A slag dam for a tundish and a method for manufacturing the same

Abstract

The application belongs to the technical field of refractory materials, and discloses a slag dam for tundish and a preparation method thereof. The slag dam for tundish comprises the following components in percentage by weight: 30-38% of forsterite with a particle size of 15-8mm, 5-15% of recycled magnesium-aluminum spinel with a particle size of 5-3mm, 10-25% of recycled magnesium-aluminum spinel with a particle size of 3-1mm, 10-20% of fused magnesite with a particle size of 1-0mm, 10-20% of fused magnesite with a particle size of 180 meshes, 2-8% of light-burned magnesia powder with a particle size of 1000 meshes, 1-5% of silicon carbide with a particle size of less than 240 meshes, and 2-6% of silica ash with a particle size of less than 2 microns; and 0.1-0.15% of dispersant, 0.01-0.02% of retarder and 0.06-0.08% of anti-explosion fiber account for the total weight of the above raw materials. The slag dam for tundish has the advantages of low cost, small water consumption, good slag resistance, high erosion resistance and long service life.

Description

Technical Field

[0001] This invention relates to the field of refractory materials technology, specifically to a slag-blocking weir for tundishes and its preparation method. Background Technology

[0002] The tundish is an intermediate step in the steelmaking process, serving as the transition point from intermittent to continuous operation. As a metallurgical reactor, the tundish is crucial for improving both steel yield and quality. Its role is indispensable for both the smooth operation of continuous casting and ensuring the required steel quality.

[0003] The slag weir spans the entire width of the tundish, extending from above the molten steel surface to a certain distance from the bottom of the tundish, allowing molten steel to flow underneath it. Its functions in the tundish are: 1) to control the size of the ladle pouring impact zone, controlling the stirring intensity of the ladle pouring on the molten steel in the tundish, and promoting the collision and aggregation of inclusions into large particles for removal; 2) to block the slag entering the tundish with the ladle pouring within the pouring impact zone, reducing secondary pollution of the molten steel caused by slag entrapment; 3) to limit the surface fluctuations of the molten steel in the tundish caused by the ladle pouring impact to the upstream of the slag weir, stabilizing the molten steel surface downstream of the slag weir, and reducing the amount of inclusions caused by surface slag entrapment, secondary oxidation, and mechanical scouring.

[0004] Magnesia is mostly used for slag weirs. It has high refractoriness and good resistance to alkaline slag. Magnesia raw material resources are abundant and can reduce non-metallic inclusions in steel. It has advantages such as desulfurization, dephosphorization and improvement of steel cleanliness. However, magnesia raw materials also have disadvantages such as large thermal expansion coefficient and easy hydration, which makes the material's thermal shock stability and slag penetration resistance worse, which can easily cause cracking and collapse during production and use.

[0005] Chinese patent application CN 106699201 A describes a "castable refractory for slag retaining walls in steelmaking tundishes", which is composed of 50-70% waste magnesia-carbon bricks, 20-30% medium-grade magnesia, 2-5% silica fume, 5-8% aluminum fume, 2-5% silicon carbide, and 1-2% stainless steel fiber. It reduces costs and improves slag resistance and service life. However, the medium-grade magnesia is prone to hydration, which can cause cracks during production and use.

[0006] Chinese patent application CN 101913908 A describes a "castable refractory for magnesia-olivine intermediate ladle slag retaining wall and its production process". It is composed of 5-70 parts of magnesia-olivine, 15-85 parts of magnesia sand, 5-15 parts of corundum powder, 3-5 parts of composite additives, 0.1 parts of organic fiber and 1 part of steel fiber. The cost is reduced and the product performance is significantly improved. However, the water content is 5.5-6 parts, which will have a certain impact on the performance of the castable.

[0007] Chinese patent application CN112500131A describes a "low-cost intermediate ladle preform and its preparation method," which is composed of 20-45% recycled magnesium aluminum spinel particles, 20-50% magnesia particles, 10-30% magnesia, 0.5-5% magnesium binder, 1-4% Si2N2O, 2-5% silica powder, 0.01-0.03% metallic aluminum powder, 0.1-0.15% sodium tripolyphosphate, 0.1-0.15% sodium hexametaphosphate, and 0.05-0.15% organic fiber. This method reduces costs and improves the high-temperature performance and service life of the product. However, the use of a magnesium binder results in a longer initial setting time for the castable, affecting production schedules. Summary of the Invention

[0008] To address the aforementioned problems, the present invention aims to provide a slag-blocking weir for raw magnesia-olivine-recycled magnesia-alumina spinel intermediate tundishes that is low in cost, requires less water, has good slag resistance, is resistant to erosion, and has a long service life.

