Graded and quality-divided artificial soil prepared by activating low-grade coal gangue through microbial inoculum, preparation and application of graded and quality-divided artificial soil

Abstract

The invention relates to microbial agent activated low-grade coal gangue graded and quality-divided artificial soil, preparation and application. The artificial soil comprises a bottom structure supporting layer, and a nutrition activation layer is laid on the structure supporting layer; the structure supporting layer adopts large-size-fraction low-grade coal gangue; the nutrition activation layer adopts a mixture inoculated with a microbial agent, and compost fermentation is performed after inoculation; the mixture is formed by mixing small-particle-grade low-grade coal gangue and local soil in equal proportion; a raised dust covering layer is arranged on the nutrition activation layer and adopts medium-grade low-grade coal gangue; the coal gangue nutrients are activated through the complex microbial inoculants, the coal gangue is divided according to the particle size, different grades of coal gangue and different treatment modes are adopted for different grades, and on the premise that the soil function is not affected, the cost can be reduced, the coal gangue absorption amount can be increased, and conversion from solid waste to artificial soil can be completed.

Description

Technical Field

[0001] This invention relates to the field of coal gangue resource utilization technology, and in particular to a microbial agent-activated, graded and classified artificial soil for low-grade coal gangue, its preparation and application. Background Technology

[0002] Coal gangue, a solid waste generated during coal mining, extraction, and washing, not only occupies land resources but also causes environmental problems such as soil pollution, soil degradation, geological disasters, and air pollution, threatening the surrounding ecological environment and the safety of people's lives and property. Although the comprehensive utilization of coal gangue has been increasing in recent years, there is still a gap between its emissions and the amount that can be disposed of. Low-grade coal gangue refers to coal gangue with low calorific value (less than 2800 kJ / kg) and high ash content. This type of coal gangue does not have the potential for combustion power generation, limiting its application and becoming a bottleneck in the development of comprehensive utilization technology for coal gangue. Stockpiling or simple backfilling of coal gangue no longer meets the current needs of sustainable development, and existing resource utilization technologies are difficult to apply on a large scale. Improving the resource utilization rate of coal gangue and developing large-scale utilization methods have become one of the most urgent tasks at present.

[0003] Coal gangue cannot decompose quickly under natural conditions, so the key to turning coal gangue into soil lies in accelerating its weathering. Currently, some studies have reported the use of microbial agents ([1] Sheng Dinghong, Zhang Jingning, Li Xiaojun, et al. Preparation and application of coal gangue fertilizer[J]. Applied Chemical Industry, 2023, 52(03):960-963+967.DOI:10.16581 / j.cnki.issn1671-3206.20230213.019; [2] Gong Wenhui, Zhu Xiaobo, Li Wang, et al. Analysis of phosphorus solubilization effect of native bacteria in coal gangue and optimization of acid production performance[J]. Coal Science and Technology, 2023, 51(S1):449-460.DOI:10.13199 / j.cnki.cst.2022-1101.) to promote the decomposition and activation of coal gangue, but most of them only use a single strain of bacteria, which cannot achieve a targeted and sufficient activation effect of nutrients. Secondly, the application of artificial soil is mainly based on in-situ tillage with the surface topsoil ([3] A method for preparing artificial soil using coal gangue: 202311845357.5[P]. 2024-02-20.), the amount of coal gangue consumed is limited, and there is no literature on building coal gangue-based artificial soil in different grades and of different qualities. Summary of the Invention

[0004] To overcome the shortcomings of the prior art, the present invention aims to provide a method for activating, preparing, and applying graded artificial soil from low-grade coal gangue using a microbial agent. By activating the nutrients in the coal gangue with a compound microbial agent and classifying the coal gangue according to its particle size, different particle sizes and different treatment methods are used for different grades. This method can reduce costs and increase the amount of coal gangue that can be disposed of without affecting the soil function, thus completing the transformation from solid waste to artificial soil.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows: A microbial agent for activating graded and classified artificial soil of low-grade coal gangue includes a bottom structural support layer and a nutrient activation layer laid on top of the structural support layer. The structural support layer uses large-particle, low-grade coal gangue with a particle size range of 4~10mm and a filling thickness of 25~40cm. The nutrient activation layer uses a mixture inoculated with microbial agents. The inoculation amount, i.e., the mass ratio of microbial agents to the mixture, is less than or equal to 2%. After inoculation, composting fermentation is maintained for 30 to 35 days. The mixture is a mixture of small-particle, low-grade coal gangue and local soil in equal proportions. The particle size range of the small-particle, low-grade coal gangue is less than or equal to 1 mm. The filling thickness of the nutrient activation layer is 10 to 25 cm.

