A method for regenerating and reusing copper nitrate stripping waste liquid

Abstract

This invention provides a method for regenerating and reusing copper nitrate stripping wastewater. The method includes the following steps: providing copper nitrate stripping wastewater; mixing the wastewater with additives and electrolyzing it to obtain metallic copper and an electrolyzed solution; the additives include sulfamic acid and urea; and replenishing the electrolyzed solution with acid to obtain a regenerated copper nitrate stripping solution. This invention adds sulfamic acid and urea, which are well-compatible with the copper nitrate stripping wastewater, as additives. Through their synergistic effect, the efficiency of copper extraction via electrolysis is significantly improved, achieving high-efficiency and high-value copper recovery, and increasing the acidity of the electrolyzed solution. Furthermore, only a small amount of acid replenishment is needed to restore the copper stripping capacity, greatly reducing acid consumption and achieving low-cost recycling. This method is simple, has a high resource recovery rate, and can effectively reduce the raw material and environmental costs of the copper stripping process, offering both economic and environmental benefits.

Description

Technical Field

[0001] This invention belongs to the field of copper nitrate waste liquid recycling technology, specifically relating to a method for regenerating and reusing copper nitrate stripping waste liquid. Background Technology

[0002] In the copper stripping process of the electroplating industry, copper nitrate solution is widely used due to its strong oxidizing properties and good copper stripping effect. Its principle is that nitrate ions oxidize metallic copper under acidic conditions, causing the copper plating layer to enter the solution in the form of copper ions. However, as the copper stripping reaction continues, the concentration of copper ions in the solution continuously increases, a large amount of free nitric acid is consumed, and the acidity of the solution continuously decreases. Ultimately, this causes the copper nitrate solution to lose its etching and copper stripping ability, becoming waste liquid.

[0003] Currently, there are three main methods for treating this type of copper nitrate stripping waste liquid: direct discharge, simple acid replenishment and reuse, and chemical precipitation treatment. Direct discharge not only results in a large waste of copper nitrate raw materials, but also causes serious water pollution problems due to the high concentration of copper ions and nitrate ions in the waste liquid, and the cost of treating hazardous waste is high. Although simply adding nitric acid can temporarily restore some acidity, the high concentration of copper ions in the solution cannot be removed, which still leads to poor etching and copper stripping ability and short bath life. Chemical precipitation removes copper ions by adding precipitants, but it generates a large amount of copper sludge hazardous waste, destroys the effective components in the solution, consumes a lot of acid, is prone to secondary pollution, and has poor regeneration effect.

[0004] In addition, electrolysis has become the mainstream approach for treating copper nitrate waste liquid because it can recover copper ions and regenerate the solution. However, conventional electrolysis processes have problems such as low current efficiency, insufficient recovery of the etching capacity of the solution after electrolysis, and poor matching of additive selection and dosage. They are prone to cathode copper back-etching and low etching rate of the regenerated solution, making it difficult to meet the needs of industrial recycling.

[0005] Therefore, how to further improve the electrolytic copper extraction efficiency of copper nitrate stripping waste liquid and significantly restore the etching ability of the regenerated solution to meet the needs of industrial recycling is an urgent technical problem to be solved. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a method for the regeneration and reuse of copper nitrate stripping wastewater. This invention utilizes the addition of sulfamic acid and urea as additives. Through their synergistic effect, not only do the additives exhibit excellent compatibility with the copper nitrate stripping wastewater, but the electrolytic copper extraction efficiency is also significantly improved. The current efficiency for electrolytic copper extraction exceeds 90%, resulting in significant copper ion extraction and achieving efficient and high-value recovery of copper ions. Simultaneously, the acidity of the solution after electrolysis is effectively increased. Based on this, only a small amount of acid replenishment is needed to adjust the solution acidity to the process value, thereby restoring its copper stripping capacity. This not only significantly reduces the consumption of acid replenishment materials and lowers production costs, but also allows for direct reuse in the electroplating copper stripping process, achieving low-cost recycling and reuse of the copper nitrate stripping solution. This method is simple to operate, has a high resource recovery rate, and can effectively reduce the raw material costs and environmental treatment costs of the copper stripping process in the electroplating industry, achieving both economic and environmental benefits.

[0007] To achieve this objective, the present invention employs the following technical solution: In a first aspect, the present invention provides a method for regenerating and reusing copper nitrate stripping waste liquid, the method comprising the following steps: We provide copper nitrate stripping waste liquid.

