Mining area soil remediation method

Abstract

The invention belongs to the technical field of agricultural biology and soil remediation, and particularly relates to a mining area soil remediation method. The method comprises the following steps: performing soil reconstruction on a mining area to obtain reconstructed soil with a multi-layer structure; the reconstructed soil of the multi-layer structure sequentially comprises a reconstruction layer, a blocking layer and a filling layer from top to bottom. The reconstruction layer comprises low-carbon coal gangue and surface soil, the particle size of the low-carbon coal gangue is smaller than or equal to 8 mm, and the mass ratio of the low-carbon coal gangue to the surface soil is (1-2): (1-2); the blocking layer comprises a grouting mixture of fly ash and cement, and the mass ratio of the fly ash to the cement is smaller than or equal to 1.8: 1; the filling layer comprises blocky waste coal gangue; and then planting alfalfa on the reconstructed soil with the multilayer structure. According to the method, recycling of the waste coal gangue and reconstruction of the mining area soil are realized, so that smooth germination and healthy growth of alfalfa seeds on the reconstructed soil are ensured, mining area soil remediation is realized, and an economical and feasible method is provided for mining area soil remediation.

Description

Technical Field

[0001] The invention belongs to the technical field of agricultural biology and soil restoration, and in particular relates to a method for restoring soil in a mining area. Background Art

[0002] At present, the mining activities of mineral resources have caused serious damage to the soil environment in the mining area, and the soil quality has been significantly affected. Mining activities in the mining area, the accumulation of abandoned coal gangue, and insufficient utilization have caused great impacts on the local soil environment, including surface subsidence, resulting in a decrease in the depth of shallow groundwater levels, soil salinization in the surface subsidence area, loss of nutrients and organic matter, and reduced soil moisture retention capacity. The salinization of the soil in the mining area and the change of the groundwater level have brought great challenges to the growth of vegetation, especially the growth of vegetation such as alfalfa that is sensitive to soil conditions.

[0003] One of the current methods of mine area remediation is covering with imported soil, but this method requires a large amount of imported soil, has high construction costs, and cannot be effectively implemented for mine soil remediation in remote areas. Summary of the invention

[0004] The purpose of the present invention is to provide a method for soil remediation in mining areas. The method provided by the present invention realizes the recycling of waste coal gangue and the reconstruction of mining area soil, thereby promoting the growth of alfalfa on the reconstructed soil, realizing the effective remediation of mining area soil, and providing an economically feasible method for soil remediation in mining areas.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] The present invention provides a method for soil remediation in a mining area, comprising the following steps:

[0007] The soil in the mining area is reconstructed to obtain a reconstructed soil with a multi-layer structure; the reconstructed soil with the multi-layer structure includes, from top to bottom, a reconstruction layer, a barrier layer and a filling layer; the reconstruction layer includes low-carbon coal gangue and surface soil, the low-carbon coal gangue is coal gangue with a carbon content of less than 4wt%, the particle size of the low-carbon coal gangue is ≤8mm, and the mass ratio of the low-carbon coal gangue to the surface soil is (1-2):(1-2); the barrier layer includes a grouting mixture of fly ash and cement, the mass ratio of the fly ash to the cement is ≤1.8:1; the filling layer includes blocky waste coal gangue;

[0008] Alfalfa is planted on the reconstructed soil of the multi-layer structure.

[0009] Preferably, the reconstruction layer further comprises organic nutrient soil;

[0010] The reconstructed layers include, from top to bottom, a first reconstructed surface layer, an organic nutrient soil layer and a second reconstructed surface layer; the first reconstructed surface layer and the second reconstructed surface layer are formed by a mixture of the low-carbon coal gangue and surface soil; the thickness of the first reconstructed surface layer is 1 to 2 cm, and the thickness of the organic nutrient soil layer is 1 to 2 cm.

[0011] Preferably, the particle size of the low carbon coal gangue is 2 to 8 mm;

[0012] The mass ratio of the low-carbon coal gangue to the surface soil is 2:1.

[0013] Preferably, the thickness of the reconstruction layer is 40 to 60 cm.

