Magnesium-aluminum-carbon brick with long service life and low cost and preparation method thereof

Abstract

The invention discloses a magnesia-alumina-carbon brick with long service life and low cost and a preparation method thereof, and relates to the technical field of refractory materials, the magnesia-alumina-carbon brick comprises the following raw material components by mass: 25-55% of waste magnesia-alumina-carbon brick, 20-40% of fused magnesia, 15-40% of intermediate frequency furnace charge, 5-10% of graphite, 5-9% of tabular corundum, and 3% of a binder, the waste magnesia-alumina-carbon brick and the medium-frequency furnace burden are used as raw materials, so that the oxidation resistance, slag corrosion resistance, thermal shock resistance and scouring resistance of the magnesia-alumina-carbon brick are improved, the cost is reduced, and the service life is prolonged.

Description

Technical Field

[0001] This invention belongs to the field of refractory materials technology, and specifically relates to a long-life, low-cost magnesium-aluminate-carbon brick and its preparation method. Background Technology

[0002] As a critical container in the steelmaking process, the performance of the ladle's wall bricks directly affects its service life and steelmaking costs. With the continuous development of the steel industry, the performance requirements for ladle wall bricks are becoming increasingly stringent.

[0003] Currently, common steel ladle wall bricks have some problems in use. For example, although traditional magnesia-alumina-carbon, alumina-magnesia-carbon, and magnesia-carbon wall bricks have certain refractory properties, their oxidation resistance, erosion resistance, and thermal shock stability are difficult to meet the requirements for long-term and efficient use when facing complex working conditions such as high temperature, molten steel scouring, and slag erosion. Moreover, the raw materials for the preparation of these traditional wall bricks often require high-temperature firing, which not only consumes a lot of energy and causes great environmental pollution, but also leads to high raw material costs.

[0004] For example, patent document CN119285334A discloses a long-life steel-clad magnesia-alumina-carbon clad wall brick and its preparation method, which is made from the following raw materials in the following mass fractions: 29%-63% magnesia-alumina-carbon brick waste, 10%-20% magnesia-carbon brick waste, 10%-25% fused magnesia, 2%-5% white corundum, 3%-5% α-alumina micro powder, 3% liquid phenolic resin, 1-3% fused magnesia dust removal powder, 0.1%-3% CeSi2-SiC multiphase material, 1%-3% high-temperature asphalt, and 1%-5% graphite; wherein the carbon content of the high-temperature asphalt is ≥45%, the carbon content of the graphite is ≥95%, and the magnesium oxide content in the fused magnesia is ≥95wt%. This invention makes extensive and effective use of waste bricks, greatly reduces raw material costs, and lays an excellent foundation for coping with the current severe steel industry situation.

[0005] However, while some wall-mounting bricks made from waste bricks can reduce raw material costs and pollution during the firing process, the complex composition and inconsistent performance of waste bricks inevitably lead to a decline in the overall performance of the wall-mounting bricks. In actual use, problems such as peeling and cracking are likely to occur, which greatly shortens the service life of the ladle and increases maintenance costs and downtime during the steelmaking process.

[0006] In view of the above technical challenges, there is an urgent need to provide a magnesium aluminate carbon brick that has a long lifespan, low cost, environmentally friendly production process, and high oxidation resistance, erosion resistance and thermal shock stability. Summary of the Invention

[0007] To address the problems existing in current magnesium aluminate carbon bricks, this invention provides a long-life, low-cost magnesium aluminate carbon brick and its preparation method. By optimizing the raw material formula and effectively utilizing recycled materials, the oxidation resistance, thermal shock resistance, erosion resistance, scour resistance, and service life of magnesium aluminate carbon bricks are significantly improved.

[0008] The solution adopted by this invention to solve its technical problem is: a long-life, low-cost magnesia-alumina-carbon brick, wherein the mass percentage of each raw material component in the magnesia-alumina-carbon brick is as follows: 25-55% magnesia-alumina-carbon brick waste brick, 20-40% fused magnesia, 15-40% medium-frequency furnace charge, 5-10% graphite, 5-9% tabular corundum, and 3% binder.

[0009] Furthermore, the mass percentages of each raw material component in the magnesia-alumina-carbon brick are as follows: 35-45% waste magnesia-alumina-carbon brick, 20-35% fused magnesia, 15-30% medium-frequency furnace charge, 7-10% graphite, 5-8% tabular corundum, and 3% binder.

[0010] Furthermore, the mass percentages of each raw material component in the magnesia-alumina-carbon brick are as follows: 38% waste magnesia-alumina-carbon brick, 25% fused magnesia, 20% medium-frequency furnace charge, 8% graphite, 6% tabular corundum, and 3% binder.

