Heavy calcium hexaluminate high-temperature-resistant material and preparation method thereof

Abstract

The invention discloses a heavy calcium hexaluminate high-temperature-resistant material and a preparation method thereof, and belongs to the technical field of high-temperature-resistant materials. The preparation method of the heavy calcium hexaluminate high-temperature-resistant material provided by the invention comprises the following steps: mixing aluminum oxide, calcium carbonate and a sintering aid to prepare a mixture; a binding agent is added into the mixture, pelletizing treatment is conducted, and green pellets are prepared; the binding agent is pure water; the green pellets are dried; the dried green pellets are put into an ultrahigh-temperature shaft kiln to be calcined, the calcination temperature ranges from 1760 DEG C to 1810 DEG C, then rapid cooling is conducted, and the heavy calcium hexaluminate high-temperature-resistant material is prepared. The invention further provides application of the heavy calcium hexaluminate high-temperature-resistant material in hydrogen metallurgy. The heavy calcium hexaluminate high-temperature-resistant material is prepared by adopting the preparation method. The heavy calcium hexaluminate high-temperature-resistant material is high in volume density and low in apparent porosity, and has good reducing atmosphere resistance, slag corrosion resistance and creep resistance.

Description

Technical Field

[0001] The present application belongs to the technical field of high-temperature resistant materials, and specifically relates to a heavy calcium hexaaluminate high-temperature resistant material and a preparation method thereof. Background Art

[0002] Hydrogen, a clean and pollution-free reducing agent, is increasingly being used in the ironmaking process. Unlike traditional carbon-based reduction methods, hydrogen reacts with iron oxide or ferrous oxide to produce only water, without generating greenhouse gases like carbon dioxide. Therefore, it is considered an ideal carbon replacement for future steel production. With the development of new energy industries and technological advancements, the cost of hydrogen is expected to decrease, further promoting its economic viability as a reducing agent.

[0003] Currently, ironmaking processes using carbon as a reducing agent primarily use brown corundum, mullite, bauxite, pyroxene, and silicon carbide products as refractory materials. These silica-containing refractories perform well at high temperatures using carbon reducing agents, meeting the requirements of traditional ironmaking processes. However, under hydrogen reducing agent conditions, since hydrogen is a gas that can be evenly distributed and reacted throughout the blast furnace at the appropriate temperature, furnace linings made from silica-containing refractories are easily reduced to elemental silicon by hydrogen at high temperatures, resulting in structural damage and a decrease or loss of high-temperature resistance. Furthermore, these materials have high wettability with molten metals and slag (such as steel and non-ferrous metals), accelerating material erosion and shortening their service life.

[0004] Faced with these challenges, a new refractory material with excellent performance and adaptability to hydrogen reduction processes is crucial. In this context, calcium hexaaluminate (CA6) is an ideal refractory material for hydrogen-reducing ironmaking due to its excellent chemical stability and low wettability by molten metal and slag. Furthermore, its coefficient of thermal expansion is similar to that of alumina, allowing it to be mixed with alumina in any ratio, enhancing the design flexibility of the composite material.

[0005] The common CA6 products on the market currently have a volume density of less than 0.8g / cm 3 Lightweight CA6 insulation material with a bulk density less than 3.1g / cm 3 Heavy CA6, but the existing CA6 products have insufficient bulk density, large apparent porosity, and low strength, and cannot provide sufficient slag corrosion resistance, creep resistance, and wear resistance, and therefore cannot meet the working environment requirements of ladles or steel ladles.

[0006] Therefore, there is an urgent need to develop a heavy calcium hexaaluminate high-temperature resistant material with good resistance to reducing atmosphere, slag corrosion and creep resistance. Summary of the Invention

[0007] In view of this, the present application provides a heavy calcium hexaaluminate high-temperature resistant material and a preparation method thereof. The heavy calcium hexaaluminate high-temperature resistant material provided in the present application has high volume density, low apparent porosity, and good resistance to reducing atmosphere, slag corrosion and creep resistance.

