Mine water treatment and mine water energy utilization method

Abstract

The application discloses a mine water treatment and mine water energy utilization method and relates to the field of mineral resource exploitation. The method comprises the following steps: constructing an energy hole in a coal mine tunnel; performing high-pressure grouting hole sealing on the energy hole, and installing a high-pressure blowout preventer and a pressure meter on the energy hole; installing a hydraulic power generation turbine set on the rear side of the high-pressure blowout preventer, changing the water flow direction, changing the water flow pressure into angular momentum, and converting the angular momentum into electric energy; constructing an underground water warehouse, guiding the water body discharged through a sealed water guide pipeline into the underground water warehouse; placing a horizontal pump near the underground water warehouse, pumping the water in the underground water warehouse out of the ground through the horizontal pump, and performing physical impurity removal and scale removal on the water in a surface water treatment station; the water after the scale removal is introduced into a quality water engineering or is poured into a surface reservoir; constructing an ordovician limestone well, pumping the water in the surface reservoir out of the ground through a water pump, and pouring the water back into a mining layer after sand removal; and the method can fully utilize mine water energy under the premise of ensuring construction safety and improves economic benefits.

Description

Technical Field

[0001] This invention relates to the field of mineral resource extraction technology, and in particular to a method for mine water treatment and mine water energy utilization. Background Technology

[0002] Currently, in the underground mining of mineral resources in North China, as the mining depth gradually increases, the hydrogeological conditions of mining areas with strong permeability of overlying water bodies and high pressure head of underlying water bodies are the main causes of mine water inrushes and other "water hazards." During mine production, the volume of water inflow is large and the treatment methods are complex. Existing methods typically involve directly treating and discharging mine water without utilizing the energy potential within the water, resulting in low economic efficiency. Summary of the Invention

[0003] In view of the problems mentioned in the background art, the present invention provides a method for mine water treatment and mine water energy utilization, which can make full use of mine water energy and improve economic benefits while ensuring construction safety.

[0004] To achieve the above objectives, the present invention provides the following solution:

[0005] A method for mine water treatment and mine water energy utilization includes:

[0006] In the case of drainage, energy holes are constructed downwards or upwards in coal mine roadways;

[0007] High-pressure grouting is used to seal the energy holes during construction, and high-pressure blowout preventers and pressure gauges are installed at the openings of the energy holes.

[0008] A hydroelectric turbine unit is installed behind the high-pressure blowout preventer valve. The water flow direction is changed by the placement of the hydroelectric turbine unit, and the water flow pressure is converted into angular momentum, which is then converted into electrical energy.

[0009] The construction of the underground water tank involves introducing the sprayed water into the underground water tank through a closed water diversion pipeline.

[0010] A horizontal pump is placed near the underground water reservoir to pump the water from the reservoir into a surface water treatment plant for physical removal of impurities and scale.

[0011] After descaling, the water is either used in water separation projects or injected into surface reservoirs.

[0012] The construction of the Ordovician limestone well involves pumping water out of the surface reservoir, removing sand, and then reinjecting it into the mining layer.

[0013] Optionally, multiple sets of the high-pressure blowout preventer valves are provided; the high-pressure blowout preventer valves are used to control when water is released; the pressure gauge is used to monitor the water pressure at the high-pressure blowout preventer valves.

[0014] Optionally, multiple hydroelectric turbine units are installed to convert water pressure into electrical energy.

[0015] Optionally, the size of the underground water reservoir should be determined based on the amount of water obtained from exploration and release and the time difference between peak and valley, and should be able to hold at least 12 hours of natural water release.

[0016] Optionally, the construction of energy holes downwards or upwards in the coal mine roadway specifically includes:

[0017] When mining a lower coal seam, locate the location of the fracture and construct the energy borehole. The fracture should be extended 100-300m below the interlayer karst to open up the interlayer karst zone. The construction sequence is as follows: first, construct the borehole into the interlayer karst zone, grout the interlayer karst to seal and form a stable backfill; then, penetrate the backfill and construct the influence zone of the structural and interlayer composite triangular area with water-conducting properties.

[0018] When the underground water supply pipeline is not feasible, the water will be treated and reinjected to form good water reinjection.

[0019] Optionally, the head pressure drop in the influence zone of the interlayer composite triangular region conforms to Darcy's law and Forchheimer flow.

[0020] Optionally, the construction of the Ordovician limestone well specifically includes:

[0021] Add sealing walls in the coal mine roadway. After the sealing walls are built, locate and construct the Ordovician limestone well on the surface. The Ordovician limestone well passes through the mining roadway strata and goes deep into the lower strata, and is constructed to the critical strata above the interlayer karst.

[0022] For the completed Ordovician limestone well, pipes are laid. After the pipes are laid, high-pressure grouting is performed on the outside of the pipes, and a filling body is formed near the sealing wall.