[0011] Furthermore, the waste magnesium-aluminum-carbon bricks include: waste magnesium-aluminum-carbon bricks with a particle size of 5-3 mm and waste magnesium-aluminum-carbon bricks with a particle size of 3-1 mm, wherein the mass ratio of waste magnesium-aluminum-carbon bricks with a particle size of 5-3 mm to waste magnesium-aluminum-carbon bricks with a particle size of 3-1 mm is 1.1-1.3:1; the sum of the contents of MgO, Al2O3 and C in the waste magnesium-aluminum-carbon bricks is ≥88wt%.

[0012] Further, the fused magnesia comprises: fused magnesia with a particle size of 3-1 mm, fused magnesia with a particle size of 1-0 mm, and fused magnesia with a particle size of 200 mesh, wherein the mass ratio of the fused magnesia with a particle size of 3-1 mm, the fused magnesia with a particle size of 1-0 mm, and the fused magnesia with a particle size of 200 mesh is 1:1:1.8-2.3, and the fused magnesia contains MgO content ≥96wt%.

[0013] Further, the medium-frequency furnace charge includes: medium-frequency furnace charge with a particle size of 5-3mm, medium-frequency furnace charge with a particle size of 3-1mm, and medium-frequency furnace charge with a particle size of 1-0mm; wherein the mass ratio of the medium-frequency furnace charge with a particle size of 5-3mm, the medium-frequency furnace charge with a particle size of 3-1mm, and the medium-frequency furnace charge with a particle size of 1-0mm is 1:1:1 to 1.5, and the Al2O3 content in the medium-frequency furnace charge is ≥80wt%.

[0014] Further, the tabular alumina includes: tabular alumina with a particle size of 1-0 mm and tabular alumina with a particle size of 200 mesh; wherein the mass ratio of tabular alumina with a particle size of 1-0 mm to tabular alumina with a particle size of 200 mesh is 1:1.2-1.5.

[0015] Furthermore, the binder is a liquid phenolic resin with a solid content ≥75%.

[0016] This invention also provides a method for preparing long-life, low-cost magnesium-aluminate-carbon bricks, comprising the following steps:

[0017] S1. Weigh out the waste magnesia-alumina-carbon bricks, medium-frequency furnace charge, fused magnesia, tabular corundum, liquid phenolic resin and graphite in sequence according to the mass percentage. First, mix the waste magnesia-alumina-carbon bricks, medium-frequency furnace charge, fused magnesia and tabular corundum. Then add liquid phenolic resin and mix. Then add graphite and mix. Finally, obtain the mixture.

[0018] S2. Fine powder is obtained by mixing fused magnesia and tabular corundum.

[0019] S3. Add the fine powder obtained in S2 to the mixture obtained in S1, then put it into the mold of the brick press and press it into shape. After heat treatment in the heat treatment kiln, long-life, low-cost magnesium aluminum carbon bricks are obtained.

[0020] Furthermore, the brick press is a 630T electric screw brick press; during the heat treatment in the heat treatment kiln, the internal temperature of the heat treatment kiln is 180-240℃, and the heat treatment time is 14-30h.

[0021] Compared with the prior art, the beneficial effects of the present invention are:

[0022] 1. This invention incorporates waste magnesia-alumina-carbon bricks and medium-frequency furnace charge into magnesia-alumina-carbon bricks, reducing the use of raw materials such as fused magnesia and white corundum. On the one hand, this achieves resource recycling, reduces the exploitation of primary refractory materials, aligns with sustainable development requirements, helps alleviate resource shortages, and reduces environmental pollution. On the other hand, it offers a price advantage; while ensuring brick performance, the rational use of waste materials reduces production costs and improves overall stability. Medium-frequency furnace charge generally possesses good erosion resistance; introducing it into magnesia-alumina-carbon bricks makes the bricks more resistant to erosion from high-temperature molten slag and molten metal, extending their service life. In steelmaking, magnesia-alumina-carbon bricks containing medium-frequency furnace charge better resist the erosion of harmful components in molten steel and slag, reducing brick damage. Furthermore, the addition of medium-frequency furnace charge improves the thermal shock resistance of magnesia-alumina-carbon bricks. When facing rapid temperature changes, the interaction between the medium-frequency furnace charge and other brick components alleviates thermal stress damage, enhances the overall stability of the brick, and reduces the likelihood of cracking and spalling.

[0023] 2. The magnesium aluminate carbon brick and its preparation method provided by this invention, after laboratory performance testing, show that the magnesium aluminate carbon brick's thermal shock resistance, slag penetration resistance, and room temperature compressive strength all meet the performance indicators, exhibiting excellent resistance to slag erosion, scour, and oxidation. The application of this invention improves the service life of magnesium aluminate carbon bricks, enhances the overall stability of the brick body, reduces costs, and increases market competitiveness.

