Copper refining and recovering system and method

Abstract

The invention discloses a copper refining and recycling system and method. The method comprises the steps of extraction, reverse extraction, electrolysis and etching liquid regeneration. During electrolysis, the copper ion concentration and the oxidation-reduction potential are monitored in real time, the current reference is set according to the concentration, the potential is dynamically and finely adjusted, the potential is maintained to be-0.2 V to + 0.1 V, and generation of cuprous is inhibited; the copper absorption amount of the extraction agent is monitored regularly; the regeneration liquid pre-controls chloride ions and pH. The system integrates on-line monitoring and automatic regulation and control of a central controller. The cathode copper purity, the system stability and the regenerated liquid quality can be improved.

Description

Technical Field

[0001] This invention relates to the field of copper ion recovery technology, and more specifically, to a copper refining and recovery system and method. Background Technology

[0002] The ammonia etching process in printed circuit board (PCB) manufacturing generates a large amount of etching waste liquid with high copper content, the main component of which is copper-ammonia complex (such as Cu(NH3)4Cl). 2） Ammonium chloride and excess ammonia water are contaminated waste liquids. Direct discharge of such waste liquids will cause serious environmental pollution and waste valuable copper resources. Therefore, copper resource recovery and etching solution regeneration from ammonia etching waste liquids have significant environmental and economic benefits.

[0003] Currently, the technologies for the treatment and resource utilization of ammonia etching waste liquid can be mainly divided into the following categories: 1. Chemical precipitation method: Copper is recovered by precipitating copper as basic copper carbonate or copper hydroxide by adding a precipitant (such as sodium carbonate or sodium hydroxide) to the waste liquid. This method is simple, but copper precipitation is usually incomplete, making it difficult to effectively regenerate the etching solution. Furthermore, the precipitated products have limited value, and subsequent treatment may cause secondary pollution.

[0004] 2. Solvent Extraction-Electrolysis Method: This is a relatively mature and widely used technology in industry. The basic process involves using a specific extractant to extract copper ions from the etching solution to the organic phase, achieving separation of copper from the etching solution matrix. The copper-loaded organic phase is then back-extracted with sulfuric acid to obtain a pure copper sulfate electrolyte. Finally, cathode copper is recovered from the electrolyte through electrolysis, and the copper-free etching solution, after being replenished with ammonia, chloride ions, and other components, can be returned to the production line for reuse. This method achieves the dual goals of copper recovery and etching solution regeneration. However, existing industrial systems face several technical bottlenecks in operation: The electrolysis process is poorly controlled: Electrolysis typically involves empirically setting a large current range based solely on the copper ion concentration in the electrolyte for constant current or segmented constant current electrolysis. This open-loop control method cannot respond in real-time to the complex electrochemical changes within the electrolytic cell, easily leading to the accumulation of monovalent copper ions (Cu... + The formation and accumulation of monovalent copper. Monovalent copper not only forms impurities such as cuprous chloride (CuCl), affecting the purity of cathode copper, but may also reduce current efficiency, and due to its solubility, it crystallizes at low temperatures in the system, causing blockages in pipes and equipment.

[0005] System operational stability relies on human experience: there is a lack of systematic and quantitative monitoring methods for the performance of the extractant (oil phase). As the "blood" of the system, the extractant's copper adsorption capacity and entrainment losses directly affect recovery efficiency and operating costs. However, relying solely on periodic simple tests or operator experience judgment makes it difficult to provide timely warnings of performance degradation, and preventive maintenance and precise optimization of process parameters are not possible.

[0006] Passive quality control of regenerated solution: The formulation of the regenerated etching solution is mostly done to meet basic process parameters (such as Cu). 2+ Cl - The current technology focuses on pH as a target, but fails to proactively control side reactions (such as the formation of monovalent copper) from the perspective of suppressing the overall system's side reactions. Monovalent copper is more stable in a high chloride ion environment, and current technologies do not adequately address optimizing the composition of the regenerated solution itself (such as Cl-). - The trend is to reduce the generation of impurities in subsequent processes from the source by adjusting concentration and pH.

