A multi-element metal composite magnesium-aluminum spinel-containing refractory material and a preparation method thereof

Abstract

The application belongs to the technical field of refractory materials, and relates to a multi-metal composite magnesium-alumina spinel-containing refractory material and a preparation method thereof. The material of the magnesium-alumina spinel-containing refractory material is one of SiC-MgAl2O4, Al2O3-MgAl2O4 and MgO-MgAl2O4; the main body of components of the magnesium-alumina spinel-containing refractory material is granular SiC, Al2O3 and MgO as aggregate and a mixture of fine powder and micro powder composed of MgAl2O4 as matrix, and the components contain metal Al and Al-Mg alloy; the magnesium-alumina spinel-containing refractory material is prepared through hot air drying at 150-200 DEG C for 8-24 hours, and high-temperature sintering is not needed; the magnesium-alumina spinel-containing refractory material is a composite refractory material with alpha-SiC or corundum or periclase as main crystal phase and magnesium-alumina spinel as secondary crystal phase. The application realizes that the formed green body only needs to be treated at low temperature not higher than 200 DEG C, and can meet good mechanical properties, structural stability and corrosion resistance in a use temperature range of 25-1600 DEG C, and the built-in hot work thermal reserve can realize high mechanical strength and volume stability from normal temperature to the highest use environment through the waste heat in the oven heating process.

Description

Technical Field

[0001] This invention belongs to the field of refractory materials technology, and mainly relates to a multi-metal composite magnesium-aluminum spinel refractory material and its preparation method. Background Technology

[0002] Chromium-containing refractories possess excellent resistance to slag erosion and are commonly used lining materials for high-temperature vessels exposed to highly corrosive media, such as coal-water slurry gasification furnaces and RH furnaces. However, they pose a potential hazard to human health and the environment due to hexavalent chromium, necessitating the use of green refractories as alternatives. Magnesium-aluminum spinel has a high melting point and good slag erosion resistance, and can form solid solutions with Fe and Ni in slag. Spinel-containing refractories, such as periclase-magnesium-aluminum spinel and silicon carbide-magnesium-aluminum spinel composite refractories, represent a potential class of green, chromium-free refractories that can meet the requirements for high-temperature and slag-resistant applications. ZL Patent application 201711187027.6 discloses a silicon carbide-magnesium aluminum spinel composite refractory material. This material uses silicon carbide particles as aggregate and fine or micro powders of magnesium aluminum spinel, alumina, and magnesium oxide as the matrix, with added antioxidants. The aggregate, matrix, and binder are mixed and shaped, then dried and fired under a carbon-embedded or nitrogen atmosphere at a maximum firing temperature of 1450–1600℃, resulting in a composite refractory material with SiC as the main crystalline phase and magnesium aluminum spinel as the secondary crystalline phase. However, because silicon carbide is a non-polar, non-oxide material, it is difficult to form a chemical bond with the polar magnesium aluminum spinel matrix. Therefore, this silicon carbide-magnesium aluminum spinel composite refractory material has low mechanical properties, with a room temperature compressive strength of approximately 50 MPa, which is insufficient to meet the requirements for erosion and abrasion resistance of the furnace lining under high-speed coal-water slurry and gas flow in gasifiers.

[0003] To further improve the high-temperature mechanical strength of silicon carbide-magnesium aluminum spinel composite refractory, ZL202010646418.5 discloses a silicon carbide-magnesium aluminum spinel-aluminum composite refractory. Based on ZL201711187027.6, it adds coated aluminum powder with a particle size range of 10μm to 45μm, accounting for 2% to 8% of the total raw material mass. When fired at a maximum temperature of 1500℃ to 1600℃ under a high-temperature carbon-buried atmosphere, the SiO2 and SiO generated by the local oxidation of SiC, and the highly active Al2O3 generated by the oxidation of the aluminum powder, react again to form irregular mullite whiskers. These whiskers act as a reinforcing phase, improving the room-temperature and high-temperature mechanical properties of the silicon carbide-magnesium aluminum spinel composite refractory. To achieve the formation of mullite whiskers, this process requires a firing temperature of 1500 to 1600℃, resulting in high energy consumption during preparation.

[0004] ZL 202210815408.9 discloses a non-fired silicon carbide-magnesium aluminate spinel refractory material, its preparation method, and the finished product. The raw materials include silicon carbide particles, magnesium aluminate spinel fine powder, aluminum powder coated with an organic polymer, and solid additives such as calcium aluminate cement. This material does not require high-temperature firing; after molding, it only needs low-temperature treatment at around 200℃ to achieve excellent refractoriness and slag resistance. The material contains one or more of calcium aluminate cement, boron oxide, and phosphorus pentoxide as solid additives. These additives form a liquid phase at 400–1000℃ to improve the material's mid-temperature strength. However, the presence of these boron and phosphorus-containing liquid phases reduces the material's slag resistance and also affects the morphology and quantity of the reaction products of the aluminum powder above 1000℃, weakening the whisker reinforcement effect.

