Method for synergistically washing and detoxifying household garbage incineration fly ash and aluminum ash

Abstract

The invention relates to the technical field of solid waste treatment, in particular to a method for synergistically washing and detoxifying household garbage incineration fly ash and aluminum ash. The method comprises the following steps: S1, collaborative washing; S2, chloride recovery; and S3, preparation of the hydraulic alkali-activated cementing material. The household garbage incineration fly ash and the aluminum ash which are adopted by the invention are hazardous wastes which need to be subjected to innocent treatment originally, and the household garbage incineration fly ash and the aluminum ash are subjected to cooperative treatment to generate the novel hydraulic alkali-activated cementing material, so that cooperative treatment of the household garbage incineration fly ash and the aluminum ash is realized, and the purpose of treating wastes with wastes is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of solid waste treatment, and particularly to a method for synergistic water washing and detoxification of municipal solid waste incineration fly ash and aluminum ash. Background Art

[0002] Alkali-activated cementitious materials, also known as "chemically activated cementitious materials", are hydraulic cementitious materials prepared by utilizing the catalytic principle of alkali activators. A small amount of alkali activator can act as a catalyst during the hardening process of the cementitious material, making it easier for silicon and aluminum compounds in the material to dissolve and form sodium silicate and sodium meta-aluminate, which further react with Ca(OH)2 to form calcium silicate and calcium aluminate minerals to cause cementitious hardening. Alkali-activated cementitious materials have the characteristics of fast setting and hardening, high strength, and high temperature resistance, and can be used in civil construction, solid nuclear waste, high strength, sealing, and high temperature environment and other projects.

[0003] Co-processing in cement kilns has been promoted and applied within a certain range. Generally speaking, there are not many other mature and reliable technologies, and most are in the R & D stage, with insufficient comprehensive utilization technology reserves; the comprehensive technologies for municipal solid waste incineration fly ash include the use of water washing coupled with co-processing in cement kilns, plasma melting, etc. Water washing coupled with co-processing in cement kilns has the advantages of large processing capacity, good removal effect of soluble salts, degradation of dioxins, and solidification of heavy metals, and is the mainstream method for fly ash comprehensive utilization at present. However, this technology is too dependent on cement kilns, and the cement kiln has high requirements for the chlorine content of the incoming materials, and the fly ash incorporation ratio is limited. Plasma melting has a good solidification effect on heavy metals, but there are problems such as high energy consumption, high cost, and large generation of secondary fly ash.

[0004] In order to solve the above problems, the present invention provides a method for synergistic water washing and detoxification of municipal solid waste incineration fly ash and aluminum ash. Summary of the Invention

[0005] The technical solution of the present invention is as follows: A method for synergistic water washing and detoxification of municipal solid waste incineration fly ash and aluminum ash, comprising the following steps:

[0006] S1. Synergistic water washing

[0007] First, pretreat the municipal solid waste incineration fly ash to obtain pretreated fly ash, and mix the pretreated fly ash and aluminum ash according to an aluminum-silicon molar ratio of 1.5 - 3.5:1 to obtain mixture A. Then, add mixture A to water at a ratio of 1 g:0.25 - 0.45 mL, stir well to remove soluble salts, and then wash in multiple stages until the soluble chlorine content ≤ 1% to obtain wash liquor A;

[0008] S2. Chloride recovery

[0009] The washing liquid A is subjected to flocculation precipitation to remove heavy metals, and then sodium chloride and potassium chloride are crystallized out step by step from the washing liquid A after heavy metal removal. The remaining liquid is washing liquid B. Then, the washing liquid B is dehydrated to obtain washing residue, and then the washing residue is dehydrated and dried to obtain the treated washing residue.

[0010] S3. Preparation of hydraulic alkali-activated cementitious material

[0011] The treated washing residue and slag are mixed according to a mass ratio of 5:1 - 25 to obtain mixture B. Finally, an alkali activator is added to mixture B according to a mass ratio of mixture B:alkali activator of 10 - 50:1 and mixed evenly to obtain the hydraulic alkali-activated cementitious material.

[0012] Further, in step S1, the pretreatment method is: microwave treating the municipal solid waste incineration fly ash for 1 - 10 min under the condition of a microwave power of 10 - 100 kw.

[0013] Note: The above pretreatment method can quickly and effectively remove dioxins.

[0014] Further, in step S2, the flocculation precipitation method is: adding a flocculant to the washing liquid A according to a ratio of 10 - 30 mg / L, and standing for 25 - 40 min. The flocculant is a mixture obtained by mixing any one of polyferric chloride, polyferric sulfate, polyaluminum chloride, polysilicate aluminum and polyacrylamide in equal proportion.

[0015] Note: This flocculation precipitation step can effectively remove heavy metals in the washing liquid A, thus improving the treatment effect; as a high molecular flocculant, polyacrylamide mainly plays a role in assisting coagulation, and when it is used in combination with other flocculants (such as polyferric chloride, polyferric sulfate, etc.), it can avoid the problem of small and unstable flocs when using flocculants such as iron salts or aluminum salts alone for low-concentration heavy metals, effectively improve the sedimentation rate and the removal rate of heavy metals, and improve the overall heavy metal removal effect in the flocculation precipitation process.

