System and method for repairing overlying strata water flowing fractures through microbial mineralization

Abstract

The invention relates to the technical field of water-preserved mining of coal mines, and discloses a system and method for repairing overlying strata water flowing fractures through microbial mineralization, and the system comprises a mineralization repairing agent preparation unit which is used for preparing a mineralization repairing agent based on a microbial bacterial solution, a mineralization precursor solution, a carbon source solution, a nutrient solution and / or a water chemical adjusting solution, the microorganisms adopt bacillus microorganisms with urea hydrolysis or carbonate mineralization capability; and the fracture injection unit is used for injecting the mineralization repairing agent into the overlying strata water diversion fracture zone between the mining coal seam and the shallow underground water. A biological-mineral composite flexible water-blocking structure can be formed in a repairing area, has interface adhesiveness and certain flexibility, can cooperatively deform along with slow sinking of overlying strata and the earth surface and stress adjustment, reduces secondary cracking and seepage channel reactivation, weakens the water guiding capacity among an underlying goaf, a working face and an overlying aquifer, and meanwhile, improves the water-blocking performance of the working face and the overlying aquifer. The water loss of shallow groundwater is reduced, and reliable technical support is provided for water-preserved mining under the aquifer.

Description

Technical Field

[0001] This invention relates to the field of water-conserving mining technology in coal mines, and in particular to a microbial mineralization system and method for repairing water-conducting fractures in overburden. Background Technology

[0002] In many coal-rich areas, there are shallow groundwater layers with good water quality and favorable recharge conditions, such as Quaternary loose aquifers and shallow bedrock fissure aquifers. These shallow groundwater layers often serve multiple functions, including domestic water supply, ecological water use, and agricultural irrigation, and are an important component of regional water resources. Beneath these layers, at a certain depth, lie mineable coal seams, which are extracted through underground mining.

[0003] Under water-conserving mining conditions beneath aquifers, it is necessary to ensure the safe and efficient mining of the underlying coal seam while simultaneously maintaining the water level and storage capacity of the overlying shallow groundwater to minimize water loss and quality. During coal seam mining, the overlying strata undergo deformation and damage under mining stress and unloading, including fissure development, rock collapse, and stratification, forming a water-conducting fracture zone extending upwards from the coal seam roof. When this fracture zone becomes excessively high, highly interconnected, or partially penetrates to the vicinity of the shallow groundwater floor, it can create seepage channels from the shallow groundwater to the goaf and working face, leading to a drop in the shallow groundwater level and water loss, weakening the aquifer's long-term water supply and ecological functions. Furthermore, the aquifer head can leak into the mine space, causing mine water hazards such as water inrush and sudden water bursts, threatening mining safety.

[0004] To address the aforementioned problems, existing technologies often employ rigid materials such as cement-based and chemical grouts to grout and reinforce water-conducting fractures in the overburden. However, these methods suffer from the following technical drawbacks: 1. High material rigidity and poor deformation coordination: Cement-based or chemically injected grouts have limited elastic deformation capacity, making it difficult to slowly subside with the overlying rock and surface after mining, and also unable to rely on stress redistribution caused by mining in adjacent working faces to coordinate deformation. They are prone to secondary cracking or interface peeling in the later stages, which can lead to the reactivation of seepage channels.

[0005] 2. Prone to deterioration under long-term hydrochemical action: The water bodies in the overlying rock water-blocking layer and aquifer often contain a certain concentration of dissolved salts, carbonate / bicarbonate ions, sulfate ions, etc. Under long-term soaking conditions, the interface between the grout and the surrounding rock may be eroded, debonded and microcracks may expand, and microcracks may also appear inside the grout.

[0006] 3. Difficulty in achieving both "water blocking" and "water retention" goals: Traditional grouting methods often focus on "waterproofing" and aim to rigidly seal the water-conducting fissures in the overlying rock as much as possible. This may result in the rigid cutting off of the bottom plate of the local aquifer, changing the original seepage field and recharge-drainage balance, which is not conducive to the long-term protection of shallow groundwater resources.

