A process for the recovery of electrolytic copper from copper-containing waste water

Abstract

The present application belongs to the technical field of wastewater treatment and recovery, and particularly relates to a method for recovering electrolytic copper from copper-containing wastewater, which comprises, in sequence, complex breaking treatment by catalysis and low-temperature plasma-ultrasound synergy; solid-liquid separation and deep purification by ceramic membrane separation and mercapto-modified mesoporous silica adsorption column; electrolysis of the purified wastewater in a dynamic gradient electrolytic cell, which is divided into high, medium and low concentration zones by a porous partition, and the current density and flow rate of each zone are dynamically regulated by an online sensor and an AI-LSTM algorithm to realize efficient electrolysis with concentration adaptation; deep recovery of the electrolyzed solution by photocatalysis and bipolar membrane electrodialysis, with the produced acid and base being reused, and deep copper removal being realized by a chelating resin column; and finally, stripping, washing and drying of the obtained cathode copper deposit to obtain high-purity electrolytic copper products. The present application realizes efficient complex breaking, precise electrolysis and resource recovery of copper-containing wastewater, with high current efficiency, low energy consumption and high product purity.

Description

Technical Field

[0001] This invention belongs to the field of wastewater recycling and treatment technology, specifically relating to a method for recovering electrolytic copper from copper-containing wastewater. Background Technology

[0002] Copper-containing wastewater is widely generated in industries such as electroplating, metallurgy, and electronic component manufacturing. Copper often exists in a strongly stable complex form (such as EDTA-Cu²⁺, citric acid-Cu²⁺), with coordination bond energies as high as 400-500 kJ / mol. Traditional treatment technologies are difficult to efficiently break the complex and recover the copper, which has become a core problem in the industry. The existing technology has the following main drawbacks: First, the complex breaking efficiency is low and incomplete. For example, the complex breaking rates of the Fenton method and the alkaline hydrolysis method are less than 85% and 80%, respectively. The residual complexed copper will reduce the purity of the subsequent electrolyzed copper to below 99.5%, which cannot meet the requirements of electronic-grade copper. Second, the electrolysis system has poor adaptability. Traditional single-chamber electrolytic cells cannot cope with the large fluctuations in copper concentration in industrial wastewater, resulting in a drop in current efficiency to 50-70% and unstable operation. Third, the resource recovery rate is low. The recovery rate of acid and alkali reagents is less than 50%, and the reagent cost per ton of copper is as high as 3,000-5,000 yuan. Functional materials are mostly for single use and generate secondary pollution. At the same time, the direct discharge of low-concentration waste liquid causes copper resource loss and environmental risks. Finally, it is difficult to balance product purity and economy. Increasing purity requires the addition of additional purification reagents, which increases the cost per ton of copper by 2,000-3,000 yuan. Otherwise, the product has a high impurity content and can only be sold as industrial crude copper at a low price, creating a dilemma of "high purity means high cost, and low cost means low purity". To address this, an improved method for recovering electrolytic copper from copper-containing wastewater was designed. Summary of the Invention

[0003] To address the aforementioned shortcomings in the existing technology, this invention provides a method for recovering electrolytic copper from copper-containing wastewater, thereby solving the problems of low and incomplete complex breaking efficiency and low resource recovery rate in the aforementioned background technology.

[0004] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: a method for recovering electrolytic copper from copper-containing wastewater, comprising the following steps:

[0005] S1: Add a pH adjuster to copper-containing wastewater containing strong stable complexes and stir to adjust the pH to 2.5-3.5; then add activated carbon-supported nano-Fe3O4 catalyst and glycolic acid-aminosulfonic acid composite complex-breaking agent to form a reaction slurry; pass the reaction slurry into a low-temperature plasma-ultrasound synergistic reaction device to carry out the complex-breaking reaction;

[0006] S2: The reaction slurry after the complex breaking in step S1 is filtered and separated into liquid and solid phases using a ceramic membrane. The separated solid phase is retained and recovered. Then, the liquid phase containing the clarified liquid after complex breaking is passed into a mercapto-modified mesoporous silica adsorption column for purification and removal of impurity metal ions.

