A fly ash resource product, its processing method and application

Abstract

This invention relates to the field of environmental protection technology, specifically to a fly ash resource product, its treatment method, and its application. This invention overcomes the problem of low fly ash resource recovery efficiency. The treatment method of this invention includes: fly ash undergoing three-stage water washing; during the first-stage water washing, disodium hydrogen phosphate, hydrochloric acid, and a washing liquid containing secondary washing filtrate are added to obtain first-stage washed fly ash and filtrate; the filtrate is subjected to pH adjustment, chemical reaction, and solid-liquid separation to obtain precipitate and pretreated salt solution; the salt solution is subjected to electrodialysis for salt separation and gradient crystallization to obtain NaCl, KCl crystals, and other salt products and recovered products; the third-stage washed fly ash is mixed with the precipitate, impurity salts, and mineral phase regulator, melted, and then cooled and quenched in water to obtain the fly ash resource product. This method improves salt recovery efficiency by combining graded water washing, precise precipitation, membrane separation, and gradient crystallization; the melting process stabilizes heavy metals; and the obtained product can be used in cement pavement or concrete, thus improving the resource utilization rate of fly ash.

Description

Technical Field

[0001] This invention relates to the field of environmental protection technology, specifically to a fly ash resource product and its treatment method and application. Background Technology

[0002] Fly ash is a fine particulate waste produced by high-temperature processes such as waste incineration and metallurgical smelting, with waste incineration fly ash being the most typical. Its composition is complex, containing inorganic minerals such as SiO2 and Al2O3, heavy metals such as Pb, Cr, and Cd, and soluble salts such as NaCl and KCl. Direct discharge of untreated fly ash will pollute soil, groundwater, and air, harming the ecosystem and human health. Therefore, fly ash must undergo stabilization treatment to solidify heavy metals, recover salts, and degrade toxic organic matter before it can be safely disposed of or utilized as a resource.

[0003] Current fly ash treatment faces a bottleneck in separation efficiency: on the one hand, heavy metals exist in various forms (water-soluble, mineral-encapsulated, etc.), and in high-salt systems, Cl... - It readily forms complexes with heavy metals, making it difficult to completely separate them using traditional precipitation and washing processes; on the other hand, the salt separation process is affected by ionic characteristics (such as Ca). 2+ (Blocking of membrane pores), low efficiency of multi-stage process connection, coupled with large fluctuations in fly ash composition and lag in manual control, easily lead to problems such as incomplete separation and high energy consumption, ultimately restricting the resource recovery efficiency of fly ash.

[0004] Therefore, a fly ash resource product, its processing method, and its application are proposed. Summary of the Invention

[0005] The purpose of this invention is to design a fly ash resource product, its processing method, and its application. The processing method includes: fly ash undergoing three-stage water washing; during the first-stage washing, disodium hydrogen phosphate, hydrochloric acid, and a washing liquid containing secondary washing filtrate are added to obtain first-stage washed fly ash and filtrate; the filtrate is subjected to pH adjustment, chemical reaction, and solid-liquid separation to obtain precipitate and pretreated salt solution; the salt solution is subjected to electrodialysis for salt separation and gradient crystallization to obtain NaCl, KCl crystals, and other salt products and recovered products; the third-stage washed fly ash is mixed with the precipitate, impurity salts, and mineral phase regulator, melted, and then cooled and quenched in water to obtain the fly ash resource product. This method improves salt recovery efficiency by combining staged water washing, precise precipitation, membrane separation, and gradient crystallization; the melting process stabilizes heavy metals; and the obtained product can be used in cement pavement or concrete, thus improving the utilization rate of fly ash resources.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] This invention provides a method for treating fly ash, comprising the following steps:

[0008] The fly ash is fed into a primary water washing mixing tank for primary water washing treatment to obtain primary water washed fly ash and primary washing filtrate.

[0009] The primary washing filtrate was subjected to solid-liquid separation to obtain precipitate and pretreated salt solution;

[0010] The pretreated salt solution was subjected to electrodialysis and gradient crystallization to obtain salt products and recovered products.

[0011] The primary water-washed fly ash is fed into a secondary water-washing mixing tank for secondary water washing treatment, resulting in secondary water-washed fly ash and secondary washing filtrate.

[0012] The secondary water-washed fly ash is fed into a tertiary water-washing mixing tank for tertiary water washing treatment to obtain tertiary water-washed fly ash and tertiary washing filtrate.

