Method for concentrating, separating, purifying and recycling low-concentration copper pyrophosphate solution

Abstract

The invention discloses a method for concentrating, separating, purifying and recycling a low-concentration copper pyrophosphate solution, which mainly solves the three core problems of cost, environmental protection and resource utilization caused by invalidation of a copper pyrophosphate plating solution in the industrial electroplating (especially electroplating of a printed circuit board (PCB)) process. In other words, metal ions are unbalanced, impurity ions are accumulated, and the pH value is unstable; according to the method, ions in a thin liquid are selectively migrated into a concentrated liquid through a membrane stack, so that the conductivity of a concentrated liquid chamber reaches 50000-120000 [mu] s / cm, and the conductivity of a thin liquid chamber reaches 100-1000 [mu] s / cm. The method comprises the following steps: returning the obtained thin liquid to a rinsing bath for recycling, and returning the obtained concentrated liquid to an electroplating bath for recycling; and the obtained thin liquid can be conveyed to the reverse osmosis module for treatment, the generated thick liquid is returned to the thin liquid storage barrel, and the generated pure water is used for each process section of the production line. The method is low in energy consumption, high in product quality and not easy to generate membrane pollution.

Description

Technical Field

[0001] This invention relates to the field of environmental protection technology, and more particularly to the field of water treatment. Specifically, it relates to a method for concentrating, separating, purifying, and recycling a low-concentration copper pyrophosphate solution. Background Technology

[0002] Copper pyrophosphate electroplating has a wide range of applications. However, the rinsing water after copper pyrophosphate electroplating contains a large amount of heavy metals from copper pyrophosphate complexes, posing significant challenges for subsequent environmental treatment and resulting in waste of non-ferrous copper and electroplating raw materials. Therefore, addressing the heavy metals from copper pyrophosphate complexes in the rinsing water after copper pyrophosphate electroplating is a crucial and indispensable measure, beneficial for reducing resource waste and environmental harm.

[0003] Patent CN104108812A discloses a method for treating copper pyrophosphate electroplating wastewater, which mainly involves three steps: recovering pyrophosphate ions and breaking the complex, solid-liquid separation, and water reuse. This invention recovers pyrophosphate ions while simultaneously breaking the complex, making the subsequent water reuse process easier to implement. However, it has high energy consumption, and the chemical precipitation method results in low ion selectivity.

[0004] Patent CN103073123A discloses a technology for recycling and reusing electroplating wastewater and its resource recovery. This technology separates electroplating wastewater into various types and a combined wastewater, and then introduces each type of wastewater into its corresponding recycling system for treatment. The permeate from each recycling system is then fed into a reverse osmosis system for filtration. This reduces treatment costs and ensures stable recycled water quality, thus achieving wastewater resource recovery. However, the generated chemical sludge requires proper treatment, and there is a risk that improper control of oxidant dosage or poor sedimentation may affect the operation of subsequent membrane systems.

[0005] Patent CN101439911A discloses a method for treating pyrophosphate copper plating wastewater, specifically for treating alkaline wastewater from electrolytic copper production. This invention uses a dual-layer filtration system of activated carbon and quartz sand as pretreatment, effectively removing some suspended solids, organic matter, and colloids, protecting the subsequent membrane system. Simultaneously, the combination of reverse osmosis and nanofiltration enables the graded reuse of water resources and useful components. Its advantages lie in the fact that the recovered substances do not undergo chemical changes, and the effluent quality is good. However, it requires high-quality influent, and membrane fouling is a key concern. Summary of the Invention

[0006] To address the problems existing in the above-mentioned patents, this invention proposes a method for efficient and energy-saving concentration, separation, purification, and recycling of rinsing water after copper pyrophosphate electroplating. In this method, solution concentration is carried out at low temperatures, effectively avoiding the risk of thermal decomposition of copper pyrophosphate, thus ensuring the chemical stability of the concentrate returned to the electroplating tank and not affecting the electroplating quality. Furthermore, the solution concentration system is easy to modularly design and continuously automate. By optimizing and controlling parameters such as voltage and current density, it can flexibly respond to changes in influent concentration and stably produce the required concentration of concentrate and fresh water. Simultaneously, this method requires little or no additional chemical reagents, avoiding the introduction of new impurity ions, reducing the risk of secondary pollution and the difficulty of subsequent water reuse. In addition, a homogeneous ion exchange membrane is used, which has better anti-fouling performance and mechanical stability, making the system operation more stable, helping to reduce the number of cleaning cycles and lower operating and maintenance costs.

