CN111304657B - Method for electrolytic recycling of alkaline etching waste liquid - Google Patents

Abstract

The method for electrolyzing and recycling the alkaline etching waste liquid comprises the following steps: (1) Taking alkaline etching waste liquid or mixed liquid of alkaline etching waste liquid and reducing agent as anode electrolyte, and adding the anode electrolyte into the anode region; adding a mixed solution of alkaline etching waste liquid and a reducing agent into the cathode region as a cathode electrolyte; (2) Starting the electrolysis power supply to perform electrolysis operation, and precipitating metallic copper on the electrolysis cathode; (3) Adding one or more of ammonium chloride, ammonia, water and other components contained in the alkaline etching solution into the anode solution and/or the cathode solution after the electrolytic operation in the step (2) according to a specific alkaline etching process to prepare the regenerated alkaline etching sub-solution which can be reused on an alkaline etching production line. The method can improve the efficiency of copper electrolytic precipitation, and the waste liquid can be prepared into regenerated alkaline etching liquid capable of maintaining ideal etching effect after electrolytic reuse.

Description

A method for electrolytic reuse of alkaline etching waste liquid

technical field

The invention belongs to the technical field of post-treatment of etching waste liquid, and in particular relates to a method for electrolytic reuse of alkaline etching waste liquid.

Background technique

Etching is an important step in the existing printed circuit board (PCB) fabrication process. Etching refers to chemically removing unnecessary copper on the copper clad substrate with an etchant to form the desired circuit pattern.

At present, commonly used etching solutions for circuit board production include acidic copper chloride etching solution and alkaline copper ammonium chloride etching solution (hereinafter referred to as alkaline etching solution). The main components of the alkaline etching solution are copper salts, ammonium chloride, ammonia water, water, optional carbonates, and optional additives; among them, the carbonates are usually ammonium carbonate and ammonium bicarbonate. In the actual production process, as the etching progresses, the components in the alkaline etching solution will be continuously consumed. In order to keep the composition of the alkaline etching solution stable, it is necessary to continuously add etching replenishing liquid and/or supplementary ammonia water, which inevitably leads to the continuous increase of the alkaline etching solution in the etching tank and overflows out of the tank. The main components of the etching replenishing liquid are optional additives, which are also called etching sub-liquids in the industry. The etchant that overflows the etching tank or the etchant that has been used is generally called etching waste. The main components of the alkaline etching waste include cupric ammonium chloride, cuprous ammonium chloride, ammonium chloride, ammonia water , Some alkaline etching waste liquids also contain ammonium carbonate, ammonium bicarbonate, organic ammonium salts, organic amines, etc.

For circuit board production plants that adopt an alkaline etching process, this process will produce a large amount of alkaline etching waste liquid containing high-concentration copper ions every day. At present, in addition to selling the waste liquid to environmental protection companies for treatment, some manufacturers also use electrolysis equipment to electrolyze it in the factory to extract copper for recycling. In the prior art, methods for extracting and reusing copper from alkaline etching waste liquid mainly include extraction electrolysis combining method and direct electrolysis method. Among them, the electrochemical reaction formula of the direct electrolysis method is as follows:

Anode: H ₂ O–e ^- → 2H ⁺ +1/2O ₂

Cathode: Cu ² ++e ^- → Cu ⁺

Cu ⁺ +e ^- → Cu

And there are following several technical problems in above-mentioned existing direct electrolytic process:

First, during the electrolysis process, the solid metal copper electro-deposited on the cathode will be quickly etched back by the electrolyte to form copper ions and dissolve back into the electrolyte, reducing the recovery efficiency of electro-deposited copper, which is only about 60-70%. This is because: the existing direct electrolysis process directly uses alkaline etching waste liquid as the electrolyte, and the copper ammonium complex Cu(NH ₃ ) ₄ Cl ₂ and Cu(NH ₃ ) ₂ Cl are complexed during the electrolysis process. The structure is broken and transformed into metallic copper, ammonium chloride, and ammonia. The concentration of ammonium chloride and ammonia in the electrolyte is getting higher and higher, and at the same time, the oxygen content in the solution is gradually increasing with the generation of oxygen on the anode. The monovalent copper ammonium complex in the etching waste liquid can react with the ammonium chloride, ammonia and oxygen dissolved in the etching waste liquid to form a divalent copper ammonium complex that can react with metal copper, which is beneficial to electrolysis. The resulting metallic copper was etched back. According to the principle that the concentration of the reactant is proportional to the reaction rate, the higher the concentration of the above-mentioned reactant, the faster the formation of divalent copper ammonium complex in the electrolyte, and the more obvious the corrosion-back effect on the precipitation of metallic copper on the cathode. The regeneration of described divalent copper ammonium complex and the chemical reaction equation of back etching copper are as follows:

Regeneration reaction of divalent copper ammonium complex:

2Cu(NH ₃ ) ₂ Cl+4NH ₄ Cl+2NH ₃ +1/2O ₂ →2Cu(NH ₃ ) ₄ Cl ₂ +H ₂ O

Etchback reaction: Cu+Cu(NH ₃ ) ₄ Cl ₂ →2Cu(NH ₃ ) ₂ Cl;

Total reaction: Cu+2NH ₄ Cl+2NH ₃ +1/2O ₂ →Cu(NH ₃ ) ₄ Cl ₂ +H ₂ O.

