Low-aluminum refined ladle brick and preparation method thereof

Abstract

The invention relates to the technical field of ladle bricks, and particularly discloses a low-aluminum refined ladle brick and a preparation method thereof.The low-aluminum refined ladle brick is prepared by mixing, by mass, 10-15 parts of fused magnesite with the particle size smaller than or equal to 0.088 mm, 30-40 parts of fused magnesite with the particle size ranging from 1 mm to 3 mm, 20-25 parts of fused magnesite with the particle size ranging from 3 mm to 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 method comprises the following steps: taking fused magnesite, white clay, carbon black and a composite binder, mixing, homogenizing, carrying out mold pressing and heat treatment, and standing overnight at 45-55 DEG C, thereby obtaining the product, wherein the composite binder is obtained by mixing aluminum carbon silicide mixed powder and asphalt powder, then performing spray granulation to obtain mixed microspheres, humidifying the mixed microspheres, then mixing the mixed microspheres with pretreated silicon carbide fibers, rolling the mixed microspheres, and finally performing remelting and cooling treatment. By using the composite binder prepared by the invention, the oxidation resistance of the brick body can be improved, and the generation of microcracks can be inhibited.

Description

Technical Field

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

[0002] Ladle bricks are key refractory materials for the ladle lining in the iron and steel smelting process, mainly used for containing and transporting high-temperature molten steel. They need to have excellent high-temperature resistance, thermal shock resistance, and slag erosion resistance to ensure the purity of molten steel and extend the service life of ladle materials. Compared with traditional refractory materials, ladle bricks have stronger stability at high temperatures, can effectively reduce molten steel pollution, and improve smelting efficiency.

[0003] Ladle bricks are usually made from high-purity magnesite, spinel, etc. as the main raw materials, through batching, mixing, high-pressure molding, and high-temperature sintering. To further optimize the antioxidant performance of ladle bricks, antioxidant components need to be added to the formula. Common metal antioxidants include aluminum powder, aluminum alloy, etc. However, due to the limitations of the high-temperature environment of steel treatment, the antioxidant effects of these antioxidants are relatively limited, and often a high-quality ratio needs to be used in the formula to meet the antioxidant requirements of ladle bricks.

[0004] The Chinese patent application document with the publication number CN106187225A discloses an erosion-resistant magnesia-carbon brick and a preparation method thereof. In the scheme, a ceramic particle aluminum carbon silicide (Al4SiC4) with a low formula ratio is used, combined with basalt particles, nano-zirconium boride and other components, which can improve the antioxidant and slag resistance of the brick body, and enhance the use effect of the brick body while introducing low-aluminum components.

[0005] In the above document, although the use of aluminum carbon silicide ceramic particles combined with other components can improve the antioxidant and slag resistance of the brick body, aluminum carbon silicide will decompose to form a mullite structure during use, resulting in volume expansion. Therefore, a reinforcing component needs to be added in the scheme to maintain the brick body from cracking, that is, the interaction between the components is not close enough to achieve a synergistic effect. Therefore, it is necessary to find a low-aluminum refined ladle brick that can improve the antioxidant ability of the ladle brick and at the same time reduce the risk of microcracks in the brick body. Summary of the Invention

[0006] In order to further improve the antioxidant ability of ladle bricks and at the same time reduce the risk of microcracks in the brick body, this application provides a low-aluminum refined ladle brick and a preparation method thereof.

[0007] In the first aspect, this application provides a preparation method of a low-aluminum refined ladle brick, adopting the following technical scheme: A preparation method of a low-aluminum refined ladle brick, which is prepared by mixing raw materials including the following parts by mass: 10-15 parts of fused magnesia with a particle size ≤ 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 are as follows: Take fused magnesia, white clay, carbon black, and composite binder, mix and homogenize them, then after molding and heat treatment, place them at 45-55 °C overnight to obtain; Among them, the composite binder is obtained by spray granulating the mixed powder of aluminum carbon silicide and asphalt powder, wetting the obtained mixed microspheres, then mixing and rolling balls with pretreated silicon carbide fibers, and finally obtaining after cooling in a reverberatory furnace; The pressure condition of the molding treatment is 250-275 MPa; The heat treatment is: treating at 200-225 °C for 10-12 h.

