Downhole treatment method for coal mine water

Abstract

A downhole treatment method for coal mine water. By means of the method, mine water is purified downhole; the mine water is preliminarily purified by using a first goaf (60) located in front of a stope working surface (50) where stoping is being performed; and a concentrated brine is sealed by using a second goaf (60) located in front of a stope working surface (50) where stoping is being performed. A water treatment device is placed in an existing downhole roadway chamber, such that no ground land is occupied; the mine water treatment cost is reduced by using the self-purification effect of fallen rock mass in the goaf (60); and the deep-treated concentrated brine can be stored in a suitable goaf (60), thereby avoiding the risk of solid waste pollution caused by crystalline salt generated after crystallization and evaporation.

Description

A method for treating coal mine water underground

[0001] This application claims priority to Chinese patent application No. 202310953033.7, filed on July 31, 2023, and all disclosed contents of that application are incorporated herein by reference. Technical Field

[0002] The present invention relates to the technical field of coal mining and mine water treatment, and in particular to an underground treatment method for coal mine water. Background Art

[0003] Mine water is produced during the coal mining process. After treatment, most of the mine water can be reused, and the wastewater (concentrated brine) produced needs to be specially treated or sealed.

[0004] Traditional mine water treatment processes usually adopt surface treatment methods, which are treated through conventional ground water treatment facilities. Some mine water that meets the reuse standards is returned to the mine for reuse. The surface treatment method has disadvantages such as large infrastructure investment, high mine water lifting and operating costs, and large land area.

[0005] Summary of the Invention

[0006] The purpose of the present invention is to overcome the shortcomings of the existing technology and provide a new underground treatment method for coal mine water, which purifies the mine water underground, uses the first goaf in front of the mining work to preliminarily purify the mine water, uses the second goaf in front of the mining work to seal the concentrated brine, uses the existing tunnels and chambers underground to place water treatment equipment, does not occupy the ground land, uses the self-purification effect of the fallen rock mass in the goaf, reduces the mine water treatment cost, and the deeply treated concentrated brine can be stored in a suitable goaf to avoid the risk of solid waste pollution caused by the crystallized salt produced after crystallization and evaporation.

[0007] The technical solution of the present invention provides a method for treating coal mine water underground, comprising the following steps:

[0008] S01: Excavation to form tunnels, underground water tanks and vertical shafts;

[0009] S02: along the direction of the roadway extension, a plurality of strip-shaped mining working faces are sequentially divided and labeled as No. 1 mining working face, No. 2 mining working face, ... No. n mining working face. Correspondingly, the goafs formed after subsequent mining are sequentially named No. 1 goaf, No. 2 goaf, ... No. n goaf, where n is a positive integer greater than or equal to 3;

[0010] S03: Mining is carried out in sequence from No. 1 mining face to No. n mining face, and the mine water generated during the mining process of each mining face is temporarily stored in an underground water tank;

[0011] Among them, before the No. 2 mining face was mined, a mine water purification system was built in the tunnel;

[0012] S04: During the mining process from No. 3 mining face to No. n mining face:

[0013] The mine water temporarily stored in the underground water tank is led to the first goaf before the mining working face for preliminary purification, and the preliminarily purified mine water is transported to the mine water purification treatment system for purification treatment. The mine water obtained after purification by the mine water purification treatment system is led out for use through pipelines;

[0014] The concentrated brine produced after treatment by the mine water purification system is led to the second goaf before the mining working face and sealed.

[0015] In one of the optional technical solutions, step S04 includes:

[0016] After the formation of goaf No. 2 and when mining the goaf No. 3, the mine water temporarily stored in the underground water tank is led to goaf No. 2 through a pipeline for preliminary purification. The mine water after preliminary purification in goaf No. 2 is led to the mine water purification treatment system through a pipeline for purification treatment. The mine water obtained after purification by the mine water purification treatment system is led out through a pipeline for use. The concentrated brine produced after treatment by the mine water purification treatment system is led to goaf No. 1 through a pipeline;

[0017] After the formation of goaf No. 3 and when mining working face No. 4 is mined, goaf No. 1 is sealed, and the mine water temporarily stored in the underground water tank is led to goaf No. 3 through a pipeline for preliminary purification. The concentrated brine produced after treatment by the mine water purification system is led to goaf No. 2 through a pipeline, and so on, until mining working face No. n is mined.

