A combined structure and method for ecological restoration of mine landfills

Abstract

The present invention provides a combined structure and method for ecological restoration of mine landfills. The combined structure comprises a capillary barrier water-retention layer and a vegetation concrete curing layer. The capillary barrier water-retention layer further comprises a coal gangue solid waste layer and a modified Yellow River sediment layer. The coal gangue solid waste layer comprises crushed coal gangue solid waste; the modified Yellow River sediment layer comprises, by weight, Yellow River sediment, an ecological adhesive, a water-retaining agent, biochar, calcium-based bentonite, and water; and the vegetation concrete curing layer comprises, by weight, Yellow River sediment, cement, an ecological modification agent, organic materials, compound fertilizer, native grass seeds, and water. This combined structure can effectively achieve the effects of preventing water infiltration and retaining moisture in the base layer, while also enhancing surface curing and preventing wind and sand during mine ecological restoration.

Description

Technical Field

[0001] The present invention relates to the fields of high-value disposal and utilization of coal gangue solid waste, Yellow River dredging sludge, and mine landfill ecological restoration, and in particular to a combined structure and method for mine landfill ecological restoration. Background Art

[0002] The Yellow River basin covers an area of ​​approximately 752,400 square kilometers and is the river with the largest sand content in the world. In 2021, except for the Bayangaoler Station, typical sections of the upper reaches of the Yellow River in Inner Mongolia showed erosion, while the rest showed siltation. Sedimentation and the unbalanced relationship between water and sand are key factors restricting the current sustainable ecological development of the Yellow River basin. As my country's "energy basin", the Yellow River basin has a series of solid waste piles such as spoil dumps and waste rock mountains brought about by long-term and large-scale coal mining. The open-air stacking occupies a large amount of land, resulting in frequent extreme weather such as dust and sandstorms, and seriously threatening the ecological environment safety around the mining area. Therefore, it is urgent to adopt scientific and efficient disposal measures to coordinate the utilization of Yellow River sediments and the ecological restoration of solid waste landfills, and resolutely win the battle to protect the mountains, rivers, forests, fields, lakes, grasslands and sands.

[0003] Chinese patent CN 105248007A discloses a method for ecological reclamation of coal mining subsidence land using Yellow River sediment. By alternating multiple fillings to reconstruct the soil, the water and fertilizer retention of the reconstructed soil profile can be effectively improved, accelerating the maturation of the sediment layer, and further promoting the growth and development of crops. Chinese patent CN115947573A discloses a composite material for the safe reinforcement and ecological restoration of mine landfills using Yellow River sediment. This composite material can effectively complete the safe reinforcement and ecological restoration of mine landfills, thereby realizing a coordinated management model for the ecological environment of mining areas in the Yellow River basin and Yellow River sediment. Chinese patent CN115949080A provides a mine landfill ecological restoration system based on modified Yellow River sediment. This system can effectively improve the water retention capacity of the structural layer, which is beneficial to the sustainable development of subsequent mine landfills.

[0004] Due to long-term water erosion and other reasons, the Yellow River dredging sediment itself has poor particle grading, low nutrient content, and poor water-holding and fertilizer-retaining performance. It cannot meet the normal growth and development needs of plants and is not suitable for direct application in ecological restoration projects. It is urgently needed to be combined with coal gangue solid waste into a blocking structure and add ecological adhesives, water-retaining agents, biochar, bentonite and other external admixtures to improve its water-holding and fertilizer-retaining performance. The Yellow River basin is located in the windy, dry, arid and water-scarce northern region. The ecological restoration substrate is prone to natural damage such as wind erosion, causing dust, dust storms and other weather conditions. Therefore, it is necessary to add cement, ecological modification agents, organic materials, compound fertilizers, native grass seeds and other external admixtures to improve the stability of the ecological restoration substrate while promoting the growth and development of plants. The combined structure can effectively achieve large-scale comprehensive utilization of coal gangue solid waste and Yellow River dredging sediment, creating a new model of coordinated management of solid waste utilization and mine landfill ecological restoration. Summary of the Invention

