Method for regenerating acid etching solution by electrolysis without chlorine

Abstract

The present application relates to a kind of methods for regenerating acid etching solution by electrolysis without chlorine, the method comprises the following steps: acid etching solution carries out etching operation, and etching waste solution is obtained;The etching waste solution obtained respectively enters the anode chamber and cathode chamber of electrolytic cell and carries out electrolysis treatment, the anode liquid obtained in the anode chamber is overflowed to transfer tank, then is used in etching operation;The copper and cathode liquid obtained in the cathode chamber, the cathode liquid obtained is into circulating tank, then is used in the electrolysis treatment of cathode chamber;The circulation flow of the acid etching solution is ≥32m 3 / h;The ORP value of the anode liquid is 600-700mV.The present application uses ion membrane electrolysis method, strictly controls the ORP of electrolytic cell anode chamber and the circulation flow of etching tank and anode chamber, inhibits the generation of chlorine, and etching line does not need to add oxidizing agent after reuse, also reduces incremental waste water.

Description

Technical Field

[0001] This invention relates to the field of etching solution treatment technology, and more specifically to a method for chlorine-free electrolytic regeneration of acidic etching solutions. Background Technology

[0002] Currently, printed circuit board (PCB) production typically employs acidic chloride etching and alkaline chloride etching processes. The acidic chloride etching process uses an etching solution primarily composed of copper chloride, hydrochloric acid, ammonium chloride, and sodium chloride. This solution is used to etch the outer layers of the PCB surface. When the copper ion concentration is too high, the etching capacity decreases, resulting in etching waste liquid. The copper content in this waste etching liquid can reach 50-140 g / L, classifying it as hazardous waste and requiring recycling and treatment through technical means.

[0003] Currently, there are several methods for recycling acidic chloride etching wastewater, including displacement, ion-exchange membrane electrolysis, sulfuric acid distillation, and diaphragm electrolysis. Displacement methods require the discharge of large amounts of wastewater after the replacement process, polluting the environment and hindering resource recovery. Sulfuric acid distillation requires the addition of large amounts of sulfuric acid to replace copper chloride with copper sulfate, resulting in a low replacement rate, complex production process, and high risk. Traditional acidic diaphragm electrolysis not only produces toxic chlorine gas but also has a low chlorine recovery rate, consumes large amounts of chemical materials, and generates a significant amount of incremental wastewater. Therefore, ion-exchange membrane electrolysis can achieve effective recycling of acidic chloride etching wastewater through strict control of process conditions.

[0004] CN 111748826A discloses a single-film dual-chamber electrolytic copper electrolysis and chlorine regeneration system and process for acidic chloride etching waste liquid. The system includes an online acidic etching machine, a single-film dual-chamber electrolysis device, a regeneration solution preparation device, a regeneration solution ejector absorption device, a chlorine recycling and regeneration device, a low-temperature water curtain absorption device, a dynamic wave absorption device, and a cyclone spray device. It employs a process of electrolyzing copper using the single-film dual-chamber electrolysis device and regenerating chlorine using the chlorine recycling and regeneration device for the acidic etching waste liquid generated by the acidic etching machine. However, this invention still generates chlorine, requiring cumbersome treatment before reuse, resulting in high production costs.

[0005] CN 201834972U discloses a copper-ion-containing acidic etching solution regeneration system. This system includes an etching tank, an etching waste transfer tank, an ion-exchange membrane electrolytic cell, and a regeneration etching solution tank. The ion-exchange membrane electrolytic cell is divided into an anode chamber and a cathode chamber via an ion exchange membrane. The etching waste transfer tank connects the etching tank and the anode chamber, storing the etching waste solution from the etching tank and supplying it to the anode chamber. The regeneration etching solution tank connects the anode chamber and the etching tank, storing the regeneration etching solution from the anode chamber and supplying it to the etching tank. This regeneration system utilizes chloride ion electrolysis to generate chlorine gas, a strong oxidant, to oxidize the cuprous ions in the etching waste solution. However, the chloride ion content in the resulting etching solution continuously increases, adversely affecting the reuse of the etching solution.

[0006] CN 106637216A discloses a copper recovery device for regenerating and recycling acidic etching solution. The membrane electrolyzer is connected to the anode and cathode circulation tank, which is connected to an etching solution parameter control device. The etching solution parameter control device is connected to the etching production line, the etching production line is connected to an etching waste liquid collection tank, the etching waste liquid collection tank is connected to an etching waste liquid storage tank, and the etching waste liquid storage tank is connected to the membrane electrolyzer. However, this invention still requires the addition of an oxidant to the etching line after recycling, and also increases the amount of wastewater generated.

[0007] In view of the shortcomings of existing technologies, there is an urgent need to provide a method that reduces chlorine evolution in the anode zone, does not require the addition of oxidants, and has a high regeneration and reuse rate of acidic etching solutions. Summary of the Invention

[0008] The purpose of this invention is to provide a chlorine-free electrolytic regeneration method for acidic etching solution. The method employs ion-exchange membrane electrolysis, strictly controls the ORP in the anode chamber of the electrolytic cell, and simultaneously controls the circulation flow rate of the etching cell and the anode chamber of the electrolytic cell to suppress the generation of chlorine. After reuse, the etching line does not need to add oxidant, reducing the use of chemical materials such as hydrochloric acid oxidant in the production line, and also reducing incremental wastewater.