Second, because the ammonia water itself is easy to volatilize and become ammonia gas to escape, and the ammonium ions in the electrolyte move to the cathode under the influence of the electric field gravity during the electrolysis process, resulting in the accumulation of ammonium ions near the cathode and causing the local ammonia concentration of the electrolyte to increase. During the electrolysis process, the temperature of the electrolyte is higher than the room temperature, which further promotes the volatilization of ammonia and wastes raw materials. Therefore, the electrolyte near the anode is prone to low ammonia water content, so that there is not enough ammonia and copper ions in the electrolyte near the anode for complexation reaction, and it is difficult to form a soluble copper ammonium complex, so some copper ions It will precipitate in the form of copper sludge and settle on the bottom of the electrolytic cell or the slurry will stick to the anode, which increases the resistance of the electrolytic cell. In this case, electrolysis will cause the necessary electrolysis voltage between the cathode and anode to increase, wasting electric energy.

Third, the return of the electrolyte after electrolysis to the alkaline etching production line will affect the etching quality: because the existing direct electrolysis method usually uses a large current to electrolyze copper in order to adapt to large-scale production, and the metal copper deposited on the cathode returns In the case of severe corrosion, the electrolytic copper surface will be very uneven, which will intensify the peak current effect and make the current unstable, which will lead to the rough and loose metal copper layer deposited and easy to fall off.

Fourth, in the prior art, in order to solve the problem that the precipitated metal copper layer is rough, loose and easy to fall off, a leveling agent is added to the electrolyte during the electrolysis process to electrolytically deposit a smoother copper skin or copper plate on the electrolysis cathode. The action principle of the leveling agent is to use its ability to block the discharge of metal ions in the solution to form an adsorption layer on the interface between the blocked surface and the solution, thereby improving the cathodic polarization and allowing metal ions to deposit at places with lower current densities. , so the concave surface of the workpiece can be leveled. However, the electrolytic solution after electrolysis contains a leveling agent. During the etching process, the leveling agent will adsorb the metal ions in the etching working solution and hinder the etching reaction, so the etching speed will be slowed down; therefore, if returning The use of alkaline etching production line will cause the etching speed to slow down and affect the quality of etching production.

Therefore, the application of the existing direct electrolysis method of alkaline etching waste liquid is still difficult to popularize and promote, and no enterprise adopts the direct electrolysis method to regenerate the alkaline etching liquid.

Contents of the invention

The purpose of the present invention is to provide a method for electrolytic reuse of alkaline etching waste liquid, which can improve the efficiency of electrolytically separating copper, and the waste liquid can be prepared into regenerated alkali that can maintain an ideal etching effect after electrolytic reuse Sexual etching sub-liquid.

The purpose of the present invention is achieved through the following technical solutions:

A method for electrolytic reuse of alkaline etching waste liquid, comprising using an electrolytic cell composed of an electrolytic cell, an electrolytic power supply, an electrolytic anode and an electrolytic cathode, wherein the electrolytic cell is divided into an anode area and a cathode area by a separator, including the following step:

(1) The mixed solution of alkaline etching waste liquid/or alkaline etching waste liquid and reducing agent is used as anolyte, and added in the anode area; the mixed solution of alkaline etching waste liquid and reducing agent is used as catholyte Liquid, added in the cathode area;

(2) Start the electrolysis power supply to carry out the electrolysis operation, and deposit metallic copper on the electrolysis cathode;

(3) According to the specific alkaline etching process, add one or more of ammonium chloride, ammonia, water and other alkaline etching solutions to the anolyte and/or catholyte after the electrolytic operation in step (2) Various, formulated as a regenerated alkaline etching sub-liquid that can be reused in the alkaline etching production line;

The alkaline etching waste liquid is an alkaline etching waste liquid with a copper ion concentration of 20-200 g/L and a pH value of 7-10.3.

The liquid formed in the anode area through the electrolysis of the anolyte is the anolyte, and the liquid formed in the cathode area through the electrolysis of the catholyte is the catholyte. That is to say, the anolyte and catholyte are the electrolytic solutions formed after the components of the anolyte and catholyte undergo chemical reaction changes during the electrolysis process.

