Method and system for constructing coal mine underground reservoir by multi-type filling mining

Abstract

The application discloses a kind of multi-type filling mining construction coal mine underground reservoir method and system, belong to mining engineering field, wherein multi-type filling mining construction coal mine underground reservoir method includes the following steps: step one, according to the geological conditions of coal mining area, ore body property, mining technology and environmental influence, from short wall paste continuous mining continuous filling, fully mechanized paste filling and pumping pillar type filling three filling mining methods select the best method;Step two, set up drainage system on the ground, and guide surface water to sedimentation tank;Step three, construct power generation reservoir in underground space, guide surface water into reservoir, and convert surface water gravitational potential energy into electric energy to provide power for mine power grid.The application reduces the settlement caused by mining on the ground, realizes the rational use of space resources, uses the space reserved by surface subsidence area and underground filling mining to store water and energy, relieves the tension of water resources in mining area, reduces cost and realizes the rational allocation of resources.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of mining engineering, and in particular to a method and system for constructing a coal mine underground reservoir through multi-type filling mining. BACKGROUND

[0002] With the improvement of coal mining specifications, the requirements for environmental problems are becoming increasingly stringent. Ground subsidence caused by coal mining and environmental pollution caused by mining waste have become one of the primary problems for land reclamation and green development in mining areas. Filling mining, as a green mining method, uses gangue and other mining waste to fill goaf to reduce environmental pollution, achieve resource recycling, increase bottom stability, and reduce the risk of ground subsidence and collapse.

[0003] Traditional filling mining only fills the mining space with waste and other binders mixed with water, which cannot fully utilize the stable space existing in the mining process, and the large filling space leads to high costs, which has been a disadvantage of filling mining. The present application forms a large storage space by supporting the filled goaf through three filling mining methods, alleviates the shortage of resource storage, and realizes the rational utilization of space resources. SUMMARY

[0004] To solve the above problems, the present application provides a method and system for constructing a coal mine underground reservoir through multi-type filling mining, which reduces the subsidence caused by mining on the ground, realizes the rational utilization of space resources, uses the space left by the ground subsidence area and underground filling mining for water storage and energy storage, alleviates the shortage of water resources in the mining area, reduces costs, and realizes the rational allocation of resources.

[0005] To achieve the above purpose, the present application provides a method for constructing a coal mine underground reservoir through multi-type filling mining, comprising the following steps:

[0006] Step one: according to the geological conditions of the coal mining area, the properties of the ore body, the mining technology, and the environmental impact, the best method is selected from the three filling mining methods of short-wall paste body continuous mining and continuous filling, fully-mechanized mining paste filling, and pump-supported pillar filling;

[0007] Step two: setting a drainage system on the ground and guiding the surface water to a sedimentation tank;

[0008] Step three: constructing a power generation reservoir in the underground space, guiding the surface water into the reservoir, and converting the gravitational potential energy of the surface water into electrical energy to provide power for the power grid on the mine.

[0009] Preferably, in step one, the underground space is filled by the method of short-wall paste body continuous mining and continuous filling, which comprises the following steps:

[0010] Step 1: According to the actual situation, plan the interval mining roadway and filling roadway, and leave a water storage space after interval mining and filling;

[0011] Step 2: Use a coal cutter to cut the coal seam, use a crusher to crush the cut coal, and use a loader to load the crushed coal into the transportation equipment;

[0012] Step 3: Mine the roadway that needs to be filled, and after the mining of the roadway is completed, fill the basic structure filling material and the specific functional anti-seepage and sealing material into the goaf through the pumping machine;

[0013] Step 4: After the filling body is stable and meets the stability and impermeability requirements, mine the roadway as a water storage space;

[0014] Step 5: Set up a tailwater surge chamber for the water storage space, and monitor and regulate the reservoir.

[0015] Preferably, in step one, the underground space is mined by fully mechanized mining, and a fully mechanized paste filling method is used to mine the underground space. During the mining process, an upper end frame, a middle frame, a lower end frame, a drainage pipe, a filling pipe, and a material distribution pipe are pre-installed in the goaf. The upper end frame, the middle frame, and the lower end frame are connected and arranged in the goaf in sequence to support the coal mining machine and the conveyor and guide the advancement of the coal mining machine and the conveyor. The drainage pipe is arranged behind the upper end frame to drain the waste water generated during the mining process. The material distribution pipe is arranged below the middle frame to transport the mined coal. The filling pipe is arranged at the lower end frame to form a filling body. The filling body is arranged to leave a water storage space. The tailings discharged are collected and mixed with water, and a binder and a water reducing agent are added to form a uniform paste filling body through a stirring device. The paste filling body is filled through the filling pipe.

