Microporous silicon carbide abrasive brick for garbage high-temperature cracking furnace and preparation method of microporous silicon carbide abrasive brick

Abstract

The invention relates to the technical field of refractory bricks, in particular to a microporous silicon carbide abrasive brick for a garbage high-temperature cracking furnace, which comprises the following components in percentage by weight: 10-20% of mullite; 10 to 15% of andalusite; 3 to 5 percent of alpha-Al2O3 micro powder; 8 to 12% of kaolinite; 7 to 9% of bauxite; 4-6% of modified phosphate tailing ceramsite; 1-3% of a binding agent; 0.5-1% of an infrared opacifying agent; silicon carbide: the balance; the preparation method of the microporous silicon carbide wear-resistant brick comprises the following steps: S1, preparing a material A, a material B and a material C; s2, preparing a pre-pressed brick; s3, preparing a molded brick; and S4, obtaining a finished product. According to the silicon carbide brick prepared by the invention, the modified phosphate tailing ceramsite is added, so that molten metal or furnace slag can be prevented from permeating at high temperature; the infrared opacifying agent is added, so that middle and far infrared radiation can be reflected, the heat efficiency of the hearth is improved, a structure with a compact surface layer and a porous middle part is formed through differential proportioning of the brick body, and strength and functionality are both considered.

Description

Technical Field

[0001] This invention relates to the field of refractory brick technology, specifically to a microporous silicon carbide wear-resistant brick for a waste high-temperature pyrolysis furnace and its preparation method. Background Technology

[0002] The core working principle of a high-temperature pyrolysis furnace is to induce thermochemical decomposition reactions in waste under anaerobic or low-oxygen high-temperature conditions. Typically, the furnace temperature can soar to 800~1600℃, and these extreme high-temperature conditions break the chemical bonds of complex organic compounds in the waste.

[0003] The operating temperature of waste pyrolysis furnaces typically exceeds 1200℃, and in some areas even reaches 1400~1600℃. Ordinary refractory materials are prone to softening or melting under long-term high temperatures, and the mechanical wear of solid materials (such as iron drums and hard slag) and the scouring effect of flue gas in the waste pyrolysis furnace place extremely high demands on the wear resistance of the materials. Although traditional silicon carbide bricks have excellent performance, they have problems such as poor high-temperature oxidation resistance.

[0004] To address the aforementioned problems, this invention proposes the design of a microporous silicon carbide wear-resistant brick for a waste high-temperature pyrolysis furnace and its preparation method. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a microporous silicon carbide wear-resistant brick for a waste high-temperature pyrolysis furnace and its preparation method.

[0006] A microporous silicon carbide wear-resistant brick for a waste high-temperature pyrolysis furnace, comprising, by weight percentage: Mullite: 10~20%; Andalusite: 10-15%; α-Al2O3 micro powder: 3~5%; Kaolinite: 8~12%; Bauxite: 7-9%; Modified phosphate tailings ceramsite: 4~6%; Binder: 1~3%; Infrared shielding agent: 0.5~1%; Silicon carbide: Balance; Among them, the particle size of mullite is ≤5mm, the particle size of andalusite is ≤1mm, the particle size of α-Al2O3 micro powder is 320~360 mesh, the particle size of kaolinite is ≤0.088mm, the particle size of bauxite is ≤0.088mm, the particle size of modified phosphorus tailings ceramsite is ≤1mm, and the particle size of silicon carbide is ≤1mm.

[0007] Furthermore, the preparation method of the modified phosphorus tailings ceramsite is as follows: After crushing the phosphate tailings, they were impregnated in a 25-28% hydrochloric acid solution at a solid-liquid ratio of 1g:10-15ml for 2-4 hours. After impregnation, the mixture was filtered, washed with water, and dried. Then, the temperature was raised to 400-500℃ and held for 15-20 minutes to obtain pretreated ceramsite. Pretreated ceramsite was impregnated in a trifluoropropyltrichlorosilane solution at a solid-liquid ratio of 1g:4~8ml for 1~2h, and then heated to 800~900℃ and kept at that temperature for 30~40min to obtain pre-cured ceramsite. Thorium oxide fibers are sprayed onto the surface of pre-cured ceramsite. The length of the thorium oxide fibers is 0.2~0.3 mm, the aspect ratio is 3~5:1, and the spraying thickness is 0.05~0.08 mm. After spraying, the ceramsite is irradiated under gamma rays with an irradiation dose of 15~20 kGy, an irradiation dose rate of 0.3~0.5 kGy / h, and an irradiation time of 1~5 min. After irradiation, the temperature is raised to 1000~1200℃ and held for 15~20 min to obtain modified phosphorus tailings ceramsite.