[0007] S3: The high-purity copper-containing wastewater purified in step S2 is fed into a dynamic gradient electrolytic cell. The dynamic gradient electrolytic cell is divided into three concentration gradient zones (high, medium, and low) along the electrolyte flow direction by a porous partition. During the electrolysis process, the current density and electrolyte flow rate of each zone are dynamically controlled. A cathode copper deposit is obtained by electrolytic deposition on the cathode.

[0008] S4: The copper-containing waste liquid after electrolysis in step S3 is first passed through a BiOBr / graphene photocatalytic unit to catalytically reduce Cu²⁺ to generate nano-elemental copper. Then, the reduced waste liquid is passed through a bipolar membrane electrodialysis structure to perform rough removal to generate sulfuric acid solution, sodium hydroxide solution, cathode copper precipitate, and waste liquid after rough removal of copper. Finally, the waste liquid after rough removal is passed through a chelating resin column for deep removal to obtain cathode copper deposit. The generated sulfuric acid solution and sodium hydroxide solution are reused in the pH adjustment in step S1.

[0009] S5: The obtained cathode copper deposit is peeled off by a mechanical scraper, and then ultrasonically washed with deionized water and vacuum dried in sequence to finally obtain a high-purity electrolytic copper product.

[0010] Furthermore, the activated carbon-supported nano-Fe3O4 catalyst comprises activated carbon and nano-Fe3O4.

[0011] Furthermore, the molar ratio of glycolic acid to aminosulfonic acid in the glycolic acid-aminosulfonic acid composite complexing agent is 2:1-3:1.

[0012] Furthermore, the low-temperature plasma-ultrasound synergistic reaction device includes a reaction chamber for the complex-breaking reaction and solid-liquid separation of the catalyst, a low-temperature plasma for supplying the energy required for complex breaking, an ultrasonic piezoelectric transducer for accelerating the complex-breaking reaction rate, and a constant temperature system for maintaining the complex-breaking reaction temperature.

[0013] Furthermore, the adsorbent in the thiol-modified mesoporous silica adsorption column is thiol-modified mesoporous silica.

[0014] Furthermore, in step S3, the porous partition of the dynamic gradient electrolyzer is made of acid- and corrosion-resistant material, and the dynamic gradient electrolyzer is equipped with an online sensor. The online sensor is used to monitor the Cu²⁺ concentration, temperature and conductivity of the electrolyte in each zone in real time.

[0015] Furthermore, in step S4, the membrane stacks of the bipolar membrane electrodialysis structure are stacked in the order of "homogeneous bipolar membrane - cation exchange membrane - anion exchange membrane".

[0016] Furthermore, in step S4, the chelating resin column is an aminophosphonic acid type chelating resin, and the amino and phosphonic acid groups on the resin surface are used to form a stable chelate with the residual Cu²⁺.

[0017] Furthermore, in step S5, the mechanical scraper is made of a flexible material to avoid scratching the cathode substrate of the dynamic gradient electrolysis cell; ultrasonic washing with deionized water is used to remove electrolyte residues such as sulfate and sodium ions attached to the surface of the cathode copper deposits, and the wastewater after washing is treated and reused in step S1 or S5.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. Achieving efficient and thorough complex breaking of highly stable complexes: By constructing a quaternary synergistic complex breaking system of "adsorption-enrichment, chemical competition, catalytic reduction, and energy synergy", the problem of incomplete complex breaking of highly stable complexes such as EDTA-Cu²⁺ by traditional single technologies has been overcome, improving the complex breaking rate and providing a key prerequisite for subsequent high-purity copper recovery.

[0020] 2. Achieve the recycling of catalysts and adsorbents and eliminate secondary pollution: The integrated purification solution of "ceramic membrane separation + catalyst reuse + selective adsorption" realizes the multiple reuse of catalysts and the removal of impurity metals, significantly reducing solid waste generation and reagent consumption, and solving the defects of high waste and high pollution of traditional purification technologies.