[0007] 4. Lack of adaptive repair capability for new fractures in the later stage: During the subsequent mining of adjacent working faces, new fractures or local re-opening fractures may still be generated in the overburden water-blocking layer between the coal seam and shallow groundwater. Traditional one-time grouting bodies lack subsequent "healing ability" and are difficult to effectively repair newly added or reactivated water-conducting fractures in a timely manner.

[0008] Therefore, it is necessary to develop a new overburden water-conducting fracture repair technology and supporting equipment that combines flexibility, adaptability and sustainable repair capabilities. This technology can construct a long-term stable "biological-mineral composite water-blocking structure" in the target strata between the coal seam and shallow groundwater. This will weaken the water-conducting capacity between the underlying goaf, working face and overlying aquifer, while minimizing the loss of shallow groundwater, and providing reliable technical support for water-conserving mining under aquifers. Summary of the Invention

[0009] The purpose of this invention is to provide a microbial mineralization system and method for repairing water-conducting fractures in overburden, in order to solve the problems existing in the prior art.

[0010] To achieve the above objectives, the present invention provides a microbial mineralization system for repairing water-conducting fractures in overburden, comprising: Mineralization remediation agent preparation unit, the mineralization remediation agent preparation unit comprising: A culture tank is used to expand microorganisms into microbial culture liquid, wherein the microorganisms contained in the microbial culture liquid are Bacillus species microorganisms with the ability to hydrolyze urea or mineralize carbonates. The first liquid tank is used to store solutions containing Ca. 2+ Mineralized precursor solution; The second liquid tank is used to store substances that can be hydrolyzed to produce CO3. 2- Carbon source solution; The third liquid tank is used to store nutrient solution and / or water chemistry conditioning solution; The mixing tank is connected to the culture tank, the first liquid tank, the second liquid tank and the third liquid tank via a feeding pipe. Flow regulating valves are installed at the connection points. The mixing tank is used to mix one or more of the following in a fixed ratio: microbial inoculum, mineralization precursor solution, carbon source solution, nutrient solution and / or water chemistry conditioning solution, to form at least one mineralization remediation agent. The fracture injection unit is used to inject mineralized remediation agents into the overburden water-conducting fracture zone located between the mined coal seam and shallow groundwater.

[0011] Furthermore, the fracture injection unit includes: The storage tank is connected to the mixing tank; A high-pressure injection pump, the inlet of which is connected to the liquid storage tank; The main injection pipeline is connected to the outlet of the high-pressure injection pump. The main injection pipeline is connected to multiple injection branch pipelines, which extend to the overburden water-conducting fracture zone for injecting mineralized repair agent into the overburden water-conducting fracture zone.

[0012] Furthermore, it also includes a monitoring unit, which comprises: Pressure sensors and flow sensors are arranged on the main injection pipeline and / or branch injection pipeline to obtain the injection pressure and injection flow rate of the mineralization remediation agent. Water level and water pressure sensors are installed near the water-conducting fracture zone of the overlying rock, with monitoring boreholes or drainage pipelines. The water level and water pressure sensors are arranged in the monitoring boreholes or drainage pipelines to monitor the changes in water head in the water-conducting fracture zone of the overlying rock. A water chemistry parameter sensor is installed at a monitoring borehole or sampling point located within a water-conducting fracture zone of the overlying rock. The sensor is used to monitor pH, Ca... 2+ Concentration and total dissolved solids were used to reflect the seepage and mineralization processes in the overlying water-conducting fracture zone and the hydrochemical changes in the overlying shallow groundwater.

[0013] Furthermore, it also includes a control unit, which is electrically connected to the mineralization remediation agent preparation unit, the fracture injection unit, and the monitoring unit, respectively. The control unit is used for: Control the mixing ratio and mixing time of microbial inoculum solution, mineralization precursor solution, carbon source solution, nutrient solution and / or water chemistry conditioning solution; Control the start / stop, injection pressure, and injection flow of the high-pressure injection pump.

[0014] Furthermore, the microbial liquid contains one or more of Bacillus pasteurellii, Bacillus subtilis, and Bacillus pseudostrongylus.

[0015] Furthermore, the mineralization precursor solution is one or more of calcium chloride solution and calcium nitrate solution, the carbon source solution is urea solution, and the nutrient solution contains a carbon source and a nitrogen source.

