Method and device for purifying copper oxalate recovered from iron-containing etching waste liquid and treating and recycling purified waste liquid

Abstract

The invention discloses a method and a device for purifying copper oxalate recovered from iron-containing etching waste liquid and treating and recycling the purified waste liquid, which are used for efficiently purifying the iron-containing impurity copper oxalate and realizing the recycling of the purified waste liquid. According to the method, a pickling solution is used for pickling copper oxalate containing iron salt impurities to achieve the effect of removing iron impurities, and copper oxalate obtained after pickling purification and iron-containing pickling waste liquid are obtained after pickling; an electrolytic cell with a cation exchange membrane is arranged, the iron-containing pickling waste liquid is added into an anode cell area to serve as an anode electrolyte and soaks an electrolytic anode, and a cathode electrolyte is added into a cathode cell area and soaks an electrolytic cathode; after an electrolysis power supply is switched on, carrying out electrochemical reaction on the iron-containing pickling waste liquid to remove impurities in the iron-containing pickling waste liquid; the electrochemical reaction process of the anolyte in the anode tank area is detected and controlled according to the standard of the recycled pickling solution set by the process, and the anolyte is used as the pickling solution directly or after being blended after being treated to carry out iron removal pickling on the current batch or another batch of copper oxalate containing iron salt impurities.

Description

Technical Field

[0001] The invention belongs to the technical field of a circuit board acidic iron-containing copper chloride etching waste liquid treatment process, and particularly relates to a method and device for purifying copper oxalate recovered from the iron-containing etching waste liquid and treating and reusing the purified waste liquid. Background Art

[0002] In the existing printed circuit board production process, the acidic iron-containing copper chloride etching process can show better etching performance than the ordinary acidic copper chloride etching process. This is because the main components of the acidic iron-containing copper chloride etching solution used in the acidic iron-containing copper chloride etching process are hydrochloric acid, copper chloride, and ferric chloride, which may also contain a small amount of chloride salt additives such as ammonium chloride, sodium chloride, and potassium chloride. In other words, the acidic iron-containing copper chloride etching solution not only contains the commonly used copper chloride etching agent, but also contains ferric chloride etching agent, and Fe 3+ With Cu 2+ The higher the electrode potential, the better the etching quality and efficiency of copper metal. In addition, the acidic iron-containing copper chloride etching solution has many advantages such as low acidity, less environmental pollution and cheap raw materials.

[0003] During the continuous production of the acidic iron-containing copper chloride etching process, a mixture of hydrochloric acid and ferric chloride, along with a chlorate oxidant, needs to be added to the etching machine to maintain etching production. The added hydrochloric acid and ferric chloride mixture is known in the industry as the etching solution, the copper etching reaction solution in the etching machine is known as the etching working solution, and the solution that overflows from the etching tank is known as the etching waste solution. The main components of the etching waste solution are hydrochloric acid, cupric chloride, ferric chloride, and ferrous chloride.

[0004] Unfortunately, the difficulty in separating the copper and iron during the recycling process of acidic iron-containing copper chloride etching wastewater has hindered its widespread application. However, with the advancement of process technology, the oxalic acid method has finally solved this problem of recycling acidic iron-containing copper chloride etching wastewater, achieving the separation of copper and iron and enabling 100% recycling of the etching wastewater.

[0005] The oxalic acid method is to add oxalic acid to the etching waste liquid to react with the copper chloride therein to produce copper oxalate and hydrochloric acid. The chemical reaction formula is as follows:

[0006] CuCl2+H2C2O4→2HCl+CuC2O4↓

[0007] During the solution reaction, the oxalic acid in the remaining acid solution after the reaction between oxalic acid and cupric chloride will continue to react with FeCl2 to form ferrous oxalate. However, the presence of a large amount of hydrochloric acid in the reaction solution will dissolve the ferrous oxalate. The solid-liquid mixture obtained after the above reaction is subjected to solid-liquid separation to obtain a filter residue of cupric oxalate and an iron-containing acidic filtrate. The iron-containing acidic filtrate mainly consists of hydrochloric acid, ferric chloride, ferrous chloride, cupric chloride, and a small amount of oxalic acid. After treatment and preparation, it can be returned to the etching machine as a regenerated etching sub-liquid for 100% recycling.

[0008] However, because the filter residue copper oxalate is extracted from acidic iron-containing copper chloride etching waste liquid, it is copper oxalate containing iron salt impurities, mainly containing the following impurities: ferric chloride, ferrous chloride, ferrous oxalate, hydrochloric acid, oxalic acid, soluble copper salts, and soluble oxalates. Therefore, the purification process of the filter residue copper oxalate has limited the promotion of the acidic iron-containing copper chloride etching process. For example, traditional water washing methods are not suitable for the purification of copper oxalate containing iron salt impurities, neither can remove iron impurities nor result in high water consumption. For example, the applicant proposed a method for separating electrolyte impurities from water-insoluble compounds in a patent. Specifically, an electrolytic cell with a central cell as the main cell and anode or cathode cell on either side is used as an electrodialysis device. Impurity-containing copper oxalate is placed in the central cell and the impurities are drawn away from the copper oxalate by the electric field force using the electrodialysis principle. The method uses water or a clear solution of a mixture of a water-insoluble compound and water as a washing liquid. Since iron ions easily form iron hydroxide under a neutral environment, it is difficult to purify copper oxalate containing iron salt impurities with water. In addition, the amount of membrane material used in the electrodialysis device is large and the material cost is high. In addition, the distance between the anode and cathode is long, which makes the electrolytic cell voltage high and the power consumption is high. Therefore, it is very necessary to find a method for purifying copper oxalate containing iron impurities and a method for treating and reusing the waste liquid after purification, so as to not only efficiently purify copper oxalate but also solve the pollution problem of the iron-containing pickling waste liquid obtained after purification and the problem of water resource utilization. Summary of the Invention

[0009] The first object of the present invention is to provide a method for purifying copper oxalate recovered from iron-containing etching waste liquid and treating and reusing the purified waste liquid, thereby efficiently purifying the copper oxalate containing iron impurities and recycling the purified waste liquid, thereby improving resource utilization. The second object of the present invention is to provide an apparatus for purifying copper oxalate recovered from iron-containing etching waste liquid and treating and reusing the purified waste liquid, thereby achieving the first object of the invention.

[0010] The purpose of the present invention is achieved through the following technical solutions.