The inventors have found through experiments that the reducing agent is mixed with the alkaline etching waste solution to prepare the electrolyte, and the reducing agent can undergo a redox reaction with the oxidizing agent (oxygen), thereby effectively consuming the oxygen in the electrolyte. As the oxygen concentration decreases, the formation rate of divalent copper ammonium complex in the electrolyte also decreases, thereby reducing the corrosion of metal copper precipitated on the cathode, and achieving the purpose of improving the recovery rate of metal copper.

The mass percent content of the reducing agent in the catholyte is 0.01 to 15%, preferably 0.01 to 13%, more preferably 1 to 13%; if the anolyte is a mixture of alkaline etching waste liquid and reducing agent In the mixed solution, the mass percentage of the reducing agent is also 0.01-15%, preferably 0.01-13%, more preferably 1-13%.

It has been proved through repeated experiments that when the content of the reducing agent in the catholyte in the cathode area of the electrolytic cell is 0.01 to 15%, it can better improve and alleviate the situation that the metal copper electrolytically separated on the electrolytic cathode is corroded back; Simultaneously, when the anolyte in the anode area of the electrolytic cell contains a reducing agent, its content should not be greater than 15%: when the reducing agent content of the catholyte is less than 0.01%, the electrolytic metal copper on the cathode is less likely to be corroded back The effect is not obvious; and when the reducing agent content of the anolyte and/or catholyte is greater than 15%, the anolyte and/or catholyte after electrolysis usually still have more reducing agent, which is formulated to regenerate When the alkaline etching sub-liquid is reused on the alkaline etching production line, the production etching rate of the alkaline etching working solution will be reduced.

The reducing agent is a reducing substance that can react with oxygen in an aqueous solution to consume oxygen, including but not limited to sulfite, thiosulfate, hydroxylamine sulfate, hydroxylamine hydrochloride, hydrazine hydrate, oxalic acid and oxalate, One or more of formic acid and formate, citric acid and citrate, glucose, vitamin C, tartaric acid, phosphite and hypophosphite, when the above-mentioned reducing agents are mixed, there is no mutual Scale limit.

Preferably, the reducing agent is one or more of sulfite, thiosulfate, hydroxylamine sulfate, hydroxylamine hydrochloride, hydrazine hydrate, oxalic acid and oxalate, when the above-mentioned reducing agents are mixed There is no ratio limit to each other.

More preferably, the reducing agent is an acidic reducing agent to reduce the volatilization of ammonia from the electrolyte by complexing and consuming free ammonia in the electrolyte. The acidic reducing agent includes hydroxylamine hydrochloride, hydroxylamine sulfate, At least one of the oxalic acid, when the above-mentioned multiple reducing agents are mixed, there is no ratio limitation among them.

In addition, after adopting the method of the present invention, the metal copper on the electrolytic cathode is less etched back, making the precipitated metal copper layer structure more compact, so the peak current effect is small, so there is no need to add a leveling agent during the electrolysis process. Therefore, when the regenerated alkaline etching sub-liquid prepared after the electrolytic treatment is returned to the alkaline etching production line for use, the etching speed and quality will not be affected. In addition, the present invention uses the separator to divide the electrolytic cell into an anode area and a cathode area, which can further reduce or even prevent the oxygen generated on the electrolysis anode from being close to the electrolysis cathode, so that divalent copper is generated near the electrolysis cathode The occurrence of ammonia complexes is greatly reduced, thereby alleviating the corrosion back to the electrolytically separated metallic copper on the electrolytic cathode.

The separator of the present invention can use materials such as filter cloth, ceramic filter plate, PE filter plate, electrolytic diaphragm, etc. that can effectively prevent the oxygen generated on the electrolytic anode from approaching the electrolytic cathode but allow some/or all ions to migrate between the two electrodes , thereby separating the electrolytic cell into an anode area and a cathode area.

According to different production equipment parameters and etching requirements, the design ratio of the components of the alkaline etching solution is also different. In addition, even after the electrolysis operation, the regenerated alkaline etching sub-liquid may still contain some copper ions, but when it is formulated into a regenerated alkaline etching sub-liquid and reused on the production line, it will not have a negative impact on the etching operation . Therefore, the other components and their concentrations in the regenerated alkaline etching sub-liquid except copper ions in step (3) can be adjusted according to the components and concentrations of ammonia nitrogen and chloride ions in general etching sub-liquids.

Preferably, the electrolytic cell adopts a sealed electrolytic cell, and the gas is pumped, so that the oxygen generated on the electrolytic anode is discharged out of the electrolytic cell in time, so as to reduce the oxygen content dissolved in the anolyte.