[0006] The nutrient activation layer is covered with a dust covering layer, which is made of medium-sized, low-grade coal gangue with a particle size range of 1-4 mm and a covering thickness of 1-2 cm.

[0007] The method for preparing graded and classified artificial soil activated by microbial agents includes the following steps: 1) Mix small-sized, low-grade coal gangue with local soil in equal proportions, with a particle size range of less than or equal to 1 mm, as a mixture. 2) Add microbial inoculants to treat the above mixture. The inoculation amount, i.e., the mass ratio of microbial inoculants to the mixture, should be less than or equal to 2%. After mixing, cover the surface with a layer of plastic film and compost at an ambient temperature of 30-35℃. Turn the pile over every 3-5 days and then cover it with plastic film again. After composting for 30-35 days, it can be used as a nutrient activation layer for artificial soil. 3) Lay a structural support layer, filling the bottom with crushed large-sized low-grade coal gangue, with a particle size range of 4~10mm and a filling thickness of 25~40cm; 4) Lay the nutrient activation layer prepared in step 2) on the structural support layer, with a filling thickness of 10~25cm.

[0008] A method for activating low-grade coal gangue graded and classified artificial soil with microbial agents includes the following steps: 1) After watering the nutrient activation layer and structural support layer thoroughly, evenly scatter the plant seeds on the surface of the nutrient activation layer. 2) Cover the nutrient activation layer with a dust covering layer. The dust covering layer uses medium-sized, low-grade coal gangue with a particle size range of 1~4mm and a covering thickness of 1~2cm. 3) Water regularly and appropriately to keep the plants fresh.

[0009] The low-grade coal gangue comes from low-calorific-value coal gangue in the mining area, with a calorific value of less than 2800 kJ / kg.

[0010] The local soil was collected, impurities were removed, it was air-dried and sieved, and the particle size was less than 4 mm.

[0011] The microbial agent is derived from coal gangue. A series of nutrient-activating bacteria with phosphorus-solubilizing, nitrogen-fixing, and IAA-secreting functions, including Bacillus, Bacillus-like bacteria, and Pseudomonas, were screened from the coal gangue using the streak plate separation method and then compounded to form the microbial agent.

[0012] The plant seeds are ryegrass seeds, which have been pre-treated for germination and soaked for about 24 hours before being planted in artificial soil.

[0013] Compared with the prior art, the present invention has the following beneficial effects: This invention constructs coal gangue-based artificial soil using a graded and graded method, which can form a planting layer of about 50cm without affecting soil function. Compared with ordinary artificial soil without grading, the coal gangue disposal capacity is increased by 58% to 88%, helping to solve the problem of excessive coal gangue stockpiling and enabling more large-scale application.

[0014] This invention uses a compound microbial agent, which has the function of activating multiple nutrients. Compared with no microbial agent, the germination rate is increased by 27% to 63%, and the plant height is increased by 64% to 97%, achieving a significant ecological restoration effect.