[0011] A method for purifying copper oxalate recovered from iron-containing etching waste liquid and treating and reusing the purified waste liquid, wherein the copper oxalate contains divalent iron salt, trivalent iron salt, copper salt, oxalic acid, and soluble oxalate impurities, comprising the following steps:

[0012] (1) establishing at least one electrolytic cell, wherein the electrolytic cell is divided into an anode cell area and a cathode cell area by a cation exchange membrane, wherein the electrolytic anode in the anode cell area is connected to the positive electrode of the electrolytic power supply, and the electrolytic cathode in the cathode cell area is connected to the negative electrode of the electrolytic power supply;

[0013] (2) pickling the copper oxalate with a pickling solution, and obtaining the copper oxalate and iron-containing pickling waste liquid after pickling purification after solid-liquid separation;

[0014] (3) Adding the iron-containing pickling waste liquid into the anode tank area as the anolyte and soaking the electrolytic anode, adding the catholyte into the cathode tank area and soaking the electrolytic cathode; after the electrolysis power supply is turned on, the iron-containing pickling waste liquid is subjected to an electrochemical reaction, the electrolytic anode electrolyzes oxidizing gas and / or carbon dioxide gas, the iron ions and other cations in the anolyte are enriched in the cathode tank area through the cation exchange membrane under the action of the electric field force, and the electrolytic cathode performs an electrochemical reduction reaction on the catholyte to electrolyze hydrogen and

[0015] / or reduce high-valent metal ions to low-valent metal ions or their metals, while the oxidant produced by electrolysis in the anolyte reacts chemically with the oxalate therein, thereby removing impurities in the iron-containing pickling wastewater;

[0016] (4) The electrochemical reaction process of the anolyte in the anode tank area is detected and controlled according to the recycled pickling liquid standard set by the process. After the treatment is completed, the anolyte is used directly or after being prepared as a pickling liquid to remove iron from this batch or another batch of copper oxalate containing iron salt impurities.

[0017] The present invention utilizes a pickling solution to pickle copper oxalate containing iron salt impurities to achieve the effect of removing iron impurities, and after pickling, copper oxalate and iron-containing pickling waste liquid are obtained after pickling and purification. The main components of the iron-containing pickling waste liquid produced after pickling are dilute hydrochloric acid and / or dilute sulfuric acid, and it contains a mixture of divalent iron salts, trivalent iron salts, copper salts, oxalic acid, and soluble oxalate impurities, so the iron-containing pickling waste liquid can be reused as a pickling solution after electrolytic treatment. The present invention adopts an electrolytic process to perform environmentally friendly treatment of iron-containing pickling waste liquid for iron removal and acid production, adopts the anode tank area of ​​an electrolytic cell with a cation exchange membrane separator as the electrochemical reaction treatment for the iron-containing pickling waste liquid, and thereby produces a dilute acid solution that is circulated back into the pickling tank to continue to perform iron removal pickling on the impurity copper oxalate.

[0018] In step (1), a cation exchange membrane is used as an electrolytic cell separator, which enables the iron ions and other cations in the anolyte to pass through the electrolytic cell separator under the action of the electric field force and be enriched in the cathode electrolyte during the electrolysis operation.

[0019] In step (2), impurities in the copper oxalate are dissolved in the pickling solution, and the copper oxalate is purified by solid-liquid separation.

[0020] In step (3), in order to prevent the iron-containing pickling waste liquid in the anode tank from undergoing a hydrolysis reaction to produce iron hydroxide precipitate, the pH value of the anolyte is required to be less than or equal to pH 4; the catholyte is an electrolyte solution with a pH value less than or equal to pH 4. Preferably, the catholyte is a solution containing at least one of hydrochloric acid, sulfuric acid, pickling solution, and iron-containing pickling waste liquid.

[0021] In step (3), the electrolysis power supply is turned on, allowing the cations (including iron and copper ions) in the anolyte to pass through the electrolytic cell separator under the action of the electric field force and be enriched in the catholyte. The oxalate in the anolyte is oxidized to carbon dioxide, thereby reducing and removing impurities in the iron-containing pickling wastewater. The following main electrochemical reactions occur in the electrolytic cell:

[0022] Anode: 4[OH] - -4e - →2H2O+O2

[0023] or 2Cl - -2e - →Cl2

[0024] C2O4 2- -2e - →2CO2

[0025] Cathode: Fe 3+ +e - →Fe 2+

[0026] or 2 hours + +2e - →H2

[0027] Cu 2+ +2e - →Cu

[0028] In addition, the anolyte undergoes the following chemical reactions during the electrolysis process:

[0029] Cl2+H2O→HCl+HClO

[0030] HClO+H2C2O4→HCl+H2O+2CO2

[0031] As can be seen from the chemical reaction formula above, the pH value of the anolyte decreases continuously during the electrolysis operation, while the catholyte is enriched with cations as the electrolysis reaction progresses and the pH value of the solution continues to rise. Using electrolysis to treat iron-containing pickling wastewater can electrolyze salt substances into acids and hydroxides, which not only replenishes the acidity of the anolyte but also reduces the amount of alkali required for the catholyte to neutralize and precipitate iron ions. Since the iron-containing pickling wastewater contains divalent iron ions, trivalent iron ions, and copper ions, in order to enable the cations in the electrolyte to quickly and efficiently pass through the cation exchange membrane to be enriched in the cathode tank area, it is preferred that the voltage output value of the electrolytic power supply be selected to be greater than or equal to the electrolytic decomposition voltage value of the electrolyte in the electrolytic cell.

[0032] The electrolytic decomposition voltage of the electrolyte in the electrolytic cell is the voltage applied by the electrolytic power supply to the anode and cathode to enable the electrolyte to undergo an electrochemical reaction. In the process of the present invention, the voltage output by the electrolytic power supply when the cathode just electrolyzes hydrogen or copper is the electrolytic decomposition voltage of the electrolyte. This electrolytic decomposition voltage is related to a variety of factors, such as the structure of the electrocatalytic gas-liquid reaction cell, the electrode material, the distance between the two electrodes, the area and structure of the electrodes immersed in the current, the composition and concentration of the electrolyte, the viscosity of the electrolyte reaction, and the temperature. Therefore, the electrolytic decomposition voltage obtained by combining electrolytic cells of different structures with different electrolytes will vary. Under the premise that the electrolytic cell structure and the composition and concentration of the electrolyte remain unchanged, the electrolytic decomposition voltage will be a stable voltage value.

[0033] In step (4), the process setting of the reuse pickling solution standard is determined according to the respective use requirements, specifically by using the iron ion concentration parameter and / or acidity and / or pH value parameter in the anolyte to measure. When the test result of the anolyte reaches at least one parameter value required in the process setting of the reuse pickling solution standard, it can be regarded that the anolyte has reached the process treatment standard for the reuse acid solution, and the solution can be directly or after being prepared and returned to the pickling tank to continue pickling the copper oxalate containing iron salt impurities.

[0034] In step (2), a solution containing at least one of sulfuric acid, hydrochloric acid, and recycled pickling solution having a pH of 4 or below is used as the pickling solution. Preferably, a pickling solution having a pH of 2 or below is selected to prevent the hydrolysis of iron salt impurities to form iron hydroxide precipitates that mix with the copper oxalate solids and are difficult to remove.

[0035] The present invention can be improved as follows: during pickling of copper oxalate, hydrogen peroxide is added to the pickling solution to oxidize the ferrous ion impurities in the copper oxalate to ferric ions, thereby reducing the formation of insoluble ferrous oxalate during pickling. Furthermore, the invention utilizes the weak reactivity of hydrogen peroxide with oxalic acid at room temperature to reduce oxidative damage to the copper oxalate product.

[0036] The present invention can also be improved as follows: when pickling copper oxalate, ultrasonic waves are added to the pickling solution for auxiliary stirring and cleaning, so that the iron salt wrapped by the copper oxalate is quickly dissolved in the pickling solution.