[0009] The objective of this invention can be achieved through the following technical solutions:

[0010] A slag-blocking weir for tundishes, comprising the following components by weight percentage:

[0011]

[0012] And 0.1% to 0.15% of the total weight of the above raw materials, 0.01% to 0.02% of the retarder and 0.06% to 0.08% of the explosion-proof fiber.

[0013] More preferably, the mass percentage of MgO in raw magnesium olivine is ≥45%.

[0014] More preferably, the recycled magnesium aluminum spinel is obtained from waste periclase-magnesia spinel bricks from RH refining furnaces recycled by steel plants through processes such as crushing, slag removal, iron removal, hydration, and shaping. The recycled magnesium aluminum spinel contains ≥85% MgO by mass and ≥93% MgO and Al2O3 by mass.

[0015] More preferably, the fused magnesia contains ≥97% MgO by mass, the lightly calcined magnesia powder contains ≥92% MgO by mass, the silicon carbide contains ≥95% SiC by mass, and the silica fume contains ≥95% SiO2 by mass.

[0016] More preferably, the dispersant is the high-efficiency water-reducing dispersant Monoladd 380s.

[0017] More preferably, the retarder is one or a mixture of sodium citrate and sodium gluconate.

[0018] More preferably, the explosion-proof fiber has a diameter of 40 μm and a length of 2–3 mm.

[0019] A method for preparing a slag-blocking weir for an intermediate ladle includes the following steps:

[0020] (1) Weigh all raw materials according to the proportion of the slag weir for the intermediate tundish;

[0021] (2) The 180-mesh fused magnesia, 1000-mesh lightly calcined magnesia powder, <240-mesh silicon carbide and <2μm silica fume weighed in step (1), as well as dispersant and retarder, are premixed for 15-20 minutes.

[0022] (3) Add the 15-8mm raw magnesium olivine, 5-3mm and 3-1mm recycled magnesium aluminum spinel, 1-0mm fused magnesia, and explosion-proof fiber weighed in step (1) to the fine powder premixed in step (2) and mix for 2-3 minutes.

[0023] (4) Add water of 3.9% to 4.1% of its total mass to the well-mixed material in step (3) and stir for 3 to 4 minutes;

[0024] (5) Place the well-stirred material from step (4) into the mold and vibrate it to remove air bubbles. Use a vibrating rod to assist in the molding process until it is fully compacted.

[0025] (6) After molding, place the preform and the mold together in a wet curing kiln with a temperature of 45-48℃ and a humidity of 50-60RH for 12-14 hours, and then demold.

[0026] (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℃ and baked for 24-36 hours to obtain the slag weir for intermediate ladle.

[0027] The beneficial effects of this invention are:

[0028] This invention optimizes the ingredient mix, selecting raw magnesia olivine, fused magnesia, and recycled magnesia-alumina spinel obtained from waste RH refining furnace periclase-magnesia spinel bricks recovered from steel mills through crushing, iron removal, hydration, and shaping as the main raw materials. These materials are not easily hydrated, ensuring no cracks appear during curing and baking. Silica fume is used for MgO-SiO2-H2O coagulation and bonding. On the one hand, the polymerization effect of the SiO2 gel formed by the reaction of silica fume and water reduces the amount of water added, significantly improving the fluidity of the castable; on the other hand, the MgO-SiO2-H2O bonding method inhibits magnesia hydration. In addition, the addition of silicon carbide, working synergistically with recycled magnesium aluminum spinel, improves slag erosion resistance. Simultaneously, silicon carbide generates SiO2 at high temperatures, which reacts with MgO to form M2S, further enhancing the high-temperature performance of the slag-blocking weir. The addition of an appropriate amount of lightly calcined magnesium oxide powder promotes the MgO-SiO2-H2O reaction, increasing reaction products and thus improving the demolding strength after wet curing, ensuring no cracking occurs during demolding. The use of the highly efficient water-reducing dispersant Monoled 380s as a dispersant, supplemented with sodium citrate and / or sodium gluconate as retarder, reduces the amount of water added to the precast components, further improving their performance.