[0023] After the grouting material cools down, the tunnel is excavated from the underground roadway to the surface construction site of the Ordovician limestone well, breaking through the sealing wall and filling body, and welding the horizontal pipes to the vertical pipes. The vertical pipes are not cut at the weld joint.

[0024] Install high-pressure blowout preventers and pressure gauges on the horizontal pipes to complete this horizontal operation;

[0025] Continue drilling from the surface to the vertical Ordovician limestone well, drilling downwards to the karst zone between the Ordovician limestone karst layers or the complex triangular zone. In the karst zone between the Ordovician limestone karst layers, bare holes or bridge-type filter pipes are used.

[0026] After the Ordovician limestone well is constructed to the corresponding hole depth, the connection between the vertical and horizontal pipes is perforated or cut to open up the channel between the horizontal and vertical Ordovician limestone wells, forming a communicating vessel effect.

[0027] The Ordovician limestone karst mass is used as a large-scale equivalent reservoir. The constructed Ordovician limestone well is equivalent to a water body communicating vessel. The horizontal vent installed in the geothermal well tunnel has equivalent water pressure. The auxiliary well is used to complete the pumping and injection water circulation, forming a water flow circulation.

[0028] Optionally, the pipe used for installation may be a high-strength steel pipe or an oil casing.

[0029] Optionally, quick-setting cement may be used as the high-pressure grouting material.

[0030] Optionally, the method for mine water treatment and mine water energy utilization further includes: generating electricity by releasing water when electricity prices are high, and pumping water to the surface or reinjecting it when electricity prices are low.

[0031] According to specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0032] This invention provides a method for mine water treatment and mine water energy utilization. The method involves constructing energy holes downwards or upwards in coal mine roadways under drainage conditions; sealing the constructed energy holes with high-pressure grouting; installing high-pressure blowout preventers and pressure gauges at the hole openings; installing a hydroelectric turbine unit behind the high-pressure blowout preventer; changing the water flow direction by the placement of the hydroelectric turbine unit, converting water pressure into angular momentum, and then into electrical energy; constructing an underground water tank; guiding the effluent water into the underground water tank through a closed-loop water pipe; placing a horizontal pump near the underground water tank; pumping the water from the underground water tank into a surface water treatment station for physical impurity and scale removal; the descaled water then enters a differentiated water use project or is injected into a surface reservoir; constructing an orogenic limestone well; pumping the water from the surface reservoir; removing sand; and reinjecting it into the mining layer. This method can fully utilize mine water energy while ensuring construction safety, significantly improving economic benefits.

[0033] This invention relates to a method for mine water treatment and mine water energy utilization that integrates functions such as mine water hazard control, pumped storage for peak shaving and valley filling, full life-cycle utilization of underground mine space, and advanced drainage development for the resource utilization of mine water. It not only makes full use of the potential energy of water, turning "water hazard" into "water resource", but also provides a new way to utilize underground mine space after mining is completed by combining energy storage with relatively low investment, thus adding a new economic value to mine water inflow. Attached Figure Description

[0034] 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.

[0035] Figure 1 This is a flowchart of a method for mine water treatment and mine water energy utilization according to the present invention;

[0036] Figure 2 This is a schematic diagram illustrating the principle of a mine water treatment and mine water energy utilization method according to the present invention.

[0037] Figure 3 This is a schematic diagram of the construction method for constructing energy holes downwards in the lower coal roadway according to the present invention;

[0038] Figure 4 This is a schematic diagram of the construction of the sealing wall and the laying of pipes in the surface construction method of the Ordovician lime well of the present invention;

[0039] Figure 5 This is a schematic diagram of the process of installing horizontal pipes in the surface construction method of the Ordovician lime well of the present invention;

[0040] Figure 6 This is a schematic diagram of the drilling and pipe connection process in the surface construction method of the Ordovician limestone well of the present invention;

[0041] Figure 7 This is a schematic diagram of the concept model of the Ordovician limestone well of the present invention. Detailed Implementation

[0042] 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.

[0043] The purpose of this invention is to provide a method for mine water treatment and mine water energy utilization, which can fully utilize mine water energy and improve economic benefits while ensuring construction safety.

[0044] 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.

[0045] Figure 1 This is a flowchart illustrating a method for mine water treatment and mine water energy utilization according to the present invention. Figure 2 This is a schematic diagram illustrating the principle of a mine water treatment and mine water energy utilization method according to the present invention. See also... Figure 1 and Figure 2 A method for mine water treatment and mine water energy utilization, comprising:

[0046] Step 1: Under drainage conditions, construct energy holes downward or upward in the coal mine roadway.

[0047] This invention relates to coal mine roadways, specifically coal mining roadways, and allows for the construction of energy wells in roadways where mining operations have already been completed. See also... Figure 2 This invention describes the construction of energy boreholes, either downwards or upwards, in coal mine roadways under hydrophobic conditions. These boreholes are used for subsequent energy conversion and utilization. Based on the difference in energy conversion efficiency, this embodiment focuses on the construction of downward energy boreholes.

