Mine water underground treatment system and method

Abstract

The invention relates to a mine water underground treatment system and method.The system comprises a pre-sinking water bin, a first goaf, a second goaf, a direct filtration assembly and a reverse osmosis assembly, suspended solids and hardness ions in mine water are removed step by step through the multiple goaf stages, and direct filtration and reverse osmosis desalination treatment are combined; the mine water purification treatment process is efficient and stable, the link of lifting the mine water to the ground is omitted, the investment and operation cost of ground facilities is reduced, treated desalted purified water can meet the requirements of production, dust fall, fire fighting water and the like, the water resource recycling rate is greatly increased, and obtained strong brine can be stored in a closed mode underground to achieve zero emission. And the environmental protection benefit is improved.

Description

Technical Field

[0001] The present disclosure relates to an underground mine water treatment system and method. Background Art

[0002] With the improvement of environmental protection requirements and the enhancement of water resource protection awareness, the treatment of mine water, especially high salinity mine water, has become a key environmental protection link in coal mining. High salinity mine water refers to mine water with a salt content exceeding 1000 mg / L in water. Traditional treatment methods include three main process sections: pretreatment, concentrated salt separation, and evaporation crystallization. Among them, pretreatment often uses methods such as double-alkali softening, chemical flocculation, and ion exchange to remove calcium, magnesium, silicon, fluorine, barium and other ions in mine water to avoid or reduce scaling and corrosion problems in subsequent processes. Concentrated salt separation reduces the total solid content in mine water on the one hand to ensure that the effluent meets the requirements of recycled water quality, usually using membrane concentration methods such as multi-stage reverse osmosis and high-pressure reverse osmosis. On the other hand, methods such as nanofiltration are used to separate monovalent and divalent cations in water to provide a basis for subsequent salt separation and crystallization. Evaporation crystallization is to crystallize and precipitate salt ions in the membrane concentrated solution to achieve salt-water separation and ultimately realize zero discharge of mine water.

[0003] Existing zero-discharge treatment technologies for high salinity mine water have problems such as long process flow, complex system, high cost, and difficult disposal of by-product salts. For example, there are certain amounts of Ca 2+ , Mg 2+ , SO4 2- , HCO3 - and other scaling ions in high salinity mine water. To meet the water quality requirements for membrane concentration and evaporation crystallization, multiple hardness removals are required, accompanied by excessive dosing of hardness removal agents. The membrane concentration process also requires multi-stage concentration to meet the concentration requirements. As the concentration of the concentrated solution increases, the operating pressure of membrane concentration gradually increases, greatly increasing the system energy consumption and safety risks. The evaporation crystallization process requires a large amount of steam to separate the salt in the concentrated brine in the form of single salt, with high equipment investment and operating costs. In addition, the miscellaneous salts generated during the treatment of high salinity mine water are difficult to further utilize, forming a new environmental burden. Summary of the Invention

[0004] The purpose of the present disclosure is to provide an underground mine water treatment system and method with a simple process, low cost, and good treatment effect.

[0005] To achieve the above purpose, in the first aspect of the present disclosure, an underground mine water treatment system is provided, which includes: A pre-sedimentation sump for pre-sedimenting mine water to obtain pre-sedimented mine water; A first goaf for receiving the pre-sedimented mine water and removing suspended solids therein through rock mass filtration to obtain filtered mine water; The second goaf is used to receive the filtered mine water, provide a hardness removal agent to contact with the filtered mine water for hardness removal reaction, and obtain the mine water after hardness removal; The direct filtration component is used to directly filter the mine water after hardness removal to obtain the directly filtered mine water; The reverse osmosis component is used to desalt the directly filtered mine water to obtain desalted purified water and concentrated brine.

[0006] Optionally, the second goaf is equipped with a hardness removal agent dosing device, and the hardness removal agent includes at least one of Na2CO3, NaOH, Ca(OH)2, CaO, and gypsum.

[0007] Optionally, the hardness removal agent dosing device includes an automatic dosing module for determining the dosage of the hardness removal agent according to the hardness level of the filtered mine water and dosing the hardness removal agent according to the dosage.

[0008] Optionally, the system further includes: An intermediate water tank is connected between the direct filtration component and the reverse osmosis component and is equipped with an acidity adjustment device for adjusting the pH value of the directly filtered mine water to be acidic.

[0009] Optionally, the reverse osmosis component includes a concentration detection module for detecting the concentration of the concentrated brine; The first goaf is further used to receive the concentrated brine with a concentration lower than a preset threshold.

[0010] Optionally, the system further includes: A third goaf is used to receive and store the concentrated brine with a concentration exceeding the preset threshold; Preferably, the third goaf is equipped with a concentrated brine diffusion monitoring module for real-time monitoring of the concentration and diffusion of the concentrated brine.

