Method for improving land through cooperation of coal-based solid waste and agricultural waste

Abstract

The invention provides a method for improving land through cooperation of coal-based solid waste and agricultural waste, and belongs to the technical field of solid waste reutilization. According to the method, coal gangue and other solid waste are used as main raw materials, different application modes are provided for mine area land restoration and desertification land improvement, the scientific, reasonable, economical and safe ecological restoration mode is adopted, the requirements for mine area land desertification and ecological restoration of a mine area are met, and the method is suitable for popularization and application. And a feasible solution is provided for regions taking coal-based industry and animal husbandry as the pillar industry, and the ecological restoration effects of treating waste with waste and turning waste into wealth are achieved. Results of the embodiment show that when the method provided by the invention is used for land improvement, the volume weight and the field moisture capacity of the soil can be effectively improved, nutritional ingredients in the soil are greatly improved, and the improved soil meets the standard of Soil Environment Quality Agricultural Land Soil Pollution Risk Management and Control Standard (Trial) (GB15618-2018).

Description

Technical Field

[0001] The present invention relates to the technical field of solid waste recycling, and in particular to a method for land improvement using coal-based solid waste in conjunction with agricultural waste. Background Art

[0002] As an important traditional energy source, coal is consumed in high quantities annually, resulting in a significant amount of coal-based solid waste. Gangue, the primary solid waste generated during coal mining and washing, occupies a large area in storage, carries a high risk of heavy metal leaching, and can spontaneously combust during weathering and oxidation, causing environmental pollution and progressive desertification. This poses a significant challenge to the sustainable use of surrounding land resources. Furthermore, the development of agricultural production and animal husbandry also generates a significant amount of organic waste, such as straw and livestock manure. The accumulation and improper handling of these organic wastes not only pollutes land resources but also contributes to greenhouse gas emissions.

[0003] Furthermore, desertification land reclamation and ecological restoration in mining areas require a focus on improving soil structure and increasing nutrients, requiring the use of soil with good water retention and fertility. Ecological restoration in coal mining areas, on the other hand, requires ensuring that the soil has a certain organic matter content and biological activity to promote plant growth and ecosystem recovery. However, traditional topsoil mulching methods pose challenges in mining area ecological restoration, including large engineering workloads, the potential for secondary damage to the land extraction area, and violations of restrictive regulations such as the "Regulations for the Implementation of the Land Administration Law of the People's Republic of China." These issues have led to slow progress in desertification land reclamation and ecological restoration in mining areas.

[0004] Gangue is similar to natural soil and contains a relatively high proportion of organic matter, making it a natural organic mineral resource. Consequently, extensive research has been conducted in China on its soil-based utilization. Directly covering and modifying the soil with gangue achieves high utilization and ease of use, but its particles are large, its porosity is low, and its water retention is poor. Chemical activation or microbial methods for producing gangue compound fertilizers and porous ecological restoration materials using gangue offer advantages such as high nutrient utilization, excellent water and fertilizer retention, and environmental friendliness. However, these methods are complex and costly.

[0005] Patent No. CN110999753A discloses a gangue-based artificial ecological matrix and its preparation method. Gangue and plant-derived organic matter are used as raw materials, and microbial agents are added for composting to produce an environmentally safe, nutrient-rich, and plant-friendly ecological matrix. However, this method utilizes a low percentage of gangue and presents environmental issues such as odor and gas emissions. Patent No. CN118020599A discloses a gangue-based artificial soil and its preparation method and application. After crushing and screening the gangue, it is mixed and cultured with microbial strains and a solvent to produce activated gangue. This is then mixed and cultured with activated fly ash to produce the gangue-based artificial soil. Patent number CN117281010A discloses a method for preparing artificial soil primarily using coal gangue. The method involves screening the coal gangue and diatomaceous earth, crushing and mixing them, then heating them at 450-550°C for dehydration. The mixture is then sprayed with water for rapid cooling to maintain moisture. The mixture is then stored for 15-30 days for natural maturation. Most of these methods simply add coal gangue to the soil as a soil conditioner, failing to achieve soil reconstitution. They are associated with high costs, complex operations, complicated production processes, and environmental concerns.

[0006] Therefore, how to achieve the coordinated resource utilization of coal-based solid waste and agricultural and forestry waste is of great significance to improving the ecological environment, enhancing soil quality and promoting the circular economy. Summary of the Invention

[0007] The purpose of the present invention is to provide a method for land improvement by combining coal-based solid waste with agricultural waste. The method provided by the present invention uses solid waste such as coal gangue as the main raw materials for land improvement, adopts different improvement methods for different land conditions, and provides different improvement methods, which can significantly improve the quality of the land and can be used for land restoration.

[0008] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0009] The present invention provides a method for land improvement using coal-based solid waste in conjunction with agricultural waste, comprising:

[0010] When the land improvement is mining land restoration, the land improvement method comprises: mixing coal gangue, construction waste and organic fertilizer to obtain activated artificial soil, and then using the activated artificial soil for mining land restoration;

[0011] When the land improvement is desertified land improvement, the land improvement method includes: mixing a desertified soil improver with desertified soil to obtain improved soil, and then performing desertified land improvement on the improved soil; the desertified soil improver includes coal gangue and porous materials.

[0012] Preferably, based on 100% by mass of the activated artificial soil, the activated artificial soil comprises 30-80% coal gangue, 15-20% construction waste and ≤10% organic fertilizer.

[0013] Preferably, when the land improvement is mining land restoration, the coal gangue includes small-particle coal gangue of 0.5-1 mm, medium-particle coal gangue of 1-2 mm and large-particle coal gangue of >2 mm.

[0014] Preferably, based on the mass of the gangue being 100%, the proportion of the small-particle gangue is 40-80%; the proportion of the medium-particle gangue is ≤30%; and the proportion of the large-particle gangue is ≤30%.