[0024] In summary, this invention improves the oxidation resistance, slag erosion resistance, thermal shock resistance, and erosion resistance of magnesia-alumina-carbon bricks by using waste magnesia-alumina-carbon bricks and medium-frequency furnace charge as raw materials, thereby reducing costs and extending service life. Detailed Implementation

[0025] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0026] This invention provides a technical solution for long-life, low-cost magnesium-aluminate-carbon bricks and their preparation method:

[0027] A long-life, low-cost magnesia-alumina-carbon brick, wherein the mass percentages of each raw material component in the magnesia-alumina-carbon brick are as follows: 25-55% magnesia-alumina-carbon brick waste brick, 20-40% fused magnesia, 15-40% medium-frequency furnace charge, 5-10% graphite, 5-9% tabular corundum, and 3% binder.

[0028] This invention incorporates waste magnesia-alumina-carbon bricks and medium-frequency furnace charge into magnesia-alumina-carbon bricks, reducing the use of raw materials such as fused magnesia and white corundum. On the one hand, it achieves resource recycling, reduces the mining of primary refractory material resources, meets the requirements of sustainable development, helps alleviate the pressure of resource shortages, and reduces environmental pollution. On the other hand, it is more cost-effective. Under the premise of ensuring the performance of the brick, the rational use of waste materials can reduce production costs and improve overall stability.

[0029] This invention introduces waste magnesium aluminate carbon bricks. After recycling, the porosity of the waste bricks is reduced, decreasing the contact between oxygen and the internal carbon source and improving oxidation resistance. At the same time, the bulk density and room temperature compressive strength of the recycled bricks are superior to some new bricks, and the cost is significantly reduced. In addition, the sintered magnesium aluminate spinel and other components in the waste bricks can enhance the density of the brick body, inhibit slag penetration, and extend the service life of magnesium aluminate carbon bricks.

[0030] The carbon in the magnesium-aluminum-carbon brick waste introduced in this invention works synergistically with the carbon network in the liquid phenolic resin to further reduce oxygen permeation and enhance oxidation resistance; at the same time, the dense structure of the waste brick and the resin binder work together to improve the overall strength of the brick.

[0031] Medium-frequency furnace charge generally has good erosion resistance. Introducing it into magnesia-alumina-carbon bricks can make the bricks more resistant to erosion by high-temperature molten slag and molten metal, thus extending their service life. In steelmaking, magnesia-alumina-carbon bricks containing medium-frequency furnace charge can better resist the erosion of harmful components in molten steel and slag, reducing brick damage. Furthermore, the addition of medium-frequency furnace charge can improve the thermal shock resistance of magnesia-alumina-carbon bricks. When faced with rapid temperature changes, the interaction between the medium-frequency furnace charge and other components of the brick can alleviate the damage of thermal stress to the brick, enhance the overall stability of the brick, and make it less prone to cracking and spalling.

[0032] As a preferred embodiment of the present invention, the mass percentages of each raw material component in the magnesia-alumina-carbon brick are as follows: 35-45% waste magnesia-alumina-carbon brick, 20-35% fused magnesia, 15-30% medium-frequency furnace charge, 7-10% graphite, 5-8% tabular corundum, and 3% binder.

[0033] In a preferred embodiment of the present invention, the waste magnesium-aluminum-carbon bricks include: waste magnesium-aluminum-carbon bricks with a particle size of 5-3 mm and waste magnesium-aluminum-carbon bricks with a particle size of 3-1 mm, wherein the mass ratio of the waste magnesium-aluminum-carbon bricks with a particle size of 5-3 mm to the waste magnesium-aluminum-carbon bricks with a particle size of 3-1 mm is 1.1-1.3:1; the sum of the contents of MgO, Al2O3 and C in the waste magnesium-aluminum-carbon bricks is ≥88wt%.

[0034] The brick is constructed using a combination of 5-3mm and 3-1mm aggregates. This optimized particle size distribution improves the bulk density and enhances the brick's compactness and thermal shock resistance. A suitable mass ratio balances structural strength and toughness, enhancing impact and spalling resistance. The two aggregates are mixed at a mass ratio of 1.1–1.3:1, ensuring that large particles form a stable skeleton while small particles fully fill the gaps. This avoids excessively weakening the supporting role of large particles or causing a decrease in matrix fluidity or a loose structure due to an excessive number of small particles. This ratio helps to improve the brick's toughness and impact resistance while maintaining its strength. The high content of the main components effectively ensures high-temperature stability, erosion resistance, and oxidation resistance. The reasonable particle ratio helps to form a dense surface structure, reducing the penetration channels of molten slag or metal, thereby improving the brick's erosion resistance and extending its service life. MgO and Al2O3 are the main high-temperature stable phases in magnesia-alumina-carbon bricks. They can form high-melting-point phases such as magnesia-alumina spinel at high temperatures, which can block pores through volume expansion, enhancing compactness and slag penetration resistance. Simultaneously, the low impurity content further improves the refractory performance. This integrated design not only significantly improves the service life of magnesium-aluminate-carbon bricks, but also reduces production costs through waste recycling, meeting the requirements of green manufacturing and sustainable development.

