High-purity dense calcium hexaluminate-based refractory and method for producing the same

Abstract

The application belongs to the technical field of refractory materials, and discloses a high-purity dense calcium hexaluminate-based refractory material, a preparation method thereof and a working lining using the same. The mixed proportion of CaO-containing raw materials, Al2O3-containing raw materials and ZrO2-containing raw materials is adjusted according to the chemical composition of the final product, and the mixed proportion is such that the mass ratio of the chemical composition Al2O3:CaO:ZrO2 is 45.5-95.5%:2.0-8.4%:0-50% according to mass parts. The materials are put into a high-temperature furnace and a mold for hot-pressing sintering, and the hot-pressing is performed while the temperature is rising, with the highest temperature being 1550-1800 DEG C and the hot-pressing strength being 0.5-30 MPa. According to the hot-pressing sintering process in the proportioning mode, the high-purity dense calcium hexaluminate-based refractory material is obtained without adding a sintering agent. The refractory material has excellent resistance to molten steel erosion and thermal shock stability, and can be widely used in the metallurgy, building material and petrochemical industries. The preparation method is scientific and reasonable, the product has high purity, and the refractory material product can increase the equipment operation cycle, reduce the production cost, and achieve the energy-saving and emission-reducing effect.

Description

Technical Field

[0001] This invention belongs to the field of refractory materials technology, and particularly relates to a high-purity, dense calcium hexaaluminate-based refractory material, its preparation method, and a kiln lining using the refractory material. Background Technology

[0002] Currently, high-performance mold steel, silicon wafer cutting wire steel, automotive transmission steel, and some common steel grades generally suffer from insufficient precise control of non-metallic inclusions, affecting the stability of steel performance. Refractory materials, which are in almost constant contact with molten steel during steelmaking, are one of the main sources of non-metallic inclusions in steel. In the steelmaking process, the refractory lining of the ladle has a significant impact on the quality of molten steel.

[0003] Currently, there are two main types of refractory materials for ladle working linings: one is alumina-magnesia-carbon bricks, and the other is corundum-spinel system castables or corundum-MgO-SiO2 system castables (including precast parts); these technologies have not undergone major improvements or changes for at least 20 years.

[0004] Alumina-magnesia-carbon bricks are mainly made from bauxite, corundum, magnesium oxide, graphite, etc. They have several drawbacks in steelmaking: firstly, they introduce carbon into the steel; secondly, the high oxygen potential of the SiO2 component leads to the formation of deoxidized inclusions in the molten steel. While corundum-spinel castables do not contain carbon and do not introduce carbon into the steel, the excellent corrosion resistance of corundum means that small corundum particles may not be completely corroded during smelting and may enter the molten steel as fine particles, forming alumina inclusions, spinel inclusions, or CaO-MgO-Al2O3 inclusions with magnesium oxide, thus affecting the stability of steel properties. Furthermore, corundum-MgO-SiO2 system castables or precast components, in addition to having the shortcomings of corundum-spinel castables, may also lead to SiO2 oxygenation during the smelting of ultra-low oxygen steel. Therefore, it is extremely important to develop refractory materials suitable for use in the metallurgical industry that do not react with slag to generate non-metallic inclusions or increase endogenous inclusions, and that can clean molten steel. This has been explored both domestically and internationally.

[0005] Calcium hexaaluminate (CaO·6Al2O3, abbreviated CA6) has the chemical composition of CaO and Al2O3, and a low oxygen potential, which meets the chemical stability requirements under deoxidation conditions in steelmaking. It also has a melting point of 1875℃ and a theoretical density of 3.79 g / cm³. 3 It has a low thermal conductivity and good refractory performance. To some extent, calcium hexaaluminate, as a refractory material, has a certain effect on purifying molten steel, which can significantly reduce the contamination of molten steel by traditional refractory materials.

[0006] However, calcium hexaaluminate has a magnetoplumble structure and exhibits anisotropy during crystal growth and development, resulting in a lamellar structure. Therefore, calcium hexaaluminate has poor sinterability, which is why it is currently difficult to prepare crystals with a bulk density greater than 3.0 g / cm³. 3 The main reason for the high density of calcium hexaaluminate is that the volume expansion effect accompanying the reactions between the components during its preparation also affects the sintering and densification process. The densification of calcium hexaaluminate is a crucial performance characteristic for its application as a working lining in the steel metallurgy industry.

[0007] Currently, to achieve densification of calcium hexaaluminate, most existing technologies employ the addition of additives such as SiO2 and TiO2 to promote sintering, thereby creating a liquid phase at high temperatures and promoting its densification sintering. For example, Chen Zhaoyou and Chai Junlan, in their article "Calcium Hexaaluminate Materials and Their Application in Aluminum Industrial Furnaces" (Refractory Materials, 2011, 45(2): 122-125), discuss the physicochemical properties of Bonate (a trade name for calcium hexaaluminate), in which the chemical composition SiO2 is 0.9%. For example, "A method for preparing dense calcium hexaaluminate refractory clinker" (CN110171980A) and "A method for preparing dense calcium hexaaluminate refractory clinker" (CN105585314A) use TiO2 and MnO as sintering agents, respectively. However, this preparation method cannot achieve densification by controlling the stacking of mirror-layer atoms. It only relies on the liquid phase to bring the grains closer together. Although this can improve the density of calcium hexaaluminate, the bulk density of calcium hexaaluminate is difficult to exceed 3.15 g / cm³. 3 Moreover, the method of adding sintering agents to improve sintering activity always comes at the cost of sacrificing the high-temperature performance of calcium hexaaluminate, which will significantly reduce the high-temperature performance of the material (although the amount added is less than 1%, it generates several times the amount of liquid phase at high temperatures). At the same time, the introduction of high oxygen potential impurities is not conducive to the control of inclusions in steel.

[0008] Refractory materials based on calcium hexaaluminate raw materials with added sintering aids suffer from the aforementioned shortcomings of the raw material, as well as problems such as high apparent porosity (typically 15-23%, leading to uneven microstructure) and poor corrosion resistance. Calcium hexaaluminate refractories with high porosity and high amounts of added sintering aids will experience rapid deterioration, resulting in significant refractory material entering the molten steel. The mixture of refractory materials corroded and washed away by molten steel and slag, while having a certain purifying effect on molten steel in some cases, will lead to large non-metallic inclusions if not properly controlled, severely impacting steel quality. Similarly, alumina-magnesia-carbon bricks and corundum-spinel castables, used for many years in refining ladle working linings, also suffer from high apparent porosity (typically 13-20%), rapid deterioration, and significant refractory material entering the molten slag and steel. However, given the current research and development concepts and existing preparation methods for refractory materials, it is already very difficult to reduce porosity (including apparent porosity and some closed porosity), but apparent porosity has a very significant adverse effect on material life and corrosion resistance.

[0009] Therefore, given the advantages of calcium hexaaluminate in terms of chemical composition, it is crucial to significantly improve the density and uniformity of the material's microstructure, reduce the amount of refractory material entering the molten steel due to corrosion and erosion by molten steel and slag, and improve the purity and high-temperature performance of the material while minimizing the introduction of high-oxygen potential sintering aids to reduce contamination of the molten steel. This is also very important for the production of high-quality steel and the reduction of inclusions in steel, and is also critical for aluminum molten steel containers.

[0010] Based on the above analysis, the problems and defects of the existing technology are as follows: (1) The existing technology, whether it is the aluminum-magnesium-carbon or the corundum-spinel series castables currently in use, has defects such as uneven microstructure, high apparent porosity (the oxidation of carbon components also leads to high porosity), and rapid damage. These defects may affect inclusions in steel, but cannot significantly reduce porosity or improve the uniformity of microstructure; (2) The existing production technology of calcium hexaaluminate basically adds TiO2, MnO, SiO2, etc. as sintering agents, which is at the expense of the high-temperature performance of the material. This not only significantly reduces the high-temperature performance of the material, but also introduces additives with high oxygen potential, which increases harmful components in calcium hexaaluminate, which originally has a very low oxygen potential and does not pollute molten steel; (3) The bulk density of calcium hexaaluminate raw materials in the existing technology can mostly not reach 3.15 g / cm³. 3 The bulk density of pure calcium hexaaluminate refractory material (CA6 phase ≥ 90%) based on this raw material is only 2.50–2.85 g / cm³. 3The apparent porosity can even reach 22-25%, and the microstructure is very uneven, so the rate of damage is predictable. Moreover, due to the difficulty of sintering, high-purity, dense calcium hexaaluminate raw materials have not yet been produced on a large scale, nor have dense calcium hexaaluminate refractory materials been produced on a large scale.

