A mine water purification system based on nanofiltration

Abstract

This utility model discloses a mine water purification system with nanofiltration as its core, including a mine water pretreatment device and a nanofiltration purification device. The nanofiltration purification device includes a main security filter, a high-pressure pump, a nanofiltration unit, a nanofiltration purified water tank, a reinjection pump, a production fresh water tank, a circulating water tank, and a nanofiltration concentrate tank. The inlet of the high-pressure pump is connected to the mine water pretreatment device through the main security filter. The inlet of the nanofiltration unit is connected to the outlet of the high-pressure pump. The purified water produced by the nanofiltration unit flows by gravity through pipelines to the nanofiltration purified water tank. The inlet of the reinjection pump is connected to the nanofiltration purified water tank, and the outlet is connected to the reinjection pipeline. The concentrate produced by the nanofiltration unit flows by gravity through pipelines to the production fresh water tank, the circulating water tank, and the nanofiltration concentrate tank. This utility model replaces the traditional reverse osmosis purification device with a nanofiltration purification device, effectively solving the problems of large membrane pressure difference and low water production rate in the original purification system, reducing system energy consumption, and lowering the cost of mine water treatment.

Description

Technical Field

[0001] This utility model relates to a mine water purification system with nanofiltration as its core, which can achieve deep purification treatment of iron ore mine water and belongs to the field of water treatment technology. Background Technology

[0002] Building green mines, promoting eco-friendly technologies, and actively participating in environmental governance are social responsibilities that every metal mining enterprise must fulfill. This is especially true for large-scale iron ore mines, where the volume of mine water inflow is often substantial. Directly discharging large quantities of harmful mine water can easily cause direct pollution to the land and water systems, affecting human and animal health, and further damaging the regional groundwater ecosystem. Therefore, the treatment and recycling of mine water is of great significance for improving the local ecological environment. To protect regional groundwater resources and improve the groundwater environment, large-scale iron ore mine drainage water is often purified before being used for mining, mineral processing, and domestic water needs. Excess water is reinjected into the aquifer of the mining area. However, mine water inflow must first be purified to meet the prescribed reinjection water quality requirements before it can be reinjected into the ground. This places even stricter requirements on mine water purification technology.

[0003] Reverse osmosis technology is currently one of the most widely used water treatment technologies in China. The water production rate of reverse osmosis membranes is about 30%, and can reach 50% in some cases. This is mainly because the reverse osmosis membrane has a high precision of 0.0001um. However, due to the large pressure difference of the reverse osmosis membrane, the required operating pressure is high, which leads to high power consumption and high system operating costs for mine water purification systems based on reverse osmosis.

[0004] Nanofiltration membranes can separate dissolved components as small as approximately 1 nm. They exhibit ion selectivity, removing heavy metal ions such as cadmium, chromium, copper, lead, manganese, mercury, and nickel, as well as SO42-. 2- PO4 3- It produces divalent or higher-valence negative ions, operates at a pressure approximately 30% lower than reverse osmosis, has a membrane pressure differential of 0.5-1.0 MPa, and achieves a water production rate of up to 80%, generating less wastewater and resulting in lower operating costs (electricity consumption). However, mine water purification technology centered on nanofiltration is rarely applied in engineering. Therefore, designing a mine water purification system based on nanofiltration is of great significance for energy conservation and consumption reduction. Utility Model Content

[0005] The purpose of this invention is to address the shortcomings of existing technologies by providing a mine water purification system based on nanofiltration, thereby reducing energy consumption and lowering water treatment costs.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A mine water purification system based on nanofiltration includes a mine water pretreatment device and a nanofiltration purification device. The nanofiltration purification device includes a main security filter, a high-pressure pump, a nanofiltration unit, a nanofiltration clean water tank, a reinjection pump, a production fresh water tank, a circulating water tank, and a nanofiltration concentrate tank. The inlet of the high-pressure pump is connected to the mine water pretreatment device through the main security filter. The inlet of the nanofiltration unit is connected to the outlet of the high-pressure pump. The purified water produced by the nanofiltration unit flows by gravity through pipelines to the nanofiltration clean water tank. The inlet of the reinjection pump is connected to the nanofiltration clean water tank, and the outlet is connected to the reinjection pipeline. The concentrate produced by the nanofiltration unit flows by gravity through pipelines to the production fresh water tank, the circulating water tank, and the nanofiltration concentrate tank.