[0037] The present invention can also be improved as follows: the iron-containing pickling waste liquid obtained after solid-liquid separation of the solid-liquid mixture obtained by pickling copper oxalate still contains trace amounts of insoluble copper oxalate solids; if the separated iron-containing pickling waste liquid is directly put into the anode tank area of ​​an electrolytic cell for electrolytic treatment, trace amounts of insoluble copper oxalate will stick to the cation exchange membrane and block the micropores in the membrane, so the iron-containing pickling waste liquid after solid-liquid separation needs to be oxidized to remove the insoluble copper oxalate. The specific method is to add at least one of chlorate, perchlorate, persulfate, and hydrogen peroxide to the iron-containing pickling waste liquid after solid-liquid separation to react so that the insoluble copper oxalate is eliminated. Preferably, the reaction solution is heat-treated during the oxidation reaction to increase the oxidation reaction rate.

[0038] The present invention can also be improved as follows: during the electrolytic treatment of the iron-containing pickling wastewater in the anode tank of the electrolytic cell, an acidity meter and / or a pH meter are used to monitor the acidity of the anolyte. Preferably, a photoelectric colorimeter and / or a hydrometer are added to monitor the iron ion and / or copper ion concentration in the anolyte, thereby achieving production automation and data standardization during the treatment of the iron-containing pickling wastewater.

[0039] The present invention can also be improved as follows: the cathode electrolyte in the electrolytic cell becomes an iron-containing acid solution after electrolytic treatment, and its iron ion concentration becomes increasingly higher as production progresses and needs to be treated. Therefore, the cathode electrolyte discharged from the electrolytic cell is neutralized to cause part or all of the iron and / or copper in the solution to precipitate, and after treatment, the filter residue iron hydroxide and a trace amount of copper hydroxide in the solution are collected, and the filtrate is tested and discharged after meeting the standards or is prepared as a recycled pickling solution for use.

[0040] The present invention can also be improved as follows: in order to prevent the catholyte in the electrolytic cell from undergoing a hydrolysis reaction of iron salts and copper salts to precipitate iron hydroxide and / or copper hydroxide, sulfuric acid and / or hydrochloric acid and / or pickling solution and / or recycled pickling solution are independently added to the cathode cell area to ensure that the catholyte in the electrolytic cell does not generate iron hydroxide and / or copper hydroxide precipitates.

[0041] The present invention can also be improved as follows: copper oxalate that has been pickled and still contains trace amounts of iron salts and acid impurities is washed with water, and pure copper oxalate is produced after the pickling and water washing processes. Preferably, the waste liquid obtained from the water washing is used as the tail liquid to be treated, and after neutralization treatment to remove heavy metal hydroxide precipitates, it is discharged in compliance with standards or prepared as recycled pickling liquid for reuse. Preferably, the copper oxalate is pickled and washed with water twice or more to produce a copper oxalate product of higher purity.

[0042] The present invention also provides a device for purifying copper oxalate recovered from iron-containing etching waste liquid and treating and reusing the purified waste liquid, which is characterized by comprising at least one pickling tank, at least one solid-liquid separator, and at least one electrolytic cell.

[0043] The cell body material in the electrolytic cell is a corrosion-resistant material that is a poor conductor of electricity, and is separated into anode and cathode cell areas with a cation exchange membrane; wherein the electrolytic anode material is at least one of gold, platinum, conductive graphite, titanium-based coated insoluble anode, and titanium, and the electrolytic anode is connected to the positive electrode of the electrolytic power supply; the electrolytic cathode material is at least one of gold, platinum, conductive graphite, copper, titanium, and stainless steel, and the electrolytic cathode is connected to the negative electrode of the electrolytic power supply.

[0044] The pickling tank is made of corrosion-resistant material and is used for pickling or washing copper oxalate containing impurities. It is connected to the solid-liquid separator, overflow buffer tank, temporary storage tank and electrolytic tank by pipeline.

[0045] The solid-liquid separator is used to separate the solid-liquid mixture. It can be divided into a filter, a centrifuge, and a filter press according to its structure. The solid-liquid separator is connected to the electrolytic cell, the pickling tank, the chemical reaction tank, the waste liquid storage tank, the temporary storage tank, and the overflow buffer tank by pipelines.

[0046] The present invention can also be improved by adding sensors to detect and control the electrolysis process of the iron-containing pickling wastewater. The sensors include a pH meter, a photoelectric colorimeter, an oxidation-reduction potentiometer (ORP meter), a hydrometer, a liquid level gauge, and a thermometer. The pH meter is preferably a chemical titration-type pH meter. The sensors are mounted on a tank or pipe that can contact the liquid being measured.

[0047] Preferably, a hydrogen concentration detector and / or a chlorine concentration detector is installed in the workplace to ensure that the production workshop meets national safety and environmental protection standards.

[0048] The present invention can also be improved as follows: an automatic detection controller is added to enable automatic operation and standardized production management to be achieved during the treatment of the iron-containing pickling waste liquid.

[0049] The present invention can also be improved as follows: an agitator is added to the tank containing the reaction liquid, specifically a liquid flow pump pipe agitator and / or an impeller agitator is added, so that the concentration and temperature of the reaction liquid can be uniformed through stirring, making the chemical reaction safe and efficient.

[0050] The present invention can also be improved as follows: an ultrasonic oscillating stirrer is added to the pickling tank to accelerate the dissolution of the iron salt impurities wrapped by the copper oxalate in the pickling solution by the effect of ultrasound. The ultrasonic oscillating stirrer is installed on the pickling tank or on the liquid flow pipeline of the liquid flow pump pipe stirrer connected to the pickling tank.

[0051] The present invention can also be improved by adding a chemical reaction tank for performing an oxidation reaction on the iron-containing pickling wastewater to remove insoluble oxalates therein to prevent clogging of the electrolytic cell partitions, or for use in chemical reactions of other solutions. The chemical reaction tank is connected by a pipeline to the wastewater storage tank, the solid-liquid separator, the electrolytic cell with a cation exchange membrane, the temporary storage tank, or the overflow buffer tank.

[0052] The present invention can also be improved as follows: a hot and cold temperature exchanger is added to enable the temperature of the reaction solution to be regulated according to the process requirements. Specifically, the hot and cold temperature exchanger is installed on the solution tank that needs to be temperature regulated or on the pipeline through which the solution flows.

[0053] The present invention can also be improved as follows: an overflow buffer tank is added to solve the problem of solution flow between tanks. The overflow buffer tank is connected to the waste liquid storage tank, temporary storage tank, electrolytic tank with cation exchange membrane, chemical reaction tank, and solid-liquid separator by pipeline.

[0054] The present invention can also be improved by adding an environmentally friendly tail gas treatment tank for environmentally friendly treatment of the escaped acidic waste gas. The environmentally friendly tail gas treatment tank is provided with a gas-liquid mixer, whose air intake pipe is connected to the pipe for escaping acidic waste gas, and the gas-liquid mixer is a vacuum ejector and / or a spray tower.