[0015] Preferably, the construction waste is solid waste-based porous bricks; the particle size of the solid waste-based porous bricks is 1 to 3 mm.

[0016] Preferably, the activated artificial soil further comprises a mycorrhizal fungal agent.

[0017] Preferably, the content of coal gangue in the desertified soil conditioner is 60-85 wt.%, and the content of porous material is 15-40 wt.%.

[0018] Preferably, the particle size of the coal gangue is less than 0.5 mm.

[0019] Preferably, the porous material includes at least one of biochar, a water retaining agent and solid waste-based porous bricks.

[0020] Preferably, the mass ratio of the desertified soil conditioner to the desertified soil is 4:6 to 1:9.

[0021] The present invention provides a method for land improvement by combining coal-based solid waste with agricultural waste, comprising: when the land improvement is for land restoration in a mining area, the land improvement method comprises: mixing coal gangue, construction waste and organic fertilizer to obtain activated artificial soil, and then using the activated artificial soil for land restoration in the mining area; when the land improvement is for desertified land improvement, the land improvement method comprises: mixing a sandy soil improver with the sandy soil to obtain improved soil, and then using the improved soil for desertified land improvement; the sandy soil improver comprises coal gangue and porous materials. The method provided by the present invention uses solid waste such as coal gangue as the main raw materials, and provides different application methods for land restoration in mining areas and improvement of desertified land. Through a scientific, reasonable, economical and safe ecological restoration method, it is suitable for solving the desertification of mining land and the ecological restoration needs of mining areas, and provides a practical solution for areas with coal-based industries and animal husbandry as pillar industries, achieving the ecological restoration effect of treating waste with waste and turning waste into treasure; the organic matter content of coal gangue is maintained between 15% and 25%, and it is rich in trace elements, which is conducive to plant growth; the addition of biochar improves the soil pore structure and enhances the soil's water retention capacity. At the same time, it also contains nutrients and fixes heavy metals in the soil; water retaining agents can enhance the soil's water retention capacity; the addition of solid waste-based porous bricks is conducive to the adsorption of bacteria and other microorganisms, thereby decomposing the organic components in the mixture and improving the soil fertility; construction waste or porous materials are conducive to the adsorption of bacteria and other microorganisms, thereby decomposing the organic components in the mixture and improving the soil fertility. The results of the examples show that the method provided by the present invention, when used for land improvement, can effectively increase the bulk density and field water holding capacity of the primary artificial soil and reduce the air-water ratio, thereby facilitating better moisture retention in the artificial soil. The nutrient content in the soil was significantly increased 3, 6, and 12 months after planting vegetation. At the same time, the improved soil met the "Soil Environmental Quality Agricultural Land Soil Pollution Risk Control Standard (Trial)" (GB15618-2018) standard. DETAILED DESCRIPTION

[0022] The present invention provides a method for land improvement using coal-based solid waste in conjunction with agricultural waste, comprising:

[0023] When the land improvement is mining land restoration, the land improvement method comprises: mixing coal gangue, construction waste and organic fertilizer to obtain activated artificial soil, and then using the activated artificial soil for mining land restoration;

[0024] When the land improvement is desertified land improvement, the land improvement method includes: mixing a desertified soil improver with desertified soil to obtain improved soil, and then performing desertified land improvement on the improved soil; the desertified soil improver includes coal gangue and porous materials.

[0025] In the present invention, when the land improvement is mining land restoration, the land improvement method includes: mixing coal gangue, construction waste and organic fertilizer to obtain activated artificial soil, and then using the activated artificial soil for mining land restoration.

[0026] In the present invention, based on the mass percentage of the activated artificial soil being 100%, the activated artificial soil preferably comprises 30-80% coal gangue, 15-20% construction waste and ≤10% organic fertilizer.

[0027] In the present invention, based on 100% by mass of the activated artificial soil, the activated artificial soil preferably comprises 30-80% coal gangue. In one embodiment of the present invention, the coal gangue may comprise 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, or 80% by mass. By using coal gangue as the raw material, the present invention not only consumes a large amount of coal gangue, reducing costs, but also, coal gangue is rich in mineral elements such as silicon, aluminum, and calcium, which, when mixed with organic fertilizers, can improve adsorption and nutrient slow-release capacity.

[0028] In the present invention, the gangue includes small-particle gangue of 0.5 to 1 mm, medium-particle gangue of 1 to 2 mm, and large-particle gangue of >2 mm. In the present invention, based on the mass of the gangue as 100%, the proportion of the small-particle gangue is preferably 40 to 80%; the proportion of the medium-particle gangue is preferably ≤30%; and the proportion of the large-particle gangue is preferably ≤30%. As an embodiment of the present invention, the proportion of the small-particle gangue can be 40%, 45%, 50%, 55%, 60%, 65%, 70wt.%, 75% or 80%; the proportion of the medium-particle gangue can be 5%, 10%, 15%, 20%, 25% or 30%; and the proportion of the large-particle gangue can be 5%, 10%, 15%, 20wt.%, 25% or 30%. In the present invention, the organic matter content of the coal gangue is maintained between 15% and 25%, and the gangue is rich in trace elements, which is beneficial to plant growth.

[0029] In the present invention, based on 100% by mass of the activated artificial soil, the activated artificial soil preferably comprises 15-20% construction waste. In the present invention, the construction waste is preferably solid waste-based porous bricks; the particle size of the solid waste-based porous bricks is preferably 1-3 mm. In one embodiment of the present invention, the mass percentage of the construction waste can be 15%, 16%, 17%, 18%, 19%, or 20%; and the particle size of the solid waste-based porous bricks can be 1 mm, 1.5 mm, 2 mm, 2.5 mm, or 3 mm. The addition of solid waste-based porous bricks in the present invention facilitates the adsorption of microorganisms such as bacteria, thereby decomposing the organic components in the mixture and improving soil fertility.