[0008] The aforementioned mine water purification system with nanofiltration as its core also includes a nanofiltration flushing pump. The inlet of the nanofiltration flushing pump is connected to the nanofiltration water purification tank, and the outlet is connected to the inlet of the nanofiltration device through a pipeline.

[0009] The aforementioned mine water purification system with nanofiltration as its core includes a nanofiltration cleaning device. The nanofiltration cleaning device comprises a chemical tank, a chemical cleaning pump, and a secondary security filter. The water inlet of the chemical tank is connected to the purified water outlet of the nanofiltration device via a pipeline. The water inlet of the chemical cleaning pump is connected to the water outlet of the chemical tank, and the water outlet is connected to the water inlet of the nanofiltration device via the secondary security filter.

[0010] The aforementioned mine water purification system with nanofiltration as its core also includes a NaCLO dosing system, which is connected to the nanofiltration purification tank and the raw water tank.

[0011] The aforementioned mine water purification system with nanofiltration as its core includes a mine water pretreatment device comprising a mechanically accelerated clarification tank, a buffer tank, a booster pump, a raw water tank, a raw water pump, a multi-media filter, and a self-cleaning filter. The inlet pipe of the clarification tank is connected to the mine drainage system, and the outlet pipe is connected to the buffer tank. The inlet pipe of the booster pump is connected to the buffer tank, and the outlet pipe is connected to the raw water tank. The inlet pipe of the raw water pump is connected to the raw water tank, and the outlet pipe is connected to the top inlet of the multi-media filter. The purified water outlet of the multi-media filter is connected to the self-cleaning filter, and the water production end of the self-cleaning filter is connected to the inlet of the main security filter.

[0012] The aforementioned mine water purification system with nanofiltration as its core has an inlet pipe connected to a coagulant dosing system, a coagulant aid dosing system, and a lime slurry dosing system.

[0013] The aforementioned mine water purification system with nanofiltration as its core includes a backwashing device in the multi-media filter. The backwashing device comprises a multi-media backwashing pump, a Roots blower, and a backwash drainage tank. The inlet of the multi-media backwashing pump is connected to the raw water tank, and the outlet is connected to the backwashing pipeline of the multi-media filter. The high-pressure air output of the Roots blower is connected to the air inlet of the multi-media filter. The backwash drain pipe of the multi-media filter is connected to the backwash drainage tank through a workshop ditch.

[0014] The aforementioned mine water purification system with nanofiltration as its core includes a self-priming pump installed on the backwash drainage tank. The inlet of the self-priming pump is connected to the backwash drainage tank, and the outlet is connected to the clarification tank through a pipeline.

[0015] The aforementioned mine water purification system with nanofiltration as its core has a scale inhibitor dosing system and a reducing agent dosing system connected to the pipeline between the self-cleaning filter and the main security filter.

[0016] The aforementioned mine water purification system with nanofiltration as its core contains two types of filter media inside the multi-media filter: quartz sand and anthracite.

[0017] This invention replaces the reverse osmosis purification device in the traditional mine water purification system with a nanofiltration purification device, which effectively solves the problems of large reverse osmosis membrane pressure difference and low water production rate in the original mine water purification system, thereby reducing the energy consumption of the mine water purification system and effectively reducing the treatment cost of mine water. Attached Figure Description

[0018] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0019] Figure 1 This is a schematic diagram of the structure of this utility model.

