Fly ash-based fluidified solidified material, and preparation method and application thereof

Abstract

This invention discloses a fly ash-based fluidized solidification material, its preparation method, and its application. The fluidized solidification material is obtained by curing fly ash with a curing agent composed of an alkali-activated material, a cementing material, a water-reducing agent, and a filler. The alkali-activated material is sodium hydroxide or carbide slag; the cementing material is granulated blast furnace slag powder; the filler is desulfurized gypsum; and the water-reducing agent is sodium hexametaphosphate, magnesium lignosulfonate, or a mixture of both. The alkali-activated material has a synergistic activating effect on the Ca-Si-Al active components in the cementing material, promoting the formation of hydrated calcium silicate gel and ettringite crystal phases, strengthening the material's mechanical properties, and increasing the density of the pore structure. The water-reducing agent optimizes the hydration reaction process, reduces the water-ash ratio, and inhibits the system's tendency to shrink and crack. The desulfurized gypsum partially replaces the alkali-activated material, filling the material's pores, improving the material's unconfined compressive strength, and reducing the material's permeability coefficient. It can be used as an ex-situ barrier material with excellent mechanical properties, impermeability, and durability.

Description

Technical fields:

[0001] This invention belongs to the field of environmental protection materials, specifically relating to a fly ash-based fluidized solidification material, its preparation method, and its application. Background technology:

[0002] With rapid economic development, China has witnessed a surge in industrial solid waste. Industrial solid waste in my country is characterized by its diverse types, massive volume, and low resource utilization rate. In 2022, the total amount of industrial solid waste reached 4.11 billion tons, with a comprehensive utilization rate of only 57%, and there is a risk of cross-media pollution. As the world's largest producer and consumer of coal, the widespread use of coal in thermal power generation has led to a large accumulation of coal combustion byproducts, among which fly ash has the highest annual output. Fly ash is a siliceous aluminous material formed by high-temperature calcination, mainly containing oxides such as SiO2 and Al2O3. The current accumulated stockpile has exceeded 3 billion tons, with a comprehensive utilization rate of less than 70%. It is particularly noteworthy that coastal industrial core areas face significant pressure in disposing of fly ash generated from thermal power generation due to high energy demand. Although the country is promoting energy structure transformation, coal will still dominate in the short term. Traditional disposal methods such as landfill and open-air storage not only occupy land resources, but also pose a continuous pollution threat to soil and water bodies because the heavy metal pollutants enriched in fly ash can be easily leached and migrated through rainwater. This highlights the urgency of industrial solid waste treatment and resource utilization.

[0003] Currently, in contaminated site remediation, landfill seepage prevention, and industrial pollution source isolation, barrier materials, as key technologies for blocking pollutant diffusion, have long relied on cement-based materials, modified bentonite, and geomembranes. However, these traditional materials have significant drawbacks: First, the high energy consumption and large-scale use of cement-based materials lead to a surge in carbon emissions, which is not environmentally friendly; second, traditional materials such as cement have insufficient long-term seepage prevention and durability; third, under contaminated conditions, unmodified bentonite-based materials are difficult to meet seepage prevention performance requirements, while modified materials are expensive; fourth, geomembranes are easily damaged during construction due to their thinness, and improper joint treatment during construction may lead to leakage, affecting the seepage prevention effect.

[0004] Some studies have focused on large stockpiles of fly ash, using industrial solid waste to solidify it. However, the following key issues still need to be addressed: 1) Heavy metal leaching risk: Fly ash contains various heavy metal pollutants. When solidified fly ash is used for pollution barrier, whether the heavy metal leaching concentration meets environmental standards still needs further verification; 2) Mechanical property optimization: When the fly ash content is too high, the mechanical properties of the material may decrease significantly, which will directly affect its engineering applicability and long-term stability; 3) Permeability control: The porous nature of fly ash may make it difficult for the permeability coefficient of the solidified material to meet the barrier performance requirements. It is necessary to reduce permeability by optimizing the material structure or adding modifiers to ensure its barrier effect.