[0018] In one of the optional technical solutions, after mining the No. n mining face, the following steps are also included:

[0019] The mine water temporarily stored in the underground water tank is led to the No. n goaf through a pipeline for preliminary purification. The concentrated brine produced after treatment by the mine water purification system is led to the No. n-1 goaf through a pipeline. After the first preset time, the No. n-1 goaf is sealed.

[0020] In one of the optional technical solutions, after sealing the n-1 goaf, the following steps are also included:

[0021] The mine water temporarily stored in the underground water tank is led to the mine water purification system through pipelines;

[0022] The concentrated brine produced after being treated by the mine water purification system is led to goaf No. n through a pipeline. After a second preset time, goaf No. n is sealed.

[0023] In one of the optional technical solutions, step S04 includes: the mine water after preliminary purification in the goaf is led to the surface through a pipeline for production reuse.

[0024] In one of the optional technical solutions, the mine water that has been initially purified in the goaf is led through a pipeline to a coal washing plant for use in coal washing; and / or, the mine water that has been initially purified in the goaf is led through a pipeline to a coal-fired power plant for use in machine cooling.

[0025] In one of the optional technical solutions, the mine water purification system includes a primary purification system, a secondary purification system and a tertiary purification system;

[0026] The mine water after preliminary purification in the goaf is led to the primary purification treatment system through pipelines;

[0027] The mine water purified by the primary purification system is led to the secondary purification system through pipelines;

[0028] The mine water purified by the secondary purification system is led to the tertiary purification system through pipelines;

[0029] The mine water purified by the three-stage purification system is led to the surface through pipes for domestic use, and the concentrated brine obtained after purification by the three-stage purification system is led to the second goaf before the mining face being mined and sealed.

[0030] In one of the optional technical solutions, part of the mine water purified by the primary purification system is also led through a pipeline to the mining face for cooling the machines and spraying out dust removal.

[0031] In one of the optional technical solutions, part of the mine water purified by the secondary purification system is also led to an above-ground reservoir through a pipeline for irrigation.

[0032] In one of the optional technical solutions, the mine water purified by the three-stage purification system is led to the water plant through a pipeline.

[0033] The above technical solution has the following beneficial effects:

[0034] The underground treatment method of coal mine water provided by the present invention purifies the mine water underground, starting from the No. 3 mining face, using the first goaf in front of the mining face being mined to preliminarily purify the mine water, and using the second goaf in front of the mining face being mined to seal the concentrated brine. During the mining process of each mining face, there is always a goaf for preliminarily purifying the mine water and there is always a goaf for sealing the concentrated brine, and the goaf used for preliminarily purifying and the goaf used for sealing the concentrated brine are also replaced in sequence, so that all goafs are available, ensuring that all the concentrated brine can be stored.

[0035] The underground treatment method for coal mine water provided by the present invention utilizes existing tunnels and chambers underground to place water treatment equipment without occupying ground land. It utilizes the self-purification effect of the fallen rock mass in the goaf to reduce the cost of mine water treatment. The deeply treated concentrated brine can be stored in a suitable goaf to avoid the risk of solid waste pollution caused by the generation of crystalline salt after crystallization and evaporation. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The disclosure of the present invention will become more easily understood with reference to the accompanying drawings. It should be understood that these drawings are for illustrative purposes only and are not intended to limit the scope of protection of the present invention. In the drawings:

[0037] FIG1 is a schematic diagram of the steps of an underground method for treating coal mine water provided by one embodiment of the present invention;

[0038] Figure 2 is a schematic diagram of using goaf No. 1 to store concentrated brine and using goaf No. 2 for preliminary filtration when mining the No. 3 mining face. DETAILED DESCRIPTION

[0039] The following further describes specific embodiments of the present invention with reference to the accompanying drawings. Like components are denoted by like reference numerals. It should be noted that the terms "front," "rear," "left," "right," "up," and "down" used in the following description refer to directions in the accompanying drawings, and the terms "inward" and "outward" refer to directions toward or away from the geometric center of a particular component, respectively.

