Cyclic regeneration process and regeneration system for extracting copper from sodium persulfate micro-etching waste liquid

Abstract

The invention discloses a cyclic regeneration process for extracting copper from sodium persulfate micro-etching waste liquid and a regeneration system thereof. The regeneration process comprises the following steps: collecting the micro-etching waste liquid: pumping the micro-etching waste liquid after micro-etching in a micro-etching production line into a micro-etching waste liquid collecting tank; the micro-etching waste liquid in the micro-etching waste liquid collecting tank is pumped into copper extraction electrolysis equipment for copper extraction electrolysis, copper metal is extracted, and low-copper waste liquid is obtained; the low-copper waste liquid is pumped into regenerative electrolysis equipment for regenerative electrolysis, so that the concentration of sodium persulfate is increased, and regenerative micro-etching liquid is obtained; and recycling the micro-etching liquid: adding the regenerated micro-etching liquid into a micro-etching production line for continuous use. The process provided by the invention can realize cyclic regeneration of the waste micro-etching liquid under a sulfuric acid-sodium persulfate system, achieves resource reutilization and clean production, has high etching rate, and can still maintain good operation and etching rate in a low-acid environment.

Description

Technical Field

[0001] This invention relates to the field of online electrolytic copper extraction technology using micro-etching solutions, and particularly to a copper extraction recycling process and regeneration system using sodium persulfate micro-etching waste liquid. Background Technology

[0002] In the PCB manufacturing process, micro-etching is a crucial step. It not only removes oxides from the board surface but also roughens the surface, enhancing the adhesion between the copper plating layer / film and the underlying copper substrate, thus improving surface properties. During micro-etching, the etching solution in the etching tank primarily consists of sulfuric acid and sodium persulfate, which continuously react with the copper-clad laminate. In this process, sodium persulfate is constantly converted into copper sulfate and sodium sulfate, causing the concentration of copper ions in the solution to continuously increase, while the concentration of sodium persulfate continuously decreases. When the concentrations of sodium persulfate and copper ions in the solution reach a certain level, the etching ability of the micro-etching solution significantly decreases. At this point, it is often necessary to replace the micro-etching solution to ensure continued production.

[0003] The main components of the micro-etching waste liquid discharged from the micro-etching production line are copper sulfate, sulfuric acid, sodium sulfate and a small amount of sodium persulfate. At present, the main treatment methods for micro-etching waste liquid in the market are chemical precipitation and electrolysis. The former has a lower technical threshold, but the copper-containing sludge recovered is also of lower value. Although the latter can obtain high-purity metallic copper, the waste liquid after copper extraction still needs further treatment. Summary of the Invention

[0004] The purpose of this invention is to propose a copper extraction and recycling process and system for sodium persulfate micro-etching waste liquid, in order to solve the problem that copper metal is difficult to recover from the existing sulfuric acid-sodium persulfate system micro-etching waste liquid.

[0005] To achieve this objective, the present invention adopts the following technical solution: This invention provides a copper extraction and recycling process for sodium persulfate micro-etching waste liquid, comprising the following steps: Collection of micro-etching waste liquid: The micro-etching waste liquid after micro-etching in the micro-etching production line is pumped to the micro-etching waste liquid collection tank; Electrolytic copper extraction: The micro-etching waste liquid in the micro-etching waste liquid collection tank is pumped to the copper extraction electrolysis equipment for copper extraction electrolysis to extract copper metal and obtain low copper waste liquid; Sodium persulfate regeneration electrolysis: Low-copper waste liquid is pumped to a regeneration electrolysis device for regeneration electrolysis to increase the concentration of sodium persulfate and obtain regenerated micro-etching solution; Recycled micro-etching solution: The regenerated micro-etching solution is added to the micro-etching production line for continued use.

[0006] In the copper extraction and recycling process of sodium persulfate micro-etching waste liquid, the micro-etching waste liquid includes sodium persulfate with a concentration of 60-70 g / L, sulfuric acid with an acid equivalent concentration of 0.8-1.5 mol / L, and copper ions with a concentration of 18-22 g / L.

[0007] In the copper extraction and recycling process of sodium persulfate micro-etching waste liquid, the low copper waste liquid includes sodium persulfate with a concentration of 0-10 g / L, sulfuric acid with an acid equivalent concentration of 1.3-2.0 mol / L, and copper ions with a concentration of 3-5 g / L.

[0008] In the copper extraction and recycling process of the sodium persulfate micro-etching waste liquid, the regenerated micro-etching liquid includes sodium persulfate with a concentration of 125-135 g / L, sulfuric acid with an acid equivalent concentration of 1.0-1.5 mol / L, and copper ions with a concentration of 0-3 g / L.