[0005] Moreover, how to efficiently couple multi-source solid waste solidifiers with fly ash, and through component optimization and process innovation, prepare barrier materials that combine fluid construction characteristics, rapid self-curing ability, excellent seepage prevention performance, and good environmental adaptability, has become the key to solving solid waste disposal problems and improving the sustainability of pollution prevention and control projects. Summary of the Invention:

[0006] Purpose of the invention: In order to overcome the shortcomings of the prior art, the present invention proposes a fly ash-based fluidized solidification material, its preparation method and application. The fly ash-based fluidized solidification material uses multi-source solid waste solidification agents such as sodium hydroxide, carbide slag, desulfurization gypsum, and mineral powder to solidify fly ash stored in power plants to form a fluidized engineering barrier material with barrier properties.

[0007] This invention achieves fluidized solidification of untreated fly ash from power plants by regulating the combination of various materials, breaking through the technical barriers of multi-source solid waste synergistic resource utilization. It not only realizes the efficient resource utilization of fly ash, but also significantly reduces material costs and carbon emissions, ensuring environmental safety and engineering reliability. It endows the fluidized solidification material with excellent construction performance and long-term barrier performance, and is suitable for scenarios such as surface cover barrier, bottom seepage prevention, and vertical barrier, providing a green, economical and high-performance solution for ex-situ barrier engineering.

[0008] Technical solution: To achieve the above objectives, the present invention adopts the following technical solution:

[0009] A fly ash-based fluidized solidification material comprises: fly ash, a solidifying agent, and water; the solidifying agent includes a main material and a water-reducing agent; the main material consists of an alkali-activating material, a cementitious material, and a filler; the alkali-activating material and the cementitious material account for 1 / 5 of the dry weight of the fly ash; the total weight of the alkali-activating material and the filler is 1 / 6 to 1 / 4 of the dry weight of the cementitious material; the filler accounts for 5% of the dry weight of the main material of the solidifying agent; the water-reducing agent accounts for 0.5% to 1% of the dry weight of the main material of the solidifying agent; the amount of water is adjusted according to the required fluidity and setting time of the solidified material. The resulting solidified material has a fluidity of 160 mm to 220 mm, and its unconfined compressive strength is not less than 0.8 MPa after 28 days of curing; the heavy metal leaching concentration of this solidified material meets the Class IV groundwater standard.

[0010] The fly ash used is untreated fly ash from the fly ash stockpile of a coastal coal-fired power plant; the cementing material is granulated blast furnace slag powder (hereinafter referred to as mineral powder); the specifications of the mineral powder, carbide slag, and desulfurization gypsum shall not be less than 200 mesh; the sodium hydroxide is industrial grade. The alkali activator is one or more of sodium hydroxide and carbide slag; the water-reducing agent is sodium hexametaphosphate (abbreviated as SHMP), magnesium lignosulfonate (abbreviated as MI), or a mixture of the two (mixed in equal proportions); the filler is desulfurization gypsum. Fly ash and cementitious materials contain a large amount of calcium, silicon, and aluminum. The curing agent solidifies the fly ash based on the alkali-activated reaction mechanism. By regulating the synergistic activation effect of the alkali activator on the Ca-Si-Al active components in the cementitious materials, it promotes the formation of hydrated calcium silicate gel and ettringite crystal phase, thereby strengthening the mechanical properties of the material and densifying the pore structure. The water-reducing agent optimizes the hydration reaction process and inhibits the tendency of the system to shrink and crack by reducing the water-ash ratio. The filler, desulfurized gypsum, fills the pores of the material, improves the 28-day and 90-day unconfined compressive strength of the material, and reduces the permeability coefficient of the material.