[0048] Figure 3 This is a schematic diagram illustrating the construction method for constructing energy wells downwards in the lower coal roadway according to the present invention. See also... Figure 3 If the coal seam being mined is a lower coal seam, then energy wells can be constructed at specific locations with fractures to drain water. Generally, the fracture should be water-conducting, have sufficient safety coal pillars, and extend 100-300m below the interlayer karst. The fracture should be able to connect to the interlayer karst area. The construction sequence should be as follows: first, construct into the interlayer karst area, then grout the karst to seal and form a stable backfill. The backfill refers to the area where solidifiable fluids such as grout (generally only cement or water glass) are injected, which solidifies to form a water-blocking area. Then, penetrate the backfill and construct into the water-conducting fracture "tectonic water-rich triangle" influence zone (i.e.,...). Figure 3 The tectonic and interstratal composite triangle refers to a geologically combined region where fractured structures and water-rich karst areas exist. Fractured structures refer to suture zones formed by fractures, cracks, and dislocations within sedimentary strata. This "tectonic water-rich triangle" generally influences the pressure drop in the stratigraphic zone according to Darcy's law and Forchheimer flow. The three physical processes—Navier-Stokes turbulence, Darcy laminar flow, and Forchheimer flow—are described below.

[0049] According to the theory of flow field dynamics, groundwater in the coal mining subsidence zone (tensional fault zone), aquifer, and fracture zone (fault, water-conducting fracture zone, collapse column) of North China coal mining subsidence area has undergone three physical processes: Navier-Stokes turbulent flow, Darcy laminar flow, and Forchheimer flow.

[0050] 1) Navier-Stokes turbulence in the goaf caving zone (tensional fault zone)

[0051] The collapse zone in the goaf is mainly composed of large-pore media and irregular conduits. Groundwater flows freely within it at relatively high velocities, with Reynolds numbers generally greater than 10, exhibiting a non-steady turbulent flow state. This unsteady state can be represented by the Navier-Stokes equations for incompressible fluids.

[0052]

[0053]

[0054] In the formula, ρ represents the fluid density, kg / m³. 3 u is the groundwater flow velocity, m / s; t is the time variable, s; η is the dynamic viscosity, Pa·s; is the gradient operator; p is the fluid pressure, Pa; f is the fluid mass force, N.

[0055] 2) Darcy laminar flow in aquifers

[0056] The velocity of groundwater within an aquifer is very low; the driving force for seepage is primarily fluid pressure, and the flow velocity increases with increasing fluid pressure. The Reynolds number is generally between 1 and 10, and it follows a linear Darcy's law, which can be expressed as:

[0057]

[0058] In the formula, k is the permeability, m²; Z is the head, m; and g is the acceleration due to gravity, typically 9.8 m / s². 2 .

[0059] Under unsteady-state conditions, the seepage continuity equation is:

[0060]

[0061] In the formula, φ represents the porosity of the medium.

[0062] 3) Forchheimer flow in the fracture zone

[0063] After mining disturbance, both fault fracture zones and water-conducting fracture zones are composed of fractured rock masses, belonging to porous media with large voids. Previous studies have shown that the velocity of groundwater in these zones increases or decreases. The water-conducting flow pattern in such media no longer falls under the Darcy flow category and obeys the Forchheimer equations. Similarly, fault fracture zones also conform to this characteristic. Under unsteady-state conditions, the Forchheimer-type non-Darcy flow motion equation, continuity equation, and state equation for groundwater in fracture zones can be expressed as follows:

[0064]

[0065]

[0066]

[0067] In the formula, c a β is the acceleration coefficient; β is the non-Darcy factor; q is the source-sink term strength, s -1 p0 is the initial pressure, Pa; φ0 is the initial porosity; c φ is the pore compressibility coefficient.

[0068] Flow resistance is the reciprocal of the unit seepage coefficient when linear Darcy's law holds. According to scientific literature (Research on the hydrothermal migration mechanism and thermal environment control of fractured rock mass in geothermal anomaly mines, Wang Junhui), the expression of flow resistance can be:

[0069]

[0070] The dimensionless Forchheimer formula (8) can be written in the form of flow resistance. According to scientific literature, the flow resistance r can be expressed as:

[0071]

[0072] B D =A D ·ξ (10)

[0073]

[0074] The three physical processes mentioned above interact and work together to form an organic whole in which groundwater seeps through multiple complex media. The continuity of fluid pressure and velocity at the interfaces of various seepage fields constitutes the boundary conditions for the transition of groundwater in different flow zones.