[0030] In the present invention, based on the mass percentage of the activated artificial soil being 100%, the activated artificial soil preferably includes ≤10% organic fertilizer, more preferably 1-10%. As one embodiment of the present invention, the mass percentage of the organic fertilizer can be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, or 10%. By adding organic fertilizer, the present invention effectively improves soil properties, increases soil microbial diversity, enhances soil enzyme activity, and reduces salinization.

[0031] In the present invention, the organic fertilizer is preferably an organic fertilizer modified by combining coal-based solid waste with agricultural waste.

[0032] In the present invention, the method for preparing the organic fertilizer modified by coal-based solid waste and agricultural waste preferably comprises the following steps:

[0033] (1) Coarse-grained coal gangue, long straw and fly ash are mixed to obtain a livestock house filler; the particle size of the coarse-grained coal gangue is 2 to 10 mm; the length of the long straw is ≤ 5 cm;

[0034] (2) Mixing fine-grained coal gangue, short straw, and filler to obtain topsoil for a livestock shed; the particle size of the fine-grained coal gangue is less than 2 mm; the length of the short straw is ≤ 1 cm;

[0035] (3) laying the barn filler obtained in step (1) to obtain a barn filler layer, and then using the barn topsoil obtained in step (2) to lay a barn topsoil layer on the upper surface of the barn filler layer to obtain an underground pit barn structure;

[0036] (4) carrying out livestock breeding in the underground pit-type livestock house structure obtained in step (3), cleaning and storing feces during the livestock breeding process, and composting the topsoil layer of the livestock house, the filler layer of the livestock house, and the stored feces after the livestock breeding is completed to obtain coal-based solid waste and agricultural waste modified organic fertilizer;

[0037] The preparation of step (1) and step (2) is not in any particular order.

[0038] In the present invention, coarse-grained coal gangue, long straw and fly ash are preferably mixed to obtain the livestock house filler.

[0039] In the present invention, the particle size of the coarse-grained gangue is preferably 2 to 10 mm. In the present invention, the coarse-grained gangue is preferably prepared by crushing and screening gangue. The present invention does not specifically limit the specific operations of the crushing and screening, as long as the particle size of the coarse-grained gangue meets the requirements. As one embodiment of the present invention, the particle size of the coarse-grained gangue can be 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, or 10 mm.

[0040] In the present invention, the length of the long straw is preferably ≤5 cm. In the present invention, the long straw is preferably obtained by cutting straw. The present invention does not particularly limit the specific cutting operation, as long as the length of the long straw meets the requirements. As an embodiment of the present invention, the length of the long straw can be 1.5 to 5 cm, and can also be 2 cm, 2.5 cm, 3 cm, 3.5 cm, 4 cm, or 4.5 cm.

[0041] The present invention does not specifically limit the specific sources of the gangue, straw, and fly ash; gangue, straw, and fly ash well known to those skilled in the art may be used. The present invention uses gangue, straw, and fly ash as raw materials, all of which are solid wastes. This not only allows for the large-scale consumption of solid waste, thus preventing environmental pollution, but also allows for high-value resource utilization and reduced production costs.

[0042] In the present invention, the livestock bedding filler preferably comprises, by mass percentage, 60-70% coarse-grained coal gangue, 15-20% long straw, and 10-30% fly ash. As one embodiment of the present invention, the mass percentage of the coarse-grained coal gangue in the livestock bedding filler can be 60%, 62%, 65%, 68%, or 70%; the mass percentage of the long straw in the livestock bedding filler can be 15%, 16%, 17%, 18%, 19%, or 20%; and the mass percentage of the fly ash in the livestock bedding filler can be 10%, 12%, 15%, 18%, 20%, 22%, 25%, 28%, or 30%. By controlling the relationship between the three components, the present invention can form a livestock bedding filler with a porosity of 15-20% after mixing. In the present invention, coal gangue and fly ash are used as the main skeleton materials. Due to their high mechanical strength and stable physical and chemical properties, they can provide a solid support structure, ensuring that the livestock house filler layer remains stable during long-term use, preventing structural damage due to self-weight settlement or external force, and avoiding pore collapse of the livestock house filler layer, thereby maintaining a good infiltration environment and air permeability; long straw enhances the infiltration capacity of the livestock house filler, and its fiber structure not only helps the uniform penetration of urine and feces, and prevents uneven decomposition caused by local accumulation, but also optimizes moisture management. By adjusting the pore moisture content, it avoids excessive drying of the system that affects microbial activity, or anaerobic corruption caused by excessive moisture, thereby ensuring a stable aerobic fermentation environment. The livestock house filler provided by the present invention has good cation exchange performance, wherein the surface of coal gangue and fly ash can effectively adsorb ammonium nitrogen in urine, reduce the release of ammonia and other volatile organic compounds, reduce the risk of environmental pollution, and at the same time improve the retention and recycling efficiency of nitrogen, so that it can be further fixed by microorganisms or converted into an effective nitrogen source that can be absorbed and utilized by plants; at the same time, by adjusting the air permeability, moisture content and carbon-nitrogen ratio of the livestock house filler, the metabolic activity of the microbial community can be optimized, so that organic matter can be decomposed at a preset rate, avoiding the overheating effect caused by too rapid degradation or the stench and anaerobic corruption caused by incomplete degradation.

[0043] The present invention has no particular limitation on the specific manner of mixing the coarse-grained coal gangue, long straw and fly ash, as long as they can be mixed evenly.

[0044] In the present invention, fine-grained coal gangue, short straw and filler are preferably mixed to obtain the topsoil for the livestock shed.

