Soil remediation agent for reducing copper pollution as well as preparation method and application of soil remediation agent

Abstract

The invention belongs to the technical field of soil remediation, and particularly discloses a soil remediation agent for reducing copper pollution and a preparation method and application thereof. The soil remediation agent comprises the following raw materials in parts by weight: 5-7 parts of red mud, 8-10 parts of blast furnace slag and an alkali activator, the alkali activator in the soil remediation agent accounts for 4-20% of the total weight of the red mud and the blast furnace slag, and the alkali activator is sodium silicate formed by adjusting NaOH. The preparation method comprises the steps of solid premixing, water glass premixing and stirring and mixing. The application refers to application of the soil remediation agent for reducing copper pollution in remediation of copper-polluted soil. By optimizing the modulus of water glass and the doping amount of Na2O, the red mud blast furnace slag-based geopolymer is stimulated to cure and repair the copper-polluted soil, the unconfined compressive strength of the polluted soil is improved, the toxic leaching of heavy metal copper is reduced, and the method has the characteristics of low cost, small dosage, environment friendliness and stable long-term curing effect.

Description

Technical Field

[0001] The present invention belongs to the technical field of soil remediation, and specifically relates to a soil remediation agent for reducing copper pollution, which has low cost, small dosage, is environmentally friendly, and has stable long-term curing effect, as well as a preparation method and application thereof. Background Art

[0002] With the continuous advancement of industrialization, heavy metal pollution has become a major global environmental problem. Contamination by heavy metals, such as copper, has severely impacted soil quality and the ecological environment, necessitating the development of efficient and environmentally friendly remediation technologies. Solidification / stabilization (S / S) technology involves immobilizing heavy metals and other hazardous substances in solid waste through physical, chemical, or biological methods, or converting them into chemically inactive forms to prevent their migration and diffusion in the environment, thereby reducing the environmental risks of these pollutants. Currently, S / S technology has been widely used as an effective, low-energy, and environmentally friendly method for treating contaminated soil. However, traditional S / S technology often uses cement as a remediation binder, and its production process can have adverse environmental impacts, such as high CO2 emissions, energy loss, and soil compaction. Therefore, alkali-activated cementitious materials derived from industrial solid waste have attracted widespread attention as a new material for soil solidification and remediation due to their low energy consumption, low cost, and strong environmental adaptability.

[0003] Geopolymers are green, inorganic gelling materials formed from aluminosilicate-rich minerals such as clay, industrial waste, or slag in the presence of an alkaline activator. Due to their excellent mechanical properties and durability, as well as their ability to utilize industrial solid waste and environmental friendliness, they are widely used in the remediation of heavy metal-contaminated soils. In remediating heavy metal-contaminated soils, geopolymers physically encapsulate, chemically bond, and exchange ions with heavy metal ions, securing them within their three-dimensional network structure. This reduces their mobility and biotoxicity, thereby achieving the goal of immobilizing and solidifying the heavy metals.

[0004] In the prior art, geopolymers used for the remediation of heavy metal-contaminated soils are typically prepared using industrial waste, such as blast furnace slag and fly ash, as their primary raw materials, in combination with an alkaline activator. For example, a slag-ferro-aluminum mud soil remediation agent, prepared using slag and ferro-aluminum mud as the primary raw materials and an alkaline activator, can achieve the simultaneous fixation of heavy metal anions and cations, with excellent fixation effects on various heavy metals, such as copper. After solidification, the leaching concentration of relevant heavy metals meets national emission standards, and the solidified product has excellent mechanical properties, making it suitable for use as a green building material or in solid waste landfills. However, due to regional differences and stability issues in the supply of ferro-aluminum mud, and the need for pretreatment such as grinding and screening of the contaminated soil and raw materials during application, the process involves relatively more steps. Another example is a chitosan-based alkaline-activated soil remediation agent, formed by mixing industrial solid waste and chitosan with an alkaline activator. This compound effectively enhances the mechanical properties and durability of copper-contaminated soil, resulting in compressive strength exceeding relevant limits before and after wet-dry cycles, meeting the requirements for actual engineering service or safe landfill. Furthermore, it significantly reduces the leaching toxicity of copper, shifting the copper's primary form to a residual state, effectively mitigating environmental risks. However, the relatively high cost of chitosan and the precise control of the proportions of the various ingredients in the formula lead to relatively high requirements for preparation processes and equipment. Another example is a copper tailings remediation agent, which uses copper tailings as the primary raw material and mixes them with varying concentrations of KOH. Silicon powder can also be used to replace some of the copper tailings, and other auxiliary ingredients can be added to optimize performance. Because it can absorb large amounts of copper tailings and improve the soil's compressive strength, it can, under certain conditions, meet the strength requirements of projects such as road bases. However, due to the complex and fluctuating composition of copper tailings, this can affect the quality stability of the remediation agent. If improperly handled, there may still be a risk of some heavy metal release.