[0011] The difficulties in solving the above problems and defects are as follows: (1) Existing industrial application materials such as aluminum-magnesium-carbon and corundum-spinel materials cannot continue to be densified, improve the microstructure and reduce porosity due to the characteristics and structural limitations of the raw materials. Their resistance to molten steel and slag erosion has reached a bottleneck, and pollution of molten steel is unavoidable; (2) Due to its unique lamellar structure and anisotropic crystallization characteristics, it is difficult to achieve structural densification by simply adding sintering agents, forming more liquid phases, and using the dissolution of the liquid phase and surface tension, and it is also difficult to reach 3.15 g / cm³. 3 The above bulk density; (3) The addition of sintering agent makes it difficult to improve the purity of calcium hexaaluminate, which also seriously affects the application performance of calcium hexaaluminate refractory materials. Without the addition of sintering aid, the bulk density of calcium hexaaluminate is mostly 2.2 to 2.7 g / cm³. 3 There is no possibility of its industrial application in the metallurgical field.

[0012] The significance of solving the above problems and defects is that, without adding sintering agents, a high-purity, uniform, and relatively dense calcium hexaaluminate refractory material can be obtained. This can fully utilize the advantages of calcium hexaaluminate refractory material in terms of chemical composition, while giving it excellent resistance to molten steel corrosion, reducing pollution to molten steel, purifying the quality of steel, and resulting in significant economic and socio-economic benefits. Summary of the Invention

[0013] To address the problems existing in the prior art, this application provides a high-purity, dense calcium hexaaluminate-based refractory material, its preparation method, and a kiln lining using the high-purity, dense calcium hexaaluminate-based refractory material.

[0014] The high-purity, dense calcium hexaaluminate refractory material of this application can be prepared without the addition of any sintering agent during the preparation process. It adopts a hot-pressing sintering process to produce calcium hexaaluminate refractory material products with high chemical purity, dense structure, good uniformity of organization and high thermal shock stability.

[0015] The specific technical solution of this application is as follows:

[0016] 1. A high-purity, dense calcium hexaaluminate-based refractory material, characterized in that the phase of the refractory material includes CA6 and one or two selected from corundum and zirconium oxide.

[0017] 2. The refractory material according to claim 1, characterized in that, based on the percentage content of the total mass of the refractory material, the total content of CA6 and one or more phases selected from corundum and zirconium oxide is ≥90%;

[0018] Preferably, the CA6 phase content is 30-100%, more preferably 35-100%.

[0019] The content of corundum phase is 0-50%, preferably 0-35%;

[0020] The zirconium oxide phase content is 0-50%, preferably 0-35%.

[0021] 3. The refractory material according to claim 1 or 2, characterized in that, based on the percentage of the total mass of the refractory material, the content of the sintering-promoting component in the refractory material is ≤1.5%, preferably ≤1.0%.

[0022] 4. The refractory material according to any one of claims 1-3, characterized in that the chemical composition of the refractory material comprises Al2O3, CaO and ZrO2, wherein, based on the percentage content of the total mass of the refractory material, the Al2O3 is 45.8-95.8%, preferably 59.54-94.54%; the CaO is 2.52-8.40%, preferably 2.94-8.40%; and the ZrO2 is 0-50%, preferably 0-35%.

[0023] 5. The refractory material according to any one of claims 1-4, characterized in that the bulk density of the refractory material is 2.90-3.65 g / cm³. 3 The preferred value is 2.90-3.45 g / cm³. 3 Further preferred values ​​are 2.95-3.30 g / cm³. 3 .

[0024] 6. The refractory material according to any one of claims 1-5, characterized in that the refractory material is prepared by a method comprising the following steps:

[0025] The relevant fine powders are mixed to obtain a mixture, and the mixture is hot-pressed and sintered to obtain the refractory material.

[0026] 7. The refractory material according to claim 6, wherein the mass ratio of fine powder in the mixture is 100%.

[0027] 8. The refractory material according to any one of claims 6-7, characterized in that the fine powder comprises Al2O3-CaO fine powder and ZrO2-containing fine powder, preferably, based on the percentage content of the total mass of the fine powder, the Al2O3-CaO fine powder is 50-100%, and the ZrO2-containing fine powder is 0-50%.

[0028] Preferably, the Al2O3-CaO fine powder is selected from CA6 fine powder containing CaO fine powder, or a mixture of fine powder containing CaO and fine powder containing Al2O3.

[0029] Preferably, the Al2O3-containing fine powder is selected from one or more of the following: active α-Al2O3 powder, γ-Al2O3 powder, ρ-Al2O3 powder, aluminum hydroxide fine powder, industrial alumina fine powder, white corundum fine powder, sub-white corundum fine powder, sintered corundum fine powder, and tabular corundum fine powder.

[0030] Preferably, the CaO-containing fine powder is selected from one or more of quicklime fine powder, limestone fine powder, calcium hydroxide fine powder, CA fine powder, CA2 fine powder, C12A7 fine powder, and CA6 fine powder.

[0031] Preferably, the ZrO2-containing fine powder is selected from one or more of monoclinic zirconium oxide fine powder, tetragonal zirconium oxide fine powder, desilicationized zirconium oxide fine powder, and fused zirconium oxide fine powder.

[0032] 9. The refractory material according to any one of claims 6-8, characterized in that the particle size of the fine powder is ≤0.088mm.

[0033] 10. The refractory material according to any one of claims 6-9, characterized in that,

[0034] The hot pressing sintering involves placing the mixture into a mold in a high-temperature device for hot pressing sintering; or...

[0035] The mixture is pre-sintered at a low temperature and then placed in a mold of a high-temperature device for hot pressing and sintering; or...

[0036] Some of the raw materials are mixed, pre-sintered at low temperature, crushed and pulverized, and then other remaining raw materials are added. After mixing evenly, a mixture is obtained. The mixture is then placed in a mold of a high-temperature device for hot pressing and sintering.

[0037] 11. The refractory material according to claim 10, wherein the hot pressing sintering temperature is 1550-1800℃; preferably, the hot pressing strength is 0.5-30 MPa.

[0038] 12. A method for preparing a high-purity, dense calcium hexaaluminate-based refractory material, comprising the following steps:

[0039] The relevant fine powders are mixed to obtain a mixture, and the mixture is hot-pressed and sintered to obtain the refractory material.

[0040] 13. The preparation method according to claim 12, wherein the mass ratio of fine powder in the mixture is 100%.

[0041] 14. The preparation method according to claims 12-13, characterized in that the fine powder includes Al2O3-CaO fine powder and ZrO2-containing fine powder, preferably, based on the percentage content of the total mass of the fine powder, the Al2O3-CaO fine powder is 50-100%, and the ZrO2-containing fine powder is 0-50%.

[0042] Preferably, the Al2O3-CaO fine powder is selected from CA6 fine powder containing CaO fine powder, or from a mixture of fine powder containing CaO and fine powder containing Al2O3.

[0043] Preferably, the fine powder containing Al2O3 is selected from one or more of the following: active α-Al2O3 powder, γ-Al2O3 powder, ρ-Al2O3 powder, aluminum hydroxide fine powder, industrial alumina fine powder, white corundum fine powder, sub-white corundum fine powder, sintered corundum fine powder, and tabular corundum fine powder.

