Comprehensive utilization method for preparing artificial covering soil from silicon-calcium slag

Abstract

The invention belongs to the technical field of comprehensive utilization of solid waste silicon-calcium slag, and relates to a comprehensive utilization method for preparing artificial covering soil from silicon-calcium slag. According to the method, solid waste silicon-calcium slag generated in the process of producing aluminum oxide from low-grade bauxite is used as a main raw material, and after low-temperature carbonation and ball milling treatment, the reaction activity and environmental stability of the solid waste silicon-calcium slag are remarkably improved. The preparation method comprises the following steps: mixing pretreated silicon-calcium slag with cement, desulfurized gypsum, fly ash and a compound additive (including light calcined magnesia powder, calcium hydrophosphate, sandstone and ammonium humate) in a specific proportion to form a composite gel system, and carrying out water adding, stirring and curing processes to prepare the artificial soil covering material with excellent compressive strength, pH buffer capability and heavy metal stability. The material is suitable for engineering scenes such as solid waste landfills, mining area greening, underground filling and ecological restoration, the silicon-calcium slag resource utilization is achieved, meanwhile, the soil structure function and ecological safety are considered, and good engineering applicability and popularization prospects are achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of comprehensive utilization of solid waste calcium silicon slag, and in particular relates to a comprehensive utilization method of calcium silicon slag in preparing artificial covering soil. Background Art

[0002] Artificial soil cover is an important research area in the current field of solid waste disposal and ecological restoration, playing a key role in the greening of mining areas, the transformation of industrial waste sites, and the closure of landfills. Ideal artificial soil cover materials must not only possess good physical stability and structural integrity, but also offer comprehensive advantages in terms of environmental friendliness, raw material sourcing, and cost control. However, most artificial soil cover materials currently used in the market rely on natural soil, peat, humus, or other organic-inorganic mixtures. These materials present a series of problems that need to be addressed in their practical application.

[0003] First, limited raw material sources hinder the large-scale application of artificial cover. With increased environmental governance efforts, demand for artificial cover is rapidly increasing, but high-quality natural soil resources are becoming increasingly scarce. Excavating large quantities of natural soil for artificial cover not only damages the existing ecosystem but also increases the overall cost of the project. Second, while fly ash, cement, lime, and other bulk materials commonly used in current artificial cover formulations provide a certain degree of mechanical strength and structural stability, they lack stability against heavy metals, corrosion resistance, and alkali resistance, posing environmental risks with long-term use.

[0004] Furthermore, some artificial cover materials lack effective physical and chemical barriers to the garbage or solid waste beneath them, leading to leachate leakage, heavy metal migration, or alkaline uptake, which in turn pollutes surrounding soil and groundwater. This is especially true when covering alkaline solid wastes such as coal gangue and metallurgical slag. Traditional cover soils are unable to effectively neutralize the high concentrations of alkaline components in the leachate, often resulting in a "white frost" phenomenon and deteriorating surface ecology.

[0005] While some current research is exploring the use of industrial solid wastes such as fly ash, steel slag, and desulfurized gypsum as alternative raw materials for artificial soil covering, and some results show promise, most approaches still face challenges such as unstable material properties, large composition fluctuations, insufficient early strength, and poor long-term durability. In particular, the core challenge facing current artificial soil covering technology is how to effectively solidify and long-term seal heavy metals and alkaline components while maintaining the material's mechanical properties.

[0006] At the same time, China's aluminum industry produces a large amount of by-product solid waste "silicon calcium slag" in the process of using low-grade bauxite to produce alumina. This type of solid waste contains a large amount of active mineral components such as β-dicalcium silicate and tricalcium aluminate. Its storage occupies a large area and has high processing costs, posing a threat to the ecological environment. Although a few studies have explored the use of silicon calcium slag in cement clinker, building materials and other fields, its large-scale resource application is still limited due to factors such as composition fluctuations and high sodium content. In particular, there is currently a lack of a systematic method to transform this type of solid waste into high-performance, environmentally friendly artificial cover materials that take into account the dual needs of ecological governance and resource recycling.

