TWI880111B - A method and a device for copper recycling via precipitation and regenerating via electrolysis from acidic cupric chloride etchant waste - Google Patents

Abstract

The invention provides a method and a device for copper recycling via precipitation and regenerating via electrolysis from acidic cupric chloride etchant waste. The method includes the following steps. Step 1: oxidizing working etchant by an electrolytic cell during an etching process, and the electrolytic cell is divided into cathode area and anode area. Step 2: at least one of the following or at least one mixed solution of the following is reacted with the copper extractant to generate copper salt precipitate, the electrolysed anolyte, the electrolysed catholyte, the oxidized catholyte, and the cupric chloride etchant waste; step 3: the mixture is solid-liquid separated to obtain solid copper salt precipitate and acidic filtrate, and the obtained acidic filtrate is directly used as a regenerated etchant or made up into a regenerated etchant which is applied on an etching production line, and the solid copper salt obtained is seen as the copper recovery product. The invention effectively solves the problem of the increasing etchant waste amount during the existing production process of acidic cupric chloride etching.

Description

Acidic copper chloride etching waste liquid precipitation copper electrolytic regeneration method and device

The invention belongs to the field of etching for circuit board production, and specifically relates to a method and device for electrolytically regenerating copper by precipitation of waste liquid from acidic copper chloride etching.

The acid copper chloride etching process is one of the most commonly used acid etching processes in the circuit board pattern manufacturing process. It uses copper chloride as an etchant to etch and dissolve the exposed metal copper on the copper-clad board that is not covered and protected by ink or film anti-etching layer, thereby forming a circuit. Etching chemical reaction equation: Cu+CuCl ₂ →2CuCl.

The main components of acidic copper chloride etching solution are hydrochloric acid, copper chloride, and optional chloride salts and additives. Common chloride salts are ammonium chloride, sodium chloride and ferric chloride, and common additives are organic acids. Since the copper chloride in the etching solution reacts with the metal copper to be etched to form cuprous chloride that has no etching ability, in order to maintain the etching ability stability of the etching solution, hydrochloric acid and etching oxidant are usually continuously added to the etching working solution during the etching process to oxidize cuprous chloride into cupric chloride to participate in etching again. When the copper chloride etching solution contains chloride salt and/or additives, in addition to adding hydrochloric acid and etching oxidant, the chloride salt and additives need to be supplemented according to the process. Therefore, it is common in the industry to mix hydrochloric acid with chloride salt and/or additives and add them together. The mixed solution is called etching liquid. The etching operation needs to be carried out at about 50°C. The lower the hydrochloric acid in the etching solution, the less acid mist will evaporate. However, because the reaction of cuprous chloride oxidizing to cupric chloride requires the participation of chloride ions, the existing etching solution with lower acidity uses ferric chloride as a component to ensure that there are enough chloride ions in the etching solution to maintain the etching reaction.

At present, the industry uses hydrogen peroxide or sodium chlorate solution as the etching oxidant for acidic copper chloride etching. It is also common to mix chlorine salt with sodium chlorate as the etching oxidant. With the addition of etching oxidant and hydrochloric acid and/or etching liquid, the increased volume of the etching working liquid overflows from the etching production line. The industry calls the solution overflowed due to the increase in the volume of the etching working liquid as etching waste liquid. Circuit board manufacturers have always sold these etching waste liquids at low prices to qualified environmental protection companies for treatment. In recent years, in response to the environmental call for emission reduction and to improve the production economic benefits of circuit board factories, some circuit board manufacturers have begun to recover copper from etching waste liquid in their factories. The existing online recovery technology of acid copper chloride etching waste liquid generally adopts the following two methods: (1) by adding sodium hydroxide and/or sodium carbonate to the acid copper chloride etching waste liquid for acid-base neutralization reaction, after filtering, copper hydroxide or copper carbonate filter residue and chloride salt filter liquid are obtained. The filter residue is recovered as a copper product, and the filter liquid is discharged for external treatment. (2) The waste liquid from acid copper chloride etching is treated by online electrolysis to recover copper, so that the copper ions in the waste liquid are electrolyzed on the electrolytic cathode to recover metallic copper. For the acid copper chloride etching waste liquid that does not contain iron, during the electrolysis process, the chlorine ions undergo an electrochemical oxidation reaction on the electrolytic anode to precipitate chlorine gas. Part of the chlorine gas is recycled in the etching line, and the rest is absorbed by sodium hydroxide solution or ferrous chloride solution. The above method (1) and the method (2) for the iron-free acidic copper chloride etching waste liquid cannot return all the chlorine ions in the etching waste liquid to the original etching liquid system for recycling. In addition, the above two methods still need to add external etching oxidants during the production process, which increases the amount of waste liquid. Therefore, the existing recycling technology can only recycle copper and cannot well reuse the chlorine salt in the original etching system, making it difficult to achieve the process requirements of environmental protection, emission reduction and recycling. As for the iron-containing acidic copper chloride etching waste liquid, although the chlorine gas released on the electrolytic anode during the electrolysis process can be effectively absorbed by the waste liquid, when electrolyzing copper on the electrolytic cathode, the trivalent iron ions in the waste liquid must be completely reduced to divalent iron ions before the electrochemical reduction reaction of copper can be realized, which consumes a lot of electricity.

In addition, in the etching production process using acid copper chloride etching solution, since the etching temperature is usually 50°C, under the dual effects of etching temperature and etching solution spraying pressure, the ink or film used as the anti-corrosion layer often dissolves into oily substances in the etching solution. When accumulated to a certain extent, it will affect the etching quality and efficiency. In the existing acid copper chloride etching waste liquid recycling process, the treatment effect of the organic impurities in the ink and film contained in the waste liquid is not obvious. Reuse will cause them to accumulate continuously, affecting the quality and efficiency of etching production.

In summary, it is necessary to optimize and improve the existing acid copper chloride etching waste liquid recovery process.

The first purpose of the present invention is to provide a method for electrolytic regeneration of copper from acidic copper chloride etching waste liquid, which can effectively solve the defect that the existing acidic copper chloride etching solution has an incremental amount of etching waste liquid due to the addition of etching oxidant in the production process; the present invention also provides a method for recovering copper products by obtaining copper salts through chemical reactions, or provides a method for recovering copper ions in waste liquid and performing oxidation regeneration reaction on etching waste liquid by combining the two methods of electrolytic copper extraction and regeneration of etching solution and chemical reaction to obtain copper salts. The filtered liquid obtained in the process can be directly or circulated in the etching process after being prepared. The process can not only electrolytically oxidize and regenerate the acidic copper chloride etching working solution in real time during the etching production process to save etching oxidants or eliminate the need for using external etching oxidants, but also adjust and allocate the amount of copper to be extracted in a scheme combining the two processes of electrolytic oxidation regeneration copper extraction method and chemical reaction precipitation copper extraction method according to the specific electricity consumption situation, so that the chlorine ions in the acidic copper chloride etching solution can be recycled to save hydrochloric acid and/or chlorine salt additive production raw materials. Compared with the existing electrolytic copper recovery technology and chemical neutralization reaction technology, the process of the present invention is more energy-saving, environmentally friendly, efficient and high-quality, and realizes a recycling and reuse process that further reduces the three wastes or even eliminates the three wastes.

The second object of the present invention is to provide a device used in the method of electrolytic regeneration of copper by precipitation of waste solution from acidic copper chloride etching.

In order to achieve the above first purpose, the technical solution adopted by the present invention is:

A method for electrolyzing and regenerating copper from waste acid copper chloride etching solution by precipitation includes the following steps.

Step 1: using an electrolytic reaction tank to oxidize the etching working solution in real time during the etching process, wherein the electrolytic reaction tank is provided with an electrolytic tank separator to divide the electrolytic tank into an electrolytic tank anode area and an electrolytic tank cathode area; the electrolytic tank anode area contains an anode and an anode electrolyte, and the electrolytic tank cathode area contains a cathode and a cathode electrolyte, wherein the anode electrolyte is an etching working solution from an acidic copper chloride etching production line. The anodic electrolyte treated by electrolysis is returned to the acid copper chloride etching production line as a regeneration etching working solution, and the chlorine gas generated by the anode during the electrolysis process is used to oxidize at least one of the cathode electrolyte, the regeneration etching sub-liquid, the etching working solution, the etching waste solution, and the acidic filter solution obtained in step three, or a mixture of more than one of them, wherein the cathode electrolyte is an electrolyte solution.

Step 2: mixing at least one of the electrolytically treated anodic electrolyte, the electrolytically treated cathodic electrolyte, the oxidized cathodic electrolyte, and the copper chloride etching waste solution, or a mixture of more than one of the above, with a copper extractant, so that copper ions from the copper chloride etching waste solution and/or the copper chloride etching working solution react in the reaction mixture to generate copper salt precipitates.

Step 3: The solid-liquid mixture obtained by the reaction in step 2 is subjected to solid-liquid separation to obtain a solid copper salt precipitate and an acidic filter solution, the obtained acidic filter solution is directly used as a regenerated etching sub-liquid for recycling in the etching process or is prepared as a regenerated etching sub-liquid for recycling in the etching process, and the obtained solid copper salt is used as a copper recovery product.

The main components of the acid copper chloride etching waste liquid of the present invention are hydrochloric acid and copper chloride, and may contain ferric chloride, ammonium chloride, sodium chloride and additives. The main component of the acidic filter liquid obtained in step three is hydrochloric acid solution or a mixture of hydrochloric acid and chloride salt.

The electrolytic cell separator in the electrolytic cell described in step 1 is a material that can effectively reduce or even prevent the cations in the anodic electrolyte from migrating from the anodic region to the cathodic region under the action of the electric field force, and is specifically at least one of an anion exchange membrane, a bipolar membrane, and a reverse osmosis membrane. Preferably, the electrolytic cell separator in the electrolytic cell described in step 1 is an anion exchange membrane, thereby allowing the chlorine ions in the cathodic electrolyte to enter the anodic region of the electrolytic cell through the electrolytic cell separator, so that the anodic electrolyte can be supplemented with chlorine ions for more effective oxidation. The cathodic electrolyte is an aqueous solution of an electrolyte, preferably a hydrochloric acid solution or an acidic solution of a chlorine salt. The acidic solution of chlorine salt is a mixed solution of hydrochloric acid and at least one chlorine salt, preferably a mixed solution of hydrochloric acid and ferric chloride and/or ammonium chloride and/or sodium chloride and/or cupric chloride. Acidic copper chloride etching waste liquid, acidic copper chloride etching working liquid, electrolyzed anode electrolyte, oxidized cathode electrolyte, acidic filter liquid obtained in step 3, and regenerated etching sub-liquid also belong to the above-mentioned hydrochloric acid solution or acidic solution of chlorine salt.

The main function of step 1 is to electrolytically oxidize and regenerate the etching working solution in the anode area of the electrolytic cell, so that less or even no external etching oxidant is added during etching, avoiding the need to add external etching oxidant during etching production, which causes excessive expansion of the volume of the etching waste liquid, so that the filter liquid produced in the subsequent chemical reaction copper extraction can be recycled and consumed as the regenerated etching sub-liquid. As an implementation scheme of this process, the anode area of the electrolytic cell is used to perform an online and instant electrochemical oxidation reaction on the etching working solution.

During the electrolysis process, an electrochemical reaction occurs in the anode region of the electrolytic cell used in the present invention, in which chlorine ions are oxidized to chlorine gas. When the copper chloride etching waste liquid contains monovalent copper ions or divalent iron ions, a chemical reaction occurs in which they are oxidized by chlorine gas and converted into divalent copper ions or trivalent iron ions, thereby increasing the redox potential of the anode electrolyte. In the cathode area of the electrolytic cell, when the cathode electrolyte contains copper ions, an electrochemical reaction occurs in which the divalent copper ions are reduced to monovalent copper ions and even metallic copper is precipitated. When the cathode electrolyte contains trivalent iron ions, an electrochemical reaction occurs in which the trivalent iron ions are reduced to divalent iron ions. When the cathode electrolyte contains neither divalent copper ions nor trivalent iron ions in an acidic solution (such as hydrochloric acid) or when the concentration of variable valence metal ions in the acidic solution is low (for example, hydrochloric acid contains only trace amounts of cupric chloride and/or ferric chloride), an electrolysis reaction of water occurs to produce hydrogen. The reaction equations of the above electrochemical reactions are as follows: (1) The electrochemical reactions occurring at the electrolytic anode are Cu ⁺ -e ^- →Cu ²⁺ ; 2Cl ^- -2e ^- →Cl ² ↑; Fe ²⁺ -e ^- →Fe ³⁺ (when the copper chloride etching working solution contains Fe ²⁺ ); (2) The electrochemical reactions occurring at the electrolytic cathode are Cu ²⁺ +e ^- →Cu ⁺ ; Cu ⁺ +e ^- →Cu; Fe ³⁺ +e ^- →Fe ²⁺ (when the cathode electrolyte contains Fe ³⁺ ); 2H ₂ O+2e ^- →2OH ^- +H ₂ ↑ (when the cathode electrolyte does not contain variable-valence metal ions or the concentration of variable-valence metal ions is low).

The inventors have also found through many experiments that the use of the anode tank area of the electrolytic cell to electrolytically oxidize and regenerate the etching working solution can effectively oxidize and degrade the oily organic impurities in the ink and film in the etching solution, solve the problem of ink and film organic impurity accumulation caused by recycling, and ensure the stability of etching quality and efficiency. This may be because the strong oxidizing property generated on the electrolytic anode and the generated chlorine and other oxidants have a better degradation effect on the oily organic impurities in the solution when the anode tank area of the electrolytic cell is used to electrolytically oxidize and regenerate the etching working solution.

As a preferred embodiment of the present invention, the process of the present invention is carried out on an acidic copper chloride etching solution containing iron ions, and both the etching working solution and the etching waste solution contain iron ions. When the iron-containing acidic copper chloride etching solution is involved in etching, a chemical reaction occurs in which trivalent iron ions are reduced to divalent iron ions, so both the etching working solution and the etching waste solution contain divalent iron ions. The inventors have found through experimental results that when the process of the present invention is carried out on an acidic copper chloride etching solution containing iron ions, the treatment of oily organic impurities in ink and film in the etching solution is more significant. This may be because the chlorine gas released from the anode of the electrolytic cell during the electrolysis process dissolves in the anode electrolyte to generate hypochlorous acid, which can react with divalent iron ions to generate highly oxidizing hydroxyl free radicals •OH, which oxidize and remove organic impurities: HClO+Fe ²⁺ →Fe ³⁺ +Cl ^- +•OH.