In the process of carrying out electrolysis operation in the present invention, can supplement described anolyte and/or alkaline etching waste liquid and/or reducing agent and/or described catholyte in described anode zone, and Replenish the catholyte and/or alkaline etching waste solution and/or reducing agent in the cathode area, that is, directly replenish the catholyte or supplement the components in the catholyte separately , thereby stabilizing the composition of the anolyte and/or catholyte and maintaining high electrolysis efficiency.

When adopting to supplement anolyte and/or alkaline etching waste solution and/or reducing agent to described anode zone, and/or supplement catholyte and/or alkaline etching waste solution and/or reducing agent to described cathode zone During electrolysis, it can be set according to the time and/or the real-time parameters of redox potential, pH value, specific gravity value, colorimetric value and liquid level of the anolyte and/or the catholyte, through artificial Or the automatic feeding controller is added, so that the concentration of copper ions and the concentration of ammonia in the anode area and the cathode area are stabilized, or it is controlled on the preset process parameter value, to reduce the copper precipitated on the electrolytic cathode Metals are etched back and contaminated. In addition, during the electrolysis process, the anolyte containing alkaline etching waste liquid is added to the anode area, and the ammonia content in the anolyte can also be increased to prevent the precipitation of copper sludge in the anolyte.

When the catholyte is replenished to the anode area in the electrolysis process, an overflow port can be set in the cathode area, and the overflow port is not lower than the preset liquid level in the anode area, so that When replenishing catholyte and/or alkaline etching waste liquid and/or reducing agent to the cathode area, if the actual liquid level of the cathode area exceeds the preset liquid level, the part exceeding the preset liquid level will pass through the The overflow port overflows from the cathode area to the anode area, thereby automatically adding catholyte to the anode area.

Preferably, the overflow port is set higher than the liquid level in the anode region. Especially when the separator allows cations to pass through, the ammonium ions in the anolyte will migrate to the electrolytic cathode under the influence of the electric field force; at the same time, the copper ammonium complex in the catholyte is electrochemically The reaction reduces copper ions to metallic copper and releases ammonium ions, resulting in a higher ammonia content than in the anolyte. Adding ammonia-rich catholyte to the anode zone can supplement the The content of ammonium ions in the anolyte can avoid copper sludge precipitation on the electrolytic anode, and the pressure between the anolyte and catholyte can be balanced.

The anode area and the cathode area can also be connected through a pipeline with a controllable pump, according to one or more parameters such as the preset time and/or the specific gravity value, pH value, and oxidation-reduction potential of the anolyte , the catholyte is fed into the anode area under the control of an automatic feeding controller.

Preferably, when the separator allows positive ions to pass through, the electrolysis power supply adopts a double-pulse power supply. During the electrolysis process, the ammonium ions in the anolyte will pass through the separator and enter the cathode area with the attraction of the electric field, which will easily cause copper sludge to precipitate in the anode area due to lack of ammonia. However, the use of double-pulse power supply can reversely lead the ammonium ions in the cathode region back to the anode region when the polarity is reversed, thereby effectively avoiding the precipitation of copper sludge and the electrolysis cathode on the electrolysis anode due to the lack of ammonia. The metal copper precipitated on the surface is quickly corroded due to a large amount of ammonia in the catholyte.

Preferably, the liquid level in the cathode region is kept higher than the liquid level in the anode region, so as to realize the specific gravity balance of the solution between the anode region and the cathode region. Since the electrolytic cell is divided into an anode area and a cathode area, if the separator can allow cations to pass through, the ammonium ions in the anode area will continuously enter the cathode area through the separator under the influence of the electric field attraction during the electrolysis process, resulting in The specific gravity difference between the anolyte and the catholyte is increasing, which in turn causes the separator to be deformed and damaged due to the excessive pressure difference caused by the specific gravity difference between the solutions on both sides. Keeping the liquid level in the cathode region higher than the liquid level in the anode region can effectively balance the pressure on both sides of the separator, reduce the deformation and damage of the separator and the liquid between the anode region and the cathode region penetration.

After the step (2) is completed, solid-liquid separation can be carried out first, and then step (3) can be carried out.

The present invention can be further improved as follows: add an ammonia source to the anode area by manual and/or automated equipment before the electrolysis operation and/or during the electrolysis process in the step (2), and the ammonia source is liquid ammonia and /or ammonia and/or ammonium carbonate and/or ammonium bicarbonate. This can effectively ensure that the anolyte contains enough ammonia to complex with copper ions to form a soluble copper-ammonia complex, so as to avoid bonding on the electrolytic anode by such as basic copper chloride, hydroxide Copper slime composed of copper and cupric ammonium chloride agglomerates, which affects the electrolysis efficiency. Preferably, the amount of the ammonia source is added before and/or during the electrolysis, so that the pH value of the anolyte and/or the anolyte in the anode zone is not lower than 6.