[0055] The present invention can also be improved as follows: a hydrogen high-altitude discharge pipe is added to solve the production safety problem of hydrogen evolution at the cathode of the electrolytic cell. The hydrogen high-altitude discharge pipe is connected to the gas escaping pipe in the cathode tank area of ​​the electrolytic cell.

[0056] The present invention can also be improved as follows: an electrolytic cell gas collecting tank cover is added, which is installed on the anode tank area and / or cathode tank area of ​​the electrolytic cell with a cation exchange membrane to collect gas escaping from the reaction liquid in the anode tank area and / or cathode tank area.

[0057] The present invention can also be improved as follows: increasing the specific surface area of ​​the electrolytic anode, specifically using a multi-piece or coiled wire or honeycomb through-hole electrolytic anode structure to accelerate collision oxidation to eliminate oxalate C2O4 2- The reaction releases the iron and copper ions in the oxalate of the reaction solution and allows them to pass through the electrolytic cell partition to be enriched in the cathode tank area, thereby accelerating the chemical reaction of removing iron and producing acid in the anode electrolyte.

[0058] The present invention can also be improved as follows: a temporary storage tank is added to temporarily store raw materials or materials produced by reactions during the production process; it is connected to the pickling tank, the cationic membrane electrolytic tank, the solid-liquid separator, the overflow buffer tank, the chemical reaction tank, and the tail gas environmental protection treatment tank by pipelines.

[0059] Compared with the prior art, the present invention has the following beneficial effects:

[0060] 1. The present invention uses pickling to efficiently purify copper oxalate. The iron-containing pickling wastewater is then electrolyzed to efficiently remove iron and produce acid, allowing the wastewater to be recycled. Compared to existing electrodialysis methods for purifying copper oxalate, the present invention effectively purifies copper oxalate containing iron salt impurities, uses less membrane material, and offers high economic benefits.

[0061] 2. Recycling the iron-containing pickling waste liquid after environmental protection treatment can reduce the use of production water resources and raw materials, thereby reducing costs.

[0062] 3. The process of the present invention is safe and controllable, simple to operate, and requires little equipment investment, and meets the environmental protection process standard requirements of energy conservation and emission reduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] Figure 1 This is a schematic diagram of the structure of a device for purifying copper oxalate recovered from iron-containing etching waste liquid and treating and reusing the purified waste liquid in Example 1.

[0064] Figure 2 Schematic diagram of the structure of the device for purifying copper oxalate recovered from iron-containing etching waste liquid and treating and recycling the purified waste liquid in Example 2 Figure 2 .

[0065] Figure 3 This is a schematic diagram of the structure of the device for purifying copper oxalate recovered from iron-containing etching waste liquid and treating and reusing the purified waste liquid in Example 3.

[0066] Reference numerals

[0067] 1-electrolytic cell, 2-electrolytic anode, 3-electrolytic cathode, 4-cation exchange membrane, 5-electrolytic power supply, 6-anolyte, 7-cathode electrolyte, 8-electrolytic cell gas collecting tank cover, 9-sensor, 10-automatic detection and feeding controller, 11-pickling tank, 12-temporary storage tank, 13-chemical reaction tank, 14-hot and cold temperature exchanger, 15-overflow buffer tank, 16-exhaust environmental protection treatment tank, 17-vacuum ejector, 18-spray tower, 19-hydrogen high altitude discharge pipe, 20-solid-liquid separator, 21-copper oxalate containing iron salt impurities, 22-has Copper oxalate that still contains trace iron salts and acid impurities after iron removal treatment, 23-pure copper oxalate, 24-iron-containing pickling wastewater, 25-hydrochloric acid, 26-sulphuric acid, 27-alkaline solution, 28-recycled pickling solution, 29-fluid pump and agitator, 30-impeller agitator, 31-pure water, 32-untreated tail liquid, 33-hydrogen, 34-oxidant, 35-standard effluent solution, 36-valve, 37-pump, 38-metal copper, 39-pickling solution, 40-ultrasonic oscillating agitator, 41-hydrogen concentration detector, 42-chlorine concentration detector. In the drawings and the following examples, "reference numerals" indicate the use of the same type of substance or component in multiple locations within a device. For example, "electrolytic cell 1-1" refers to one electrolytic cell, and "electrolytic cell 1-2" refers to the second electrolytic cell. DETAILED DESCRIPTION

[0068] The present invention will be further described below through specific embodiments.

[0069] The cation exchange membrane electrolytic cell, temporary storage tank, chemical reaction tank, pickling tank, exhaust gas environmental treatment tank, and overflow buffer tank described herein are all manufactured by Yegao Environmental Protection Equipment Manufacturing Co., Ltd. in Foshan, Guangdong Province. The sensors, automatic detection and feeding controller, pumps, valves, solid-liquid separators, and chemical raw materials are all commercially available products. In addition to the above, those skilled in the art may also select other products with similar performance to those listed above, and any of these products can achieve the objectives of the present invention.

[0070] Example 1

[0071] Example 1 uses Figure 1 The device shown includes a 100-liter electrolytic tank 1, a pickling tank 11, a temporary storage tank 12, a solid-liquid separator 20, an impeller stirrer 30, a pump, and a valve.

[0072] The electrolytic cell 1 is divided into a 50-liter anode tank section and a 50-liter cathode tank section by a cation exchange membrane 4. The anode and cathode sections are topped with electrolytic cell gas collecting tank covers 8-1 and 8-2, respectively. The electrolytic anode 2 is platinum, and the electrolytic cathode 3 is conductive graphite. The pickling tank 11 is connected to the anode tank section via a solid-liquid separator 20. The liquid outlet of the anode tank section is connected to a temporary storage tank 12, which is connected to the pickling tank 11 via a pipeline. The solid-liquid separator 20 is a filter.

[0073] The iron-containing pickling waste liquid 24 in this embodiment comes from the iron-containing pickling waste liquid 24 produced by pickling copper oxalate 21 containing iron salt impurities in the pickling tank 11 using pickling liquid 39. The main components of this waste liquid are sulfuric acid, hydrochloric acid, ferric sulfate, ferric chloride, copper chloride, copper sulfate and oxalic acid; the total iron ion concentration is 2.5 g / L, the total copper ion concentration is 4.7 g / L, the oxalate concentration is 3.69 g / L, and the acidity is 0.62 M / L.

[0074] The cathode electrolyte is an acid wash solution 39. The acid wash solution 39 is 0.5M / L dilute sulfuric acid.

[0075] The weight of the copper oxalate 21 containing iron salt impurities in the pickling tank for pickling each time is 10 kilograms.

[0076] The electrolytic decomposition voltage value of the electrolyte in the electrolytic cell 1 of this embodiment is 0.8V.

[0077] The steps for purifying the copper oxalate recovered from the iron-containing etching waste liquid and treating and reusing the purified waste liquid are as follows:

[0078] 1. Add pickling solution 39 and 10 kg of copper oxalate 21 containing iron salt impurities into the pickling tank, start the impeller stirrer 30 to stir and pickle for 60 minutes.