[0007] Therefore, there is an urgent need to develop a new type of artificial covering material suitable for the resource utilization of bulk industrial solid waste, especially silicon-calcium slag, to fundamentally break through the technical bottleneck of existing artificial covering and achieve the green circular development goal of "waste treatment with waste". Summary of the Invention

[0008] The purpose of the present invention is to provide a method for comprehensive utilization of calcium silicon slag to prepare artificial covering soil. The method uses calcium silicon slag produced in the process of producing alumina from low-grade bauxite as the main raw material, supplemented by an appropriate amount of additives, and can be directly applied to the preparation of covering soil materials in scenes such as solid waste landfills after uniform mixing. By adjusting the ingredients, the present invention can also be used for mine filling, yard damming, etc., and has extremely wide applications. This method not only effectively improves the resource utilization rate of calcium silicon slag and realizes "waste treatment with waste", but also the artificial covering soil obtained has good structural stability and environmental adaptability, low cost, wide application range, and significant economic and ecological benefits.

[0009] In order to achieve the above object, the present invention provides the following technical solutions:

[0010] A method for comprehensive utilization of calcium-silicon slag to prepare artificial covering soil comprises the following steps:

[0011] (1) Pretreatment of calcium-silicon slag: Carbonating the calcium-silicon slag in an atmosphere containing carbon dioxide, and then ball-milling the carbonated calcium-silicon slag to obtain pretreated calcium-silicon slag;

[0012] (2) artificial covering soil ingredients: pre-treated calcium silicate slag, cement, gypsum, fly ash and compound additives are mixed to obtain a mixture; wherein the compound additives include light-burned magnesium oxide powder, calcium hydrogen phosphate, sandstone and ammonium humate;

[0013] (3) Adding water and stirring: adding water to the mixture of step (2) and stirring to form a slurry;

[0014] (4) Stacking and curing: The slurry from step (3) is stacked and cured to obtain artificial covering material.

[0015] Furthermore, the calcium silicate slag in step (1) is a solid waste calcium silicate slag produced by producing alumina from low-grade bauxite, wherein the silicon dioxide content is 15-40%, the calcium oxide content is 30-60%, the sodium oxide content is 0.5-3%, the physical phases are mainly β-dicalcium silicate, tricalcium aluminate, calcium aluminosilicate, etc., and the moisture content of the calcium silicate slag is 0-95%.

[0016] Furthermore, the carbonation treatment in step (1) is specifically as follows: placing the silica-calcium slag in a closed or semi-closed reaction device, introducing a mixed gas of carbon dioxide and air, wherein the volume fraction of carbon dioxide in the mixed gas is 5-40%, and reacting at 20-95° C. for 30-120 minutes.

[0017] Furthermore, the ball milling time in step (1) is 20-60 minutes, and the particle size of the pretreated calcium-silicon slag is 20-50 μm.

[0018] Through carbonation treatment, the residual free calcium oxide (CaO) in the calcium silicate slag reacts with CO2 to form calcium carbonate. The microcrystalline calcium carbonate generated by these reactions will cover the surface of the particles, playing a role in passivating alkalinity, stabilizing the structure, and improving the environmental compatibility of the slag. After carbonation, the calcium silicate slag is removed and immediately mechanically activated to reduce the slag particle size to a range of 20-50μm, significantly increasing the surface active sites and exposing the crystal faces of minerals such as β-dicalcium silicate and tricalcium aluminate. This promotes their subsequent bonding reaction with exogenous calcium sulfate, cement hydration products, and active silica-alumina components in fly ash, forming a variety of CSH, CAH and ettringite hydrates, thereby improving the overall structural density and erosion resistance.

[0019] Furthermore, in step (2), the amount of light-burned magnesium oxide powder added is 40-60% of the total amount of the compound additive, the amount of calcium hydrogen phosphate added is 10-30% of the total amount of the compound additive, the amount of ammonium humate added is 10-30% of the total amount of the compound additive, and the amount of sandstone added is 5-40% of the total amount of the compound additive.

[0020] Furthermore, the mixture in step (2) comprises, by weight, 400-550 parts of silica-calcium slag, 10-30 parts of cement, 40-120 parts of gypsum, 100-200 parts of fly ash and 2-8 parts of compound additives.

[0021] Furthermore, the gypsum in step (2) is desulfurized gypsum.

[0022] Furthermore, the pozzolanic activity of the fly ash in step (2) is ≥65%.