[0008] Explanation: Hydrochloric acid impregnation can dissolve carbonate impurities in phosphate tailings, forming multi-level pores. The high-porosity structure buffers thermal stress at high temperatures, improving the thermal shock resistance of refractory bricks. After impregnation in silane solution, pre-curing forms a -Si-O-Si- cross-linked network, creating a hydrophobic layer that prevents molten metal or slag from penetrating at high temperatures. The sprayed thorium oxide fibers have extremely high melting points and can form a three-dimensional network skeleton on the surface of ceramsite. Gamma-ray irradiation induces chemical bonding between the fibers and the ceramsite matrix, increasing the compressive strength of the refractory bricks after sintering.

[0009] Furthermore, the mullite with a particle size ≤5mm is composed of mullite with particle sizes ≤1mm, 1~3mm and 3~5mm in a mass ratio of 1:0.8:0.5~0.8.

[0010] Note: Fine-grained mullite (≤1mm) forms a high-silica glass phase in the matrix. Its low thermal expansion characteristics can offset the thermal expansion stress of coarse particles. The heterogeneous structure formed by multi-level particle size can induce crack deflection or bifurcation at the coarse / fine particle interface, thus improving the fracture work.

[0011] Furthermore, the silicon carbide with a particle size ≤1mm is composed of silicon carbide particles with a particle size ≤0.088mm and silicon carbide particles with a particle size of 0.088~1mm in a mass ratio of 1~1.2:1.

[0012] Explanation: The high specific surface area of ​​fine particles makes it easier to generate a liquid phase during sintering, which encapsulates coarse particles to form an "anchoring effect," improving the interfacial bonding strength and preventing coarse particles from falling off during wear.

[0013] Furthermore, the surface of the silicon carbide has a corrosion-resistant layer, which is prepared by chemical vapor deposition of chromium oxide on the silicon carbide surface under the conditions of nitrogen and argon gas with an ambient temperature of 980~1050℃ and a flow ratio of 3~6:1, the deposition pressure is 10~50kPa, the time is 35~55min, and the flow rate of the nitrogen source gas is 15~25L / min, thereby obtaining the corrosion-resistant layer.

[0014] Explanation: The chromium oxide coating formed by the CVD process is chemically bonded to the silicon carbide substrate (such as Cr-O-Si bonds), which improves the interfacial bonding strength. This structure can also prevent particle detachment during wear, further enhancing the wear resistance of the refractory brick.

[0015] Furthermore, the binder is aluminum dihydrogen phosphate.

[0016] Note: The addition of aluminum dihydrogen phosphate can significantly improve the high-temperature resistance of refractory bricks. Under high-temperature conditions, aluminum dihydrogen phosphate can form stable chemical bonds, enhance the structural strength of the brick, and prevent deformation and cracking caused by high temperature.

[0017] Furthermore, the infrared shielding agent is ZS1061 or ZS811.

[0018] Explanation: Infrared shielding agent enhances the erosion resistance of refractory bricks by forming a hard glazed shell, while reflecting infrared heat energy inside the furnace, reducing flue gas temperature and improving thermal efficiency.

