A method for preparing zircon mullite brick with ultra-low apparent porosity at low temperature by using microporous zircon mullite composite material

Abstract

The present application relates to the technical field of refractory materials, and particularly relates to a preparation method of zircon mullite bricks with ultra-low apparent porosity prepared by using microporous zircon mullite composite materials at low temperature, which comprises the following steps: mixing a mixed slurry of microporous zircon mullite composite materials with particle sizes of 3mm≤d1<5mm, 1mm≤d1<3mm and 0.074mm≤d1<1mm, zirconium silicon ash, active ρ-Al2O3 and dextrin solution, and a mixture of microporous zircon mullite composite materials with particle sizes of 0mm<d1<0.074mm, calcined a-Al2O3 powder, metallic silicon and Suzhou soil, then pressing, low-temperature sintering, obtaining zircon mullite bricks, and soaking the zircon mullite bricks in high-permeability silicon sol and drying to obtain zircon mullite bricks with ultra-low apparent porosity. The zircon mullite bricks with ultra-low apparent porosity prepared by the method have improved compression strength and erosion resistance on the basis of maintaining low thermal conductivity, and realize direct application of microporous system raw materials to high-temperature working surfaces.

Description

Technical Field

[0001] This invention belongs to the field of refractory materials, specifically relating to a method for preparing ultra-low apparent porosity zircon mullite bricks using microporous zircon mullite multiphase materials at low temperature. Background Technology

[0002] With the advocacy of sustainable development, energy conservation and emission reduction have gradually become key issues of concern. The development of high-temperature industries requires that the next generation of refractory materials possess the following characteristics: lightweight, long service life, pollution-free, and functional. High-performance microporous lightweight raw materials have been well developed and applied, among which microporous lightweight composite refractory materials have become an indispensable basic material for high-temperature technology due to their superior comprehensive performance, and have become a major direction for the development of refractory material technology both domestically and internationally.

[0003] Currently, research on high-strength, high-temperature resistant, and corrosion-resistant heat-insulating refractory materials for direct use on working surfaces is limited. Microporous raw materials are significantly affected by their porous structure, particularly the presence of some non-uniform macropores, which greatly impacts their compressive strength, corrosion resistance, and thermal conductivity. Microporous zircon-mullite is prepared by introducing zirconium oxide into mullite and then using a special pore-forming process. It possesses characteristics such as uniform expansion, good thermal shock stability, high load softening point, low high-temperature creep value, high hardness, and good chemical corrosion resistance. How to utilize the inherent pore structure of microporous zircon-mullite raw materials, and through technical processing to form closed pores and reduce open pores, while maintaining low thermal conductivity, to improve compressive strength and corrosion resistance, and ultimately enable the direct application of microporous raw materials on high-temperature working surfaces, is a crucial and significant challenge that urgently needs to be addressed in this field. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a method for preparing ultra-low apparent porosity zircon mullite bricks using microporous zircon mullite multiphase materials at low temperatures.

[0005] Specifically, the present invention provides the following technical solutions:

[0006] In a first aspect, the present invention provides a method for preparing ultra-low apparent porosity zircon mullite bricks using microporous zircon mullite multiphase materials at low temperatures. The method includes sequentially mixing microporous zircon mullite multiphase materials of 3mm≤d1<5mm, 1mm≤d1<3mm, and 0.074mm≤d1<1mm, zircon silica fume, active ρ-Al2O3, and dextrin solution into a mixed slurry, and microporous zircon mullite multiphase materials of 0mm<d1<0.074mm, calcined α-Al2O3 powder, metallic silicon, and Suzhou clay. The mixture is then pressed and fired to obtain zircon mullite bricks. The zircon mullite bricks are then soaked in a high-permeability silica sol and dried to obtain ultra-low apparent porosity zircon mullite bricks.

