A low-aluminum refined ladle brick and its preparation method

Abstract

The present application relates to the technical field of ladle bricks, and specifically discloses a low-aluminum refined ladle brick and its preparation method, which is prepared by mixing the following raw materials in parts by mass: 10-15 parts of fused magnesia with a particle size of ≤0.088mm, 30-40 parts of fused magnesia with a particle size of 1-3mm, 20-25 parts of fused magnesia with a particle size of 3-5mm, 5-8 parts of a composite binder, 2-3 parts of white clay, and 0.5-1 parts of carbon black. The preparation steps include the following: taking fused magnesia, white clay, carbon black, and a composite binder, mixing and homogenizing, then molding and heat-treating, and placing at 45-55°C overnight to obtain the brick; wherein the composite binder is spray-granulated by mixing a mixed powder of aluminum silicon carbide with asphalt powder to obtain mixed microspheres, which are then wetted and then mixed with pretreated silicon carbide fibers to form balls, and finally returned to the furnace for cooling. The composite binder prepared by the present application can improve the oxidation resistance of the brick and inhibit the formation of microcracks.

Description

Technical Field

[0001] The present application relates to the technical field of ladle bricks, and more specifically, to a low-aluminum refined ladle brick and a preparation method thereof. Background Art

[0002] Ladle bricks are a key refractory material used in the ladle lining during steelmaking, primarily for containing and transporting high-temperature molten steel. They must possess excellent resistance to high temperatures, thermal shock, and slag erosion to ensure molten steel purity and extend the life of the ladle material. Compared to traditional refractory materials, ladle bricks offer greater stability at high temperatures, effectively reducing molten steel contamination and improving smelting efficiency.

[0003] Ladle bricks are typically made from high-purity magnesia and alumina-magnesia spinel, and are produced through a process of batching, mixing, high-pressure forming, and high-temperature sintering. To further optimize the oxidation resistance of ladle bricks, antioxidants are added to the formula. Common metal antioxidants include aluminum powder and aluminum alloys. However, due to the high-temperature environment of molten steel processing, the antioxidant effects of these antioxidants are relatively limited, often requiring a high-quality blend to meet the ladle brick's antioxidant requirements.

[0004] The Chinese patent application document with application publication number CN106187225A discloses a corrosion-resistant magnesia-carbon brick and its preparation method. The scheme uses a ceramic particle carbon silicon aluminum (Al4SiC4) with a low formula ratio, combined with basalt particles, nano-zirconium boride and other components, which can improve the brick's oxidation resistance and slag resistance, realize the introduction of low aluminum components while enhancing the use effect of the brick.

[0005] In the above document, the ceramic particles carbon silicide are used in combination with other components. Although it can improve the oxidation resistance and slag resistance of the brick, the carbon silicide will decompose to form a mullite structure during use, resulting in volume expansion. Therefore, the solution needs to add reinforcing components to keep the brick from cracking. That is, the interaction between the components is not close, and it is difficult to achieve a synergistic effect. Therefore, it is necessary to find a low-aluminum refined ladle brick that can improve the oxidation resistance of the ladle brick and reduce the risk of microcracks in the brick. Summary of the Invention

[0006] In order to further improve the oxidation resistance of ladle bricks and reduce the risk of microcracks in the brick body, the present application provides a low-aluminum refined ladle brick and a preparation method thereof.

[0007] In a first aspect, the present application provides a method for preparing low-aluminum refined ladle bricks, which adopts the following technical solution:

[0008] A method for preparing a low-aluminum refined ladle brick is provided, wherein the brick is prepared by mixing the following raw materials in parts by weight: 10-15 parts of fused magnesia with a particle size of ≤0.088 mm, 30-40 parts of fused magnesia with a particle size of 1-3 mm, 20-25 parts of fused magnesia with a particle size of 3-5 mm, 5-8 parts of a composite binder, 2-3 parts of white clay, and 0.5-1 part of carbon black. The preparation steps include the following:

[0009] Take fused magnesia, white clay, carbon black and composite binder, mix and homogenize, then mold and heat treat, and place at 45-55℃ overnight to obtain the product;

[0010] The composite binder is prepared by spraying and granulating a mixture of aluminum carbide mixed powder and asphalt powder to obtain mixed microspheres, which are then wetted and then mixed with pre-treated silicon carbide fibers to form balls, which are then returned to the furnace for cooling.

