A fluidized solidification soil solidifying agent for solidifying harmful heavy metal ions

Abstract

The present application relates to the field of environmental protection technology, and discloses a kind of solidified soil solidifying agent for solidifying harmful heavy metal ions, and the solidifying agent is composed of 85-90 parts of alkaline composite excitation core component and 10-15 parts of acid potential control bentonite carrier.It is made of industrial waste residue, low-temperature calcined synthesis silicate, clinker and calcium oxide, and the carrier is inorganic aluminum salt modified calcium-based bentonite.The present application forms a microcapsule structure with acid shell and alkaline core through dry mixing coating process, effectively inhibits the early transient hydration of the solidifying agent, and prolongs the construction operation time of the solidified soil.At the same time, the C-A-S-H gel and ettringite excited after the shell breaks are used to efficiently lock heavy metal ions through physical adsorption and crystal lattice isomorphism replacement mechanism, achieving excellent solidification effect and long-term stability, and high utilization rate of industrial solid waste, green and environmentally friendly.

Description

Technical Field

[0001] This invention relates to the field of environmental protection technology, and in particular to a fluidized solidified soil solidifier for solidifying harmful heavy metal ions. Background Technology

[0002] Currently, with the acceleration of industrialization and the large-scale development of mineral resources, the remediation of heavy metal-contaminated soil has become a global environmental challenge. Heavy metals such as lead and cadmium left in industrial wastelands, mine tailings ponds, and urban brownfields pose a severe challenge to ecological security. Among numerous remediation methods, solidification / stabilization technology has become the mainstream choice for contaminated site treatment due to its advantages such as short treatment cycle, low economic cost, and mature construction technology. This technology aims to physically or chemically fix pollutants in the soil medium by adding solidifying agents, reducing the risk of their migration into the environment.

[0003] For the remediation of soil contaminated with heavy metals, fluidized bed solidification technology is commonly used in engineering projects. This process involves mixing contaminated soil, water, and cementing materials in a specific ratio to prepare a slurry with a certain degree of fluidity. Commonly used cementing materials include ordinary silicate cement, lime, or fly ash. After the materials are evenly dispersed using mixing equipment, they are backfilled into foundation pits, mine pits, and other similar areas using pumps or self-leveling methods. Driven by hydration reactions, the slurry gradually solidifies and hardens, forming a solidified body with a certain strength. This process utilizes the cementing effect of hydration products to encapsulate soil particles, thereby blocking the diffusion path of heavy metal ions.

[0004] However, existing curing agent technologies still have many limitations in practical applications. Traditional strong alkaline activators have excessively rapid hydration rates, which can easily cause the fluid soil slurry to thicken rapidly during transportation. This flash-setting phenomenon greatly increases pumping resistance, not only shortening the construction window but also frequently causing pipeline blockage accidents. On the other hand, conventional cement-based materials mainly rely on physical encapsulation for the curing of heavy metals. This bonding method is not stable. Once exposed to acid rain erosion or changes in the groundwater environment, the cured heavy metals are prone to leaching again, raising questions about long-term environmental safety. In addition, relying solely on high-energy-consuming cement clinker does not conform to the low-carbon trend, while simple industrial waste residue mixing is difficult to guarantee the uniformity and stability of the curing effect due to large fluctuations in raw material composition. Summary of the Invention

[0005] The purpose of this invention is to provide a curing agent for solidifying fluidized soil containing harmful heavy metal ions, which solves the problems of poor flowability and easy flash solidification of fluidized soil during construction caused by existing curing agents, as well as the insufficient long-term stability and easy leaching of heavy metal solidification products in acidic environments.

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

[0007] This invention provides a fluidized solidified soil solidifier for solidifying harmful heavy metal ions, which is made of components comprising the following parts by weight:

[0008] The system comprises 85-90 parts of an alkaline composite activation core component and 10-15 parts of an acidic potential-controlled bentonite carrier. The alkaline composite activation core component is made from raw materials comprising the following weight percentages: 60%-70% industrial waste-derived materials and 30%-40% low-temperature calcined synthetic aluminosilicates. Based on the sum of the mass of the industrial waste-derived materials and the low-temperature calcined synthetic aluminosilicates, 5%-10% rapid-hardening sulfoaluminate cement clinker is also added, and calcium oxide powder is added to adjust the total CaO / SiO2 molar ratio of the system. The acidic potential-controlled bentonite carrier is calcium-based bentonite modified with inorganic aluminum salts.

[0009] By adopting the above technical solution, due to the core-shell structure design of the bentonite carrier coated with alkaline composite excitation core components by acid potential regulation, and the specific low-temperature calcination mineral components, the present invention achieves the synergistic effect of physical coating slow release and chemical mineral polymerization solidification.

[0010] This invention utilizes the principles of mechanochemistry to construct a microcapsule structure with an acidic outer shell and an alkaline inner core. The solidification mechanism of heavy metal ions in fluidized solidified soil mainly includes the following three stages:

[0011] Acid buffering and long-lasting sustained-release stage: The surface of the bentonite carrier modified with inorganic aluminum salts is rich in acidic sites (H). + and Al 3+ This process forms a dense, acidic outer shell. When the solidifying agent is initially added to the fluidized soil slurry, this acidic shell neutralizes the strong alkalinity that momentarily dissolves from the surface of the core components, forming a localized acidic buffer layer. This effectively inhibits the premature reaction between the alkaline activator and soil particles, ensuring the fluidity and pumpability of the solidified soil during the initial construction phase. As the hydration reaction proceeds, water gradually penetrates the shell, and the acidic shell gradually disintegrates under the erosion of the alkaline environment, achieving a delayed release of the core activating components.

[0012] Controlled hydration and gel network construction stage: After core release, aluminosilicates are synthesized at low temperature as highly active precursors. These precursors undergo synergistic hydration reactions with industrial waste-derived materials (slag, fly ash) in the alkaline and sulfate environment provided by calcium oxide and sulfoaluminate cement clinker. The low-temperature calcination process places the aluminosilicates in a high-energy metastable state (high degree of amorphization), making them easy to depolymerize and recombine. The reaction system rapidly generates a large amount of ettringite (AFt) crystals and low-calcium-to-silica hydrated calcium silicate (CSH) and hydrated calcium aluminosilicate (CASH) gels. The precisely controlled CaO / SiO2 molar ratio ensures the density and stability of the gel network, avoiding expansion and cracking due to excessive calcium content or insufficient strength due to insufficient calcium content.

[0013] Multidimensional Heavy Metal Solidification and Stabilization Stage: This invention solidifies heavy metal ions through a triple mechanism of physical encapsulation, chemical adsorption, and lattice substitution.

[0014] Physical adsorption and interlayer trapping: After the bentonite carrier disintegrates, it disperses in the matrix. Its layered structure and large specific surface area have a significant effect on Pb adsorption. 2+ Cd 2+ Strong physical adsorption occurs between heavy metal ions;

[0015] Chemical bonding and precipitation: OH groups in the system - CO3 2- It forms insoluble hydroxide or carbonate precipitates with heavy metal ions;

[0016] Isomorphic substitution: This is the core curing mechanism of this invention. During the growth of CASH gel and ettringite crystals, heavy metal ions (such as Pb) are... 2+ Zn 2+ Due to the small difference in ionic radii, they can isomorphically substitute Ca in the crystal lattice. 2+ Or Al 2+ The location allows heavy metals to be permanently locked inside the mineral lattice, thereby reducing the leaching toxicity of heavy metals and achieving long-term stability.