[0007] This invention innovatively achieves a coating technology for microporous zircon-mullite using ultrafine raw materials by adjusting the mixing sequence of the above-mentioned raw materials, and realizes low-temperature firing through activation sintering technology. Finally, a silica sol impregnation technology is used to prepare zircon-mullite bricks with ultra-low apparent porosity. While maintaining the low thermal conductivity of the material, the compressive strength and corrosion resistance are improved, thereby enabling the direct application of microporous raw materials on high-temperature working surfaces.

[0008] Preferably, the method for preparing ultra-low apparent porosity zircon mullite bricks using microporous zircon mullite multiphase materials at low temperature includes the following steps:

[0009] 1) Mix and stir active ρ-Al2O3 with dextrin solution to obtain a slurry; mix microporous zircon mullite multiphase material with particle size 0mm < d1 < 0.074mm, calcined α-Al2O3 powder and metallic silicon to obtain a mixture.

[0010] 2) Microporous zircon-mullite multiphase materials with particle sizes of 3mm≤d1<5mm, 1mm≤d1<3mm and 0.074mm≤d1<1mm are dry-mixed, zirconium silicate fume is added and mixing is continued, then the slurry is added and mixed, and the mixture is mixed with Suzhou soil to obtain mud.

[0011] 3) Press the clay into brick blanks, dry, fire and cool them to obtain zircon mullite bricks;

[0012] 4) The zircon mullite bricks are soaked in highly permeable silica sol and then dried.

[0013] Preferably, the low-temperature firing temperature is 1250–1350℃, more preferably 1250–1300℃, and the firing time is 4–8 hours. By adopting the preferred low-temperature sintering conditions of this invention, and based on the specific preparation process of this invention, especially the mixing sequence of each raw material and the final high-permeability silica sol soaking, zircon mullite bricks with ultra-low apparent porosity and excellent comprehensive performance can be better prepared.

[0014] Preferably, in step 4), the temperature for drying the brick blank is 100–180°C and the drying time is 24–36 h.

[0015] Preferably, in step 4), the bulk density of the pressed brick blank is 2.30–2.50 g / cm³. 3 .

[0016] According to some embodiments of the present invention, during the low-temperature firing, the temperature is raised from room temperature to 1250–1350°C and held at this firing temperature for 4–8 hours, after which it is naturally cooled to room temperature. The temperature rise curves in some embodiments are shown below. Figure 1 As shown.

[0017] Preferably, in step 5), the sample is soaked in a silica sol with a concentration of 40% to 50% for 10 to 30 hours.

[0018] In this invention, calcined α-Al₂O₃ powder and zirconium silicate ash are introduced. Both powders have relatively fine particle sizes, with the calcined α-Al₂O₃ powder having a particle size D90 of less than 10 μm and the zirconium silicate ash having a particle size D90 of less than 5 μm. By controlling the particle size, they are fully mullitized during firing or use, forming zirconium mullite. Simultaneously, the purity is relatively high, strengthening the matrix and improving the material's high-temperature resistance. The fine zirconium silicate ash is added by mixing the aggregate pulp zirconium silicate ash with other fine powders, ensuring that the zirconium silicate ash fully coats the microporous zirconium mullite, forming a spherical shell-like structure. Furthermore, α-Al₂O₃ not only has good activity, interacting with other raw materials in the system to improve the bonding strength of the brick blank, but also, in conjunction with zirconium silicate ash and metallic silicon, promotes sintering and lowers the sintering temperature. Simultaneously, metallic silicon can oxidize during firing, reacting with alumina to form mullite, further reducing porosity and improving alkali resistance. This invention employs a 40-50% high-permeability silica sol soaking process for 10-30 hours. The silica sol fills the apparent pores of the microporous zircon-mullite bricks, which are then dried to obtain ultra-low apparent porosity zircon-mullite bricks with a porosity of less than 12%.