[0035] In a preferred embodiment of the present invention, the fused magnesia comprises: fused magnesia with a particle size of 3-1 mm, fused magnesia with a particle size of 1-0 mm, and fused magnesia with a particle size of 200 mesh, wherein the mass ratio of the fused magnesia with a particle size of 3-1 mm, the fused magnesia with a particle size of 1-0 mm, and the fused magnesia with a particle size of 200 mesh is 1:1:1.8-2.3, and the MgO content in the fused magnesia is ≥96wt%.

[0036] This invention uses high-quality 200-mesh fused magnesia, which can fully fill the gaps between coarse and medium particles, significantly reduce porosity, and improve the density and mechanical strength of the brick. At the same time, the finer fused magnesia particles help to form a more uniform and dense matrix structure, reduce slag penetration channels, and thus improve erosion resistance. The high MgO content helps to form a stable periclase phase structure, maintain good volume stability and structural strength at high temperatures, and extend the service life of the brick.

[0037] In a preferred embodiment of the present invention, the medium-frequency furnace charge comprises: medium-frequency furnace charge with a particle size of 5-3 mm, medium-frequency furnace charge with a particle size of 3-1 mm, and medium-frequency furnace charge with a particle size of 1-0 mm; wherein the mass ratio of the medium-frequency furnace charge with a particle size of 5-3 mm, the medium-frequency furnace charge with a particle size of 3-1 mm, and the medium-frequency furnace charge with a particle size of 1-0 mm is 1:1:1 to 1.5, and the Al2O3 content in the medium-frequency furnace charge is ≥80wt%.

[0038] The medium-frequency furnace charge utilizes a three-stage particle size combination of 5-3mm, 3-1mm, and 1-0mm, scientifically proportioned in a mass ratio of 1:1:1 to 1.5. Combined with its high Al2O3 content of 80wt%, it achieves optimized particle packing and structural density, significantly improving the mechanical strength, thermal shock resistance, and erosion resistance of magnesia-alumina-carbon bricks. The increased proportion of fine particles helps form a more uniform and dense matrix structure, reducing slag penetration channels and thus improving erosion resistance. At high temperatures, fine particles also facilitate the sintering reaction, promoting interparticle bonding and enhancing the overall strength and erosion resistance of the brick. This design not only effectively reduces porosity and enhances volume stability and structural strength at high temperatures but also extends the service life of the brick in high-temperature environments by reducing the content of low-melting-point impurities. Simultaneously, it considers production cost control and green manufacturing concepts, meeting the development needs of high-performance refractory materials.

[0039] In a preferred embodiment of the present invention, the tabular alumina includes: tabular alumina with a particle size of 1-0 mm and tabular alumina with a particle size of 200 mesh; wherein the mass ratio of the tabular alumina with a particle size of 1-0 mm to the tabular alumina with a particle size of 200 mesh is 1:1.2-1.5.

[0040] This invention introduces tabular corundum, and the reasonable particle size distribution achieves close particle packing, improving the density and thermal shock resistance of the brick. Coarse particles (1-0 mm) provide skeletal support, while fine particles (200 mesh) fill the gaps, optimizing the microstructure and thus enhancing the mechanical strength and erosion resistance of the brick. The appropriate mass ratio ensures structural stability while also taking into account the toughness and anti-stripping properties of the material, effectively extending the service life of the brick in high-temperature environments. In addition, the high purity and excellent high-temperature performance of tabular corundum not only improve the high-temperature resistance and oxidation resistance of the brick, but also further enhances its resistance to slag erosion and volume stability by reducing the content of low-melting-point impurities.

[0041] In this invention, tabular corundum and fused magnesia react synergistically at high temperatures to form magnesium aluminum spinel, which produces a volume expansion effect that can block pores and enhance density; at the same time, it reduces the coefficient of thermal expansion and improves thermal shock resistance and high temperature stability.

[0042] In a preferred embodiment of the present invention, the binder is liquid phenolic resin with a solid content ≥75%. This design not only optimizes the production process and product performance of magnesium-aluminum-carbon bricks, but also reduces resin usage and lowers production costs. Furthermore, this resin exhibits good environmental performance, reducing environmental pollution.