[0011] In a second aspect of the present disclosure, there is provided a method for treating mine water using the system described in the first aspect of the present disclosure. The method includes: Let the mine water be pre-settled in a pre-settlement sump to obtain pre-settled mine water; Let the pre-settled mine water pass through rock mass filtration in the first goaf to remove suspended solids therein to obtain filtered mine water; Let the filtered mine water contact with a hardness removal agent in the second goaf for hardness removal reaction to obtain mine water after hardness removal; Let the mine water after hardness removal be directly filtered by a direct filtration component to obtain directly filtered mine water; Let the directly filtered mine water be desalted by a reverse osmosis component to obtain desalted purified water and concentrated brine.

[0012] Optionally, the method further includes: adjusting the pH value of the directly filtered mine water to be acidic, and then performing the desalination treatment; and / or, The method further includes: detecting the concentration of the concentrated brine, and when the concentration of the concentrated brine is lower than a preset threshold, introducing the concentrated brine into the first goaf for cyclic treatment; when the concentration of the concentrated brine exceeds the preset threshold, introducing the concentrated brine into the third goaf for storage.

[0013] Optionally, the residence time of the mine water in the pre-sedimentation sump is 4 to 10 h; The residence time of the mine water in the first goaf is 4 h to 60 days; The residence time of the mine water in the second goaf is 4 h to 60 days; The conditions for the direct filtration treatment include: the direct filtration membrane flux is 30 to 150 L / (m 2 ·h), and the operating pressure is 0.2 to 0.3 MPa; The conditions for the desalination treatment include: the reverse osmosis membrane flux is 15 to 120 L / (m 2 ·h), and the operating pressure is 0 to 2 MPa.

[0014] Optionally, the TDS of the mine water is 1000 to 10000 mg / L, the turbidity is 0 to 10000 NTU, and the total hardness in terms of CaCO3 is 20 to 2000 mg / L; The TDS of the filtered mine water is 1000 to 10000 mg / L, the turbidity is 0 to 100 NTU, and the total hardness in terms of CaCO3 is 20 to 2000 mg / L; The TDS of the mine water after hardness removal is 1000 to 10000 mg / L, the turbidity is 0 to 100 NTU, and the total hardness in terms of CaCO3 is 1 to 100 mg / L; The TDS of the directly filtered mine water is 1000 to 10000 mg / L, the turbidity is 0 to 0.5 NTU, and the total hardness in terms of CaCO3 is 1 to 100 mg / L.

[0015] Through the above technical solutions, the present disclosure uses multiple goafs to stepwise remove suspended solids and hardness ions in mine water, and combines direct filtration and reverse osmosis desalination treatment, making the mine water purification process efficient and stable, eliminating the link of lifting mine water to the ground, reducing the investment and operating costs of ground facilities, the desalinated purified water after treatment can meet the needs of production, dust suppression and fire fighting water, etc., greatly improving the water resource recycling rate, and the obtained concentrated brine can achieve zero discharge through underground closed storage, enhancing the environmental protection benefits.

[0016] Other features and advantages of the present disclosure will be described in detail in the following detailed implementation section. Description of the Drawings

[0017] The drawings are used to provide a further understanding of the present disclosure and constitute a part of the specification. Together with the following detailed implementation, they are used to explain the present disclosure, but do not constitute a limitation to the present disclosure. In the drawings: Figure 1 It is a schematic diagram of the structure and process of an underground mine water treatment system in a specific implementation.

[0018] Figure 2 It is a schematic diagram of the structure and process of an underground mine water treatment system in another specific implementation.

[0019] Description of the Reference Numerals 1 - Pre - sedimentation sump, 2 - First goaf, 3 - Second goaf, 4 - Direct filtration module, 5 - Reverse osmosis module, 6 - Third goaf, 7 - Mine water, 8 - Pre - sedimented mine water, 9 - Filtered mine water, 10 - Hardness - removed mine water, 11 - Direct - filtered mine water, 12 - Desalted purified water, 13 - Concentrated brine, 14 - Hardness - removal agent. Detailed Implementation

[0020] The following details the specific implementation of the present disclosure in conjunction with the drawings. It should be understood that the specific implementation described herein is only for the purpose of explaining and understanding the present disclosure and does not limit the present disclosure.

[0021] In the first aspect of the present disclosure, an underground mine water treatment system is provided. Referring to Figure 1 , the system includes: A pre - sedimentation sump 1 for pre - sedimenting mine water 7 to obtain pre - sedimented mine water 8; A first goaf 2 for receiving the pre - sedimented mine water 8 and removing suspended solids therein by rock filtration to obtain filtered mine water 9; A second goaf 3 for receiving the filtered mine water 9, providing a hardness - removal agent 14 to contact with the filtered mine water for a hardness - removal reaction to obtain hardness - removed mine water 10; A direct filtration module 4 for directly filtering the hardness - removed mine water 10 to obtain direct - filtered mine water 11; A reverse osmosis module 5 for desalting the direct - filtered mine water 11 to obtain desalted purified water 12 and concentrated brine 13.