[0008] The copper nitrate stripping waste liquid and additives are mixed and electrolyzed to obtain metallic copper and an electrolyzed solution; wherein the additives include aminosulfonic acid and urea.

[0009] The electrolyzed solution is then acidified to obtain a regenerated copper nitrate copper stripping solution.

[0010] This invention utilizes sulfamic acid and urea as additives. Through their synergistic effect, the additives not only exhibit excellent compatibility with copper nitrate stripping wastewater but also significantly improve the efficiency of electrolytic copper extraction. The current efficiency of electrolytic copper extraction exceeds 90%, resulting in remarkable copper ion extraction and achieving efficient, high-value recovery of copper ions. Simultaneously, it effectively increases the acidity of the post-electrolysis solution. Furthermore, only a small amount of acid replenishment is needed to adjust the solution acidity to the process value, thereby restoring its copper stripping capacity. This significantly reduces the consumption of acid replenishment materials, lowering production costs, and allows for direct reuse in the electroplating copper stripping process, achieving low-cost recycling and reuse of the copper nitrate stripping solution. This method is simple to operate, has a high resource recovery rate, and effectively reduces the raw material and environmental treatment costs of the copper stripping process in the electroplating industry, offering both economic and environmental benefits.

[0011] This invention uses a combination of aminosulfonic acid and urea as additives. During electrolysis, aminosulfonic acid preferentially reacts with free nitrate ions, inhibiting the reduction side reaction of nitrate ions at the cathode. At the same time, the hydrogen ions generated by its decomposition can effectively increase the acidity of the solution after electrolysis. Urea, as a cathode surfactant, can be adsorbed at the electrode interface, promoting the uniform deposition of copper ions, inhibiting the formation of dendrites and passivation layers, and preventing intermediate products such as nitrous acid from interfering with the electrolysis process. The synergistic effect of the two significantly improves the compatibility of the additive with the copper nitrate stripping solution while improving current efficiency, achieving efficient copper recovery and controllable acidity regeneration of the solution.

[0012] In the electrolysis process of this invention, copper ions are reduced and deposited at the cathode to recover copper resources, while hydrogen ions are generated by the oxidation of water at the anode, which increases the acidity of the solution. At the same time, the additives can effectively prevent the back corrosion of copper at the cathode and ensure electrolysis efficiency.

[0013] It should be noted that the present invention does not specifically limit the source of copper nitrate stripping waste liquid. For example, it can be aged copper nitrate stripping solution generated from the copper stripping process in the electroplating industry.

[0014] Preferably, the concentration of copper ions in the copper nitrate stripping waste liquid is ≥100g / L, for example, it can be 100g / L, 150g / L or 200g / L, etc., and the acidity is ≤1.5mol / L, for example, it can be 1.5mol / L, 1.0mol / L or 0.5mol / L, etc.

[0015] It should be noted that acidity refers to the concentration of hydrogen ions (H+) in the solution. + The molar concentration of a substance is expressed in mol / L.

[0016] Preferably, the amount of aminosulfonic acid added is 0.5-1.5 wt% of the mass of the copper nitrate stripping waste liquid, for example, it can be 0.5 wt%, 1.0 wt%, or 1.5 wt%.

[0017] Preferably, the amount of urea added is 1.5-2.5 wt% of the mass of the copper nitrate stripping waste liquid, for example, it can be 1.5 wt%, 2.0 wt%, or 2.5 wt%.

[0018] Preferably, the mass ratio of aminosulfonic acid to urea is (0.3-0.6):1, for example, it can be 0.3:1, 0.4:1, 0.5:1 or 0.6:1, etc.

[0019] Preferably, the mixing process is accompanied by stirring, and the stirring rate is 30-60 rpm, for example, 30 rpm, 40 rpm, 50 rpm or 60 rpm.

[0020] Preferably, the mixing time is ≥30 min, for example, 30 min, 45 min, or 60 min. Sufficient mixing time ensures that the additive and copper nitrate stripping waste liquid are fully mixed, avoiding uneven local concentrations that could affect the electrolysis effect.

[0021] Preferably, during the electrolysis process, the electrolysis temperature is ≤25℃, for example, it can be 25℃, 20℃ or 15℃, and more preferably 20-25℃.