[0011] The molding pressure condition is 250-275MPa;

[0012] The heat treatment is: treating at 200-225° C. for 10-12 hours.

[0013] By adopting the above technical solution, the composite binder acts as a bonding agent during the ladle brick preparation process and decomposes in the operating environment to produce a residual carbon-enriched mass, thereby improving the overall oxidation resistance of the ladle brick. The composite binder is obtained by combining pretreated silicon carbide fibers and mixed microspheres prepared by spray granulation of carbon-silicon-aluminum mixed powder and asphalt powder. The pretreated silicon carbide fibers disperse the stress generated by the pyrolysis of the mixed microspheres through shear and deflection, avoiding stress concentration problems, and enhance the support effect of the residual carbon-enriched mass by interacting with the alumina generated by the pyrolysis of carbon-silicon-aluminum mixed powder. Before the pyrolysis of the asphalt powder in the mixed microspheres begins, it first melts into a viscous flow state, at which point it can penetrate and wrap around the outer layer of pretreated silicon carbide fibers, strengthening the combined effect between the components. When the asphalt powder pyrolyzes, the fine particles in the carbon-silicon-aluminum mixed powder can mix into the asphalt pyrolysis products, participating in the formation of a pyrolysis skeleton and improving the structural stability of the residual carbon-enriched mass. The coarse particles combine with the pretreated silicon carbide fibers to further strengthen the combined effect.

[0014] Preferably, the preparation steps of the aluminum silicide carbon mixed powder include: mixing silicon dioxide, carbon powder, aluminum powder and a crystal promoter, adding anhydrous ethanol, stirring, molding and then calcining to obtain a solid product, passing it through a 200-mesh sieve, grading and then mixing to obtain the aluminum silicide carbon mixed powder;

[0015] The crystal-growing agent is activated alumina with an average particle size of 10-20 microns;

[0016] The mass ratio of the silicon dioxide, carbon powder, aluminum powder and crystal-promoting agent is (1.2-1.3): (5.5-5.8): (4.3-4.4): (0.01-0.03).

[0017] Preferably, the thermal calcination treatment includes a first stage thermal calcination and a second stage thermal calcination in sequence, and the operation is as follows:

[0018] First stage of hot burning: argon gas is passed through, and then the tungsten wire is ignited;

[0019] Second stage calcination: Set the system pressure to 1.2-2.3GPa and the temperature to 1750-1835℃, and continue to treat the first stage calcination product at a constant temperature for 10-16 hours;

[0020] The classification is to grind the fine particles on the lower layer of the sieve and mix them with the residue on the upper layer.

[0021] By adopting the above technical solution, aluminum silicide is prepared by chemical self-propagation method combined with high-pressure thermal calcination treatment. The introduction of crystallization promoters in the components can promote the crystallization behavior of aluminum silicide. After graded treatment, the aluminum silicide can be mixed to adjust its particle size distribution and obtain coarse and fine particle sizes. Among them, fine-grained aluminum silicide can participate in the asphalt pyrolysis process, thereby strengthening the residual carbon skeleton, while the aluminum oxide formed on the surface of coarse-grained aluminum silicide during pyrolysis can react with the silica on the surface of pretreated silicon carbide fiber, promoting the interaction between the components. The reaction can be expressed as:

[0022]

[0023] Preferably, the mass ratio of the aluminum carbon silicide mixed powder to the asphalt powder is (4.5-7): (20-30);

[0024] The spray granulation spray pressure is 0.3-0.4MPa, and the drying temperature is 70-80°C;

[0025] The preparation steps of the spray granulation binder are as follows: sodium silicate and sodium dodecylbenzene sulfonate are taken, water and glycerin are added to disperse them, sodium citrate is added thereto, the mixture is stirred and the pH value is adjusted to obtain the binder.