[0007] This invention is specifically implemented through the following technical solutions: A method for concentrating, separating, purifying, and recycling a low-concentration copper pyrophosphate solution, the method comprising the following steps: 1.1 The copper pyrophosphate solution in the washing tank is pumped into the dilute solution storage tank and the concentrated solution storage tank respectively; 1.2 Pour the potassium pyrophosphate solution into the polar liquid storage tank; 1.3 Start the desalination circulation pump, the concentrate circulation pump, and the polar liquid circulation pump to drive the solution to circulate between the membrane stack and the corresponding liquid tank, and control the pipeline pressure and maintain pressure balance by adjusting the valves on each circulation pipeline; 1.4 A constant voltage is applied to the membrane stack to electro-concentrate the solution; 1.5 Monitor the conductivity of the concentrate and dilute chambers in real time, and stop concentration when any of the following conditions are met: • The conductivity of the concentrated liquid chamber reaches 50,000-120,000 μs / cm; • The conductivity of the dilute liquid chamber reaches 100-1000 μs / cm; 1.6 The diluted solution obtained in step 1.5 is returned to the water washing tank for recycling via a pump, and the concentrated solution obtained in step 1.5 is returned to the electroplating tank for recycling via a pump; 1.7 The desalinated solution obtained in step 1.6 is pumped to the reverse osmosis module for processing. The resulting concentrated solution is returned to the desalinated solution storage tank, and the resulting pure water is supplied to each process section of the production line.

[0008] Furthermore, the concentration of the copper pyrophosphate solution is 1-1.5 g / L, and the conductivity is 2000-20000 μs / cm.

[0009] Furthermore, the concentration of the potassium pyrophosphate solution is 35-40 g / L.

[0010] Furthermore, in step 1.3, the control pipeline pressure is <0.06MPa.

[0011] Furthermore, the constant voltage in step 1.4 is 12-18V.

[0012] Furthermore, in step 1.7, the conductivity of the pure water is <10 μs / cm.

[0013] Furthermore, in step 1.4, an electro-concentration module or an electro-concentration module plus a reverse osmosis module is used for concentration; The electroconcentration module includes a membrane stack, a dilute liquid storage tank, a concentrated liquid storage tank, an electrode liquid storage tank, a dilute liquid circulation pump, a concentrated liquid circulation pump, an electrode liquid circulation pump, a rectifier, liquid piping fittings, monitoring components, and electrical control components. The membrane stack includes a dilute liquid chamber, a concentrated liquid chamber, an electrode liquid chamber, a dilute liquid chamber inlet, a dilute liquid chamber outlet, a concentrated liquid chamber inlet, a concentrated liquid chamber outlet, an electrode liquid chamber inlet, an electrode liquid chamber outlet, a positive electrode terminal, and a negative electrode terminal. The inlet of the desalination chamber is connected to the outlet of the desalination circulation pump via a pipeline. The pipeline is equipped with a desalination filter, a desalination flow meter, a desalination flow regulating valve, a desalination pressure transmitter, and a desalination conductivity probe. The outlet of the desalination chamber is connected to the desalination storage tank via a pipeline. The drain valve of the first desalination storage tank is connected to the inlet of the desalination circulation pump via a pipeline. The inlet of the concentrate chamber is connected to the outlet of the concentrate circulation pump via a pipeline. The pipeline is equipped with a concentrate filter, a concentrate flow meter, a concentrate flow regulating valve, a concentrate pressure transmitter, and a concentrate conductivity probe. The outlet of the concentrate chamber is connected to the concentrate storage tank via a pipeline. The concentrate storage tank is connected to the inlet of the concentrate circulation pump via a pipeline. The inlet of the polar liquid chamber is connected to the outlet of the polar liquid circulation pump via a pipeline. The pipeline is equipped with a polar liquid filter, a polar liquid flow meter, a polar liquid flow regulating valve, and a polar liquid pressure transmitter. The outlet of the polar liquid chamber is connected to the polar liquid storage tank via a pipeline. An polar liquid discharge pipeline is provided on the pipeline to drain the liquid from the polar liquid storage tank. The positive terminal of the membrane stack is connected to the positive output terminal of the rectifier via a positive cable, and the negative terminal of the membrane stack is connected to the negative output terminal of the rectifier via a negative cable.