[0005] Therefore, for the remediation of copper-contaminated soil, research on a soil remediation agent that is mainly based on industrial solid waste with a wide source and low cost, has a simple preparation process, high strength after soil remediation and low toxicity leaching has become one of the current research hotspots of geopolymers. Summary of the Invention

[0006] In order to solve the problems mentioned in the above background technology, the present invention provides a soil remediation agent for reducing copper pollution with low cost, small dosage, environmental friendliness, and stable long-term curing effect. It also provides a method for preparing a soil remediation agent for reducing copper pollution, and further provides an application of a soil remediation agent for reducing copper pollution.

[0007] The soil remediation agent for reducing copper pollution of the present invention is achieved as follows: the raw materials include, by weight, 5 to 7 parts of red mud, 8 to 10 parts of blast furnace slag and an alkaline activator, wherein the alkaline activator in the soil remediation agent accounts for 4 to 20% of the total weight of the red mud and blast furnace slag, and the alkaline activator is water glass formed by adjusting NaOH.

[0008] Furthermore, the Na2O content of the water glass accounts for 2-8% of the total weight of the red mud and blast furnace slag, and the modulus of the water glass is 1.2-1.8.

[0009] Furthermore, the addition amount G of NaOH in the water glass is calculated according to the following formula: , Where: G1 is the weight of water glass, N is the proportion of Na2O in water glass, M1 is the initial modulus of water glass, M2 is the target modulus of water glass, and P is the purity of NaOH.

[0010] Furthermore, the raw materials include, by weight, 2 parts of red mud, 3 parts of blast furnace slag and an alkaline activator. The red mud is Bayer process red mud of bauxite, Bayer-sintering combined process red mud or pre-roasted-Bayer process red mud. The particle size of the red mud and blast furnace slag is -200 mesh.

[0011] The method for preparing a soil remediation agent for reducing copper pollution of the present invention is achieved by comprising the steps of solid premixing, water glass premixing, and stirring and mixing. The specific contents of each step are as follows: A. Solid premix: Weigh 5-7 parts of red mud and 8-10 parts of blast furnace slag by weight, then fully mix the weighed red mud and blast furnace slag to obtain a solid premix; B. Water glass premix: weigh 4-20% of the total weight of red mud and blast furnace slag, and then fully mix the weighed water glass with an equal weight of water to obtain a water glass premix; C. Stirring and mixing: fully mix the aforementioned solid premix with the water glass premix to obtain a soil remediation agent.

[0012] Furthermore, in the step A, the red mud is crushed to a particle size of -200 mesh, and the blast furnace slag is crushed and ground to a particle size of -200 mesh.

[0013] Furthermore, in step B, the Na2O content of the water glass accounts for 2-8% of the total weight of the red mud and blast furnace slag, and the modulus of the water glass is 1.2-1.8.

[0014] Furthermore, the water glass in step B is adjusted with NaOH, and the amount of NaOH added to the water glass is calculated as follows: , Where: G1 is the weight of water glass, N is the proportion of Na2O in water glass, M1 is the initial modulus of water glass, M2 is the target modulus of water glass, and P is the purity of NaOH.

[0015] The application of the soil remediation agent for reducing copper pollution of the present invention is achieved as follows: the aforementioned soil remediation agent for reducing copper pollution is applied in remediating copper-contaminated soil.

[0016] Furthermore, the application of the soil remediation agent for reducing copper pollution of the present invention is to fully stir and mix the copper-contaminated soil to be repaired with the soil remediation agent in an amount of 8-12%, and then cure it at 20-30°C and humidity ≥98% for at least 7 days to complete the copper-contaminated soil remediation.