[0009] In the copper extraction and recycling process of sodium persulfate micro-etching waste liquid, the positive electrode of the electrolytic cell of the copper extraction electrolytic equipment is an inert electrode, and the negative electrode of the electrolytic cell of the copper extraction electrolytic equipment is a titanium metal plate.

[0010] In the copper extraction and recycling process of sodium persulfate micro-etching waste liquid, the positive electrode of the electrolytic cell of the regeneration electrolysis equipment is one of a platinum metal plate, a titanium metal plate with lead dioxide plated on the surface, or a boron-doped diamond electrode, and the negative electrode of the electrolytic cell of the regeneration electrolysis equipment is a titanium metal plate.

[0011] The present invention also provides a copper extraction and recycling system for sodium persulfate micro-etching waste liquid, which is used to realize the above-mentioned copper extraction and recycling process of sodium persulfate micro-etching waste liquid, including a micro-etching waste liquid collection tank, a copper extraction electrolysis equipment, a low copper waste liquid tank, a regeneration electrolysis equipment, and a regenerated micro-etching liquid storage and reuse device. The micro-etching waste liquid collection tank is connected to the outlet of the micro-etching production line, and the regenerated micro-etching liquid storage and reuse device is connected to the replenishment port of the micro-etching production line. The micro-etching waste liquid collection tank, copper extraction electrolysis equipment, low copper waste liquid tank, regenerated electrolysis equipment and regenerated micro-etching liquid storage and reuse device are connected in sequence through pipelines, and each pipeline is equipped with a delivery pump.

[0012] The sodium persulfate micro-etching waste liquid copper extraction recycling system also includes a micro-etching waste liquid transfer tank and a filter; the micro-etching waste liquid transfer tank is a pipeline between the micro-etching waste liquid collection tank and the outlet of the micro-etching production line, used to store the transferred micro-etching waste liquid; the filter is a pipeline between the micro-etching waste liquid collection tank and the copper extraction electrolysis equipment.

[0013] In the copper extraction and recycling system of sodium persulfate micro-etching waste liquid, the regenerated micro-etching liquid storage and reuse device includes a regenerated micro-etching liquid storage tank and a regenerated micro-etching liquid transfer cylinder connected by pipelines; the regenerated micro-etching liquid storage tank is connected to the outlet of the regeneration electrolysis equipment, and the regenerated micro-etching liquid transfer cylinder is connected to the replenishment port of the micro-etching production line.

[0014] One of the technical solutions in this invention can have the following beneficial effects: The process of this invention can realize the recycling and regeneration of micro-etching solution waste liquid under the sulfuric acid-sodium persulfate system, achieve resource reuse, realize clean production, have a high etching rate, and can still maintain good operation and etching rate in a low acid environment. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the connection relationship in one embodiment of the present invention.

[0016] In the attached diagram: 1. Micro-etching waste liquid collection tank; 2. Copper extraction electrolysis equipment; 3. Low copper waste liquid tank; 4. Regeneration electrolysis equipment; 5. Regeneration micro-etching liquid storage and reuse device; 6. Micro-etching production line; 7. Infusion pump; 8. Micro-etching waste liquid transfer tank; 9. Filter; 41. Electrolysis tank; 42. Positive electrode circulation tank; 43. Negative electrode circulation tank; 51. Regeneration micro-etching liquid storage tank; 52. Regeneration micro-etching liquid transfer tank. Detailed Implementation

[0017] The technical solution of the present invention will be further illustrated below through specific embodiments. To facilitate understanding of the present invention, a more comprehensive description is provided below. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of the present invention.

[0018] Where specific techniques or conditions are not specified in the examples, they shall be performed in accordance with the techniques or conditions described in the literature in this field or in accordance with the product instructions. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0019] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0020] This invention provides a copper extraction and recycling process for sodium persulfate micro-etching waste liquid, comprising the following steps: Collection of micro-etching waste liquid: The micro-etching waste liquid after micro-etching in the micro-etching production line is pumped to the micro-etching waste liquid collection tank; Electrolytic copper extraction: The micro-etching waste liquid in the micro-etching waste liquid collection tank is pumped to the copper extraction electrolysis equipment for copper extraction electrolysis to extract copper metal and obtain low copper waste liquid; Sodium persulfate regeneration electrolysis: Low-copper waste liquid is pumped to a regeneration electrolysis device for regeneration electrolysis to increase the concentration of sodium persulfate and obtain regenerated micro-etching solution; Recovery of micro-etching solution: Adding the micro-etching solution to the sodium persulfate micro-etching production line or storing the micro-etching solution.