[0043] This invention also provides a method for preparing long-life, low-cost magnesium-aluminate-carbon bricks, comprising the following steps:

[0044] S1. Weigh out the waste magnesia-alumina-carbon bricks, medium-frequency furnace charge, fused magnesia, tabular corundum, liquid phenolic resin and graphite in sequence according to the mass percentage. First, mix the waste magnesia-alumina-carbon bricks, medium-frequency furnace charge, fused magnesia and tabular corundum. Then add liquid phenolic resin and mix. Then add graphite and mix. Finally, obtain the mixture.

[0045] S2. Fine powder is obtained by mixing fused magnesia and tabular corundum.

[0046] S3. Add the fine powder obtained in S2 to the mixture obtained in S1, then put it into the mold of the brick press and press it into shape. After heat treatment in the heat treatment kiln, long-life, low-cost magnesium aluminum carbon bricks are obtained.

[0047] In a preferred embodiment of the present invention, the brick press is a 630T electric screw brick press; during heat treatment in the heat treatment kiln, the temperature inside the heat treatment kiln is 180-240℃, and the heat treatment time is 14-30h.

[0048] Specific implementation examples:

[0049] The following provides a specific embodiment of the present invention: a long-life, low-cost magnesium-aluminum-carbon brick and its preparation method.

[0050] Example 1:

[0051] This embodiment provides a long-life, low-cost magnesia-alumina-carbon brick, with the following mass percentages of each raw material component: 38% magnesia-alumina-carbon brick waste, of which 20% is magnesia-alumina-carbon brick waste with a particle size of 5-3mm and 18% is magnesia-alumina-carbon brick waste with a particle size of 3-1mm; 25% fused magnesia, of which 6% is fused magnesia with a particle size of 3-1mm, 6% is fused magnesia with a particle size of 1-0mm, and 13% is fused magnesia with a particle size of 200 mesh; 20% medium-frequency furnace charge, of which 6% is medium-frequency furnace charge with a particle size of 5-3mm, 6% is medium-frequency furnace charge with a particle size of 3-1mm, and 8% is medium-frequency furnace charge with a particle size of 1-0mm; 8% graphite; 6% tabular corundum, of which 2.5% is tabular corundum with a particle size of 1-0mm and 3.5% is tabular corundum with a particle size of 200 mesh; and 3% liquid phenolic resin.

[0052] Based on the above-mentioned long-life, low-cost magnesium-aluminate-carbon bricks, the present invention also provides a method for preparing long-life, low-cost magnesium-aluminate-carbon bricks, comprising the following steps:

[0053] S1. Weigh out the following materials in order of mass percentage: 5-3mm magnesia-alumina-carbon brick waste, 3-1mm magnesia-alumina-carbon brick waste, 5-3mm medium-frequency furnace charge, 3-1mm medium-frequency furnace charge, 1-0mm medium-frequency furnace charge, 3-1mm fused magnesia, 1-0mm fused magnesia, 1-0mm tabular corundum, liquid phenolic resin, and graphite. First, mix the magnesia-alumina-carbon brick waste, medium-frequency furnace charge, fused magnesia, and tabular corundum. Then, add liquid phenolic resin and mix. Next, add graphite and mix again to obtain the final mixture.

[0054] S2. Fine powder is obtained by mixing fused magnesia with a particle size of 200 mesh and tabular corundum with a particle size of 200 mesh.

[0055] S3. Add the fine powder obtained in S2 to the mixture obtained in S1, then put it into the mold of the brick press and press it into shape. After heat treatment in the heat treatment kiln, long-life, low-cost magnesium aluminum carbon bricks are obtained.

[0056] In the above steps, the brick press used is a 630T electric screw brick press; during heat treatment in the heat treatment kiln, the temperature inside the heat treatment kiln is 180-240℃, and the heat treatment time is 14-30h.

[0057] Example 2:

[0058] This embodiment provides a long-life, low-cost magnesia-alumina-carbon brick, with the following mass percentages of each raw material component: 50% magnesia-alumina-carbon brick waste, of which 27% is magnesia-alumina-carbon brick waste with a particle size of 5-3mm and 23% is magnesia-alumina-carbon brick waste with a particle size of 3-1mm; 20% fused magnesia, of which 5% is fused magnesia with a particle size of 3-1mm, 5% is fused magnesia with a particle size of 1-0mm, and 10% is fused magnesia with a particle size of 200 mesh; 15% medium-frequency furnace charge, of which 5% is medium-frequency furnace charge with a particle size of 5-3mm, 5% is medium-frequency furnace charge with a particle size of 3-1mm, and 5% is medium-frequency furnace charge with a particle size of 1-0mm; 7% graphite; 5% tabular corundum, of which 2% is tabular corundum with a particle size of 1-0mm and 3% is tabular corundum with a particle size of 200 mesh; and 3% liquid phenolic resin. Based on the above-mentioned long-life, low-cost magnesium-aluminate-carbon brick, its preparation method is the same as in Example 1.