[0044] Preferably, the CaO-containing fine powder is selected from one or more of quicklime fine powder, limestone fine powder, calcium hydroxide fine powder, CA fine powder, CA2 fine powder, C12A7 fine powder, and CA6 fine powder.

[0045] Preferably, the ZrO2-containing fine powder is selected from one or more of monoclinic zirconium oxide fine powder, tetragonal zirconium oxide fine powder, desilicationized zirconium oxide fine powder, and fused zirconium oxide fine powder.

[0046] 15. The preparation method according to any one of claims 12-14, wherein the particle size of the fine powder is ≤0.088 mm.

[0047] 16. The preparation method according to any one of claims 12-15, characterized in that the hot pressing sintering is performed by placing the mixture into a mold of a high-temperature device for hot pressing sintering; or,

[0048] The mixture is pre-sintered at a low temperature and then placed in a mold of a high-temperature device for hot pressing and sintering; or...

[0049] Some of the raw materials are mixed, pre-sintered at low temperature, crushed and pulverized, and then other remaining raw materials are added. After mixing evenly, a mixture is obtained. The mixture is then placed in a mold of a high-temperature device for hot pressing and sintering.

[0050] 17. The preparation method according to claim 16, wherein the hot pressing sintering temperature is 1550-1800℃; preferably, the hot pressing strength is 0.5-30MPa.

[0051] 18. A working lining for a steel ladle used in steelmaking, characterized in that it comprises the refractory material according to any one of claims 1-11 or the refractory material prepared by the preparation method according to any one of claims 12-17.

[0052] 19. A working lining for an aluminum molten metal smelting and conveying ladle, characterized in that it comprises the refractory material according to any one of claims 1-11 or the refractory material prepared by the preparation method according to any one of claims 12-17.

[0053] 20. A refractory lining for an industrial kiln, characterized in that it comprises the refractory material according to any one of claims 1-11 or the refractory material prepared by the preparation method according to any one of claims 12-17.

[0054] Effects of the invention

[0055] Compared with existing technologies, the advantages and positive effects of this application are as follows:

[0056] (1) The refractory material provided by this invention has CA6, Al2O3, and ZrO2 as its main phases, and the total content of CA6+Al2O3+ZrO2 is ≥90%. It has low content of impurities such as SiO2 and TiO2, and its purity is significantly higher than that of other existing calcium hexaaluminate refractory materials. It has a much better effect on inclusions in high-end steel grades and its sensitivity to some atmospheres is also greatly reduced, increasing its versatility in some application fields. Its bulk density is 2.90~3.65g / cm³. 3 This material is significantly superior to existing calcium hexaaluminate refractory materials of the same grade, exhibiting greatly enhanced resistance to corrosion from molten steel and slag. This not only significantly extends its service life but also drastically reduces the amount of refractory material entering the molten steel, greatly contributing to the purification of the steel. It can be widely used in the metallurgical industry, as well as in the construction of rotary kiln linings such as transition zones in cement kilns and the building blocks of some industrial kilns. This can increase equipment operating cycles, reduce production costs, and achieve energy conservation and emission reduction.

[0057] (2) The preparation method provided in this application uses simple and abundant raw materials. Without adding sintering agent, the calcium hexaaluminate refractory material can be well sintered by means of hot pressing sintering process. This method is scientific and reasonable and has significant economic benefits.

[0058] (3) The preparation method provided in this application produces a dense and high-purity calcium hexaaluminate-based material with a main phase content of CA6 + corundum + zirconium oxide ≥90% and a bulk density as high as 2.90~3.65g / cm³. 3 This allows for the full utilization of the excellent properties of calcium hexaaluminate refractory materials.

[0059] (4) The high-purity dense calcium hexaaluminate refractory material of this application can be widely used in steelmaking production lines, such as ladle working linings for ladle refining. It has good corrosion resistance and its effect on inclusions in steel is significantly better than that of existing corundum, spinel and many other refractory materials. It greatly reduces the impact of refractory materials on molten steel during the smelting of high-end special steel, improves the overall quality of high-end special steel in my country's metallurgical industry, increases equipment operating cycle, improves economic benefits and has significant social benefits.

[0060] (5) The high-purity dense calcium hexaaluminate refractory material of this application can also be widely used in the refractory lining of rotary kilns, such as the transition zone of cement rotary kilns. It has good erosion resistance and low thermal conductivity, and its performance is significantly better than many existing refractory materials such as silicon-mullite bricks and magnesium-aluminate spinel bricks. It can increase the equipment operating cycle, reduce heat loss, and improve economic benefits.

[0061] (6) The high-purity dense calcium hexaaluminate refractory material of this application can also be widely used in the construction of industrial kilns under conditions of high temperature, reducing atmosphere and alkaline atmosphere erosion, such as petrochemical cracking furnaces. It has good erosion resistance and low thermal conductivity, and its performance is significantly better than many existing corundum bricks and other refractory materials. It can increase the equipment operation cycle, reduce heat loss and improve economic benefits. Attached Figure Description

[0062] To more clearly illustrate the technical solution of this application, the accompanying drawings used in this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0063] Figure 1 This is a drawing of a fired product made from the high-purity, dense calcium hexaaluminate refractory material of this application.

[0064] Figure 2 The damage condition of sample 3, cast according to Example 1 of CN107500747 A, after the experiment.

[0065] Figure 3 This is a damage effect diagram of the high-purity, dense calcium hexaaluminate refractory material sample after testing. Detailed Implementation

[0066] The present application will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the present application can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present application and to fully convey the scope of the present application to those skilled in the art.

[0067] It should be noted that certain terms are used in the specification and claims to refer to specific components. Those skilled in the art will understand that different terms may be used to refer to the same component. This specification and claims do not distinguish components based on differences in terminology, but rather on differences in function. The terms "comprising" or "including" used throughout the specification and claims are open-ended and should be interpreted as "comprising but not limited to." The following descriptions in the specification are preferred embodiments for carrying out this application; however, these descriptions are for the purpose of understanding the general principles of the specification and are not intended to limit the scope of this application. The scope of protection of this application shall be determined by the appended claims.

[0068] This application provides a high-purity, dense calcium hexaaluminate-based refractory material, characterized in that the phases of the refractory material include CA6 and one or two selected from corundum and ZrO2.

[0069] In this application, "phase" refers to a phase in a substance that possesses specific physicochemical properties.

[0070] In one specific embodiment, the refractory material comprises CA6 and corundum; in another specific embodiment, the refractory material comprises CA6 and ZrO2; in yet another specific embodiment, the refractory material comprises CA6, corundum, and ZrO2.

[0071] In this application, "CA6" is an abbreviation for calcium hexaaluminate, with the structural formula CaO·6Al2O, a melting point of 1875℃, and a theoretical density of 3.79 g / cm³. 3 The characteristics of this material are: good stability under low oxygen partial pressure; it has a layered stacked structure with anisotropic crystal growth, a slow growth rate along the C-axis, and is difficult to sinter; when it reacts with molten slag, it generates CA2 (abbreviation of CaO·2Al2O3) and CA (abbreviation of CaO·Al2O3), etc. At the steelmaking temperature, CA2 is solid and CA is liquid, so the solid-liquid mixed phase blocks the pores and inhibits molten slag penetration.

[0072] The phase composition of the refractory material is determined by XRD, for example, by grinding the material to below 325 mesh and then scanning it using an X-ray diffractometer. By analyzing the diffraction data and matching it with a standard PDF card, the relevant phases are obtained, and then the content of the relevant phases is obtained by fitting the diffraction data.

[0073] Regarding the ZrO2 phase, because H f O2 and ZrO2 coexist, are difficult to separate, and have similar crystal forms, therefore,

[0074] ① In this application, the ZrO2 phase contains H f The content of O2 phase;

[0075] ② Due to differences in temperature, process, etc., and the fact that the composition distribution is not very uniform (absolute uniformity is impossible), the final product may contain ZrO2-CaO solid solution, CaO·ZrO2, and other phases. In the case of ZrO2-CaO solid solution, CaO·ZrO2, etc., the ZrO2 content is first corrected based on the XRF results, and then the corrected ZrO2 content is converted into zirconia phase. At the same time, CaO that is dissolved or combined in the form of CaO·ZrO2 is converted into CA6. Then, all these phases are normalized to 100%, and finally the percentage content of each phase is calculated.