[0017] Preferably, the industrial waste residue derived material is composed of S95 grade slag powder and F-type Class II fly ash, and the mass ratio of S95 grade slag powder to F-type Class II fly ash is 3:1-4:1.

[0018] By adopting the above technical solution, the high potential hydraulicity of slag powder provides early strength, and the morphological effect of fly ash improves rheology and provides later pozzolanic reactivity. The two form a dense packing at a specific ratio, reducing the porosity of the solidified body and further physically blocking the migration path of heavy metal ions.

[0019] Preferably, the amount of calcium oxide powder added is such that the total CaO / SiO2 molar ratio of the alkaline composite activating core component system is controlled between 1.2 and 1.8.

[0020] By employing the above technical solution, the degree of polymerization of CSH gel in the hydration product was ensured. Within this modulus range, the generated gel structure tends to form long chain or network structures, achieving an optimal balance between physical encapsulation and chemical complexation of heavy metal ions.

[0021] Preferably, the low-temperature calcined synthetic aluminosilicate is made from raw materials comprising the following weight percentages: 65%-75% kaolin, 15%-20% calcium hydroxide, and 10%-15% waste glass powder; and the preparation method of the low-temperature calcined synthetic aluminosilicate includes: ball milling and activating the mixed raw materials, calcining them at 750-850°C for 2.0-3.0 hours, followed by forced air cooling treatment and grinding.

[0022] By employing the above technical solution, waste glass powder is introduced as a flux and combined with calcium hydroxide to promote the dehydroxylation of kaolinite at low temperatures (750-850℃) and form a defect-state metakaolinite-calcium glass structure. Forced extraction freeze-crystallizes this high-temperature disordered structure, preventing the recrystallization of crystalline minerals, thereby maximizing the pozzolanic activity of the material.

[0023] Preferably, the mass ratio of Al2O3 / SiO2 in the mixed raw materials for low-temperature calcination synthesis of aluminosilicates is 0.6-0.8; the forced air quenching cooling rate is ≥60℃ / min, and the specific surface area of ​​the obtained powder is 505-535 m². 2 / kg.

[0024] By adopting the above technical solutions, a higher aluminum-to-silicon ratio is conducive to the formation of an aluminum-rich gel network, which increases the number of sites for isomorphic substitution of heavy metal ions; a high cooling rate and a high specific surface area provide more reaction contact surfaces, accelerating the hydration process of the core components after the shell breaks.

[0025] Preferably, the preparation method of the acid potential-controlled bentonite carrier includes the following steps: dispersing calcium-based bentonite in water to make a slurry, slowly adding aluminum sulfate solution dropwise, such that the dry basis of aluminum sulfate added is 10%-20% of the bentonite mass; adjusting the pH value of the system to maintain at 3.0-4.0 during the dropwise addition process; heating the slurry to 60-80℃, stirring at a constant temperature and allowing it to stand for aging, and obtaining powder with a particle size of 45-75μm after drying and grading.

[0026] By adopting the above technical solution, the hydrolysis of aluminum sulfate introduces a large amount of active aluminum hydroxyl polymers into the bentonite interlayer and surface, which not only endows the carrier with a suitable acid buffering capacity, but also enhances the electrostatic adsorption force between the bentonite and alkaline core particles by changing the Zeta potential of the bentonite surface, which is conducive to the formation of a uniform and firm coating layer.

[0027] Preferably, the concentration of the aluminum sulfate solution is 1.0-2.0 mol / L; the constant temperature stirring time is 2.0-4.0 hours, and the standing aging time is 12-24 hours.

[0028] By adopting the above technical solution, sufficient ion exchange between aluminum ions and the bentonite interlayer is ensured, resulting in a more uniform distribution of acidic sites and avoiding coating failure caused by excessively strong or weak local acidity.

[0029] Preferably, the curing agent is prepared by a dry mixing pre-dispersion coating process, which specifically includes: putting the alkaline composite activation core component and the acidic potential-controlled bentonite carrier into a mixer, pre-mixing at a speed of 300-500 rpm for 2-3 minutes; then increasing the speed to 1500-2500 rpm and maintaining high-speed stirring for 10-15 minutes, using mechanical force and electrostatic adsorption to coat the acidic potential-controlled bentonite carrier onto the surface of the alkaline composite activation core component.

[0030] By adopting the above technical solution and using stepped speed control, low-speed mixing is first used to achieve macroscopic uniformity, and then high-speed stirring is used to generate shear heat and mechanical force, which causes the fine sheet-like bentonite carrier to soften, spread and embed on the surface of the core particles, forming a true physical microcapsule structure, rather than a simple loose adsorption.

[0031] Preferably, the acidic potential-regulated bentonite carrier forms a microcapsule outer shell in the curing agent, and the alkaline composite-excited core component forms the core of the microcapsule structure.

[0032] By adopting the above technical solution, the microstructural characteristics of the product were clarified. This structure achieves full-cycle performance optimization, including stable transport and storage of the curing agent, slow setting in the early stage of construction, strong strength development in the later stage, and long-term locking of heavy metals.

[0033] Preferably, the preparation of the alkaline composite activation core component specifically includes: first, mixing industrial waste residue-derived materials with low-temperature calcined synthetic aluminosilicates, determining the oxide composition of the mixture using an X-ray fluorescence spectrometer, calculating and adding calcium oxide powder and fast-hardening sulfoaluminate cement clinker according to the target total CaO / SiO2 molar ratio, and then placing the resulting mixture in a grinding device for co-grinding activation treatment.

[0034] By adopting the above technical solutions, the technical challenge of large fluctuations in the composition of industrial waste residue raw materials was overcome. XRF online monitoring and dynamic batching ensured precise control over the chemical modulus of each batch of product; co-grinding not only improved mixing uniformity but also increased the lattice defects on the surface of each component through mechanical activation, thereby enhancing the reactivity and early strength of the curing agent.

[0035] In summary, the present invention has at least one of the following beneficial technical effects:

[0036] 1. This invention constructs a microcapsule structure with acid-potential-controlled bentonite as the shell and an alkaline composite activating component as the core through a dry-mix pre-dispersion coating process. The acidic shell forms a local pH buffer barrier in the early stage of slurry mixing, effectively inhibiting the instantaneous dissolution and violent reaction of the alkaline activator. This solves the problem of flash solidification and rapid loss of fluidity in fluidized soil caused by traditional strong alkaline solidifying agents, prolongs the pumpable time of the fluidized solidified soil, and achieves a dual balance between excellent construction fluidity and subsequent strength activation.

[0037] 2. This invention utilizes low-temperature calcination to synthesize aluminosilicates as a high-energy precursor, combined with rapid-hardening sulfoaluminate cement clinker, to induce the formation of a large amount of ettringite and a low calcium-to-silica ratio CASH gel in the hydration system. This specific mineral phase combination not only blocks the migration pathways of heavy metals through its dense physical structure, but also promotes the growth of Pb. 2+ Cd 2+ The heavy metal ions undergo isomorphic substitution in the crystal lattice, permanently locking them in the mineral crystal structure. Combined with the interlayer adsorption of the bentonite carrier, this reduces the leaching toxicity of heavy metals and ensures the long-term environmental safety of the solidified body.