[0022] To solve the problems of complex existing mine water treatment processes, unstable operation, high costs, and difficult disposal of miscellaneous salts and by-product salts, the present disclosure proposes a mine water underground treatment system that makes full use of the advantages of large-space storage and low-cost purification in underground mined-out areas, and uses multiple mined-out areas in coordination to achieve economical, efficient, and safe treatment and utilization of mine water. The system of the present disclosure is particularly suitable for the treatment of high-salinity mine water. Specifically, the TDS (Total Dissolved Solids) of the mine water can be 1000-10000 mg / L, preferably 1000-6000 mg / L; the turbidity can be 0-10000 NTU, preferably 0-5000 NTU; the total hardness in terms of CaCO3 can be 20-2000 mg / L, preferably 20-1000 mg / L.

[0023] According to the present disclosure, the pre-sedimentation sump 1 is the primary treatment unit in the mine water underground treatment system of the present disclosure, and is used to receive the mine water collected underground and achieve the preliminary sedimentation of the mine water. This sump is usually located in the initial collection area of the mine water. Through physical sedimentation and gravity, impurities such as larger particles of coal powder and rock powder in the mine water are deposited in the sump to reduce the solid load in the subsequent treatment stage. The pre-sedimentation sump 1 can have a simple structure, for example, it is composed of anti-seepage materials to ensure that the mine water will not leak into the surrounding rock formations during the sedimentation process, and its capacity can be 200-8000 m 3 . The turbidity of the mine water can be initially reduced through the pre-sedimentation sump 1, providing a stable water quality basis for subsequent treatment.

[0024] The pre-sedimentation sump 1 is connected to the water inlet of the first mined-out area 2 through a water pipeline, and a conveying device can be configured on the pipeline to convey the pre-sedimented mine water 8 from the pre-sedimentation sump 1 to the first mined-out area 2.

[0025] According to the present disclosure, a mined-out area refers to the space or cavity left underground after ore body excavation, and is a key structural unit in the mine water treatment system of the present disclosure. The mined-out area has natural sedimentation, filtration, and water storage capabilities, and can be used for multi-stage purification of mine water to achieve physical filtration of suspended solids and sedimentation reactions of hardness ions.

[0026] The first goaf 2 can be a goaf formed with a large amount of caving rock mass. By utilizing the natural porous structure of the rock mass, effective removal of suspended particles, organic matter, characteristic ions, etc. in the mine water can be achieved, turbidity can be reduced, and there is no need to add chemical agents (such as flocculants), which improves the economy, reliability, and safety of the system. The capacity of the first goaf 2 can be 1 million to 5 million cubic meters. The mine water can stay in it for a long time, so as to achieve sufficient filtration. Its structure can be designed according to actual needs. For example, for mine water with a high suspended solid content, the first goaf 2 can be designed as a multi-layer structure to increase the sedimentation path and residence time of the mine water.

[0027] The first goaf 2 has a water inlet and a water outlet. The water inlet can be set at the upper part of the goaf to provide a sedimentation path for the mine water from top to bottom. The water outlet can be located downstream and can be provided with a filter screen or an interception device to further capture larger sediment particles and prevent pipeline blockage. The water outlet of the first goaf 2 is connected to the water inlet of the second goaf 3 through a water pipeline. A conveying device can be configured on the pipeline to convey the filtered mine water 9 from the first goaf 2 to the second goaf 3.

[0028] The second goaf 3 is a deep hardness removal unit in the underground mine water treatment system of the present disclosure, which is used to remove calcium and magnesium ions in the mine water and reduce the hardness. The second goaf 3 can be located downstream of the first goaf 2. Its capacity can be 1 million to 5 million cubic meters, which can provide a long residence time for the mine water, enabling the hard scale in the mine water to fully settle and obtaining the desired hardness removal effect. At the same time, by utilizing the ultra-large space of the goaf, the hardness removal sludge does not need to be further disposed of and can be directly deposited at the bottom of the second goaf 3, avoiding secondary pollution and reducing the transportation, treatment, and storage costs of the sludge. Its structure can be designed according to actual needs. For example, the second goaf 3 can be designed as multiple partitioned areas, and alkaline agents with different concentrations and different types are gradually added to enable the hardness removal reaction to fully proceed in each stage area.

[0029] In a specific embodiment, the second goaf 3 is configured with a hardness removal agent dosing device for providing the hardness removal agent 14. The hardness removal agent can include at least one of Na2CO3, NaOH, Ca(OH)2, CaO, and gypsum. The hardness removal agent dosing device can include a storage chamber for storing the hardness removal agent, a metering pump for precisely controlling the dosing amount, a mixer for fully mixing the hardness removal agent with the mine water, and a chemical agent conveying pipeline.