[0011] This invention also provides the use of fly ash-based fluidized solidified material as an ex-situ barrier material, for blocking the migration of heavy metal pollutants in fly ash stockpiles. The permeability coefficient of this barrier, when uncontaminated, must not exceed 10. -9 m / s, the permeability coefficient after contamination must not exceed 10. -8 This invention provides a fly ash-based fluidized solidification material that, while enabling large-scale fly ash disposal, can be adapted to the construction of barrier structures in various engineering contexts using an off-site construction method. It meets the mechanical performance requirements of achieving 0.8 MPa at 28 days and maintaining a strength below 10 m / s in engineering applications. -9The material meets the following requirements: firstly, it has a seepage prevention performance of m / s; secondly, the fly ash-based fluidized solidification material can control the setting time by adjusting the content of alkaline activator according to different construction distance requirements, thus better adapting to long-distance transportation construction scenarios; and thirdly, the fly ash-based fluidized solidification material can still maintain a permeability coefficient of less than 10 for 28 days even under long-term heavy metal pollution. -8 The seepage prevention performance requirement is [m / s]. Desulfurized gypsum is used to partially replace the alkali activator material, further reducing the material price while maintaining the original mechanical properties, seepage prevention performance, and durability. The cement used is ordinary Portland cement with a strength grade of not less than 42.5.

[0012] The present invention also provides a method for preparing the above-mentioned fly ash-based fluidized solidification material, comprising the following steps:

[0013] Step 1) Weigh out the alkali activating material, cementing material, filler, and water-reducing agent according to the proportions, add them to the powder mixer, and stir thoroughly to make them evenly mixed to form a curing agent powder;

[0014] Step 2) Weigh the amount of water at the preset flow rate and add it to the mixer along with the curing agent powder, and mix thoroughly to form a curing agent slurry;

[0015] Step 3) Add fly ash to the well-mixed curing agent slurry and stir at high speed with a mixer until the mixture is uniform to form a fluidized curing material;

[0016] Step 4) Pour the well-stirred fluidized solidified material into the cylindrical mold.

[0017] The density of granulated blast furnace slag powder is not less than 2.8 g / cm³. 3 Specific surface area not less than 400m² 2 / kg, after 28 days of standard curing, the activity index is not less than 95%, the fluidity ratio is not less than 95%, and the moisture content is less than 1%;

[0018] The density of untreated fly ash from the power plant is 1.55 g / cm³. 3 The specific surface area is not less than 357.6 m². 2 / kg, fineness 49.2%, loss on ignition 4.1%, strength activity index 62.0%, moisture content 46%; calcium hydroxide content in carbide slag not less than 75%, mesh size not less than 200 mesh, moisture content less than 1%; calcium sulfate dihydrate content in desulfurized gypsum not less than 90%, mesh size not less than 200 mesh, moisture content less than 1%; pure sodium hydroxide content in sodium hydroxide not less than 80%, moisture content less than 1%; phosphorus pentoxide content in sodium hexametaphosphate not less than 70%, degree of polymerization not less than 12, mesh size not less than 60 mesh; lignin content in magnesium lignosulfonate not less than 50%, bulk density not less than 0.3 g / cm³3 The moisture content is less than 7%.

[0019] Beneficial effects: Compared with the prior art, the present invention has the following advantages:

[0020] 1) The fly ash-based fluidized solidification material obtained in this invention can control its setting time by adjusting the component ratios and combinations of different materials, thereby adapting to the needs of different conveying distances and engineering scenarios. This allows the fluidized solidification material to be flexibly applied in various scenarios such as surface cover barrier, bottom seepage prevention, and vertical barrier, effectively isolating surface water or groundwater from pollutants and preventing the diffusion and migration of pollutants, thus playing a key role in environmental protection, pollution remediation, and soil improvement. Its fluidity and solidification properties can be optimized and adjusted according to actual engineering needs to ensure stability and construction efficiency under different construction conditions.

[0021] 2) The fly ash-based fluidized solidification material obtained in this invention can meet the industry standards for mechanical properties and impermeability under continuous heavy metal pollution conditions, demonstrating its excellent barrier effect. By optimizing the material formulation, the fluidized solidification material can maintain its stable mechanical strength, impermeability, and durability, making it highly adaptable to water and soil pollution control projects.