[0079] 2. Start pump 37-1 to separate the reactants in the pickling tank 11 into solid-liquid form through the solid-liquid separator 20. The copper oxalate 22, which has been treated for iron removal but still contains trace amounts of iron salts and acid impurities, is retained in the solid-liquid separator 20. The iron-containing pickling wastewater 24 is drained into the anode tank area and soaks the electrolytic anodes.

[0080] 3. Add pickling solution 39 to the cathode tank area and soak the electrolytic cathode.

[0081] 4. Turn on the electrolysis power supply and adjust its operating voltage to 0.8V to cause an oxidation reaction in the anolyte. The copper ions, iron ions and hydrogen ions in the anolyte are affected by the electric field force and pass through the cation exchange membrane 4 to be enriched in the cathode tank area. Oxygen, chlorine and carbon dioxide escape from the anode tank area. A small amount of hydrogen escapes from the catholyte and the copper and trivalent iron ions on the cathode electrolysis undergo an electrochemical reduction reaction on the electrolysis cathode to generate divalent iron ions.

[0082] 5. After 180 minutes of electrolytic iron removal and acid production, when an anolyte having an iron ion concentration of 0.9 g / L and an acidity of 0.83 M / L is obtained, sampling and testing are performed to confirm that the results meet the process requirements of a recycled pickling solution of an iron ion concentration of 1 g / L and an acidity of 0.5 M / L. The electrolytic power supply is shut down, and the anolyte is extracted into a temporary storage tank 12 as a recycled pickling solution 28 for standby use. The copper oxalate 22 in the solid-liquid separator 20, which has been iron-removed but still contains trace iron salts and acid impurities, is collected.

[0083] 6. Add a second batch of 10 kg of copper oxalate 21 containing iron salt impurities into the pickling tank 11 and start pump 37-3 to add recycled pickling liquid 28. Replenish pickling liquid 39 to make the pickling tank 11 reach the process required liquid level and continue the pickling operation.

[0084] 7. Collect the washed copper oxalate product.

[0085] Example 2

[0086] Example 2 uses Figure 2 The device shown includes a 100-liter electrolytic cell 1, two electrolytic cell gas collecting tank covers 8, multiple sensors 9, two pickling tanks 11, seven temporary storage tanks 12, an oxidation reaction tank 13, a hot and cold temperature exchanger 14, an overflow buffer tank 15, an exhaust gas environmental protection treatment tank 16, a hydrogen high-altitude discharge pipe 19, four solid-liquid separators 20, three liquid flow pump pipe agitators 29, two impeller agitators 30, an ultrasonic oscillation agitator 40, and multiple pumps and valves.

[0087] The electrolytic cell 1 is divided into a 50-liter anode cell area and a 50-liter cathode cell area by a cation exchange membrane 4. The tops of the anode cell area and the cathode cell area are respectively provided with electrolytic cell gas collecting tank covers 8-1 and 8-2, as well as liquid flow pump tube agitators 29-2 and 29-3. The electrolytic anode 2 is composed of multiple pieces of titanium-based insoluble anodes, and the electrolytic cathode is composed of a stainless steel plate 3-1 and a titanium plate 3-2.

[0088] The pickling tank 11-1 is equipped with an ultrasonic oscillating agitator 40 and an impeller agitator 30-1. It is connected to solid-liquid separators 20-1 and 20-2 by pipes, and then to chemical reaction tank 13 via temporary storage tank 12-2. Chemical reaction tank 13 is connected to the anode tank area of ​​electrolytic cell 1 via temporary storage tank 12-3. Pickling tank 11-2 is used to wash copper oxalate 22 that has been deironed but still contains trace iron salts and acid impurities. It is connected to solid-liquid separator 20-3 and leads to temporary storage tank 12-5.

[0089] The liquid outlet of the anode tank area of ​​the electrolytic cell 1 is connected to the pickling tank 11-1 through the temporary storage tank 12-4; the liquid outlet of the cathode tank area leads to the temporary storage tank 12-5.

[0090] The solid-liquid separator 20-1 is a filter press for performing solid-liquid separation on the reactants in the pickling tank 11-1; the solid-liquid separator 20-2 is a filter for fine filtering the filtrate from the filter press 20-1; and the solid-liquid separator 20-3 is a centrifuge for separating the pure copper oxalate 23 in the pickling tank 11-2 from the solution.

[0091] The tail gas environmental protection treatment tank 16 is provided with a spray tower, and the air intake pipe is connected to the pipe for escaping acid waste gas.

[0092] The pickling liquid 39 used in this embodiment is dilute hydrochloric acid with a pH of 3; the treated iron-containing pickling waste liquid 24 comes from the waste liquid produced by pickling copper oxalate, which contains iron salt impurities. Its main components are hydrochloric acid, a small amount of ferric chloride, copper chloride, ammonium chloride and trace amounts of oxalic acid and copper oxalate, wherein the iron ion concentration is 1.2 g / L, the copper ion concentration is 3.1 g / L, the oxalate ion concentration is 1.46 g / L, and its pH value is pH 2.2.

[0093] The starting solution of the catholyte in the electrolytic cell 1 is dilute hydrochloric acid with a pH of 3. After electrolysis, the acid is concentrated in the cathode tank area to form a ferrous chloride solution. The acidity of the dilute hydrochloric acid catholyte 7 is controlled to be pH 4.

[0094] The oxidant 34-1 is hydrogen peroxide, and 34-2 is sodium chlorate.

[0095] The alkaline solution 27 is a 10% sodium hydroxide solution.

[0096] Sensors 9-1 are a level gauge, 9-2 an ORP meter, 9-3 a level gauge, 9-4 a thermometer, 9-5 an ORP meter, 9-6 a photoelectric colorimeter, 9-7 a level gauge, 9-8 a pH meter, 9-9 a pH meter, and 9-10 a level gauge. The photoelectric colorimeter is used to detect the iron ion concentration in the solution, the pH meter is used to detect the pH value of the anolyte, and the pH meter is used to detect the acidity of the catholyte and control pump 37-9 to add hydrochloric acid to the cathode tank to maintain its acidity. Sensors 9-1 and 9-2 are located in the pickling tank 11-1, sensors 9-3, 9-4, and 9-5 are located in the chemical reaction tank 13, sensors 9-6, 9-7, and 9-8 are located in the anode tank, sensor 9-9 is located in the cathode tank, and sensor 9-10 is located in the pickling tank 11-2.

[0097] The sensors 9-11 are hydrogen concentration detectors, and 9-12 are chlorine concentration detectors, which are used to detect the safety environment of the workplace.

[0098] The electrolytic decomposition voltage value of the electrolyte in the electrolytic cell 1 is 0.95V.

[0099] This embodiment is characterized by using a pickling tank 11-1 for pickling and iron removal. Electrolytic tank 1 uses the iron-containing pickling wastewater to produce a reusable pickling solution through an electrolytic iron removal and acid production process. The copper oxalate 22, which has undergone iron removal but still contains trace amounts of iron salts and acid impurities, is washed in a pickling tank 11-2. The resulting wash wastewater has an iron ion concentration of 370 mg / L and a pH of 3.6. After washing, the wastewater is separated into solids and liquids in a solid-liquid separator 20-3 to produce high-quality copper oxalate.