[0021] 3. Significantly improves the adaptability of the electrolysis process to concentration fluctuations and current efficiency: Through the dynamic gradient electrolysis technology of "zoning design + AI intelligent control" combined with high-performance electrode materials, the system can automatically adapt to copper concentration fluctuations, stabilize current efficiency, effectively suppress side reactions, and achieve efficient, stable and continuous operation under highly fluctuating water quality.

[0022] 4. Achieve full-element recycling and near-zero emissions of copper, acid and alkali and water resources: Creatively construct a three-level deep resource recovery closed loop of "photocatalytic reduction + bipolar membrane electrodialysis + chelating resin adsorption", which not only improves the total copper recovery rate, but also realizes the on-site regeneration and recycling of acid and alkali reagents in wastewater. The final effluent can be reused as circulating water, thus fully achieving the goals of resource conservation and near-zero emissions. Attached Figure Description

[0023] Figure 1 shows a schematic diagram of the overall steps of a method for recovering electrolytic copper from copper-containing wastewater according to an embodiment of this application. Detailed Implementation

[0024] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structure, features and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.

[0025] Example 1:

[0026] like Figure 1 As shown, this invention discloses a method for recovering electrolytic copper from copper-containing wastewater, specifically for treating wastewater containing EDTA-Cu²⁺ from electroplating plants. The wastewater contains 0.8 mg / L Pb²⁺, 0.3 mg / L Cd²⁺, and 0.5 mg / L Cr³⁺. Batch trials of this invention were conducted, and the core equipment includes a reaction vessel, low-temperature plasma, an ultrasonic generator, a ceramic membrane filtration system, a dynamic gradient electrolytic cell, an AI-LSTM control system, a photocatalytic reactor, and a bipolar membrane electrodialysis structure.

[0027] The detailed implementation steps are as follows:

[0028] S1: Add a pH adjuster to copper-containing wastewater containing EDTA-Cu²⁺ and stir to adjust the pH to 2.5-3.5; then add activated carbon-supported nano-Fe3O4 catalyst and glycolic acid-sulfamic acid composite complex-breaking agent to form a reaction slurry; pass the reaction slurry into a low-temperature plasma-ultrasound synergistic reaction device to carry out the complex-breaking reaction and achieve the decomposition of the strongly stable complex. Specifically, first pump 100L of wastewater into the reactor, stir at a rate of 400r / min, add 1.2L of 30% industrial-grade dilute sulfuric acid to adjust the pH to 3.0, and then add the self-made activated carbon-supported nano-Fe3O4 catalyst at 1.2g / L. The activated carbon-supported nano-Fe3O4 catalyst was prepared by soaking 0.8 mm activated carbon in 5% dilute hydrochloric acid at 60 °C for 2 h and then drying it. 120 g of activated carbon was mixed with a mixed solution of FeCl2・4H2O and FeCl3・6H2O, where the molar ratio of FeCl2・4H2O to FeCl3・6H2O was 1:2. Ammonia was added dropwise to adjust the pH to 8.0. The mixture was stirred in a 60 °C water bath for 2 h, filtered, and then dried at 110 °C to obtain the target catalyst. After drying, stirring was continued for 5 min to form a brownish-yellow suspension. The intermediate product was a wastewater suspension containing the catalyst, with uniform dispersion and no sedimentation. The nano-Fe3O4 loading was 20% of the total catalyst.

[0029] Next, the complex-breaking agent is added: Then, a complex-breaking agent composed of glycolic acid and aminosulfonic acid is added to the reaction system, and its total molar concentration in the reaction system is controlled to be 0.05 mol / L, wherein the molar ratio of glycolic acid to aminosulfonic acid is 2.5:1. After stirring for 10 minutes, a brown reaction slurry is formed.

