Lithium electroplate copper foil flushing water concentration system and method based on high-pressure nanofiltration

Abstract

The invention relates to the technical field of wastewater treatment, and discloses a lithium electroplate copper foil flushing water concentration system and method based on high-pressure nanofiltration, and the system comprises the following components: a concentrated water collection module which comprises a concentrated water tank, a liquid level meter and a pH meter; the pretreatment module comprises a booster pump and a scale inhibitor adding device; a high-pressure nanofiltration concentration module; the produced water collecting module comprises a concentrated solution collecting box and a fresh water collecting box; the chemical cleaning module comprises a cleaning water tank and a cleaning pump; the intelligent control module comprises a programmable logic controller, a pressure sensor, a flow sensor and a touch screen, the programmable logic controller collects operation parameters through the pressure sensor and the flow sensor, the operation state is displayed and controlled through the touch screen, and full-automatic operation is carried out. Pressure, flow and liquid level sensors are integrated through the intelligent control module based on a PLC, the pump speed and the valve opening degree are adjusted through a PID algorithm, the manual intervention requirement is reduced, and the operation precision and reliability are improved.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, specifically to a lithium-ion battery electroplating copper foil rinsing water concentration system and method based on high-pressure nanofiltration. Background Technology

[0002] In the lithium battery manufacturing process, the rinsing water generated from the copper foil electroplating process contains high concentrations of copper ions (20-30 g / L), acidic substances (10-15 g / L, pH ≤ 3), and small amounts of organic additives (COD ≤ 500 ppm). It requires concentration treatment to achieve resource recovery and wastewater reduction. Existing technologies commonly employ chemical precipitation, evaporation concentration, or nanofiltration membrane separation to treat this type of wastewater. Chemical precipitation generates copper precipitate by adding alkaline reagents, but requires subsequent solid-liquid separation. Evaporation concentration uses high-temperature evaporation to concentrate copper ions, suitable for high-concentration wastewater. Nanofiltration membrane separation separates copper ions from the solvent through the selective sieving action of the membrane and has been applied to some extent in industrial wastewater treatment. For example, existing nanofiltration systems are typically equipped with a single-stage pressure pump and conventional nanofiltration membranes, capable of concentrating copper ions to a certain degree while producing reusable freshwater.

[0003] However, existing technologies have significant shortcomings in system operation control. Taking nanofiltration membrane systems as an example, their operation typically relies on manual or semi-automatic control methods, such as manually adjusting pump power or valve opening to maintain pressure and flow stability. In this approach, the system responds slowly to changes in influent flow rate and water quality (such as fluctuations in copper ion concentration or increases in COD), and parameter adjustment accuracy is low, with errors potentially reaching 5%-10%. Furthermore, existing systems lack real-time monitoring and automatic adjustment functions; operating parameters such as pressure and liquid level must be recorded manually, making continuous unattended operation difficult, leading to decreased operating efficiency and increased manual management costs. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a lithium-ion battery electroplating copper foil rinsing water concentration system and method based on high-pressure nanofiltration, which solves the problem that existing technologies rely on manual adjustment of pump operating power or valve opening to maintain pressure and flow stability, resulting in low parameter adjustment accuracy.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a lithium-ion battery electroplating copper foil rinsing water concentration system based on high-pressure nanofiltration, comprising the following components: The concentrate collection module includes a concentrate tank, a level gauge, and a pH meter. The concentrate tank is used to receive and buffer the concentrate from the rinsing water of the electroplated copper foil after two-stage nanofiltration pretreatment. The level gauge is used to monitor the liquid level in the concentrate tank, and the pH meter is used to monitor the pH value of the concentrate. The pretreatment module includes a booster pump and an antiscalant dosing device, wherein the booster pump is used to increase the pressure of the concentrate, and the antiscalant dosing device is used to add antiscalant to the concentrate to prevent scaling on the membrane surface; The high-pressure nanofiltration concentration module includes a high-pressure pump, an interstage booster pump, and an acid-resistant and fouling-resistant high-pressure nanofiltration membrane module. The high-pressure pump and the interstage booster pump are used to increase the pressure of the concentrate in stages, and the high-pressure nanofiltration membrane module is used to separate copper ions in the concentrate for concentration. The product water collection module includes a concentrate collection tank and a fresh water collection tank. The concentrate collection tank is used to store the concentrate containing high concentrations of copper ions produced by high-pressure nanofiltration, and the fresh water collection tank is used to store the fresh water produced by high-pressure nanofiltration. Both the concentrate collection tank and the fresh water collection tank are equipped with level sensors to control the liquid level. The chemical cleaning module includes a cleaning tank and a cleaning pump, wherein the cleaning tank is used to store the cleaning solution and the cleaning pump is used to deliver the cleaning solution to the high-pressure nanofiltration membrane module to clean the membrane surface. The intelligent control module includes a programmable logic controller (PLC), a pressure sensor, a flow sensor, and a touch screen. The PLC collects operating parameters through the pressure and flow sensors and displays and controls the operating status through the touch screen to achieve fully automatic operation.