[0016] Preferably, in step one, the underground space is mined by a pump support pillar filling method. Pump support pillars are arranged in the goaf to support the entire goaf. The pump support pillars are arranged to leave a water storage space, and a tailwater surge chamber is arranged in the goaf.

[0017] Preferably, the pump support pillar filling method comprises the following steps:

[0018] Step 1: Perform geological exploration on the goaf;

[0019] Step 2: Prepare a paste made of tailings mixed with cement and add support pillars according to the size and expected load of the filling area;

[0020] Step 3: Arrange the filling pipe in the mine;

[0021] Step 4: Install the pump station and pump the filling material containing the support pillars into the goaf. First, fill the large space, and then fill the goaf in layers. After each layer is filled, solidify it, and then repeat the above layer-by-layer filling operation.

[0022] Step 5: waterproofing treatment is carried out on all filling columns after solidification of the filling columns is completed;

[0023] Step 6: whether the safety of the filling area meets the design requirements is evaluated, and if not, the filling columns are continuously increased until the design requirements are met.

[0024] Preferably, in step two, a drainage system is arranged on the ground surface, and through the drainage system, the ground surface water is guided into the treated sedimentation tank, coagulant is added to adsorb large particles suspended in the water, preliminary purification is realized through stirring and sedimentation, the upper layer of the preliminarily treated water enters the underground reservoir through the water guide channel of the drainage system, and the lower layer of sludge is discharged through the bottom sludge discharge system of the drainage system.

[0025] Preferably, in step three, the filling mining method in step one is used to construct a reservoir in the underground space, and through the water turbine and generator set equipment, the gravitational potential energy of the ground surface water is converted into electrical energy for storage and connection to the power grid on the mine to provide power.

[0026] Preferably, the water in the reservoir is used for daily use in the mining area after further purification and disinfection treatment, realizing sustainable utilization of water resources.

[0027] A system based on a method of constructing a coal mine underground reservoir based on multiple types of filling mining, comprising a water channel arranged on the ground surface, the water channel being used for ground surface water drainage and storage;

[0028] A drainage system arranged on the ground surface, the drainage system being used for ground surface water transportation, purification and discharge;

[0029] A sedimentation tank arranged in the goaf, the sedimentation tank being used for ground surface water sedimentation treatment;

[0030] The constructed underground space, the underground space comprising a plurality of water storage spaces and a tail water pressure regulating chamber, the plurality of water storage spaces being used for storing treated ground surface water, the plurality of water storage spaces forming a reservoir of the underground space, and the tail water pressure regulating chamber being used for slowing down and adjusting the pressure change of the ground surface water flow.

[0031] The drainage system comprises a ground surface water extraction pipeline, a coagulant adding system, a stirrer, a bottom sludge discharge system and a water guide channel, one end of the ground surface water extraction pipeline is connected with the water channel, the other end of the ground surface water extraction pipeline is connected with the sedimentation tank, the coagulant adding system is used for adding coagulant to the sedimentation tank, the stirrer is used for stirring the sedimentation tank after the coagulant is added, the upper layer of the sedimentation tank is communicated with the water storage space through the water guide channel, and the lower layer of the sedimentation tank discharges sludge through the bottom sludge discharge system.

[0032] The present application has the following beneficial effects:

[0033] 1. The present invention uses three backfill mining methods to support and utilize the filled goaf to form a large storage space, alleviating the problem of resource storage tension and achieving rational utilization of space resources;

[0034] 2. The backfill mining method adopted by this invention is different from traditional single backfill mining. The construction of underground storage based on backfill mining can bring added value to coal mining, thereby reducing the cost of backfill mining, making full use of underground space and alleviating the problem of limited surface storage space.

[0035] 3. The method of the present invention can reduce the subsidence of the ground caused by mining, realize the rational use of space resources, and use the surface subsidence area and the space left by underground filling mining to store water and energy, alleviate the shortage of water resources in the mining area, reduce costs and realize the rational allocation of resources.