[0100] The steps for purifying the copper oxalate recovered from the iron-containing etching waste liquid and treating and reusing the purified waste liquid are as follows:

[0101] 1. Copper oxalate 21 containing iron salt impurities and pickling solution 39 are added to the pickling tank 11-1 for pickling. During the pickling process, a small amount of hydrogen peroxide 34-1 is added to increase the ORP value of the reaction solution from 320mv to 450mv, thereby oxidizing the divalent iron ions in the reaction solution to trivalent iron ions.

[0102] 2. After pickling, the iron-containing pickling waste liquid obtained by treatment in the solid-liquid separators 20-1 and 20-2 is drained to the temporary storage tank 12-2 for temporary storage, and the copper oxalate 22 that has been treated for iron impurities but still contains acid impurities is put into the temporary storage tank 12-1 for temporary storage.

[0103] 3. Iron-containing pickling wastewater 24 is added to chemical reaction tank 13. Sodium chlorate 34 is added based on the process setpoint of 810 mV as measured by ORP meter sensor 9-5 within the tank. The hot and cold temperature exchanger 14 is operated to heat the reaction solution at 50°C to accelerate the reaction. After 10 hours of reaction, a sample is taken and tested. If no oxalate is detected in the solution, the oxidation treatment is considered complete. Pump 37-4 is then operated to pump the solution to temporary storage tank 12-3.

[0104] 4. The iron-containing pickling waste liquid 24-2 in the temporary storage tank 12-3 is controlled by the sensor 9-7 to be added to the anode tank area of ​​the electrolytic cell 1, and the dilute hydrochloric acid is added to the cathode tank area, so that the positive and negative electrodes are immersed in their respective electrolytes.

[0105] 5. Start the liquid flow pump tube agitators 29-2 and 29-3, turn on the electrolysis power supply and adjust its output voltage to 6.5V, and perform electrolysis to cause chlorine and carbon dioxide gas to escape from the anode electrolyte. The iron ions and copper ions in the anode electrolyte pass through the separator and enter the cathode tank area. The cathode electrolyte escapes hydrogen and is discharged through the hydrogen high-altitude discharge pipe. A small amount of metallic copper is electrolytically deposited on the cathode. The iron ion concentration detected by the photoelectric colorimeter in the anode tank area becomes smaller and smaller, and the pH value detected by the pH meter becomes lower and lower. The acidity detected by the acidity meter in the cathode tank area decreases, and the pump 37-9 is controlled to add hydrochloric acid.

[0106] 6. To maintain the acidity of the cathode electrolyte, a pH meter is used as the setting value of the hydrochloric acid parameter pH1 to control the addition of dilute hydrochloric acid 25. The overflowed cathode electrolyte becomes the tail liquid 32 to be treated and is drained into the temporary storage tank 12-5 for temporary storage and treatment.

[0107] 7. When the photoelectric colorimeter in the anolyte is less than 0.1g / L Fe 3+ When the concentration reaches the set value, it is considered that the iron-containing pickling waste liquid in the tank has completed its iron removal and acid production treatment according to the reuse pickling liquid treatment standard, and then the electrolysis power supply, liquid flow pump pipe agitator are turned off and pump 37-7 is turned on to pump the reuse pickling solution 28 to the temporary storage tank 12-4 for temporary storage. When production needs it, the reuse pickling solution 28 is returned to the pickling tank 11-1 for recycling.

[0108] 8. Under the control of the liquid level gauge in the anode tank area, the solution 24-2 is again extracted from the temporary storage tank 12-3 and added to the anode tank area of ​​the electrolytic cell. After the liquid level is reached, the pump 37-5 is shut down and the electrolysis power supply and the liquid flow pump pipe agitator are started to resume the electrolytic iron removal and acid production operation, and the operation sequence of steps 5 to 7 above is continued.

[0109] 9. The copper oxalate, which has been deironed but still contains acid impurities, is placed in the pickling tank 11-2 and washed with clean water 31. After washing, the copper oxalate is separated into solid and liquid by the solid-liquid separator 20-3 to obtain pure copper oxalate 23 and a separated washing filtrate. The washing filtrate is drained as the tail liquid to be treated 32 and temporarily stored in the tank 11-5 for further treatment.

[0110] 10. The chlorine Cl2 and other acidic tail gases generated in the treatment device during the operation are all drained into the tail gas environmental protection treatment tank 16 for environmental protection treatment.

[0111] 11. Hydrogen concentration detectors 9-11 and chlorine concentration detectors 9-12 installed in the workshop space monitor the environment.

[0112] 12. In this embodiment, the pure copper oxalate product 23 can be cleaned again or multiple times using the pickling solution 39 and pure water 31 according to the process requirements to obtain copper oxalate powder with higher purity.

[0113] 13. Collect the washed copper oxalate product.

[0114] Example 3

[0115] Example 3 uses Figure 3The device shown includes two 100-liter electrolytic cells 1-1 and 1-2, multiple sensors 9, an automatic detection and feeding controller 10, a pickling tank 11, five temporary storage tanks 12, two chemical reaction tanks 13, a hot and cold temperature exchanger 14, four overflow buffer tanks 15, an exhaust gas environmental protection treatment tank 16, a solid-liquid separator 20, two liquid flow pump tube agitators 29, an impeller agitator 30, multiple pumps and valves.

[0116] Both electrolytic cells are separated into an anode cell area and a cathode cell area by a cation exchange membrane 4. The tops of the anode cell area and the cathode cell area are both provided with an electrolytic cell gas collecting tank cover, and the cathode cell area is provided with a liquid flow pump tube agitator. The electrolytic anode 2-1 in the electrolytic cell 1-1 is made of conductive graphite, and the electrolytic cathode 3-1 is made of titanium. The electrolytic anode 2-2 in the electrolytic cell 1-2 is made of a gold-plated conductor and platinum wire, and the electrolytic cathode 3-2 is made of copper.

[0117] The pickling tank 11 is provided with an impeller agitator 30 for cleaning the copper oxalate 21 containing iron salt impurities.

[0118] The solid-liquid separator 20 is a centrifuge used for solid-liquid separation of the reactants in the pickling tank 11; it is connected to the solid-liquid separator 20 and connected to the chemical reaction tank 13-1 through the temporary storage tank 12-2.

[0119] The chemical reaction tank 13-1 is a mixed exchange tank for the anode electrolytes of the two electrolytic cells. Specifically, its liquid outlet is respectively connected to the liquid inlet of the anode tank area of ​​the two electrolytic cells and the liquid inlet of the temporary storage tank 12-3, and its liquid inlet is respectively connected to the liquid outlet of the anode tank area of ​​the two electrolytic cells; its storage capacity is 500 liters, which is used to increase the amount of iron-containing pickling waste liquid processed each time. It is equipped with a hot and cold temperature exchanger 14, as well as sensors 9-3, 9-4, 9-5, 9-6 and 9-7, which are respectively a liquid level meter, a photoelectric colorimeter, an ORP meter, a thermometer, and a pH meter; among them, the photoelectric colorimeter is used to detect the iron ion concentration, the ORP meter is used to control the working state of the electrolytic power supply, the thermometer is used to control the working state of the hot and cold temperature exchangers, and the pH meter is used to detect the acidity of the anode electrolyte. The chemical reaction tank 13-2 is used to neutralize the tail liquid 32 to be treated and discharge the upper qualified discharge solution 35 after the heavy metal hydroxide settles; it is connected to the liquid outlet of the cathode tank area of ​​the electrolytic cells 1-1 and 1-2 through the temporary storage tank 12-4.