[0030] The reaction slurry was pumped into a low-temperature plasma-ultrasound synergistic reaction device, which included a reaction chamber for complex-breaking reaction and catalyst solid-liquid separation, low-temperature plasma for supplying the energy required for complex-breaking, an ultrasonic piezoelectric transducer for accelerating the complex-breaking reaction rate, and a constant temperature system for maintaining the complex-breaking reaction temperature. Initially, the plasma discharge voltage was set to 22kV and power to 1400W, the ultrasonic frequency to 30kHz and power to 1200W, and a 20% ethylene glycol aqueous solution was introduced. The constant temperature system maintained the chamber temperature at 35℃, and the reaction time was 25 minutes. During the reaction, the slurry color gradually lightened, from brownish-red to light brown, and no bubbles overflowed. After the reaction, the reactor and the low-temperature plasma-ultrasound synergistic reaction device were rinsed with deionized water, and the rinse water was collected and incorporated into the next batch of wastewater treatment.

[0031] S2: The reaction slurry after complex breaking in step S1 is filtered and separated using a ceramic membrane. The separated solid phase is retained and recovered. The solid phase includes washable and reusable activated carbon-supported nano-Fe3O4 catalyst and trace solid impurities. Subsequently, the liquid phase containing the clarified liquid after complex breaking is purified by passing it through a mercapto-modified mesoporous silica adsorption column to remove impurity metal ions. Specifically, the complex-broken slurry is filtered through a ceramic membrane with a pore size of 0.15 μm, an operating pressure of 0.18 MPa, and a cross-flow velocity of 1.8 m / s. After filtration for 20 min, a light yellow-green clarified liquid with a concentration of 830 mg / L and a retained solid phase containing 120 g of catalyst and 5 g of trace solid impurities are obtained, totaling 125 g of retained solid phase. The retained solid phase is transferred to a washing tank and rinsed with 55°C deionized water for 4 min. At the same time, the activated carbon-supported nano-Fe3O4 catalyst is recovered and reused in the next batch.

[0032] The liquid phase containing the clarified solution after complex breaking was then pumped into a mercapto-modified mesoporous silica adsorption column, with the empty bed flow rate controlled at 1.0 BV / h. After adsorption, impurity metal ions were basically removed, and a high-purity Cu²⁺ solution was obtained. The ceramic membrane was backwashed with 0.5% dilute nitric acid for 10 min and then rinsed until neutral. After the adsorption column ran for 100 h, it was eluted and regenerated with 7% dilute sulfuric acid, and the regenerated solution was sent for hazardous waste treatment.

[0033] S3: The high-purity copper-containing wastewater purified in step S2 is fed into a dynamic gradient electrolytic cell. The dynamic gradient electrolytic cell is divided into three concentration gradient zones (high, medium, and low) along the electrolyte flow direction by a porous partition to accommodate different concentrations of copper ions for electrolysis. During electrolysis, the copper ion concentration in each zone is monitored in real time by an online sensor, and the current density and electrolyte flow rate in each zone are dynamically controlled by an AI-LSTM algorithm in conjunction with an independently configured adjustable-speed circulating pump and DC power supply for each zone. The cathode of the dynamic gradient electrolytic cell is a graphene-carbon nanotube-supported copper-palladium alloy, and the anode is a titanium-based iridium-ruthenium-tin-lanthanum quaternary doped oxide. A cathode copper deposit is obtained by electrolytic deposition on the cathode.

[0034] Specifically, a high-purity Cu²⁺ solution is pumped into a three-section dynamic gradient electrolyzer, which is separated by a polytetrafluoroethylene porous partition. By activating online sensors, including an ICP sensor, a temperature sensor, and a conductivity sensor, the online sensors can transmit data to the AI-LSTM control system in real time.

[0035] During electrolysis, Cu²⁺ in the high-concentration zone is rapidly consumed by the cathode reduction. In the medium and low-concentration zones, the Cu²⁺ concentration gradually decreases with the flow of electrolyte. The ICP sensor collects data at intervals to dynamically feed back the Cu²⁺ concentration decay rate in each zone. If Cu²⁺ in the high-concentration zone is consumed too quickly, the AI-LSTM system will automatically reduce the current density to prevent hydrogen evolution at the cathode due to insufficient Cu²⁺. If Cu²⁺ accumulates in the medium-concentration zone, the circulation pump flow rate will be increased to accelerate electrolyte flow and ensure that the concentration in each zone is always maintained within the appropriate range of 830 mg / L in the high zone, 270 mg / L in the medium zone, and 90 mg / L in the low zone.