[0029] Overall, the slag weir for the tundish of this invention uses raw magnesia olivine and recycled magnesia-alumina spinel to replace part of the magnesia raw material, significantly reducing costs to approximately 2000 yuan / ton. It employs the highly efficient water-reducing dispersant Monoled 380s as a dispersant, supplemented with sodium citrate and / or sodium gluconate as retarder, resulting in low water addition (3.9%–4.1%). Silica fume is used for MgO-SiO2-H2O coagulation and bonding, improving the fluidity of the castable while further inhibiting magnesia hydration, resulting in a high yield and no cracking during production. Furthermore, the addition of silicon carbide, working synergistically with the recycled magnesia-alumina spinel, enhances resistance to slag erosion. The slag weir produced by this invention has demonstrated excellent performance in tundish applications, showing no abnormal erosion or deformation after more than 12 heats.

[0030] Of course, any product implementing this invention does not necessarily need to achieve all of the advantages described above at the same time. Detailed Implementation

[0031] The technical solutions in the embodiments of the present invention have been clearly and completely described. 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 skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] In all embodiments of the present invention, the raw magnesium olivine contains ≥45% MgO by mass; the recycled magnesium aluminum spinel is obtained from waste periclase-magnesia spinel bricks from RH refining furnaces recycled from steel plants through processes such as crushing, slag removal, iron removal, hydration, and shaping; the recycled magnesium aluminum spinel contains ≥85% MgO by mass and ≥93% MgO and Al2O3 by mass; the fused magnesia contains ≥97% MgO by mass, the lightly calcined magnesium oxide powder contains ≥92% MgO by mass, the silicon carbide contains ≥95% SiC by mass, and the silica fume contains ≥95% SiO2 by mass; the explosion-proof fiber has a diameter of 40μm and a length of 2-3mm.

[0033] Example 1

[0034] A slag-blocking weir for tundishes comprises the following components by weight percentage: 32% raw magnesia olivine (15-8 mm), 12% recycled magnesia alumina spinel (5-3 mm), 15% recycled magnesia alumina spinel (3-1 mm), 16% fused magnesia (1-0 mm), 12% fused magnesia (180 mesh), 6% lightly calcined magnesia powder (1000 mesh), 4% silicon carbide (<240 mesh), and 3% silica fume (<2 μm).

[0035] And, by weight of the above raw materials, 0.15% of the high-efficiency water-reducing dispersant Monoladd 380s, 0.02% of sodium citrate, and 0.06% of explosion-proof fiber.

[0036] The method for preparing a slag-blocking weir for an intermediate ladle includes the following steps:

[0037] (1) Weigh all raw materials according to the proportion of the slag weir for the intermediate tundish;

[0038] (2) The 180-mesh fused magnesia, 1000-mesh lightly calcined magnesia powder, <240-mesh silicon carbide and <2μm silica fume weighed in step (1), as well as dispersant and retarder, are premixed for 15 min.

[0039] (3) Add the 15-8mm raw magnesium olivine, 5-3mm and 3-1mm recycled magnesium aluminum spinel, 1-0mm fused magnesia, and explosion-proof fiber weighed in step (1) to the fine powder premixed in step (2) and mix for 2 minutes.

[0040] (4) Add water accounting for 3.9% of the total mass of the mixture in step (3) and stir for 4 minutes;

[0041] (5) Place the well-stirred material from step (4) into the mold and vibrate it to remove air bubbles. Use a vibrating rod to assist in the molding process until it is fully compacted.

[0042] (6) After molding, place the preform and the mold together in a wet curing kiln with a temperature of 45℃ and a humidity of 60RH for 14 hours, and then demold.

[0043] (7) After demolding, the preform is placed in a dry curing kiln at 60°C for 36 hours, and then sent to a baking kiln to be heated to 240°C and baked for 24 hours to obtain the slag weir for intermediate ladle.

[0044] The performance of the slag-blocking weir (with a water content of 3.9%) prepared in Example 1 was tested, and the results were as follows: 1) the compressive strength at 110℃*24h was 56.4MPa; 2) the linear change at 1500℃*3h (%) was 0.41%; and the compressive strength was 49.3MPa.

[0045] The slag-blocking weir prepared in Example 1 was used in a 70t tundish at a steel plant: it was used for 13 heats, 629 minutes, and the results were normal, with no abnormal erosion or deformation.

[0046] Example 2

[0047] A slag-blocking weir for tundishes comprises the following components by weight percentage: 33% raw magnesia-olivine (15-8 mm), 10% recycled magnesia-alumina spinel (5-3 mm), 17% recycled magnesia-alumina spinel (3-1 mm), 14% fused magnesia (1-0 mm), 14% fused magnesia (180 mesh), 5% lightly calcined magnesia powder (1000 mesh), 3% silicon carbide (<240 mesh), and 4% silica fume (<2 μm).