[0005] Adding elemental Al or Si to the raw materials of refractory materials and subjecting them to high-temperature treatment allows these elements to react with environmental stimuli such as N2, O2, and CO in the liquid and gas phases formed after melting, generating Al, Si, O, C, and O compounds with fibrous structures that interweave within the refractory material structure, significantly improving its mechanical properties. However, although metallic Al has a low melting point (660℃), its high reactivity and easy surface oxidation to form an Al2O3 shell that acts as a passivator, mean that Al can hardly react below 1000℃. The formation of whisker-like reinforcing phases; elemental Si has a high melting point (1410℃) and high vapor pressure, and will not form Si-containing whisker-like reinforcing phases below 1000℃; therefore, for non-fired refractories with added metallic Al or Si that have not been sintered at high temperatures, if used as high-temperature furnace linings, there are problems such as poor mechanical strength in the medium temperature range of 600~1000℃ during the addition process from room temperature to high temperature, which affects the safety and stability of the furnace lining structure and erosion corrosion, thus restricting the engineering application of non-fired refractories as erosion-resistant, creep-resistant, and corrosion-resistant furnace linings. Summary of the Invention

[0006] The purpose of this invention is to propose a multi-metal composite magnesium-aluminum spinel refractory material and its preparation method. By changing the raw material formulation, the formed green body only needs to be heat-treated at a low temperature not exceeding 200℃ to meet the requirements of good mechanical properties, structural stability and corrosion resistance within the service temperature range of 25~1600℃. From the time of construction to the thermal standby, the residual heat of the furnace heating process can be used to achieve high mechanical strength and volume stability from room temperature to the maximum service environment, thus achieving the purpose of energy saving and cost reduction.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: A multi-metal composite magnesium-aluminum spinel refractory material, wherein the magnesium-aluminum spinel refractory material is one of SiC-MgAl2O4, Al2O3-MgAl2O4, or MgO-MgAl2O4; the main component of the magnesium-aluminum spinel refractory material is composed of particles of SiC, Al2O3, and MgO as aggregates and a mixture of fine and micro powders constituting MgAl2O4 as a matrix, and the component contains metallic Al and Al-Mg alloy; the particle size range of the aggregate is 0.2-5 mm; the particle size of the matrix is ​​≤0.1 mm; the purity of metallic Al and Al-Mg alloy is ≥99.0%, the particle size is ≤0.074 mm, and the total content is 4%-10% of the total mass of the solid components of the refractory material, and the mass ratio of the two is 1:1-4:1; the magnesium-aluminum spinel refractory material uses a liquid binder, and the amount added is 3%-6% of the total mass of the solid powder; Prepared by hot air drying at 150-200℃ for 8-24 hours, without high-temperature firing; the aforementioned multi-metal composite magnesium-aluminum spinel refractory material is a non-firing refractory product with a fixed shape after molding, which can be used as a high-temperature furnace lining without high-temperature firing treatment above 1200℃; the aforementioned magnesium-aluminum spinel refractory material is a composite refractory material with α-SiC or corundum or periclase as the main crystalline phase and magnesium-aluminum spinel as the secondary crystalline phase; the sum of the mass fractions of SiC, MgO and Al2O3 in the aforementioned magnesium-aluminum spinel refractory material is greater than or equal to 95%, the apparent porosity is 6% to 16%, and the bulk density is 2.60 to 3.30 g / cm³. 3 The flexural strength at room temperature is 25~40 MPa, the flexural strength at 600~1200℃ is 15~30 MPa, and the flexural strength at 1400℃ is 25~40 MPa.

[0008] The magnesium aluminum spinel is a secondary crystalline phase, and its content in the total mineral phase composition of the magnesium aluminum spinel-containing refractory material after high-temperature treatment at 1400~1600℃ is 15%~40%.

[0009] The main crystalline phases α-SiC, corundum, and periclase constitute no less than 50% of the total mineral phase composition of magnesium-aluminum spinel refractory materials after high-temperature treatment at 1400~1600℃. The particles containing SiC, Al2O3, and MgO in the aggregate are industrial-grade refractory materials, and are one of fused silicon carbide, fused white corundum, sintered corundum, fused magnesia, and sintered magnesia.

[0010] The matrix is ​​an industrial raw material composed of MgAl2O4, MgO, and Al2O3, or a precursor of organic or inorganic salts that can generate MgO and Al2O3 at high temperatures.

