Alumina hollow sphere heat-insulating refractory material prepared by aluminothermic reaction sintering and its preparation method

Abstract

The application belongs to the technical field of refractory materials, and discloses an aluminum-thermal reaction sintered alumina hollow ball heat-insulating refractory material and a preparation method thereof.The aluminum-thermal reaction sintered alumina hollow ball heat-insulating refractory material comprises the following raw materials in mass percentage: 20-30% of alumina hollow balls with a particle size of 3-5 mm, 10-20% of alumina hollow balls with a particle size of 1-3 mm, 5-15% of alumina hollow balls with a particle size of 0.1-1 mm, 2-10% of light-burned magnesia, 20-30% of active alumina powder, 15-25% of magnesium peroxide powder, 4-7% of aluminum powder, and 2-4% of a binder in addition to the total mass of the above raw materials.The refractory material utilizes the aluminum-thermal reaction of aluminum and magnesium peroxide to realize self-reaction sintering, forms a continuous spinel structure on the surface of the matrix and the alumina hollow balls, realizes high strength at low temperature, and has low thermal conductivity and high thermal shock stability.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of refractory materials, and particularly relates to an aluminum-thermal reaction sintered alumina hollow sphere heat-insulating refractory material and a preparation method thereof. BACKGROUND

[0002] The alumina hollow sphere product has excellent heat-insulating performance, and can be used as a heat-insulating material for high-temperature kilns to reduce heat loss and energy consumption and save production cost. In addition, the alumina hollow sphere product has good refractory performance, and is often used as a non-contact molten metal working lining for high-temperature kilns, and the service temperature can reach 1800 DEG C. However, the alumina hollow sphere product has poor thermal shock resistance, and is easy to crack and peel off in an environment with large temperature fluctuations, and is difficult to meet the long-term use requirements of intermittent kilns. In addition, the sintering temperature is high, and the production cost is high.

[0003] Patent CN101429044A discloses an alumina hollow sphere product containing magnesium oxide. Magnesium oxide is introduced into the matrix or the matrix and aggregate of the alumina hollow sphere product, and in-situ generated or pre-synthesized magnesium aluminate spinel phases are formed at high temperatures to improve the thermal shock stability of the product. However, the product needs to be sintered at a high temperature of 1700 DEG C, and the energy consumption is high.

[0004] Patent CN1554616A discloses a preparation method of a light-weight high-strength alumina hollow sphere ceramic. Alumina hollow spheres and alpha-Al2O3 micro-powder are used as raw materials, and a phosphoric acid solution is used as a binder to prepare heat-insulating bricks. However, the bricks also need to be sintered at a high temperature of 1700 DEG C. If sintering is performed at 900 DEG C, the bricks can be used for masonry, but the bricks still need to be sintered at a high temperature for the second time after masonry to meet the use requirements. In addition, the matrix phase of the bricks is dense corundum phase, which leads to high thermal conductivity and poor thermal shock resistance.

[0005] In summary, how to obtain high strength, low thermal conductivity and high thermal shock stability of the alumina hollow sphere material at a low sintering temperature is a technical difficulty at present. SUMMARY

[0006] The present application solves the technical problems existing in the prior art, and provides an aluminum-thermal reaction sintered alumina hollow sphere heat-insulating refractory material and a preparation method thereof. The refractory material is sintered by aluminum-thermal reaction of aluminum and magnesium peroxide, a continuous spinel structure is formed on the matrix and the surface of the alumina hollow sphere, high strength is achieved at a low sintering temperature, and low thermal conductivity and high thermal shock stability are also considered.

[0007] In order to solve the technical problem raised by the present invention, the present invention provides an aluminothermic reaction sintered alumina hollow ball insulating refractory material, which includes the following raw materials in percentage by weight: 20-30% of alumina hollow balls with a particle size of 3-5 mm, 10-20% of alumina hollow balls with a particle size of 1-3 mm, 5-15% of alumina hollow balls with a particle size of 0.1-1 mm, 2-10% of light-burned magnesia, 20-30% of activated alumina powder, 15-25% of magnesium peroxide powder, 4-7% of metallic aluminum powder, and an additional binder accounting for 2-4% of the total weight of the above raw materials.

