Modified glass fiber reinforced corundum-mullite castable and preparation method thereof

Abstract

The application discloses a modified glass fiber reinforced corundum-mullite castable and a preparation method thereof, and belongs to the technical field of amorphous refractory materials. The castable comprises the following components: 38-48% of dense corundum particles, 20-30% of mullite particles, 16-20% of dense corundum powder, 2-5% of silica powder, 5-10% of active alumina powder, 1-3% of composite additives, 0.05-0.15% of water reducing agent, 0.2-0.6% of modified glass fiber and 7.5-8.5% of additional silica sol. The modified glass fiber is prepared by the following steps: high-temperature calcination of glass fiber at a temperature of 350-400 DEG C, then immersion in a solution containing a silane coupling agent under stirring, and then ultrasonic treatment. The obtained castable has high low-temperature strength, meanwhile, the high-temperature performance of the castable is improved, and the large-scale industrial application of the silica sol combined corundum-mullite castable is facilitated.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of amorphous refractory, and particularly relates to a modified glass fiber reinforced corundum-mullite castable and a preparation method thereof. BACKGROUND

[0002] The smelting environment of high temperature and high pressure inside the blast furnace brings severe challenges to the safety and long service life of the blast furnace. The lining materials of blast furnace, hot blast furnace and other furnaces are usually integrally constructed by high alumina castable. However, during the operation of the equipment, the organizational structure of the lining in the furnace is easily damaged due to the long-time severe mechanical scouring of high-temperature slag liquid and the erosion of various dust and smoke, thereby causing the lining material to deform, such as cracks, bulges and even large-scale shedding and collapse, which seriously threatens the safety of people's life and property.

[0003] Corundum-mullite castable has excellent properties such as high high-temperature strength, good heat shock resistance, good structure spalling, good heat shock resistance, high load softening temperature, low high-temperature creep rate and good chemical corrosion resistance, and is widely used in the lining of blast furnaces, hot blast furnaces and other furnaces. The binder of corundum-mullite castable on the market is mainly aluminate cement, which has the advantages of high early strength and rheological properties. However, the low high-temperature strength and long construction period limit the large-scale use of aluminate cement combined with mullite-corundum castable. In recent years, with the continuous application and development of nanotechnology in the metallurgical industry, silica sol as a castable binder has become one of the research hotspots at home and abroad. For example, Xiong Jiqian et al. studied the properties and application of silica sol combined with corundum-silicon carbide castable, and the results showed that the castable had high high-temperature strength, good slag erosion resistance, good thermal shock stability and fast baking property (Bulletin of the Ceramic Society, 2013, Vol. 32, No. 8, 1688-1692); Wang Xitang et al. studied the rheological properties of silica sol combined with corundum refractory castable, and the results showed that the type of Al2O3 micro powder affected the stability of the slurry, the castable had good fluidity, and the high-temperature bending strength was higher than that of cement combined with corundum castable (Rare Metal Materials and Engineering, 2009, Vol. 38, Supplement 2); Xu Yong et al. summarized the performance research and application status of silica sol combined with amorphous refractory, and the silica sol combined refractory had many excellent properties due to the presence of nano-SiO2, such as good medium and high temperature strength, good slag erosion resistance and good thermal shock resistance, which could be quickly dried and baked, saving time for normal production, energy saving and environmental protection (Refractory, 2014, Vol. 48, No. 5, 391-396). Compared with aluminate cement, the introduction of CaO in the system is avoided when silica sol is used as the binder, and the castable has high early strength, high high-temperature strength, good rheological properties, good slag erosion resistance and good thermal shock resistance, which can be quickly dried and baked, saving time for normal production, energy saving and environmental protection. 2+,can avoid the formation of low melting point substances such as anorthite, calcium aluminum yellow longite, tricalcium aluminate at high temperature, significantly enhance the high temperature strength and corrosion resistance, at the same time, the use of silica sol does not produce hydration product, less crystallization water, the castable can be fast construction and baking, greatly shorten the construction cycle and so on. However, there is a major problem of silica sol combined castable that its strength is very low at low temperature, because the low temperature strength of castable is mainly provided by the condensation reaction of a small amount of silanol group (-Si-OH), in this reaction, only the recombination of molecular bond between silica sol particles, and then form a siloxane space network structure, and only rely on the condensation reaction of -Si-OH spontaneous, the degree of condensation reaction is low, the binding force is weak, so that the particles can not be closely bonded, therefore, the low temperature strength of silica sol combined castable is low, which also seriously limits the large-scale popularization and application of silica sol combined refractory castable. SUMMARY

