Metal-based composite magnesia spinel brick as well as preparation method and application thereof

Abstract

The invention provides a metal-based composite magnesia spinel brick as well as a preparation method and application thereof, and belongs to the technical field of refractory materials. The magnesium spinel brick provided by the invention can ensure sufficient sintering and high density after being compounded with a metal-based mixture, can effectively reduce permeation of corrosive substances such as co-processed garbage as a lining of a rotary cement kiln, has good affinity with a cement raw material, is easy to adhere to a kiln coating, can reduce the wear degree of the material and prolong the service life, and is suitable for industrial production. The refractory material has excellent high-temperature strength, is not easily damaged by operation torsion stress in use, is green and environment-friendly, can replace the existing magnesium-chromium refractory material, and avoids the pollution problem of Cr < 6 + >.

Description

Technical Field

[0001] This invention relates to the field of refractory materials technology, and in particular to a metal-based composite magnesium spinel brick, its preparation method, and its application. Background Technology

[0002] When magnesia-chrome bricks are used as linings in cement kilns, they react with alkalis and their compounds in cement raw materials, as well as lime, causing the trivalent chromium in the magnesia-chrome bricks to convert into toxic hexavalent chromium, posing a serious threat to human health. Furthermore, the residual magnesia-chrome bricks produced after the bricks are discarded and piled up directly will pollute the soil and groundwater resources, causing severe environmental pollution problems. Therefore, the large-scale use of magnesia-chrome bricks will undoubtedly cause enormous damage to public health and the environment. In recent years, with the increasing severity of environmental pollution and the growing awareness of environmental protection, the development of low-chromium or chromium-free environmentally friendly alkaline bricks for cement kilns has become increasingly important in order to solve the problem of hexavalent chromium pollution.

[0003] For chromium-free alkaline bricks, magnesium-iron-aluminum spinel bricks are currently the most widely used in the market. They have good kiln lining performance. However, due to the high sensitivity of iron in magnesium-iron-aluminum spinel bricks to atmosphere, irreversible volume changes can occur due to atmosphere variations, greatly increasing the instability of magnesium-iron-aluminum spinel bricks during use. Although common magnesium-aluminum spinel bricks on the market have excellent thermal shock stability and high-temperature strength, they are not easy to form kiln lining and have poor wear resistance, failing to meet requirements.

[0004] Furthermore, the approach of using a new dry-process rotary kiln to treat municipal solid waste is a method that simultaneously treats, utilizes, and avoids secondary pollution of urban solid waste. This method of application is referred to as the use of secondary raw materials in the cement industry. Using a new dry-process cement rotary kiln to treat municipal solid waste must ensure that cement production is pollution-free and environmentally friendly. It also places high demands on the lining bricks. Harmful elements such as Cl, N, and S contained in municipal solid waste can create a strong acid-base environment during firing, affecting the lifespan of the lining bricks. Considering seasonal variations, waste sorting, and the co-processing of different wastes, higher requirements are placed on the cement rotary kiln lining bricks and the overall operating conditions.

[0005] Therefore, how to provide a magnesium spinel brick with excellent mechanical properties, easy kiln coating, low wear and long service life has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0006] The purpose of this invention is to provide a metal-based composite magnesia spinel brick, its preparation method, and its application. The metal-based composite magnesia spinel brick provided by this invention has high density, effectively reducing the penetration of corrosive substances such as co-processed waste when used as a lining in a cement rotary kiln. It also exhibits good compatibility with cement raw materials, easily forms kiln lining, reduces material wear, and extends service life. Furthermore, it possesses excellent high-temperature strength and is not easily damaged by torsional stress during operation. It is also environmentally friendly and can replace current magnesia-chromium refractories, avoiding the problems associated with Cr... 6+ Pollution problem.

[0007] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a metal-based composite magnesium spinel brick. The raw materials for preparing the magnesium spinel brick, by weight, include: 60-80 parts of magnesia granules; 13-20 parts of magnesia fine powder; 8-25 parts of spinel; 1-6 parts of alumina micro powder; 0.5-5 parts of metal-based mixture; and 2-4 parts of binder. The metal-based mixture is metal powder treated with a coating agent; the metal powder includes aluminum powder, silicon powder, manganese powder, and magnesium powder; the particle size of the metal powder is independently 80~180 mesh; the particle size of the metal-based mixture is ≤0.5mm; The preparation method of the metal-based mixture is as follows: aluminum powder, silicon powder, manganese powder and magnesium powder are placed on a vibrating fine sieve, and then coated with a coating agent by spraying or sprinkling. After drying, aluminum powder coated with the coating agent, silicon powder coated with the coating agent, manganese powder coated with the coating agent and magnesium powder coated with the coating agent are obtained respectively. Finally, the aluminum powder coated with the coating agent, silicon powder coated with the coating agent, manganese powder coated with the coating agent and magnesium powder coated with the coating agent are mixed to obtain the metal-based mixture.

[0008] Preferably, the particle size of the magnesia particles is 0.088~6mm; the particle size of the fine magnesia powder is <0.088mm.

[0009] Preferably, the spinel is fused spinel and / or sintered spinel; the particle size of the spinel is ≤5mm.