[0036] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is a flowchart of the steps of an embodiment of a method for constructing a coal mine underground water reservoir using multi-type backfill mining according to the present invention;

[0038] Figure 2 Schematic diagram of a continuous mining and filling method for short-wall paste according to an embodiment of the present invention;

[0039] Figure 3 Schematic diagram of a fully mechanized mining paste filling method according to an embodiment of the present invention;

[0040] Figure 4 A top view of a pumping pillar-type filling method according to an embodiment of the present invention;

[0041] Figure 5 A schematic diagram of a pumping pillar-type filling method according to an embodiment of the present invention;

[0042] Figure 6 Schematic diagram of underground water storage and energy generation according to an embodiment of the present invention.

[0043] In the picture:

[0044] 1. Upper end frame; 2. Middle frame; 3. Lower end frame; 4. Backfill body; 5. Backfill pipe; 6. Drain pipe; 7. Plastic sheeting; 8. Fabric pipe; 9. Coal seam; 10. Pumping pillar; 11. Goaf; 12. Tailwater surge chamber; 13. Sedimentation tank; 14. Preliminary treated water; 15. Sludge; 16. Underground rock formation; 17. Sludge treatment workshop; 19. Backfill pillar; 20. Water storage space; 21. Section return air level tunnel; 22. Section transport level tunnel. DETAILED DESCRIPTION

[0045] In order to make the purpose, technical solutions and advantages disclosed in the embodiments of the present invention clearer, the embodiments of the present invention are further described in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the embodiments of the present invention and are not intended to limit the embodiments of the present invention. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application. Examples of the embodiments are shown in the accompanying drawings, where the same or similar numbers throughout represent the same or similar elements or elements with the same or similar functions.

[0046] It should be noted that the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or server that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units that are not explicitly listed or are inherent to these processes, methods, products or devices.

[0047] Like reference numerals and letters denote like items in the following drawings, and thus, once an item is defined in one drawing, it does not require further definition or explanation in subsequent drawings.

[0048] In the description of the present invention, it should be noted that the terms "upper", "lower", "inside", "outside", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, or are the orientations or positional relationships in which the inventive product is usually placed when in use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they should not be understood as limiting the present invention.

[0049] In the description of the present invention, it should also be noted that, unless otherwise expressly specified or limited, the terms "disposed," "installed," and "connected" should be understood broadly. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0050] like Figure 1 As shown, the method and system for constructing a coal mine underground water reservoir through multi-type backfilling mining described in the present invention is a method for storing surface water in coal mining subsidence areas, continuously mining and backfilling coal mines, and utilizing underground space. This method utilizes the characteristics of easy flow of water in the goaf 11, good water storage capacity of the goaf 11, and the infiltration and dispersion of surface water to replenish groundwater, to carry out "mining-backfilling-underground space" construction. The specific steps include:

[0051] Step 1: Select the best filling mining method from the three methods of short-wall paste continuous mining and filling, fully mechanized paste filling, and pumped pillar filling according to the different mining areas;

[0052] Determining whether a coal mine can adopt partial-fill mining requires consideration of multiple factors, including geological conditions, orebody properties, mining techniques, and environmental impacts. Partial-fill mining is a mining method designed to reduce surface subsidence and increase coal recovery, but it is not suitable for all coal mines. Factors that may need to be considered include the stability and suitability of the coal mine, the inclination, lithology, orebody thickness, and hydrogeological effects. Before considering partial-fill mining, detailed exploration and engineering feasibility studies are required to ensure that the selected mining method is suitable for the mine's specific conditions.

[0053] By adopting the method of continuous mining and filling, that is, implementing interval filling while coal mining is in progress, it is possible to utilize the abandoned space when the coal seam 9 is mined to form the goaf 11, creating the possibility of creating a large underground storage space, and using the coal mining subsidence area as a sedimentation pond 13. Figure 2 As shown, several groups of filling pillars 19 are spaced apart. These pillars are constructed from a combination of basic structural filling materials and specialized functional anti-seepage and sealing materials to ensure the stability and permeability of the filling body 4 and provide support for the storage space. The upper side of the filling pillars 19 serves as a section transport lane 22, while the lower side serves as a section return air lane 21. The empty lanes between adjacent filling pillars 19 serve as water storage spaces 20 for individual units. After mining is complete, the section return air lanes 21 serve as tailwater surge chambers 12 for all units.