[0026] Preferably, the wet treatment is to take the mixed microspheres, add them to the treatment solution, let them stand for 1-3 minutes, and then filter out the solid part;

[0027] The treatment liquid is obtained by mixing water, anhydrous ethanol and polyethylene glycol in a volume ratio of (3-5): (1-2):0.5.

[0028] By adopting the above technical solution, the wetting treatment can promote the formation of a temporary adhesion structure between the mixed microspheres and the subsequently pretreated silicon carbide fibers.

[0029] Preferably, the preparation step of the pretreated silicon carbide fiber comprises: placing the silicon carbide fiber in a muffle furnace, heating it and then keeping it warm, and then cooling it with the furnace;

[0030] The heat preservation operation after heating is as follows: adjusting the heating rate to 7.5-8°C / min to heat to 1200-1275°C, and then keeping the temperature for 2-3 hours.

[0031] By adopting the above technical solution, the silicon carbide fiber can be pretreated to obtain a silicon dioxide layer on its surface. During subsequent use, the silicon dioxide layer can react with the decomposition products of aluminum silicide to strengthen the composite structure and inhibit the formation of microcracks.

[0032] Preferably, the re-furnace cooling treatment is to transfer the ball product to a rotary kiln, set the speed to 25-35 rpm, the temperature to 85-90° C., discharge the material after treatment for 10-20 seconds, and cool with air for 1-2 minutes, and repeat the operation 2-3 times.

[0033] By adopting this technical solution, the combination of the hybrid microspheres and the pretreated silicon carbide fiber composite structure can be promoted. The asphalt powder softens in the hot environment and can penetrate the pretreated silicon carbide fiber wrapped in the outer layer, promoting the formation of a compact structure.

[0034] In the second aspect, the present application prepares low-aluminum refined ladle bricks through the above-mentioned preparation process.

[0035] In summary, this application has the following beneficial effects:

[0036] 1. This application uses a composite binder to enhance the oxidation and microcrack resistance of ladle bricks. During use, the composite binder decomposes to produce a residual carbon-rich mass that improves the overall oxidation resistance of the ladle bricks. The aluminum carbide used in the composite binder preparation undergoes a graded treatment, where the fine-grained fraction forms the asphalt pyrolysis skeleton, enhancing structural stability. The coarse-grained fraction combines with pretreated silicon carbide fibers to enhance the synergistic effect between the components.

[0037] 2. In this application, pretreated silicon carbide fibers are preferably used as a composite binder component to enhance the ladle brick's resistance to microcracks. Pretreatment of the silicon carbide fibers yields a silicon dioxide layer on their surface. In the thermal environment of subsequent use, the silicon dioxide layer reacts with the decomposition products of aluminum silicide, reinforcing the composite structure. Furthermore, the silicon dioxide layer disperses the stress generated by the pyrolysis of the mixed microspheres during pyrolysis of the composite binder component, avoiding stress concentration and ultimately improving the ladle brick's resistance to microcracks. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is the XRD diffraction test pattern of carbon silicide aluminum mixed powder prepared in Example 1 of this application.

[0039] Figure 2 These are the oxidation resistance test results of low-aluminum refined ladle bricks of Examples 1-4 and Comparative Examples 1-3 of the present application.

[0040] Figure 3These are SEM scans of the cross-section of the low-aluminum refined ladle bricks after heat treatment in Comparative Example 1 and Example 2 of this application. DETAILED DESCRIPTION

[0041] The technical solution of the present invention is explained in detail below with reference to several representative embodiments of the present invention.

[0042] Unless otherwise specified, the experimental methods used in the following examples are all conventional methods. Unless otherwise specified, the materials, reagents, etc. used in the following examples are all commercially available.

[0043] Description of the raw materials used in the examples and comparative examples of the present invention:

[0044] White clay, particle size ≤ 5 microns, alumina content ≤ 20%;

[0045] Silicon dioxide, particle size ≤ 100 μm;

[0046] Carbon powder, particle size ≤75nm;

[0047] Aluminum powder, particle size 20-30 microns, purity ≥99%;

[0048] Activated alumina, specific surface area ≥ 280m 2 / g, particle size 10-20 microns;

[0049] Asphalt powder, particle size ≤ 2mm, ash content ≥ 15%;

[0050] Silicon carbide fiber, aspect ratio ≥ 50;

[0051] The chemical composition of fused magnesia is shown in Table 1.