[0010] Preferably, the alumina micro powder has a continuous gradation in particle size; the particle size of the alumina micro powder includes D1≤0.010mm, 0.010mm<D2≤0.025mm and 0.025mm<D3≤0.044mm; the mass ratio of D1, D2 and D3 is (10~20):(20~30):(40~60).

[0011] Preferably, the raw materials for preparing the coating agent are any one or more of glass wool, rock wool, aluminum silicate fiber, and aerogel fiber.

[0012] Preferably, the binder is any one or more of pulp, lignin sulfonate solution, dextrin solution, and carboxymethyl cellulose solution.

[0013] The present invention provides a method for preparing the metal-based composite magnesium spinel brick described in the above technical solution, comprising: mixing magnesium sand particles, magnesium sand fine powder, spinel, alumina micro powder, metal-based mixture and binder, and then sequentially pressing and firing them to obtain the metal-based composite magnesium spinel brick.

[0014] Preferably, the pressing pressure is 800~2500T.

[0015] Preferably, the firing temperature is 1500~1730℃, and the firing holding time is 10~25h.

[0016] This invention provides the application of the metal-based composite magnesium spinel brick described in the above technical solution or the metal-based composite magnesium spinel brick prepared by the preparation method described in the above technical solution in a cement rotary kiln.

[0017] This invention provides a metal-based composite magnesium spinel brick. The raw materials for preparing the magnesium spinel brick, by weight, include: 60-80 parts of magnesia granules; 13-20 parts of fine magnesia powder; 8-25 parts of spinel; 1-6 parts of alumina powder; 0.5-5 parts of a metal-based mixture; and 2-4 parts of a binder. The metal-based mixture is metal powder treated with a coating agent. The metal powder includes aluminum powder, silicon powder, manganese powder, and magnesium powder. The particle size of the metal powder is independently 80-180 mesh. The particle size of the metal-based mixture is ≤0.5mm; the preparation method of the metal-based mixture is as follows: aluminum powder, silicon powder, manganese powder and magnesium powder are placed on a vibrating fine sieve, and then coated with a coating agent by blowing or spraying. After drying, aluminum powder coated with the coating agent, silicon powder coated with the coating agent, manganese powder coated with the coating agent and magnesium powder coated with the coating agent are obtained respectively. Finally, the aluminum powder coated with the coating agent, silicon powder coated with the coating agent, manganese powder coated with the coating agent and magnesium powder coated with the coating agent are mixed to obtain the metal-based mixture. This invention utilizes a vibrating fine sieve for coating, ensuring that the fine metal powder particles roll on the sieve, which is beneficial for subsequent coating. By controlling the spraying or sprinkling time, the coating thickness can be controlled to achieve different coating thicknesses for different metal powders. Since different metal powders have different activities and oxidation temperatures, and different coating agents have different ignition temperatures, the oxidation of the metal powder at different temperatures and rates during the firing process can be controlled by adjusting the type of coating agent and the coating thickness, resulting in the formation of a stable mineral phase. Ultimately, this achieves the desired oxidation rate of the fine metal powder particles and the formation of the mineral phase during firing. By adding multiple metal powders and controlling the coating agent thickness, the oxidation rate of the metal powder can be controlled. The reaction rate of metal powder with other raw materials varies depending on the type of metal powder and the oxidation temperature. As a result, during the firing process of magnesia spinel bricks, different metal powders successively and controllably form metal oxides at different temperatures. Then, the metal oxides react with each other. For example, magnesium and aluminum form magnesium oxide and aluminum oxide. Magnesium oxide and aluminum oxide react with magnesium oxide and aluminum oxide in the brick to form magnesium aluminum spinel. Manganese oxide and aluminum oxide can form manganese aluminum spinel. This allows for the regulation of the content of different spinels in the magnesia spinel bricks and the microstructure of the magnesia spinel bricks, thereby further improving the mechanical properties of the magnesia spinel bricks and obtaining magnesia spinel bricks that are easy to apply kiln skin, have low wear, and have a long service life. The magnesia spinel bricks provided by this invention, after being composited with metal-based admixtures, ensure thorough sintering and high density. As linings for cement rotary kilns, they effectively reduce the penetration of corrosive substances such as co-processed waste. The addition of metal-based admixtures improves the product's compatibility with cement raw materials, facilitates kiln lining formation, reduces material wear, and extends service life. They possess excellent high-temperature strength, are not easily damaged by torsional stress during operation, and are environmentally friendly. They can replace current magnesia-chromium refractories, avoiding the problems associated with Cr... 6+ Pollution problem. Detailed Implementation

[0018] This invention provides a metal-based composite magnesium spinel brick. The raw materials for preparing the magnesium spinel brick, by weight, include: 60-80 parts of magnesia granules; 13-20 parts of magnesia fine powder; 8-25 parts of spinel; 1-6 parts of alumina micro powder; 0.5-5 parts of metal-based mixture; and 2-4 parts of binder. The metal-based mixture is metal powder treated with a coating agent; the metal powder includes aluminum powder, silicon powder, manganese powder, and magnesium powder; the particle size of the metal powder is independently 80~180 mesh; the particle size of the metal-based mixture is ≤0.5mm; The preparation method of the metal-based mixture is as follows: aluminum powder, silicon powder, manganese powder and magnesium powder are placed on a vibrating fine sieve, and then coated with a coating agent by spraying or sprinkling. After drying, aluminum powder coated with the coating agent, silicon powder coated with the coating agent, manganese powder coated with the coating agent and magnesium powder coated with the coating agent are obtained respectively. Finally, the aluminum powder coated with the coating agent, silicon powder coated with the coating agent, manganese powder coated with the coating agent and magnesium powder coated with the coating agent are mixed to obtain the metal-based mixture.