[0008] In the above solution, the Al2O3 content of the hollow alumina spheres is greater than 99%.

[0009] In the above scheme, the MgO content of the light-burned magnesia is greater than 92%, and the particle size is 180-325 meshes.

[0010] In the above solution, the Al2O3 content of the activated alumina powder is greater than 99%, and the particle size is less than 325 meshes.

[0011] In the above scheme, the MgO2 content of the magnesium peroxide powder is ≥99.9%, the particle size is <10μm, and the median particle size D 50 0.5~1.5μm.

[0012] In the above solution, the Al content of the metal aluminum powder is ≥99% and the particle size is <50 μm.

[0013] In the above solution, the binder is a viscous liquid organic substance.

[0014] Preferably, the binder is one or more of tung oil, phenolic resin, maltose, honey, etc.

[0015] Furthermore, when the binder is a phenolic resin, a resin curing agent needs to be added, and the amount of the resin curing agent added is 1 to 4% of the mass of the phenolic resin.

[0016] In the above solution, the mass ratio of the magnesium peroxide powder to the metallic aluminum powder is (3.12-3.5):1.

[0017] Preferably, the sum of the mass of the magnesium peroxide powder and the metallic aluminum powder accounts for 20 to 32% of the total mass of the raw materials excluding the binder.

[0018] The present invention also provides a method for preparing a heat-insulating refractory material of hollow alumina balls sintered by thermite reaction, comprising the following steps:

[0019] 1) ball-milling magnesium peroxide powder, metallic aluminum powder and a portion of a binder to prepare a thermite;

[0020] 2) adding activated alumina powder to the thermite and continuing to ball mill and mix to obtain a diluted thermite;

[0021] 3) mixing and stirring the alumina hollow spheres of each particle size, the light-burned magnesia and the remaining binder to obtain light-burned magnesia-wrapped alumina hollow spheres;

[0022] 4) mixing and stirring the light-burned magnesia-wrapped alumina hollow spheres and the dilute thermite to obtain a mixture;

[0023] 5) filling the mixture into a mold, compacting by vibration and surface pressing and flattening, demolding after shaping, naturally air-drying, heating to 600-700℃, initiating the aluminothermic reaction of the magnesium peroxide powder and the aluminum powder, and sintering the alumina hollow sphere thermal insulation refractory material as a whole.

[0024] In the above scheme, the ball milling is carried out in vacuum or inert atmosphere, the ball milling speed is 16-50 r / min, the ball milling time in step 1) is 2-4 h, and the ball milling time in step 2) is 1-2 h, and the material temperature during ball milling is ≤60℃.

[0025] In the above scheme, the amount of the binder in step 1) is 50-70% of the total amount of the binder.

[0026] In the above scheme, the stirring speed in step 3) is 45-90 r / min, and the stirring time is 10-30 min.

[0027] In the above scheme, the stirring speed in step 4) is 60-120 r / min, and the stirring time is 10-30 min.

[0028] In the above scheme, the pressure of the pressing and flattening is 0.4-0.6 MPa.

[0029] In the above scheme, the time of the natural air-drying is 24-48 h.

[0030] In the above scheme, the time of the heating is 20-30 min.

[0031] In the above scheme, the volume density of the alumina hollow sphere thermal insulation refractory material sintered by the aluminothermic reaction is 1.20-1.40 g / cm 3 , the cold crushing strength is 16-25 MPa, the thermal conductivity at a hot face temperature of 1000℃ is 0.55-0.65 W / m·K, the 1100℃ wind-cooled thermal cycle is 15-20 times, and the 0.1 MPa load softening temperature is >1700℃.

