CN115180932B - In-situ synthesis of mullite porous ceramics based on high-sodium industrial alumina and its preparation method - Google Patents

Abstract

The invention relates to an in-situ synthesis of mullite porous ceramics based on high-sodium industrial alumina and a preparation method. Its technical scheme is: according to the mass ratio of high-sodium industrial alumina fine powder: tertiary bauxite fine powder is 1: (2.3～3.3) batching, high-sodium industrial alumina fine powder and tertiary bauxite fine powder are placed Mix in a ball mill to obtain a mixture; then add 10-20wt% polyvinyl alcohol solution to the mixture and mix to obtain ceramic powder; machine-press the ceramic powder at 80-150 MPa and dry at 100-110°C and then placed in a muffle furnace, kept in an air atmosphere at 1550-1650° C. for 2-3 hours, cooled, and obtained based on high-sodium industrial alumina in-situ synthesis of mullite porous ceramics. The main chemical composition of the high-sodium industrial alumina fine powder: Al ₂ O ₃ ≥ 98 wt%, Na ₂ O ≥ 1.2 wt%; the invention has low cost, saves energy and is environmentally friendly; the prepared product has good thermal shock resistance , good air permeability and excellent mechanical properties, significant economic benefits.

Description

In-situ synthesis of mullite porous ceramics based on high-sodium industrial alumina and its preparation method

technical field

The invention belongs to the technical field of mullite porous ceramics. It specifically relates to an in-situ synthesis of mullite porous ceramics based on high-sodium industrial alumina and a preparation method.

Background technique

As the main raw material for producing corundum, industrial alumina is often used in the field of refractory materials. At present, 95% of the industrial alumina in the world is produced by the Bayer process. Since NaOH solution needs to be added to dissolve the alumina during the production process, there is part of Na ₂ O in the calcined industrial alumina product, as shown in the formula ( 1) shows that 1% Na ₂ O as an impurity will form 16% β-Al ₂ O ₃ with Al ₂ O ₃ at high temperature, and the brittleness of β-Al ₂ O ₃ is much higher than that of α-Al ₂ O ₃ , so the mechanical properties of the material will be significantly reduced. Moreover, industrial alumina has a large number of pores left by the decomposition of the mother salt. During the sintering process, due to reactions such as phase change or dehydration, there are a large number of natural pores in the structure.

(1)

Mullite porous ceramic is a kind of ceramic material which has been fired at high temperature and has a large number of interconnected or isolated pores inside. Industrial alumina is often used as an alumina source to synthesize mullite porous ceramics.

(1) Wang Tao et al. (Wang Tao et al. In-situ synthesis of mullite from microsilica powder to prepare high-strength porous ceramic materials [J]. Silicate Bulletin, 2013, 32(11): 2244-2248.) Utilizing microsilica powder and industrial Using alumina as the starting material, mullite porous ceramics were prepared by in situ reaction. Although porous ceramics with mullite crystal interweaving structure have been prepared, the Al ₂ O ₃ content of the industrial alumina used is 99.75%, and the impurity content is very small, so the cost of removing impurities from raw materials is high. In addition, the pore-forming agent is added, and the natural pore structure of the industrial alumina mother salt is not effectively utilized, resulting in an increase in cost and pollution to the environment.

(2) Chen Gangling et al. (Chen Gangling et al. Preparation of high-strength porous mullite support by in-situ reaction sintering[J]. Rare Metal Materials and Engineering, 2008, 37(z1): 74-77.) Based on clay minerals and Industrial alumina is used as raw material, and porous mullite support is prepared by in-situ reaction sintering. The advantage is that the prepared mullite support has a good pore structure and high mechanical properties, but the disadvantage is: the addition of Feldspar is used to provide a liquid phase environment for mullite growth, and more impurities are introduced into the system. At the same time, its pore structure is mainly composed of mullite crystal columns. With the increase of sintering temperature, the densification process of the material is accelerated, and the pore diameter The size is reduced, and the advantages of high strength and high porosity cannot be combined.