[0036] Temperature sensors are used to monitor the electrolyte temperature in each zone to prevent temperature fluctuations from affecting electrolysis efficiency. Electrolysis is an exothermic reaction, and the higher the current density, the more pronounced the heat release. Excessive temperature can lead to abnormal electrolyte conductivity and coarse copper deposition grains at the cathode, while excessively low temperature reduces the Cu²⁺ diffusion rate and decreases current efficiency. When the sensor detects that the temperature in the high-concentration zone has risen to 38°C, the AI-LSTM system fine-tunes the circulation pump flow rate to remove excess heat through electrolyte flow, maintaining temperature stability.

[0037] ICP, temperature, and conductivity sensors are the core data sources for achieving "concentration adaptation and parameter optimization" in dynamic gradient electrolysis: the ICP sensor monitors the changes in Cu²⁺ concentration in each zone in real time, providing a basis for the AI-LSTM system to control and prevent insufficient Cu²⁺ from causing hydrogen evolution or accumulation; the temperature sensor ensures stable electrolyte temperature, avoiding a decrease in deposition quality or efficiency; and the conductivity sensor ensures the conductivity of the electrolyte, preventing increased energy consumption or co-deposition of impurities. The data from these three sensors construct a three-dimensional model of "concentration-temperature-conductivity," driving the AI-LSTM to adjust the current density and flow rate.

[0038] The dynamic gradient electrolyzer utilizes porous PTFE partitions to achieve a three-zone design for high, medium, and low concentrations. Combined with an AI-LSTM system, it enables precise control of "one parameter per zone," allowing for rapid reduction with high current in the high-concentration zone and avoiding hydrogen evolution with low current in the low-concentration zone. High-performance electrodes are employed to enhance deposition efficiency and purity. This structure effectively avoids side reactions caused by concentration fluctuations in traditional single-chamber systems, achieving high current efficiency in each zone and reducing energy consumption per ton of copper.

[0039] Next, a graphene-carbon nanotube-supported copper-palladium alloy cathode and a titanium-based iridium-ruthenium-tin-lanthanum quaternary doped oxide anode were installed. The AI-LSTM system dynamically adjusted the parameters according to the initial concentrations in the high, medium, and low concentration zones. The parameters were: high concentration zone current density 320 A / m², flow rate 1.4 L / min; medium concentration zone 200 A / m², 1.1 L / min; low concentration zone 100 A / m², 0.9 L / min; cell voltage 2.2 V; and temperature 36 °C.

[0040] After electrolysis, the copper deposits on the cathode are stripped off. During the electrolysis process, a dense, dark red copper layer gradually forms on the cathode surface without the generation of bubbles.

[0041] S4: The copper-containing waste liquid after electrolysis in step S3 is first passed into a BiOBr / graphene photocatalytic unit for catalytic reduction to generate nano-copper. Then, the reduced waste liquid is passed into a bipolar membrane electrodialysis structure composed of a homogeneous bipolar membrane, a cation exchange membrane, and an anion exchange membrane stacked together to perform rough removal of the reduced waste liquid, generating sulfuric acid solution, sodium hydroxide solution, cathode copper precipitate, and waste liquid after rough removal of copper. Finally, the waste liquid after rough removal is passed into a chelating resin column to deeply remove residual copper ions and nano-copper to obtain cathode copper precipitate. The generated sulfuric acid solution and sodium hydroxide solution are reused in the pH adjustment in S1, with the aim of recovering residual copper, regenerating acid and alkali, and achieving near-zero wastewater discharge.

[0042] The operating procedure is as follows: First, the low-concentration waste liquid is pumped into the photocatalytic reactor, BiOBr / graphene catalyst is added, and the LED light source is turned on for 40 minutes. After the reaction, the color of the waste liquid changes from light yellow to colorless. The Cu²⁺ concentration is 2.2 mg / L and the reduction rate is 87.8%. Nano-elemental copper is generated and partially adsorbed on the surface of the BiOBr / graphene catalyst. Then, the BiOBr / graphene catalyst is recovered by ultrafiltration membrane filtration, ultrasonically washed with deionized water, and after washing, the photocatalytic activity is tested to ensure that the BiOBr / graphene catalyst can maintain stable catalytic efficiency after reuse. The catalyst is then sealed for later use, and the ultrafiltration permeate is collected into the electrodialysis feed tank.