[0008] By adopting the above technical solution, the composite binder plays a role in bonding powder materials during the preparation of the ladle brick, and decomposes in the use environment to obtain a residual carbon aggregate to improve the overall antioxidant capacity of the ladle brick. The composite binder is obtained by combining pretreated silicon carbide fibers and mixed microspheres prepared by spray granulating the mixed powder of aluminum carbon silicide and asphalt powder; the pretreated silicon carbide fibers disperse the stress generated by the pyrolysis of the mixed microspheres through shearing and deflection actions, avoiding the problem of stress concentration, and enhancing the support effect of the residual carbon aggregate by acting with the alumina generated by the pyrolysis of aluminum carbon silicide; before the pyrolysis of the asphalt powder in the mixed microspheres, it first melts into a viscous flow state, at this time it can penetrate and wrap the outer layer of pretreated silicon carbide fibers, strengthening the combination effect between components; when the asphalt powder pyrolyzes, the fine particle part in the mixed powder of aluminum carbon silicide can be mixed into the asphalt pyrolysis product to participate in the formation of the pyrolysis skeleton, improving the structural stability of the residual carbon aggregate; while the coarse particle part combines with the pretreated silicon carbide fibers to further strengthen the combination effect.

[0009] Preferably, the preparation steps of the mixed powder of aluminum carbon silicide include: taking silicon dioxide, carbon powder, aluminum powder and a crystal growth promoter, adding absolute ethanol, stirring, molding by pressing and then heat burning, passing the obtained solid product through a 200-mesh sieve, classifying and then mixing to obtain the mixed powder of aluminum carbon silicide; The crystal growth promoter is activated alumina with an average particle size of 10-20 microns; The mass ratio of silicon dioxide, carbon powder, aluminum powder to the crystal growth promoter used is (1.2-1.3):(5.5-5.8):(4.3-4.4):(0.01-0.03).

[0010] Preferably, the heat burning treatment includes a first-stage heat burning and a second-stage heat burning in sequence, and the operation is as follows: One-stage thermal sintering: Argon is introduced, and then the tungsten wire is ignited. Two-stage thermal sintering: Set the system pressure to 1.2 - 2.3 GPa and the temperature to 1750 - 1835 °C, and continue to treat the one-stage thermal sintering product at a constant temperature for 10 - 16 h. The classification is as follows: Take the fine-grained product from the lower layer of the sieving, grind it, and mix it with the residue on the upper sieve.

[0011] By adopting the above technical solutions, aluminum silicon carbide is prepared here by the combination of chemical self-propagating high-temperature synthesis and high-pressure thermal sintering. Introducing a crystal growth promoter in the components can promote the crystallization behavior of aluminum silicon carbide. After the classification treatment and mixing of aluminum silicon carbide, its particle size distribution can be regulated, and two particle sizes, coarse and fine, can be obtained. Among them, the fine-grained aluminum silicon carbide can participate in the pyrolysis process of asphalt, thereby strengthening the carbon residue skeleton, while the aluminum oxide formed on the surface of the coarse-grained aluminum silicon carbide during pyrolysis can react with the silica on the surface of the pretreated silicon carbide fiber, promoting the interaction between the components. The reaction can be expressed as:

[0012] Preferably, the mass ratio of the mixed powder of aluminum silicon carbide to the asphalt powder used is (4.5 - 7):(20 - 30). The spray pressure for spray granulation is 0.3 - 0.4 MPa, and the drying temperature is 70 - 80 °C. The preparation steps of the binder for spray granulation are as follows: Take sodium silicate and sodium dodecylbenzenesulfonate, add water and glycerol for dispersion, then add sodium citrate, and adjust the pH after stirring to obtain it.