[0045] In the present invention, the particle size of the fine-grained gangue is preferably less than 2 mm. In the present invention, the fine-grained gangue is preferably prepared by crushing and screening gangue. The present invention does not specifically limit the specific operations of the crushing and screening, as long as the particle size of the fine-grained gangue meets the requirements. As an embodiment of the present invention, the particle size of the fine-grained gangue can be 0.1 to 1.8 mm, and can also be 0.2 mm, 0.3 mm, 0.5 mm, 0.8 mm, 1 mm, 1.2 mm, or 1.5 mm.

[0046] In the present invention, the length of the short straw is preferably ≤1 cm. In the present invention, the short straw is preferably obtained by cutting straw. The present invention does not particularly limit the specific cutting operation, as long as the length of the short straw meets the requirements. As an embodiment of the present invention, the length of the short straw can be 0.1 to 1 cm, and can also be 0.2 cm, 0.3 cm, 0.5 cm, 0.6 cm, or 0.8 cm.

[0047] In the present invention, the filler preferably comprises slag and / or loess. In the present invention, the particle size of the slag is preferably ≤1 cm.

[0048] In the present invention, the topsoil of the barn preferably comprises 60-70% fine-grained gangue, 15-20% short straw, and 15-20% filler, calculated by mass percentage. As one embodiment of the present invention, the mass percentage of the fine-grained gangue in the barn topsoil can be 60%, 62%, 65%, 68%, or 70%; the mass percentage of the short straw in the barn topsoil can be 15%, 16%, 17%, 18%, 19%, or 20%; and the mass percentage of the filler in the barn topsoil can be 15%, 16%, 17%, 18%, 19%, or 20%. In the present invention, the poultry and livestock move above the barn topsoil layer, and the urine produced will naturally seep through the barn topsoil layer to the barn filler layer for storage, while undergoing preliminary fermentation; the feces will accumulate in the barn topsoil layer. When the feces accumulate to a certain level, they will be cleaned by a scraper and temporarily stored for further composting treatment.

[0049] After obtaining the barn filler and barn topsoil, the present invention preferably lays the barn filler to obtain a barn filler layer, and then uses the barn topsoil to lay a barn topsoil layer on the upper surface of the barn filler layer to obtain an underground pit barn structure.

[0050] The present invention has no particular limitation on the specific method of laying the livestock house filler. A laying method well known to those skilled in the art can be used as long as the thickness of the livestock house filler layer meets the requirements.

[0051] In the present invention, the livestock house filler is preferably laid on an anti-seepage layer. In the present invention, the thickness of the anti-seepage layer is preferably 0.3 to 0.5 m.

[0052] In the present invention, the raw materials for preparing the anti-seepage layer preferably include fly ash, carbide slag, desulfurized gypsum and water. By using the above components as raw materials, the present invention can make the anti-seepage layer have a good anti-seepage effect, preventing urine and other substances from seeping into the ground and contaminating groundwater during the breeding process.

[0053] In the present invention, the raw materials for preparing the anti-seepage layer preferably include, by weight, 60-70 parts fly ash, 20-30 parts carbide slag, 10-20 parts desulfurized gypsum, and water. By controlling the amounts of fly ash, carbide slag, and desulfurized gypsum used, the anti-seepage performance of the anti-seepage layer can be further improved.

[0054] In the present invention, the amount of water used is preferably such that the solid-liquid ratio is 0.50 to 0.70. By controlling the amount of water used, the present invention can make the raw materials have good fluidity after mixing, thereby facilitating the subsequent coating into an impermeable layer.

[0055] In the present invention, the method for preparing the anti-seepage layer preferably includes: mixing fly ash, carbide slag, desulfurization gypsum, and water, and then applying the mixture to the bottom and surrounding areas of the underground pit to form the anti-seepage layer. The present invention is not particularly limited to the specific method of mixing, as long as the fly ash, carbide slag, desulfurization gypsum, and water are uniformly mixed.

[0056] In the present invention, the thickness of the livestock house filler layer is preferably 1.5 to 2 m. In the present invention, the livestock house filler layer has a porous structure and plays multiple roles in the livestock breeding process, such as storing urine, promoting fermentation, supporting filler, regulating percolation, cation exchange and controlled decomposition.

[0057] In the present invention, the livestock shed packing layer preferably also includes an exhaust pipe and a microbial agent delivery pipe. The present invention does not specifically limit the arrangement of the exhaust pipe and microbial agent delivery pipe, and can be determined based on the technical knowledge of those skilled in the art. In the present invention, the exhaust pipe is preferably an inside-out exhaust pipe; the microbial agent delivery pipe is preferably an outside-in microbial agent delivery pipe. The exhaust pipe facilitates the collection and discharge of fermentation gases; the microbial agent delivery pipe is used to regulate the fermentation process and deliver microbial agents, thereby improving the fermentation efficiency within the livestock shed packing layer.

[0058] The present invention has no special limitation on the specific operation of laying the livestock house topsoil, as long as it can ensure that the structure of the livestock house filler layer is not affected and the thickness of the livestock house topsoil layer meets the requirements.

[0059] In the present invention, the thickness of the topsoil layer of the livestock shed is preferably 0.3 to 0.5 m. The present invention facilitates livestock breeding by controlling the thickness of the topsoil layer of the livestock shed.

[0060] After obtaining the underground pit-type livestock house structure, the present invention preferably carries out livestock breeding in the underground pit-type livestock house structure, cleans and stores the feces during the livestock breeding process, and composts the topsoil layer of the livestock house, the filler layer of the livestock house and the stored feces after the livestock breeding is completed to obtain coal-based solid waste and agricultural waste modified organic fertilizer.