[0013] The fly ash resource product is obtained by melting the three-stage water-washed fly ash and the precipitated residue.

[0014] Preferably, the specific process of primary water washing is as follows: fly ash enters the primary water washing mixing tank, and disodium hydrogen phosphate, hydrochloric acid and washing liquid are added at the same time for primary water washing. After water washing, solid and liquid separation is performed to obtain primary water washed fly ash and primary washing filtrate. The washing liquid includes secondary washing filtrate, condensate and makeup water. The weight ratio of fly ash to washing liquid is 1:1-5.

[0015] Preferably, the specific process of solid-liquid separation is as follows: the pH of the primary washing filtrate is adjusted to 6.5-7.5, disodium hydrogen phosphate is added, and after the reaction, solid-liquid separation is performed to obtain primary precipitate and filtrate; the pH of the filtrate is adjusted to 8.5-9.5, sodium thiosulfate is added, and after the reaction, solid-liquid separation is performed to obtain secondary precipitate and pretreated salt solution; the precipitate residue includes primary precipitate and secondary precipitate.

[0016] Preferably, the specific process of electrodialysis salt separation and gradient crystallization is as follows: the pretreated salt solution enters the electrodialysis device, and the solution containing NaCl and the solution containing KCl are separated by ion exchange membranes; for the solution containing NaCl, NaCl crystals and condensate are obtained by evaporation crystallization; for the solution containing KCl, the temperature is first raised to 20℃-30℃ to evaporate to saturation, and then cooled to -5℃ to crystallize to obtain KCl crystals and the remaining solution; the remaining solution is flash-evaporated at 55℃-65℃ and then rapidly cooled to 0℃ to obtain impurity salts and desalinated water; the salt products include NaCl crystals and KCl crystals; the recovered products include condensate, impurity salts and desalinated water; the ion exchange membranes include sodium-selective membranes and potassium-selective membranes.

[0017] Preferably, the specific process of the secondary water washing treatment is as follows: the primary water washing fly ash is introduced into the secondary water washing stirring tank, and washing liquid is added for secondary water washing. After water washing, solid and liquid are separated to obtain secondary water washing fly ash and secondary washing filtrate. The washing liquid includes deacidification wastewater, desalination water and makeup water. The weight ratio of primary water washing fly ash to washing liquid is 1:1-5.

[0018] Preferably, the specific process of the three-stage water washing treatment is as follows: the secondary water washing fly ash is introduced into the tertiary water washing mixing tank, and washing liquid is added for tertiary water washing. After water washing, solid and liquid separation is performed to obtain tertiary water washing fly ash and tertiary washing filtrate. The tertiary washing filtrate is introduced into the reuse deacidification wastewater tank, and after incineration deacidification, liquid alkali is introduced to obtain deacidification wastewater. The washing liquid includes desalination water and makeup water. The weight ratio of secondary water washing fly ash to washing liquid is 1:1-5.

[0019] Preferably, the specific process of the melting treatment is as follows: the tertiary water-washed fly ash, precipitated slag, impurity salts and mineral phase modifier are mixed and then melted at a temperature of 1300℃ to obtain a melt; then the temperature is reduced to 800℃ at a rate of 20℃ / s, and then sprayed with water to obtain fly ash resource products; the weight ratio of mineral phase modifier to tertiary water-washed fly ash is 3:20, and the mineral phase modifier includes hematite Fe2O3 and calcium carbonate, with a weight ratio of hematite Fe2O3 to calcium carbonate of 1:1.

[0020] Another aspect of the present invention provides a fly ash resource product, which is obtained by subjecting fly ash to a three-stage water washing process, and finally molten water quenching the three-stage water-washed fly ash and precipitated slag.

[0021] Finally, this invention provides an application of fly ash resource products, which can be applied to cement pavements or concrete.

[0022] Fly ash contains soluble substances and other impurities. These two substances are separated after primary water washing. The soluble substances undergo solid-liquid separation to obtain a pretreated salt solution. The pretreated salt solution then undergoes electrodialysis and gradient crystallization to obtain NaCl and KCl crystals. Other impurities undergo secondary and tertiary water washing and are finally melted to obtain fly ash resource products. The aqueous solutions generated in the entire process are recycled into the tertiary water washing process.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] 1. The phosphate fractionation precipitation method employs a step-by-step precipitation strategy. First, disodium hydrogen phosphate, under specific pH conditions, causes calcium, fluoride, and sulfate ions to form a complex precipitate, preferentially removing these interfering ions. Then, the pH is adjusted and sodium thiosulfate is added to specifically precipitate heavy metal ions. This fractional treatment effectively avoids the problem of salt ion encapsulation, significantly improves the purity of salt crystals, and reduces calcium sulfate scaling during subsequent evaporation and crystallization processes, ensuring stable equipment operation and reducing maintenance costs.

