Coal mine solid-liquid-gas three waste cooperative near zero emission mining method

Abstract

The present application relates to the technical field of coal green mining and mine ecological environment protection, in particular to a coal mine solid-liquid-gas three waste collaborative near-zero emission mining method, comprising: gas source head reduction and resourceization pretreatment before mining, underground site selection to build underground reservoir and sorting chamber before mining, process reduction and solid waste in-situ disposal during mining, underground utilization of mine water, gas dispersion control and resource utilization of spent air during mining process, ecological resource utilization and ecological restoration of solid waste after mining. The present application aims at the technical problems of single end treatment, poor multi-medium collaboration and low resource utilization rate in the existing disposal of coal mine solid, liquid and gas waste, through whole process time sequence collaboration and cross-medium complementation before, during and after mining, the near-zero emission target of coal gangue comprehensive utilization rate >= 95%, mine water comprehensive utilization rate >= 95%, and coal mine gas comprehensive utilization rate >= 90% is realized.

Description

Technical Field

[0001] This invention relates to the field of green coal mining and mine ecological environment protection technology, specifically a near-zero emission mining method for the coordinated treatment of solid, liquid, and gaseous wastes in coal mines. Background Technology

[0002] Coal is my country's primary energy source, but the disposal of the "three wastes" generated during coal mining—coal gangue (solid), mine water (liquid), and gas—has long faced significant challenges. Existing technologies primarily address the end-of-pipe treatment of individual wastes, such as underground gangue backfilling, surface mine water treatment, and gas extraction for power generation. However, these technologies suffer from three core shortcomings in practical coal mine production: First, they are fragmented in timeline and lack full-process coordination. Gas extraction, mine water treatment, and gangue backfilling belong to different stages—pre-mining, during-mining, and post-mining—and are planned and operated independently, failing to establish a temporally and spatially aligned "waste-to-waste" relationship. For example, goafs, serving as optimal backfilling and water storage spaces, are often sealed off after gangue backfilling, failing to simultaneously utilize the in-situ purification function of mine water.

[0003] Spatial conflict and separation of underground and surface functions: A large amount of waste (especially gangue and mine water) still follows the path of "lifting to the surface - surface treatment - partial reuse", which not only consumes transportation energy and land resources, but also misses the natural advantage of in-situ disposal and utilization underground, resulting in high treatment costs and low resource utilization efficiency.

[0004] The media are isolated, and cross-media complementarity has not been explored: the adsorption properties of gangue, the fluidity of mine water, and the energy properties of gas are not interconnected in existing technologies. This has prevented the realization of synergistic benefits across multiple media, such as using gangue / fly ash to assist in the purification of mine water, using mine water to prepare backfill materials, and using gas extraction to ensure the safety of backfilling operations.

[0005] In summary, current technologies have not yet formed a comprehensive engineering method that deeply integrates and coordinates the three types of coal mine waste in terms of time, space, and function, thus hindering coal mines from achieving near-zero emissions and a green, low-carbon transformation. Therefore, developing a method for the coordinated treatment of coal mine waste that integrates pre-mining, mining, and post-mining processes and complements different media is of great significance. Summary of the Invention

[0006] The purpose of this invention is to provide a method for near-zero emission mining of coal mine solid, liquid, and gaseous wastes in a coordinated manner, so as to solve the problems mentioned in the background art.

[0007] To achieve the above objectives, the present invention provides the following technical solution.

[0008] A coal mine near-zero emission mining method for coordinating solid, liquid, and gas waste includes the following steps: S1, pre-mining gas source reduction and resource utilization pretreatment: Before mining, borehole gas pre-extraction is carried out on the coal seam in the mining area, the extracted gas is transported to the surface gas storage device, and the gas is utilized in stages according to the gas volume fraction.