[0011] The liquid binder is one or two of the organic resins phenolic resin and furfural resin, diluted with anhydrous ethanol; the liquid binder does not contain free water.

[0012] A method for preparing a multi-metal composite magnesium-aluminum spinel refractory material, comprising the following steps: The first step involves mixing industrial-grade raw materials MgAl2O4 or MgO and Al2O3, or precursor powders of organic or inorganic salts that can generate MgO and Al2O3 at high temperatures, with industrial-grade raw materials metallic Al and Al-Mg alloy powder with a purity of ≥99.0% and a particle size of ≤0.074mm, with corundum or zirconia grinding balls in a mixer until uniformly mixed. The grinding residue is then sieved out to prepare a mixed powder. The second step is to weigh a certain proportion of particles of SiC, Al2O3, and MgO with a particle size range of less than or equal to 5 mm and greater than 0.2 mm, pour them into a mixer, and mix them evenly with the liquid binder. The third step is to add the mixed powder prepared in the first step to the aggregate containing the binder in the second step in a certain proportion, stir evenly, and prepare mud. The fourth step is to put the clay into a steel mold and shape it on a friction brick press, hydraulic press or vibration molding machine with a pressure of not less than 50MPa. After demolding, a refractory material blank is obtained. The fifth step is to dry the blank with hot air at 150~200℃ for 8~24 hours to obtain a multi-metal composite magnesium aluminum spinel refractory material.

[0013] The liquid binder exhibits bonding strength after cross-linking and curing at 150-200℃. This type of binder gradually dehydrates, pyrolyzes, and carbonizes at 200-600℃. On the one hand, it can provide the refractory material with extremely high mechanical properties at 150-600℃. On the other hand, the pyrolysis product is C, which provides a carbon source for the refractory material components. It adjusts the concentration of CO and O2 gas phases inside the material at high temperatures towards a reaction direction that favors the metal phase reaction to generate more low-dimensional reinforcing phases, which is beneficial to improving the mechanical properties of the material. This also prevents the metal Al or Al-Mg alloy from being consumed by hydration reaction at room temperature.

[0014] The magnesium aluminum spinel component is either added to the material composition initially or obtained by further reaction of the material composition at high temperature. As a high-temperature phase, the presence of magnesium aluminum spinel not only ensures the temperature resistance of the refractory material, but also resists the penetration and erosion of molten slag, ensuring that the refractory material has a certain high-temperature slag resistance.

[0015] The SiC-MgAl2O4, Al2O3-MgAl2O4, or MgO-MgAl2O4 mentioned above are all green refractory materials that are resistant to high temperature and slag erosion. The silicon carbide, corundum, or magnesia particles used as aggregates have high melting points and erosion resistance. The phases existing in α-SiC, corundum, and periclase at high temperatures can provide the refractory material with excellent high-temperature mechanical properties and slag erosion resistance.

[0016] During the heating and heat preservation stages of the magnesium-aluminum spinel refractory material used as a furnace lining, the metallic Al and Al-Mg alloys in the composition can react with gaseous substances such as N2, O2, and CO in the environment to generate substances composed of Al, Mg, N, O, and C. These substances will further react with Al2O3, MgO, MgAl2O4, etc. in the composition to generate complex solid solutions containing Al, Mg, N, O, C, and Si, such as AlN, Al2OC-AlN, AlON, MgAlON, MgAl2O4, and Sialon. These solid solutions are not only resistant to high temperatures, but also have granular, whisker-like, and lamellar microstructures that permeate the material's internal structure, improving the mechanical properties of the refractory material at high temperatures. When the content of the metallic phase in the composition is too low, the improvement in the mechanical properties of the refractory material is not significant. When the content of the metallic phase in the composition is too high, on the one hand, the reaction is incomplete at high temperatures, leaving residual metallic phases. The melting of the residual metallic phases at high temperatures leads to a decrease in the mechanical properties of the material. On the other hand, the nitriding and oxidation reactions of the metal produce volume expansion, and excessive expansion causes the refractory material to crack.

[0017] The temperature ranges for the reaction of metallic Al and Al-Mg alloys differ significantly in the material composition. Due to the alumina film coating, metallic Al completes the reaction to form Al, N, O, and C whiskers within the temperature range of 1000–1400℃. In Al-Mg alloys, Al and Mg are uniformly dispersed solid solutions, with Mg exhibiting higher reactivity than Al. Al-Mg alloys cannot form a dense oxide film after oxidation. Al and Mg in the alloy begin to fully react with the gaseous phase in the environment at approximately 600℃. The low dimensionality of the Al, Mg, N, and O formed is beneficial for improving the high-temperature mechanical properties of the refractory material at 600–1000℃. The composite addition of Al-Mg alloys and metallic Al helps maintain stable and high-temperature mechanical properties, such as hot flexural strength, within the 600–1400℃ temperature range. Because the final product of Al-Mg alloys is a lamellar MgAlON, it has lower bonding strength and density than the short columnar AlON and AlN products formed by metallic Al. Therefore, a higher proportion of metallic Al is preferable in the composite metal addition ratio.