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

1. The present invention is compared with the processing method that adopts direct electrolysis method to recycle alkaline etching waste liquid in the prior art, can reduce described waste liquid in the electrolysis process the divalent cupric ammonium complex of cathodic region Generation speed, by controlling the concentration of oxygen and divalent copper ammonia complexes in the electrolyte that have anti-corrosion effects on metal copper, the effect of significantly improving the recovery efficiency of metal copper electrolysis can be achieved, and the recovery rate can reach 90%. or above;

2. The present invention has less anti-corrosion to electrolytically separated copper, so a dense copper layer can be obtained without adding a leveling agent in the electrolyte, so that the anolyte and/or anolyte generated after the waste liquid is electrolyzed by the present invention The catholyte can be formulated into a regenerated alkaline etchant that can maintain an ideal etching effect, and can be reused in an alkaline etch production line, thus solving the problem of affecting the etching quality of the regenerated etchant in the prior art due to the corrosion inhibition effect of the leveler. It leads to the problem that the alkaline etching solution cannot be regenerated, realizes the efficient recycling and reuse of the alkaline etching waste solution, and at the same time greatly reduces the pollution to the environment caused by the discharge of the alkaline etching waste solution;

3. When the present invention adopts an acidic reductant, it can reduce the escape of ammonia, improve the pollution of ammonia, and improve the production environment; When replenishing the catholyte in the area, it can also reduce the escape of ammonia gas;

4. When the present invention adopts to replenish alkaline etching waste liquid and/or ammonia source and/or catholyte in the anolyte, or when adopting double-pulse power supply, all can effectively restrain the phenomenon that copper slime is separated out in the anode area, reach The effect of reducing the energy consumption of electrolysis;

5. The present invention has less anti-corrosion to electrolytic copper, therefore, without using a leveler, the copper layer deposited on the electrolytic cathode is denser than the copper layer deposited in the prior art , on the one hand, the smaller the surface area of the copper surface exposed to the air, the easier it is to store and transport;

Detailed ways

The present invention will be further described below through specific embodiments.

In the embodiments of the present invention, the ammonia water used is preferably a commercially available concentration of 20% or 25% ammonia solution, and the liquid ammonia used is selected from the commercially available specification 40L bottled liquid ammonia product with a pressure relief valve; The etching production line is preferably the etching production line produced by Kejie PCB Equipment Factory. During the etching operation, the temperature of the etching cylinder is set to 49°C, and the pressure of the etching liquid nozzle of the etching machine is set to 1kg/cm ² ; except for the ones listed above In addition, those skilled in the art can also choose other products with similar properties to the above-mentioned products listed in the present invention according to conventional selection, all of which can achieve the purpose of the present invention.

The mentioned detection of copper ion concentration is a technique well known in the art.

The main components of the alkaline etching waste liquid are ammonia water, ammonium chloride and copper ammonium complexes.

Etching effect test : Take a pure copper etching rate test plate with a size of 500×300mm×1.5mm and put it into an etching cylinder for spray corrosion to test the etching rate; use a size of 620×540mm, a copper thickness of 1oz, and a developing line The double-sided circuit board with a wide line spacing of 50.8 μm was spray-etched to test the etching factor and the stability of the electrolytic recycling process system. Use methods known in this industry ("Printed Circuit Technology", Li Xueming, Ministry of Industry and Information Technology, Electronic Industry Vocational Skills Appraisal and Guidance Center, Fifth Edition, p387-389; "Metal Corrosion Theory and Application", Wei Baoming, Chemical Industry Publishing Society, p5-7; "On the Calculation Method of Etching Factor", Tian Ling et al., Printed Circuit Information 2007No.12, p55-56) to calculate the etching rate, etching factor K and electrolytic current efficiency.

Example 1

(1) Use an electrolytic cell composed of an electrolytic cell, an electrolytic power supply, an electrolytic anode and an electrolytic cathode, and separate the electrolytic cell into an anode area and a cathode area by superimposing a ceramic filter plate and a filter cloth;

Prepare the anolyte and catholyte according to the composition and ratio of the following table-1, and add the anolyte and catholyte to the anode area and the cathode area respectively;

(2) Start the electrolysis power supply to carry out the electrolysis operation, and deposit metallic copper on the electrolysis cathode;

(3) After 2 hours of electrolysis, mix the anolyte and catholyte, add 5% water by weight, and then use liquid ammonia to adjust the pH to 11 to form a regenerated alkaline etching sub-liquid, which is recycled for use in Etching production line.