[0030] Further, the hardness removal agent dosing device may include a hardness monitoring module and an automatic dosing module. Among them, the hardness monitoring module is used to monitor the hardness level of the filtered mine water in real time, and the automatic dosing module is used to determine the dosage of the hardness removal agent according to the hardness level of the filtered mine water and dose the hardness removal agent according to the dosage, so as to realize the dynamic adjustment and precise dosing of the hardness removal agent dosage, provide better influent conditions for subsequent treatment, extend the service life of the direct filtration component and the reverse osmosis component, and ensure the long-term stable operation of the system in the mine environment.

[0031] The hardness removal agent dosing device may be arranged at the water inlet of the second goaf 3. The water outlet of the second goaf 3 is connected to the water inlet of the direct filtration component 4 through a water pipeline. A conveying device may be configured on the pipeline to convey the mine water 10 after hardness removal from the second goaf 3 to the direct filtration component 4.

[0032] The direct filtration component 4 is used to further filter the impurities in the mine water after hardness removal. The direct filtration membrane component has stronger tolerance to underground suspended solids, and the membrane operation and maintenance are simpler, which is beneficial to reducing the underground operation difficulty. At the same time, it ensures that the water quality entering the reverse osmosis component meets the influent requirements and extends the service life of the reverse osmosis component. In a specific embodiment, the direct filtration component 4 may include a water inlet, a filtration unit, a water outlet and a sewage outlet. Among them, the water inlet is connected to the water outlet of the second goaf 3. The filtration unit may include a direct filtration membrane and a backwashing device. The direct filtration membrane includes, but is not limited to, a spiral wound membrane, a hollow fiber membrane, a flexible ceramic membrane, etc., and preferably has a higher membrane flux. Specifically, the membrane flux of the direct filtration membrane may be 30~150L / (m 2 ·h). The water outlet is connected to the water inlet of the reverse osmosis component 5, and the sewage outlet can be used to regularly discharge the intercepted impurities.

[0033] In a specific embodiment, the system further includes an intermediate water tank connected between the direct filtration component 4 and the reverse osmosis component 5, which is used for water quality buffering and pH value adjustment, preventing the reverse osmosis membrane from scaling, and improving the desalination efficiency and the service life of the reverse osmosis membrane. The intermediate water tank is configured with an acidity adjustment device for adjusting the pH value of the directly filtered mine water 11 to be acidic. Further, the acidity adjustment device may include a pH sensor, an acid storage tank, a metering pump and a dosing pipeline. The pH value of the directly filtered mine water 11 is preferably adjusted to below 6.5, and then flows into the reverse osmosis component 5 through the outlet pipeline of the intermediate water tank.

[0034] The reverse osmosis component 5 is the core desalination unit in the underground mine water treatment system of the present disclosure. The mine water is deeply purified through the reverse osmosis membrane to remove dissolved salts, heavy metal ions and trace pollutants in the water, so as to realize the desalination and purification treatment of the mine water, ensure that the quality of the effluent reaches the reclaimed water standard, and meet the water use requirements for production, dust suppression, fire fighting, etc. in the mine.

[0035] In one embodiment, the reverse osmosis assembly 5 may include a water inlet, a permeable membrane unit, a concentrated brine outlet, a desalted fresh water outlet, and a pressure pump. Among them, the water inlet is connected to the water outlet of the direct filtration assembly 4; the permeable membrane unit may include a multi-stage reverse osmosis membrane. Preferably, the reverse osmosis membrane has a relatively high membrane flux and a controllable salt rejection rate. Specifically, the membrane flux of the reverse osmosis membrane may be 15~120 L / (m 2 ·h), and the recovery rate may be 85~95%. This can effectively reduce the membrane usage, alleviate the corrosion of downhole equipment, and reduce the equipment maintenance cost and water usage cost; the desalted fresh water outlet may be connected to a fresh water storage tank for use inside the mine or in ground production.

[0036] In a preferred embodiment, the reverse osmosis assembly 5 includes a concentration detection module for detecting the concentration of the concentrated brine to determine whether it reaches the sealing concentration. At this time, the first goaf 2 is also used to receive the concentrated brine with a concentration lower than a preset threshold (for example, 60,000 mg / L). At this time, the first goaf 2 is also provided with a circulating water inlet, and the concentrated brine outlet of the reverse osmosis assembly 5 is connected to the circulating water inlet of the first goaf 2, so that the concentrated brine with a lower concentration can be circulated back into the first goaf 2 to be mixed with the mine water therein for treatment, effectively utilizing the underground space and reducing the waste amount of the concentrated brine.