[0004] The purpose of the present application is to overcome the shortcomings of the prior art, provide a modified glass fiber reinforced corundum-mullite castable and a preparation method thereof, the obtained corundum-mullite castable has high low temperature strength, overcomes the low low temperature strength of silica sol combined corundum-mullite, improves the high temperature performance, and is beneficial to the large-scale industrial application of silica sol combined corundum-mullite castable.

[0005] In order to solve the above technical problems, the technical scheme adopted by the present application is as follows:

[0006] Provided is a modified glass fiber reinforced silica sol combined corundum-mullite castable, the raw materials include, by mass percentage: dense corundum particles 38-48%, mullite particles 20-30%, dense corundum powder 16-20%, silicon powder 2-5%, active alumina powder 5-10%, composite additive 1-3%, water reducing agent 0.05-0.15%, modified glass fiber 0.2-0.6%, and additional silica sol 7.5-8.5%; wherein:

[0007] The modified glass fiber is prepared by high-temperature calcination of glass fiber at 350-400 DEG C, then soaking in a solution containing silane coupling agent under stirring, and then ultrasonic treatment.

[0008] According to the above scheme, the high-temperature calcination time is 1.5-3h; the soaking time is 0.5-1h; and the ultrasonic treatment time is 1-3h.

[0009] According to the above scheme, the length of the glass fiber is 3-6mm, and the diameter is 0.05-0.1mm.

[0010] According to the above scheme, the silane coupling agent is one of KH-570, KH-560 and KH-550.

[0011] According to the above scheme, the mass percentage of the silane coupling agent in the solution is 10-20%.

[0012] According to the above scheme, the dense corundum particles are mixed by three kinds of dense corundum particles with particle sizes of 5-3mm, 3-1mm and 1-0mm in a mass ratio of 1:(2.5-3.5):(2.5-3); and the Al2O3 content is ≥98%.

[0013] According to the above scheme, the dense corundum particles are mixed by three kinds of dense corundum particles with particle sizes of 5-3mm, 3-1mm and 1-0mm in a mass ratio of 1:(2.5-3.5):(2.5-3); and the Al2O3 content is ≥98%.

[0014] According to the above scheme, the SiO2 content in the silicon powder is ≥96%, and the particle size is ≤5μm.

[0015] According to the above scheme, the Al2O3 content in the active alumina powder is ≥98%, and the particle size is ≤1.5μm.

[0016] According to the above scheme, the composite additive is a mixture of magnesium oxide and boron carbide; preferably, the mass ratio of magnesium oxide to boron carbide is 1:(1.5-3).

[0017] According to the above scheme, the particle size of the composite additive is ≤0.088mm.

[0018] According to the above scheme, the water reducing agent is one or more of sodium hexametaphosphate, sodium pyrophosphate and sodium tripolyphosphate; preferably, the particle size of the water reducing agent is ≤0.074mm.

[0019] According to the above scheme, the mass fraction of SiO2 in the silica sol is 20-35%, and the particle size is 5-30nm.

[0020] A preparation method of a modified glass fiber reinforced silica sol combined corundum-mullite castable is provided, comprising the following steps:

[0021] The weighed dense corundum particles, mullite particles, dense corundum powder, silicon powder, active alumina powder, composite additive, water reducing agent and modified glass fiber are mechanically stirred and mixed into dry uniform aggregate, then the silica sol is added, and after being fully mixed and stirred uniformly, the pouring construction can be carried out.