[0007] 3. Direct reduction method (e.g., hydrazine hydrate reduction under nitrogen protection): This method has shown high copper precipitation efficiency in laboratory studies, directly yielding high-purity copper powder. However, this method focuses on the single recovery of copper, lacking systematic solutions for the recycling characteristics of the mother liquor after reduction, long-term operational stability, and integration into existing continuous industrial systems. Furthermore, there are no reports on how to transplant and optimize the advanced control concepts (such as potential monitoring) from this method for large-scale industrial electrolysis processes.

[0008] In summary, existing technologies either suffer from single defects in recycling efficiency, product value, or regeneration effect, or, in integrated industrial systems, face comprehensive problems such as low operating efficiency, limited product purity, and poor system stability due to inefficient process control and insufficient monitoring. Therefore, there is an urgent need to develop a new ammonia etching solution recycling and copper refining recovery technology that can inherit the advantages of continuous and stable operation from mature industrial systems while fundamentally improving copper recovery purity, system operating efficiency, and regeneration solution quality through the introduction of intelligent and refined control and monitoring methods. Summary of the Invention

[0009] To overcome the shortcomings of the prior art, the first objective of this invention is to provide a copper refining and recycling method, comprising the following steps: Step S1, Extraction: The copper-containing ammonia etching solution is brought into contact with an organic extractant to transfer copper ions to the organic phase, resulting in a copper-loaded organic phase and a preliminary copper-poor etching aqueous phase. Step S2, back-extraction: The copper-loaded organic phase is back-extracted with sulfuric acid solution to obtain a copper sulfate electrolyte rich in copper ions and a regenerated organic phase; Step S3, Electrolysis: Electrolysis is performed on a copper sulfate electrolyte rich in copper ions to obtain metallic copper at the cathode; Step S4, Etching solution regeneration: The composition of the initial copper-poor etching aqueous phase is adjusted to obtain a regenerated etching solution.

[0010] Compared with existing technologies, this invention systematically integrates four core process units: solvent extraction, acid back-extraction, electrolytic purification, and etching solution regeneration, constructing a complete resource-based process. This not only achieves efficient and continuous extraction of high-value copper from complex etching waste liquid, but more importantly, it simultaneously repairs and regenerates the etching solution matrix, enabling it to be safely returned to the production line for reuse. This fundamentally transforms the traditional "treatment-discharge" model into an "extraction-regeneration" circular economy model, maximizing both environmental and economic benefits.

[0011] In one possible implementation, step S3 involves real-time monitoring and optimization of the electrolysis process, which includes: Step S31: Monitor the copper ion concentration and redox potential of the copper sulfate electrolyte in real time; Step S32: Set the initial reference value of the electrolysis current based on the monitored copper ion concentration; Step S33: Dynamically fine-tune the electrolysis current based on the monitored redox potential to maintain the redox potential within a preset range.

[0012] Compared with existing technologies, this invention overcomes the limitations of traditional electrolysis processes that rely solely on concentration for crude current control. It innovatively introduces redox potential as a real-time sensitive indicator reflecting the microscopic state of the electrochemical reaction and establishes a dynamic feedback control mechanism based on this potential. This transforms the electrolysis process from an open-loop, static operation into a closed-loop intelligent system capable of sensing the internal chemical environment in real time and automatically adjusting itself, providing unprecedented control capabilities for precisely managing complex electrochemical reactions and directionally suppressing byproduct formation.

[0013] In one possible implementation, in step S32, the reference relationship for setting the initial reference value of the electrolysis current based on the monitored copper ion concentration is as follows: When Cu 2+ When the concentration is greater than 10 g / L and less than or equal to 15 g / L, the current should be set to 700-1000A; When Cu 2+ When the concentration is greater than 15 g / L and less than or equal to 30 g / L, the current should be set to 1000-3000A; When Cu 2+ When the concentration is >30 g / L, the current should be set to 3000-3500A.

[0014] Compared with existing technologies, this invention establishes a standardized correspondence between copper ion concentration and current magnitude, enabling the system to quickly determine the optimal starting operating point under different feed loads. This avoids the arbitrariness of manual settings and the resulting inefficiency or safety issues, laying a stable and reliable process foundation for subsequent fine-tuning and ensuring optimal operation under all working conditions.