[0048] And, by weight of the above raw materials, 0.1% of the high-efficiency water-reducing dispersant Monoled 380s, 0.02% of sodium gluconate, and 0.06% of explosion-proof fiber.

[0049] The method for preparing a slag-blocking weir for an intermediate ladle includes the following steps:

[0050] (1) Weigh all raw materials according to the proportion of the slag weir for the intermediate tundish;

[0051] (2) The 180-mesh fused magnesia, 1000-mesh lightly calcined magnesia powder, <240-mesh silicon carbide and <2μm silica fume weighed in step (1), along with dispersant and retarder, are premixed for 18 minutes.

[0052] (3) Add the 15-8mm raw magnesium olivine, 5-3mm and 3-1mm recycled magnesium aluminum spinel, 1-0mm fused magnesia, and explosion-proof fiber weighed in step (1) to the fine powder premixed in step (2) and mix for 3 minutes.

[0053] (4) Add water accounting for 3.95% of the total mass of the mixture in step (3) and stir for 4 minutes;

[0054] (5) Place the well-stirred material from step (4) into the mold and vibrate it to remove air bubbles. Use a vibrating rod to assist in the molding process until it is fully compacted.

[0055] (6) After molding, the preform and the mold are placed together in a wet curing kiln with a temperature of 46℃ and a humidity of 55RH for 13 hours and then demolded.

[0056] (7) After demolding, the preform is placed in a dry curing kiln at 55°C for 30 hours, and then sent to a baking kiln to be heated to 250°C and baked for 30 hours to obtain the slag weir for intermediate ladle.

[0057] The performance of the slag-blocking weir (with a water content of 3.95%) prepared in Example 2 was tested, and the results were as follows: 1) the compressive strength at 110℃*24h was 59.0MPa; 2) the linear change at 1500℃*3h (%) was 0.50%; and the compressive strength was 55.9MPa.

[0058] The slag-blocking weir prepared in Example 2 was used in a 70t tundish at a steel plant: it was used for 12 heats, 593 minutes, and was normal, with no abnormal erosion or deformation.

[0059] Example 3

[0060] A slag-blocking weir for tundishes comprises the following components by weight percentage: 33% raw magnesia olivine (15-8 mm), 10% recycled magnesia alumina spinel (5-3 mm), 18% recycled magnesia alumina spinel (3-1 mm), 15% fused magnesia (1-0 mm), 12% fused magnesia (180 mesh), 4% lightly calcined magnesia powder (1000 mesh), 3% silicon carbide (<240 mesh), and 5% silica fume (<2 μm).

[0061] And 0.1% of the total weight of the above raw materials, of the high-efficiency water-reducing dispersant Monoladd 380s, 0.01% of sodium gluconate and 0.08% of explosion-proof fiber.

[0062] The method for preparing a slag-blocking weir for an intermediate ladle includes the following steps:

[0063] (1) Weigh all raw materials according to the proportion of the slag weir for the intermediate tundish;

[0064] (2) The 180-mesh fused magnesia, 1000-mesh lightly calcined magnesia powder, <240-mesh silicon carbide and <2μm silica fume weighed in step (1), as well as dispersant and retarder, are premixed for 20 minutes.

[0065] (3) Add the 15-8mm raw magnesium olivine, 5-3mm and 3-1mm recycled magnesium aluminum spinel, 1-0mm fused magnesia, and explosion-proof fiber weighed in step (1) to the fine powder premixed in step (2) and mix for 3 minutes.

[0066] (4) Add water accounting for 4.1% of the total mass of the mixture in step (3) and stir for 3 minutes;

[0067] (5) Place the well-stirred material from step (4) into the mold and vibrate it to remove air bubbles. Use a vibrating rod to assist in the molding process until it is fully compacted.

[0068] (6) After molding, place the preform and the mold together in a wet curing kiln with a temperature of 45℃ and a humidity of 50RH for 14 hours, and then demold.

[0069] (7) After demolding, the preform is placed in a dry curing kiln at 60°C for 36 hours, and then sent to a baking kiln to be heated to 260°C and baked for 36 hours to obtain the slag weir for intermediate ladle.