[0019] The preparation method of a microporous silicon carbide wear-resistant brick for a waste high-temperature pyrolysis furnace as described in any of the above includes the following steps: S1. Mix andalusite, α-Al2O3 micro powder, kaolinite, and bauxite, and record them as auxiliary materials; Mix 70-80% of mullite, 80-90% of silicon carbide, 60-70% of auxiliary materials, 70-80% of modified phosphorus tailings ceramsite, and 75-85% of binder, and denote this mixture as material A. Mix 5-10% of mullite, 1-5% of silicon carbide, 15-25% of auxiliary materials, 5-10% of modified phosphorus tailings ceramsite, and 5-10% of binder, and denote this mixture as material B. The remaining raw materials are mixed and denoted as material C; S2. Pre-press material A into shape at a pressing temperature of 80~85℃ for 30~35 minutes to obtain pre-pressed bricks; S3. Drill holes in the pre-pressed brick to obtain upper layer holes, upper middle layer holes, lower middle layer holes, and lower layer holes. The spacing between the holes in each layer is equal, and the holes in the same layer have the same diameter and are evenly distributed. Then fill the upper layer holes and lower layer holes with material B, and fill the upper middle layer holes and lower middle layer holes with material C. Then press and shape the brick. The pressing temperature is 90~100℃ and the time is 20~30min to obtain the shaped brick. S4. The molded bricks are fired at a temperature of 1400~1500℃ for 20~22 hours to obtain silicon carbide bricks.

[0020] Further, in step S4, the surface of the formed brick is first subjected to femtosecond laser processing. The wavelength of the femtosecond laser is 1030nm, the pulse width is 150~200fs, the repetition frequency is 50~150kHz, the spot diameter is 35μm, and the time is <1s.

[0021] Note: During the processing, the surface nanostructure of silicon carbide can be modified synchronously by adjusting the laser parameters, thereby improving the high-temperature oxidation resistance of refractory bricks.

[0022] Compared with existing silicon carbide bricks, the beneficial effects of this invention are: (1) In the silicon carbide bricks prepared by this method, the synergistic reinforcement of mullite and andalusite can buffer thermal stress. Combined with the high thermal conductivity of silicon carbide, it has good thermal shock resistance. The binder and α-Al2O3 micro powder synergistically form micropores with low porosity but uniform distribution. When the temperature changes rapidly, energy is absorbed through pore deformation, which improves thermal shock resistance. The silicon carbide-mullite form a composite skeleton, which reduces the wear amount compared with pure silicon carbide bricks. Kaolinite generates a glass phase at high temperature and forms a high viscosity aluminosilicate layer with bauxite, which can block the penetration of molten slag. The multi-level pores formed by the activation of modified phosphorus tailings ceramsite by hydrochloric acid reduce the bulk density of the brick and improve its lightweight. The addition of infrared shading agent can reflect mid- and far-infrared radiation and improve the thermal efficiency of the furnace.

[0023] (2) In the preparation of silicon carbide bricks, this method uses material A, which contains a high proportion of mullite and silicon carbide, as the matrix to form a wear-resistant skeleton; material B, which has a lower silicon carbide content and is combined with auxiliary materials, forms a transition buffer layer, which retains a certain wear resistance and absorbs thermal stress through the high-temperature mullite formation of andalusite, reducing cracks caused by the difference in thermal expansion between the matrix and the surface. Material C, which contains more modified phosphorus tailings ceramsite than material B, forms a tough interlayer, which disperses stress through microcracks, further improving the overall thermal shock resistance. A three-dimensional heat dissipation channel is formed through a four-row hole design, which, combined with the low thermal expansion coefficient of the modified phosphorus tailings ceramsite, reduces the thermal shock crack propagation rate of the material, forming a porous heat insulation layer. The combination of two pressing and vacuum drying processes improves the uniformity of stress distribution, ensures the compactness and dimensional stability of the green body, and reduces the risk of deformation during high-temperature sintering. Attached Figure Description

[0024] Figure 1 This is a comparison chart of the high-temperature compressive strength results of Investigation 1 of this invention; Figure 2 This is a comparison chart of the wear results of Investigation 1 of this invention; Figure 3 This is a comparison chart of the high-temperature compressive strength results of Investigation 2 of this invention; Figure 4 This is a comparison chart of the wear amount results in Investigation 2 of this invention; Figure 5 This is a comparison chart of the high-temperature compressive strength results of Investigation 3 of this invention; Figure 6 This is a comparison chart of the wear amount results in Investigation 3 of this invention; Figure 7 This is a schematic diagram of the pores in the silicon carbide brick of the present invention. Detailed Implementation

[0025] To further illustrate the methods and effects of this invention, the technical solution of this invention will be clearly and completely described below in conjunction with experiments.