[0009] S2. Pre-mining underground site selection and construction of underground reservoirs and sorting chambers: Before mining, underground reservoirs are constructed in adjacent mined working faces or adjacent goaf areas to store water gushing from the roof and floor aquifers and wastewater generated during mining; sorting chambers are arranged in the underground roadways, and dry sorting machines are placed in the sorting chambers to separate coal and gangue from the mined raw coal.

[0010] S3. Emission Reduction and In-situ Solid Waste Disposal During Mining: During the mining process, the mined raw coal is transported to the underground sorting chamber, sorted by a dry sorting machine, and the sorted gangue is stored in the underground gangue bin. Backfilling materials are prepared and transported to the goaf for backfilling. The remaining gangue is brought to the surface from the auxiliary shaft of the coal mine and then classified and utilized according to its composition.

[0011] S4. Mine water utilization underground: Mine water generated during mining is transported to underground reservoirs in the goaf area. The collapsed rock mass in the goaf area is used to complete the underground purification treatment. The purified mine water is given priority to supply underground production and dust suppression water. The remaining mine water is brought to the surface reservoir for treatment and then used in a tiered manner according to water quality.

[0012] S5. Control of gas escape during mining and utilization of exhaust gas: During the mining process, gas in the exhaust gas is captured from the ventilation outlet of the surface ventilation shaft and purified. The purified gas is then incorporated into the cascade resource utilization system.

[0013] S6. Ecological resource utilization and ecological restoration of post-mining solid waste: Fly ash generated during coal sorting and combustion is used in conjunction with low-calorific-value coal gangue after ground grading for land reclamation and soil improvement in mining subsidence areas. The adsorption characteristics of coal gangue and fly ash are also used as auxiliary filter media for mine water treatment.

[0014] As a further aspect of the present invention: in step S1, the gas pre-extraction adopts the in-seam parallel drilling extraction technology, and the extraction borehole diameter is 110mm; the cascade resource utilization path is as follows: gas with a methane volume fraction ≥30% is directly used for gas-fired power generation, urban gas supply or industrial fuel; gas with a methane volume fraction of 16% ≤ 30% is purified to above 30% and then incorporated into the high-concentration gas utilization system; gas with a methane volume fraction of 9% ≤ 16% is connected to the low-concentration gas generator set; gas with a methane volume fraction of <9% and exhaust air are combined using thermal regenerative oxidation technology to recover waste heat.

[0015] As a further aspect of the present invention: in step S3, the solid composition ratio of the underground filling material is gangue: cement: fly ash = 80:15:4, the solid component accounts for 60% of the total mass of the filling material, and the remaining water is mine water purified from an underground reservoir.

[0016] As a further aspect of the present invention: in step S3, coal gangue is classified and disposed of according to its carbon content: gangue with a carbon content ≤6% is used for underground backfilling; gangue with a carbon content of 6%-20% is used for preparing building materials; and gangue with a carbon content >20% is used for low-calorific-value power generation.

[0017] As a further aspect of the present invention: in step S4, the hydraulic residence time of the mine water in the underground reservoir of the goaf is ≥24h, and natural purification is achieved by utilizing the dissolution, adsorption, and oxidation-reduction effects of the collapsed rock mass in the goaf.

[0018] As a further aspect of the present invention: in step S5, exhaust gas capture adopts a pressure swing adsorption device to purify the gas in the exhaust gas to a methane volume fraction of 9%-16% before resource utilization.

[0019] As a further aspect of the present invention: in step S5, real-time underground gas monitoring technology is used to continuously monitor the gas concentration online, with a gas concentration monitoring accuracy of ≤0.1%CH4 and a response time of ≤30s; the gas concentration at the working face is controlled below 0.5% through ventilation system optimization.

[0020] As a further aspect of the present invention: in step S6, the coal gangue surface application is treated according to its physical and chemical properties: when the SiO2 content is >55%, it is used to prepare sintered bricks; when the Al2O3 content is >25%, it is used as a cement additive; when the S content is >6%, it is used to recover sulfur resources; when the ash content is ≤85% and the moisture content is <2%, it is used to produce fertilizers or improve soil; when none of the above conditions are met, it is used as an engineering building material.