[0013] Preferably, the humidification treatment is as follows: Take the mixed microspheres, add them to the treatment solution, let them stand for 1 - 3 min, and then filter to obtain the solid part. The treatment solution is obtained by mixing water, absolute ethanol, and polyethylene glycol in a volume ratio of (3 - 5):(1 - 2):0.5.

[0014] By adopting the above technical solutions, the humidification treatment can promote the formation of a temporary adhesion structure between the mixed microspheres and the subsequent pretreated silicon carbide fibers.

[0015] Preferably, the preparation steps of the pretreated silicon carbide fibers include: Take the silicon carbide fibers and place them in a muffle furnace, heat them up and keep them at a constant temperature, and then cool them down with the furnace to obtain them. The operation of heating up and keeping at a constant temperature is as follows: Adjust the heating rate to 7.5 - 8 °C / min, heat up to 1200 - 1275 °C, and then keep it at a constant temperature for 2 - 3 h.

[0016] By adopting the above technical solutions, a layer of silica can be obtained on the surface of the silicon carbide fibers after the pretreatment. During the subsequent use process, the silica layer can react with the decomposition products of aluminum silicon carbide, strengthening the composite structure and inhibiting the formation of microcracks.

[0017] Preferably, the re-melting and cooling treatment is as follows: transfer the rolled ball product to a rotary furnace, set the rotation speed at 25 - 35 rpm, the temperature at 85 - 90 °C, export the material after 10 - 20 s of treatment, and cool it by blowing for 1 - 2 min. Repeat the operation 2 - 3 times.

[0018] By adopting the above technical solution, the combination of the mixed microspheres and the pre-treated silicon carbide fiber composite structure can be promoted. The asphalt powder softens under the thermal environment and can penetrate and wrap the outer layer of the pre-treated silicon carbide fibers, promoting the formation of a tight structure.

[0019] In the second aspect, the low-aluminum refined ladle brick is prepared by the above preparation process in this application.

[0020] In summary, this application has the following beneficial effects: 1. This application uses a composite binder to enhance the oxidation resistance and micro-crack resistance of the ladle brick. During use, the residual carbon aggregate obtained by the decomposition of the composite binder can improve the overall oxidation resistance of the ladle brick; the aluminum carbon silicide used in the preparation process of the composite binder, after being classified, the fine-grained part can participate in the formation of the asphalt pyrolysis skeleton to improve the structural stability, while the coarse-grained part combines with the pre-treated silicon carbide fibers to enhance the synergistic effect between components.

[0021] 2. In this application, pre-treated silicon carbide fibers are preferably used as components of the composite binder to enhance the micro-crack resistance of the ladle brick. After being pre-treated, a layer of silicon dioxide can be obtained on the surface of the silicon carbide fibers. In the subsequent thermal environment during use, the silicon dioxide layer can react with the decomposition products of the aluminum carbon silicide, reinforce the composite structure, and disperse the stress generated by the pyrolysis of the mixed microspheres during the pyrolysis of the composite binder components, avoiding the problem of stress concentration, and ultimately improving the micro-crack resistance of the ladle brick. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is the XRD diffraction test pattern of the aluminum carbon silicide mixed powder in Preparation Example 1 of this application.

[0023] Figure 2 It is the oxidation resistance test results of the low-aluminum refined ladle bricks in Examples 1 - 4 and Comparative Examples 1 - 3 of this application.

[0024] Figure 3 It is the SEM cross-section scan pattern of the low-aluminum refined ladle bricks in Comparative Example 1 and Example 2 of this application after heat treatment. DETAILED DESCRIPTION OF THE INVENTION

[0025] The technical solutions of the present invention will be described in detail below with reference to several representative embodiments of the present invention.

[0026] 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 can all be obtained from commercial sources.

[0027] Description of the raw materials used in the examples and comparative examples of the present invention: White clay, particle size ≤ 5 μm, alumina content ≤ 20%; Silica, particle size ≤ 100 μm; Carbon powder, particle size ≤ 75 nm; Aluminum powder, particle size 20 - 30 μm, purity ≥ 99%; Activated alumina, specific surface area ≥ 280 m 2 / g, particle diameter 10 - 20 μm; Pitch powder, particle diameter ≤ 2 mm, ash content ≥ 15%; Silicon carbide fiber, aspect ratio ≥ 50; The chemical composition of fused magnesia is shown in Table 1.

