A method for synthesizing zeolite molecular sieve using economical raw materials

Abstract

The present application relates to the technical field of molecular sieve materials, and in particular to a method for synthesizing zeolite molecular sieves using economical raw materials; the method comprises: mixing high-silicon waste liquid and low-alumina concentration waste liquid, and performing a hydrothermal reaction to obtain a gel; solid-liquid separation of the gel to obtain a gel filter cake; adding a regulator to the gel filter cake, stirring the mixture, and then adding a seed crystal directing agent to perform a crystallization reaction, and performing separation, washing and drying to obtain a zeolite molecular sieve; wherein the volume ratio of the high-silicon waste liquid to the low-alumina concentration waste liquid is 1 to 3:1; the silicon oxide concentration of the high-silicon waste liquid is greater than 1 g / L, and the aluminum oxide concentration of the low-alumina concentration waste liquid is 5 g / L to 30 g / L; the method realizes the deep utilization of silicon in the high-silicon waste liquid and aluminum oxide in the low-alumina waste liquid, thereby significantly reducing the circulation amount of silicon and aluminum oxide in the alumina production process, thereby reducing the production cost of zeolite.

Description

Technical Field

[0001] The present application relates to the technical field of molecular sieve materials, and in particular to a method for synthesizing zeolite molecular sieves using economical raw materials. Background Art

[0002] Zeolite, a crystalline aluminosilicate with a tetrahedral spatial framework, possesses excellent adsorption and sieving properties due to this unique structure. It is also known as a "molecular sieve" and is currently widely used in the molecular sieve, catalyst, and detergent industries. When used as a molecular sieve, zeolite primarily separates gases through pressure swing adsorption. It also acts as a desiccant, used for deep dehydration of gases and liquids, as exemplified by 13X molecular sieves. Furthermore, to protect the environment, 4A zeolite is widely used in detergent production as a phosphorus substitute, earning it the nickname "green additive."

[0003] Currently, the main raw materials used in the production of synthetic zeolite products are relatively high concentrations of sodium aluminate solutions and water glass, and the raw materials required in this synthesis process are relatively expensive. Due to the large amount of low-concentration alumina waste liquid in the alumina production process and the large amount of high-silicon mother liquor generated during the synthesis of 13X molecular sieves, if these two solid waste liquids can be fully utilized, such as effectively extracting alumina and silicon as reactants for the synthesis product, it will greatly reduce the production cost of zeolite and significantly reduce the amount of silicon and alumina recycled in the alumina production process. Therefore, how to provide a method for synthesizing zeolite molecular sieves using economical raw materials to fully utilize low-concentration alumina waste liquid and high-silicon mother liquor is a technical problem that needs to be solved urgently. Summary of the Invention

[0004] The present application provides a method for synthesizing zeolite molecular sieves using economical raw materials to solve the technical problem in the prior art that low-concentration alumina waste liquid and high-silicon mother liquor are difficult to be deeply used in the zeolite production process.

[0005] In a first aspect, the present application provides a method for synthesizing zeolite molecular sieves using economical raw materials, the method comprising:

[0006] Mixing high-silicon waste liquid and low-alumina concentration waste liquid and performing a hydrothermal reaction to obtain a gel;

[0007] solid-liquid separation of the gel to obtain a gel filter cake;

[0008] adding a regulator to the gel filter cake and stirring the mixture, then adding a seed crystal directing agent to carry out a crystallization reaction, and separating, washing and drying the mixture to obtain a zeolite molecular sieve;

[0009] Wherein, the volume ratio of the high silicon waste liquid to the low alumina concentration waste liquid is 1 to 3:1;

[0010] The silicon oxide concentration of the high silicon waste liquid is greater than 1 g / L, and the aluminum oxide concentration of the low aluminum oxide concentration waste liquid is 5 g / L to 30 g / L.

[0011] Optionally, the temperature of the hydrothermal reaction is 75° C. to 85° C., and the time of the hydrothermal reaction is ≥10 min.