[0070] The performance of the slag-blocking weir (with a water content of 4.1%) prepared in Example 3 was tested, and the results were as follows: 1) The compressive strength at 110℃ for 24 hours was 48.7 MPa; 2) The linear change at 1500℃ for 3 hours (%) was 0.53%; the compressive strength was 44.8 MPa.

[0071] The slag weir prepared in Example 3 was used in a 70t tundish at a steel plant: it was used for 12 heats, 602 minutes, and the results were normal, with no abnormal erosion or deformation.

[0072] Example 4

[0073] A slag-blocking weir for tundishes comprises the following components by weight percentage: 33% raw magnesia olivine (15-8 mm), 10% recycled magnesia alumina spinel (5-3 mm), 18% recycled magnesia alumina spinel (3-1 mm), 15% fused magnesia (1-0 mm), 12% fused magnesia (180 mesh), 4% lightly calcined magnesia powder (1000 mesh), 3% silicon carbide (<240 mesh), and 5% silica fume (<2 μm).

[0074] And 0.1% of the total weight of the above raw materials, of the high-efficiency water-reducing dispersant Monoladd 380s, 0.01% of sodium gluconate and 0.08% of explosion-proof fiber.

[0075] The method for preparing a slag-blocking weir for an intermediate ladle includes the following steps:

[0076] (1) Weigh all raw materials according to the proportion of the slag weir for the intermediate tundish;

[0077] (2) The 180-mesh fused magnesia, 1000-mesh lightly calcined magnesia powder, <240-mesh silicon carbide and <2μm silica fume weighed in step (1), as well as dispersant and retarder, are premixed for 15-20 minutes.

[0078] (3) Add the 15-8mm raw magnesium olivine, 5-3mm and 3-1mm recycled magnesium aluminum spinel, 1-0mm fused magnesia, and explosion-proof fiber weighed in step (1) to the fine powder premixed in step (2) and mix for 2-3 minutes.

[0079] (4) Add water accounting for 4.0% of the total mass of the mixture in step (3) and stir for 4 minutes;

[0080] (5) Place the well-stirred material from step (4) into the mold and vibrate it to remove air bubbles. Use a vibrating rod to assist in the molding process until it is fully compacted.

[0081] (6) After molding, place the preform and the mold together in a wet curing kiln with a temperature of 47°C and a humidity of 60%RH for 12 hours, and then demold.

[0082] (7) After demolding, the preform is placed in a dry curing kiln at 60°C for 24 hours, and then sent to a baking kiln to be heated to 260°C and baked for 24 hours to obtain the slag weir for intermediate ladle.

[0083] The performance of the slag-blocking weir (with a water content of 4.0%) prepared in Example 4 was tested, and the results were as follows: 1) The compressive strength at 110℃*24h was 53.8MPa; 2) The linear change (%) at 1500℃*3h was 0.48%; and the compressive strength was 49.6MPa.

[0084] The slag-blocking weir prepared in Example 4 was used in a 70t tundish at a steel plant: it was used for 13 heats, 637 minutes, and was normal, with no abnormal erosion or deformation.

[0085] Comparative Example 1

[0086] A type of slag-retaining weir castable for intermediate ladles, expressed as a weight percentage, is composed of the following raw materials:

[0087] The composition includes 32% raw magnesium olivine (15-8mm), 12% recycled magnesium aluminum spinel (5-3mm), 15% recycled magnesium aluminum spinel (3-1mm), 16% fused magnesia (1-0mm), 12% fused magnesia (180 mesh), 6% lightly calcined magnesium oxide powder (1000 mesh), 4% silicon carbide (<240 mesh), 3% silica fume (<2μm), and sodium hexametaphosphate (0.1% by weight), sodium tripolyphosphate (0.05%), sodium citrate (0.02%), and explosion-proof fiber (0.06%).

[0088] The refractory material for the slag-blocking weir in the intermediate ladle is prepared by the following method, and the specific operating steps are as follows:

[0089] (1) Weigh out all raw materials according to the above proportions;

[0090] (2) The 180-mesh fused magnesia, 1000-mesh lightly calcined magnesia powder, <240-mesh silicon carbide and <2μm silica fume weighed in step (1), as well as sodium hexametaphosphate, sodium tripolyphosphate and sodium citrate are premixed.

[0091] (3) The 15-8mm raw magnesium olivine, 5-3mm and 3-1mm recycled magnesium aluminum spinel, 1-0mm fused magnesia, and explosion-proof fiber weighed in step (1) are added to the fine powder premixed in step (2) and mixed and ground.