[0020] The following are the labels in the diagram: 1. Clarifying tank, 2. Buffer tank, 3. Booster pump, 4. Raw water tank, 5. Raw water pump, 6. Multi-media backwash pump, 7. Multi-media filter, 8. Self-cleaning filter, 9. Backwash drainage tank, 10. Self-priming pump, 11. Main security filter, 12. High-pressure pump, 13. Nanofiltration unit, 14. Nanofiltration purified water tank, 15. Nanofiltration flushing pump, 16. Recharge pump, 17. Nanofiltration concentrate tank, 18. Roots blower, 19. Coagulant dosing system, 20. Coagulant aid dosing system, 21. Lime slurry dosing system, 22. Scale inhibitor dosing system, 23. Reducing agent dosing system, 24. New production water tank, 25. Circulating water tank, 26. Secondary security filter, 27. NaCLO dosing system, 28. Chemical tank, 29. Chemical cleaning pump. Detailed Implementation

[0021] This invention addresses the shortcomings of existing technologies by providing a mine water purification system based on nanofiltration. This system achieves deep purification of iron ore mine water, meeting national reinjection water quality standards, while simultaneously reducing water treatment costs.

[0022] See Figure 1 This utility model mainly includes a mechanically accelerated clarification tank 1, a buffer tank 2, a booster pump 3, a raw water tank 4, a raw water pump 5, a multi-media backwash pump 6, a multi-media filter 7, a self-cleaning filter 8, a backwash drainage tank 9, a self-priming pump 10, a main security filter 11, a high-pressure pump 12, a nanofiltration device 13, a nanofiltration purified water tank 14, a nanofiltration flushing pump 15, a reinjection water pump 16, a nanofiltration concentrate tank 17, a Roots blower 18, a coagulant dosing system 19, a coagulant aid dosing system 20, a lime slurry dosing system 21, a scale inhibitor dosing system 22, a reducing agent dosing system 23, a production fresh water tank 24, a circulating water tank 25, a NaCLO dosing system 27, and a nanofiltration cleaning device. The nanofiltration cleaning device includes a chemical tank 28, a chemical cleaning pump 29, and a secondary security filter 26.

[0023] The influent to clarifier 1 comes from mine drainage, and the produced water (cleaned water) is piped to buffer tank 2. Coagulant (polyaluminum chloride) is added to clarifier 1 via coagulant dosing system 19, coagulant aid (polyacrylamide) is added via coagulant aid dosing system 20, and slaked lime is added via lime slurry dosing system 21 to further remove suspended solids, colloidal impurities, calcium and magnesium carbonate hardness, etc., from the mine water, ensuring the final turbidity of the produced water from the clarifier is ≤10 NTU. The produced water, after flocculation and sedimentation treatment in clarifier 1, flows by gravity to buffer tank 2 via pipeline.

[0024] Water in buffer tank 2 is pumped to raw water tank 4 by lift pump 3 (two to three units, only one shown in the figure) and pipeline. Raw water pump 5 (three to four units, only one shown in the figure) pressurizes the water in raw water tank 4 to multi-media filter 7 (nine to eleven units, only one shown in the figure) through pipeline. The permeate water after flocculation and sedimentation treatment in clarifier 1 still contains fine colloidal particles, humic substances, microorganisms, etc. The multi-media filter 7 is filled with two kinds of filter media, quartz sand and anthracite. After the mine water is filtered by the filter media, the above-mentioned impurities are further removed. The permeate water from multi-media filter 7 flows by gravity through pipeline to self-cleaning filter 8.

[0025] After running for a period of time, more and more impurities will accumulate in the multi-media filter 7. When the water production is significantly reduced, the multi-media filter 7 needs to be backwashed. The backwashing device includes a multi-media backwash pump 6 and a Roots blower 18. The inlet of the multi-media backwash pump 6 (two units, only one is shown in the figure) is connected to the raw water tank 4, and the outlet is connected to the backwash pipeline of the multi-media filter 7, which pumps backwash water into the multi-media filter 7 to cooperate with the Roots blower 18 for backwashing. The water inlet direction of the backwash pipeline of the multi-media filter 7 is opposite to that of the inlet pipeline, and water enters from the bottom of the filter media of the multi-media filter 7. The Roots blower 18 (two units, only one is shown in the figure) provides high-pressure air to the bottom of the multi-media filter 7 through the pipeline, which blows the filter media upward and backwashes the filter media together with the backwash water. The wastewater generated by backwashing is discharged into the workshop ditch through the backwash drain pipe and collected into the backwash drainage tank 9. The backwash drainage tank 9 is equipped with a self-priming pump 10 (two units, only one is shown in the figure), which discharges the wastewater to the mechanical acceleration clarification tank 1 for flocculation and purification through the pipeline.