[0012] Optionally, the mixing of high-silicon waste liquid and low-alumina concentration waste liquid and performing a hydrothermal reaction to obtain a gel comprises the following steps:

[0013] Mixing high-silicon waste liquid and low-alumina concentration waste liquid, and performing a hydrothermal reaction to obtain a mixed slurry;

[0014] Determining whether to introduce carbon dioxide based on the actual silicon content and the standard silicon content in the mixed slurry;

[0015] If the actual silicon content is less than the standard content, the hydrothermal reaction is continued to obtain a gel;

[0016] If the actual silicon content is greater than or equal to the standard silicon content, carbon dioxide is introduced into the mixed slurry to obtain a gel.

[0017] Optionally, the carbon dioxide is introduced for 30 to 90 minutes.

[0018] Optionally, the standard silicon content is ≤1 g / L.

[0019] Optionally, the regulator includes at least one of sodium aluminate solution, liquid alkali and high-silicon waste liquid.

[0020] Optionally, the concentration of aluminum oxide in the sodium aluminate solution is ≥10 g / L; and / or,

[0021] The concentration of the liquid caustic soda is 30 g / L to 100 g / L; and / or,

[0022] The silicon oxide concentration in the high-silicon waste liquid is 1 g / L to 20 g / L.

[0023] Optionally, the concentration of aluminum oxide in the sodium aluminate solution is 30 g / L to 60 g / L.

[0024] Optionally, the temperature of the crystallization reaction is 40° C. to 130° C., and the time of the crystallization reaction is 2 h to 48 h.

[0025] Optionally, the added amount of the regulator is ≥0%.

[0026] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0027] The embodiment of the present application provides a method for synthesizing zeolite molecular sieves using economical raw materials. The method uses silicon in high-silicon waste liquid generated in the zeolite crystallization process and alumina in low-alumina concentration waste liquid generated in the alumina production process as raw materials, and performs a hydrothermal reaction to obtain a gel of zeolite molecular sieve precursor. The gel is then used in combination with different regulators to generate zeolite products with different crystal forms. After the reaction, the alumina in the waste liquid is almost 0 and the silicon is less than 0.5g / L, which realizes the deep utilization of silicon in high-silicon waste liquid and alumina in low-alumina waste liquid. Therefore, the circulation amount of silicon and alumina in the alumina production process can be greatly reduced, so that the production cost of zeolite can be reduced. At the same time, the low-alumina concentration waste liquid can be used to graft the alumina production process, and the organic connection and green production of alumina and zeolite production can be realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0029] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0030] Figure 1 A schematic flow chart of a method for synthesizing zeolite molecular sieves using economical raw materials provided in an embodiment of the present application;

[0031] Figure 2 A detailed flow chart of a method for synthesizing zeolite molecular sieves using economical raw materials provided in an embodiment of the present application;

[0032] Figure 3 This is the XRD pattern of the gel J-1 product provided in the examples of this application;

[0033] Figure 4 This is the XRD pattern of the gel J-2 product provided in the examples of this application;

[0034] Figure 5 The XRD pattern of product Z-1 provided in the examples of this application;

[0035] Figure 6 This is the SEM scanning electron microscope image of product Z-1 provided in the examples of this application;

[0036] Figure 7 The XRD pattern of product Z-2 provided in the examples of this application;

[0037] Figure 8This is the SEM scanning electron microscope image of the product Z-2 provided in the examples of this application;

[0038] Figure 9 The XRD pattern of product Z-3 provided in the examples of this application;

[0039] Figure 10 This is the SEM scanning electron microscope image of the product Z-3 provided in the examples of this application;

[0040] Figure 11 The XRD pattern of the product Z-4 provided in the examples of this application;

[0041] Figure 12 This is the SEM scanning electron microscope image of the product Z-4 provided in the examples of this application;

[0042] Figure 13 The XRD pattern of the product Z-5 provided in the examples of this application;

[0043] Figure 14 This is the SEM scanning electron microscope image of the product Z-5 provided in the examples of this application;

[0044] Figure 15 The XRD pattern of the product Z-6 provided in the examples of this application;

[0045] Figure 16 This is the SEM scanning electron microscope image of product Z-6 provided in the examples of this application. DETAILED DESCRIPTION

[0046] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0047] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0048] like Figure 1 As shown, the embodiment of the present application provides a method for synthesizing zeolite molecular sieves using economical raw materials, the method comprising:

[0049] S1. Mixing high-silicon waste liquid and low-alumina concentration waste liquid and performing a hydrothermal reaction to obtain a gel;

[0050] S2. solid-liquid separation of the gel to obtain a gel cake;

[0051] S3. A conditioning agent is added to the gel cake and stirred, and then a seed directing agent is added to carry out a crystallization reaction, and separated, washed and dried to obtain a zeolite molecular sieve;

[0052] Wherein, the volume ratio of the high silicon waste liquid to the low alumina concentration waste liquid is 1 to 3:1;

[0053] The silicon oxide concentration of the high silicon waste liquid is greater than 1 g / L, and the aluminum oxide concentration of the low aluminum oxide concentration waste liquid is 5 g / L to 30 g / L.