[0032] The technical principle of the present application is as follows:

[0033] The peroxide magnesium reacts with the metal aluminum powder to generate spinel and magnesium oxide (reaction formula 1), and the theoretical consumption ratio of the peroxide magnesium and the metal aluminum powder is 3.11:1; the excessive peroxide magnesium is decomposed into oxygen and magnesium oxide at 300-500 DEG C (reaction formula 2), a large number of bubbles are uniformly dispersed in the matrix, the bulk density and the thermal conductivity of the material are reduced, and the heat insulation effect is better; the generated magnesium oxide reacts with the active aluminum oxide again, the Al2O3 on the surface of the aluminum oxide hollow sphere reacts with the active magnesium sand, a continuous spinel structure is formed on the surface of the matrix and the aluminum oxide hollow sphere (reaction formula 3), the connection between the aluminum oxide hollow sphere particles is more compact, and the strength and the thermal shock resistance of the material are improved.

[0034] Reaction formula 1: 3MgO2+2Al=2MgO+MgAl2O4;

[0035] Reaction formula 2: 2MgO2=2MgO+O2↑;

[0036] Reaction formula 3: MgO+Al2O3=MgAl2O4.

[0037] Compared with the prior art, the present application has the following beneficial effects:

[0038] 1) The present application adopts the peroxide magnesium as the oxygen source, generates the spinel by the aluminothermic reaction with the metal aluminum, releases a large amount of heat at the same time, makes the material self-sintering, significantly reduces the sintering energy consumption, and decomposes the excessive peroxide magnesium to generate oxygen, uniformly disperses the small bubbles in the matrix, reduces the bulk density and the thermal conductivity of the material, and improves the heat insulation effect.

[0039] 2) The present application mixes the active aluminum oxide powder with the aluminothermic agent, dilutes and disperses the aluminothermic agent, reduces the reaction intensity of the aluminothermic agent, avoids the material cracking caused by the local temperature being too high, and makes the active aluminum oxide powder fully contact with the magnesium oxide generated by the aluminothermic reaction and the magnesium oxide generated by the decomposition of the excessive peroxide magnesium, forms the spinel in the matrix in situ, has a certain volume expansion, compensates the shrinkage generated by the powder melting and sintering at high temperature, makes the combination between the aluminum oxide hollow sphere and the matrix more compact, improves the material strength, and makes the MgO on the surface of the active magnesium sand react with the aluminum oxide hollow sphere and the active aluminum oxide powder to generate the spinel, connects the spinel and the aluminum oxide hollow sphere in the matrix into a network structure, and improves the strength and the thermal shock stability of the material. DETAILED DESCRIPTION

[0040] In order to better understand the present application, the content of the present application is further illustrated below in combination with the examples, but the content of the present application is not limited to the following examples.

[0041] In the following examples, the Al2O3 content of the alumina hollow spheres used is >99%; the MgO content of the light-burned magnesite is >92%, and the particle size is 180-325 mesh; the Al2O3 content of the active alumina powder is >99%, and the particle size is <325 mesh; the MgO2 content of the periclase powder is >99.9%, and the particle size is <10 μm, and the median particle size D50 is 0.5-1.5 μm; and the Al content of the metallic aluminum powder is >99%, and the particle size is <50 μm. 50 In the following examples, the Al2O3 content of the alumina hollow spheres used is >99%; the MgO content of the light-burned magnesite is >92%, and the particle size is 180-325 mesh; the Al2O3 content of the active alumina powder is >99%, and the particle size is <325 mesh; the MgO2 content of the periclase powder is >99.9%, and the particle size is <10 μm, and the median particle size D50 is 0.5-1.5 μm; and the Al content of the metallic aluminum powder is >99%, and the particle size is <50 μm.

[0042] Example 1

[0043] The aluminum-thermic reaction sintered alumina hollow sphere heat-insulating refractory material in this example comprises the following raw materials in mass percentage: 20% of alumina hollow spheres with a particle size of 3-5 mm (not including 5 mm), 15% of alumina hollow spheres with a particle size of 1-3 mm (not including 3 mm), 10% of alumina hollow spheres with a particle size of 0.1-1 mm (not including 1 mm), 5% of light-burned magnesite, 24% of active alumina powder, 20% of periclase powder, and 6% of metallic aluminum powder, and 2% of tung oil is additionally added to the total mass of the above raw materials.