[0021] In existing technologies, caustic soda is typically added directly to the micro-etching waste liquid for neutralization to obtain copper hydroxide precipitate. However, this neutralizes the acidic substances in the waste liquid, resulting in a large amount of saline wastewater. This invention, however, first extracts high-purity metallic copper directly from the micro-etching waste liquid through an electrolytic copper extraction step. Then, through a regeneration electrolysis step, the sodium persulfate in the low-concentration waste liquid after copper extraction is effectively regenerated and its concentration increased. The resulting regenerated micro-etching liquid can be directly returned to the production line for use, achieving closed-loop resource utilization and significantly reducing the raw material consumption cost of the micro-etching process.

[0022] The process of this invention can realize the recycling and regeneration of micro-etching solution waste liquid under the sulfuric acid-sodium persulfate system, achieve resource reuse, realize clean production, have a high etching rate, and can still maintain good operation and etching rate in a low acid environment.

[0023] Specifically, the micro-etching waste liquid includes sodium persulfate with a concentration of 60-70 g / L, sulfuric acid with an acid equivalent concentration of 0.8-1.5 mol / L, and copper ions with a concentration of 18-22 g / L.

[0024] In a specific embodiment, the micro-etching waste liquid discharged from the micro-etching production line includes 60-70 g / L of sodium persulfate, sulfuric acid with an acid equivalent concentration of 0.8-1.5 mol / L, and copper ions with a concentration of 18-22 g / L.

[0025] Specifically, the low-copper waste liquid includes sodium persulfate with a concentration of 0-10 g / L, sulfuric acid with an acid equivalent concentration of 1.3-2.0 mol / L, and copper ions with a concentration of 3-5 g / L.

[0026] The micro-etching waste liquid is pumped to a copper extraction electrolysis device for electrolytic copper extraction. The device contains alternating positive and negative electrode plates, and the following reactions occur during the electrolysis process: Negative electrode: Cu 2+ +2e - →Cu Positive electrode: 2H₂O - 4e →O2↑+4H + ; After electrolytic copper extraction, copper ions are reduced to metallic copper, which is then deposited, reducing the copper ion content. The electrolysis process directly consumes persulfate ions and generates hydrogen ions, thus increasing the acid equivalent concentration and decreasing the sodium persulfate concentration.

[0027] During the electrolytic copper extraction process, the electrolyte in the electrolysis can be tested. When the low-copper waste liquid reaches the above parameters, it can be pumped to the regeneration electrolysis equipment for regeneration electrolysis.

[0028] Specifically, the regenerated micro-etching solution includes sodium persulfate with a concentration of 125-135 g / L, sulfuric acid with an acid equivalent concentration of 1.0-1.5 mol / L, and copper ions with a concentration of 0-3 g / L.

[0029] The low-copper waste liquid is pumped to a regeneration electrolysis device for sodium persulfate regeneration. The regeneration electrolysis device 4 includes an electrolysis cylinder 41, a positive electrode circulation cylinder 42, and a negative electrode circulation cylinder 43. Several ion-exchange membrane positive electrode frames are installed inside the electrolysis cylinder. Each ion-exchange membrane positive electrode frame is the positive electrode region, and its two sides are the negative electrode regions. Alternating positive and negative electrode plates are placed in the positive and negative electrode regions. The positive and negative electrode regions are connected to the solutions in the positive electrode circulation cylinder 42 and the negative electrode circulation cylinder 43 via a pump. The following reactions occur during the electrolysis process: Negative electrode: 2H + +2e - →H2↑ Positive electrode: 2SO4 2- -2e - →S2O82 - ; During the sodium persulfate regeneration electrolysis process, the electrolyte in the electrolysis tank can be tested. When the regenerated micro-etching solution reaches the above parameters, it can be added to the sodium persulfate micro-etching production line or transported to a storage tank for storage.

[0030] Specifically, the positive electrode of the electrolytic cell in the copper extraction electrolysis equipment is an inert electrode, and the negative electrode of the electrolytic cell in the copper extraction electrolysis equipment is a titanium metal plate.

[0031] The positive electrode is an inert electrode, which can effectively resist the strong oxidative corrosion of persulfate and nascent oxygen.

[0032] The negative electrode is a titanium metal plate, and the deposited copper foil is easy to peel off completely, resulting in a smooth copper metal surface.