[0054] In the embodiments of the present application, the specific volume ratio of high-silicon waste liquid and low-alumina concentration waste liquid is controlled, and the silica concentration of the high-silicon waste liquid and the alumina concentration of the low-alumina concentration waste liquid are controlled. The specific mass of silica in the high-silicon waste liquid and the specific mass of alumina in the low-alumina concentration waste liquid can be limited, and a hydrothermal reaction can be used to obtain a gel precursor of the zeolite molecular sieve.

[0055] The volume ratio may be 1:1, 1.5:1, 2:1, 2.5:1, or 3:1.

[0056] The aluminum oxide concentration can be 5g / L, 7g / L, 10g / L, 13g / L, 16g / L, 19g / L, 22g / L, 25g / L, 28g / L, or 30g / L.

[0057] In some optional embodiments, the temperature of the hydrothermal reaction is 75° C. to 85° C., and the time of the hydrothermal reaction is ≥10 min.

[0058] In the embodiments of the present application, the specific temperature and specific reaction time of the hydrothermal reaction are controlled so that the silicon oxide in the high-silicon waste liquid and the aluminum oxide in the low-alumina concentration waste liquid can react completely and generate a gel with a complex network structure, which facilitates the subsequent acquisition of molecular sieves with different crystal forms.

[0059] The temperature of the hydrothermal reaction can be 75°C, 76°C, 77°C, 77°C, 78°C, 79°C, 80°C, 81°C, 82°C, 83°C, 84°C, or 85°C.

[0060] like Figure 2 As shown, in some optional embodiments, the mixing of high-silicon waste liquid and low-alumina concentration waste liquid and performing a hydrothermal reaction to obtain a gel comprises the steps of:

[0061] S101 mixing high silicon waste liquid and low alumina concentration waste liquid, and performing a hydrothermal reaction to obtain a mixed slurry;

[0062] S102. According to the actual silicon content and the standard silicon content in the mixed slurry, it is determined whether carbon dioxide needs to be introduced;

[0063] If the actual silicon content is less than the standard content, the hydrothermal reaction is continued to obtain a gel;

[0064] If the actual silicon content is greater than or equal to the standard silicon content, carbon dioxide is introduced into the mixed slurry to obtain a gel.

[0065] In the embodiments of the present application, by determining the silicon content in the mixed slurry after the hydrothermal reaction, the consumption of raw materials during the reaction process can be determined. If there is residual silicon, carbon dioxide can be introduced to react with the silicon to form a gel product, which is convenient for the subsequent formation of molecular sieve products with different crystal forms through crystallization reaction.

[0066] In some optional embodiments, the carbon dioxide is introduced for 30 min to 90 min.

[0067] In the embodiment of the present application, controlling the specific time of introducing carbon dioxide can allow the residual silicon in the mixed slurry to be completely reacted, thereby forming a sufficient amount of gel product, and further allowing the high-silicon waste liquid and the low-alumina concentration waste liquid to react completely.

[0068] The carbon dioxide introduction time can be 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, 60 min, 65 min, 70 min, 75 min, 80 min, 85 min, or 90 min.

[0069] In some optional embodiments, the standard silicon content is ≤1 g / L.

[0070] In the examples of the present application, the specific content of the standard silicon content is controlled, and under the condition of the standard silicon content, it is indicated that the silicon in the gel is completely consumed, thereby achieving deep utilization of high-silicon waste liquid.

[0071] In some optional embodiments, the regulator includes at least one of sodium aluminate solution, liquid alkali and high-silicon waste liquid.

[0072] In the embodiments of the present application, the specific type of the control regulator can be adjusted by using different regulators according to the requirements of zeolite molecular sieves with different crystal forms.