[0021] Compared with existing technologies, the beneficial effects of this invention are: 1. It constructs a whole-process collaborative control system: This invention breaks through the traditional single governance model of "divide and conquer, end-of-pipe treatment" for coal mine waste. Through the spatiotemporal collaborative design of the entire life cycle of pre-mining, during-mining, and post-mining, it fundamentally solves the core technical bottlenecks such as spatiotemporal conflicts, process fragmentation, and low resource utilization that have long existed in the traditional treatment mode for solid, liquid, and gaseous wastes. It realizes a fundamental transformation of the treatment of the three wastes from "passive end-of-pipe treatment" to "active whole-process control".

[0022] 2. Achieved cross-media synergistic resource utilization of three wastes: This invention utilizes the adsorption characteristics of coal gangue and fly ash (specific surface area ≥ 5m²). 2 / g) Auxiliary mine water treatment can improve the suspended solids removal rate to over 85%; mine water is used for underground dust suppression spraying, equipment cooling, and backfill material preparation; gas extraction ensures safe and efficient backfilling mining. The various treatment links form a synergistic and complementary relationship, greatly improving the comprehensive utilization rate of coal mine waste and realizing the cascade utilization of gas at all concentrations.

[0023] 3. Near-zero emission target achieved: Engineering verification shows that this method can increase the comprehensive utilization rate of coal gangue from the current about 70% to more than 95%, the comprehensive utilization rate of mine water from less than 50% to more than 95%, and the comprehensive utilization rate of coal mine gas concentration from less than 50% to more than 90%, basically achieving near-zero emissions of coal mine waste.

[0024] 4. Reduced environmental costs: In-situ backfilling underground saves on surface transportation costs of gangue, land occupation costs of gangue piles, and environmental pollution discharge fees; underground recycling of mine water saves on water resource costs and construction and operation costs of surface water treatment plants; and the cascade utilization of full concentration of methane generates clean energy benefits. Attached Figure Description

[0025] Figure 1 This is a diagram showing the layout of underground facilities for the near-zero emission mining method for the co-processing of solid, liquid, and gaseous wastes in coal mines according to the present invention.

[0026] Figure 2 This is a schematic diagram of the working face of the coal mine near-zero emission mining method for the coordinated treatment of solid, liquid, and gaseous wastes according to the present invention.

[0027] Figure 3 This is a ground system layout diagram of the near-zero emission mining method for the co-processing of solid, liquid, and gaseous wastes in coal mines according to the present invention.

[0028] Figure 4 This is a flowchart illustrating the graded and graded resource utilization process of coal gangue according to the present invention.

[0029] Figure 5 This is a process flow diagram of the full-concentration cascade resource utilization technology for coal mine gas according to the present invention.

[0030] Figure 6 This is a flowchart of the overall process flow of the coal mine near-zero emission mining method that combines solid, liquid, and gaseous wastes according to the present invention.

[0031] In the diagram: 1. Return airway; 2. Track roadway; 3. Transport roadway; 4. Working face track level roadway; 5. Working face return air level roadway; 6. Gas extraction borehole; 7. Underground gangue bin; 8. Separation chamber; 9. Dry separator; 10. Underground reservoir dam; 11. Underground reservoir water storage space; 12. Goaf; 13. Coal mining face; 14. Ventilation shaft; 15. Ventilation shaft ventilation duct; 16. Exhaust gas capture device; 17. Gas valve; 18. Gas storage tank; 19. Auxiliary shaft; 20. Surface reservoir; 21. Water valve; 22. Gangue conveyor belt; 23. Surface gangue bin. Detailed Implementation

[0032] The technical solution of this application will be further described in detail below with reference to specific embodiments.

[0033] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0034] Example

[0035] This embodiment takes a typical underground coal mine as an example. The coal seam dip angle is ≤25°, the burial depth is ≤800m, and the original gas content is ≥5m³. 3 / t, thus possessing the conditions for implementing this invention.