[0076] In one specific embodiment, the refractory material of this application, based on the percentage of the total mass of the refractory material, contains ≥90% of CA6 and one or more of the two or more phases selected from corundum and ZrO2; for example, based on the percentage of the total mass of the refractory material, the total phase content in the refractory material can be 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 100%, etc.

[0077] In a preferred embodiment, the CA6 phase content in the refractory material of this application is 30-100% by weight of the total mass of the refractory material, preferably 35-100%.

[0078] The corundum phase content is 0-50%, preferably 0-35%;

[0079] The ZrO2 phase content is 0-50%, preferably 0-35%.

[0080] In one specific embodiment, the refractory material of this application, based on the percentage of the total mass of the refractory material, has a sintering-promoting component content of ≤1.5%, preferably ≤1.0%.

[0081] For example, based on the percentage of the total mass of the refractory material, the content of the sintering-promoting component in the refractory material can be 1.5%, 1.4%, 1.3%, 1.2%, 1.1%, 1.0%, 0.9%, 0.8%, 0.7%, 0.6%, 0.5%, 0.4%, 0.3%, 0.2%, 0.1%, 0, or any range thereof.

[0082] The sintering-promoting components are SiO2, TiO2, Fe2O3, and R2O. Due to the low content of the sintering-promoting components, the chemical purity of the material system is high. Among them, R2O refers to an oxide of an alkali metal.

[0083] In one specific embodiment, the refractory material of this application has a chemical composition comprising Al2O3, CaO, and ZrO2; the chemical composition of the refractory material, calculated as a percentage of the total mass of the refractory material, includes:

[0084] The Al2O3 content is 45.8-95.8%, preferably 59.54-94.54%. For example, the Al2O3 can be 45.8%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 95.8% or any range between these values, representing 45.8% of the total mass of the refractory material.

[0085] The CaO content is 2.52-8.40%, preferably 2.94-8.40%. For example, the CaO content can be 2.52%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.4% or any range thereof, which is the total mass of the refractory material.

[0086] The ZrO2 content is 0-50%, preferably 0-35%. For example, the ZrO2 content can be 0%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, or any range thereof.

[0087] The chemical composition of the refractory material was determined by XRF fluorescence analysis in accordance with GB / T21114-2007.

[0088] Regarding the content of ZrO2 in its chemical composition, due to H f O2 and ZrO2 coexist and are difficult to separate, so in the XRF of this patent, the HfO2 content is calculated in the ZrO2 content.

[0089] In one specific embodiment, the bulk density of the refractory material of this application is 2.90-3.65 g / cm³. 3 The preferred value is 2.90-3.45 g / cm³. 3 Further preferred values ​​are 2.95-3.30 g / cm³.3 .

[0090] For example, the bulk density of the refractory material can be 2.90 g / cm³. 3 2.91 g / cm 3 2.92g / cm 3 2.93g / cm 3 2.94 g / cm 3 2.95g / cm 3 2.96g / cm 3 2.97g / cm 3 2.98g / cm 3 2.99g / cm 3 3.00g / cm 3 3.05g / cm 3 3.10 g / cm 3 3.15g / cm 3 3.20g / cm 3 3.25g / cm 3 3.30g / cm 3 3.35g / cm 3 3.40 g / cm 3 3.45g / cm 3 3.50g / cm 3 3.55g / cm 3 3.60g / cm 3 3.65g / cm 3 or any range thereof.

[0091] The bulk density of the refractory material was determined according to GB / T2997-2000.

[0092] In one specific embodiment, the refractory material of this application is prepared by a method comprising the following steps:

[0093] The relevant fine powders are mixed to obtain a mixture, and the mixture is hot-pressed and sintered to obtain the refractory material.

[0094] The fine powder refers to the portion that passes through a 180-mesh square hole sieve (Xinxiang Zhongtuo Machinery Equipment Co., Ltd.), i.e., the portion below the 180-mesh square hole sieve, with a particle size ≤180 mesh, i.e., a particle size ≤0.088mm.

[0095] In one specific embodiment, the mass ratio of fine powder in the mixture is 100%.

[0096] In one specific embodiment, the fine powder includes Al2O3-CaO-based fine powder and ZrO2-containing fine powder. In a preferred specific embodiment, based on the percentage of the total mass of the fine powder, the Al2O3-CaO-based fine powder is 50-100%, for example, it can be 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 100%, or any range thereof; the ZrO2-containing fine powder is 0-50%, for example, it can be 0%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, or any range thereof.

[0097] In a preferred embodiment, the Al2O3-CaO fine powder described in this application is selected from CA6 fine powder containing CaO fine powder, or a mixture of fine powder containing CaO and fine powder containing Al2O3.

[0098] In this application, "fine powder containing CaO" refers to fine powder whose chemical composition includes CaO, or fine powder containing CaO and Al2O3.

[0099] In this application, "fine powder containing Al2O3" refers to alumina-based fine powder whose main chemical component is Al2O3.

[0100] In a preferred embodiment, the Al2O3-containing fine powder is selected from one or more of the following: active α-Al2O3 powder, γ-Al2O3 powder, ρ-Al2O3 powder, aluminum hydroxide fine powder, industrial alumina fine powder, white corundum fine powder, sub-white corundum fine powder, sintered corundum fine powder, and tabular corundum fine powder.

[0101] The “active α-Al2O3 fine powder” in this application refers to alumina powder with high activity, mainly composed of α-Al2O3, obtained by processing industrial alumina or aluminum hydroxide as raw materials at 1250-1450℃.

[0102] The “γ-Al2O3 fine powder” in this application refers to alumina powder with a high specific surface area and good adsorption properties obtained by treating aluminum hydroxide as raw material at 140-150℃.

[0103] The “ρ-Al2O3 fine powder” in this application refers to alumina powder with certain hydration bonding properties obtained by rapidly processing aluminum hydroxide at high temperatures of 600–900℃.

[0104] The "industrial alumina fine powder" in this application is mainly composed of α-Al2O3 mineral, which is a powder prepared by calcining aluminum hydroxide at 900-1250℃.

[0105] The "white corundum fine powder" in this application refers to an alumina raw material with an aluminum oxide (Al2O3) content of more than 97.5% prepared by electro-melting of industrial alumina, and containing a small amount of iron oxide, silicon oxide and other components, and is white in color.

[0106] The "sub-white fused alumina fine powder" in this application is produced from bauxite. Its chemical composition and physical properties are similar to those of white fused alumina. It has the hardness of white fused alumina and the toughness of brown fused alumina, making it an ideal high-grade refractory and abrasive material.

[0107] The “sintered corundum fine powder” in this application refers to refractory clinker made by grinding alumina into pellets or blanks and sintering them at a high temperature of 1750-1900℃. It has high bulk density, low porosity, and excellent thermal shock resistance and slag erosion resistance at high temperatures.

[0108] The "plate-shaped corundum powder" in this application has a coarse-grained, well-developed α-Al2O3 crystal structure with an Al2O3 content of over 97.0%, a plate-shaped crystal structure, small pores, and a large number of closed pores.

[0109] In a preferred embodiment, the CaO-containing fine powder is selected from one or more of quicklime fine powder, limestone fine powder, calcium hydroxide fine powder, CA fine powder, CA2 fine powder, C12A7 fine powder, and CA6 fine powder.

[0110] The "fine quicklime powder" in this application is mainly composed of calcium oxide. It is usually produced by calcining natural rocks, whose main component is calcium carbonate, at high temperature, which decomposes them into carbon dioxide and calcium oxide (chemical formula: CaO, i.e., quicklime, also known as marble).

[0111] In this application, "CA fine powder" refers to fine powder whose main component is CaO·Al2O3.

[0112] In this application, "CA2 fine powder" refers to fine powder whose main component is CaO·2Al2O3.