[0059] Example 3:

[0060] This embodiment provides a long-life, low-cost magnesia-alumina-carbon brick, with the following mass percentages of each raw material component: 25% magnesia-alumina-carbon brick waste, of which 14% is magnesia-alumina-carbon brick waste with a particle size of 5-3mm and 11% is magnesia-alumina-carbon brick waste with a particle size of 3-1mm; 23% fused magnesia, of which 6% is fused magnesia with a particle size of 3-1mm, 6% is fused magnesia with a particle size of 1-0mm, and 11% is fused magnesia with a particle size of 200 mesh; 30% medium-frequency furnace charge, of which 9% is medium-frequency furnace charge with a particle size of 5-3mm, 9% is medium-frequency furnace charge with a particle size of 3-1mm, and 12% is medium-frequency furnace charge with a particle size of 1-0mm; 10% graphite; 9% tabular corundum, of which 4% is tabular corundum with a particle size of 1-0mm and 5% is tabular corundum with a particle size of 200 mesh; and 3% liquid phenolic resin. Based on the above-mentioned long-life, low-cost magnesium-aluminate-carbon brick, its preparation method is the same as in Example 1.

[0061] Example 4:

[0062] This embodiment provides a long-life, low-cost magnesia-alumina-carbon brick. The mass percentages of each raw material component are as follows: 25% waste magnesia-alumina-carbon bricks, of which 13.1% are waste magnesia-alumina-carbon bricks with a particle size of 5-3mm and 11.9% are waste magnesia-alumina-carbon bricks with a particle size of 3-1mm; 40% fused magnesia, of which 9.3% are fused magnesia with a particle size of 3-1mm and 9.3% are fused magnesia with a particle size of 1-0mm. The composition of the magnesia-alumina-carbon brick is as follows: 21.4% is 200-mesh fused magnesia; 19% is medium-frequency induction furnace charge, of which 5.5% is 5-3mm particle size medium-frequency induction furnace charge, 5.5% is 3-1mm particle size medium-frequency induction furnace charge, and 8% is 1-0mm particle size medium-frequency induction furnace charge; 5% is graphite; 8% is tabular corundum, of which 3.5% is 1-0mm tabular corundum and 4.5% is 200-mesh tabular corundum; and 3% is liquid phenolic resin. Based on the above, a long-life, low-cost magnesia-alumina-carbon brick is prepared using the same method as in Example 1.

[0063] Example 5:

[0064] This embodiment provides a long-life, low-cost magnesia-alumina-carbon brick, with the following mass percentages of each raw material component: 25% magnesia-alumina-carbon brick waste, of which 14.1% is magnesia-alumina-carbon brick waste with a particle size of 5-3mm and 10.9% is magnesia-alumina-carbon brick waste with a particle size of 3-1mm; 20% fused magnesia, of which 5% is fused magnesia with a particle size of 3-1mm, 5% is fused magnesia with a particle size of 1-0mm, and 10% is fused magnesia with a particle size of 200 mesh; 40% medium-frequency furnace charge, of which 12% is medium-frequency furnace charge with a particle size of 5-3mm, 12% is medium-frequency furnace charge with a particle size of 3-1mm, and 16% is medium-frequency furnace charge with a particle size of 1-0mm; 7% graphite; 5% tabular corundum, of which 2% is tabular corundum with a particle size of 1-0mm and 3% is tabular corundum with a particle size of 200 mesh; and 3% liquid phenolic resin. Based on the above-mentioned long-life, low-cost magnesium-aluminate-carbon brick, its preparation method is the same as in Example 1.

[0065] Example 6:

[0066] This embodiment provides a long-life, low-cost magnesia-alumina-carbon brick, with the following mass percentages of each raw material component: 35% magnesia-alumina-carbon brick waste, of which 19% is magnesia-alumina-carbon brick waste with a particle size of 5-3mm and 16% is magnesia-alumina-carbon brick waste with a particle size of 3-1mm; 35% fused magnesia, of which 9.2% is fused magnesia with a particle size of 3-1mm, 9.2% is fused magnesia with a particle size of 1-0mm, and 16.6% is fused magnesia with a particle size of 200 mesh; 15% medium-frequency furnace charge, of which 5% is medium-frequency furnace charge with a particle size of 5-3mm, 5% is medium-frequency furnace charge with a particle size of 3-1mm, and 5% is medium-frequency furnace charge with a particle size of 1-0mm; 7% graphite; 5% tabular corundum, of which 2% is tabular corundum with a particle size of 1-0mm and 3% is tabular corundum with a particle size of 200 mesh; and 3% liquid phenolic resin. Based on the above-mentioned long-life, low-cost magnesium-aluminate-carbon brick, its preparation method is the same as in Example 1.