[0015] This invention utilizes coal gangue to produce high-quality artificial soil with a pH value within the optimal range for most crops (6.5-7.5) and a relatively stable soil water holding capacity. It "turns waste into treasure," meets the requirements of circular economy development, and can provide new solutions for saline-alkali land improvement and desertification control. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of artificial soil according to an embodiment of the present invention. Detailed Implementation

[0017] The present invention will now be described in detail with reference to the embodiments and accompanying drawings. It is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] Example 1, referring to Figure 1 A microbial agent for activating graded and classified artificial soil of low-grade coal gangue includes a bottom structural support layer and a nutrient activation layer laid on top of the structural support layer. The structural support layer uses large-particle, low-grade coal gangue with a particle size range of 4~10mm and a filling thickness of 25cm. The nutrient activation layer uses a mixture inoculated with microbial agents. The inoculation amount, i.e., the mass ratio of microbial agents to the mixture, is 1%. After inoculation, composting fermentation is maintained for 35 days. The mixture is a mixture of small-particle, low-grade coal gangue and local soil in equal proportions. The particle size range of the small-particle, low-grade coal gangue is less than or equal to 1 mm. The filling thickness of the nutrient activation layer is 25 cm.

[0019] The nutrient activation layer is covered with a dust covering layer, which is made of medium-sized, low-grade coal gangue with a particle size range of 1-4 mm and a covering thickness of 1 cm.

[0020] The method for preparing graded and classified artificial soil activated by microbial agents includes the following steps: 1) Mix small-sized, low-grade coal gangue with local soil in equal proportions, with a particle size range of less than or equal to 1 mm, as a mixture. 2) Add microbial inoculants to treat the above mixture. The inoculation amount is 1% of the mass ratio of microbial inoculants to the mixture. After mixing, cover the surface with a layer of plastic film and compost at an ambient temperature of 30°C. Turn the pile over every 3 days and then cover it with plastic film again. After composting for 30 days, it can be used as a nutrient activation layer for artificial soil. 3) Lay a structural support layer, fill the bottom with crushed large-particle low-grade coal gangue, with a particle size range of 4~10mm and a filling thickness of 25cm; 4) Lay the nutrient activation layer prepared in step 2) on the structural support layer, with a filling thickness of 25cm.

[0021] A method for activating low-grade coal gangue graded and classified artificial soil with microbial agents includes the following steps: 1) After watering the nutrient activation layer and structural support layer thoroughly, evenly scatter the plant seeds on the surface of the nutrient activation layer. 2) Cover the nutrient activation layer with a dust covering layer. The dust covering layer uses medium-sized, low-grade coal gangue with a particle size range of 1~4mm and a covering thickness of 1cm. 3) Water regularly and appropriately to keep the plants fresh.

[0022] The low-grade coal gangue comes from low-calorific-value coal gangue in the mining area, with a calorific value of less than 2800 kJ / kg.

[0023] The local soil was collected, impurities were removed, it was air-dried and sieved, and the particle size was <4mm.

[0024] The microbial agent is derived from coal gangue. A series of nutrient-activating bacteria with phosphorus-solubilizing, nitrogen-fixing, and IAA-secreting functions, including Bacillus, Bacillus-like bacteria, and Pseudomonas, were screened from the coal gangue using the streak plate separation method and then compounded to form the microbial agent.

[0025] The plant seeds are ryegrass seeds, which have been pre-treated for germination and soaked for about 24 hours before being planted in artificial soil.

[0026] In this embodiment, the final seed germination rate was 90%, the average plant height after one week was 11.2 cm, the soil pH was 7.95, the water holding capacity was 55%, and the coal gangue disposal rate was about 79% (coal gangue occupies the volume of artificial soil).

[0027] Example 2: A microbial agent-activated graded and classified artificial soil for low-grade coal gangue, comprising a bottom structural support layer and a nutrient activation layer laid on top of the structural support layer; The structural support layer uses large-particle, low-grade coal gangue with a particle size range of 4~10mm and a filling thickness of 30cm. The nutrient activation layer uses a mixture inoculated with microbial agents. The inoculation amount, i.e., the mass ratio of microbial agents to the mixture, is 1%. After inoculation, composting and fermentation are maintained for 30 days. The mixture is a mixture of small-particle, low-grade coal gangue and local soil in equal proportions. The particle size range of the small-particle, low-grade coal gangue is less than or equal to 1 mm. The filling thickness of the nutrient activation layer is 20 cm.

[0028] The nutrient activation layer is covered with a dust covering layer, which is made of medium-sized, low-grade coal gangue with a particle size range of 1-4 mm and a covering thickness of 1 cm.

