Secondary aluminum ash-based silicon-aluminum series refractory mortar and preparation method thereof

Abstract

The invention relates to the technical field of slurry, and particularly discloses secondary aluminum ash-based silicon-aluminum series refractory slurry and a preparation method thereof. The invention discloses secondary aluminum ash-based silicon-aluminum series refractory mortar. The raw materials of the mortar comprise an aluminum ash material and a modified water glass binding agent, the modified water glass binding agent accounts for 10-15% of the weight of the slurry; the raw materials of the aluminum ash material comprise the following components in parts by weight: 10-30 parts of low-aluminum mullite, 30-50 parts of calcined secondary aluminum ash, 5-15 parts of secondary aluminum ash, 5-15 parts of silica powder, 3-8 parts of a composite additive, 0-5 parts of potassium feldspar powder and 1-5 parts of bentonite. The refractory mortar provided by the invention has excellent high temperature resistance, thermal shock resistance stability and thermal insulation performance.

Description

Technical Field

[0001] The present application relates to the technical field of mud, and particularly to a secondary aluminum ash-based silicon-aluminum refractory mud and a preparation method thereof. Background Art

[0002] As a jointing material required for masonry of shaped refractory products, refractory mud is required to have comprehensive properties such as being able to harden at room temperature, having high bond strength, and being easy to sinter. According to different usage scenarios, it can be divided into silica-based, alumina-silica-based, silicon carbide-based, and basic refractory muds, etc. Among them, alumina-silica refractory mud has a wide range of applications and can be used to masonry high-aluminum bricks, anchor bricks, mullite bricks, clay bricks, etc., and is thus commonly used in different scenarios such as glass kilns, cement kilns, and non-ferrous metal smelting reverberatory furnaces.

[0003] During the melting and casting process of aluminum and recycled aluminum, floating aluminum slag is formed due to oxidation, also known as primary aluminum ash. Primary aluminum ash contains a large amount of metallic aluminum. After recycling and treatment, the remaining aluminum ash usually contains 15-30% metallic aluminum, but the quality of aluminum is low, and generally, aluminum is not further extracted and is discarded, which is called secondary aluminum ash. Due to the presence of heavy metal elements and impurities such as AlN in the composition of secondary aluminum ash, it pollutes the atmosphere and soil and is an industrial hazardous waste. However, secondary aluminum ash contains a large amount of alumina with economic value and is a renewable resource.

[0004] Calcined secondary aluminum ash is a material obtained by converting secondary aluminum ash into a material mainly composed of alumina through pyrometallurgical calcination, also known as harmless secondary aluminum ash. It has characteristics such as high alumina content, irregular microstructure, and large surface activity, making it have certain corrosion resistance, thermal shock resistance, thermal stability, and high-temperature resistance. However, due to the use of refining agents such as KCL and NaCL in the aluminum refining process, a considerable amount of alkali metal oxides such as K2O and Na2O are contained in secondary aluminum ash, which limits its application scenarios and also affects the performance of the obtained refractory mud. Summary of the Invention

[0005] In order to improve the performance of refractory mud, the present application provides a secondary aluminum ash-based silicon-aluminum refractory mud and a preparation method thereof.

[0006] In a first aspect, a secondary aluminum ash-based silicon-aluminum refractory mud provided by the present application adopts the following technical solution: A secondary aluminum ash-based silicon-aluminum refractory mud, the raw materials of the mud include aluminum ash material and a modified sodium silicate binder; the modified sodium silicate binder accounts for 10-15% by weight of the mud; the raw materials of the aluminum ash material include the following components in parts by weight: 10-30 parts of low-aluminum mullite, 30-50 parts of calcined secondary aluminum ash, 5-15 parts of secondary aluminum ash, 5-15 parts of silica fume, 3-8 parts of a composite additive, 0-5 parts of potassium feldspar powder, and 1-5 parts of bentonite.