[0019] This invention innovatively changes the traditional production process of pre-shaped products, which involves adding aggregate first, then binder, and finally fine powder. Instead, it first adds microporous zircon-mullite aggregate, followed by ultrafine zircon silica fume. The high surface activity of the ultrafine raw materials allows for coating of the porous aggregate. Then, a mixture of active ρ-Al₂O₃ and dextrin aqueous solution is added, along with α-calcined alumina powder and metallic silicon powder, achieving direct coating of the porous raw materials during production. By strengthening the matrix through calcination of α-alumina powder, metallic silicon and active ρ-Al₂O₃ promote sample sintering and reduce porosity, significantly lowering the firing temperature by 100-150℃, achieving low-temperature sintering and reduced porosity. Through silica sol impregnation technology, the apparent porosity of the zircon-mullite bricks is further reduced, decreasing open pores. While maintaining a low thermal conductivity, the compressive strength and corrosion resistance are improved, enabling the direct application of the microporous system raw materials to high-temperature working surfaces.

[0020] Secondly, the present invention provides an ultra-low apparent porosity zircon mullite brick prepared by the above-mentioned method of preparing ultra-low apparent porosity zircon mullite bricks using microporous zircon mullite multiphase material at low temperature. The zircon mullite brick comprises the following raw materials in the following mass contents: 70-85 parts of microporous zircon mullite multiphase material, 5-10 parts of calcined α-Al2O3 powder, 2-5 parts of zircon silica fume, 3-5 parts of Suzhou clay, 1-3 parts of active ρ-Al2O3 powder, 2-5 parts of metallic silicon, and 3-5 parts of dextrin solution; the zircon mullite brick is obtained by soaking the zircon mullite brick in a high-permeability silica sol.

[0021] The present invention provides a method for preparing ultra-low apparent porosity zircon mullite bricks using microporous zircon mullite multiphase materials at low temperature. The ultra-low apparent porosity zircon mullite bricks are prepared by forming a large number of tiny closed pores inside the microporous particles through ultrafine powder coating technology. By immersing the zircon mullite bricks in silica sol, the open porosity of the system is reduced, so that the material maintains a low thermal conductivity and the compressive strength and corrosion resistance are significantly improved.

[0022] Preferably, the microporous zirconium mullite multiphase material contains 60±2% Al2O3 and 1-4% ZrO2.

[0023] Preferably, the bulk density of the microporous zirconium mullite multiphase material is 2.40–2.55 g / cm³. 3 The average pore size is 1–4 μm.

[0024] Preferably, the particle size distribution and dosage of the microporous zirconium mullite multiphase material are as follows: the mass ratio of 3mm≤d1<5mm, 1mm≤d1<3mm, 0.074mm≤d1<1mm and 0mm<d1<0.074mm is 0~10:35~50:15~25:18~28, preferably 5~10:35~45:15~25:18~25.

[0025] This invention uses microporous zirconium mullite multiphase material as the main raw material. Microporous zirconium mullite is prepared by introducing zirconium oxide into mullite and then performing a specific pore-forming process. It features uniform expansion, good thermal shock stability, high load softening point, low high-temperature creep value, high hardness, and good chemical corrosion resistance. The porous structure of microporous raw materials, especially the presence of some non-uniform macropores, significantly affects their compressive strength, corrosion resistance, and thermal conductivity. This invention aims to utilize the inherent pore structure characteristics of microporous zirconium mullite raw materials, and through technical processing, transform the micropores into closed pores, reducing open pores, thereby improving compressive strength and corrosion resistance while maintaining low thermal conductivity, ultimately enabling the direct application of microporous system raw materials on high-temperature working surfaces.

[0026] Preferably, the zirconium silicate ash contains ≥93% SiO2 by mass and has a particle size ≤0.005mm.

[0027] Preferably, the active ρ-Al2O3 powder has an Al2O3 mass content > 85% and a particle size ≤ 0.045 mm.

[0028] Preferably, the dextrin solution is obtained by mixing maltodextrin and water at a mass ratio of 1:1 to 2, and the specific gravity of the resulting dextrin solution is 1.1 to 1.2 g / cm³. 3 .

[0029] Preferably, the calcined α-Al2O3 powder has an Al2O3 content ≥ 99.0%, a Na2O content ≤ 0.4%, and a particle size ≤ 0.010 mm.

[0030] Preferably, in the metallic silicon, the mass content of Si is >98% and the particle size is ≤0.074mm.