[0054] The continuous mining and charging method includes the following steps:

[0055] Step 1: Based on the actual project situation, plan the interval mining tunnels and filling tunnels to meet the requirements of interval mining and filling to leave 20 water storage spaces;

[0056] Step 2: Use a coal cutter to cut the coal seam. The crusher breaks the cut coal into smaller pieces, and the loader loads the crushed coal into transportation equipment;

[0057] Step 3: First, the tunnel that needs to be filled is mined. After the tunnel is mined, the basic structural filling materials and specific functional anti-seepage and sealing materials are pumped into the goaf 11;

[0058] Step 4: After the filling body is stable and meets the stability and anti-permeability requirements, the tunnel serving as the water storage space 20 is mined;

[0059] Step 5: Set up a tailwater surge chamber in the water storage space 20 to monitor and regulate the reservoir.

[0060] Advantages: ① High coal mining rate ② 20 water storage space and high safety ③ Low later maintenance cost.

[0061] like Figure 3 As shown, through fully mechanized mining, the fully mechanized paste filling method is used. During the fully mechanized mining process, an upper head frame 1, an intermediate frame 2, a lower head frame 3, a drainage pipe 6, a filling pipe 5, a plastic sheet 7, and a distribution pipe 8 are pre-installed. After the fully mechanized mining is completed, the filling body 4 is filled through the filling pipe 5 to create a water storage space 20. The upper head frame 1, several intermediate frames 2, and the lower head frame 3 are sequentially connected and arranged in the goaf 11. The upper head frame 1, the intermediate frames 2, and the lower head frame 3 support equipment such as coal mining machines and conveyors, and guide these machines to move forward smoothly; the drainage pipe 6 is arranged behind the upper head frame 1 to promptly discharge wastewater during the mining process; the distribution pipe 8 is arranged below the intermediate frame 2 to promptly transport the mined coal; the filling pipe 5 is arranged on the lower head frame 3, and is promptly filled as the mining progresses, ensuring the temporal continuity of the underground space construction. The filling pipe 5 is used to form a filling body 4, and a water storage space 20 is left between the filling bodies 4. This method can be implemented immediately after the comprehensive mining is completed, and since most of the facilities are installed during the mining process, the time for reservoir construction can be greatly shortened; the transported tailings are recovered, and the tailings are mixed with water in a certain proportion, and an appropriate amount of adhesive (such as cement) and water reducer and other additives are added. A uniform paste is made through existing mixing equipment, and finally filled through the filling pipe 5.

[0062] Advantages: ① The mining, filling and reservoir construction are continuous in time and space, and the construction period is short. ② The mining efficiency is high. ③ The 20-degree rule of water storage space is convenient for management.

[0063] The pumping pillar filling method is adopted, and the pumping pillars 10 are arranged in the goaf 11 to support the entire goaf 11. Figure 4 、 Figure 5 As shown, a water storage space 20 is provided between the pumping supports 10, and a tailwater surge chamber 12 is installed in the goaf 11. The tailwater surge chamber 12 is used to mitigate and regulate water pressure fluctuations, ensuring a smooth return of water to the underground reservoir, thereby improving the safety and efficiency of the hydropower station's operation. This method is simple and efficient, facilitating later facility construction in the goaf 11. The filling material space occupies a low percentage, improving the utilization rate of the water storage space 20. However, the reservoir structure is less stable than the previous two methods, requiring geological surveys of the mining area.

[0064] The pumping pillar filling method includes the following steps:

[0065] Step 1: Conduct geological exploration of the goaf 11, and ensure that the floor meets strength and water-resistance requirements;

[0066] Step 2: Prepare the paste made of tailings mixed cement or other binding agent according to the size and expected load of the filling area, and add the support pillars (wood, steel or mixed material) of appropriate size and quantity;

[0067] Step 3: Place the filling pipes 5 in the mine, and make sure that the filling pipes 5 can reach all the predetermined filling areas and have the necessary outlets to distribute the filling material;

[0068] Step 4: Install the pump station at a suitable location to pump the filling material containing the support pillars to the goaf 11, first filling the large space to ensure that the bottom and edges are fully supported. Perform the filling in layers within the goaf 11, and after each layer of filling, allow a certain time for solidification, and after solidification, continue to repeat the above-mentioned layering and filling operation;

[0069] Step 5: After the filling support pillars 19 are fully solidified, perform waterproofing treatment on all the filling support pillars 19;

[0070] Step 6: Evaluate whether the safety of the filling area meets the design requirements; if not, continue to add filling support pillars 19 until the design requirements are met.