[0052] Table 1 Chemical composition of fused magnesia

[0053]

[0054] Preparation Example 1

[0055] Take 120g of silica, 550g of carbon powder, 430g of aluminum powder and 1g of activated alumina, add 50ml of anhydrous ethanol, mix and stir for 10min, then use a molding machine to set the pressure to 35MPa, and mold it into mixed microspheres with Φ=35mm. Then place the mixed microspheres in a chemical furnace, exhaust the gas with argon, and then ignite them with tungsten wire. After stabilization, transfer the sintered material to a high-pressure reactor, set the system pressure to 1.2GPa, the temperature to 1750℃, and continue to treat at a constant temperature for 10h to obtain a solid product. Grind it for 1min and then pass it through a 200-mesh sieve. The lower layer of fine-grained product is further ground using a disc airflow mill for 10min, and then mixed with the upper sieve residue to obtain a carbon silicide aluminum mixed powder.

[0056] Take 10g of sodium silicate and 0.5g of sodium dodecylbenzenesulfonate, add 100ml of deionized water and 50ml of glycerol to disperse, then add 0.1g of sodium citrate to the system, adjust the magnetic stirring speed to 300rpm, treat for 1min, and then use 20% mass concentration of sodium hydroxide solution to adjust the pH of the system to 10 to obtain a sodium silicate mixed solution.

[0057] 200 g of asphalt powder was mixed with 45 g of aluminum carbon silicide mixed powder and placed in a spray granulator. Sodium silicate mixed solution was used as the spray binder. The spray pressure was set to 0.3 MPa and the drying temperature was set to 70°C to obtain mixed microspheres.

[0058] 10 g of silicon carbide fiber was placed in a muffle furnace, and the temperature was raised to 1200° C. at a heating rate of 7.5° C. / min, followed by keeping the temperature for 2 h. The heating was stopped and the pretreated silicon carbide fiber was obtained after cooling with the furnace.

[0059] Preparation Example 2

[0060] Take 125g of silica, 560g of carbon powder, 430g of aluminum powder and 2g of activated alumina, add 50ml of anhydrous ethanol, mix and stir for 10 minutes, then use a molding machine to set the pressure to 36MPa, and mold it into mixed microspheres with a diameter of Φ=35mm. Then place the mixed microspheres in a chemical furnace, exhaust the gas with argon, and then ignite them with tungsten wire. After stabilization, transfer the sintered material to a high-pressure reactor, set the system pressure to 1.8GPa, the temperature to 1800℃, and continue to treat at a constant temperature for 12h to obtain a solid product. Grind it for 2min and pass it through a 200-mesh sieve. The lower layer of fine-grained product is further ground for 15min using a disc airflow mill, and then mixed with the upper sieve residue to obtain a carbon silicide aluminum mixed powder.

[0061] Take 12g of sodium silicate and 0.5g of sodium dodecylbenzenesulfonate, add 120ml of deionized water and 50ml of glycerol to disperse, then add 0.2g of sodium citrate to the system, adjust the magnetic stirring speed to 300rpm, treat for 3min, and then use 20% mass concentration of sodium hydroxide solution to adjust the pH of the system to 11 to obtain a sodium silicate mixed solution.

[0062] 250g of asphalt powder was mixed with 60g of aluminum carbon silicide mixed powder and placed in a spray granulator. Sodium silicate mixed solution was used as the spray binder. The spray pressure was set to 0.3MPa and the drying temperature was set to 75°C to obtain mixed microspheres.

[0063] Take 10g of silicon carbide fiber, place it in a muffle furnace, adjust the heating rate to 7.5℃ / min and heat it to 1200℃, then keep it warm for 3h, stop heating and cool it with the furnace to obtain pretreated silicon carbide fiber.