[0031] Preferably, the Suzhou soil contains Al2O3 with a mass content of >28% and a particle size of ≤0.074mm.

[0032] Preferably, the highly permeable silica sol is a silica sol with a concentration of 40% to 50% and a particle size of 5±1 nm.

[0033] Further preferably, the ultra-low apparent porosity zircon mullite brick has a porosity of less than 12% and a bulk density of 2.3–2.45 g / cm³. 3 Strength greater than 80MPa, load softening temperature greater than 1600℃.

[0034] The ultra-low apparent porosity zircon mullite bricks prepared by this invention have a porosity of less than 12%, which is significantly lower than the 18%–22% porosity of microporous zircon mullite bricks. The bulk density of the zircon mullite bricks is 2.3–2.45 g / cm³. 3 With a strength greater than 80MPa and a load softening temperature greater than 1600℃, it achieves high-temperature working layer use while maintaining the original microporous structure. It is an excellent refractory product that is resistant to alkali corrosion, wear-resistant, high-temperature resistant, and has low thermal conductivity. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 This is a temperature rise curve of the firing process of the present invention, from room temperature to 1350°C. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0038] Unless otherwise specified, specific techniques or conditions in the embodiments of this invention shall be performed in accordance with the techniques or conditions described in the literature in this field, or in accordance with the product instructions. Devices, instruments, reagents, etc., whose manufacturers are not specified are all conventional products that can be purchased through legitimate channels. All raw materials used in this invention are readily available in the domestic market.

[0039] In the following examples of the present invention, unless otherwise specified, the microporous zircon-mullite multiphase material used contains 60±2% Al2O3, 1-4% ZrO2, 28-32% SiO2, and has a bulk density of 2.40-2.55 g / cm³. 3 The average pore size is 1–4 μm. The calcined α-Al₂O₃ powder used has an Al₂O₃ content ≥99.0% and a particle size ≤0.045 mm. The zirconium silicate ash used has a SiO₂ mass content ≥93% and a particle size ≤0.005 mm. The active ρ-Al₂O₃ powder has an Al₂O₃ mass content >85% and a particle size ≤0.045 mm. The Suzhou soil used has an Al₂O₃ mass content >28% and a particle size ≤0.074 mm. The metallic silicon used has a Si mass content >98% and a particle size ≤0.074 mm. The dextrin solution used is obtained by mixing maltodextrin and water at a mass ratio of 1:1–2, and the specific gravity of the resulting dextrin solution is 1.1–1.2 g / cm³. 3 The high-permeability silica sol used is a silica sol with a concentration of 40% to 50% and a particle size of about 5 nm.

[0040] Example 1

[0041] An ultra-low apparent porosity zircon mullite brick is prepared by soaking microporous zircon mullite brick and silica sol. The microporous zircon mullite brick is prepared from the following raw materials in the following mass percentages: 75% microporous zircon mullite multiphase material, 9% calcined α-Al2O3 powder, 5% zircon silica fume, 2% active ρ-Al2O3, 5% Suzhou clay, 4% metallic silicon; plus 3.5% dextrin aqueous solution of the total mass of the above raw materials.

[0042] The particle size distribution of the microporous zircon mullite homogeneous material is as follows: the mass percentages of 3mm≤d1<5mm, 1mm≤d1<3mm, 0.074mm≤d1<1mm, and 0mm<d1<0.074mm are 10%:40%:25%:25%.

[0043] The above raw materials were mixed (active ρ-Al2O3 and dextrin aqueous solution were mixed to obtain a slurry; microporous zircon-mullite multiphase material with particle size 0mm < d1 < 0.074mm, calcined α-Al2O3 powder and metallic silicon were mixed to obtain a mixture; microporous zircon-mullite multiphase material with particle size 3mm ≤ d1 < 5mm, 1mm ≤ d1 < 3mm and 0.074mm ≤ d1 < 1mm was dry-mixed, zirconium silicate ash was added and mixed again, then the above slurry was added and mixed, and the above mixture was added and mixed with Suzhou clay) to prepare mud, which was then pressed into brick blanks (bulk density of 2.49 g / cm³). 3 The process involves drying, firing, and cooling. During firing, the temperature is raised from room temperature to 1250℃ and held at this firing temperature for 8 hours to prepare microporous zircon mullite bricks. Then, the bricks are treated by soaking in a 40% high-permeability silica sol for 20 hours and then dried at 110℃ for 24 hours.