[0019] The raw materials for preparing the magnesia spinel bricks provided by this invention, by weight, include 60-80 parts of magnesia sand particles; the magnesia sand particles are preferably one or two of fused magnesia, sintered magnesia, and flotation magnesia; the particle size of the magnesia sand particles is preferably 0.088-6 mm. As one embodiment of this invention, the weight of the magnesia sand particles can be 60, 62, 64, 65, 66, 68, 70, 72, 74, 75, 76, 78, or 80 parts; the particle size of the magnesia sand particles can be 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, or 6 mm. In this invention, magnesia particles are an important raw material for producing magnesia spinel bricks. Its main crystalline phase is periclase, which can produce magnesia spinel bricks with good high-temperature performance and high resistance to erosion and abrasion. The main crystalline phase of spinel is magnesium aluminum spinel, which has excellent thermal shock stability. At the same time, the metal-based mixture is evenly dispersed in the brick matrix. During the firing process, the residual voids of the oxidizing filling coating agent are formed, resulting in stable sintering. As the temperature rises, the oxides formed will continue to form solid solutions of mineral phases such as magnesium aluminum spinel, manganese aluminum spinel, and mullite. Through solid solution and diffusion between mineral phases of different raw materials, the mineral phases and intercrystalline bonding of the material are realized, thereby improving the overall performance of magnesia spinel bricks.

[0020] The raw materials for preparing the magnesia spinel bricks provided by this invention include 13-20 parts of fine magnesia powder, based on a mass fraction of 60-80 parts of magnesia particles. In this invention, the fine magnesia powder is preferably one or two of fused magnesia, sintered magnesia, and flotation magnesia; the particle size of the fine magnesia powder is preferably <0.088 mm, more preferably ≤0.075 mm. As one embodiment of this invention, the mass fraction of the fine magnesia powder can be 13, 14, 15, 16, 17, 18, 19, or 20 parts. By adding fine magnesia powder, this invention not only achieves the same effect as magnesia particles, but also improves the density of the magnesia spinel bricks due to the smaller particle size of the fine magnesia powder.

[0021] The raw materials for preparing the magnesium spinel bricks provided by this invention include 8-25 parts spinel, based on a mass fraction of 60-80 parts of magnesia sand particles; the spinel is preferably fused spinel and / or sintered spinel; the particle size of the spinel is preferably ≤5mm, more preferably 0.5-5mm. In one embodiment of this invention, the mass fraction of the spinel can be 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, or 24 parts; the particle size of the spinel can be 1mm, 2mm, 3mm, or 4mm. In this invention, the addition of spinel forms magnesium aluminum spinel and mullite, thereby improving the erosion resistance, spalling resistance, slag resistance, abrasion resistance and thermal shock stability of magnesium spinel bricks; at the same time, the combination of magnesia sand and spinel sand achieves direct bonding of materials through the mutual diffusion between ions, thereby improving the overall performance of magnesium spinel bricks.

[0022] The raw materials for preparing the magnesium spinel bricks provided by this invention include 1-6 parts of alumina micropowder, based on a mass fraction of 60-80 parts of magnesia particles; the particle size of the alumina micropowder is preferably ≤0.044 mm. In one embodiment of this invention, the mass fraction of the alumina micropowder can be 1.5 parts, 2 parts, 2.5 parts, 3 parts, 3.5 parts, 4 parts, 4.5 parts, 5 parts, or 5.5 parts. In this invention, the addition of alumina micropowder can form magnesium aluminum spinel with magnesium oxide, mullite with silicon oxide, and manganese aluminum spinel with manganese oxide.

[0023] In this invention, the alumina micro powder preferably has a continuously graded particle size distribution; the particle size of the alumina micro powder preferably includes D1≤0.010mm, 0.010mm<D2≤0.025mm, and 0.025mm<D3≤0.044mm; the mass ratio of D1, D2, and D3 is preferably (10~20):(20~30):(40~60). As one embodiment of this invention, the mass ratio of D1, D2, and D3 can be (12~18):(22~28):(45~55), or it can be 15:25:50. By adopting the above-mentioned gradation method, since the particle size is between micro powder and small particles, after uniformly dispersing it in magnesia spinel bricks, the volume change of the brick can be stabilized during the reaction of the coating agent continuously burning away the fine metal particles, preventing the brick from bursting.

[0024] The raw materials for preparing the magnesium spinel bricks provided by this invention include 0.5 to 5 parts of a metal-based mixture, based on a mass fraction of 60 to 80 parts of magnesia sand particles. The metal-based mixture is metal powder treated with a coating agent. The particle size of the metal-based mixture is ≤0.5 mm, preferably 0.1 to 0.5 mm. In one embodiment of this invention, the mass fraction of the metal-based mixture can be 1 part, 1.5 parts, 2 parts, 2.5 parts, 3 parts, 3.5 parts, 4 parts, or 4.5 parts; the particle size of the metal-based mixture can be 0.1 mm, 0.15 mm, 0.2 mm, 0.25 mm, 0.3 mm, 0.35 mm, 0.4 mm, or 0.45 mm.