[0064] Preparation Example 3

[0065] Take 130g of silica, 580g of carbon powder, 440g of aluminum powder and 3g of activated alumina, add 50ml of anhydrous ethanol, mix and stir for 10min, then use a molding machine to set the pressure to 37MPa, and mold it into mixed microspheres with Φ=36mm. Then place the mixed microspheres in a chemical furnace, exhaust the gas with argon, and then ignite them with tungsten wire. After stabilization, transfer the sintered material to a high-pressure reactor, set the system pressure to 2.3GPa, the temperature to 1835℃, and continue to treat at a constant temperature for 16h to obtain a solid product. Grind it for 3min and pass it through a 200-mesh sieve. The lower layer of fine-grained product is further ground using a disc airflow mill for 30min, and then mixed with the upper sieve residue to obtain a carbon silicide aluminum mixed powder.

[0066] Take 20g of sodium silicate and 1g of sodium dodecylbenzenesulfonate, add 150ml of deionized water and 100ml of glycerol to disperse, then add 0.3g of sodium citrate to the system, adjust the magnetic stirring speed to 300rpm, treat for 5min, and then use 20% mass concentration of sodium hydroxide solution to adjust the pH of the system to 12 to obtain a sodium silicate mixed solution.

[0067] 300 g of asphalt powder was mixed with 70 g of aluminum carbon silicide mixed powder and placed in a spray granulator. Sodium silicate mixed solution was used as the spray binder. The spray pressure was set to 0.4 MPa and the drying temperature was 80°C to obtain mixed microspheres.

[0068] Take 10g of silicon carbide fiber, place it in a muffle furnace, adjust the heating rate to 8℃ / min and heat it to 1275℃, then keep it warm for 3h, stop heating and cool it in the furnace to obtain pretreated silicon carbide fiber.

[0069] Preparation Example 4

[0070] The only difference between this preparation example and Preparation Example 1 is that the preparation steps of pre-treated silicon carbide fiber are as follows:

[0071] Take 10g of silicon carbide fiber, place it in a muffle furnace, adjust the heating rate to 7.8℃ / min and heat it to 1250℃, then keep it warm for 3h, stop heating and cool it with the furnace to obtain pretreated silicon carbide fiber.

[0072] The remaining steps are the same as those in Preparation Example 1.

[0073] Example 1

[0074] In this embodiment, the preparation steps of low-aluminum refined ladle bricks are as follows:

[0075] Take 1000g of fused magnesia with a particle size of ≤0.088mm, 3000g of fused magnesia with a particle size of 1-3mm, and 2000g of fused magnesia with a particle size of 3-5mm, mix them with 200g of white clay, 50g of carbon black and 500g of composite binder, place them in a wheel mill for processing for 20min, then seal and homogenize for 2d, and then use a molding machine to set the pressure to 250MPa and press them into 100mm×55mm×28mm samples, then heat treat them at 200℃ for 10h, and then place them at 45℃ overnight to obtain low-aluminum refined steel-clad bricks.

[0076] In this embodiment, the steps for preparing the composite adhesive are as follows:

[0077] Take 100g of mixed microspheres, add them to 200ml of treatment liquid and let them stand for 1 minute, then filter the solid part and place it in a ball rolling machine, then add 20g of pretreated silicon carbide fiber and treat for 5 minutes, then transfer it to an 85℃ rotary kiln, set the speed to 25rpm, and after treating for 10s, discharge the material, blow cool for 1min, then repeat the kiln and cooling twice, and place it at room temperature.

[0078] In this embodiment, the mixed microspheres and pretreated silicon carbide fibers are prepared by Preparation Example 1.

[0079] The treatment liquid is prepared by mixing deionized water, anhydrous ethanol and polyethylene glycol in a volume ratio of 3:1:0.5.