[0038] 3. This invention employs a preparation process combining batch-wise raw material testing with dynamic molar ratio control, effectively overcoming the technical bottleneck of large fluctuations in the chemical composition of industrial waste-derived materials. This process involves analyzing the basic chemical composition of each batch of raw materials, adjusting the dosage of regulating components such as calcium oxide accordingly, and precisely locking in the optimal CaO / SiO2 molar ratio of the system. This reduces production control costs while ensuring highly uniform and stable product performance, achieving high-proportion, high-value-added resource utilization of bulk industrial solid wastes such as slag, fly ash, and waste glass powder. It possesses the dual advantages of low-carbon environmental protection and economic applicability. Detailed Implementation

[0039] Preparation Examples 1-6:

[0040] Preparation of aluminosilicates by low-temperature calcination (Preparation Examples 1-3):

[0041] Preparation Example 1:

[0042] This preparation example aims to verify the effects of low-temperature calcination conditions and high-alumina formulations on mineral activity.

[0043] Raw material composition: Weigh 750g (75%) of kaolin, 150g (15%) of industrial grade calcium hydroxide, and 100g (10%) of waste glass powder. After mixing, XRF analysis showed that the mass ratio of Al2O3 / SiO2 in the mixture was approximately 0.8.

[0044] Ball milling activation: Place the above mixture in a planetary ball mill, set the ball-to-material ratio to 5:1, the rotation speed to 300 r / min, and grind for 0.5 hours to fully homogenize the material.

[0045] Low-temperature calcination: The ground powder is placed in a muffle furnace and heated to 750°C at a rate of 5°C / min. It is then held at this temperature for 2.0 hours.

[0046] Post-processing: Immediately after the heat preservation period, the material was removed and subjected to forced air cooling (cooling rate approximately 60℃ / min). After cooling to room temperature, it was ground and passed through a 200-mesh sieve, and the specific surface area was measured to be 510 m². 2 / kg. Thus, the low-temperature calcination synthetic aluminosilicate of Preparation Example 1 is obtained.

[0047] Preparation Example 2:

[0048] This preparation example represents the recommended best implementation of the present invention, aiming to achieve the optimal balance between activity and cost.

[0049] Raw material composition: Weigh 700g (70%) of kaolin, 175g (17.5%) of industrial grade calcium hydroxide, and 125g (12.5%) of waste glass powder. After mixing, XRF analysis showed that the mass ratio of Al2O3 / SiO2 in the mixture was approximately 0.70.

[0050] Ball milling activation: Place the above mixture in a planetary ball mill, set the ball-to-material ratio to 8:1, the rotation speed to 400 r / min, and grind for 0.8 hours.

[0051] Low-temperature calcination: The ground powder is placed in a muffle furnace and heated to 800°C at a rate of 8°C / min. It is held at this temperature for 2.5 hours to ensure that the kaolin is completely dehydroxylated and not over-sintered.

[0052] Post-processing: Immediately after the heat preservation period, the material was removed and subjected to forced air cooling. After cooling to room temperature, it was ground and passed through a 200-mesh sieve, and the specific surface area was measured to be 535 m². 2 / kg. Thus, the low-temperature calcination synthetic aluminosilicate of Preparation Example 2 is obtained.

[0053] Preparation Example 3:

[0054] This preparation example aims to verify the lattice stability under high-temperature boundary conditions and high-calcium formulations.

[0055] Raw material composition: Weigh 650g (65%) of kaolin, 200g (20%) of industrial grade calcium hydroxide, and 150g (15%) of waste glass powder. After mixing, XRF analysis showed that the mass ratio of Al2O3 / SiO2 in the mixture was approximately 0.6.

[0056] Ball milling activation: The above mixture is placed in a planetary ball mill, the ball-to-material ratio is set to 10:1, the rotation speed is 500 r / min, and the milling is carried out for 1.0 hour to introduce lattice distortion by using high mechanical force.

[0057] Low-temperature calcination: The ground powder is placed in a muffle furnace and heated to 850°C at a rate of 10°C / min. It is then held at this temperature for 3.0 hours.

[0058] Post-processing: Immediately after the heat preservation period, the material was removed and subjected to forced air cooling. After cooling to room temperature, it was ground and passed through a 200-mesh sieve. The specific surface area was measured to be 505 m² / kg. This yielded the low-temperature calcined synthetic aluminosilicate of Preparation Example 3.

[0059] Preparation of bentonite carriers controlled by acid potential (Preparation Examples 4-6):

[0060] Preparation Example 4:

[0061] This preparation example prepares a carrier with a low density of acidic sites to verify the minimum effectiveness of the microcapsule structure.

[0062] Pulping: Weigh 1000g of calcium-based bentonite, add it to 4000g of deionized water, and stir to disperse evenly.

[0063] Acid impregnation: Prepare an aluminum sulfate solution with a concentration of 1.0 mol / L. Measure an appropriate amount of this solution so that the amount of aluminum sulfate added (dry basis mass ratio) is 10% of the bentonite mass.

[0064] Reaction control: The aluminum sulfate solution was slowly added dropwise to the bentonite slurry, and the pH of the system was adjusted to be around 4.0 by adding a small amount of dilute sulfuric acid during the process.

[0065] Aging and drying: The slurry was heated to 60°C and stirred at a constant temperature for 2.0 hours, then allowed to stand for 12 hours for aging. Subsequently, it was filtered by pressure and dried at 105°C.

[0066] Classification: The dried material was air-jet pulverized and classified, and powder with a particle size between 45-75 μm was collected. This yielded the acid potential-controlled bentonite carrier of Preparation Example 4.

[0067] Preparation Example 5:

[0068] This preparation example represents the recommended optimal carrier treatment method, which has a suitable acid buffering capacity.

[0069] Pulping: Weigh 1000g of calcium-based bentonite, add it to 4000g of deionized water, and stir to disperse evenly.

[0070] Acid impregnation: Prepare an aluminum sulfate solution with a concentration of 1.5 mol / L. Measure an appropriate amount of this solution so that the amount of aluminum sulfate added (dry basis mass ratio) is 15% of the mass of bentonite.

[0071] Reaction control: The aluminum sulfate solution was slowly added dropwise to the bentonite slurry, while the pH of the system was adjusted to be maintained at around 3.5.

[0072] Aging and drying: The slurry was heated to 70°C and stirred at a constant temperature for 3.0 hours, then allowed to stand for 18 hours to age. Subsequently, it was filtered by pressure and dried at 105°C.

[0073] Classification: The dried material was air-jet pulverized and classified, and powder with a particle size between 45-75 μm was collected. This yielded the acid potential-controlled bentonite carrier of Preparation Example 5.

[0074] Preparation Example 6:

[0075] This preparation example demonstrates the preparation of a carrier with a high density of acidic sites, and verifies its strong inhibitory (long-release) effect on alkali-induced reactions.

[0076] Pulping: Weigh 1000g of calcium-based bentonite, add it to 4000g of deionized water, and stir to disperse evenly.