[0006] Preferably, the high-pressure nanofiltration membrane assembly in the high-pressure nanofiltration concentration module adopts a three-layer composite membrane structure. The three-layer composite membrane includes a support layer, a separation layer, and an intercalation layer. The molecular weight cutoff range is 150-300 Daltons. It can allow monovalent ions to pass through and retain divalent ions. The intercalation layer is used to improve the smoothness and antifouling properties of the membrane surface.

[0007] Preferably, the high-pressure pump in the high-pressure nanofiltration concentration module operates at a pressure of 10-15 MPa, and the inter-stage booster pump operates at a pressure of 5-8 MPa. The high-pressure pump and the inter-stage booster pump are connected in sequence to form a multi-stage booster structure.

[0008] Preferably, the scale inhibitor dosing device includes a dosing tank and a dosing pump. The dosing tank has a volume of 50-100L and is made of polyethylene. The dosing pump consists of two metering pumps connected in parallel, each with a power of 10-20W, used to deliver the scale inhibitor from the dosing tank to the concentrated water.

[0009] Preferably, the programmable logic controller of the intelligent control module is connected to the pressure sensor, flow sensor and liquid level sensor through a communication interface. The collected operating parameters include pressure, flow rate and liquid level. The PLC adjusts the operating frequency of the high-pressure pump and the inter-stage booster pump according to the collected parameters, supports network transmission and the transmission lag does not exceed 10 seconds.

[0010] Preferably, the concentrate from the copper foil rinsing water received by the concentrate collection module has the following characteristics: copper ion content of 20-30 g / L, acid content of 10-15 g / L, pH ≤ 3, chlorine content ≤ 100 ppm, and COD content ≤ 500 ppm.

[0011] Preferably, the copper ion content of the concentrate in the concentrate collection tank is ≥60g / L, the daily concentrate influent volume is ≥30m³, and the concentrate production volume is ≤4.5m³.

[0012] Preferably, a method for concentrating rinsing water for lithium-ion battery copper plating based on high-pressure nanofiltration includes the following steps: S1. Inlet water pretreatment: The concentrated water from the electroplated copper foil rinsing after two-stage nanofiltration pretreatment is transported to the concentrated water tank of the concentrated water collection module. The concentrated water pressure is increased to the initial operating pressure by a booster pump. At the same time, scale inhibitor is added to the concentrated water through a scale inhibitor dosing device to complex scale ions. S2. High-pressure nanofiltration concentration: The concentrated water after step S1 is transported to the high-pressure nanofiltration concentration module. The pressure of the concentrated water is increased to 10-15MPa by a high-pressure pump, and then further increased to 5-8MPa by an inter-stage booster pump. The concentrated water is separated by an acid-resistant and fouling-resistant high-pressure nanofiltration membrane module to produce a concentrated solution with a copper ion concentration ≥60g / L and fresh water. S3. Separation and collection of product water: The concentrate produced in step S2 is transported to the concentrate collection tank and the fresh water is transported to the fresh water collection tank. The liquid level is monitored by the liquid level sensors in the concentrate collection tank and the fresh water collection tank and the system operation status is adjusted by the intelligent control module. S4. System maintenance: Based on the fouling status of the high-pressure nanofiltration membrane module, prepare cleaning solution through the cleaning water tank of the chemical cleaning module, and use the cleaning pump to deliver the cleaning solution to the high-pressure nanofiltration membrane module for cleaning. S5. Intelligent control: The PLC of the intelligent control module collects the pressure, flow and liquid level parameters of the system in real time, and adjusts the operating status of the high-pressure pump, inter-stage booster pump and scale inhibitor dosing device according to the collected parameters to achieve fully automatic control.

[0013] Preferably, the high-pressure nanofiltration membrane module in step S2 includes multiple membrane elements arranged in parallel, each membrane element having a pressure resistance rating of 600 PSI, and the membrane elements are encapsulated in fiberglass membrane shells.

[0014] Preferably, the cleaning solution in step S4 is an acidic or alkaline cleaning agent, the cleaning cycle is once every 20-40 days, the flow rate of the cleaning pump is 8-12 m³ / h, and the head is 40-50 m.

[0015] This invention provides a high-pressure nanofiltration-based system and method for concentrating rinsing water from lithium-ion battery copper foil plating. It offers the following advantages: 1. This invention integrates pressure, flow, and level sensors based on a PLC through an intelligent control module, with a data acquisition frequency of 1 time / second. It adjusts pump speed and valve opening through a PID algorithm, controlling the error of operating parameters within ±1%, and network transmission lag ≤10 seconds. It supports 24-hour unattended operation, and the touch screen displays process parameters and fault alarms in real time. The data storage capacity can reach 1 year. Compared with traditional manual or semi-automatic systems, it reduces the need for manual intervention and improves operating accuracy and reliability.

[0016] 2. This invention uses an acid-resistant and fouling-resistant high-pressure nanofiltration membrane and a multi-stage pressurization design to increase the copper ion concentration in the lithium battery electroplating copper foil rinsing water concentrate from 20-30 g / L to ≥60 g / L, achieving a concentration ratio of 2-3 times. The three-layer composite structure of the membrane module, combined with intercalation technology, ensures a high rejection rate (≥90%) for divalent ions while allowing monovalent ions to pass through. The separation efficiency is significantly better than that of traditional single-stage nanofiltration systems.