[0080] Example 2

[0081] In this embodiment, the preparation steps of low-aluminum refined ladle bricks are as follows:

[0082] Take 1200g of fused magnesia with a particle size of ≤0.088mm, 3500g of fused magnesia with a particle size of 1-3mm, and 2200g of fused magnesia with a particle size of 3-5mm, mix them with 250g of white clay, 50g of carbon black and 600g of composite binder, place them in a wheel mill for processing for 20min, then seal and homogenize for 2d, and then use a molding machine to set the pressure to 250MPa and press them into 100mm×55mm×28mm samples, then heat treat them at 200℃ for 12h, and then place them at 45℃ overnight to obtain low-aluminum refined steel-clad bricks.

[0083] In this embodiment, the steps for preparing the composite adhesive are as follows:

[0084] Take 100g of mixed microspheres, add them to 200ml of treatment liquid and let them stand for 2 minutes, then filter the solid part and place it in a ball rolling machine, then add 20g of pretreated silicon carbide fiber and treat it for 10 minutes, then transfer it to an 85℃ rotary kiln, set the speed to 25rpm, and after treating for 15s, discharge the material, blow cool for 1min, then repeat the kiln and cooling twice, and place it at room temperature.

[0085] In this embodiment, the mixed microspheres and pretreated silicon carbide fibers are prepared by Preparation Example 2.

[0086] The treatment liquid is prepared by mixing deionized water, anhydrous ethanol and polyethylene glycol in a volume ratio of 4:1:0.5.

[0087] Example 3

[0088] In this embodiment, the preparation steps of low-aluminum refined ladle bricks are as follows:

[0089] Take 1300g of fused magnesia with a particle size of ≤0.088mm, 3600g of fused magnesia with a particle size of 1-3mm, 2400g of fused magnesia with a particle size of 3-5mm, mix them with 250g of white clay, 60g of carbon black and 750g of composite binder, place them in a wheel mill for processing for 20min, then seal and homogenize for 3d, and then use a molding machine to set the pressure to 275MPa and press them into 100mm×55mm×28mm samples, then heat treat them at 225℃ for 12h, and then place them at 50℃ overnight to obtain low-aluminum refined steel-clad bricks.

[0090] In this embodiment, the steps for preparing the composite adhesive are as follows:

[0091] Take 100g of mixed microspheres, add them to 200ml of treatment liquid and let them stand for 2 minutes, then filter the solid part and place it in a ball rolling machine, then add 20g of pretreated silicon carbide fiber and treat it for 20 minutes, then transfer it to a 90℃ rotary kiln, set the speed to 35rpm, and after treating for 20s, discharge the material, blow cool for 2min, then repeat the kiln and cooling three times, and place it at room temperature.

[0092] In this embodiment, the mixed microspheres and pretreated silicon carbide fibers are prepared by Preparation Example 3.

[0093] The treatment liquid is prepared by mixing deionized water, anhydrous ethanol and polyethylene glycol in a volume ratio of 5:1.5:0.5.

[0094] Example 4

[0095] In this embodiment, the preparation steps of low-aluminum refined ladle bricks are as follows:

[0096] Take 1500g of fused magnesia with a particle size of ≤0.088mm, 4000g of fused magnesia with a particle size of 1-3mm, 2500g of fused magnesia with a particle size of 3-5mm, mix them with 300g of white clay, 100g of carbon black and 800g of composite binder, place them in a wheel mill for processing for 20min, then seal and homogenize for 3d, and then use a molding machine to set the pressure to 275MPa and press them into 100mm×55mm×28mm samples, then heat treat them at 225℃ for 12h, and then place them at 50℃ overnight to obtain low-aluminum refined steel-clad bricks.

[0097] In this embodiment, the steps for preparing the composite adhesive are as follows:

[0098] Take 100g of mixed microspheres, add them to 200ml of treatment liquid and let them stand for 3 minutes, then filter the solid part and place it in a ball rolling machine, then add 20g of pretreated silicon carbide fiber and treat it for 20 minutes, then transfer it to a 90℃ rotary kiln, set the speed to 35rpm, and after treating for 20s, discharge the material, blow cool for 2min, then repeat the kiln and cooling three times, and place it at room temperature.

[0099] In this embodiment, the mixed microspheres and pretreated silicon carbide fibers are prepared by Preparation Example 4.