[0040] As shown in FIG1-2 , an underground treatment method for coal mine water provided by an embodiment of the present invention includes the following steps:

[0041] S01: Excavation forms a tunnel 10, an underground water tank 20 and a vertical shaft 30.

[0042] S02: Along the direction of extension of the tunnel, a plurality of strip-type mining working faces 50 are divided in sequence and marked as mining working face No. 1, mining working face No. 2... mining working face No. n. Correspondingly, the goaf 60 formed after subsequent mining are named goaf No. 1, goaf No. 2... goaf No. n, where n is a positive integer greater than or equal to 3.

[0043] S03: Mining is carried out in sequence from No. 1 mining face to No. n mining face. The mine water generated during the mining of each mining face 50 is temporarily stored in the underground water tank 20 .

[0044] Among them, before the No. 2 mining working face is mined, a mine water purification system 40 is built in the tunnel 10.

[0045] S04: During the mining process from No. 3 mining face to No. n mining face:

[0046] The mine water temporarily stored in the underground water tank 20 is led to the first goaf 60 in front of the mining working face 50 being mined for preliminary purification, and the mine water after preliminary purification is transported to the mine water purification treatment system 40 for purification treatment. The mine water obtained after purification by the mine water purification treatment system 40 is led out for use through a pipeline.

[0047] The concentrated brine produced after being processed by the mine water purification system 40 is led to a second goaf 60 located before the mining working face 50 being mined and sealed.

[0048] The underground treatment method of coal mine water provided by the present invention can treat, classify and utilize the mine water while coal is being mined.

[0049] Specifically, the steps include:

[0050] Step 1: Initial preparation work, excavating to form a tunnel 10, an underground water tank 20, and a vertical shaft 30. The underground water tank 20 is an underground chamber. Multiple underground chambers can be used to construct multiple underground water tanks 20 as needed. A water system will be built outside the underground water tank 20, including a water pump, a control system, a pipeline 70, etc., which is used to guide the mine water or production wastewater generated by the mining working face 50 to the underground water tank 20 for temporary storage, and also to transport the mine water in the underground water tank 20 to a goaf 60 for preliminary purification using fallen rock. The water pump, control system, pipeline 70, etc. are conventionally arranged and will not be described in detail here.

[0051] The vertical shaft 30 connects the ground surface with the tunnel 10 and is used for arranging the pipeline 70.

[0052] Step 2: Preparation work before mining. Coal mining adopts a strip mining method. Along the length direction of the roadway 10, a plurality of spaced mining faces 50 are divided in sequence. The mining direction of the mining face 50 is roughly perpendicular to the roadway 10. For the convenience of description, along the direction from one end of the roadway 10 to the vertical shaft 30, the plurality of mining faces 50 are marked as No. 1 mining face, No. 2 mining face... No. n mining face, which is a positive integer greater than or equal to 3. Also for the convenience of description, according to the sequence number of the mining face 50, the goaf 60 formed after subsequent mining are named No. 1 goaf, No. 2 goaf... No. n goaf. After each goaf 60 is formed, the opening connected to the roadway 10 is blocked to form an underground water reservoir for filtering mine water and sealing the underground water reservoir. In the subsequent description, the mined-out areas used for filtration and sealing are all underground reservoirs, that is, mined-out area No. 1, mined-out area No. 2... mined-out area No. n correspond to underground reservoir No. 1, underground reservoir No. 2... underground reservoir No. n.

[0053] Step 3: The mining face 50 begins mining, specifically in the order from mining face No. 1 to mining face No. n. When mining each mining face 50, the pipe 70 of the underground water tank 20 is connected to the water outlet (e.g., water storage ditch / trough) of each mining face 50, so as to lead the mine water generated during the mining of each mining face 50 into the underground water tank 20 for temporary storage in the underground water tank 20. For example, the mine water generated during the mining of mining face No. 1 is temporarily stored in one or more underground water tanks 20, the mine water generated during the mining of mining face No. 2 is also temporarily stored in one or more underground water tanks 20, and the mine water generated during the subsequent mining of mining faces No. 3, No. 4...n is first temporarily stored in one or more underground water tanks 20. Starting from the No. 3 mining face, the mine water in the underground water tank 20 begins to be transported to the goaf 60, and the mine water is preliminarily purified through the goaf 60.