[0022] 3) The heavy metal leaching concentration of the fly ash-based fluidized solidification material obtained in this invention meets the Class IV standard for groundwater, indicating that the heavy metals in untreated fly ash can be solidified / stabilized and will not cause secondary pollution to the environment.

[0023] 4) The fly ash-based fluidized solidification material obtained in this invention improves the mechanical properties, impermeability, and durability of the barrier material by using desulfurized gypsum to partially replace the alkali-activated material, thereby reducing costs and making it more economical.

[0024] 5) The fly ash-based fluidized solidification material obtained in this invention is mainly composed of general industrial solid waste, belonging to a green material that can be utilized as a resource. It has good environmental friendliness and will not have a negative impact on the surrounding environment. Compared with traditional high-energy-consuming and high-carbon-emission silicate cement materials, it can significantly absorb fly ash and can be used as an ex-situ barrier material in various environments. The cost is greatly reduced, exhibiting more prominent green and low-carbon characteristics and good environmental sustainability. Attached Figure Description

[0025] Figure 1 This is a particle size distribution diagram of untreated fly ash from a power plant used in Example 1. Detailed Implementation

[0027] The technical solution of the present invention will be described in detail below with reference to the embodiments:

[0028] Example 1

[0029] The following are examples of fly ash-based fluidized bed curing materials. Specific components and dosages are shown in Table 1 (the units for each component in Table 1 are dry weight ratios, dimensionless). The alkali-activated material, combined with the cementitious material and filler, constitutes the main curing agent material. The main curing agent material is 1 / 5 of the dry weight of the fly ash. The flowability of the fly ash-based fluidized bed curing material is 160 mm (refer to the "Technical Standard for Engineering Application of Premixed Fluidized Bed Curing Soil" (DBJ51 / T188-2022)).

[0030] Table 1

[0031]

[0032] Control group 1 used ordinary Portland cement as the curing agent (cement purchased from a cement plant in Nanjing, Jiangsu Province, grade 42.5). In the control example, the dry weight ratio of cement to fly ash was 1 / 5. The fluidity of the fly ash-based fluidized bed material was determined according to the "Technical Standard for Engineering Application of Premixed Fluidized Bed Soil" (DBJ51 / T188-2022). Specific components and contents are shown in Table 2.

[0033] Table 2

[0034]

[0035] In this embodiment, the content of various oxides in the untreated fly ash from the power plant is shown in Table 3.

[0036] Table 3

[0037]

[0038] In practical engineering applications, unconfined compressive strength is a key indicator for evaluating the mechanical properties of rigid barrier materials, and is of great significance. Unconfined compressive strength refers to the maximum compressive strength that a material sample can withstand under unconfined conditions (i.e., without any external lateral constraints). For barrier materials, unconfined compressive strength directly affects their performance and long-term stability in engineering applications. In this embodiment, the barrier test adopted a cylindrical mold casting method, and the samples were demolded after different curing periods, followed by unconfined compressive strength testing. The test data in Table 4 shows the strength performance of different materials under different curing conditions. Analysis of the test results shows that the fly ash-based fluidized solidified materials obtained from samples 1 to 12 have a significant advantage in unconfined compressive strength compared with the fluidized solidified material made by conventional cement curing in control group 1, as shown in Table 4. The results indicate that the fly ash-based fluidized solidified material of the present invention can more effectively maintain its shape and withstand greater pressure under pressure, thus demonstrating its potential and superiority as a barrier in practical engineering.

[0039] Table 4

[0040]

[0041] In the actual risk control process of industrial contaminated sites, the permeability coefficient of the barrier is one of the key indicators for evaluating its effectiveness and reliability. According to the "Technical Specification for Vertical Barriers in Industrial Contaminated Sites" (HG / T 20715-2020), the permeability coefficient of an uncontaminated rigid vertical barrier should not exceed 10. -9 m / s; however, under the influence of pollutants, the permeability coefficient of the barrier should be maintained at no more than 10. -8 Within the range of m / s. This requirement ensures that the barrier can effectively prevent the migration of pollutants during long-term use, maintaining the safety of groundwater and soil. The experimental data in Table 5 show that the fly ash-based fluidized bed material provided by this invention has significantly better permeability performance than traditional cement-based solidification materials. Furthermore, the difference in permeability coefficient between the two is approximately one order of magnitude, indicating that the fly ash-based fluidized bed material provided by samples 1-12 in Example 1 has lower permeability in its barrier performance, effectively preventing the penetration and diffusion of pollutants, further enhancing its application value as a barrier material. Its excellent permeability performance provides strong support for its widespread application in the risk control of contaminated sites, especially in situations requiring efficient isolation of pollutants.