[0015] In one possible implementation, in step S33, the preset range is -0.2V to +0.1V; Furthermore, when the redox potential exceeds the upper limit of the range, the electrolysis current is increased; When the current is below the lower limit of the range, reduce the electrolysis current.

[0016] Compared with existing technologies, this invention, through extensive experiments and mechanistic analysis, clarifies that maintaining the redox potential of the system within a specific range is crucial for suppressing the generation of monovalent copper ions and ensuring the purity of the cathode copper. Furthermore, it specifies an intuitive and reliable control logic: "higher potential increases current to enhance reduction, while lower potential decreases current to prevent over-reduction." This precise regulation based on electrochemical principles ensures that the deposition process is always within an ideal thermodynamic and kinetic window, representing a significant technological leap from pursuing "current quantity" to controlling "reactant quality."

[0017] In one possible implementation, step S1 further includes monitoring the performance of the organic extractant: taking samples periodically, using a separatory funnel method, and sequentially treating and titrating the extractant with sulfuric acid, etching working solution, water, and sulfuric acid to determine its copper adsorption, copper elution, and copper entrainment, and judging the state of the extractant or adjusting the oil-water ratio based on the results.

[0018] Compared with existing technologies, this invention simulates the entire process of "copper absorption-elution-back-extraction" under actual working conditions and quantitatively analyzes key indicators such as copper absorption and entrainment loss, thereby achieving a quantitative evaluation of the extractant performance. This provides data basis for judging the degree of extractant attenuation and scientific adjustment, avoiding complete reliance on manual experience, and thus ensuring the stable operation of the extraction unit.

[0019] In one possible implementation, in step S3, an inert gas is introduced to cover the liquid surface during the storage or transportation of the copper sulfate electrolyte.

[0020] In one possible implementation, the concentration of sulfuric acid in the copper sulfate electrolyte is controlled to be 190-220 g / L.

[0021] Compared to existing technologies, this invention introduces an inert gas to cover the liquid surface, effectively isolating oxygen and preventing accidental oxidation of electrolyte components and acid mist volatilization, thus maintaining the constancy of the material composition. Simultaneously, actively controlling the sulfuric acid concentration within the optimal range ensures stable conductivity and ionic strength of the electrolyte, creating an ideal chemical environment for efficient electrode reactions. These two measures work synergistically to significantly reduce system operational fluctuations and the risk of crystallization blockage.

[0022] In one possible implementation, during step S4, when preparing the components, the chloride ion concentration of the regenerated etching solution is controlled within the range of 175-200 g / L, while its pH value is controlled within the range of 9.1-9.7.

[0023] Compared with existing technologies, this invention, based on a deep understanding of the side reaction mechanism, can effectively reduce the tendency of monovalent copper byproducts to form in the electrolysis process and reduce the risk of cuprous chloride precipitation by controlling the chloride ion concentration and pH value of the regenerated etching solution within a specific synergistic range, thereby improving the cleanliness and stability of the long-term operation of the circulation system.

[0024] A second objective of this invention is to provide a copper refining and recovery system for implementing copper refining and recovery methods, comprising: An extraction device is used to mix and separate copper-containing etching solutions from organic extractants; A back-extraction device, connected to the extraction device, is used for back-extracting a loaded organic phase with sulfuric acid; An electrolysis device, connected to the back-extraction device, is used for electrolyzing copper sulfate solution; A regeneration solution preparation device, connected to the extraction device, is used to treat the initial copper-poor etching aqueous phase.

[0025] Compared with existing technologies, this invention materializes the process flow with a clear physical architecture. Through the explicit connection and functional definition of dedicated devices such as extraction, back-extraction, electrolysis, and regeneration, it ensures a perfect match between the "process flow" and the "equipment flow." The system design not only guarantees the feasibility and industrialization of the technical solution, but its modular approach also facilitates system installation, maintenance, and scale adjustment, serving as a solid bridge connecting innovative processes with industrialized production.