[0016] Furthermore, the culture tank, the first drug solution tank, the second drug solution tank, the third drug solution tank, the mixing tank, the storage tank, the high-pressure injection pump, and the control unit are integrated and installed on a movable skid-mounted base.

[0017] Furthermore, the culture tank is equipped with a stirring mechanism, a temperature control device, and / or a pH control device.

[0018] This invention also provides a method for microbial mineralization repair of water-conducting fractures in overburden, which utilizes a microbial mineralization system for repairing water-conducting fractures in overburden and includes the following steps: S1: Obtain the spatial distribution and equivalent permeability coefficient of the overburden water-conducting fracture zone between the coal seam and shallow groundwater. Based on the burial depth of the shallow groundwater floor and the safety head requirements, delineate the repair area of ​​the overburden water-conducting fractures that need to be repaired and the location of the boreholes. Drill boreholes and lay out the main injection pipeline and injection branch pipelines. Lay out monitoring boreholes or drainage pipelines near the repair area and place water level and water pressure sensors on the monitoring boreholes or drainage pipelines. S2: The control unit opens the flow regulating valves of the culture tank, the first drug solution tank, the second drug solution tank, and the third drug solution tank, and delivers one or more of the following into the mixing tank according to a preset ratio: microbial inoculum, mineralization precursor solution, carbon source solution, nutrient solution, and / or water chemistry conditioning solution, and mixes them in a fixed ratio to form at least one mineralization remediation agent; after the mineralization remediation agent is mixed, it is delivered to the storage tank or remains in the mixing tank; S3: The mineralization remediation agent is pumped to the main injection pipeline via a high-pressure injection pump and injected into the remediation area through multiple injection branch pipelines, allowing the mineralization remediation agent to seep along the fissure channels in the remediation area and fill the fissure spaces; initially, nutrient solution and / or water chemistry conditioning solution are injected into the remediation area as mineralization remediation agents to adjust the pH and Ca of the water in the remediation area. 2+ The concentration and carbon source concentration are kept within the range for microbial growth, and then the microbial liquid is injected into the repair area as a mineralization repair agent, so that the microbial liquid adheres to the crack wall. S4: After the preset injection time is reached, stop injecting the microbial solution. Then, by restoring the water chemistry environment within the restoration area and / or injecting a water chemistry conditioning solution into the restoration area, adjust the pH and Ca content of the water within the restoration area. 2+ The concentrations of the carbon source and the concentration of the microorganisms are kept within the range of microbial growth and mineral deposition. Microorganisms attach to and grow in the fissure channels within the repair area and induce mineral deposition, forming fillers, bridging bodies or shell structures.

[0019] Furthermore, it also includes the following steps: The repair area is monitored by water level, water pressure and water chemistry parameter sensors. When new cracks are generated or local cracks reopen in the repair area, nutrient solution and mineralization precursor solution are injected into the repair area by high pressure injection pump to trigger secondary mineralization.

[0020] The present invention discloses the following technical effects: 1. This invention injects a mineralized repair agent into the water-conducting fracture zone of the overburden, enabling the formation of a flexible "bio-mineral composite" water-blocking structure within the repair area. This flexible water-blocking structure is a composite structure composed of carbonate minerals induced by microorganisms, bacterial cells, and extracellular polymers. Compared to the rigid structure formed after the grout solidifies in existing technologies, it has better interfacial adhesion and a certain degree of flexibility, allowing it to deform in tandem with the slow subsidence of the overburden and surface and stress adjustment, reducing secondary cracking and the reactivation of seepage channels. Furthermore, the formation of this flexible water-blocking structure utilizes the hydrochemical environment of the water-conducting fracture zone of the overburden, naturally avoiding problems such as dissolution, debonding, and microcrack propagation, and preventing the formation of microcrack seepage channels within the structure.

[0021] 2. Balancing water blocking and water retention to reduce shallow groundwater loss. This invention limits the injection location of the mineralization remediation agent to the water-conducting fracture zone of the overlying rock, which weakens the hydraulic connection between the goaf, working face and shallow groundwater, preventing water inrush and sudden water flow, while avoiding direct damage to the internal structure of the aquifer, and is conducive to the long-term protection of shallow groundwater resources, thereby achieving "water-retaining mining".