[0026] Example 1: A microporous silicon carbide wear-resistant brick for a waste high-temperature pyrolysis furnace, comprising, by weight percentage: Mullite: 15%; andalusite: 12.5%; α-Al₂O₃ micro powder: 4%; Kaolinite: 10%; Bauxite: 8%; Modified phosphorus tailings ceramsite: 5%; Binder: 2%; the binder is aluminum dihydrogen phosphate; Infrared light-blocking agent: 0.8%; the infrared light-blocking agent is ZS1061; Silicon carbide: Balance; Among them, the particle size of mullite is ≤5mm, the particle size of andalusite is ≤1mm, the particle size of α-Al2O3 micro powder is 330~350 mesh, the particle size of kaolinite is ≤0.088mm, the particle size of bauxite is ≤0.088mm, the particle size of modified phosphorus tailings ceramsite is ≤1mm, and the particle size of silicon carbide is ≤1mm. The mullite with a particle size ≤5mm is composed of mullite with particle sizes ≤1mm, 1~3mm and 3~5mm in a mass ratio of 1:0.8:0.6; the silicon carbide with a particle size ≤1mm is composed of silicon carbide particles with a particle size ≤0.088mm and a particle size of 0.088~1mm in a mass ratio of 1.1:1. The method for preparing the modified phosphorus tailings ceramsite is as follows: After crushing the phosphate tailings, they were impregnated in a 27% hydrochloric acid solution at a solid-liquid ratio of 1g:13ml for 3 hours. After impregnation, the mixture was filtered, washed with water, dried, and then heated to 450℃ and held for 18 minutes to obtain pretreated ceramsite. The pretreated ceramsite was impregnated in a trifluoropropyltrichlorosilane solution at a solid-liquid ratio of 1g:6ml for 1.5h, and then heated to 850℃ and held for 35min to obtain pre-cured ceramsite. Thorium oxide fibers were sprayed onto the surface of pre-cured ceramsite. The length of the thorium oxide fibers was 0.25 mm, the aspect ratio was 4:1, and the spraying thickness was 0.07 mm. After spraying, the ceramsite was irradiated under gamma rays with an irradiation dose of 15~20 kGy, an irradiation dose rate of 0.4 kGy / h, and an irradiation time of 3 min. After irradiation, the temperature was raised to 1100℃ and held for 18 min to obtain modified phosphorus tailings ceramsite.

[0027] Example 2: The preparation method of microporous silicon carbide wear-resistant bricks for high-temperature pyrolysis furnaces as described in Example 1 includes the following steps: S1. Mix andalusite, α-Al2O3 micro powder, kaolinite, and bauxite, and record them as auxiliary materials; Mix 75% of mullite, 85% of silicon carbide, 65% of auxiliary materials, 75% of modified phosphorus tailings ceramsite, and 80% of binder, and denote this mixture as material A. Mix 7.5% mullite, 3% silicon carbide, 20% auxiliary materials, 7.5% modified phosphate tailings ceramsite, and 7.5% binder, and denote this mixture as material B. The remaining raw materials are mixed and denoted as material C; In materials A, B, and C, the particle size ratios of mullite and silicon carbide are consistent with the overall particle size ratios of mullite and silicon carbide. S2. Pre-press material A into shape at a pressing temperature of 82℃ for 2 minutes to obtain pre-pressed bricks. S3, such as Figure 7 As shown, the pre-pressed brick is perforated to obtain upper layer holes, upper middle layer holes, lower middle layer holes, and lower layer holes, with equal spacing between each layer of holes. Holes in the same layer have the same diameter and are evenly distributed. Material B is then filled into the upper layer holes and the lower layer holes, and material C is filled into the upper middle layer holes and the lower middle layer holes. The brick is then pressed into shape at a temperature of 95°C for 25 minutes to obtain the shaped brick. S4. First, the surface of the molded brick is processed by femtosecond laser. The wavelength of the femtosecond laser is 1030nm, the pulse width is 175fs, the repetition frequency is 100kHz, the spot diameter is 35μm, and the time is 0.9s. The molded brick is then placed in a vacuum drying oven for drying at a temperature of 1450℃ for 21h to obtain silicon carbide brick.

[0028] Example 3: This example differs from Example 1 in that, by weight percentage, it includes: Mullite: 10%; Andalusite: 15%; α-Al₂O₃ micro powder: 3%; Kaolinite: 8%; Bauxite: 7%; Modified phosphorus tailings ceramsite: 4%; Binder: 1%; Infrared shielding agent: 0.5%; the infrared shielding agent is ZS811; Silicon carbide: Balance.