Furthermore, when the etching working solution and the etching waste solution contain ammonium chloride, during the electrolytic oxidation regeneration process using the anode tank area of the electrolytic cell, the chlorine gas precipitated on the anode can react with the ammonium chloride under acidic conditions to generate explosive nitrogen trichloride. Since divalent iron ions can reduce nitrogen trichloride to ammonium chloride, the process of the present invention can effectively avoid the generation of nitrogen trichloride hazards when applied to iron-containing acidic copper chloride etching solutions, thereby improving the safety of the process.

In addition, the process of the present invention is used in the iron-containing acidic copper chloride etching process, which avoids the power consumption disadvantage of the existing electrolytic recovery process, and it is not necessary to reduce all the trivalent iron ions in the electrolytic waste liquid to divalent iron ions before copper can be extracted. It has obvious advantages in terms of energy consumption, equipment investment, and environmental protection.

The present invention uses an electrolytic cell to perform online real-time oxidation and regeneration treatment on the etching working solution. Under normal electrolytic oxidation working conditions, the cathode area of the electrolytic cell will exhibit the following three different working conditions:

1. When the cathode electrolyte does not contain copper ions and does not contain trivalent iron ions or the concentration of trivalent iron ions is low, water electrolysis occurs in the cathode region of the electrolytic cell or hydrogen ions in the acid solution are reduced to produce hydrogen gas.

2. Add an acidic solution containing copper ions and/or trivalent iron ions to the cathode solution of the electrolytic cell. When the copper ion concentration in the cathode electrolyte is high, an electrochemical reaction of electrolyzing metallic copper mainly occurs on the electrolytic cathode. When the trivalent iron ion concentration in the cathode electrolyte is high, an electrochemical reaction of reducing trivalent iron ions to divalent iron ions mainly occurs on the electrolytic cathode. When the copper ion concentration and/or trivalent iron ion concentration in the cathode electrolyte is low, hydrogen gas will be precipitated on the electrolytic cathode. Therefore, a hydrometer, a photoelectric colorimeter, and a redox potentiometer can be further used to control the copper content and/or the concentration of trivalent iron ions in the cathode electrolyte during the electrolysis process. The cathode electrolyte contains at least one of acidic copper chloride etching waste liquid, copper-containing cathode overflow liquid subjected to oxidation treatment, and an electrolytically treated anodic electrolyte, or a mixture thereof. By controlling the concentration of copper ions or trivalent iron ions in the cathode electrolyte, the work distribution amount of the two methods of electrolytic copper extraction and chemical reaction copper extraction can be selected and allocated. This working method can not only extract copper through electrolysis in an electrolytic cell, but also combine the process of recovering copper by mixing the overflow liquid from the cathode electrolysis with a copper extractant to obtain copper salt.

3. When the cathode electrolyte contains copper ions and/or iron ions, the cathode electrolyte is mixed with an oxidant to oxidize and regenerate divalent copper ions and/or trivalent iron ions, thereby reducing or even avoiding the precipitation of hydrogen gas on the electrolytic cathode. When the cathode electrolyte contains copper ions, a redox potentiometer can be used to control the addition of an oxidant to the cathode solution of the electrolytic cell according to the structure and process requirements of the electrolyzer, so that the cathode electrolyzes as little copper as possible or even no metallic copper. When the separator of the electrolytic cell is an anion exchange membrane, as the electrolytic reaction and the chemical reaction with the oxidant proceed, the chloride ion concentration and acid concentration in the cathode electrolyte continue to decrease. At this time, the acidity meter can be further used to control the addition of at least one of hydrochloric acid, acidic regeneration etching solution, and acidic copper chloride etching waste solution to the cathode area of the electrolytic cell to maintain the chemical reaction between the cathode electrolyte and the oxidant, so as to enable the electrolytic cell to work normally. Preferably, the cathode electrolyte is acidic copper chloride etching waste solution and/or iron-containing regeneration etching sub-liquid and/or iron-containing filter solution obtained in step three, and the cathode region structure of the electrolytic cell is configured with an overflow port, and an oxidant is added to the cathode region solution of the electrolytic cell to carry out an oxidation reaction, and acidic copper chloride etching waste solution and/or iron-containing regeneration etching sub-liquid and/or iron-containing acid filter solution obtained in step three is added. To replenish the chloride ions and acid in the cathodic electrolyte; to add alkaline substances or copper extractants to the overflowed cathodic electrolyte for mixed reaction so that the copper ions and/or iron ions therein are converted into hydroxides or carbonates or oxalates for precipitation and separation; or to extract copper from the overflowed cathodic electrolyte by electrolysis; the solution obtained after the removal of copper ions can be prepared for reuse or discharged as wastewater.

As a preferred implementation of the above-mentioned method 3 of the present invention: during the electrolysis process, in order to keep a certain amount of divalent copper ions and/or trivalent iron ions in the cathode electrolyte, to avoid the precipitation of explosive hydrogen gas on the electrolytic cathode and to avoid a large amount of copper precipitation on the cathode, the oxidant added is at least one of sodium chlorate, potassium chlorate, sodium perchlorate, potassium perchlorate, sodium chlorite, potassium chlorite, chlorine, oxygen, ozone, air, hydrogen peroxide or a mixture thereof. In addition to external chlorine, the chlorine can also be directly used as the chlorine precipitated by the reaction in the anode area of the electrolytic cell.

The copper extractant described in step 2 is a chemical that can form a solid precipitate with divalent copper ions in a hydrochloric acid solution environment, and the specific copper extractant is oxalic acid. In step 2, when the copper extractant is used to carry out a mixed reaction with at least one or more mixed solutions of an electrolytically treated anodic electrolyte, an electrolytically treated cathodic electrolyte, an oxidized cathodic electrolyte, and copper chloride etching waste solution, each solution can be mixed with the copper extractant separately, or two or more copper-containing solutions can be mixed together and then mixed with the copper extractant to produce precipitated copper salt.

The chemical reaction formula is: H ₂ C ₂ O ₄ +CuCl ₂ →2HCl+CuC ₂ O ₂ ↓.

In step 2, the oxidized cathodic electrolyte is specifically a solution obtained by oxidizing the electrolyzed cathodic electrolyte with an oxidant when the cathodic electrolyte contains copper ions after overflowing the electrolytic cell. The inventors have found that in an acidic environment dominated by hydrochloric acid, divalent copper ions can combine with oxalic acid to form a relatively stable copper oxalate precipitate, while monovalent copper ions and ferrous ions cannot form a stable precipitate because their oxalates are easily soluble in hydrochloric acid solutions. During the electrolysis process, an electrochemical reduction reaction occurs at the electrolytic cathode, so the cathode electrolyte contains copper salt with monovalent copper ions. In addition, when the cathode electrolyte contains trivalent iron ions, an electrochemical reaction occurs in which the trivalent iron ions are reduced to divalent iron ions. Therefore, for the cathodic electrolyte containing monovalent copper salt, the cathodic electrolyte overflowing from the overflow port of the cathode region of the electrolytic cell is first oxidized to produce a copper-containing solution containing a large amount of divalent copper ions and a small amount of trivalent iron ions, i.e., the oxidized cathodic electrolyte, and then reacted with a copper extractant to perform a copper extraction reaction. After treatment by this method, the copper salt recovery rate can be effectively improved and the consumption of oxalic acid due to the high content of trivalent iron ions can be reduced.

The oxidant used in the oxidation treatment of the cathode electrolyte is preferably at least one of sodium chlorate, potassium chlorate, sodium perchlorate, potassium perchlorate, sodium chlorite, potassium chlorite, sodium hypochlorite, sodium percarbonate, chlorine, oxygen, ozone, air, and hydrogen peroxide. In addition to external chlorine, the chlorine can also be directly used as the chlorine generated and precipitated on the electrolytic anode. When the acidic copper chloride etching solution contains ferric chloride, the etching waste solution and/or etching working solution and/or anodic electrolyte can also be used as an oxidant for oxidation treatment of the cathodic electrolyte, and the oxidizing ferric chloride therein is used to oxidize the monovalent copper ions in the cathodic electrolyte to prepare an ideal solution of acidic divalent cupric salt and ferrous salt to react with oxalic acid to obtain high-yield copper oxalate.

The present invention can be improved as follows: when the cathode electrolyte contains copper ions, an acidic solution containing copper ions and/or trivalent iron ions is added to the cathode zone solution of the electrolytic cell, or the cathode electrolyte is mixed with an oxidant for oxidation regeneration, so that the redox potential of the cathode electrolyte is controlled to be not less than 250 mV. When the cathode electrolyte contains copper ions and its redox potential is not less than 250 mV, the cathode electrolyte contains an appropriate amount of divalent copper ions, which can achieve a better copper salt recovery effect.

In addition, the present invention uses the chlorine gas generated on the electrolytic anode during the electrolysis process to oxidize at least one or a mixture of the cathode electrolyte, the etching waste liquid, the anodic electrolyte, and the etching working solution through process control, so that the monovalent copper ions in the oxidized solution can be oxidized into divalent copper ions. When the method of the present invention is used in an acidic copper chloride etching process containing iron ions, the chlorine gas generated on the electrolytic anode during the electrolysis process is absorbed by the ferrous ions in the etching working solution and/or the etching waste liquid, further reducing the chlorine gas leakage and improving the safety and controllability of the recycling process. The chlorine gas electrolyzed from copper chloride etching waste liquid can be returned to the original etching liquid system, which can be fully recycled and avoid the increase of treatment cost by harmful chlorine gas emission.

Its regenerative oxidation reaction is: 2Cu ⁺ +Cl ₂ →2Cu ²⁺ +2Cl ^- ; 2Fe ²⁺ +Cl ₂ →2Fe ³⁺ +2Cl ^- .

The present invention can be improved as follows: when an acid copper chloride etching process containing ferric chloride is used, the obtained acidic filter solution is first oxidized in step three, and then it is directly or prepared as a regenerated etching liquid for recycling in the etching production line to effectively improve the stability of the etching working liquid. When an acid copper chloride etching process containing ferric chloride is used, iron ions will also exist in the solution mixed with the copper extractant in step two. Since oxalic acid has reducing properties, part of the trivalent iron ions will be reduced to divalent iron ions during the chemical reaction copper extraction process. According to the test results of the inventor, the reduced trivalent iron ions account for about 20%. At this time, the obtained filter solution is directly used as a regenerated etching solution or is prepared as a regenerated etching solution and reused in the etching production line. Because the regenerated etching solution contains divalent iron ions, it needs to be oxidized in the etching production line to be converted into trivalent iron ions before it can become an etchant to participate in the etching reaction, which brings instability to the etching quality. The oxidant of the obtained acidic filter solution in the oxidation step three is selected in the same range as the oxidant of the cathode electrolyte in the oxidation treatment.

The present invention can be improved as follows: the solid copper salt precipitate obtained in step 3 is preferably cleaned. Since etching waste liquid often contains chloride salt additives (such as ammonium chloride, sodium chloride, ferric chloride, etc.), the solid copper salt precipitate obtained after the first solid-liquid separation will inevitably contain these impurities in addition to residual hydrochloric acid. The specific cleaning method is to use a dilute hydrochloric acid solution or clean water to clean the solid copper salt precipitate once or more to remove the hydrochloric acid in the copper salt precipitate and the chloride salt impurities that can be dissolved in the acid solution or water, thereby improving the purity of the recovered copper salt product.

The present invention can also be improved as follows: a barium source is added to the acidic filter liquid used as the copper extractant for solid-liquid separation after a mixed reaction with the etching waste liquid, etc. to remove sulfate impurities, and only after the impurities are removed can it be reused in the etching production line as a regenerated etching sub-liquid or it can be prepared into a regenerated etching sub-liquid and reused in the etching process. The barium source is at least one of barium chloride, barium carbonate, and barium hydroxide. This is because the oxalic acid products currently available on the market often contain sulfate impurities, and the acidic filter liquid obtained by using oxalic acid as a copper extractant for copper extraction reaction will contain sulfate. If the regenerated etchant containing sulfate impurities is reused in the etching process, a small amount of sulfuric acid will react chemically with the ink or film anti-etching layer on the copper-clad board to dissolve the ink or film, exposing part of the bottom copper originally protected by the ink or film anti-etching layer, which will be corroded into chipping or even disconnection during the etching of the circuit pattern, resulting in quality problems in the etching of the circuit board. Therefore, it is necessary to separate and remove solid barium sulfate impurities from the solution by reacting the sulfate in the acidic filter solution or the regenerated etchant with the barium source.

Preferably, the molar amount of the barium source material added is less than or equal to the chemical reaction molar amount of sulfate contained in the treated solution, thereby avoiding unreacted barium ions remaining in the solution.

The present invention can be improved as follows: during the electrolysis process, a circulating exchange tank is used to circulate and exchange the etching working solution from the copper chloride etching production line with the anodic electrolyte from the anodic area of the electrolytic cell, and the obtained mixed solution is returned to the copper chloride etching production line and the anodic area of the electrolytic cell respectively, so that the etching working solution is oxidized in the anodic area of the electrolytic cell, so as to stabilize the redox potential value of the etching working solution and carry out the chemical reaction of etching. Specifically, the redox potential of the anodic electrolyte after electrolysis is increased by oxidation, and the mixed solution in the circulating exchange tank obtained after mixing with the etching working solution on the copper chloride etching production line has a higher redox potential than the etching working solution on the production line. When the mixed solution enters the etching production line, it can participate in a new copper etching chemical reaction.

From the above explanation, the combination of the electrolytic oxidation regeneration method and the chemical reaction precipitation method for copper extraction has the following three advantages.

1. The present invention uses chemical reaction precipitation to extract copper and then reuses the acidic filter solution in the etching process, thereby realizing the recycling of chlorine compound raw materials in the original etching system.

2. A new type of acidic etching working fluid with high redox potential values containing iron and copper ions can be produced by electrolytic oxidation regeneration, which can not only meet the production quality requirements of 5G high-precision line boards, but also increase production efficiency by 50%.

3. The gas, liquid and solid produced in the recycling process can be recycled, achieving the effect of no additional three wastes, overcoming the problem of wastewater increase in existing recycling technology, and greatly reducing the cost of sewage treatment.

The above three advantages specifically explain and solve the process difficulties existing in the existing acid copper chloride electrolytic recovery process technology.