[0009] To achieve this objective, the present invention adopts the following technical solution:

[0010] This invention provides a method for regenerating acidic etching solution using chlorine-free electrolysis, the method comprising the following steps:

[0011] An acidic etching solution is used for etching operations to obtain etching waste liquid. The obtained etching waste liquid is then fed into the anode chamber and cathode chamber of an electrolytic cell for electrolytic treatment. The anolyte obtained from the anode chamber overflows into a transfer tank and is then reused in the etching operation. Copper and catholyte are obtained from the cathode chamber. The obtained catholyte enters a circulation tank and is then reused in the electrolytic treatment of the cathode chamber.

[0012] The circulation flow rate of the acidic etching solution is ≥32m³. 3 / h; the ORP value of the anolyte is 600-700mV.

[0013] The method provided by this invention is based on the situation in actual production where electrolysis equipment and etching machines operate synchronously, and the processing capacity of the electrolysis equipment must be highly matched with the capacity of the etching machine, the adjustment of the current, and the changes in the board production of the etching line. It employs ion-exchange membrane electrolysis to electrolyze acidic etching solutions, and monitors Cu by strictly controlling the ORP value of the anolyte in the anode chamber of the electrolytic cell. + The concentration is controlled to ensure a high ORP value and extremely low chlorine production in the anolyte. Combined with further tail gas absorption treatment, the entire process can achieve a chlorine-free effect. Simultaneously, controlling the minimum circulation flow rates of the electrolytic cell and etching machine ensures high-speed circulation, thereby minimizing the Cu content in the etching solution. + The anolyte is quickly fed into the electrolytic cell, and the high ORP value anolyte from the electrolytic cell is promptly recycled to the etching production line, effectively reducing the precipitation of chlorine gas.

[0014] The circulation flow rate of the acidic etching solution is ≥32m³. 3 / h, for example, could be 32m 3 / h、34m 3 / h、36m 3 / h, 38m 3 / h or 40m 3 / h, but not limited to the listed values, other unlisted values ​​within the range also apply.

[0015] During the etching process, Cu is continuously generated. + However, the lower limit of the ORP of the etching solution is usually 480-530mV. Below this value, sodium chlorate, an oxidant, will be automatically added. That is, the Cu allowed in the etching solution... + The concentration of chlorine is extremely low. Therefore, only by maintaining rapid circulation between the etching machine and the electrolytic cell can we minimize chlorine evolution at the anode of the electrolytic cell and ensure high efficiency of electrolytic regeneration and reuse.

[0016] Based on the Faraday constant, the amount of Cu that can be oxidized at the anode per KAh of charge can be calculated. + The weight is:

[0017]

[0018] Therefore, the hourly circulation rate corresponding to every 1000A of current is not less than:

[0019]

[0020] Based on an electrolytic cell capable of recovering 10 tons of electrolytic copper per month, the maximum current output of the electrolytic cell can reach 20kA, and the total circulation volume should be 32m³. 3The actual circulation rate required in actual production is close to the theoretical calculation value, which is above a certain level. Where equipment allows, the higher the circulation flow rate of the electrolytic cell and etching machine, the better.

[0021] The ORP value of the anolyte is 600-700mV, for example, it can be 600mV, 620mV, 650mV, 680mV or 700mV, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0022] In the anode chamber of the electrolytic cell, Cu in the etching solution + Far superior to Cl - An electrochemical reaction occurs, but due to concentration polarization, when Cu... + At extremely low concentrations, a chlorine evolution side reaction may occur at the anode. The Cl2 produced in this side reaction can react with Cu. + Further reactions, all chemical reactions at the anode are as follows:

[0023] Main reaction: Cu + -e=Cu 2+

[0024] Side reaction: 2Cl - -2e = Cl2; 2Cu + +Cl2=2Cu 2+ +2Cl -

[0025] Therefore, during the electrolysis process, as long as a certain amount of Cu remains in the anolyte... + This allows for extremely low chlorine production at the anode of the electrolytic cell, which can then be absorbed and treated by a tail gas treatment device, achieving a chlorine-free system. The ORP value is relevant to Cu... + The concentration is very sensitive, so the chlorine production at the anode can be kept extremely low by continuously monitoring and adjusting the ORP value of the anolyte in the electrolyzer.

[0026] Preferably, the ORP value of the anolyte is ≤620mV, and the current is adjusted to 300-600A / m. 2 .

[0027] The ORP value of the anolyte is ≤620mV, for example, it can be 620mV, 615mV, 610mV, 605mV or 600mV, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0028] The current is adjusted to 300-600A / m. 2 For example, it could be 300A / m 2 350A / m 2 400A / m 2500A / m 2 Or 600A / m 2 However, this does not limit the listed values; other unlisted values ​​within the range are also applicable.

[0029] Alternatively, if the ORP value of the anolyte is >620mV and <700mV, adjust the current to 100-300A / m. 2 .