[0008] In a first aspect, the present application provides a method for preparing a heavy calcium hexaaluminate high temperature resistant material, comprising the following steps:

[0009] Step S1, mixing aluminum oxide, calcium carbonate, and a sintering aid to prepare a mixture;

[0010] Step S2, adding a binder to the mixture and performing a ball-forming process to obtain green balls; the binder is pure water;

[0011] Step S3, placing the green pellets in a tower dryer for drying, with a maximum drying temperature of 300-500° C. and a drying time of 5-12 hours;

[0012] Step S4: putting the dried green balls into an ultra-high temperature vertical kiln for calcination at a temperature of 1760-1810°C for 0.5-1.5 hours, and then rapidly cooling to 800-1000°C at a cooling rate of 8-10°C / min to obtain the heavy calcium hexaaluminate high temperature resistant material.

[0013] By adopting the above-mentioned technical solution, the preparation method of the present application can increase the bulk density of the heavy calcium hexaaluminate high-temperature resistant material and reduce the apparent porosity, thereby imparting excellent resistance to reducing atmospheres, slag corrosion, and creep. The resulting heavy calcium hexaaluminate high-temperature resistant material can be used in harsh working environments such as hydrogen reduction ironmaking, providing strong support for future low-carbon ironmaking processes.

[0014] In step S1 of the present application, the raw materials are uniformly mixed and ground, which promotes the subsequent solid-phase reaction process and improves the density of the product; and the presence of the sintering aid reduces the sintering temperature and maintains good density. In step S2, pure water is used as a binder in combination with the alumina raw material, and the hydration of the amorphous transition phase alumina contained in the alumina is utilized to help the particles bond together to form a stable structure with high mechanical strength, which can prevent disintegration during the drying and calcination process. Pure water is used as a binder and will not introduce impurities, which is beneficial to improving the purity of the product and thus improving the high temperature resistance of the product. This preforming method can achieve automatic control, with high output, high efficiency, and low cost. It can also control the particle size distribution of the final product, which is conducive to obtaining an ideal microstructure. The specific drying conditions in step S3 can evenly discharge excess moisture from the green ball without causing stress concentration due to excessively rapid drying of the surface, which is beneficial to maintaining the integrity of the finished product and reducing the apparent porosity. Combined with the specific calcination temperature and appropriate calcination time in step S4, it is beneficial to form a product with high bulk density and low apparent porosity; rapid cooling preserves a large number of closed pores within the crystal, and these tiny and evenly distributed pores enhance the thermal shock stability of the material.

[0015] Optionally, in step S1, the aluminum oxide is metallurgical grade aluminum oxide with a purity of 99.5% to 99.9%; and the purity of the calcium carbonate is ≥98.5%.

[0016] By adopting the above-mentioned technical solution, the present application selects metallurgical-grade alumina as raw material, and makes full use of the amorphous transition phase alumina contained in metallurgical-grade alumina, which undergoes a hydration reaction when in contact with water to form a hydrate with a certain adhesiveness. This characteristic can make the subsequent green balls have better mechanical strength, which not only meets the transportation requirements of subsequent processes, but also high purity means lower impurity content, which can reduce the impact of other elements on the high-temperature resistance of the material. The specific type of alumina used in this application can better cooperate with calcium carbonate, which is conducive to calcination to form a regular and dense crystal structure, improve the material's resistance to slag corrosion and creep resistance, and improve the performance of the final product. Moreover, in a hydrogen reducing atmosphere, the lower impurity level helps to maintain the chemical stability of the material and prevent unnecessary side reactions.

[0017] Optionally, in step S1, the sintering aid includes at least one of a titanium-containing sintering aid and a barium-containing sintering aid;

[0018] The titanium-containing sintering aid comprises 73-75% aluminum oxide, 12-13% calcium oxide, and 13-14% titanium dioxide.

[0019] The barium-containing sintering aid comprises 72-74% aluminum oxide, 12-13% calcium oxide and 14-15% barium carbonate.

[0020] Optionally, in step S1, the content of the aluminum oxide is 78-80 wt %, the content of the calcium carbonate is 11-13 wt %, and the content of the sintering aid is 8-10 wt %.