[0026] In one possible implementation, an optimization control system is also included; the optimization control system includes: An online electrolyte monitoring module, wherein the sensors are installed in the inlet pipe or electrolytic cell of the electrolysis device, includes at least an online copper ion analyzer and a redox potentiometer; The central controller receives signals from the monitoring module and has a built-in potential fine-tuning algorithm. The execution module is electrically connected to the central controller and the rectifier of the electrolysis device; The potential fine-tuning algorithm is configured to dynamically adjust the electrolysis current based on the redox potential signal.

[0027] Compared with existing technologies, this invention constructs a complete "perception-decision-execution" automated closed loop by deploying online monitoring sensors, a central processing unit integrating advanced control algorithms, and a linked final actuator. This system can capture real-time changes in the microscopic state of the electrolyte and automatically adjust the current output in milliseconds, transforming cutting-edge control concepts into a stable and reliable industrial reality. It is a key manifestation of turning process knowledge into core competitiveness.

[0028] In one possible implementation, the central controller also has a built-in current-concentration reference table for setting an initial reference value for the electrolysis current based on the copper ion concentration signal.

[0029] Compared with existing technologies, this invention organically integrates a "feedforward" benchmark based on concentration setting and a "fine-tuning" command based on potential feedback into the controller's decision logic. This design enables the system to comprehensively utilize macroscopic concentration information (reflecting material load) and microscopic potential information (reflecting reaction state) to make more scientific and comprehensive control decisions, achieving synergistic optimization under multiple parameters and objectives, and significantly improving the system's adaptability and overall robustness in the face of complex operating conditions. Detailed Implementation

[0030] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described in detail below. It should be noted that the following embodiments are only used to illustrate the implementation methods and typical parameters of the present invention, and are not intended to limit the parameter range described in the present invention. Reasonable variations derived therefrom are still within the protection scope of the claims of the present invention.

[0031] It should be noted that the endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0032] Unless otherwise defined, all terms, symbols, and other scientific terms used herein are intended to have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. In some instances, terms having a conventional meaning are defined herein for clarification or ease of reference, and such definitions should not be construed as indicating a significant difference from conventional understanding in the art. The technical methods described or referenced herein are generally well understood by those skilled in the art and employed by conventional methods. Unless otherwise stated, the use of commercially available kits, reagents, and instruments shall be performed according to the manufacturer's instructions and parameters. Example 1

[0033] This embodiment provides a copper refining and recycling method, which specifically includes the following steps: S1, Extraction: A copper-containing ammonia etching waste liquid produced by a PCB manufacturer was analyzed and found to contain: Cu 2+ Concentration 129.6 g / L, Cl - The concentration was 183.2 g / L, the total ammonia nitrogen was 155.3 g / L, and the density was 1.232 g / mL. This etching solution was mixed with 60% N910 extractant (diluted with carbonized kerosene) at a ratio of O / A = 2:1 and contacted in an extraction stirred tank at 30°C for 10 minutes. After standing and phase separation, a copper-loaded organic phase (copper concentration approximately 29.3 g / L) and a preliminarily copper-depleted etching aqueous phase (copper concentration approximately 45 g / L) were obtained.

[0034] S2, Back Extraction: The copper-loaded organic phase was mixed with a 3 mol / L sulfuric acid solution at a ratio of O / A = 1:1 and contacted in a stirred tank at 60°C for 10 minutes. After standing and phase separation, a copper-rich copper sulfate electrolyte (Cu) was obtained. 2+ The concentration of H2SO4 is approximately 200 g / L (approximately 50 g / L) and the regenerated organic phase is returned to the extraction process for recycling.

[0035] S3, Electrolysis: The aforementioned copper sulfate electrolyte was injected into an electrolytic cell, with a titanium plate as the cathode and a ruthenium-iridium coated titanium plate as the anode. The electrolyte temperature was controlled at 42°C, and the cathode current density was approximately 300 A / m. 2 During electrolysis, the electrolyte circulation flow rate remains constant. After 24 hours of continuous electrolysis, a dense, smooth metallic copper plate with a copper content of 99.95% is deposited at the cathode. The electrolyte solution after electrolysis contains Cu... 2+ When the concentration drops to 25 g / L, it is returned to the back-extraction process to continue contact with the newly generated loaded organic phase.