[0014] Preferably, the mass ratio of fly ash to cement is (1.2-1.8):1.

[0015] Preferably, the mass ratio of fly ash to cement is 1.5:1.

[0016] Preferably, the thickness of the barrier layer is 15 to 35 cm.

[0017] Preferably, the thickness of the barrier layer is 20 cm.

[0018] Preferably, the filling layer has a thickness of 20 to 40 cm.

[0019] Preferably, the thickness of the filling layer is 20 cm.

[0020] The present invention provides a method for soil remediation in a mining area, comprising the following steps: reconstructing the soil in the mining area to obtain a reconstructed soil with a multi-layer structure; the reconstructed soil with a multi-layer structure comprises, from top to bottom, a reconstruction layer, a barrier layer and a filling layer; the reconstructed layer comprises low-carbon coal gangue and surface soil, the low-carbon coal gangue is coal gangue with a carbon content of less than 4wt%, the particle size of the low-carbon coal gangue is ≤8mm, and the mass ratio of the low-carbon coal gangue to the surface soil is (1-2): (1-2); the barrier layer comprises a grouting mixture of fly ash and cement, the mass ratio of the fly ash to the cement is ≤1.8:1; the filling layer comprises blocky waste coal gangue; and alfalfa is planted on the reconstructed soil with a multi-layer structure. Compared with the prior art, the present invention has the following beneficial effects:

[0021] The present invention significantly improves the suitability of alfalfa growth: the present invention reconstructs the soil in the mining area, and the obtained multi-layer structure reconstructed soil optimizes the multi-layer structure soil environment, thereby significantly improving the suitability of alfalfa growth. The mixture of surface soil and low-carbon coal gangue in the reconstructed layer effectively improves the physical properties and fertility of the soil, provides rich minerals and nutrients, and promotes the rapid germination of alfalfa seeds. The experimental results show that the germination speed of alfalfa is significantly accelerated by using the reconstructed soil with a multi-layer structure reconstructed by the present invention to plant alfalfa, ensuring the smooth germination of more alfalfa seeds; the barrier layer composed of cement and fly ash effectively regulates the moisture and gas exchange of the soil, maintains the appropriate humidity and oxygen content, and prevents excessive evaporation of water and water accumulation. This moisture management mechanism not only supports the healthy growth of alfalfa seedlings, but also reduces the risk of root hypoxia, thereby further improving the number of germinations and the survival rate of plants. The filling layer uses blocky abandoned coal gangue as the main material, which provides excellent drainage performance and physical support, prevents soil compaction, and promotes the in-depth development of the root system. The stability and durability of the massive waste coal gangue ensure the long-term stability of the soil structure and support the tall growth of alfalfa plants. Experimental data show that the height of alfalfa plants is significantly increased when the reconstructed soil with a multi-layer structure reconstructed by the present invention is used to plant alfalfa.

[0022] The reconstructed soil of the multi-layer structure reconstructed by the present invention improves the soil's water retention and drainage capabilities: the barrier layer and the filling layer in the multi-layer structure work together to effectively retain moisture in the soil and prevent excessive evaporation of moisture, and quickly remove excess moisture to avoid soil compaction and root hypoxia. The barrier layer mixed with cement and fly ash performs well in regulating moisture, and the massive coal gangue filling layer provides an excellent drainage channel to ensure the stable growth of alfalfa under different climatic conditions.

[0023] The reconstructed soil with a multi-layer structure reconstructed by the present invention finds a new way to treat solid wastes such as coal gangue: The present invention effectively integrates and utilizes various solid waste materials, such as coal gangue, fly ash, etc., through a multi-layer structure design, reduces the pollution of solid waste to the environment, promotes the recycling of resources, and has significant environmental benefits and economic value. The reconstruction layer is made of a mixture of surface soil and low-carbon coal gangue, the middle layer is a barrier layer mixed with cement and fly ash, and the filling layer uses block waste coal gangue as the main material. The block waste coal gangue has good physical stability and durability, ensuring the structural integrity and environmental safety of the filling layer in long-term use, and can effectively solidify and seal solid waste to prevent its diffusion in the environment and secondary pollution. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The germination rate data statistics of each experimental group in Example 1 of the present invention are as follows;