[0061] The present invention does not specifically limit the types of livestock in the livestock farming, and the livestock to be farmed can be determined according to the technical common sense of those skilled in the art. As an embodiment of the present invention, the livestock in the livestock farming can be pigs, cattle, sheep, chickens, ducks or geese.

[0062] In the present invention, the livestock breeding period is preferably from September of each year to April of the following year. By breeding livestock during this period, the present invention can not only prevent livestock from dying due to low outdoor temperatures, but also generate heat through fermentation of urine and other substances stored in the filler layer of the livestock shed during breeding, thereby reducing the energy consumption required to keep the livestock warm.

[0063] In the present invention, the cleaning method is preferably scraper cleaning. The present invention has no special limitation on the cleaning time interval, which can be determined according to the technical common sense of those skilled in the art to avoid the negative impact of feces accumulation on poultry and livestock.

[0064] The present invention has no special limitation on the storage method, and the storage can be performed according to the technical common sense of those skilled in the art.

[0065] The present invention preferably digs out the topsoil layer and filler layer of the barn before composting, and then mixes them with the stored feces for composting. The present invention has no particular limitation on the specific operation of digging out, and it can be transferred to the composting site and mixed with the feces.

[0066] In the present invention, the moisture content of the raw materials during composting is preferably 45-65%; the composting time is preferably 20-30 days; the composting temperature is preferably 50-65°C; the composting temperature is preferably ≥55°C for ≥5 days; the composting frequency is preferably: turning once a day when the composting time is ≤12 days, turning once every 2-3 days for the remaining composting time, and turning 2-4 times every 2 days when the composting temperature is ≥60°C. The present invention can improve the quality of organic fertilizer by controlling the composting process; and by regularly turning the compost to promote oxygen supply and uniform temperature distribution, thereby improving composting efficiency.

[0067] The present invention preferably further comprises adding bacterial liquid and additives during composting.

[0068] In the present invention, the bacterial solution is preferably a commercially available EM bacterial solution; the amount of the bacterial solution used is preferably 0.05-0.2%, more preferably 0.1%, of the total mass of the raw materials used in composting. In the present invention, the EM bacterial solution is primarily composed of more than 80 microorganisms from 10 genera, including photosynthetic bacteria, lactic acid bacteria, yeasts, and actinomycetes, thereby improving composting efficiency.

[0069] In the present invention, the additive is preferably a chemical additive and / or a physical additive; the chemical additive preferably includes at least one of magnesium hydroxide, potassium dihydrogen phosphate, and magnesium chloride; the amount of the chemical additive is preferably 0.5-2% of the total mass of the raw materials during composting, more preferably 1-1.5%; the physical additive preferably includes biochar and / or bentonite; the amount of the physical additive is preferably 2.5-10% of the total mass of the raw materials during composting, more preferably 3-8%, and even more preferably 4-6%. The present invention can further improve the efficiency of composting and the fertility of organic fertilizers by adding additives.

[0070] The present invention uses coal gangue, straw and fly ash as raw materials to prepare the livestock shed filler layer, and uses coal gangue, straw and filler as raw materials to prepare the livestock shed topsoil layer. During the breeding process, livestock and poultry will move on the livestock shed topsoil layer, and their urine will naturally penetrate through the livestock shed topsoil layer to the livestock shed filler layer for storage and preliminary fermentation. Feces will gradually accumulate on the livestock shed topsoil layer and be regularly removed and stored for future use. The livestock shed filler layer relies on the synergistic effect of porous materials such as coarse coal gangue, fly ash and straw to not only evenly absorb and store urine, It can prevent local over-wetting or over-drying, optimize the infiltration environment, promote the slow-release decomposition of manure and nitrogen fixation, reduce the emission of harmful gases such as ammonia, and improve the air quality of the farm; after the livestock and poultry breeding is completed, the filler layer and the topsoil layer of the livestock house are cleaned as a whole, and the partially decomposed organic matter and filler that has absorbed nitrogen are taken out and centralized composting is carried out. Combined with measures such as carbon-nitrogen ratio adjustment, composting and oxygenation, and bacterial agent enhancement, the degradation and composting of organic matter are further accelerated, so that it can eventually be converted into efficient and stable organic fertilizer.

[0071] In the present invention, the activated artificial soil preferably includes ≤10% biochar, more preferably 1-10%. In one embodiment of the present invention, the mass percentage of the biochar can be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, or 10%. The present invention does not specifically limit the particle size of the biochar; it can be determined based on the common knowledge of those skilled in the art. In the present invention, biochar can provide a small amount of nutrients and immobilize heavy metals in the soil.

[0072] In the present invention, the activated artificial soil preferably also includes an ambimycorrhizal fungus (AMF). In the present invention, the amount of AMF added is preferably 0.01-0.1% of the mass of the activated artificial soil. As one embodiment of the present invention, the amount of AMF added can be 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, or 0.1% of the mass of the activated artificial soil. The addition of AMF in the present invention can form a mutually beneficial symbiotic relationship with plant roots, improve the soil rhizosphere microenvironment, reduce the use of chemical fertilizers, and solidify heavy metals through mycelial secretions.

[0073] In the present invention, the activated artificial soil is preferably used for land remediation in mining areas by transferring the activated artificial soil to a pit in the mining area or directly covering it with soil, followed by planting vegetation. In the present invention, the covering material used is preferably soil from the mining area. The thickness of the covering is not particularly limited and can be determined based on the technical knowledge of those skilled in the art.

[0074] The present invention has no particular limitation on the specific type of the vegetation, and any vegetation readily grown and well known to those skilled in the art can be used. As one embodiment of the present invention, the vegetation can be forage grass suitable for local climate and soil conditions.