[0077] Acid impregnation: Prepare an aluminum sulfate solution with a concentration of 2.0 mol / L. Measure an appropriate amount of this solution so that the amount of aluminum sulfate added (dry basis mass ratio) is 20% of the bentonite mass.

[0078] Reaction control: The aluminum sulfate solution was slowly added dropwise to the bentonite slurry, while the pH of the system was adjusted to be maintained at around 3.0.

[0079] Aging and drying: The slurry was heated to 80°C and stirred at a constant temperature for 4.0 hours, then allowed to stand for aging for 24 hours. Subsequently, it was filtered by pressure and dried at 105°C.

[0080] Classification: The dried material was air-jet pulverized and classified, and powder with a particle size between 45-75 μm was collected. This yielded the acid potential-controlled bentonite carrier of Preparation Example 6.

[0081] Examples 1-3:

[0082] Example 1:

[0083] This embodiment provides a fluidized solidified soil solidifier for solidifying harmful heavy metal ions, comprising the following steps:

[0084] Preparation of alkaline composite activation core components:

[0085] S95 grade slag powder and Class II fly ash (F type) were selected as industrial waste derivative materials, with a mass ratio of 3:1. The low-temperature calcined synthetic aluminosilicate prepared in Preparation Example 1 was selected. 70% of the industrial waste derivative material and 30% of the low-temperature calcined synthetic aluminosilicate were weighed out according to mass percentage. After mixing the above raw materials, their oxide composition was analyzed by XRF, and an appropriate amount of calcium oxide powder was added to adjust the total CaO / SiO2 molar ratio of the system to be precisely controlled at 1.2. Based on the total mass of the matrix, an additional 5% of rapid-hardening sulfoaluminate cement clinker was added. All components were mixed evenly and ground to obtain an alkaline composite activated core powder.

[0086] Dry-mix pre-dispersion coating:

[0087] The acid-potential-controlled bentonite carrier prepared in Example 4 was selected. Alkaline composite excitation core powder and acid-potential-controlled bentonite carrier were weighed in a mass ratio of 90:10. Both were added to a Henschel high-speed mixer and premixed at 300 rpm for 2 minutes. The speed was then increased to 1500 rpm and maintained at high speed for 10 minutes, utilizing mechanical force and electrostatic adsorption to coat the acid-potential-controlled bentonite onto the core surface. After mixing, the mixture was discharged, yielding the curing agent for the fluidized solidified soil of Example 1.

[0088] Example 2:

[0089] This embodiment provides a fluidized solidified soil solidifier for solidifying harmful heavy metal ions, which is a preferred embodiment of the present invention and includes the following steps:

[0090] Preparation of alkaline composite activation core components:

[0091] S95 grade slag powder and Class II fly ash (F type) were selected as industrial waste derivative materials, with a mass ratio of 3.5:1. The low-temperature calcined synthetic aluminosilicate obtained in Preparation Example 2 was selected. 65% of the industrial waste derivative material and 35% of the low-temperature calcined synthetic aluminosilicate were weighed out according to mass percentage. After mixing the above raw materials, their oxide composition was analyzed by XRF, and an appropriate amount of calcium oxide powder was added to adjust the total CaO / SiO2 molar ratio of the system to be precisely controlled at 1.5. Based on the total mass of the matrix, 7.5% of rapid-hardening sulfoaluminate cement clinker was additionally added. All components were mixed evenly and ground to obtain an alkaline composite activated core powder.

[0092] Dry-mix pre-dispersion coating:

[0093] The acid-potential-controlled bentonite carrier prepared in Preparation Example 5 was selected. Alkaline composite excitation core powder and acid-potential-controlled bentonite carrier were weighed in a mass ratio of 87.5:12.5. Both were added to a Henschel high-speed mixer and premixed at 400 rpm for 2.5 minutes. The speed was then increased to 2000 rpm and maintained at high speed for 12.5 minutes, utilizing mechanical force and electrostatic adsorption to coat the acid-potential-controlled bentonite onto the core surface. After mixing, the material was discharged, yielding the curing agent for the fluidized solidified soil of Example 2.

[0094] Example 3:

[0095] This embodiment provides a fluidized solidified soil solidifier for solidifying harmful heavy metal ions, comprising the following steps:

[0096] Preparation of alkaline composite activation core components:

[0097] S95 grade slag powder and Class II fly ash (F type) were selected as industrial waste derivative materials, with a mass ratio of 4:1. The low-temperature calcined synthetic aluminosilicate obtained in Preparation Example 3 was selected. 60% of the industrial waste derivative material and 40% of the low-temperature calcined synthetic aluminosilicate were weighed out according to mass percentage. After mixing the above raw materials, their oxide composition was analyzed by XRF, and an appropriate amount of calcium oxide powder was added to adjust the system, ensuring the total CaO / SiO2 molar ratio was precisely controlled at 1.8. Based on the total mass of the matrix, an additional 10% of rapid-hardening sulfoaluminate cement clinker was added. All components were mixed evenly and ground to obtain an alkaline composite activated core powder.

[0098] Dry-mix pre-dispersion coating:

[0099] The acid-potential-controlled bentonite carrier prepared in Example 6 was selected. Alkaline composite excitation core powder and acid-potential-controlled bentonite carrier were weighed in a mass ratio of 85:15. Both were added to a Henschel high-speed mixer and premixed at 500 rpm for 3 minutes. The speed was then increased to 2500 rpm and maintained at high speed for 15 minutes, utilizing mechanical force and electrostatic adsorption to coat the acid-potential-controlled bentonite onto the core surface. After mixing, the mixture was discharged, yielding the fluidized solidified soil curing agent of Example 3.

[0100] Comparative Examples 1-5:

[0101] Comparative Example 1:

[0102] Compared with Example 2, the difference is that in the second step of dry mixing pre-dispersion coating, an equal mass of unmodified natural calcium-based bentonite was used instead of the acid potential-controlled bentonite carrier prepared in Example 5, and all other aspects were the same.

[0103] Comparative Example 2:

[0104] Compared with Example 2, the difference lies in the preparation process. This comparative example does not perform the second step of high-speed dry mixing pre-dispersion coating. Instead, the alkaline composite activating core powder obtained in the first step and the acidic potential-controlled bentonite carrier obtained in Example 5 are directly put into a regular mixer and simply mixed at a speed of 40 rpm for 10 minutes. No microcapsule coating structure is formed. All other aspects are the same.

[0105] Comparative Example 3:

[0106] Compared with Example 2, the difference is that in the preparation of the alkaline composite activation core component in the first step, an equal mass of Class F II fly ash was used to directly replace the low-temperature calcined synthetic aluminosilicate prepared in Example 2, while the rest were the same.

[0107] Comparative Example 4:

[0108] Compared with Example 2, the difference is that in the preparation of the alkaline composite activation core component in the first step, the ratio of each raw material is adjusted, and no additional calcium oxide is added for adjustment, so that the total CaO / SiO2 molar ratio of the system is controlled at 0.8, and the rest are the same.

[0109] Comparative Example 5:

[0110] Compared with Example 2, the difference is that the curing agent of the present invention is replaced entirely with a cement-based curing agent in the prior art, specifically a mixture of commercially available P.O42.5 ordinary Portland cement and industrial-grade sodium sulfide (added at 2% of the cement mass).