[0028] Table 1 Chemical composition of fused magnesia

[0029] Preparation Example 1 Take 120 g of silica, 550 g of carbon powder, 430 g of aluminum powder and 1 g of activated alumina, mix them, add 50 ml of anhydrous ethanol, mix and stir for 10 min, then use a molding press to set the pressure at 35 MPa and mold them into mixed microspheres with Φ = 35 mm. Subsequently, place the mixed microspheres in a chemical furnace, purge the air with argon gas, then ignite them with a tungsten wire. After stabilization, transfer the sintered product to a high-pressure reactor, set the system pressure at 1.2 GPa and the temperature at 1750 °C, and continue to process at a constant temperature for 10 h. Grind the solid product for 1 min and then pass it through a 200-mesh sieve. The fine-grained product in the lower layer is further pulverized with a disk-type air classifier mill for 10 min, and then mixed with the residue on the upper sieve to obtain an aluminum carbon-silicide mixed powder.

[0030] Take 10 g of sodium silicate and 0.5 g of sodium dodecylbenzenesulfonate, disperse them in 100 ml of deionized water and 50 ml of glycerol. Then add 0.1 g of sodium citrate to the system, adjust the magnetic stirring speed to 300 rpm, and process for 1 min. Subsequently, use a 20% sodium hydroxide solution to adjust the pH of the system to 10 to obtain a sodium silicate mixed solution.

[0031] Take 200 g of pitch powder and 45 g of aluminum carbon-silicide mixed powder, mix them and place them in a spray granulator. Use the sodium silicate mixed solution as the spray binder, set the spray pressure at 0.3 MPa and the drying temperature at 70 °C to obtain mixed microspheres.

[0032] Take 10 g of silicon carbide fibers, place them in a muffle furnace, adjust the heating rate to 7.5 °C / min and heat up to 1200 °C, then hold for 2 h, stop heating and cool with the furnace to obtain pretreated silicon carbide fibers.

[0033] Preparation Example 2 Take 125 g of silica, 560 g of carbon powder, 430 g of aluminum powder and 2 g of activated alumina and mix them. Add 50 ml of absolute ethanol, mix and stir for 10 min. Then use a molding press to set the pressure at 36 MPa and mold them into mixed microspheres with Φ = 35 mm. Subsequently, place the mixed microspheres in a chemical furnace, purge the air with argon, then ignite with a tungsten wire. After stabilization, transfer the sintered product to a high-pressure autoclave, set the system pressure at 1.8 GPa and the temperature at 1800 °C, and continue to treat at a constant temperature for 12 h. Grind the solid product for 2 min and then pass through a 200-mesh sieve. The lower fine-grained product is further ground with a disk-type air jet mill for 15 min, and then mixed with the upper sieve residue to obtain an aluminum silicon carbide mixed powder.

[0034] Take 12 g of sodium silicate and 0.5 g of sodium dodecylbenzenesulfonate, add 120 ml of deionized water and 50 ml of glycerol for dispersion. Then add 0.2 g of sodium citrate to the system, adjust the magnetic stirring speed to 300 rpm, and treat for 3 min. Subsequently, use a sodium hydroxide solution with a mass concentration of 20% to adjust the pH of the system to 11 to obtain a sodium silicate mixed solution.

[0035] Take 250 g of asphalt powder and 60 g of the aluminum silicon carbide mixed powder and mix them, then place them in a spray granulator. Using the sodium silicate mixed solution as a spray binder, set the spray pressure at 0.3 MPa and the drying temperature at 75 °C to obtain mixed microspheres.

[0036] Take 10 g of silicon carbide fibers, place them in a muffle furnace, adjust the heating rate to 7.5 °C / min and heat up to 1200 °C, then hold for 3 h, stop heating and cool with the furnace to obtain pretreated silicon carbide fibers.