[0026] Self-cleaning filters 8 (five to six units, only one shown in the diagram) are installed after the multi-media filter 7 and before the high-pressure pump 12 and nanofiltration unit 13. Their product water end is connected to the main security filter 11 via a pipeline. The product water, further filtered and purified by the self-cleaning filter 8, flows by gravity to the main security filter 11. The self-cleaning filter 8 has a filtration accuracy of 50μm and is a fully automatic operating device. When the pressure difference between the inlet and outlet water of the self-cleaning filter 8 exceeds 0.05MPa or the filtration cycle reaches 24 hours, the self-cleaning filter 8 will automatically clean its filter element, achieving uninterrupted operation and continuous water output. The cleaning wastewater is discharged to the backwash drainage tank 9 through the workshop ditch.

[0027] Main security filters 11 (five to six units, only one shown in the diagram) are installed before the high-pressure pump 12. The filter cartridge has a filtration accuracy of 5μm. The product water, after further filtration and purification by the main security filter 11, is connected to the inlet of the high-pressure pump 12 via pipeline. When the pressure difference between the inlet and outlet of the main security filter 11 is greater than 0.02Mpa, the filter cartridge must be replaced manually. The product water after further purification by the main security filter 11 meets the requirements for nanofiltration influent, with a turbidity of less than 1.0 NTU.

[0028] High-pressure pumps 12 (five to six units, only one shown in the diagram) are installed before the nanofiltration unit 13. Based on the pressure difference requirements of the membrane elements, one high-pressure pump 12 is configured before each nanofiltration unit 13. The system operating pressure is 0.5-0.75 MPa. The high-pressure pump 12 pumps water at a high pressure of approximately 0.69 MPa into the inlet of the nanofiltration unit 13 through pipelines, where the water undergoes further desalination and deep purification through the nanofiltration membrane module.

[0029] The self-cleaning filter 8, main security filter 11, high-pressure pump 12, and nanofiltration unit 13 are all of equal quantity. The purified water produced by the nanofiltration unit 13 flows by gravity through pipeline to the nanofiltration purified water tank 14. The inlet of the reinjection pump 16 (two units, only one is shown in the figure) is connected to the nanofiltration purified water tank 14, and the outlet is connected to the reinjection pipeline. The purified water is sent to the domestic water point and reinjection well through the reinjection pump 16 and reinjection pipeline for domestic water use and reinjection. The concentrated water produced by the nanofiltration unit 13 flows by gravity to the new production water tank 24, the ring water tank 25, and the nanofiltration concentrated water tank 17 for the production water of the entire mine.

[0030] The inlet of the nanofiltration flushing pump 15 (one or two units, one is shown in the figure) is connected to the nanofiltration purification water tank 14 through a pipeline, and the outlet is connected to the nanofiltration device 13 through a pipeline. Before each nanofiltration is started, the nanofiltration device 13 is flushed with purified water through the nanofiltration flushing pump 15 to flush away microorganisms and other impurities that have grown or remained in the nanofiltration system. Before each nanofiltration is stopped, the nanofiltration device 13 is also flushed with purified water through the nanofiltration flushing pump 15 to ensure that the water in the nanofiltration device 13 is purified water. The flushing water flows by gravity through pipelines to the nanofiltration concentrate tank 17, the production fresh water tank 24, and the circulating water tank 25.

[0031] To protect the nanofiltration membrane of nanofiltration unit 13, when the oxidation-reduction potential (ORP) in the raw water is greater than 180, a reducing agent is added to the pipeline through the reducing agent dosing system 23 to prevent oxides from entering the membrane housing. The dosing point is located on the inlet pipe of the main security filter 11, and the dosing method is metering pump injection. To protect the nanofiltration membrane of nanofiltration unit 13 and prevent membrane scaling, a scale inhibitor is added to the pipeline through the scale inhibitor dosing system 22. The dosing point is located on the inlet pipe of the main security filter 11, and the dosing method is metering pump injection. Two NaCLO dosing systems 27 are configured, with dosing points located in the nanofiltration purified water tank 14 and the raw water tank 4 respectively (the dosing pipeline of the raw water tank 4 is not shown in the figure), and the dosing method is metering pump injection.