[0021] By adopting the above technical solution, the specific ratio of the raw materials in this application achieves a balance of material properties, achieving higher bulk density, lower apparent porosity, good resistance to reducing atmosphere, slag corrosion and creep resistance.

[0022] Pure water, a binder, hydrates the amorphous transition phase of alumina in metallurgical-grade alumina to form gibbsite and boehmite gels. This water gradually evaporates in gaseous form between 100°C and 550°C, forming uniform pores within the spherical body. At 800-900°C, calcium carbonate decomposes to form solid calcium oxide and carbon dioxide gas. The gaseous carbon dioxide is expelled through the pores left by the previous water evaporation, preventing cracking and explosion in the green body. Simultaneously, the newly decomposed solid calcium oxide is highly reactive and readily reacts with alumina to form calcium hexaaluminate. During the high-temperature stage, sintering aids allow for rapid densification, ultimately resulting in a heavy calcium hexaaluminate with 100% CA6 phase purity, high bulk density, and low apparent porosity.

[0023] Optionally, in step S1, the particle size D50 of the mixture is 3.0-5.0 μm.

[0024] By adopting the above technical solution, the particle size of the mixture of the present application can promote uniform mixing, increase the surface area of the reaction, thereby improving the reaction rate and degree. It also helps to form a dense structure and improve the bulk density and mechanical strength of the material.

[0025] Optionally, in step S2, the content of the binder is 17-20 wt % based on the mass percentage of the mixture.

[0026] By adopting the above technical solution, the present application uses pure water as a binder, which does not introduce harmful substances, meets environmental protection requirements, avoids the volatile organic compound emissions that may be caused by traditional organic binders, and reduces costs. In addition, due to the inherent hydration properties of metallurgical-grade alumina, the use of pure water as a binder simplifies the process flow and reduces the problems that may arise from using complex binders.

[0027] Optionally, in step S2, the particle size of the green balls is 18 to 30 mm.

[0028] By adopting the above technical solution, the green ball particle size of this application facilitates more uniform heating during the drying and calcining processes, reducing internal stress and cracking caused by temperature gradients. It also provides the green balls with sufficient mechanical strength to withstand the pressure during transportation and stacking, reducing breakage losses. The specific green ball particle size facilitates the expulsion of internal gases during calcination, reducing apparent porosity and improving the material's slag erosion and creep resistance.

[0029] Optionally, in step S4, the calcination temperature is 1770-1800°C.

[0030] Optionally, the bulk density of the heavy calcium hexaaluminate high temperature resistant material is 3.4 to 3.55 g / cm 3 , apparent porosity ≤8.0%, water absorption ≤2.0%.

[0031] By adopting the above technical solution, the high volume density, low apparent porosity and water absorption of heavy calcium hexaaluminate high temperature resistant material can significantly improve the material's resistance to slag corrosion and alkaline environment corrosion, and has good creep resistance and thermal shock resistance, making it suitable for working environments such as hydrogen reduction ironmaking.

[0032] In a second aspect, the present application provides an application of a heavy calcium hexaaluminate high-temperature resistant material in hydrogen metallurgy, wherein the heavy calcium hexaaluminate high-temperature resistant material is prepared using the above-mentioned preparation method.

[0033] By adopting the above technical solution, the high-temperature resistant heavy calcium hexaaluminate material produced in this application can be directly used for the working lining of hydrogen metallurgical furnaces. In addition, the calcium-containing material also has a purifying effect on molten iron and molten steel, and is particularly friendly to ultra-low carbon steel and clean steel, without contaminating the molten steel.

[0034] The heavy calcium hexaaluminate high-temperature resistant material prepared in this application has high bulk density, low apparent porosity, good resistance to reducing atmosphere, slag corrosion resistance and creep resistance, and performs excellently in hydrogen reducing atmosphere. It is an ideal refractory material choice in future steel production and can contribute to achieving global carbon emission reduction goals.