High-sodium industrial alumina fine powder is low-grade industrial alumina that has not been treated with sodium removal process. Na ₂ O in industrial alumina is generally considered a harmful impurity. In the standard for alumina products (GB/T 24487- 2009) also strictly limited the content of Na ₂ O (Na ₂ O<0.7wt%). Therefore, in order to reduce the Na ₂ O content in industrial alumina, it is often necessary to consume a lot of resources and energy (such as reducing the Na ₂ O content by calcination of β-Al ₂ O ₃ at high temperature to convert it into gas phase), and for high Na There is no public report on the use of industrial alumina with ₂ O content in the synthesis of mullite porous ceramics.

Contents of the invention

The present invention aims to overcome the defects of the prior art, and the purpose is to provide a low-cost and environmentally friendly preparation method for in-situ synthesis of mullite porous ceramics based on high-sodium industrial alumina; Aluminum in-situ synthesis of mullite porous ceramics has good thermal shock resistance, good air permeability and excellent mechanical properties, and has significant economic benefits.

In order to achieve the above object, the technical scheme adopted in the present invention is:

According to the mass ratio of high-sodium industrial alumina fine powder: tertiary bauxite fine powder is 1: (2.3 ~ 3.3) ingredients, the high-sodium industrial alumina fine powder and the tertiary bauxite fine powder are placed in a ball mill and mix for 1-2 hours to obtain the mixture; then add 10-20wt% polyvinyl alcohol solution of the mixture and mix evenly to obtain the ceramic powder.

The ceramic powder is placed in a mold, machine-pressed at 80-150MPa, dried at 100-110°C for 20-24 hours; then placed in a muffle furnace, heated in an air atmosphere at 1550-1650°C Keeping the temperature for 2 to 3 hours under lower temperature, and then cooling to obtain a porous ceramic based on high-sodium industrial alumina in-situ synthesis of mullite.

The high-sodium industrial alumina fine powder refers to industrial alumina that has not been treated with a sodium removal process, and the main chemical components of the high-sodium industrial alumina fine powder are: Al ₂ O ₃ ≥ 98wt%, Na ₂ O ≥ 1.2wt %; The particle size of the high-sodium industrial alumina micropowder is 0.05~0.1mm.

The third-grade alumina fine powder: the content of Al ₂ O ₃ is 45-60wt%, the mass ratio of Al ₂ O ₃ : SiO ₂ is 1-1.8:1; the particle size of the third-grade alumina fine powder is ≤0.01mm.

The polyvinyl alcohol solution is a mixture of analytically pure polyvinyl alcohol and deionized water; wherein the mass ratio of analytically pure polyvinyl alcohol: deionized water is 0.05-0.06:1.

The grinding balls of the ball mill are corundum balls.

Owing to adopting above-mentioned technical scheme, the present invention has following positive effect compared with prior art:

(1) In the present invention, the formation temperature of the liquid phase of the tertiary alumina is lower than the formation temperature of β-Al ₂ O ₃ , so that the Na ₂ O on the phantom particles of the parent salt is dispersed when β-Al ₂ O ₃ is not formed Liquid phase absorption formed by uniform tertiary alumina fine powder. Calculated by the Factsage thermodynamic software: Schematic diagram of the composition evolution of the three-grade alumina and high-sodium industrial alumina in the sintering process in the prepared mullite porous ceramics based on in-situ synthesis of high-sodium industrial alumina; low-sodium Schematic diagram of compositional evolution of in situ synthesized mullite porous ceramics from industrial alumina during sintering. Therefore, it is known that there is no significant difference in the amount of mullite generated and the change of liquid phase content between high-sodium industrial alumina and low-sodium industrial alumina during the sintering process. In addition, it is known from the calculation of Factsage thermodynamic software that with the increase of Na ₂ O content in industrial alumina, the viscosity of liquid phase decreases. The results indicated that more Na ₂ O dissolved in the liquid phase penetrated into the false gap of the parent salt, increasing the reactivity. At the same time, the reduction of viscosity provides a liquid phase environment for mullite crystal columns, promotes the growth of mullite crystal columns, makes the crystal size of mullite crystal columns larger, and improves the mechanical properties of mullite porous ceramics based on high-sodium industrial alumina in situ synthesis. .