[0025] Figure 2The statistical results of the average root length data of each experimental group in Example 1 of the present invention;

[0026] Figure 3 It is the statistical result of the average plant height data of each experimental group in Example 1 of the present invention. DETAILED DESCRIPTION

[0027] The present invention provides a method for soil remediation in a mining area, comprising the following steps:

[0028] The soil in the mining area is reconstructed to obtain a reconstructed soil with a multi-layer structure; the reconstructed soil with the multi-layer structure includes, from top to bottom, a reconstruction layer, a barrier layer and a filling layer; the reconstruction layer includes low-carbon coal gangue and surface soil, the low-carbon coal gangue is coal gangue with a carbon content of less than 4wt%, the particle size of the low-carbon coal gangue is ≤8mm, and the mass ratio of the low-carbon coal gangue to the surface soil is (1-2):(1-2); the barrier layer includes a grouting mixture of fly ash and cement, the mass ratio of the fly ash to the cement is ≤1.8:1; the filling layer includes blocky waste coal gangue;

[0029] Alfalfa is planted on the reconstructed soil of the multi-layer structure.

[0030] In the present invention, unless otherwise specified, all preparation raw materials / components are commercially available products well known to those skilled in the art.

[0031] The present invention reconstructs soil in a mining area to obtain a reconstructed soil with a multi-layer structure; the reconstructed soil with a multi-layer structure includes, from top to bottom, a reconstruction layer, a barrier layer and a filling layer; the reconstructed layer includes low-carbon coal gangue and surface soil, the low-carbon coal gangue is coal gangue with a carbon content of less than 4wt%, the particle size of the low-carbon coal gangue is ≤8mm, and the mass ratio of the low-carbon coal gangue to the surface soil is (1-2):(1-2); the barrier layer includes a grouting mixture of fly ash and cement, the mass ratio of the fly ash to the cement is ≤1.8:1; the filling layer includes blocky waste coal gangue.

[0032] The multi-layered reconstructed soil provided by the present invention includes a reconstructed layer. In the present invention, the reconstructed layer includes low-carbon coal gangue and surface soil. The low-carbon coal gangue is coal gangue with a carbon content of less than 4wt%. The particle size of the low-carbon coal gangue is ≤8mm, preferably 2-8mm, and most preferably 2mm. The surface soil is preferably the surface soil of the mining area.

[0033] In the present invention, the reconstruction layer preferably also includes organic nutrient soil.

[0034] In the present invention, the reconstructed layer preferably includes, from top to bottom, a first reconstructed surface layer, an organic nutrient soil layer and a second reconstructed surface layer.

[0035] In the present invention, the first reconstructed surface layer is preferably formed by a mixture of the low-carbon coal gangue and the surface soil, and the low-carbon coal gangue is a coal gangue with a carbon content of less than 4wt%. The particle size of the low-carbon coal gangue is ≤8mm, preferably 2-8mm, and most preferably 2mm. The surface soil is preferably the surface soil of the mining area. The mass ratio of low-carbon coal gangue to surface soil in the first reconstructed surface layer is (1-2): (1-2), preferably 2:1. The thickness of the first reconstructed surface layer is preferably 1-2cm, and can be 2cm in the embodiment.

[0036] In the present invention, the organic nutrient soil layer is preferably composed of organic nutrient soil. The thickness of the organic nutrient soil layer is preferably 1 to 2 cm, and in the embodiment, it can be 1 cm. The organic nutrient soil layer serves as the nutrient material layer of the alfalfa.

[0037] In the present invention, the second reconstructed surface layer is preferably formed by a mixture of the low-carbon coal gangue and the surface soil, wherein the low-carbon coal gangue is a coal gangue with a carbon content of less than 4wt%. The particle size of the low-carbon coal gangue is ≤8mm, preferably 2-8mm, and most preferably 2mm. The surface soil is preferably the surface soil of the mining area. The mass ratio of the low-carbon coal gangue to the surface soil in the second reconstructed surface layer is (1-2): (1-2), preferably 2:1.