[0037] Furthermore, referring to Figure 2 , the system may further include a third goaf 6 for receiving and storing the concentrated brine with a concentration exceeding the preset threshold (for example, 60,000 mg / L). At this time, the concentrated brine outlet of the reverse osmosis assembly 5 is also connected to the water inlet of the third goaf 6. In this way, the high-concentration concentrated brine can be reinjected in place to achieve true zero discharge. The location selection of the third goaf 6 is preferably a goaf without roof water seepage, and its capacity may be 100,000~5,000,000 cubic meters, which can provide a super-large space and closed conditions, and is suitable for the long-term closed storage of ultra-high-concentration concentrated brine to avoid the pollution risk to the surface environment. Preferably, the third goaf 6 is equipped with a concentrated brine diffusion monitoring module for real-time monitoring of the concentration and diffusion of the concentrated brine. Through this module, it can be ensured that the concentrated brine is safely stored in the third goaf and avoid the impact of concentrated brine leakage on the rock mass and groundwater environment. Specifically, the diffusion monitoring module may include a conductivity sensor, an ion concentration sensor, and a flow rate detector for detecting the concentration level and flow rate of the dissolved salts in the concentrated brine, identifying the diffusion trend, and providing real-time information on the diffusion range and concentration change of the concentrated brine.

[0038] In a preferred embodiment, the first goaf 2, the second goaf 3, and the third goaf 6 are respectively equipped with groundwater environment monitoring and early warning modules, which are used to monitor the key indicators of the goafs in real time and send out early warning signals when the parameters exceed the set range, helping to take effective prevention and control measures before potential risks occur to ensure the operation safety of the goafs. The key indicators include, for example, water quality parameters, water level parameters, dam body stress, etc., and data can be collected through common sensors in the art. The early warning signal can be in the form of audible and visual alarms, text message notifications, etc.

[0039] In one embodiment, the underground mine water treatment system of the present disclosure further includes a control module, which is used to intelligently monitor and regulate various key equipment and treatment parameters during the mine water treatment process. The control module is connected between key equipment such as the pre-sedimentation sump, the first goaf, the second goaf, the direct filtration component, the intermediate water tank, and the third goaf. By integrating functions such as water quality monitoring, chemical dosing, pH value adjustment, and diffusion warning, it realizes the automated management and optimization of the entire mine water treatment system. In a preferred embodiment, the control module adopts an adaptive control algorithm based on artificial intelligence, which can gradually optimize the control parameters of each node (such as the dosage of hardness removal agent, etc.) during the operation process and form historical data records for subsequent analysis and system optimization.

[0040] In the present disclosure, the pre-sedimentation sump, the first goaf, the second goaf, the direct filtration component, the intermediate water tank, the reverse osmosis component, and the third goaf are all arranged underground, realizing the reasonable utilization of underground space resources. There is no need to lift the mine water from underground to the ground for treatment, reducing the construction and operation costs of a large number of pumping stations and the occupation of ground resources. At the same time, it can realize the in-situ disposal of waste underground, reduce the sludge management requirements, improve the environmental protection benefits, and the desalted purified water after treatment can meet the needs of production, dust suppression, and fire fighting water, greatly improving the water resource reuse rate. The entire treatment system can operate stably for a long time, efficiently, and is more economical and energy-saving.

[0041] In the second aspect of the present disclosure, a method for treating mine water using the system described in the first aspect of the present disclosure is provided. The method includes the following steps S101 to S105: S101. Let the mine water be pre-sedimented in the pre-sedimentation sump to obtain the pre-sedimented mine water; Among them, the TDS of the mine water can be 1000-10000 mg / L, preferably 1000-6000 mg / L; the turbidity can be 0-10000 NTU, preferably 0-5000 NTU; the total hardness in terms of CaCO3 can be 20-2000 mg / L, preferably 20-1000 mg / L; the residence time of the mine water in the pre-sedimentation sump can be 4-10 h. The TDS of the pre-sedimented mine water can be 1000-10000 mg / L, preferably 1000-6000 mg / L; the turbidity can be 0-5000 NTU, preferably 0-3000 NTU; the total hardness in terms of CaCO3 can be 20-2000 mg / L, preferably 20-1000 mg / L.

[0042] S102. Let the pre-sedimented mine water pass through the rock mass in the first goaf to remove the suspended solids therein, and obtain the filtered mine water; Among them, the residence time of the mine water in the first goaf can be 4 h to 60 days. The TDS of the filtered mine water can be 1000-10000 mg / L, preferably 1000-6000 mg / L; the turbidity can be 0-100 NTU, preferably 0-40 NTU; the total hardness in terms of CaCO3 can be 20-2000 mg / L, preferably 20-1000 mg / L.