[0033] Specifically, the positive electrode of the electrolytic cell of the regenerative electrolysis equipment is one of a platinum metal plate, a titanium metal plate with lead dioxide plated on the surface, or a boron-doped diamond electrode, and the negative electrode of the electrolytic cell of the regenerative electrolysis equipment is a titanium metal plate.

[0034] Using the above material as the positive electrode, for S2O8 2-The formation of 2SO4 exhibits high catalytic selectivity and can significantly increase the overpotential of oxygen evolution reaction (OER). However, due to the large overpotential of oxygen on Pt or PbO2, oxygen formation is inhibited. Under applied voltage, 2SO4... 2- -2e - →S2O8 2- The reaction is more likely to occur.

[0035] Please refer to Figure 1 The present invention also provides a copper extraction and recycling system for sodium persulfate micro-etching waste liquid, which is used to realize the above-mentioned copper extraction and recycling process of sodium persulfate micro-etching waste liquid, including micro-etching waste liquid collection tank 1, copper extraction electrolysis equipment 2, low copper waste liquid tank 3, regeneration electrolysis equipment 4, and regenerated micro-etching liquid storage and reuse device 5. The micro-etching waste liquid collection tank 1 is connected to the outlet of the micro-etching production line 6, and the regenerated micro-etching liquid storage and reuse device 5 is connected to the replenishment port of the micro-etching production line 6. The micro-etching waste liquid collection tank 1, the copper extraction electrolysis equipment 2, the low copper waste liquid tank 3, the regenerated electrolysis equipment 4, and the regenerated micro-etching liquid storage and reuse device 5 are connected in sequence through pipelines, and each pipeline is equipped with a delivery pump 7.

[0036] The copper extraction electrolysis equipment 2 can refer to an existing electrolytic cell and is equipped with multiple electrolysis units; each electrolysis unit includes: a power source, a positive electrode, and a negative electrode; the positive electrode of the power source is connected to the positive electrode through a wire, and the negative electrode of the power source is connected to the negative electrode through a wire.

[0037] Specifically, it also includes a micro-etching waste liquid transfer tank 8 and a filter 9; the micro-etching waste liquid transfer tank 8 is a pipeline between the micro-etching waste liquid collection tank 1 and the outlet of the micro-etching production line 6, and is used to store and transfer micro-etching waste liquid; the filter 9 is a pipeline between the micro-etching waste liquid collection tank 1 and the copper extraction electrolysis equipment 2.

[0038] The micro-etching waste liquid transfer tank 8 temporarily stores the micro-etching waste liquid, mixes the waste liquid at different time points, makes the composition and temperature of the micro-etching waste liquid more uniform and stable, ensures the recovery efficiency and quality, and avoids the overflow of excess micro-etching waste liquid.

[0039] The filter 9 can filter impurities in the micro-etching waste liquid, preventing them from entering the copper extraction electrolysis equipment 2, avoiding impurities from adhering to the cathode plate, which would cause the deposited copper to be rough, loose, and less pure, thus improving the quality and value of the recovered copper metal.

[0040] Specifically, the regenerated micro-etching solution storage and reuse device 5 includes a regenerated micro-etching solution storage tank 51 and a regenerated micro-etching solution transfer cylinder 52 connected by pipelines; the regenerated micro-etching solution storage tank 51 is connected to the outlet of the regenerated electrolysis equipment 4, and the regenerated micro-etching solution transfer cylinder 52 is connected to the replenishment port of the micro-etching production line 6.

[0041] The regenerated micro-etching solution storage tank 51 can hold the regenerated micro-etching solution produced by the regeneration electrolysis equipment 4 within one cycle, ensuring that the regeneration process is not affected by the usage of downstream production lines. When the regeneration electrolysis equipment 4 is shut down due to planned maintenance or sudden failure, the regenerated micro-etching solution stored in the storage tank 51 can provide a supply for the micro-etching production line 6 for a period of time, avoiding production disruptions due to supply interruptions from the recycling system. Furthermore, the regenerated micro-etching solution in the storage tank 51 can be subjected to compositional analysis. If there are minor deviations, final adjustments can be made in the tank, providing a buffer and ensuring the stability of the quality of the regenerated micro-etching solution.

[0042] The liquid level and concentration of the micro-etching tank on the micro-etching production line 6 are consumed in real time. A transfer cylinder 52 for regenerated micro-etching liquid is set up. It can automatically, instantly, and with a small flow rate, replenish the liquid through the liquid level gauge or concentration gauge signal, so as to achieve accurate and fast online replenishment and maintain the extreme stability of the process parameters of the production tank.