[0025] In this invention, the metal powder includes aluminum powder, silicon powder, manganese powder, and magnesium powder; the preferred mass ratio of aluminum powder, silicon powder, manganese powder, and magnesium powder is (2.0~3.5):(0.5~1.5):(1.0~2.5):(0.5~1.0); the particle size of the metal powder is independently 80~180 mesh; the purity of the metal powder is independently preferably ≥95%. As one embodiment of this invention, the particle size of the metal powder can be independently 90 mesh, 100 mesh, 110 mesh, 120 mesh, 130 mesh, 140 mesh, 150 mesh, 160 mesh, or 170 mesh. In this invention, if the metal powder is too fine, the reaction will be too fast and violent, affecting the stability of the entire brick firing process; if the metal powder is too large, the reaction rate will be too slow, making it difficult to complete the reaction. Therefore, reducing the particle size of the metal powder to 80~180 mesh can control its reaction activity and speed.

[0026] In this invention, the raw materials for preparing the coating agent are preferably one or more selected from glass wool, rock wool, aluminum silicate fiber, and aerogel fiber. In this invention, the particle size of the coating agent is preferably ≤0.044 mm. In this invention, when the particle size of the coating agent does not meet the above requirements, it is preferable to crush and grind the coating agent. This invention does not have specific limitations on the specific operations of crushing and grinding, as long as the particle size of the coating agent meets the requirements. By controlling the particle size of the coating agent, this invention makes it easier for the coating agent to adhere to metal powder particles, thereby achieving coating.

[0027] In this invention, the preparation method of the metal-based mixture is as follows: aluminum powder, silicon powder, manganese powder and magnesium powder are placed on a vibrating fine sieve, and then coated with a coating agent by spraying or sprinkling. After drying, aluminum powder coated with the coating agent, silicon powder coated with the coating agent, manganese powder coated with the coating agent and magnesium powder coated with the coating agent are obtained respectively. Finally, the aluminum powder coated with the coating agent, silicon powder coated with the coating agent, manganese powder coated with the coating agent and magnesium powder coated with the coating agent are mixed to obtain the metal-based mixture. In this invention, the preferred spraying or sprinkling rate of the coating agent is 0.1~2.0 g / min; when the metal powder is aluminum powder, the preferred spraying or sprinkling time of the coating agent is 0.5~1.0 min; when the metal powder is silicon powder, the preferred spraying or sprinkling time of the coating agent is 0.3~1.2 min; when the metal powder is manganese powder, the preferred spraying or sprinkling time of the coating agent is 0.1~0.6 min; when the metal powder is magnesium powder, the preferred spraying or sprinkling time of the coating agent is 0.8~1.8 min. In this invention, the preferred mass ratio of aluminum powder to coating agent during coating is (2.0~3.5):(0.1~0.5), more preferably (2.5~3.2):(0.2~0.4), and even more preferably (2.8~3.0):0.3; the preferred mass ratio of silicon powder to coating agent during coating is (0.5~1.5):(0.1~0.5), more preferably (0.8~1.4):(0.2~0.4), and even more preferably (1.0~1.2):(0.3~0.4); The preferred mass ratio of manganese powder to coating agent during coating is (1.0~2.5):(0.05~0.4), more preferably (1.2~2.2):(0.1~0.3), and even more preferably (1.5~2.0):(0.15~0.2); the preferred mass ratio of magnesium powder to coating agent during coating is (0.5~1.0):(0.2~0.6), more preferably (0.6~0.9):(0.3~0.5), and even more preferably (0.7~0.8):(0.4~0.5). This invention allows for adjustment of the coating effect by controlling the ratio of coating agent to metal powder.

[0028] This invention, by coating on a vibrating fine sieve, ensures that the fine metal powder particles roll on the sieve, which is beneficial for subsequent coating. By controlling the blowing or spraying time, the coating thickness can be controlled to achieve different coating thicknesses for different metal powders. Since different metal powders have different activities and oxidation temperatures, and different coating agents have different ignition temperatures, by controlling the type of coating agent and the coating thickness, the oxidation of metal powder at different temperatures and rates during the firing process can be controlled to form a stable mineral phase. Ultimately, this invention achieves control over the oxidation rate of fine metal powder particles and the formation of mineral phases during the firing process.

[0029] This invention controls the reaction rate of metal powders with other raw materials by adding various metal powders treated with coating agents and controlling the amount of coating agents and metal powders. Since different types of metal powders have different oxidation temperatures, different metal powders can sequentially and controllably form metal oxides at different temperatures during the firing process of magnesia spinel bricks. Then, the metal oxides react with each other. For example, magnesium and aluminum form magnesium oxide and aluminum oxide, which then react with the magnesium oxide and aluminum oxide in the brick to form magnesium aluminum spinel. Manganese oxide and aluminum oxide can form manganese aluminum spinel. This allows for the regulation of the spinel content and microstructure of the magnesia spinel bricks, thereby further improving the mechanical properties of the magnesia spinel bricks and obtaining magnesia spinel bricks that are easy to apply kiln skin, have low wear, and have a long service life.