[0005] In order to solve the current technical problems, the main purpose of the present invention is to provide a combined structure and method for the ecological restoration of mine landfills. Through the combined structure, the effects of water infiltration prevention, water storage and moisture retention in the base layer, surface layer solidification enhancement, and wind and sand suppression can be effectively achieved in the process of mine ecological reclamation, thereby realizing the organic combination of large-scale comprehensive utilization of typical solid wastes such as coal gangue and Yellow River dredging mud and ecological restoration of mine landfills in the Yellow River area.

[0006] In order to achieve the above-mentioned technical features, the purpose of the present invention is achieved as follows: a combined structure for ecological restoration of mine landfills, comprising a coal gangue solid waste layer arranged on the surface of the mine landfill, the surface layer of the coal gangue solid waste layer is a modified Yellow River bottom mud layer, the coal gangue solid waste layer and the modified Yellow River bottom mud layer together constitute a capillary barrier water retention layer, the surface layer of the modified Yellow River bottom mud layer is a plant growth base layer, the surface layer of the plant growth base layer is a plant growth surface layer, and the plant growth base layer and the plant growth surface layer together constitute a vegetation concrete solidification layer.

[0007] The coal gangue solid waste layer adopts crushed coal gangue.

[0008] The particle size of the crushed coal gangue is less than 15 mm.

[0009] The modified Yellow River sediment layer comprises, by weight, 100 parts of Yellow River sediment, 0.1-0.2 parts of ecological adhesive, 0.05-0.1 parts of water retaining agent, 5-8 parts of biochar, 10-15 parts of bentonite, and 4-8 parts of water.

[0010] Calculated by weight, the plant growth base layer includes: 100 parts of Yellow River sediment, 2-3 parts of cement, 4-6 parts of ecological reformer, 2-3 parts of organic materials, and 0.1-0.2 parts of compound fertilizer.

[0011] The plant growth surface layer includes, by weight: 100 parts of Yellow River sediment, 2-3 parts of cement, 4-6 parts of ecological modification agent, 2-3 parts of organic materials, 0.1-0.2 parts of compound fertilizer, 40g-45g / m2 of native grass seeds. 2 .

[0012] The ecological adhesive comprises at least one of polyanionic cellulose, carboxymethyl cellulose and / or polyacrylamide;

[0013] The water-retaining agent is a super absorbent resin with a water absorption rate greater than 300 times;

[0014] The bentonite is calcium-based bentonite and / or sodium-based bentonite.

[0015] The cement includes silicate and / or aluminate cement.

[0016] The organic material is at least one of wheat husks, sawdust and / or chopped grass;

[0017] The ratio of nitrogen, phosphorus and potassium in the compound fertilizer is 1:1.5-1.8:0.5-1;

[0018] The native grass seeds are selected from the cold-resistant and drought-resistant native plants in the northern region according to the principle of reasonable combination of grass, shrub and vine. The sowing amount is 40g-45g / m 2 For specific seeding amount, please refer to the "Technical Specifications for Ecological Restoration of Vegetation Concrete on Steep Slopes of Hydropower Projects": NB / T 35082-2016[S].

[0019] A method for ecological restoration using a combined structure for ecological restoration of a mine landfill, comprising the following steps:

[0020] Step 1: Pre-treat the surface of the mine landfill to remove protrusions or fill obvious depressions;

[0021] Step 2: Evenly spread the crushed gangue on the landfill surface to a thickness of 10-15 cm after leveling to obtain a gangue solid waste layer;

[0022] Step 3: The naturally air-dried dredged sludge is passed through a 5mm pore sieve to remove gravel and debris;

[0023] Step 4, uniformly mixing and stirring the sieved Yellow River sediment, ecological adhesive, water retaining agent, biochar, bentonite, and water according to a set weight ratio to prepare a modified Yellow River sediment admixture;