[0017] 3. The high-pressure nanofiltration membrane of this invention adopts an acid-resistant and fouling-resistant design. The intercalation technology in the three-layer composite membrane reduces the surface roughness of the membrane to below 10nm, reducing the adsorption and corrosion of organic matter (such as additives with COD≤500ppm) and acidic substances (pH≤3). Compared with traditional nanofiltration membranes, the membrane flux decay rate is reduced to less than 5%, the cleaning cycle is extended to 20-40 days, and the membrane service life can reach more than 3 years. The regular maintenance of the chemical cleaning module further restores the membrane performance to more than 95% of the initial value, significantly improving the long-term operational stability of the system in a strongly acidic wastewater environment.

[0018] 4. This invention uses a multi-stage pressurization design with a high-pressure pump (10-15MPa) and an inter-stage booster pump (5-8MPa) to concentrate concentrated water with a daily influent volume of ≥30m³ to a product volume of ≤4.5m³, achieving a volume reduction rate of over 85%. The multi-stage pressure gradation optimizes the membrane flux (10-15L / m²·h) and concentration ratio, improving the concentration efficiency by approximately 30% compared to a single-stage high-pressure system, reducing the wastewater treatment load, and providing convenience for subsequent wastewater treatment or reuse. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the intelligent control module of the present invention; Figure 2 This is a schematic cross-sectional view of the three-layer composite membrane element of the present invention; Figure 3 This is a flowchart of the lithium battery electroplating copper foil rinsing water concentration method based on high-pressure nanofiltration according to the present invention.

[0020] Among them, 1. Intercalation layer; 2. Separation layer; 3. Support layer. Detailed Implementation

[0021] The technical solution of the present invention will now be clearly and completely described 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.

[0022] Please see the appendix Figure 1 - Appendix Figure 2 This invention provides a lithium-ion battery electroplating copper foil rinsing water concentration system based on high-pressure nanofiltration, comprising the following components: The concentrate collection module includes a concentrate tank, a level gauge, and a pH meter. The concentrate tank is used to receive and buffer the concentrate from the rinsing water of the electroplated copper foil after two-stage nanofiltration pretreatment. The level gauge is used to monitor the liquid level in the concentrate tank, and the pH meter is used to monitor the pH value of the concentrate. The pretreatment module includes a booster pump and an antiscalant dosing device, wherein the booster pump is used to increase the pressure of the concentrate, and the antiscalant dosing device is used to add antiscalant to the concentrate to prevent scaling on the membrane surface; The high-pressure nanofiltration concentration module includes a high-pressure pump, an interstage booster pump, and an acid-resistant and fouling-resistant high-pressure nanofiltration membrane module. The high-pressure pump and the interstage booster pump are used to increase the pressure of the concentrate in stages, and the high-pressure nanofiltration membrane module is used to separate copper ions in the concentrate for concentration. The product water collection module includes a concentrate collection tank and a fresh water collection tank. The concentrate collection tank is used to store the concentrate containing high concentrations of copper ions produced by high-pressure nanofiltration, and the fresh water collection tank is used to store the fresh water produced by high-pressure nanofiltration. Both the concentrate collection tank and the fresh water collection tank are equipped with level sensors to control the liquid level. The chemical cleaning module includes a cleaning tank and a cleaning pump, wherein the cleaning tank is used to store the cleaning solution and the cleaning pump is used to deliver the cleaning solution to the high-pressure nanofiltration membrane module to clean the membrane surface. The intelligent control module includes a programmable logic controller (PLC), a pressure sensor, a flow sensor, and a touch screen. The PLC collects operating parameters through the pressure and flow sensors and displays and controls the operating status through the touch screen to achieve fully automatic operation.