[0036] S4, Etching solution regeneration: The preliminary copper-deficient etching aqueous phase obtained in step S1 is transferred to the regeneration solution preparation tank, and samples are taken for analysis of its Cu content. 2+ Concentration, Cl - Concentration and pH value. Based on the analysis results, industrial-grade ammonium chloride, ammonia, and a special etching additive were added to adjust the concentration to: Cu 2+ Concentration ≤80 g / L, Cl - The concentration is 185 g / L, and the pH value is 9.4. After preparation, the solution is precisely filtered to obtain a regenerated etching solution, which is then pumped into the working tank of the etching production line to be mixed with the fresh etching solution for use. Example 2

[0037] Based on Example 1, the S3 electrolysis process was monitored and optimized in real time, specifically including: S31. Real-time monitoring: An online copper ion analyzer (range 0-100 g / L, accuracy ±0.5 g / L) and a redox potentiometer (composite Ag / AgCl reference electrode, measurement accuracy ±1 mV) were installed in the inlet line of the electrolysis unit. Continuous monitoring showed that the initial Cu in the copper sulfate electrolyte entering the electrolytic cell... 2+ The concentration was 52.3 g / L, and the redox potential was +0.15 V (vs. Ag / AgCl).

[0038] S32. Set the initial current reference value: The central controller receives the copper ion concentration signal and reads the built-in current-concentration reference table. Because the measured Cu... 2+ When the concentration is 52.3 g / L > 30 g / L, the controller automatically sets the initial reference value of the rectifier output current to 3200 A.

[0039] S33, Dynamic fine-tuning of potential: Two hours into electrolysis, the redox potential monitoring value rose to +0.18 V, exceeding the upper limit of the preset range (-0.2 V to +0.1 V). Based on its built-in potential fine-tuning algorithm, the central controller determined that the current system was too oxidizing, potentially promoting the oxidation of monovalent copper or anodic side reactions. It immediately issued a command to the rectifier to increase the current, adjusting in 50 A increments with 30-second intervals. When the current reached 3450 A, the redox potential began to decline; further adjustment to 3550 A stabilized the potential at +0.08 V, returning it to the preset range. The controller then stopped increasing the current and maintained this current value.

[0040] When the electrolysis has been carried out for 8 hours, Cu 2+When the concentration dropped to 28.7 g / L, the controller automatically reduced the current to 2800 A based on the reference meter. At this point, the redox potential monitoring value was -0.25 V, lower than the lower limit of the preset range. The controller determined that the system reduction was too strong, which could easily lead to hydrogen evolution or monovalent copper precipitation, and immediately executed a current reduction command, decreasing the current by 30 A at 20-second intervals. When the current dropped to 2650 A, the potential rose back to -0.12 V, entering the preset range, and the controller maintained this current value.

[0041] Furthermore, in this embodiment, a nitrogen inlet pipe is installed at the top of the copper sulfate electrolyte storage tank, continuously supplying nitrogen at a rate of 0.5m. 3 A flow rate of 99.9% pure nitrogen is introduced at a rate of / h to cover the liquid surface, maintain a slight positive pressure in the storage tank, and prevent air from entering. At the same time, the concentration of sulfuric acid in the electrolyte is sampled and tested every shift, and controlled at 200±5 g / L. If the concentration is insufficient, 98% concentrated sulfuric acid is added by the automatic acid dosing system.

[0042] Testing revealed that the electrolytic cell operated stably throughout the entire electrolysis cycle (28 days), with a smooth, pinkish surface on the cathode copper plate, free of burrs and nodules. Chemical analysis showed that the cathode copper contained 99.97% copper and only 32 ppm of chlorine impurities, far lower than conventional electrolytic products (typically >200 ppm). Current efficiency was increased by approximately 12% compared to traditional constant current electrolysis, and DC power consumption per ton of copper was reduced by 18%. Example 3

[0043] Based on Example 2, in step S1, the performance of the organic extractant is also monitored: Sampling and pretreatment: Every Tuesday and Friday morning, 500 mL of organic extractant sample is taken from the T2 oil tank of the running extraction system. The sample is allowed to stand for 30 minutes to allow any entrained aqueous phase to completely separate, and the clear oil phase in the middle layer is taken for analysis.