[0036] The overall process flow of this embodiment is shown below. Figure 6 .like Figures 1 to 6 As shown in the figure, this embodiment provides a method for near-zero emission mining of coal mine solid, liquid and gas waste, which specifically includes the following steps.

[0037] S1. Pre-mining gas source reduction and resource utilization pretreatment: Before mining, borehole gas pre-extraction is carried out on the coal seam in the mining area. The extracted gas is transported to the surface gas storage device and utilized in stages according to the gas volume fraction.

[0038] Specifically, six months before mining begins, parallel borehole pre-drainage of gas is carried out in the coal seam of the mining area. For example... Figure 1 As shown, six gas drainage boreholes with a diameter of 110 mm are arranged in the coal seams on both sides of the working face. The spacing and drainage time of the drainage boreholes are determined comprehensively based on the original gas content of the coal seam, the target gas content after drainage, and the drainage radius.

[0039] The borehole spacing and extraction time need to be calculated according to the following steps.

[0040] First, determine the extractable gas reserves in the coal seam: .

[0041] The extraction radius range is determined based on the set gas extraction efficiency η: ;in: This refers to the amount of extractable gas within the coal seam. The amount of gas extracted from the borehole within time T; L is the density of the coal; L is the length of the extraction borehole (longer than half the length of the extraction face); R is the extraction radius (the borehole spacing is 2R); h is the coal seam thickness; W0 is the original gas content; Wcy When the gas content reaches the standard (generally <8m), the extraction rate is considered to be within acceptable limits. 3 / t); For extraction efficiency.

[0042] Based on extensive field tests, the relationship between extraction time T and borehole radius R is as follows: .

[0043] In practical applications, the design of gas drainage boreholes should be carried out according to the above steps based on geological conditions.

[0044] The extracted gas is transported through pipelines to ground-based gas storage tank 18, where it is utilized in stages according to concentration. (See process flow diagram). Figure 5 High-concentration methane with a methane volume fraction ≥30% is directly used for gas-fired power generation, urban gas supply, or industrial fuel; methane with a methane volume fraction of 16% ≤ 30% is purified to ≥30% and then incorporated into the high-concentration methane utilization system; medium-concentration methane with a methane volume fraction of 9% ≤ 16% is connected to a low-concentration methane generator set; ultra-low-concentration methane with a methane volume fraction of <9% and mine exhaust air are combined using thermal regenerative oxidation technology to recover waste heat for wellhead antifreeze or employee bathing.

[0045] S2. Pre-mining underground site selection and construction of underground reservoir and sorting chamber 8: Before mining, an underground reservoir is constructed in the adjacent mined working face or adjacent goaf area to store the water inflow from the roof and floor aquifers and the wastewater generated during mining; sorting chamber 8 is arranged in the underground roadway, and dry sorting machine 9 is placed in sorting chamber 8 to separate coal and gangue from the mined raw coal.

[0046] Specifically, before mining begins, an underground reservoir is constructed in the goaf area 12 of the adjacent mined working face (where backfilling has been completed and the collapsed rock mass has stabilized). For example... Figure 1 As shown, the underground reservoir includes an underground reservoir dam 10 and an underground reservoir storage space 11, which is used to store water gushing from the aquifers at the top and bottom plates during the mining process and wastewater generated during mining.

[0047] The underground roadway system in this embodiment includes a return air roadway 1, a track roadway 2, and a transport roadway 3, providing ventilation and transport channels for coal mining. A sorting chamber 8 is arranged near the underground transport roadway 3, and a dry separator 9 (a TDS dry separator can be used, suitable for raw coal particle size of 50-300mm, raw coal moisture content ≤7%, single unit processing capacity of 200t / h) is placed in the sorting chamber 8 for separating coal and gangue from the mined raw coal.