[0014] Furthermore, the monitoring components include a dilute liquid conductivity probe, a concentrated liquid conductivity probe, an electrode liquid pH probe, a waste liquid high level probe, a waste liquid low level probe, a concentrated liquid high level probe, a concentrated liquid low level probe, an electrode liquid high level probe, an electrode liquid low level probe, a dilute liquid pressure transmitter, a concentrated liquid pressure transmitter, an electrode liquid pressure transmitter, a dilute liquid flow meter, a concentrated liquid flow meter, and an electrode liquid flow meter; The desalination tank is equipped with a high-level waste liquid probe and a low-level waste liquid probe. Triggering the high-level waste liquid probe will stop the second rinse water pump to prevent the desalination tank from reaching an excessively high level. Triggering the low-level waste liquid probe will stop the electro-concentration module to prevent equipment damage, and simultaneously start the second rinse water pump to replenish the desalination tank. The desalination tank is equipped with a second and a third drain valve. The second drain valve is connected to the washing tank via a pipeline and a first desalination pump to transfer the concentrated desalination from the tank to the washing tank. The third drain valve is connected to the reverse osmosis module via a pipeline and a second desalination pump to transfer the concentrated desalination from the tank to the reverse osmosis module.

[0015] Furthermore, the concentrated liquid storage tank is equipped with a high-level concentrated liquid probe and a low-level concentrated liquid probe; the high-level concentrated liquid probe will stop the electro-concentration module when triggered to prevent the liquid level in the concentrated liquid storage tank from becoming too high; the low-level concentrated liquid probe will stop the operation of the electro-concentration module when triggered to avoid equipment damage; the concentrated liquid storage tank is equipped with a first concentrated liquid storage tank drain valve and a second concentrated liquid storage tank drain valve, the second concentrated liquid storage tank drain valve being connected to the electroplating tank through a pipeline and a concentrated liquid transfer pump; by opening the first concentrated liquid storage tank drain valve and the second concentrated liquid storage tank drain valve and starting the concentrated liquid transfer pump, the concentrated liquid in the concentrated liquid storage tank can be transported to the electroplating tank.

[0016] Furthermore, the polar liquid storage tank is equipped with a high-level polar liquid probe and a low-level polar liquid probe; triggering the high-level polar liquid probe will activate an alarm to remind the operator to stop adding polar liquid; triggering the low-level polar liquid probe will stop the operation of the electro-concentration module to prevent equipment damage; the polar liquid storage tank is equipped with a second drain valve; opening both the first and second drain valves of the polar liquid storage tank will drain the liquid inside the polar liquid storage tank.

[0017] Furthermore, the electrical control components include a PLC, a touch screen, alarm lights, power indicator lights, emergency stop buttons, silence buttons, contactors, air switches, and relays; Liquid piping fittings include pipes, valves, elbows, tees, dilute liquid filters, concentrate liquid filters, polar liquid filters, dilute liquid flow regulating valves, concentrate liquid flow regulating valves, and polar liquid flow regulating valves.