[0023] Specifically, the concentrate collection module's concentrate tank is made of 316L stainless steel with a volume of 10m³, capable of withstanding corrosion in acidic environments (pH≤3) to ensure long-term operational stability. The level gauge uses an ultrasonic or radar design with a range of 0-5m and an output signal of 4-20mA, offering high accuracy and anti-interference capabilities. It can monitor the concentrate level in real time to prevent overflow or no-load operation. The pH meter uses the PH / ORP-3500 series, with a range of 0-14, equipped with acid-resistant electrodes, capable of withstanding highly corrosive environments with concentrated concentrate containing 10-15g / L of acid. Its output signal is also 4-20mA, facilitating PLC integration. The pretreatment module's booster pump is a centrifugal pump manufactured by Southern Pump Industry, with a flow rate of 15m³ / h, a head of 34.5m, a motor power of 3.0kW, and an energy efficiency rating of IE4. It is equipped with U-PVC piping and a pressure gauge to ensure the pressure is increased to the initial value required for subsequent high-pressure nanofiltration (approximately 2-3MPa). The scale inhibitor dosing device's dosing tank and pump work in tandem. The dosing tank is equipped with a level alarm to prevent insufficient scale inhibitor from affecting system operation. The high-pressure pump and interstage booster pump of the high-pressure nanofiltration concentration module are both made of 316L stainless steel, offering strong acid resistance. The high-pressure pump has a flow rate of 15 m³ / h, a head of 213 m, and a power of 15.0 kW. The interstage booster pump has a flow rate of 5 m³ / h, a head of 124 m, and a power of 3.0 kW. Both are controlled by a frequency converter (ABB or Mitsubishi brand, frequency range 0-50Hz) to achieve graded pressure regulation. The high-pressure nanofiltration membrane module includes eight 8040 type membrane elements. The membrane housing has a pressure resistance rating of 600 PSI and is made of fiberglass, exhibiting excellent pressure resistance and corrosion resistance. The concentrate and freshwater collection tanks of the permeate collection module each have a volume of 10m³ and are made of 316L stainless steel. The level sensors use a magnetic flap or float design with a range of 0-5m and are interlocked with the PLC to control the pump's start and stop, preventing overload or dry running. The chemical cleaning module has a cleaning water tank with a volume of 2000L, made of polyethylene (PE), which is resistant to acid and alkali corrosion. The cleaning pump has a flow rate of 10m³ / h, a head of 43m, and a power of 2.2kW. It is equipped with 316L stainless steel piping and a pressure gauge to ensure that the cleaning solution is evenly distributed on the membrane module surface. The PLC for the intelligent control module is from Siemens, Mitsubishi, or Omron, and supports multi-channel I / O expansion. The pressure sensor has a range of 0-20MPa, the flow sensor is electromagnetic with a range of 0-20m³ / h, and the touch screen is from Siemens or Weintek with a resolution of no less than 800×600. It supports process flow diagram display, parameter setting, and fault alarm functions. The system is remotely monitored via Ethernet, and the data refresh time does not exceed 30 seconds.

[0024] The high-pressure nanofiltration membrane module in the high-pressure nanofiltration concentration module adopts a three-layer composite membrane structure, which includes a support layer 3, a separation layer 2 and an intercalation layer 1. The molecular weight cutoff range is 150-300 Daltons. It can pass through monovalent ions and retain divalent ions. The intercalation layer 1 is used to improve the smoothness and antifouling properties of the membrane surface.

[0025] Specifically, the support layer 3 is made of high-strength polyester nonwoven fabric, providing mechanical strength and stability; the separation layer 2 is made of polyamide material, which forms a dense structure through a chemical cross-linking process, ensuring a high rejection rate (≥95%) for divalent ions (such as Cu²⁺, SO₄²⁻); the intercalation layer 1 is a proprietary modified layer, which may contain nanoscale inorganic materials or hydrophilic polymers. It is embedded into the surface of the separation layer 2 through the intercalation layer 1 process, reducing the membrane surface roughness to below 10 nm and improving the ability to resist organic matter adsorption. The selection of the molecular weight cutoff (MWCO) range of 150-300 Daltons is based on the molecular weight distribution of additive molecules (such as SPS, HEC, gelatin, and protein), ensuring a permeability of ≥80% for monovalent ions (such as Cl⁻, F⁻) and a rejection rate of ≥90% for divalent ions, achieving efficient concentration of copper ions. The application of intercalation technology significantly improves the membrane's antifouling properties. Under conditions where COD content is ≤500ppm, the membrane flux decay rate is controlled within 5%, extending the service life by approximately 50% compared to traditional dual-layer nanofiltration membranes. The membrane element adopts a spiral wound structure with a diameter of 8 inches and a length of 40 inches. The area of ​​a single membrane is approximately 37m², and the operating pressure range is 5-15MPa. It can operate stably in acidic environments (pH≤3) and is suitable for the high-load treatment requirements of lithium battery wastewater.

[0026] The high-pressure pump in the high-pressure nanofiltration concentration module operates at a pressure of 10-15 MPa, and the inter-stage booster pump operates at a pressure of 5-8 MPa. The high-pressure pump and the inter-stage booster pump are connected in sequence to form a multi-stage booster structure.

[0027] Specifically, the multi-stage pressurization structure of the high-pressure nanofiltration concentration module maximizes concentration efficiency through the coordinated operation of a high-pressure pump and inter-stage booster pumps. The high-pressure pump operates at a pressure range of 10-15 MPa, calculated based on the initial copper ion concentration (20-30 g / L) and target concentration (≥60 g / L) in the concentrate. This pressure compresses the concentrate to approximately one-third of its volume while maintaining a membrane flux of 10-15 L / m²·h. The inter-stage booster pump operates at a pressure range of 5-8 MPa to treat the concentrate after the first stage of concentration, further increasing the concentration ratio to 2-3 times and ensuring a concentrate production rate ≤4.5 m³ / d. The high-pressure pump and inter-stage booster pump are connected in series via 316L stainless steel piping with a diameter of DN50, equipped with pressure gauges (range 0-25 MPa) and flow control valves for real-time monitoring and adjustment of pressure distribution. Both pumps employ variable frequency control, with inverters of 15.0kW and 3.0kW respectively, and a frequency adjustment range of 0-50Hz. They can dynamically adjust the speed according to the influent flow rate and membrane fouling level, reducing energy consumption by approximately 20%. The multi-stage pressurization design improves concentration efficiency by approximately 30% compared to a single-stage high-pressure pump system, while reducing the pressure load on the membrane module and extending membrane life to more than 3 years.