[0038] In the present invention, the thickness of the reconstruction layer (ie, the total thickness of the reconstruction layer) is preferably 30 to 60 cm, more preferably 40 to 60 cm, and most preferably 60 cm.

[0039] The multi-layered reconstructed soil provided by the present invention comprises a barrier layer arranged on the lower surface of the reconstructed layer. In the present invention, the barrier layer comprises a grouting mixture of fly ash and cement. The fly ash is preferably industrial-grade fly ash. The cement is preferably ordinary Portland cement. The mass ratio of the fly ash to the cement is ≤1.8:1, preferably (1.2-1.8):1, and more preferably 1.5:1. The thickness of the barrier layer is preferably 15-35 cm, and more preferably 20 cm.

[0040] The multi-layered reconstructed soil provided by the present invention includes a filling layer arranged on the lower surface of the barrier layer. In the present invention, the filling layer includes block-shaped abandoned coal gangue. The block-shaped abandoned coal gangue is preferably naturally accumulated coal gangue of mining strippings. The present invention has no special requirements on the particle size of the block-shaped abandoned coal gangue. The present invention uses the block-shaped abandoned coal gangue as the filling layer of the multi-layered reconstructed soil, which can help to eliminate the abandoned coal gangue in the mining area. The thickness of the filling layer is preferably 20 to 40 cm, more preferably 20 cm. The present invention selects block-shaped abandoned coal gangue as the filling layer, which is not only conducive to the disposal of solid waste, but also conducive to improving the stability of the multi-layered reconstructed soil.

[0041] In the present invention, the method for reconstructing the multi-layered reconstructed soil preferably comprises the following steps:

[0042] The filling layer, the barrier layer and the reconstruction layer are prepared in sequence from bottom to top to obtain the reconstructed soil with the multi-layer structure.

[0043] In the present invention, the method for preparing the filling layer preferably comprises: laying block-shaped waste coal gangue to obtain the filling layer.

[0044] In the present invention, the method for preparing the barrier layer preferably comprises: mixing the fly ash, cement and water to obtain a barrier layer mixture; laying the barrier layer mixture on the upper surface of the filling layer, and drying to obtain the barrier layer. In the present invention, the mass content of the water in the barrier layer mixture is preferably 30-35%.

[0045] In the present invention, the preparation method of the reconstructed layer includes: grinding block low-carbon coal gangue; mixing the ground low-carbon coal gangue with surface soil to obtain a mixture of low-carbon coal gangue and surface soil; laying the mixture of low-carbon coal gangue and surface soil on the upper surface of the barrier layer to obtain the reconstructed layer; or after obtaining the mixture of low-carbon coal gangue and surface soil, laying the mixture of low-carbon coal gangue and surface soil on the upper surface of the barrier layer to obtain a second reconstructed surface layer, and then laying organic nutrient soil on the upper surface of the second reconstructed surface layer to obtain an organic nutrient soil layer; laying the upper surface of the organic nutrient soil layer on the upper surface of the barrier layer to obtain a first reconstructed surface layer to obtain the reconstructed layer. The grinding is preferably carried out in a grinder, and during the grinding, the feeding volume of the block low-carbon coal gangue does not exceed 50% of the total volume of the grinding bin of the grinder. The low-carbon coal gangue and the surface soil are preferably mixed in a barrel, and the mixing is preferably manually shaken.

[0046] After obtaining the reconstructed soil of the multi-layer structure, the present invention plants alfalfa on the reconstructed soil of the multi-layer structure. In the present invention, the alfalfa is purple alfalfa. In the present invention, the reconstructed layer preferably includes a first reconstructed surface layer, an organic nutrient soil layer and a second reconstructed surface layer from top to bottom, and the alfalfa seeds are preferably placed in the organic nutrient soil layer for germination and growth.