[0111] Test Examples 1-5:

[0112] Test Example 1: Construction Performance and Rheological Properties Test of Fluidized Solidified Soil

[0113] Experimental materials and sample preparation:

[0114] All test cases used artificially prepared heavy metal contaminated simulated soil as the reference soil. The simulated soil matrix was silty clay taken from a construction foundation pit, dried, pulverized, and sieved through a 5mm sieve. Lead nitrate, cadmium nitrate, and zinc nitrate solutions were added to the soil sample to artificially simulate heavy metal contamination, with the initial heavy metal ion contents controlled as follows: Pb 1200 mg / kg, Cd 80 mg / kg, and Zn 1500 mg / kg. The soil moisture content was adjusted to 35%, which was then used as the wet soil to be treated.

[0115] The sample preparation process is as follows: Weigh 1000g of the above-mentioned wet soil to be treated, and add the curing agents prepared in Examples 1-3 and Comparative Examples 1-5 respectively. The amount of curing agent is uniformly set to 10% of the mass of the wet soil. Spread the curing agent powder evenly on the surface of the soil sample and place it in a JJ-5 planetary mixer. Set the mixing speed to slow (140r / min) for 30 seconds, followed by rapid mixing (285r / min) for 180 seconds. After mixing, immediately conduct various performance tests.

[0116] Test method:

[0117] (1) Initial Flowability Test: Refer to ASTM D6103-04 "Flow Continuity of Controlled Low-Strength Materials". Use a hollow cylindrical mold with an inner diameter of 75 mm and a height of 150 mm. Fill the mold with the mixed slurry in one go and level it. Lift the mold vertically, allowing the slurry to diffuse freely on the glass plate. After 30 seconds, measure the diameter of the diffusion surface in two perpendicular directions and take the average value as the initial flowability. ).

[0118] (2) Flowability loss test over time: The remaining slurry was placed in the mixing pot and covered with a damp cloth to prevent moisture evaporation. After standing for 30 minutes and 60 minutes respectively, the slurry was slowly stirred again for 15 seconds, and its flowability was measured according to the above method. The results were recorded as follows. and .

[0119] (3) Setting time test: Refer to the "Standard consistency water requirement, setting time and soundness test method of cement" (GB / T1346-2011) and use a Vicat apparatus to determine the initial setting time of the slurry.

[0120] Test results:

[0121] The test data for each group of samples are summarized in Table 1.

[0122] Table 1. Record of test data on rheological parameters and setting time of fluidized solidified soil

[0123] Group Initial flowability (mm) 30-minute flowability (mm) 60min flowability (mm) 60-minute flowability loss rate (%) Initial setting time (min) Example 1 218 211 203 6.88 255 Example 2 234 230 224 4.27 280 Example 3 227 221 216 4.85 310 Comparative Example 1 215 168 132 38.60 95 Comparative Example 2 221 175 148 33.03 110 Comparative Example 3 208 195 182 12.50 420 Comparative Example 4 238 235 231 2.94 >720 Comparative Example 5 202 155 115 43.07 140

[0124] Results Analysis and Conclusions:

[0125] Data from Examples 1-3 show that the curing agent prepared in this invention imparts good initial fluidity (210 mm) to the slurry while suppressing fluidity loss over time. Within 60 minutes, the fluidity loss rate in the example groups was controlled below 7%, and the initial setting time remained within the 4-5 hour range. This confirms that the microcapsule structure composed of an acid-potential-regulated bentonite carrier and an alkaline composite excitation core plays the expected chemical gradient barrier role. The acid-modified bentonite in the outer layer, upon initial contact with water, utilizes the H2O loaded in its interlayer... + and Al 3+ Ions neutralized the small amount of OH groups that dissolved and permeated from the core components. - This creates a temporary chemically inert zone at the microscopic interface, delaying the rapid hydration and condensation of aluminosilicate and waste components, thereby ensuring the pumpability of the fluid soil during the construction window (usually 60 minutes).

[0126] In contrast, Comparative Example 1 (using unmodified natural bentonite) showed a fluidity loss rate as high as 38.60% at 60 minutes, and the initial setting time was shortened to 95 minutes. This is because the lack of chemical inhibition by the outer acidic sites caused the highly alkaline activator to undergo rapid and intense hydration and ion exchange with the mineral components upon contact with water, resulting in rapid flocculation of the slurry structure and loss of fluidization characteristics.

[0127] Although the composition of Comparative Example 2 (simple physical mixing, without coating structure) was exactly the same as that of Example 2, the flowability loss rate still reached 33.03% after 60 minutes. This indicates that simple physical mixing cannot build an effective isolation barrier, and the components reacted disorderly in the early stage of stirring, proving the necessity of dry mixing pre-dispersion process to build core and shell structure.

[0128] Although Comparative Example 4 (low calcium-silicon ratio) maintained good fluidity, its initial setting time exceeded 12 hours (720 min), indicating that the geopolymer reaction is difficult to start under excessively low alkalinity conditions, which will affect the progress of the project and the establishment of later strength.

[0129] In summary, this invention successfully resolves the contradiction between maintaining high fluidity and preventing segregation and flash solidification in fluidized solidified soil by using an acidic carrier to encapsulate an alkaline core, thus achieving controllable delayed triggering of the solidification reaction.

[0130] Test Example 2: Physical and Mechanical Properties Testing of Cured Products

[0131] Experimental description:

[0132] This test case mainly evaluates the strength development law of fluidized solidified soil during the curing process and verifies the contribution of solidifier components to the densification of soil microstructure.

[0133] The samples were sourced from the freshly mixed, solidified soil slurry prepared in Test Example 1. After completing the initial flowability test, each group of slurry was immediately poured into a triplet mold measuring 70.7 mm × 70.7 mm × 70.7 mm. The mold was compacted for 30 seconds using a vibrating table to remove internal air bubbles, and then the surface was smoothed with a scraper. The mold surface was covered with a polyethylene film to prevent rapid moisture evaporation.

[0134] The specimens were demolded after standing at room temperature (20±2℃) for 24 hours. After demolding, the specimens were placed in a standard curing room for curing, with the ambient temperature controlled at 20±2℃ and the relative humidity ≥95%.

[0135] Test blocks were removed after 7 days (early strength) and 28 days (late strength), respectively. Following the unconfined compressive strength test method in the "Standard for Geotechnical Testing Methods" (GB / T50123-2019), the test blocks were loaded using a universal testing machine. The loading rate was controlled at 1.0 mm / min until the test block failed. The maximum failure load was recorded, and the unconfined compressive strength (UCS) was calculated. Six parallel test blocks were tested in each group; the maximum and minimum values ​​were discarded, and the arithmetic mean was taken as the final test result.

[0136] Test results:

[0137] The mechanical strength test data of each group of solidified soil test blocks are summarized in Table 2.