[0092] (4) Add a certain amount of water to the fine powder and granules mixed in step (3), stir evenly, and then put them into a mold and vibrate to form.

[0093] In Comparative Example 1, sodium hexametaphosphate and sodium tripolyphosphate were used as a water-reducing dispersant, and the amount of water added to the slag weir castable increased to 4.3%. Meanwhile, the compressive strength at 110℃ for 24 hours was 39.2 MPa, which was significantly lower than the compressive strength of 56.4 MPa in Example 1.

[0094] Comparative Example 2

[0095] A type of slag-retaining weir castable for intermediate ladles, expressed as a weight percentage, is composed of the following raw materials:

[0096] The composition includes 32% raw magnesium olivine (15-8mm), 12% recycled magnesium aluminum spinel (5-3mm), 15% recycled magnesium aluminum spinel (3-1mm), 16% recycled magnesium aluminum spinel (1-0mm), 12% fused magnesia (180 mesh), 6% lightly calcined magnesium oxide powder (1000 mesh), 4% silicon carbide (<240 mesh), 3% silica fume (<2μm), and 0.15% of the total weight of the above raw materials as a high-efficiency water-reducing dispersant Monoled 380s, 0.02% sodium citrate, and 0.06% explosion-proof fiber.

[0097] The refractory material for the slag-blocking weir in the intermediate ladle is prepared by the following method, and the specific operating steps are as follows:

[0098] (1) Weigh out all raw materials according to the above proportions;

[0099] (2) The 180-mesh fused magnesia, 1000-mesh lightly calcined magnesia powder, <240-mesh silicon carbide and <2μm silica fume weighed in step (1), as well as the high-efficiency water-reducing dispersant Monoladd 380s and sodium citrate are premixed.

[0100] (3) The raw magnesium olivine weighed in step (1) with a diameter of 15-8 mm and recycled magnesium aluminum spinel with diameters of 5-3 mm, 3-1 mm and 1-0 mm, as well as explosion-proof fiber, are added to the fine powder premixed in step (2) and mixed and ground.

[0101] (4) Add a certain amount of water to the fine powder and granules mixed in step (3), stir evenly, and then put them into a mold and vibrate to form.

[0102] In Comparative Example 2, 1-0 mm of recycled magnesium aluminum spinel was added, and the slag weir castable dispersed, and it still could not be formed even after the water content reached 4.3%.

[0103] Comparative Example 3

[0104] A type of slag-retaining weir castable for intermediate ladles, expressed as a weight percentage, is composed of the following raw materials:

[0105] The composition includes 32% raw magnesium olivine (15-8mm), 12% recycled magnesium aluminum spinel (5-3mm), 15% recycled magnesium aluminum spinel (3-1mm), 16% 97% high-purity magnesia (1-0mm), 12% 95% medium-grade magnesia (180-mesh), 6% lightly calcined magnesia powder (1000-mesh), 4% silicon carbide (<240-mesh), 3% silica fume (<2μm), and 0.15% of the total weight of the above raw materials, along with high-efficiency water-reducing dispersant Monoled 380s, 0.02% sodium citrate, and 0.06% explosion-proof fiber.

[0106] The refractory material for the slag-blocking weir in the intermediate ladle is prepared by the following method, and the specific operating steps are as follows:

[0107] (1) Weigh out all raw materials according to the above proportions;

[0108] (2) The 180-mesh 95 medium-grade magnesia, 1000-mesh lightly calcined magnesia powder, <240-mesh silicon carbide and <2μm silica fume weighed in step (1), as well as the high-efficiency water-reducing dispersant Monoladd 380s and sodium citrate are premixed.

[0109] (3) The 15-8mm raw magnesium olivine, 5-3mm and 3-1mm recycled magnesium aluminum spinel, 1-0mm 97 high-purity magnesium sand and explosion-proof fiber weighed in step (1) are added to the fine powder premixed in step (2) and mixed and ground.

[0110] (4) Add a certain amount of water to the fine powder and granules mixed in step (3), stir evenly, and then put them into a mold and vibrate to form.

[0111] In Comparative Example 3, the water content was 4.0%, which included 1-0 mm 97 sintered magnesia and 180 mesh 95 medium-grade magnesia. Hydration occurred, and fine cracks were found after treatment at 110℃ for 24 hours.