[0029] The method for preparing graded and classified artificial soil activated by microbial agents includes the following steps: 1) Mix small-sized, low-grade coal gangue with local soil in equal proportions, with a particle size range of less than or equal to 1 mm, as a mixture. 2) Add microbial inoculants to treat the above mixture. The inoculation amount is 1% of the mass ratio of microbial inoculants to the mixture. After mixing, cover the surface with a layer of plastic film and compost at an ambient temperature of 30°C. Turn the pile over every 3 days and then cover it with plastic film again. After composting for 30 days, it can be used as a nutrient activation layer for artificial soil. 3) Lay a structural support layer, filling the bottom with crushed large-particle, low-grade coal gangue, with a particle size range of 4~10mm and a filling thickness of 30cm; 4) Lay the nutrient activation layer prepared in step 2) on the structural support layer, with a filling thickness of 20cm.

[0030] A method for activating low-grade coal gangue graded and classified artificial soil with microbial agents includes the following steps: 1) After watering the nutrient activation layer and structural support layer thoroughly, evenly scatter the plant seeds on the surface of the nutrient activation layer. 2) Cover the nutrient activation layer with a dust covering layer. The dust covering layer uses medium-sized, low-grade coal gangue with a particle size range of 1~4mm and a covering thickness of 1cm. 3) Water regularly and appropriately to keep the plants fresh.

[0031] The low-grade coal gangue comes from low-calorific-value coal gangue in the mining area, with a calorific value of less than 2800 kJ / kg.

[0032] The local soil was collected, impurities were removed, it was air-dried and sieved, and the particle size was <4mm.

[0033] The microbial agent is derived from coal gangue. A series of nutrient-activating bacteria with phosphorus-solubilizing, nitrogen-fixing, and IAA-secreting functions, including Bacillus, Bacillus-like bacteria, and Pseudomonas, were screened from the coal gangue using the streak plate separation method and then compounded to form the microbial agent.

[0034] The plant seeds are ryegrass seeds, which have been pre-treated for germination and soaked for about 24 hours before being planted in artificial soil.

[0035] In this embodiment, the final seed germination rate was 90%, the average plant height after one week was 12.8 cm, the soil pH was 7.50, the water holding capacity was 53%, and the coal gangue disposal rate was about 84% (coal gangue occupies the volume of artificial soil).

[0036] Example 3: A microbial agent-activated graded and classified artificial soil for low-grade coal gangue, comprising a bottom structural support layer and a nutrient activation layer laid on top of the structural support layer; The structural support layer uses large-particle, low-grade coal gangue with a particle size range of 4~10mm and a filling thickness of 35cm. The nutrient activation layer uses a mixture inoculated with microbial agents. The inoculation amount, i.e., the mass ratio of microbial agents to the mixture, is 1%. After inoculation, composting and fermentation are maintained for 30 days. The mixture is a mixture of small-particle, low-grade coal gangue and local soil in equal proportions. The particle size range of the small-particle, low-grade coal gangue is less than or equal to 1 mm. The filling thickness of the nutrient activation layer is 15 cm.

[0037] The nutrient activation layer is covered with a dust covering layer, which is made of medium-sized, low-grade coal gangue with a particle size range of 1-4 mm and a covering thickness of 2 cm.

[0038] The method for preparing graded and classified artificial soil activated by microbial agents includes the following steps: 1) Mix small-sized, low-grade coal gangue with local soil in equal proportions, with a particle size range of less than or equal to 1 mm, as a mixture. 2) Add microbial inoculants to treat the above mixture. The inoculation amount is 1% of the mass ratio of microbial inoculants to the mixture. After mixing, cover the surface with a layer of plastic film and compost at an ambient temperature of 30°C. Turn the pile over every 3 days and then cover it with plastic film again. After composting for 30 days, it can be used as a nutrient activation layer for artificial soil. 3) Lay a structural support layer, filling the bottom with crushed large-particle, low-grade coal gangue, with a particle size range of 4~10mm and a filling thickness of 35mm; 4) Lay the nutrient activation layer prepared in step 2) on the structural support layer, with a filling thickness of 15cm.