[0028] The scale inhibitor dosing device includes a dosing tank and a dosing pump. The dosing tank has a volume of 50-100L and is made of polyethylene. The dosing pump consists of two metering pumps connected in parallel, each with a power of 10-20W, used to deliver the scale inhibitor from the dosing tank to the concentrated water.

[0029] Specifically, the scale inhibitor dosing device's tank volume range of 50-100L is designed to accommodate a daily inflow of 30m³ of water and a scale inhibitor dosage ratio (typically 5-10mg / L). 50L is the minimum operating capacity, while 100L can meet the needs of continuous operation for 24 hours, avoiding frequent replenishment. The dosing tank is made of polyethylene (PE), which has excellent acid and alkali resistance and anti-aging properties. The wall thickness is no less than 5mm. It features an inlet and vent valve at the top, and a drain valve at the bottom for easy maintenance and cleaning. The dosing pump uses two parallel metering pumps, model reference SKEODMS200 series, with a single pump power range of 10-20W (corresponding to 220V voltage), a flow rate adjustment range of 0-200mL / min, and an accuracy of ±1%. The parallel design enables redundant operation; if one pump fails, the other can continue operating, ensuring system continuity. The scale inhibitor is selected from polycarboxylic acid or phosphonic acid compounds, which can effectively complex scale-forming ions such as Ca²⁺ and Mg²⁺ in the water. The dosage is automatically calculated and adjusted by PLC based on the hardness and flow rate of the influent to prevent the formation of calcium carbonate or calcium sulfate deposits on the membrane surface. The device is equipped with a liquid level sensor (range 0-1m) and a low liquid level alarm function. When the scale inhibitor level is below 20%, an alarm is triggered to remind the operator to replenish it.

[0030] The programmable logic controller (PLC) of the intelligent control module is connected to the pressure sensor, flow sensor, and level sensor through a communication interface. The collected operating parameters include pressure, flow rate, and level. The PLC adjusts the operating frequency of the high-pressure pump and the inter-stage booster pump according to the collected parameters. It supports network transmission with a transmission lag of no more than 10 seconds.

[0031] Specifically, the PLC of the intelligent control module is the core control unit, supporting at least 32 digital inputs / outputs and 8 analog inputs / outputs. The communication interface uses RS485 or Ethernet protocol, and it connects to pressure sensors, flow sensors, and level sensors via shielded cables (RVVP2×1.5mm²) to ensure stable signal transmission. Pressure sensors are installed at the outlets of the high-pressure pump and inter-stage booster pump, with a range of 0-20MPa, accuracy ±0.5%FS, and an output signal of 4-20mA. Flow sensors are installed in the inlet and product water pipelines, with a range of 0-20m³ / h, accuracy ±1%, and an electromagnetic design with strong acid resistance. Level sensors are distributed in the concentrate tank, concentrate collection tank, and desalination collection tank, outputting a 24VDC switching signal. The PLC collects parameters including inlet water pressure, pre-membrane pressure, concentrate flow rate, desalination flow rate, and liquid levels in each tank, with a sampling frequency of once per second. It analyzes membrane fouling trends using a built-in algorithm and adjusts the inverter frequencies (range 0-50Hz) of the high-pressure pump and inter-stage booster pump to achieve precise pressure and flow control. The touchscreen supports multi-screen display, including process flow diagrams, real-time parameter curves, and alarm records. Network transmission uses industrial Ethernet, with transmission lag controlled within 5-10 seconds. Data storage capacity is at least one year's worth and supports USB export. The system has a self-diagnostic function; when pressure exceeds limits or flow is abnormal, it automatically shuts down and issues audible and visual alarms to ensure operational safety.

[0032] The concentrate from the copper foil rinsing water received by the concentrate collection module has the following characteristics: copper ion content of 20-30 g / L, acid content of 10-15 g / L, pH ≤ 3, chlorine content ≤ 100 ppm, and COD content ≤ 500 ppm.

[0033] Specifically, the concentrate collected by the copper foil rinsing module originates from the copper foil electroplating process in lithium battery production. It is formed after activated carbon adsorption, security filtration, and two-stage nanofiltration pretreatment. The copper ion content ranges from 20-30 g / L, introduced from electroplating solution residue and the rinsing process; the fluctuation range depends on the production batch and the volume of rinsing water. The acid content is 10-15 g / L, mainly sulfuric acid or nitric acid, with a pH ≤ 3 reflecting the strong acidity of the concentrate. The chlorine content ≤ 100 ppm originates from process water or additive decomposition. The COD content ≤ 500 ppm is contributed by organic additives (such as SPS, HEC, gelatin, and protein), with molecular weights ranging from 200-1000 Daltons. In addition, the concentrate may contain hydrogen peroxide (≤ 0.01%) and high-valence metal ions (such as Fe³⁺ and Zn²⁺, with a total content ≤ 2000 ppm). The system must possess acid resistance, anti-fouling properties, and high selectivity. The inner wall of the concentrate tank is coated with an anti-corrosion coating, and the probes of the level gauge and pH meter are made of titanium alloy or Hastelloy alloy to ensure long-term stable operation in harsh chemical environments. Inlet water is delivered to the concentrate tank via a DN50 U-PVC pipeline, equipped with a manual valve and a filter screen (5μm pore size) to prevent suspended particulate matter from entering subsequent modules.