[0042] Table 5

[0043]

[0044] Analysis of the reasons: The superior unconfined compressive strength and permeability of the fly ash fluidized solidification material developed in this invention compared to traditional solidification materials are primarily due to its unique composition and chemical reaction mechanism. Firstly, under the activation of an alkali activator, the activity of elements such as calcium, silicon, and aluminum in fly ash and mineral powder can be significantly increased. These elements undergo hydration reactions under alkali activation conditions, generating a large amount of cementitious substances, such as hydrated aluminosilicates and ettringite. These products enrich the internal structure of the material during the solidification of sludge, reducing its permeability coefficient and providing higher strength. The introduction of a water-reducing agent effectively optimizes the hydration reaction process, suppressing the system's tendency to shrink and crack by reducing the water-ash ratio. Simultaneously, the fly ash stockpiled along the coast contains sulfate ions, which can react with calcium ions in the material to form ettringite. ettringite is a very strong mineral; its crystal structure effectively fills the pores in the material, reducing porosity and increasing the material's density, thereby significantly enhancing its compressive strength and reducing its permeability coefficient. Overall, the active components in fly ash and mineral powder interact to form a multi-layered, dense structural network, which greatly improves the mechanical and impermeability properties of the solidified material, giving it higher stability and durability in engineering applications.

[0045] To systematically evaluate the durability characteristics of fly ash-based fluidized solidification materials, this invention employs a wet-dry cycle accelerated aging test method, simulating alternating wet and dry environmental conditions. Samples cured for 28 days under standard conditions were placed in a 40°C oven for 48 hours, then removed and cooled at room temperature for 1 hour. After drying, the samples were placed in a plastic storage box, and sufficient seawater was added (simulating a wet-dry cycle scenario), ensuring the surface was covered with seawater. The samples were then immersed in a standard curing chamber for 23 hours to complete one wet-dry cycle. A total of 10 cycles were performed, and mass, strength, and permeability tests were conducted after each cycle. The mass loss rate, strength loss rate, and permeability coefficient loss rate after wet-dry cycles are shown in Tables 6-8.

[0046] Table 6

[0047]

[0048] Table 7

[0049]

[0050] Table 8 Permeability coefficient loss rate after wet-dry cycles

[0051]

[0052] (Note: In this invention, mass loss rate refers to the amount of mass reduction compared to a sample that has not undergone wet-dry cycling; strength loss rate refers to the amount of strength reduction compared to a sample that has not undergone wet-dry cycling; permeability loss rate refers to the amount of permeability increase compared to a sample that has not undergone wet-dry cycling.)

[0053] Analysis of the reasons: Alkali-activated materials form a highly cross-linked three-dimensional network structure through the alkali activation reaction. This structure is more robust and denser than the hydration products of traditional cement (such as calcium silicate hydrate). The alumina tetrahedral structure forms strong chemical bonds during hardening, making the overall structure of the material more stable and resistant to wet-dry cycles. Therefore, alkali-activated materials generally have higher strength and are less susceptible to large-scale damage during wet-dry cycles. Simultaneously, alkali-activated materials have lower porosity and smaller pore size distribution, especially the very dense network structure formed under strong alkali activation conditions, reducing the penetration of moisture and other substances. This allows alkali-activated materials to maintain a low permeability coefficient after wet-dry cycles, effectively preventing the intrusion of moisture or harmful substances. In contrast, although the hydration products of cement materials (such as calcium silicate hydrate, CSH gel) also form a certain network structure, this structure is relatively loose and easily affected by environmental factors such as humidity changes and temperature fluctuations. During wet-dry cycles, the hydration products of cement may experience microcrack propagation and structural loosening, leading to a decrease in strength. Furthermore, due to the relatively loose microstructure and large pores of the hydration products in cement, and the incomplete hydration process, cement materials typically exhibit high permeability after wet-dry cycles. The larger pore structure and irregular hydration products of cement provide more channels for water and other substances, resulting in a higher permeability coefficient.