[0030] The raw materials for preparing the magnesium spinel bricks provided by this invention include 2-4 parts of binder, based on a mass fraction of 60-80 parts of magnesia sand particles. The binder is preferably any one or more of pulp, lignin sulfonate solution, dextrin solution, and carboxymethyl cellulose solution. The concentrations of the lignin sulfonate solution, dextrin solution, and carboxymethyl cellulose solution are independently preferably ≥1.20 g / mL. In one embodiment of this invention, the mass fraction of the binder can be 2.5 parts, 3 parts, or 3.5 parts. By adding a binder, this invention can improve the bonding strength of the magnesium spinel bricks.

[0031] The magnesia spinel bricks provided by this invention, after being compounded with metal-based admixtures, ensure thorough sintering and high density. As linings for cement rotary kilns, they effectively reduce the penetration of corrosive substances such as co-processed waste. They also exhibit good compatibility with cement raw materials, easily forming kiln linings, reducing material wear, and extending service life. They possess excellent high-temperature strength and are not easily damaged by torsional stress during operation. Furthermore, they are environmentally friendly and can replace current magnesia-chromium refractories, avoiding the problems associated with Cr... 6+ Pollution problem.

[0032] The present invention also provides a method for preparing the metal-based composite magnesium spinel brick described in the above technical solution, comprising: mixing magnesia particles, magnesia fine powder, spinel, alumina micro powder, metal-based mixture and binder, and then sequentially pressing and firing them to obtain the metal-based composite magnesium spinel brick.

[0033] In this invention, the preferred method for mixing the magnesia particles, fine magnesia powder, spinel, alumina powder, metal-based mixture, and binder is as follows: first, the alumina powder and metal-based mixture are mixed to obtain a premix; then, the magnesia particles, spinel, and binder are mixed for 10-15 minutes; finally, the fine magnesia powder and premix are added and mixed for 10-20 minutes. In this invention, the mixing is preferably carried out under stirring conditions. This invention does not have a specific limitation on the stirring speed, as long as it ensures that the components are mixed evenly. By employing the above-described stepwise mixing method, this invention can further improve the mixing uniformity of the components.

[0034] In this invention, the pressing pressure is preferably 800-2500T. The pressing time is not specifically limited and can be determined based on the technical knowledge of those skilled in the art. As one embodiment of this invention, the pressing pressure can be 900T, 1000T, 1100T, 1200T, 1300T, 1400T, 1500T, 1600T, 1700T, 1800T, 1900T, 2000T, 2100T, 2200T, 2300T, or 2400T. This invention, through pressing, can improve the density of magnesia spinel bricks and further enhance their mechanical properties.

[0035] In this invention, the firing temperature is preferably 1500~1730℃; the firing holding time is preferably 10~25h. Preferably, the temperature is uniformly increased from room temperature to the firing temperature within 36~48h. As one embodiment of this invention, the firing temperature can be 1530℃, 1550℃, 1580℃, 1600℃, 1630℃, 1650℃, 1680℃, or 1700℃; the firing holding time can be 11h, 12h, 13h, 14h, 15h, 16h, 17h, 18h, 19h, 20h, 21h, 22h, 23h, or 24h. By controlling the firing temperature and time, this invention can further improve the density of magnesia spinel bricks, thereby improving their thermal shock stability and high-temperature strength.

[0036] The preparation method provided by this invention is simple, requiring only simple mixing, pressing and molding, and firing. It can be achieved using existing equipment without the need to introduce new equipment, which is conducive to large-scale industrial promotion and application.

[0037] This invention provides the application of the metal-based composite magnesium spinel brick described in the above technical solution or the metal-based composite magnesium spinel brick prepared by the preparation method described in the above technical solution in a cement rotary kiln.

[0038] The present invention does not impose any special limitation on the specific application method, and any application method known to those skilled in the art can be used.

[0039] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0040] Example 1 A metal-based composite magnesium spinel brick, the raw materials for preparing the magnesium spinel brick by mass parts are: 68 parts of magnesia granules; 15 parts of magnesia fine powder; 15 parts of spinel; 5 parts of alumina micro powder; 1.5 parts of metal-based mixture and 3 parts of binder; The magnesia particles and fine magnesia powder are both fused magnesia, with the particle size of the magnesia particles being 0.088~6mm and the particle size of the fine magnesia powder being <0.088mm; the spinel is fused spinel, with the particle size of the spinel being ≤5mm; the particle size of the alumina micro powder is ≤0.044mm; and the binder is pulp. The alumina micro powder has a continuously graded particle size distribution; the particle size of the alumina micro powder is D1≤0.010mm, 0.010mm<D2≤0.025mm and 0.025mm<D3≤0.044mm; the mass ratio of D1, D2 and D3 is 20:20:60. The metal-based mixture is a metal powder treated with a coating agent; the metal powder is aluminum powder, silicon powder, manganese powder, and magnesium powder, with a mass ratio of 2.5:0.6:1.5:0.5; the raw materials for preparing the coating agent are a mixture of aluminum silicate fiber and aerogel fiber with a mass ratio of 1:1, and the particle size of the coating agent is ≤0.044mm; the particle size of the metal-based mixture is 0.15~0.25mm; the particle size of the aluminum powder, silicon powder, manganese powder, and magnesium powder is independently 80~180 mesh; the purity of the aluminum powder, silicon powder, manganese powder, and magnesium powder is independently ≥95%; The preparation method of the metal-based mixture is as follows: aluminum powder, silicon powder, manganese powder and magnesium powder are placed on a vibrating fine sieve to keep the metal powder in a vibrating state, then a coating agent is sprayed on for coating, followed by drying to obtain aluminum powder coated with coating agent, silicon powder coated with coating agent, manganese powder coated with coating agent and magnesium powder coated with coating agent respectively. Finally, the aluminum powder coated with coating agent, silicon powder coated with coating agent, manganese powder coated with coating agent and magnesium powder coated with coating agent are mixed to obtain the metal-based mixture. The coating agent is sprayed at a rate of 0.5 g / min; when the metal powder is aluminum powder (2.5 g), the coating agent is sprayed for 0.6 min; when the metal powder is silicon powder (0.6 g), the coating agent is sprayed for 0.8 min; when the metal powder is manganese powder (1.5 g), the coating agent is sprayed for 0.3 min; and when the metal powder is magnesium powder (0.5 g), the coating agent is sprayed for 1.0 min. The preparation method of the metal-based composite magnesium spinel brick is as follows: under stirring conditions, alumina micro powder and metal-based mixture are first mixed to obtain a premix, then magnesia particles, spinel and binder are mixed for 15 min, then magnesia fine powder and premix are added and mixed for 20 min, and finally pressed and fired sequentially to obtain the metal-based composite magnesium spinel brick; the pressing pressure is 2000T; the firing temperature is 1600℃ and the firing holding time is 15h.