[0018] In this invention, the ion exchange membrane used in the electroconcentration module is preferably a homogeneous ion exchange membrane. Homogeneous ion exchange membranes have advantages such as high ion exchange capacity and good selective permeability, which can improve concentration efficiency and product quality. Furthermore, to ensure the smooth operation of the electroconcentration process and the concentration effect, this invention optimizes the control of the power supply voltage and the temperature of the dilute chamber.

[0019] By adopting the above technical solution, the present invention has the following beneficial effects: Low energy consumption: Compared with the traditional evaporation concentration method, the electro-concentration concentration process does not require a large amount of heat energy, thus significantly reducing energy consumption.

[0020] High product quality: Concentration is carried out at low temperatures, which avoids the decomposition of copper pyrophosphate and ensures product quality.

[0021] Less prone to membrane fouling: Compared with reverse osmosis concentration, the degree of fouling of ion exchange membranes during electro-concentration is relatively low, which extends the service life of the membrane. Attached Figure Description

[0022] Figure 1 Flowchart of a waste liquid concentration, separation, purification, and recycling method; Figure 2 Structure diagram of a waste liquid concentration, separation, purification and recycling system; in Electroconcentration module (31), membrane stack (1), dilute liquid chamber (1.2), concentrate liquid chamber (1.1), electrode liquid chamber (1.3), positive electrode cable (1.4), negative electrode cable (1.5), dilute liquid chamber inlet (1.2.1), dilute liquid chamber outlet (1.2.2), concentrate liquid chamber inlet (1.1.1), concentrate liquid chamber outlet (1.1.2), electrode liquid chamber inlet (1.3.1), electrode liquid chamber outlet (1.3.2); Fresh liquid storage tank (11), fresh liquid conductivity probe (11.1), waste liquid high level probe (11.3), waste liquid low level probe (11.2). Dilute circulating pump (12), dilute filter (13), dilute flow meter (14), dilute flow regulating valve (15), dilute pressure transmitter (16), first dilute transfer pump (32), second dilute transfer pump (33), first dilute storage tank drain valve (44), second dilute storage tank drain valve (10), third dilute storage tank drain valve (43); concentrate storage tank (2), concentrate conductivity probe (2.1), concentrate high level probe (2.3), concentrate low level probe (2.2), concentrate circulating pump (4), first concentrate storage tank drain valve (3), second concentrate storage tank drain valve (9), concentrate filter (5), concentrate flow meter (6), concentrate flow regulating valve (7), concentrate pressure transmitter (8), concentrate transfer pump (38); Electrolytic liquid storage tank (17), electrolytic liquid pH probe (17.1), electrolytic liquid high level probe (17.3), electrolytic liquid low level probe (17.2). The components include: an polar liquid circulation pump (20), a first drain valve (18) for the polar liquid storage tank, a second drain valve (19) for the polar liquid storage tank, a polar liquid filter (28), a polar liquid flow meter (21), a polar liquid flow regulating valve (22), and a polar liquid pressure transmitter (23). Rectifier (24), electrical control module (25), touch screen (26), three-color alarm light (27); first rinse water transfer pump (42), second rinse water transfer pump (29), water washing tank (30), electro-concentration module (31), first dilute liquid transfer pump (32), second dilute liquid transfer pump (33), second concentrated liquid transfer pump (36), pure water transfer pump (37), production line (35), electroplating tank (39), electrode liquid discharge pipeline (41) Detailed Implementation

[0023] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification.