[0075] The present invention uses the above-mentioned method to repair the mining area land. After about 0.5 to 3 years, the soil can become activated nutrient soil, which is self-sustaining and can be used to grow other plants or crops. It can also be used as nutrient soil for direct covering in other places.

[0076] In the present invention, when the land improvement is desertified land improvement, the land improvement method includes: mixing a desertified soil improver with desertified soil to obtain improved soil, and then performing desertified land improvement on the improved soil; the desertified soil improver includes coal gangue and porous materials.

[0077] In the present invention, the content of coal gangue in the desertified soil conditioner is preferably 60-85 wt.%, and the content of porous material in the desertified soil conditioner is preferably 15-40 wt.%. As one embodiment of the present invention, the content of coal gangue in the desertified soil conditioner may be 60 wt.%, 65 wt.%, 70 wt.%, 75 wt.%, 80 wt.%, or 85 wt.%, and the content of porous material in the desertified soil conditioner may be 15 wt.%, 20 wt.%, 25 wt.%, 30 wt.%, 35 wt.%, or 40 wt.%.

[0078] In the present invention, the particle size of the coal gangue is preferably less than 0.5 mm. The present invention adopts the above-mentioned coal gangue, which can be mixed with porous materials more evenly.

[0079] In the present invention, the porous material preferably includes at least one of biochar, a water-retaining agent, and solid waste-based porous bricks; the water-retaining agent preferably includes at least one of a polymer water-retaining agent, a microbial water-retaining agent, a mineral water-retaining agent, and an organosilicon water-retaining agent. In the present invention, the biochar content of the desertified soil conditioner is preferably 0-10 wt.%; the water-retaining agent content of the desertified soil conditioner is preferably 0-10 wt.%; the solid waste-based porous brick content of the desertified soil conditioner is preferably 15-20 wt.%; and the particle size of the solid waste-based porous bricks is preferably 1-3 mm. As an embodiment of the present invention, the content of biochar in the desertified soil conditioner can be 1wt.%, 2wt.%, 3wt.%, 4wt.%, 5wt.%, 6wt.%, 7wt.%, 8wt.%, 9wt.% or 10wt.%; the content of water-retaining agent in the desertified soil conditioner can be 1wt.%, 2wt.%, 3wt.%, 4wt.%, 5wt.%, 6wt.%, 7wt.%, 8wt.%, 9wt.% or 10wt.%; the content of solid waste-based porous bricks in the desertified soil conditioner can be 15wt.%, 16wt.%, 17wt.%, 18wt.%, 19wt.% or 20wt.%; the particle size of the solid waste-based porous bricks can be 1mm, 1.5mm, 2mm, 2.5mm or 3mm. In the present invention, the organic matter content of coal gangue is maintained between 15% and 25%, and it is rich in trace elements, which is beneficial to plant growth; the addition of biochar improves the soil pore structure and enhances the soil's water retention capacity. At the same time, it also contains nutrients and fixes heavy metals in the soil; water-retaining agents can enhance the soil's water retention capacity; the addition of solid waste-based porous bricks is conducive to the adsorption of microorganisms such as bacteria, thereby decomposing the organic components in the mixture and improving the soil's fertility.

[0080] In the present invention, the mass ratio of the desertified soil conditioner to the desertified soil is preferably 4:6 to 1:9. As one embodiment of the present invention, the mass ratio of the desertified soil conditioner to the desertified soil can be 3:7 or 2:8. By controlling the ratio of the two, the present invention can reduce the cost of sandy soil improvement.

[0081] In the present invention, the improved soil preferably also includes organic fertilizer; the organic fertilizer is preferably coal-based solid waste synergistically modified with agricultural waste as the organic fertilizer. In the present invention, the preparation method of the organic fertilizer modified with coal-based solid waste synergistically modified with agricultural waste is preferably the same as the preparation method of the aforementioned coal-based solid waste synergistically modified with agricultural waste as the organic fertilizer, which will not be repeated here. In the present invention, the amount of the organic fertilizer is preferably 0-10% of the mass of the desertified soil conditioner, more preferably 1-8%, and further preferably 2-5%. The present invention effectively improves the soil properties, enhances the diversity of microorganisms in the soil, enhances the activity of soil enzymes, and reduces the degree of salinization by adding organic fertilizers.

[0082] The present invention preferably further comprises adding an ambiomycorrhizal fungus agent (AMF) to the improved soil. In the present invention, the amount of the AMF added is preferably 0.01 to 0.1% of the mass of the improved soil. As one embodiment of the present invention, the amount of the AMF added can be 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09% or 0.1% of the mass of the improved soil. The addition of AMF in the present invention can form a mutually beneficial symbiotic relationship with the plant root system, improve the soil root microenvironment, reduce the application of chemical fertilizers, and solidify heavy metals through the secretions of the hyphae.

[0083] The present invention provides different application methods for land restoration in mining areas and improvement of desertified land. Through scientific, reasonable, economical and safe ecological restoration methods, it is suitable for solving the desertification of mining land and the ecological restoration needs of mining areas. It provides a practical solution for areas with coal-based industries and animal husbandry as the pillar industries, and achieves the ecological restoration effect of treating waste with waste and turning waste into treasure.