[0044] Copper absorption measurement: Accurately measure 50 mL of the oil sample to be tested into a 250 mL separatory funnel, add 50 mL of 20% sulfuric acid solution, stopper the funnel, mechanically shake for 10 minutes, allow to stand for 10 minutes to separate the layers, and discard the lower layer of sulfuric acid washing solution. Then measure 25 mL of etching working solution (Cu) from the production line's working cylinder. 2+ Add the 146 g / L concentration of the etching solution to the separatory funnel, shake for 10 minutes, let stand for 10 minutes to separate the layers, and remove the lower layer of etching solution (take a sample for analysis W2). Add 100 mL of deionized water to the separatory funnel, shake and wash, let stand for separation, discard the lower layer of wash water, and repeat the water washing once.

[0045] Back-extraction and titration: Add 50 mL of 20% sulfuric acid solution to the washed oil phase, shake for 10 minutes, and allow to stand for 10 minutes to separate the layers. Collect the lower copper sulfate back-extraction solution completely in a clean beaker. Accurately pipette 1.00 mL of this back-extraction solution into a 250 mL Erlenmeyer flask, add 50 mL of deionized water, and add 25% ammonia solution dropwise until the solution turns deep blue. Add approximately 0.02 g of ammonium purpurate indicator, shake well, and titrate with 0.1000 mol / L EDTA standard solution. The endpoint is reached when the solution changes from green to purple. Record the volume V (mL) of EDTA consumed. Calculate the amount of copper absorbed by the oil using the following formula: Copper absorption = V × 6.354 (g / L).

[0046] Copper entrainment measurement: After collecting the stripping solution as described above, add 50 mL of deionized water to the oil phase in the separatory funnel, shake for 5 minutes, let stand for 10 minutes to separate the layers, and discard the lower wash water. Then add 50 mL of 20% sulfuric acid solution, shake for 5 minutes, let stand for 10 minutes to separate the layers, collect the lower solution, and titrate the copper ion concentration using the same method to calculate the amount of copper entrained in the oil.

[0047] Status assessment and adjustment: On Tuesday, the copper absorption of the T2 cylinder sample was measured at 16.8 g / L, with a copper entrainment of 0.35 g / L. Compared to the process control standard (copper absorption 12-20 g / L), the extractant condition was deemed normal. On Friday, a retest showed the copper absorption had decreased to 11.2 g / L, below the lower control limit. Investigation revealed a leak in the extractant circulation pump seal, causing some oil phase loss. After adding fresh extractant and repairing the pump, a new sample was taken, and the copper absorption recovered to 14.7 g / L. Simultaneously, based on the recent week's trend of decreasing copper absorption, the extraction ratio (O / A) was slightly adjusted from 2.0:1 to 2.2:1 to maintain extraction efficiency. Example 4

[0048] Based on Example 3, in step S4, during component preparation, the chloride ion concentration of the regenerated etching solution is controlled within the range of 175-200 g / L, and its pH value is controlled within the range of 9.1-9.7. Specifically, the steps include the following: Regenerated solution preparation: Take 5000 L of the preliminary copper-deficient etching aqueous phase obtained in step S1 into a T8 mixing tank, turn on the stirrer, and rotate at 250 rpm. Sampling analysis revealed: Cu 2+ Concentration 70.5 g / L, Cl - Concentration 182 g / L, pH 9.0.

[0049] According to the quality control objectives (Cl) -Within the lower limit range of 175-200 g / L and the upper limit range of pH 9.1-9.7, the following calculations and additions were performed: Chloride ion regulation: Target Cl - The concentration is 186 g / L, which needs to be increased by 4 g / L. Based on a volume of 5000 L, a total of 20 kg of chloride ions needs to be added. Using industrial-grade ammonium chloride (66% chloride content), the calculated amount to be added is: 20 kg ÷ 0.66 ≈ 30.3 kg. Accurately weigh 30.5 kg of ammonium chloride, dissolve it in a small amount of regeneration solution, and add it to the mixing tank.