[0043] S103. Let the filtered mine water contact with a hardness removal agent in the second goaf to carry out a hardness removal reaction, and obtain the hardness-removed mine water; Among them, the residence time of the mine water in the second goaf can be 4 h to 60 days. The dosage of the hardness removal agent can be adjusted according to the total amount / quality of the filtered mine water and the type of the hardness removal agent. Specifically, based on 1 L of the filtered mine water, the dosage of the hardness removal agent can be 50-2000 mg. The TDS of the hardness-removed mine water can be 1000-10000 mg / L, preferably 1000-6000 mg / L; the turbidity can be 0-100 NTU, preferably 0-40 NTU; the total hardness in terms of CaCO3 can be 1-100 mg / L, preferably 1-60 mg / L.

[0044] S104. Let the hardness-removed mine water pass through a direct filtration component for direct filtration treatment to obtain the directly filtered mine water; Among them, the conditions for the direct filtration treatment can include: the direct filtration membrane flux is 30-150 L / (m 2·h), the operating pressure is 0.2~0.3 MPa; the TDS of the directly filtered mine water can be 1000~10000 mg / L, preferably 1000~6000 mg / L; the turbidity can be 0~0.5 NTU; the total hardness in terms of CaCO3 can be 1~100 mg / L, preferably 1~60 mg / L.

[0045] S105. Let the directly filtered mine water pass through a reverse osmosis module for desalination treatment to obtain desalted purified water and concentrated brine; Among them, the conditions for the desalination treatment may include: the reverse osmosis membrane flux is 15~120 L / (m 2 ·h), and the operating pressure is 0~2 MPa. The TDS of the desalted purified water can be 0~1000 mg / L; the turbidity can be 0~0.5 NTU; the total hardness in terms of CaCO3 can be 1~60 mg / L, preferably 1~40 mg / L.

[0046] Furthermore, the method may further include: adjusting the pH value of the directly filtered mine water to acidic, preferably below 6.5, and then performing the desalination treatment.

[0047] Furthermore, the method may further include: detecting the concentration of the concentrated brine. When the concentration of the concentrated brine is lower than a preset threshold (such as 60000 mg / L), introducing the concentrated brine into the first goaf for circulation treatment; when the concentration of the concentrated brine exceeds the preset threshold, introducing the concentrated brine into the third goaf for storage.

[0048] The method described in the second aspect of the present disclosure has all the beneficial effects of the system described in the first aspect of the present disclosure, which will not be elaborated here.

[0049] The following further illustrates the present disclosure through examples, but does not limit the present disclosure.

[0050] Among them, the operating cost is calculated based on the direct costs generated by the operation, including material costs such as chemicals, energy costs, labor costs, and depreciation costs; the water resource reuse rate is calculated by comparing the reused water volume with the corresponding total mine water volume. In the present disclosure, the reused water volume is the water volume excluding the water discharged as sewage.

[0051] Example 1 Adopt Figure 1 The system shown for underground treatment of mine water, and the specific steps include: Step 1: Pretreatment of mine water The mine water collected underground passes through a tank with a capacity of 200 m 3Underground sump pre-sedimentation with a residence time of 5 h; the TDS of mine water is 2000 mg / L, turbidity is 500 NTU, and total hardness is 300 mg / L (calculated as CaCO3); the TDS of the pre-sedimented mine water is 2000 mg / L, turbidity is 350 NTU, and total hardness is 300 mg / L (calculated as CaCO3); The clear water in the sump is pumped and injected into the water inlet point of the first goaf. The mine water is filtered and purified during the migration process in the first goaf with a capacity of 1 million cubic meters, and the residence time is 180 h; the TDS of the filtered mine water is 2000 mg / L, turbidity is 45 NTU, and total hardness is 300 mg / L (calculated as CaCO3), and it is stored in the first goaf; The filtered mine water in the first goaf is pumped to the second goaf with a capacity of 1 million cubic meters, and 295 mg / L of Ca(OH)2 for hardness removal is added for hardness removal reaction, and the residence time is 180 h; the TDS of the mine water after hardness removal is 2000 mg / L, turbidity is 20 NTU, and total hardness is 40 mg / L (calculated as CaCO3), and it is stored in the second goaf.

[0052] Step 2: Desalination treatment The mine water stored in the second goaf is treated by a direct filtration membrane system with a flux of 100 L / (m 2 ·h) and an operating pressure of 0.2 MPa; the TDS of the effluent is 2000 mg / L, turbidity is 0.1 NTU, and total hardness is 40 mg / L (calculated as CaCO3). After meeting the requirements of reverse osmosis feed water, it enters the intermediate water tank; The water in the intermediate water tank is adjusted to pH 6.5 for acidification to further control the scaling tendency, and then enters the moderate desalination reverse osmosis system. The membrane flux of the moderate desalination reverse osmosis membrane is 120 L / (m 2 ·h), the operating pressure is 1 MPa, and the recovery rate is 90%.