[0034] The copper ion content of the concentrate in the concentrate collection tank is ≥60g / L, the daily concentrate influent volume is ≥30m³, and the concentrate production volume is ≤4.5m³.

[0035] Specifically, the copper ion content of the concentrate is ≥60g / L, achieved through selective retention by a high-pressure nanofiltration membrane, reaching 62-65g / L in actual operation, meeting the economic requirements for copper resource recovery. The daily concentrate influent volume is ≥30m³, calculated based on an 8-hour shift operation and a processing capacity of 3.75m³ / h. The system is configured with 2.0m³ / h equipment and considers an 80% uptime to ensure sufficient capacity. A concentrate production rate ≤4.5m³ / d corresponds to a concentration ratio of approximately 6-7 times, and a freshwater production rate of approximately 25.5m³ / d, which can be reused in the rinsing process or further treated. The concentrate collection tank is equipped with a stirring device (0.75kW, 60rpm) to prevent copper salt precipitation; the freshwater collection tank is connected to the recycled water network and equipped with a conductivity meter (range 0-2000μS / cm) to monitor water quality, ensuring the freshwater conductivity is ≤500μS / cm. System operating parameters are recorded in real time via PLC, and daily data is stored on a local MMC card (capacity ≥16GB) for easy traceability and optimization.

[0036] Please see the appendix Figure 3 A method for concentrating rinsing water for lithium-ion battery copper plating based on high-pressure nanofiltration includes the following steps: S1. Inlet water pretreatment: The concentrated water from the electroplated copper foil rinsing after two-stage nanofiltration pretreatment is transported to the concentrated water tank of the concentrated water collection module. The concentrated water pressure is increased to the initial operating pressure by a booster pump. At the same time, scale inhibitor is added to the concentrated water through a scale inhibitor dosing device to complex scale ions. S2. High-pressure nanofiltration concentration: The concentrated water after step S1 is transported to the high-pressure nanofiltration concentration module. The pressure of the concentrated water is increased to 10-15MPa by a high-pressure pump, and then further increased to 5-8MPa by an inter-stage booster pump. The concentrated water is separated by an acid-resistant and fouling-resistant high-pressure nanofiltration membrane module to produce a concentrated solution with a copper ion concentration ≥60g / L and fresh water. S3. Separation and collection of product water: The concentrate produced in step S2 is transported to the concentrate collection tank and the fresh water is transported to the fresh water collection tank. The liquid level is monitored by the liquid level sensors in the concentrate collection tank and the fresh water collection tank and the system operation status is adjusted by the intelligent control module. S4. System maintenance: Based on the fouling status of the high-pressure nanofiltration membrane module, prepare cleaning solution through the cleaning water tank of the chemical cleaning module, and use the cleaning pump to deliver the cleaning solution to the high-pressure nanofiltration membrane module for cleaning. S5. Intelligent control: The PLC of the intelligent control module collects the pressure, flow and liquid level parameters of the system in real time, and adjusts the operating status of the high-pressure pump, inter-stage booster pump and scale inhibitor dosing device according to the collected parameters to achieve fully automatic control.

[0037] Specifically, in step S1, concentrate enters the concentrate tank via a DN50 pipeline by gravity or pumping. The initial operating pressure is increased to 2-3 MPa by a booster pump to ensure the inlet water requirements of the subsequent high-pressure nanofiltration module. The booster pump is equipped with a frequency converter (3.0 kW), and the speed is adjusted based on feedback from the flow sensor. The scale inhibitor dosage is 5-10 mg / L, automatically calculated by the PLC based on the inlet water hardness (usually ≤2000 ppm) and flow rate. The dosing pump runs for approximately 20-24 hours per day. A stirrer (50W) is installed at the bottom of the dosing tank to ensure uniform dispersion of the scale inhibitor. In step S2, the pressure grading design of the high-pressure pump and the inter-stage booster pump is based on the concentration ratio requirements. The outlet pressure of the high-pressure pump is 10-15 MPa, controlled by the frequency converter. The inlet of the inter-stage booster pump is connected to the concentrate side of the high-pressure pump, and the outlet pressure is 5-8 MPa to further compress the concentrate volume. The membrane module operating temperature is controlled between 15-40℃ to avoid high temperatures affecting membrane performance. In step S3, the concentrate and fresh water are transported separately through 316L stainless steel pipelines (DN25). The liquid level sensor trigger thresholds are set to 80% (high level) and 20% (low level). The PLC controls the start and stop of the permeate pump (power 0.75-1.1kW) based on the liquid level signal. The pump heads are 73m (concentrate) and 71m (fresh water), respectively. In step S4, the cleaning solution is prepared with a concentration of 0.5-2% (such as citric acid or NaOH solution). The cleaning time is approximately 2-4 hours, and the membrane flux recovery rate after cleaning is ≥95%. In step S5, the PLC adjusts the pump speed and valve opening using a PID algorithm. The parameter acquisition frequency is 1 time / second. The system supports manual / automatic switching, and the touch screen displays real-time curves and historical data. The operator can adjust the set values ​​via password (three-level access).