[0029] Example 4: This example differs from Example 1 in that, by weight percentage, it includes: Mullite: 20%; Andalusite: 10%; α-Al₂O₃ micro powder: 5%; Kaolinite: 12%; Bauxite: 9%; Modified phosphorus tailings ceramsite: 6%; Binder: 3%; Infrared shielding agent: 1%; Silicon carbide: Balance.

[0030] Example 5: This example differs from Example 1 in that the particle size of the α-Al2O3 micro powder is 320~330 mesh, the mullite with a particle size ≤5mm is composed of mullite with particle sizes ≤1mm, 1~3mm and 3~5mm in a mass ratio of 1:0.8:0.5, and the silicon carbide with a particle size ≤1mm is composed of silicon carbide particles with a particle size ≤0.088mm and a particle size of 0.088~1mm in a mass ratio of 1:1.

[0031] Example 6: This example differs from Example 1 in that the particle size of the α-Al2O3 micro powder is 350~360 mesh, the mullite with a particle size ≤5mm is composed of mullite with particle sizes ≤1mm, 1~3mm and 3~5mm in a mass ratio of 1:0.8:0.8, and the silicon carbide with a particle size ≤1mm is composed of silicon carbide particles with a particle size ≤0.088mm and a particle size of 0.088~1mm in a mass ratio of 1.2:1.

[0032] Example 7: The difference between this example and Example 1 is that the phosphate tailings were crushed and then immersed in a 25% hydrochloric acid solution at a solid-liquid ratio of 1g:15ml. After immersion for 2 hours, the solution was filtered, washed with water, and dried.

[0033] Example 8: The difference between this example and Example 1 is that the phosphate tailings were crushed and then immersed in a 28% hydrochloric acid solution at a solid-liquid ratio of 1g:10ml. After immersion for 4 hours, the solution was filtered, washed with water, and dried.

[0034] Example 9: The difference between this example and Example 1 is that the pretreated ceramsite was impregnated in a trifluoropropyltrichlorosilane solution at a solid-liquid ratio of 1g:8ml for 1 hour.

[0035] Example 10: The difference between this example and Example 1 is that the pretreated ceramsite was impregnated in a trifluoropropyltrichlorosilane solution at a solid-liquid ratio of 1g:4ml for 2 hours.

[0036] Example 11: The difference between this example and Example 1 is that the length of the thorium oxide fiber is 0.2 mm, the aspect ratio is 3:1, and the spraying thickness is 0.05 mm.

[0037] Example 12: The difference between this example and Example 1 is that the length of the thorium oxide fiber is 0.3 mm, the aspect ratio is 5:1, and the spraying thickness is 0.08 mm.

[0038] Example 13: This example differs from Example 1 in that the irradiation dose is 15 kGy, the irradiation dose rate is 0.3 kGy / h, and the irradiation time is 1 min.

[0039] Example 14: This example differs from Example 1 in that the irradiation dose is 20 kGy, the irradiation dose rate is 0.5 kGy / h, and the irradiation time is 5 min.

[0040] Example 15: The difference between this example and Example 1 is that the temperature is raised to 400℃ and held for 15 minutes to obtain pretreated ceramsite; the temperature is raised to 900℃ and held for 30 minutes to obtain pre-cured ceramsite; and the temperature is raised to 1000℃ and held for 15 minutes to obtain modified phosphate tailings ceramsite.

[0041] Example 16: The difference between this example and Example 1 is that the temperature is raised to 500℃ and held for 20 minutes to obtain pretreated ceramsite; the temperature is raised to 800℃ and held for 40 minutes to obtain pre-cured ceramsite; and the temperature is raised to 1200℃ and held for 20 minutes to obtain modified phosphate tailings ceramsite.

[0042] Example 17: This example differs from Example 1 in that the surface of the silicon carbide has a corrosion-resistant layer. The corrosion-resistant layer is prepared by chemical vapor deposition of chromium oxide on the surface of silicon carbide at an ambient temperature of 1010°C and under the conditions of nitrogen and argon with a flow ratio of 5:1. The deposition pressure is 30 kPa and the time is 42 min. The flow rate of the nitrogen source gas is 20 L / min, thus obtaining the corrosion-resistant layer.