[0022] This invention controls the electrolysis temperature to ≤25℃, which can avoid the back corrosion of the cathode copper. If the temperature is too high, it will accelerate the chemical dissolution of copper (i.e., aggravate back corrosion) and promote the reduction side reaction of nitrate ions, resulting in a decrease in current efficiency and copper recovery rate, which will affect the stability of the operating environment and the electrolysis system.

[0023] Preferably, during the electrolytic treatment, the current density is 100-300 A / m. 2 For example, it could be 100A / m 2 200A / m 2 or 300A / m 2 wait.

[0024] In this invention, a suitable current density is beneficial for maintaining the uniform and dense deposition of cathode copper, while suppressing the reduction side reactions of impurities such as nitrate, thereby improving current efficiency and copper recovery rate.

[0025] Preferably, the purity of the copper is ≥99%, for example, it can be 99%, 99.2%, 99.5%, 99.6% or 99.8%, etc.

[0026] Preferably, the average particle size of the metallic copper is 5-50 μm, for example, it can be 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm or 50 μm, etc.

[0027] This invention, through the synergistic effect of appropriate electrolysis process and additives, enables the metallic copper deposited on the cathode to achieve a purity of ≥99% and an average particle size of 5-50μm. Furthermore, the surface is flat and dense, easy to peel off, and convenient for subsequent direct reuse or external sale, further enhancing the recycling value of copper resources.

[0028] It should be noted that purity can be tested using inductively coupled plasma optical emission spectrometry (ICP-OES), and average particle size can be tested using laser particle size analysis.

[0029] Preferably, the concentration of copper ions in the solution after electrolysis is ≤10g / L, for example, it can be 9g / L, 8g / L, 7g / L, 6g / L, 5g / L, 4g / L or 3g / L, etc.

[0030] It should be noted that the concentration of copper ions in the solution can be tested using the ICP-OES method.

[0031] Preferably, the acidity of the solution after electrolysis is ≥3.25 mol / L, for example, it can be 3.3 mol / L, 3.5 mol / L or 4 mol / L, etc.

[0032] This invention achieves a copper ion concentration ≤10g / L and an acidity >3.25mol / L in the solution after electrolysis through the synergistic effect of a suitable electrolysis process and additives. This indicates that the copper ions have been efficiently extracted and the acidity of the solution has significantly recovered. Only a small amount of acid replenishment is needed to meet the acidity requirements of the copper stripping process again, providing favorable conditions for the low-cost recycling and regeneration of copper nitrate stripping solution.

[0033] Preferably, the acid replenishing solution used in the acid replenishing process includes concentrated nitric acid.

[0034] Preferably, the acidity of the regenerated copper nitrate copper stripping solution is 6.5-7.5 mol / L, for example, it can be 6.5 mol / L, 7 mol / L or 7.5 mol / L, etc.

[0035] Preferably, the regeneration and reuse method includes the following steps: (1) Provide copper nitrate stripping waste liquid.

[0036] The copper ion concentration in the copper nitrate stripping waste liquid is ≥100g / L, and the acidity is ≤1.5mol / L.

[0037] (2) Mix aminosulfonic acid and urea, then add them to the copper nitrate stripping waste liquid, and stir at a rate of 30-60 rpm for ≥30 min to obtain a mixed solution.

[0038] The amount of aminosulfonic acid added is 0.5-1.5 wt% of the mass of the copper nitrate stripping waste liquid; the amount of urea added is 1.5-2.5 wt% of the mass of the copper nitrate stripping waste liquid; and the mass ratio of aminosulfonic acid to urea is (0.3-0.6):1.

[0039] (3) Transfer the mixed solution to a diaphragmless electrolytic cell and apply it at a current density of 100-300 A / m 2 Under the condition of electrolysis temperature ≤25℃, constant current electrolysis is carried out for 960-1020min (e.g., 960min, 1000min or 1020min, etc.) to reduce and deposit metallic copper at the cathode, and at the same time obtain the electrolytic solution.

[0040] The anode of the diaphragmless electrolytic cell includes a titanium plate, and the cathode includes a copper sheet; the purity of the metallic copper is ≥99%, and the average particle size is 5-50μm; the concentration of copper ions in the electrolytic solution is ≤10g / L; and the acidity of the electrolytic solution is ≥3.25mol / L.

[0041] (4) The electrolyzed solution is mixed with an acid replenishing solution with a concentration of 15-15.8 mol / L (e.g., 15 mol / L, 15.5 mol / L or 15.8 mol / L) to replenish the acid, thereby obtaining a regenerated copper nitrate copper stripping solution with an acidity of 6.5-7.5 mol / L.