[0054] The fly ash used in this invention is untreated fly ash produced by power plants. Its leachate contains numerous heavy metal pollutants, all exceeding the Class IV standard of the "Groundwater Quality Standard" (GB / T 14848-2017). Leaching tests were conducted to verify whether the sludge fluidized bed solidification material could solidify the heavy metals in the fly ash without causing secondary pollution to the environment. The pollutants exceeding the standards in the fly ash are shown in Table 9.

[0055] Table 9

[0056]

[0057] For specific leaching methods, refer to the "Horizontal Oscillation Method for Leaching Toxicity of Solid Waste" (HJ557-2010). The leaching concentration of heavy metals in fly ash-based fluidized solidified materials is shown in Table 10.

[0058] Table 10

[0059]

[0060] Analysis of the reasons: Fly ash leachate typically contains various heavy metals. Fly ash-based fluidized bed solidification materials, due to their unique structure and chemical properties, exhibit superior performance in the fixation and stabilization of heavy metals. Firstly, the geopolymer possesses a compact network structure and a special three-dimensional framework, enabling it to effectively encapsulate heavy metal ions within it, thereby inhibiting their migration and diffusion. This structural feature not only increases the adsorption capacity for heavy metals but also improves its stability during long-term use. Secondly, the alumina tetrahedral structure also plays a crucial role in the fixation of heavy metals. The aluminum ions in the alumina tetrahedron are trivalent ions, which combine with four oxygen atoms to form the highly electronegative [AlO(OH)4]⁻ ions. In this structure, the high charge density of aluminum ions allows them to form strong electrostatic attraction with other cations, providing favorable conditions for the adsorption of heavy metal cations. To maintain the charge balance of the reaction system, Al³⁺ in the alumina tetrahedron combines with other metal cations, further promoting the adsorption and fixation of heavy metals.

[0061] In summary, this invention discloses a green, low-carbon, and high-performance fly ash-based fluidized solidification material and its preparation method, which can be applied to various scenarios such as surface cover barrier, bottom seepage prevention, and vertical barrier. Compared with traditional cement-based barrier materials, it has better mechanical and seepage prevention properties, and can maintain good seepage prevention performance even under heavy metal pollution conditions. Furthermore, the setting time can be controlled by adjusting the content of the alkaline activator according to different construction scenarios and transportation distances, meeting different engineering needs. Secondly, compared with traditional curing agents, the curing agent materials used in this invention are all resource-recyclable materials, with lower costs and adjustable costs according to engineering scenarios, exhibiting environmentally friendly characteristics.

[0062] It should be specifically stated that the above description is merely a preferred embodiment of the present invention, and its core purpose is to explain the technical principles. For those skilled in the art, without departing from the core principles of the present invention, necessary adaptive adjustments, structural optimizations, and functional expansions can be made to the technical solution based on actual application scenarios. Any modifications and improvements that meet the equivalence principle stipulated in the Patent Law—"achieving substantially the same function and achieving substantially the same effect by substantially the same means"—and do not depart from the design concept and technical route of the present invention, should be included within the scope of protection of the claims of the present invention.

Claims

1. A fly ash-based fluidized solidification material, characterized in that, include: Fly ash, curing agent, and water; The curing agent includes the main material and the water-reducing agent; The main materials include: alkali activating materials, cementing materials, and fillers; the amount of main materials added is 1 / 5 of the dry weight of fly ash; the total weight of alkali activating materials and fillers is 1 / 6 to 1 / 4 of the dry weight of cementing materials. The filler accounts for 5% of the dry weight of the curing agent's main material; The water-reducing agent accounts for 0.5% to 1% of the dry weight of the main curing agent material; The amount of water used should be adjusted according to the required fluidity and setting time of the curing material; The fluidity of the obtained cured material is 160 mm to 220 mm, and the unconfined compressive strength is not less than 0.8 MPa after 28 days of curing; the heavy metal leaching concentration of the cured material meets the Class IV standard for groundwater.