[0043] Example 18: This example differs from Example 17 in that the surface of the silicon carbide has a corrosion-resistant layer. The corrosion-resistant layer is prepared by chemical vapor deposition of chromium oxide on the surface of silicon carbide at an ambient temperature of 980°C and under the conditions of nitrogen and argon with a flow ratio of 3:1. The deposition pressure is 10 kPa and the time is 35 min. The flow rate of the nitrogen source gas is 15 L / min, thus obtaining the corrosion-resistant layer.

[0044] Example 19: This example differs from Example 17 in that the surface of the silicon carbide has a corrosion-resistant layer. The corrosion-resistant layer is prepared by chemical vapor deposition of chromium oxide on the surface of silicon carbide at an ambient temperature of 1050°C and under the conditions of nitrogen and argon with a flow ratio of 6:1. The deposition pressure is 50 kPa and the time is 55 min. The flow rate of the nitrogen source gas is 25 L / min, thus obtaining the corrosion-resistant layer.

[0045] Example 20: The difference between this example and Example 2 is that 70% of mullite, 80% of silicon carbide, 60% of auxiliary materials, 70% of modified phosphate tailings ceramsite, and 75% of binder are mixed together and denoted as material A. Mix 10% mullite, 5% silicon carbide, 25% auxiliary materials, 10% modified phosphorus tailings ceramsite, and 10% binder, and denote this mixture as material B.

[0046] Example 21: The difference between this example and Example 2 is that 80% of mullite, 90% of silicon carbide, 70% of auxiliary materials, 80% of modified phosphate tailings ceramsite, and 85% of binder are mixed together and denoted as material A. Mix 5% mullite, 1% silicon carbide, 15% auxiliary materials, 5% modified phosphorus tailings ceramsite, and 5% binder, and denote this mixture as material B.

[0047] Example 22: The difference between this example and Example 2 is that the pressing temperature is 80℃ and the time is 30min to obtain pre-pressed bricks; the pressing temperature is 100℃ and the time is 30min to obtain shaped bricks; and the firing temperature is 1400℃ and the time is 20h.

[0048] Example 23: The difference between this example and Example 2 is that the pressing temperature is 85℃ and the time is 35min to obtain pre-pressed bricks; the pressing temperature is 90℃ and the time is 20min to obtain shaped bricks; and the firing temperature is 1500℃ and the time is 22h.

[0049] Example 24: This example differs from Example 2 in that the pulse width is 150fs and the repetition frequency is 50kHz.

[0050] Example 25: This example differs from Example 2 in that the pulse width is 200 fs and the repetition frequency is 150 kHz.

[0051] Experimental Example: The description of this experimental example is based on the schemes described in Examples 1 to 28, and aims to illustrate the practical application effect of the present invention.

[0052] The wear resistance and high-temperature pressure resistance of the silicon carbide bricks prepared in each embodiment were tested. The average value of five test results for each embodiment was taken as the final performance test result. The specific analysis is as follows: 1. To investigate the effects of the composition and proportion of silicon carbide bricks on their wear resistance and high-temperature pressure resistance.

[0053] The difference between Comparative Example 1 and Example 1 is that no modified phosphorus tailings ceramsite was added; The difference between Comparative Example 2 and Example 1 is that no infrared shielding agent was added; The difference between Comparative Example 3 and Example 1 is that no gamma-ray irradiation was performed during the preparation of modified phosphate tailings ceramsite. Depend on Figure 1 and Figure 2 The results show that, in Comparative Example 1, the lack of modified phosphorus tailings particles improved the performance of silicon carbide bricks; in Comparative Example 2, the lack of infrared shading agent improved the thermal erosion performance of silicon carbide bricks; and in Comparative Example 3, the lack of γ-ray irradiation of the modified phosphorus tailings particles reduced the improvement in compressive strength. Therefore, compared with Examples 1 and 16, Comparative Examples 1 to 3 showed an increase in wear and a corresponding decrease in high-temperature compressive strength. Comparing Examples 1 and 3-16, it can be seen that too small or too large a proportion of modified phosphorus tailings ceramsite, too small or too large a raw material particle size, too small or too large a hydrochloric acid impregnation parameter after phosphorus tailings crushing, too small or too large an impregnation parameter of pretreated ceramsite, too fine or too coarse thorium oxide fiber, too small or too large an irradiation parameter, and too small or too large a temperature rise parameter at each stage of modified phosphorus tailings ceramsite will all increase the wear of silicon carbide bricks and reduce their high-temperature compressive strength. Therefore, in summary, the parameter effect of Example 1 is relatively better.