[0018] This invention proposes a multi-metal composite magnesium-aluminum spinel refractory material and its preparation method, which uses SiC, Al2O3 or MgO as aggregate and MgAl2O4 as matrix to form a composite structure and improve the basic mechanical properties of the material. By adding metallic Al and Al-Mg alloy, low-dimensional reinforcing phases are generated through the reaction of the two metallic phases with the ambient atmosphere at different temperature ranges: the Al-Mg alloy can begin to react at about 600℃, generating low-dimensional phases of Al, Mg, N, and O, improving mechanical properties in the 600-1000℃ range; metallic Al reacts in the 1000-1400℃ range, generating Al, N, O, and C whiskers, improving high-temperature mechanical properties; anhydrous organic resin binder is used to prevent hydration of the metallic phases, while providing high mechanical strength from room temperature to 600℃; it can be used after low-temperature drying, saving energy consumption of high-temperature firing, while ensuring that the material has high mechanical strength across the entire temperature range; by changing the raw material formulation, the formed green body only needs to be heat-treated at a low temperature not exceeding 200℃ to meet the requirements of good mechanical properties, structural stability, and corrosion resistance in the service temperature range of 25~1600℃. From construction to thermal standby, the waste heat from the furnace heating process is used to achieve high mechanical strength and volume stability from room temperature to the highest service environment, achieving the goal of energy saving and cost reduction. Detailed Implementation

[0019] The present invention will be described in detail with reference to specific embodiments: Example 1:

[0020] 40 kg of fused magnesium aluminum spinel fine powder with a particle size ≤0.1 mm, 2.5 kg of aluminum powder (Al=99.0%) with a particle size ≤0.074 mm, and 2.5 kg of magnesium aluminum alloy powder (Al=50.0%, Mg=49.7%) with a particle size ≤0.074 mm were weighed out and dry-mixed evenly. Then, they were mixed with 55 kg of fused silicon carbide particles with a particle size of 0.2-5 mm and w(SiC)=98% and 6 kg of thermosetting phenolic resin binder diluted with alcohol in a roller-type sand mixer to form mud. The mud was put into a steel mold and formed into a standard brick blank of 230 mm×114 mm×65 mm under a friction brick press at a pressure of 50 MPa. After the blank was placed naturally, it was dried in hot air at 150℃ for 8 h to obtain silicon carbide-magnesium aluminum spinel composite refractory material.

[0021] XRD analysis revealed that the silicon carbide-magnesium aluminum spinel composite refractory material exhibits SiC as the main crystalline phase, comprising approximately 55%, and magnesium aluminum spinel as the secondary crystalline phase, comprising approximately 40%. The composite refractory material contains 53% SiC, 35% Al₂O₃, and 10% MgO by mass, with an apparent porosity of 10% and a bulk density of 2.95 g / cm³. 3The flexural strength at room temperature is 40 MPa, at 600℃ it is 15 MPa, at 900℃ it is 28 MPa, at 1200℃ it is 30 MPa, and at 1400℃ it is 40 MPa. Example 2:

[0022] 15 kg of fused magnesium aluminum spinel fine powder with a particle size ≤0.1 mm, 4 kg of metallic aluminum powder with a particle size ≤0.074 mm and Al=99.0%, and 1 kg of magnesium aluminum alloy powder with a particle size ≤0.074 mm, Al=50.0%, and Mg=49.7% were weighed out and dry-mixed evenly. Then, they were mixed with 80 kg of fused silicon carbide particles with a particle size of 0.2-3 mm and w(SiC)=98% and 5 kg of furfural resin binder diluted with alcohol in a roller-type sand mixer to form mud. The mud was put into a steel mold and formed into a standard brick blank of 230 mm×114 mm×65 mm under a friction brick press with a pressure of 100 MPa. After the blank was placed naturally, it was dried in hot air at 200℃ for 24 h to obtain silicon carbide-magnesium aluminum spinel composite refractory material.