[0047] In order to further illustrate the present invention, the technical solutions provided by the present invention are described in detail below in conjunction with embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0048] Example 1

[0049] The present invention provides a method for soil remediation in a mining area, and the specific steps are as follows:

[0050] Reconstructing the soil in the mining area to obtain a multi-layer structured reconstructed soil; wherein the multi-layer structured reconstructed soil includes, from top to bottom, a reconstruction layer, a barrier layer, and a filling layer;

[0051] The reconstruction method of the multi-layer structured reconstructed soil includes:

[0052] (1) Use blocky waste coal gangue to lay the filling layer, and the thickness of the filling layer is 20 cm;

[0053] (2) Mix fly ash, cement and water (the mass ratio of fly ash to cement is 1.5:1, and the mass of water accounts for 30% of the mass of the obtained barrier layer mixture), spread the barrier layer, and after solidification, obtain the barrier layer, the thickness of the barrier layer is 20 cm;

[0054] (3) Put the lump of low-carbon coal gangue into the grinding chamber of the grinder for 2 minutes of grinding, and the input ratio shall not exceed 50% of the grinding chamber. The machine shall be cooled for 5 minutes after every four operations; obtain low-carbon coal gangue with a particle size of 2 mm; put the low-carbon coal gangue and the surface soil in a clean bucket, shake them manually, and pour them evenly onto the surface of the barrier layer with a shovel to obtain a second reconstructed surface layer, and then set a layer of organic nutrient soil (1 cm) on the second reconstructed surface layer, and finally set the first reconstructed surface layer (2 cm) on the organic nutrient soil layer to obtain a reconstructed layer.

[0055] In this embodiment, during the reconstruction process of the reconstructed soil column with a multi-layer structure, a probe for real-time monitoring of physical and chemical properties is buried.

[0056] Then, alfalfa was planted on the reconstructed soil with a multi-layer structure. The specific method is: dig a hole 2 cm above the surface of the reconstructed soil with a multi-layer structure, evenly spread 50 alfalfa seeds, water 5 mL every three days, monitor germination, vegetation growth (leaf width, plant height, etc.), and in October when the weather turns cooler, cover the soil column with film (two layers of film, the upper layer is closed), and evenly poke 9 holes in the lower layer for exhaust (exhaust 1 hour every 7 hours); in mid-October, there is insufficient light, and 4 growth lamps are added to supplement the light.

[0057] The present invention investigates the effects of the mass ratio of low-carbon coal gangue to surface soil in a reconstructed layer of reconstructed soil with a multi-layer structure and the thickness of the reconstructed layer on the growth of alfalfa.

[0058] Three groups of experiments were set up for the reconstruction layer of this embodiment. The mass ratio of the mixture of low-carbon coal gangue and surface soil in each group of experimental reconstruction layers (in the second reconstructed surface layer and the first reconstructed surface layer) was 1:1, 1:2, and 2:1. In order to explore the differences in the thickness of different reconstruction layers, ×1, ×2, and ×33 experiments were set up in each group according to the gradient changes of the total thickness of the reconstruction layer of 40cm, 50cm, and 60cm, and a control group was set up. In order to reduce the contingency of the experiment, A1-A3, B1-B3, and C1-C3 were repeated 3 times respectively; the barrier layer was a mixture of fly ash and cement in a mass ratio of 1.5:1, and the bottom layer was block coal gangue. The experimental scheme of this embodiment is shown in Table 1. Among them, the experimental control group (Group D): the reconstruction layer was surface soil, and the barrier layer and the filling layer were consistent with the experimental group.

[0059] Alfalfa was selected as the sowing object, and 50 seeds were sown in each soil column. The experiment started on September 20, 2024, with a 3-day cycle, and its growth indicators such as plant number, plant height, germination rate and germination time were recorded. The planned growth cycle of alfalfa was 45 days.