[0084] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions of the present invention. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0085] The preparation method of the coal-based solid waste and agricultural waste modified organic fertilizer used in the examples and comparative examples is the following steps:

[0086] (1) Based on the mass of the livestock shed filler being 100%, 65% of coarse-grained coal gangue, 15% of long straw, and 20% of fly ash are uniformly mixed to obtain a livestock shed filler with a porosity of about 20%; the particle size of the coarse-grained coal gangue is 2 to 10 mm, and the length of the long straw is 1.5 to 5 cm;

[0087] (2) Based on the mass of the topsoil for the barn being 100%, 60% fine-grained coal gangue, 20% short straw, and 20% slag are uniformly mixed to obtain the topsoil for the barn; the particle size of the fine-grained coal gangue is less than 2 mm; the length of the short straw is ≤ 1 cm;

[0088] (3) The livestock house filler obtained in step (1) is laid on the upper surface of the anti-seepage layer to obtain a livestock house filler layer with a thickness of 2 m, and an exhaust pipe from the inside to the outside and a microbial agent delivery pipe from the outside to the inside are set in the livestock house filler layer, and then the livestock house topsoil is used to lay a livestock house topsoil layer with a thickness of 0.5 m on the upper surface of the livestock house filler layer to obtain an underground pit type livestock house structure; the preparation method of the anti-seepage layer is as follows: by weight, 65 parts of fly ash, 25 parts of calcium carbide slag and 10 parts of desulfurization gypsum are mixed, and then water is added to adjust the solid-liquid ratio to 0.65, and after stirring evenly, it is coated on the bottom and around the underground pit to form an anti-seepage layer with a thickness of 0.5 m;

[0089] (4) Shanxi beef cattle are raised in the underground pit-type livestock house structure obtained in step (3), and the raising period is from September to April of the following year. During the Shanxi beef cattle raising process, the feces are scraped and stored. After the Shanxi beef cattle raising is completed, the topsoil layer of the livestock house, the filler layer of the livestock house and the stored feces are composted, and the moisture content of the raw materials during the composting is 50-60%; the composting time is 30 days; the composting temperature is 50-65°C; the composting temperature is ≥55°C for 6 days; the composting frequency is preferably: turning the compost once a day during the first 10 days of composting, turning the compost once every two days during the remaining composting time, and turning the compost four times in two days when the compost temperature is ≥60°C, to obtain coal-based solid waste and agricultural waste modified organic fertilizer.

[0090] The obtained coal-based solid waste and agricultural waste modified organic fertilizer was analyzed and found to meet the requirements of the "Organic Fertilizer Standard" (NY / T 525-2021), effectively realizing the comprehensive utilization of solid waste.

[0091] Examples 1 to 5

[0092] Mixing coal gangue and construction waste to obtain primary artificial soil, then mixing the primary artificial soil with coal-based solid waste and agricultural waste modified organic fertilizer to obtain activated artificial soil, then transferring the activated artificial soil to a pit in the mining area, and finally planting vegetation to prepare local forage grass;

[0093] Based on the mass percentage of the activated artificial soil being 100%, the activated artificial soil is composed of 75% coal gangue, 20% solid waste-based porous bricks, and 5% coal-based solid waste-synergistic agricultural waste-modified organic fertilizer; the particle size of the solid waste-based porous bricks is 2 mm;

[0094] The gangue is composed of small-particle gangue of 0.5-1 mm, medium-particle gangue of 1-2 mm and large-particle gangue of >2 mm; the proportions of small-particle gangue, medium-particle gangue and large-particle gangue are shown in Table 1.

[0095] Comparative Example 1

[0096] Mixing coal gangue and construction waste to obtain primary artificial soil, then transferring the primary artificial soil to a pit in a mining area, and finally planting vegetation;

[0097] Taking the mass percentage of the primary artificial soil as 100%, the composition of the primary artificial soil is 80% coal gangue and 20% solid waste-based porous bricks; the particle size of the solid waste-based porous bricks is 2 mm.

[0098] Table 1 Particle size distribution of coal gangue in Examples 1 to 5 and Comparative Example 1

[0099]

[0100] The performance parameters of the primary artificial soil obtained in Examples 1 to 5 and Comparative Example 1 are shown in Table 2:

[0101] Table 2 Performance parameters of primary artificial soil obtained in Examples 1 to 5 and Comparative Example 1

[0102]

[0103] As can be seen from Table 2, the present invention can effectively improve the bulk density and field water holding capacity of the primary artificial soil and reduce the air-water ratio by selecting coal gangue of different gradations when preparing the primary artificial soil, thereby facilitating better moisture retention in the artificial soil and laying a foundation for subsequent vegetation planting.

[0104] The nutritional components of the vegetation (local forage grass) planted in the artificial soil provided in Examples 1 to 5 and Comparative Example 1 for 3 months, 6 months, and 12 months are shown in Table 3:

[0105] Table 3 Nutrient composition of vegetation grown in artificial soil of Examples 1 to 5 and Comparative Example 1 after 3, 6 and 12 months

[0106]

[0107] As can be seen from Table 3, after adding the coal-based solid waste synergistically modified agricultural waste organic fertilizer provided by the present invention to the artificial soil, the nutrient content in the soil far exceeded that of the control example 3 months, 6 months, and 12 months after vegetation planting, indicating that the coal-based solid waste synergistically modified agricultural waste organic fertilizer provided by the present invention can effectively improve soil fertility.

[0108] Example 6

[0109] Based on Example 1, adjustments were made. The activated artificial soil was composed of 77% coal gangue, 20% solid waste-based porous bricks, and 3% coal-based solid waste-synergistic agricultural waste-modified organic fertilizer, based on the mass percentage of the activated artificial soil being 100%. AMF was added to the activated artificial soil in an amount of 0.05% of the mass of the activated artificial soil. Other conditions were the same as in Example 1.

[0110] Comparative Example 2

[0111] Mixing farmland soil and coal-based solid waste with agricultural waste-modified organic fertilizer to obtain activated farmland soil;

[0112] Taking the mass percentage of the activated farmland soil as 100%, the activated farmland soil is composed of 95% farmland soil and 5% coal-based solid waste and agricultural waste modified organic fertilizer.