[0023] The core ingredients of the artificial covering formula of the present invention use pretreated calcium silicate slag as the main aggregate, combined with a certain proportion of cement, desulfurized gypsum and fly ash to form a composite cementitious system, and realize the early strength formation and later stability improvement of the material through multiphase reaction. Among them, during the carbonation and ball milling process of the pretreated calcium silicate slag, the reactive minerals such as β-dicalcium silicate and tricalcium aluminate inside it are exposed and activated, participating in the subsequent hydration reaction, and synergizing with the active silicon and aluminum components in calcium sulfate, cement and fly ash to generate various hydration products such as calcium silicate hydrate (CSH) and calcium aluminate hydrate (CAH), which are cross-linked and filled on a microscopic scale to form a continuous and dense spatial skeleton, thereby providing structural support and the ability to resist penetration erosion.

[0024] The introduction of cement mainly plays a role in the development of early strength. The hydration reaction of tricalcium silicate (C3S) and belite (C2S) provided by cement releases a large amount of Ca 2+ , further reacting with the activated slag and the silicon and aluminum components in the fly ash to promote the formation of CSH gel; gypsum provides SO4 2- ions, together with calcium aluminate and calcium ions, form ettringite, which assists in the construction of the crystal skeleton and improves the material's resistance to shrinkage and cracking; fly ash, as a potential active admixture, its micro-glassy structure gradually dissociates into silicates and aluminates in an alkaline environment, and synergizes with cement and slag to produce a "secondary gelling reaction", enhancing the bulk density and extending the material reaction cycle, so that the structural strength continues to increase in the middle and late stages, while improving fluidity and construction adaptability.

[0025] The compound additives introduced into the formula are key functional enhancement factors. Lightly burned magnesium oxide powder, due to its high reactivity, can form low-crystallinity magnesium silicate hydrate and magnesium aluminate hydrate with residual free SiO2 and Al2O3 in the slag, helping to build an amorphous structure network. At the same time, its alkalinity can moderately neutralize the acidic groups in the system, forming a buffer zone and stabilizing the pH value. Calcium hydrogen phosphate provides phosphate ions that can participate in the precipitation reaction, and reacts with Mg in a high pH environment. 2+ , Ca 2+ The reaction generates low-solubility phosphate precipitates, such as MgNH4PO4·6H2O or hydroxyapatite, which effectively improves the fixation capacity of heavy metal ions and provides a certain slow-release phosphorus source, improving the soil nutrient structure. Ammonium humate is rich in active complexing groups such as carboxyl and phenolic hydroxyl groups, which can chelate Cu 2+ , Pb 2+ 、Cd 2+Humic acid organic matter can also provide a carbon source for soil microorganisms, promoting microecological balance and vegetation adaptability. As a natural siliceous-aluminous aggregate, sandstone has high structural stability and good particle grading characteristics. It plays a role in strengthening the skeleton and regulating pores in the system. It also enhances the overall density and mechanical stability of the material through interfacial bonding with the cementitious material, while also improving the material's stability and durability during wet-dry cycles.

[0026] Furthermore, the amount of water added in step (3) is such that the water content of the mixture reaches 20-40%.

[0027] Furthermore, the curing time in step (4) is 1-7 days.

[0028] Compared with the prior art, the advantages and beneficial effects of the present invention are:

[0029] This method pre-treats calcium silicate slag through carbonation and ball milling to stimulate its potential activity, reduce the risk of alkali release, and enhance reactivity. The compounded additives introduced into the formula synergistically control pH, solidify heavy metals, and improve ecological adaptability, addressing the poor efflorescence resistance, structural instability, and lack of environmental compatibility of traditional materials. The resulting artificial covering soil exhibits excellent strength, stability, and eco-friendliness, capable of absorbing large-scale industrial solid wastes such as calcium silicate slag, achieving "waste-to-waste" treatment. It offers significant economic and environmental benefits in resource utilization, environmental remediation, and the development of low-carbon building materials. DETAILED DESCRIPTION

[0030] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0031] Unless otherwise specified, the raw materials used in the examples are common commercially available products, and the following are exemplary purchase sources.

[0032] Cement was purchased from Anhui Conch Group Co., Ltd., PO 42.5.

[0033] Desulfurization gypsum was purchased from Huaneng Power International Co., Ltd.

[0034] The fly ash was purchased from Shandong Tai'an Huaneng Power Plant, which is Grade II fly ash with a pozzolanic activity index of ≥88%.