[0113] In this application, "C12A7 fine powder" refers to fine powder whose main component is 12CaO·7Al2O3.

[0114] In this application, "CA6 fine powder" refers to fine powder whose main component is CaO·6Al2O.

[0115] In a preferred embodiment, the ZrO2-containing fine powder is selected from one or more of monoclinic zirconium oxide fine powder, tetragonal zirconium oxide fine powder, desilicationized zirconium oxide fine powder, and fused zirconium oxide fine powder.

[0116] In this application, "monoclinic zirconia fine powder" refers to zirconia fine powder with a monoclinic crystal system.

[0117] In this application, "tetragonal zirconia fine powder" indicates that the crystal form is tetragonal zirconia fine powder.

[0118] In this application, "desiliconized zircon fine powder" refers to zircon oxide fine powder obtained by desiliconizing zircon sand.

[0119] In this application, "electrofused zirconia fine powder" refers to zirconia fine powder prepared by electric arc melting of zirconia powder.

[0120] In one specific embodiment, the particle size of the fine powder in the mixture is ≤0.088mm.

[0121] In one specific embodiment, the refractory material of this application can be prepared by three hot pressing sintering methods.

[0122] Hot pressing sintering refers to a method of sintering and preparing materials under the combined action of pressure and temperature.

[0123] In one specific implementation method (method one), the hot pressing sintering method involves placing the mixture into a mold of a high-temperature device for hot pressing sintering.

[0124] The above-mentioned method of hot-pressing sintering the mixture in a mold of a high-temperature device refers to: mixing the fine powder of raw materials according to a preset mass ratio and then placing it in a mold of a high-temperature device to raise the temperature; applying pressure when the temperature reaches the maximum temperature to achieve sintering, or continuously maintaining the temperature and pressure for a certain time to complete the hot-pressing sintering of the material; or placing the mixture in a mold of a high-temperature device and raising the temperature to a certain temperature while applying pressure, then gradually raising the temperature and simultaneously increasing the applied pressure until the temperature reaches the maximum temperature and the pressure reaches the maximum value, or continuously maintaining the temperature and pressure for a certain time to complete the hot-pressing sintering of the material; or placing the mixture in a mold of a high-temperature device and gradually increasing the pressure applied to the mixture while raising the temperature until the temperature reaches the maximum temperature and the pressure reaches the maximum value, or continuously maintaining the temperature and pressure for a certain time to complete the hot-pressing sintering of the material.

[0125] In another specific implementation (method two), the hot pressing sintering method involves first pre-sintering the mixture at a low temperature (i.e., pre-synthesizing it completely) and then placing it into a mold of a high-temperature device for hot pressing sintering.

[0126] The above-mentioned method of pre-synthesizing all the mixtures before hot pressing and sintering refers to mixing all the raw material fine powders according to the preset treatment ratio, pressing them into shape at room temperature, lightly sintering them at a temperature of 1400-1600℃ to obtain the pre-synthesized material, and then placing the pre-synthesized material into the mold of the high-temperature device for hot pressing and sintering according to the hot pressing and sintering method of Method 1.

[0127] In another specific implementation method (method three), the hot pressing sintering method involves first mixing some raw materials, pre-sintering at low temperature (i.e., partial pre-synthesis), crushing and pulverizing, and then adding other remaining raw materials. After mixing evenly, a mixture is obtained, and then the mixture is placed into a mold of a high-temperature device for hot pressing sintering.

[0128] The above-mentioned method of pre-synthesizing a portion of the mixture and then hot-pressing and sintering it with the remaining raw materials refers to first mixing a portion of the fine powder of the raw materials, pressing it into shape at room temperature, and then lightly sintering it at a temperature of 1400-1600℃ to obtain a pre-synthesized material. After crushing the pre-synthesized material, the remaining fine powder of the raw materials is added to the preset mass ratio and mixed evenly to obtain a mixture. Then, the mixture is placed in the mold of a high-temperature device and hot-pressed and sintered according to the hot-pressing and sintering method of Method 1.

[0129] In one specific embodiment, when the refractory material of this application is prepared by hot pressing sintering, the high-temperature device is a high-temperature device commonly used by those skilled in the art, such as a high-temperature furnace; or a kiln that integrates high temperature and hot pressing, such as a hot press furnace.

[0130] In one specific embodiment, when the refractory material of this application is prepared by hot pressing sintering, the hot pressing sintering temperature is 1550-1800℃, for example, it can be 1550℃, 1600℃, 1650℃, 1700℃, 1750℃, 1800℃ or any range therebetween, and the hot pressing strength is 0.5-30MPa, for example, it can be 0.5MPa, 1MPa, 1.5MPa, 2MPa, 2.5MPa, 3MPa, 3.5MPa, 4MPa, 4. 5MPa, 5MPa, 5.5MPa, 6MPa, 6.5MPa, 7MPa, 7.5MPa, 8MPa, 8.5MPa, 9MPa, 9.5MPa, 10MPa, 10.5MPa, 11MPa, 11.5MPa, 12MPa, 12.5MPa, 13MPa, 13.5MPa, 14MPa, 14.5MPa, 15MPa, 20MPa, 25MPa, 30MPa, or any range thereof.

[0131] The hot-pressing strength is the pressure value applied to a unit area of ​​the sample.

[0132] This application also provides a method for preparing a high-purity, dense calcium hexaaluminate-based refractory material, which includes the following steps:

[0133] The relevant fine powders are mixed to obtain a mixture, and the mixture is hot-pressed and sintered to obtain the refractory material.

[0134] In one specific embodiment, in the preparation method of the high-purity dense calcium hexaaluminate refractory material of this application, the mass ratio of fine powder in the mixture is 100%.

[0135] Specifically, the fine powder refers to the portion that passes through an 180-mesh square-hole sieve, that is, the portion located below the 180-mesh square-hole sieve, with a particle size ≤0.088mm.

[0136] In one specific embodiment, in the preparation method of the high-purity dense calcium hexaaluminate refractory material of this application, the fine powder includes Al2O3-CaO fine powder and ZrO2-containing fine powder. Preferably, based on the percentage content of the total mass of the fine powder, the Al2O3-CaO fine powder is 50-100%, and the ZrO2-containing fine powder is 0-50%.

[0137] In a preferred embodiment, the Al2O3-CaO fine powder is selected from CA6 fine powder containing CaO fine powder, or from a mixture of fine powder containing CaO and fine powder containing Al2O3.

[0138] In a preferred embodiment, the Al2O3-containing fine powder is selected from one or more of the following: active α-Al2O3 powder, γ-Al2O3 powder, ρ-Al2O3 powder, aluminum hydroxide fine powder, industrial alumina fine powder, white corundum fine powder, sub-white corundum fine powder, sintered corundum fine powder, and tabular corundum fine powder.

[0139] In a preferred embodiment, the CaO-containing fine powder is selected from one or more of the following: quicklime fine powder, limestone fine powder, calcium hydroxide fine powder, CA (CaO·Al2O3) fine powder, CA2 (CaO·2Al2O3) fine powder, C12A7 (12CaO·7Al2O3) fine powder, and CA6 (CaO·6Al2O) fine powder.

[0140] In a preferred embodiment, the ZrO2-containing fine powder is selected from one or more of monoclinic zirconium oxide fine powder, tetragonal zirconium oxide fine powder, desilicationized zirconium oxide fine powder, and fused zirconium oxide fine powder.

[0141] In one specific embodiment, the preparation method of the high-purity dense calcium hexaaluminate-based refractory material of this application can employ three hot-pressing sintering methods, including:

[0142] The mixture is placed in a mold of a high-temperature device for hot pressing and sintering; or...

[0143] The mixture is pre-sintered at a low temperature and then placed in a mold of a high-temperature device for hot pressing and sintering; or...

[0144] Some of the raw materials are mixed, pre-sintered at low temperature, crushed and pulverized, and then other remaining raw materials are added. After mixing evenly, a mixture is obtained. The mixture is then placed in a mold of a high-temperature device for hot pressing and sintering.