[0039] A method for activating low-grade coal gangue graded and classified artificial soil with microbial agents includes the following steps: 1) After watering the nutrient activation layer and structural support layer thoroughly, evenly scatter the plant seeds on the surface of the nutrient activation layer. 2) Cover the nutrient activation layer with a dust covering layer. The dust covering layer uses medium-sized, low-grade coal gangue with a particle size range of 1~4mm and a covering thickness of 2cm. 3) Water regularly and appropriately to keep the plants fresh.

[0040] The low-grade coal gangue comes from low-calorific-value coal gangue in the mining area, with a calorific value of less than 2800 kJ / kg.

[0041] The local soil was collected, impurities were removed, it was air-dried and sieved, and the particle size was less than 4 mm.

[0042] The microbial agent is derived from coal gangue. A series of nutrient-activating bacteria with phosphorus-solubilizing, nitrogen-fixing, and IAA-secreting functions, including Bacillus, Bacillus-like bacteria, and Pseudomonas, were screened from the coal gangue using the streak plate separation method and then compounded to form the microbial agent.

[0043] The plant seeds are ryegrass seeds, which have been pre-treated for germination and soaked for about 24 hours before being planted in artificial soil.

[0044] In this embodiment, the final seed germination rate was 85%, the average plant height after one week was 10.7 cm, the soil pH was 7.20, the water holding capacity was 49%, and the coal gangue disposal rate was about 89% (coal gangue occupies the volume of artificial soil).

[0045] Example 4: A microbial agent-activated graded and classified artificial soil for low-grade coal gangue, comprising a bottom structural support layer and a nutrient activation layer laid on top of the structural support layer. The structural support layer uses large-particle, low-grade coal gangue with a particle size range of 4~10mm and a filling thickness of 40cm. The nutrient activation layer uses a mixture inoculated with microbial agents. The inoculation amount, i.e., the mass ratio of microbial agents to the mixture, is 1%. After inoculation, composting and fermentation are maintained for 30 days. The mixture is a mixture of small-particle, low-grade coal gangue and local soil in equal proportions. The particle size range of the small-particle, low-grade coal gangue is less than or equal to 1 mm. The nutrient activation layer is 10 cm thick.

[0046] The nutrient activation layer is covered with a dust covering layer, which is made of medium-sized, low-grade coal gangue with a particle size range of 1-4 mm and a covering thickness of 2 cm.

[0047] The method for preparing graded and classified artificial soil activated by microbial agents includes the following steps: 1) Mix small-sized, low-grade coal gangue with local soil in equal proportions, with a particle size range of less than or equal to 1 mm, as a mixture. 2) Add microbial inoculants to treat the above mixture. The inoculation amount is 1% of the mass ratio of microbial inoculants to the mixture. After mixing, cover the surface with a layer of plastic film and compost at an ambient temperature of 30°C. Turn the pile over every 3 days and then cover it with plastic film again. After composting for 30 days, it can be used as a nutrient activation layer for artificial soil. 3) Lay a structural support layer, filling the bottom with crushed large-particle, low-grade coal gangue, with a particle size range of 4~10mm and a filling thickness of 40cm; 4) Lay the nutrient activation layer prepared in step 2) on the structural support layer, with a filling thickness of 10cm.

[0048] A method for activating low-grade coal gangue graded and classified artificial soil with microbial agents includes the following steps: 1) After watering the nutrient activation layer and structural support layer thoroughly, evenly scatter the plant seeds on the surface of the nutrient activation layer. 2) Cover the nutrient activation layer with a dust covering layer. The dust covering layer uses medium-sized, low-grade coal gangue with a particle size range of 1~4mm and a covering thickness of 2cm. 3) Water regularly and appropriately to keep the plants fresh.

[0049] The low-grade coal gangue comes from low-calorific-value coal gangue in the mining area, with a calorific value of less than 2800 kJ / kg.

[0050] The local soil was collected, impurities were removed, it was air-dried and sieved, and the particle size was less than 4 mm.