[0022] The present application provides a modified glass fiber reinforced silica sol combined corundum-mullite castable, in which the modified glass fiber is matched with the silicon powder, the active alumina powder, the composite additive and the water reducing agent, so as to effectively improve the low-temperature strength of the silica sol combined corundum-mullite castable, and simultaneously improve the high-temperature strength and wear resistance; and the specific embodiments are as follows:

[0023] The modified glass fiber is modified by sintering the glass fiber and silane coupling agent grafting modification, so that the surface is rougher and contains a large amount of -OH; on the one hand, the modified glass fiber is added into the silica sol combined castable, the rough surface increases the interfacial friction, improves the adhesion between the fiber and the powder, and forms a stress skeleton, strengthens the connection between the refractory powder and the silica sol, when the castable is subjected to external stress, the modified fiber can effectively share part of the load and prevent the crack from further expanding, the material fracture path is lengthened, so that the low temperature strength is improved; on the other hand, the modified glass fiber is modified by the silane coupling agent, is physically adsorbed on the surface of the glass fiber and is chemically grafted with the glass fiber, the surface of the modified glass fiber has a large number of active -OH, and the dehydration condensation reaction (Si-OH + HO-R- = -Si-O-R- + H2O) occurs between the Si-OH in the silica sol, so that the silica sol forms a three-dimensional network structure, and the low temperature strength of the castable is significantly improved.

[0024] At the same time, the modified glass fiber is more closely bonded with the powder due to the rough surface, on the one hand, the porosity of the castable is reduced, when high-temperature sintering, the sintering degree between the particles of the castable is higher, and the high-temperature performance is better. On the other hand, the main component of the glass fiber is SiO2, the close combination of the modified glass fiber and the powder is also more conducive to the generation of needle-like or prismatic mullite phase from the SiO2 of the glass fiber and Al2O3 in the raw material at high temperature, the mullite phases interpenetrate and interleave, thereby significantly improving the high-temperature strength and wear resistance of the castable. In addition, the liquid phase formed by the small amount of Na in the modified glass fiber promotes the filling of particles to the voids, which is beneficial to promote the sintering between the particles, improves the packing degree of the castable, and significantly improves the high-temperature strength and wear resistance of the castable.

[0025] The beneficial effects of the present application are as follows:

[0026] 1. The present application provides a modified glass fiber reinforced silica sol combined corundum-mullite castable, the surface of the modified glass fiber is rough and contains a large amount of -OH, which is added into the silica sol combined corundum-mullite castable, can not only serve as a stress skeleton to improve the adhesion with the powder and the silica sol, and exhibit obvious physical enhancement, but also can react with the silica sol to form a three-dimensional network structure to exhibit chemical enhancement, the physical and chemical dual enhancement significantly improves the low temperature strength of the castable; at the same time, the glass fiber has good combination with the powder after modification, reduces the porosity, and is conducive to the generation of mullite phase, thereby improving the high-temperature strength and wear resistance of the castable; the present application effectively improves the low temperature strength, high temperature strength, porosity and wear resistance of the silica sol combined corundum-mullite castable by using a small amount of modified glass fiber in combination with silica powder, active alumina powder, composite additive and water reducing agent, and the price is low, basically no impurities are introduced, and has important application potential.

[0027] 2. The mullite-corundum castable of the present application has simple and effective preparation process, low equipment requirement, and can be produced on a large scale. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical scheme and advantages of the present application more clear, the present application is further described in detail below with examples. It should be understood that the specific examples described herein are only used to explain the present application, and are not used to limit the present application.

[0029] The specific indexes of raw materials in the embodiment of the present application are as follows:

[0030] The dense corundum particles are mixed by three kinds of dense corundum particles with particle size of 5-3mm, 3-1mm and 1-0mm in a mass ratio of 1:(2.5-3.5):(2.5-3); wherein the content of Al2O3 is ≥98%.