[0120] The iron-containing pickling wastewater 24 is produced by pickling copper oxalate 22, which has been treated for iron but still contains acid impurities, using a mixture of sulfuric acid and hydrochloric acid. Its main components are sulfuric acid, hydrochloric acid, copper sulfate, ferric sulfate, ferric chloride, cupric chloride, oxalic acid, and trace amounts of oxalate. Its pH is 0.98, its iron ion concentration is 430 mg / L, and its copper ion concentration is 30 mg / L.

[0121] The pickling 39 is a mixture of sulfuric acid and hydrochloric acid, and its pH value is 1.

[0122] The cathode electrolyte is all acid washing solution 39.

[0123] The alkaline solution is 10% sodium hydroxide solution.

[0124] The sensors 9-1 and 9-2 are level gauges, installed in the temporary storage tanks 12-2 and 12-3 respectively; sensors 9-8 and 9-9 are pH meters installed in the cathode tank areas of the two electrolytic cells and used to control the operation of pumps 37-12 and 37-13 to add pickling solution to the temporary storage tank 12-4 respectively.

[0125] The temporary storage tank 12-4 is installed with sensors 9-10, specifically liquid level gauges, for temporarily storing the washing waste liquid 32 for processing.

[0126] The temporary storage tank 12-5 is equipped with a sensor 9-11, specifically a liquid level meter, for loading the pickling solution 39 for use.

[0127] The exhaust gas environmental treatment tank 16 is equipped with a pH meter as a sensor 9-12 for environmentally treating the exhaust gas from each tank; and it is provided with a spray tower, and the air intake pipe is connected to the pipe for escaping acidic waste gas.

[0128] The chemical reaction tank 13-2 is equipped with an impeller stirrer 30-2 for stirring the neutralization reaction.

[0129] The electrolytic decomposition voltage value of the electrolyte in the electrolytic cell is 1.7V.

[0130] The steps of purifying copper oxalate recovered from iron-containing etching waste liquid and treating and reusing the purified waste liquid are as follows: 1. Turn on the device control cabinet to enable the automatic detection and feeding controller 10 to start control execution, perform on-site detection of each sensor and transmit the data to the automatic detection and feeding controller 10 for processing, and issue instructions to make the device run automatically according to the pre-programmed program.

[0131] 2. Copper oxalate 22 that has been subjected to iron removal treatment and still contains trace iron salts and acid impurities and pickling solution 39 are added to the pickling tank 11, and the impeller stirrer 30 is started to carry out pickling for 60 minutes.

[0132] 3. Start pump 37-1 to transfer the reactants in the pickling tank 11 to the solid-liquid separator 20 for solid-liquid separation. The separated iron-containing pickling waste liquid 24 is pumped to tank 12-2 for temporary storage. The separated copper oxalate 22, which has been treated for iron but still contains trace iron salts and acid impurities, is stored in the temporary storage tank 12-1.

[0133] 4. Pump the iron-containing pickling waste liquid 24 in the temporary storage tank 12-2 into the chemical reaction tank 13, and at the same time add the iron-containing pickling waste liquid 24 to the anode tank areas of the electrolytic cells 1-1 and 1-2, and add the pickling liquid 39 in the temporary storage tank 12-5 to the two cathode tank areas as the starting liquid of the cathode electrolyte.

[0134] 5. Under the control of the automatic detection and feeding controller 10, the hot and cold temperature exchanger 14 and the liquid flow pump tube agitators 29-1 and 29-2 are started, and the electrolysis power supplies 5-1 and 5-2, pumps 37-6, 37-7, 37-8, and 37-9 are turned on to circulate the anolyte of the two electrolytic cells. The anolyte temperature is controlled at 40°C. The operating voltage output by the electrolysis power supply 5-1 is 11V, and the operating voltage output by the electrolysis power supply 5-2 is 40V. Oxygen, chlorine, and a small amount of carbon dioxide are released from the anolyte of the two cells, and hydrogen is released from the catholyte. The gas is drained to high altitude for discharge and electrolysis, and a trace amount of sponge copper is electrolyzed on the cathode. The iron ions and other cations in the anolyte pass through the cathode electrolyte under the action of the electric field force and are enriched. The iron ion concentration detected by the photoelectric colorimeter of sensor 9-4 is getting lower and lower; the pH meters of sensors 9-8 and 9-9 control pumps 37-12 and 37-13 respectively according to the process setting values ​​to add acid cleaning solution 39 to maintain the pH value of the two cathode electrolytes at 3. The overflow liquid from the two cathode tank areas is drained to the temporary storage tank 12-4 as the tail liquid to be treated 32 for temporary storage for treatment.

[0135] 6. When the sensor 9-4 photoelectric colorimeter detects that the iron ion concentration of the solution in the chemical reaction tank 13 is as low as the process setting value of the reuse pickling liquid 200 mg / L and the pH value is lower than or reaches 1, it is considered that the iron removal and acid production treatment of the iron-containing pickling waste liquid is completed, and the automatic detection feeding controller 10 automatically shuts down the two electrolysis power supplies, the agitator and multiple circulating flow pumps, and starts the pump 37-5 under the control of the sensor 9-3 liquid level gauge to pump the solution in the chemical reaction tank 13 to the temporary storage tank 12-2 for temporary storage.

[0136] 7. Under the control of the liquid level gauge of sensor 9-3, the iron-containing pickling waste liquid 24 in the temporary storage tank 12-2 is added to the chemical reaction tank 13 again. When the liquid level is reached, the controller automatically issues a command to shut down the pump 37-2 and restart the electrolysis power supply, agitator, circulation pump and hot and cold temperature exchangers to continue the electrolytic iron removal and acid production operation.

[0137] 8. The recycled pickling liquid 28 in the temporary storage tank 12-3 is added to the pickling tank 11 according to process requirements to carry out a new round of mixed washing with the newly added iron salt impurity copper oxalate 21.

[0138] 9. The overflow liquid from the cathode tank area of ​​the electrolytic cell is drained into the temporary storage tank 12-5 for intermediate treatment. The tail liquid 32 to be treated in the temporary storage tank 12-5 is drained into the chemical reaction tank 13-2 for neutralization and precipitation treatment. The brine is discharged after the heavy metal hydroxide is settled.

[0139] 10. The hydrogen escaping from the cathode tank area of ​​the electrolytic cell is discharged to high altitude through hydrogen high altitude discharge pipes 19-1 and 19-2.

[0140] 11. The acidic tail gas escaping from multiple tanks in the device is led to the spray tower in the tail gas environmental protection treatment tank 16 for treatment.