[0038] The high-pressure nanofiltration membrane module in step S2 includes multiple membrane elements arranged in parallel, each membrane element having a pressure rating of 600 PSI, and the membrane elements are encapsulated in fiberglass membrane shells.

[0039] Specifically, the high-pressure nanofiltration membrane module in step S2 uses eight 8040-type membrane elements connected in parallel. Each membrane has an effective area of ​​37 m², for a total membrane area of ​​296 m², capable of processing 30 m³ of influent per day while maintaining a flux of 10-15 L / m²·h. The membrane elements have a design minimum pressure rating of 600 PSI (approximately 4.14 MPa), with the actual operating pressure of 10-15 MPa provided by a multi-stage booster pump. The membrane housing is made of fiberglass reinforced plastic (FRP) with a wall thickness of 8-10 mm, offering strong acid resistance. It is equipped with end caps and O-ring seals to ensure leak-free operation. The parallel design is connected via 316L stainless steel manifolds with a diameter of DN80. Each membrane is equipped with an independent pressure gauge (range 0-20 MPa) and a manual valve for easy maintenance and replacement of individual membranes. The membrane element has an internal spiral wound structure with a membrane width of 1.0-1.2m, 30-40 layers, and a channel height of 0.8-1.0mm, ensuring smooth separation of concentrate and desalination. During operation, the concentrate flow rate gradually decreases to below 5m³ / h, while the desalination flow rate is maintained at around 25m³ / h. The separation efficiency is closely related to the smoothness of the membrane surface and the intercalation technology.

[0040] The cleaning solution in step S4 is an acidic or alkaline cleaning agent. The cleaning cycle is once every 20-40 days. During cleaning, the flow rate of the cleaning pump is 8-12 m³ / h, and the head is 40-50 m.

[0041] Specifically, in step S4, an acidic cleaning agent (such as a 2% citric acid solution, pH 2-3) is selected to remove inorganic scale, or an alkaline cleaning agent (such as a 1% NaOH solution, pH 11-12) is selected to remove organic contaminants. The cleaning solution is prepared in a 2000L PE water tank equipped with a stirrer (100W power, 100rpm speed) to ensure uniformity. The cleaning cycle range is 20-40 days, determined based on the COD content (≤500ppm) and membrane flux decay rate (5-10%). When the water quality is poor, the cycle is shortened to 20-25 days, and can be extended to 35-40 days during stable operation. The cleaning pump flow rate range is 8-12m³ / h, which is adjusted by a frequency converter (2.2kW power). The actual flow rate is dynamically adjusted according to the number of membrane modules (e.g., 10m³ / h for 8 membranes). The head range is 40-50m to ensure that the cleaning solution covers all membrane channels. The cleaning pressure is controlled at 0.2-0.5MPa to avoid damaging the membrane structure. The cleaning process includes pre-rinsing (clean water, 10 minutes), circulating cleaning (cleaning solution, 2 hours), and post-rinsing (clean water, 20 minutes). Waste liquid is discharged to the wastewater treatment system through a DN50 drain pipe. After cleaning, the membrane flux recovers to 95%-98% of its initial value, and the water consumption for a single cleaning is approximately 2-3 m³.

[0042] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A lithium-ion battery electroplating copper foil rinsing water concentration system based on high-pressure nanofiltration, characterized in that, It includes the following components: The concentrate collection module includes a concentrate tank, a level gauge, and a pH meter. The concentrate tank is used to receive and buffer the concentrate from the rinsing water of the electroplated copper foil after two-stage nanofiltration pretreatment. The level gauge is used to monitor the liquid level in the concentrate tank, and the pH meter is used to monitor the pH value of the concentrate. The pretreatment module includes a booster pump and an antiscalant dosing device, wherein the booster pump is used to increase the pressure of the concentrate, and the antiscalant dosing device is used to add antiscalant to the concentrate to prevent scaling on the membrane surface; The high-pressure nanofiltration concentration module includes a high-pressure pump, an interstage booster pump, and an acid-resistant and fouling-resistant high-pressure nanofiltration membrane module. The high-pressure pump and the interstage booster pump are used to increase the pressure of the concentrate in stages, and the high-pressure nanofiltration membrane module is used to separate copper ions in the concentrate for concentration. The product water collection module includes a concentrate collection tank and a fresh water collection tank. The concentrate collection tank is used to store the concentrate containing high concentrations of copper ions produced by high-pressure nanofiltration, and the fresh water collection tank is used to store the fresh water produced by high-pressure nanofiltration. Both the concentrate collection tank and the fresh water collection tank are equipped with level sensors to control the liquid level. The chemical cleaning module includes a cleaning tank and a cleaning pump, wherein the cleaning tank is used to store the cleaning solution and the cleaning pump is used to deliver the cleaning solution to the high-pressure nanofiltration membrane module to clean the membrane surface. The intelligent control module includes a programmable logic controller (PLC), a pressure sensor, a flow sensor, and a touch screen. The PLC collects operating parameters through the pressure and flow sensors and displays and controls the operating status through the touch screen to achieve fully automatic operation.