The second object of the present invention is achieved by the following technical solutions:

A device used in a method for electrolytic regeneration of copper from acidic copper chloride etching waste liquid precipitation includes: an acidic etching production line, an electrolytic cell, an electrolytic cell separator, an anode, a cathode, an electrolytic power source, a copper salt extraction reaction tank and a copper salt extraction solid-liquid separator.

Wherein: the electrolytic cell separator divides the electrolytic cell into an electrolytic cell anode area and an electrolytic cell cathode area, and the anode and cathode are placed in the electrolytic cell anode area and the electrolytic cell cathode area respectively; the electrolytic cell anode area is connected to the etching liquid cylinder of the etching production line through a pipeline, and the top of the electrolytic cell anode area is provided with an exhaust cover plate, and the gas outlet of the exhaust cover plate is connected to a gas drainage pipeline; the etching production line and/or the electrolytic cell anode area and/or the electrolytic cell cathode area are connected to the copper salt extraction reactor through a pipeline provided with a pump, and the copper salt extraction reactor is connected to the copper salt extraction solid-liquid separator by a pipeline.

The anode is an insoluble electrode, and the cathode is an insoluble electrode.

The electrolytic cell separator is a material that can effectively reduce or even prevent cations in the anodic electrolyte from migrating from the anodic region to the cathodic region under the action of an electric field force, and is specifically at least one of an anion exchange membrane, a bipolar membrane, and a reverse osmosis membrane.

The anode preferably includes at least one of conductive graphite, bare metal, a metal electrode coated with an electrolytic anode coating or plated with an inert metal, and a non-metallic object coated with an electrolytic anode coating or plated with an inert metal; the bare metal used for the anode is platinum, gold, or an alloy containing platinum and/or gold. The surface of the anode is coated with an electrolytic anode coating or plated with an inert metal. The metal substrate in the metal electrode is at least one of titanium, platinum, gold, silver, copper, iron, nickel, an alloy containing any of the above metals, and stainless steel. The inert metal used for the anode is at least one of platinum and gold.

The cathode preferably includes at least one of conductive graphite, bare metal, a metal electrode with an inert metal plated on the surface, and a non-metallic object with an inert metal plated on the surface; the bare metal of the cathode is at least one of platinum, gold, copper, and an alloy containing any of the above metals. When the cathode electrolyte does not contain sulfuric acid, the bare metal of the cathode can also be titanium, silver, or a metal containing The metal substrate of the metal electrode whose surface is plated with an inert metal is at least one of titanium, platinum, gold, silver, copper, iron, alloys containing any of the above metals, and stainless steel. The inert metal used for the cathode is platinum and/or gold. When the cathode electrolyte does not contain sulfuric acid, the inert metal used for the cathode can also be titanium or silver.

The present invention can be improved as follows: an etching waste liquid or cathodic electrolysis overflow liquid oxidation tank is added. The etching waste liquid or cathodic electrolysis overflow liquid oxidation tank is connected to the copper salt extraction reaction tank through a pipeline provided with a valve and a pump, so that the etching waste liquid or cathodic electrolysis overflow liquid is oxidized in the etching waste liquid or cathodic electrolysis overflow liquid oxidation tank before copper salt extraction, so as to improve the copper salt yield.

The present invention can be improved as follows: an electrolytic cell cathode region oxidation device is added to oxidize the cathode electrolyte. The electrolytic cell cathode region oxidation device is installed and connected to the cathode electrolysis overflow liquid oxidation tank. The cathode electrolysis overflow liquid oxidation tank is at least one of an oxidant tank connected to a dosing pump pipeline, an oxidant solid dosing device, and a gas-liquid mixing device connected to a gas drainage of an oxidizing gas source.

The present invention can also be improved as follows: an overflow buffer tank is added to collect the overflow of various tanks during the production process and pump the solution according to the process requirements to solve the liquid level problem of the flowing solution. The overflow buffer tank of the cathode area of the electrolytic tank is arranged between the overflow port of the cathode area of the electrolytic tank and the corresponding other tanks. The overflow buffer tank of the anode area of the electrolytic tank is arranged between the overflow port of the anode area of the electrolytic tank and the corresponding other tanks; the overflow buffer tank of the etching working line is arranged between the overflow pipe port of the etching liquid cylinder of the etching production line and the corresponding other tanks.

The present invention can also be improved as follows: an etching waste liquid temporary storage tank is added to temporarily store copper chloride etching waste liquid; the etching waste liquid temporary storage tank is connected to at least one tank of the electrolytic cell anode area, the electrolytic cell cathode area, the etching liquid cylinder on the etching production line, the circulation exchange tank, and the copper salt extraction reaction tank through a pipeline.

The present invention can also be improved as follows: a circulating exchange tank is added, which serves as a mixing exchange reaction center for the anode electrolyte and the etching working solution. The interconnected structure of the mixing pipeline makes the solution mixing efficiency and production safety different.

Preferably, the circulation exchange tank is respectively connected to the etching liquid cylinder and the anode area of the electrolytic cell on the etching production line to form two independent circulation liquid flow loops, so that the etching working liquid from the copper chloride etching production line and the anode electrolyte from the anode area of the electrolytic cell can reach the circulation exchange tank in the shortest time for intersection and mixing under reduced links, and at the same time, the prepared mixed liquid returns to the copper chloride etching production line and returns to the anode area of the electrolytic reaction cell in the shortest response time, so that the redox potential value of the etching working liquid on the copper chloride etching production line quickly converges within the control value range, making the oxidation regeneration process of the etching working liquid safer.

Further preferably, a liquid flow regulating controller is provided on the connecting pipe between the liquid outlet of the circulation exchange tank and the etching liquid cylinder on the etching production line; the liquid flow regulating controller controls the liquid flow through the pipe by adjusting the valve opening of the pipe, or controls the liquid flow of the regulating pipe by turning on or off the pump or changing the speed of the pump motor to control the stability of the redox potential value of the etching working fluid. The liquid flow regulating controller is controlled by the redox potential redox detection device of the etching working fluid on the etching production line. After the etching liquid tank is full of liquid, the etching working liquid drains the overflowed etching waste liquid into the overflow buffer tank through the overflow port, and the solution in the overflow buffer tank is pumped back to the circulation exchange tank for solution mixing or pumped to the etching waste liquid temporary storage tank for temporary storage. The circulation exchange tank is connected to the overflow buffer tank of the anode area of the electrolytic cell through a pipeline. When the solution in the circulation exchange tank is pumped to the anode area of the electrolytic cell by a pump, the full liquid in the anode area of the electrolytic cell overflows into its overflow buffer tank and is then pumped back to the circulation exchange tank by the pump, so that the anode electrolyte containing chlorine can quickly mix and react with the etching working solution to reduce the escape of chlorine.

Furthermore, the circulation exchange tank is connected to at least one of the cathode region of the electrolytic cell, the oxidant tank of the oxidizing device of the cathode region of the electrolytic cell, and the etching waste liquid temporary storage tank through a pipeline.

Furthermore, a vacuum cover is provided at the top of the circulation exchange tank, and the gas outlet of the vacuum cover is connected to at least one of the cathode area of the electrolytic cell, the etching liquid cylinder on the etching production line, the cathode electrolysis overflow liquid oxidation tank, the overflow buffer tank of the cathode area of the electrolytic cell, the etching waste liquid temporary storage tank, the regenerated etching sub-liquid preparation tank, the regenerated etching sub-liquid temporary storage tank or the tail gas absorption liquid tank through a gas drainage pipe.

The present invention can also be improved as follows: a copper salt cleaning tank and a copper salt cleaning solid-liquid separator are added to clean the copper salt precipitate solid and separate the solid and liquid, respectively.

The present invention can also be improved as follows: a regeneration etching liquid preparation tank is added to prepare the regeneration etching liquid using the acidic filter liquid from the copper salt extraction solid-liquid separator; the regeneration etching liquid preparation tank is arranged between the copper salt extraction solid-liquid separator and the regeneration etching liquid temporary storage tank.

The present invention can also be improved as follows: a solution impurity removal tank and an impurity removal solid-liquid separator are added, which are used to chemically react and precipitate the sulfate contained in the acidic filter liquid obtained from the copper salt extraction solid-liquid separator and to perform solid-liquid separation and removal of the precipitated sulfate. The solution impurity removal tank and the impurity removal solid-liquid separator are arranged between the copper salt extraction solid-liquid separator and the regeneration etching sub-liquid temporary storage tank, or between the copper salt extraction solid-liquid separator and the regeneration etching sub-liquid preparation tank, or after the regeneration etching sub-liquid temporary storage tank.

The present invention can also be improved as follows: the gas drainage pipe of the exhaust cover plate at the top of the anode zone of the electrolytic cell is connected to at least one of the anode zone of the electrolytic cell, the cathode zone of the electrolytic cell, the etching liquid cylinder on the etching production line, the cathode electrolysis overflow liquid oxidation tank, the overflow buffer tank of the cathode zone of the electrolytic cell, the overflow buffer tank of the anode zone of the electrolytic cell, the circulation exchange tank, the etching waste liquid temporary storage tank, the regenerated etching sub-liquid preparation tank, and the regenerated etching sub-liquid temporary storage tank.

The present invention can also be improved as follows: at least one of an air pump, a vacuum jet device, and a spray device is added to the gas drainage pipe in the present invention to accelerate the gas-liquid mixing reaction.

The present invention can also be improved as follows: a temporary storage tank for the chemical reaction of the cathode overflow liquid is added to perform a reaction treatment on the cathode overflow liquid by adding alkaline substances or copper extracting agent oxalic acid.

The present invention can also be improved as follows: a detection device is added, and the probe of the detection device is arranged in at least one tank of the etching production line of the circuit board, the anode area of the electrolytic cell, the cathode area of the electrolytic cell, the copper salt extraction reaction tank, the regeneration etching sub-liquid temporary storage tank, the cathode electrolysis overflow liquid oxidation tank, the overflow buffer tank of the cathode area of the electrolytic cell, the circulation exchange tank, the overflow buffer tank of the anode area of the electrolytic cell, the etching waste liquid temporary storage tank, the copper salt cleaning tank, the cathode overflow liquid chemical reaction temporary storage tank, the regeneration etching sub-liquid preparation tank, and the solution impurity removal tank. The detection device includes at least one of a redox potential meter, a photocolorimeter, a densimeter, a thermometer, an acidity meter, a turbidity meter, a pH meter, a liquid level meter, a hydrogen detector, and a chlorine detector. According to the sensor function of the detection device, it is used to detect multiple process parameters such as the redox potential value and/or the colorimetric value and/or the acidity and/or the turbidity and/or the temperature and/or the liquid level and/or the specific gravity value of the solution in the tank, or to detect the concentration content of hydrogen and chlorine in the workshop environment.

The present invention can also be improved as follows: an automatic feeding controller is added, the automatic feeding controller is connected via a data line of the detection device, and its output end is connected to at least one of the pump, valve, liquid flow regulating controller, and electrolytic power supply in the device of the present invention, and the corresponding pump, valve, liquid flow regulating controller, and electrolytic power supply are controlled to perform work through a time program and/or process parameters detected in real time by the detection device.

The present invention can also be improved as follows: a stirring device is added to make the components of the liquid in the tank evenly distributed; the stirring device is arranged in at least one of the anode area of the electrolytic cell, the cathode area of the electrolytic cell, the copper salt extraction reaction tank, the regeneration etching sub-liquid temporary storage tank, the cathode electrolysis overflow liquid oxidation tank, the overflow buffer tank of the cathode area of the electrolytic cell, the circulation exchange tank, the overflow buffer tank of the anode area of the electrolytic cell, the etching waste liquid temporary storage tank, the copper salt cleaning tank, the regeneration etching sub-liquid preparation tank, the cathode overflow liquid chemical reaction temporary storage tank, and the solution impurity removal tank. The stirring device is at least one of a liquid reflux stirring device, an impeller stirring device, and a pneumatic stirring device. The liquid reflux stirring device includes a liquid outlet pipe, a reflux pipe, a controlled pump and/or a valve, and the pneumatic stirring device is a device that can introduce gas into the electrolytic cell to cause the liquid therein to flow. Among them, the copper salt extraction reaction tank and the solution impurity removal tank can both use reaction tanks or reaction tanks with filters; the regeneration etching sub-liquid temporary storage tank, the regeneration etching sub-liquid preparation tank, the cathode electrolysis overflow liquid oxidation tank, the cathode overflow liquid chemical reaction temporary storage tank, the etching waste liquid temporary storage tank, the cleaning waste liquid temporary storage tank, and the tank products for storing production raw materials can all be replaced by universal temporary storage tanks.

The present invention can also be improved as follows: an exhaust gas treatment system is added, the exhaust gas treatment system includes an exhaust hood and an exhaust gas absorption tank, and can further include any one or more of a spray device and a vacuum jet device; the exhaust hood is arranged in the anode area of the electrolytic cell, the cathode area of the electrolytic cell, the copper salt extraction reaction tank, the regeneration etching sub-liquid temporary storage tank, the cathode electrolysis overflow liquid oxygen storage tank, and the exhaust gas treatment system. The tail gas absorption liquid tank is provided at the top of any one or more of the following: a chemical reaction storage tank for cathode overflow liquid, an overflow buffer tank of the cathode zone of the electrolytic cell, a circulating exchange tank, an overflow buffer tank of the anode zone of the electrolytic cell, an overflow buffer tank of the etching production line, a temporary storage tank for etching waste liquid, a copper salt cleaning tank, a regeneration etching sub-liquid preparation tank, and a solution impurity removal tank, and the tail gas absorption liquid tank is filled with tail gas absorption liquid. When the tail gas treatment system only includes an exhaust hood and a tail gas absorption liquid tank, the gas outlet of the exhaust hood is placed in the tail gas absorption liquid tank. When the exhaust gas treatment system further includes a spray device and/or a jet suction device, the air outlet of the exhaust hood is connected to the air intake of the spray device and/or the jet suction device, the liquid inlet of the spray device and/or the jet suction device is connected to the exhaust gas absorption liquid tank, and the liquid outlet of the spray device and/or the jet suction device is connected to the exhaust gas absorption liquid tank and/or inserted in the exhaust gas absorption liquid tank for circulation of the absorption liquid. When the exhaust gas treatment system further includes an air pump, the air pump is arranged on the gas drainage pipe connected to the exhaust hood.