[0041] Example 2 A metal-based composite magnesium spinel brick, the raw materials for preparing the magnesium spinel brick by mass parts are: 65 parts of magnesia granules; 16 parts of magnesia fine powder; 15 parts of spinel; 5 parts of alumina micro powder; 1 part of metal-based mixture and 3 parts of binder; The mass ratio of aluminum powder, silicon powder, manganese powder, and magnesium powder is 2.8:0.5:1.4:0.6. Two raw materials are used to prepare the coating agent: one is a mixture of aluminum silicate fiber and aerogel fiber in a mass ratio of 1:1, and the other is aluminum silicate fiber itself. Aluminum powder, silicon powder, and manganese powder are all coated using aluminum silicate fiber; magnesium powder is coated using a 1:1 mixture of aluminum silicate fiber and aerogel fiber. In the preparation method of the metal-based mixture, the coating agent is sprayed at a rate of 0.5 g / min; when the metal powder is aluminum powder (2.8 g), the coating agent is sprayed for 0.6 min; when the metal powder is silicon powder (0.5 g), the coating agent is sprayed for 0.8 min; when the metal powder is manganese powder (1.4 g), the coating agent is sprayed for 0.3 min; and when the metal powder is magnesium powder (0.6 g), the coating agent is sprayed for 1.0 min. Other conditions are the same as in Example 1.

[0042] Example 3 A metal-based composite magnesium spinel brick, the raw materials for preparing the magnesium spinel brick by mass parts are: 75 parts of magnesia granules; 13 parts of magnesia fine powder; 15 parts of spinel; 5 parts of alumina micro powder; 2 parts of metal-based mixture and 3 parts of binder; The mass ratio of aluminum powder, silicon powder, manganese powder, and magnesium powder is 3.0:1.3:1.0:0.9; there are two raw materials for preparing the coating agent, one is aerogel fiber, and the other is aluminum silicate fiber; aluminum powder and manganese powder are coated with aluminum silicate fiber; silicon powder and magnesium powder are coated with aerogel fiber; In the preparation method of the metal-based mixture, the coating agent is sprayed at a rate of 0.5 g / min; when the metal powder is aluminum powder (3.0 g), the coating agent is sprayed for 0.6 min; when the metal powder is silicon powder (1.3 g), the coating agent is sprayed for 0.8 min; when the metal powder is manganese powder (1.0 g), the coating agent is sprayed for 0.3 min; and when the metal powder is magnesium powder (0.9 g), the coating agent is sprayed for 1.0 min. Other conditions are the same as in Example 1.

[0043] Example 4 A metal-based composite magnesium spinel brick, the raw materials for preparing the magnesium spinel brick by mass parts are: 78 parts of magnesia granules; 13 parts of magnesia fine powder; 15 parts of spinel; 5 parts of alumina micro powder; 3 parts of metal-based mixture and 3 parts of binder; The mass ratio of aluminum powder, silicon powder, manganese powder, and magnesium powder is 3.2:1.2:0.9:1.0. Three raw materials are used to prepare the coating agent: a mixture of rock wool and aluminum silicate fiber in a mass ratio of 1:2; aluminum silicate fiber and aerogel fiber; and aerogel fiber. Specifically, silicon powder and magnesium powder are coated using the mixture of rock wool and aluminum silicate fiber in a mass ratio of 1:2; aluminum powder is first coated using aluminum silicate fiber, then coated using aerogel fiber; and manganese powder is coated using aerogel fiber. In the preparation method of the metal-based mixture, the coating agent is sprayed at a rate of 0.5 g / min; when the metal powder is aluminum powder (3.2 g), the coating agent is sprayed for 0.6 min; when the metal powder is silicon powder (1.2 g), the coating agent is sprayed for 0.8 min; when the metal powder is manganese powder (0.9 g), the coating agent is sprayed for 0.3 min; and when the metal powder is magnesium powder (1.0 g), the coating agent is sprayed for 1.0 min. Other conditions are the same as in Example 1.