[0075] 4) Characteristic coefficients summarized from actual production process experiments

[0076] Clearly defining the characteristics of rough seepage allows for analysis of the influence of roughness, fracture width, and flow rate on wavy and planar fracture water seepage, identification of the critical points for Darcy flow and non-Darcy flow, and modification of the fracture seepage-pressure drop equation. However, Navier-Stokes turbulent flow, Darcy laminar flow, and Forchheimer flow are relatively easy to simulate in the laboratory. In actual production processes, head loss in the middle section of the seepage characteristics can be ignored, and the rough seepage characteristics can be explained more by generalizing the comparison of available pressure head at the initial and final ends.

[0077] Based on some seepage characteristics in the North China coalfield, researchers have compiled statistics on the seepage properties of some sandstone and carbonate rock strata. According to actual data from mine pre-drainage, the rough seepage characteristics of sandstone water, the main overlying aquifer in the North China coalfield, cause a head pressure loss of approximately 60%.

[0078] At a depth of 1000m in the surface drilling, the water head pressure formula is ρgh, and the water pressure is about 10MPa. However, when pressure observation is carried out in the well for the advance drainage of sandstone water, the drainage water pressure only reaches 4MPa due to the influence of rough seepage characteristics, and the characteristics are mostly consistent with Forchheimer flow.

[0079] 5) Investigation, research and theoretical summary on interlayer karst

[0080] During the formation of paleokarst, primary karst is rarely preserved due to crustal movement; most existing karst consists of secondary fissures eroded by various fluids. Currently, there is no unified definition of interlayer karst, but based on actual exploration data, this layer, formed during the paleokarst formation period, differs from the weathering crust of thick, unweathered bedrock. Its structure is often loose, consisting of gullies, nodules, or basal gravels. This structure facilitates the intrusion and dissolution of primary gases and fluids, forming excellent water flow channels.

[0081] One prominent location of interlayer karst in North China is a weathered layer approximately 50m thick, situated beneath the coal-bearing strata and atop the Ordovician karst limestone. This layer is characterized by well-developed dissolution, high permeability, insignificant anisotropy, fractured rock, partial argillaceous content, and poor rock mass integrity. Multiple pressure tests using carbonate rock pumping have demonstrated that even with frequent pumping, the pressure drop in this aquifer is small, and the impact of rough seepage is minimal, conforming to the Darcy flow formula. Through repeated drilling operations, open-hole testing, large-scale pumping tests, downhole geophysical exploration, and tracer experiments, the characteristics of this interlayer karst in the area have been identified as suitable for generalization as an underground confined reservoir. In non-interlayer seepage zones, within the structurally fractured carbonate strata, fluid seepage is predominantly Forchheimer flow, partially Darcy laminar flow, and a small portion of Navier-Stokes turbulent flow.

[0082] See also Figure 3 If the underground environment lacks the conditions for constructing water pipelines (this is determined based on the actual conditions of the mine; if the mining depth is narrow and construction is difficult, then construction is not feasible), the water must be treated before reinjection to form good water for reinjection and ensure the geological and ecological environment. Water-rock ion exchange is a long-term and complex geological process. Water prematurely released from underground coal mines, after water treatment, purifies its soluble and readily soluble salts. Through long-term recycling, due to the rapid renewal rate of groundwater, the ionic composition of surface and groundwater tends to become more uniform.

[0083] Figure 3 The construction method shown can be combined with the geological occurrence to form a horizontal off-site reinjection through surface pipelines. Off-site reinjection expands the water circulation path and increases the time for water circulation back to the pumping area. In special circumstances, it provides a time buffer for dealing with sudden situations downhole. Figure 2 and Figure 3 The injection wells and reinjection wells are located in different places, but belong to the same stratum. After being injected and reinjected in different areas, the water is transported in the underground strata, which is called ex-situ reinjection.

[0084] Figure 3The construction method shown can also be combined with heat pump heating and geothermal energy storage. Because coal has a low thermal conductivity, the lower coal seam has insulation properties, making it suitable for heat storage. Groundwater possesses not only potential energy but also thermal energy; heat pumps can extract heat from the water for heating, a relatively mature utilization method. Geothermal energy storage refers to storing waste heat from domestic or photovoltaic power generation as a resource, using water as the storage medium to store the thermal energy in the ground. Figure 3 The construction method shown is only applicable to mines where mining operations have been completed; otherwise, heat conduction may affect underground mining operations.

[0085] Step 2: High-pressure grouting is performed to seal the energy boreholes during construction, and a high-pressure blowout preventer valve and pressure gauge are installed at the borehole opening.

[0086] See Figure 2 High-pressure grouting is used to seal the energy wells during construction to ensure mining safety. High-pressure blowout preventers and pressure gauges are installed at the wellheads. Multiple sets of high-pressure blowout preventers can be installed depending on the pressure conditions. The high-pressure blowout preventers control the water flow at the outlet to determine when to release water. The pressure gauges monitor the water pressure at the high-pressure blowout preventers.