Furthermore, the exhaust gas treatment system is used in multiple stages in series. When the exhaust gas treatment system is used in multiple stages in series, the exhaust hood of the next-stage exhaust gas treatment system is arranged on the top of the exhaust gas absorption liquid tank of the previous-stage exhaust gas treatment system, or the exhaust/gas outlet provided in the exhaust gas absorption liquid tank of the previous-stage exhaust gas treatment system is directly connected to the component originally connected to the exhaust hood outlet in the next-stage exhaust gas treatment system through a pipeline for exhaust gas treatment.

The present invention can also be improved as follows: a hydrogen exhaust system is added to drain and exhaust the hydrogen generated by the electrolytic reaction in the cathode region of the electrolytic cell, thereby avoiding the accumulation of hydrogen and causing safety hazards; the hydrogen exhaust system is arranged on the cathode region of the electrolytic cell for collection and exhaust. The hydrogen exhaust system can adopt a power exhaust system that meets safety requirements, or a simple straight exhaust pipe, and the hydrogen exhaust system can be further provided with a flame arrester.

The present invention can also be improved as follows: a filter is added to remove solid impurities and organic pollutants in the etching working liquid or the etching waste liquid; the filter is arranged on the liquid inlet pipe and/or liquid outlet pipe of the etching waste liquid temporary storage tank and/or the etching production line and/or the electrolytic cell.

The present invention can also be improved as follows: a water-oil separator is added to remove organic oil layer impurities in the etching working fluid or etching waste liquid; the water-oil separator is arranged on the liquid inlet pipe connecting the etching production line outlet pipe and the etching waste liquid tank and the circulation exchange tank.

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

1. The method of the present invention combines electrolytic oxidation to regenerate the etching working solution with a chemical copper extraction method to achieve a waste acid etching solution recycling process without three wastes, which not only reduces environmental pollution but also reduces production costs through recycling.

2. The present invention can reduce or even eliminate the use of external etching oxidants, effectively solving the process problem of increasing the amount of waste liquid produced during the treatment of etching waste liquid in the prior art, and saving the cost of treating the additional waste liquid.

3. The copper salt obtained from the etching waste liquid in the present invention can be directly reused in the bright electroplating production of circuit board copper after purification to reduce the pollution of phosphorus copper.

4. The operation method of the present invention is simple and the process consumes little energy, which is fully in line with the carbon emission reduction policy of the national environmental protection policy.

5. The device structure of the present invention is safe, simple and reliable, with high operational safety and low equipment manufacturing and maintenance costs.

The present invention is further described below through specific embodiments.

The present invention discloses a method for electrolytically regenerating copper by precipitation of waste acid copper chloride etching solution, comprising the following steps:

Step 1: Use an electrolytic cell to oxidize the etching working solution in real time during the etching process. The electrolytic cell is provided with an electrolytic cell separator to divide the electrolytic cell into an electrolytic cell anode area and an electrolytic cell cathode area. The electrolytic cell anode area contains an anode and an anode electrolyte, and the electrolytic cell cathode area contains a cathode and a cathode electrolyte. The anode electrolyte is from an acidic copper chloride etching production line. The etching working solution and/or etching waste solution are recycled, and the anode electrolyte treated by electrolysis is returned to the acid copper chloride etching production line as the regenerated etching working solution. The chlorine gas generated by the anode during the electrolysis process is used to oxidize at least one or a mixture of more than one of the cathode electrolyte, the regenerated etching sub-liquid, the etching working solution, and the etching waste solution. The cathode electrolyte is an electrolyte solution.

Step 2: mixing at least one of the electrolytically treated anodic electrolyte, the electrolytically treated cathodic electrolyte, the oxidized cathodic electrolyte, and the copper chloride etching waste solution, or a mixture of more than one of the above, with a copper extractant, so that copper ions from the copper chloride etching waste solution and/or the copper chloride etching working solution react in the reaction mixture to generate copper salt precipitates.

Step 3: The solid-liquid mixture obtained by the reaction in step 2 is subjected to solid-liquid separation to obtain a solid copper salt precipitate and an acidic filter solution. The obtained acidic filter solution is directly used as a regenerated etching sub-liquid for recycling in the etching process of the etching production line or is prepared as a regenerated etching sub-liquid for recycling in the etching process. The obtained solid copper salt is used as a copper recovery product.

In the following embodiments, the circuit board etching production line used is a product produced by Guangzhou Kejie Circuit Board Equipment Co., Ltd.; the circulating exchange tank, electrolytic cell, reaction tank, filter reaction tank, and temporary storage tank used are all products produced by Foshan Yegao Environmental Protection Equipment Manufacturing Co., Ltd.; the solid-liquid separator, jet suction device, temperature hot and cold exchanger, detection device, valve and pump are all commercially available products. Any circuit board etching production line can be used in conjunction with the process of the present invention. In addition to the above-mentioned, technical personnel in this field can also choose other products with similar performance to the above-mentioned products listed in the present invention according to routine selection to achieve the purpose of the present invention.

In the following embodiments, a device used in a method for electrolytic regeneration of copper from acidic copper chloride etching waste liquid precipitation mainly includes an acidic etching production line, an electrolytic cell, an electrolytic cell separator, an anode, a cathode, an electrolytic power source, a copper salt extraction reaction tank and a copper salt extraction solid-liquid separator, wherein:

The electrolytic cell separator divides the electrolytic cell into an electrolytic cell anode area and an electrolytic cell cathode area, the anode and cathode are placed in the electrolytic cell anode area and the electrolytic cell cathode area respectively, the electrolytic cell anode area is connected to the etching liquid cylinder of the etching production line through a pipeline, the top of the electrolytic cell anode area is provided with a vacuum cover plate, the gas outlet of the vacuum cover plate is connected to a gas drainage pipeline, the etching production line and/or the electrolytic cell anode area and/or the electrolytic cell cathode area are connected to the copper salt extraction reactor through a pipeline provided with a pump, and the copper salt extraction reactor is connected to the copper salt extraction solid-liquid separator by a pipeline;

The anode is an insoluble electrode, and the cathode is an insoluble electrode.

In the following embodiments, the copper salt extraction reaction tank and the solution impurity removal tank can be selected as ordinary reaction tanks or reaction tanks with filters; the regeneration etching sub-liquid temporary storage tank, the regeneration etching sub-liquid preparation tank, the cathode electrolysis overflow liquid oxidation tank, the cathode overflow liquid chemical reaction temporary storage tank, the etching waste liquid temporary storage tank, the cleaning waste liquid temporary storage tank and the tank products for storing production raw materials can all be replaced by universal temporary storage tanks. Each tank product in the specific embodiment is provided with a feeding port and an exhaust port, and valves and pumps are provided on the pipes connecting the tanks. Some pipes are gas drainage pipes, on which air pumps, vacuum jet devices or spray devices are added to accelerate the gas-liquid mixing reaction. The preferred technical scheme of the present invention is specifically described below through embodiments and their corresponding drawings.

Embodiment 1

As shown in FIG1 , a basic embodiment of the present invention is a method and device for electrolytic regeneration of copper by precipitation of acidic copper chloride etching waste liquid. The method comprises a circuit board etching production line 1, an electrolytic cell 3, a reaction tank 19, a solid-liquid separator 49, a regeneration etching liquid preparation tank 26, valves 89 to 92, pumps 116 to 119, and a copper extractor 136, wherein the electrolytic cell separator 169 is an anion exchange membrane.

The acidic copper chloride etching solution used in the etching production line 1 of the circuit board is mainly composed of a mixture of hydrochloric acid and copper chloride, with an acidity of 1.4 mol/L and a copper ion concentration of 200 g/L.

The etching production line 1 pumps the etching liquid from the etching production line 1 to the anode area of the electrolytic cell 3 through the valve 89 and the pipeline of the pump 116. The anode area of the electrolytic cell 3 also pumps the anode electrolyte back to the etching production line 1 through the pipeline containing the pump 117 at the overflow port of the anode area of the electrolytic cell to form an electrolytic regeneration circulation reflux system of the etching working liquid. The detection devices 75, 76, and 77 are respectively an acidity meter, a redox potentiometer, and a hydrometer.

Open valve 89 to start pumps 116 and 117, so that the etching working solution and the anode electrolyte are mixed and circulated. As the etching production is carried out, the line copper plate needs to be added to the etching production line 1, and the electrolytic power supply 13 is turned on to circulate and oxidize the etching work continuously. In addition to the recycled regeneration liquid added to the etching production line, it is necessary to timely add external hydrochloric acid to the etching production line to keep the acidity of the etching working solution stable. When the liquid level of the etching production line 1 reaches a certain height, the etching production line 1 guides the overflowed etching waste liquid into the reaction tank 19 through the etching production line overflow port. The reaction tank 19 is a copper salt extraction reaction tank for copper salt extraction.

The electrolytic cell 3 has an electrolytic cell partition 169 that divides the electrolytic cell into an electrolytic cell anode area and an electrolytic cell cathode area. The anode electrolyte is a solution on the etching production line, and the cathode electrolyte is a mixed solution of hydrochloric acid 137 and acidic filter 180 (mixing ratio 1:15). During the electrolysis process, the cathodic solution undergoes an electrochemical reaction to precipitate hydrogen. The chlorine gas escaping from the anode area of the electrolytic cell is drained to the etching production line through the exhaust port on the electrolytic cell cover 17 (equivalent to the exhaust cover plate of the anode area of the electrolytic cell) to oxidize the etching working solution. During the process, the operator adjusts the current output value of the electrolytic power source 13 or shuts it down according to the value of the detection device 76.

Copper extractant 136 is added to the solution in reaction tank 19, and the solution in reaction tank 19 undergoes a chemical reaction to generate precipitate copper salt 141. The solid-liquid mixture in reaction tank 19 is separated by valve 90, pump 118, and solid-liquid separator 49. The solid-liquid separator 49 is a solid-liquid separator used for copper salt extraction. The filtered liquid obtained after solid-liquid separation is drained into regeneration etching sub-liquid preparation tank 26. Valve 91 is opened, and pump 119 is started according to the value of detection device 75 to pump acidic filtered liquid 180 in regeneration etching sub-liquid preparation tank 26 into etching production line 1 for circulation. The main component of the acidic filtrate 180 is hydrochloric acid solution, and the obtained precipitate copper salt 141 is retained in the solid-liquid separator 49 to be retrieved.

This embodiment is used for the method of electrolyzing and regenerating copper from waste solution of acidic copper chloride etching. The steps are as follows:

1. The etching production working solution is exchanged and mixed with the anode electrolyte, and the etching working solution is electrochemically oxidized through an electrolytic cell to be regenerated and reused in the etching production line.

2. The etching waste liquid overflowing from the etching production line is sent to the reaction tank through a pipeline, and a copper extractant is added to the solution in the reaction tank according to 100% of the amount required to react with the copper ions in the solution, so that the solution undergoes a chemical reaction to generate copper salt precipitation, wherein the copper extractant is a chemical that can form a fixed precipitate with divalent copper ions in a hydrochloric acid solution environment, and in this embodiment, it is oxalic acid.

3. Set up a solid-liquid separator to perform solid-liquid separation on the solid-liquid mixture in the reaction tank to obtain acidic filtrate and copper salt.

4. The obtained acidic filter solution is reused as regenerated etching solution in the etching production line, and the copper salt is collected and reused.

Embodiment 2

As shown in FIG2 , an embodiment of the present invention is a method and device for electrolytic regeneration of copper by precipitation of acidic copper chloride etching waste liquid. The method comprises a circuit board etching production line 1, a circulating exchange tank 2, an electrolytic tank 3, a temporary storage tank 26, i.e., a cathode electrolysis overflow liquid oxidation tank, a temporary storage tank 27, i.e., an etching waste liquid temporary storage tank, reaction tanks 19 and 20, solid-liquid separators 49 to 55, detection devices 75 to 84, copper salt cleaning tanks 139 and 140, valves 89 to 107, pumps 116 to 131, a copper extractant 136, clean water 138, and a sulfate impurity removal agent 167, wherein the electrolytic tank separator 169 is an anion exchange membrane.

The etching production line 1 of the circuit board is equipped with three detection devices 75-77, which are an acidity meter, a hydrometer, and a redox potentiometer. The etching working fluid is a mixed solution mainly including hydrochloric acid, cupric chloride, ammonium chloride, and sodium chloride, with an acidity of 3.5 mol/L and a copper ion concentration of 120 g/L.

The circulation exchange tank 2 and the etching production line 1 are connected through the overflow port 69 of the etching production line 1, the water-oil separator 42, the valve 89, the pump 116, and the pipeline of the solid-liquid separator 49 as a branch flow from the etching production line 1 to the circulation exchange tank 2 and through the valve 90, the liquid flow regulating controller 74, and the pipeline of the solid-liquid separator 50 as a pump to send the liquid from the circulation exchange tank 2 to the branch flow of the etching production line 1 to form a regenerated etching working liquid. The circulation reflux system of the circulation exchange tank 2 and the electrolytic tank 3 is formed by the valve 92 and the pipeline of the pump 118 as a branch flow from the circulation exchange tank 2 to the electrolytic tank anode area and the overflow port 70 of the electrolytic tank anode area, the overflow buffer tank 43, the valve 91, and the pipeline of the pump 111 as a branch flow from the electrolytic tank anode area to the circulation exchange tank 2 to form a circulation reflux system for the etching working liquid to be oxidized. The circulation exchange tank 2 constitutes the mixing and exchange center of the anode electrolyte and the etching working liquid. During the process, the working current of the electrolytic power source 14 is controlled or shut down by the detection device 78, i.e., the redox potentiometer, installed on the circulation exchange tank 2. The detection device 77 of the etching production line 1 controls the liquid flow regulating controller 74 to pump the solution of the circulation exchange tank 2 back to the etching production line 1.

As the etching production proceeds, the etching copper plate needs to be put into the etching production line 1, and the etching production line 1 needs to continuously put in the regenerated etching liquid or external hydrochloric acid. According to the working liquid level of the circulation exchange tank 2, the pump 120 is controlled to start and stop to pump the etching waste liquid overflowed from the etching production line 1 to the temporary storage tank 27, i.e., the etching waste liquid temporary storage tank, for temporary storage.

In order to ensure that the temperature of the etching working solution is constant, a temperature hot-cold exchanger 66 is provided in the circulation exchange tank 2 so that the temperature of the solution added to the etching production line 1 meets the requirements of the etching process.