[0016] Further, in step S2, before stepwise crystallization, the heavy metals remaining in the washing liquid A are subjected to capture treatment. The capture treatment method is: adding cage-like zeolite capture microspheres to the washing liquid A according to a ratio of 0.05 - 0.1 g:40 - 60 mL, placing it on a horizontal shaker and oscillating at a constant temperature of 22 - 27 °C for 100 - 150 min.

[0017] The preparation method of the cage-like zeolite capture microspheres is as follows: Mix rice husk ash and potassium silicate according to a mass ratio of 1:0.2 - 0.25 to obtain product A. Then, add an aluminum-based compound to product A according to a mass ratio of product A:aluminum-based compound of 3 - 4:1 and mix. Put it into a spherical mold and heat and cure it into a spherical shape at 60 - 80 °C to obtain product B. Finally, according to a spraying amount of 3 - 5 mL / cm 2 Spray oleic acid on the surface of product B, and then calcine it at 400 - 600 °C for 1.5 - 3 h to obtain a zeolite-like material. Mix the zeolite-like material and C-S-H gel according to a mass ratio of 2 - 5:1 - 3, and then put it into an autoclave. Carry out hydrothermal treatment at a temperature of 100 - 120 °C and a pressure of 3 - 7 MPa for 20 - 60 min to obtain a hydrothermally treated product. Cool the hydrothermally treated product to room temperature, and after drying, obtain cage-like zeolite capture microspheres with a particle size of 80 - 120 μm;

[0018] Note: The cage-like structure formed by polymer cyclic molecules can effectively adsorb heavy metal ions. Compared with other solid adsorbents, the cage-like structure has excellent adsorption, chelation, and cross-linking effects, and can more effectively remove low-concentration heavy metals in fly ash and aluminum ash; carrying out heavy metal capture treatment after flocculation precipitation can further improve the removal efficiency of heavy metals, making the heavy metal content in fly ash and aluminum ash reach the discharge standard; heavy metal capture treatment can convert heavy metals in fly ash and aluminum ash into stable compounds, reducing the volatilization and leakage of heavy metals, thereby reducing the risk of secondary pollution. Fly ash and aluminum ash contain a large amount of valuable metals such as aluminum and iron, which can be recycled through heavy metal solidification treatment to improve resource utilization rate.

[0019] The cage-like structure also has an adsorption effect on heavy metal ions such as Pb 2+ etc., and can chelate with heavy metal ions to form a reticular cage-like structure, further reducing the residue of heavy metal ions in washing liquid A.

[0020] Furthermore, the aluminum-based compound is composed of any one of aluminum, aluminum oxide, and aluminum hydroxide and a graphene material according to a mass ratio of 1:0.3 - 0.5;

[0021] Note: The empty orbitals around aluminum atoms can accept the lone pair electrons of heavy metal ions, thereby fixing the heavy metal ions on the surface or inside of the material and preventing their migration and diffusion; the alumina generated by the decomposition of aluminum hydroxide during the heating and curing process has a large specific surface area, which can provide more adsorption sites to adsorb heavy metal ions. The high strength and stability of the graphene material can further improve its adsorption effect during the adsorption of heavy metals. At the same time, the stability of the aluminum-based compound can also help maintain the effectiveness of the adsorption sites and prevent the structure of the microspheres from collapsing during the adsorption process, thereby ensuring the continuous progress of adsorption.

[0022] Further, in step S2, the method of fractional crystallization is as follows: First, heat the washed liquid A after heavy metal removal to 90 - 100 °C for evaporation and concentration until potassium chloride in the washed liquid A after heavy metal removal reaches a saturated dissolution state to obtain a concentrated liquid. Then, cool the concentrated liquid to precipitate sodium chloride crystals to obtain a remaining concentrated liquid. Finally, add an ethanol solvent with a concentration of 65 - 70% to the remaining concentrated liquid according to a volume ratio of 10:1 to precipitate potassium chloride crystals. Separate and dry the precipitated sodium chloride crystals and potassium chloride crystals at 28 - 32 °C respectively to obtain sodium chloride and potassium chloride products;

[0023] Note: The above method of fractional crystallization can effectively separate sodium chloride and potassium chloride, improve the product purity, and thus achieve the efficient recovery of resources.