[0044] Example 5 A metal-based composite magnesium spinel brick, the raw materials for preparing the magnesium spinel brick by mass parts are: 65 parts of magnesia granules; 18 parts of magnesia fine powder; 15 parts of spinel; 5 parts of alumina micro powder; 4 parts of metal-based mixture and 3 parts of binder; The mass ratio of aluminum powder, silicon powder, manganese powder, and magnesium powder is 2.5:1.5:1.1:0.8. Three raw materials are used to prepare the coating agent: a mixture of glass wool and aluminum silicate fiber in a mass ratio of 1:5; an mixture of aluminum silicate fiber and aerogel fiber; and an aerogel fiber. Aluminum powder and silicon powder are coated using the mixture of glass wool and aluminum silicate fiber in a mass ratio of 1:5. Manganese powder is first coated using aluminum silicate fiber, then coated using aerogel fiber. Magnesium powder is coated using aerogel fiber. In the preparation method of the metal-based mixture, the coating agent is sprayed at a rate of 0.5 g / min; when the metal powder is aluminum powder (2.5 g), the coating agent is sprayed for 0.6 min; when the metal powder is silicon powder (1.5 g), the coating agent is sprayed for 0.8 min; when the metal powder is manganese powder (1.1 g), the coating agent is sprayed for 0.3 min; and when the metal powder is magnesium powder (0.8 g), the coating agent is sprayed for 1.0 min. Other conditions are the same as in Example 1.

[0045] Example 6 A metal-based composite magnesium spinel brick, the raw materials for preparing the magnesium spinel brick by mass parts are: 62 parts of magnesia granules; 20 parts of magnesia fine powder; 15 parts of spinel; 5 parts of alumina micro powder; 5 parts of metal-based mixture and 3 parts of binder; The mass ratio of aluminum powder, silicon powder, manganese powder, and magnesium powder is 3.3:1.0:1.2:0.7. The coating agent is prepared from three raw materials: aluminum silicate fiber, aerogel fiber, and a mixture of aluminum silicate fiber and aerogel fiber in a mass ratio of 2:1. Aluminum powder is coated using aluminum silicate fiber; silicon powder is coated using aerogel fiber; and magnesium and manganese powders are coated using a mixture of aluminum silicate fiber and aerogel fiber in a mass ratio of 2:1. In the preparation method of the metal-based mixture, the coating agent is sprayed at a rate of 0.5 g / min; when the metal powder is aluminum powder (3.3 g), the coating agent is sprayed for 0.6 min; when the metal powder is silicon powder (1.0 g), the coating agent is sprayed for 0.8 min; when the metal powder is manganese powder (1.2 g), the coating agent is sprayed for 0.3 min; and when the metal powder is magnesium powder (0.7 g), the coating agent is sprayed for 1.0 min. Other conditions are the same as in Example 1.

[0046] Comparative Example 1 A magnesium spinel brick, the raw materials for preparing the magnesium spinel brick by weight parts are: 65 parts of magnesia granules; 15 parts of magnesia fine powder; 15 parts of spinel; 2 parts of alumina micro powder and 3 parts of binder; The magnesia particles and fine magnesia powder are both fused magnesia, with the particle size of the magnesia particles being 0.088~6mm and the particle size of the fine magnesia powder being <0.088mm; the spinel is fused spinel, with the particle size of the spinel being ≤5mm; the particle size of the alumina micro powder is ≤0.044mm; and the binder is pulp. The alumina micro powder has a continuously graded particle size distribution; the particle size of the alumina micro powder is D1≤0.010mm, 0.010mm<D2≤0.025mm and 0.025mm<D3≤0.044mm; the mass ratio of D1, D2 and D3 is 20:20:60. The preparation method of the magnesium spinel brick is as follows: under stirring conditions, alumina micro powder, magnesia, spinel and binder are mixed for 20 minutes, and then pressed and fired in sequence to obtain magnesium spinel brick; the pressing pressure is 2000T; the firing temperature is 1600℃ and the firing holding time is 15h.

[0047] Comparative Example 2 A metal-based composite magnesium spinel brick, the raw materials for preparing the magnesium spinel brick by mass parts are: 65 parts of magnesia granules; 15 parts of magnesia fine powder; 15 parts of spinel; 5 parts of alumina micro powder; 0.5 parts of aluminum powder treated with coating agent and 3 parts of binder; The raw materials for preparing the coating agent are aluminum silicate fiber and aerogel fiber in a mass ratio of 1:1, and the particle size of the coating agent is ≤0.044mm; the particle size of the aluminum powder treated with the coating agent is 0.15~0.25mm; the particle size of the aluminum powder is 80~180 mesh; and the purity of the aluminum powder is ≥95%. The method for preparing the aluminum powder treated with the coating agent is as follows: aluminum powder is placed on a vibrating fine sieve to keep the metal powder vibrating, then a coating agent is sprayed on for coating, followed by drying to obtain aluminum powder coated with the coating agent; the spraying rate of the coating agent is 0.5 g / min; when the metal powder is aluminum powder (2.5 g), the spraying time of the coating agent is 0.6 min; Other conditions are the same as in Example 1.