[0031] The mullite particles are mixed by three kinds of mullite particles with particle size of 5-3mm, 3-1mm and 1-0mm in a mass ratio of 1:(2.5-3.5):(2.5-3); wherein the content of Al2O3 is ≥60%.

[0032] The SiO2 content in the silicon micropowder is ≥96%, and the particle size is ≤5μm.

[0033] The content of Al2O3 in the active alumina powder is ≥98%, and the particle size is ≤1.5μm.

[0034] The composite additive is a mixture of magnesium oxide and boron carbide with a mass ratio of 1:2, and the particle size is ≤0.088mm.

[0035] The water reducing agent is sodium hexametaphosphate, and the particle size of the water reducing agent is ≤0.074mm.

[0036] The mass fraction of SiO2 in the silicon sol is 20-35%, and the particle size is 5-30nm.

[0037] The modified glass fiber is prepared by the following steps: high-temperature calcination of glass fiber at a temperature of 350-400℃, then mixing with a solution containing silane coupling agent, and then ultrasonic treatment; wherein:

[0038] The length of the glass fiber is 3-6mm, and the diameter is 0.05-0.1mm.

[0039] The silane coupling agent is one of KH-570, KH-560 and KH-550.

[0040] The mass percentage content of the silane coupling agent in the solution containing silane coupling agent is 10-20%.

[0041] The castable in the embodiment is prepared by the following method:

[0042] The weighed dense corundum particles, mullite particles, dense corundum powder, silicon powder, active alumina powder, composite additive, water reducing agent and modified glass fiber are mechanically stirred and mixed into dry uniform aggregate, then the silica sol is added by external addition, and the mixture is fully mixed and stirred uniformly before pouring construction.

[0043] Example 1

[0044] A modified glass fiber reinforced corundum-mullite castable is provided, and the components and their mass percentages are as follows:

[0045] Dense corundum particles 40%, mullite particles 25%, dense corundum powder 19%, silicon powder 4%, active alumina powder 10%, composite additive 1.53%, sodium hexametaphosphate 0.07%, modified glass fiber 0.4%, and additional silica sol 7.8%.

[0046] The modified glass fiber is prepared by placing the glass fiber in a muffle furnace at 400°C for 2h, then soaking the calcined glass fiber in a 15% KH-570 solution for about 30 minutes, continuously stirring the solution to mix uniformly, ultrasonic treatment for 2h at room temperature, removing the filtrate, washing with ethanol for 3 times, and drying in an oven at 110°C.

[0047] According to the above formula, the castable is packaged into two components (powder and silica sol) and transported to the construction site, the powder and silica sol are mixed and stirred uniformly according to the proportion, and the corundum-mullite castable is obtained, which can be applied to the furnace lining pouring construction of blast furnace and hot blast furnace.

[0048] The performance test results of the corundum-mullite castable obtained in this embodiment are shown in Table 1.

[0049] Comparative Example 1

[0050] The corundum-mullite castable is prepared according to the preparation method of Example 1 without adding modified glass fiber, and the components and their mass percentages are as follows: dense corundum particles 40%, mullite particles 25%, dense corundum powder 19.4%, silicon powder 4%, active alumina powder 10%, composite additive 1.53%, sodium hexametaphosphate 0.07%, and additional silica sol 7.8%.

[0051] The performance test results of the corundum-mullite castable obtained in this comparative example are shown in Table 1.

[0052] Example 2

[0053] The modified glass fiber reinforced corundum-mullite castable has the following components and mass percentages: dense corundum particles 38%, mullite particles 28%, dense corundum powder 19%, silicon micro powder 4%, active alumina powder 9%, composite additive 1.73%, sodium hexametaphosphate 0.07%, modified glass fiber 0.2%, and additional silica sol 8%. The modified glass fiber is prepared by the following method: the glass fiber is placed in a muffle furnace and burned at a high temperature of 400 DEG C for 2 hours, then the burned glass fiber is soaked in KH-570 with a mass fraction of 15% for about 30 minutes, the solution is continuously stirred to uniformly mix, ultrasonic treatment is performed at room temperature for 2 hours, the filtrate is removed, the glass fiber is washed with ethanol for 3 times, and then the glass fiber is dried in an oven at 110 DEG C.