[0035] Light-burned magnesium oxide powder was purchased from Tianjin Meihong Chemical Co., Ltd. with an average particle size of 200 mesh.

[0036] Calcium hydrogen phosphate was purchased from Shandong Jiuan Chemical Co., Ltd.

[0037] Ammonium humate was purchased from Hubei Longfei Biotechnology Co., Ltd.

[0038] Example 1

[0039] This embodiment provides a method for comprehensive utilization of calcium-silicon slag in preparing artificial covering soil, comprising the following steps:

[0040] (1) Pretreatment of calcium silicate slag: The raw material is calcium silicate slag produced in the process of producing alumina from low-grade bauxite of China Aluminum Corporation Shanxi Branch. The chemical composition of the calcium silicate slag includes: 35.6% silicon dioxide, 49.8% calcium oxide, 1.2% sodium oxide, and the phase is mainly composed of β-dicalcium silicate, tricalcium aluminate and calcium aluminosilicate, with a moisture content of about 28%;

[0041] The calcium silicate slag is placed in a closed reactor and a mixed gas consisting of carbon dioxide and air is introduced for carbonation treatment, wherein the volume fraction of carbon dioxide in the mixed gas is 10%, the reaction temperature is maintained at 25°C, and the reaction time is 45 minutes;

[0042] After the carbonation treatment, the calcium silicate slag was immediately put into a planetary ball mill for mechanical activation treatment. The ball milling parameters were set at a speed of 300 rpm and a time of 40 minutes. Finally, the particles were ground to an average particle size of 30 μm and a specific surface area of ​​about 6800 cm 2 / g, to obtain pretreated calcium-silicon slag;

[0043] (2) Artificial covering soil ingredients: The raw materials are mixed according to the following weight ratios: 500 parts of pre-treated calcium silicate slag, 20 parts of cement, 80 parts of desulfurized gypsum, 150 parts of fly ash, 6 parts of compound additives, including: 2.5 parts of light-burned magnesium oxide powder, 1.25 parts of calcium hydrogen phosphate, 1.25 parts of ammonium humate, and 1 part of sandstone;

[0044] The above dry powder raw materials were added into a high-speed dry mixer in sequence and stirred for 10 minutes to mix them evenly to obtain a mixture;

[0045] (3) Adding water and stirring: Add water to the mixture while stirring until the overall moisture content of the mixture reaches 25%, and continue stirring for 5 minutes to obtain a slurry with good plasticity and uniform distribution;

[0046] (4) Stacking and curing: The mixed slurry is immediately spread in a curing tank covered with a plastic film with a thickness of about 10 cm, and sealed with a plastic film. Cured at room temperature of 25±2°C and relative humidity of about 70% for 5 days to obtain artificial covering soil material.

[0047] Comparative Example 1

[0048] This comparative example provides a comprehensive utilization method for preparing artificial covering soil using calcium silicon slag, which differs from Example 1 in that the calcium silicon slag is not pretreated and is directly used as an ingredient for artificial covering soil.

[0049] Comparative Example 2

[0050] This comparative example provides a method for comprehensive utilization of calcium silicate slag in preparing artificial covering soil, which differs from Example 1 in that: in step (2), the raw materials are mixed according to the following weight parts: 500 parts of pretreated calcium silicate slag, 60 parts of cement, 20 parts of desulfurized gypsum, 150 parts of fly ash, and 6 parts of compound additives, including: 2.5 parts of light-burned magnesium oxide powder, 1.25 parts of calcium hydrogen phosphate, 1.25 parts of ammonium humate, and 1 part of sandstone.

[0051] Comparative Example 3

[0052] This comparative example provides a method for comprehensive utilization of calcium silicate slag to prepare artificial covering soil, which differs from Example 1 in that: in step (2), the raw materials are mixed according to the following weight parts: 500 parts of pretreated calcium silicate slag, 20 parts of cement, 80 parts of desulfurized gypsum, 150 parts of fly ash, and 6 parts of compound additives, including: 1 part of light-burned magnesium oxide powder, 2 parts of calcium hydrogen phosphate, 2 parts of ammonium humate, and 1 part of sandstone.

[0053] Comparative Example 4

[0054] This comparative example provides a comprehensive utilization method for preparing artificial covering soil using calcium silicate slag, which differs from Example 1 in that no compound additive is added in step (2).