[0024] Further, in step S2, the method for dehydrating and drying the washed residue is as follows: Use a plate and frame filter press to dehydrate the washed residue under the conditions of a filtration area of 15 - 40 m 2 , a filtration volume of 0.25 - 0.65 m 3 , a number of filter chambers of 19 - 49 pcs, and a filtration pressure of 0.5 MPa to obtain a filter cake. Then, pre-cool the filter cake to -20 - -40 °C and pre-freeze it at this temperature for 25 - 40 min. Finally, evacuate to 55 - 75 Pa and heat it at a heating rate of 5 - 10 °C / min to 40 - 70 °C, and keep it at a constant temperature for drying for 5 - 10 h until the moisture content of the filter cake ≤ 3% to obtain the treated washed residue;

[0025] Description: The water-washed slag after dehydration by vacuum freeze-drying has a more porous internal structure. When it is mixed with slag and an alkali activator to form a hydraulic alkali-activated cementitious material, this porous structure facilitates the faster penetration of the alkali activator into the interior of the water-washed slag, thereby accelerating the progress of the alkali activation reaction, accelerating the setting and hardening rate of the cementitious material, and enabling these gel products to play a cementing and filling role at an early stage, promoting the faster setting and hardening of the material. At the same time, from a microscopic structure perspective, after dehydration by vacuum freeze-drying, more active sites will form on the surface of the water-washed slag, making the hydration products generated by its reaction with slag and alkali activator more uniform and dense. The generated C-S-H (calcium silicate hydrate) gel can better fill the pores inside the material, improving the density of the material. The increase in density directly contributes to improving the strength indexes such as compressive strength and flexural strength of the material. And this treatment method may change the crystal structure in the water-washed slag, making it form a more stable and higher-strength crystal phase structure after the alkali activation reaction, further enhancing the overall strength of the material. After dehydration by vacuum freeze-drying, when the water-washed slag forms an alkali-activated cementitious material, the internal moisture is effectively removed. When the material is subjected to high temperature, the pores and internal stress generated by the evaporation of internal moisture are reduced, so that the generated products have better stability at high temperature.

[0026] Further, in step S3, the alkali activator is one of sodium hydroxide, sodium silicate, sodium carbonate, and sodium sulfate;

[0027] Description: The above alkali activator can continuously react with the components in the slag, continuously optimizing the structure and composition of the gel. As the reaction progresses, the internal structure of the material becomes more dense and the porosity decreases, thus continuously increasing the compressive and flexural strengths in the later stage. This optimized pore structure not only helps to improve the strength of the material but also reduces the intrusion of moisture and harmful gases, further improving the durability of the material.

[0028] Further, in step S3, before mixing the treated water-washed slag with the slag, the slag is subjected to grinding and activation treatment until the particle size is 0.2 - 1 mm; in step S1, the multi-stage water washing is 2 - 4 stages of water washing. Among them, in the multi-stage water washing process, the first stage is washed with water, and then each subsequent stage of water washing uses the water-washed liquid after the previous water washing;

[0029] Description: The above multi-stage water washing can effectively ensure the effective removal of soluble chlorine in fly ash and aluminum ash. Excessive soluble chlorine content will affect the strength of the cementitious material product. The content of soluble chlorine is measured according to the method specified in the HJ1134 standard. Using the water-washed liquid after the previous water washing can greatly reduce the use of fresh water, which is of great significance for environmental protection and the sustainable utilization of water resources.

[0030] Furthermore, the hydraulic alkali-activated cementitious material is applied to projects such as civil construction and filling backfill.

[0031] Compared with the existing technologies, the beneficial effects of the present invention are as follows:

[0032] (1) The synergistic water washing and detoxification of municipal solid waste incineration fly ash and aluminum ash is an effective treatment method, which can reduce harmful substances such as heavy metals and organic matters in the fly ash and aluminum ash, thereby reducing their potential harm to the environment; the municipal solid waste incineration fly ash and aluminum ash adopted in the present invention are originally hazardous wastes that need to be harmlessly treated, and the method proposed in the present invention for generating a new type of hydraulic alkali-activated cementitious material through the synergistic treatment of the two realizes the synergistic treatment of the fly ash and aluminum ash, achieving the purpose of treating waste with waste.

[0033] (2) In the present invention, the residual heavy metals in the washing liquid A are captured. The cage-like zeolite-like microspheres can more effectively remove the residual low-concentration heavy metals in the fly ash and aluminum ash. The cage-like structure is a three-dimensional network-like zeolite cage structure, which can exert the potential hydraulicity of the fly ash, improve the strength of the geopolymer, and can also play a good role in solidifying heavy metal ions, avoiding secondary pollution of the fly ash. The surface of the cage-like structure usually carries a positive charge, which enables them to form an electrostatic attraction with the negatively charged heavy metal ions, further enhancing the adsorption effect. Moreover, the internal cavity structure of the cage-like structure enables the cage-like structure to maintain its adsorption capacity for a long time, thereby achieving the long-term removal of heavy metals. Description of the Drawings

[0034] Figure 1 is a comparison chart of the fracture toughness of the hydraulic alkali-activated cementitious materials in Examples 1 to 11 and Control Groups 1 to 3 of the present invention;

[0035] Figure 2 is a comparison chart of the compressive strength of the hydraulic alkali-activated cementitious materials in Examples 1 to 11 and Control Groups 1 to 3 of the present invention;

[0036] Figure 3 is a comparison chart of the fracture toughness of the hydraulic alkali-activated cementitious materials in Example 1, Examples 12 to 18 and Control Groups 4 to 6 of the present invention;

[0037] Figure 4 is a comparison chart of the compressive strength of the hydraulic alkali-activated cementitious materials in Example 1, Examples 12 to 18 and Control Groups 4 to 6 of the present invention;

[0038] Figure 5 is a comparison chart of the average heavy metal removal rate of the washing liquid A in Example 1, Examples 12 to 18 and Control Groups 4 to 6 of the present invention. Detailed implementation mode

[0039] To further elaborate on the methods adopted and the effects achieved by the present invention, the technical solutions of the present invention will be clearly and completely described below in combination with experiments.