[0007] By adopting the above technical solutions, using calcined secondary aluminum ash and secondary aluminum ash as the core aluminum sources, silica fume as the silicon source, and under a reasonable silicon-aluminum ratio, the formation of cristobalite phase can be avoided. The reaction product is mainly composed of mullite phase as the main crystal phase. As the only high-temperature stable phase in the Al-Si binary system, mullite phase has excellent high-temperature resistance and thermal shock stability. There are active metal Al and aluminum nitride in the secondary aluminum ash. During the high-temperature process, within 500 °C, metal Al and aluminum nitride AlN react with water, and the generated gas overflows from the fireclay, forming micropores and optimizing the pore structure. On the one hand, it can improve the ability of the fireclay to resist thermal shock and thermal stress of thermal cycling. On the other hand, the micropores generated by the reaction can significantly improve the heat insulation performance of the material. In addition, the aluminum hydroxide generated by the reaction decomposes when heated, and the generated alumina has high reaction activity and reacts with silica fume to form mullite phase at about 1000 °C, improving the thermal shock resistance of the material. Moreover, the generated water vapor is discharged to generate pores, further improving the heat insulation performance of the material. The highly active alkali metal oxides potassium oxide and sodium oxide in the calcined secondary aluminum ash, together with the introduced potassium feldspar powder, serve as low-temperature sintering agents. By adjusting the introduction amount of the sintering agent, the sintering temperature of the fireclay is reduced, and the sintering between the material and the brick is accelerated, thereby enhancing the interfacial bonding strength. Therefore, the obtained refractory mortar has excellent high-temperature resistance, thermal shock stability and adiabatic heat preservation performance.

[0008] In a specific feasible embodiment, the particle size of the low-aluminum mullite is 50 mesh, and the content of aluminum oxide in the low-aluminum mullite is greater than 45%, the content of iron oxide is less than or equal to 1.5%, and it is composed of mullite phase and amorphous glass phase.

[0009] In a specific feasible embodiment, the particle size of the calcined secondary aluminum ash is 200 mesh, and the mass percentages of each component in the composition of the calcined secondary aluminum ash are as follows: Al2O3 is 60 - 80%, SiO2 is 5 - 15%, Fe2O3 is 0.5 - 3%, CaO is 0.5 - 3%, K2O is 1 - 5%, Na2O is 0.5 - 3%, and MgO is 0.5 - 2%.

[0010] In a specific feasible embodiment, the particle size of the secondary aluminum ash is 200 mesh, and the mass percentages of each component in the composition of the secondary aluminum ash are as follows: Al is 10 - 20%, AlN is 5 - 15%, Al2O3 is 30 - 50%, KCl is 5 - 10%, and NaCl is 3 - 8%.

[0011] In a specific feasible embodiment, the content of SiO2 in the silica fume is > 95%, the particle size D50 < 0.5 μm, and the specific surface area > 20 m 2 / g.

[0012] In a specific feasible implementation, the particle size of the potassium feldspar powder is 325 mesh, and the content of K2O in the potassium feldspar powder is > 10%, and the content of SiO2 is 55 - 70%.

[0013] In a specific feasible implementation, the particle size of the composite additive is 325 mesh, and the composite additive includes a mixture composed of one or more of cyanite, andalusite, calcium silicate, and fine calcium carbonate powder.

[0014] By adopting the above technical solution, the thermal expansion characteristics of cyanite and andalusite offset the volume shrinkage during the sintering process of the fire clay, maintaining the overall structural stability of the wall; utilizing the decomposition characteristics of calcium carbonate at about 800 °C, and cooperating with the thermal decomposition of calcined secondary aluminum ash to continuously generate micropores in different temperature ranges, the micropore distribution of the material is adjusted.

[0015] In a specific feasible implementation, the particle size of the bentonite is 325 mesh, and the content of montmorillonite in the bentonite is ≥ 75%, and the total content of alumina, potassium oxide, and sodium oxide is ≤ 3%.