The anodic electrolyte in the anode area of the electrolytic cell 3 is originally the solution in the circulating exchange tank 2, and the cathodic electrolyte in the cathode area of the electrolytic cell is originally the etching waste liquid. During the electrolysis process, the cathodic solution undergoes an electrochemical reaction to reduce the copper ions from the original divalent to monovalent cuprous ions and electrolyze copper on the cathode. The addition of etching waste liquid to the solution in the cathode area of the electrolytic cell is controlled by a detection device 79, i.e., a hydrometer, to maintain the copper content in the cathodic electrolyte set by the process, so that the cathode electrolysis overflow still contains a certain amount of copper ion concentration to be reacted with oxalic acid for chemical copper extraction. The chlorine gas released from the anode region of the electrolytic cell is led to the jet suction device 38 through the exhaust port 155 on the electrolytic cell cover 17 to mix with the solution in the circulation exchange tank 2 to be used as the oxidation etching working solution and etching waste solution. The gas released from the solution in the cathode region of the electrolytic cell is led to the tail gas absorption liquid tank 34 through the exhaust port 156 for treatment.

The overflow port 71 of the cathode region of the electrolytic cell pumps the overflowed cathode electrolyte into the temporary storage tank 26, i.e., the cathode electrolysis overflow liquid oxidation tank, through the overflow buffer tank 44, the valve 95, the pump 121, and the feeding port 145. The cathode region oxidation device of the electrolytic cell connected to the jet suction device 39 is installed on the tank top of the temporary storage tank 26 to absorb the gas escaping from the circulation exchange tank 2 to oxidize the cathode overflow liquid in the temporary storage tank 26. When there is unabsorbed chlorine in the circulation exchange tank 2, it is introduced into the temporary storage tank 26 to oxidize the cathode electrolyte. The solution is pumped to the reaction tank 19, i.e., the copper salt extraction reaction tank of the present embodiment, through the valve 97, the pump 122, and the pipeline of the feeding port 148.

The reaction tank 19 is equipped with detection devices 81 and 82 and an impeller agitator 59. The detection device 81 is a redox potentiometer to detect the concentration of divalent copper ions, and the detection device 82 is a photoelectric colorimeter and/or an acidity meter and/or a specific gravity meter and/or a liquid level meter to detect its acidity and copper ion concentration and liquid level for control. The liquid in the temporary tank 26 is first pumped into the reaction tank 19 through the valve 97, the pump 122, and the pipeline of the feeding port 148. The concentration of divalent copper ions in the solution in the reaction tank 19 is detected by the detection device 81. If the concentration does not meet the standard, an oxidant 166 (a mixture of sodium perchlorate, potassium perchlorate, sodium chlorite, potassium chlorite, sodium hypochlorite, sodium chlorate, sodium percarbonate and hydrogen peroxide, with the proportion of each component being 1:1:1:1:1:1:1:1) is added to oxidize the monovalent copper metal ions in the solution. After ensuring that the redox potential of the solution is not less than 250 mV, a copper extractant 136, oxalic acid, is added to the solution in the reaction tank 19, and the amount of the copper extractant 136 is set and controlled by the detection device 81 and/or 82. The solution in the reaction tank 19 generates a precipitate copper salt 141 during the reaction process. After the reaction is completed, the valve 100 , the pump 126 , and the solid-liquid separator 51 are opened to pump the acidic filtrate into the temporary storage tank 28 through the feed port 149 , while the precipitate copper salt 141 is retained in the solid-liquid separator 51 .

The solution in the temporary tank 28 is pumped into the reaction tank 20 through the valve 102, the pump 128, and the pipe of the feeding port 150. The detection device 84 and the impeller agitator 60 are installed in the tank, wherein the detection device 84 is a photoelectric colorimeter or a turbidity meter or an acidity meter to detect the light transmittance or acidity of the solution. The reaction tank 20 is a reaction tank dedicated to removing sulfate impurities. The concentration of sulfate in the solution in the reaction tank 20 is detected by the laboratory technician, and the desulfurization impurity agent 167 of the same chemical reaction equivalent is added into the reaction tank 20 through the feeding port 151 to react with the sulfate or sulfuric acid in the solution to generate barium sulfate precipitate. The detection data of the detection device 84 is used as a reference control during the process. The solution containing the barium sulfate precipitate is subjected to solid-liquid separation through the valve 103, the pump 129, and the solid-liquid separator 54. The acidic filtrate is pumped into the temporary storage tank 29 through the feed port 152, while the barium sulfate solid is retained in the solid-liquid separator 54.

The solution in the temporary storage tank 29 is mainly composed of a mixture of hydrochloric acid, cupric chloride, ammonium chloride and sodium chloride. The detection device 75 of the etching production line 1 controls the pump 130 through the valve 104, the pump 130 and the pipeline of the solid-liquid separator 55 to pump the solution in the temporary storage tank 29 back to the circuit board etching production line 1 for recycling. The temporary storage tank 29 is provided with a temperature cold and hot exchanger 67 and an exhaust port 163. In addition, when the production process requires, the detection device 75 sends the detection data to control the addition of external hydrochloric acid to the circuit board etching production line 1.

The copper salt 141 is obtained from the opened solid-liquid separator 51 and put into the copper salt cleaning tank 139. Clean water 138 is put into the copper salt cleaning tank 139 for washing to remove hydrochloric acid and chlorine salt in the copper salt 141. After washing, the solid-liquid separation treatment is performed through the valve 101, the pump 127, and the equipment of the solid-liquid separator 52. The washing waste liquid is discharged to the temporary tank 30 through the valve 105 and the feeding port 153 for temporary storage. The temporary tank 30 is provided with an exhaust port 164. The copper salt 142 is trapped in the solid-liquid separator 52. The copper salt 142 is then put into the copper salt cleaning tank 140 and cleaned with clean water 138. The cleaning liquid is pumped to the solid-liquid separator 53 through the valve 106 and the pipeline of the pump 131. After solid-liquid separation in the solid-liquid separator 53, a relatively pure copper salt 143 is obtained.

The solid-liquid separator 53 is opened to take out the copper salt product 143 to obtain copper oxalate. The filtered liquid after the solid-liquid separator 53 is discharged to the temporary storage tank 30 through the valve 107 and the pipeline of the feeding port 153.

In the process of electrolytic oxidation recovery and recycling, the tail gas C discharged from multiple exhaust ports on the tank, including exhaust ports 156~158 and exhaust ports 160~163, is introduced into the tail gas treatment system for treatment, wherein a detection device 83 is installed in the tail gas absorption liquid tank 34 to control the input of alkaline substances or replace the tank liquid to ensure that the tail gas is effectively absorbed. The solution in the tail gas absorption liquid tank 34 is circulated through the valve 99, the pump 125, and the jet suction device 40, and the tail gas absorption liquid tank 34 is provided with an exhaust port 159.

In this embodiment, a solid-liquid separator 49 is provided on the liquid outlet pipe of the etching production line 1, and a solid-liquid separator 50 is provided on the liquid inlet pipe. A solid-liquid separator 54 is provided on the liquid inlet pipe of the temporary storage tank 29 for regenerating the etching sub-liquid, and a solid-liquid separator 55 is provided on the liquid outlet pipe. The solid-liquid separators 49-50 and the solid-liquid separators 54-55 are used as filters to remove solid impurities and organic pollutants in the etching working liquid or the etching waste liquid. Furthermore, suitable filters can also be provided on the liquid inlet pipe and/or liquid outlet pipe of the etching waste liquid temporary storage tank and the electrolytic cell. The other solid-liquid separators 51-53 are used as copper salt extraction solid-liquid separators.

The characteristics of the electrolytic oxidation regeneration equipment system of this embodiment are: the cathode electrolyte is taken from the etching waste solution in the temporary tank 27, and the pump 124 is controlled to perform addition through the detection device 79, i.e., the hydrometer, in the cathode area of the electrolytic cell. The etching waste liquid enters the cathode area of the electrolytic cell through the valve 98 and the pipeline of the pump 124. The cathode electrolysis overflow liquid in the cathode area of the electrolytic cell is drained into the temporary tank 26 to react with chlorine for oxidation. In the process, by controlling the copper content in the cathode electrolyte, it is possible to recover copper through electrolysis and to make the overflowed cathode electrolyte contain residual copper, which can be collected by the chemical method of oxalic acid. This is a typical process that combines electrolytic copper extraction with chemical copper extraction.

A method for electrolyzing and regenerating copper from waste solution of acidic copper chloride etching. The steps are as follows:

1. Set up a circulating exchange tank to exchange and mix the etching production working solution with the anode electrolyte, so that the etching working solution passes through the electrolytic tank for electrochemical oxidation treatment and is regenerated and reused in the etching production line.

2. Set up acid filter liquid impurity removal equipment, add sulfate impurity removal agent to remove the insoluble sulfate generated by the reaction, and obtain regenerated and reused etching liquid that meets the quality requirements of acid copper chloride etching technology.

3. Set up a filter-belt reaction tank, pump the cathode overflow liquid into the filter-belt reaction tank through a pipeline, adjust the redox potential value of the solution in the tank, and then add copper extractant to the solution in the filter-belt reaction tank at 10% of the amount required to react with the copper ions in the solution, so that the solution undergoes a chemical reaction to generate copper salt precipitation.

4. A solid-liquid separator is set up to perform solid-liquid separation on the solid-liquid mixture in the filter reaction tank to obtain acidic filter liquid and copper salt.

5. Set up copper salt cleaning equipment to remove chloride salt and/or hydrochloric acid during the cleaning process to produce copper oxalate that meets quality requirements.

Embodiment 3

As shown in FIG3 , it is one embodiment of the present invention of a method and device for electrolytic regeneration of copper by precipitation of acidic copper chloride etching waste liquid. It includes a circuit board etching production line 1, a circulation exchange tank 2, an electrolytic tank 3, a temporary storage tank 26, i.e., a cathode electrolyte overflow liquid oxidation tank, a temporary storage tank 27, i.e., an etching waste liquid temporary storage tank, a temporary storage tank 31, i.e., a cathode overflow liquid chemical reaction temporary storage tank, a filter reaction tank 23-24, a solid-liquid separator 49-53, a detection device 75-88, a valve 89-106, a three-way valve 115, a pump 116-134, a copper extractant 136, clean water 138, and a sulfate impurity removal agent 167. Among them, the electrolytic cell separators 169 and 170 are anion exchange membranes, and the electrolytic cell separators 171 and 172 are bipolar membranes.

The circuit board etching production line 1 is equipped with three detection devices 75-77, which are an acidity meter, a hydrometer, and a redox potentiometer. The etching working fluid is an acidic copper chloride etching solution, the main components of which are a mixture of hydrochloric acid and copper chloride, and which also contains an additive of ferric chloride. Its acidity is 0.7 mol/L, the copper ion concentration is 130 g/L, and the iron ion concentration is 7 g/L.

The circulation exchange tank 2 and the etching production line 1 are connected through the overflow port 69 of the etching production line, the overflow buffer tank 43, the valve 89, the pump 116, and the pipeline of the solid-liquid separator 50 as a branch flow from the etching production line 1 to the circulation exchange tank 2, and through the valve 90, the liquid flow regulating controller 74, and the pipeline of the solid-liquid separator 49 as a branch flow pumping the circulation exchange tank 2 to the etching production line 1 to form a liquid circulation between the etching production line 1 and the circulation exchange tank 2. Reflux system: The circulation exchange tank 2 and the electrolytic tank anode regions 5 and 6 of the electrolytic tank 3 are connected through valve 94 and pump 120 as a branch flow from the circulation exchange tank 2 to the electrolytic tank anode regions 5 and 6, and another branch flow from the electrolytic tank anode regions 5 and 6 to the circulation exchange tank 2 through the anode electrolyte overflow pipe 15, overflow buffer tank 44, valve 95, and pump 121. The circulation reflux system of the two tank solutions is formed. The circulation exchange tank 2 is used as a liquid mixing and exchange center for the anode electrolyte and the etching working solution. During the process, the output working current of the electrolytic power source 14 is controlled or shut down by the detection device 78, i.e., the redox potentiometer, and the liquid flow regulating controller 74 is controlled by the detection device 77 to execute the delivery amount of the solution of the circulating exchange tank 2 to the etching production line 1.

As the etching production proceeds, the etching copper plate needs to be put into the etching production line, and the etching production line needs to continuously put in the regenerated etching solution or external hydrochloric acid or a mixture thereof. The volume of the mixed solution of the etching working solution and the anodic electrolyte in the circulating exchange tank 2 will continue to increase. When the circulating exchange tank 2 is full, the pump 117 is controlled to transfer part of the solution in the circulating exchange tank 2 (i.e., the mixed solution of the etching waste solution and the anodic electrolyte that has been electrolytically treated) to the temporary storage tank 27 for temporary storage.

In order to ensure that the temperature of the etching working solution is constant, a temperature hot-cold exchanger 66 is provided in the circulation exchange tank 2 so that the temperature of the solution added to the etching production line meets the requirements of the etching process.

The electrolytic cell 3 has four electrolytic cell partitions 169 to 172 to separate the electrolytic cells 3 and 4 into two electrolytic cell anode areas and one electrolytic cell cathode area, respectively. The tank boxes of the two electrolytic cell anode areas are separated by the electrolytic cell cathode area. The anode electrolyte is originally the solution in the circulating exchange tank 2, and the cathode electrolyte is originally the etching waste liquid. During the electrolysis process, the cathode electrolyte undergoes an electrochemical reaction to reduce the copper ions in the solution from the original divalent cupric ions to monovalent cuprous ions, and the original trivalent iron ions to divalent iron ions. In order to avoid the precipitation of copper metal on the cathode during further electrolysis, the oxidation potential control value is set according to practical experience and controlled by the detection device 79, i.e., the redox potentiometer, in the cathode region of the electrolytic cell. The oxidant 166 (a mixture of potassium chlorate, sodium perchlorate, potassium perchlorate, sodium chlorite, and potassium chlorite, in a mixing ratio of 1:1:1:1:1) is added to the temporary storage tank 26 through the oxidant solid adding device connected to the temporary storage tank 26 to allow the cathode electrolyte to be oxidized. At the same time, a jet suction device 39 is installed on the top of the temporary tank 26 as a gas-liquid mixing device for gas drainage to absorb the chlorine gas escaping from the temporary tank 2, and the chlorine gas is used to oxidize the cathode electrolyte, so that the cathode solution in the cathode region maintains the process conditions of no copper electrolysis. In addition, the acidity meter of the detection device 87 of the cathode region 7 of the electrolytic cell controls the pump 127, so that the etching waste liquid of the temporary tank 27 is added to the cathode region 7 of the electrolytic cell through the valve 101 and the pipeline of the pump 127 to ensure that the acidity of the cathode electrolyte meets the process requirements. The cathode electrolysis overflow liquid circulates back through the overflow port 70 and the overflow buffer tank 45 to the temporary storage tank 26 to undergo oxidation reaction with the oxidant, and is monitored by the detection device 79 during the process.