2. The fly ash-based fluidized solidification material according to claim 1, characterized in that, The fly ash mentioned is untreated fly ash from the fly ash stockpile of a coastal coal-fired power plant; Granulated blast furnace slag powder was selected as the cementing material. The alkaline activator is selected from one or a mixture of sodium hydroxide and carbide slag; The water-reducing agent is one of sodium hexametaphosphate and magnesium lignosulfonate, or a mixture of both in equal amounts; Desulfurized gypsum was selected as the filler. The curing agent solidifies fly ash based on the alkali-activated reaction mechanism. By regulating the synergistic activation effect of the alkali-activated material on the Ca-Si-Al active components in the cementitious material, it promotes the formation of hydrated calcium silicate gel and ettringite crystal phase, thereby enhancing the mechanical properties of the material and densifying the pore structure. The water-reducing agent optimizes the hydration reaction process and inhibits the tendency of the system to shrink and crack by reducing the water-ash ratio. The filler, desulfurized gypsum, fills the pores of the material, improves the 28-day and 90-day unconfined compressive strength of the material, and reduces the permeability coefficient of the material.

3. The fly ash-based fluidized solidification material according to claim 2, characterized in that: The granulated blast furnace slag powder, carbide slag, and desulfurized gypsum shall have a specification of not less than 200 mesh; the sodium hydroxide shall be industrial grade.

4. The fly ash-based fluidized solidification material according to claim 2, characterized in that: The density of granulated blast furnace slag powder is not less than 2.8 g / cm³. 3 Specific surface area not less than 400m² 2 / kg, with an activity index of not less than 95% and a fluidity ratio of not less than 95% after 28 days of standard curing, and a moisture content of less than 1%; the density of fly ash is 1.55 g / cm³. 3 The specific surface area is not less than 357.6 m². 2 / kg, fineness 49.2%, loss on ignition 4.1%, strength activity index 62.0%, moisture content 46%; calcium hydroxide content in carbide slag not less than 75%, mesh size not less than 200 mesh, moisture content less than 1%; calcium sulfate dihydrate content in desulfurized gypsum not less than 90%, mesh size not less than 200 mesh, moisture content less than 1%; pure sodium hydroxide content in sodium hydroxide not less than 80%, moisture content less than 1%; phosphorus pentoxide content in sodium hexametaphosphate not less than 70%, degree of polymerization not less than 12, mesh size not less than 60 mesh; lignin content in magnesium lignosulfonate not less than 50%, bulk density not less than 0.3 g / cm³ 3 The moisture content is less than 7%.

5. The use of the fly ash-based fluidized solidified material according to claim 1 as an ex-situ barrier material.

6. The use as described in claim 5, characterized in that, This material is used to block the migration of heavy metal pollutants in fly ash stockpiles. The permeability coefficient of the barrier material must not exceed 10 when it is uncontaminated. -9 m / s, the permeability coefficient after contamination must not exceed 10. -8 m / s.

7. The method for preparing a fly ash-based fluidized solidification material according to claim 1, characterized in that, Includes the following steps: Step 1) Weigh out the alkali activating material, cementing material, filler, and water-reducing agent according to the proportions, add them to the powder mixer, and stir thoroughly to make them evenly mixed to form a curing agent powder; Step 2) Weigh the amount of water at the preset flow rate and add the curing agent powder to the mixer, and mix thoroughly to form a curing agent slurry; Step 3) Add fly ash to the well-mixed curing agent slurry and stir at high speed with a mixer until the mixture is uniform to form a fluidized curing material; Step 4) Pour the well-stirred fluidized solidified material into the cylindrical mold.

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