[0025] 2. Electrodialysis pre-enrichment technology is introduced, using selective ion exchange membranes to efficiently separate the solution into sodium chloride enrichment and potassium chloride enrichment solutions, achieving preliminary and efficient separation of sodium and potassium ions. In the subsequent gradient temperature-controlled crystallization process, different temperature conditions are used for precise crystallization of the potassium chloride enrichment solution and the remaining solution, further separating potassium chloride and impurity salts. This method not only improves the recovery rate of potassium chloride but also reduces the residual potassium ion content in sodium chloride, significantly improving the separation efficiency of salt resources while reducing energy consumption in the crystallization process, making the entire salt separation process more efficient and energy-saving.

[0026] 3. By adding hematite and calcium carbonate to adjust the mineral phase composition and control the proportion of key elements, and then melting under a high-temperature reducing atmosphere, high-valence heavy metal ions are reduced to stable forms, generating stable phases such as iron-chromium spinel, thus enhancing the solidification effect of heavy metals. Subsequent gradient quenching promotes the formation of a microcrystalline glass structure in the melt, optimizing the product's microstructure. This treatment method significantly reduces the risk of heavy metal leaching and substantially improves the chemical stability of the product; simultaneously, the product can be applied to cement pavements or concrete, achieving high-value and resource-based utilization of fly ash. Attached Figure Description

[0027] Figure 1 This is a flowchart of the fly ash treatment method of the present invention. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] For details, please refer to [link / reference]. Figure 1 This invention provides a fly ash resource product, its processing method, and its application. The technical solution is as follows:

[0030] Example 1

[0031] Fly ash enters the primary water washing mixing tank, and disodium hydrogen phosphate, hydrochloric acid and washing liquid are added at the same time for primary water washing. After water washing, solid and liquid separation is performed to obtain primary water washed fly ash and primary washing filtrate. The washing liquid includes secondary washing filtrate, condensate and makeup water. The weight ratio of fly ash to washing liquid is 1:3.

[0032] The pH of the primary washing filtrate was adjusted to 7, disodium hydrogen phosphate was added, and after the reaction, solid-liquid separation was performed to obtain the primary precipitate and filtrate; the pH of the filtrate was adjusted to 9, sodium thiosulfate was added, and after the reaction, solid-liquid separation was performed to obtain the secondary precipitate and the pretreated salt solution; the precipitate residue included the primary precipitate and the secondary precipitate;

[0033] The pretreated salt solution enters an electrodialysis unit, where it is separated into NaCl-containing and KCl-containing solutions using ion exchange membranes. For the NaCl-containing solution, evaporation and crystallization yield NaCl crystals and condensate. For the KCl-containing solution, the temperature is first raised to 25°C and evaporated to saturation, then cooled to -5°C to crystallize and obtain KCl crystals and the remaining solution. The remaining solution is flash-evaporated at 60°C and then rapidly cooled to 0°C to obtain impurity salts and desalinated water. The salt products include NaCl crystals and KCl crystals; the recovered products include condensate, impurity salts, and desalinated water; the ion exchange membranes include sodium-selective and potassium-selective membranes.

[0034] The primary water-washed fly ash is fed into the secondary water-washing mixing tank, and washing liquid is added for secondary water washing. After water washing, solid and liquid are separated to obtain secondary water-washed fly ash and secondary washing filtrate. The washing liquid includes deacidification wastewater, desalination water and makeup water. The weight ratio of primary water-washed fly ash to washing liquid is 1:3.

[0035] Secondary water-washed fly ash is fed into a tertiary water-washing mixing tank, where washing liquid is added for tertiary water washing. After washing, solid-liquid separation is performed to obtain tertiary water-washed fly ash and tertiary washing filtrate. The tertiary washing filtrate is fed into a reuse deacidification wastewater tank, where it is incinerated to remove acid, and then liquid alkali is introduced to obtain deacidification wastewater. The washing liquid includes desalination water and makeup water. The weight ratio of secondary water-washed fly ash to washing liquid is 1:3.