[0030] The anolyte has an ORP value greater than 620mV and less than 700mV. For example, it can be 630mV, 650mV, 660mV, 680mV or 690mV, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0031] The current is adjusted to 100-300A / m. 2 For example, it could be 100A / m 2 150A / m 2 200A / m 2 250A / m 2 or 300A / m 2 However, this does not limit the listed values; other unlisted values ​​within the range are also applicable.

[0032] Alternatively, if the ORP value of the anolyte is ≥700mV, adjust the current to ≤100A / m. 2 .

[0033] The anolyte has an ORP value ≥ 700mV, for example, it can be 700mV, 705mV, 710mV, 715mV or 720mV, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0034] The adjusted current is ≤100A / m 2 For example, it could be 100A / m 2 80A / m 2 60A / m 2 40A / m 2 Or 20A / m 2 However, this does not limit the listed values; other unlisted values ​​within the range are also applicable.

[0035] When the electrolytic cell and etching machine are running synchronously, Cu is continuously generated in the etching solution of the etching machine. + Cu + It enters the anode chamber of the electrolytic cell and is oxidized to Cu. 2+ However, in actual production, due to variations in PCB board copper layer thickness, circuit design, and board placement speed, the amount of copper etched per unit time is not fixed, meaning the etching solution Cu...+ The concentration is constantly changing; therefore, the operating current of the electrolysis equipment needs to be adjusted according to the Cu concentration. + The concentration is adjusted accordingly to ensure a high ORP value and extremely low chlorine production in the anolyte. Since the ORP value directly and accurately reflects the Cu content... + Therefore, automatically adjusting the current using the ORP value through a PLC system is a reliable control method. A reasonable anolyte ORP value can be set based on the lower limit of the etching line's ORP. When the anolyte ORP value is not higher than 620mV, the rectifier automatically adjusts to a high current; when the anolyte ORP value is higher than 620mV but lower than 700mV, the rectifier automatically adjusts to a medium current; and when the ORP value is not lower than 700mV, the rectifier automatically adjusts to a low current. This ensures that the anolyte ORP value is always maintained within a certain range. At this point, the chlorine production of the anolyte is extremely low, and no additional oxidant needs to be added to the etching line after reuse.

[0036] Preferably, the acidic etching solution has a copper ion concentration of 120-150 g / L, a chloride ion concentration of 270-300 g / L, an acidity of 1.5-3 mol / L, and a specific gravity of 1.28-1.31.

[0037] The concentration of copper ions in the acidic etching solution is 120-150 g / L, for example, it can be 120 g / L, 125 g / L, 130 g / L, 140 g / L or 150 g / L, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0038] The chloride ion concentration in the acidic etching solution is 270-300 g / L, for example, it can be 270 g / L, 275 g / L, 280 g / L, 290 g / L or 300 g / L, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0039] The acidity of the acidic etching solution is 1.5-3 mol / L, for example, it can be 1.5 mol / L, 2 mol / L, 2.5 mol / L or 3 mol / L, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0040] The specific gravity of the acidic etching solution is 1.28-1.31, for example, it can be 1.28, 1.29, 1.3 or 1.31, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0041] Preferably, the ORP value of the acidic etching solution is 480-530mV, for example, it can be 480mV, 490mV, 500mV, 510mV or 530mV, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0042] Preferably, the etching temperature is 48-52°C, for example, 48°C, 49°C, 50°C, 51°C or 52°C, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0043] Preferably, the temperature at which the anode chamber is subjected to electrolytic treatment is 48-52°C, for example, 48°C, 49°C, 50°C, 51°C or 52°C, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0044] Preferably, the temperature at which the cathode chamber is subjected to electrolytic treatment is 38-45°C, for example, 38°C, 40°C, 42°C, 44°C or 45°C, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0045] Preferably, the anolyte has a copper ion concentration of 120-150 g / L, a chloride ion concentration of 270-300 g / L, an acidity of 1.5-3 mol / L, and a specific gravity of 1.28-1.31.

[0046] The concentration of copper ions in the anolyte is 120-150 g / L, for example, it can be 120 g / L, 125 g / L, 130 g / L, 140 g / L or 150 g / L, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0047] The chloride ion concentration in the anolyte is 270-300 g / L, for example, it can be 270 g / L, 275 g / L, 280 g / L, 290 g / L or 300 g / L, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0048] The acidity of the anolyte is 1.5-3 mol / L, for example, it can be 1.5 mol / L, 2 mol / L, 2.5 mol / L or 3 mol / L, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0049] The specific gravity of the anolyte is 1.28-1.31, for example, it can be 1.28, 1.29, 1.3 or 1.31, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0050] Preferably, the concentration of copper ions in the catholyte is 30-40 g / L, the concentration of chloride ions is 200-250 g / L, and the acidity is 3.5-4.2 mol / L.

[0051] The concentration of copper ions in the catholyte is 30-40 g / L, for example, it can be 30 g / L, 32 g / L, 35 g / L, 38 g / L or 40 g / L, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0052] The chloride ion concentration in the catholyte is 200-250 g / L, for example, it can be 200 g / L, 210 g / L, 220 g / L, 230 g / L or 250 g / L, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0053] The acidity of the catholy solution is 3.5-4.2 mol / L, for example, it can be 3.5 mol / L, 3.6 mol / L, 3.8 mol / L, 4 mol / L or 4.2 mol / L, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0054] Preferably, the copper ion concentration in the catholyte is less than 30 g / L, and the etching waste liquid is added to the target copper ion concentration.