[0023] XRD analysis revealed that the silicon carbide-magnesium aluminum spinel composite refractory material exhibits SiC as the main crystalline phase, comprising approximately 80%, and magnesium aluminum spinel as the secondary crystalline phase, comprising approximately 20%. The composite refractory material contains 78% SiC, 16% Al₂O₃, and 3.5% MgO by mass, with an apparent porosity of 8% and a bulk density of 2.98 g / cm³. 3 The flexural strength at room temperature is 33 MPa, the flexural strength at 600℃ is 18 MPa, the flexural strength at 900℃ is 25 MPa, the flexural strength at 1200℃ is 23 MPa, and the flexural strength at 1400℃ is 35 MPa. Example 3:

[0024] Weigh out 15 kg of fused magnesium aluminate spinel fine powder with a particle size ≤0.1 mm, 4 kg of sintered alumina micro powder with a particle size ≤0.01 mm, 1 kg of sintered magnesium powder with a particle size ≤0.045 mm, 7.5 kg of metallic aluminum powder with a particle size ≤0.074 mm and Al=99.0%, and 2.5 kg of magnesium aluminate alloy powder with a particle size ≤0.074 mm (Al=66.3%, Mg=32.9%). After dry mixing evenly, mix with 70 kg of fused white corundum particles with a particle size of 0.5-4 mm and w(Al2O3)=99.1%, and 6 kg of phenolic resin and furfural resin mixed binder diluted with alcohol. Mix in a roller-type sand mixer to form mud. Load the mud into a steel mold and form 230 mm × 114 mm × 65 mm bricks on a friction brick press with a pressure of 100 MPa. mm standard brick blanks are left to stand naturally and then dried with hot air at 200℃ for 24 hours to obtain corundum-magnesium aluminum spinel composite refractory material.

[0025] XRD analysis revealed that the corundum-magnesium aluminum spinel composite refractory material exhibits corundum as the main crystalline phase, comprising approximately 65%, and magnesium aluminum spinel as the secondary crystalline phase, comprising approximately 35%. The composite refractory material contains 93.5% Al₂O₃, 4.3% MgO, has an apparent porosity of 12%, and a bulk density of 3.20 g / cm³. 3 The flexural strength at room temperature is 26 MPa, at 600℃ it is 19 MPa, at 900℃ it is 18 MPa, at 1200℃ it is 28 MPa, and at 1400℃ it is 27 MPa. Example 4:

[0026] Weigh out 25 kg of fused magnesium aluminate spinel fine powder with a particle size ≤0.1 mm, 4 kg of aluminum hydroxide micro powder with a particle size ≤0.045 mm, 1 kg of magnesium carbonate powder with a particle size ≤0.045 mm, 3 kg of metallic aluminum powder with a particle size ≤0.074 mm and Al=99.0%, and 2 kg of magnesium aluminate alloy powder with a particle size ≤0.074 mm (Al=49.3%, Mg=49.9%). Mix them thoroughly with a roller mixer to form a mud. Then, mix the mud with 65 kg of sintered corundum particles with a particle size of 0.2-5 mm and w(Al2O3)=99.1% and 4 kg of phenolic resin binder diluted with alcohol. Place the mud into a steel mold and form a standard 230 mm × 114 mm × 65 mm brick blank on a vibration molding machine under a pressure of 50 MPa. After natural placement, dry the blank in hot air at 180℃ for 18 days. After h, corundum-magnesium aluminum spinel composite refractory material is obtained.

[0027] XRD analysis revealed that the corundum-magnesium aluminum spinel composite refractory material exhibits corundum as the main crystalline phase, comprising approximately 65%, and magnesium aluminum spinel as the secondary crystalline phase, comprising approximately 35%. The composite refractory material contains 93.7% Al₂O₃, 4.5% MgO, has an apparent porosity of 16%, and a bulk density of 3.05 g / cm³. 3 The flexural strength at room temperature is 23 MPa, at 600℃ it is 26 MPa, at 900℃ it is 24 MPa, at 1200℃ it is 26 MPa, and at 1400℃ it is 25 MPa. Example 5:

[0028] Weigh out 15 kg of fused magnesium aluminate spinel fine powder with a particle size ≤0.1 mm, 4 kg of sintered alumina micro powder with a particle size ≤0.045 mm, 1 kg of magnesium carbonate powder with a particle size ≤0.045 mm, 7 kg of metallic aluminum powder with a particle size ≤0.074 mm and Al=99.0%, and 3 kg of magnesium aluminate alloy powder with a particle size ≤0.074 mm (Al=49.3%, Mg=49.9%). Dry mix them thoroughly, then mix them with 45 kg of sintered corundum particles with a particle size of 0.2-3 mm and w(Al2O3)=99.1%, 25 kg of fused white corundum particles with a particle size of 3-5 mm and w(Al2O3)=99.2%, and 3 kg of phenolic resin binder diluted with alcohol in a roller mixer to form a mud. The mud is then loaded into a steel mold and molded into a 230 mm × 114 mm × 65 mm shape using a hydraulic press under pressure of 80 MPa. mm standard brick blanks are left to stand naturally and then dried with hot air at 180℃ for 18 hours to obtain corundum-magnesium aluminum spinel composite refractory material.