[0112] Comparative Example 4

[0113] A type of slag-retaining weir castable for intermediate ladles, expressed as a weight percentage, is composed of the following raw materials:

[0114] The composition includes 32% raw magnesium olivine (15-8mm), 12% recycled magnesium aluminum spinel (5-3mm), 15% recycled magnesium aluminum spinel (3-1mm), 16% fused magnesia (1-0mm), 12% fused magnesia (180 mesh), 4% lightly calcined magnesium oxide powder (1000 mesh), 2% magnesium binder (DMG75), 4% silicon carbide (<240 mesh), 3% silica fume (<2μm), and 0.15% high-efficiency water-reducing dispersant Monoled 380s, 0.02% sodium citrate, and 0.06% explosion-proof fiber.

[0115] The refractory material for the slag-blocking weir in the intermediate ladle is prepared by the following method, and the specific operating steps are as follows:

[0116] (1) Weigh out all raw materials according to the above proportions;

[0117] (2) The 180-mesh fused medium-grade magnesia, 1000-mesh lightly calcined magnesia powder, magnesia binder (DMG 75), <240-mesh silicon carbide and <2μm silica fume, as well as the high-efficiency water-reducing dispersant Monoled 380s and sodium citrate weighed in step (1) are premixed.

[0118] (3) The 15-8mm raw magnesium olivine, 5-3mm and 3-1mm recycled magnesium aluminum spinel, 1-0mm fused magnesia, and explosion-proof fiber weighed in step (1) are added to the fine powder premixed in step (2) and mixed and ground.

[0119] (4) Add a certain amount of water to the fine powder and granules mixed in step (3), stir evenly, and then put them into a mold and vibrate to form.

[0120] In Comparative Example 4, the water content was 4.0%, and magnesium binder DMG75 was added, which may contain MgCl2 components. The slag weir castable dried slowly, and the initial setting time was >2 hours.

[0121] Comparative Example 5

[0122] A type of slag-retaining weir castable for intermediate ladles, expressed as a weight percentage, is composed of the following raw materials:

[0123] The composition includes 33% raw magnesium olivine (15-8mm), 10% recycled magnesium aluminum spinel (5-3mm), 17% recycled magnesium aluminum spinel (3-1mm), 14% fused magnesia (1-0mm), 14% fused magnesia (180 mesh), 5% lightly calcined magnesium oxide powder (1000 mesh), 3% silicon carbide (<240 mesh), 4% silica fume (<2μm), and 0.1% of the total weight of the above raw materials as a high-efficiency water-reducing dispersant Monoled 380s and 0.06% of explosion-proof fiber.

[0124] The refractory material for the slag-blocking weir in the intermediate ladle is prepared by the following method, and the specific operating steps are as follows:

[0125] (1) Weigh out all raw materials according to the above proportions for the slag weir;

[0126] (2) The 180-mesh fused magnesia, 1000-mesh lightly calcined magnesia powder, <240-mesh silicon carbide and <2μm silica fume weighed in step (1) are premixed with the high-efficiency water-reducing dispersant Monoladd 380s.

[0127] (3) The 15-8mm raw magnesium olivine, 5-3mm and 3-1mm recycled magnesium aluminum spinel, 1-0mm fused magnesia, and explosion-proof fiber weighed in step (1) are added to the fine powder premixed in step (2) and mixed and ground.

[0128] (4) Add a certain amount of water to the fine powder and granules mixed in step (3), stir evenly, and then put them into a mold and vibrate to form.

[0129] In Comparative Example 5, the water content was 4.2%, and no retarder was added to the slag weir castable. It dried quickly, had poor fluidity, and had an initial setting time of less than 20 minutes.

[0130] Comparative Example 6

[0131] A type of slag-retaining weir castable for intermediate ladles, expressed as a weight percentage, is composed of the following raw materials:

[0132] The composition includes 34% raw magnesium olivine (15-8mm), 8% recycled magnesium aluminum spinel (5-3mm), 20% recycled magnesium aluminum spinel (3-1mm), 12% fused magnesia (1-0mm), 19% fused magnesia (180 mesh), 2% silicon carbide (<240 mesh), 5% silica fume (<2μm), and 0.1% high-efficiency water-reducing dispersant Monoled 380s, 0.01% sodium gluconate, 0.01% sodium citrate, and 0.08% explosion-proof fiber, accounting for 0.1% of the total weight of the above raw materials.

[0133] The refractory material for the slag-blocking weir in the intermediate ladle is prepared by the following method, and the specific operating steps are as follows:

[0134] (1) Weigh out all raw materials according to the above proportions;

[0135] (2) The 180-mesh fused magnesia, <240-mesh silicon carbide and <2μm silica fume weighed in step (1), as well as the high-efficiency water-reducing dispersant Monoladd 380s, sodium gluconate and sodium citrate are premixed.