[0145] In one specific embodiment, the hot pressing sintering temperature is 1550-1800℃; preferably, the hot pressing strength is 0.5-30MPa.

[0146] In a preferred embodiment, a high-purity, dense calcium hexaaluminate-based refractory material can be prepared by the following methods and steps:

[0147] (1) Mix the raw materials containing CaO, Al2O3, and ZrO2 evenly according to the mixing ratio, wherein the mixing ratio is such that the chemical composition Al2O3:CaO:ZrO2 is 45.8-95.8%:2.52-8.4%:0-50% by mass.

[0148] (2) The mixed raw materials are placed in the mold of the high-temperature device for hot pressing and sintering, with a maximum temperature of 1550-1800℃ and a hot pressing strength of 0.5-30MPa.

[0149] In another preferred embodiment, a high-purity, dense calcium hexaaluminate-based refractory material can be prepared by the following methods and steps:

[0150] (1) Mix the raw materials containing CaO, Al2O3, and ZrO2 evenly according to the mixing ratio, wherein the mixing ratio is such that the chemical composition Al2O3:CaO:ZrO2 is 45.8-95.8%:2.52-8.4%:0-50% by mass.

[0151] (2) The mixed raw materials are shaped at room temperature and then lightly sintered at 1400-1600℃ to obtain a pre-synthesized material;

[0152] (3) After crushing the above pre-synthesized material, it is placed in the mold of a high-temperature device for hot pressing and sintering. The maximum temperature is 1550-1800℃ and the hot pressing strength is 0.5-30 MPa.

[0153] In another preferred embodiment, a high-purity, dense calcium hexaaluminate-based refractory material can be prepared by the following methods and steps:

[0154] (1) Mix the raw materials containing CaO, Al2O3, and ZrO2 evenly;

[0155] (2) The mixed raw materials are shaped at room temperature and then lightly sintered at 1400-1600℃ to obtain a pre-synthesized material;

[0156] (3) After crushing the above pre-synthesized material, mix it evenly with the remaining raw materials containing CaO, Al2O3 and ZrO2. The mixing ratio of all raw materials is such that the chemical composition Al2O3:CaO:ZrO2 is 45.8-95.8%:2.52-8.4%:0-50% by mass.

[0157] (4) The mixture obtained in step (3) is placed in the mold of the high-temperature device for hot pressing and sintering, with a maximum temperature of 1550-1800℃ and a hot pressing strength of 0.5-30MPa.

[0158] This application also provides a working lining for a steel ladle used in steelmaking, comprising the refractory material described above or a high-purity, dense calcium hexaaluminate refractory material prepared by the preparation method described above.

[0159] This application also provides a working lining for an aluminum molten metal smelting vessel, comprising the refractory material described above or the high-purity, dense calcium hexaaluminate-based refractory material prepared by the preparation method described above.

[0160] This application also provides a refractory lining for an industrial kiln, comprising the refractory material described above or a high-purity, dense calcium hexaaluminate refractory material prepared by the preparation method described above.

[0161] The high-purity, dense calcium hexaaluminate refractory material provided in this application is prepared by hot pressing and sintering of fine raw material powder without adding sintering agent. It has high chemical purity, dense structure, good uniformity and high thermal shock stability. It can give full play to the advantages of calcium hexaaluminate refractory material in chemical composition, purify molten steel, and at the same time endow it with excellent resistance to molten steel corrosion, which has significant economic and social benefits.

[0162] Example

[0163] This application provides a general and / or specific description of the materials and test methods used in the experiments. In the following examples, unless otherwise specified, % represents wt%, i.e., weight percentage. Reagents or instruments used, unless otherwise specified, are all commercially available conventional reagent products. Table 1 lists the main raw materials used in the examples and their sources.

[0164] Table 1

[0165]

[0166] The phase composition of the refractory materials in each embodiment was analyzed using XRD. The materials were ground to a fineness below 325 mesh and then scanned using an X-ray diffractometer (Bruker: D8 ADVANCE). The diffraction data were analyzed and matched with a standard PDF card to obtain the relevant phases. The content of these phases was then determined by fitting the diffraction data.

[0167] The chemical composition of the refractory materials in each embodiment was determined using the XRF method in accordance with GB / T21114-2007.

[0168] Example 1

[0169] (1) Mix 935g of industrial alumina powder and 115g of calcium hydroxide fine powder evenly to obtain a mixture.

[0170] (2) Take 700g of the mixture, press it into shape, and then put it into a high-temperature device to heat it to 1400℃ and keep it at that temperature for 1.5 hours to carry out low-temperature pre-synthesis.

[0171] (3) The pre-synthesized sample is crushed and ground to a particle size ≤88μm, and then mixed evenly with the remaining 350g of mixture. The mixture is then placed in a mold of a high-temperature device for hot pressing and sintering. When the temperature rises to 1780℃, pressure is applied, and the maximum hot pressing strength is 3MPa, thus obtaining a high-density, high-purity calcium hexaaluminate refractory material.

[0172] The obtained refractory material was subjected to powder XRD analysis. The refractory material was ground to below 325 mesh and then scanned using an X-ray diffractometer (Bruker: D8 ADVANCE). By analyzing the diffraction data and matching it with a standard PDF card, the relevant phases were obtained. The content of these phases was then determined by fitting the diffraction data, revealing that the main phase was CA6. Based on the mass percentage of the phases in the tested refractory material, the CA6 content was 100%.

[0173] The refractory material was subjected to XRF analysis according to the standard, and the determination was carried out in accordance with GB / T21114-2007. The refractory material was found to contain 90.3% Al2O3 and 8.40% CaO by mass percentage.

[0174] The refractory material of this embodiment was tested according to GB / T2997-2000, and the bulk density was found to be 3.32 g / cm³. 3 .

[0175] Example 2

[0176] (1) Mix 400g of plate-shaped corundum fine powder, 388g of aluminum hydroxide fine powder and 110g of CaCO3 fine powder evenly, press them into shape, and then put them into a high-temperature device to heat to 1500℃ and keep them warm for 3 hours for low-temperature pre-synthesis.

[0177] (2) The pre-synthesized sample is crushed and ground to a particle size ≤ 88 μm, and then mixed evenly with 200 g of α-Al2O3 fine powder and 100 g of desiliconized zirconium fine powder to obtain a mixture.

[0178] (3) The mixture is placed in a mold of a high-temperature device for hot pressing and sintering. When the temperature rises to 1600℃, pressure is applied while the temperature is rising. The maximum temperature rises to 1740℃ and the maximum hot pressing strength is 6MPa, thus obtaining a high-density and high-purity calcium hexaaluminate refractory material.

[0179] The analysis was performed using the same method as in Example 1, and the main phases were found to be CA6, corundum, and zirconium oxide. The mass percentages of the phases in the tested refractory material were 67.4% for CA6, 17.5% for corundum, and 9.58% for zirconium oxide.

[0180] The analysis was performed using the same method as in Example 1, and the refractory material was found to contain 83.1% Al2O3, 5.45% CaO, and 9.65% ZrO2 by mass percentage.

[0181] The bulk density was determined using the same method as in Example 1, and was found to be 3.15 g / cm³. 3 .

[0182] Example 3

[0183] (1) Mix 190g of fine CA powder, 400g of off-white corundum powder and 432g of ρ-Al2O3 powder evenly to obtain a mixture.

[0184] (2) After the mixture is cast into a mold, it is placed in a high-temperature device and heated to 1550°C. The temperature is maintained for 1.5 hours to carry out low-temperature pre-synthesis.

[0185] (3) The pre-synthesized sample was crushed and ground to a particle size ≤88μm, and then placed in a mold of a high-temperature device for hot pressing and sintering. When the temperature was raised to 1700℃, pressure was applied, and the maximum hot pressing strength was 4MPa, thus obtaining a high-density and high-purity calcium hexaaluminate refractory material.