[0016] In a specific feasible implementation, the modified sodium silicate binder includes a mixture composed of sodium silicate with a modulus of 2.8 - 3.2 and nano-silica, and the mass fraction of nano-silica in the modified sodium silicate binder is 3 - 5%.

[0017] By adopting the above technical solution, adding nano-silica to sodium silicate can improve the bonding strength of the binder.

[0018] In the second aspect, a preparation method of a secondary aluminum ash-based silicon-aluminum refractory mortar provided by the present application adopts the following technical solution: A preparation method of a secondary aluminum ash-based silicon-aluminum refractory mortar includes the following steps: Pretreatment of secondary aluminum ash: adding secondary aluminum ash to water for washing, then separating, drying, and ball milling to obtain pretreated secondary aluminum ash; Mixing materials: uniformly stirring and mixing low-aluminum mullite, calcined secondary aluminum ash, pretreated secondary aluminum ash, silica fume, potassium feldspar powder, composite additive, and bentonite to obtain an aluminum ash material; Adding a binder: adding the modified sodium silicate binder to the aluminum ash material in batches and stirring and mixing evenly to obtain a refractory mortar.

[0019] By adopting the above technical solution, first, the secondary aluminum ash is washed to remove soluble salts potassium chloride and sodium chloride, then low-aluminum mullite, calcined secondary aluminum ash, pretreated secondary aluminum ash, silica fume, potassium feldspar powder, composite additive, and bentonite are stirred and mixed to obtain an aluminum ash material, and finally, the modified sodium silicate binder is added to the aluminum ash material in batches and stirred and mixed evenly to obtain a refractory mortar.

[0020] In summary, the present application includes at least one of the following beneficial technical effects: 1. In the present application, calcined secondary aluminum ash and secondary aluminum ash are selected as the core aluminum sources, and silica fume is used as the silicon source. Under a reasonable silicon-aluminum ratio, the formation of cristobalite phase can be avoided, and the reaction product is mainly mullite phase as the main crystal phase. As the only high-temperature stable phase in the Al-Si binary system, mullite has excellent high-temperature resistance and thermal shock stability; active metal Al and aluminum nitride are contained in secondary aluminum ash. During the high-temperature process, within 500 °C, metal Al and aluminum nitride AlN react with water, and the generated gas overflows from the fireclay, forming micropores and optimizing the pore structure. On the one hand, it can improve the ability of the fireclay to resist thermal shock and thermal stress of thermal cycling. On the other hand, the micropores generated by the reaction can significantly improve the heat insulation performance of the material; in addition, the aluminum hydroxide generated by the reaction decomposes when heated, and the generated alumina has high reactivity and reacts with silica fume at about 1000 °C to form mullite phase, improving the thermal shock resistance of the material; in addition, the generated water vapor is discharged to form pores, further improving the heat insulation performance of the material; the highly active alkali metal oxides potassium oxide and sodium oxide in the calcined secondary aluminum ash, together with the introduced potassium feldspar powder, are used as low-temperature sintering agents. By adjusting the introduction amount of the sintering agent, the sintering temperature of the fireclay is reduced, and the sintering between the material and the brick is accelerated, thereby improving the interfacial bonding strength; therefore, the obtained refractory mortar has excellent high-temperature resistance, thermal shock stability and adiabatic heat preservation performance; 2. The thermal expansion characteristics of kyanite and andalusite in the composite additive of the present application offset the volume shrinkage during the sintering process of the fireclay, maintaining the overall structural stability of the wall; using the decomposition characteristics of calcium carbonate at about 800 °C, and cooperating with the continuous generation of micropores by the calcined secondary aluminum ash during decomposition at different temperature segments, the micropore distribution of the material is adjusted; 3. In the method of the present application, the secondary aluminum ash is first washed with water to remove soluble salts potassium chloride and sodium chloride, then low-aluminum mullite, calcined secondary aluminum ash, pretreated secondary aluminum ash, silica fume, potassium feldspar powder, composite additive, and bentonite are stirred and mixed to obtain an aluminum ash material. Finally, a modified sodium silicate binder is added to the aluminum ash material in batches and stirred and mixed evenly to obtain a refractory mortar. Specific Embodiments

[0021] The present application will be further described in detail below with reference to the embodiments.