[0136] (3) The 15-8mm raw magnesium olivine, 5-3mm and 3-1mm recycled magnesium aluminum spinel and 1-0mm fused magnesia, as well as the explosion-proof fiber, weighed in step (1) are added to the fine powder premixed in step (2) and mixed and ground.

[0137] (4) Add a certain amount of water to the fine powder and granules mixed in step (3), stir evenly, and then put them into a mold and vibrate to form.

[0138] In Comparative Example 6, the water content was 4.1%, and the concrete cracked during demolding. The slag weir castable did not contain lightly calcined magnesium oxide powder, and its compressive strength at 50℃ for 24 hours was <15MPa, which was significantly lower than the demolding strength of 27.8MPa in Example 4.

[0139] The above description is merely an example and illustration of the concept of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the concept of the invention or exceed the scope defined in the claims, they should all fall within the protection scope of the present invention.

Claims

1. A slag dam for a tundish, characterized by comprising: The intermediate ladle dam includes the following components by weight percentage: Particle size 15-8mm raw forsterite 30-38%, Particle size 5-3mm regenerated magnesium-aluminum spinel 5-15%, Particle size 3-1mm regenerated magnesium-aluminum spinel 10-25%, Particle size 1-0mm fused magnesite 10-20%, Particle size 180 mesh fused magnesite 10-20%, Particle size 1000 mesh light-burned magnesium oxide powder 2-8%, Particle size <240 mesh silicon carbide 1-5%, Particle size <2 μm silica fume 2-6%; and 0.1%-0.15% of dispersant, 0.01%-0.02% of retarder and 0.06%-0.08% of explosion-proof fiber in total weight of the above raw materials; The dispersant is high-efficiency water-reducing dispersant Monoladd 380s.

2. The slag dam according to claim 1, characterized in that The mass percentage of MgO in the raw forsterite is ≥45%.

3. The slag dam according to claim 1, wherein The regenerated magnesium-aluminum spinel is obtained from the periclase-magnesia spinel brick for RH refining furnace recovered from steel plant by crushing, slag removal, iron removal, hydration and shaping processes, and the mass percentage of MgO in the regenerated magnesium-aluminum spinel is ≥85%, and the mass percentage of MgO and Al2O3 is ≥93%.

4. The slag dam according to claim 1, wherein The mass percentage of MgO in the fused magnesite is ≥97%, the mass percentage of MgO in the light-burned magnesium oxide powder is ≥92%, the mass percentage of SiC in the silicon carbide is ≥95%, and the mass percentage of SiO2 in the silica fume is ≥95%.

5. The weir for a tundish according to claim 1, wherein The retarder is one or mixture of two of sodium citrate and sodium gluconate.

6. The slag dam according to claim 1, wherein The diameter of the explosion-proof fiber is 40 μm, and the length is 2-3 mm.

7. A method of manufacturing a slag dam for a tundish according to any one of claims 1 to 6, characterized in that, The method comprises the following steps: (1) weighing various raw materials according to the proportion of the intermediate ladle dam; (2) pre-mixing the fused magnesite of 180 mesh, light-burned magnesium oxide powder of 1000 mesh, silicon carbide of <240 mesh and silica fume of <2 μm, dispersant and retarder weighed in step (1) for 15-20 min; (3) adding the raw forsterite of 15-8 mm, regenerated magnesium-aluminum spinel of 5-3 mm and 3-1 mm, fused magnesite of 1-0 mm and explosion-proof fiber weighed in step (1) into the fine powder pre-mixed in step (2) and mixing for 2-3 min; (4) adding water accounting for 3.9%-4.1% of the total mass of the mixture in step (3) and stirring for 3-4 min; (5) putting the mixture stirred uniformly in step (4) into a mold for vibration forming to discharge air bubbles and using a vibration rod for auxiliary forming until the mixture is fully vibrated; (6) after the forming, putting the precast piece and the mold together into a wet curing kiln with a temperature of 45-48 ℃ and humidity of 50-60 RH for 12-14 h, and then demolding; (7) after demolding, putting the precast piece into a dry curing kiln with a temperature of 50-60 ℃ for 24-36 h, and then sending it into a baking kiln to heat to 240-260 ℃, and baking for 24-36 h, to obtain the intermediate ladle dam.

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