(2) The present invention blends the large-grained high-sodium industrial alumina fine powder with the false structure of the mother salt with the tertiary alumina fine powder of the small particle size, and utilizes the pore structure characteristics of the false structure material of the mother salt to effectively retain the high The large pore size porous skeleton structure of sodium industrial alumina makes the tertiary alumina fine powder evenly distributed around the structural skeleton of high sodium industrial alumina.

(3) The mullite crystal columns formed in the process of liquid phase sintering of the mullite porous ceramics based on high-sodium industrial alumina prepared by the present invention replace the solid-phase sintered alumina crystal grains with lower structural strength, mullite The growth of the crystal pillars opened up the original pore structure, which significantly improved the pore size and gas permeability of the in-situ synthesized mullite porous ceramics based on high-sodium industrial alumina. The generated mullite crystal columns are all based on the pseudo-skeleton of the mother salt of high-sodium industrial alumina, and the original loose pseudo-salt structure is transformed into the cross-column structure of mullite crystal columns, which can improve the in-situ synthesis of mullite based on high-sodium industrial alumina. Thermal Shock Resistance of Lishi Porous Ceramics.

(4) The industrial alumina with high Na ₂ O content used in the present invention has abundant sources and low cost. In particular, no high-temperature calcination treatment in the sodium removal process is required, which can save resources and energy. Therefore, the rational application of industrial alumina with high Na ₂ O content will help to improve the utilization efficiency of energy and resources, realize the high value-added conversion of low-value raw materials, and have significant economic benefits.

The in-situ synthesis of mullite porous ceramics based on high-sodium industrial alumina prepared by the present invention is tested: the main phase is mullite phase, and the apparent pore structure is mostly in a through state; the bulk density is 1.82-2.10g/cm ³ , The apparent porosity is 33-40%, the average pore diameter is 35-50μm, and the cold compressive strength is 90-110MPa.

Therefore, the invention has low cost, energy saving and environmental friendliness; the prepared mullite porous ceramic based on in-situ synthesis of high-sodium industrial alumina has good thermal shock resistance, good air permeability and excellent mechanical properties, and remarkable economic benefits.

Description of drawings

Fig. 1 is a kind of high-sodium industrial alumina based on high-sodium industrial alumina in-situ synthesis mullite porous ceramics prepared by the present invention and the component evolution schematic diagram of two kinds of raw materials of tertiary bauxite in the sintering process;

Figure 2 is a schematic diagram of component evolution during sintering of a low-sodium industrial alumina in situ synthesized mullite porous ceramic prepared;

Figure 3 is a schematic diagram of the influence of different _Na2O contents in industrial alumina on the liquid phase viscosity of in-situ synthesized mullite porous ceramics;

Fig. 4 is the microscopic morphology picture of the high-sodium industrial alumina raw material adopted in the present invention under high temperature conditions;

Fig. 5 is a picture of the microscopic appearance of a mullite porous ceramic based on in-situ synthesis of high-sodium industrial alumina prepared by the present invention.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, without limiting its protection scope.

In this specific implementation manner:

The high-sodium industrial alumina fine powder refers to industrial alumina that has not been treated with a sodium removal process, and the particle size of the high-sodium industrial alumina fine powder is 0.05-0.1mm;

The particle size of the tertiary alumina fine powder is ≤0.01mm;

The grinding balls of the ball mill are corundum balls.

No more details will be given in the embodiments.