[0138] Table 2. Record of Unconfined Compressive Strength Test Data for Stabilized Soil Specimens

[0139] Group 7-day compressive strength (MPa) 28-day compressive strength (MPa) Intensity growth rate (7d-28d, %) Example 1 2.94 4.82 63.9 Example 2 3.87 6.53 68.7 Example 3 4.12 6.89 67.2 Comparative Example 1 2.15 3.95 83.7 Comparative Example 2 2.43 4.21 73.3 Comparative Example 3 1.38 2.96 114.5 Comparative Example 4 0.65 1.24 90.8 Comparative Example 5 3.62 5.40 49.2

[0140] Results Analysis and Conclusions:

[0141] The solidified soil specimens from Examples 1 to 3 all exhibited compressive strengths exceeding the technical requirement of 2.5 MPa at 7 days and strengths exceeding 4.5 MPa at 28 days. Examples 2 and 3, using optimized parameters, demonstrated superior mechanical properties, achieving 28-day strengths of 6.53 MPa and 6.89 MPa, respectively, which are superior to those of ordinary cement-based curing agents (Comparative Example 5). This indicates that the low-temperature calcined aluminosilicate synthesized in this invention underwent a sufficient geological polymerization reaction with industrial waste under alkaline-activated conditions, generating a high-strength CASH (hydrated calcium aluminum silicate) and NASH (hydrated sodium aluminum silicate) gel network, effectively filling the pores of soil particles and cementing the framework.

[0142] The strength data for Comparative Example 3 was low, with a 7-day strength of only 1.38 MPa. This group used conventional Class II fly ash instead of the aluminosilicate synthesized by low-temperature calcination. Due to the dense glassy structure of fly ash, the release of activity is slow at room temperature and moderate alkalinity, resulting in insufficient early gel formation and inability to provide sufficient binding force. In contrast, the aluminosilicate prepared by the Example group through low-temperature calcination has a metastable crystal structure, which easily depolymerizes and participates in condensation reactions under alkaline-activated conditions, confirming the key role of this custom active component in strength building.

[0143] The strength performance of Comparative Example 1 and Comparative Example 2 was lower than that of Example 2. Comparative Example 1 lacked the coating of an acid-potential-controlled carrier, causing flocculation of the slurry in the initial stirring stage (as shown in Test Example 1). This resulted in poor slurry flowability upon placement into the mold, and numerous macroscopic pores inside the specimen due to insufficient compaction, weakening its macroscopic mechanical strength. Although Comparative Example 2 had the same formulation, it failed to form a core-shell structure, and the premature initiation of the reaction led to compromised structural uniformity. This also indirectly confirms that good rheological control is not only beneficial for construction but also a prerequisite for ensuring the final density and strength of the cured body.

[0144] In Comparative Example 4, the CaO / SiO2 molar ratio was too low (0.8), resulting in insufficient alkalinity to disrupt the glassy network of the mineral slag. This led to a low degree of geopolymerization, causing the specimen to be loose and its strength to fail to meet engineering requirements. In contrast, the Example group controlled the modulus between 1.2 and 1.8, achieving an optimal balance between reaction rate and gel strength.

[0145] Test Example 3: Heavy Metal Leaching Toxicity and Fixation Rate Test

[0146] Experimental description:

[0147] This test case aims to evaluate the chemical stabilization effect of the solidifying agent on heavy metal pollutants in soil, especially its ability to lock in different forms of heavy metals (cationic Pb, Cd, Zn and anionic As).

[0148] The experimental subjects were solidified specimens from each group with a curing period of 28 days, as selected in Test Example 2. The operation was carried out in accordance with the "Solid Waste Leaching Toxicity Leaching Method Acetic Acid Buffer Solution Method" (HJ / T299-2007) to simulate the risk of heavy metal migration in acid rain or landfill leachate environments after waste is landfilled.

[0149] The specific steps are as follows: The cured specimen block, after 28 days of curing, is crushed and passed through a 9.5mm sieve. The particles passing through the sieve are collected as the sample to be tested. 100g of the sample is weighed and placed in a 2L extraction bottle. An acetic acid buffer solution (prepared from glacial acetic acid and deionized water) with a pH of 2.88±0.05 is added, maintaining a liquid-to-solid ratio of 20:1 (L / kg). The extraction bottle is fixed on a tilting shaker, and the rotation speed is set to 30±2 r / min. The shaker is then placed at 23±2℃ and shaken for 18 hours.

[0150] After shaking, the mixture was pressure filtered through a 0.45 μm microporous membrane, and the leachate was collected. The concentrations of lead (Pb), zinc (Zn), cadmium (Cd), and arsenic (As) in the leachate were determined using inductively coupled plasma optical emission spectrometry (ICP-OES).

[0151] The heavy metal fixation rate is calculated using the following formula:

[0152] ;

[0153] in:

[0154] Heavy metal fixation rate (%)

[0155] Initial heavy metal content in the original soil (mg / kg);

[0156] : Concentration of heavy metals in leachate (mg / L);

[0157] : Leaching experiment liquid-to-solid ratio (20L / kg).

[0158] Test results:

[0159] The results of heavy metal leaching concentration detection for each group of samples and the calculated comprehensive fixation rate (the arithmetic mean of the fixation rates of the four elements) are summarized in Table 3.

[0160] Table 3. Record of Test Data on Heavy Metal Leaching Concentration and Fixation Rate in Solidified Soil

[0161] Group Pb leaching concentration (mg / L) Zn leaching concentration (mg / L) Cd leaching concentration (mg / L) As leaching concentration (mg / L) Overall Fixed Income Rate (%) Standard Limit ≤5.0 ≤100.0 ≤1.0 ≤5.0 - Example 1 0.084 0.621 0.013 0.057 99.82 Example 2 0.032 0.115 0.005 0.024 99.96 Example 3 0.041 0.188 0.008 0.031 99.93 Comparative Example 1 0.425 3.120 0.088 0.145 98.92 Comparative Example 2 0.386 2.845 0.072 0.118 99.04 Comparative Example 3 1.854 15.630 0.352 0.482 96.25 Comparative Example 4 4.920 68.450 0.925 2.110 85.30 Comparative Example 5 0.215 1.840 0.045 1.865 98.41

[0162] Note: The standard limits refer to the entry limits usually required in the "Pollution Control Standard for Municipal Solid Waste Landfills" (GB16889-2008).

[0163] Results and conclusions: The data in Table 3 show that the embodiments of the present invention have advantages in the curing of heavy metals, especially for difficult-to-cur amphoteric metals and anionic heavy metals.

[0164] In Example 2, the leaching concentrations of Pb, Cd, Zn, and As in the sample were all far below the relevant national standard limits, with an overall fixation rate approaching 100%. In particular, the leaching control of arsenic (As) reached 0.024 mg / L. This is attributed to the abundant active aluminum source provided by the low-temperature calcination synthesis of aluminosilicates in the system. During the alkali-activated reaction, AsO4... 3- The functional group enters the crystal lattice structure of ettringite (AFt) or zeolite minerals through isomorphous substitution, replacing SO4. 2- or SiO4 4- The location allowed for the formation of stable mineral solid solutions.

[0165] In contrast, the leaching concentrations of various heavy metals in Comparative Example 3 (using only fly ash, without low-temperature calcined aluminosilicates) were higher, with the leaching concentration of Zn reaching as high as 15.63 mg / L. This confirms that ordinary fly ash is difficult to depolymerize at room temperature to provide sufficient [AlO4] tetrahedral units, and thus cannot form a sufficient network structure to physically encapsulate or chemically bond heavy metal ions.