[0048] Comparative Example 3 A metal-based composite magnesium spinel brick, the raw materials for preparing the magnesium spinel brick by mass parts are: 65 parts of magnesia granules; 15 parts of magnesia fine powder; 15 parts of spinel; 5 parts of alumina micro powder; 0.5 parts of iron powder treated with coating agent and 3 parts of binder; The raw materials for preparing the coating agent are aluminum silicate fiber and aerogel fiber in a mass ratio of 1:1, and the particle size of the coating agent is ≤0.044mm; the particle size of the iron powder treated with the coating agent is 0.15~0.25mm; the particle size of the iron powder is 80~180 mesh; and the purity of the iron powder is ≥95%. The method for preparing the coating agent-treated iron powder is as follows: iron powder is placed on a vibrating fine sieve to keep the metal powder vibrating, then a coating agent is sprayed on for coating, followed by drying to obtain iron powder coated with the coating agent; the spraying rate of the coating agent is 0.5 g / min; when the metal powder is iron powder (2.5 g), the spraying time of the coating agent is 0.6 min; Other conditions are the same as in Example 1.

[0049] The properties of the magnesium spinel bricks prepared in Examples 1-6 and Comparative Examples 1-3 were tested, and the results are shown in Table 1: Table 1. Properties of the magnesium spinel bricks prepared in Examples 1-6 and Comparative Examples 1-3

[0050] As shown in Table 1, the magnesium spinel bricks prepared in Examples 1-6 of this invention have lower apparent porosity and higher bulk density compared to Comparative Examples 1-3. This indicates that the magnesium spinel bricks of this invention are sintered more densely, and correspondingly have a lower wear resistance coefficient. The room temperature compressive strength and room temperature flexural strength of the magnesium spinel bricks are also greater, proving that the magnesium spinel bricks have better mechanical strength. Furthermore, the magnesium spinel bricks prepared in this invention have higher high temperature flexural strength, indicating better resistance to mechanical stress under high temperature conditions. The higher thermal shock stability value proves that the magnesium spinel bricks have stronger resistance to extreme temperature changes. The higher kiln lining strength value proves that the magnesium spinel bricks have better component affinity and are more likely to adhere to a stable kiln lining.

[0051] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A metal-based composite magnesium spinel brick, characterized in that, The raw materials for preparing magnesia spinel bricks, by mass parts, include: 60-80 parts of magnesia granules; 13-20 parts of magnesia fine powder; 8-25 parts of spinel; 1-6 parts of alumina micro powder; 0.5-5 parts of metal-based mixture; and 2-4 parts of binder. The metal-based mixture is metal powder treated with a coating agent; the metal powder includes aluminum powder, silicon powder, manganese powder, and magnesium powder; the particle size of the metal powder is independently 80~180 mesh; the particle size of the metal-based mixture is ≤0.5mm; The preparation method of the metal-based mixture is as follows: aluminum powder, silicon powder, manganese powder and magnesium powder are placed on a vibrating fine sieve, and then coated with a coating agent by spraying or sprinkling. After drying, aluminum powder coated with the coating agent, silicon powder coated with the coating agent, manganese powder coated with the coating agent and magnesium powder coated with the coating agent are obtained respectively. Finally, the aluminum powder coated with the coating agent, silicon powder coated with the coating agent, manganese powder coated with the coating agent and magnesium powder coated with the coating agent are mixed to obtain the metal-based mixture.

2. The metal-based composite magnesium spinel brick according to claim 1, characterized in that, The particle size of the magnesia particles is 0.088~6mm; the particle size of the fine magnesia powder is <0.088mm.

3. The metal-based composite magnesium spinel brick according to claim 1, characterized in that, The spinel is fused spinel and / or sintered spinel; the particle size of the spinel is ≤5mm.

4. The metal-based composite magnesium spinel brick according to claim 1, characterized in that, The alumina micro powder has a continuous gradation in particle size; the particle size of the alumina micro powder includes D1≤0.010mm, 0.010mm<D2≤0.025mm and 0.025mm<D3≤0.044mm; the mass ratio of D1, D2 and D3 is (10~20):(20~30):(40~60).

5. The metal-based composite magnesium spinel brick according to claim 1, characterized in that, The raw materials for preparing the coating agent are any one or more of glass wool, rock wool, aluminum silicate fiber and aerogel fiber.

6. The metal-based composite magnesium spinel brick according to claim 1, characterized in that, The binder is any one or more of pulp, lignin sulfonate solution, dextrin solution and carboxymethyl cellulose solution.

7. The method for preparing the metal-based composite magnesium spinel brick according to any one of claims 1 to 6, characterized in that, include: Magnesia particles, magnesia fine powder, spinel, alumina micro powder, metal-based mixture and binder are mixed and then pressed and fired in sequence to obtain metal-based composite magnesia spinel bricks.

8. The preparation method according to claim 7, characterized in that, The pressing pressure is 800~2500T.

9. The preparation method according to claim 7, characterized in that, The firing temperature is 1500~1730℃, and the firing holding time is 10~25h.

10. The application of the metal-based composite magnesium spinel brick according to any one of claims 1 to 6 or the metal-based composite magnesium spinel brick prepared by the preparation method according to any one of claims 7 to 9 in a cement rotary kiln.

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