[0186] The analysis was performed using the same method as in Example 1, and the main phases were found to be CA6 and corundum. The mass percentage of CA6 phase and corundum phase in the measured refractory material was 78.2% and 19.2%, respectively.

[0187] The analysis was performed using the same method as in Example 1, and the refractory material was found to contain 92.1% Al2O3 and 6.43% CaO by mass percentage.

[0188] The bulk density was determined using the same method as in Example 1, and was found to be 3.15 g / cm³. 3 .

[0189] Example 4

[0190] (1) Mix 300g of active α-powder, 306g of γ-Al2O3 powder and 58g of quicklime powder evenly, press them into shape, and then put them into a high-temperature device to heat to 1500℃ and keep them at that temperature for 3 hours to carry out low-temperature pre-synthesis.

[0191] (2) The pre-synthesized sample is crushed and ground to a particle size ≤ 88 μm, and then mixed evenly with 350 g of fused zirconium oxide fine powder to obtain a mixed powder.

[0192] (3) The mixed powder is placed in a mold of a high-temperature device for hot pressing and sintering. The temperature is increased and the pressure is gradually increased. The temperature rises to a maximum of 1550℃ and the maximum hot pressing strength is 30MPa, thus producing a high-density and high-purity calcium hexaaluminate refractory material.

[0193] The analysis was performed using the same method as in Example 1, and the main phases were found to be CA6 and zirconium oxide. The mass percentage of CA6 phase and zirconium oxide phase in the measured refractory material was 64.2% and 35.0%, respectively.

[0194] The analysis was performed using the same method as in Example 1, and the refractory material was found to contain 59.54% Al2O3, 5.24% CaO, and 35% ZrO2 by mass percentage.

[0195] The bulk density was determined using the same method as in Example 1, and was found to be 3.30 g / cm³. 3 .

[0196] Example 5

[0197] (1) Mix 201g of fine CA2 powder, 500g of dense corundum powder and 321g of ρ-Al2O3 powder evenly to obtain a mixture.

[0198] (2) After the mixture is shaped and dried, it is placed in a high-temperature device and heated to 1600°C and kept at that temperature for 3.5 hours for low-temperature pre-synthesis.

[0199] (3) The pre-synthesized sample was crushed and ground to a particle size of ≤88μm and then placed in a mold of a high-temperature device for hot pressing and sintering. When the temperature rose to 1600℃, pressure was applied and the pressure was increased while the temperature was increased. The temperature rose to a maximum of 1760℃ and the maximum hot pressing strength was 1MPa, thus obtaining a high-density and high-purity calcium hexaaluminate refractory material.

[0200] The analysis was performed using the same method as in Example 1, and the main phases were found to be CA6 and corundum. The mass percentage of CA6 phase and corundum phase in the measured refractory material was 48.8% and 50%, respectively.

[0201] The analysis was performed using the same method as in Example 1, and the refractory material was found to contain 95.8% Al2O3 and 3.84% CaO by mass percentage.

[0202] The bulk density was determined using the same method as in Example 1, and was found to be 3.15 g / cm³. 3 .

[0203] Example 6

[0204] (1) Mix 300g of active α-powder, 306g of γ-Al2O3 powder, 350g of white corundum powder and 80g of calcium hydroxide powder evenly, press them into shape, and then put them into a high-temperature device to heat to 1500℃ and keep them warm for 1 hour to carry out low-temperature pre-synthesis.

[0205] (2) The pre-synthesized sample was crushed and ground to a particle size ≤88μm, and then placed in a mold of a high-temperature device for hot pressing and sintering. The temperature was increased and the pressure was gradually increased. When the temperature reached a maximum of 1650℃, the maximum hot pressing strength was 5MPa, thus producing a high-density and high-purity calcium hexaaluminate refractory material.

[0206] The analysis was performed using the same method as in Example 1, and the main phases were found to be CA6 and corundum. The mass percentage of CA6 phase and corundum phase in the measured refractory material was 62.1% and 35.0%, respectively.

[0207] The analysis was performed using the same method as in Example 1, and the refractory material was found to contain 94.54% Al2O3 and 5.13% CaO by mass percentage.

[0208] The bulk density was determined using the same method as in Example 1, and was found to be 2.95 g / cm³. 3 .

[0209] Example 7

[0210] (1) Mix 350g of CA6 powder, 200g of sintered corundum powder, 105g of ρ-Al2O3 powder and 350g of fused zirconia fine powder evenly to obtain a mixture.

[0211] (2) The mixture is placed in a mold of a high-temperature device for hot pressing and sintering. When the temperature rises to 1650℃, pressure is applied while the temperature is rising. The maximum temperature rises to 1750℃ and the maximum hot pressing strength is 15MPa, thus obtaining a high-density, high-purity calcium hexaaluminate refractory material.

[0212] The analysis was performed using the same method as in Example 1, and the main phases were found to be CA6, corundum, and zirconium oxide. The mass percentages of the phases in the tested refractory material were 35% for CA6, 28.9% for corundum, and 35.0% for zirconium oxide.

[0213] The analysis was performed using the same method as in Example 1, and the refractory material was found to contain 60.86% Al2O3, 2.94% CaO, and 35% ZrO2 by mass percentage.

[0214] The bulk density was determined using the same method as in Example 1, and was found to be 3.45 g / cm³. 3 .

[0215] Example 8

[0216] (1) Mix 700g of CA6 fine powder, 205g of ρ-Al2O3 powder and 100g of monoclinic zirconium oxide powder evenly to obtain a mixture.

[0217] (2) The mixture is placed in a mold of a high-temperature device for hot pressing and sintering. The temperature is increased and the pressure is gradually increased. The temperature is raised to a maximum of 1600℃ and the maximum hot pressing strength is 8MPa, thus producing a high-density and high-purity calcium hexaaluminate refractory material.

[0218] The analysis was performed using the same method as in Example 1, and the main phases were found to be CA6, corundum, and zirconium oxide. The mass percentages of the phases in the tested refractory material were 66.1% for CA6, 18.4% for corundum, and 9.46% for zirconium oxide.

[0219] The analysis was performed using the same method as in Example 1, and the refractory material was found to contain 84.12% Al2O3, 5.88% CaO, and 10% ZrO2 by mass percentage.

[0220] The bulk density was determined using the same method as in Example 1, and was found to be 2.90 g / cm³. 3 .

[0221] Example 9

[0222] (1) Mix 260g of γ-Al2O3 powder, 200g of white corundum powder and 44g of lime powder, shape them and put them into a high-temperature device to heat to 1550℃, keep warm for 3 hours, and carry out low-temperature pre-synthesis.

[0223] (2) The pre-synthesized sample was crushed and ground to a particle size ≤88μm, and then mixed evenly with 500g of fused zirconia fine powder to obtain a mixture.

[0224] (3) The mixture is placed in a mold of a high-temperature device for hot pressing and sintering. When the temperature rises to 1500℃, pressure is applied, and the pressure is increased while the temperature is increased. The temperature rises to a maximum of 1600℃, and the maximum hot pressing strength is 20MPa, thus obtaining a high-density and high-purity calcium hexaaluminate refractory material.

[0225] The analysis was performed using the same method as in Example 1, and the main phases were found to be CA6 and zirconium oxide. The mass percentage of CA6 phase and zirconium oxide phase in the measured refractory material was 47.5% and 50%, respectively.

[0226] The analysis was performed using the same method as in Example 1, and the refractory material was found to contain 45.8% Al2O3, 3.99% CaO, and 50% ZrO2 by mass percentage.

[0227] The bulk density was determined using the same method as in Example 1, and was found to be 3.30 g / cm³. 3 .

[0228] Example 10

[0229] (1) Mix 300g of CA6 fine powder, 200g of tabular corundum powder and 500g of tetragonal zirconia powder evenly to obtain a mixture.

[0230] (2) The mixture is placed in a mold of a high-temperature device for hot pressing and sintering. When the temperature rises to 1800℃, pressure is applied and the maximum hot pressing strength is 0.5MPa, thus obtaining a high-density, high-purity calcium hexaaluminate refractory material.