[0044] The performance of the ultra-low apparent porosity zircon mullite brick prepared in this embodiment was tested, and the results are as follows: the apparent porosity of the prepared zircon mullite brick is 10.2%, and the bulk density is 2.35 g / cm³. 3 It has a room temperature compressive strength of 97.3 MPa, a load softening temperature of 1652℃, a thermal shock resistance (1100℃, water cooling) of more than 15 cycles, and a thermal conductivity of 1.125 W·m at 1000℃. -1 ·K -1 .

[0045] Example 2

[0046] An ultra-low apparent porosity zircon mullite brick is prepared by soaking microporous zircon mullite brick and silica sol. The microporous zircon mullite brick is prepared from the following raw materials in the following mass percentages: 77% microporous zircon mullite multiphase material, 8% calcined α-Al2O3 powder, 5% zircon silica fume, 3% active ρ-Al2O3, 5% Suzhou clay, 2% metallic silicon; plus 4% dextrin aqueous solution of the total mass of the above raw materials.

[0047] The particle size distribution of the microporous zircon mullite homogeneous material is as follows: the mass percentages of 3mm≤d1<5mm, 1mm≤d1<3mm, 0.074mm≤d1<1mm, and 0mm<d1<0.074mm are 8%:45%:25%:22%.

[0048] The clay prepared by mixing the above raw materials according to the mixing sequence in Example 1 was then pressed into brick blanks (bulk density of 2.45 g / cm³). 3 The process involves drying, firing, and cooling. During firing, the temperature is raised from room temperature to 1300℃ and held at this firing temperature for 8 hours to prepare microporous zircon mullite bricks. Then, the bricks are treated by soaking in a 50% high-permeability silica sol for 28 hours and then dried.

[0049] The performance of the ultra-low apparent porosity zircon mullite brick prepared in this embodiment was tested, and the results are as follows: the apparent porosity of the prepared zircon mullite brick is 10.8%, and the bulk density is 2.31 g / cm³. 3 It has a room temperature compressive strength of 88.0 MPa, a load softening temperature of 1647℃, a thermal shock resistance (1100℃, water cooling) of more than 15 cycles, and a thermal conductivity of 1.042 W·m at 1000℃. -1 ·K -1 .

[0050] Example 3

[0051] An ultra-low apparent porosity zircon mullite brick is prepared by soaking microporous zircon mullite brick and silica sol. The microporous zircon mullite brick is prepared from the following raw materials in the following mass percentages: 79% microporous zircon mullite multiphase material, 8% calcined α-Al2O3 powder, 4% zircon silica fume, 2% active ρ-Al2O3, 5% Suzhou clay, 2% metallic silicon; plus 4% dextrin aqueous solution of the total mass of the above raw materials.

[0052] The particle size distribution of the microporous zircon mullite homogeneous material is as follows: the mass percentages of 3mm≤d1<5mm, 1mm≤d1<3mm, 0.074mm≤d1<1mm, and 0mm<d1<0.074mm are 8%:45%:20%:27%.

[0053] The clay prepared by mixing the above raw materials according to the mixing sequence in Example 1 was then pressed into brick blanks (bulk density of 2.44 g / cm³). 3 The process involves drying, firing, and cooling. During firing, the temperature is raised from room temperature to 1300℃ and held at this firing temperature for 8 hours to prepare microporous zircon mullite bricks. Then, the bricks are treated by soaking them in a 40% high-permeability silica sol for 24 hours, followed by drying.