[0024] like Figure 1 , Figure 2 As shown, the specific steps of the method of the present invention are as follows: (1) Solution injection and initialization 1.1 Pour a copper pyrophosphate solution with a concentration of 1-1.5 g / L and a conductivity of 2000-20000 μs / cm from the water washing tank 30 into the dilute liquid storage tank 11 and the concentrated liquid storage tank 2 respectively, and control the liquid level in both tanks to be no lower than the working liquid level; 1.2 Pour a potassium pyrophosphate solution with a concentration of 35-40 g / L into the polar liquid storage tank 17, ensuring the liquid level is not lower than the working liquid level; (2) Start-up and pressure control of the circulation system 1.3 Start the desalination circulation pump 12, the concentrate circulation pump 4 and the polar liquid circulation pump 20 to drive the solution to circulate between the membrane stack 1 and the corresponding liquid tank, and adjust the desalination flow regulating valve 15, the concentrate flow regulating valve 7 and the polar liquid flow regulating valve 22 to keep the pressure of each pipeline <0.06MPa and maintain pressure balance. (3) Electrochemical concentration 1.4 Turn on rectifier 24 and set it to constant voltage mode, controlling the voltage to 12-18V for concentration; (4) Determination of concentration endpoint 1.5 Monitor the conductivity of the concentrate chamber 1.1 and the dilute chamber 1.2 in real time, and stop concentration when any of the following conditions are met: The conductivity of the concentrate chamber 1.1 reaches 50,000-120,000 μS / cm; The conductivity of the dilute liquid chamber 1.2 reaches 100-1000 μS / cm; (5) Concentrate treatment 1.6 The concentrated dilute solution (conductivity 100-1000 μs / cm, concentration 0.1-0.2 g / L) is returned to the washing tank 30 via the first dilute solution transfer pump 32; 1.7 The concentrated solution (conductivity 50000-120000μs / cm, concentration 9-10g / L) after concentration is completed is transported to the electroplating tank 39 through the concentrated solution transfer pump 38; (6) Deep treatment of desalinated liquor (optional step) 1.8 The dilute solution obtained in step 1.6 is transported to the reverse osmosis module 34 for processing. The resulting concentrate is returned to the dilute storage tank 11 via the second concentrate transfer pump 36. The resulting pure water (conductivity <10μs / cm) is transported to each process section of the production line 35 via the pure water transfer pump 37.