[0044] The aluminum-thermic reaction sintered alumina hollow sphere heat-insulating refractory material in this example comprises the following raw materials in mass percentage: 20% of alumina hollow spheres with a particle size of 3-5 mm (not including 5 mm), 15% of alumina hollow spheres with a particle size of 1-3 mm (not including 3 mm), 10% of alumina hollow spheres with a particle size of 0.1-1 mm (not including 1 mm), 5% of light-burned magnesite, 24% of active alumina powder, 20% of periclase powder, and 6% of metallic aluminum powder, and 2% of tung oil is additionally added to the total mass of the above raw materials.

[0045] 1) The periclase powder and the metallic aluminum powder are placed in a ball mill with an atmosphere protection device and a cooling device, a portion of the tung oil (70% of the total amount of tung oil) is added, argon gas is filled for protection, the ball mill is started, the rotation speed is 25 r / min, and the ball milling and mixing is carried out for 4 h, the material temperature during the ball milling process is ≤60℃, and the thermite is prepared;

[0046] 2) The active alumina powder is added to the thermite, the ball milling and mixing is continued for 1 h, the material temperature during the ball milling process is ≤60℃, and the diluted thermite is obtained;

[0047] 3) The alumina hollow spheres with different particle sizes and the light-burned magnesite are placed in a stirrer, the remaining tung oil is added, the stirring is carried out at a speed of 90 r / min for 30 min, and the light-burned magnesite coated alumina hollow spheres are obtained;

[0048] 4) The diluted thermite is further added to the stirrer, and is stirred and mixed with the light-burned magnesite coated alumina hollow spheres, the stirring speed is 90 r / min, and the stirring time is 30 min, and the mixture is obtained;

[0049] 5) The mixture is filled in a 500mmx500mmx100mm mold, vibrated and compacted, and the surface is pressed flat at 0.4MPa. After setting, it is demolded, naturally placed for 24h to dry, and further dried at 100℃±10℃ for 48h. Then it is placed on a kiln car with magnesia particles, and put into a medium temperature heating furnace at 650℃ for 30min to initiate the aluminothermic reaction of magnesium peroxide powder and aluminum powder, so that the whole alumina hollow sphere thermal insulation refractory is sintered.

[0050] Example 2

[0051] The aluminothermic reaction sintered alumina hollow sphere thermal insulation refractory in this example comprises the following raw materials by mass percentage: 25% of alumina hollow spheres with a particle size of 3-5mm (not including 5mm), 10% of alumina hollow spheres with a particle size of 1-3mm (not including 3mm), 8% of alumina hollow spheres with a particle size of 0.1-1mm (not including 1mm), 6% of light burned magnesia, 22% of active alumina powder, 22% of magnesium peroxide powder, and 7% of aluminum powder, and 4% of maltose is additionally added to the total mass of the above raw materials.

[0052] The preparation method of the aluminothermic reaction sintered alumina hollow sphere thermal insulation refractory in this example comprises the following steps:

[0053] 1) The magnesium peroxide powder and aluminum powder are placed in a ball mill with atmosphere protection device and cooling device, a part of the maltose (50% of the total amount of maltose) is added, argon gas is filled for protection, the ball mill is started, the rotating speed is 20r / min, and the ball milling and mixing is carried out for 3h, the material temperature during ball milling is ≤50℃, and the aluminothermic agent is prepared;

[0054] 2) The active alumina powder is added to the aluminothermic agent, and the ball milling and mixing is continued for 2h, the material temperature during ball milling is ≤50℃, and the diluted aluminothermic agent is obtained;

[0055] 3) The alumina hollow spheres with different particle sizes and light burned magnesia are placed in a stirrer, the remaining maltose is added, and stirring is carried out at a speed of 60r / min for 30min to obtain light burned magnesia coated alumina hollow spheres;