[0037] Preparation Example 3 Take 130 g of silica, 580 g of carbon powder, 440 g of aluminum powder and 3 g of activated alumina and mix them. Add 50 ml of absolute ethanol, mix and stir for 10 min. Then use a molding press to set the pressure at 37 MPa and mold them into mixed microspheres with Φ = 36 mm. Subsequently, place the mixed microspheres in a chemical furnace, purge the air with argon, then ignite with a tungsten wire. After stabilization, transfer the sintered product to a high-pressure autoclave, set the system pressure at 2.3 GPa and the temperature at 1835 °C, and continue to treat at a constant temperature for 16 h. Grind the solid product for 3 min and then pass through a 200-mesh sieve. The lower fine-grained product is further ground with a disk-type air jet mill for 30 min, and then mixed with the upper sieve residue to obtain an aluminum silicon carbide mixed powder.

[0038] Take 20 g of sodium silicate and 1 g of sodium dodecylbenzenesulfonate, add 150 ml of deionized water and 100 ml of glycerol for dispersion. Then add 0.3 g of sodium citrate to the system, adjust the magnetic stirring speed to 300 rpm, and treat for 5 min. Subsequently, use a sodium hydroxide solution with a mass concentration of 20% to adjust the pH of the system to 12 to obtain a sodium silicate mixture.

[0039] Take 300 g of asphalt powder and 70 g of a mixed powder of silicon carbide and aluminum, mix them, and place them in a spray granulator. Use the sodium silicate mixture as the spray binder, set the spray pressure at 0.4 MPa and the drying temperature at 80 °C to obtain mixed microspheres.

[0040] Take 10 g of silicon carbide fibers, place them in a muffle furnace, adjust the heating rate to 8 °C / min and heat up to 1275 °C. Then keep the temperature for 3 h, stop heating, and let it cool down with the furnace to obtain pretreated silicon carbide fibers.

[0041] Preparation Example 4 The difference between this preparation example and Preparation Example 1 is only that the preparation steps of the pretreated silicon carbide fibers are as follows: Take 10 g of silicon carbide fibers, place them in a muffle furnace, adjust the heating rate to 7.8 °C / min and heat up to 1250 °C. Then keep the temperature for 3 h, stop heating, and let it cool down with the furnace to obtain pretreated silicon carbide fibers.

[0042] All the other steps are the same as those in Preparation Example 1.

[0043] Example 1 In this example, the preparation steps of the low-aluminum refined ladle brick are as follows: Take 1000 g of fused magnesia with a particle size ≤ 0.088 mm, 3000 g of 1 - 3 mm fused magnesia, 2000 g of 3 - 5 mm fused magnesia, 200 g of white clay, 50 g of carbon black, and 500 g of a composite binder, mix them, place them in a wheel mill and treat for 20 min. Then seal and homogenize for 2 d. After that, use a molding press to set the pressure at 250 MPa, press them into a 100 mm × 55 mm × 28 mm specimen, and then heat-treat at 200 °C for 10 h, and then place it overnight at 45 °C to obtain the low-aluminum refined ladle brick.

[0044] In this example, the preparation steps of the composite binder are as follows: Take 100 g of mixed microspheres, add them to 200 ml of a treatment liquid and let it stand for 1 min. Then filter and take the solid part and place it in a ball rolling machine. Immediately add 20 g of pretreated silicon carbide fibers and treat for 5 min. Then transfer it to a rotary furnace at 85 °C, set the rotation speed at 25 rpm, export the material after treating for 10 s, and cool it with air for 1 min. Then repeat the steps of returning to the furnace and cooling twice, and let it stand at room temperature to obtain it.

[0045] In this embodiment, the hybrid microspheres and the pretreated silicon carbide fibers are prepared according to Preparation Example 1.

[0046] Among them, the treatment liquid is prepared by mixing deionized water, absolute ethanol and polyethylene glycol in a volume ratio of 3:1:0.5.