[0017] The mechanism of the soil remediation agent of the present invention in repairing copper-contaminated soil is as follows:

[0018] The present invention has the following beneficial effects: 1. The soil remediation agent of the present invention is mainly based on red mud and blast furnace slag. By optimizing the modulus of water glass added as an alkali activator and the amount of Na2O, the geopolymerization reaction of red mud and blast furnace slag-based geopolymer is stimulated, thereby generating a sufficient amount of hydration product gel, thereby effectively encapsulating and solidifying the copper ions in the contaminated soil. The appropriate modulus can provide the necessary OH for the geopolymerization reaction. - , and can generate a gel phase with a good network structure and high adsorption capacity. It not only solves the problem of low efficiency of directly repairing copper-contaminated soil with red mud and blast furnace slag, but also improves the unconfined compressive strength of the contaminated soil after repair, which can meet the actual engineering service or safe landfill needs. The solidification effect can stabilize the copper ions in the three-dimensional network structure. While reducing the mobility and biological toxicity of heavy metal copper after repair, it can also reduce the risk of secondary release of heavy metals caused by environmental changes (such as acid-base conditions, water circulation) during long-term service. Therefore, the repair is efficient and the long-term solidification effect after repair is stable.

[0019] 2. The soil remediation agent of the present invention uses red mud and blast furnace slag as main raw materials, both of which are industrial solid wastes with large quantities and wide applications. Not only is the source of raw materials stable and low-cost, which can significantly reduce the cost of the remediation agent, but it can also achieve "waste treatment with waste", reducing the land occupied by solid waste storage and the risk of environmental pollution. The remediated soil can be reused in agriculture and engineering construction to alleviate land resource shortages, which is in line with the concepts of green environmental protection and circular economy. In addition, the preparation method of the soil remediation agent of the present invention does not require high-temperature sintering, and the energy consumption is much lower than that of traditional cement-based remediation materials. The amount of water glass used only accounts for 4-20% of the total weight of red mud and blast furnace slag, thus significantly reducing raw material costs and production energy consumption, providing a new technical approach for the remediation of similar heavy metal-contaminated soils (such as lead, cadmium, etc.) and the utilization of industrial solid waste.

[0020] 3. The preparation method of the soil remediation agent of the present invention requires only three steps: "solid premixing - water glass premixing - stirring and mixing", without the need for complex equipment or elaborate pretreatment. Therefore, the operation process is simple and suitable for industrial large-scale production. Moreover, after the soil remediation agent is mixed with copper-contaminated soil, it can be effective under conventional maintenance conditions. Therefore, it can be applied to different types of copper-contaminated soil (such as farmland, industrial sites, slag yards, etc.), and the dosage can be adjusted according to the degree of soil contamination, thus having wide applicability.

[0021] 4. The main raw material of the soil remediation agent of the present invention is industrial solid waste, without any harmful chemical additives, and no toxic gas or waste liquid is released during the repair and curing process. Therefore, the repaired soil can be safely used for building materials, backfill projects, etc., realizing resource utilization; and compared with traditional cement-based remediation materials, the preparation method of the soil remediation agent of the present invention does not require high-temperature calcination, which can greatly reduce CO2 emissions (cement production accounts for 7-8% of global CO2 emissions), meets the carbon neutrality goal, and has significant environmental benefits.

[0022] In summary, the present invention achieves the "high efficiency, low cost, and environmental protection" goals of copper-contaminated soil remediation through the optimized formula design of "industrial solid waste + water glass" and a simple process. It not only solves the high energy consumption and high cost problems of traditional remediation technologies, but also provides a new path for the resource utilization of industrial solid waste. It has significant technological innovation and practical application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a flow chart of the method for preparing a soil remediation agent for reducing copper pollution according to the present invention; Figure 2 This is a graph showing the change in unconfined compressive strength of the repaired soil under different Na2O dosages and moduli of water glass in the embodiment; Figure 3 Cu is the Cu content of soil repaired under different Na2O content and modulus of water glass in the embodiment. 2+ Toxic leaching concentration change diagram; Figure 4 This is a scanning electron microscope (SEM) analysis of the repaired soil under different Na2O dosages and moduli of water glass in the example. DETAILED DESCRIPTION

[0024] The present invention will be further described below with reference to the accompanying drawings and embodiments, but the present invention is not limited in any way. Any changes or improvements made based on the teachings of the present invention fall within the scope of protection of the present invention.

[0025] The soil remediation agent for reducing copper pollution of the present invention comprises raw materials, in parts by weight, 5 to 7 parts of red mud, 8 to 10 parts of blast furnace slag, and an alkaline activator. The alkaline activator in the soil remediation agent accounts for 4 to 20% of the total weight of the red mud and the blast furnace slag, and the alkaline activator is water glass formed by adjusting NaOH.