Example 2

(1) Use an electrolytic cell consisting of a sealed electrolytic cell, an electrolytic power supply, an electrolytic anode and an electrolytic cathode, and use a PE filter plate to separate the electrolytic cell into an anode area and a cathode area;

Prepare the anolyte and catholyte according to the composition and ratio of the following table-1, and add the anolyte and catholyte to the anode area and the cathode area respectively;

(2) Start the electrolysis power supply to carry out the electrolysis operation, and at the same time, the gas generated in the electrolytic cell is pumped out, and metal copper is deposited on the electrolysis cathode, and is manually transferred to the anode area and the cathode area every half an hour. Supplementary volume of anolyte and catholyte with a volume of 5% of the preset liquid level;

(3) After 2 hours of electrolysis, the anolyte and catholyte were mixed for solid-liquid separation, and then adjusted to pH = 11 with liquid ammonia to form a regenerated alkaline etching sub-liquid, which was recycled for use in the etching production line.

Example 3

(1) Use an electrolytic cell consisting of a sealed electrolytic cell, an electrolytic power supply, an electrolytic anode and an electrolytic cathode, and use an anion membrane to separate the electrolytic cell into an anode area and a cathode area;

Prepare the anolyte and catholyte according to the composition and ratio of the following table-1, and add the anolyte and catholyte to the anode area and the cathode area respectively;

(2) Start the electrolysis power supply to carry out the electrolysis operation, and at the same time, the gas generated in the electrolytic cell is pumped out, and metallic copper is precipitated on the electrolysis cathode, and is automatically detected according to the real-time pH value of the anolyte in the anode area The input and control machine replenishes alkaline etching waste liquid to the anode area, and the automatic detection input and control machine adds reducing agent to the anode area according to the real-time oxidation-reduction potential of the anolyte, and the automatic detection input and control is based on the real-time colorimetric value of the catholyte. The machine supplies alkaline etching solution to the cathode area, and then adds reducing agent to the cathode area by the automatic detection and control machine according to the real-time oxidation-reduction potential of the catholyte, and the anolyte overflowing from the anode area is directly reused on the etching production line;

(3) After 2 hours of electrolysis, use liquid ammonia to adjust the catholyte to pH=11.5, thereby forming a regenerated alkaline etching sub-liquid, which is recycled for use in the etching production line.

Example 4

(1) Use an electrolytic cell consisting of a sealed electrolytic cell, an electrolytic power supply, an electrolytic anode, and an electrolytic cathode. The electrolytic cell is divided into an anode area and a cathode area by a filter cloth, and the anode area and the cathode area are separated by a pipeline with a controllable pump. The cathode area is connected;

Prepare the anolyte and the catholyte according to the composition and proportioning of the following table-1, and add the anolyte and the catholyte to the anode area and the cathode area respectively, in the alkaline etching waste liquid described in this embodiment Also contains etching additives;

(2) adjust the pH value of the anolyte to 6, start the electrolysis power supply to carry out the electrolysis operation, simultaneously the gas produced in the electrolysis cell is exhausted, and metal copper is precipitated on the electrolysis cathode, and according to the anode The real-time specific gravity value of the anolyte in the zone is replenished with catholyte to the anode zone by the automatic detection input control machine, and the reducing agent is supplied to the anode zone by the automatic detection input control machine according to the real-time oxidation-reduction potential of the anolyte, and then according to the real-time The specific gravity value is replenished with catholyte in the cathode area by the automatic detection and control machine;

(3) After 2 hours of electrolysis, the anolyte overflowing from the anode area is mixed with the etching sub-liquid additive to pH = 10.5, thereby forming a regenerated alkaline etching sub-liquid, which is recycled for use in the etching production line.

Example 5

(1) Use an electrolytic cell composed of an electrolytic cell, a double-pulse electrolytic power supply, an electrolytic anode and an electrolytic cathode, and use a cationic membrane to separate the electrolytic cell into an anode area and a cathode area. The gas extraction system and material inlet, the anode area and the cathode area are equipped with stirring devices, overflow ports, redox potential and pH detection devices, and the anode area and the cathode area are connected by pipelines with controllable pumps ;

Prepare the anolyte and catholyte according to the composition and ratio of the following table-1, and add the anolyte and catholyte to the anode area and the cathode area respectively;

(2) Keep the liquid level in the cathode area higher than the liquid level in the anode area, start the electrolysis power supply to carry out the electrolysis operation, and simultaneously pump out the gas generated in the electrolysis cell, and reverse the electrolysis power supply every 5 minutes after forward energization. To energize for 1 minute, metal copper is precipitated on the electrolytic cathode, and according to the real-time specific gravity value of the anolyte in the cathode area, the alkaline etching waste liquid is replenished in the anode area by the automatic detection and control machine, and according to the real-time specific gravity value of the catholyte Oxidation-reduction potential is automatically detected and controlled to replenish the reducing agent to the cathode area, and the part of the catholyte that is higher than the preset liquid level overflows into the anode area;

(3) After 2 hours of electrolysis, the anolyte overflowing from the anode area is mixed with the catholyte in the cathode area, and then adjusted to pH = 11.5 with liquid ammonia to form a regenerated alkaline etching sub-liquid, which is recycled in the etching production line superior.