[0022] 3. Capable of secondary repair of new fractures. This invention can use a monitoring unit to track parameters such as water level, water pressure, and hydrochemistry over a long period of time. When slow subsidence occurs after mining or when mining activities in adjacent working faces induce new fractures or local fractures to reopen, secondary mineralization can be triggered by low-intensity injection of nutrient solution and mineralization precursor solution, thereby achieving follow-up repair of new water-conducting channels. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 Schematic diagram of the mineralization repair agent preparation unit; Figure 3 This is a schematic diagram illustrating the operation of the present invention; Figure 4 This is a control diagram of the control unit; Figure 5 This is a flowchart of the microbial mineralization method for repairing water-conducting fractures in overburden, as described in this invention. Among them, 10, overburden water-conducting fracture zone; 20, mineralization repair agent preparation unit; 21, incubation tank; 22, first liquid tank; 23, second liquid tank; 24, third liquid tank; 25, mixing tank; 26, flow regulating valve; 30, fracture injection unit; 31, storage tank; 32, high-pressure injection pump; 33, main injection pipeline; 34, branch injection pipeline; 40, monitoring unit; 41, pressure sensor; 42, flow sensor; 50, control unit; 60, shallow groundwater; 70, goaf; 80, working face; 90, mined coal seam. Detailed Implementation

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] Those skilled in the art will understand that the term "comprising" as used in this application means the presence of the stated features, integers, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. It should be understood that when we say an element is "connected" or "coupled" to another element, it can be directly connected or coupled to the other element, or there may be intermediate elements present. Furthermore, "connected" or "coupled" as used herein can include wireless connections or wireless coupling. The term "and / or" as used herein includes all or any unit and all combinations of one or more associated listed items.

[0027] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0028] like Figures 1 to 5 As shown, the present invention provides a microbial mineralization system for repairing water-conducting fractures in overlying rock, comprising: Mineralization remediation agent preparation unit 20, the mineralization remediation agent preparation unit 20 includes: Culture tank 21 is used to expand microorganisms into microbial culture solution, the microorganisms contained in the microbial culture solution are Bacillus microorganisms with the ability to hydrolyze urea or mineralize carbonate; The first liquid tank 22 is used to store liquids containing Ca. 2+ Mineralized precursor solution; The second liquid tank 23 is used to store substances that can be hydrolyzed to produce CO3. 2- Carbon source solution; The third liquid tank 24 is used to store nutrient solution and / or water chemistry conditioning solution; The mixing tank 25 is connected to the culture tank 21, the first liquid tank 22, the second liquid tank 23 and the third liquid tank 24 respectively through the feeding pipe. The connection points are respectively equipped with flow regulating valves 26. The mixing tank 25 is used to mix one or more of the following in a certain proportion: microbial inoculum, mineralization precursor solution, carbon source solution, nutrient solution and / or water chemical conditioning solution to form at least one mineralization remediation agent. The fracture injection unit 30 is used to inject mineralization repair agent into the overburden water-conducting fracture zone 10 located between the mined coal seam 90 and the shallow groundwater 60.

[0029] In this embodiment, the mineralization remediation agent preparation unit 20 includes: The culture tank 21 is used to expand microorganisms into microbial culture solution. The culture tank 21 is equipped with a stirring mechanism, a temperature control device and / or a pH control device. The first liquid tank 22 is used to store liquids containing Ca. 2+ Mineralized precursor solution; The second liquid tank 23 is used to store substances that can be hydrolyzed to produce CO3. 2- Carbon source solution; The third liquid tank 24 is used to store nutrient solution and / or water chemistry conditioning solution; The mixing tank 25 is connected to the culture tank 21, the first liquid tank 22, the second liquid tank 23 and the third liquid tank 24 through the feeding pipe. Flow regulating valves 26 are installed at the connection points. The mixing tank 25 is used to mix microbial inoculum, mineralization precursor solution, carbon source solution, nutrient solution and / or water chemical conditioning solution in a fixed ratio to form a mineralization remediation agent.