[0054] Before mining the No. 2 mining face, a mine water purification system 40 needs to be constructed in the tunnel 10. The mine water purification system 40 is constructed in one or more chambers on one side of the tunnel 10. The mine water purification system 40 is used to further purify the mine water that has been initially purified in the goaf 60, producing reusable mine water and wastewater (concentrated brine) that needs to be sealed. The mine water purification system 40 can utilize a combination of an ultrafiltration purification system, a reverse osmosis purification system, and a membrane distillation purification system.

[0055] Step 4: During the mining process from No. 3 mining face to No. n mining face, the mine water purification treatment method is as follows:

[0056] With the active mining face 50 as a reference, the water supply pipe 70 of the underground water tank 20 is connected to the higher elevation of the first goaf 60 before the active mining face 50. Mine water injected into this goaf flows by gravity to the lower elevation. During this flow, the self-purification effect of the fallen rock mass in the goaf removes large particles, fine suspended matter, and soluble organic matter from the mine water, achieving preliminary purification of the mine water. Currently, the first goaf 60 before the active mining face 50 is referred to as the mine water pretreatment goaf / underground water reservoir.

[0057] Mine water, filtered after pre-treatment in the goaf / underground reservoir, is then directed to the mine water purification system 40 via pipeline 70 for purification. The mine water purification system 40 is equipped with a corresponding water pump, control system, pipeline 70, and other components, which are conventional and will not be described in detail here. The control system of the mine water purification system 40 can be integrated with the control system of the underground water tank 20.

[0058] The usable mine water obtained after being treated and purified by the mine water purification system 40 is led out through the pipeline 70 for reuse. For example, it is led through the pipeline 70 to the mining face 50 for machine cooling and dust removal, and is led out through the vertical shaft 30 through the pipeline 70 for surface irrigation and domestic use.

[0059] After deep purification by the mine water purification system 40, wastewater, also known as concentrated brine, is produced. This brine is piped to a second goaf 60 located before the active mining face 50 for storage. Currently, the second goaf 60 located before the active mining face 50 is referred to as the concentrated brine storage goaf / underground reservoir.

[0060] To sum up, the underground treatment method of coal mine water provided by the present invention purifies the mine water underground, starting from the No. 3 mining face, and uses the first goaf in front of the mining face being mined to preliminarily purify the mine water, and uses the second goaf in front of the mining face being mined to seal the concentrated brine. During the mining process of each mining face, there is always a goaf for preliminarily purifying the mine water, and there is always a goaf for sealing the concentrated brine, and the goaf used for preliminary purification and the goaf used for sealing the concentrated brine are also replaced in sequence, so that all goafs are available, ensuring that all concentrated brine can be stored.

[0061] With the continuous injection of mine water, the self-purification effect of the rockfall in the goaf 60, which serves as the initial filtration function, will weaken, and the concentrated brine stored in the goaf 60, which serves as the sealing function, will also tend to be saturated. As underground mining activities proceed, subsequent mining faces will be gradually completed, forming new goaf 60. The newly formed goaf 60 can be used as mine water pretreatment goaf / groundwater reservoir. Goaf 60 where the self-purification effect has been significantly weakened can be used as concentrated brine sealing goaf / groundwater reservoir for permanent storage of concentrated brine.

[0062] The underground treatment method for coal mine water provided by the present invention utilizes existing tunnels and chambers underground to place water treatment equipment without occupying ground land. It utilizes the self-purification effect of the fallen rock mass in the goaf to reduce the cost of mine water treatment. The deeply treated concentrated brine can be stored in a suitable goaf to avoid the risk of solid waste pollution caused by the generation of crystalline salt after crystallization and evaporation.