[0141] 12. Collect the washed pure copper oxalate product 23.

Claims

1. A method for purifying copper oxalate recovered from iron-containing etching waste liquid and treating and reusing the purified waste liquid, wherein the copper oxalate contains divalent iron salt, trivalent iron salt, copper salt, oxalic acid, and soluble oxalate impurities, characterized in that: The following steps are involved: (1) establishing at least one electrolytic cell, wherein the electrolytic cell is divided into an anode cell area and a cathode cell area by a cation exchange membrane, wherein the electrolytic anode in the anode cell area is connected to the positive electrode of the electrolytic power supply, and the electrolytic cathode in the cathode cell area is connected to the negative electrode of the electrolytic power supply; (2) pickling the copper oxalate with a pickling solution, and obtaining the copper oxalate and iron-containing pickling waste liquid after pickling purification after solid-liquid separation; (3) adding the iron-containing pickling waste liquid into the anode tank area as the anolyte and soaking the electrolytic anode, and adding the catholyte into the cathode tank area and soaking the electrolytic cathode; After the electrolysis power supply is turned on, an electrochemical reaction is performed on the iron-containing pickling waste liquid. The electrolytic anode electrolyzes oxidizing gas and / or carbon dioxide gas. The iron ions and other cations in the anolyte are enriched in the cathode tank area by the action of the electric field force through the cation exchange membrane. The electrolytic cathode performs an electrochemical reduction reaction on the cathode electrolyte to electrolyze hydrogen and / or reduce high-valent metal ions to low-valent metal ions or their metals. At the same time, the anolyte reacts chemically with the oxalate ions therein through the oxidant produced by electrolysis, thereby removing impurities in the iron-containing pickling waste liquid. (4) According to the process set by the reuse pickling liquid standard to detect the electrochemical reaction process of the anolyte in the anode tank area After the treatment is completed, the anolyte is used directly or after preparation as a pickling solution for this batch or another batch of oxalic acid containing iron salt impurities. Copper is used for iron removal pickling.

2. The method according to claim 1, characterized in that In step (3), the pH value of the anolyte is less than or equal to pH 4; the cathode electrolyte is a solution containing at least one of hydrochloric acid, sulfuric acid, pickling solution, and iron-containing pickling waste liquid, and Its pH value is less than or equal to pH4.

3. The method according to claim 2, characterized in that The voltage output value of the electrolytic power supply is selected to be greater than or equal to the The electrolytic decomposition voltage value of the electrolyte in the electrolytic cell; the electrolytic decomposition voltage value of the electrolyte in the electrolytic cell is the cathode just electrolysis The voltage value output by the electrolysis power supply when hydrogen or copper is used.

4. The method according to claim 3, characterized in that In step (4), the recycled acid The washing solution standard is specifically measured by using the parameters of iron ion concentration and / or acidity and / or pH value in the anolyte; when When the test result of the anolyte reaches at least one parameter value required by the process setting of the recycled acid cleaning solution standard, the anolyte is deemed to have reached the process treatment standard of the recycled acid cleaning solution, and the solution is directly or after being prepared and returned to the pickling tank to treat the acid cleaning solution. The iron salt impurity copper oxalate continues to be pickled.

5. The method according to claim 3, characterized in that In step (2), a pH of 4 or below and containing The pickling liquid is a solution of at least one of sulfuric acid, hydrochloric acid, and recycled pickling liquid.

6. The method according to claim 5, characterized in that When pickling copper oxalate, add double Oxygen water is used to oxidize the ferrous ion impurities in copper oxalate into trivalent ferrous ions, so as to reduce the generation of insoluble ferrous oxalate during pickling. become.

7. The method according to claim 5, characterized in that When pickling copper oxalate, ultrasonic cleaning is added to the pickling solution. The waves are used to assist in stirring and cleaning, so that the iron salt wrapped by copper oxalate dissolves faster in the pickling solution.

8. The method according to claim 5, characterized in that Add chlorate to the iron-containing pickling wastewater after solid-liquid separation. At least one of perchlorate, persulfate and hydrogen peroxide reacts to eliminate the insoluble copper oxalate.

9. The method according to claim 5, characterized in that Use a pH meter and / or acidity meter to measure the acidity of the anolyte. and add a photoelectric colorimeter and / or hydrometer to monitor the concentration of iron ions and / or copper ions in the anolyte. Control is used to achieve production automation and data standardization in the treatment process of iron-containing pickling wastewater.

10. The method according to claim 5, characterized in that Neutralize the catholyte discharged from the electrolytic cell The treatment is to make part or all of the iron and / or copper in the solution precipitate out, and after the treatment, the filter residue iron hydroxide, Trace amounts of copper hydroxide are collected, and the filtrate is tested and discharged after meeting the standards or mixed as recycled pickling liquid for use.

11. The method according to claim 5, characterized in that The acid-washed products still contain trace amounts of iron salts and acid The copper oxalate with impurities is washed with water, and the pure copper oxalate is produced after acid washing and water washing; the waste liquid obtained by water washing is used as the tail The liquid is treated with neutralization to remove heavy metal hydroxide precipitates and then discharged in compliance with standards or formulated as recycled pickling liquid for use.

12. A device for purifying copper oxalate recovered from iron-containing etching waste liquid using the method of claim 1 and treating and reusing the purified waste liquid, characterized in that: The electrolytic cell comprises at least one pickling tank, at least one solid-liquid separator and at least one electrolytic cell; the electrolytic cell is provided with a cation exchange membrane to separate it into anode and cathode cell areas, and is provided with an electrolytic anode connected to the positive electrode of the electrolytic power supply and an electrolytic cathode connected to the negative electrode of the electrolytic power supply.

13. The device according to claim 12, characterized in that Additional sensors are installed to detect and control the iron-containing pickling waste liquid during the electrolysis operation. The sensors include a acidity meter, a pH meter, a photoelectric colorimeter, a redox potentiometer, a hydrometer, a liquid level gauge, and a thermometer. The sensors are placed on a tank or pipeline that can contact the liquid to be measured.

14. The device according to claim 12, characterized in that An ultrasonic oscillating agitator is added to the pickling tank to accelerate the dissolution of iron salt impurities wrapped by copper oxalate in the pickling solution by the effect of ultrasound; and a hot and cold temperature exchanger is added to the solution tank where temperature control is required or on the pipeline through which the solution circulates, so that the temperature of the reaction liquid can be controlled according to process requirements.

15. The device according to claim 12, characterized in that A chemical reaction tank is added to perform an oxidation reaction on the iron-containing pickling waste liquid to remove insoluble oxalates therein to prevent it from clogging the electrolytic cell partition, or to be used for chemical reactions of other solutions; and an exhaust gas environmental protection treatment tank is added. The exhaust gas environmental protection treatment tank is provided with a gas-liquid mixer, and its air intake pipe is connected to the pipe for escaping acidic waste gas. The gas-liquid mixer is a vacuum ejector and / or a spray tower.

16. The device according to claim 12, characterized in that The specific surface area of ​​the electrolytic anode is increased, specifically by adopting an electrolytic anode structure having multiple pieces, coiled wires or honeycomb through-holes.

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