[0055] The concentration of copper ions in the catholyte is less than 30 g / L, for example, it can be 29 g / L, 28 g / L, 26 g / L, 25 g / L or 23 g / L, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0056] Preferably, the addition method includes pumping the etching waste liquid for 10-20 seconds every 300-600 seconds.

[0057] The interval for pumping the etching waste liquid is 300-600s, for example, it can be 300s, 350s, 400s, 500s or 600s, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0058] The pumping time for the etching waste liquid is 10-20 seconds, for example, it can be 10 seconds, 12 seconds, 15 seconds, 18 seconds or 20 seconds, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0059] The concentration of copper ions in the catholyte is controlled at 30-40 g / L. During the electrolysis process, copper ions are continuously electrodeposited as elemental copper at the cathode. When the concentration of copper ions in the catholyte is lower than 30 g / L, acidic etching solution is added to the circulation tank to replenish the copper ions. At this time, an equal amount of catholyte overflows. The overflowing catholyte with low copper concentration is recycled to the etching machine after anodic oxidation, so that the specific gravity of the etching solution remains stable.

[0060] Preferably, the method is carried out using a chlorine-free electrolytic regeneration system for acidic etching solution, the system comprising an etching machine, an electrolytic cell, a transfer tank, and a circulation tank; the electrolytic cell is separated into an anode chamber and a cathode chamber by an ion-exchange membrane; the etching machine, the anode chamber, and the transfer tank are connected sequentially along the material flow direction, and the anolyte discharged from the transfer tank is returned to the etching machine; the etching machine is connected to the circulation tank, the circulation tank is connected to the cathode chamber via a cathode liquid reuse pump, and the cathode chamber is connected to the circulation tank via a cathode circulation pump; the circulation tank is connected to the anode chamber.

[0061] Preferably, the anode in the anode chamber is a titanium plate coated with a ruthenium-iridium noble metal coating, and the cathode in the cathode chamber is a pure titanium plate.

[0062] Preferably, the anode chamber and the transfer tank are connected by an anode overflow pipe, the anode overflow pipe is provided with an ORP value detection sampling port, the ORP value detection sampling port is connected to a sampling pump, and the sampling pump is connected to an ORP value monitor.

[0063] The ORP value detection sampling port is located on the anode overflow pipe, which allows for real-time detection of the ORP value signal and reduces delay compared to setting it in the transfer tank.

[0064] Preferably, the length of the sampling pump is ≤1.5m, for example, it can be 1.5m, 1.4m, 1.3m, 1.2m or 1.1m, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0065] Preferably, the inner cavity of the transfer tank includes a main tank and a secondary tank. The main tank is connected to the etching machine via an anode recycling pump, and the secondary tank is connected to the etching machine via an anode recycling auxiliary pump.

[0066] Both the main tank and the auxiliary tank are equipped with transparent liquid level tubes, and the auxiliary tank is equipped with high and low liquid level probes.

[0067] Preferably, the etching machine is connected to the anode chamber via a waste liquid pump.

[0068] Preferably, the flow rates of the waste liquid pump, the anode reuse pump, and the anode reuse auxiliary pump satisfy the following:

[0069] V1>V2 and V1<V2+V3;

[0070] Where: V1 represents the flow rate of the waste liquid pump, in m 3 / h; V2 represents the flow rate of the anode reuse pump, in m³ / h 3 / h; V3 represents the flow rate of the anode reuse auxiliary pump, in m³ / h 3 / h.

[0071] The etching solution enters the electrolytic cell from the etching machine, and the anolyte overflows from the electrolytic cell to the transfer tank and then returns to the etching machine. Both are transported by pumps, making it impossible to achieve completely consistent inflow and outflow velocities in the electrolytic equipment. The above flow control method can achieve a balance between inflow and outflow and maintain uninterrupted circulation. The waste liquid pump and the anode recycling pump are continuously running, while the anode auxiliary pump starts intermittently based on the level of the auxiliary tank.

[0072] It should be noted that in the device system described in this invention, all pumps that transport liquid from low to high level are connected to a check valve at their rear end to prevent backflow; and all closed pipelines that transport liquid from high to low level are equipped with an anti-siphon device.

[0073] Preferably, when the etching machine stops, the control valve connects the main tank to the anode chamber via an anode recycling pump, and the auxiliary tank is connected to the anode chamber via an anode recycling auxiliary pump.

[0074] The anode chamber and the transfer tank adopt two circulation modes, which are automatically switched by electric valves: when the etching machine is running and making boards, the external circulation is performed: etching machine → anode chamber → transfer tank → etching machine; when the etching machine is stopped, the internal circulation is performed: anode chamber → transfer tank → anode chamber.

[0075] Preferably, the inner cavity of the circulation tank includes a main circulation tank and a liquid level adjustment tank. The main circulation tank is connected to the cathode chamber via a cathode circulation pump, and the liquid level adjustment tank is connected to the cathode chamber via a cathode liquid recycling pump.

