powder is >0 μm and ≤44 μm, and the Al2O3 content in α-Al2O3 micro powder is ≥99 wt%; Bulk density of the metal aluminum powder ≥ 1.03 g / cm 3 Al content in the metal aluminum powder ≥ 99 wt.-%; the particle size of magnesia is >0 μm and ≤74 μm, and the MgO content in magnesia is ≥97.2 wt%.

3. The tundish slag stopping wall castable suitable for low carbon steel according to claim 1, wherein: the white corundum includes white corundum particles with a particle size of >3 mm and ≤5 mm, white corundum particles with a particle size of >1 mm and ≤3 mm, and white corundum fine powder with a particle size of >0 mm and ≤1 mm; the mass ratio of white corundum particles with a particle size of >3 mm and ≤5 mm, white corundum particles with a particle size of >1 mm and ≤3 mm, and white corundum fine powder with a particle size of >0 mm and ≤1 mm is 3:5-6:4-5; the Al2O3 content in white corundum is ≥99 wt%.

4. The tundish slag stopping wall castable suitable for low carbon steel according to claim 1, wherein: the water reducing agent is a mixture of polycarboxylic acid and sodium hexametaphosphate; the mass ratio of polycarboxylic acid to sodium hexametaphosphate is 4:1; and the pH of the water reducing agent is 7-8.

5.

5. The tundish slag stopping wall castable suitable for low carbon steel according to claim 1, wherein: the explosion-proof agent is a mixture of steel fiber and polypropylene fiber; the mass ratio of steel fiber to polypropylene fiber is 2:1; the steel fiber is nickel-chromium alloy heat-resistant steel, the refractoriness is 1450℃, and the specification is 0.3×1×25 / 30 mm; the specification of the polypropylene fiber is: length 2.5-3.5 mm, diameter 20-40 μm, and melting point 173-178℃.

6. The tundish slag stopping wall castable suitable for low carbon steel according to claim 1, wherein: The hardening accelerator is a mixture of 70G cement and silica powder, and the mass ratio of 70G cement to silica powder is 3:2; The 70G cement has a CaO content of 28wt%-30wt% and an Al2O3 content of 68wt%-70wt%; the silicon micro powder has a SiO2 content of ≥92wt%, the particle size of the silicon micro powder is >0μm and ≤0.620μm, and the specific surface area of the silicon micro powder is 10-15m 2 / g.

7. A process for the preparation of a tundish dam wall castable suitable for low carbon steel according to any one of claims 1 to 6, characterized in that, The method comprises the following steps: White corundum, MgO·Al2O3 spinel and solid solution phase of magnesium aluminide, water reducing agent, explosion-proof agent and hardening accelerator are mixed according to selected mass fractions, and water is added to obtain a mixture; the mixture is put into a mold, vibration formed, then cured, and finally baked to obtain the intermediate ladle slag retaining wall castable suitable for low carbon steel.

8. The preparation method of claim 7, wherein: The curing temperature is 60-80 DEG C, and the curing time is 16-18h; The baking temperature is 240-260 DEG C, and the baking time is 6-8h.

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