[0048] S3. Emission reduction and in-situ solid waste disposal during mining: During the mining process, the mined raw coal is transported to the underground sorting chamber 8, sorted by the dry sorting machine 9, and the sorted gangue is stored in the underground gangue bin 7. The backfill material is prepared and transported to the goaf 12 for backfilling. The remaining gangue is brought to the surface from the auxiliary shaft 19 of the coal mine and then classified and utilized according to its composition.

[0049] Specifically, during the longwall mining process at face 13, the mined raw coal is transported to the underground sorting chamber 8 via the face track roadway 4 and the main transport roadway 3, where it is sorted by the dry sorting machine 9. The sorted gangue is stored in the underground gangue bin 7 and used directly to prepare backfill material.

[0050] The backfill material was prepared according to the following ratio: gangue:cement:fly ash = 80:15:4 (mass ratio), with solid components accounting for 60% of the total mass of the backfill material. The remaining water was mine water purified from underground reservoir storage space 11. After being mixed into a slurry, it was transported to the goaf 12 for backfilling through the backfill pipeline. Laboratory orthogonal experiments verified that, under this ratio, the 21-day uniaxial compressive strength of the backfill body was ≥14.28 MPa, the 3-day uniaxial compressive strength was ≥7.88 MPa, and the water bleeding rate of the backfill body was ≤5%, meeting the surface settlement control requirements for "three-under" coal mining in the "Specifications for Coal Pillar Retention and Coal Mining in Buildings, Water Bodies, Railways and Main Shafts".

[0051] The remaining unprocessed gangue is transported from auxiliary shaft 19 to surface gangue bin 23 via gangue conveyor belt 22, where it is graded and sorted according to carbon content for resource utilization. (See process flow diagram). Figure 4 Gangue with a carbon content of ≤6% is used for underground backfilling; gangue with a carbon content of 6%-20% is used for preparing building materials; gangue with a carbon content of >20% is used for low-calorific-value power generation.

[0052] S4. Mine water utilization underground: Mine water generated during mining is transported to the underground reservoir in the goaf area. The collapsed rock mass in the goaf area is used to complete the underground purification treatment. The purified mine water is given priority to supply underground production and dust suppression water. The remaining mine water is brought to the surface reservoir for 20 treatments and then used in a tiered manner according to water quality.

[0053] Specifically, the mine water generated during the mining process is transported to the underground reservoir storage space 11 in the goaf area. Under the condition that the hydraulic retention time is ≥24h, the mine water is naturally purified by the dissolution, adsorption and oxidation-reduction of the collapsed rock mass in the goaf area. The suspended solids (SS) removal rate is ≥85%, the purified suspended solids are ≤30mg / L, and the chemical oxygen demand (COD) removal rate is ≥50%.

[0054] The purified mine water is given priority to underground spray dust suppression, equipment cooling and filling material preparation. The remaining mine water is lifted from the auxiliary shaft 19 and transported to the surface reservoir 20. After deep treatment, it is used in stages according to water quality. The surface reservoir 20 is equipped with a water valve 21 to control the water flow.

[0055] S5. Control of gas escape during mining and utilization of exhaust gas: During the mining process, gas in the exhaust gas is captured from the air outlet of the ventilation shaft 15 on the ground and purified. The purified gas is then incorporated into the cascade resource utilization system.

[0056] Specifically, during the mining process, residual gas in the coal seam escapes into the underground air and is transported to the surface ventilation shaft 14 via the ventilation system through the return air roadway 5 and the main return air roadway 1. A waste gas collection device 16, employing a pressure swing adsorption (PSA) system, is installed at the outlet of the ventilation duct 15 in the surface ventilation shaft, with a single unit capable of handling 1000~5000 m³ / h of gas. 3 / h, methane recovery rate ≥80%, after purifying the gas in the exhaust gas to a methane volume fraction of 9%-16%, it is incorporated into the [unclear - possibly a specific process or product]. Figure 5 The illustrated cascade resource utilization system includes a gas storage tank 18 equipped with a gas valve 17 for controlling gas delivery.