[0166] While Comparative Example 5 (cement + sodium sulfide) showed good immobilization of cationic heavy metals (Pb, Cd) (due to the precipitation effect of sulfides), its As leaching concentration was as high as 1.865 mg / L, far exceeding that of the Example group. This is because cement hydration produces a large amount of calcium hydroxide, raising the pH of the pore solution to above 12. In a high pH environment, amphoteric metals (such as Pb, Zn) are at risk of redissolving, and anionic arsenic is difficult to form insoluble precipitates, and may even undergo desorption. This invention utilizes acidic bentonite as a carrier to adjust the microenvironment's pH, combined with the mineral solidification mechanism of aluminosilicates, effectively solving the industry problem of arsenic leaching in high-alkaline environments.

[0167] The leaching concentration of Comparative Example 1 (without acid-modified carrier) was slightly higher than that of Example Group, indicating that the acid potential-regulated bentonite not only serves as a physical shell, but the active aluminum component loaded on its surface also provides additional chemical adsorption sites for heavy metals, synergistically enhancing the curing effect.

[0168] Test Example 4: Environmental Compatibility (Leachate pH) Test

[0169] Experimental description:

[0170] This test case aims to evaluate the extent to which solidified soil releases alkaline substances under long-term immersion conditions, and to verify the compatibility of the technical solution of this invention with the surrounding soil ecological environment. Highly alkaline leaching water can lead to soil compaction and salinization, which is one of the main environmental risks of traditional cement-based solidification materials.

[0171] The test subject was directly selected from the leachate of solidified soil prepared according to the HJ / T299-2007 standard and subjected to inverting and oscillation.

[0172] The specific experimental steps are as follows:

[0173] Instrument calibration: A benchtop pH meter (model PHS-3C) with an accuracy of 0.01 pH units was used. Before testing, the electrodes were calibrated at three points using standard pH buffer solutions (pH=4.00, 6.86, 9.18) to ensure the slope was within the range of 95%-105%.

[0174] Sample settling: Place the clarified leachate obtained by filtration in Test Example 3 into a beaker and let it stand for 5 minutes to reach room temperature thermal equilibrium.

[0175] Measurement: Immerse the cleaned and dried composite electrode into the solution to be tested, gently shake the beaker to make the solution uniform, and record the displayed value after the reading stabilizes (the value changes by no more than 0.02 within 30 seconds).

[0176] Replication: Each group of samples was tested in parallel 3 times, and the arithmetic mean was taken as the final result.

[0177] Test results:

[0178] The pH test data of the leachate from each group of solidified soil are summarized in Table 4.

[0179] Table 4. Record of pH value test data for leachate from solidified soil

[0180] Group pH value of parallel sample 1 pH value of parallel sample 2 pH value of parallel sample 3 Average pH Example 1 8.12 8.05 8.18 8.12 Example 2 7.85 7.91 7.82 7.86 Example 3 8.34 8.28 8.41 8.34 Comparative Example 1 9.76 9.88 9.65 9.76 Comparative Example 2 10.15 10.02 10.21 10.13 Comparative Example 3 10.45 10.58 10.39 10.47 Comparative Example 4 7.42 7.35 7.48 7.42 Comparative Example 5 11.92 12.15 11.85 11.97

[0181] Results Analysis and Conclusions:

[0182] The pH values ​​of the leachates from Examples 1-3 remained stable between 7.8 and 8.4, meeting the expected environmentally friendly index (pH < 8.5). This result confirms the chemical buffering effect of the acid potential-regulated bentonite carrier of this invention. During the initial stage of the curing reaction and subsequent immersion, the active hydrogen ions (H+) loaded in the interlayer of the carrier... + ) and aluminum ions (Al 3+Through ion exchange, the residual alkali diffused outward from the core excitation component is effectively neutralized. Furthermore, the high reactivity of the aluminosilicate synthesized by low-temperature calcination allows for the release of alkali metal ions (Na₂O₃) within the system. + K + More of the alkali is bound within the NASH gel framework rather than remaining free in the pore solution, thus reducing the leaching of soluble alkali at the source.

[0183] The leachate of Comparative Example 5 (cement-based curing agent) had a pH value as high as 11.97, exhibiting strong alkalinity. This is an inevitable byproduct of silicate cement hydration: the large-scale formation of calcium hydroxide (CH) crystals. Calcium hydroxide has high solubility and readily releases OH- upon contact with water. - If it is used directly for soil remediation in farmland or sensitive ecological areas, it will cause serious secondary salinization pollution.

[0184] The average pH of Comparative Example 1 (using natural calcium-based bentonite) was 9.76, higher than that of the Example Group. Due to the lack of neutralizing capacity of the acid-modified carrier, the alkaline substances of the core component could more easily penetrate the physical shell and enter the water. The pH of Comparative Example 2 (simple physical mixing) further increased to 10.13, indicating that in the absence of a microencapsulation structure, the contact between the alkali activator and water was unrestricted, resulting in the rapid release of readily soluble alkali.

[0185] Although Comparative Example 4 has a low pH value (7.42), it is known from Test Example 2 to have a low strength, indicating that the low pH value is due to insufficient alkali activator dosage and no reaction occurring, and has no practical engineering significance.

[0186] In summary, this invention successfully solves the high alkalinity leaching problem commonly found in traditional chemical curing technologies by actively regulating the acidic carrier and synergistically utilizing the geopolymer solidification mechanism, achieving both high-alkalinity curing effect and environmental compatibility.

[0187] Test Example 5: Water Resistance and Long-Term Stability Test

[0188] Experimental description:

[0189] This test case aims to simulate the integrity of the solidified soil structure and its long-term binding capacity for heavy metal pollutants after seasonal wet-dry cycles. The focus is on comparing the stability differences between chemical lattice solidification and physical adsorption solidification under extreme conditions.

[0190] The experimental subjects were selected from the cured test blocks of each group that had been cured under standard conditions for 28 days in Test Example 2.

[0191] The specific experimental steps are as follows:

[0192] Initial parameter setting: The 28-day unconfined compressive strength measured in Test Example 2 was used as the initial strength benchmark.

[0193] Environmental stress treatment: Each group of test blocks was placed in a wet-dry cycle test chamber. The conditions for a single cycle were set as follows: immersion in water at 20±2℃ for 12 hours, followed by drying at 60±2℃ for 12 hours. This was repeated for 5 cycles.

[0194] Mechanical property retest: After the cycle is completed, the unconfined compressive strength of the specimen is measured and the strength loss rate is calculated.

[0195] Pollutant re-leaching test: The test block after the cycle is crushed and the leaching toxicity test of acetic acid buffer solution is carried out again according to the HJ / T299-2007 standard (same as test example 3). The concentrations of Pb, Zn, Cd and As in the leachate are determined to assess the desorption risk of heavy metals.

[0196] The formula for calculating the strength loss rate is as follows:

[0197] ;

[0198] in:

[0199] Strength loss rate (100%)

[0200] : Compressive strength (MPa) 28 days before wet-dry cycling;

[0201] Compressive strength (MPa) after 5 wet-dry cycles.

[0202] Test results:

[0203] The mechanical decay and heavy metal re-leaching data of each group of samples after 5 dry-wet cycles are summarized in Table 5.