[0063] In one embodiment, as shown in FIG1-2 , step S04 includes:

[0064] After the formation of goaf No. 2 and when mining the No. 3 mining face, the mine water temporarily stored in the underground water tank 20 is led to goaf No. 2 through pipeline 70 for preliminary purification. The mine water after preliminary purification in goaf No. 2 is led to the mine water purification treatment system 40 through pipeline 70 for purification treatment. The mine water obtained after purification by the mine water purification treatment system 40 is led out for use through pipeline 70, and the concentrated brine produced after treatment by the mine water purification treatment system 40 is led to goaf No. 1 through a pipeline.

[0065] After the formation of goaf No. 3 and when mining working face No. 4 is mined, goaf No. 1 is sealed, and the mine water temporarily stored in the underground water tank 20 is led to goaf No. 3 through a pipeline for preliminary purification. The concentrated brine produced after treatment by the mine water purification treatment system 40 is led to goaf No. 2 through a pipeline, and so on, until mining working face No. n is mined.

[0066] In this embodiment, taking the mining of the No. 3 working face as an example, the mine water in the underground water tank 20 is diverted to the No. 2 goaf for preliminary purification. The No. 2 goaf is now the mine water pretreatment goaf / underground reservoir. After preliminary purification in the No. 2 goaf, the mine water is diverted to the mine water purification system 40 for further purification. The resulting mine water is then diverted for reuse via pipeline 70. The resulting concentrated brine is then diverted via pipeline 70 to the No. 1 goaf. The concentrated brine in the No. 1 goaf is now stored in the goaf / underground reservoir.

[0067] Taking the No. 4 mining face as an example, the No. 1 goaf is sealed, the No. 2 goaf is used to seal the concentrated brine, and the No. 3 goaf is used to preliminarily purify the mine water.

[0068] Taking the No. 5 mining face as an example, the No. 2 goaf is sealed, the No. 3 goaf is used to seal the concentrated brine, and the No. 4 goaf is used to preliminarily purify the mine water.

[0069] Taking the No. 6 mining face as an example, the No. 3 goaf is sealed, the No. 4 goaf is used to seal the concentrated brine, and the No. 5 goaf is used to preliminarily purify the mine water.

[0070] And so on, until the mining face No. n is mined.

[0071] Starting from the third mining face, during the mining process of each mining face, there will always be a goaf for preliminary purification of mine water, and there will always be a goaf for storing concentrated brine. The goaf used for preliminary purification and the goaf used for storing concentrated brine will also be replaced in sequence, so that all goafs can be utilized, ensuring that all concentrated brine can be stored.

[0072] With the continuous injection of mine water, the self-purification effect of the caving rock mass in goaf No. 2 will weaken, and the concentrated brine stored in goaf No. 1 will also become saturated. As underground mining activities continue, mining will be completed in succession at the No. 3, No. 4, No. 5, and No. 6 mining faces, forming new goafs 60. These newly formed goafs 60 can be used as mine water pretreatment goafs / groundwater reservoirs. Goafs 60, where the self-purification effect has been significantly weakened, can be used as concentrated brine storage goafs / groundwater reservoirs for permanent storage of concentrated brine.

[0073] In one embodiment, after mining the No. n mining face, the method further includes:

[0074] The mine water temporarily stored in the underground water tank 20 is led to the No. n goaf through the pipeline 70 for preliminary purification. The concentrated brine produced after treatment by the mine water purification system 40 is led to the No. n-1 goaf through the pipeline 70. After the first preset time, the No. n-1 goaf is sealed.

[0075] In this embodiment, after the last mining face 50 is mined, the second-to-last goaf 60 is used to seal the concentrated brine, and the last goaf 60 is used to perform preliminary filtration on the mine water stored in the underground water tank 20. After the filtration of the mine water stored in the underground water tank 20 is completed, the second-to-last goaf 60 is sealed.

[0076] In one embodiment, after sealing the n-1 goaf, the method further includes:

[0077] The mine water temporarily stored in the underground water tank 20 is led to the mine water purification system 40 through the pipeline 70.

[0078] The concentrated brine produced after being processed by the mine water purification system 40 is led to the goaf No. n through the pipeline 70. After the second preset time, the goaf No. n is sealed.