[0057] Meanwhile, real-time underground gas monitoring technology is used to continuously monitor the gas concentration online. The gas concentration monitoring accuracy is ≤0.1%CH4, and the response time is ≤30s. The gas concentration at the working face is controlled below 0.5% through ventilation system optimization.

[0058] S6. Ecological resource utilization and ecological restoration of post-mining solid waste: Fly ash generated during coal sorting and combustion is used in conjunction with low-calorific-value coal gangue after ground grading for land reclamation and soil improvement in mining subsidence areas. The adsorption characteristics of coal gangue and fly ash are also used as auxiliary filter media for mine water treatment.

[0059] Specifically, fly ash generated during coal sorting and combustion is used in conjunction with low-calorific-value coal gangue after ground grading for land reclamation and soil improvement in mining subsidence areas. Simultaneously, the adsorption properties of coal gangue and fly ash are utilized as auxiliary filter media for mine water treatment.

[0060] Coal gangue is treated according to its physical and chemical properties for surface application; the process flow is described in [link to process flow chart]. Figure 4 When the SiO2 content is >55%, it is used to prepare sintered bricks; when the Al2O3 content is >25%, it is used as a cement additive; when the S content is >6%, it is used to recover sulfur resources; when the ash content is ≤85% and the moisture content is <2%, it is used to produce fertilizers or improve soil; when none of the above conditions are met, it is used as an engineering building material.

[0061] After the implementation of this embodiment, the treatment effect of the coal mine's "three wastes" was statistically analyzed, and the results are as follows: the comprehensive utilization rate of coal gangue is ≥95%, the comprehensive utilization rate of mine water is ≥95%, and the comprehensive utilization rate of the total concentration of coal mine gas is ≥90%, achieving near-zero emissions of the coal mine's "three wastes".

[0062] This near-zero emission mining method for solid, liquid, and gaseous waste in coal mines constructs a theoretical framework for the coordinated control of the entire process, from source reduction to process reduction to resource utilization. It breaks through the technical limitations of traditional end-of-pipe treatment of coal mine waste. Through the time-series coordinated design of the entire coal mining cycle, it solves the spatiotemporal conflict problem of existing waste treatment technologies, realizes closed-loop management and coordinated treatment of solid, liquid, and gaseous wastes, and basically achieves near-zero emissions of coal mine wastes. While ensuring safe and efficient coal mining, it significantly reduces the ecological and environmental impact of coal mining and helps the coal mining industry to reduce pollution and carbon emissions and increase efficiency.

[0063] This invention also realizes the cross-media synergistic resource utilization of "three wastes" (waste gas, wastewater, and solid waste). It utilizes the adsorption characteristics of coal gangue and fly ash to assist in mine water treatment. The mine water is used for underground spray dust suppression, equipment cooling, and material preparation. Gas extraction ensures the safety and efficiency of backfilling mining. The various disposal links form a synergistic and complementary relationship, which greatly improves the comprehensive utilization rate of coal mine waste and realizes the full-concentration cascade utilization of gas.

[0064] The above are merely preferred embodiments of the present invention. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention, and these should also be considered within the scope of protection of the present invention. These will not affect the effectiveness of the implementation of the present invention or the practicality of the patent.