[0024] Step 5: Evenly spread the modified Yellow River sediment admixture on the surface of the coal gangue solid waste layer to a thickness of 20-25 cm after leveling to obtain a modified Yellow River sediment layer. The coal gangue solid waste layer and the modified Yellow River sediment layer constitute a capillary barrier water retention layer;

[0025] Step 6: Evenly mix and stir the sieved Yellow River sediment, cement, ecological modification agent, organic material, and compound fertilizer according to the set weight ratio to prepare vegetation concrete admixture A;

[0026] Step 7: Take a portion of the vegetation concrete admixture A, add native grass seeds, and mix them evenly according to a set weight ratio to prepare the vegetation concrete admixture B;

[0027] Step 8: laying and fixing a hanging net on the surface of the modified Yellow River sediment layer;

[0028] Step 9: evenly spray the vegetation concrete admixture A onto the surface of the modified Yellow River sediment layer, and level it to a thickness of 5-10 cm to obtain a plant growth base;

[0029] Step 10: Evenly spray the vegetation concrete admixture B onto the surface of the plant growth base layer, and level it to a thickness of 3-5 cm to obtain a plant growth surface layer. The plant growth base layer and the plant growth surface layer constitute a vegetation concrete solidification layer.

[0030] In step 11, step 9 and step 10, the amount of water added for spraying should ensure that the water does not disperse or flow after spraying. The water quality should comply with the relevant provisions of the current national standard "Agricultural Irrigation Water Quality Standard" GB 5084, and should be filtered if necessary.

[0031] The present invention has the following beneficial effects:

[0032] 1. The present invention utilizes two typical solid wastes, coal gangue and Yellow River dredging mud, as the basic materials for the coarse-grained layer and fine-grained layer in the capillary barrier water retention layer, respectively, realizing a new form of large-scale and comprehensive utilization of solid waste, which is in line with the current trend of accelerating the secondary utilization of engineering solid waste.

[0033] 2. Under unsaturated conditions, the present invention's capillary retardation effect, due to the difference in permeability coefficients between the fine and coarse layers, causes water to preferentially migrate toward the fine-grained layer, where the capillary driving force is greater, after reaching the fine / coarse interface, ultimately preventing water from infiltrating. Furthermore, the incorporation of multiple additives, such as ecological adhesives, biochar, water-retaining agents, and bentonite, into the fine-grained layer significantly increases the saturated moisture content of the modified Yellow River sediment, thereby achieving a moisture-retaining effect. These two factors work together to effectively enhance the water-retaining capacity of the capillary retardation layer, further providing sufficient water and fertilizer for plant growth.

[0034] 3. Cement, as a cementitious material, is added to the mine landfill ecological restoration base material, improving its stability while significantly enhancing its strength. This effectively reduces damage caused by natural factors such as wind erosion, extends the service life of the ecological restoration base material, and reduces subsequent maintenance costs. Simultaneously, multiple admixtures, such as ecological modifiers, organic materials, compound fertilizers, and native grass seeds, are added to the base material to meet the base material's strength requirements while creating a suitable environment for the growth and development of various locally adapted plants, including grasses, shrubs, and vines.

[0035] 4. The present invention provides a combined structure for ecological restoration of mine landfills and a restoration method thereof, which utilizes a capillary barrier water-retaining layer composed of coal gangue and modified Yellow River bottom mud as a base layer and a vegetation concrete solidification layer as a surface layer, thereby inventing a new water-retaining and enhanced combined structure for ecological restoration of mine landfills, realizing a new model of coordinated management of large-scale and comprehensive utilization of typical solid wastes such as coal gangue and Yellow River dredged bottom mud in the Yellow River area and ecological restoration of mine landfills, thus killing two birds with one stone. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The present invention will be further described below with reference to the accompanying drawings and examples.