[0040] Example 1: A method for synergistic water washing and detoxification of municipal solid waste incineration fly ash and aluminum ash, comprising the following steps:

[0041] S1. Synergistic water washing

[0042] First, pre-treat the municipal solid waste incineration fly ash to obtain the pre-treated fly ash, and mix the pre-treated fly ash and aluminum ash according to the molar ratio of aluminum to silicon of 2.5:1 to obtain mixture A. Then add mixture A to water at a ratio of 1 g:0.35 mL, fully stir to remove soluble salts, and then wash with multiple stages until the soluble chlorine content is 1% to obtain washing liquid A; the pre-treatment method is: microwave-treat the municipal solid waste incineration fly ash for 5 min under the condition of a microwave power of 500 kw.

[0043] S2. Chloride recovery

[0044] Perform flocculation precipitation on washing liquid A to remove heavy metals, and then fractionally crystallize sodium chloride and potassium chloride from the washing liquid A after removing heavy metals. The remaining liquid is washing liquid B. Then dehydrate washing liquid B to obtain washing residue, and then perform dehydration and drying treatment on the washing residue to obtain the treated washing residue;

[0045] Among them, the method of flocculation precipitation is: add a flocculant to washing liquid A at a ratio of 20 mg / L, and let it stand for 32 min. The flocculant is a mixture obtained by mixing polyferric chloride and polyacrylamide in equal proportions;

[0046] Among them, the method of fractional crystallization is: first heat the washing liquid A after removing heavy metals to 95 °C for evaporation and concentration until potassium chloride in the washing liquid A after removing heavy metals reaches a saturated dissolution state to obtain a concentrated liquid. Then cool the concentrated liquid to precipitate sodium chloride crystals to obtain the remaining concentrated liquid; finally, add an ethanol solvent with a concentration of 68% to the remaining concentrated liquid according to a volume ratio of 10:1 to precipitate potassium chloride crystals; separately dry the separated sodium chloride crystals and potassium chloride crystals at 30 °C to obtain sodium chloride and potassium chloride products;

[0047] Among them, the method of dehydrating and drying the washing residue is: use a plate and frame filter press with a filtration area of 25 m 2 and a filtration volume of 0.45 m 3, the number of filter chambers is 35pcs, and the filtration pressure is 0.5MPa. The water-washed slag is dehydrated to obtain a filter cake, and then the filter cake is pre-cooled to -30°C and pre-frozen at this temperature for 33min, and finally evacuated to 65Pa, and heated to 55°C at a heating rate of 7°C / min, and dried at a constant temperature for 8h until the moisture content of the filter cake is 3%, to obtain the treated water-washed slag;

[0048] S3. Preparation of hydraulic alkali-activated cementitious materials

[0049] The treated washed slag is mixed with the slag in a mass ratio of 5:12 to obtain a mixture B, and finally an alkali activator is added to the mixture B in a mass ratio of 30:1 to obtain a hydraulic alkali-activated cementitious material; wherein the alkali activator is sodium hydroxide; wherein the main components of the slag include silicon dioxide (SiO2), aluminum oxide (Al2O3), iron oxide (Fe2O3), calcium oxide (CaO) and magnesium oxide (MgO), etc. In this scheme, the slag is directly obtained from an incinerator and can be crushed and pre-treated;

[0050] The slag is ground and activated to a particle size of 0.2 to 1 mm before the treated washed slag is mixed with the slag; the multi-stage washing comprises three stages of washing, wherein in the multi-stage washing process, the first stage is washed with water, and each subsequent stage of washing uses the washing liquid from the previous washing;

[0051] The hydraulic alkali-activated cementitious materials are applied in civil engineering, construction, backfilling and other projects.

[0052] Example 2: Different from Example 1, in step S1, the fly ash from the incineration of domestic waste is microwave-treated for 10 minutes under the condition of a microwave power of 10 kW, and then the pretreated fly ash and aluminum ash are mixed at an aluminum-silicon molar ratio of 1.5:1 to obtain a mixture A, and then the mixture A is added to water at a ratio of 1 g:0.25 mL, stirred thoroughly to remove soluble salts, and then washed with water for multiple stages until the soluble chlorine content is 1%, to obtain a water washing liquid A.