[0087] Step 3: Install a hydroelectric turbine unit behind the high-pressure blowout preventer valve. By changing the placement of the hydroelectric turbine unit, the direction of water flow is changed, and the water pressure is converted into angular momentum, which is then converted into electrical energy.

[0088] See Figure 2 A hydroelectric turbine unit is installed downstream of the high-pressure blowout preventer valve, using the pressure of the released water to provide stable power for electricity generation. By altering the water flow direction through the placement of the hydroelectric turbine unit, the water pressure is converted into angular momentum, which is then converted into electrical energy, thus improving the power generation efficiency based on pressure drop. Multiple hydroelectric turbine units can be placed to fully utilize the potential energy difference. The function of the hydroelectric generator unit is to convert water pressure (water potential energy) into electrical energy, and its principle is similar to that of a hydroelectric power station.

[0089] Step 4: Construct an underground water tank and guide the sprayed water into the underground water tank through a closed water pipe.

[0090] This invention treats the Ordovician limestone water storage tank as an equivalent underground water reservoir, the location of which varies in different coal mines. See also Figure 2 The construction involves creating an underground water reservoir. Water from the blowout is diverted into the reservoir via a closed-loop water pipe. The size of the reservoir can be determined based on the water volume obtained from exploration and release, and to match peak and off-peak water flow. Considering economic factors, the size of the underground water reservoir should be determined based on the release capacity of the high-pressure blowout preventer valve, with a minimum capacity sufficient to withstand 12 hours of natural water release. In special circumstances, additional reservoirs can be added to meet 1-3 days of downhole drainage needs.

[0091] Step 5: Place a horizontal pump near the underground water tank to pump the water from the underground water tank into the surface water treatment station for physical removal of impurities and scale.

[0092] See Figure 2 A horizontal pump is placed near the underground water reservoir to pump out the water. The pumped water flows through a return water pipe in the auxiliary shaft into a simple surface water treatment station for physical removal of impurities and scale. The auxiliary shaft refers to a large vertical shaft used in the coal industry for normal personnel access and drainage. Mining operations typically generate water inrushes; the return water pipe in this invention refers to a surface pipe that pumps the water out and then pumps it back underground. The water treatment station is set up to achieve "good water reinjection" when water quality varies.

[0093] Step 6: The descaled water is then used in a water separation project or poured into a surface reservoir.

[0094] See Figure 2 After descaling, the water can be used in a water separation project for purposes such as heat extraction. If water separation is not required, it can be pumped into a surface reservoir. Surface reservoirs are mainly for supplementing groundwater storage and are not primary special-needs facilities. Some mines have surface open pits or surface water bodies, which can also be used as alternatives if the water quality meets the requirements.

[0095] Surface reservoirs refer to reservoirs on the surface that can store water. They are set up to alleviate the pressure on underground water storage; if the water pressure is not high, this can be omitted. Differentiated water use engineering is a general term; in this invention, it refers to water-consuming projects that can be used for irrigation, production, etc., depending on the different water quality types.

[0096] Step 7: Construct the Ordovician limestone well, pump out the water from the surface reservoir using a water pump, remove sand, and then recharge it into the mining layer.

[0097] See Figure 2 The construction of Ordovician limestone strata reinjection wells (referred to as Ordovician limestone wells) involves pumping water from the surface reservoir out of the reservoir, removing sand, and then reinjecting it into the mining layer.

[0098] Ordovician limestone wells are wells that reinject water back into the original aquifer. To ensure that the groundwater environment is not affected, water is injected back into the original aquifer as much as possible (in this invention, Ordovician limestone aquifer is used as a metaphor). A water pump is a power pump used by a surface reservoir to pump water back into the well; it can be omitted if there is no surface reservoir.

[0099] Due to the characteristics of coal seam occurrence and the uncertainty of underground strata fractures, and considering both production safety and the difficulty of construction in certain narrow roadways, this invention proposes a specific construction method combining surface construction in Ordovician limestone wells to reduce technical difficulty and increase the universality of the method. For example... Figures 4 to 6 As shown.

[0100] Figure 4 This is a schematic diagram illustrating the construction of the sealing wall and the laying of pipes in the surface construction method for Ordovician limestone wells of the present invention. See also... Figure 4 The present invention discloses a surface construction method for Ordovician limestone wells. First, a sealing wall is added within the roadway. The construction method involves infiltrating the roadway with water or mud. After the sealing wall is constructed, the Ordovician limestone well is precisely located and constructed on the surface. The construction of the Ordovician limestone well should penetrate the mining roadway strata and extend into the lower strata, ideally reaching the critical stratum above the interlayer karst. Then, the completed Ordovician limestone well is piped, using high-strength steel pipe or oil casing. After pipe laying, high-pressure grouting is performed on the outside of the pipe, forming a filling body near the sealing wall. Quick-setting cement can be used as the grouting material.