[0054] The performance of the ultra-low apparent porosity zircon mullite brick prepared in this embodiment was tested, and the results are as follows: the apparent porosity of the prepared zircon mullite brick is 11.2%, and the bulk density is 2.32 g / cm³. 3 It has a room temperature compressive strength of 91.0 MPa, a load softening temperature of 1637℃, a thermal shock resistance (1100℃, water cooling) of more than 15 cycles, and a thermal conductivity of 0.972 W·m at 1000℃. -1 ·K -1 .

[0055] Example 4

[0056] An ultra-low apparent porosity zircon mullite brick is prepared by soaking microporous zircon mullite brick and silica sol. The microporous zircon mullite brick is prepared from the following raw materials in the following mass percentages: 85% microporous zircon mullite multiphase material, 5% calcined α-Al2O3 powder, 3% zircon silica fume, 1% active ρ-Al2O3, 3% Suzhou clay, 3% metallic silicon; plus 4.5% dextrin aqueous solution of the total mass of the above raw materials.

[0057] The particle size distribution of the microporous zircon mullite homogeneous material is as follows: the mass percentages of 3mm≤d1<5mm, 1mm≤d1<3mm, 0.074mm≤d1<1mm, and 0mm<d1<0.074mm are 5%:50%:22%:28%.

[0058] The clay prepared by mixing the above raw materials according to the mixing sequence in Example 1 was then pressed into brick blanks (bulk density of 2.39 g / cm³). 3 The process involves drying, firing, and cooling. During firing, the temperature is raised from room temperature to 1350℃ and held at this firing temperature for 8 hours to prepare microporous zircon mullite bricks. Then, the bricks are treated by soaking them in a 40% high-permeability silica sol for 30 hours, followed by drying.

[0059] The performance of the ultra-low apparent porosity zircon mullite brick prepared in this embodiment was tested, and the results are as follows: the apparent porosity of the prepared zircon mullite brick is 11.7%, and the bulk density is 2.28 g / cm³. 3 It has a room temperature compressive strength of 81.0 MPa, a load softening temperature of 1602℃, a thermal shock resistance (1100℃, water cooling) of more than 15 cycles, and a thermal conductivity of 0.867 W·m at 1000℃. -1 ·K -1 .

[0060] Comparative Example 1

[0061] An ultra-low apparent porosity zircon-mullite brick is prepared by impregnation of microporous zircon-mullite brick and silica sol. The microporous zircon-mullite brick is made from the following raw materials in the indicated mass percentages: 65% microporous zircon-mullite multiphase material, 20% andalusite (0mm < d1 < 0.074mm), 10% calcined α-Al2O3 powder, and 5% Suzhou clay; plus 3.5% dextrin aqueous solution of the total mass of the above raw materials. The particle size distribution of the homogeneous microporous zircon-mullite material is as follows: 3mm ≤ d1 < 5mm, 1mm ≤ d1 < 3mm, and 0.074mm ≤ d1 < 1mm, with a mass percentage ratio of 10%:50%:40%.

[0062] The above raw materials were mixed (andalusite and calcined α-Al₂O₃ powder were mixed to obtain a mixture; microporous zircon-mullite multiphase materials with particle sizes of 3mm≤d₁<5mm, 1mm≤d₁<3mm, and 0.074mm≤d₁<1mm were dry-mixed, then mixed with dextrin aqueous solution, and then mixed with the above mixture and Suzhou clay) to prepare mud, which was then pressed into brick blanks (bulk density of 2.58 g / cm³). 3 The process involves drying, firing, and cooling. During firing, the temperature is raised from room temperature to 1450℃ and held at this firing temperature for 8 hours to prepare microporous zircon mullite bricks.

[0063] The performance of the ultra-low apparent porosity zircon mullite brick prepared in this comparative example was tested, and the results are as follows: the apparent porosity of the prepared zircon mullite brick is 18.6%, and the bulk density is 2.47 g / cm³. 3 It has a room temperature compressive strength of 67.6 MPa, a load softening temperature of 1612℃, a thermal shock resistance (1100℃, water cooling) of more than 15 cycles, and a thermal conductivity of 1.376 W·m at 1000℃. -1 ·K -1 The porosity of this comparative example is significantly higher than that of the previous sets of examples, and its strength is lower.