[0026] The Na2O content of the water glass accounts for 2-8% of the total weight of the red mud and the blast furnace slag, and the modulus of the water glass is 1.2-1.8.

[0027] It should be noted that the Na2O content of water glass is 2-8% and the water glass modulus is 1.2-1.8, which can effectively ensure that the alkali excitation reaction is fully carried out and sufficient hydration product gel is generated, thereby effectively encapsulating and solidifying heavy metal ions in contaminated soil. In addition, the appropriate modulus can provide the necessary OH for the geopolymerization reaction. - , and can also produce a gel phase with a well-defined network structure and high adsorption capacity. When the dosage is greater than the maximum value of this range, the amount of alkaline activator required is excessive, significantly increasing treatment costs. The excessive alkalinity may cause soil particles to disperse, increase porosity, and induce the risk of harmful expansion or cracking. When the dosage is less than the minimum value of this range, it fails to provide a sufficient alkaline environment and reactants, resulting in incomplete geopolymerization and insufficient gel production, significantly reducing the ability to encapsulate and fix pollutants. When the modulus is greater than the maximum value of this range, the SiO2 content in the water glass is too high, increasing solution viscosity and reducing reaction activity. This slows the dissolution and polycondensation of silicate ions, slows the geopolymerization rate and may result in incompleteness, resulting in a loose gel structure and high porosity. When the modulus is less than the minimum value of this range, the solution is too alkaline (excessive Na2O content), which can lead to an overly vigorous reaction, potentially forming an uneven structure or excessive consumption of active ingredients, weakening the long-term curing effect.

[0028] The addition amount G of NaOH in the water glass is calculated as follows: , Where: G1 is the weight of water glass, N is the proportion of Na2O in water glass, M1 is the initial modulus of water glass, M2 is the target modulus of water glass, and P is the purity of NaOH.

[0029] The soil remediation agent for reducing copper pollution of the present invention comprises raw materials in parts by weight: 2 parts of red mud, 3 parts of blast furnace slag and an alkaline activator. The red mud is Bayer process red mud of bauxite, Bayer-sintering combined process red mud or pre-roasted-Bayer process red mud. The particle size of the red mud and blast furnace slag is -200 mesh.

[0030] like Figure 1As shown, the preparation method of the soil remediation agent for reducing copper pollution of the present invention includes the steps of solid premixing, water glass premixing, and stirring and mixing. The specific contents of each step are as follows: A. Solid premix: Weigh 5-7 parts of red mud and 8-10 parts of blast furnace slag by weight, then fully mix the weighed red mud and blast furnace slag to obtain a solid premix; B. Water glass premix: weigh 4-20% of the total weight of red mud and blast furnace slag, and then fully mix the weighed water glass with an equal weight of water to obtain a water glass premix; C. Stirring and mixing: fully mix the aforementioned solid premix with the water glass premix to obtain a soil remediation agent.

[0031] In step A, the red mud is crushed to a particle size of -200 mesh, and the blast furnace slag is crushed and ground to a particle size of -200 mesh.

[0032] In step B, the Na2O content of the water glass accounts for 2-8% of the total weight of the red mud and blast furnace slag, and the modulus of the water glass is 1.2-1.8.

[0033] The water glass in step B is adjusted with NaOH, and the amount of NaOH added to the water glass is calculated as follows: , Where: G1 is the weight of water glass, N is the proportion of Na2O in water glass, M1 is the initial modulus of water glass, M2 is the target modulus of water glass, and P is the purity of NaOH.

[0034] The application of the soil remediation agent for reducing copper pollution of the present invention is the application of the aforementioned soil remediation agent for reducing copper pollution in remediating copper-contaminated soil.

[0035] The invention discloses a soil remediation agent for reducing copper pollution, wherein the copper-contaminated soil to be repaired is fully stirred and mixed with the soil remediation agent in an amount of 8 to 12%, and then cured for at least 7 days at 20 to 30° C. and a humidity of 98% or higher, thereby completing the copper-contaminated soil remediation.