[0022] All raw materials in the embodiments can be obtained commercially. Among them, low-aluminum mullite is provided by Shandong Refractories Group Co., Ltd.; calcined secondary aluminum ash and secondary aluminum ash are both provided by Yongzhen Technology Co., Ltd. Embodiments

[0023] Example 1 Example 1 provides a preparation method of a secondary aluminum ash-based silicon-aluminum refractory mortar, including the following steps: Secondary aluminum ash pretreatment: Add 8 kg of secondary aluminum ash to water, stir for 20 min, let it stand and precipitate for 1.5 h, then separate the upper turbid liquid and the lower precipitate. Dry the middle layer material at 110 °C and ball mill it to a particle size of 325 mesh to obtain pretreated secondary aluminum ash. The weight ratio of secondary aluminum ash to water is 1:2. The particle size of the secondary aluminum ash is 200 mesh. The mass percentages of each component in the secondary aluminum ash are as follows: Al is 10 - 20%, AlN is 5 - 15%, Al2O3 is 30 - 50%, KCl is 5 - 10%, and NaCl is 3 - 8%. Mixing materials: Add 20 kg of low - alumina mullite, 52 kg of calcined secondary aluminum ash, pretreated secondary aluminum ash, 10 kg of silica fume, 3 kg of potassium feldspar powder, 4 kg of composite additive, and 3 kg of bentonite into a double - shaft mixer and dry - mix for 8 min to obtain aluminum ash material. The particle size of the low - alumina mullite is 50 mesh, and the content of aluminum oxide in the low - alumina mullite is greater than 45%, the content of iron(III) oxide is less than or equal to 1.5%, and it is composed of mullite phase and amorphous glass phase. The particle size of the calcined secondary aluminum ash is 200 mesh, and the mass percentages of each component in the calcined secondary aluminum ash are as follows: Al2O3 is 60 - 80%, SiO2 is 5 - 15%, Fe2O3 is 0.5 - 3%, CaO is 0.5 - 3%, K2O is 1 - 5%, Na2O is 0.5 - 3%, and MgO is 0.5 - 2%. 2 The content of SiO2 in the silica fume is > 95%, the particle size D50 < 0.5 μm, and the specific surface area > 20 m / g. The particle size of the potassium feldspar powder is 325 mesh, and the content of K2O in the potassium feldspar powder is > 10%, and the content of SiO2 is 55 - 70%. The composite additive is kyanite with a particle size of 325 mesh. The particle size of the bentonite is 325 mesh, and the content of montmorillonite in the bentonite is ≥ 75%, and the total content of aluminum oxide, potassium oxide, and sodium oxide is ≤ 3%.

[0024] Example 2 The difference between Example 2 and Example 1 lies in the secondary aluminum ash pretreatment: Add 12 kg of secondary aluminum ash to water, stir for 20 min, let it stand and precipitate for 1.5 h, then separate the upper turbid liquid and the lower precipitate. Dry the middle layer material at 110 °C and ball mill it to a particle size of 325 mesh to obtain pretreated secondary aluminum ash. Mixing materials: Add 20 kg of low-aluminum mullite, 45 kg of calcined secondary aluminum ash, pretreated secondary aluminum ash, 12 kg of silica fume, 4 kg of potassium feldspar powder, 4 kg of composite additive, and 3 kg of bentonite into a double-shaft mixer, and dry mix for 8 min to obtain aluminum ash material; the composite additive is a mixture composed of kyanite and fine calcium carbonate powder, and the weight ratio of kyanite to fine calcium carbonate powder is 4:1, and the particle size of the composite additive is 325 mesh; Adding binder: Stir and mix water glass with a modulus of 3 and nano-silica evenly to obtain a modified water glass binder, and the mass fraction of nano-silica in the modified water glass binder is 5%; take an appropriate amount of the modified water glass binder, add 40% of the total mass of the modified water glass binder to the aluminum ash material first, stir for 5 min, then add 60% of the total mass of the modified water glass binder, and stir for 7 min to obtain refractory mud; the weight percentage of the modified water glass binder in the refractory mud is 14%; the remaining steps are the same as those in Example 1.