[0054] The performance test results of the mullite castable prepared in the example are shown in Table 1.

[0055] Comparative Example 2

[0056] The corundum-mullite castable prepared according to the preparation method of Example 2 without adding modified glass fiber has the following components and mass percentages: dense corundum particles 38%, mullite particles 28%, dense corundum powder 19.2%, silicon micro powder 4%, active alumina powder 9%, composite additive 1.73%, sodium hexametaphosphate 0.07%, and additional silica sol 8%.

[0057] The performance test results of the corundum-mullite castable obtained in the comparative example are shown in Table 1.

[0058] Example 3

[0059] The modified glass fiber reinforced corundum-mullite castable has the following components and mass percentages: dense corundum particles 45%, mullite particles 25%, dense corundum powder 16%, silicon micro powder 3%, active alumina powder 8%, composite additive 2.3%, sodium hexametaphosphate 0.1%, modified glass fiber 0.6%, and additional silica sol 8.1%. The modified glass fiber is prepared by the following method: the glass fiber is placed in a muffle furnace and burned at a high temperature of 400 DEG C, then the burned glass fiber is soaked in KH-560 with a mass fraction of 15% for about 30 minutes, the solution is continuously stirred to uniformly mix, ultrasonic treatment is performed at room temperature for 2 hours, the filtrate is removed, the glass fiber is washed with ethanol for 3 times, and then the glass fiber is dried in an oven at 110 DEG C.

[0060] The performance test results of the mullite castable prepared in the example are shown in Table 1.

[0061] Comparative Example 3

[0062] The glass fiber was not modified and directly added to the corundum-mullite castable according to the preparation method of Example 3. The components and their mass percentages are as follows: dense corundum particles 45%, mullite particles 25%, dense corundum powder 16%, silicon micro powder 3%, active alumina powder 8%, composite additive 2.3%, sodium hexametaphosphate 0.1%, glass fiber 0.6%, and additional silica sol 8.1%.

[0063] The performance test results of the corundum-mullite castable obtained in the present comparative example are shown in Table 1.

[0064] Comparative Example 4

[0065] The modified glass fiber reinforced corundum-mullite castable has the following components and their mass percentages: dense corundum particles 45%, mullite particles 25%, dense corundum powder 15.8%, silicon micro powder 3%, active alumina powder 8%, composite additive 2.3%, sodium hexametaphosphate 0.1%, modified glass fiber 0.8%, and additional silica sol 8.1%. The preparation method of the modified glass fiber is as follows: the glass fiber is placed in a muffle furnace and burned at a high temperature of 400°C for 2h, then the burned glass fiber is soaked in KH-560 with a mass fraction of 15% for about 30 minutes, the solution is continuously stirred to make it uniformly mixed, ultrasonic treatment is performed at room temperature for 2h, the filtrate is removed, washed with ethanol for 3 times, and dried in an oven at 110°C for use.

[0066] The performance test results of the corundum-mullite castable obtained in the present comparative example are shown in Table 1.

[0067] Comparative Example 5

[0068] The modified glass fiber reinforced corundum-mullite castable has the following components and their mass percentages: dense corundum particles 45%, mullite particles 25%, dense corundum powder 16.5%, silicon micro powder 3%, active alumina powder 8%, composite additive 2.3%, sodium hexametaphosphate 0.1%, modified glass fiber 0.1%, and additional silica sol 8.1%. The preparation method of the modified glass fiber is as follows: the glass fiber is placed in a muffle furnace and burned at a high temperature of 400°C for 2h, then the burned glass fiber is soaked in KH-560 with a mass fraction of 15% for about 30 minutes, the solution is continuously stirred to make it uniformly mixed, ultrasonic treatment is performed at room temperature for 2h, the filtrate is removed, washed with ethanol for 3 times, and dried in an oven at 110°C for use.