[0073] In some optional embodiments, the concentration of aluminum oxide in the sodium aluminate solution is ≥10 g / L; and / or,

[0074] The concentration of the liquid caustic soda is 30 g / L to 100 g / L; and / or,

[0075] The silicon oxide concentration in the high-silicon waste liquid is 1 g / L to 20 g / L.

[0076] In some optional embodiments, the concentration of aluminum oxide in the sodium aluminate solution is 30 g / L to 60 g / L.

[0077] In the embodiments of the present application, the specific alumina concentration of the sodium aluminate solution, the specific concentration of the liquid caustic soda, and the specific silica concentration of the high-silicon waste liquid are controlled, and different regulators can be further selected according to the requirements of different gel types and different crystal forms of molecular sieves to promote the full progress of the subsequent crystallization reaction.

[0078] In some optional embodiments, the temperature of the crystallization reaction is 40° C. to 130° C., and the time of the crystallization reaction is 2 h to 48 h.

[0079] In the embodiments of the present application, the specific temperature and specific time of the crystallization reaction are controlled so that the gel product can react completely with the regulator and the seed directing agent, thereby obtaining molecular sieve products with different crystal forms according to different gel products and different regulators.

[0080] The temperature of the crystallization reaction can be 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, 120°C, 125°C, or 130°C.

[0081] The crystallization reaction time can be 2h, 4h, 6h, 8h, 10h, 12h, 14h, 16h, 18h, 20h, 22h, 24h, 26h, 28h, 30h, 32h, 34h, 36h, 38h, 40h, 42h, 44h, 46h, or 48h.

[0082] In some optional embodiments, the amount of the regulator added is ≥0%.

[0083] In the embodiments of the present application, the specific amount of the regulator added is controlled. According to the actual requirements of the zeolite molecular sieve crystal form, it is possible to choose to add the regulator or not, and the corresponding type of regulator to be added, so as to obtain a molecular sieve product of the corresponding crystal form.

[0084] The present application will be further described below in conjunction with specific examples. It should be understood that these examples are intended to illustrate the present application only and are not intended to limit the scope of the present application. The experimental methods in the following examples where specific conditions are not specified are usually measured in accordance with national standards. If there are no corresponding national standards, then the methods are carried out in accordance with general international standards, conventional conditions, or according to the conditions recommended by the manufacturer.

[0085] Example 1

[0086] A high-silicon waste liquid with an initial silicon concentration of 9.58 g / L and a low-alumina waste liquid with an initial alumina concentration of 12.45 g / L were used. The low-alumina waste liquid and the high-silicon waste liquid were mixed in a volume ratio of 1:1.5 and subjected to a hydrothermal reaction at 80°C for 30 minutes. The slurry was then separated to reduce the Al2O3 concentration in the mother liquor to 0 g / L, thereby obtaining a gel filter cake numbered as gel J-1.

[0087] Alternatively, a high-silicon waste liquid with a silicon oxide concentration of 1 g / L to 20 g / L and a low-alumina waste liquid with an alumina concentration of 5 g / L to 30 g / L were used, the low-alumina waste liquid and the high-silicon waste liquid were mixed in a volume ratio of 1:1.5, and subjected to a hydrothermal reaction at 80° C. for 10 min, followed by the introduction of carbon dioxide for a hydrothermal reaction for 30 min to 90 min, and then slurry separation was performed to reduce the Al2O3 concentration in the mother liquor to 0 g / L, thereby obtaining a gel filter cake numbered as gel J-2;

[0088] The obtained gel J-1 and gel J-2 were subjected to X-ray diffraction detection, and the results were as follows: Figure 3 and Figure 4 shown.

[0089] Example 2

[0090] Based on the gel J-1 obtained in Example 1, a sodium aluminate solution with an alumina content of 40.2 g / L was added as a regulator to the synthesis reactor containing the gel J-1. The mixture was stirred for 30 minutes. Then, a seed crystal directing agent accounting for 0.2% of the total mass ratio of the reactants was added, and the temperature was raised to 80°C. Crystallization was carried out under insulation for 3 hours. After separation, washing, and drying, the product was obtained, which was numbered Z-1.