[0047] Example 2 In this embodiment, the preparation steps of the low-aluminum refining ladle brick are as follows: Take 1200 g of fused magnesia with a particle size ≤ 0.088 mm, 3500 g of fused magnesia with a particle size of 1 - 3 mm, 2200 g of fused magnesia with a particle size of 3 - 5 mm, 250 g of white clay, 50 g of carbon black and 600 g of composite binder, mix them, place them in a wheel mill for 20 min, then seal and homogenize for 2 d. After that, use a molding press to set the pressure at 250 MPa, press them into a 100 mm × 55 mm × 28 mm specimen, and then heat-treat them at 200 °C for 12 h, and then place them overnight at 45 °C to obtain the low-aluminum refining ladle brick.

[0048] In this embodiment, the preparation steps of the composite binder are as follows: Take 100 g of hybrid microspheres, add them to 200 ml of treatment liquid and let them stand for 2 min, then filter to obtain the solid part and place it in a ball rolling machine. Immediately add 20 g of pretreated silicon carbide fibers and treat for 10 min. Then transfer them to a rotary furnace at 85 °C, set the rotation speed at 25 rpm, export the material after 15 s of treatment, blow air to cool for 1 min, and then repeat the process of returning to the furnace and cooling 2 times, and place them at room temperature to obtain the product.

[0049] In this embodiment, the hybrid microspheres and the pretreated silicon carbide fibers are prepared according to Preparation Example 2.

[0050] Among them, the treatment liquid is prepared by mixing deionized water, absolute ethanol and polyethylene glycol in a volume ratio of 4:1:0.5.

[0051] Example 3 In this embodiment, the preparation steps of the low-aluminum refining ladle brick are as follows: Take 1300 g of fused magnesia with a particle size ≤ 0.088 mm, 3600 g of fused magnesia with a particle size of 1 - 3 mm, 2400 g of fused magnesia with a particle size of 3 - 5 mm, 250 g of white clay, 60 g of carbon black and 750 g of composite binder, mix them, place them in a wheel mill for 20 min, then seal and homogenize for 3 d. After that, use a molding press to set the pressure at 275 MPa, press them into a 100 mm × 55 mm × 28 mm specimen, and then heat-treat them at 225 °C for 12 h, and then place them overnight at 50 °C to obtain the low-aluminum refining ladle brick.

[0052] In this embodiment, the preparation steps of the composite binder are as follows: Take 100 g of the mixed microspheres, add them to 200 ml of the treatment liquid, let it stand for 2 min, then filter to obtain the solid part and place it in a ball rolling machine. Immediately add 20 g of the pretreated silicon carbide fibers and treat for 20 min. Then transfer it to a rotary furnace at 90 °C, set the rotation speed at 35 rpm, export the material after treating for 20 s, cool it by blowing air for 2 min, and then repeat the steps of returning to the furnace and cooling 3 times. Place it at room temperature to obtain the product.

[0053] In this example, the mixed microspheres and the pretreated silicon carbide fibers are prepared according to Preparation Example 3.

[0054] Among them, the treatment liquid is prepared by mixing deionized water, absolute ethanol and polyethylene glycol in a volume ratio of 5:1.5:0.5.

[0055] Example 4 In this example, the preparation steps of the low-aluminum refining ladle brick are as follows: Take 1500 g of fused magnesia with a particle size ≤ 0.088 mm, 4000 g of fused magnesia with a particle size of 1 - 3 mm, 2500 g of fused magnesia with a particle size of 3 - 5 mm, 300 g of white clay, 100 g of carbon black and 800 g of the composite binder, mix them, place them in a wheel mill and treat for 20 min. Then seal and homogenize for 3 d. After that, use a molding press to set the pressure at 275 MPa, press them into a specimen with dimensions of 100 mm × 55 mm × 28 mm, and then heat-treat at 225 °C for 12 h. Subsequently, place it at 50 °C overnight to obtain the low-aluminum refining ladle brick.