[0035] In summary, the present invention includes at least one of the following beneficial technical effects:

[0036] 1. The preparation method of the present application can increase the bulk density of heavy calcium hexaaluminate high-temperature resistant material, reduce the apparent porosity, and enable the heavy calcium hexaaluminate high-temperature resistant material to obtain good resistance to reducing atmosphere, slag corrosion resistance and creep resistance.

[0037] 2. The heavy calcium hexaaluminate high-temperature resistant material produced in this application has a high bulk density, low apparent porosity, good resistance to reducing atmosphere, slag corrosion resistance and creep resistance, and performs well in a hydrogen reducing atmosphere. It is an ideal refractory material choice for future steel production and can contribute to achieving global carbon emission reduction goals. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is a scanning electron microscope image of the heavy calcium hexaaluminate high temperature resistant material prepared in Example 3;

[0039] Figure 2 This is the X-ray diffraction pattern of the heavy calcium hexaaluminate high temperature resistant material prepared in Example 3. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solutions and advantages of this application more clear, the following further describes this application in detail with reference to the embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0041] The inventors of this application found in their research on calcium hexaaluminate high-temperature resistant materials that the bulk density of the calcium hexaaluminate high-temperature resistant materials in the prior art is not high enough, the apparent porosity is relatively large, and they cannot provide sufficient slag corrosion resistance and creep resistance, nor can they meet the working environment requirements of ladles or steel ladles.

[0042] In order to solve the above problems, the present application proposes a method for preparing a heavy calcium hexaaluminate high temperature resistant material, comprising the following steps:

[0043] Step S1, mixing aluminum oxide, calcium carbonate, and a sintering aid to prepare a mixture;

[0044] Step S2, adding a binder to the mixture and performing a ball-forming process to obtain green balls; the binder is pure water;

[0045] Step S3, placing the green pellets in a tower dryer for drying, with a maximum drying temperature of 300-500° C. and a drying time of 5-12 hours;

[0046] Step S4: putting the dried green balls into an ultra-high temperature vertical kiln for calcination at a temperature of 1760-1810°C for 0.5-1.5 hours, and then rapidly cooling to 800-1000°C at a cooling rate of 8-10°C / min to obtain the heavy calcium hexaaluminate high temperature resistant material.

[0047] The present application also provides an application of a heavy calcium hexaaluminate high-temperature resistant material in hydrogen metallurgy. The heavy calcium hexaaluminate high-temperature resistant material is prepared using the above-mentioned preparation method.

[0048] The scheme of the present application is described below with reference to the following specific examples. Unless otherwise specified, the raw materials used in the following examples are all from common commercial products, and the devices or equipment used are all purchased from conventional market sales channels. Specific embodiments

[0050] Example 1

[0051] This embodiment provides a method for preparing a heavy calcium hexaaluminate high temperature resistant material, comprising the following steps:

[0052] Step S1, mixing aluminum oxide, calcium carbonate, and a sintering aid, wherein, by mass percentage, the aluminum oxide content is 78wt%, the calcium carbonate content is 13wt%, and the sintering aid content is 9wt%, to obtain a mixture having a particle size D50 of 5.0 μm; wherein the aluminum oxide is metallurgical grade aluminum oxide with a purity of 99.9%; the calcium carbonate has a purity of 98.5%; and the sintering aid is a titanium-containing sintering aid, wherein the titanium-containing sintering aid has an aluminum oxide content of 73%, a calcium oxide content of 13%, and a titanium dioxide content of 14%;

[0053] Step S2, adding a binder to the mixture and performing a ball-forming process to obtain green balls with a particle size of 18 mm; wherein the binder is pure water; and the content of the binder is 20 wt% based on the mass percentage of the mixture;

[0054] Step S3: placing the green pellets in a tower dryer for drying at a maximum drying temperature of 300° C. for 12 hours;

[0055] Step S4: The dried green balls are put into an ultra-high temperature vertical kiln for calcination at a temperature of 1760°C for 1.5 hours, and then rapidly cooled to 1000°C at a cooling rate of 8°C / min to obtain a heavy calcium hexaaluminate high temperature resistant material.