[0055] Comparative Example 5

[0056] This comparative example provides a comprehensive utilization method for preparing artificial covering soil using silica-calcium slag, which differs from Example 1 in that the compound additive in step (2) is replaced by 2.5 parts of limestone powder, 1.25 parts of bentonite, 1.25 parts of sodium humate, and 1 part of sandstone.

[0057] Performance Testing

[0058] In order to evaluate the performance of the artificial covering soil material, the compressive strength, pH value, alkalinity release and Zn content of the artificial covering soil prepared in Example 1 and Comparative Examples 1-5 were tested. 2+ Testing of four indicators of leaching concentration.

[0059] The compressive strength was tested with reference to GB / T 17671-2021. The soil samples cured for 5 days were made into 40mm×40mm×40mm cubic specimens. The compressive strength was measured using a pressure testing machine (loading rate 2.4kN / s) to evaluate the structural integrity and construction adaptability of the material.

[0060] The pH value was tested with reference to HJ 962-2018. The sample was added into deionized water at a ratio of 1:10 (mass / volume). After soaking for 2 hours, the pH value of the supernatant was measured to reflect the impact of the material on the environmental pH.

[0061] The alkalinity release was tested according to HJ / T 299-2007. The sample was added to the acetate buffer at a ratio of 1:10 (mass / volume), shaken for 18 hours, filtered, and the OH content in the supernatant was determined. - The release amount, measured in NaOH equivalent concentration, is used to evaluate the alkali release risk and anti-efflorescence ability of the material.

[0062] Zn 2+ The leaching concentration was tested according to GB 5085.3-2007. The sample was added to the acetate buffer at a ratio of 1:10 (mass / volume), shaken for 18 hours and filtered. The filtrate was adjusted to pH <2 with HNO3 and the Zn content was determined by atomic absorption spectrometry. 2+ The content reflects its ecological safety and heavy metal stabilization ability.

[0063] The test results are shown in Table 1.

[0064] Table 1 Performance test results

[0065]

[0066]

[0067] The above results show that Example 1 of the present invention performs best in all four key properties: its compressive strength is significantly higher than that of the comparative examples, the pH value is controlled within the range suitable for plant growth and environmental safety, and the alkalinity release is the lowest, indicating that the material has excellent alkaline stability; Zn 2+ The leaching concentration is controlled at an extremely low level, far below the hazardous waste determination line (5 mg / L), indicating that the compound additive has a good fixation effect on heavy metals.

[0068] Comparative Example 1 did not pre-treat the calcium silicate slag, resulting in the free calcium oxide in the material not being passivated. Its alkalinity release was strong, the pH value was as high as 9.1, and the alkalinity release amount reached 7.3 mg / L, which was significantly higher than that of Example 1. This high alkaline environment is not conducive to plant growth and is prone to efflorescence. At the same time, since the reactive minerals in the calcium silicate slag were not activated, the degree of hydration reaction was low, the gel product generated was small, and the structure was loose, resulting in a compressive strength of only 0.22 MPa. In addition, its Zn 2+ The fixation capacity is insufficient, and the leaching concentration reaches 0.064 mg / L, which is significantly higher than that of the embodiment, and the ecological safety is poor.

[0069] In the formula of Comparative Example 2, the amount of cement used was significantly excessive, while the proportion of gypsum was seriously insufficient. This ratio caused a strong alkaline reaction in the system, with the pH value rising to 8.7 and the alkalinity release amount being 6.1 mg / L. There was still a strong risk of efflorescence. Although the excess cement brought a certain early strength improvement (compressive strength of 0.30 MPa), due to the lack of sufficient SO4 2- Participate in the formation of ettringite, the overall structural adjustment ability is insufficient, Zn 2+ The leaching concentration was 0.057 mg / L, and the heavy metal stabilization effect was not ideal.

[0070] In Comparative Example 3, the ratio of the compound additives was adjusted, the proportion of light-burned magnesium oxide powder was reduced, the structural forming performance of the system was improved, the compressive strength was increased to 0.34MPa, the pH value was controlled at 7.6, and the alkalinity release was 3.9mg / L, which was relatively good. However, due to the insufficient proportion of MgO, the system had a poor resistance to OH - The sustained release and inhibition ability of the metal ions decreased, the precipitation reaction of the metal ions was insufficient, and Zn 2+ The leaching concentration was 0.038 mg / L, and the fixation effect was still lower than that in the embodiment.