[0036] Example

[0037] The preparation process of the soil remediation agent for reducing copper pollution and the application process of the prepared soil remediation agent in remediating copper-contaminated soil are as follows: 1. Prepare ingredients: Sodium silicate: Aladdin instant sodium silicate powder, its original modulus is 2.43, Na2O content is: 23.19%; NaOH: fine granular sodium hydroxide (analytical grade) from Yunnan Jingrui Technology; Heavy metal drugs: copper nitrate is CNW anhydrous copper nitrate (analytical grade); Red mud (RM): Bayer red mud selected from a bauxite red mud dump in Yunnan; Granulated blast furnace slag (GGBS): S95 grade granulated blast furnace slag powder purchased from a steel mill in Hebei Province.

[0038] 2. The preparation process of soil remediation agent is as follows: S100: First, the prepared red mud is crushed to a particle size of -200 mesh, and then 2 parts of red mud and 2 parts of blast furnace slag are weighed respectively by weight, and then the weighed red mud and blast furnace slag are fully mixed to obtain a solid premix.

[0039] S200: Weigh NaOH according to the following formula, and then mix the weighed NaOH with Aladdin instant sodium silicate powder to obtain water glass with a modulus of 1.2 to 1.8; then weigh 10% of the total weight of red mud and blast furnace slag water glass and mix it with an equal weight of water to obtain a water glass premix.

[0040] S300: Fully mixing the aforementioned solid premix with the water glass premix to obtain a soil remediation agent; wherein the amount of Na2O in the water glass accounts for 2 to 8% of the total weight of the red mud and blast furnace slag.

[0041] 3. Application of soil remediation agents in repairing copper-contaminated soil: The copper-contaminated clay to be repaired prepared with the copper nitrate mentioned above and the soil remediation agent with a dosage of 10% were placed in a blender and stirred and mixed. The stirred mixture was then pressed into a sample, and then the sample was placed at 25°C and 98% humidity for 28 days to complete the preparation of the copper-contaminated soil remediation sample.

[0042] As shown in Table 1, in the copper-contaminated soil remediation process of this embodiment, the water glass added to the soil remediation agent adopts different Na2O dosages and moduli; wherein, N i Represents the Na2O content of water glass, i ∈(2,4,6,8);M k represents the modulus of water glass, k ∈(1.2,1.4,1.6,1.8). At the same time, a blank group (CS) without soil remediation agent and a control group (RG) with soil remediation agent (i.e., geopolymer) without water glass were added.

[0043] Table 1 Sample number list in this embodiment

[0044] To evaluate the compressive strength characteristics of samples with different mix ratios, unconfined compressive strength tests were conducted. The method is as follows: 50 mm × 50 mm cylindrical specimens were prepared from the stirred mixture according to JTG 3441-2024, "Testing Procedure for Stabilized Materials with Inorganic Binders for Highway Engineering." After the curing period, the unconfined compressive strength was measured using a YYW-II digital display electric compressive strength tester manufactured by Cangzhou Huayi Instrument Factory.

[0045] The results are as follows Figure 2 As shown in the figure, after alkali activation, the unconfined compressive strength of the sample with a 2% Na₂O content decreased, remaining below that of the sample with geopolymer alone. The compressive strength of the remaining samples increased, with the N6M3 sample reaching 3.28 MPa, a significant increase of 63.18%. This strength improvement is significantly greater than that of the sample without alkali activation (RG).

[0046] To evaluate the leaching concentration characteristics of heavy metals under different mixing ratios, toxicity leaching tests were conducted. The following method was used: After meeting the curing age, samples were oven-dried at 105°C for 24 h. The samples were then crushed using an XFB-1000 grinder and passed through a 1 mm sieve. The samples were then mixed with the leaching solution at a solid-to-liquid ratio of 1:20 (m:V, g / mL). The mixture was then placed in a polyethylene shaker bottle and placed on a horizontal shaker. The shaker was shaken for 18 ± 2 h at a speed of 30 ± 2 rpm and a temperature of 25 ± 2°C. After shaking, the samples were allowed to stand to separate the supernatant. The metal ion concentration in the supernatant was then determined using an ICP-OES (Thermo Fisher Scientific, USA). To ensure the accuracy of the results, three replicates were performed for each sample, and the final result was the average of the three measurements.

[0047] The results are as follows Figure 3 As shown, after adding base to stimulate, Cu 2+ The toxic leaching concentration was significantly reduced. When the Na2O content was 6% and 8%, the toxic leaching concentration met the leaching standard. 2+ The leaching concentration was the lowest, only 85.4 mg / L, Cu 2+ The reduction rate reached 70.95%. 2+ The leaching effect is significantly reduced.