[0071] Advantages: ① Low cost ② Short construction period, less engineering quantity ③ Large water storage space 20 ④ High coal recovery rate.

[0072] Step 2: Lay out the drainage system on the ground, which includes surface water pumping pipeline, coagulant dosing system, mixer, bottom sludge discharge system, and water diversion channel. As shown in Figure 6 , through the surface water pumping pipeline, surface water is introduced into the treated coal mining subsidence area (sedimentation tank 13), coagulant is added to adsorb large particles suspended in water, and after stirring and sedimentation, preliminary purification is achieved. The upper layer of preliminary treated water 14 enters the underground reservoir through the water diversion channel in the underground rock layer 16, and the lower layer of sludge 15 is discharged through the bottom sludge discharge system and transported to the sludge treatment workshop 17.

[0073] Step 3: First, the construction of the reservoir in the underground space can maximize the reduction of surface area occupation, slow down the surface subsidence, and improve the safety and stability of the reservoir. Then, through devices such as water turbines and generator sets, the gravitational potential energy of surface water is converted into electrical energy, which is stored and connected to the power grid on the mine to provide power. At the same time, the settled water is stored and used for daily use in the mining area after further purification and disinfection treatment, realizing sustainable use of water resources. Self-suction water devices can also be used to suck water into the underground space from the main stream of the Yellow River during the low electricity consumption period, achieving water storage and energy storage, serving as a means of power peak shaving, and improving the efficiency of electrical energy utilization.

[0074] The drainage system and self-suction water device are all based on the existing mechanisms on the mine.

[0075] The method for constructing the coal mine underground reservoir based on the multi-type filling mining comprises a water channel arranged on the ground surface, and the water channel is used for surface water drainage and storage.

[0076] A drainage system arranged on the ground surface is used for surface water transportation, purification and discharge.

[0077] A sedimentation tank arranged in the goaf is used for surface water sedimentation treatment.

[0078] The constructed underground space comprises a plurality of water storage spaces and a tail water pressure regulating chamber, the plurality of water storage spaces are used for storing the treated surface water, the plurality of water storage spaces form a reservoir of the underground space, and the tail water pressure regulating chamber is used for slowing down and adjusting the pressure change of the surface water flow.

[0079] The drainage system comprises a surface water pumping pipeline, a coagulant adding system, a stirrer, a bottom sludge discharge system and a water guide channel, one end of the surface water pumping pipeline is connected with the water channel, the other end of the surface water pumping pipeline is connected with the sedimentation tank, the coagulant adding system is used for adding coagulant into the sedimentation tank, the stirrer is used for stirring the sedimentation tank after the coagulant is added, the upper layer of the sedimentation tank is communicated with the water storage space through the water guide channel, and the lower layer of the sedimentation tank is discharged through the bottom sludge discharge system.

[0080] Therefore, the method and the system for constructing the coal mine underground reservoir based on the multi-type filling mining are adopted, the settlement caused by mining to the ground surface is reduced, the rational utilization of space resources is realized, the space left by the surface subsidence area and the underground filling mining is used for water storage and energy storage, the water resource tension in the mining area is relieved, the cost is reduced, and the rational distribution of resources is realized.

[0081] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application rather than limiting them, although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can still be modified or replaced by equivalents, and these modifications or equivalent replacements cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present application.