[0079] In this embodiment, after the second-to-last goaf 60 is sealed, mine water will still gather in the underground water tank 20. At this time, the mine water in the underground water tank 20 is directly led to the mine water purification treatment system 40. The usable mine water filtered by the mine water purification treatment system 40 is led to the ground through a pipe 70 for reuse. The concentrated brine produced after treatment by the mine water purification treatment system 40 is led to the last goaf 60 through a pipe 70. After a second preset time (for example, mine water is no longer gathered in the underground water tank 20 or the mining of the area is completed and the area needs to be replaced), the last goaf 60 is sealed to seal the concentrated brine underground.

[0080] In one embodiment, as shown in FIG2 , step S04 includes: After preliminary purification in goaf 60, the mine water is led to the surface via pipeline 70 for reuse in production. The mine water initially purified in goaf 60 meets the cooling, quenching, and washing requirements of surface plants and can be directly reused without further purification in mine water purification system 40.

[0081] In one embodiment, the mine water initially purified in goaf 60 is led through pipeline 70 to a coal washing plant for coal washing. Alternatively, the mine water initially purified in goaf 60 is led through pipeline 70 to a coal-fired power plant for machine cooling.

[0082] In one embodiment, as shown in FIG2 , the mine water purification system 40 includes a primary purification system 401 , a secondary purification system 402 , and a tertiary purification system 403 .

[0083] The mine water that has been preliminarily purified in the goaf 60 is led to the primary purification system 401 through the pipeline 70 .

[0084] The mine water purified by the primary purification system 401 is led to the secondary purification system 402 through the pipeline 70.

[0085] The mine water purified by the secondary purification system 402 is led to the tertiary purification system 403 through the pipeline 70.

[0086] The mine water purified by the tertiary purification system 403 is led to the surface through a pipe 70 for domestic use, and the concentrated brine obtained after purification by the tertiary purification system 403 is led to the second goaf 60 before the mining working face 50 being mined for storage.

[0087] In this embodiment, mine water purification system 40 employs a three-stage filtration system, comprising a primary purification system 401, a secondary purification system 402, and a tertiary purification system 403. Primary purification system 401 is an ultrafiltration purification system, secondary purification system 402 is a reverse osmosis purification system, and tertiary purification system 403 is a membrane distillation purification system. Primary purification system 401, secondary purification system 402, and tertiary purification system 403 can be housed in three separate chambers.

[0088] The filtration effects of the primary purification system 401, the secondary purification system 402 and the tertiary purification system 403 are improved in sequence, and their combined use improves the filtration effect. The concentrated brine is separated by the tertiary purification system 403.

[0089] In one embodiment, as shown in FIG2 , a portion of the mine water purified by the primary purification system 401 is also led by a pipeline 70 to the mining face 50 for machine cooling and dust removal, and the mine water purified by the primary purification system 401 is classified and utilized.

[0090] In one embodiment, as shown in FIG2 , a portion of the mine water purified by the secondary purification system 402 is also led to an above-ground reservoir via a pipeline 70 for irrigation, and the mine water purified by the secondary purification system 402 is classified and utilized.

[0091] In one embodiment, the mine water purified by the tertiary purification system 403 is led to the water plant through the pipeline 70, and the mine water purified by the tertiary purification system 403 is classified and utilized.

[0092] The present invention proposes a graded and quality-based utilization approach for mine water after different treatment stages, based on the different requirements for production, ecological and domestic water use above and below the ground in mining areas: the mine water after pre-treatment and filtration in the goaf can be used in surface coal washing plants; the mine water after primary treatment can be used for cooling and dust removal in underground coal mine production; the mine water after secondary treatment can be used for surface ecological irrigation; and the mine water after tertiary treatment can be used for domestic water use.

[0093] As needed, the above technical solutions can be combined to achieve the best technical effect.

[0094] The above are only the principles and preferred embodiments of the present invention. It should be noted that, for those skilled in the art, several other variations can be made based on the principles of the present invention, which should also be considered as the scope of protection of the present invention.