[0231] The analysis was performed using the same method as in Example 1, and the main phases were found to be CA6, corundum, and zirconium oxide. The mass percentages of the phases in the tested refractory material were 30% for CA6, 19.1% for corundum, and 50% for zirconium oxide.

[0232] The analysis was performed using the same method as in Example 1, and the refractory material was found to contain 46.3% Al2O3, 2.52% CaO, and 50% ZrO2 by mass percentage.

[0233] The bulk density was determined using the same method as in Example 1, and was found to be 3.65 g / cm³. 3 .

[0234] Example 11

[0235] (1) Mix 446g of industrial alumina powder, 300g of tabular corundum powder, 115g of calcium hydroxide fine powder and 214g of p-Al2O3 powder evenly to obtain a mixture.

[0236] (2) The mixture is placed in a mold of a high-temperature device for hot pressing and sintering. When the temperature rises to 1600℃, pressure is applied, and the maximum hot pressing strength is 3MPa, thus obtaining a high-density, high-purity calcium hexaaluminate refractory material.

[0237] The analysis was performed using the same method as in Example 1, and the main phases were found to be CA6 and corundum. The mass percentage of CA6 phase and corundum phase in the measured refractory material was 74.5% and 15.5%, respectively.

[0238] The analysis was performed using the same method as in Example 1, and the refractory material was found to contain 90.3% Al2O3 and 8.36% CaO by mass percentage.

[0239] The bulk density was determined using the same method as in Example 1, and was found to be 2.92 g / cm³. 3 .

[0240] Experimental Example: Refractory Material Performance Test

[0241] The refractory materials obtained in Examples 1-11 above and the comparative examples were subjected to performance tests such as erosion resistance and thermal shock stability.

[0242] The comparative example is a refractory material obtained according to the method of Example 1 of CN107500747 A.

[0243] The following describes the experiment in detail using Examples 1 and 2 as examples.

[0244] Samples were drilled from the hot-pressed test blocks obtained in Examples 1, 2, and the comparative example. As samples 1-3.

[0245] Samples 1, 2, and 3 were subjected to a material corrosion test under the same conditions of steel smelting. The test was a dynamic rotation test with the following conditions: temperature 1600℃, sample rotation 10 times per minute in steel and slag, and steel slag composition of CaO 51%, Al2O3 30%, SiO2 11%, MgO 8%, and CaO / SiO2 ratio of 4.6.

[0246] The above dynamic rotation experiment results show that after 8 minutes of rotation, sample 3 immersed in steel slag completely disintegrated. Compared to sample 3, samples 1 and 2 showed little change. After rotating for another 15 minutes, samples 1 and 2 were removed, and their roundness remained very obvious. The wettability of molten steel and slag was very low, and the corrosiveness was minimal, with virtually no change. Measurements showed that sample 1 was damaged by only about 0.5 mm, and sample 2 by only 0.2 mm, essentially without damage, indicating that the samples in this embodiment exhibit excellent corrosion resistance. Figure 2 This is a residual sample of corundum-spinel castable specimen 3 that collapsed during this experiment. Figure 3 Images of Sample 1 and Sample 2 after testing according to this application.

[0247] Table 2 shows the relevant parameters, performance test results, and evaluations of the embodiments and comparative examples of this application.

[0248] Table 2

[0249]

[0250] For refractory materials, their applicability and performance evaluation depend not only on their resistance to molten slag erosion but also on their thermal shock stability under rapid heating and cooling conditions. Poor thermal shock stability can lead to cracks during use, affecting the material's performance. Furthermore, the cost-effectiveness of the refractory material must be considered. For example, refractory materials with added zirconium oxide exhibit excellent resistance to molten slag erosion and thermal shock stability, and their performance is superior with higher addition amounts. However, zirconium oxide is relatively expensive. Therefore, the performance of the embodiments in this application is a result of comprehensive comparison.

[0251] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any modifications, equivalent substitutions, and improvements made by those skilled in the art within the scope of the technology disclosed in this invention, and within the spirit and principles of this application, should be covered within the scope of protection of this application.

Claims

1. A high-purity, dense calcium hexaaluminate-based refractory material, characterized in that, The bulk density of the refractory material is 2.90-3.65 g / cm³. 3 , The refractory material comprises CA6, corundum, and zirconium oxide, with the following percentages by mass: CA6 content 30-67.4%, corundum content 17.5-28.9%, and zirconium oxide content 9.46-50%. The chemical composition of the refractory material includes Al2O3, CaO, and ZrO2, with the following percentages by mass: Al2O3 46.3-84.12%, CaO 2.52-5.88%, and ZrO2 9.65-50%. Based on the percentage of the total mass of the refractory material, the content of the sintering-promoting component in the refractory material is ≤1.5%, and The mass ratio of fine powder in the raw material mixture for preparing the refractory material is 100%.

2. The refractory material according to claim 1, characterized in that, The content of the sintering-promoting component in the refractory material is ≤1.0% based on the percentage of the total mass of the refractory material.

3. The refractory material according to claim 1, characterized in that, The bulk density of the refractory material is 2.90-3.45 g / cm³. 3 .

4. The refractory material according to claim 1, characterized in that, The bulk density of the refractory material is 2.95-3.30 g / cm³. 3 .

5. A method for preparing a high-purity, dense calcium hexaaluminate-based refractory material, comprising the following steps: Some of the raw materials are mixed, pre-sintered at low temperature, crushed and pulverized, and then other remaining raw materials are added. After mixing evenly, a mixture is obtained. The mixture is then placed in a mold of a high-temperature device for hot pressing and sintering. The raw material is a fine powder; The fine powder includes Al2O3-CaO-based fine powder and fine powder containing ZrO2; The hot-pressing sintering temperature is 1550-1800℃; the hot-pressing strength is 0.5-30MPa; The prepared refractory material has a bulk density of 2.90-3.65 g / cm³. 3 The refractory material comprises CA6, corundum and zirconium oxide, and the percentage content of CA6 phase is 30-67.4%, the content of corundum phase is 17.5-28.9%, and the content of zirconium oxide phase is 9.46-50% based on the total mass of the refractory material.

6. The preparation method according to claim 5, characterized in that, The mass ratio of fine powder in the mixture is 100%.

7. The preparation method according to claim 5, characterized in that, The Al2O3-CaO fine powder is selected from CA6 fine powder containing CaO fine powder, or from a mixture of fine powder containing CaO and fine powder containing Al2O3.

8. The preparation method according to claim 7, characterized in that, The Al2O3-containing fine powder is selected from one or more of the following: active α-Al2O3 powder, γ-Al2O3 powder, ρ-Al2O3 powder, aluminum hydroxide fine powder, industrial alumina fine powder, white corundum fine powder, sub-white corundum fine powder, sintered corundum fine powder, and tabular corundum fine powder.

9. The preparation method according to claim 5, characterized in that, The CaO-containing fine powder is selected from one or more of the following: quicklime fine powder, limestone fine powder, calcium hydroxide fine powder, CA fine powder, CA2 fine powder, C12A7 fine powder, and CA6 fine powder.

10. The preparation method according to claim 5, characterized in that, The ZrO2-containing fine powder is selected from one or more of monoclinic zirconium oxide fine powder, tetragonal zirconium oxide fine powder, desilicationized zirconium oxide fine powder, and fused zirconium oxide fine powder.

11. The preparation method according to claim 5, characterized in that, Its features are, The particle size of the fine powder is ≤0.088mm.

12. A working lining for a steel ladle used in steelmaking, characterized in that, It includes the refractory material according to any one of claims 1-4 or the refractory material prepared by the preparation method according to any one of claims 5-11.

13. A working liner for an aluminum molten metal smelting and conveying ladle, characterized in that, It includes the refractory material according to any one of claims 1-4 or the refractory material prepared by the preparation method according to any one of claims 5-11.

14. A refractory lining for an industrial kiln, characterized in that, It includes the refractory material according to any one of claims 1-4 or the refractory material prepared by the preparation method according to any one of claims 5-11.

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