[0056] 4) The diluted aluminothermic agent is further added to the stirrer and stirred and mixed with the light burned magnesia coated alumina hollow spheres, the stirring speed is 120r / min, and the stirring time is 20min to obtain the mixture;

[0057] 5) The mixture is filled in a 500mmx500mmx100mm mold, vibrated and compacted, and the surface is pressed flat at 0.6MPa. After setting, it is demolded, naturally placed for 24h to dry, and placed on bauxite fine sand, and heated to 600-700℃ by a flame spray gun for 20min to initiate the aluminothermic reaction of magnesium peroxide powder and aluminum powder, so that the whole alumina hollow sphere thermal insulation refractory is sintered.

[0058] Example 3

[0059] The aluminum thermal reaction sintered alumina hollow sphere heat-insulating refractory material in this example comprises the following raw materials by mass percentage: 22% of alumina hollow spheres with a particle size of 3-5 mm (not including 5 mm), 10% of alumina hollow spheres with a particle size of 1-3 mm (not including 3 mm), 7% of alumina hollow spheres with a particle size of 0.1-1 mm (not including 1 mm), 8% of light-burned magnesia, 22% of active alumina powder, 24% of magnesium peroxide powder, and 7% of aluminum metal powder, and 3% of phenolic resin is additionally added to the total mass of the above raw materials, and 1% of urotropine is additionally added to the mass of the phenolic resin.

[0060] The preparation method of the aluminum thermal reaction sintered alumina hollow sphere heat-insulating refractory material in this example comprises the following steps:

[0061] 1) The magnesium peroxide powder and the aluminum metal powder are placed in a ball mill with an atmosphere protection device and a cooling device, a part of the phenolic resin (2% of the total mass of the raw materials) is added, argon gas is filled for protection, the ball mill is started, the rotating speed is 30 r / min, and the ball milling and mixing are performed for 4 h, the material temperature during the ball milling process is ≤60℃, and the thermite is prepared;

[0062] 2) The active alumina powder is added to the thermite, the ball milling and mixing are continuously performed for 1 h, the material temperature during the ball milling process is ≤60℃, and the diluted thermite is obtained;

[0063] 3) The alumina hollow spheres with different particle sizes and the light-burned magnesia are placed in a stirrer, the remaining phenolic resin (1% of the total mass of the raw materials) is added, the stirring is performed at a speed of 45 r / min for 30 min, and the light-burned magnesia wrapped alumina hollow spheres are obtained;

[0064] 4) The diluted thermite is further added to the stirrer, the light-burned magnesia wrapped alumina hollow spheres are stirred and mixed at a speed of 90 r / min for 20 min, and the urotropine is further added and stirred for 5 min, and the mixture is obtained;

[0065] 5) The mixture is filled in a mold with a size of 500 mm×500 mm×100 mm, is compacted by vibration, is leveled on the surface by surface pressurization of 0.5 MPa, is demolded after shaping, is naturally placed for 24 h for air drying, is placed on a kiln car paved with corundum fine sand, is put into a medium-temperature furnace at 700℃, is calcined for 25 min, the aluminum thermal reaction of the magnesium peroxide powder and the aluminum metal powder is initiated, and the whole sintering of the alumina hollow sphere heat-insulating refractory material is performed.

[0066] Comparative Example 1

[0067] The difference between Comparative Example 1 and Example 1 is only that the magnesium peroxide is 18% and the aluminum metal powder is 8%.

[0068] Comparative Example 2

[0069] Comparative Example 2 differs from Example 1 only in that the ball mill is an air atmosphere.

[0070] Comparative Example 3

[0071] Comparative Example 3 differs from Example 2 only in that the magnesium peroxide is 24% and the aluminum metal powder is 5%.

[0072] Comparative Example 4

[0073] Comparative Example 4 differs from Example 2 only in that the heating temperature is 500-600°C.