[0054] 2. To investigate the effect of the corrosion-resistant layer on the surface of silicon carbide on the wear resistance and high-temperature pressure resistance of silicon carbide bricks.

[0055] Depend on Figure 3 and Figure 4 The results show that after adding a corrosion-resistant layer to the silicon carbide surface in Examples 17 to 19, the wear amount of the silicon carbide brick in Example 1 was significantly reduced, and the high-temperature compressive strength was also increased. This indicates that the chromium oxide coating formed by the CVD process is chemically bonded to the silicon carbide substrate (such as Cr-O-Si bonds), and the interfacial bonding strength is improved. Moreover, this structure can prevent particle peeling during the wear process, further improving the wear resistance of the refractory brick. Comparing Examples 17 to 19, it can be seen that if the parameters of chemical vapor deposition are too small or too large, the improvement in performance will be reduced. Therefore, in summary, the parameter effect of Example 17 is relatively better.

[0056] 3. To investigate the influence of silicon carbide brick preparation methods on the wear resistance and high-temperature pressure resistance of silicon carbide bricks.

[0057] The difference between Comparative Example 4 and Example 2 is that all raw materials were mixed evenly and then pressed into shape to obtain shaped bricks; The difference between Comparative Example 5 and Example 2 is that the filling material for each row of holes is material C; The difference between Comparative Example 6 and Example 2 is that femtosecond laser processing is not performed on the surface of the molded brick; Depend on Figure 5 and Figure 6 The results show that, in Comparative Example 4, the lack of a dense surface and porous middle structure leads to a decrease in overall apparent porosity. In Comparative Example 5, the lack of differentiation between different layers of filling materials weakens the targeting of the pore areas in the upper or lower layer when the upper or lower layer is subjected to thermal shock first. In Comparative Example 6, the lack of femtosecond laser processing results in a decrease in the thermal contact area of ​​the silicon carbide brick. Therefore, compared with Examples 2 and 20-25, the wear amount is increased and the high-temperature compressive strength is correspondingly decreased. Comparing Examples 2 and 20-25, it can be seen that if the proportion of modified phosphorus tailings ceramsite in material B is too small or too large, the pressing parameters are too small, and the femtosecond laser processing parameters are too small or too large, the wear of silicon carbide bricks will increase and the high-temperature compressive strength will decrease. The wear of Example 23 is lower than that of Example 2 and the high-temperature compressive strength is improved, but the improvement in performance is less than the increase in parameters. Therefore, from an economic point of view, the parameter effect of Example 2 is relatively better.

Claims

1. A microporous silicon carbide refractory brick for use in a waste pyrolysis furnace, characterized by, By weight percentage, comprising: Mullite: 10~20%; Andalusite: 10~15%; α-Al2O3 micro powder: 3~5%; Kaolinite: 8~12%; Bauxite: 7~9%; Modified phosphorus tailings ceramsite: 4~6%; Binder: 1~3%; Infrared light shielding agent: 0.5~1%; Silicon carbide: the balance; Among them, the particle size of mullite is ≤5mm, the particle size of andalusite is ≤1mm, the particle size of α-Al2O3 micro powder is 320~360 mesh, the particle size of kaolinite is ≤0.088mm, the particle size of bauxite is ≤0.088mm, the particle size of modified phosphorus tailings ceramsite is ≤1mm, and the particle size of silicon carbide is ≤1mm.