Example 1

An in-situ synthesis of mullite porous ceramics based on high-sodium industrial alumina and a preparation method thereof. The preparation method described in this embodiment is:

The mass ratio of high-sodium industrial alumina fine powder: tertiary bauxite fine powder is 1: 2.3, and the high-sodium industrial alumina fine powder and the tertiary bauxite fine powder are placed in a ball mill and mixed for 1 hour to obtain the mixture; then add 10wt% polyvinyl alcohol solution to the mixture and mix evenly to obtain ceramic powder.

The ceramic powder is placed in a mold, machine-pressed at 80 MPa, dried at 110°C for 24 hours; then placed in a muffle furnace, kept at 1550°C for 3 hours in an air atmosphere, cooled, and manufactured In-situ synthesis of mullite porous ceramics based on high-sodium industrial alumina was obtained.

The main chemical components of the high-sodium industrial alumina fine powder: Al ₂ O ₃ is 98.2wt%, and Na ₂ O is 1.2wt%.

The tertiary alumina fine powder: the content of Al ₂ O ₃ is 48wt%, and the ratio of Al ₂ O ₃ : SiO ₂ is 1.3:1.

The polyvinyl alcohol solution is a mixed solution of analytically pure polyvinyl alcohol and deionized water; wherein: the mass ratio of analytically pure polyvinyl alcohol:deionized water is 0.05:1.

The in-situ synthesis of mullite porous ceramics based on high-sodium industrial alumina prepared in this example is tested: the main phase is mullite phase, and the apparent pore structure is mostly in a through state; the bulk density is 1.82g/cm ³ , and the apparent pores The ratio is 38%, the average pore diameter is 50μm, and the cold compressive strength is 110MPa.

Example 2

An in-situ synthesis of mullite porous ceramics based on high-sodium industrial alumina and a preparation method thereof. The preparation method described in this embodiment is:

The mass ratio of high-sodium industrial alumina fine powder: tertiary bauxite fine powder is 1: 2.5, and the high-sodium industrial alumina fine powder and the tertiary bauxite fine powder are placed in a ball mill and mixed for 1 Hours, the mixture is obtained; then 13wt% polyvinyl alcohol solution of the mixture is added, and the mixture is evenly mixed to obtain the ceramic powder.

The ceramic powder is placed in a mold, machine-pressed at 100 MPa, dried at 110°C for 22 hours; then placed in a muffle furnace, kept at 1600°C for 3 hours in an air atmosphere, cooled, and manufactured In-situ synthesis of mullite porous ceramics based on high-sodium industrial alumina was obtained.

The main chemical components of the high-sodium industrial alumina fine powder: Al ₂ O ₃ is 98.5wt%, and Na ₂ O is 1.3wt%.

The third-grade alumina fine powder: the content of Al ₂ O ₃ is 52wt%, and the ratio of Al ₂ O ₃ : SiO ₂ is 1.5:1.

The polyvinyl alcohol solution is a mixed solution of analytically pure polyvinyl alcohol and deionized water; wherein: the mass ratio of analytically pure polyvinyl alcohol:deionized water is 0.05:1.

The in-situ synthesis of mullite porous ceramics based on high-sodium industrial alumina prepared in this example is tested: the main phase is mullite phase, and the apparent pore structure is mostly in a through state; the bulk density is 2.03g/cm ³ , and the apparent pores The ratio is 38%, the average pore size is 42μm, and the cold compressive strength is 98MPa.

Example 3

An in-situ synthesis of mullite porous ceramics based on high-sodium industrial alumina and a preparation method thereof. The preparation method described in this embodiment is:

According to the high-sodium industrial alumina fine powder: the mass ratio of the three-grade bauxite fine powder is 1: 2.7 ingredients, the high-sodium industrial alumina fine powder and the three-grade bauxite fine powder are placed in the ball mill, mixed for 1.5 hour to obtain the mixture; then add 15wt% polyvinyl alcohol solution to the mixture and mix evenly to obtain ceramic powder.

The ceramic powder is placed in a mold, machine-pressed at 120MPa, dried at 110°C for 20 hours; then placed in a muffle furnace, kept at 1650°C for 3 hours in an air atmosphere, cooled, and manufactured In-situ synthesis of mullite porous ceramics based on high-sodium industrial alumina was obtained.