[0067] Example 7:

[0068] This embodiment provides a long-life, low-cost magnesia-alumina-carbon brick, with the following mass percentages of each raw material component: 45% magnesia-alumina-carbon brick waste, of which 25% is magnesia-alumina-carbon brick waste with a particle size of 5-3mm and 20% is magnesia-alumina-carbon brick waste with a particle size of 3-1mm; 27% fused magnesia, of which 7% is fused magnesia with a particle size of 3-1mm, 7% is fused magnesia with a particle size of 1-0mm, and 13% is fused magnesia with a particle size of 200 mesh; 15% medium-frequency furnace charge, of which 5% is medium-frequency furnace charge with a particle size of 5-3mm, 5% is medium-frequency furnace charge with a particle size of 3-1mm, and 5% is medium-frequency furnace charge with a particle size of 1-0mm; 5% graphite; 5% tabular corundum, of which 2% is tabular corundum with a particle size of 1-0mm and 3% is tabular corundum with a particle size of 200 mesh; and 3% liquid phenolic resin. Based on the above-mentioned long-life, low-cost magnesium-aluminate-carbon brick, its preparation method is the same as in Example 1.

[0069] Comparative Example 1:

[0070] This comparative example provides a long-life, low-cost magnesia-alumina-carbon brick. The mass percentages of each raw material component are as follows: fused magnesia 25%, of which 6% is fused magnesia with a particle size of 3-1mm, 6% is fused magnesia with a particle size of 1-0mm, and 13% is fused magnesia with a particle size of 200 mesh; medium-frequency furnace charge 58%, of which 18% is medium-frequency furnace charge with a particle size of 5-3mm, 18% is medium-frequency furnace charge with a particle size of 3-1mm, and 22% is medium-frequency furnace charge with a particle size of 1-0mm; graphite 8%; tabular corundum 6%, of which 2.5% is tabular corundum with a particle size of 1-0mm and 3.5% is tabular corundum with a particle size of 200 mesh; and liquid phenolic resin 3%. Based on the above-mentioned long-life, low-cost magnesia-alumina-carbon brick, its preparation method is the same as in Example 1. This comparative example does not contain waste magnesia-alumina-carbon bricks.

[0071] Comparative Example 2:

[0072] This comparative example provides a long-life, low-cost magnesia-alumina-carbon brick. The mass percentages of each raw material component are as follows: 58% waste magnesia-alumina-carbon brick, of which 31% is waste magnesia-alumina-carbon brick with a particle size of 5-3mm and 27% is waste magnesia-alumina-carbon brick with a particle size of 3-1mm; 25% fused magnesia, of which 6% is fused magnesia with a particle size of 3-1mm, 6% is fused magnesia with a particle size of 1-0mm, and 13% is fused magnesia with a particle size of 200 mesh; 8% graphite; 6% tabular corundum, of which 2.5% is tabular corundum with a particle size of 1-0mm and 3.5% is tabular corundum with a particle size of 200 mesh; and 3% liquid phenolic resin. Based on the above-mentioned long-life, low-cost magnesia-alumina-carbon brick, its preparation method is the same as in Example 1. This comparative example does not contain medium-frequency furnace charge.

[0073] The present invention tested the magnesium-aluminate-carbon bricks prepared by different proportions of Examples 1-7 and Comparative Examples 1-2, and conducted qualification tests on their room temperature compressive strength, bulk density, apparent porosity, slag permeability resistance index, and thermal shock resistance. The performance test results are shown in Table 1.

[0074] Table 1. Test results of Examples 1-7 and Comparative Examples 1-2

[0075]

[0076] Comparative Example 1 is based on Example 1, but the addition of magnesia-alumina-carbon brick waste bricks is removed, and the medium-frequency furnace charge is increased accordingly. As can be seen from Table 1, compared with Example 1, Comparative Example 1 has a lower bulk density, higher apparent porosity and slag penetration resistance index, significantly lower compressive strength, and significantly lower thermal shock resistance, which are significantly lower than the test results of Example 1.

[0077] Comparative Example 2 is based on Example 1, but the addition of medium-frequency furnace charge is cancelled and the waste magnesia-alumina-carbon brick is added accordingly. As can be seen from Table 1, compared with Example 1, Comparative Example 2 has a lower bulk density, higher apparent porosity and slag penetration resistance index, significantly lower compressive strength, and significantly lower thermal shock resistance, which are significantly lower than the test results of Example 1.