[0025] Example 3 The difference between Example 3 and Example 1 lies in the pretreatment of secondary aluminum ash: Add 10 kg of secondary aluminum ash to water, stir for 20 min, let it stand and precipitate for 1.5 h, then separate the upper turbid liquid and the lower precipitate, dry the middle layer material at 110 °C, and ball mill it to a particle size of 325 mesh to obtain pretreated secondary aluminum ash; Mixing materials: Add 15 kg of low-aluminum mullite, 50 kg of calcined secondary aluminum ash, pretreated secondary aluminum ash, 14 kg of silica fume, 2 kg of potassium feldspar powder, 5 kg of composite additive, and 4 kg of bentonite into a double-shaft mixer, and dry mix for 8 min to obtain aluminum ash material; Adding binder: Stir and mix water glass with a modulus of 3.2 and nano-silica evenly to obtain a modified water glass binder, and the mass fraction of nano-silica in the modified water glass binder is 4%; take an appropriate amount of the modified water glass binder, add 40% of the total mass of the modified water glass binder to the aluminum ash material first, stir for 5 min, then add 30% of the total mass of the modified water glass binder, stir for 3.5 min, and finally add 30% of the total mass of the modified water glass binder, and stir for 3.5 min to obtain refractory mud; the weight percentage of the modified water glass binder in the refractory mud is 14%; the remaining steps are the same as those in Example 1.

[0026] Example 4 The difference between Example 4 and Example 1 lies in the pretreatment of secondary aluminum ash: Add 5 kg of secondary aluminum ash to water, stir for 20 min, let it stand and precipitate for 1.5 h, then separate the upper turbid liquid and the lower precipitate, dry the middle layer material at 110 °C, and ball mill it to a particle size of 325 mesh to obtain pretreated secondary aluminum ash; Mixing materials: Add 10 kg of low-aluminum mullite, 30 kg of calcined secondary aluminum ash, pretreated secondary aluminum ash, 5 kg of silica fume, 3 kg of composite additive, and 1 kg of bentonite into a double-shaft mixer, and dry mix for 8 min to obtain aluminum ash material; Adding binder: Stir and mix water glass with a modulus of 3.2 and nano-silica evenly to obtain a modified water glass binder, and the mass fraction of nano-silica in the modified water glass binder is 4%; Take an appropriate amount of the modified water glass binder, add 40% of the total mass of the modified water glass binder to the aluminum ash material first, stir for 5 min, then add 30% of the total mass of the modified water glass binder, stir for 3.5 min, and finally add 30% of the total mass of the modified water glass binder, stir for 3.5 min to obtain refractory mud; The weight percentage of the modified water glass binder in the refractory mud is 10%; The remaining steps are the same as those in Example 1.

[0027] Example 5 The difference between Example 5 and Example 1 lies in the pretreatment of secondary aluminum ash: Add 15 kg of secondary aluminum ash into water, stir for 20 min, let it stand and precipitate for 1.5 h, then separate the upper turbid liquid and the lower precipitate, dry the middle layer material at 110 °C, and ball mill it to a particle size of 325 mesh to obtain pretreated secondary aluminum ash; Mixing materials: Add 30 kg of low-aluminum mullite, 50 kg of calcined secondary aluminum ash, pretreated secondary aluminum ash, 15 kg of silica fume, 8 kg of composite additive, and 5 kg of bentonite into a double-shaft mixer, and dry mix for 8 min to obtain aluminum ash material; Adding binder: Stir and mix water glass with a modulus of 3.2 and nano-silica evenly to obtain a modified water glass binder, and the mass fraction of nano-silica in the modified water glass binder is 4%; Take an appropriate amount of the modified water glass binder, add 40% of the total mass of the modified water glass binder to the aluminum ash material first, stir for 5 min, then add 30% of the total mass of the modified water glass binder, stir for 3.5 min, and finally add 30% of the total mass of the modified water glass binder, stir for 3.5 min to obtain refractory mud; The weight percentage of the modified water glass binder in the refractory mud is 15%; The remaining steps are the same as those in Example 1.