[0204] Table 5. Data Record of Strength Loss Rate and Heavy Metal Re-leaching Concentration After Dry and Wet Cycles

[0205] Group Post-cycle strength (MPa) Strength loss rate (%) Pb releaching concentration (mg / L) Zn releaching concentration (mg / L) As releaching concentration (mg / L) Example 1 4.41 8.51 0.095 0.682 0.063 Example 2 6.25 4.29 0.038 0.124 0.028 Example 3 6.52 5.37 0.046 0.205 0.035 Comparative Example 1 3.24 17.97 0.582 4.150 0.186 Comparative Example 2 3.06 27.32 0.815 6.920 0.245 Comparative Example 3 1.95 34.12 2.650 22.450 0.864 Comparative Example 4 -(Disintegration) 100.00 5.840 75.600 2.540 Comparative Example 5 4.35 19.44 0.364 2.950 2.150

[0206] Results and conclusions: The data in Table 5 show that, after being subjected to environmental stress, the long-term stability of the technical solution of this invention is better than that of the comparative solution.

[0207] The strength loss rate in Example 2 was only 4.29%, and the released concentrations of heavy metals (Pb, Zn, As) showed little change compared to before recycling (see Test Example 3). This confirms that the hierarchical ion exchange structure constructed in this invention achieves deep mineral solidification of heavy metals. During the reaction, heavy metal ions are not merely adsorbed onto the gel surface, but rather enter the lattice cavities of zeolite minerals or ettringite through isomorphous substitution, forming stable chemical bonds. This lattice binding is unaffected by external moisture migration or physical expansion and contraction, thus ensuring the long-term low release characteristics of pollutants.

[0208] Comparative Example 2 (simple physical mixture) exhibited the most typical performance degradation, with a strength loss rate as high as 27.32%, and the releaching concentrations of Pb and Zn surged compared to before the cycle (Pb increased from 0.386 mg / L to 0.815 mg / L). This indicates that in the absence of microencapsulation and ordered reaction control, a large number of physically adsorbed heavy metals exist inside the solidified body. Under the capillary force and water scouring action of the wet-dry cycle, these heavy metal ions, which were only adsorbed by van der Waals forces or surface electrostatics, underwent significant desorption and migrated out with the pore water. Simultaneously, the propagation of microcracks caused by uneven reaction within the structure further exacerbated the connectivity of the pollutant leaching channels.

[0209] Comparative Example 5 (cement-based) showed a strength loss rate close to 20%, and the re-leaching concentration of As remained at a high level (2.150 mg / L). This indicates that cement hydration products are prone to carbonization or dissolution under alternating wet and dry conditions, leading to pH fluctuations and a loose structure in the solidified body, which in turn increases the risk of secondary release of encapsulated heavy metals.

[0210] In summary, this invention overcomes the problem of contaminant re-dissolution that easily occurs during long-term service using traditional physical mixing or simple cementation and curing techniques by constructing a stable mineral lattice system, and has excellent water resistance and environmental safety.

Claims

1. A solidifying agent for fluidized solidified soil used to solidify harmful heavy metal ions, characterized in that, It is made from the following components in parts by weight: 85-90 parts of alkaline composite activation core components; 10-15 parts of bentonite carrier with acid potential regulation; The alkaline composite activation core component is made from raw materials comprising the following weight percentages: Industrial waste-derived materials account for 60%-70%, and low-temperature calcination synthesized aluminosilicates account for 30%-40%. Based on the sum of the mass of the industrial waste-derived materials and the low-temperature calcined synthesized aluminosilicates, 5%-10% of rapid-hardening sulfoaluminate cement clinker is also added, and calcium oxide powder is added to adjust the total CaO / SiO2 molar ratio of the system. The acid potential-controlled bentonite carrier is calcium-based bentonite modified with inorganic aluminum salt.

2. The fluidized solidified soil solidifier for solidifying harmful heavy metal ions according to claim 1, characterized in that, The industrial waste residue-derived material is composed of S95 grade slag powder and F-class II fly ash, and the mass ratio of S95 grade slag powder to F-class II fly ash is 3:1-4:

1.

3. The fluidized solidified soil solidifier for solidifying harmful heavy metal ions according to claim 1, characterized in that, The amount of calcium oxide powder added is such that the total CaO / SiO2 molar ratio of the alkaline composite activating core component system is controlled between 1.2 and 1.

8.

4. The fluidized solidified soil solidifier for solidifying harmful heavy metal ions according to claim 1, characterized in that, The low-temperature calcination synthetic aluminosilicate is made from raw materials comprising the following weight percentages: Kaolin 65%-75%, calcium hydroxide 15%-20%, waste glass powder 10%-15%; The method for preparing aluminosilicates by low-temperature calcination includes: After the mixed raw materials are activated by ball milling, they are calcined at 750-850℃ for 2.0-3.0 hours, followed by forced air cooling treatment.

5. The fluidized solidified soil solidifier for solidifying harmful heavy metal ions according to claim 4, characterized in that, The mass ratio of Al2O3 / SiO2 in the mixed raw materials for the low-temperature calcination synthesis of aluminosilicates is 0.6-0.8; The forced air cooling rate is ≥60℃ / min, and the resulting powder has a specific surface area of ​​505-535m². 2 / kg.

6. The fluidized solidified soil solidifier for solidifying harmful heavy metal ions according to claim 1, characterized in that, The preparation method of the acid potential-regulated bentonite carrier includes the following steps: Calcium-based bentonite is dispersed in water to make a slurry, and aluminum sulfate solution is slowly added dropwise, so that the dry basis of aluminum sulfate is 10%-20% of the bentonite mass. During the dropwise addition process, the pH value of the system should be maintained at 3.0-4.0; The slurry is heated to 60-80℃, stirred at a constant temperature and allowed to stand for aging. After drying and grading, powder with a particle size of 45-75μm is obtained.

7. The fluidized solidified soil solidifier for solidifying harmful heavy metal ions according to claim 6, characterized in that, The concentration of the aluminum sulfate solution is 1.0-2.0 mol / L; The constant temperature stirring time is 2.0-4.0 hours, and the standing and aging time is 12-24 hours.

8. The fluidized solidified soil solidifier for solidifying harmful heavy metal ions according to claim 1, characterized in that, The curing agent is prepared through a dry-mix pre-dispersion coating process, which specifically includes: The alkaline composite activation core component and the acidic potential-regulated bentonite carrier are put into a mixer and premixed for 2-3 minutes at a speed of 300-500 rpm. Then increase the speed to 1500-2500 rpm and maintain high-speed stirring for 10-15 minutes. Use mechanical force and electrostatic adsorption to coat the acid potential-controlled bentonite carrier onto the surface of the alkaline composite excitation core component.

9. The fluidized solidified soil solidifier for solidifying harmful heavy metal ions according to claim 1, characterized in that, The acidic potential-regulated bentonite carrier forms a microcapsule outer shell in the curing agent, and the alkaline composite-excited core component forms the core of the microcapsule structure.

10. The fluidized solidified soil solidifier for solidifying harmful heavy metal ions according to claim 1, characterized in that, The preparation of the alkaline composite activation core component specifically includes: First, the industrial waste residue-derived material is mixed with low-temperature calcined synthetic aluminosilicate. The oxide composition of the mixture is determined by X-ray fluorescence spectrometry. Based on the target total CaO / SiO2 molar ratio, calcium oxide powder and fast-hardening sulfoaluminate cement clinker are added. Then, the resulting mixture is placed in a grinding equipment for co-grinding and activation treatment.