[0101] Using high-strength steel pipes can extend the service life of the equipment; oil casing can also be used. The sealing wall is located on both sides of the reinjection well in the underground tunnel and is a pre-sealing facility to prevent water from entering the tunnel during construction. The filling material refers to the cement, water glass, etc., injected downwards through the wellbore after the reinjection well has reached a certain depth for well cementing. After cementing, the reinjection well steel pipe and the formation form a tight bond. Because the cement and water glass are fluids during injection, a solidified filling material is formed at the sealed tunnel location, serving two purposes: stabilization and water blocking. High-pressure grouting can cause the filling fluid to block general fractures.

[0102] Figure 5 This is a schematic diagram illustrating the process of installing horizontal pipes in the surface construction method for Ordovician lime wells according to the present invention. See also... Figure 5 After the grouting cement cools, the tunnel is excavated from the underground roadway towards the surface construction site of the Ordovician limestone well, penetrating the sealing wall and filling material, and welding the horizontal high-strength steel pipe to the vertical steel pipe. The vertical steel pipe is not cut at the weld joint to facilitate further construction. High-pressure valves and pressure gauges are installed on the horizontal high-strength steel pipe to complete this horizontal operation.

[0103] Figure 6 This is a schematic diagram illustrating the drilling and pipe connection process in the surface construction method for Ordovician limestone wells of the present invention. See also... Figure 6 The drilling continues from the surface to the vertical Ordovician limestone well, proceeding downwards to the karst zone or water-rich triangle area between the Ordovician limestone strata. In the karst zone between the Ordovician limestone strata, open boreholes or bridge-type filter pipes are used. After the well reaches the appropriate depth, perforation or cutting is performed at the connection points between the vertical and horizontal wells to create a communicating vessel effect. At this point, under the original geological conditions, the isobaric head line is much higher than the horizontal position of the tunnel.

[0104] The conceptual model of the Ordovician lime well of this invention is as follows: Figure 7As shown, the Ordovician limestone karst is used as a large-scale equivalent reservoir. The constructed Ordovician limestone well (geothermal well) is equivalent to a water communication device. The horizontal vent installed in the geothermal well tunnel has equivalent water pressure. The auxiliary well is used to complete the pumping and injection water circulation, forming a water flow circulation.

[0105] In recent production processes, through technical analysis, seismic data identification, construction drilling, and capacity testing, a seepage layer with a rough seepage coefficient resulting in less pressure loss was discovered. This seepage layer can be considered equivalent to a conceptual underground reservoir. The equivalent water velocity, equivalent water flow rate, and equivalent total water storage under recharge runoff conditions can be calculated.

[0106] This invention provides a method for mine water treatment and mine water energy utilization with broad applicability, but it requires a certain level of technical expertise from the construction team and carries high construction risks. Therefore, this invention proposes... Figure 3 The construction method for downward energy well construction in the lower coal seam roadway, as shown, is applicable to coal seam roadways adjacent to high-pressure aquifers, preventing construction risks. Furthermore, it provides... Figures 4 to 6 The surface construction method for Ordovician limestone wells shown is a safe, reliable construction method with low technical requirements and strong risk prevention capabilities.

[0107] Furthermore, the mine water treatment and mine water energy utilization method of the present invention has the following advantages:

[0108] Interlayer karst systems are stable permeable channels that have been repeatedly verified in geothermal development and utilization. Natural groundwater gradient slopes can be formed through grouting or curtain technology. The volume of a virtual reservoir can be predicted based on hydrogeological coefficients, elastic release coefficients, interlayer karst thickness, and water storage coefficients.

[0109] Inclined coal seam mining can be combined with Ordovician limestone hydrothermal mining. The extraction of karst geothermal water can lead to advanced drainage or water blocking due to the formation of fallout cones, which can promote the safety of coal mining.

[0110] Water exploration and drainage in the sandstone above the coal seam can be used for advanced drainage and hydropower generation. Based on general hydropower calculation experience and the head drop ratio observed at the top and bottom, the head drop conversion efficiency to electricity is about 30%.

[0111] Extensive data demonstrates that the infiltration of karst water between layers largely conforms to Darcy's principle of flow. Advanced drainage of the karst interlayers beneath the coal seam is utilized for hydroelectric power generation, converting water head and pressure drop into electrical energy with a conversion efficiency exceeding 60%.

[0112] When mining the upper coal seam, due to the thick interlayer between the coal seam and the Ordovician limestone layer, high-pressure sealing should be carried out using double-casing drilling technology as much as possible, under the condition that the technology is controllable. Grouting should avoid seeping into the interlayer karst area, so as not to waste grouting materials.

[0113] When mining the next coal seam, the interlayer between the coal seam and the Ordovician limestone layer is relatively thin. Grouting can be used to seal the karst area between the layers. Suitable locations for specific fracture extensions can be found, and water exploration and drainage holes can be constructed into the karst triangle area for water extraction. However, this measure increases the water seepage distance and is located within the structural water-conducting system. Its kinetic energy may be lost by 10%–30% due to rough seepage. The specific loss should be determined based on the fracture moment width and the structural water conductivity.