The anode areas 5 and 6 of the electrolytic cell drain the anode electrolyte into the overflow buffer tank 44 through the anode electrolyte overflow pipe 15 arranged on the electrolytic cell cover 17 and send it to the circulation exchange tank 2 through the pump 121. The exhaust port 155 on the overflow buffer tank 44 drains the gas escaping from the anode electrolyte to the jet suction device 38 to mix the gas and liquid with the solution of the circulation exchange tank 2. At the same time, the solution of the circulation exchange tank 2 is pumped into the overflow buffer tank 44 through the valve 93 and the pump 119 to absorb the chlorine or oxygen in the anode electrolyte.

During the electrolysis process, an oxidant 166 needs to be added to the cathode electrolysis overflow liquid in the temporary storage tank 26. After the oxidant is added cumulatively, when the specific gravity value of the solution in the temporary storage tank 26 detected by the hydrometer of the detection device 80 is greater than the process setting value, the valve 99 is opened and the pump 125 is used to partially discharge part of the solution in the temporary storage tank 26. The liquid level is supplemented by the etching waste liquid in the temporary storage tank 27 through the pump 127 to dilute the salt content of the cathode electrolyte. The part of the solution discharged from the temporary storage tank 26 is introduced into the temporary storage tank 31, i.e., the cathode overflow liquid chemical reaction temporary storage tank for treatment. The impeller agitator 62 is started and sodium hydroxide 179 is added through the control of the detection device 88, i.e., the pH meter, to neutralize the reaction solution in the temporary storage tank 31 and precipitate the precipitate. The solution in the temporary storage tank 31 enters the solid-liquid separator 53 through the valve 106 and the pipeline of the pump 135 to separate the solid-liquid mixture in the temporary storage tank 31. The filter residue copper hydroxide and iron hydroxide are retained in the solid-liquid separator 53. The solid iron hydroxide and copper hydroxide 176 are separated and the iron compound is reused in the etching system; the filter liquid is a sodium chloride solution, i.e., waste brine 178, which is discharged as waste water.

The etching waste liquid in the temporary tank 27 is pumped into the filter-belt reaction tank 23 through the valve 102 and the pipeline of the pump 128. The filter-belt reaction tank 23 is equipped with detection devices 81 and 82 and an impeller agitator 61. The detection device 81 is a redox potentiometer to detect the concentration of divalent copper ions. The detection device 82 is a photoelectric colorimeter and/or an acidity meter and/or a hydrometer and/or a redox potentiometer and a liquid level meter to detect its acidity, copper ion concentration and liquid level. The concentration of divalent copper ions in the solution is detected by the detection device 81. If it does not meet the standard, the oxidant 166 is added to the filter reaction tank 23 to oxidize the copper metal ions in the solution into divalent copper ions, so that the redox potential of the solution is not less than 250mV. After meeting the standard, the copper extractant 136 is added to the solution, and the amount of the copper extractant 136 is controlled by the detection personnel or according to the set value of the detection device 82. The solution in the filter screen reaction tank 23 generates a precipitate copper salt 141 during the reaction process. The acidic filter liquid is pumped to the temporary storage tank 28 through the three-way valve 115, the pump 129, and the pipeline equipment of the solid-liquid separator 51. The precipitate copper salt 141 is retained in the filter screen reaction tank 23, and a small amount of copper salt is also retained in the solid-liquid separator 51.

The solution in the temporary tank 28 is pumped to the filter-belt reaction tank 24 through the valve 103 and the pipeline of the pump 130. The detection device 83 and the impeller agitator 60 are installed in the tank. The detection device 83 is a photoelectric colorimeter or a turbidity meter or an acidity meter to detect the transmittance or acidity of the solution. The filter-belt reaction tank 24 is a reaction tank dedicated to removing sulfate impurities. The sulfate-belt impurity removal agent 167 barium chloride is added to the filter-belt reaction tank 24 to react with the soluble sulfate or sulfuric acid in the solution to generate a barium sulfate precipitate. The solution containing the barium sulfate precipitate is pumped into the temporary storage tank 29 through the valve 104 and the pipeline of the pump 131, while the barium sulfate solid is retained in the filter reaction tank 24.

The solution in the temporary storage tank 29 is mainly composed of a mixture of hydrochloric acid, ferric chloride, ferrous chloride and a small amount of cupric chloride. The detection device 75 in the etching production line 1 controls the pump 132 through the valve 105, the pump 132 and the pipeline of the solid-liquid separator 52 to pump the solution in the temporary storage tank 29 back to the circuit board etching production line 1 for circulation. In addition, when the process control requires, the detection device 75 sends the detection data to add external hydrochloric acid or a mixture of hydrochloric acid and additives to the circuit board etching production line 1 for supplementary use.

The copper salt 141 is still temporarily retained in the belt filter reaction tank 23, and the passage to the pump 129 is closed through the three-way valve 115. The agitator 61 is started to add dilute hydrochloric acid 137 to the belt filter reaction tank 23 for cleaning. After the acid cleaning is completed, the three-way valve 115 is opened to discharge the cleaning waste liquid in the belt filter reaction tank 23 to the temporary storage tank 30 for treatment. Then the three-way valve 115 is closed and clean water 138 is added to the belt filter reaction tank 23 again to wash the copper salt with clean water to obtain copper oxalate. After the cleaning is completed, the three-way valve 115 is continued to be opened to discharge the washing waste water to the temporary storage tank 30.

After cleaning, the tank cover in the filter reaction tank 23 is opened to take out the copper salt product 141.

The tail gas absorption liquid tank 34 and the spray device 37 and the tail gas absorption liquid tank 35 and the jet suction device 40 form a series-connected tail gas treatment system to absorb the tail gas C discharged from multiple tanks. The pH meters of the detection devices 84 and 85 are used to prompt the replacement of the tank liquid so that the tail gas absorption liquid tank 35 can work normally.

The characteristics of the electrolytic oxidation regeneration equipment system of this embodiment are: the cathode electrolyte is taken from the solution in the circulation exchange tank 2, and the detection device 79 is an ORP meter that sets the redox potential control value according to practical experience to control the addition of external oxidant 166 so that the cathode electrolyte meets the process requirement that the cathode does not electrolyze copper metal, that is, the process can be specially designed according to the structure of the electrolytic machine to only oxidize the anode electrolyte and control the cathode not to electrolyze copper metal. The use of an electrolytic machine with this type of structure can reduce the cell pressure and reduce the energy consumption of electrolytic oxidation. The detection device 87 is a hydrometer or an acidometer, preferably an acidometer. After the process control value is set for the acidity meter, when the solution drops to the set value, the pump 127 is started to add the etching waste liquid in the temporary tank 27 to the cathode area of the electrolytic cell to replenish the acid solution, so that the electrolyzer can work normally.

This embodiment uses only a chemical reaction method to produce copper salt as a recovered copper product, and the etching waste liquid production is not increased during the process.

A method for electrolytic regeneration of copper from waste solution of acidic copper chloride etching by precipitation. The steps are as follows:

1. A circulating exchange tank is set up to mix and exchange the etching working solution with the anode electrolyte, so that the copper ion concentration and redox potential of the etching working solution can be stably controlled during the recycling etching production process.

2. Set up a filter-belt reaction tank to pump the oxidized etching waste liquid into the filter-belt reaction tank. After detecting the solution or adjusting the redox potential value, add 40% of the copper extractant required to react with the copper ions in the solution into the solution in the reaction tank to make the solution undergo a chemical reaction to precipitate copper salt. The filter-belt reaction tank is equipped with a filter or filter cloth, which can be used as a copper salt extraction solid-liquid separator to perform solid-liquid separation on the solid-liquid mixture in the tank to obtain acidic filter liquid and copper salt.

3. Set up acidic filter liquid impurity removal equipment, add sulfate impurity removal agent to make the solution react to generate insoluble sulfate for impurity removal, and obtain regenerated etching liquid that meets the technical requirements of acid copper chloride etching process.

4. Set up copper salt cleaning equipment to remove chloride salt and/or hydrochloric acid during the cleaning process and produce copper oxalate products that meet quality requirements.

Embodiment 4

As shown in FIG4 , an embodiment of the present invention is a method and device for electrolytic regeneration of copper by precipitation of acidic copper chloride etching waste liquid. It includes a circuit board etching production line 1, a circulation exchange tank 2, an electrolytic tank 3, temporary tanks 26-32, reaction tanks 19-21, solid-liquid separators 49-55, detection devices 75-87, copper salt cleaning tanks 139-140, valves 89-111, pumps 116-133, copper extractants 136, clean water 138, sulfate impurity removal agents 167, and automatic detection and feeding controllers 168. Among them, the electrolytic tank separator 169 is a reverse osmosis membrane.

The etching production line 1 of the circuit board is equipped with three detection devices 75-77, which are an acidity meter, a hydrometer, and a redox potentiometer. The etching working fluid is an acidic copper chloride etching solution, which is a mixture of mainly hydrochloric acid, copper chloride and ferric chloride. The acidity is 1.0 mol/L, the copper ion concentration is 120 g/L, and the iron ion concentration is 40 g/L.

The circulation exchange tank 2 and the etching production line 1 are connected through the overflow port 69 of the etching production line 1, the overflow buffer tank 43, the valve 89, the pump 116, and the pipeline of the solid-liquid separator 49. The liquid from the etching production line 1 flows to the circulation exchange tank 2, and the other branch flows through the valve 91, the liquid flow control controller 73, and the pipeline of the solid-liquid separator 50 to pump the liquid from the circulation exchange tank 2 to the etching production line 1 so that the two branches form a liquid. The circulation exchange tank 2 and the electrolytic tank anode area 5 of the electrolytic tank 3 are connected through a pipeline of valve 94 and pump 120 as a branch flow from the circulation exchange tank 2 to the electrolytic tank anode area 5, and another branch flow from the electrolytic anode area 5 to the circulation exchange tank 2 is combined through an overflow port 70, an overflow buffer tank 44, a valve 90, and a pump 117 of the electrolytic tank anode area 5 to form a circulation reflux system of the liquid. The circulation exchange tank 2 is formed as a mixing and exchange center for the anode electrolyte and the etching working liquid. The control system uses the automatic detection and feeding controller 168 of PLC for data processing control. During the process, the detection data of the detection device 78, i.e., the redox potentiometer, is used to control the working current size or shut down of the electrolytic power source 14. The data of the detection device 77, i.e., the redox potentiometer, is used to control the amount of solution added from the circulation exchange tank 2 to the etching production line 1 by the liquid flow regulating controller 73. The acidity meter of the detection device 75 controls the addition of regenerated etching liquid or external hydrochloric acid. The hydrometer of the detection device 76 controls the addition of clean water to the etching production line 1.

As the etching production proceeds, the etching copper plate needs to be put into the etching production line 1, and the etching production line 1 needs to continuously put in the regenerated etching liquid or external hydrochloric acid or other liquid. The etching waste liquid overflowed from the etching production line 1 is pumped into the circulation exchange tank 2 by the pump 116 according to the liquid level of the circulation exchange tank 2, or is pumped into the temporary storage tank 26 of the etching waste liquid by the pump 118 for temporary storage.

In order to ensure that the temperature of the etching working solution is constant, a temperature hot-cold exchanger 66 is provided in the circulation exchange tank 2 so that the temperature of the solution added to the etching production line meets the requirements of the etching process.

The electrolytic cell 3 is divided into an electrolytic cell anode area 5 and an electrolytic cell cathode area 7 by a structural electrolytic cell partition 169. The anode electrolyte is a solution pumped in from the circulation exchange tank 2, and the cathode electrolyte is a mixture of hydrochloric acid and sodium chloride (10% hydrochloric acid, 5% sodium chloride). During the electrolysis process, water is mainly electrolyzed according to the properties of the electrolytic cell partition 169, and the anode electrolyte mainly undergoes an oxidation reaction in which divalent iron is oxidized to trivalent iron. The gases released from the anode area of the electrolytic cell are oxidizing gases of chlorine and oxygen. The cathode electrolyte undergoes an electrochemical reaction to release hydrogen. The released hydrogen is directly discharged through the hydrogen exhaust system 174 and the flame arrester 175. In order to avoid the lack of electrolyte in the cathode region 7 of the electrolytic cell during the electrolysis process, the detection device 79 of the cathode region of the electrolytic cell, i.e., the liquid level meter, controls the addition of clean water 138 to maintain the normal electrochemical reaction of the cathode. The gas overflowing from the anode region 5 of the electrolytic cell is guided to the jet suction device 38 through the exhaust port 156 on the electrolytic cell cover 17 and the gas escaping from the overflow buffer tank 44 to mix with the solution in the reaction tank 21 to be absorbed by the regenerated etching sub-liquid reaction.

The valve 95 of the overflow port 71 of the cathode region of the electrolytic cell is closed. A detection device 80, namely a redox potentiometer, is installed in the etching waste liquid in the temporary tank 26 to display the process parameters of the etching waste liquid. When production needs it, the valve 97 is opened and the solution is pumped into the reaction tank 19 through the valve 111 and the pipeline of the pump 123.

The reaction tank 19 is equipped with detection devices 81-82 and an impeller agitator 59. The detection device 81 is a redox potentiometer to detect the concentration of divalent copper ions. The detection device 82 is a photoelectric colorimeter and/or an acidity meter and/or a specific gravity meter and/or a redox potentiometer and a liquid level meter to detect its acidity, copper ion concentration and liquid level for control. The impeller agitator 59 is turned on after the etching waste liquid from the temporary tank 26 is pumped into the reaction tank 19. The concentration of divalent copper ions in the solution is detected by the detection device 81. If it does not meet the standard, the oxidant 166 (chlorine and oxygen, mixed in a ratio of 5:1) is added to oxidize the copper metal ions in the solution so that the redox potential of the solution is not less than 250mV. After meeting the standard, the copper extractant 136 is added to the solution, and the amount of the copper extractant 136 is sent to the automatic detection and feeding controller 168 for processing and setting value control based on the detection data of the detection device 82. The reaction tank 19 is used as a copper salt extraction reaction tank, wherein the solution generates a precipitate copper salt 141 during the reaction process, and the solid-liquid separator 51 is used as a copper salt extraction solid-liquid separator. After the detection value of the detection device 82 reaches the standard, the solid-liquid separation is performed through the valve 101, the pump 125, and the pipeline equipment of the solid-liquid separator 51 after the reaction is completed, and the acidic filter liquid is pumped into the temporary tank 28, and the precipitate copper salt 141 is retained in the solid-liquid separator 51.