[0053] Example 3: Different from Example 1, in step S1, the fly ash from the incineration of domestic waste is microwave-treated for 1 min at a microwave power of 100 kW, and then the pretreated fly ash and aluminum ash are mixed at an aluminum-silicon molar ratio of 3.5:1 to obtain a mixture A, and then the mixture A is added to water at a ratio of 1 g:0.45 mL, stirred thoroughly to remove soluble salts, and then washed with water for multiple stages until the soluble chlorine content is 1%, to obtain a water washing liquid A.

[0054] Example 4: Different from Example 1, in step S2, the flocculation precipitation method is: add flocculant to the water washing liquid A at a ratio of 10 mg / L, and let it stand for 25 minutes.

[0055] Example 5: Different from Example 1, in step S2, the method of flocculation precipitation is as follows: Add a flocculant to the washed solution A at a ratio of 30 mg / L, and let it stand for 40 min.

[0056] Example 6: Different from Example 1, in step S2, the method of fractional crystallization is as follows: First, heat the washed solution A after heavy metal removal to 90 °C for evaporation and concentration until potassium chloride in the washed solution A after heavy metal removal reaches a saturated dissolution state to obtain a concentrated liquid. Then, cool the concentrated liquid to precipitate sodium chloride crystals to obtain a remaining concentrated liquid. Finally, add an ethanol solvent with a volume concentration of 65% to the remaining concentrated liquid at a volume ratio of 10:1 to precipitate potassium chloride crystals. Separate and dry the precipitated sodium chloride crystals and potassium chloride crystals at 28 °C to obtain sodium chloride and potassium chloride products.

[0057] Example 7: Different from Example 1, in step S2, the method of fractional crystallization is as follows: First, heat the washed solution A after heavy metal removal to 100 °C for evaporation and concentration until potassium chloride in the washed solution A after heavy metal removal reaches a saturated dissolution state to obtain a concentrated liquid. Then, cool the concentrated liquid to precipitate sodium chloride crystals to obtain a remaining concentrated liquid. Finally, add an ethanol solvent with a volume concentration of 70% to the remaining concentrated liquid at a volume ratio of 10:1 to precipitate potassium chloride crystals. Separate and dry the precipitated sodium chloride crystals and potassium chloride crystals at 32 °C to obtain sodium chloride and potassium chloride products.

[0058] Example 8: Different from Example 1, in step S2, the method for dehydrating and drying the washed residue is as follows: Use a plate and frame filter press to dehydrate the washed residue under the conditions of a filtration area of 15 m 2 , a filtration volume of 0.25 m 3 , 19 filter chambers, and a filtration pressure of 0.5 MPa to obtain a filter cake. Then, pre-cool the filter cake to -20 °C and pre-freeze it at this temperature for 25 min. Finally, evacuate to 55 Pa and heat it at a heating rate of 5 °C / min to 40 °C, and keep it at a constant temperature for drying for 5 h until the water content of the filter cake is 3% to obtain the treated washed residue.

[0059] Example 9: Different from Example 1, in step S2, the method for dehydrating and drying the washed residue is as follows: Use a plate and frame filter press to dehydrate the washed residue under the conditions of a filtration area of 40 m 2 , a filtration volume of 0.65 m 3Under the conditions that the number of filter chambers is 49 pcs and the filtration pressure is 0.5 MPa, the washed slag is dehydrated to obtain a filter cake. Then, the filter cake is pre-cooled to -40 °C and pre-frozen at this temperature for 40 min. Finally, the vacuum is pumped to 75 Pa, and the temperature is raised to 70 °C at a heating rate of 10 °C / min, and dried at a constant temperature for 10 h until the moisture content of the filter cake is 3% to obtain the treated washed slag.

[0060] Example 10: Different from Example 1, in step S3, the treated washed slag and slag are mixed according to a mass ratio of 5:1 to obtain mixture B. Finally, an alkali activator is added to mixture B according to a mass ratio of mixture B:alkali activator of 10:1 and mixed evenly.

[0061] Example 11: Different from Example 1, in step S3, the treated washed slag and slag are mixed according to a mass ratio of 5:25 to obtain mixture B. Finally, an alkali activator is added to mixture B according to a mass ratio of mixture B:alkali activator of 50:1 and mixed evenly.

[0062] Example 12: Different from Example 1, in step S2, the heavy metals remaining in washing liquid A are captured before fractional crystallization. The capture method is: adding cage-like zeolite capture microspheres to washing liquid A according to a ratio of 0.07 g:50 mL, placing it on a horizontal shaker and constantly oscillating at 25 °C for 125 min.

[0063] The preparation method of the cage-like zeolite capture microspheres is: mixing rice husk ash and potassium silicate according to a mass ratio of 1:0.23 to obtain product A. Then, an aluminum-based compound is added to product A according to a mass ratio of product A:aluminum-based compound of 3.5:1 and mixed. It is put into a spherical mold and heated and solidified into a spherical shape at 70 °C to obtain product B. Finally, according to a spraying amount of 4 mL / cm 2 oleic acid is sprayed on the surface of product B, and then calcined at 500 °C for 2.5 h to obtain a zeolite-like material. The zeolite-like material and C-S-H gel are mixed according to a mass ratio of 4:2, and then put into an autoclave and hydrothermally treated at a temperature of 110 °C and a pressure of 5 MPa for 40 min to obtain a hydrothermal treatment product. The hydrothermal treatment product is cooled to room temperature and dried to obtain cage-like zeolite capture microspheres with a particle size of 80 - 120 μm; among them, the aluminum-based compound is composed of alumina and graphene material according to a mass ratio of 1:0.4.