[0030] In this embodiment, a stirring mechanism is also arranged in the mixing tank 25 to improve the mixing uniformity of the mineralization remediation agent. The proportion of each liquid entering the mixing tank 25 can be adjusted by controlling the opening of the flow regulating valve 26.

[0031] In this embodiment, the fracture injection unit 30 includes: Storage tank 31 is connected to mixing tank 25; High-pressure injection pump 32, the inlet of which is connected to liquid storage tank 31; The main injection pipeline 33 is connected to the outlet of the high-pressure injection pump 32. The main injection pipeline 33 is connected to multiple injection branch pipelines 34. The injection branch pipelines 34 extend to the overlying rock water-conducting fracture zone 10 and are used to inject the mineralization repair agent into the overlying rock water-conducting fracture zone 10.

[0032] In this embodiment, a monitoring unit 40 is also included, which includes: Pressure sensor 41 and flow sensor 42 are arranged on injection main pipeline 33 and / or injection branch pipeline 34 to obtain injection pressure and injection flow rate of mineralization remediation agent. Water level and water pressure sensors are installed near the overlying rock water-conducting fracture zone 10. Monitoring boreholes or drainage pipelines are set up to monitor the water head changes in the overlying rock water-conducting fracture zone 10. A water chemistry parameter sensor is installed at the monitoring borehole or sampling point, located within the overlying water-conducting fracture zone 10. The water chemistry parameter sensor is used to monitor pH, Ca... 2+ Concentration and total dissolved solids were used to reflect the seepage and mineralization process of the overlying water-conducting fracture zone 10 and the hydrochemical changes of the overlying shallow groundwater 60.

[0033] In this embodiment, the monitoring unit 40 further includes an online water quality sensor installed on the return water pipeline for real-time detection of the pH and Ca content of the return water. 2+ At least one of concentration, conductivity and turbidity is used to determine the degree of blockage in the overlying water-conducting fracture zone 10 and the hydrochemical changes in the shallow groundwater 60.

[0034] In this embodiment, a control unit 50 is also included. The control unit 50 is a programmable logic controller or an industrial control computer, with a built-in multi-stage injection sequence control program. The control unit 50 is electrically connected to the mineralization repair agent preparation unit 20, the fracture injection unit 30, and the monitoring unit 40, respectively. The control unit 50 is used for: Based on the preset program and the parameters obtained by the monitoring unit 40, the mixing ratio and mixing time of the microbial inoculum, mineralization precursor solution, carbon source solution, nutrient solution and / or water chemistry conditioning solution are controlled. Control the start / stop, injection pressure, and injection flow rate of the high-pressure injection pump 32; The injection conditions are adjusted in real time based on the pressure, water level and hydrochemical parameters monitored by the monitoring unit 40, so as to maintain the water level of shallow groundwater 60 as much as possible while repairing the water-conducting fracture zone 10 of the overburden.

[0035] In this embodiment, the microbial liquid contains one or more of Bacillus pasteurellii, Bacillus subtilis, and Bacillus pseudostrongylus.

[0036] In this embodiment, during the microbial propagation process, mine water or shallow groundwater samples should be used as much as possible to improve the adaptability of microorganisms to the target aquifer's water chemical environment.

[0037] In this embodiment, the mineralization precursor solution is one or more of calcium chloride solution and calcium nitrate solution, the carbon source solution is urea solution, and the nutrient solution contains carbon source, nitrogen source and trace elements to maintain the activity of microorganisms in the overlying water-conducting fracture zone 10.

[0038] In this embodiment, the culture tank 21, the first liquid tank 22, the second liquid tank 23, the third liquid tank 24, the mixing tank 25, the storage tank 31, the high-pressure injection pump 32, and the control unit 50 are integrated and installed on a movable skid base so that they can be transported as a whole on the ground and underground and moved between different working faces 80, so as to realize the reuse of water-retaining mining working faces 80 under different aquifers.

[0039] In this embodiment, the culture tank 21 is equipped with a stirring mechanism, a temperature control device and / or a pH control device.