The main chemical composition of the high-sodium industrial alumina fine powder: Al ₂ O ₃ is 98.2wt%, and Na ₂ O is 1.5wt%.

Said tertiary alumina fine powder: the content of Al ₂ O ₃ is 55wt%, and the ratio of Al ₂ O ₃ : SiO ₂ is 1.4:1.

The polyvinyl alcohol solution is a mixed solution of analytically pure polyvinyl alcohol and deionized water; wherein: the mass ratio of analytically pure polyvinyl alcohol:deionized water is 0.05:1.

The in-situ synthesis of mullite porous ceramics based on high-sodium industrial alumina prepared in this example is tested: the main phase is mullite phase, and the apparent pore structure is mostly in a through state; the bulk density is 1.96g/cm ³ , and the apparent pores The ratio is 40%, the average pore size is 47μm, and the cold compressive strength is 102MPa.

Example 4

An in-situ synthesis of mullite porous ceramics based on high-sodium industrial alumina and a preparation method thereof. The preparation method described in this embodiment is:

According to the high-sodium industrial alumina fine powder: the mass ratio of the three-grade alumina fine powder is 1: 3 ingredients, the high-sodium industrial alumina fine powder and the three-grade alumina fine powder are placed in the ball mill, mixed for 1.5 Hours, the mixture is obtained; then 17wt% polyvinyl alcohol solution of the mixture is added, and the mixture is evenly mixed to obtain the ceramic powder.

The ceramic powder is placed in a mold, machine-pressed at 140MPa, dried at 100°C for 24 hours; then placed in a muffle furnace, kept at 1650°C for 2.5 hours in an air atmosphere, cooled, and manufactured In-situ synthesis of mullite porous ceramics based on high-sodium industrial alumina was obtained.

The main chemical composition of the high-sodium industrial alumina fine powder: Al ₂ O ₃ is 98.3wt%, and Na ₂ O is 1.4wt%.

Said tertiary alumina fine powder: the content of Al ₂ O ₃ is 48wt%, and the ratio of Al ₂ O ₃ : SiO ₂ is 1.5:1.

The polyvinyl alcohol solution is a mixed solution of analytically pure polyvinyl alcohol and deionized water; wherein: the mass ratio of analytically pure polyvinyl alcohol:deionized water is 0.06:1.

The in-situ synthesis of mullite porous ceramics based on high-sodium industrial alumina prepared in this example is tested: the main phase is mullite phase, and the apparent pore structure is mostly in a through state; the bulk density is 2.08g/cm ³ , and the apparent pores The ratio is 33%, the average pore size is 38μm, and the cold compressive strength is 90MPa.

Example 5

An in-situ synthesis of mullite porous ceramics based on high-sodium industrial alumina and a preparation method thereof. The preparation method described in this embodiment is:

According to the high-sodium industrial alumina fine powder: the mass ratio of the third-grade alumina fine powder is 1: 3.3 ingredients, the high-sodium industrial alumina fine powder and the third-grade alumina fine powder are placed in a ball mill, and mixed for 2 Hours, the mixture is obtained; add 20wt% polyvinyl alcohol solution to the mixture, and mix evenly to obtain ceramic powder.

The ceramic powder is placed in a mold, machine-pressed at 150MPa, dried at 100°C for 22 hours; then placed in a muffle furnace, kept at 1650°C for 2 hours in an air atmosphere, cooled, and manufactured In-situ synthesis of mullite porous ceramics based on high-sodium industrial alumina was obtained.

The main chemical composition of the high-sodium industrial alumina fine powder: Al ₂ O ₃ is 98.1wt%, and Na ₂ O is 1.5wt%.

The tertiary alumina fine powder: the content of Al ₂ O ₃ is 50wt%, and the ratio of Al ₂ O ₃ : SiO ₂ is 1.2:1.