[0114] This invention can be used for water hazard control in large-scale mines with water bodies above. By controlling the irrigation volume (through valve control) and adjusting the pressure head (through pressure gauges and valves), water hazard problems in production mines can be solved. Water hazards are dynamic, and pre-emptive drainage also provides a method for controlling the deterioration of mine water quality, representing a way to utilize mine water hazards as resources. By using pre-emptive drainage to drain and discharge water in advance, it is possible to avoid the flow of water-rich strata during production, thus preventing mine water hazards.

[0115] This invention's method can be used for peak shaving and valley filling in new energy power. During off-peak hours, electricity is used for pumping water, and during peak hours, water is released. Energy is converted between potential energy and electrical energy and back to potential energy. Due to the characteristics of interlayer karst, it can be considered as a communicating vessel, and the seepage flow basically conforms to Darcy's law. This energy conversion efficiency is high, and it has good development and utilization prospects. Interlayer karst, as a geological body widely existing in North China, exists in a three-dimensional, broad, and spatially extensive form. Under natural seepage at equal pressure heads, it can also be considered as independently constituting upper and lower reservoir conditions. Its development and utilization can overcome the limitations of pumped storage regional applications and has a wider range of applications.

[0116] When the method of this invention is used for peak shaving and valley filling, water is released to generate electricity when the electricity price is high, and water is pumped to the surface or reinjected when the electricity price is low. The principle is the same as that of pumped storage power stations.

[0117] Furthermore, the method of this invention successfully brings pumped-storage hydroelectric power underground by utilizing the hydraulic characteristics of karst interlayers in the Ordovician system and underground coal mine tunnels. The proof of the usability of karst interlayers is the result of long-term experimental verification by geothermal geologists based on relevant experiments with carbonate rock thermal reservoirs. Simultaneously, based on practical experience and statistical data, and combined with the concept of serving mine production, this invention innovatively proposes a construction method for underground pumped-storage power stations. This method is a geological interpretation for peak shaving and valley filling, water hazard control, and advanced drainage and synergistic utilization of coal, water, and heat.

[0118] Since the entire system is essentially a closed-loop system, no water-rock reaction occurs, and it is considered intra-layer water recharge, resulting in minimal environmental impact. Minor impacts (such as sedimentation and flocculation caused by water oxidation) can be addressed through water treatment methods, thus constituting "good water recharge."

[0119] Furthermore, the method of this invention, after sealing with curtain grouting technology, can also be applied to large-water metal mines with water bodies above and fractured connecting mining roadways, solving the economic problem of drainage in large-water metal mines. The specific construction method involves first sealing the main water outlets, then diverting the water during construction to utilize the previously disorderly discharged water.

[0120] Furthermore, the method of the present invention is applicable to production mines in conjunction with advanced drainage, and can also be used for pumping and storage for peak shaving and valley filling after the end of the mining life cycle, making full use of underground development facilities and improving the economic efficiency and life cycle of facility construction.

[0121] Furthermore, in the method of this invention, confined aquifers possessing pressure and overflow conditions, reliable seepage channels, and a certain considerable seepage flow rate can all be considered as energy storage tanks. Confined aquifers possessing potential energy differences and top old kiln water, as well as those possessing top water accumulation and reservoir characteristics, are also application scenarios. Combining curtain grouting can be one way to utilize the method of this invention.

[0122] Furthermore, in the method of this invention, the water volume can be calculated by referring to methods such as the large well method and the narrow tunnel method to estimate the drainage volume, or it can be based on actual monitoring of the drainage volume. Energy utilization can refer to the energy utilization formula for hydroelectric power generation.

[0123] The formula for the large well method is:

[0124]

[0125] The calculation formula for the horizontal tunnel method is:

[0126]

[0127]

[0128] The energy calculation equation for the power that can be generated is:

[0129]

[0130] Furthermore, the method of this invention requires less investment and has a wide range of applications. Currently, the peak-hour electricity price is eight times that of off-peak electricity price. By utilizing the negative peak electricity from wind and solar power generation and the peak-valley price difference to implement pumped storage, the method of this invention has high economic efficiency.

[0131] Furthermore, the surface construction method for the Ordovician limestone well of the present invention can utilize the underground space to construct a large-scale peak-shaving energy storage power station (construction of multiple sets of reinjection holes and blowout preventers plus generator sets, utilizing the pressure difference between underground water and surface water to construct a peak-shaving energy storage power station), with relatively low investment.

[0132] This invention's method can be applied to production mines. Due to the need for advanced drainage and peak-shaving pumping, the volume of underground pumps increases significantly, and this increased volume is part of the engineering construction. The increased pumping capacity enhances emergency response capabilities during underground construction, correspondingly reducing potential losses of life and property caused by water hazards and improving the safety of the mining production process.