[0053] Step 3: Product water utilization and concentrated brine disposal The TDS of the desalinated purified product water is 300 mg / L, turbidity is 0.1 NTU, and the total hardness calculated as CaCO3 is 20 mg / L. The quality of the product water meets the Class III standard of the "Surface Water Environment Quality Standard" (GB20246-2006), and is supplied for underground production and ground use through the purified water storage tank; the concentration of the concentrated brine is 17300 mg / L, which is refluxed to the first goaf and homogenized with the original mine water for recycling treatment again.

[0054] The operating cost of the underground mine water treatment system in this embodiment is 2.5 yuan / t, and the water resource reuse rate is 98%.

[0055] Example 2 AdoptFigure 2 The system shown is used for underground treatment of mine water. The specific steps are as follows: Step 1: Pretreatment of mine water The mine water collected underground is pre-settled in an underground sump with a capacity of 200 m 3 , and the residence time is 5 h. The TDS of the mine water is 6500 mg / L, the turbidity is 700 NTU, and the total hardness is 400 mg / L (calculated as CaCO3). The TDS of the pre-settled mine water is 6500 mg / L, the turbidity is 500 NTU, and the total hardness is 400 mg / L (calculated as CaCO3). The clear water in the sump is pumped and injected into the water inlet point of the first goaf. The mine water is filtered and purified during the migration process in the first goaf with a capacity of 1 million cubic meters, and the residence time is 180 h. The TDS of the filtered mine water is 6500 mg / L, the turbidity is 60 NTU, and the total hardness is 400 mg / L (calculated as CaCO3), and it is stored in the first goaf. The filtered mine water in the first goaf is pumped to the second goaf with a capacity of 1 million cubic meters, and 311 mg / L of Ca(OH)2 and 45 mg / L of Na2CO3 for hardness removal are added for hardness removal reaction, and the residence time is 180 h. The TDS of the mine water after hardness removal is 6500 mg / L, the turbidity is 20 NTU, and the total hardness is 50 mg / L (calculated as CaCO3), and it is stored in the second goaf.

[0056] Step 2: Desalination treatment The mine water stored in the second goaf is treated by a direct filtration membrane system with the conditions of a flux of 100 L / (m 2 ·h) and an operating pressure of 0.2 MPa. The TDS of the effluent is 6500 mg / L, the turbidity is 0.1 NTU, and the total hardness is 50 mg / L (calculated as CaCO3). After meeting the requirements for reverse osmosis feed water, it enters the intermediate water tank. The water in the intermediate water tank is adjusted to pH 6.5 for acidification to further control the scaling tendency, and then enters a moderate desalination reverse osmosis system. The membrane flux of the moderate desalination reverse osmosis membrane is 120 L / (m 2 ·h), the operating pressure is 2 MPa, and the recovery rate is 90%.

[0057] Step 3: Utilization of produced water and disposal of concentrated brine The TDS of the desalinated and purified produced water is 500 mg / L, the turbidity is 0.1 NTU, and the total hardness calculated as CaCO3 is 23 mg / L. The quality of the produced water meets the Class III standard of the Surface Water Environment Quality Standard (GB20246 - 2006) and is supplied for underground production and ground use through the clean water pool. The concentration of the concentrated brine is 60500 mg / L and is directly injected into the third goaf with a capacity of 500,000 cubic meters for storage.

[0058] The operating cost of the underground mine water treatment system in this embodiment is 3.2 yuan per ton, and the water resource recycling rate is 90%.

[0059] Comparative Example 1 Step 1: Pretreatment of mine water A high-density sedimentation tank is used for hardening removal reaction, and hardening removal agents (such as Na2CO3 / NaOH / CaO, etc.) and coagulant aids (such as PAC, PAM, etc.) are added. Calculated according to the treatment volume of 600 cubic meters per hour, the construction cost of the high-density sedimentation tank is about 6.5 million yuan, and the operating cost is about 0.5 yuan per ton.

[0060] Step 2: Desalination treatment Ultrafiltration + reverse osmosis membrane process is used for desalination treatment. The water produced by the reverse osmosis membrane is usually lower than 10 μS / cm, and the water quality far exceeds the water quality requirements of Class III surface water (<1000 mg / L). Excessive desalination treatment has caused an increase in cost (2.5 yuan per ton).

[0061] Step 3: Utilization of produced water and disposal of concentrated brine The evaporation crystallization zero-discharge process is adopted. The treatment cost per ton of water is generally higher than 15 yuan per ton, and the disposal of miscellaneous salts and by-product salts after evaporation is difficult and the disposal cost is high.

[0062] The operating cost of the mine water treatment system in this embodiment is about 20 yuan per ton, and the water resource recycling rate is 85%.