[0029] XRD analysis revealed that the corundum-magnesium aluminum spinel composite refractory material exhibits corundum as the main crystalline phase, comprising approximately 70%; and magnesium aluminum spinel as the secondary crystalline phase, comprising approximately 25%. The composite refractory material contains 94.1% Al₂O₃, 4.4% MgO, has an apparent porosity of 14%, and a bulk density of 3.12 g / cm³. 3 The flexural strength at room temperature is 26 MPa, at 600℃ it is 19 MPa, at 900℃ it is 19 MPa, at 1200℃ it is 22 MPa, and at 1400℃ it is 28 MPa. Example 6:

[0030] Weigh out 15 kg of fused magnesium aluminate spinel fine powder with a particle size ≤0.1 mm, 4 kg of sintered alumina micro powder with a particle size ≤0.01 mm, 1 kg of sintered magnesium powder with a particle size ≤0.045 mm, 7.5 kg of metallic aluminum powder with a particle size ≤0.074 mm and Al=99.0%, and 2.5 kg of magnesium aluminate alloy powder with a particle size ≤0.074 mm (Al=66.3%, Mg=32.9%). After dry mixing evenly, mix with 70 kg of fused magnesium oxide sand with a particle size of 0.5-5 mm and w(MgO)=98.1%, and 5 kg of phenolic resin and furfural resin mixed binder diluted with alcohol in a roller mixer to form mud. Put the mud into a steel mold and press it into a standard brick blank of 230 mm × 114 mm × 65 mm on a friction brick press with a pressure of 100 MPa. After the blank is left to stand naturally, it is dried in hot air at 180℃ for 24 days. After h, the periclase-magnesium aluminum spinel composite refractory material is obtained.

[0031] XRD analysis revealed that the periclase-magnesia-alumina spinel composite refractory material exhibits periclase as the dominant crystalline phase, comprising approximately 70%, while magnesium alumina spinel serves as the secondary crystalline phase, accounting for approximately 30%. The composite refractory material contains 20.3% Al₂O₃, 78.3% MgO, has an apparent porosity of 12%, and a bulk density of 3.30 g / cm³. 3 The flexural strength at room temperature is 32 MPa, the flexural strength at 600℃ is 19 MPa, the flexural strength at 900℃ is 26 MPa, the flexural strength at 1200℃ is 28 MPa, and the flexural strength at 1400℃ is 37 MPa. Example 7:

[0032] 25 kg of sintered magnesium aluminate spinel fine powder with a particle size ≤0.1 mm, 4 kg of sintered alumina micro powder with a particle size ≤0.01 mm, 1 kg of magnesium carbonate powder with a particle size ≤0.045 mm, 4 kg of metallic aluminum powder with a particle size ≤0.074 mm and Al=99.0%, and 1 kg of magnesium aluminate alloy powder with a particle size ≤0.074 mm (Al=66.3%, Mg=32.9%), were weighed out and dry-mixed evenly. This mixture was then combined with 65 kg of sintered magnesia sand with a particle size of 0.5-4 mm and w(MgO)=99.1% and 5 kg of phenolic resin binder diluted with alcohol in a roller mixer to form a mud. The mud was then placed into a steel mold and formed into standard brick blanks of 230 mm × 114 mm × 65 mm under a hydraulic press at a pressure of 100 MPa. After being left to stand naturally, the blanks were dried in hot air at 180℃ for 12 hours. After h, the periclase-magnesium aluminum spinel composite refractory material is obtained.

[0033] XRD analysis revealed that the periclase-magnesia-alumina spinel composite refractory material exhibits periclase as the dominant crystalline phase, comprising approximately 70%, while magnesium alumina spinel serves as the secondary crystalline phase, accounting for approximately 30%. The composite refractory material contains 25.3% Al₂O₃, 73.9% MgO, has an apparent porosity of 15%, and a bulk density of 3.05 g / cm³. 3 The flexural strength at room temperature is 26 MPa, at 600℃ it is 16 MPa, at 900℃ it is 18 MPa, at 1200℃ it is 17 MPa, and at 1400℃ it is 27 MPa. Example 8:

[0034] Weigh out 20 kg of sintered magnesium aluminate spinel fine powder with a particle size ≤0.1 mm, 9 kg of sintered alumina micro powder with a particle size ≤0.01 mm, 1 kg of lightly calcined magnesium oxide powder with a particle size ≤0.045 mm, 7.5 kg of metallic aluminum powder with a particle size ≤0.074 mm and Al=99.0%, and 2.5 kg of magnesium aluminate alloy powder with a particle size ≤0.074 mm (Al=66.3%, Mg=32.9%). Dry mix them thoroughly, then mix them with 28 kg of fused magnesia sand with a particle size 3-5 mm and w(MgO)=97.3%, 32 kg of sintered magnesia sand with a particle size 0.2-3 mm and w(MgO)=99.1%, and 6 kg of phenolic resin binder diluted with alcohol in a roller mixer to form a mud. The mud is then loaded into a steel mold and molded into 230 mm × 114 mm × 65 mm bricks using a friction brick press at 100 MPa pressure. The standard brick blanks are laid out naturally and then dried with hot air at 200℃ for 12 hours to obtain periclase-magnesium aluminum spinel composite refractory materials.

[0035] XRD analysis revealed that the periclase-magnesia-alumina spinel composite refractory material exhibits periclase as the primary crystalline phase, comprising approximately 60%, while magnesium alumina spinel serves as the secondary crystalline phase, accounting for approximately 35%. The composite refractory material contains 32.3% Al₂O₃, 65.9% MgO, has an apparent porosity of 15%, and a bulk density of 3.18 g / cm³. 3 The flexural strength at room temperature is 35 MPa, the flexural strength at 600℃ is 26 MPa, the flexural strength at 900℃ is 35 MPa, the flexural strength at 1200℃ is 36 MPa, and the flexural strength at 1400℃ is 39 MPa. Example 9:

[0036] Weigh out 15 kg of fused magnesium aluminate spinel fine powder with a particle size ≤0.1 mm, 4 kg of sintered alumina micro powder with a particle size ≤0.01 mm, 1 kg of sintered magnesium powder with a particle size ≤0.045 mm, 7.5 kg of metallic aluminum powder with a particle size ≤0.074 mm and Al=99.0%, and 2.5 kg of magnesium aluminate alloy powder with a particle size ≤0.074 mm (Al=48.9%, Mg=50.3%). After dry mixing evenly, mix with 70 kg of fused white corundum particles with a particle size of 0.5-4 mm and w(Al2O3)=98.3%, and 6 kg of phenolic resin and furfural resin mixed binder diluted with alcohol. Mix in a roller-type sand mixer to form mud. Load the mud into a steel mold and form 230 mm × 114 mm × 65 mm bricks on a friction brick press under a pressure of 100 MPa. mm standard brick blanks are left to stand naturally and then dried with hot air at 200℃ for 24 hours to obtain corundum-magnesium aluminum spinel composite refractory material.

[0037] XRD analysis revealed that the corundum-magnesium aluminum spinel composite refractory material exhibits corundum as the main crystalline phase, comprising approximately 70%; and magnesium aluminum spinel as the secondary crystalline phase, comprising approximately 25%. The composite refractory material contains 90.8% Al₂O₃, 4.2% MgO, has an apparent porosity of 15%, and a bulk density of 3.15 g / cm³. 3 The flexural strength at room temperature is 28 MPa, at 600℃ it is 19 MPa, at 900℃ it is 17 MPa, at 1200℃ it is 23 MPa, and at 1400℃ it is 24 MPa.

[0038] Example 10: Weigh out 11 kg of fused magnesium aluminate spinel fine powder with a particle size ≤0.1 mm, 8 kg of sintered alumina micro powder with a particle size ≤0.01 mm, 1 kg of lightly calcined magnesium oxide powder with a particle size ≤0.045 mm, 7.5 kg of metallic aluminum powder with a particle size ≤0.074 mm and Al=99.0%, and 2.5 kg of magnesium aluminate alloy powder with a particle size ≤0.074 mm (Al=66.3%, Mg=32.9%). After dry mixing evenly, mix with 70 kg of fused magnesium oxide sand with a particle size of 0.5-5 mm and w(MgO)=97.1%, and 5 kg of phenolic resin and furfural resin mixed binder diluted with alcohol. Mix in a roller-type sand mixer to form mud. Put the mud into a steel mold and form 230 mm × 114 mm × 65 mm bricks on a friction brick press with a pressure of 100 MPa. The standard mm brick blanks are left to stand naturally and then dried with hot air at 200℃ for 24 hours to obtain periclase-magnesium aluminum spinel composite refractory material.

[0039] XRD analysis revealed that the periclase-magnesia-alumina spinel composite refractory material exhibits periclase as the dominant crystalline phase, comprising approximately 70%, while magnesium alumina spinel serves as the secondary crystalline phase, accounting for approximately 25%. The composite refractory material contains 24.4% Al₂O₃, 72.2% MgO, has an apparent porosity of 16%, and a bulk density of 3.19 g / cm³. 3 The flexural strength at room temperature is 28 MPa, at 600℃ it is 23 MPa, at 900℃ it is 26 MPa, at 1200℃ it is 31 MPa, and at 1400℃ it is 34 MPa.