[0028] Comparative example Comparative example 1 The difference between Comparative example 1 and Example 1 lies in the pretreatment of secondary aluminum ash: Add 2 kg of secondary aluminum ash into water, stir for 20 min, let it stand and precipitate for 1.5 h, then separate the upper turbid liquid and the lower precipitate, dry the middle layer material at 110 °C, and ball mill it to a particle size of 325 mesh to obtain pretreated secondary aluminum ash; Mixing: Add 20 kg of low-aluminum mullite, 20 kg of calcined secondary aluminum ash, pretreated secondary aluminum ash, 20 kg of silica fume, 3 kg of potassium feldspar powder, 4 kg of composite additive, and 3 kg of bentonite into a double-shaft mixer, and dry mix for 8 minutes to obtain aluminum ash material; the remaining steps are the same as those in Example 1.

[0029] Comparative Example 2 The difference between Comparative Example 2 and Example 1 lies in the pretreatment of secondary aluminum ash: Add 18 kg of secondary aluminum ash into water, stir for 20 minutes, let it stand and precipitate for 1.5 hours, then separate the upper turbid liquid and the lower sediment, dry the middle layer material at 110 °C, and ball mill it to a particle size of 325 mesh to obtain pretreated secondary aluminum ash; Mixing: Add 20 kg of low-aluminum mullite, 62 kg of calcined secondary aluminum ash, pretreated secondary aluminum ash, 2 kg of silica fume, 3 kg of potassium feldspar powder, 4 kg of composite additive, and 3 kg of bentonite into a double-shaft mixer, and dry mix for 8 minutes to obtain aluminum ash material; the remaining steps are the same as those in Example 1.

[0030] Performance detection test Performance at room temperature: Measure the initial fluidity value, setting time, and room-temperature flexural bond strength of the refractory cement in each example and comparative example; the detection standard for the initial fluidity value is GB / T 2419 "Test Method for Fluidity of Cement Mortar", the detection standard for the setting time is GB / T 22459.3, and the detection standard for the room-temperature flexural bond strength is GB / T 22459.4.

[0031] Performance at high temperature: Measure the apparent porosity, linear change rate, and flexural bond strength of the refractory cement in each example and comparative example after being treated at 1000 °C; the detection standard for the apparent porosity is GB / T 2997-2000, the detection standard for the linear change rate is GB / T22459.7, and the detection standard for the flexural bond strength after being treated at 1000 °C is GB / T 22459.4.

[0032] Table 1 Performance detection results of refractory cement Combined with Examples 1-3 and Comparative Examples 1-2, it can be seen that when preparing aluminum ash material, according to the raw material ratio in Examples 1-3, under a reasonable silicon-aluminum ratio, the formation of cristobalite phase can be avoided, and the reaction product is mainly composed of mullite phase as the main crystal phase. As the only high-temperature stable phase in the Al-Si binary system, mullite phase has excellent high-temperature resistance and thermal shock stability, so the performance of the obtained refractory mortar is improved.

[0033] Combined with Example 1 and Example 4, the initial fluidity value of the refractory mortar in Example 4 is relatively high, but the setting time is relatively long. It can be seen that because the proportion of the modified water glass binder is insufficient, the fluidity is high but the setting speed is slow.

[0034] Combining Example 1 and Example 5, it can be seen that the high alumina content of the refractory mortar and the modified sodium silicate binder in Example 5 enhance the formation of mullite phase and bonding strength at high temperatures, and also improve the high temperature resistance of the refractory mortar.