[0043] The catalytically purified solution is then pumped into a bipolar membrane electrodialysis structure. The membrane stack consists of a homogeneous bipolar membrane (BPM), a cation exchange membrane (CEM), and an anion exchange membrane (AEM), stacked sequentially. The voltage is set at 45V, the current density at 120A / m², and the circulation flow rate at 8L / min. The anode plate of the bipolar membrane electrodialysis structure is a titanium-based iridium-tantalum coated electrode, and the cathode plate is a titanium mesh-supported copper-palladium alloy. Each membrane is separated by a porous polypropylene mesh, forming independent acid, alkali, and waste liquid chambers. Independent inlet and outlet channels are provided to achieve a parallel flow channel design, ensuring uniform electrolyte flow rate in each chamber. This membrane stack structure utilizes the selective permeability of the ion exchange membrane and the dissociation characteristics of the bipolar membrane to achieve copper removal and acid / alkali regeneration under an electric field. The specific electrolysis mechanism is as follows: Under the action of an electric field, the homogeneous bipolar membrane dissociates the internal water into H⁺ and OH⁻. H⁺ is released on the cation exchange membrane side and OH⁻ is released on the anion exchange membrane side. The potential gradient formed by the electric field drives Na⁺ in the waste liquid chamber to migrate to the alkali chamber through the cation exchange membrane and SO₄²⁻ to migrate to the acid chamber through the anion exchange membrane. Cu²⁺ and nano-elemental copper are confined in the waste liquid chamber and undergo a reduction deposition reaction on the cathode surface. Finally, crude copper precipitate and copper removal waste liquid are generated in the waste liquid chamber. In the acid chamber, H⁺ and SO₄²⁻ combine to generate sulfuric acid solution. In the alkali chamber, OH⁻ and Na⁺ combine to generate sodium hydroxide solution. The regenerated sulfuric acid and sodium hydroxide can be diluted and reused for pH adjustment in step S1, so as to achieve simultaneous copper resource recovery and acid-base resource recycling.

[0044] After 2 hours of operation, the sulfuric acid solution obtained from the acid chamber is collected in the acid storage tank for reuse in step S1 for pH adjustment. The sodium hydroxide solution obtained from the alkali chamber is collected in the alkali storage tank for reuse in step S1 for pH adjustment. Crude copper precipitate is deposited on the cathode surface of the waste liquid chamber and collected using a polytetrafluoroethylene scraper. The waste liquid after crude copper removal is collected in the resin column feed tank. The intermediate products are sulfuric acid, sodium hydroxide, crude copper precipitate, and low-concentration waste liquid.

[0045] The waste liquid after crude copper removal is then pumped into an aminophosphonic acid chelating resin column, with the empty bed flow rate controlled at 1.1 BV / h. The Cu²⁺ concentration of the outlet liquid from the aminophosphonic acid chelating resin column is detected to be 0.003 ppm. The outlet liquid is returned to the reactor in step S1 as circulating water. After use, the aminophosphonic acid chelating resin column is eluted with dilute sulfuric acid to generate regenerated liquid. The regenerated liquid is pumped into the high-concentration zone of step S3 for electrolysis. Finally, a cleaning operation is performed, rinsing the inner wall of the aminophosphonic acid chelating resin column with deionized water. The bipolar membrane electrodialysis structure is rinsed with deionized water after shutdown to prevent salt crystallization blockage. The aminophosphonic acid chelating resin column needs to be rinsed with deionized water after elution until the pH reaches 3.0 before use.