[0056] In this example, the preparation steps of the composite binder are as follows: Take 100 g of the mixed microspheres, add them to 200 ml of the treatment liquid, let it stand for 3 min, then filter to obtain the solid part and place it in a ball rolling machine. Immediately add 20 g of the pretreated silicon carbide fibers and treat for 20 min. Then transfer it to a rotary furnace at 90 °C, set the rotation speed at 35 rpm, export the material after treating for 20 s, cool it by blowing air for 2 min, and then repeat the steps of returning to the furnace and cooling 3 times. Place it at room temperature to obtain the product.

[0057] In this example, the mixed microspheres and the pretreated silicon carbide fibers are prepared according to Preparation Example 4.

[0058] Among them, the treatment liquid is prepared by mixing deionized water, absolute ethanol and polyethylene glycol in a volume ratio of 5:2:0.5.

[0059] Comparative Example 1 The difference between this comparative example and Example 1 is only that the preparation steps of the composite binder are as follows: Take 25 g of the aluminum carbonitride mixed powder, 75 g of asphalt powder and 20 g of the pretreated silicon carbide fibers, and mix them to obtain the composite binder.

[0060] The remaining steps are the same as those in Example 1.

[0061] Comparative Example 2 The difference between this comparative example and Example 1 lies in that during the preparation process of the composite binder, the preparation steps of the mixed microspheres used are as follows: Take 120 g of silica, 550 g of carbon powder, 430 g of aluminum powder and 1 g of activated alumina, mix them, add 50 ml of absolute ethanol, mix and stir for 10 min, then use a molding press to set the pressure at 35 MPa and mold them into mixed microspheres with Φ = 35 mm. Subsequently, place the mixed microspheres in a chemical furnace, purge the air with argon gas, then ignite them with a tungsten wire. After stabilization, transfer the sintered product to a high-pressure autoclave, set the system pressure at 1.2 GPa and the temperature at 1750 °C, and continue to process at a constant temperature for 10 h. After grinding the solid product for 1 min, obtain the aluminum carbon silicide mixed powder.

[0062] All other steps are the same as those in Example 1.

[0063] Comparative Example 3 The difference between this comparative example and Example 1 lies in that an equal amount of glass fiber is used to replace the pretreated silicon carbide fiber to prepare the composite binder.

[0064] All other steps are the same as those in Example 1.

[0065] Among them, the glass fiber (model: T912) is provided by Taishan Fiberglass Co., Ltd.

[0066] Performance detection test XRD test Take the aluminum carbon silicide mixed powder of Preparation Example 1 for XRD diffraction test, and the results are as Figure 1 shown.

[0067] Antioxidant test Refer to the test method of GB / T17732 - 2023 to conduct antioxidant tests on the low-aluminum refining ladle bricks of Examples 1 - 4 and Comparative Examples 1 - 3. Heat them at a heating rate of 8.5 °C / min to 1000 °C, then continue to heat at a heating rate of 4 °C / min to 1475 °C, and then keep them at a constant temperature for 2 h. During the process, pass air into the test furnace at a flow rate of 4 L / min. After the test, measure the thickness of the decarburized layer on the cross-section of each group of low-aluminum refining ladle bricks. Take the average value of 3 measurements for each group as the final data, and the test results are as Figure 2 shown.

[0068] Analyze Examples 1 - 4 and Comparative Examples 1 - 3 and combine with Figure 2It can be seen that after the antioxidant test of the test groups in the embodiments, the thickness of the decarburized layer formed is slightly lower than that of the comparative example, indicating that the embodiments have better ability to resist the external oxidation environment; for the comparative example 1, since only the composite binder components are mechanically blended, and during the preparation of the ladle brick, each component is redispersed, resulting in a relatively weak synergistic antioxidant effect between the components, and the thickness of the decarburized layer obtained after the antioxidant test is the highest; for comparative example 2 and comparative example 3, the lack of treatment process or the change of fiber materials also lead to the reduction of the antioxidant performance of the ladle brick products; among all the test groups, after the antioxidant test of embodiment 2, the thickness of the decarburized layer formed by the ladle brick is the lowest.