[0036] The tertiary water-washed fly ash, precipitated slag, impurity salts, and mineral phase modifier were mixed and then melted at 1300℃ to obtain a melt. The melt was then cooled to 800℃ at a rate of 20℃ / s and then spray-quenched to obtain the fly ash resource product. The weight ratio of mineral phase modifier to tertiary water-washed fly ash was 3:20. The mineral phase modifier included hematite Fe2O3 and calcium carbonate, and the weight ratio of hematite Fe2O3 to calcium carbonate was 1:1.

[0037] Examples 2-8 refer to the parameter conditions in Example 1, with specific differences as shown in Table 1.

[0038] Table 1 Parameters and conditions for Examples 1-8

[0039]

[0040] Comparative Example 1 follows the same parameters and conditions as in Example 1, except that disodium hydrogen phosphate and hydrochloric acid are not added during the primary water washing process.

[0041] Comparative Example 2 follows the same parameters and conditions as in Example 1, except that the pH value is not adjusted during the solid-liquid separation process.

[0042] Comparative Example 3 follows the same parameters and conditions as in Example 1, except that calcium carbonate is used instead of disodium hydrogen phosphate and sodium thiosulfate in the solid-liquid separation process.

[0043] Comparative Example 4 follows the same parameters and conditions as in Example 1, except that disodium hydrogen phosphate and sodium thiosulfate are not added during the solid-liquid separation process.

[0044] Comparative Example 5 follows the same parameters and conditions as in Example 1, except that it does not undergo electrodialysis desalination and instead undergoes gradient crystallization directly.

[0045] Comparative Example 6 follows the same parameters and conditions as in Example 1, except that the remaining solution is not subjected to flash evaporation and rapid cooling during the gradient crystallization process.

[0046] Comparative Example 7 follows the same parameters and conditions as in Example 1, except that a secondary water washing treatment is not performed.

[0047] Comparative Example 8 follows the same parameters and conditions as in Example 1, except that it does not undergo a three-stage water washing process.

[0048] Experiment Example 1: Fly Ash Treatment Results

[0049] The moisture and soluble salt content in the three-stage water-washed fly ash of Examples 1-8 and Comparative Examples 1-8 were tested, and the results are shown in Table 2.

[0050] Table 2 Results of three-stage water washing fly ash in Examples 1-8 and Comparative Examples 1-8

[0051]

[0052] Table 2 shows that the soluble salt content in the examples is low. In Comparative Example 1, no disodium hydrogen phosphate and hydrochloric acid were added, and the first-stage water wash did not use hydrochloric acid to dissolve the slaked lime, resulting in a lower Ca content. 2+ Unable to participate in precipitation reactions in their free form; the absence of disodium hydrogen phosphate prevents calcium, fluoride, and sulfate ions from forming complex precipitates (such as fluorapatite and calcium sulfate), leaving a large amount of soluble salts in the fly ash. In Comparative Example 2, the pH was not controlled during the solid-liquid separation stage, preventing disodium hydrogen phosphate from reacting with Ca under weakly acidic conditions. 2+ F -A stable precipitate forms; sodium thiosulfate decomposes inefficiently under neutral conditions, resulting in incomplete precipitation of heavy metal sulfides. In Comparative Example 3, calcium carbonate can only provide Ca. 2+ While some heavy metals precipitate, fluoride and sulfate ions cannot be removed, and the hydroxide precipitate is loose and easily traps salt ions; the lack of sulfur ions causes heavy metals to remain in the form of soluble salts. In Comparative Example 4, no phosphate or sodium thiosulfate was added, relying entirely on physical water washing, which could not break the mineral-salt-heavy metal encapsulation structure in the fly ash. Soluble salts and heavy metal ions form stable complexes, and water washing can only remove surface free salts. In Comparative Example 5, direct gradient crystallization led to cross-contamination of sodium and potassium ions, with K ions trapped in the NaCl crystals. + The presence of Na in KCl solution + Residual, partially crystalline salts are carried over to the mother liquor during the reflux washing stage, increasing the salt load on the fly ash. In Comparative Example 6, impurities such as MgCl2 in the remaining mother liquor were not separated, and their high solubility led to the continuous dissolution of Mg from the fly ash during the reflux washing. 2+ This leads to the accumulation of impurities and salts, resulting in a decrease in washing efficiency. In Comparative Examples 7-8, omitting the secondary or tertiary washing process makes it easier to reach dissolution equilibrium and stop desalination during the process.