[0076] Both the main circulation tank and the liquid level adjustment tank are equipped with transparent liquid level pipes. The main circulation tank is equipped with a cooling water coil, and the liquid level adjustment tank is equipped with a liquid level probe.

[0077] Preferably, the transfer tank is connected to the anode chamber by a tail gas treatment device.

[0078] Preferably, the etching machine is equipped with an automatic chemical dosing device.

[0079] The device system retains the original automatic dosing device of the etching machine, so that even if the electrolytic regeneration equipment fails, it will not affect the quality of the board produced by the etching machine.

[0080] Compared with the prior art, the present invention has the following beneficial effects:

[0081] The present invention provides a chlorine-free electrolytic regeneration method for acidic etching solution. Based on the actual production process where the electrolysis equipment and etching machine operate synchronously, and the processing capacity of the electrolysis equipment must be highly matched with the capacity of the etching machine, as well as the adjustment of the current and changes in the etching line's board production conditions. This method employs ion-exchange membrane electrolysis to electrolyze the acidic etching solution, and monitors the Cu content by strictly controlling the ORP value of the anolyte in the anode chamber of the electrolytic cell. +The concentration is controlled to ensure a high ORP value and extremely low chlorine production in the anolyte. Combined with tail gas treatment, this achieves a chlorine-free system. Simultaneously, controlling the minimum circulation flow rates of the electrolytic cell and etching machine ensures high-speed circulation, thereby minimizing Cu content in the etching solution. + The solution is quickly fed into the electrolytic cell, and the high ORP value anolyte from the electrolytic cell is promptly recycled to the etching line, effectively reducing chlorine precipitation. The acidic etching solution has a high regeneration and recycling rate, and the etching line does not require additional oxidant after recycling, reducing the use of hydrochloric acid, oxidant and other chemical materials in the production line, and also reducing incremental wastewater. Attached Figure Description

[0082] Figure 1 This is a schematic diagram of the device system for the chlorine-free electrolytic regeneration of acidic etching solution provided in Embodiment 1 of the present invention;

[0083] The components are: 1. Etching machine; 2. Transfer tank; 3. Circulation tank; 4. Anode chamber; 5. Cathode chamber; 6. Waste liquid pump; 7. Anode recycling pump; 8. Anode recycling auxiliary pump; 9. Tail gas treatment device; 10. Cathode circulation pump; 11. Cathode liquid recycling pump. Detailed Implementation

[0084] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0085] Example 1

[0086] This embodiment provides a method for regenerating acidic etching solution without chlorine gas electrolysis, the method comprising the following steps:

[0087] An acidic etching solution is used for etching operations to obtain etching waste liquid. The obtained etching waste liquid enters the anode chamber 4 and cathode chamber 5 of the electrolytic cell for electrolytic treatment. The anolyte obtained in the anode chamber 4 overflows into the transfer tank 2 and is then reused in the etching operation. The cathode chamber 5 yields copper and catholyte. The obtained catholyte enters the circulation tank 3 and is then reused in the electrolytic treatment of the cathode chamber 5.

[0088] The circulation flow rate of the acidic etching solution is 40 m³ / s. 3 / h; the acidic etching solution has a copper ion concentration of 130g / L, a chloride ion concentration of 280g / L, an acidity of 2mol / L, a specific gravity of 1.3, and an ORP value of 500mV; the etching operation temperature is 50℃;

[0089] The anolyte has an ORP value of 650mV, and the current is adjusted to 200A / m. 2The anolyte has a copper ion concentration of 130 g / L, a chloride ion concentration of 280 g / L, an acidity of 2 mol / L, and a specific gravity of 1.3; the electrolysis temperature in the anode chamber 4 is 50°C.

[0090] The concentration of copper ions in the catholy solution is 35 g / L, the concentration of chloride ions is 220 g / L, and the acidity is 3.8 mol / L. The temperature at which the cathode chamber 5 is subjected to electrolysis is 40°C. During the electrolysis process, when the concentration of copper ions in the catholy solution is lower than 30 g / L, etching waste liquid is pumped for 15 seconds every 500 seconds until the copper ion concentration reaches the target requirement.

[0091] The method is carried out using a device system for the regeneration of acidic etching solution via chlorine-free electrolysis, such as... Figure 1 As shown, the device system includes an etching machine 1, an electrolytic cell, a transfer tank 2, and a circulation tank 3; the electrolytic cell is separated into an anode chamber 4 and a cathode chamber 5 that are not interconnected by an ion membrane;

[0092] The etching machine 1, anode chamber 4, and transfer tank 2 are connected sequentially along the material flow direction. The anolyte discharged from the transfer tank 2 is returned to the etching machine 1. The anode chamber 4 and the transfer tank 2 are connected via an anode overflow pipe, which is equipped with an ORP value detection sampling port. The ORP value detection sampling port is connected to a 1.5m long sampling pump, which is connected to an ORP value monitor. The etching machine 1 and the anode chamber 4 are connected via a waste liquid pump 6. The inner cavity of the transfer tank 2 includes a main... The main tank is connected to the etching machine 1 via an anode recycling pump 7, and the secondary tank is connected to the etching machine 1 via an anode recycling auxiliary pump 8. When the etching machine 1 stops, a control valve connects the main tank to the anode chamber 4 via the anode recycling pump 7, and the secondary tank to the anode chamber 4 via the anode recycling auxiliary pump 8. The flow rates of the waste liquid pump 6, the anode recycling pump 7, and the anode recycling auxiliary pump 8 satisfy: V1 > V2 and V1 < V2 + V3; where V1 represents the flow rate of the waste liquid pump 6, in meters. 3 / h; V2 represents the flow rate of the anode reuse pump 7, m 3 / h; V3 represents the flow rate of the anode reuse auxiliary pump 8, in m³ / h 3 / h; The transfer tank 2 and the anode chamber 4 are connected to a tail gas treatment device 9;