[0113] The physical and chemical properties of the activated artificial soil obtained in Examples 1 and 6 and the activated farmland soil provided in Comparative Example 2 were tested, wherein the pH value and conductivity were determined by electrode method, the available phosphorus was determined by sodium bicarbonate extraction-molybdenum antimony anti-spectrophotometry, and the alkaline hydrolyzable nitrogen was determined by alkaline hydrolysis diffusion method. The results are shown in Table 4: Table 4 Physical and chemical properties and nutrient changes of the activated artificial soil obtained in Examples 1 and 6 and the activated farmland soil provided in Comparative Example 2

[0114]

[0115] It can be seen from Table 4 that, when organic fertilizer was reduced, the addition of AMF had a significant effect on reducing the EC value of the rhizosphere in artificial soil and improving the rhizosphere nutrients.

[0116] Example 7

[0117] Coal gangue with a particle size of less than 0.5 mm and solid waste-based porous bricks with a particle size of 2 mm are mixed to obtain a desertified soil conditioner, wherein the content of the solid waste-based porous bricks in the desertified soil conditioner is 15 wt.%. Then, the desertified soil conditioner and desertified soil are mixed in a mass ratio of 4:6 to obtain a mixture. Finally, coal-based solid waste and agricultural waste-modified organic fertilizer are added in an amount of 10% of the mass of the desertified soil conditioner to improve desertified land.

[0118] Example 8

[0119] The mass ratio of the desertified soil conditioner to the desertified soil is 3:7, and other conditions are the same as those in Example 7.

[0120] Example 9

[0121] The mass ratio of the desertified soil conditioner to the desertified soil was 2:8, and other conditions were the same as those in Example 7.

[0122] Example 10

[0123] The mass ratio of the desertified soil conditioner to the desertified soil was 1:9, and other conditions were the same as those in Example 7.

[0124] Comparative Example 3

[0125] No desertified soil conditioner was added, and other conditions were the same as in Example 7.

[0126] The moisture characteristic indexes of the mixtures obtained in Examples 7 to 10 and the sandy soil in Comparative Example 3 are shown in Table 5:

[0127] Table 5 Moisture characteristic indexes of the mixtures obtained in Examples 7 to 10 and the sandy soil in Comparative Example 3

[0128] Example Saturated moisture content Field capacity Total porosity Capillary porosity Example 7 46.73％ 17.87％ 47.49％ 24.21％ Example 8 39.89％ 15.82％ 44.77％ 23.41％ Example 9 37.72％ 13.47％ 41.65％ 22.67％ Example 10 34.54％ 11.00％ 40.60％ 22.56％ Comparative Example 3 18.34％ 6.77％ 25.31％ 23.32％

[0129] The water infiltration characteristic indices of the mixtures obtained in Examples 7 to 10 and the sandy soil in Comparative Example 3 are shown in Table 6:

[0130] Table 6 Water infiltration characteristic indexes of the mixtures obtained in Examples 7 to 10 and the sandy soil in Comparative Example 3

[0131]

[0132] It can be seen from Tables 5 and 6 that with the increase of coal gangue content, the saturated moisture content, field water holding capacity and total porosity of the mixture gradually increase, the water infiltration rate decreases, the cumulative infiltration volume decreases, and the water retention capacity increases.

[0133] The heavy metal risk assessment of the primary artificial soil in Example 1, the activated artificial soil in Example 4, and the mixture in Example 7 was fully digested, and the measured As, Cd, Cr, Hg, and Pb contents are shown in Table 7:

[0134] Table 7 Heavy metal contents of the primary artificial soil in Example 1, the activated artificial soil in Example 4, and the mixture in Example 7

[0135]

[0136] As can be seen from Table 7, the above soils all meet the standards of the "Soil Environmental Quality Agricultural Land Soil Pollution Risk Control Standard (Trial)" (GB15618-2018), indicating that the solution of the present invention will not lead to an increase in the heavy metal content in the soil.

[0137] The above is only 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 land improvement using coal-based solid waste and agricultural waste, comprising: When the land improvement is mining land restoration, the land improvement method comprises: mixing coal gangue, construction waste and organic fertilizer to obtain activated artificial soil, and then using the activated artificial soil for mining land restoration; When the land improvement is desertified land improvement, the land improvement method includes: mixing a desertified soil improver with desertified soil to obtain improved soil, and then performing desertified land improvement on the improved soil; the desertified soil improver includes coal gangue and porous materials.

2. The method according to claim 1, characterized in that Taking the activated artificial soil as 100% by mass, the activated artificial soil comprises 30-80% of coal gangue, 15-20% of construction waste and ≤10% of organic fertilizer.

3. The method according to claim 1, characterized in that When the land improvement is mining land restoration, the coal gangue includes small-particle coal gangue of 0.5-1 mm, medium-particle coal gangue of 1-2 mm and large-particle coal gangue of >2 mm.

4. The method according to claim 3, characterized in that Taking the mass of the coal gangue as 100%, the proportion of the small-particle coal gangue is 40-80%; the proportion of the medium-particle coal gangue is ≤30%; and the proportion of the large-particle coal gangue is ≤30%.

5. The method according to claim 1, wherein The construction waste is solid waste-based porous bricks; the particle size of the solid waste-based porous bricks is 1 to 3 mm.

6. The method according to claim 1, characterized in that The activated artificial soil also includes a mycorrhizal fungal agent.

7. The method according to claim 1, characterized in that The content of coal gangue in the desertified soil improver is 60-85 wt.%, and the content of porous material is 15-40 wt.%.

8. The method according to claim 7, characterized in that The particle size of the coal gangue is less than 0.5 mm.

9. The method according to claim 1, characterized in that The porous material includes at least one of biochar, a water retaining agent and solid waste-based porous bricks.

10. The method according to claim 1, characterized in that The mass ratio of the desertified soil improver to the desertified soil is 4:6 to 1:9.

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