[0025] like Figure 2 As shown, the electroconcentration module 31 used in this invention includes, but is not limited to, a membrane stack 1, a dilute liquid storage tank 11, a concentrate liquid storage tank 2, an electrode liquid storage tank 17, a dilute liquid circulation pump 12, a concentrate liquid circulation pump 4, an electrode liquid circulation pump 20, a rectifier 24, liquid pipeline fittings (not labeled), a monitoring component (not labeled), and an electrical control component (not labeled). Membrane stack 1 includes, but is not limited to, a dilute liquid chamber 1.2, a concentrate liquid chamber 1.1, an electrode liquid chamber 1.3, a dilute liquid chamber inlet 1.2.1, a dilute liquid chamber outlet 1.2.2, a concentrate liquid chamber inlet 1.1.1, a concentrate liquid chamber outlet 1.1.2, an electrode liquid chamber inlet 1.3.1, an electrode liquid chamber outlet 1.3.2, a positive electrode terminal (not labeled), and a negative electrode terminal (not labeled). The inlet 1.2.1 of the desalination chamber is connected to the outlet of the desalination circulation pump 12 via a pipeline. The pipeline is equipped with a desalination filter 13, a desalination flow meter 14, a desalination flow regulating valve 15, a desalination pressure transmitter 16, and a desalination conductivity probe 11.1. The outlet 1.2.2 of the desalination chamber is connected to the desalination storage tank 11 via a pipeline. The drain valve 44 of the first desalination storage tank is connected to the inlet of the desalination circulation pump 12 via a pipeline. The inlet of the concentrate chamber 1.1.1 is connected to the outlet of the concentrate circulation pump 4 via a pipeline. The pipeline is equipped with a concentrate filter 5, a concentrate flow meter 6, a concentrate flow regulating valve 7, a concentrate pressure transmitter 8, and a concentrate conductivity probe 2.1. The outlet of the concentrate chamber 1.1.2 is connected to the concentrate storage tank 2 via a pipeline. The concentrate storage tank 2 is connected to the inlet of the concentrate circulation pump 4 via a pipeline. The inlet 1.3.1 of the polar liquid chamber is connected to the outlet of the polar liquid circulation pump 20 via a pipeline. The pipeline is equipped with a polar liquid filter (28), a polar liquid flow meter 21, a polar liquid flow regulating valve 22, and a polar liquid pressure transmitter 23. The outlet 1.3.2 of the polar liquid chamber is connected to the polar liquid storage tank 17 via a pipeline. The pipeline is equipped with a polar liquid discharge pipe 41 for draining the liquid from the polar liquid storage tank 17. The positive terminal (unlabeled) of membrane stack 1 is connected to the positive output terminal (unlabeled) of rectifier 24 via positive cable 1.4, and the negative terminal (unlabeled) of membrane stack 1 is connected to the negative output terminal (unlabeled) of rectifier 24 via negative cable 1.5. The monitoring components (not labeled) include, but are not limited to, a dilute liquid conductivity probe 11.1, a concentrated liquid conductivity probe 2.1, an extreme liquid pH probe 17.1, a waste liquid high level probe 11.3, a waste liquid low level probe 11.2, a concentrated liquid high level probe 2.3, a concentrated liquid low level probe 2.2, an extreme liquid high level probe 17.3, an extreme liquid low level probe 17.2, a dilute liquid pressure transmitter 16, a concentrated liquid pressure transmitter 8, an extreme liquid pressure transmitter 23, a dilute liquid flow meter 14, a concentrated liquid flow meter 6, and an extreme liquid flow meter 21. The desalination storage tank 11 is equipped with a high-level waste liquid probe 11.3 and a low-level waste liquid probe 11.2. Triggering the high-level waste liquid probe 11.3 will stop the second rinse water transfer pump 29 to prevent excessively high levels. Triggering the low-level waste liquid probe 11.2 will stop the operation of the electro-concentration module 31 to avoid equipment damage, and simultaneously start the second rinse water transfer pump 29 to replenish the desalination storage tank 11. The desalination storage tank 11 is equipped with a second desalination storage tank drain valve 10 and a third desalination storage tank drain valve 43. The second desalination storage tank drain valve 10 is connected to the washing tank 30 via a pipeline and the first desalination transfer pump 32, thus transferring the concentrated desalination from the desalination storage tank 11 to the washing tank 30. The third desalination storage tank drain valve 43 is connected to the reverse osmosis module 34 via a pipeline and the second desalination transfer pump 33, thus transferring the concentrated desalination from the desalination storage tank 11 to the reverse osmosis module 34. The concentrated liquid storage tank 2 is equipped with a high liquid level probe 2.3 and a low liquid level probe 2.2. When the high liquid level probe 2.3 is triggered, the electro-concentration module 31 will be stopped to prevent the liquid level in the concentrated liquid storage tank 2 from being too high. When the low liquid level probe 2.2 is triggered, the electro-concentration module 31 will be stopped to avoid equipment damage. The concentrated liquid storage tank 2 is equipped with a first concentrated liquid storage tank drain valve 3 and a second concentrated liquid storage tank drain valve 9. The second concentrated liquid storage tank drain valve 9 is connected to the electroplating tank 39 through a pipeline and a concentrated liquid transfer pump 38. By opening the first concentrated liquid storage tank drain valve 3, opening the second concentrated liquid storage tank drain valve 9, and starting the concentrated liquid transfer pump 38, the concentrated liquid in the concentrated liquid storage tank 2 can be transferred to the electroplating tank 39. The polar liquid storage tank 17 is equipped with a high-level polar liquid probe 17.3 and a low-level polar liquid probe 17.2. When the high-level polar liquid probe 17.3 is triggered, an alarm will be activated to remind the operator to stop adding polar liquid. When the low-level polar liquid probe 17.2 is triggered, the electro-concentration module 31 will stop running to avoid damage to the equipment. The polar liquid storage tank 17 is equipped with a second drain valve 19. Opening both the first drain valve 18 and the second drain valve 19 of the polar liquid storage tank can drain the liquid in the polar liquid storage tank 17.