[0050] pH adjustment: The target pH value is 9.4, which needs to be increased by 0.4 units. Based on experience data from the work instructions, adding 25 kg of liquid ammonia will increase the pH value by approximately 0.06 units. The calculated amount of liquid ammonia to be added is: (0.4 ÷ 0.06) × 25 ≈ 166.7 kg. 167 kg of liquid ammonia is slowly added using the liquid ammonia metering and dispensing device, with the addition time controlled within 40 minutes.

[0051] Additive supplements: Add 15 L of etching-specific additive according to the company's standard ratio.

[0052] Homogenization and Testing: Continue stirring for 30 minutes, and after the system is fully homogenized, take another sample for analysis. The results show that Cu 2+ Concentration 70.2 g / L, Cl - The concentration was 186.5 g / L, and the pH value was 9.38. All indicators met the internal control standards for the regeneration etching solution.

[0053] After testing, this batch of regenerated etching solution, after being pumped to the etching machine, ran continuously for 72 hours with a stable etching rate and normal lateral etching volume. Two weeks after system operation, an inspection revealed no significant crystallization scale adhering to the extraction tank, regenerated solution storage tank, and inner walls of the pipelines. This was significantly lower than the control batch (Cl...) that did not undergo chloride ion and pH pre-control. - (195 g / L, pH 9.0) significantly improved cleanliness. Example 5

[0054] This embodiment provides a copper refining and recycling system, including: Extraction apparatus: Three-stage countercurrent mixing and clarification tank, single-stage mixing chamber volume 5 m³ 3 The clarification chamber has an area of ​​12 m². 2 ; Back-extraction unit: Two-stage countercurrent mixing and clarification tank, made of 316L stainless steel; Electrolysis unit: 8 vertical electrolytic cells operating in parallel, each with a cathode area of ​​2.5 m². 2Configured with a 20000 A / 12 V high-frequency switching rectifier; Regenerated liquid preparation unit: 2 units of 30 m³ 3 Glass-lined mixing tank, equipped with an automatic weighing and metering feeding system; Optimized control system: Siemens S7-1500 series PLC serves as the central controller, with a copper ion online analyzer (Hash APA6000) and an industrial redox potentiometer (Mettler Thornton) configured at the front end. The rectifier communicates with the PLC via the Profibus-DP bus.

[0055] The system operated continuously for 6 months, producing a total of 520 tons of cathode copper. The average DC power consumption per ton of copper was 2180 kWh, the average purity of the cathode copper was 99.96%, and the average chlorine impurity content was 41 ppm. The regenerated etching solution was 100% reused in the etching production line, and the etching speed and etching factor were not significantly different from those of the new solution batches.

[0056] In summary, this invention provides a copper refining and recovery system and method. Through a systematic intelligent upgrade and refined reconstruction of the traditional "extraction-back-extraction-electrolysis-regeneration" process framework, it achieves full-process optimization, efficiently recovering metallic copper from etching waste liquid and simultaneously regenerating the etching solution. In the electrolysis process, by introducing real-time monitoring of both redox potential and copper ion concentration, a closed-loop intelligent control strategy of "concentration as the baseline and potential as the fine-tuning" is constructed, fundamentally suppressing the generation of monovalent copper ions and significantly improving the purity of cathode copper and electrolysis efficiency. In the extraction process, the quantitative analysis of extractant performance is integrated into standardized monitoring steps, using key indicators such as copper absorption to achieve health status diagnosis and predictive maintenance of the extraction unit. In the regeneration process, based on the side reaction mechanism, the etching solution preparation parameters are pre-controlled at the source, significantly reducing the system's tendency to crystallize and scale, and improving the stability of the regenerated solution for reuse. This invention also provides a dedicated system integrating the above-mentioned process innovations. Through the collaborative work of online monitoring, central control, and execution modules, the process innovations are fully transformed into a stable and reliable industrial solution. This invention is not a partial repair of a single link, but a multi-dimensional, cross-unit collaborative optimization of the entire recycling system, which significantly improves the purity of copper recovery, the stability of system operation and the efficiency of resource recycling, and has good industrialization prospects and application value.

[0057] While the disclosure is as stated above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of this disclosure, and all such changes and modifications will fall within the protection scope of this invention.