[0091] The product Z-1 was tested by X-ray diffraction, and the results were as follows: Figure 5 The results were observed under a scanning electron microscope. Figure 6 As shown, the results show that the product is 4A zeolite molecular sieve.

[0092] Example 3

[0093] Based on the gel J-1 obtained in Example 1, the gel mother liquor was added to the synthesis reactor containing the gel J-1, and the mixture was stirred directly for 30 minutes. Then, 0.2% of a seed director was added and the temperature was raised to 85°C. The mixture was crystallized for 3 hours under a heat preservation state. After separation, washing, and drying, the product was obtained, which was numbered Z-2.

[0094] The product Z-2 was tested by X-ray diffraction, and the results were as follows: Figure 7 The results were observed under a scanning electron microscope. Figure 8 This indicates that the product is a pure phase 13X molecular sieve.

[0095] Example 4

[0096] Based on the gel J-1 obtained in Example 1, the gel mother liquor was added to the synthesis reactor containing the gel J-1, and the mixture was stirred directly under stirring for 30 minutes. Then, a crystal seed director accounting for 0.2% of the total mass ratio of the reactants was added, and the temperature was raised to 65°C for aging. The mixture was kept warm for aging for 4 hours, and then the temperature was raised to 85°C and crystallized under the warm state for 4 hours. After separation, washing, and drying, the product was obtained, which was numbered Z-3.

[0097] The product Z-3 was tested by X-ray diffraction, and the results were as follows: Figure 9 The results were observed under a scanning electron microscope. Figure 10 This indicates that the product is a pure phase 13X molecular sieve.

[0098] Example 5

[0099] Based on the gel J-2 obtained in Example 1, a sodium aluminate solution with an alumina content of 40.2 g / L was added as a regulator to the synthesis reactor containing the gel J-2. The mixture was stirred for 30 minutes. Then, a seed director accounting for 0.2% of the total mass of the reactants was added, and the temperature was raised to 80°C. The mixture was crystallized for 3 hours under a heat-insulating state. After separation, washing, and drying, the product was obtained, which was numbered Z-4.

[0100] The product Z-4 was tested by X-ray diffraction, and the results were as follows: Figure 11 The results were observed under a scanning electron microscope. Figure 12 As shown, the results indicate that the product is pure phase 4A zeolite.

[0101] Example 6

[0102] Based on the gel J-2 obtained in Example 1, the obtained gel mother liquor was added to the synthesis reactor containing gel J-2, and 30 g / L of liquid caustic soda was used as a regulator to adjust the total alkali content to 120 g / L. The mixture was stirred for 30 minutes under stirring, and then a seed crystal director accounting for 0.2% of the total mass ratio of the reactants was added. The mixture was heated to 65°C for aging, kept at this temperature for aging for 2 hours, and then heated to 85°C and crystallized under this temperature for 5 hours. After separation, washing, and drying, the product was obtained, which was numbered Z-5.

[0103] The product Z-5 was tested by X-ray diffraction, and the results were as follows: Figure 13 The results were observed under a scanning electron microscope. Figure 14 As shown, the results indicate that the product is pure phase 4A zeolite.

[0104] Example 7

[0105] Based on the gel J-2 obtained in Example 1, high-silicon waste liquid with a silicon oxide content of 9 g / L was added as a regulator to the synthesis reactor containing gel J-2, and the total alkali content was adjusted to 80 g / L. The mixture was stirred for 30 minutes under stirring, and then a crystal seed director accounting for 0.2% of the total mass ratio of the reactants was added. The mixture was heated to 65°C for aging, kept at this temperature for aging for 2 hours, and then heated to 85°C and crystallized under this temperature for 5 hours. After separation, washing, and drying, the product was obtained, which was numbered Z-6.

[0106] The product Z-6 was tested by X-ray diffraction, and the results were as follows: Figure 15 The results were observed under a scanning electron microscope. Figure 16 As shown, the results show that the product is a pure phase 13X molecular sieve.

[0107] In summary, the embodiments of the present application provide a method for synthesizing zeolite molecular sieves using economical raw materials. High-silicon waste liquid and low-alumina concentration waste liquid are used as raw materials, and carbon dioxide is selectively introduced to obtain two gels with different structures. Different regulators including sodium aluminate solution, liquid alkali or high-silicon waste liquid are then added, or no regulator is added, to further crystallize the gel, thereby producing 4A and 13X molecular sieve products with different crystal forms to meet the needs of different high-end molecular sieve customers.