[0064] Example 13: Different from Example 12, the capture method is: adding cage-like zeolite capture microspheres to washing liquid A according to a ratio of 0.05 g:40 mL, placing it on a horizontal shaker and constantly oscillating at 22 °C for 100 min.

[0065] Example 14: Different from Example 12, the method of capture treatment is as follows: Add the cage-like zeolite capture microspheres to the washing liquid A at a ratio of 0.1 g: 60 mL, place it on a horizontal shaker and keep it oscillating at a constant temperature of 27 °C for 150 min.

[0066] Example 15: Different from Example 12, mix rice husk ash and potassium silicate at a mass ratio of 1:0.2 to obtain product A. Then, add an aluminum-based compound to product A at a mass ratio of product A: aluminum-based compound of 3:1 and mix. Put it into a spherical mold and heat and cure it into a spherical shape at 60 °C to obtain product B. Finally, spray 2 Spray oleic acid on the surface of product B, then calcine it at 400 °C for 1.5 h to obtain a zeolite-like material. Mix the zeolite-like material and C-S-H gel at a mass ratio of 2:1, then put it into an autoclave and carry out hydrothermal treatment at a temperature of 100 °C and a pressure of 3 MPa for 20 min to obtain a hydrothermally treated product. Cool the hydrothermally treated product to room temperature and dry it to obtain cage-like zeolite capture microspheres with a particle size of 80 - 120 μm.

[0067] Example 16: Different from Example 12, mix rice husk ash and potassium silicate at a mass ratio of 1:0.25 to obtain product A. Then, add an aluminum-based compound to product A at a mass ratio of product A: aluminum-based compound of 4:1 and mix. Put it into a spherical mold and heat and cure it into a spherical shape at 80 °C to obtain product B. Finally, spray 2 Spray oleic acid on the surface of product B, then calcine it at 600 °C for 3 h to obtain a zeolite-like material. Mix the zeolite-like material and C-S-H gel at a mass ratio of 5:3, then put it into an autoclave and carry out hydrothermal treatment at a temperature of 120 °C and a pressure of 7 MPa for 60 min to obtain a hydrothermally treated product. Cool the hydrothermally treated product to room temperature and dry it to obtain cage-like zeolite capture microspheres with a particle size of 80 - 120 μm.

[0068] Example 17: Different from Example 12, the aluminum-based compound is composed of aluminum and graphene material at a mass ratio of 1:0.3.

[0069] Example 18: Different from Example 12, the aluminum-based compound is composed of aluminum hydroxide and graphene material at a mass ratio of 1:0.5.

[0070] Experimental Example: The description basis of this experimental example is the recording schemes in Examples 1 to 18, aiming to clarify the actual application effects of the present invention. The fracture toughness, compressive strength of the obtained hydraulic alkali-activated cementitious material, and the average removal rates of four heavy metals, namely Mn, Cu, Zn, and Pb, were respectively detected and recorded. The detection of compressive strength was carried out using a fully automatic flexural and compressive testing machine from Hebei Zhongke Beigong Experimental Instrument Co., Ltd., with the model DYE-300S. The pressure rate during the compressive strength test was 2400 N / s. The fracture toughness and the average removal rate of heavy metals were both measured by conventional methods.

[0071] 1. Explore the influence of the water washing and detoxification method on the properties of the obtained hydraulic alkali-activated cementitious material

[0072] Control Group 1: Different from Example 1, the soluble chlorine content after water washing was not limited.

[0073] Control Group 2: Different from Example 1, alumina was used to replace aluminum ash, and silica was used to replace slag.

[0074] Control Group 3: Different from Example 1, the drying treatment after dehydration was carried out by natural drying.

[0075] Conclusion: The test results of this exploration are as Figure 1 、 Figure 2 shown. From the comparison between Examples 1 to 3 and Control Group 1, it can be obtained that the content of soluble chlorine also has a certain influence on the properties of the hydraulic alkali-activated cementitious material, and too high a content of soluble chlorine will affect the compressive strength of the cementitious material product; from the comparison between Examples 1 to 3 and Control Group 2, it can be obtained that although replacing aluminum ash with alumina and slag with silica has little influence on the properties of the hydraulic alkali-activated cementitious material, the cost increases significantly; from the comparison between Example 1, Examples 8 to 9 and Control Group 3, it can be obtained that vacuum freeze-drying can sublimate water under low-temperature and low-pressure conditions. Compared with the slow evaporation of water during natural drying, it can better maintain the original microstructure of the water-washed slag, contribute to the formation of a more uniform and dense cementitious system, thereby improving its mechanical properties. At the same time, due to the good preservation of the microstructure by vacuum freeze-drying, the interfacial bonding between it and the slag and the alkali activator is stronger. When the cementitious material is subjected to external forces, the good interfacial bonding can effectively transfer stress and prevent the expansion of cracks, thereby improving the fracture toughness; thus, it can be concluded that Example 1 is the optimal scheme.