The polyvinyl alcohol solution is a mixed solution of analytically pure polyvinyl alcohol and deionized water; wherein: the mass ratio of analytically pure polyvinyl alcohol:deionized water is 0.06:1.

The in-situ synthesis of mullite porous ceramics based on high-sodium industrial alumina prepared in this example is tested: the main phase is mullite phase, and the apparent pore structure is mostly in a through state; the bulk density is 2.10g/cm ³ , and the apparent pores The ratio is 35%, the average pore size is 35μm, and the cold compressive strength is 100MPa.

Compared with the prior art, this specific embodiment has the following positive effects:

(1) In this specific embodiment, the formation temperature of the liquid phase of the tertiary alumina is lower than the formation temperature of β-Al ₂ O ₃ , so that when the Na ₂ O on the false particles of the mother salt does not form β-Al ₂ O ₃ , It is absorbed by the liquid phase formed by uniformly dispersed tertiary alumina fine powder. Through the calculation of the Factsage thermodynamic software, the composition change comparison charts shown in Figures 1 to 3 were obtained. Figure 1 is a schematic diagram of the composition evolution of the three-grade alumina and high-sodium industrial alumina in the sintering process in the in-situ synthesis of mullite porous ceramics based on high-sodium industrial alumina prepared in Example 1; Figure 2 is the preparation A schematic diagram of the component evolution of a low-sodium industrial alumina in-situ synthesized mullite porous ceramic during the sintering process. The low-sodium industrial alumina in-situ synthesized mullite porous ceramic is to replace high- Except sodium industrial alumina, all the other low-sodium industrial alumina synthesized in-situ porous ceramics of mullite obtained by the same preparation method as in Example 1, that is, the in-situ synthesized mullite porous ceramics of low-sodium industrial alumina described in FIG. Schematic diagram of compositional evolution of tertiary bauxite and low-sodium industrial alumina during the sintering process; Factsage thermodynamic software from Figure 1 and Figure 2 (the abscissa is the mass of high-sodium/low-sodium industrial alumina participating in the reaction) It can be seen from the calculation of the viscosity module of the high-sodium industrial alumina and low-sodium industrial alumina that there is no significant difference in the amount of mullite generated and the change of the liquid phase content during the sintering process.

Figure 3 is a schematic diagram of the influence of different Na ₂ O contents in industrial alumina on the liquid phase viscosity of in-situ synthesized mullite porous ceramics. It can be seen from Figure 3 that: with the increase of Na ₂ O content in industrial alumina , the viscosity of the liquid phase decreases. The results indicated that more Na ₂ O dissolved in the liquid phase penetrated into the false gap of the parent salt, increasing the reactivity. At the same time, the reduction of viscosity provides a liquid phase environment for mullite crystal columns, promotes the growth of mullite crystal columns, makes the crystal size of mullite crystal columns larger, and improves the mechanical properties of mullite porous ceramics based on high-sodium industrial alumina in situ synthesis. .

(2) In this specific embodiment, the large-sized high-sodium industrial alumina fine powder with the false structure of the mother salt is blended with the tertiary alumina fine powder with a small particle size, and the pore structure characteristics of the false structure material of the mother salt are used (as shown in Figure 4 shown), effectively retaining the large-sized porous framework structure of high-sodium industrial alumina, so that the tertiary alumina fine powder is evenly distributed around the structural framework of high-sodium industrial alumina.

(3) The porous ceramics based on high-sodium industrial alumina in-situ synthesis of mullite prepared in this specific embodiment is shown in Figure 5, and Figure 5 is a kind of in-situ synthesis of mullite based on high-sodium industrial alumina prepared in Example 1 It can be seen from Figure 5 that the microscopic morphology of porous ceramics shows that the mullite crystal pillars formed in the liquid phase sintering process replaced the solid phase sintered alumina grains with low structural strength, and the growth of the mullite crystal pillars opened up. The original pore structure significantly improves the pore size and gas permeability of the in-situ synthesized mullite porous ceramics based on high-sodium industrial alumina. It can also be seen from Figure 5 that all the generated mullite crystal pillars rely on the false skeleton of the mother salt of high-sodium industrial alumina, and the original loose mother salt false structure is transformed into the intercolumn cross structure of mullite crystal pillars, which can improve the quality of the mullite crystal pillars based on high Thermal shock resistance of in situ synthesized mullite porous ceramics from sodium industrial alumina;