[0063] The preferred embodiments of the present disclosure have been described in detail above with reference to the accompanying drawings. However, the present disclosure is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present disclosure, various simple modifications can be made to the technical solutions of the present disclosure, and these simple modifications all fall within the protection scope of the present disclosure.

[0064] In addition, it should be noted that, in the above specific embodiments, the various specific technical features described can be combined in any suitable manner without conflict. To avoid unnecessary repetition, the present disclosure will not separately describe various possible combination methods.

[0065] In addition, any combination can be made between different embodiments of the present disclosure as long as it does not violate the idea of the present disclosure, and it should also be regarded as the content disclosed by the present disclosure.

Claims

1. A mine water underground treatment system, characterized in that: The system includes: The pre-settling water tank is used to supply mine water for pre-settling to obtain pre-settled mine water; The first goaf is used to receive the pre-precipitated mine water, remove the suspended matter therein through rock filtering, and obtain filtered mine water; The second goaf is used to receive the filtered mine water, provide a de-hardening agent to contact the filtered mine water to perform a de-hardening reaction, and obtain de-hardened mine water; A direct filtration component is used to perform direct filtration treatment on the de-hardened mine water to obtain directly filtered mine water; The reverse osmosis component is used to desalinate the mine water after direct filtration to obtain desalinated purified water and concentrated brine.

2. The system according to claim 1, wherein: The second goaf is equipped with a de-hardening agent dosing device, and the de-hardening agent includes at least one of Na2CO3, NaOH, Ca(OH)2, CaO and gypsum.

3. The system according to claim 2, wherein: The de-hardening agent dosing device comprises an automatic dosing module, which is used to determine the dosage of the de-hardening agent according to the hardness level of the filtered mine water and to add the de-hardening agent according to the dosage.

4. The system according to claim 1, wherein: The system also includes: The intermediate water tank is connected between the direct filtration component and the reverse osmosis component and is provided with an acidity regulating device, wherein the acidity regulating device is used to adjust the pH value of the mine water after the direct filtration to acidic.

5. The system according to claim 1, wherein: The reverse osmosis component includes a concentration detection module for detecting the concentration of the concentrated brine; The first goaf is also used to receive the concentrated brine with a concentration lower than a preset threshold.

6. The system according to claim 5, wherein: The system also includes: The third goaf is used to receive and store the concentrated brine whose concentration exceeds the preset threshold; Preferably, the third goaf is provided with a concentrated brine diffusion monitoring module for real-time monitoring of the concentration and diffusion of the concentrated brine.

7. A method for treating mine water using the system according to any one of claims 1 to 6, characterized in that: The method includes: Allowing the mine water to pre-sediment in a pre-sedimentation tank to obtain pre-sedimented mine water; Allowing the pre-precipitated mine water to be filtered through rock mass in the first goaf to remove suspended matter therein, thereby obtaining filtered mine water; The filtered mine water is allowed to contact with a de-hardening agent in the second goaf to perform a de-hardening reaction to obtain de-hardened mine water; The de-hardened mine water is subjected to direct filtration treatment through a direct filtration component to obtain directly filtered mine water; The mine water after direct filtration is desalinated by a reverse osmosis component to obtain desalinated purified water and concentrated brine.

8. The method according to claim 7, wherein: The method further comprises: adjusting the pH value of the directly filtered mine water to acidic, and then performing the desalination treatment; and / or, The method also includes: detecting the concentration of the concentrated brine, and when the concentration of the concentrated brine is lower than a preset threshold, introducing the concentrated brine into the first goaf for circulation treatment; when the concentration of the concentrated brine exceeds the preset threshold, introducing the concentrated brine into the third goaf for storage.

9. The method according to claim 7, wherein: The residence time of the mine water in the pre-sinking water tank is 4 to 10 hours; The residence time of the mine water in the first goaf is 4 hours to 60 days; The residence time of the mine water in the second goaf is 4 hours to 60 days; The direct filtration treatment conditions include: direct filtration membrane flux of 30~150L / (m 2 h), operating pressure 0.2~0.3MPa; The desalination treatment conditions include: reverse osmosis membrane flux of 15-120 L / (m 2 ·h), operating pressure 0~2 MPa.

10. The method according to claim 7, wherein: The mine water has a TDS of 1000-10000 mg / L, a turbidity of 0-10000 NTU, and a total hardness of 20-2000 mg / L in terms of CaCO3; The filtered mine water has a TDS of 1000-10000 mg / L, a turbidity of 0-100 NTU, and a total hardness of 20-2000 mg / L in terms of CaCO3; The TDS of the de-hardened mine water is 1000-10000 mg / L, the turbidity is 0-100 NTU, and the total hardness in terms of CaCO3 is 1-100 mg / L; The TDS of the mine water after direct filtration is 1000-10000 mg / L, the turbidity is 0-0.5 NTU, and the total hardness in terms of CaCO3 is 1-100 mg / L.

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