[0078] In summary, the present invention introduces waste magnesia-alumina-carbon bricks and medium-frequency furnace charge into magnesia-alumina-carbon bricks, which has the characteristics of strong thermal shock resistance, excellent resistance to molten slag penetration, high anti-stripping performance and strong resistance to slag corrosion. Moreover, it can also reduce the raw material cost of magnesia-alumina-carbon bricks, extend the service life of magnesia-alumina-carbon bricks, and improve market competitiveness.

[0079] The above description is only a preferred embodiment of the present invention and does not limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A long life, low cost magnesia-alumina-carbon brick characterized by: The mass percentages of each raw material component in the magnesia-alumina-carbon brick are as follows: 25-55% waste magnesia-alumina-carbon brick, 20-40% fused magnesia, 15-40% medium-frequency furnace charge, 5-10% graphite, 5-9% tabular corundum, and 3% binder.

2. The long life, low cost magnesia-alumina-carbon brick according to claim 1, characterized in that: The mass percentages of each raw material component in the magnesia-alumina-carbon brick are as follows: 35-45% waste magnesia-alumina-carbon brick, 20-35% fused magnesia, 15-30% medium-frequency furnace charge, 7-10% graphite, 5-8% tabular corundum, and 3% binder.

3. The long life, low cost magnesia-alumina-carbon brick according to claim 1, characterized in that: The mass percentages of each raw material component in the magnesia-alumina-carbon brick are as follows: 38% waste magnesia-alumina-carbon brick, 25% fused magnesia, 20% medium-frequency furnace charge, 8% graphite, 6% tabular corundum, and 3% binder.

4. The long life, low cost magnesia-alumina-carbon brick according to claim 1, characterized by: The waste magnesium-aluminate-carbon bricks include: Waste magnesia-alumina-carbon bricks with a particle size of 5-3mm and waste magnesia-alumina-carbon bricks with a particle size of 3-1mm. The mass ratio of 5-3mm magnesia-alumina-carbon brick waste to 3-1mm magnesia-alumina-carbon brick waste is 1.1-1.3:

1. The total content of MgO, Al2O3 and C in the waste magnesium-aluminum-carbon bricks is ≥88wt%.

5. The long life, low cost magnesia-alumina-carbon brick according to claim 1, characterized by: The fused magnesia includes: Fused magnesia with a particle size of 3-1mm, fused magnesia with a particle size of 1-0mm, and fused magnesia with a particle size of 200 mesh. The mass ratio of fused magnesia with a particle size of 3-1 mm, fused magnesia with a particle size of 1-0 mm, and fused magnesia with a particle size of 200 mesh is 1:1:1.8-2.

3. The fused magnesia contains ≥96wt% MgO.

6. The long life, low cost magnesia-alumina-carbon brick according to claim 1, characterized by: The medium-frequency furnace charge includes: Medium-frequency furnace charge with a particle size of 5-3mm, medium-frequency furnace charge with a particle size of 3-1mm, and medium-frequency furnace charge with a particle size of 1-0mm; The mass ratio of medium-frequency furnace charge with a particle size of 5-3mm, medium-frequency furnace charge with a particle size of 3-1mm, and medium-frequency furnace charge with a particle size of 1-0mm is 1:1:1 to 1.

5. The Al2O3 content in the medium-frequency furnace charge is ≥80wt%.

7. The long life, low cost magnesia-alumina-carbon brick according to claim 1, characterized by: The tabular corundum comprises: Tabular corundum with a particle size of 1-0 mm and tabular corundum with a particle size of 200 mesh; The mass ratio of tabular corundum with a particle size of 1-0 mm to tabular corundum with a particle size of 200 mesh is 1:1.2-1.

5.

8. The long life, low cost magnesia-alumina-carbon brick according to claim 1, characterized by: The binder is liquid phenolic resin with a solid content ≥75%.

9. A process for the production of long-lasting, low-cost Mg-Al-C brick according to any one of claims 1 to 8, characterized in that, Includes the following steps: S1. Weigh out the waste magnesia-alumina-carbon bricks, medium-frequency furnace charge, fused magnesia, tabular corundum, liquid phenolic resin and graphite in sequence according to the mass percentage. First, mix the waste magnesia-alumina-carbon bricks, medium-frequency furnace charge, fused magnesia and tabular corundum. Then add liquid phenolic resin to mix the materials. Next, add graphite to mix the materials. Finally, obtain the mixture. S2. Fine powder is obtained by mixing fused magnesia and tabular corundum. S3. Add the fine powder obtained in S2 to the mixture obtained in S1, then put it into the mold of the brick press and press it into shape. After heat treatment in the heat treatment kiln, long-life, low-cost magnesium aluminum carbon bricks are obtained.

10. The method of claim 9, wherein the method is characterized by: The brick press is a 630T electric screw brick press; during the heat treatment in the heat treatment kiln, the internal temperature of the heat treatment kiln is 180-240℃, and the heat treatment time is 14-30h.

Images