The solution in the temporary tank 28 is pumped into the reaction tank 20 through the valve 102 and the pipeline of the pump 128. The detection device 83 and the impeller agitator 60 are installed in the reaction tank 20. The detection device 83 is an acidity meter or a photoelectric colorimeter or a turbidity meter and a liquid level meter to detect the acidity or transmittance of the solution and the liquid level. The reaction tank 20 is a reaction tank dedicated to removing sulfate impurities. The impeller agitator 60 is started and the sulfate impurity removal agent 167, i.e., barium hydroxide, is added into the reaction tank to react with the soluble sulfate or sulfuric acid in the solution to generate a barium sulfate precipitate. After the detection device 83 reaches the standard, the solution containing the barium sulfate precipitate is subjected to solid-liquid separation through the pipeline equipment of the valve 103, the pump 129, and the solid-liquid separator 52. The acidic filtrate is pumped to the temporary tank 29, and the barium sulfate solid is retained in the solid-liquid separator 52.

In order to make the regenerated etching liquid more suitable for use as etching regenerated liquid, the solution in the temporary tank 29 is pumped to the reaction tank 21 through the valve 104 and the pump 130 to react with the oxidant 166 chlorine and oxygen for oxidation. The reaction tank 21 is equipped with a detection device 84 and an impeller agitator 62. The detection device 84 is a redox potentiometer and a liquid level gauge. The top of the tank cover is equipped with a jet suction device 38 to introduce the gas escaping from the circulation exchange tank 2 and the gas escaping from the anode area 5 and the buffer tank 44 of the electrolytic cell into the reaction tank 21 to react with the solution for oxidation to increase the concentration of ferric chloride. When the detection device 84 reaches the process setting, solid-liquid separation is performed through the valve 105, the pump 131 and the solid-liquid separator 53, and the regenerated etching liquid that has been oxidized is pumped to the temporary storage tank 30 for temporary storage, and the impurity solids are trapped in the solid-liquid separator 53.

The solution in the temporary storage tank 30 is mainly composed of a mixture of hydrochloric acid and ferric chloride. By processing the data of the detection device 75 in the etching production line, the automatic detection feed controller 168 opens the valve 106, and the liquid flow control controller 74 pumps the solution in the temporary storage tank 30 as an etching liquid back to the circuit board etching production line 1 for circulation. In addition, external hydrochloric acid can be added to the etching production line 1 according to production needs.

The copper salt 141 is opened and taken out from the solid-liquid separator 51 and put into the copper salt cleaning tank 139. The detection device 85 in the copper salt cleaning tank 139 is a pH meter and a liquid level meter. Clean water 138 is put into the copper salt cleaning tank 139 for washing to remove hydrochloric acid and chlorine salt in the copper salt 141. After washing, the solid-liquid separation treatment is performed through the valve 107, the pump 126, and the pipeline equipment of the solid-liquid separator 54. The washing waste liquid is discharged through the pipeline to the temporary storage tank 31 for temporary storage. The copper salt 142 is trapped in the solid-liquid separator 54.

The solid-liquid separator 54 is opened to take out the copper salt 142 and put it into the copper salt cleaning tank 140. The detection device 86 in the copper salt cleaning tank 140 is a pH meter and a liquid level meter. Clean water 138 is added to clean the copper salt for the second time. After the cleaning is completed, the automatic detection feeding controller 168 opens the valve 108 and starts the pump 127 to perform solid-liquid separation through the solid-liquid separator 55. The cleaning waste liquid is drained to the temporary storage tank 31 for temporary storage, while the copper salt 143 is retained in the solid-liquid separator 55. The solid-liquid separator 55 is opened to take out the copper salt 143, i.e., copper oxalate, and place it in the temporary storage tank 32.

In the electrolytic oxidation recovery and recycling equipment system, the tail gas C discharged from the exhaust ports on multiple tanks is introduced into the tail gas treatment system for treatment, wherein a detection device is installed in the tail gas absorption liquid tank 34 to control the input of alkaline substances or replace the tank liquid.

The characteristics of the electrolytic oxidation regeneration equipment system of this embodiment are: the cathode electrolyte adopts a mixed solution of hydrochloric acid and sodium chloride, and the liquid level is supplemented by adding clean water 138 through the detection device 79, i.e., the liquid level meter. Since the cathode electrolyte does not contain copper ions, the cathode only performs an electrochemical reaction of electrolyzing water to precipitate hydrogen. The precipitated hydrogen is collected and discharged into the air.

A method for electrolytic regeneration of copper from waste solution of acidic copper chloride etching. The steps are as follows:

1. A circulating exchange tank is set up to exchange and mix the etching working solution with the anode electrolyte, so that the copper ion concentration and redox potential of the etching working solution can be stably controlled during the etching production process; at the same time, the etching working solution is electrochemically oxidized through the electrolytic tank for regeneration and reuse. The hydrogen generated in the cathode area of the electrolytic tank is collected and discharged into the air.

2. Set up acid filter liquid impurity removal equipment and oxidation regeneration equipment, add sulfate impurity removal agent to remove the insoluble sulfate generated by the reaction, and then add chlorine and oxygen to the treated liquid to obtain a regenerated etching liquid that meets the requirements of the acid copper chloride etching process.

3. Set up a reaction tank to pump the etching waste liquid into the reaction tank. After reaching the redox potential value, add 80% of the copper extractant required to react with the copper ions in the solution into the reaction tank to make the solution undergo a chemical reaction to synthesize copper salt precipitation.

4. Set up a solid-liquid separator to perform solid-liquid separation on the solid-liquid mixture in the reaction tank to obtain acidic filtrate and copper salt.

5. Set up copper salt cleaning equipment to remove chloride salt and/or hydrochloric acid during the cleaning process to produce copper oxalate that meets quality requirements.

Embodiment 5

As shown in FIG5 , it is an embodiment of a method and device for electrolytic regeneration of copper by precipitation of waste solution from acidic copper chloride etching of the present invention. It mainly includes a circuit board etching production line 1, a circulation exchange tank 2, an electrolytic tank 3, an electrolytic tank 4, a temporary tank 26, i.e., an etching waste liquid temporary tank, reaction tanks 19-21, solid-liquid separators 49-52, detection devices 75-86, an exhaust gas absorption tank 34, a cold and hot temperature exchanger 66-67, an impeller agitator 59-61, a liquid circulation agitator 64-65, a pump 116-133, a copper extractant 136, sodium hydroxide 179, clean water 138, a sulfate impurity removal agent 167, and an automatic detection and feeding controller 168, wherein the electrolytic tank separators 169 and 170 are both anion exchange membranes.

The etching production line 1 of the circuit board is equipped with three detection devices 75-77, which are an acidity meter, a hydrometer, and a redox potentiometer. The etching working solution is an acidic copper chloride etching solution, which is a mixture of hydrochloric acid, copper chloride, ammonium chloride, and ferric chloride, with an acidity of 2.0 mol/L, a copper ion concentration of 80 g/L, an ammonium ion concentration of 10 g/L, and an iron ion concentration of 108 g/L. Among them, the detection device 76 controls the addition of clean water to maintain a constant specific gravity of the etching working solution, that is, it can stabilize the concentration of copper ions and iron ions in the solution.

The etching production line 1 flows into the circulation exchange tank 2 through the overflow port of the etching production line, the water-oil separator 42, and the pipeline of the pump 116. The circulation exchange tank 2 pumps the solution of the circulation exchange tank 2 into the etching production line 1 through the pipeline of the liquid flow regulator 74. The anode electrolytes of the electrolytic cells 3 and 4 are pumped into the circulation exchange tank 2 through the pipelines of the overflow buffer tank 45 and the pump 118 and the pipelines of the overflow buffer tank 43 and the pump 125 for solution mixing; the solution of the circulation exchange tank 2 enters the anode areas 5 and 6 of the electrolytic cell through the pipelines of the pump 117 and the pump 123, respectively, so that the liquid of the etching production line 1 flows into the anode area of the electrolytic cell for oxidation reaction. As the etching production proceeds, the etching copper plate needs to be added to the etching production line 1, and the etching production line 1 needs to continuously add the regenerated etching liquid or the mixture of external hydrochloric acid and additives. When the etching production line 1 is full of liquid, it flows into the water-oil separator 42 through the overflow port and is distributed according to the liquid level of the circulation exchange tank 2. When the liquid level of the circulation exchange tank 2 is lower than the process control height, the pump 116 is started to pump the etching waste liquid into the circulation exchange tank 2, so that the circulation exchange tank 2 constitutes a mixing exchange center for the anode electrolyte and the etching working liquid. When the liquid level in the circulation exchange tank 2 is higher than the control value, the pump 122 is started to pump the overflowed etching waste liquid into the temporary storage tank 26. During the electrolysis process, the output working current of the electrolysis power source 13 and/or 14 is controlled or shut down by the detection device 78, i.e., the ORP meter. The detection device 77 controls the liquid flow regulator 74 to pump the solution in the circulation exchange tank 2 into the etching production line 1 to participate in the etching chemical reaction.

In order to ensure that the temperature of the etching working solution is constant, a temperature hot-cold exchanger 66 is provided in the circulation exchange tank 2 so that the temperature of the solution added to the etching production line meets the requirements of the etching process.

The electrolytic cells 3 and 4 are divided into an anode region and a cathode region by electrolytic cell separators 169 and 170, respectively, and the anode electrolytes are the solutions in the circulating exchange cell 2. The cathode electrolyte of the electrolytic cell 4 is originally the etching waste liquid. During the electrolysis process, the cathode electrolyte of the electrolytic cell 4 undergoes an electrochemical reaction on the cathode to reduce the trivalent iron ions to divalent iron ions, and the copper ions are reduced from the original divalent to monovalent cuprous ions, and even metal copper is electrolyzed. In order to prevent copper from being electrolyzed on the cathode of the electrolytic cell 4, the ORP meter of the detection device 82 controls the addition of etching waste liquid in the temporary storage tank 26 so that the cathode electrolyte of the electrolytic cell 4 maintains a certain redox potential value according to practical experience so that copper is not electrolyzed on the cathode. When there is no etching waste liquid in the temporary storage tank 26, the electrolytic power supply 14 of the electrolytic cell 4 is shut down. In addition, the cathode electrolyte in the cathode area of the electrolytic cell 3 uses etching regeneration liquid that does not contain copper, and the pH meter of the detection device 79 controls the pump 133 to add the regeneration etching liquid of the temporary storage tank 31. The detection device 80 is an ORP meter set according to practical experience to control the oxidant 166 sodium chlorate solution in the temporary storage tank 28 through the pump 121 into the cathode area of the electrolytic cell 3. The cathode does not electrolyze hydrogen. The cathode overflow liquid is pumped into the temporary storage tank 32 through the overflow buffer tank 46 and the pump 119.

The solution in the temporary tank 32 is mainly composed of a mixture of hydrochloric acid, ferric chloride, ammonium chloride, ferrous chloride and potassium chloride. According to the program, the automatic detection and feeding controller 168 issues a command to start the pump 134 to pump the solution in the temporary tank 32 into the reaction tank 19, turn on the impeller stirrer 59, and the pH meter of the detection device 81 of the reaction tank 19 controls the addition of sodium hydroxide 184 to the solution in the reaction tank 19. When the pH meter of the detection device 81 reaches the set process value, the reaction solution in the reaction tank 19 has generated ferric hydroxide and ferrous hydroxide solid precipitates. The impeller agitator 59 is shut down according to program control, and the valve is opened and the pump 120 is turned on to separate the solid-liquid mixture in the reaction tank 19. The ferric hydroxide 177 and ferrous hydroxide 185 are retained in the solid-liquid separator 49 and are later taken out and reused in the preparation of the regenerated etching liquid; the filtered liquid is drained into the temporary storage tank 27. The main component of the filtered liquid is a mixed liquid of sodium chloride, sodium hydroxide and ammonium hydroxide, which is treated as an external waste liquid.

After the cathode area of the electrolytic cell 4 is full of liquid, the liquid overflows from the overflow buffer tank 44 to the temporary storage tank 29. The solution in the temporary storage tank 29 is mainly composed of a mixture of hydrochloric acid, cupric chloride, ferric chloride, ferrous chloride and ammonium chloride. The ratio of ferric chloride to ferrous chloride in the solution is controlled by the ORP meter of the detection device 82. The solution in the temporary storage tank 29 is pumped into the reaction tank 20 by the automatic control pump 127 according to the liquid level. The reaction tank 20 is used as a copper salt extraction reaction tank 20. The ORP meter of the detection device 83, the detection device 84, i.e., the hydrometer and the impeller agitator 60 are installed. The impeller agitator 60 is started and the detection devices 83 and 84 transmit the on-site data to the automatic detection and feeding controller 168 for processing. If the detection device 83 does not meet the standard, the oxidant 166 sodium chlorate solution is controlled to be added. After the standard is met, the copper extracting agent 136 is controlled by the detection device 84, i.e., the hydrometer. When the specific gravity value of the detection device 84 drops to the process setting value, the reaction liquid in the reaction tank 20 produces a solid-liquid mixture of copper oxalate according to the process. The impeller agitator 60 is turned off, and the valve and pump 128 are opened to separate the solid-liquid mixture through the solid-liquid separator 50 for copper salt extraction. The solid slag copper oxalate is retained in the solid-liquid separator 50 for later recycling and treatment; the filtrate is drained into the reaction tank 21. After completion, the valve and pump 128 are closed. The main components of the filtrate are a mixture of hydrochloric acid, ferric chloride, ferrous chloride, ammonium chloride, trace amounts of oxalic acid and sulfuric acid.

The sulfuric acid solution in the reaction tank 21 is treated to remove sulfate impurities. The impeller agitator 61 is started, and the barium hydroxide of the sulfate removal impurity agent 167 is controlled by the automatic detection and feeding controller 168 according to the acidity meter value of the detection device 85. Insoluble barium sulfate is generated during the reaction process. After completion, the impeller agitator 61 is turned off, the valve is opened, and the pump 129 is turned on. The solid-liquid separation is performed on the solid-liquid mixture in the reaction tank 21 through the solid-liquid separator 51. The barium sulfate impurities are trapped in the solid-liquid separator 51, and the filtrate is drained into the temporary storage tank 30. The main components of the filter liquid are a mixture of hydrochloric acid, ferric chloride, ferrous chloride, ammonium chloride, trace amounts of oxalic acid and barium chloride.