[0053] Experiment Example 2: Test of the content of various substances in the pretreated salt solution

[0054] The contents of soluble salts and other substances in the pretreated salt solutions of Examples 1-3 and Comparative Examples 1-4 were tested, and the results are shown in Table 3.

[0055] Table 3. Content of each substance in the pretreated salt solutions of Examples 1-3 and Comparative Examples 1-4

[0056]

[0057] Table 3 shows that in Comparative Example 1, the absence of disodium hydrogen phosphate and hydrochloric acid during the primary water washing process made it difficult to dissolve the quicklime in the fly ash, preventing calcium from fully participating in the subsequent precipitation reaction. Simultaneously, the lack of disodium hydrogen phosphate prevented sulfate ions from forming a precipitate and being effectively removed. Furthermore, the absence of hydrochloric acid hindered the precipitation of some heavy metals, leaving a large amount of impurities in the salt solution. In Comparative Example 2, the lack of pH adjustment during solid-liquid separation significantly interfered with the normal precipitation reaction. During primary precipitation, a suitable pH is essential for the formation of a stable precipitate from disodium hydrogen phosphate, calcium ions, and sulfate ions; pH miscontrol led to incomplete precipitation. In secondary precipitation, pH directly affected the efficiency of sodium thiosulfate decomposition to produce sulfur ions; an inappropriate pH prevented the sufficient precipitation of heavy metals. Comparative Example 3 used calcium carbonate instead of disodium hydrogen phosphate and sodium thiosulfate. While this precipitated some calcium ions, calcium carbonate could not remove sulfate ions and heavy metal ions. Due to the lack of targeted impurity removal capabilities, a large amount of impurities remained in the salt solution, indicating that calcium carbonate cannot replace the fractional precipitation function of disodium hydrogen phosphate and sodium thiosulfate, making it difficult to effectively purify the salt solution. Comparative Example 4 did not add disodium hydrogen phosphate and sodium thiosulfate during the solid-liquid separation process, missing the crucial chemical precipitation step. Calcium, sulfate, heavy metal, and other impurity ions were almost impossible to remove, resulting in extremely high impurity concentrations in the salt solution, severely impacting the overall treatment efficiency and effectiveness.

[0058] This scheme employs a staged impurity removal strategy, achieving targeted removal of impurity ions through the sequential addition of disodium hydrogen phosphate and sodium thiosulfate. Disodium hydrogen phosphate preferentially combines with calcium, fluoride, and sulfate ions to form precipitates, clearing obstacles for subsequent treatment; sodium thiosulfate targets heavy metal ions, forming stable sulfide precipitates and preventing interference between various ions during precipitation. Simultaneously, precise control of two pH levels creates an optimal environment for different precipitation reactions, enabling efficient synergy between chemical precipitation and physical separation, ensuring thorough impurity removal and providing pure raw materials for subsequent processes. The application of electrodialysis pre-salting technology utilizes the selectivity of ion exchange membranes to remove Na+. + K +Highly efficient separation significantly reduces the impurity content in subsequent crystallization solutions, lessening the burden on reflux washing. In the gradient crystallization stage, a flash evaporation and rapid cooling process refines the remaining solution, specifically removing impurity salts such as MgCl2, achieving deep recovery of salt resources. The organic combination of membrane separation and crystallization technology not only improves salt recovery rate but also optimizes the energy consumption and efficiency of the entire process, making salt recovery more efficient and economical. The three-stage washing adopts a counter-current washing mode, fully utilizing the dissolving capacity of the washing liquid based on the increasing salt concentration of each stage, significantly improving desalination efficiency. Simultaneously, emphasis is placed on the recycling of the washing liquid; the secondary washing liquid is reused in the primary washing, and the tertiary washing liquid is reused after deacidification treatment. This reduces fresh water consumption while enhancing the dissolution effect of alkali metal ions in fly ash, achieving dual optimization of efficient water resource utilization and fly ash desalination. This solution realizes the high-value utilization of salt resources, significantly increasing resource added value. In terms of fly ash reduction, the soluble salt content of fly ash is significantly reduced after three-stage water washing, which meets the requirements of the melting process for low-salt raw materials, effectively avoids problems such as melt foaming and equipment corrosion caused by high salt, reduces environmental pressure, and truly achieves the dual goals of resource recovery and reduction, thus combining environmental and economic benefits.