[0064] Comparative Example 2

[0065] A zircon mullite brick is prepared from the following raw materials in the indicated mass percentages: 85% microporous zircon mullite multiphase material, 10% calcined α-Al2O3 powder, 5% Suzhou clay, plus 3.5% dextrin aqueous solution of the total mass of the above raw materials.

[0066] The particle size distribution of the microporous zircon mullite homogeneous material is as follows: the mass percentages of 3mm≤d1<5mm, 1mm≤d1<3mm, 0.074mm≤d1<1mm, and 0mm<d1<0.074mm are 10%:40%:25%:25%.

[0067] The above raw materials were mixed (microporous zircon-mullite multiphase material with a particle size of 0mm < d1 < 0.074mm and calcined α-Al2O3 powder were mixed to obtain a mixture; microporous zircon-mullite multiphase material with a particle size of 3mm ≤ d1 < 5mm, 1mm ≤ d1 < 3mm and 0.074mm ≤ d1 < 1mm was dry-mixed, then mixed with dextrin aqueous solution, and then mixed with the above mixture and Suzhou clay) to prepare mud. This mud was then pressed into brick blanks (bulk density of 2.31 g / cm³). 3 The process involves drying, firing, and cooling. During firing, the temperature is raised from room temperature to 1450℃ and held at this firing temperature for 8 hours to prepare microporous zircon mullite bricks.

[0068] The performance of the ultra-low apparent porosity zircon mullite brick prepared in this comparative example was tested, and the results are as follows: the apparent porosity of the prepared zircon mullite brick is 25.6%, and the bulk density is 2.18 g / cm³. 3 It has a room temperature compressive strength of 33.2 MPa, a load softening temperature of 1486℃, a thermal shock resistance (1100℃, water cooling) of more than 15 cycles, and a thermal conductivity of 0.811 W·m at 1000℃. -1 ·K -1 The porosity of this comparative example is significantly higher than that of the previous examples, requiring a significantly higher firing temperature. However, the strength and load softening temperature are significantly reduced, making this comparative example somewhat insufficient as a working lining.

[0069] The ultra-low apparent porosity zircon mullite bricks prepared by this invention have significantly improved various performance characteristics. While maintaining a low thermal conductivity, the material improves compressive strength and erosion resistance, thereby enabling the direct application of microporous raw materials on high-temperature working surfaces, which has a promising application prospect.

[0070] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing ultra-low apparent porosity zircon-mullite bricks using microporous zircon-mullite multiphase materials at low temperature, characterized in that, The process includes mixing and stirring active ρ-Al2O3 with dextrin solution to obtain a slurry; mixing microporous zircon mullite multiphase material with particle sizes of 0mm < d1 < 0.074mm, calcined α-Al2O3 powder, and metallic silicon to obtain a mixture; dry mixing microporous zircon mullite multiphase material with particle sizes of 3mm ≤ d1 < 5mm, 1mm ≤ d1 < 3mm, and 0.074mm ≤ d1 < 1mm, adding zircon silica fume and continuing mixing, then adding the slurry and mixing, adding the mixture and Suzhou clay to obtain mud, then pressing and low-temperature firing to obtain zircon mullite bricks; soaking the zircon mullite bricks in highly permeable silica sol and drying them to obtain zircon mullite bricks with ultra-low apparent porosity. The low-temperature firing temperature is 1250~1350℃; The zircon mullite brick comprises the following raw materials by mass content: 70-85 parts of microporous zircon mullite multiphase material, 5-10 parts of calcined α-Al2O3 powder, 2-5 parts of zircon silica fume, 3-5 parts of Suzhou clay, 1-3 parts of active ρ-Al2O3 powder, 2-5 parts of metallic silicon, and 3-5 parts of dextrin solution. The particle size distribution and dosage of the microporous zircon-mullite multiphase material are as follows: the mass ratio of 3mm≤d1<5mm, 1mm≤d1<3mm, 0.074mm≤d1<1mm and 0mm<d1<0.074mm is 5~10:35~45:15~25:18~25; The ultra-low apparent porosity zircon mullite bricks have a porosity of less than 12%.