Claims

1. A method for constructing a coal mine underground water reservoir by multi-type backfill mining, characterized by: The following steps are involved: Step 1: Based on the geological conditions of the mining area, the properties of the ore body, the mining process, and environmental impacts, the best method is selected from three filling mining methods: short-wall paste continuous mining and filling, fully mechanized mining paste filling, and pumped pillar filling. Step 2: Set up a drainage system on the surface and guide the surface water to the sedimentation tank; Step three: Build a power generation reservoir in the underground space, divert surface water into the reservoir, and convert the gravitational potential energy of the surface water into electricity to provide power for the mine power grid; In step 1, the underground space is filled in intervals by a short-wall paste continuous mining and filling method. The short-wall paste continuous mining and filling method includes the following steps: Step 1: Based on the actual project situation, plan the tunnels for interval mining and filling, and leave water storage space for interval mining and filling; Step 2: Use a coal cutter to cut the coal seam, use a crusher to break the cut coal blocks, and then use a loader to load the crushed coal into the transportation equipment; Step 3: Mining the tunnels that need to be filled. After the tunnels are mined, the basic structural filling materials and anti-seepage and sealing materials are pumped into the goaf; Step 4: After the filling body is stable and meets the requirements of stability and anti-permeability, the tunnel used as water storage space is mined; Step 5: Set up a tailwater surge chamber in the water storage space to monitor and regulate the reservoir; In step 1, the underground space is mined by fully mechanized mining and the paste filling method is used. During the mining process, an upper head frame, an intermediate frame, a lower head frame, a drainage pipe, a filling pipe, and a distribution pipe are pre-set in the goaf. The upper head frame, several intermediate frames, and the lower head frame are sequentially connected and arranged in the goaf to support the coal mining machine and the conveyor and guide them forward. The drainage pipe is arranged behind the upper head frame to discharge wastewater during the mining process. The distribution pipe is arranged below the intermediate frame to transport the mined coal. The filling pipe is arranged at the lower head frame to form a filling body. Water storage space is left between the filling bodies. The transported tailings are recovered, mixed with water, and a binder and a water reducer are added. A uniform paste filling body is made through a stirring device and filled through the filling pipe. In step one, a pumping pillar filling method is used to mine underground space. Pumping pillars are arranged in the goaf to support the entire goaf. Water storage space is left between the pumping pillars, and a tail water pressure regulating chamber is set in the goaf.

2. The method for constructing a coal mine underground water reservoir by multi-type backfill mining according to claim 1, characterized in that: The pumping pillar filling method includes the following steps: Step 1: Conduct geological exploration of the mined-out area; Step 2: Prepare a paste made of tailings mixed with cement and add pillars according to the size of the filling area and the expected load; Step 3: Arrange the filling pipe in the mine; Step 4: Install a pump station and pump the filling material containing the pillars into the goaf. First fill the large space, then fill it layer by layer in the goaf. After each layer is filled, solidify it. After solidification, repeat the above layered filling operation. Step 5: After the filling columns are solidified, all filling columns are waterproofed; Step 6: Evaluate whether the safety of the filling area meets the design requirements. If not, continue to add filling columns until the design requirements are met.

3. The method for constructing a coal mine underground water reservoir by multi-type backfill mining according to claim 2, characterized in that: In step 2, a drainage system is arranged on the surface. Through the drainage system, surface water is introduced into a treated sedimentation tank, and coagulants are added to adsorb large particles suspended in the water. After stirring and sedimentation, preliminary purification is achieved. The upper layer of preliminarily treated water enters the underground reservoir through the drainage system's water diversion channel, and the lower layer of sludge is discharged through the bottom sludge discharge system of the drainage system.

4. The method for constructing a coal mine underground water reservoir by multi-type backfill mining according to claim 3, characterized in that: In step three, a reservoir is built in the underground space using the backfill mining method in step one. The gravitational potential energy of the surface water is converted into electrical energy and stored through turbines and generator sets, and then connected to the power grid on the mine to provide electricity.

5. The method for constructing a coal mine underground water reservoir by multi-type backfill mining according to claim 4, characterized in that: The water in the reservoir is further purified and disinfected before being used for daily use in the mining area, achieving sustainable use of water resources.

6. A system for constructing a coal mine underground water reservoir based on multi-type backfill mining according to any one of claims 1 to 5, characterized in that: It includes channels set on the surface for the drainage and storage of surface water; Drainage system installed on the surface, used for conveying, purifying and discharging surface water; Settlement tanks are installed in goaf areas and are used for surface water sedimentation treatment; The underground space is constructed, which includes several water storage spaces and tailwater surge chambers. Several water storage spaces are used to store treated surface water. Several water storage spaces form reservoirs in the underground space. The tailwater surge chamber is used to slow down and regulate the pressure changes of surface water flows.

7. The system for constructing a coal mine underground water reservoir based on multi-type backfill mining according to claim 6, characterized in that: The drainage system includes a surface water extraction pipeline, a coagulant dosing system, an agitator, a bottom sludge discharge system, and a water diversion channel. One end of the surface water extraction pipeline is connected to the water diversion channel, and the other end of the surface water extraction pipeline is connected to the sedimentation tank. The coagulant dosing system is used to add coagulant to the sedimentation tank. The agitator stirs the sedimentation tank after the coagulant is added. The upper layer of the sedimentation tank is connected to the water storage space through the water diversion channel, and the sludge in the lower layer of the sedimentation tank is discharged through the bottom sludge discharge system.

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