[0093] The etching machine 1 is connected to the circulation tank 3. The inner cavity of the circulation tank 3 includes a main circulation tank and a liquid level adjustment tank. The main circulation tank is connected to the cathode chamber 5 through the cathode circulation pump 10. The liquid level adjustment tank is connected to the cathode chamber 5 through the cathode liquid reuse pump 11. The circulation tank 3 is connected to the anode chamber 4. The etching machine 1 is equipped with an automatic chemical dosing device.

[0094] Example 2

[0095] This embodiment provides a method for regenerating acidic etching solution without chlorine gas electrolysis, the method comprising the following steps:

[0096] An acidic etching solution is used for etching operations to obtain etching waste liquid. The obtained etching waste liquid enters the anode chamber 4 and cathode chamber 5 of the electrolytic cell for electrolytic treatment. The anolyte obtained in the anode chamber 4 overflows into the transfer tank 2 and is then reused in the etching operation. The cathode chamber 5 yields copper and catholyte. The obtained catholyte enters the circulation tank 3 and is then reused in the electrolytic treatment of the cathode chamber 5.

[0097] The circulation flow rate of the acidic etching solution is 36m³. 3 / h; the acidic etching solution has a copper ion concentration of 120g / L, a chloride ion concentration of 270g / L, an acidity of 1.5mol / L, a specific gravity of 1.28, and an ORP value of 530mV; the etching operation temperature is 48℃;

[0098] The anolyte has an ORP value of 700mV, and the current is adjusted to 60A / m. 2 The anolyte has a copper ion concentration of 120 g / L, a chloride ion concentration of 270 g / L, an acidity of 1.5 mol / L, and a specific gravity of 1.28; the electrolysis temperature in the anode chamber 4 is 48°C.

[0099] The concentration of copper ions in the catholy solution is 30 g / L, the concentration of chloride ions is 200 g / L, and the acidity is 3.5 mol / L. The temperature at which the cathode chamber 5 is subjected to electrolysis is 38°C. During the electrolysis process, when the concentration of copper ions in the catholy solution is lower than 30 g / L, etching waste liquid is pumped for 10 seconds every 300 seconds until the copper ion concentration reaches the target requirement.

[0100] The method is carried out using a device system for the electrolytic regeneration of acidic etching solution without chlorine gas, which is the same as that in Example 1.

[0101] Example 3

[0102] This embodiment provides a method for regenerating acidic etching solution without chlorine gas electrolysis, the method comprising the following steps:

[0103] An acidic etching solution is used for etching operations to obtain etching waste liquid. The obtained etching waste liquid enters the anode chamber 4 and cathode chamber 5 of the electrolytic cell for electrolytic treatment. The anolyte obtained in the anode chamber 4 overflows into the transfer tank 2 and is then reused in the etching operation. The cathode chamber 5 yields copper and catholyte. The obtained catholyte enters the circulation tank 3 and is then reused in the electrolytic treatment of the cathode chamber 5.

[0104] The circulation flow rate of the acidic etching solution is 32m³. 3 / h; the acidic etching solution has a copper ion concentration of 150g / L, a chloride ion concentration of 300g / L, an acidity of 3mol / L, a specific gravity of 1.31, and an ORP value of 480mV; the etching operation temperature is 52℃;

[0105] The anolyte has an ORP value of 600mV, and the current is adjusted to 400A / m. 2 The anolyte has a copper ion concentration of 150 g / L, a chloride ion concentration of 300 g / L, an acidity of 3 mol / L, and a specific gravity of 1.31; the electrolysis temperature in the anode chamber 4 is 52°C.

[0106] The catholy solution has a copper ion concentration of 40 g / L, a chloride ion concentration of 250 g / L, and an acidity of 4.2 mol / L. The cathode chamber 5 is electrolyzed at a temperature of 45°C. During electrolysis, when the copper ion concentration in the catholy solution is lower than 30 g / L, etching waste liquid is pumped for 20 seconds every 600 seconds until the copper ion concentration reaches the target requirement.

[0107] The method is carried out using a device system for the electrolytic regeneration of acidic etching solution without chlorine gas, which is the same as that in Example 1.

[0108] Example 4

[0109] This embodiment provides a method for regenerating acidic etching solution by chlorine-free electrolysis. The difference from Embodiment 1 is that the flow relationship between the waste liquid pump 6, the anode recycling pump 7, and the anode recycling auxiliary pump 8 in the device system is not limited, while the rest is the same as in Embodiment 1.