[0051] The microbial agent is derived from coal gangue. A series of nutrient-activating bacteria with phosphorus-solubilizing, nitrogen-fixing, and IAA-secreting functions, including Bacillus, Bacillus-like bacteria, and Pseudomonas, were screened from the coal gangue using the streak plate separation method and then compounded to form the microbial agent.

[0052] The plant seeds are ryegrass seeds, which have been pre-treated for germination and soaked for about 24 hours before being planted in artificial soil.

[0053] In this embodiment, the final seed germination rate was 70%, the average plant height after one week was 8.5 cm, the soil pH was 7.12, the water holding capacity was 45%, and the coal gangue disposal rate was about 94% (coal gangue occupies the volume of artificial soil).

[0054] Comparative Example 1: A coal gangue-based artificial soil with applied microbial agent, wherein the soil matrix is ​​composed of a 1:1 mixture of low-grade coal gangue and local soil, and a compound microbial agent is applied externally.

[0055] The low-grade coal gangue comes from low-calorific-value coal gangue in the mining area, with a calorific value of less than 2800 kJ / kg.

[0056] The local soil was collected, impurities were removed, it was air-dried and sieved, and the particle size was less than 4 mm.

[0057] The microbial agent is a complex of a series of nutrient-activating bacteria, including Bacillus, Bacillus-like bacteria, and Pseudomonas.

[0058] The plant seeds are ryegrass seeds, which have been pre-treated for germination and soaked for 24 hours before being planted in artificial soil.

[0059] A method for preparing and applying coal gangue-based artificial soil with applied microbial agents includes the following steps: 1) Mix coal gangue and soil evenly in a 1:1 ratio and fill the bottom with a filling thickness of 50cm; 2) Add microbial agent to treat the above mixture at an inoculum rate of 1% (mass ratio of microbial agent to test substrate); after mixing, cover the surface with a layer of plastic film and compost at an ambient temperature of 30℃. Turn the pile over every 3 days, then cover it with plastic film again and maintain this condition for 30 days. 3) After watering the soil thoroughly, scatter 50 plant seeds evenly on the soil surface; 4) Finally, gently cover with soil, with a thickness of 2cm.

[0060] 5) Water regularly and appropriately to keep the plants fresh.

[0061] The final seed germination rate of this comparative example was 85%, the average plant height after one week was 9.3 cm, the soil pH was 8.58, the water holding capacity was 51%, and the coal gangue disposal rate was about 50% (coal gangue occupies the volume of artificial soil).

[0062] Comparative Example 2: A graded artificial soil based on coal gangue, wherein the structural support layer is 30 cm thick, the nutrient activation layer is 20 cm thick, and the dust covering layer is 2 cm thick.

[0063] The low-grade coal gangue comes from low-calorific-value coal gangue in the mining area, with a calorific value of less than 2800 kJ / kg.

[0064] The local soil was collected, impurities were removed, it was air-dried and sieved, and the particle size was less than 4 mm.

[0065] The plant seeds are ryegrass seeds, which have been pre-treated for germination and soaked for 24 hours before being planted in artificial soil.

[0066] A method for preparing and applying graded coal gangue-based artificial soil includes the following steps: 1) First, fill the bottom with crushed large-particle coal gangue (particle size range of 4~10mm) to a thickness of 30cm; 2) Mix the crushed small-sized coal gangue (particle size range of 0~1mm) with local soil in equal proportion and lay it in the middle layer with a filling thickness of 20cm; 3) After watering the soil thoroughly, scatter 50 plant seeds evenly on the soil surface; 4) Finally, gently cover with medium-sized coal gangue (particle size range of 1~4mm) to a thickness of 2cm; 5) Water regularly and appropriately to keep the plants fresh.

[0067] The final seed germination rate of this comparative example was 55%, the average plant height after one week was 6.5 cm, the soil pH was 8.03, the water holding capacity was 53%, and the coal gangue disposal rate was about 84% (coal gangue accounted for 84% of the volume of the artificial soil).