Claims

1. A method for near-zero emission mining of coal mine solid, liquid, and gaseous wastes, characterized in that, Includes the following steps: S1. Pre-mining gas source reduction and resource utilization pretreatment: Before mining, pre-extraction of gas is carried out in the coal seam of the mining area through boreholes. The extracted gas is transported to the surface gas storage device and utilized in stages according to the gas volume fraction. The staged resource utilization path is as follows: gas with a methane volume fraction ≥30% is directly used for gas-fired power generation, urban gas supply or industrial fuel; gas with a methane volume fraction of 16% ≤ 30% is purified to above 30% and then incorporated into the high-concentration gas utilization system; gas with a methane volume fraction of 9% ≤ 16% is connected to the low-concentration gas generator set; gas with a methane volume fraction <9% and exhaust air are treated with thermal regenerative oxidation technology to recover waste heat. S2. Pre-mining underground site selection and construction of underground reservoirs and sorting chambers: Before mining, an underground reservoir is constructed in the adjacent mined working face or adjacent goaf to store water gushing from the roof and floor aquifers and wastewater generated during mining; sorting chambers are arranged in the underground roadways, and dry sorting machines are placed in the sorting chambers to separate coal and gangue from the mined raw coal; S3. Emission reduction and in-situ solid waste disposal during mining: During the mining process, the mined raw coal is transported to the underground sorting chamber, sorted by a dry sorting machine, and the sorted gangue is stored in the underground gangue bin. Backfilling materials are prepared and transported to the goaf for backfilling. The remaining gangue is brought to the surface from the auxiliary shaft of the coal mine and then classified and utilized according to its composition. S4. Mine water utilization underground: Mine water generated during mining is transported to an underground reservoir in the goaf area. The goaf collapse rock mass is used to complete the underground purification treatment. The purified mine water is given priority to supply underground production and dust suppression water. The remaining mine water is brought to the surface reservoir for further treatment and then used in a tiered manner according to water quality. The hydraulic residence time of the mine water in the goaf area underground reservoir is ≥24 hours, and natural purification is achieved by the dissolution, adsorption, and oxidation-reduction effects of the goaf collapse rock mass. S5. Gas Emission Control and Waste Air Resource Utilization During Mining: During mining, gas in the waste air is captured and purified from the ventilation shaft outlet at the surface. The purified gas is then incorporated into the cascade resource utilization system. Gas capture in the waste air utilizes a pressure swing adsorption device to purify the gas to a methane volume fraction of 9%-16% before resource utilization. Real-time underground gas monitoring technology is used to continuously monitor the gas concentration online, with a monitoring accuracy of ≤0.1%CH4 and a response time of ≤30s. The gas concentration at the working face is controlled below 0.5% through ventilation system optimization. S6. Ecological resource utilization and ecological restoration of post-mining solid waste: Fly ash generated during coal sorting and combustion is used in conjunction with low-calorific-value coal gangue after ground grading for land reclamation and soil improvement in mining subsidence areas. The adsorption characteristics of coal gangue and fly ash are also used as auxiliary filter media for mine water treatment.

2. The coal mine near-zero emission mining method for the coordinated treatment of solid, liquid, and gaseous wastes according to claim 1, characterized in that, In step S1, the gas pre-extraction adopts the in-seam parallel borehole extraction technology, and the diameter of the extraction borehole is 110mm.

3. The coal mine near-zero emission mining method for the coordinated treatment of solid, liquid, and gaseous wastes according to claim 1, characterized in that, In step S3, the solid composition ratio of the underground backfill material is gangue:cement:fly ash = 80:15:4, with the solid component accounting for 60% of the total mass of the backfill material, and the remaining water is mine water purified from an underground reservoir.

4. The coal mine near-zero emission mining method for the coordinated treatment of solid, liquid, and gaseous wastes according to claim 1, characterized in that, In step S3, coal gangue is classified and disposed of according to its carbon content: gangue with a carbon content ≤6% is used for underground backfilling; gangue with a carbon content of 6%-20% is used to prepare building materials; and gangue with a carbon content >20% is used for low-calorific-value power generation.

5. The coal mine near-zero emission mining method for the coordinated treatment of solid, liquid, and gaseous wastes according to claim 1, characterized in that, In step S6, the coal gangue is treated according to its physical and chemical properties: when the SiO2 content is >55%, it is used to prepare sintered bricks; when the Al2O3 content is >25%, it is used as a cement additive; when the S content is >6%, it is used to recover sulfur resources; when the ash content is ≤85% and the moisture content is <2%, it is used to produce fertilizers or improve soil; when none of the above conditions are met, it is used as an engineering building material.

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