[0040] This invention also provides a method for microbial mineralization repair of water-conducting fractures in overburden, which utilizes a microbial mineralization system for repairing water-conducting fractures in overburden and includes the following steps: S1: Obtain the spatial distribution and equivalent permeability coefficient of the water-conducting fracture zone 10 in the overlying rock between the mined coal seam 90 and the shallow groundwater 60. Specifically, geological, mining, and hydrogeological data of the area where the water-retaining mining face 80 is located under the aquifer can be obtained. Combined with geophysical exploration, drilling, and water pressure or injection tests, determine the spatial distribution and equivalent permeability coefficient of the water-conducting fracture zone in the overlying rock between the mined coal seam 90 and the shallow groundwater 60. Based on the burial depth of the bottom plate of the shallow groundwater 60 and the safety head requirements, delineate the repair area of ​​the water-conducting fractures in the overlying rock that need to be repaired and the location of the boreholes. Drill boreholes and install the main injection pipeline 33 and the branch injection pipeline 34. Install monitoring boreholes or drainage pipelines near the repair area and install water level and water pressure sensors on the monitoring boreholes or drainage pipelines.

[0041] S2: Control unit 50 opens the flow regulating valve 26 of culture tank 21, first medicine tank 22, second medicine tank 23, and third medicine tank 24, and delivers one or more of the following into mixing tank 25 according to a preset ratio: microbial inoculum, mineralization precursor solution, carbon source solution, nutrient solution and / or water chemical conditioning solution, and mixes them in a fixed ratio to form at least one mineralization repair agent; after the mineralization repair agent is mixed, it is delivered to storage tank 31 or remains in mixing tank 25.

[0042] S3: The mineralization remediation agent is pumped to the main injection pipeline 33 via a high-pressure injection pump 32 and injected into the remediation area through multiple injection branch pipelines 34, allowing the mineralization remediation agent to seep along the fissure channels in the remediation area and fill the fissure space; the injection pressure is controlled to be greater than the seepage initiation pressure of the overlying rock water-conducting fissures and less than the fracturing pressure of the surrounding rock in the remediation area, preferably 1.1 to 2.5 times the seepage initiation pressure of the water-conducting fissures, to ensure that the remediation agent seeps fully along the existing fissures without inducing new upward penetrating fissures and avoiding damage to the integrity of the shallow groundwater 60 bottom plate; specifically, nutrient solution and / or water chemical conditioning solution are first injected into the remediation area as mineralization remediation agents to adjust the pH and Ca of the water in the remediation area. 2+The concentrations of the microorganisms and carbon source are kept within the range for microbial growth. Then, the microbial liquid is injected into the repair area as a mineralization repair agent, allowing the microbial liquid to adhere to the crack wall.

[0043] S4: After the preset injection time is reached, stop injecting the microbial solution. Then, by restoring the water chemistry environment within the restoration area and / or injecting a water chemistry conditioning solution into the restoration area, adjust the pH and Ca content of the water within the restoration area. 2+ The concentrations of microorganisms and carbon sources are maintained within the range of microbial growth and mineral deposition. Microorganisms attach to and grow in the fracture channels within the remediation area, inducing mineral deposition and forming fillers, bridging structures, or shell structures. These structures together constitute a flexible water-blocking structure, which can reduce the connectivity and effective porosity of the overburden water-conducting fracture zone 10, and weaken the hydraulic connection between shallow groundwater 60 and the goaf 70 and working face 80.

[0044] S5: After repair, using the injection pressure, flow rate, and water level, water pressure, and hydrochemical parameters of the monitoring borehole obtained by monitoring unit 40, a pressure test or injection test can be conducted. Combining the results of the pressure test or injection test before and after repair, the change in the equivalent permeability coefficient or water inrush coefficient of the repaired area is evaluated. If the water conductivity index after repair is less than the preset safety threshold and the drop in shallow groundwater level 60 is controlled within the allowable range, the repair is deemed qualified. Otherwise, steps S2-S5 are repeated by adjusting the mineralization remediation agent ratio or injection conditions through control unit 50.