[0032] To prevent nanofiltration membrane degradation and subsequent performance decline, a nanofiltration cleaning unit (one set) is installed, and the nanofiltration system is chemically cleaned every three months. The nanofiltration cleaning unit includes: a chemical tank 28, a chemical cleaning pump 29, a secondary security filter 26, and piping. The outlet of the nanofiltration unit 13 is connected to the inlet of the chemical tank 28 via piping, and the inlet of the chemical cleaning pump 29 is connected to the outlet of the chemical tank 28. The outlet of the chemical cleaning pump 29 is connected to the inlet of the nanofiltration unit 13 via the secondary security filter 26 and piping. The chemical cleaning pump 29 delivers the chemical solution from the chemical tank 28 to the nanofiltration unit 13, allowing the solution to circulate between the tank and the unit, thus chemically cleaning the nanofiltration membrane. The cleaning wastewater is discharged into the workshop ditch and collected in the backwash drainage tank 9. Example

[0033] (1) A certain iron mine is a large-scale water-rich iron mine. In order to ensure safe mining and protect the groundwater environment, a curtain grouting and recharge project is implemented. The mine water must first be discharged to the surface for deep purification to meet the standard requirements before being recharged to the underground aquifer outside the curtain to maintain the groundwater ecological environment. Through the analysis of the mine water inflow, it can be seen that the mine water inflow mainly comes from the Ordovician aquifer in the upper part of the ore body. The water from the working face of the mining area is discharged to the -260m permanent water reservoir through the roadway ditch and the drainage well. The underground water inflow was sampled and tested. The results are detailed in Table 1. According to Table 1, it can be determined that the water contains a small amount of suspended solids, intestinal bacteria, organic matter, ammonia nitrogen, etc. Based on this utility model, the mine water treatment system is designed for the mine.

[0034] Table 1. General characteristics of water inrush in a certain mine.

[0035]

[0036] (2) Install one mechanically accelerated clarification tank, a semi-underground reinforced concrete structure, with a treatment capacity of 1000-1300 m³. 3 / h. A coagulant dosing system 19, a coagulant aid dosing system 20, and a lime slurry dosing system 21 are installed. Polyaluminum chloride, polyacrylamide, and quicklime are added to the clarifier to further remove suspended solids, colloidal impurities, calcium and magnesium carbonate hardness, etc., from the mine water. The final turbidity of the clarifier is ≤10 NTU. The influent to the mechanically accelerated clarifier 1 comes from mine drainage, and the produced water (clean water) is discharged to the buffer tank 2 through pipelines.

[0037] (3) Construct one buffer pool, a reinforced concrete structure, underground, with a volume V=120m³. 3 The buffer pool 2 is equipped with three lift pumps 3, which are self-priming pumps with a capacity of Q=600-800m³. 3 / h, H=13-8m, N=55kw, two in use and one on standby. The water in buffer tank 2 is discharged to raw water tank 4 through lift pump 3 and pipeline.

[0038] A raw water tank (V=500m³) will be constructed. 3 Four raw water pumps (5) are installed next to raw water tank 4. These are horizontal centrifugal pumps with a capacity of Q=340m³. 3 / h, H=40m, N=55kw, 3 in operation, 1 on standby. The raw water pump 5 pumps water from the raw water tank 4 through pipelines to the multi-media filter 7.

[0039] (4) Install eleven multi-media filters 7, Q=120m 3 / h, with a diameter of DN3200mm, the multi-media filter contains two types of filter media: quartz sand and anthracite. The permeate water after flocculation and sedimentation treatment in the clarifier still contains fine colloidal particles, humic substances, microorganisms, etc. After the mine water is filtered through the filter media in the multi-media filter 7, the above-mentioned impurities are further removed. The permeate water from the multi-media filter 7 flows by gravity through pipeline to the self-cleaning filter 8.