[0037] Figure 1 A schematic diagram of a combined structure for ecological restoration of a mine landfill provided by an embodiment of the present invention.

[0038] Figure 2 A schematic diagram of a method for ecological restoration using a combined structure for ecological restoration of a mine landfill provided by an embodiment of the present invention.

[0039] In the figure: coal gangue solid waste layer 1, modified Yellow River bottom mud layer 2, plant growth base layer 3, plant growth surface layer 4, mine landfill 5, capillary barrier water retention layer 6, vegetation concrete solidification layer 7. DETAILED DESCRIPTION

[0040] The embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0041] Example 1:

[0042] like Figure 1 As shown, an embodiment of the present invention provides a combined structure for ecological restoration of mine landfills, including a mine landfill 5, a capillary barrier water retention layer 6, and a vegetation concrete solidification layer 7; the capillary barrier water retention layer 6 covers the surface of the mine landfill 5, and the capillary barrier water retention layer 6 includes: a coal gangue solid waste layer 1 and a modified Yellow River bottom mud layer 2 arranged in sequence outward along the surface of the mine landfill 5; the vegetation concrete solidification layer 7 covers the surface of the capillary barrier water retention layer 6, and the vegetation concrete solidification layer 7 includes: a plant growth base layer 3 and a plant growth surface layer 4 arranged in sequence outward along the surface of the capillary barrier water retention layer 6.

[0043] Specifically, for the gangue solid waste layer 1 in the above-mentioned embodiment 1, this embodiment further proposes a repair method, which includes: the gangue solid waste layer 1 is prepared by secondary crushing of mining solid waste gangue; the particle size of the gangue solid waste layer 1 is between 0-15 mm; the thickness of the gangue solid waste layer 1 is 15 cm; the saturated permeability coefficient of the gangue solid waste layer 1 is 1.54×10 -2 cm / s.

[0044] Specifically, for the modified Yellow River sediment layer 2 in the above-mentioned embodiment 1, this embodiment also proposes a repair method, which includes: in parts by weight, the modified Yellow River sediment layer 2 is prepared by uniformly stirring 100 parts of Yellow River sediment, 0.1 parts of ecological adhesive, 0.05 parts of water retaining agent, 7 parts of biochar, 12 parts of bentonite, and 5 parts of water; the Yellow River sediment is naturally air-dried and then manually removed of impurities, and the particle size is between 0-5 mm; the thickness of the modified Yellow River sediment layer 2 is 25 cm; the saturated permeability coefficient of the modified Yellow River sediment layer 2 is 1.68×10 -7 cm / s.

[0045] In the technical solution of the above-mentioned embodiment 1, a plant growth base layer 3 and a plant growth surface layer 4 are sequentially arranged along the surface of the capillary barrier water retention layer 6. In parts by weight, the plant growth base layer 3 includes: 100 parts of Yellow River sediment, 2 parts of cement, 5 parts of ecological modification agent, 2 parts of organic materials, and 0.15 parts of compound fertilizer. In parts by weight, the plant growth surface layer 4 includes: 100 parts of Yellow River sediment, 2 parts of cement, 5 parts of ecological modification agent, 2 parts of organic materials, 0.15 parts of compound fertilizer, and 40g-45g / m of native grass seeds. 2 .

[0046] Specifically, for the plant growth base layer 3 in the above-mentioned embodiment 1, this embodiment also proposes a repair method, which includes: laying a machine-woven flexible wire mesh with a wire diameter of not less than 2.0 mm or a flexible plastic mesh with a maximum tensile force of not less than 6.0 kN / m and an anti-aging property of not less than 15a on the surface of the modified Yellow River sediment layer 2, and the distance between the mesh and the slope surface should be 6-8 cm. The plant growth base layer 3 is constructed in the form of spraying; when spraying the plant growth base layer 3, the spray angle of the spray gun should be controlled within 15°, and the distance between the spray gun nozzle and the modified Yellow River sediment layer 2 should be 0.8m~1.2m; the thickness of the plant growth base layer 3 is 5 cm; after 3 days of construction, the bulk density of the plant growth base layer 3 should be 0.3~1.7 g / cm 3 between.