A jet suction device 38 is installed on the top of the temporary storage tank 30. The jet suction device acts as a gas-liquid mixing device to attract chlorine gas from the circulation exchange tank 2, the anode area of the electrolytic tank 3, and the anode area of the electrolytic tank 4 into the temporary storage tank 30 to react with the solution in the tank. The chlorine gas removes the trace amount of oxalic acid in the solution through oxidation reaction, and oxidizes ferrous chloride to ferric chloride. When the ORP meter of the detection device 86 in the temporary storage tank 30 reaches the set value, the pump 131 is turned on to pump part of the solution in the temporary storage tank 30 into the temporary storage tank 31 as a regenerated etching liquid to be reused in the etching production line.

After the solution in the temporary storage tank 31 is oxidized by chlorine, its main component is a mixture of hydrochloric acid, ammonium chloride and ferric chloride. The detection device 77 on the etching production line 1 sends data to the automatic detection and feeding controller 168 for processing and controls the pump 132 to add the solution in the temporary storage tank 31 to the etching production line 1, so that all the acidic filter liquid produced in the waste liquid recovery process can be recycled.

The features of the electrolytic oxidation regeneration equipment system of this embodiment are as follows: two electrolytic machines are used. Among them, electrolytic cell 3 is an etching working solution oxidation regeneration machine. Electrolytic cell 4 is used to produce a copper-containing solution with a relatively low concentration of ferric chloride, so that when it reacts with oxalic acid, the oxalic acid loss is reduced due to the small amount of trivalent iron ions contained. Under the process condition that the cathodes of the two electrolytic machines do not electrolyze metallic copper, the anodes of the two electrolytic machines release chlorine to oxidize the etching working solution and oxidize and remove organic impurities in the etching working solution. During the electrolysis process, neither cathode releases copper nor hydrogen.

A method for electrolytic regeneration of copper from waste solution of acidic copper chloride etching by precipitation. The steps are as follows:

1. A circulating exchange tank is set up to exchange and mix the etching production working solution with the two tanks of anode electrolyte, so that the copper ion concentration and redox potential value of the etching working solution can be stably controlled during the etching production process. At the same time, the etching working solution is electrochemically oxidized through the electrolytic tank to be regenerated and reused. During the electrolysis process, the cathode neither releases copper nor hydrogen.

2. A reaction tank is set up to pump the cathode electrolysis overflow liquid of the electrolytic tank 4 to the reaction tank for chemical reaction to extract copper. When the redox potential value of the reaction liquid meets the process requirements, a copper extractant is added to the solution in the reaction tank according to the amount required to react with the copper ions in the solution, so that the solution undergoes a chemical reaction to synthesize copper salt precipitation.

3. Set up a solid-liquid separator to perform solid-liquid separation on the solid-liquid mixture in the reaction tank to obtain acidic filtrate and copper salt.

4. Set up acid filter liquid impurity removal equipment and oxidation regeneration equipment, add sulfate impurity removal agent to generate insoluble sulfate solids in the reaction liquid for removal, and then introduce chlorine gas into the treated liquid for oxidation regeneration treatment to obtain regenerated and recycled etching liquid that meets the quality requirements of acid copper chloride etching technology.

5. The waste liquid recovery process is subject to automated production process control.

Comparison Example 1

The acidic copper chloride etching solution used in the etching production line of circuit boards is mainly composed of a mixture of hydrochloric acid and copper chloride, with an acidity of 1.4 mol/L and a copper ion concentration of 200 g/L.

The etching production line is equipped with an acidity meter, a redox potentiometer and a specific gravity meter. As the etching production proceeds, the circuit copper plate needs to be put into the etching production line 1, and external hydrochloric acid and etching oxidant are put into the etching production line in time to keep the acidity of the etching working solution stable.

Examples 1 to 5 can significantly reduce organic impurities in the etching working solution, as shown in the following table.

Table 1- Oily organic impurities in etching working fluid Oily organic impurities in etching working fluid Embodiment 1 There is slight oiliness, but no accumulation Embodiment 2 There is slight oiliness, but no accumulation Embodiment 3 No oil was observed Embodiment 4 No oil was observed Embodiment 5 No oil was observed Comparison Example 1 There is a clear layer of oil on the surface of the liquid

1: Etching production line 2: Circulation exchange tank 3,4: Electrolyzer 5,6: Anode area of electrolyzer 7,8: Cathode area of electrolyzer 9,10: Anode 11,12: Cathode 13,14: Electrolysis power supply 15: Anode electrolyte overflow pipe 17,18: Electrolyzer cover (exhaust cover) 19~22: Reactor 23,24: Reactor with filter 26~32: Temporary storage tank 34,35: Tail gas absorption tank 37: Spraying device 38~40: Jet suction device 42: Water-oil separator 43~46: Overflow buffer tank 49~55: solid-liquid separator 59~62: impeller agitator 64,65: liquid circulation agitator 66~68: temperature heat exchanger 69~71: overflow port 73,74: liquid flow control controller 75~88: detection device 89~111: valve 115: three-way valve 116~135: pump 136: copper extractor 137: hydrochloric acid 138: clean water 139,140: copper salt cleaning tank 141~143: copper salt 144~153: feeding port 154~164: exhaust port 166: oxidant 167: Sulfate removal agent 168: Automatic detection feed controller 169~172: Electrolytic cell partition 174: Hydrogen exhaust system 175: Flame arrester 176: Copper hydroxide 177: Ferric hydroxide 178: Waste brine 179: Sodium hydroxide 180: Acid filter 184: Sodium chloride 185: Ferrous hydroxide C: Tail gas

FIG1 is a schematic diagram of a basic embodiment of a method for electrolytically regenerating copper from an acidic copper chloride etching waste solution according to Example 1 of the present invention. FIG2 is a schematic diagram of a method for electrolytically regenerating copper from an acidic copper chloride and iron chloride etching waste solution according to Example 2 of the present invention. FIG3 is a schematic diagram of a method for electrolytically regenerating copper from an acidic copper chloride etching waste solution according to Example 3 of the present invention. FIG4 is a schematic diagram of a method for electrolytically regenerating copper from an acidic copper chloride etching waste solution according to Example 4 of the present invention. FIG5 is a schematic diagram of a method for electrolytically regenerating copper from an acidic copper chloride etching waste solution according to Example 5 of the present invention.

1: Etching production line

3: Electrolyzer

9: Yang pole

11: cathode

13:Electrolysis power source

17: Electrolytic cell cover (exhaust cover)

19: Reactor

26: Cache slot

49: Solid-liquid separator

75~77: Detection device

89~92: Valve

116~119: Pumping

136: Copper extractant

137: Hydrochloric acid

141: Copper salt

169: Electrolyzer separator

180: Acidic filter

Claims (14)

A method for electrolytic regeneration of copper from acidic copper chloride etching waste solution precipitation, comprising the following steps: Step 1: using an electrolytic cell to oxidize an etching working solution in real time during the etching process, wherein the etching working solution comprises hydrochloric acid and copper chloride, and an electrolytic cell separator is provided in the electrolytic cell to divide the electrolytic cell into an electrolytic cell anode area and an electrolytic cell cathode area, wherein the electrolytic cell anode area contains an anode and an anode electrolyte, and the electrolytic cell cathode area contains a cathode and a cathode electrolyte. The cathode electrolyte is an etching working solution and/or etching waste solution from an acid copper chloride etching production line. The electrolytically treated anode electrolyte is returned to the acid copper chloride etching production line as a regenerated etching working solution. The chlorine gas generated by the anode during the electrolysis process is used to oxidize the cathode electrolyte, the regenerated etching sub-liquid, the etching working solution, the etching waste solution, and the acidic filter solution obtained in step three. The cathode electrolyte is an electrolyte solution; Step 2: mixing at least one or more of the anode electrolyte treated by electrolysis, the cathode electrolyte treated by electrolysis, the cathode electrolyte treated by oxidation, and the copper chloride etching waste solution with a copper extractant, so that the copper ions from the copper chloride etching waste solution and/or the copper chloride etching working solution are reacted in the reaction mixture. The copper extractant is oxalic acid, and the solid-liquid mixture obtained by the reaction in step 2 is subjected to solid-liquid separation to obtain a solid copper salt precipitate and an acidic filter solution, the solid copper salt obtained is used as a copper recovery product, and the acidic filter solution obtained is directly used as a regenerated etching sub-liquid for recycling in the etching process of the etching production line or as one of the raw materials for the regenerated etching sub-liquid for recycling in the etching process. The method for electrolytic regeneration of copper by precipitation of acidic copper chloride etching waste liquid as described in claim 1, wherein the electrolytic cell separator in step 1 is at least one of an anion exchange membrane, a bipolar membrane, and a reverse osmosis membrane. The method for electrolytic regeneration of copper by precipitation of acidic copper chloride etching waste liquid as described in claim 2, wherein the cathode electrolyte is an aqueous solution of electrolyte, including a hydrochloric acid solution or an acidic solution of a chlorine salt, and the acidic solution of a chlorine salt is a mixed solution of hydrochloric acid and at least one chlorine salt. The method for electrolytic regeneration of copper by precipitation of acidic copper chloride etching waste solution as described in claim 3, wherein the cathode electrolyte is acidic copper chloride etching waste solution and/or iron-containing regeneration etching sub-liquid and/or the iron-containing acidic filter solution obtained in step 3, and the cathode region of the electrolytic cell is provided with an overflow port, and an oxidant is added to the cathode region of the electrolytic cell to carry out an oxidation reaction, and the acidic copper chloride etching waste solution and/or the iron-containing regeneration etching sub-liquid and/or the iron-containing acidic filter solution obtained in step 3 are added to replenish The chlorine ions and acid in the cathodic electrolyte are mixed with alkaline substances or the copper extractant to react with the cathodic electrolyte overflowing from the overflow port of the cathode area of the electrolytic cell so that the copper ions and/or iron ions therein are converted into hydroxides, carbonates or oxalates for precipitation and separation, or the cathodic electrolyte overflowing from the overflow port of the cathode area of the electrolytic cell is subjected to copper extraction treatment by electrolysis, and the solution obtained after the removal of copper ions is prepared for reuse or discharged as waste water. The method for electrolytic regeneration of copper by precipitation of acidic copper chloride etching waste liquid as described in claim 1, wherein both the etching working liquid and the etching waste liquid contain iron ions. The method for electrolytic regeneration of copper by precipitation of acidic copper chloride etching waste liquid as described in claim 5, wherein the redox potential of the cathode electrolyte in the cathode region of the electrolytic cell is not less than 250mV. As described in claim 6, the method for electrolytic regeneration of copper by precipitation of acidic copper chloride etching waste liquid, wherein during the electrolysis process, a circulating exchange tank is used to circulate and exchange the etching working solution from the copper chloride etching production line with the anodic electrolyte from the anodic area of the electrolytic cell, and the obtained mixed solution is returned to the copper chloride etching production line and the anodic area of the electrolytic cell respectively, so that the etching working solution is oxidized in the anodic area of the electrolytic cell. A device for electrolytic regeneration of copper from acidic copper chloride etching waste liquid precipitation, comprising an acidic etching production line, an electrolytic cell, an electrolytic cell separator, an anode, a cathode, an electrolytic power source, a copper salt extraction reaction tank and a copper salt extraction solid-liquid separator, wherein: the electrolytic cell separator divides the electrolytic cell into an electrolytic cell anode area and an electrolytic cell cathode area, the anode and the cathode are placed in the electrolytic cell anode area and the electrolytic cell cathode area respectively, the electrolytic cell anode area is connected to the etching liquid cylinder of the etching production line through a pipeline, and the electrolytic cell separator is used to separate the electrolytic cell into an electrolytic cell anode area and an electrolytic cell cathode area. The top of the anode area of the electrolytic cell is provided with an exhaust cover plate, and the gas outlet of the exhaust cover plate is connected to a gas drainage pipeline. The etching production line and/or the anode area of the electrolytic cell and/or the cathode area of the electrolytic cell are connected to the copper salt extraction reactor through a pipeline provided with a pump, and the copper salt extraction reactor is connected to the copper salt extraction solid-liquid separator by a pipeline; the anode is an insoluble electrode, and the cathode is an insoluble electrode; the electrolytic cell separator is at least one of an anion exchange membrane, a bipolar membrane, and a reverse osmosis membrane. The device used in the method of electrolytic regeneration of copper from acidic copper chloride etching waste liquid precipitation as described in claim 8 also includes an etching waste liquid or cathode electrolysis overflow liquid oxidation tank, and the etching waste liquid or cathode electrolysis overflow liquid oxidation tank is connected to the copper salt extraction reaction tank through a valve and a pump pipeline. The device used in the method for electrolytic regeneration of copper from acidic copper chloride etching waste liquid precipitation as described in claim 9 also includes an electrolytic cell cathode zone oxidation device for oxidizing the cathode electrolyte, the electrolytic cell cathode zone oxidation device is installed and connected to the cathode electrolysis overflow liquid oxidation tank, the cathode electrolysis overflow liquid oxidation tank is connected to at least one of an oxidant tank with a dosing pump pipeline, an oxidant solid dosing device, and a gas-liquid mixing device connected to an oxidizing gas source for gas drainage. The device used in the method of electrolytic regeneration of copper by precipitation of acidic copper chloride etching waste liquid as described in claim 10 also includes a circulating exchange tank, which serves as a mixed exchange reaction center for the anodic electrolyte and the etching working solution. As described in claim 11, the device used in the method for electrolytic regeneration of copper by precipitation of acidic copper chloride etching waste liquid, wherein a liquid flow regulating controller is provided on the connecting pipe between the liquid outlet of the circulation exchange tank and the etching liquid cylinder on the etching production line. The device used in the method of electrolytic regeneration of copper by precipitation of acidic copper chloride etching waste liquid as described in claim 12, wherein the circulating exchange tank is connected to at least one of the cathode area of the electrolytic cell, the oxidant tank of the cathode area oxidation device of the electrolytic cell, and the etching waste liquid temporary storage tank through a pipeline. The device used in the method of electrolytic regeneration of copper by precipitation of acidic copper chloride etching waste liquid as described in claim 13 also includes a cathode overflow liquid chemical reaction temporary storage tank for adding alkaline substances or copper extractants to the cathode overflow liquid in the cathode area of the electrolytic cell.