[0068] The effects of Examples 1-4 and Comparative Examples 1-2 are shown in Table 1. In Comparative Example 1, the coal gangue-based artificial soil was not graded, and the coal gangue absorption rate was only 50%. In Comparative Example 2, although the coal gangue absorption rate was improved, the soil quality was poor due to the lack of activation by the compound microbial agent, making it difficult for plants to survive. In contrast, all examples showed significant improvement effects, with soil pH and water holding capacity within the optimal range for most crops, and the coal gangue absorption rate increased to 79%~94%. Among them, Example 2 had the highest plant germination rate and average plant height. Therefore, the preferred embodiment of this invention is an artificial soil prepared by grading low-grade coal gangue activated by a microbial agent, wherein the structural support layer is 30cm thick, the nutrient activation layer is 20cm thick, the dust covering layer is 1cm thick, and the compound microbial agent application rate is 1%.

[0069] Table 1

Claims

1. A microbial agent for activating graded and classified artificial soil from low-grade coal gangue, characterized in that: This includes a bottom structural support layer, on which a nutrient activation layer is laid. The structural support layer uses large-particle, low-grade coal gangue with a particle size range of 4~10mm and a filling thickness of 25~40cm. The nutrient activation layer uses a mixture inoculated with microbial agents. The inoculation amount, i.e., the mass ratio of microbial agents to the mixture, is less than or equal to 2%. After inoculation, composting fermentation is maintained for 30 to 35 days. The mixture is a mixture of small-particle, low-grade coal gangue and local soil in equal proportions. The particle size range of the small-particle, low-grade coal gangue is less than or equal to 1 mm. The filling thickness of the nutrient activation layer is 10 to 25 cm.

2. The artificial soil for grading and classifying low-grade coal gangue activated by a microbial agent according to claim 1, characterized in that: The nutrient activation layer is covered with a dust covering layer, which is made of medium-sized, low-grade coal gangue with a particle size range of 1-4 mm and a covering thickness of 1-2 cm.

3. The method for preparing graded and classified artificial soil from low-grade coal gangue activated by microbial agents as described in claim 1, characterized in that, Includes the following steps: 1) Mix small-sized, low-grade coal gangue with local soil in equal proportions, with a particle size range of less than or equal to 1 mm, as a mixture. 2) Add microbial inoculants to treat the above mixture. The inoculation amount, i.e., the mass ratio of microbial inoculants to the mixture, should be less than or equal to 2%. After mixing, cover the surface with a layer of plastic film and compost at an ambient temperature of 30-35℃. Turn the pile over every 3-5 days and then cover it with plastic film again. After composting for 30-35 days, it can be used as a nutrient activation layer for artificial soil. 3) Lay a structural support layer, filling the bottom with crushed large-sized low-grade coal gangue, with a particle size range of 4~10mm and a filling thickness of 25~40cm; 4) Lay the nutrient activation layer prepared in step 2) on the structural support layer, with a filling thickness of 10~25cm.

4. The preparation method according to claim 3, characterized in that, The low-grade coal gangue comes from low-calorific-value coal gangue in the mining area, with a calorific value of less than 2800 kJ / kg.

5. The preparation method according to claim 3, characterized in that, The local soil was collected, impurities were removed, it was air-dried and sieved, and the particle size was less than 4 mm.

6. The preparation method according to claim 3, characterized in that, The microbial agent is derived from coal gangue. A series of nutrient-activating bacteria with phosphorus-solubilizing, nitrogen-fixing, and IAA-secreting functions, including Bacillus, Bacillus-like bacteria, and Pseudomonas, were screened from the coal gangue using the streak plate separation method and then compounded to form the microbial agent.

7. The method for applying a microbial agent to activate graded and classified artificial soil from low-grade coal gangue, as described in claim 2, is characterized in that... Includes the following steps: 1) After watering the nutrient activation layer and structural support layer thoroughly, evenly scatter the plant seeds on the surface of the nutrient activation layer. 2) Cover the nutrient activation layer with a dust covering layer. The dust covering layer uses medium-sized, low-grade coal gangue with a particle size range of 1~4mm and a covering thickness of 1~2cm. 3) Water regularly and appropriately to keep the plants fresh.

8. The application method according to claim 7, characterized in that, The plant seeds are ryegrass seeds, which have been pre-treated for germination and soaked for about 24 hours before being planted in artificial soil.

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