[0026] The electrical control module (25) includes, but is not limited to, a PLC (not shown), a touch screen 26, an alarm light 27, a power indicator light (not shown), an emergency stop button (not shown), a mute button (not shown), a contactor (not shown), an air switch (not shown), and a relay (not shown). Liquid piping fittings (unmarked) include, but are not limited to, pipes (unmarked), valves (unmarked), elbows (unmarked), tees (unmarked), 13 dilute liquid filters, 5 concentrated liquid filters, 28 polar liquid filters, 15 dilute liquid flow regulating valves, 7 concentrated liquid flow regulating valves, and 22 polar liquid flow regulating valves.

[0027] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for concentrating, separating, purifying, and recycling a low-concentration copper pyrophosphate solution, characterized in that the method comprises the following steps: 1.1 The copper pyrophosphate solution in the washing tank is pumped into the dilute solution storage tank and the concentrated solution storage tank respectively; 1.2 Pour the potassium pyrophosphate solution into the polar liquid storage tank; 1.3 Start the desalination circulation pump, the concentrate circulation pump, and the polar liquid circulation pump to drive the solution to circulate between the membrane stack and the corresponding liquid tank, and control the pipeline pressure and maintain pressure balance by adjusting the valves on each circulation pipeline; 1.4 A constant voltage is applied to the membrane stack to electro-concentrate the solution; 1.5 Monitor the conductivity of the concentrate and dilute chambers in real time, and stop concentration when any of the following conditions are met: The conductivity of the concentrate chamber reaches 50,000-120,000 μS / cm; The conductivity of the dilute liquid chamber reaches 100-1000 μs / cm; 1.6 The diluted solution obtained in step 1.5 is returned to the water washing tank for recycling via a pump, and the concentrated solution obtained in step 1.5 is returned to the electroplating tank for recycling via a pump; 1.7 The desalinated solution obtained in step 1.6 is pumped to the reverse osmosis module for processing. The resulting concentrated solution is returned to the desalinated solution storage tank, and the resulting pure water is supplied to each process section of the production line.

2. The method according to claim 1, characterized in that, The concentration of the copper pyrophosphate solution is 1-1.5 g / L, and the conductivity is 2000-20000 μs / cm.

3. The method according to claim 1, characterized in that, The concentration of the potassium pyrophosphate solution is 35-40 g / L.

4. The method according to claim 1, characterized in that, In step 1.3, the control pipeline pressure is <0.06MPa.

5. The method according to claim 1, characterized in that, In step 1.4, the constant voltage is 12-18V.

6. The method according to claim 1, characterized in that, In step 1.7, the conductivity of the pure water is <10 μs / cm.

7. The method according to claim 1, characterized in that, In step 1.4, an electro-concentration module or an electro-concentration module plus a reverse osmosis module is used for concentration. The electroconcentration module includes a membrane stack, a dilute liquid storage tank, a concentrated liquid storage tank, an electrode liquid storage tank, a dilute liquid circulation pump, a concentrated liquid circulation pump, an electrode liquid circulation pump, a rectifier, liquid piping fittings, monitoring components, and electrical control components. The membrane stack includes a dilute liquid chamber, a concentrated liquid chamber, an electrode liquid chamber, a dilute liquid chamber inlet, a dilute liquid chamber outlet, a concentrated liquid chamber inlet, a concentrated liquid chamber outlet, an electrode liquid chamber inlet, an electrode liquid chamber outlet, a positive electrode terminal, and a negative electrode terminal. The inlet of the desalination chamber is connected to the outlet of the desalination circulation pump via a pipeline. The pipeline is equipped with a desalination filter, a desalination flow meter, a desalination flow regulating valve, a desalination pressure transmitter, and a desalination conductivity probe. The outlet of the desalination chamber is connected to the desalination storage tank via a pipeline. The drain valve of the first desalination storage tank is connected to the inlet of the desalination circulation pump via a pipeline. The inlet of the concentrate chamber is connected to the outlet of the concentrate circulation pump via a pipeline. The pipeline is equipped with a concentrate filter, a concentrate flow meter, a concentrate flow regulating valve, a concentrate pressure transmitter, and a concentrate conductivity probe. The outlet of the concentrate chamber is connected to the concentrate storage tank via a pipeline. The concentrate storage tank is connected to the inlet of the concentrate circulation pump via a pipeline. The inlet of the polar liquid chamber is connected to the outlet of the polar liquid circulation pump via a pipeline. The pipeline is equipped with a polar liquid filter, a polar liquid flow meter, a polar liquid flow regulating valve, and a polar liquid pressure transmitter. The outlet of the polar liquid chamber is connected to the polar liquid storage tank via a pipeline. An polar liquid discharge pipeline is provided on the pipeline to drain the liquid from the polar liquid storage tank. The positive terminal of the membrane stack is connected to the positive output terminal of the rectifier via a positive cable, and the negative terminal of the membrane stack is connected to the negative output terminal of the rectifier via a negative cable.