[0047] Specifically, for the plant growth surface layer 4 in the first embodiment above, this embodiment also proposes a repair method, which includes: spraying the plant growth surface layer 4 during construction; the spray gun's spray angle should be controlled within 15° during spraying, and the distance between the spray gun nozzle and the plant growth base layer 3 should be preferably 0.8m to 1.2m; the plant growth surface layer 4 has a thickness of 3cm; the native grass seeds in the plant growth surface layer 4 should follow the principle of combining grasses, shrubs, and vines, and select native plants that are cold-resistant and drought-resistant in northern regions. After construction of the plant growth surface layer 4 is completed, it should be promptly covered with straw mats for maintenance to better stabilize the slope and prevent wind and bird feed from affecting the germination of the grass seeds.

[0048] According to the combined structure and repair method provided by the present invention, moisture sensors and matrix suction sensors were installed in sequence at 10 cm, 25 cm, and 42.5 cm inside a model tube with a radius of 12 cm and a height of 60 cm, and a one-dimensional vertical infiltration test of simulated rainfall was carried out under heavy rain conditions (10 mm / h).

[0049] Example 2:

[0050] In this embodiment, except that the vegetation concrete solidification layer 7 is the original Yellow River bottom mud layer and no cement or ecological modifier is added, the rest of the structure and repair method are exactly the same as those in Example 1. Therefore, the structure in Example 2 that is essentially the same as that in Example 1 will not be elaborated in detail. For the parts not described in detail, please refer to Example 1.

[0051] Example 3:

[0052] In this embodiment, except that all structural layers are original Yellow River bottom mud layers and capillary blocking water retention layer 6 and vegetation concrete solidification layer 7 are not provided, the rest of the structure and repair method are exactly the same as those in embodiment one. Therefore, the structure in embodiment three that is essentially the same as that in embodiment one will not be elaborated in detail. For the parts not described in detail, please refer to embodiment one.

[0053] Related test and effect data:

[0054] The various parameters of the combined structures in Examples 1 to 3 and the strength indicators of the vegetation concrete solidified layer 7 at different ages were monitored and analyzed, and the results are shown in Table 1.

[0055] Table 1 Analysis of combined structure retardation characteristics and physical and chemical indicators

[0056]

[0057] Finally, it should be noted that the above-described embodiments are only specific implementation methods of the present invention, which are used to illustrate the technical solutions of the present invention, rather than to limit them, and the protection scope of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the aforementioned embodiments, a person of ordinary skill in the art should understand that any person familiar with the technical field can still modify the technical solutions described in the aforementioned embodiments or easily conceive of changes within the technical scope disclosed by the present invention, or perform equivalent replacements on some of the technical features thereof; and these modifications, changes or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention, and should all be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

[0058] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the description and implementation methods. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A combined structure for ecological restoration of mine landfills, characterized in that: The invention comprises a coal gangue solid waste layer (1) arranged on the surface of a mine landfill (5); the surface layer of the coal gangue solid waste layer (1) is a modified Yellow River bottom mud layer (2); the coal gangue solid waste layer (1) and the modified Yellow River bottom mud layer (2) together constitute a capillary blocking water retention layer (6); the surface layer of the modified Yellow River bottom mud layer (2) is a plant growth base layer (3); the surface layer of the plant growth base layer (3) is a plant growth surface layer (4); the plant growth base layer (3) and the plant growth surface layer (4) together constitute a vegetation concrete solidification layer (7); The gangue solid waste layer (1) is made of crushed gangue; The particle size of the crushed coal gangue is less than 15 mm; The modified Yellow River sediment layer (2) specifically comprises, by weight, 100 parts of Yellow River sediment, 0.1-0.2 parts of ecological adhesive, 0.05-0.1 parts of water retaining agent, 5-8 parts of biochar, 10-15 parts of bentonite, and 4-8 parts of water.