[0040] After running for a period of time, impurities will accumulate in the multi-media filter 7. When the water production decreases significantly, backwashing of the multi-media filter 7 is necessary. Two multi-media backwash pumps 6 are installed; these are horizontal centrifugal pumps with a capacity of Q=210m³. 3 / h, H=20m, N=18.5kw, one in operation and one on standby. The inlet of the multi-media backwash pump 6 is connected to the raw water tank 4, and the outlet is connected to the backwash pipeline of the multi-media filter 7, pumping water into the multi-media filter 7 to perform backwashing in conjunction with the Roots blower 18; the water inlet direction of the backwash pipeline of the multi-media filter 7 is opposite to that of the inlet pipeline, entering from the bottom of the filter media of the multi-media filter 7; two Roots blowers 18 are installed, Q=6.5m 3 / h, P=58.8kPa, N=15kw, one in operation and one on standby. Roots blower 18 supplies high-pressure air to the bottom of multi-media filter 7 through pipelines, backflushing the filter media upwards. This air, along with backwash water, backwashes the filter media. The backwash wastewater is discharged into the workshop ditch and collected in backwash drainage tank 9. A single underground reinforced concrete structure, V=250m³, is installed for backwash drainage. 3 The backwash drainage tank is equipped with two self-priming pumps (Q=50m). 3 / h, H=30m, N=11kw, one in use and one on standby. The self-priming pump 10 discharges sewage to the mechanically accelerated clarification tank 1 through pipeline for flocculation and purification.

[0041] (5) Install six self-cleaning filters 8, Q=200m 3 / h, P=1.0MPa, filtration accuracy 50μm, installed after the multi-media filter 7 and before the high-pressure pump 12, its product water end is connected to the main security filter 11 through a pipeline, and the product water after further filtration and purification by the self-cleaning filter 8 flows by gravity to the main security filter 11 through the pipeline.

[0042] The self-cleaning filter 8 is a fully automatic operating device. When the pressure difference between the inlet and outlet water of the self-cleaning filter 8 is greater than 0.05MPa or the filtration cycle reaches 24 hours, the self-cleaning filter 8 will automatically clean the filter element, which can achieve uninterrupted operation and continuous water output. Its cleaning wastewater is discharged to the backwash drainage pool 9 through the workshop ditch.

[0043] (6) Six main security filters 11, DN900, with a filter element filtration accuracy of 5µm, are installed before the high-pressure pump 12. The product water, after further filtration and purification by the main security filters 11, is connected to the inlet of the high-pressure pump 12 via pipeline. When the pressure difference between the inlet and outlet of the main security filters 11 is greater than 0.02 MPa, the filter element is replaced manually. The product water after further purification by the main security filters 11 can meet the nanofiltration inlet requirements, with a turbidity of less than 1.0 NTU.

[0044] (7) Six high-pressure pumps 12 are installed. They are horizontal centrifugal pumps with Q=194m. 3 With a pressure of approximately 0.69 MPa, a pressure pump 12 is installed before the nanofiltration unit 13. The pump operates at approximately 0.69 MPa, based on the inlet pressure requirements of the membrane element. The high-pressure pump 12 pumps water at approximately 0.69 MPa into the inlet of the nanofiltration unit 13 via pipeline, where it further desalinates and deeply purifies the water through the nanofiltration membrane module.

[0045] (8) Six nanofiltration units 13 are set up. Each nanofiltration unit 13 can operate independently or simultaneously. Based on the analysis of mine water quality and the actual membrane products of Hydranautics, the experimental calculation determined that the membrane element model is ESNA1-LF-LDS, 8” nanofiltration membrane element, with an average membrane energy of 22.1 LMH. Harlepu R8040B300S-6W type fiberglass membrane housing is selected. Each nanofiltration unit is equipped with 27 6-core 8” membrane housings and 162 8” nanofiltration membrane elements. The membrane assembly is a two-stage primary stage, arranged in an 18:9 ratio. The influent flow rate of a single nanofiltration unit 13 is 200 m³ / h. 3 / h, water production 167m³ 3 / h.