[0110] Example 5

[0111] This embodiment provides a method for regenerating acidic etching solution by chlorine-free electrolysis. The difference from Embodiment 1 is that the anode overflow pipe is not equipped with an ORP value detection sampling port, but is adjusted to perform ORP value detection sampling from the intermediate transfer tank 2. All other aspects are the same as in Embodiment 1.

[0112] Comparative Example 1

[0113] This comparative example provides a method for regenerating acidic etching solution using chlorine-free electrolysis. The difference from Example 1 is that the circulation flow rate of the acidic etching solution is adjusted to 30 m³ / s. 3 / h, the rest are the same as in Example 1.

[0114] Comparative Example 2

[0115] This comparative example provides a method for regenerating acidic etching solution by chlorine-free electrolysis. The difference from Example 1 is that the ORP value of the anolyte is adjusted to 580mV, while the rest is the same as in Example 1.

[0116] Comparative Example 3

[0117] This comparative example provides a method for regenerating acidic etching solution by chlorine-free electrolysis. The difference from Example 1 is that the ORP value of the anolyte is adjusted to 720mV, while the rest is the same as in Example 1.

[0118] The acidic etching solution was regenerated by chlorine-free electrolysis using the methods provided in Examples 1-5 and Comparative Examples 1-3. Chlorine was detected at the anode during the electrolysis process, and the results are shown in Table 1. The acidic etching solution regeneration and reuse rate was calculated as follows: acidic etching solution regeneration and reuse rate = monthly waste liquid volume / (monthly waste liquid volume + total amount of hydrochloric acid and oxidant) * 100%, and the results are shown in Table 1.

[0119] Table 1

[0120] Example 1 300 90 Example 2 500 85 Example 3 300 80 Example 4 600 60 Example 5 3000 50 Comparative Example 1 1000 60 Comparative Example 2 5000 70 Comparative Example 3 10000 75

[0121] As can be seen from Table 1, the method for regenerating acidic etching solution without chlorine gas provided by the present invention limits the circulation flow range of acidic etching solution and controls the ORP value of anolyte, so that very little chlorine gas is generated at the anode. At the same time, the tail gas treatment device can completely absorb the chlorine gas, thereby ensuring that no chlorine gas is generated in the device system and the acidic etching solution has a high recycling rate.

[0122] A comparison of Examples 1 and 4 shows that the flow relationship between the waste liquid pump, the anode recycling pump, and the anode recycling auxiliary pump is not limited, making it impossible to achieve a completely consistent inflow and outflow velocity in the electrolysis equipment, thus failing to maintain circulation balance. A comparison of Examples 1 and 5 shows that sampling in the transfer tank to detect the ORP value signal will cause a delay, resulting in a mismatch between the measured ORP value and the actual value, which in turn leads to an increase in the amount of chlorine gas generated and a decrease in the etching solution regeneration and reuse rate.

[0123] A comparison of Example 1 and Comparative Example 1 shows that if the circulation flow rate is too low, the Cu in the anolyte will be insufficient. + If the concentration is too low, chlorine gas will be generated in the anolyte, while Cu will be generated by the reaction of the acidic etching solution and copper in the etching machine. + Since the Cu cannot be recycled to the electrolytic anode region in time, hydrochloric acid and oxidants are added to the etching machine to react with it. + The reaction maintains the etching rate of the acidic etching solution. However, as the amounts of hydrochloric acid and oxidant increase, the recycling rate of the etching solution decreases. A comparison of Example 1 with Comparative Examples 2 and 3 shows that if the ORP value of the anolyte is too low, the electrolytic anode cannot effectively remove Cu from the acidic etching solution in a timely manner. + Oxidized to Cu 2+ Similarly, this will require additional hydrochloric acid and oxidants to maintain the etching rate along the etching lines; if the ORP value of the anolyte is too high, the anolyte region will experience Cu degradation. + Converted to Cu 2+If the rate is too fast, some of the electrical energy will also deplete Cl. - Oxidation into chlorine gas leads to a decrease in the chloride ion concentration during etching. - It is also an important factor affecting the etching rate. The etching line will also add hydrochloric acid and oxidant according to its control parameters to maintain the etching rate.

[0124] In summary, the chlorine-free electrolytic regeneration method for acidic etching solution provided by this invention is based on the actual production process where the electrolysis equipment and etching machine operate synchronously, and the processing capacity of the electrolysis equipment must be highly matched with the capacity of the etching machine, the adjustment of the current, and the changes in the board production situation of the etching line. The method employs ion-exchange membrane electrolysis to electrolyze the acidic etching solution. By strictly controlling the ORP value of the anolyte in the anode chamber of the electrolytic cell to monitor the Cu+ concentration, a high ORP value and extremely low chlorine production are ensured. Combined with tail gas treatment, the system achieves the technical effect of zero chlorine generation. Simultaneously, controlling the minimum circulation flow rate of the electrolytic cell and etching machine maintains high-speed circulation, allowing Cu+ in the etching solution to quickly enter the electrolytic cell. The high ORP value anolyte from the electrolytic cell is promptly reused in the etching production line, effectively reducing chlorine precipitation. The acidic etching solution has a high regeneration and reuse rate, and the etching line does not require additional oxidant after reuse, reducing the use of hydrochloric acid, oxidants, and other chemical materials in the production line, and also reducing incremental wastewater.