[0108] At the same time, this method can effectively reduce the circulation volume of silicon and alumina in the alumina process and realize the comprehensive utilization of waste liquid, thereby reducing production costs while increasing corporate benefits. In addition, the synthesis process has no external emissions, is environmentally friendly, and has significant social benefits.

[0109] Various embodiments of the present application may be presented in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity and should not be understood as a hard limitation on the scope of the present application; therefore, the range description should be considered to have specifically disclosed all possible sub-ranges and single numbers within the range. For example, the description of a range from 1 to 6 should be considered to have specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which applies regardless of the range. In addition, whenever a numerical range is indicated herein, it is meant to include any cited number (fractional or integer) within the indicated range.

[0110] In this application, unless otherwise indicated, directional terms such as "upper" and "lower" refer specifically to the directions of the drawings in the accompanying drawings. Additionally, in the description of this application specification, the terms "including," "comprising," and the like mean "including but not limited to." In this document, relational terms such as "first" and "second" are used solely to distinguish one entity or operation from another, and do not necessarily require or imply any actual relationship or order between these entities or operations. As used herein, "and / or" describes an association between associated objects, indicating that three possible relationships exist. For example, "A and / or B" can mean: A exists alone, A and B exist simultaneously, or B exists alone. A and B can be singular or plural. As used herein, "at least one" means one or more, and "plurality" means two or more. "At least one," "at least one of the following," or similar expressions refer to any combination of these items, including any combination of singular or plural items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, c can be single or multiple.

[0111] The foregoing is merely a list of specific embodiments of the present application, intended to enable those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application is not limited to the embodiments shown herein, but is intended to conform to the broadest scope consistent with the principles and novel features of the present application.

Claims

1. A method for synthesizing zeolite molecular sieves using economical raw materials, characterized in that: The method comprises: Mixing high-silicon waste liquid and low-alumina concentration waste liquid and performing a hydrothermal reaction to obtain a gel; solid-liquid separation of the gel to obtain a gel filter cake; adding a regulator to the gel filter cake and stirring the mixture, then adding a seed crystal directing agent to carry out a crystallization reaction, and separating, washing and drying the mixture to obtain a zeolite molecular sieve; Wherein, the volume ratio of the high silicon waste liquid to the low alumina concentration waste liquid is 1 to 3:1; The silicon oxide concentration of the high silicon waste liquid is greater than 1 g / L, and the aluminum oxide concentration of the low aluminum oxide concentration waste liquid is 5 g / L to 30 g / L; The mixing of high-silicon waste liquid and low-alumina concentration waste liquid and performing a hydrothermal reaction to obtain a gel comprises the following steps: Mixing high-silicon waste liquid and low-alumina concentration waste liquid, and performing a hydrothermal reaction to obtain a mixed slurry; Determining whether to introduce carbon dioxide based on the actual silicon content and the standard silicon content in the mixed slurry; If the actual silicon content is less than the standard silicon content, the hydrothermal reaction is continued to obtain a gel; If the actual silicon content is greater than or equal to the standard silicon content, introducing carbon dioxide into the mixed slurry to obtain a gel; The standard silicon content is 1 g / L.

2. The method according to claim 1, characterized in that The temperature of the hydrothermal reaction is 75° C. to 85° C., and the time of the hydrothermal reaction is ≥10 min.

3. The method according to claim 1, characterized in that The carbon dioxide is introduced for 30 to 90 minutes.

4. The method according to claim 1, wherein The regulator includes at least one of sodium aluminate solution, liquid alkali and high-silicon waste liquid.

5. The method according to claim 4, characterized in that The concentration of aluminum oxide in the sodium aluminate solution is ≥10 g / L; and / or, The concentration of the liquid caustic soda is 30 g / L to 100 g / L; and / or, The silicon oxide concentration in the high-silicon waste liquid is 1 g / L to 20 g / L.

6. The method according to claim 5, characterized in that The concentration of aluminum oxide in the sodium aluminate solution is 30 g / L to 60 g / L.

7. The method according to claim 1, characterized in that The temperature of the crystallization reaction is 40° C. to 130° C., and the time of the crystallization reaction is 2 h to 48 h.

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