[0074] Comparative Example 5

[0075] Comparative Example 5 differs from Example 3 only in that the ball mill and the step mixing process are not used, all of the raw materials are mixed at one time using a stirrer, and the phenolic resin and the urotropine are added at the end.

[0076] Comparative Example 6

[0077] Comparative Example 6 differs from Example 3 only in that, in addition to the other components, 3% of the total amount of magnesium peroxide powder and 1% of the total amount of aluminum metal powder are added.

[0078] The volume density, the cold compressive strength, the thermal conductivity, and the thermal shock resistance of the alumina hollow sphere thermal insulation refractory material of each example and comparative example were detected according to GB / T 4513.6-2017.

[0079] The detection data of each example and the current domestic industry standard technical index are shown in the following table:

[0080]

[0081] The detection data of each comparative example are as follows:

[0082]

[0083] As can be seen from the data of the alumina hollow sphere thermal insulation refractory material in each example and comparative example and the conventional alumina hollow sphere brick in the industry standard, the alumina hollow sphere thermal insulation refractory material provided by the application, because of the self-reaction and integral sintering, forms a spinel network framework in the matrix and between the alumina hollow spheres, significantly improves the cold compressive performance and the thermal shock resistance of the material, because of the decomposition of the magnesium peroxide, generates uniformly dispersed small bubbles, further reduces the volume density and the thermal conductivity, and does not need to consume time and energy to sinter the product at high temperature, saves the energy of the alumina hollow sphere brick sintering loss, and can greatly improve the production efficiency, and the purity of the raw material is high and the high temperature performance is good.

[0084] The above embodiments are merely exemplary but not intended to limit the present application. Based on the above description, those skilled in the art can make other variations and modifications of the present application without departing from the scope of the present application. Therefore, the intended scope of the present application should be defined by the appended claims.

Claims

1. An alumina hollow sphere thermal insulating refractory material sintered by aluminothermic reaction, characterized in that, The raw materials include the following mass percentages: 20-30% of alumina hollow spheres with a particle size of 3-5 mm, 10-20% of alumina hollow spheres with a particle size of 1-3 mm, 5-15% of alumina hollow spheres with a particle size of 0.1-1 mm, 2-10% of light-burned magnesia, 20-30% of active alumina powder, 15-25% of magnesium peroxide powder, and 4-7% of metallic aluminum powder, and 2-4% of the total mass of the above raw materials is added as a binder; The preparation method of the aluminum-thermal reaction sintered alumina hollow sphere heat-insulating refractory material includes the following steps: 1) The magnesium peroxide powder, the metallic aluminum powder, and a part of the binder are ball-mixed to prepare an aluminothermic agent; 2) The active alumina powder is added to the aluminothermic agent, and the ball-mixing is continued to obtain a diluted aluminothermic agent; 3) The alumina hollow spheres with different particle sizes, the light-burned magnesia, and the remaining binder are mixed and stirred to obtain light-burned magnesia-coated alumina hollow spheres; 4) The light-burned magnesia-coated alumina hollow spheres and the diluted aluminothermic agent are mixed and stirred to obtain a mixture; 5) The mixture is filled into a mold, is compacted by vibration, is flattened on the surface by pressure, is demolded after setting, is naturally air-dried, is heated to 600-700 DEG C, and is subjected to an aluminothermic reaction of the magnesium peroxide powder and the metallic aluminum powder to sinter the whole alumina hollow sphere heat-insulating refractory material.

2. The aluminum thermal reaction sintered alumina hollow sphere heat insulating refractory material according to claim 1, characterized in that, The sum of the mass of the magnesium peroxide powder and the mass of the metallic aluminum powder is 20-32% of the total mass of the raw materials excluding the binder; and the mass ratio of the magnesium peroxide powder to the metallic aluminum powder is (3.12-3.5):

1.

3. The aluminum thermal reaction sintered alumina hollow sphere heat insulating refractory material according to claim 1, characterized in that, The binder is one or more of tung oil, phenolic resin, maltose, and honey; when the binder is the phenolic resin, a resin curing agent also needs to be added, and the addition amount of the resin curing agent is 1-4% of the mass of the phenolic resin.