[0048] like Figure 4As shown, as the water glass modulus increases, its hydration products gradually increase, and the structure becomes more compact. However, when the water glass modulus reaches 1.8, the structure becomes looser and the hydration products decrease. The microstructure of the samples remains roughly the same as the Na2O content increases. N6M3 contains a small amount of needle-like AFt, while the hydration products of N2M3, N4M3, and N8M3 are primarily CSH gel, lamellar hydrates, and Ca(OH)2. The gel bond of the N6M3 sample is the densest, while the bond of the N2M3 sample is relatively loose due to the presence of numerous pores.

[0049] Conclusion: The copper-contaminated soil remediation agent of this invention significantly improved the unconfined compressive strength of the remediated copper-contaminated soil compared to geopolymer (RG) alone. The addition of a small amount of waterglass significantly improved the unconfined compressive strength of the remediated copper-contaminated soil while significantly reducing the toxic leaching concentration of copper ions. The maximum unconfined compressive strength was achieved when the Na₂O content was 6% and the waterglass modulus was 1.6. The toxic leaching concentration met the standard, while also minimizing material consumption.

[0050] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A soil remediation agent for reducing copper pollution, characterized in that: The raw materials include, by weight, 5 to 7 parts of red mud, 8 to 10 parts of blast furnace slag and an alkaline activator. The alkaline activator in the soil remediation agent accounts for 4 to 20% of the total weight of the red mud and blast furnace slag. The alkaline activator is water glass formed by adjusting NaOH.

2. The soil remediation agent for reducing copper pollution according to claim 1, characterized in that: The Na2O content of the water glass accounts for 2-8% of the total weight of the red mud and the blast furnace slag, and the modulus of the water glass is 1.2-1.

8.

3. The soil remediation agent for reducing copper pollution according to claim 1, characterized in that: The addition amount G of NaOH in the water glass is calculated as follows: ， Where: G1 is the weight of water glass, N is the proportion of Na2O in water glass, M1 is the initial modulus of water glass, M2 is the target modulus of water glass, and P is the purity of NaOH.

4. The soil remediation agent for reducing copper pollution according to claim 1, 2 or 3, characterized in that: The raw materials include, by weight, 2 parts of red mud, 3 parts of blast furnace slag and an alkaline activator. The red mud is Bayer process red mud of bauxite, Bayer-sintering combined process red mud or pre-roasted-Bayer process red mud. The particle size of the red mud and blast furnace slag is -200 mesh.

5. A method for preparing a soil remediation agent for reducing copper pollution, characterized in that: The process includes solid premixing, water glass premixing, and stirring and mixing steps. The specific contents of each step are as follows: A. Solid premix: Weigh 5-7 parts of red mud and 8-10 parts of blast furnace slag by weight, then fully mix the weighed red mud and blast furnace slag to obtain a solid premix; B. Water glass premix: weigh 4-20% of the total weight of red mud and blast furnace slag, and then fully mix the weighed water glass with an equal weight of water to obtain a water glass premix; C. Stirring and mixing: fully mix the aforementioned solid premix with the water glass premix to obtain a soil remediation agent.

6. The method for preparing a soil remediation agent for reducing copper pollution according to claim 5, characterized in that: In step A, the red mud is crushed to a particle size of -200 mesh, and the blast furnace slag is crushed and ground to a particle size of -200 mesh.

7. The method for preparing a soil remediation agent for reducing copper pollution according to claim 5, characterized in that: In step B, the Na2O content of the water glass accounts for 2-8% of the total weight of the red mud and blast furnace slag, and the modulus of the water glass is 1.2-1.

8.

8. The method for preparing a soil remediation agent for reducing copper pollution according to claim 7, characterized in that: The water glass in step B is adjusted with NaOH, and the amount of NaOH added to the water glass is calculated as follows: ， Where: G1 is the weight of water glass, N is the proportion of Na2O in water glass, M1 is the initial modulus of water glass, M2 is the target modulus of water glass, and P is the purity of NaOH.

9. An application of a soil remediation agent for reducing copper pollution, characterized in that: The soil remediation agent for reducing copper pollution according to claim 1, 2 or 3 is used in remediating copper-contaminated soil.

10. The use of the soil remediation agent for reducing copper pollution according to claim 9, characterized in that: The copper-contaminated soil to be repaired is fully mixed with a soil remediation agent with a dosage of 8-12%, and then cured for at least 7 days at 20-30°C and humidity ≥98% to complete the copper-contaminated soil remediation.

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