[0076] 2. Explore the influence of the capture treatment on the properties of the obtained hydraulic alkali-activated cementitious material

[0077] Control Group 4: Different from Example 12, the shape of the cage-like zeolite capture material was not limited during the curing process.

[0078] Control group 5: Different from Example 12, oleic acid is not sprayed on the surface of product B.

[0079] Control group 6: Different from Example 12, C-S-H gel and zeolite-like material are not mixed.

[0080] Conclusion: The test results of this exploration are as Figure 3 , Figure 4 , Figure 5 shown. By comparing Examples 1 to 18, it can be obtained that the hydraulic alkali-activated cementitious materials obtained in Examples 12 to 18 have better performance than those in Examples 1 to 11. And the preparation of zeolite-like microspheres in the cages of Examples 12 to 18 usually adopts an environmentally friendly synthesis method, reducing the negative impact on the environment. At the same time, due to the excellent adsorption, chelation and cross-linking effects of zeolite-like microspheres, they also have a high specific surface area and porosity. They can provide more active sites, thereby improving the adsorption efficiency of low-concentration heavy metals and improving the resource conversion effect; by comparing Examples 12 to 18 and Control group 4, it can be obtained that the average heavy metal removal rate of the hydraulic alkali-activated cementitious materials obtained in Control group 4 shows a decreasing trend. This is because the spherical structure of Examples 12 to 18 is conducive to increasing the fluidity and dispersibility of the material in subsequent processing. Compared with conventional irregularly shaped materials, the spherical cage-like zeolite capture microspheres may have a larger specific surface area, thus improving the adsorption effect on low-concentration heavy metals; by comparing Examples 12 to 18 and Control group 5, it can be obtained that spraying oleic acid on the surface of product B will increase the affinity of the material for low-concentration heavy metals, thereby improving its adsorption efficiency for low-concentration heavy metals; the reason is that oleic acid is a long-chain fatty acid, and its molecular structure contains a long hydrocarbon chain and a carboxylic acid group. During the calcination process, oleic acid can form a hydrophobic layer on the surface of product B, which helps to improve the hydrophobicity of the material, thereby enhancing its adsorption ability for low-concentration heavy metal ions.

[0081] By comparing Examples 12 to 18 and Control group 6, it can be obtained that the performance of the hydraulic alkali-activated cementitious material will also decline without adding C-S-H gel. This is because when the zeolite-like material is mixed with C-S-H gel and hydrothermally treated, C-S-H gel will fill into some pores of the zeolite-like material, making the entire adsorbent more stable in the process of long-term adsorption of low-concentration heavy metals; at the same time, C-S-H gel itself has certain ion exchange ability, and the zeolite-like material has the function of an ion sieve. When adsorbing low-concentration heavy metals, C-S-H gel can first adsorb a part of heavy metal ions through ion exchange, and then transfer them to the zeolite-like material for more stable fixation, so as to continuously and stably adsorb heavy metals. In summary, Example 12 is selected as the optimal solution.

Claims

1. A method for collaborative water washing and detoxification of fly ash from incineration of domestic waste and aluminum ash, characterized in that: The following steps are involved: S1. Cooperative washing First, the domestic waste incineration fly ash is pretreated to obtain pretreated fly ash, and the pretreated fly ash and aluminum ash are mixed according to an aluminum-silicon molar ratio of 1.5 to 3.5:1 to obtain a mixture A, and then the mixture A is added to water at a ratio of 1g:0.25 to 0.45mL, and the soluble salt is removed by stirring, and then the mixture is washed with water for multiple stages until the soluble chlorine content is ≤1%, to obtain a water washing liquid A; S2. Chloride recovery The water washing liquid A is subjected to flocculation and precipitation to remove heavy metals, and then the water washing liquid A after the heavy metals are removed is subjected to step-by-step crystallization to precipitate sodium chloride and potassium chloride, and the remaining liquid is the water washing liquid B, and then the water washing liquid B is dehydrated to obtain water washing residue, and then the water washing residue is dehydrated and dried to obtain treated water washing residue; S3. Preparation of hydraulic alkali-activated cementitious materials The treated washed slag is mixed with furnace slag at a mass ratio of 5:1 to 25 to obtain a mixture B, and finally an alkali activator is added to the mixture B at a mass ratio of mixture B to alkali activator of 10 to 50:1 and mixed to obtain a hydraulic alkali-activated cementitious material.

2. The method for collaborative water washing and detoxification of fly ash from incineration of domestic waste and aluminum ash as claimed in claim 1, characterized in that: In step S1, the pretreatment method is: subjecting the domestic waste incineration fly ash to microwave treatment for 1 to 10 minutes at a microwave power of 10 to 100 kW.