4. The aluminum thermal reaction sintered alumina hollow sphere heat insulating refractory material according to claim 1, characterized in that, The MgO2 content of the magnesium peroxide powder is ≥ 99.9%, the particle size is < 10 μm, and the median particle size D50 is 0.5-1.5 μm; the Al content of the aluminum metal powder is ≥ 99%, the particle size is < 50 μm; and the Al2O3 content of the activated aluminum oxide powder is > 99%, the particle size is < 325 mesh. 50 The MgO2 content of the magnesium peroxide powder is ≥ 99.9%, the particle size is < 10 μm, and the median particle size D50 is 0.5-1.5 μm; the Al content of the aluminum metal powder is ≥ 99%, the particle size is < 50 μm; and the Al2O3 content of the activated aluminum oxide powder is > 99%, the particle 5. The aluminum thermal reaction sintered alumina hollow sphere heat insulating refractory material according to claim 1, characterized in that, The Al2O3 content of the alumina hollow spheres is >99%, and the MgO content of the light-burned magnesia is >92%, and the particle size is 180-325 mesh.

6. The aluminum thermal reaction sintered alumina hollow sphere thermal and fire resistant material of claim 1, wherein, The volume density of the aluminum hot reaction sintered alumina hollow ball heat insulation refractory material is 1.20-1.40 g / cm 3 The cold compressive strength is 16-25 MPa, the thermal conductivity coefficient is 0.55-0.65 W / m·K when the hot surface temperature is 1000 DEG C, the 1100 DEG C air cooling thermal cycle is 15-20 times, and the 0.1 MPa load softening temperature is > 1700 DEG C.

7. A method of producing the aluminum-thermally reacted sintered alumina hollow sphere heat-insulating refractory material according to any one of claims 1 to 6, characterized by, The preparation method of the aluminum-thermal reaction sintered alumina hollow sphere heat-insulating refractory material includes the following steps: 1) The magnesium peroxide powder, the metallic aluminum powder, and a part of the binder are ball-mixed to prepare an aluminothermic agent; 2) The active alumina powder is added to the aluminothermic agent, and the ball-mixing is continued to obtain a diluted aluminothermic agent; 3) The alumina hollow spheres with different particle sizes, the light-burned magnesia, and the remaining binder are mixed and stirred to obtain light-burned magnesia-coated alumina hollow spheres; 4) The light-burned magnesia-coated alumina hollow spheres and the diluted aluminothermic agent are mixed and stirred to obtain a mixture; 5) The mixture is filled into a mold, is compacted by vibration, is flattened on the surface by pressure, is demolded after setting, is naturally air-dried, is heated to 600-700 DEG C, and is subjected to an aluminothermic reaction of the magnesium peroxide powder and the metallic aluminum powder to sinter the whole alumina hollow sphere heat-insulating refractory material.

8. The method for preparing the thermal reaction sintered alumina hollow sphere insulating refractory material according to claim 7, characterized in that: The ball-mixing is performed under vacuum or in an inert atmosphere, the ball-milling speed is 16-50 r / min, the ball-milling time in step 1) is 2-4 h, the ball-milling time in step 2) is 1-2 h, and the material temperature during the ball-milling process is ≤60 DEG C.

9. The method for preparing the thermal reaction sintered alumina hollow sphere insulating refractory material according to claim 7, characterized in that: In step 1), the amount of the binder is 50-70% of the total amount of the binder; in step 3), the stirring speed is 45-90 r / min, and the stirring time is 10-30 min; and in step 4), the stirring speed is 60-120 r / min, and the stirring time is 10-30 min.

10. The method for preparing the thermal reaction sintered alumina hollow sphere insulating refractory material according to claim 7, characterized in that: The pressure of the pressurized leveling is 0.4-0.6 MPa; the time of the natural air-drying is 24-48 h; and the time of the heating is 20-30 min.

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