2. The lithium-ion battery electroplating copper foil rinsing water concentration system based on high-pressure nanofiltration according to claim 1, characterized in that, The high-pressure nanofiltration membrane assembly in the high-pressure nanofiltration concentration module adopts a three-layer composite membrane structure. The three-layer composite membrane includes a support layer (3), a separation layer (2), and an intercalation layer (1). The molecular weight cutoff range is 150-300 Daltons. It can pass through monovalent ions and retain divalent ions. The intercalation layer (1) is used to improve the smoothness and antifouling properties of the membrane surface.

3. The lithium-ion battery electroplating copper foil rinsing water concentration system based on high-pressure nanofiltration according to claim 1, characterized in that, The high-pressure pump in the high-pressure nanofiltration concentration module operates at a pressure of 10-15 MPa, and the inter-stage booster pump operates at a pressure of 5-8 MPa. The high-pressure pump and the inter-stage booster pump are connected in sequence to form a multi-stage booster structure.

4. The lithium-ion battery electroplating copper foil rinsing water concentration system based on high-pressure nanofiltration according to claim 1, characterized in that, The scale inhibitor dosing device includes a dosing tank and a dosing pump. The dosing tank has a volume of 50-100L and is made of polyethylene. The dosing pump consists of two metering pumps connected in parallel, each with a power of 10-20W, used to deliver the scale inhibitor from the dosing tank to the concentrated water.

5. The lithium-ion battery electroplating copper foil rinsing water concentration system based on high-pressure nanofiltration according to claim 1, characterized in that, The programmable logic controller (PLC) of the intelligent control module is connected to the pressure sensor, flow sensor, and level sensor via a communication interface. The collected operating parameters include pressure, flow rate, and level. The PLC adjusts the operating frequency of the high-pressure pump and the inter-stage booster pump according to the collected parameters. It supports network transmission with a transmission lag of no more than 10 seconds.

6. The lithium-ion battery electroplating copper foil rinsing water concentration system based on high-pressure nanofiltration according to claim 1, characterized in that, The concentrated water collected by the concentrated water collection module has the following characteristics: copper ion content of 20-30 g / L, acid content of 10-15 g / L, pH ≤ 3, chlorine content ≤ 100 ppm, and COD content ≤ 500 ppm.

7. The lithium-ion battery electroplating copper foil rinsing water concentration system based on high-pressure nanofiltration according to claim 1, characterized in that, The copper ion content of the concentrate in the concentrate collection tank is ≥60g / L, the daily concentrate influent volume is ≥30m³, and the concentrate production volume is ≤4.5m³.

8. A method for concentrating rinsing water for lithium-ion battery electroplating copper foil based on high-pressure nanofiltration, characterized in that, The lithium-ion battery electroplating copper foil rinsing water concentration system based on high-pressure nanofiltration as described in any one of claims 1-7 comprises the following steps: S1. Inlet water pretreatment: The concentrated water from the electroplated copper foil rinsing after two-stage nanofiltration pretreatment is transported to the concentrated water tank of the concentrated water collection module. The concentrated water pressure is increased to the initial operating pressure by a booster pump. At the same time, scale inhibitor is added to the concentrated water through a scale inhibitor dosing device to complex scale ions. S2. High-pressure nanofiltration concentration: The concentrated water after step S1 is transported to the high-pressure nanofiltration concentration module. The pressure of the concentrated water is increased to 10-15MPa by a high-pressure pump, and then further increased to 5-8MPa by an inter-stage booster pump. The concentrated water is separated by an acid-resistant and fouling-resistant high-pressure nanofiltration membrane module to produce a concentrated solution with a copper ion concentration ≥60g / L and fresh water. S3. Separation and collection of product water: The concentrate produced in step S2 is transported to the concentrate collection tank and the fresh water is transported to the fresh water collection tank. The liquid level is monitored by the liquid level sensors in the concentrate collection tank and the fresh water collection tank and the system operation status is adjusted by the intelligent control module. S4. System maintenance: Based on the fouling status of the high-pressure nanofiltration membrane module, prepare cleaning solution through the cleaning water tank of the chemical cleaning module, and use the cleaning pump to deliver the cleaning solution to the high-pressure nanofiltration membrane module for cleaning. S5. Intelligent control: The PLC of the intelligent control module collects the pressure, flow and liquid level parameters of the system in real time, and adjusts the operating status of the high-pressure pump, inter-stage booster pump and scale inhibitor dosing device according to the collected parameters to achieve fully automatic control.

9. A method for concentrating rinsing water for lithium-ion battery electroplating copper foil based on high-pressure nanofiltration according to claim 8, characterized in that, The high-pressure nanofiltration membrane module in step S2 includes multiple membrane elements arranged in parallel, each membrane element having a pressure rating of 600 PSI, and the membrane elements are encapsulated in fiberglass membrane shells.

10. A method for concentrating rinsing water for lithium-ion battery electroplating copper foil based on high-pressure nanofiltration according to claim 8, characterized in that, The cleaning solution in step S4 is an acidic or alkaline cleaning agent. The cleaning cycle is once every 20-40 days. During cleaning, the flow rate of the cleaning pump is 8-12 m³ / h, and the head is 40-50 m.

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