3. The method for collaborative water washing and detoxification of fly ash from incineration of domestic waste and aluminum ash as claimed in claim 1, characterized in that: In step S2, the flocculation precipitation method is: add a flocculant to the water washing liquid A at a ratio of 10 to 30 mg / L, and let it stand for 25 to 40 minutes. The flocculant is a mixture of any one of polyferric chloride, polyferric sulfate, polyaluminum chloride, polyaluminum silicate and polyacrylamide in equal proportions.

4. The method for collaborative water washing and detoxification of fly ash from incineration of domestic waste and aluminum ash as claimed in claim 3, characterized in that: In step S2, the heavy metals remaining in the water washing liquid A are captured before the fractional crystallization. The capture method is as follows: adding cage-shaped zeolite capture microspheres to the water washing liquid A in a ratio of 0.05-0.1 g: 40-60 mL, placing the mixture on a horizontal shaker and oscillating the mixture at a constant temperature of 22-27° C. for 100-150 min; The preparation method of the cage-shaped zeolite capture microspheres is as follows: rice husk ash and potassium silicate are mixed at a mass ratio of 1:0.2-0.25 to obtain product A, and then the aluminum-based compound is added to the product A at a mass ratio of product A to aluminum-based compound of 3-4:1 and mixed, and the product is placed in a spherical mold and heated at 60-80°C to solidify into a spherical shape to obtain product B, and finally the product is sprayed at a spray rate of 3-5 mL / cm 2 Oleic acid is sprayed on the surface of product B, and then calcined at 400-600°C for 1.5-3h to obtain a zeolite material. The zeolite material and CSH gel are mixed in a mass ratio of 2-5:1-3, and then put into an autoclave, and hydrothermally treated at a temperature of 100-120°C and a pressure of 3-7MPa for 20-60min to obtain a hydrothermally treated product. The hydrothermally treated product is cooled to room temperature and dried to obtain cage-shaped zeolite capture microspheres with a particle size of 80-120μm.

5. The method for collaborative water washing and detoxification of fly ash from incineration of domestic waste and aluminum ash as claimed in claim 4, characterized in that: The aluminum-based compound is composed of any one of aluminum, aluminum oxide, and aluminum hydroxide and graphene material in a mass ratio of 1:0.3-0.

5.

6. The method for collaborative water washing and detoxification of fly ash from incineration of domestic waste and aluminum ash as claimed in claim 1, characterized in that: In step S2, the fractional crystallization method is as follows: firstly, the water washing liquid A after the heavy metals are removed is heated to 90-100° C. for evaporation and concentration treatment, until the potassium chloride in the water washing liquid A after the heavy metals are removed reaches a saturated dissolved state, to obtain a concentrated liquid, then the concentrated liquid is cooled to allow sodium chloride crystals to precipitate, to obtain a remaining concentrated liquid; finally, an ethanol solvent with a concentration of 65-70% is added to the remaining concentrated liquid at a volume ratio of 10:1 to allow potassium chloride crystals to precipitate; and the separated sodium chloride crystals and potassium chloride crystals are dried at 28-32° C. respectively to obtain sodium chloride and potassium chloride products.

7. The method for collaborative water washing and detoxification of fly ash from incineration of domestic waste and aluminum ash as claimed in claim 1, characterized in that: In step S2, the method for dehydrating and drying the washed slag is: using a plate-and-frame filter press with a filtration area of ​​15 to 40 m 2 , Filtration volume is 0.25~0.65m 3 The water-washed slag is dehydrated under the conditions that the number of filter chambers is 19 to 49 pcs and the filtration pressure is 0.5 MPa to obtain a filter cake, and then the filter cake is pre-cooled to -20 to -40°C and pre-frozen at this temperature for 25 to 40 minutes, and finally evacuated to 55 to 75 Pa, and heated to 40 to 70°C at a heating rate of 5 to 10°C / min, and dried at a constant temperature for 5 to 10 hours until the moisture content of the filter cake is ≤3%, to obtain the treated water-washed slag.

8. The method for collaborative water washing and detoxification of fly ash from incineration of domestic waste and aluminum ash as claimed in claim 1, characterized in that: In step S3, the alkaline activator is one of sodium hydroxide, sodium silicate, sodium carbonate and sodium sulfate.

9. The method for collaborative water washing and detoxification of fly ash from incineration of domestic waste and aluminum ash as claimed in claim 1, characterized in that: In step S3, the slag is subjected to grinding and activation treatment to a particle size of 0.2 to 1 mm before the treated water-washed slag is mixed with the slag; in step S1, the multi-stage water washing is 2 to 4 stages of water washing, wherein, in the multi-stage water washing process, the first stage is washed with water, and each subsequent stage of water washing uses the washing liquid from the previous washing.

10. The method for collaborative water washing and detoxification of fly ash from incineration of domestic waste and aluminum ash as claimed in claim 1, characterized in that: The hydraulic alkali-activated cementitious material is applied in civil engineering, construction, filling and backfilling and other projects.

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