Claims

1. A multi-metal composite magnesium-aluminum spinel refractory material, characterized in that: The magnesium-aluminum spinel refractory material is made of one of SiC-MgAl2O4, Al2O3-MgAl2O4, or MgO-MgAl2O4. The main component of the magnesium-aluminum spinel refractory material is composed of particles of SiC, Al2O3, and MgO as aggregates and a mixture of fine and micro powders constituting MgAl2O4 as the matrix. The component contains metallic Al and Al-Mg alloys. The particle size range of the aggregates is 0.2-5 mm; the particle size of the matrix is ​​≤0.1 mm; the purity of metallic Al and Al-Mg alloys is ≥99.0%, the particle size is ≤0.074 mm, and the total content is 4%-10% of the total mass of the solid components of the refractory material, with a mass ratio of 1:1-4:

1. The magnesium-aluminum spinel refractory material uses a liquid binder, added at 3%-6% of the total mass of the solid powder. Prepared by hot air drying at 150-200℃ for 8-24 hours, without high-temperature firing; the aforementioned multi-metal composite magnesium-aluminum spinel refractory material is a non-firing refractory product with a fixed shape after molding, which can be used as a high-temperature furnace lining without high-temperature firing treatment above 1200℃; the aforementioned magnesium-aluminum spinel refractory material is a composite refractory material with α-SiC or corundum or periclase as the main crystalline phase and magnesium-aluminum spinel as the secondary crystalline phase; the sum of the mass fractions of SiC, MgO and Al2O3 in the aforementioned magnesium-aluminum spinel refractory material is greater than or equal to 95%, the apparent porosity is 6% to 16%, and the bulk density is 2.60 to 3.30 g / cm³. 3 The flexural strength at room temperature is 25~40 MPa, the flexural strength at 600~1200℃ is 15~30 MPa, and the flexural strength at 1400℃ is 25~40 MPa.

2. The magnesium-aluminum spinel composite refractory material as described in claim 1, characterized in that: The magnesium aluminum spinel is a secondary crystalline phase, and its content in the total mineral phase composition of the magnesium aluminum spinel-containing refractory material after high-temperature treatment at 1400~1600℃ is 15%~40%.

3. The magnesium-aluminum spinel composite refractory material as described in claim 1, characterized in that: The content of α-SiC, corundum, and periclase as the main crystalline phases in the total mineral phase composition of magnesium-aluminum spinel refractory materials after high-temperature treatment at 1400~1600℃ is not less than 50%.

4. The magnesium-aluminum spinel composite refractory material as described in claim 1, characterized in that: The particles containing SiC, Al2O3, and MgO in the aggregate are industrial-grade refractory materials, and are one of fused silicon carbide, fused white corundum, sintered corundum, fused magnesia, and sintered magnesia.

5. The magnesium-aluminum spinel composite refractory material as described in claim 1, characterized in that: The matrix is ​​an industrial raw material composed of MgAl2O4, MgO, and Al2O3, or a precursor of organic or inorganic salts that can generate MgO and Al2O3 at high temperatures.

6. The magnesium-aluminum spinel composite refractory material as described in claim 1, characterized in that: The liquid binder is one or two of the organic resins phenolic resin and furfural resin, diluted with anhydrous ethanol; the liquid binder does not contain free water.

7. A method for preparing a multi-metal composite magnesium-aluminum spinel refractory material according to any one of claims 1-6, characterized in that: The steps are as follows: The first step involves mixing industrial-grade raw materials MgAl2O4 or MgO and Al2O3, or precursor powders of organic or inorganic salts that can generate MgO and Al2O3 at high temperatures, with industrial-grade raw materials metallic Al and Al-Mg alloy powder with a purity of ≥99.0% and a particle size of ≤0.074mm, with corundum or zirconia grinding balls in a mixer until uniformly mixed. The grinding residue is then sieved out to prepare a mixed powder. The second step is to weigh a certain proportion of particles of SiC, Al2O3, and MgO with a particle size range of less than or equal to 5 mm and greater than 0.2 mm, pour them into a mixer, and mix them evenly with the liquid binder. The third step is to add the mixed powder prepared in the first step to the aggregate containing the binder in the second step in a certain proportion, stir evenly, and prepare mud. The fourth step is to put the clay into a steel mold and shape it on a friction brick press, hydraulic press or vibration molding machine with a pressure of not less than 50MPa. After demolding, a refractory material blank is obtained. The fifth step is to dry the blank with hot air at 150~200℃ for 8~24 hours to obtain a multi-metal composite magnesium aluminum spinel refractory material.