[0059] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for treating fly ash, characterized in that: The processing method includes the following steps: The fly ash is fed into a primary water washing mixing tank for primary water washing treatment to obtain primary water washed fly ash and primary washing filtrate. The primary washing filtrate is subjected to solid-liquid separation to obtain a precipitate and a pretreated salt solution. The specific process of solid-liquid separation is as follows: the pH value of the primary washing filtrate is adjusted, disodium hydrogen phosphate is added, and after reaction, solid-liquid separation is performed to obtain a primary precipitate and filtrate; the pH value of the filtrate is adjusted, sodium thiosulfate is added, and after reaction, solid-liquid separation is performed to obtain a secondary precipitate and the pretreated salt solution; the precipitate includes the primary precipitate and the secondary precipitate. The pretreated salt solution undergoes electrodialysis and gradient crystallization to obtain salt products and recovered products. The specific processes of electrodialysis and gradient crystallization are as follows: the pretreated salt solution enters an electrodialysis device, where ion exchange membranes are used to separate a NaCl-containing solution and a KCl-containing solution; for the NaCl-containing solution, evaporation crystallization is used to obtain NaCl crystals and condensate; for the KCl-containing solution, the temperature is first raised to saturation, followed by cooling crystallization to obtain KCl crystals and the remaining solution; the remaining solution is flash-evaporated and then rapidly cooled to obtain impurity salts and desalinated water; the salt products include the NaCl crystals and KCl crystals; the recovered products include the condensate, the impurity salts, and the desalinated water. The primary water-washed fly ash is fed into a secondary water-washing mixing tank for secondary water washing treatment to obtain secondary water-washed fly ash and secondary washing filtrate. The secondary water-washed fly ash is fed into a tertiary water-washing mixing tank for tertiary water washing treatment to obtain tertiary water-washed fly ash and tertiary washing filtrate. The fly ash resource product is obtained by melting the three-stage water-washed fly ash and the precipitated residue. The fly ash is processed to obtain the salt product and the fly ash resource product.

2. The method for treating fly ash according to claim 1, characterized in that: The specific process of the primary water washing treatment is as follows: the fly ash enters the primary water washing stirring tank, and the disodium hydrogen phosphate, hydrochloric acid and washing liquid are added at the same time to carry out primary water washing. After water washing, solid-liquid separation is performed to obtain the primary water washed fly ash and the primary washing filtrate. The washing solution includes the secondary washing filtrate, condensate, and makeup water.

3. The method for treating fly ash according to claim 1, characterized in that: The specific process of the secondary water washing treatment is as follows: the primary water washing fly ash is introduced into the secondary water washing stirring tank, and washing liquid is added for secondary water washing. After water washing, solid and liquid are separated to obtain the secondary water washing fly ash and the secondary washing filtrate. The washing liquid includes deacidification wastewater, desalination water and makeup water.

4. The method for treating fly ash according to claim 1, characterized in that: The specific process of the three-stage water washing treatment is as follows: the secondary water washing fly ash is introduced into the tertiary water washing stirring tank, washing liquid is added for tertiary water washing, and solid-liquid separation is performed after water washing to obtain the tertiary water washing fly ash and the tertiary washing filtrate. The three-stage washing filtrate is fed into a reuse deacidification wastewater tank, and after incineration to remove acid, liquid alkali is introduced to obtain deacidified wastewater; the washing liquid includes desalinated water and makeup water.

5. The method for treating fly ash according to claim 1, characterized in that: The specific process of the melting treatment is as follows: the three-stage water-washed fly ash, the precipitated slag, the impurity salt and the mineral phase regulator are mixed and then melted to obtain a melt; then the mixture is cooled and then sprayed with water to obtain the fly ash resource product; the mineral phase regulator includes hematite Fe2O3 and calcium carbonate.

6. A fly ash resource product, characterized in that: The fly ash resource product is obtained by the processing method described in any one of claims 1-5; the fly ash resource product is obtained by subjecting fly ash to three-stage water washing treatment, and finally molten water quenching the three-stage water-washed fly ash and precipitated slag.

7. An application of a fly ash resource product, characterized in that, The fly ash resource product is obtained by the processing method described in any one of claims 1-5; the fly ash resource product can be applied to cement pavement or concrete.

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