[0069] The performance test results of the corundum-mullite castable obtained in the present comparative example are shown in Table 1.

[0070] Table 1. Performance test results of Examples 1-3 and Comparative Examples 1-5

[0071]

[0072] As can be seen from the data of Example 1 and Comparative Example 1, Example 2 and Comparative Example 2 in Table 1, the bending and compressive strength of the corundum-mullite castable of the present application with modified glass fiber at low, medium and high temperature is significantly higher than that of the corundum-mullite castable without modified glass fiber, especially after drying at 110℃, the bending and compressive strength of the castable without modified glass fiber is only about 5MPa and 22MPa, while the bending and compressive strength of the castable with modified glass fiber is significantly enhanced, especially after curing at 110℃, the bending and compressive strength is more than 9MPa and 30MPa respectively, which is mainly because the addition of modified glass fiber, after modification, the surface of the glass fiber is rougher, the interfacial friction is increased, the adhesion between the fiber and the powder is improved, and a stress skeleton is formed, which strengthens the connection between the refractory powder and the silica sol, when the castable is subjected to external stress, the modified fiber can effectively share part of the load and prevent the crack from further expanding, the material fracture path is lengthened, so that the strength is improved. On the other hand, through modification by silane coupling agent, physical adsorption on the surface of glass fiber and chemical grafting with glass fiber, the surface of the modified glass fiber has a large number of active -OH, which dehydrates and condenses with -Si-OH in the silica sol, further accelerating the formation of three-dimensional network structure of silica sol, so that the low temperature strength of the castable is significantly improved. In addition, due to the rough surface of the modified glass fiber, the bonding force between the particles of the castable is increased, so the porosity of the castable with modified glass fiber is significantly lower than that of the castable without modified glass fiber. At the same time, after heat treatment of the corundum-mullite castable with modified glass fiber, because the main component of the modified glass fiber is SiO2, it is easy to form needle-like or prismatic mullite phase with Al2O3 in the raw material at high temperature, the mullite phases penetrate each other, which improves the high temperature strength of the castable, and the linear change rate after firing shows that the castable shrinks less and the volume is more stable. In addition, the liquid phase formed by a small amount of Na in the modified glass fiber promotes the filling of particles to the void, which is beneficial to promote the sintering between particles and improve the packing degree of the castable, so the high temperature strength of the castable is significantly improved.

[0073] Comparing Example 3 with Comparative Examples 3-5, it can be seen that the flexural and compressive strengths of the corundum-mullite castable with the addition of modified glass fiber at low, medium and high temperatures are significantly higher than those of the corundum-mullite castable with the addition of unmodified glass fiber. This is mainly because the unmodified glass fiber has only a partial physical reinforcement effect. Although it can share part of the load of the castable, there is a bundle agent on the surface of the fiber, the surface is relatively smooth, and the bonding force with the powder in the castable is slightly poor. The addition of modified glass fiber can not only effectively share part of the load of the castable, but also has a rough surface and a large amount of active -OH, which undergoes a dehydration condensation reaction with the -Si-OH in the silica sol, further accelerating the formation of a three-dimensional network structure of the silica sol. Therefore, the strength is significantly higher than that of the corundum-mullite castable with the addition of unmodified glass fiber. Comparing Example 3 with Comparative Examples 4 and 5, it can be seen that adding too much modified glass fiber will cause partial entanglement and agglomeration of the fibers in the castable, affecting the bonding between the fibers, the powder, and the sol, resulting in a decrease in strength. Adding too little modified glass fiber will not fully exert the reinforcing effect of the modified glass fiber, resulting in a general strengthening effect. Therefore, adding an appropriate amount of modified glass fiber to the corundum-mullite castable has a significant positive effect on improving the strength of the corundum-mullite castable.