Claims

1. A method for treating coal mine water underground, characterized in that: The steps include: S01: Excavation to form tunnels, underground water tanks and vertical shafts; S02: along the direction of the tunnel extension, a plurality of strip-type mining working faces are divided in sequence and marked as No. 1 mining working face, No. 2 mining working face... No. n mining working face in sequence. Accordingly, the goafs formed after subsequent mining are named No. 1 goaf, No. 2 goaf... No. n goaf in sequence, where n is a positive integer greater than or equal to 3; S03: Mining is performed in sequence from No. 1 mining face to No. n mining face, and the mine water generated during the mining of each mining face is temporarily stored in an underground water tank; Among them, before the No. 2 mining face was mined, a mine water purification system was built in the tunnel; S04: During the mining process from No. 3 mining face to No. n mining face: The mine water temporarily stored in the underground water tank is led to the first goaf before the mining face for preliminary purification, and the initially purified mine water is transported to the mine water purification treatment system for purification treatment. The mine water obtained after purification by the mine water purification treatment system is led out for use through pipelines; The concentrated brine produced after treatment by the mine water purification system is led to the second goaf before the mining face being mined and sealed.

2. The underground treatment method for coal mine water according to claim 1, characterized in that: The step S04 includes: After the formation of goaf No. 2 and when mining the goaf No. 3, the mine water temporarily stored in the underground water tank is led to goaf No. 2 through a pipeline for preliminary purification. The mine water after preliminary purification in goaf No. 2 is led to the mine water purification treatment system through a pipeline for purification treatment. The mine water obtained after purification by the mine water purification treatment system is led out through a pipeline for use. The concentrated brine produced after treatment by the mine water purification treatment system is led to goaf No. 1 through a pipeline; After the formation of goaf No. 3 and when mining working face No. 4 is being mined, goaf No. 1 is sealed, and the mine water temporarily stored in the underground water tank is led to goaf No. 3 through a pipe for preliminary purification. The concentrated brine produced after treatment by the mine water purification system is led to goaf No. 2 through a pipe, and so on, until mining working face No. n is mined.

3. The underground treatment method for coal mine water according to claim 2, characterized in that: After the mining of No. n mining face, it also includes: The mine water temporarily stored in the underground water tank is led to the No. n goaf through a pipe for preliminary purification. The concentrated brine produced after treatment by the mine water purification system is led to the No. n-1 goaf through a pipe. After the first preset time, the No. n-1 goaf is sealed.

4. The underground treatment method for coal mine water according to claim 3, characterized in that: After sealing the n-1 goaf, it also includes: The mine water temporarily stored in the underground water tank is led to the mine water purification system through pipelines; The concentrated brine produced after being treated by the mine water purification system is led to goaf No. n through a pipeline, and after a second preset time, goaf No. n is sealed.

5. The underground treatment method for coal mine water according to any one of claims 1 to 4, characterized in that: The step S04 includes: the mine water after preliminary purification in the goaf is led to the surface through a pipeline for production reuse.

6. The underground treatment method for coal mine water according to claim 5, characterized in that: The mine water that has been initially purified in the goaf is led to the coal washing plant through pipelines for use in coal washing; and / or, the mine water that has been initially purified in the goaf is led to the coal-fired power plant through pipelines for use in machine cooling.

7. The underground treatment method for coal mine water according to any one of claims 1 to 4, characterized in that: The mine water purification system includes a primary purification system, a secondary purification system and a tertiary purification system; The mine water after preliminary purification in the goaf is led to the primary purification treatment system through pipelines; The mine water purified by the primary purification system is led to the secondary purification system through pipelines; The mine water purified by the secondary purification system is led to the tertiary purification system through pipelines; The mine water purified by the three-stage purification system is led out to the surface through pipes for domestic use, and the concentrated brine obtained after purification by the three-stage purification system is led to the second goaf before the mining face being mined and sealed.

8. The underground treatment method for coal mine water according to claim 7, characterized in that: Part of the mine water purified by the primary purification system is also led through pipelines to the mining face for machine cooling and dust removal.

9. The underground treatment method for coal mine water according to claim 7, characterized in that: Part of the mine water purified by the secondary purification system is also led through pipes to above-ground reservoirs for irrigation.

10. The underground treatment method for coal mine water according to claim 7, characterized in that: The mine water purified by the three-stage purification system is led to the water plant through pipes.

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