[0060] Table 1 Soil column test design

[0061] plan Low carbon coal gangue: topsoil (mass ratio) Reconstruction layer height (cm) A1 1:1 60 A2 1:1 50 A3 1:1 40 B1 1:2 60 B2 1:2 50 B3 1:2 40 C1 2:1 60 C2 2:1 50 C3 2:1 40 Control group D1 - 60 Control group D2 - 50 Control group D3 - 40

[0062] Note: A1-C3 in Table 1 were repeated three times, and the reconstruction layer of control group D was all topsoil.

[0063] Test results

[0064] (1) Germination rate: The percentage of germinated seeds to the total number of seeds. The calculation formula is as follows:

[0065] Germination rate = (number of germinated seeds / total number of seeds) × 100%;

[0066] Figure 1 The germination rate data statistics of each experimental group in Example 1 of the present invention are as follows. Figure 1It can be seen that: although the B1 treatment group showed a higher number of germinations, indicating that the scheme has certain advantages in promoting the germination of alfalfa seeds, the number of germinations in the B2 and B3 treatment groups was significantly reduced compared with B1, and there was a large difference. This shows that in the B group scheme, except for B1, the other treatments have unstable effects on germination, and it is difficult to ensure the smooth germination of alfalfa seeds. All treatments in group C (C1, C2, C3) showed a relatively stable number of germinations, and the number of germinations was at a high level. Compared with the volatility of group B, the germination effect of group C was more reliable. Based on the analysis results of the germination number graph, although the number of germinations in group B1 was large, the number of germinations in groups B2 and B3 was significantly lower, so the group B scheme had obvious deficiencies in overall stability and consistency. In contrast, the number of germinations in groups C1-C3 was stable and sufficient, showing higher reliability and consistency. Therefore, the group C scheme is a soil reconstruction scheme that is more suitable for alfalfa growth. This scheme can provide consistent and reliable germination effects, ensure the smooth germination and healthy growth of alfalfa seeds, and has better application prospects and promotion value.

[0067] (2) Average root length: The root length of alfalfa after the experiment was measured and calculated using the following formula:

[0068] Average root length = total root length / number of germinated seeds;

[0069] Figure 2 is the statistical result of the average root length data of each experimental group in Example 1 of the present invention, Figure 2 It can be seen that: among all the treatment groups, the root length of alfalfa in group C1 was significantly better than that in other groups. The average root length reached 5.0cm, which was significantly higher than that in other treatment groups. From the perspective of ratio, the average root length of alfalfa in the ratio of 2:1 between low-carbon coal gangue and topsoil was higher than that in the other two ratios; from the analysis of the thickness of the reconstruction layer, a thickness of 60cm was more suitable for the growth of alfalfa. Based on the analysis results of the root length graph, treatment group C1 showed significantly better root length performance than other schemes, proving that C1 is the most suitable soil reconstruction scheme for alfalfa growth. This scheme provides an ideal physical and chemical environment by optimizing the multi-layer structure and material ratio, significantly promoting the healthy development of the alfalfa root system, thereby improving the overall plant growth rate and yield.

[0070] (3) Average plant height: The average plant height after the test, calculated using the following formula:

[0071] Average plant height = total plant height / number of germinated seeds;

[0072] Figure 3 is the statistical result of the average plant height data of each experimental group in Example 1 of the present invention, Figure 3It can be seen that: among all the treatment groups, the average plant height of alfalfa in group C was significantly higher than that in other groups. In particular, the average plant height of group C1 reached 7.7 cm, which was significantly better than that of groups C2, C3, and other treatment groups such as A and B. Through variance analysis, the plant height of group C1 was significantly different from that of other groups (p<0.05), indicating that group C1 had a significant effect in promoting the plant height of alfalfa. In each treatment group, the average plant height of treatment No. 1 (i.e. C1) (60 cm thickness) in group C was the highest, namely A1, B1, and C1. This shows that in different groups, the reconstruction scheme with a thickness of 60 cm can effectively promote the growth of alfalfa and achieve the best plant height performance. Although groups A1 and B1 performed well in their respective groups, the overall average plant height was still lower than that of group C. This shows that the multi-layer structure design and material ratio of group C have greater advantages in promoting the plant height of alfalfa.