2. The method for preparing ultra-low apparent porosity zircon-mullite bricks using microporous zircon-mullite multiphase materials at low temperature according to claim 1, characterized in that, Includes the following steps: 1) Mix and stir active ρ-Al2O3 with dextrin solution to obtain a slurry; mix microporous zircon mullite multiphase material with particle size 0mm < d1 < 0.074mm, calcined α-Al2O3 powder and metallic silicon to obtain a mixture. 2) Microporous zircon-mullite multiphase materials with particle sizes of 3mm≤d1<5mm, 1mm≤d1<3mm and 0.074mm≤d1<1mm are dry-mixed, zirconium silicate fume is added and mixing is continued, then the slurry is added and mixed, and the mixture is mixed with Suzhou soil to obtain mud. 3) Press the clay into brick blanks, dry, fire and cool them to obtain zircon mullite bricks; 4) The zircon mullite bricks are soaked in highly permeable silica sol and then dried.

3. The method for preparing ultra-low apparent porosity zircon-mullite bricks using microporous zircon-mullite multiphase materials at low temperature according to claim 2, characterized in that, The low-temperature firing time is 4-8 hours.

4. The method for preparing ultra-low apparent porosity zircon-mullite bricks using microporous zircon-mullite multiphase materials at low temperature according to claim 2, characterized in that, In step 4), the drying temperature of the brick blanks is 100~180℃ and the drying time is 24~36h; And / or, in step 4), the bulk density of the pressed brick blank is 2.30~2.50 g / cm³. 3 .

5. The method for preparing ultra-low apparent porosity zircon mullite bricks using microporous zircon mullite multiphase materials at low temperature according to any one of claims 1-4, characterized in that, In step 5), the sample is soaked in silica sol with a concentration of 40% to 50% for 10 to 30 hours.

6. A zircon-mullite brick with ultra-low apparent porosity, characterized in that, The ultra-low apparent porosity zircon mullite brick prepared by the method of preparing ultra-low apparent porosity zircon mullite brick using microporous zircon mullite multiphase material at low temperature according to any one of claims 1-5.

7. The ultra-low apparent porosity zircon-mullite brick according to claim 6, characterized in that, The microporous zirconium mullite multiphase material contains 60±2% Al2O3 and 1~4% ZrO2. And / or, the bulk density of the microporous zirconium mullite multiphase material is 2.40~2.55 g / cm³. 3 The average pore size is 1~4μm.

8. The ultra-low apparent porosity zircon-mullite brick according to claim 6, characterized in that, The zirconium silicate ash contains SiO2 with a mass content of ≥93% and a particle size of ≤0.005mm. And / or, in the active p-Al2O3 powder, the mass content of Al2O3 is >85% and the particle size is ≤0.045mm; And / or, the dextrin solution is obtained by mixing maltodextrin and water at a mass ratio of 1:1 to 2, and the specific gravity of the resulting dextrin solution is 1.1 to 1.2 g / cm³. 3 .

9. The ultra-low apparent porosity zircon-mullite brick according to any one of claims 6-8, characterized in that, The calcined α-Al2O3 powder has an Al2O3 content ≥ 99.0%, a Na2O content ≤ 0.4%, and a particle size ≤ 0.010 mm. And / or, in the metallic silicon, the mass content of Si is >98% and the particle size is ≤0.074mm; And / or, in the Suzhou soil, the mass content of Al2O3 is >28%, and the particle size is ≤0.074mm; And / or, the highly permeable silica sol is a silica sol with a concentration of 40%~50% and a particle size of 5±1nm.

10. The ultra-low apparent porosity zircon-mullite brick according to any one of claims 6-8, characterized in that, The bulk density of zircon mullite bricks is 2.3~2.45 g / cm³. 3 Strength greater than 80MPa, load softening temperature greater than 1600℃.

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