[0100] The treatment liquid is prepared by mixing deionized water, anhydrous ethanol and polyethylene glycol in a volume ratio of 5:2:0.5.

[0101] Comparative Example 1

[0102] The only difference between this comparative example and Example 1 is that the preparation steps of the composite adhesive are as follows:

[0103] 25 g of aluminum carbide mixed powder, 75 g of asphalt powder and 20 g of pretreated silicon carbide fiber were mixed to obtain a composite adhesive.

[0104] The remaining steps are the same as those in Example 1.

[0105] Comparative Example 2

[0106] The difference between this comparative example and Example 1 is that, in the preparation process of the composite binder, the preparation steps of the mixed microspheres used are as follows:

[0107] Take 120g of silica, 550g of carbon powder, 430g of aluminum powder and 1g of activated alumina, add 50ml of anhydrous ethanol, mix and stir for 10 minutes, then use a molding machine to set the pressure to 35MPa, and mold it into mixed microspheres with a diameter of Φ=35mm. Then, place the mixed microspheres in a chemical furnace, exhaust the gas with argon, and ignite them with tungsten wire. After stabilization, transfer the sintered material to a high-pressure reactor, set the system pressure to 1.2GPa, the temperature to 1750℃, and continue to treat at a constant temperature for 10 hours to obtain a solid product. After grinding for 1 minute, a carbon silicide aluminum mixed powder is obtained.

[0108] The remaining steps are the same as those in Example 1.

[0109] Comparative Example 3

[0110] The difference between this comparative example and Example 1 is that an equal amount of glass fiber is used instead of pretreated silicon carbide fiber to prepare the composite adhesive.

[0111] The remaining steps are the same as those in Example 1.

[0112] Among them, the glass fiber (model: T912) is provided by Taishan Glass Fiber Co., Ltd.

[0113] Performance testing

[0114] XRD test

[0115] Take the carbon silicide aluminum mixed powder of Preparation Example 1 and perform XRD diffraction test. The results are as follows: Figure 1 shown.

[0116] Antioxidant test

[0117] With reference to the GB / T17732-2023 test method, the oxidation resistance test was conducted on the low-aluminum refined steel ladle bricks of Examples 1-4 and Comparative Examples 1-3. The temperature was raised to 1000°C at a heating rate of 8.5°C / min, and then continued to rise to 1475°C at a heating rate of 4°C / min, and then kept constant at this temperature for 2 hours. During this process, air was introduced into the test furnace at a flow rate of 4L / min. After the test, the thickness of the decarburized layer on the cross section of each group of low-aluminum refined steel ladle bricks was measured. The average value of 3 points in each group was taken as the final data. The test results are shown in the figure below. Figure 2 shown.

[0118] Analyze Examples 1-4 and Comparative Examples 1-3 and combine Figure 2 It can be seen that after the oxidation resistance test of the embodiment test group, the thickness of the decarburized layer formed is slightly lower than that of the comparative example, indicating that the embodiment has better ability to resist the external oxidizing environment; in the comparative example 1, since only the composite binder components are mechanically blended, the components are redispersed during the preparation of the ladle brick, resulting in a weak synergistic antioxidant effect between the components, and the decarburized layer thickness obtained after the oxidation resistance test is the highest; comparative examples 2 and 3 lack treatment processes or changes in fiber materials, which also lead to reduced oxidation resistance of the ladle brick products; among all test groups, the decarburized layer thickness formed on the ladle brick after the oxidation resistance test of embodiment 2 is the lowest.

[0119] SEM testing

[0120] Take the low aluminum refined ladle bricks of Example 2 and Comparative Example 1, place them in a test furnace, and heat treat them at 1200℃ for 1 hour. Then take the cross sections and perform SEM scanning tests. The test results are as follows: Figure 3 shown.

[0121] Analyze Example 2 and Comparative Example 1 and combine Figure 3 It can be seen that after heat treatment, the comparative example 1 ( Figure 3 Left) The brick body has obvious micro-cracks concentrated area, while Example 2 ( Figure 3The cross section (right) is relatively complete, indicating that when the components of the composite binder are effectively combined, the ability of the ladle brick to resist microcracks can be enhanced. However, when the components are not well combined, the ability of the ladle brick to resist microcracks is greatly reduced.