[0045] In this embodiment, the following steps are also included: In steps S4 and S5, the repair area is monitored by water level, water pressure, and hydrochemical parameter sensors. When new fractures occur or localized fractures reopen in the repair area, nutrient solution and mineralization precursor solution are injected into the repair area via high-pressure injection pump 32 to trigger secondary mineralization. This achieves an integrated "monitorable, controllable, and evaluable" repair process. Monitoring unit 40 integrates online monitoring of pressure, flow rate, water level / pressure, and hydrochemical parameters. Control unit 50 adjusts the repair agent ratio, injection pressure, and injection flow rate in real time based on the monitoring data. The repair effect is quantitatively evaluated through pressure / injection tests before and after repair, providing data support for water-conserving mining beneath aquifers.

[0046] In this embodiment, after the repair is deemed qualified, the mining height, advance speed and water-resistant coal (rock) pillar parameters of the corresponding working face 80 are optimized and adjusted according to the evaluation results of the water-blocking capacity of the repair area, so as to achieve water-retaining mining under the aquifer while ensuring the basic stability of the shallow groundwater level and water quality.

[0047] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0048] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0049] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0050] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A microbial mineralization system for repairing water-conducting fractures in overlying rock, characterized in that, include: A mineralization remediation agent preparation unit (20) comprising: The culture tank (21) is used to expand microorganisms to form microbial liquid, wherein the microorganisms contained in the microbial liquid are Bacillus microorganisms with the ability to hydrolyze urea or mineralize carbonates; The first liquid tank (22) is used to store liquid containing Ca. 2+ Mineralized precursor solution; The second liquid tank (23) is used to store the CO3 produced by hydrolysis. 2- Carbon source solution; The third liquid tank (24) is used to store nutrient solution and / or water chemistry conditioning solution; The mixing tank (25) is connected to the culture tank (21), the first liquid tank (22), the second liquid tank (23) and the third liquid tank (24) respectively through the feeding pipe. The connection points are respectively equipped with flow regulating valves (26). The mixing tank (25) is used to mix one or more of the following in a certain proportion: microbial inoculum, mineralization precursor solution, carbon source solution, nutrient solution and / or water chemical conditioning solution to form at least one mineralization remediation agent. A fracture injection unit (30) is used to inject mineralization repair agent into the overburden water-conducting fracture zone (10) located between the mined coal seam (90) and shallow groundwater (60).

2. The microbial mineralization system for repairing water-conducting fractures in overlying rock according to claim 1, characterized in that, The fracture injection unit (30) includes: The storage tank (31) is connected to the mixing tank (25); A high-pressure injection pump (32) has its inlet connected to the liquid storage tank (31); The main injection pipeline (33) is connected to the outlet of the high-pressure injection pump (32). The main injection pipeline (33) is connected to multiple injection branch pipelines (34). The injection branch pipelines (34) extend to the overlying rock water-conducting fracture zone (10) and are used to inject the mineralization repair agent into the overlying rock water-conducting fracture zone (10).

3. The microbial mineralization system for repairing water-conducting fractures in overlying rock according to claim 2, characterized in that, It also includes a monitoring unit (40), which includes: Pressure sensor (41) and flow sensor (42) are arranged on the main injection pipeline (33) and / or the branch injection pipeline (34) to obtain the injection pressure and injection flow rate of the mineralization remediation agent; Water level and water pressure sensors are installed near the water-conducting fracture zone (10) of the overlying rock. Monitoring boreholes or drainage pipelines are set up and water level and water pressure sensors are arranged on the monitoring boreholes or drainage pipelines to monitor the water head changes of the water-conducting fracture zone (10) of the overlying rock. A water chemistry parameter sensor is installed at a monitoring borehole or sampling point located within a water-conducting fracture zone (10) of the overlying rock. The water chemistry parameter sensor is used to monitor pH, Ca... 2+ Concentration and total dissolved solids were used to reflect the seepage and mineralization process of the overlying water-conducting fracture zone (10) and the hydrochemical changes of the overlying shallow groundwater (60).