[0074] In summary, the present invention adds modified glass fiber to corundum-mullite castable, and the low-temperature strength of corundum-mullite castable is significantly improved compared to the castable without modified glass fiber, and its high-temperature performance is improved at the same time, and the problem of low strength of silica sol combined with corundum-mullite castable at low temperature is effectively solved, which is conducive to the further promotion and application of silica sol combined with corundum-mullite castable. At the same time, the modified glass fiber added to mullite-corundum castable is relatively small, low in price, substantially free of impurities, and can directly react with raw materials at high temperature, and the castable has stable low-temperature and high-temperature performance. In addition, the preparation process of mullite-corundum castable of the present invention is simple and effective, has low equipment requirements, can be produced on a large scale industrially, and has good economic benefits and broad development prospects.

[0075] It should be understood that those skilled in the art can make improvements or changes based on the above description, and all such improvements and changes should fall within the scope of protection of the appended claims of the present invention.

Claims

1. A modified glass fiber reinforced silica sol bonded corundum-mullite castable characterized in that, The raw materials include, by mass percentage, dense corundum particles 38-48%, mullite particles 20-30%, dense corundum powder 16-20%, silicon micro powder 2-5%, active alumina powder 5-10%, composite additive 1-3%, water reducing agent 0.05-0.15%, modified glass fiber 0.2-0.6%, and additional silica sol 7.5-8.5%; wherein: The modified glass fiber is prepared by high-temperature calcination of glass fiber at 350-400 ℃, then soaking in a solution containing silane coupling agent with stirring, and then ultrasonic treatment.

2. The silica sol bonded corundum-mullite castable according to claim 1, characterized in that, The high-temperature calcination time is 1.5-3 h; the soaking time is 0.5-1 h; and the ultrasonic treatment time is 1-3 h.

3. The silica sol bonded corundum-mullite castable according to claim 1, characterized in that, The length of the glass fiber is 3-6 mm, and the diameter is 0.05-0.1 mm.

4. The silica sol bonded corundum-mullite castable according to claim 1, characterized in that, The silane coupling agent is one of KH-570, KH-560, and KH-550.

5. The silica sol bonded corundum-mullite castable according to claim 1, characterized in that, The mass percentage of silane coupling agent in the solution containing silane coupling agent is 10-20%.

6. The silica sol bonded corundum-mullite castable according to claim 1, characterized in that, The dense corundum particles are prepared by mixing three kinds of dense corundum particles with particle sizes of 5-3 mm, 3-1 mm, and 1-0 mm at a mass ratio of 1:(2.5-3.5):(2.5-3); wherein the Al2O3 content is ≥98%; the mullite particles are prepared by mixing three kinds of mullite particles with particle sizes of 5-3 mm, 3-1 mm, and 1-0 mm at a mass ratio of 1:(2.5-3.5):(2.5-3); wherein the Al2O3 content is ≥ 65% and the SiO2 content is ≥ 25%. ≥60％。 7. The silica sol bonded corundum-mullite castable according to claim 1, characterized in that, The SiO2 content in the silicon micro powder is ≥96%, and the particle size is ≤5 μm; the Al2O3 content in the active alumina powder is ≥98%, and the particle size is ≤1.5 μm; and the SiO2 mass fraction in the silica sol is 20-35%, and the micro-particle size is 5-30 nm.

8. The silica sol bonded corundum-mullite castable according to claim 1, characterized in that, The composite additive is a mixture of magnesium oxide and boron carbide.

9. The silica sol bonded corundum-mullite castable according to claim 1, characterized in that, The water reducing agent is one or more of sodium hexametaphosphate, sodium pyrophosphate, and sodium tripolyphosphate.

10. A method for producing a silica sol-bonded corundum-mullite castable according to claim 1, characterized in that, The method comprises the following steps: The weighed dense corundum particles, mullite particles, dense corundum powder, silicon micro powder, active alumina powder, composite additive, water reducing agent, and modified glass fiber are mechanically stirred and mixed into dry uniform aggregate, then the silica sol is added, and the mixture is fully mixed and stirred uniformly before pouring construction.

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