[0071] Comparative Example 4 did not add compound additives, lacked the coordinated regulation of MgO, phosphate and organic complexing agent, resulting in insufficient structural bonding and a compressive strength of only 0.25 MPa. At the same time, the system released a serious alkalinity, with a pH value of 8.8 and an alkalinity release of up to 6.8 mg / L, resulting in a significant risk of efflorescence. The lack of the complexing ability of organic components such as humic acid on heavy metals resulted in the Zn 2+ The leaching concentration increased to 0.055 mg / L, and the ecological adaptability was poor.

[0072] Comparative Example 5 uses traditional limestone powder, bentonite and sodium humate to replace some components of the compound additive. The overall performance is slightly better than Comparative Example 4 without adding additives, but still significantly lower than the examples.

[0073] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for comprehensive utilization of calcium silicon slag to prepare artificial covering soil, comprising the following steps: (1) Pretreatment of calcium-silicon slag: Carbonating the calcium-silicon slag in an atmosphere containing carbon dioxide, and then ball-milling the carbonated calcium-silicon slag to obtain pretreated calcium-silicon slag; (2) artificial covering soil ingredients: pre-treated calcium silicate slag, cement, gypsum, fly ash and compound additives are mixed to obtain a mixture; wherein the compound additives include light-burned magnesium oxide powder, calcium hydrogen phosphate, sandstone and ammonium humate; (3) Adding water and stirring: adding water to the mixture of step (2) and stirring to form a slurry; (4) Stacking and curing: The slurry from step (3) is stacked and cured to obtain artificial covering material.

2. The method for comprehensive utilization of calcium-silicon slag for preparing artificial covering soil according to claim 1, characterized in that: The calcium-silicon slag in step (1) is solid waste calcium-silicon slag produced by producing alumina from low-grade bauxite, wherein the silicon dioxide content is 15-40%, the calcium oxide content is 30-60%, the sodium oxide content is 0.5-3%, and the moisture content of the calcium-silicon slag is 0-95%.

3. The method for comprehensive utilization of calcium-silicon slag for preparing artificial covering soil according to claim 1, characterized in that: The carbonation treatment in step (1) is specifically as follows: placing the silica-calcium slag in a closed or semi-closed reaction device, introducing a mixed gas of carbon dioxide and air, wherein the volume fraction of carbon dioxide in the mixed gas is 5-40%, and reacting at 20-95° C. for 30-120 minutes.

4. The method for comprehensive utilization of calcium-silicon slag for preparing artificial covering soil according to claim 1, characterized in that: The ball milling time in step (1) is 20-60 minutes, and the particle size of the pretreated calcium-silicon slag is 20-50 μm.

5. The method for comprehensive utilization of calcium-silicon slag for preparing artificial covering soil according to claim 1, characterized in that: In step (2), the amount of light-burned magnesium oxide powder added is 40-60% of the total amount of the compound additive, the amount of calcium hydrogen phosphate added is 10-30% of the total amount of the compound additive, the amount of ammonium humate added is 10-30% of the total amount of the compound additive, and the amount of sandstone added is 5-40% of the total amount of the compound additive.

6. The method for comprehensive utilization of calcium-silicon slag for preparing artificial covering soil according to claim 1, characterized in that: The mixture in step (2) comprises, by weight, 400-550 parts of silica-calcium slag, 10-30 parts of cement, 40-120 parts of gypsum, 100-200 parts of fly ash and 2-8 parts of compound additives.

7. The method for comprehensive utilization of calcium-silicon slag for preparing artificial covering soil according to claim 1, characterized in that: The gypsum in step (2) is desulfurized gypsum.

8. The method for comprehensive utilization of calcium-silicon slag for preparing artificial covering soil according to claim 1, characterized in that: The pozzolanic activity of the fly ash in step (2) is ≥65%.

9. The method for comprehensive utilization of calcium-silicon slag for preparing artificial covering soil according to claim 1, characterized in that: The amount of water added in step (3) is such that the water content of the mixture reaches 20-40%.

10. The method for comprehensive utilization of calcium-silicon slag for preparing artificial covering soil according to claim 1, characterized in that: The curing time in step (4) is 1-7 days.

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