[0056] Example 2

[0057] This embodiment provides a method for preparing a heavy calcium hexaaluminate high temperature resistant material, comprising the following steps:

[0058] Step S1, mixing aluminum oxide, calcium carbonate, and a sintering aid, wherein, by mass percentage, the aluminum oxide content is 78wt%, the calcium carbonate content is 13wt%, and the sintering aid content is 9wt%, to obtain a mixture having a particle size D50 of 5.0 μm; wherein the aluminum oxide is metallurgical grade aluminum oxide with a purity of 99.9%; the calcium carbonate has a purity of 98.5%; and the sintering aid is a titanium-containing sintering aid, wherein the titanium-containing sintering aid has an aluminum oxide content of 73%, a calcium oxide content of 13%, and a titanium dioxide content of 14%;

[0059] Step S2, adding a binder to the mixture and performing a ball-forming process to obtain green balls with a particle size of 18 mm; wherein the binder is pure water; and the content of the binder is 18 wt% based on the mass percentage of the mixture;

[0060] Step S3: placing the green pellets in a tower dryer for drying at a maximum drying temperature of 400° C. for 8 hours;

[0061] Step S4: The dried green balls are put into an ultra-high temperature vertical kiln for calcination at a temperature of 1785°C for 1 hour, and then rapidly cooled to 900°C at a cooling rate of 9°C / min to obtain a heavy calcium hexaaluminate high temperature resistant material.

[0062] Example 3

[0063] This embodiment provides a method for preparing a heavy calcium hexaaluminate high temperature resistant material, comprising the following steps:

[0064] Step S1, mixing aluminum oxide, calcium carbonate, and a sintering aid, wherein, by mass percentage, the aluminum oxide content is 78wt%, the calcium carbonate content is 13wt%, and the sintering aid content is 9wt%, to obtain a mixture having a particle size D50 of 5.0 μm; wherein the aluminum oxide is metallurgical grade aluminum oxide with a purity of 99.9%; the calcium carbonate has a purity of 98.5%; and the sintering aid is a titanium-containing sintering aid, wherein the titanium-containing sintering aid has an aluminum oxide content of 73%, a calcium oxide content of 13%, and a titanium dioxide content of 14%;

[0065] Step S2, adding a binder to the mixture and performing a ball-forming process to obtain green balls with a particle size of 18 mm; wherein the binder is pure water; and the content of the binder is 17 wt% based on the mass percentage of the mixture;

[0066] Step S3: placing the green pellets in a tower dryer for drying at a maximum drying temperature of 500° C. for 5 hours;

[0067] Step S4: The dried green balls are put into an ultra-high temperature vertical kiln for calcination at a temperature of 1810°C for 0.5 h, and then rapidly cooled to 800°C at a cooling rate of 10°C / min to obtain a heavy calcium hexaaluminate high temperature resistant material.

[0068] Comparative Example 1

[0069] The difference between Comparative Example 1 and Example 2 is that in step S4 of Comparative Example 1, the calcination temperature is 1700°C.

[0070] Comparative Example 2

[0071] The difference between Comparative Example 2 and Example 2 is that in step S1 of Comparative Example 2, the sintering aid is a titanium-containing sintering aid, and the content of aluminum oxide in the titanium-containing sintering aid is 76%, the content of calcium oxide is 14%, and the content of titanium dioxide is 10%.

[0072] Experimental testing

[0073] Test items and methods

[0074] It should be noted that D50 has a well-known meaning in the art, and refers to the particle size corresponding to 50% in the particle size distribution. It can be detected according to methods and instruments known in the art. As an example, it is detected using a Mastersizer 3000 produced by Malvern Company with reference to GB / T 19077-2016.

[0075] Bulk density, apparent porosity, and water absorption were determined using Method 1: Weighing Method, as specified in GB / T 2999-2016, Test Method for Bulk Density of Refractory Particles. The vacuum drying oven used was a DZF-6020 vacuum drying oven manufactured by Shanghai Hongdu Electronic Technology Co., Ltd.