[0043] The technical principles of the present invention have been described above with reference to specific embodiments. These descriptions are merely for explaining the principles of the invention and should not be construed as limiting the scope of protection of the invention in any way. Based on this explanation, those skilled in the art can readily conceive of other specific embodiments of the invention without inventive effort, and these equivalent variations or substitutions are all included within the scope defined by the claims of this application.

Claims

1. A copper extraction and recycling process for sodium persulfate micro-etching waste liquid, characterized in that, Includes the following steps: Collection of micro-etching waste liquid: The micro-etching waste liquid after micro-etching in the micro-etching production line is pumped to the micro-etching waste liquid collection tank; Electrolytic copper extraction: The micro-etching waste liquid in the micro-etching waste liquid collection tank is pumped to the copper extraction electrolysis equipment for copper extraction electrolysis to extract copper metal and obtain low copper waste liquid; Sodium persulfate regeneration electrolysis: Low-copper waste liquid is pumped to a regeneration electrolysis device for regeneration electrolysis to increase the concentration of sodium persulfate and obtain regenerated micro-etching solution; Recycled micro-etching solution: The regenerated micro-etching solution is added to the micro-etching production line for continued use.

2. The copper extraction and recycling process from sodium persulfate micro-etching waste liquid according to claim 1, characterized in that, The micro-etching waste liquid includes sodium persulfate with a concentration of 60-70 g / L, sulfuric acid with an acid equivalent concentration of 0.8-1.5 mol / L, and copper ions with a concentration of 18-22 g / L.

3. The copper extraction and recycling process from sodium persulfate micro-etching waste liquid according to claim 1, characterized in that, The low-copper waste liquid includes sodium persulfate with a concentration of 0-10 g / L, sulfuric acid with an acid equivalent concentration of 1.3-2.0 mol / L, and copper ions with a concentration of 3-5 g / L.

4. The copper extraction and recycling process from sodium persulfate micro-etching waste liquid according to claim 1, characterized in that, The regenerated micro-etching solution comprises sodium persulfate at a concentration of 125–135 g / L, sulfuric acid at an acid equivalent concentration of 1.0–1.5 mol / L, and copper ions at a concentration of 0–3 g / L.

5. The copper extraction and recycling process from sodium persulfate micro-etching waste liquid according to claim 1, characterized in that, The positive electrode of the electrolytic cell in the copper extraction electrolysis equipment is an inert electrode, and the negative electrode of the electrolytic cell in the copper extraction electrolysis equipment is a titanium metal plate.

6. The copper extraction and recycling process from sodium persulfate micro-etching waste liquid according to claim 1, characterized in that, The positive electrode of the electrolytic cell of the regenerative electrolysis equipment is one of a platinum metal plate, a titanium metal plate with lead dioxide plated on the surface, or a boron-doped diamond electrode, and the negative electrode of the electrolytic cell of the regenerative electrolysis equipment is a titanium metal plate.

7. A copper extraction and recycling system for sodium persulfate micro-etching waste liquid, characterized in that, The process for copper extraction and recycling of sodium persulfate micro-etching waste liquid according to any one of claims 1 to 6 includes a micro-etching waste liquid collection tank, a copper extraction electrolysis device, a low copper waste liquid tank, a regeneration electrolysis device, and a regenerated micro-etching liquid storage and reuse device. The micro-etching waste liquid collection tank is connected to the outlet of the micro-etching production line, and the regenerated micro-etching liquid storage and reuse device is connected to the replenishment port of the micro-etching production line. The micro-etching waste liquid collection tank, copper extraction electrolysis equipment, low copper waste liquid tank, regenerated electrolysis equipment and regenerated micro-etching liquid storage and reuse device are connected in sequence through pipelines, and each pipeline is equipped with a delivery pump.

8. The copper extraction and recycling system for sodium persulfate micro-etching waste liquid according to claim 7, characterized in that, It also includes a transfer tank for micro-etching waste liquid and a filter; the transfer tank for micro-etching waste liquid is a pipeline between the micro-etching waste liquid collection tank and the outlet of the micro-etching production line, used to store and transfer micro-etching waste liquid; the filter is a pipeline between the micro-etching waste liquid collection tank and the copper extraction electrolysis equipment.

9. A copper extraction and recycling system for sodium persulfate micro-etching waste liquid according to claim 7, characterized in that, The regenerated micro-etching solution storage and reuse device includes a regenerated micro-etching solution storage tank and a regenerated micro-etching solution transfer cylinder connected by pipelines; the regenerated micro-etching solution storage tank is connected to the outlet of the regeneration electrolysis equipment, and the regenerated micro-etching solution transfer cylinder is connected to the replenishment port of the micro-etching production line.

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