[0046] S5: The obtained cathode copper deposit is mechanically scraped off, and then sequentially ultrasonically washed with deionized water and vacuum dried to finally obtain a high-purity electrolytic copper product, specifically including:

[0047] Mechanical stripping: Combine the S3 cathode copper deposit with the S4 crude copper deposit, and use a PTFE flexible scraper to strip along the parallel direction of the cathode substrate. After stripping, the copper sheet is dark red and has no obvious scratches.

[0048] Ultrasonic cleaning: Place the copper sheet in an ultrasonic cleaning tank, add 55℃ deionized water, ultrasonically clean for 8 minutes, and wipe the surface of the copper sheet after cleaning.

[0049] Ion chromatography analysis showed that sulfate residue was 0.08 mg / g and sodium residue was 0.05 mg / g, which met the purity requirements. The washing wastewater was collected and used for the next batch of washing.

[0050] Vacuum drying: Place the copper sheet in a vacuum drying oven, set the temperature to 80℃ and the vacuum degree to 0.098MPa, and dry for 1.5 hours. Nitrogen gas is introduced during the drying process to maintain a low-oxygen environment and prevent copper oxidation.

[0051] Final product testing: The dried copper sheet weighed 79.8g, with a purity of 99.992% Cu.

[0052] The following table compares this method with two comparative examples, and the comparison results are as follows:

[0053]

[0054] Comparative Example 1 used Fenton's reagent to replace the S1 synergistic complex-breaking system. The reaction was carried out at pH 3.0 for 60 min, and the results showed a complex-breaking rate of 82%, a sludge volume of 12 kg / m³, and a copper purity of 98.5% in the subsequent electrolysis. It had the defects of incomplete complex breaking and large sludge volume, which confirmed the necessity of synergistic complex breaking. Comparative Example 2 used a non-zoned single-chamber electrolyzer to replace the dynamic gradient electrolyzer. The current density was fixed at 200 A / m² and the flow rate was 1.0 L / min. The core results were a current efficiency of 78%, an electrolysis time of 90 min, and pores on the cathode copper surface with a purity of 98.8%. It had the defects of poor concentration fluctuation adaptability and many side reactions.

[0055] The advantages of this invention are: efficient and thorough complex breaking: through the synergistic breaking of complexes by a "catalyst + complex breaking agent + low-temperature plasma-ultrasound synergistic reaction device", the strong and stable complexes are effectively decomposed, providing a prerequisite for subsequent electrolysis.

[0056] Precise and efficient electrolysis: The core technology of "dynamic gradient electrolyzer + online sensor + AI-LSTM control" is adopted to achieve zoned and parameter-adaptive electrolysis of copper ions with different concentrations, which fundamentally avoids side reactions.

[0057] Full resource recovery: By combining photocatalysis, bipolar membrane electrodialysis and chelating resin adsorption, deep recovery of copper and recycling of acid, alkali and catalyst are achieved, realizing resource utilization and low emission of wastewater treatment.

[0058] High product purity: Deep purification and precise control throughout the entire process, combined with high-performance electrodes, ensure the high purity and density of the final electrolytic copper product.

[0059] The above are merely embodiments of the present invention. The circuits, electronic components, and modules involved are all prior art, fully achievable by those skilled in the art, and require no further explanation. The content protected by this application does not involve improvements to the software and methods. Commonly known structures and characteristics in the solutions are not described in detail here. Those skilled in the art are aware of all common technical knowledge in the field prior to the application date or priority date, are able to access all prior art in that field, and have the ability to apply conventional experimental methods prior to that date. Those skilled in the art can, under the guidance of this application, improve and implement this solution in combination with their own capabilities. Some typical known structures or methods should not be obstacles for those skilled in the art to implement this application. It should be noted that those skilled in the art can make several modifications and improvements without departing from the structure of the present invention. These should also be considered within the scope of protection of the present invention, and will not affect the effectiveness of the implementation of the present invention or the practicality of the application.