(4) The industrial alumina with high Na ₂ O content used in this embodiment has abundant sources and low cost. In particular, no high-temperature calcination treatment in the sodium removal process is required, which can save resources and energy. Therefore, the rational application of industrial alumina with high Na ₂ O content will help to improve the utilization efficiency of energy and resources, realize the high value-added conversion of low-value raw materials, and have significant economic benefits.

The in-situ synthesis of mullite porous ceramics based on high-sodium industrial alumina prepared in this specific embodiment is tested: the main phase is mullite phase, and the apparent pore structure is mostly in a through state; the bulk density is 1.82-2.10g/cm ^3. The apparent porosity is 33-40%, the average pore diameter is 35-50μm, and the cold compressive strength is 90-110MPa.

Therefore, this specific embodiment has low cost, energy saving and environmental friendliness; the prepared mullite porous ceramic based on high-sodium industrial alumina in-situ synthesis has good thermal shock resistance, good air permeability and excellent mechanical properties, and has remarkable economic benefits.

Claims (6)

1. A preparation method for synthesizing mullite porous ceramic in situ based on high-sodium industrial alumina is characterized by comprising the following steps:

mixing the high-sodium industrial alumina fine powder and the tertiary alumina fine powder according to the mass ratio of 1:2.3-3.3, and placing the high-sodium industrial alumina fine powder and the tertiary alumina fine powder in a ball mill to mix for 1-2 hours to obtain a mixture; adding 10-20wt% of polyvinyl alcohol solution into the mixture, and uniformly mixing to obtain ceramic powder;

placing the ceramic powder into a die, performing mechanical press forming under the condition of 80-150 MPa, and drying for 20-24 hours at the temperature of 100-110 ℃; then placing the ceramic in a muffle furnace, preserving heat for 2-3 hours in an air atmosphere at 1550-1650 ℃, and cooling to obtain the mullite porous ceramic synthesized in situ based on high-sodium industrial alumina;

the main chemical components of the high-sodium industrial alumina fine powder are as follows: al (Al) ₂ O ₃ ≥98wt%，Na ₂ O≥1.2wt%。

2. The method for preparing the mullite porous ceramic based on the in-situ synthesis of the high-sodium industrial alumina, which is disclosed in claim 1, wherein the granularity of the high-sodium industrial alumina fine powder is 0.05-0.1 mm.

3. The method for preparing the mullite porous ceramic based on the in-situ synthesis of high sodium industrial alumina according to claim 1, wherein the three-stage alumina fine powder is characterized in that: al (Al) ₂ O ₃ The content is 45-60wt%, al ₂ O ₃ ∶SiO ₂ The mass ratio of (2) is 1-1.8:1; the granularity of the tertiary alumina fine powder is less than or equal to 0.01mm.

4. The method for preparing the mullite porous ceramic based on the in-situ synthesis of the high sodium industrial alumina, which is characterized in that the polyvinyl alcohol solution is a mixed solution of analytically pure polyvinyl alcohol and deionized water; wherein: the mass ratio of the analytically pure polyvinyl alcohol to the deionized water is 0.05-0.06:1.

5. The method for preparing the mullite porous ceramic based on the high sodium industrial alumina in-situ synthesis of claim 1, wherein the grinding balls of the ball mill are corundum balls.

6. The high-sodium industrial alumina-based in-situ synthesized mullite porous ceramic is characterized in that the high-sodium industrial alumina-based in-situ synthesized mullite porous ceramic is prepared by the preparation method of the high-sodium industrial alumina-based in-situ synthesized mullite porous ceramic according to any one of claims 1-5.

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