2. The combined structure for ecological restoration of a mine landfill according to claim 1, characterized in that: In parts by weight, the plant growth base (3) comprises: 100 parts of Yellow River sediment, 2-3 parts of cement, 4-6 parts of ecological modification agent, 2-3 parts of organic materials, and 0.1-0.2 parts of compound fertilizer.

3. The combined structure for ecological restoration of a mine landfill according to claim 2, characterized in that: In parts by weight, the plant growth surface layer (4) comprises: 100 parts of Yellow River sediment, 2-3 parts of cement, 4-6 parts of ecological modification agent, 2-3 parts of organic materials, 0.1-0.2 parts of compound fertilizer, 40g-45g / m 2 .

4. The combined structure for ecological restoration of a mine landfill according to claim 1, characterized in that: The ecological adhesive comprises at least one of polyanionic cellulose, carboxymethyl cellulose and / or polyacrylamide; The water-retaining agent is a super absorbent resin with a water absorption rate greater than 300 times; The bentonite is calcium-based bentonite and / or sodium-based bentonite.

5. The combined structure for ecological restoration of a mine landfill according to claim 2, characterized in that: The cement includes silicate and / or aluminate cement.

6. The combined structure for ecological restoration of a mine landfill according to claim 3, characterized in that: The organic material is at least one of wheat husks, sawdust and / or chopped grass; The ratio of nitrogen, phosphorus and potassium in the compound fertilizer is 1:1.5-1.8:0.5-1; The native grass seeds are selected from the cold-resistant and drought-resistant native plants in the northern region according to the principle of reasonable combination of grass, shrub and vine. The sowing amount is 40g-45g / m 2 .

7. A method for ecological restoration using the combined structure for ecological restoration of a mine landfill according to any one of claims 1 to 6, characterized in that: The following steps are involved: Step 1, pre-treating the surface of the mine landfill (5) to remove protrusions or fill obvious depressions; Step 2: evenly spread the crushed gangue on the landfill surface to a thickness of 10-15 cm after leveling, thereby obtaining a gangue solid waste layer (1); Step 3: The naturally air-dried dredged sludge is passed through a 5mm pore sieve to remove gravel and debris; Step 4, uniformly mixing and stirring the sieved Yellow River sediment, ecological adhesive, water retaining agent, biochar, bentonite, and water according to a set weight ratio to prepare a modified Yellow River sediment admixture; Step 5, evenly spreading the modified Yellow River sediment admixture on the surface of the gangue solid waste layer (1), and leveling the surface to a thickness of 20-25 cm to obtain a modified Yellow River sediment layer (2), wherein the gangue solid waste layer (1) and the modified Yellow River sediment layer (2) constitute a capillary barrier water retention layer (6); Step 6: Evenly mix and stir the sieved Yellow River sediment, cement, ecological modification agent, organic material, and compound fertilizer according to the set weight ratio to prepare vegetation concrete admixture A; Step 7: Take a portion of the vegetation concrete admixture A, add native grass seeds, and mix them evenly according to a set weight ratio to prepare the vegetation concrete admixture B; Step 8, laying a hanging net on the surface of the modified Yellow River sediment layer (2) and fixing it; Step 9, spraying the vegetation concrete admixture A evenly onto the surface of the modified Yellow River sediment layer (2), and leveling it to a thickness of 5-10 cm to obtain a plant growth base layer (3); Step 10, spraying the vegetation concrete admixture B evenly onto the surface of the plant growth base layer, and leveling it to a thickness of 3-5 cm to obtain a plant growth surface layer (4). The plant growth base layer (3) and the plant growth surface layer (4) constitute a vegetation concrete solidification layer (7); In step 11, step 9 and step 10, the amount of water added for spraying should be such that the seeds do not disperse or flow after spraying.

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