Claims

1. A method for recovering electrolytic copper from copper-containing wastewater, characterized in that: Includes the following steps: S1: Add a pH adjuster to copper-containing wastewater containing strong stable complexes and stir to adjust the pH to 2.5-3.5; then add activated carbon-supported nano-Fe3O4 catalyst and glycolic acid-aminosulfonic acid composite complex-breaking agent to form a reaction slurry; pass the reaction slurry into a low-temperature plasma-ultrasound synergistic reaction device to carry out the complex-breaking reaction; S2: The reaction slurry after the complex breaking in step S1 is filtered and separated into liquid and solid phases using a ceramic membrane. The separated solid phase is retained and recovered. Then, the liquid phase containing the clarified liquid after complex breaking is passed into a mercapto-modified mesoporous silica adsorption column for purification and removal of impurity metal ions. S3: The high-purity copper-containing wastewater purified in step S2 is fed into a dynamic gradient electrolytic cell. The dynamic gradient electrolytic cell is divided into three concentration gradient zones (high, medium, and low) along the electrolyte flow direction by a porous partition. During the electrolysis process, the current density and electrolyte flow rate of each zone are dynamically controlled. A cathode copper deposit is obtained by electrolytic deposition on the cathode. The dynamic gradient electrolytic cell is equipped with an online sensor, which is used to monitor the Cu²⁺ concentration, temperature, and conductivity of the electrolyte in each zone in real time. S4: The copper-containing waste liquid after electrolysis in step S3 is first passed through a BiOBr / graphene photocatalytic unit to catalytically reduce Cu²⁺ to generate nano-elemental copper. Then, the reduced waste liquid is passed through a bipolar membrane electrodialysis structure to perform rough removal to generate sulfuric acid solution, sodium hydroxide solution, cathode copper precipitate, and waste liquid after rough removal of copper. Finally, the waste liquid after rough removal of copper is passed through a chelating resin column for deep removal to obtain cathode copper deposit. The generated sulfuric acid solution and sodium hydroxide solution are reused in the pH adjustment in step S1. S5: The cathode copper deposits obtained in steps S3 and S4 are peeled off by a mechanical scraper, and then ultrasonically washed with deionized water and vacuum dried in sequence to finally obtain a high-purity electrolytic copper product.

2. The method for recovering electrolytic copper from copper-containing wastewater as described in claim 1, characterized in that: The molar ratio of glycolic acid to aminosulfonic acid in the glycolic acid-aminosulfonic acid composite complexing agent is 2:1-3:

1.

3. The method for recovering electrolytic copper from copper-containing wastewater as described in claim 1, characterized in that: The low-temperature plasma-ultrasound synergistic reaction device includes a reaction chamber for the complex-breaking reaction and solid-liquid separation of the catalyst, a low-temperature plasma for supplying the energy required for complex breaking, an ultrasonic piezoelectric transducer for accelerating the complex-breaking reaction rate, and a constant temperature system for maintaining the complex-breaking reaction temperature.

4. The method for recovering electrolytic copper from copper-containing wastewater as described in claim 1, characterized in that: The adsorbent in the thiol-modified mesoporous silica adsorption column is thiol-modified mesoporous silica.

5. The method for recovering electrolytic copper from copper-containing wastewater as described in claim 1, characterized in that: In step S3, the porous partition of the dynamic gradient electrolytic cell is made of acid- and corrosion-resistant material.

6. The method for recovering electrolytic copper from copper-containing wastewater as described in claim 1, characterized in that: In step S4, the membrane stacks of the bipolar membrane electrodialysis structure are stacked in the order of "homogeneous bipolar membrane - cation exchange membrane - anion exchange membrane".

7. The method for recovering electrolytic copper from copper-containing wastewater as described in claim 1, characterized in that: In step S4, the chelating resin column uses an aminophosphonic acid type chelating resin, and the amino and phosphonic acid groups on the resin surface are used to form a stable chelate with the residual Cu²⁺.

8. The method for recovering electrolytic copper from copper-containing wastewater as described in claim 1, characterized in that: In step S5, the mechanical scraper is made of a flexible material to avoid scratching the cathode substrate of the dynamic gradient electrolysis cell; ultrasonic washing with deionized water is used to remove electrolyte residues such as sulfate and sodium ions attached to the surface of the cathode copper deposits; the wastewater after washing is treated and then returned to step S1 or S5 for reuse.

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