4. The microbial mineralization system for repairing water-conducting fractures in overlying rock according to claim 3, characterized in that, It also includes a control unit (50), which is electrically connected to the mineralization repair agent preparation unit (20), the fracture injection unit (30), and the monitoring unit (40), respectively. The control unit (50) is used for: Control the mixing ratio and mixing time of microbial inoculum solution, mineralization precursor solution, carbon source solution, nutrient solution and / or water chemistry conditioning solution; Control the start / stop, injection pressure and injection flow of the high-pressure injection pump (32).

5. A microbial mineralization system for repairing water-conducting fractures in overlying rock according to claim 4, characterized in that, The microbial inoculum contains one or more of the following microorganisms: Pasteurella multocida, Bacillus subtilis, and Bacillus pseudostrongylus.

6. A microbial mineralization system for repairing water-conducting fractures in overlying rock according to claim 4, characterized in that, The mineralization precursor solution is one or more of calcium chloride solution and calcium nitrate solution, the carbon source solution is urea solution, and the nutrient solution contains a carbon source and a nitrogen source.

7. A microbial mineralization system for repairing water-conducting fractures in overlying rock according to claim 4, characterized in that, The culture tank (21), the first liquid tank (22), the second liquid tank (23), the third liquid tank (24), the mixing tank (25), the storage tank (31), the high-pressure injection pump (32), and the control unit (50) are integrated and installed on a movable skid base.

8. A microbial mineralization system for repairing water-conducting fractures in overlying rock according to claim 4, characterized in that, The culture tank (21) is equipped with a stirring mechanism, a temperature control device and / or a pH control device.

9. A method for microbial mineralization repair of water-conducting fractures in overburden, characterized in that, The application of the microbial mineralization repair system for overburden water-conducting fractures according to any one of claims 4-8 includes the following steps: S1: Obtain the spatial distribution and equivalent permeability coefficient of the overburden water-conducting fracture zone (10) between the coal seam (90) and shallow groundwater (60). Based on the burial depth of the bottom plate of the shallow groundwater (60) and the safety head requirements, delineate the repair area of ​​the overburden water-conducting fracture and the location of the boreholes. Drill boreholes and arrange the main injection pipeline (33) and the branch injection pipeline (34). Arrange monitoring boreholes or drainage pipelines near the repair area and arrange water level and water pressure sensors on the monitoring boreholes or drainage pipelines. S2: The control unit (50) opens the flow regulating valves (26) of the culture tank (21), the first liquid tank (22), the second liquid tank (23), and the third liquid tank (24), and delivers one or more of the following into the mixing tank (25) in a preset ratio: microbial inoculum, mineralization precursor solution, carbon source solution, nutrient solution and / or water chemical conditioning solution, and mixes them in a fixed ratio to form at least one mineralization repair agent; after the mineralization repair agent is mixed, it is delivered to the storage tank (31) or remains in the mixing tank (25); S3: The mineralization remediation agent is pumped to the main injection pipeline (33) via a high-pressure injection pump (32) and injected into the remediation area through multiple injection branch pipelines (34), allowing the mineralization remediation agent to seep along the crack channels in the remediation area and fill the crack space; firstly, nutrient solution and / or water chemistry conditioning solution are injected into the remediation area as mineralization remediation agents to adjust the pH and Ca of the water in the remediation area. 2+ The concentration and carbon source concentration are kept within the range for microbial growth, and then the microbial liquid is injected into the repair area as a mineralization repair agent, so that the microbial liquid adheres to the crack wall. S4: After the preset injection time is reached, stop injecting the microbial solution. Then, by restoring the water chemistry environment within the restoration area and / or injecting a water chemistry conditioning solution into the restoration area, adjust the pH and Ca content of the water within the restoration area. 2+ The concentrations of the carbon source and the concentration of the microorganisms are kept within the range of microbial growth and mineral deposition. Microorganisms attach to and grow in the fissure channels within the repair area and induce mineral deposition, forming fillers, bridging bodies or shell structures.

10. A method for microbial mineralization repair of water-conducting fractures in overburden as described in claim 9, characterized in that, It also includes the following steps: The repair area is monitored by water level, water pressure and water chemical parameter sensors. When new cracks are generated or local cracks are opened in the repair area, nutrient solution and mineralization precursor solution are injected into the repair area by high pressure injection pump (32) to trigger secondary mineralization.

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