Claims

1. A method for copper refining and recycling, characterized in that, Includes the following steps: Step S1, Extraction: The copper-containing ammonia etching solution is brought into contact with an organic extractant to transfer copper ions to the organic phase, resulting in a copper-loaded organic phase and a preliminary copper-poor etching aqueous phase. Step S2, back-extraction: The copper-loaded organic phase is back-extracted with sulfuric acid solution to obtain a copper sulfate electrolyte rich in copper ions and a regenerated organic phase; Step S3, Electrolysis: Electrolysis is performed on a copper sulfate electrolyte rich in copper ions to obtain metallic copper at the cathode; Step S4, Etching solution regeneration: The composition of the initially copper-poor etching aqueous phase is adjusted to obtain a regenerated etching solution.

2. The copper refining and recovery method according to claim 1, characterized in that, In step S3, the electrolysis process is monitored and optimized in real time, and this process includes: Step S31: Monitor the copper ion concentration and redox potential of the copper sulfate electrolyte in real time; Step S32: Set the initial reference value of the electrolysis current based on the monitored copper ion concentration; Step S33: Dynamically fine-tune the electrolysis current based on the monitored redox potential to maintain the redox potential within a preset range.

3. The copper refining and recycling method according to claim 2, characterized in that, In step S32, the reference relationship for setting the initial reference value of the electrolysis current based on the monitored copper ion concentration is as follows: When Cu 2+ When the concentration is greater than 10 g / L and less than or equal to 15 g / L, the current should be set to 700-1000A; When Cu 2+ When the concentration is greater than 15 g / L and less than or equal to 30 g / L, the current should be set to 1000-3000A; When Cu 2+ When the concentration is >30 g / L, the current should be set to 3000-3500A.

4. The copper refining and recycling method according to claim 2, characterized in that, In step S33, the preset range is -0.2V to +0.1V; Furthermore, when the redox potential exceeds the upper limit of the range, the electrolysis current is increased; When the current is below the lower limit of the range, reduce the electrolysis current.

5. The copper refining and recovery method according to claim 1, characterized in that, In step S1, the performance of the organic extractant is also monitored: samples are taken periodically, and the extractant is treated and titrated with sulfuric acid, etching working solution, water and sulfuric acid in sequence using the separatory funnel method to determine the amount of copper absorbed, the amount of copper eluted and the amount of copper entrained, and the state of the extractant is determined or the oil-water ratio is adjusted based on the results.

6. The copper refining and recycling method according to claim 1, characterized in that, In step S3, an inert gas is introduced to cover the liquid surface during the storage or transportation of the copper sulfate electrolyte; and / or, The concentration of sulfuric acid in the copper sulfate electrolyte is controlled to be 190-220 g / L.

7. The copper refining and recycling method according to claim 1, characterized in that, In step S4, during component preparation, the chloride ion concentration of the regenerated etching solution is controlled within the range of 175-200 g / L, while its pH value is controlled within the range of 9.1-9.

7.

8. A copper refining and recovery system for implementing the copper refining and recovery method according to any one of claims 1-7, characterized in that, include: An extraction device is used to mix and separate copper-containing etching solutions from organic extractants; A back-extraction device, connected to the extraction device, is used for back-extracting a loaded organic phase with sulfuric acid; An electrolysis device, connected to the back-extraction device, is used for electrolyzing copper sulfate solution; A regeneration solution preparation device, connected to the extraction device, is used to treat the initial copper-poor etching aqueous phase.

9. The copper refining and recovery system according to claim 8, characterized in that, It also includes an optimization control system; the optimization control system includes: An online electrolyte monitoring module, wherein the sensors are installed in the inlet pipe or electrolytic cell of the electrolysis device, includes at least an online copper ion analyzer and a redox potentiometer; The central controller receives signals from the monitoring module and has a built-in potential fine-tuning algorithm. The execution module is electrically connected to the central controller and the rectifier of the electrolysis device; The potential fine-tuning algorithm is configured to dynamically adjust the electrolysis current based on the redox potential signal.

10. The copper refining and recovery system according to claim 9, characterized in that, The central controller also has a built-in current-concentration reference table, which is used to set the initial reference value of the electrolysis current based on the copper ion concentration signal.