[0076] The bulk density, apparent porosity and water absorption of the heavy calcium hexaaluminate high temperature resistant materials prepared in Examples 1 to 3 and Comparative Examples 1 to 2 were tested. The test results are shown in Table 1.

[0077] Table 1

[0078] <![CDATA[Volume density (g / cm 3 )]]> Apparent porosity (%) Water absorption (%) Example 1 3.40 5.2 1.5 Example 2 3.48 5.0 1.4 Example 3 3.55 3.0 0.9 Comparative Example 1 3.22 13.1 4.1 Comparative Example 2 3.31 10.2 3.1

[0079] From the test results in Table 1, it can be seen that the bulk density of the heavy calcium hexaaluminate high temperature resistant material prepared by the preparation method of the present application in Examples 1 to 3 is high, which can reach 3.4 to 3.55 g / cm 3 , apparent porosity ≤8.0%, water absorption ≤2.0%, thus having good resistance to reducing atmosphere, slag corrosion and creep resistance.

[0080] The calcination temperature of Comparative Example 1 is 1700° C., and the bulk density of the obtained heavy calcium hexaaluminate high-temperature resistant material is significantly reduced, while the apparent porosity and water absorption rate are significantly increased.

[0081] The content of titanium dioxide in the sintering aid of Comparative Example 2 is reduced, the bulk density of the obtained heavy calcium hexaaluminate high-temperature resistant material is reduced, and the apparent porosity and water absorption rate are increased.

[0082] Examples 4 to 11

[0083] Example 4

[0084] The difference between Example 4 and Example 2 is that in step S1 of Example 4, the sintering aid is a barium-containing sintering aid, and the barium-containing sintering aid has an aluminum oxide content of 73%, a calcium oxide content of 13%, and a barium carbonate content of 14%.

[0085] Example 5

[0086] The difference between Example 5 and Example 2 is that in step S1 of Example 5, the sintering aids are a titanium-containing sintering aid and a barium-containing sintering aid in a mass ratio of 1:1;

[0087] The titanium-containing sintering aid comprises 74% aluminum oxide, 12% calcium oxide and 14% titanium dioxide.

[0088] The barium-containing sintering aid comprises 73% aluminum oxide, 13% calcium oxide and 14% barium carbonate.

[0089] Example 6

[0090] The difference between Example 6 and Example 2 is that in step S1 of Example 6, the raw materials of alumina, calcium carbonate and sintering aid are, by mass percentage, 79wt% of alumina, 12wt% of calcium carbonate and 9wt% of sintering aid.

[0091] Example 7

[0092] The difference between Example 7 and Example 2 is that in step S1 of Example 7, the raw materials of alumina, calcium carbonate and sintering aid are, by mass percentage, 80 wt % of alumina, 11 wt % of calcium carbonate and 9 wt % of sintering aid.

[0093] Example 8

[0094] The difference between Example 8 and Example 6 is that in step S1 of Example 8, the particle size D50 of the mixture is 4.0 μm.

[0095] Example 9

[0096] The difference between Example 9 and Example 6 is that in step S1 of Example 9, the particle size D50 of the mixture is 3.0 μm.

[0097] Example 10

[0098] The difference between Example 10 and Example 9 is that in step S2 of Example 10, the particle size of the green balls is 24 mm.

[0099] Example 11

[0100] The difference between Example 11 and Example 9 is that in step S2 of Example 11, the particle size of the green balls is 30 mm.

[0101] The bulk density, apparent porosity and water absorption of the heavy calcium hexaaluminate high temperature resistant materials prepared in Examples 4 to 11 were tested. The test results are shown in Table 2.