[0125] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Those skilled in the art should understand that any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the scope of protection and disclosure of the present invention.

Claims

1. A method for regenerating acidic etching solution by chlorine-free electrolysis, characterized in that, The method includes the following steps: An acidic etching solution is used for etching operations to obtain etching waste liquid. The obtained etching waste liquid is then fed into the anode chamber and cathode chamber of an electrolytic cell for electrolytic treatment. The anolyte obtained from the anode chamber overflows into a transfer tank and is then reused in the etching operation. Copper and catholyte are obtained from the cathode chamber. The obtained catholyte enters a circulation tank and is then reused in the electrolytic treatment of the cathode chamber. The circulation flow rate of the acidic etching solution between the electrolytic cell and the etching machine is ≥32m³. 3 / h; the ORP value of the anolyte is 600-700mV; The anolyte has an ORP value ≥600mV and ≤620mV, and the current is adjusted to 300-600A / m. 2 ; Alternatively, if the ORP value of the anolyte is >620mV and <700mV, adjust the current to 100-300A / m. 2 ; Alternatively, if the ORP value of the anolyte is 700mV, adjust the current to ≤100A / m. 2 ; The acidic etching solution has a copper ion concentration of 120-150 g / L, a chloride ion concentration of 270-300 g / L, an acidity of 1.5-3 mol / L, and a specific gravity of 1.28-1.31; the anolyte has a copper ion concentration of 120-150 g / L, a chloride ion concentration of 270-300 g / L, an acidity of 1.5-3 mol / L, and a specific gravity of 1.28-1.31; the catholyte has a copper ion concentration of 30-40 g / L, a chloride ion concentration of 200-250 g / L, and an acidity of 3.5-4.2 mol / L.

2. The method according to claim 1, characterized in that, The ORP value of the acidic etching solution is 480-530mV.

3. The method according to claim 1, characterized in that, The etching operation is performed at a temperature of 48-52℃.

4. The method according to claim 1, characterized in that, The temperature at which the anode chamber is subjected to electrolysis is 48-52℃.

5. The method according to claim 1, characterized in that, The temperature at which the cathode chamber is subjected to electrolysis is 38-45℃.

6. The method according to claim 1, characterized in that, The copper ion concentration in the cathode solution is less than 30 g / L, and the etching waste liquid is added to the target copper ion concentration.

7. The method according to claim 6, characterized in that, The method of addition includes pumping etching waste liquid for 10-20 seconds every 300-600 seconds.

8. The method according to claim 1, characterized in that, The method is carried out using a chlorine-free electrolytic regeneration system for acidic etching solution. The system includes an etching machine, an electrolytic cell, a transfer tank, and a circulation tank. The electrolytic cell is separated into an anode chamber and a cathode chamber by an ion-exchange membrane; the etching machine, anode chamber, and transfer tank are connected sequentially along the material flow direction; the anolyte discharged from the transfer tank is returned to the etching machine; the etching machine is connected to the circulation tank, which is connected to the cathode chamber via a cathode liquid reuse pump; the cathode chamber is connected to the circulation tank via a cathode circulation pump; and the circulation tank is connected to the anode chamber.

9. The method according to claim 8, characterized in that, The anode chamber and the transfer tank are connected by an anode overflow pipe. The anode overflow pipe is equipped with an ORP value detection sampling port. The ORP value detection sampling port is connected to a sampling pump, and the sampling pump is connected to an ORP value monitor.

10. The method according to claim 9, characterized in that, The length of the sampling pump is ≤1.5m.

11. The method according to claim 8, characterized in that, The inner cavity of the transfer tank includes a main tank and a secondary tank. The main tank is connected to the etching machine via an anode recycling pump, and the secondary tank is connected to the etching machine via an anode recycling auxiliary pump.

12. The method according to claim 11, characterized in that, The etching machine is connected to the anode chamber via a waste liquid pump.

13. The method according to claim 12, characterized in that, The flow rates of the waste liquid pump, the anode reuse pump, and the anode reuse auxiliary pump meet the following requirements: V1>V2 and V1<V2+V3; Where: V1 represents the flow rate of the waste liquid pump, in m 3 / h; V2 represents the flow rate of the anode reuse pump, in m³ / h 3 / h; V3 represents the flow rate of the anode reuse auxiliary pump, in m³ / h 3 / h.

14. The method according to claim 11, characterized in that, When the etching machine stops, the control valve connects the main tank to the anode chamber via the anode recycling pump, and the auxiliary tank is connected to the anode chamber via the anode recycling auxiliary pump.

15. The method according to claim 8, characterized in that, The inner cavity of the circulation tank includes a main circulation tank and a liquid level adjustment tank. The main circulation tank is connected to the cathode chamber through a cathode circulation pump, and the liquid level adjustment tank is connected to the cathode chamber through a cathode liquid recycling pump.

16. The method according to claim 8, characterized in that, The transfer tank is connected to the anode chamber by a tail gas treatment device.

17. The method according to claim 8, characterized in that, The etching machine is equipped with an automatic chemical dosing device.

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