8. The method according to claim 7, characterized in that, The monitoring components include a dilute liquid conductivity probe, a concentrated liquid conductivity probe, an extreme liquid pH probe, a waste liquid high level probe, a waste liquid low level probe, a concentrated liquid high level probe, a concentrated liquid low level probe, an extreme liquid high level probe, an extreme liquid low level probe, a dilute liquid pressure transmitter, a concentrated liquid pressure transmitter, an extreme liquid pressure transmitter, a dilute liquid flow meter, a concentrated liquid flow meter, and an extreme liquid flow meter. The desalination tank is equipped with a high-level waste liquid probe and a low-level waste liquid probe. Triggering the high-level waste liquid probe will stop the second rinse water pump to prevent the desalination tank from reaching an excessively high level. Triggering the low-level waste liquid probe will stop the electro-concentration module to prevent equipment damage, and simultaneously start the second rinse water pump to replenish the desalination tank. The desalination tank is equipped with a second and a third drain valve. The second drain valve is connected to the washing tank via a pipeline and a first desalination pump to transfer the concentrated desalination from the tank to the washing tank. The third drain valve is connected to the reverse osmosis module via a pipeline and a second desalination pump to transfer the concentrated desalination from the tank to the reverse osmosis module.

9. The method according to claim 8, characterized in that, The concentrated liquid storage tank is equipped with a high-level probe and a low-level probe. Triggering the high-level probe will stop the electro-concentration module to prevent the liquid level in the storage tank from becoming too high. Triggering the low-level probe will stop the electro-concentration module to prevent equipment damage. The concentrated liquid storage tank is equipped with a first drain valve and a second drain valve. The second drain valve is connected to the electroplating tank via a pipe and a concentrated liquid transfer pump. By opening the first drain valve, opening the second drain valve, and starting the concentrated liquid transfer pump, the concentrated liquid in the storage tank can be transferred to the electroplating tank.

10. The method according to claim 8, characterized in that, The polar liquid storage tank is equipped with a high-level polar liquid probe and a low-level polar liquid probe. When the high-level polar liquid probe is triggered, an alarm will be activated to remind the operator to stop adding polar liquid. When the low-level polar liquid probe is triggered, the electro-concentration module will stop running to prevent equipment damage. The polar liquid storage tank is equipped with a second drain valve. Opening both the first and second drain valves of the polar liquid storage tank will drain the liquid in the storage tank completely.

11. The method according to claim 8, characterized in that, The electrical control components include a PLC, touch screen, alarm lights, power indicator lights, emergency stop button, silence button, contactor, air switch, and relay; Liquid piping fittings include pipes, valves, elbows, tees, dilute liquid filters, concentrate liquid filters, polar liquid filters, dilute liquid flow regulating valves, concentrate liquid flow regulating valves, and polar liquid flow regulating valves.

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