[0122] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A method for preparing low-aluminum refined ladle bricks, characterized in that: The invention is prepared by mixing the following raw materials in parts by mass: 10-15 parts of fused magnesia with a particle size of ≤0.088 mm, 30-40 parts of fused magnesia with a particle size of 1-3 mm, 20-25 parts of fused magnesia with a particle size of 3-5 mm, 5-8 parts of a composite binder, 2-3 parts of white clay, and 0.5-1 part of carbon black. The preparation steps include the following: Take fused magnesia, white clay, carbon black and composite binder, mix and homogenize, then mold and heat treat, and place at 45-55℃ overnight to obtain the product; The composite binder is prepared by spraying and granulating a mixture of aluminum carbide mixed powder and asphalt powder to obtain mixed microspheres, which are then wetted and then mixed with pretreated silicon carbide fibers to form rolling balls, which are then returned to the furnace for cooling.

2. The method for preparing a low-aluminum refined ladle brick according to claim 1, characterized in that: The molding pressure condition is 250-275MPa; The heat treatment is: treating at 200-225° C. for 10-12 hours.

3. The method for preparing a low-aluminum refined ladle brick according to claim 1, characterized in that: The preparation steps of the aluminum silicide carbon mixed powder include: mixing silicon dioxide, carbon powder, aluminum powder and a crystal promoter, adding anhydrous ethanol, stirring, molding and then calcining to obtain a solid product, passing it through a 200-mesh sieve, grading it, and then mixing it to obtain the aluminum silicide carbon mixed powder; The crystal-growing agent is activated alumina with an average particle size of 10-20 microns; The mass ratio of the silicon dioxide, carbon powder, aluminum powder and crystal-growing agent is (1.2-1.3): (5.5-5.8): (4.3-4.4): (0.01-0.03); The classification is to grind the fine particles on the lower layer of the sieve and mix them with the residue on the upper layer.

4. The method for preparing a low-aluminum refined ladle brick according to claim 3, characterized in that: The thermal calcination treatment includes a first stage thermal calcination and a second stage thermal calcination in sequence, and the operation is as follows: First stage of hot burning: argon gas is passed through, and then the tungsten wire is ignited; Second stage calcination: Set the system pressure to 1.2-2.3 GPa and the temperature to 1750-1835°C, and continue to treat the first stage calcination product at a constant temperature for 10-16 hours.

5. The method for preparing a low-aluminum refined ladle brick according to claim 1, characterized in that: The mass ratio of the aluminum carbon silicide mixed powder to the asphalt powder is (4.5-7): (20-30).

6. The method for preparing a low-aluminum refined ladle brick according to claim 1, characterized in that: The wet treatment is to take the mixed microspheres, add them into the treatment solution, let them stand for 1-3 minutes, and then filter out the solid part.

7. The method for preparing a low-aluminum refined ladle brick according to claim 6, characterized in that: The treatment liquid is obtained by mixing water, anhydrous ethanol and polyethylene glycol in a volume ratio of (3-5): (1-2):0.

5.

8. The method for preparing a low-aluminum refined ladle brick according to claim 1, characterized in that: The preparation steps of the pretreated silicon carbide fiber include: placing the silicon carbide fiber in a muffle furnace, heating it and then keeping it warm, and then cooling it with the furnace; The heat preservation operation after heating is as follows: adjusting the heating rate to 7.5-8°C / min to heat to 1200-1275°C, and then keeping the temperature for 2-3 hours.

9. The method for preparing a low-aluminum refined ladle brick according to claim 1, characterized in that: The re-furnace cooling treatment is to transfer the ball product to a rotary kiln, set the speed to 25-35 rpm, the temperature to 85-90° C., discharge the material after treating for 10-20 seconds, and cool with air for 1-2 minutes, and repeat the operation 2-3 times.

10. A low-aluminum refined ladle brick produced by the production method according to any one of claims 1 to 9.

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