[0069] SEM test Take the low-aluminum refining ladle bricks of embodiment 2 and comparative example 1, place them in a test furnace, heat-treat them with air blowing at 1200 °C for 1 h, and then take cross-sections for SEM scanning tests respectively. The test results are as Figure 3 shown.

[0070] Analyze embodiment 2 and comparative example 1 and combine with Figure 3 It can be seen that after heat treatment, obvious microcrack concentration areas appear locally in the brick body of comparative example 1 ( Figure 3 left), while the cross-section of embodiment 2 ( Figure 3 right) is relatively intact, indicating that when the components of the composite binder are effectively combined, the ability of the ladle brick body to resist microcracks can be enhanced, and when the combination of each component is not good, the ability of the ladle brick to resist microcracks is greatly reduced.

[0071] This specific embodiment is only an interpretation of the present application, and it does not limit the present application. After reading this specification, those skilled in the art can make modifications without creative contributions to this 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 preparation method of a low-aluminum refined ladle brick, characterized in that, It is prepared by mixing raw materials including the following parts by mass: 10 - 15 parts of fused magnesia with a particle size ≤ 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 are as follows: Take fused magnesia, white clay, carbon black, and the composite binder, mix and homogenize them, then after molding under pressure and heat treatment, place them at 45 - 55 °C overnight to obtain it; Among them, the composite binder is obtained by mixing a carbon siliconized aluminum mixed powder and asphalt powder, spray granulating to obtain mixed microspheres, humidifying them, then mixing and rolling balls with pretreated silicon carbide fibers, and finally obtaining it through a re - furnace cooling treatment.

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

3. The preparation method of a low-aluminum refined ladle brick according to claim 1, characterized in that The preparation steps of the carbon siliconized aluminum mixed powder include: taking silicon dioxide, carbon powder, aluminum powder and a crystal - promoting agent, adding absolute ethanol, stirring, molding under pressure and then heat - burning, passing the solid product through a 200 - mesh sieve, classifying and then mixing to obtain the carbon siliconized aluminum mixed powder; The crystal - promoting agent is activated alumina with an average particle size of 10 - 20 microns; The mass ratio of silicon dioxide, carbon powder, aluminum powder to the crystal - promoting agent used is (1.2 - 1.3):(5.5 - 5.8):(4.3 - 4.4):(0.01 - 0.03); The classification is: taking the fine - grained product powder of the lower layer after sieving, grinding it and mixing it with the sieve residue of the upper layer.

4. The preparation method of a low-aluminum refined ladle brick according to claim 3, characterized in that, The heat - burning treatment sequentially includes a first - stage heat - burning and a second - stage heat - burning, and the operations are as follows: First - stage heat - burning: Pass argon gas, and then ignite with a tungsten wire; Second - stage heat - burning: Set the system pressure at 1.2 - 2.3 GPa and the temperature at 1750 - 1835 °C, and continue to treat the product of the first - stage heat - burning at a constant temperature for 10 - 16 h.

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

6. The preparation method of a low-aluminum refined ladle brick according to claim 1, characterized in that, The humidifying treatment is: taking the mixed microspheres, adding them to the treatment liquid, standing for 1 - 3 min, and then immediately filtering to take the solid part.

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

5.

8. The preparation method of a low-aluminum refined ladle brick according to claim 1, characterized in that, The preparation steps of the pretreated silicon carbide fibers include: taking silicon carbide fibers and placing them in a muffle furnace, heating up and then holding the temperature, and then cooling with the furnace to obtain them; The operation of heating up and then holding the temperature is: adjusting the heating rate to 7.5 - 8 °C / min, heating up to 1200 - 1275 °C, and then holding the temperature for 2 - 3 h.

9. The preparation method of a low-aluminum refined ladle brick according to claim 1, characterized in that, The re - furnace cooling treatment is: transferring the ball - rolling product to a rotary furnace, setting the rotation speed at 25 - 35 rpm and the temperature at 85 - 90 °C, treating for 10 - 20 s and then discharging the material, and blowing air to cool for 1 - 2 min, repeating the operation 2 - 3 times.

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

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