Example 6

(1) Use an electrolytic cell consisting of a sealed electrolytic cell, an electrolytic power supply, an electrolytic anode, and an electrolytic cathode. The electrolytic cell is divided into an anode area and a cathode area by a filter cloth, and the anode area and the cathode area are separated by a pipeline with a controllable pump. The cathode area is connected;

Prepare the anolyte and catholyte according to the composition and ratio of the following table-1, and add the anolyte and catholyte to the anode area and the cathode area respectively;

(2) Keep the liquid level in the cathode area higher than the liquid level in the anode area, start the electrolysis power supply to carry out the electrolysis operation, and simultaneously pump out the gas generated in the electrolysis cell, and reverse the electrolysis power supply every 5 minutes after forward energization. After energizing for 1 minute, metal copper is precipitated on the electrolytic cathode, and according to the real-time pH value, redox potential and timing setting of the anolyte in the anode area, the catholyte is replenished in the anode area by the automatic detection and control machine, and According to the real-time oxidation-reduction potential of the catholyte, the catholyte is replenished to the cathode area by the automatic detection and control machine;

(3) after the electrolysis operation is through 2h, the anolyte that the anode area overflows is mixed with the catholyte in the cathode area, and adds 1% sodium chlorate, the water of 5% by weight, then uses liquid ammonia to adjust to pH= 11.5, so as to form a regenerated alkaline etching sub-liquid, which is recycled for use in the etching production line.

Comparative example 1

(1) Use an electrolytic cell consisting of an electrolytic cell, an electrolytic power supply, an electrolytic anode and an electrolytic cathode;

Prepare the electrolyte according to the ingredients and proportions in Table-1 below and add it to the electrolytic cell, and add thiourea as a leveling agent at 1mol/L;

(2) Start the electrolysis power supply to carry out the electrolysis operation, and deposit metallic copper on the electrolysis cathode;

(3) After 2 hours of electrolysis, add 5% water to the electrolyzed solution by weight, and then use liquid ammonia to adjust the pH to 11, thereby forming a regenerated alkaline etching sub-liquid, which is recycled for use in the etching production line.

Comparative example 2

(1) Use an electrolytic cell consisting of an electrolytic cell, an electrolytic power supply, an electrolytic anode and an electrolytic cathode;

Prepare the electrolyte according to the ingredients and proportions in Table-1 below and add it to the electrolytic cell, and add thiourea as a leveling agent at 1mol/L;

(2) Start the electrolysis power supply to carry out the electrolysis operation, and deposit metallic copper on the electrolysis cathode;

(3) After 2 hours of electrolysis, add sub-liquid additives to the electrolyzed solution to adjust the pH to 10.5, thereby forming a regenerated alkaline etching sub-liquid, which is recycled for use in the etching production line.

Table 1

Remarks: "Etching speed/or etching factor when no regenerated alkaline etchant is used" in Table-1 should be understood as not using regenerated alkaline etchant, but the etching speed/or when the original alkaline etchant works alone etch factor.

The etching speed and etching quality are not only affected by the performance of the etching solution itself, but also vary with the temperature of the etching solution, the spray pressure of the etching equipment and other factors. Therefore, all experimental conditions other than the recovery method need to be kept the same in order for the results to be compared.

As can be seen from the results in Table-1, Comparative Example 1 and Comparative Example 2 are existing schemes of direct electrolysis of alkaline etching waste liquid, and their electrolytic copper current efficiencies are only 60% and 64%. After the solution is prepared as a regenerated alkaline etching sub-solution, the etching speed drops by 47.5% and 43.3%, respectively, and the etching quality also decreases. However, the electrolytic copper current efficiency of Examples 1-6 is at least 53.3% higher than that of the prior art, and the solution after electrolysis is prepared as a regenerated alkaline etching sub-solution for repeated use, which has no obvious adverse effects on the etching speed and etching quality.

It should be pointed out that the above-mentioned embodiment is only a further description of the present invention, rather than a limitation, and any adjustment or change within the equivalent meaning and scope of the technical solution of the present invention by those skilled in the art should be considered as being included in the present invention. within the scope of protection of the invention.