2. A micro-porous silicon carbide refractory brick for a waste pyrolysis furnace according to claim 1, characterized in that, The preparation method of the modified phosphorus tailings ceramsite is: After crushing the phosphorus tailings, immerse them in a hydrochloric acid solution with a mass fraction of 25~28% at a solid-liquid ratio of 1g:10~15ml, filter, wash with water, and dry after 2~4h of immersion, then heat to 400~500℃ and keep for 15~20min to obtain pretreated ceramsite; Immerse the pretreated ceramsite in a trifluoropropyltrichlorosilane solution at a solid-liquid ratio of 1g:4~8ml, immerse for 1~2h, then heat to 800~900℃ and keep for 30~40min to obtain pre-solidified ceramsite; Spray thorium oxide fibers on the surface of the pre-solidified ceramsite, the length of the thorium oxide fibers is 0.2~0.3mm, the aspect ratio is 3~5:1, the spraying thickness is 0.05~0.08mm, after spraying is completed, place the ceramsite under γ-ray irradiation, the irradiation dose is 15~20kGy, the irradiation dose rate is 0.3~0.5kGy / h, the irradiation time is 1~5min, after irradiation is completed, heat to 1000~1200℃ and keep for 15~20min to obtain modified phosphorus tailings ceramsite.

3. A micro-porous silicon carbide refractory brick for a waste pyrolysis furnace according to claim 1, wherein The mullite with a particle size of ≤5mm is composed of mullite with a particle size of ≤1mm, 1~3mm and 3~5mm at a mass ratio of 1:0.8:0.5~0.

8.

4. A micro-porous silicon carbide refractory brick for a waste pyrolysis furnace according to claim 1, wherein The silicon carbide with a particle size of ≤1mm is composed of silicon carbide particles with a particle size of ≤0.088mm and 0.088~1mm at a mass ratio of 1~1.2:

1.

5. A micro-porous silicon carbide refractory brick for a waste pyrolysis furnace according to claim 1, wherein The surface of the silicon carbide has a corrosion-resistant layer, and the preparation method of the corrosion-resistant layer is: chemical vapor deposition of chromium oxide on the surface of the silicon carbide at an ambient temperature of 980~1050℃, a flow ratio of nitrogen and argon of 3~6:1, a deposition pressure of 10~50kPa, a time of 35~55min, and a flow rate of the nitrogen source gas of 15~25L / min to obtain the corrosion-resistant layer.

6. A micro-porous silicon carbide refractory brick for a waste pyrolysis furnace according to claim 1, wherein The binder is aluminum dihydrogen phosphate.

7. A micro-porous silicon carbide refractory brick for a waste pyrolysis furnace according to claim 1, wherein the micro-porous silicon carbide refractory brick is used for a waste pyrolysis furnace. The infrared light shielding agent is ZS1061 or ZS811.

8. The method for preparing the micro-porous SiSiC wear-resistant brick for the waste high-temperature pyrolysis furnace according to any one of claims 1-7, characterized in that, The method comprises the following steps: S1, mix andalusite, α-Al2O3 micro powder, kaolinite, and bauxite, denoted as auxiliary materials; Mix 70~80% of mullite, 80~90% of silicon carbide, 60~70% of auxiliary materials, 70~80% of modified phosphorus tailings ceramsite, and 75~85% of binder, denoted as material A; Mixing 5-10% of mullite, 1-5% of silicon carbide, 15-25% of auxiliary materials, 5-10% of modified phosphorite ceramsite and 5-10% of binder, denoted as material B; Mixing the remaining raw materials, denoted as material C; S2, pre-pressing material A, the pressing temperature is 80-85℃, the time is 30-35min, obtaining pre-pressed brick; S3, opening holes in the pre-pressed brick, obtaining upper layer holes, middle-upper layer holes, middle-lower layer holes and lower layer holes, the interval between each layer of holes is equal, the diameter of holes in the same layer is the same and is equally spaced, then filling material B into the upper layer holes and the lower layer holes, filling material C into the middle-upper layer holes and the middle-lower layer holes, then pressing, the pressing temperature is 90-100℃, the time is 20-30min, obtaining formed brick; S4, firing the formed brick, the firing temperature is 1400-1500℃, the time is 20-22h, obtaining silicon carbide brick.

9. The method for preparing a microporous silicon carbide wear-resistant brick for a waste high-temperature pyrolysis furnace as described in claim 8, characterized in that, In step S4, first, the surface of the formed brick is processed by femtosecond laser, the wavelength of the femtosecond laser is 1030nm, the pulse width is 150-200fs, the repetition frequency is 50-150kHz, the spot diameter is 35μm, and the time is <1s.

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