[0102] Table 2

[0103] <![CDATA[Apparent density (g / cm 3 )]]> Apparent porosity (%) Water absorption (%) Example 4 3.51 4.0 1.2 Example 5 3.53 4.4 1.3 Example 6 3.47 6.5 1.9 Example 7 3.44 6.4 1.9 Example 8 3.48 5.9 1.7 Example 9 3.50 3.9 1.1 Example 10 3.46 4.7 1.4 Example 11 3.43 6.2 1.8

[0104] From the test results in Table 2, it can be seen that the differences between Example 4 and Example 5 and Example 2 are that the components of the sintering aids are different. Among them, the heavy calcium hexaaluminate high-temperature resistant material prepared in Example 4 has lower apparent porosity and water absorption, and the heavy calcium hexaaluminate high-temperature resistant material prepared in Example 5 has a higher volume density.

[0105] The difference between Example 6 and Example 7 and Example 2 is that the contents of the raw materials alumina, calcium carbonate and sintering aid are different. Among them, the heavy calcium hexaaluminate high-temperature resistant material prepared in Example 6 has a higher volume density and lower apparent porosity and water absorption.

[0106] The difference between Example 8 and Example 9 and Example 6 is that the particle size of the mixture is different. Among them, the heavy calcium hexaaluminate high-temperature resistant material prepared in Example 9 has a higher volume density and lower apparent porosity and water absorption.

[0107] The difference between Example 10 and Example 11 and Example 9 is that the particle size of the green balls is different. Among them, the heavy calcium hexaaluminate high-temperature resistant material prepared in Example 9 has a higher volume density and lower apparent porosity and water absorption rate.

[0108] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements and improvements made within the principles of the present application should be included in the scope of protection of the present application.

Claims

1. A method for preparing a heavy calcium hexaaluminate high temperature resistant material, characterized in that: The following steps are involved: Step S1, mixing aluminum oxide, calcium carbonate, and a sintering aid to prepare a mixture; Step S2, adding a binder to the mixture and performing a ball-forming process to obtain green balls; the binder is pure water; Step S3, placing the green pellets in a tower dryer for drying, with a maximum drying temperature of 300-500° C. and a drying time of 5-12 hours; Step S4: putting the dried green balls into an ultra-high temperature vertical kiln for calcination at a temperature of 1760-1810°C for 0.5-1.5 hours, and then rapidly cooling to 800-1000°C at a cooling rate of 8-10°C / min to obtain the heavy calcium hexaaluminate high temperature resistant material.

2. The preparation method according to claim 1, characterized in that In step S1, the alumina is metallurgical grade alumina with a purity of 99.5% to 99.9%; The purity of the calcium carbonate is ≥98.5%.

3. The preparation method according to claim 1, characterized in that In step S1, the sintering aid includes at least one of a titanium-containing sintering aid and a barium-containing sintering aid; The titanium-containing sintering aid comprises 73-75% aluminum oxide, 12-13% calcium oxide, and 13-14% titanium dioxide. The barium-containing sintering aid comprises 72-74% aluminum oxide, 12-13% calcium oxide and 14-15% barium carbonate.

4. The preparation method according to any one of claims 1 to 3, characterized in that In the step S1, the content of the aluminum oxide is 78-80 wt %, the content of the calcium carbonate is 11-13 wt %, and the content of the sintering aid is 8-10 wt %.

5. The preparation method according to any one of claims 1 to 3, characterized in that In the step S1, the particle size D50 of the mixture is 3.0-5.0 μm.

6. The preparation method according to any one of claims 1 to 3, characterized in that In the step S2, the content of the binder is 17-20 wt % based on the mass percentage of the mixture.

7. The preparation method according to any one of claims 1 to 3, characterized in that In step S2, the particle size of the green balls is 18 to 30 mm.

8. The preparation method according to any one of claims 1 to 3, characterized in that In the step S4, the calcination temperature is 1770-1800°C.

9. The preparation method according to any one of claims 1 to 3, characterized in that The bulk density of the heavy calcium hexaaluminate high temperature resistant material is 3.4-3.55 g / cm 3 , apparent porosity ≤8.0%, water absorption ≤2.0%.

10. Application of a heavy calcium hexaaluminate high temperature resistant material in hydrogen metallurgy, characterized in that: The heavy calcium hexaaluminate high temperature resistant material is prepared by the preparation method according to any one of claims 1 to 8.

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