[0073] Based on the comprehensive analysis results of the experiments in this embodiment, Group C (the mass ratio of low-carbon coal gangue and topsoil is 2:1, and the multi-layer structure) and especially Group C1 (the mass ratio of low-carbon coal gangue and topsoil is 2:1, and the thickness is 60 cm) were determined to be the most suitable soil reconstruction scheme for alfalfa growth.

[0074] This embodiment provides an ideal physical and chemical environment for the growth of alfalfa by optimizing the multi-layer structure and material ratio of the reconstructed soil of the multi-layer structure. The 60 cm thickness provides a more stable and optimized soil environment, including better water management, nutrient supply and root support, thereby promoting the tall growth of the plant. The multi-layer structure adopted, especially the barrier layer of cement and fly ash mixed in the middle layer and the massive coal gangue in the filling layer, provide ideal water retention and drainage capabilities, supporting the healthy development of the alfalfa root system and the tall growth of the plant. The germination rate, root length and plant height of alfalfa were significantly improved, ensuring that alfalfa thrives in an efficient and healthy growth environment. The C1 scheme not only performs well in promoting the growth of alfalfa, but also has good environmental friendliness and economic feasibility, and has broad application prospects and promotion value.

[0075] From the above embodiments, it can be seen that the mining area soil remediation method provided by the present invention realizes the recycling of waste coal gangue and the reconstruction of mining area soil, thereby ensuring the smooth germination and healthy growth of alfalfa seeds on the reconstructed soil, realizing mining area soil remediation, and providing an economically feasible method for mining area soil remediation.

[0076] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention, not all of the embodiments. Other embodiments can be obtained based on this embodiment without creativity, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for soil remediation in a mining area, characterized in that: The following steps are involved: The soil in the mining area is reconstructed to obtain a reconstructed soil with a multi-layer structure; the reconstructed soil with the multi-layer structure includes, from top to bottom, a reconstruction layer, a barrier layer and a filling layer; the reconstruction layer includes low-carbon coal gangue and surface soil, the low-carbon coal gangue is coal gangue with a carbon content of less than 4wt%, the particle size of the low-carbon coal gangue is ≤8mm, and the mass ratio of the low-carbon coal gangue to the surface soil is (1-2):(1-2); the barrier layer includes a grouting mixture of fly ash and cement, the mass ratio of the fly ash to the cement is ≤1.8:1; the filling layer includes blocky waste coal gangue; Alfalfa is planted on the reconstructed soil of the multi-layer structure.

2. The method for soil remediation in mining areas according to claim 1, characterized in that: The reconstructed layer also includes organic nutrient soil; The reconstructed layers include, from top to bottom, a first reconstructed surface layer, an organic nutrient soil layer and a second reconstructed surface layer; the first reconstructed surface layer and the second reconstructed surface layer are formed by a mixture of the low-carbon coal gangue and surface soil; the thickness of the first reconstructed surface layer is 1 to 2 cm, and the thickness of the organic nutrient soil layer is 1 to 2 cm.

3. The method for soil remediation in mining areas according to claim 1, characterized in that: The particle size of the low carbon coal gangue is 2 to 8 mm; The mass ratio of the low-carbon coal gangue to the surface soil is 2:

1.

4. The method for soil remediation in mining areas according to claim 1 or 2, characterized in that: The thickness of the reconstruction layer is 40 to 60 cm.

5. The method for remediating mining area soil according to claim 1, characterized in that: The mass ratio of fly ash to cement is (1.2-1.8):

1.

6. The method for remediating mining area soil according to claim 6, characterized in that: The mass ratio of fly ash to cement is 1.5:

1.

7. The method for remediating mining area soil according to claim 1, 5 or 6, characterized in that: The thickness of the barrier layer is 15 to 35 cm.

8. The method for remediating mining area soil according to claim 7, characterized in that: The thickness of the barrier layer is 20 cm.

9. The method for remediating mining area soil according to claim 1, characterized in that: The thickness of the filling layer is 20 to 40 cm.

10. The method for remediating mining area soil according to claim 1, characterized in that: The thickness of the filling layer is 20 cm.

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