[0046] The purified water produced by nanofiltration unit 13 flows by gravity through pipeline to nanofiltration purification tank 14. A nanofiltration purification tank 14 is provided, with a reinforced concrete corrosion-resistant structure and a volume V=500m³. 3 Two horizontal centrifugal pumps (Q=1071m) are installed for the reinjection water. 3 / h, H=12m, N=55kw, the inlet of the reinjection pump 16 is connected to the nanofiltration water purification tank 14, and the outlet is connected to the reinjection pipeline. The purified water is sent to the domestic water point and the reinjection well through the reinjection pump 16 and the reinjection pipeline for domestic water use and reinjection. The concentrated water produced by the nanofiltration device 13 flows by gravity to the new production water tank 24, the ring water tank 25, and the nanofiltration concentrated water tank 17 for production water use throughout the mine.

[0047] (9) Install one nanofiltration backwash pump 15, a horizontal centrifugal pump, Q=100m 3The nanofiltration flushing pump 15 has a flow rate of / h, a height of H=32m, a power of N=15kw, and its inlet is connected to the nanofiltration purification tank 14 via a pipeline. Its outlet is connected to the nanofiltration unit 13 via a pipeline. Before each start-up of the nanofiltration system, purified water is used to flush the nanofiltration unit 13 through the flushing pump 15 to remove any microorganisms or other impurities that may have grown or remained in the system. Before each shutdown, purified water is also used to flush the nanofiltration unit 13 through the flushing pump 15 to ensure that the water in the nanofiltration unit 13 is purified water. The flushing water flows by gravity through pipelines to the nanofiltration concentrate tank 17, the new production water tank 24, and the circulating water tank 25.

[0048] (10) Set up one set of reducing agent dosing system 23, one set of scale inhibitor dosing system 22, and two sets of NaClO dosing system 27. To protect the nanofiltration membrane of nanofiltration device 13, when the oxidation-reduction potential (ORP) in the raw water is greater than 180, a reducing agent is added to the pipeline through the reducing agent dosing system 23 to prevent oxides from entering the membrane housing. The dosing point is located on the inlet pipe of the main security filter 11, and the dosing method is metering pump injection. To protect the nanofiltration membrane of nanofiltration device 13 and prevent membrane scaling, a scale inhibitor is added to the pipeline through the scale inhibitor dosing system 22. The dosing point is located on the inlet pipe of the main security filter 11, and the dosing method is metering pump injection. The dosage of the two agents is 2-5 PPM. The sodium hypochlorite dosing points are located in nanofiltration water purification tank 14 and raw water tank 4, respectively, and the dosing method is metering pump injection.

[0049] (11) To prevent the nanofiltration membrane from deteriorating and causing a decline in membrane performance, a nanofiltration cleaning device is installed. The nanofiltration system is chemically cleaned every three months. The nanofiltration cleaning device includes: a chemical tank 28 (8000L capacity), a chemical cleaning pump 29 (a corrosion-resistant horizontal centrifugal pump with a flow rate of 120m³ / h and a head of 0.28MPa), a main security filter 11 (filter accuracy of 5μm), and pipelines. The inlet of the nanofiltration cleaning device is connected to the chemical tank 28 via a pipeline, and the outlet is connected to the nanofiltration device 13 via a pipeline. The chemical cleaning pump 29 delivers the chemical solution from the chemical tank 28 to the nanofiltration device 13, allowing the chemical solution to circulate between the chemical tank 28 and the nanofiltration device 13, thus chemically cleaning the nanofiltration membrane. The wastewater after cleaning is discharged into the workshop ditch and collected in the backwash drainage tank 9.

[0050] This system uses nanofiltration device 13 as its core equipment, which can achieve deep purification treatment of iron ore mine water with a water production rate of over 75%. It reduces the operating pressure of the equipment and can reduce power consumption by about 30% compared with reverse osmosis. The system is more energy-efficient, thereby reducing water treatment costs.