Claims (9)

1. A method for electrolytic reuse of alkaline etching waste liquid, comprising using an electrolytic cell composed of an electrolytic cell, an electrolytic power supply, an electrolytic anode and an electrolytic cathode, and the electrolytic cell is separated into an anode area and a cathode area by a divider, Wherein said alkaline etching waste liquid is the etching waste liquid produced when carrying out operation production with alkaline cupric ammonium chloride etching liquid, it is characterized in that, comprises the following steps: (1) The mixed solution of alkaline etching waste liquid/or alkaline etching waste liquid and reducing agent is used as anolyte, and added in the anode area; the mixed solution of alkaline etching waste liquid and reducing agent is used as catholyte Liquid, added in the cathode area; (2) start the electrolysis power supply to carry out the electrolysis operation, and deposit metallic copper on the cathode of the electrolysis; The generation rate of the valence cupric ammonium complex decreases accordingly, thereby reducing the corrosion of the precipitated metal copper on the cathode; (3) According to the specific alkaline etching process, add one or more of the following alkaline cupric ammonium chloride etching solution components to the anolyte and/or catholyte after the electrolysis operation in step (2): ammonium chloride , ammonia, water, carbonate and additives, formulated as a regenerated alkaline etching sub-liquid that can be reused in the alkaline etching production line; The alkaline etching waste liquid is an alkaline etching waste liquid with a copper ion concentration of 20 to 200 g/L and a pH value of 7 to 10.3; The mass percentage content of the reducing agent in the catholyte is 0.01-15%; if the anolyte is a mixture of alkaline etching waste liquid and reducing agent, the mass percentage of the reducing agent is 0.01-15% . 2. The method for electrolytic reuse of alkaline etching waste liquid according to claim 1, characterized in that, the mass percent content of reducing agent in the catholyte is 0.01 to 13%; if the anolyte is In the case of the mixed liquid of alkaline etching waste liquid and reducing agent, the mass percentage of reducing agent is 0.01-13%. 3. The method for electrolytic reuse of alkaline etching waste liquid according to claim 2, characterized in that, the mass percent content of reducing agent in the catholyte is 1 to 13%; if the anolyte is In the case of the mixed liquid of alkaline etching waste liquid and reducing agent, the mass percentage of reducing agent is 1-13%. 4. The method for electrolytic reuse of alkaline etching waste liquid according to any one of claims 1 to 3, wherein the reducing agent is sulfite, thiosulfate, hydroxylamine sulfate, hydroxylamine hydrochloride, One or more of hydrazine hydrate, oxalic acid and oxalate, formic acid and formate, citric acid and citrate, glucose, vitamin C, tartaric acid, phosphite and hypophosphite, when the above There is no ratio limit to each other when the agents are mixed. 5. The method for electrolytic reuse of alkaline etching waste liquid according to claim 4, characterized in that, in the process of carrying out the electrolysis operation, replenish the anolyte and/or alkali in the anode area Active etching waste liquid and/or reducing agent and/or described catholyte, and replenish described catholyte and/or alkaline etching waste liquid and/or reducing agent in described cathodic region, namely directly supplement The catholyte or the components in the catholyte are supplemented separately, so as to stabilize the anolyte and/or the components of the catholyte and maintain high electrolysis efficiency. 6. the method for electrolytic reuse of alkaline etching waste liquid according to claim 5, is characterized in that, when adopting to supplement anolyte and/or alkaline etching waste liquid and/or reducing agent to described anode area, and /or when replenishing the catholyte and/or alkaline etching waste solution and/or reducing agent to the cathode area, according to the time setting and/or the anolyte and/or the catholyte in the electrolysis process The redox potential, pH value, specific gravity value, colorimetric value, and real-time parameters of the liquid level are added through manual or automatic feeding controllers to stabilize the copper ion concentration and ammonia concentration in the anode and cathode regions. Or control it on the preset process parameter value, so as to reduce the situation that the copper metal deposited on the electrolytic cathode is etched back and polluted. 7. The method for electrolytic reuse of alkaline etching waste liquid according to claim 5, characterized in that, when the catholyte is replenished to the anode area in the electrolysis process, an overflow port is set in the cathode area , and the overflow port is not lower than the preset liquid level in the anode area, so that when the catholyte and/or alkaline etching waste liquid and/or reducing agent are replenished to the cathode area, if the If the actual liquid level in the cathode area exceeds the preset liquid level, the part exceeding the preset liquid level will overflow from the cathode area to the anode area through the overflow port, thereby automatically adding the catholyte to the In the anode region. 8. The method for electrolytic reuse of alkaline etching waste liquid according to claim 5, characterized in that, the anode area and the cathode area are connected through a pipeline with a controllable pump, according to the preset time and /or one or more parameters of the specific gravity value, pH value, and oxidation-reduction potential of the anolyte are controlled by an automatic feeding controller to feed the catholyte into the anode area. 9. the method for alkaline etching waste liquid electrolysis recycling according to claim 8, is characterized in that, before described step (2) carries out electrolysis operation and/or during electrolysis, to anode by manual and/or automatic equipment Ammonia source is added in the zone, and described ammonia source is liquid ammonia and/or ammonia water and/or ammonium carbonate and/or ammonium bicarbonate.