[0035] This specific embodiment is only an interpretation of the present application and is not a limitation thereto. After reading this specification, those skilled in the art can make modifications to this embodiment without creative contributions as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A secondary aluminum ash-based silicon-aluminum refractory mortar, characterized in that: The raw materials of the slurry include aluminum ash material and modified sodium silicate binder; the weight percentage of the modified sodium silicate binder in the slurry is 10-15%; the raw materials of the aluminum ash material include the following components in parts by weight: 10-30 parts of low-aluminum mullite, 30-52 parts of calcined secondary aluminum ash, 5-15 parts of secondary aluminum ash, 5-15 parts of silica fume, 3-8 parts of composite additive, 0-5 parts of potassium feldspar powder, and 1-5 parts of bentonite.

2. The secondary aluminum ash-based silicon-aluminum refractory mortar according to claim 1, characterized in that: The particle size of the low-aluminum mullite is 50 mesh, and the content of aluminum oxide in the low-aluminum mullite is greater than 45%, the content of iron oxide is less than or equal to 1.5%, and it is composed of mullite phase and amorphous glass phase.

3. A secondary aluminum ash-based silicon-aluminum refractory mortar according to claim 1, characterized in that: The particle size of the calcined secondary aluminum ash is 200 mesh, and the mass percentages of the components in the calcined secondary aluminum ash are as follows: 60-80% of Al2O3, 5-15% of SiO2, 0.5-3% of Fe2O3, 0.5-3% of CaO, 1-5% of K2O, 0.5-3% of Na2O, and 0.5-2% of MgO.

4. A secondary aluminum ash-based silicon-aluminum refractory mortar according to claim 1, characterized in that: The particle size of the secondary aluminum ash is 200 mesh, and the mass percentages of the components in the secondary aluminum ash are as follows: 10-20% of Al, 5-15% of AlN, 30-50% of Al2O3, 5-10% of KCl, and 3-8% of NaCl.

5. A secondary aluminum ash-based silicon-aluminum refractory mortar according to claim 1, characterized in that: The content of SiO2 in the fused silica powder is > 95%, the particle size D50 < 0.5 μm, and the specific surface area > 20 m 2 / g.

6. The secondary aluminum ash-based silicon-aluminum refractory mortar according to claim 1, characterized in that: The particle size of the potassium feldspar powder is 325 mesh, and the content of K2O in the potassium feldspar powder is >10%, and the content of SiO2 is 55-70%.

7. A secondary aluminum ash-based silicon-aluminum refractory mortar according to claim 1, characterized in that: The particle size of the composite additive is 325 mesh, and the composite additive includes a mixture composed of one or more of kyanite, andalusite, calcium silicate, and calcium carbonate fine powder.

8. A secondary aluminum ash-based silicon-aluminum refractory mortar according to claim 1, characterized in that: The particle size of the bentonite is 325 mesh, and the content of montmorillonite in the bentonite is ≥75%, and the total content of aluminum oxide, potassium oxide, and sodium oxide is ≤3%.

9. A secondary aluminum ash-based silicon-aluminum refractory mortar according to claim 1, characterized in that: The modified sodium silicate binder includes a mixture composed of sodium silicate with a modulus of 2.8-3.2 and nano-silica, and the mass fraction of nano-silica in the modified sodium silicate binder is 3-5%.

10. A method for preparing a secondary aluminum ash-based silicon-aluminum refractory mortar according to any one of claims 1-9, characterized in that: Including the following steps: Pretreatment of secondary aluminum ash: adding secondary aluminum ash into water for washing, then separating, drying, and ball milling to obtain pretreated secondary aluminum ash; Mixing materials: uniformly stirring and mixing low-aluminum mullite, calcined secondary aluminum ash, pretreated secondary aluminum ash, silica fume, potassium feldspar powder, composite additive, and bentonite to obtain aluminum ash material; Adding binder: adding the modified sodium silicate binder to the aluminum ash material in batches, and stirring and mixing evenly to obtain refractory slurry.

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