Claims

1. A mine water purification system based on nanofiltration, characterized in that, The system includes a mine water pretreatment device and a nanofiltration purification device. The nanofiltration purification device includes a main security filter (11), a high-pressure pump (12), a nanofiltration device (13), a nanofiltration water tank (14), a reinjection pump (16), a production new water tank (24), a circulating water tank (25), and a nanofiltration concentrate tank (17). The inlet of the high-pressure pump (12) is connected to the mine water pretreatment device through the main security filter (11). The inlet of the nanofiltration device (13) is connected to the outlet of the high-pressure pump (12). The purified water generated by the nanofiltration device (13) flows by gravity through the pipeline to the nanofiltration water tank (14). The inlet of the reinjection pump (16) is connected to the nanofiltration water tank (14), and the outlet is connected to the reinjection pipeline. The concentrate generated by the nanofiltration device (13) flows by gravity through the pipeline to the production new water tank (24), the circulating water tank (25), and the nanofiltration concentrate tank (17).

2. The mine water purification system based on nanofiltration as described in claim 1, characterized in that, The nanofiltration purification device also includes a nanofiltration flushing pump (15), the inlet of which is connected to the nanofiltration water purification tank (14), and the outlet is connected to the inlet of the nanofiltration device (13) through a pipeline.

3. A mine water purification system based on nanofiltration as described in claim 2, characterized in that, The nanofiltration purification device also includes a nanofiltration cleaning device, which includes a medicine tank (28), a chemical cleaning pump (29), and a secondary security filter (26). The water inlet of the medicine tank (28) is connected to the clean water outlet of the nanofiltration device (13) through a pipeline. The water inlet of the chemical cleaning pump (29) is connected to the water outlet of the medicine tank (28), and the water outlet is connected to the water inlet of the nanofiltration device (13) through the secondary security filter (26).

4. A mine water purification system based on nanofiltration as described in claim 3, characterized in that, The nanofiltration purification device also includes a NaCLO dosing system (27), which is connected to the nanofiltration water purification tank (14) and the raw water tank (4).

5. A mine water purification system based on nanofiltration as described in any one of claims 1-4, characterized in that, The mine water pretreatment device includes a mechanically accelerated clarification tank (1), a buffer tank (2), a booster pump (3), a raw water tank (4), a raw water pump (5), a multi-media filter (7), and a self-cleaning filter (8). The inlet pipe of the clarification tank (1) is connected to the mine drainage, and the outlet pipe is connected to the buffer tank (2). The inlet pipe of the booster pump (3) is connected to the buffer tank (2), and the outlet pipe is connected to the raw water tank (4). The inlet pipe of the raw water pump (5) is connected to the raw water tank (4), and the outlet pipe is connected to the top inlet of the multi-media filter (7). The clean water outlet of the multi-media filter (7) is connected to the self-cleaning filter (8), and the water production end of the self-cleaning filter (8) is connected to the inlet end of the main security filter (11).

6. A mine water purification system based on nanofiltration as described in claim 5, characterized in that, The inlet pipe of the clarifier (1) is connected to a coagulant dosing system (19), a coagulant aid dosing system (20), and a lime slurry dosing system (21).

7. A mine water purification system based on nanofiltration as described in claim 6, characterized in that, The multi-media filter (7) is equipped with a backwashing device, which includes a multi-media backwashing pump (6), a Roots blower (18), and a backwashing drainage tank (9). The inlet of the multi-media backwashing pump (6) is connected to the raw water tank (4), and the outlet is connected to the backwashing pipeline of the multi-media filter (7). The high-pressure air output end of the Roots blower (18) is connected to the air inlet of the multi-media filter (7). The backwashing sewage pipe of the multi-media filter (7) is connected to the backwashing drainage tank (9) through the workshop ditch.

8. A mine water purification system based on nanofiltration as described in claim 7, characterized in that, The backwash drainage tank (9) is equipped with a self-priming pump (10). The inlet end of the self-priming pump (10) is connected to the backwash drainage tank (9), and the outlet end is connected to the clarification tank (1) through a pipeline.

9. A mine water purification system based on nanofiltration as described in claim 8, characterized in that, The self-cleaning filter (8) and the main security filter (11) are connected by a scale inhibitor dosing system (22) and a reducing agent dosing system (23).

10. A mine water purification system based on nanofiltration as described in claim 9, characterized in that, The multi-media filter (7) contains two types of filter media: quartz sand and anthracite.

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