[0133] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0134] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for mine water treatment and mine water energy utilization, characterized in that, include: In the case of drainage, energy wells are constructed downwards or upwards in coal mine roadways, specifically including: When mining a lower coal seam, locate the fracture and construct an energy borehole. The fracture extends 100-300m below the interlayer karst, connecting the interlayer karst zone. The construction sequence is as follows: first, construct into the interlayer karst zone, grout the karst, and seal it to form a stable filling body; then, penetrate the filling body and construct into the influence zone of the structural and interlayer composite triangle with water-conducting properties. When there are no conditions for constructing a water pipeline underground, the water is treated and reinjected to form good water reinjection. The structural and interlayer composite triangle refers to the composite location of geological fracture and fissure structures and water-rich interlayer karst areas. Fracture and fissure structures refer to the suture sites of fractures, cracks, and dislocations in the sedimentary strata. High-pressure grouting is used to seal the energy holes during construction, and high-pressure blowout preventers and pressure gauges are installed at the openings of the energy holes. A hydroelectric turbine unit is installed behind the high-pressure blowout preventer valve. The water flow direction is changed by the placement of the hydroelectric turbine unit, and the water flow pressure is converted into angular momentum, which is then converted into electrical energy. The construction of the underground water tank involves introducing the sprayed water into the underground water tank through a closed water diversion pipeline. A horizontal pump is placed near the underground water reservoir to pump the water from the reservoir into a surface water treatment plant for physical removal of impurities and scale. After descaling, the water is either used in water separation projects or injected into surface reservoirs. The construction of the Ordovician limestone well involves pumping water out of the surface reservoir, removing sand, and then reinjecting it into the mining layer.

2. The method for mine water treatment and mine water energy utilization according to claim 1, characterized in that, Multiple sets of high-pressure blowout preventers are provided; the high-pressure blowout preventers are used to control when water is released; the pressure gauge is used to monitor the water pressure at the high-pressure blowout preventers.

3. The method for mine water treatment and mine water energy utilization according to claim 1, characterized in that, Multiple hydroelectric turbine units are installed to convert water pressure into electrical energy.

4. The method for mine water treatment and mine water energy utilization according to claim 1, characterized in that, The size of the underground water reservoir should be determined based on the amount of water obtained from exploration and release and to match the peak and valley time differences. It should be able to hold at least 12 hours of natural water release.

5. The method for mine water treatment and mine water energy utilization according to claim 1, characterized in that, The head pressure drop in the structure and the interlayer composite triangular zone conforms to Darcy's law and Forchheimer flow.

6. The method for mine water treatment and mine water energy utilization according to claim 1, characterized in that, The construction of the Ordovician limestone well specifically includes: Add sealing walls in the coal mine roadway. After the sealing walls are built, locate and construct the Ordovician limestone well on the surface. The Ordovician limestone well passes through the mining roadway strata and goes deep into the lower strata, and is constructed to the critical strata above the interlayer karst. Pipes were lowered into the already constructed Ordovician limestone wells. After the pipes were lowered, high-pressure grouting was performed on the outside of the pipes, and a filling body was formed near the sealing wall. After the grouting material cools down, the tunnel is excavated from the underground roadway to the surface construction site of the Ordovician limestone well, breaking through the sealing wall and filling body, and welding the horizontal pipes to the vertical pipes. The vertical pipes are not cut at the weld joint. Install high-pressure blowout preventers and pressure gauges on the horizontal pipes to complete this horizontal operation; Continue drilling from the surface to the vertical Ordovician limestone well, drilling downwards to the karst zone between the Ordovician limestone karst layers or the complex triangular zone. In the karst zone between the Ordovician limestone karst layers, bare holes or bridge-type filter pipes are used. After the Ordovician limestone well is constructed to the corresponding hole depth, the connection between the vertical and horizontal pipes is perforated or cut to open up the channel between the horizontal and vertical Ordovician limestone wells, forming a communicating vessel effect. The Ordovician limestone karst mass is used as a large-scale equivalent reservoir. The constructed Ordovician limestone well is equivalent to a water body communicating vessel. The horizontal vent installed in the geothermal well tunnel has equivalent water pressure. The auxiliary well is used to complete the pumping and injection water circulation, forming a water flow circulation.

7. The method for mine water treatment and mine water energy utilization according to claim 6, characterized in that, The pipe used for installation is a high-strength steel pipe or an oil casing.

8. The method for mine water treatment and mine water energy utilization according to claim 6, characterized in that, The high-pressure grouting material uses quick-setting cement.

9. The method for mine water treatment and mine water energy utilization according to claim 1, characterized in that, Also includes: When electricity prices are high, water is released to generate electricity; when electricity prices are low, water is pumped to the surface or reinjected.

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