[0042] The acid replenishing solution includes concentrated nitric acid.

[0043] Secondly, the present invention provides a system for regenerating and reusing copper nitrate stripping waste liquid, wherein the regeneration and reuse method described in the first aspect is carried out in the regeneration and reuse system.

[0044] The recycling system includes a raw material storage unit, an electrolysis unit, and a regeneration liquid unit connected in sequence; wherein, the raw material storage unit is used to store copper nitrate stripping waste liquid and additives.

[0045] Preferably, the regeneration and reuse system further includes an acid replenishment unit and a tail gas treatment device. The acid replenishment unit is used to provide acid replenishment solution to the regenerated liquid unit, and the tail gas treatment device is used to treat the tail gas generated by the electrolysis unit during the electrolysis process.

[0046] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0047] Compared with the prior art, the present invention has the following beneficial effects: (1) By adding aminosulfonic acid and urea as additives, the additives have good compatibility with copper nitrate stripping waste liquid and significantly improve the efficiency of electrolytic copper extraction. The current efficiency of electrolytic copper extraction exceeds 90%, and the copper ion extraction effect is significant, realizing the efficient and high-value recovery of copper ions. At the same time, the acidity of the solution after electrolysis is effectively improved. On this basis, only a small amount of acid needs to be added to adjust the acidity of the solution to the process value, thereby restoring its copper stripping ability. This not only greatly reduces the consumption of acid raw materials and reduces production costs, but also allows it to be directly reused in the electroplating copper stripping process, realizing the low-cost recycling and reuse of copper nitrate stripping solution.

[0048] (2) The recycling and reuse method provided by the present invention is simple to operate, has a high resource recovery rate, and generates no hazardous waste in the entire process. It can effectively reduce the raw material cost and environmental treatment cost of the copper stripping process in the electroplating industry, and has both economic and environmental benefits. Attached Figure Description

[0049] Figure 1 This is a process flow diagram provided in Embodiment 1 of the present invention. Detailed Implementation

[0050] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0051] The scope of this invention can be defined by lower and upper limits. The selected lower and upper limits define the boundaries of a specific range. The range defined in this way can be defined by the inclusion or exclusion of endpoints. Any endpoint can be independently selected for inclusion or exclusion, and all lower and upper limits can be arbitrarily combined to form new ranges. That is, any lower limit can be combined with any upper limit to form an effective range. For example, if the ranges of 60~120 and 80~110 are listed for specific parameters, it should be understood that the ranges of 60~110 and 80~120 also fall within the scope of this invention. In addition, if the minimum range values ​​1 and 2 are listed, and the maximum range values ​​3, 4 and 5 are also listed, then all ranges of 1~3, 1~4, 1~5, 2~3, 2~4 and 2~5 fall within the scope of this invention. In this invention, the numerical range "a~b" represents a shortened representation of any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "0~5" means that all real numbers between 0 and 5 have been fully listed in this document, and "0~5" is only a shortened representation of this set of numerical combinations. When a parameter is expressed as an integer ≥2, it is equivalent to listing positive integers that meet the requirements, such as 2, 3, 4, 5, 6, 7, 8, 9, 10, etc. When a parameter is expressed as an integer selected from "2~10", it is equivalent to listing any integer among 2, 3, 4, 5, 6, 7, 8, 9, and 10.

[0052] In this invention, "a combination of at least two" refers to a quantity greater than or equal to 2 unless otherwise specified. For example, "any one or a combination of at least two" means that any one of the listed items can be selected, or a combination of at least two of the listed items formed in a manner that does not conflict and enables the implementation of this invention. In this invention, unless otherwise specified, the features or solutions corresponding to "and / or" cover any one of two or more related listed items, as well as any and all combinations of the related listed items. The arbitrary and all combinations include any two related listed items, any more related listed items, or a combination of all related listed items. For example, "A and / or B" means a set consisting of A, B, and combinations of A and B, where "containing A and / or B" can be understood, depending on the context of the statement, as containing A, containing B, or simultaneously containing both A and B. In this invention, "optional" means that the corresponding feature, component, step or solution is not necessary, that is, it is selected from either "with" or "without". If there are multiple "optional" limitations in a technical solution, unless otherwise specified and there is no technical conflict or mutual constraint, each "optional" limitation is independent and does not affect the others.

[0053] In this invention, technical features or solutions described using open-ended terms such as "comprising" or "including" do not exclude additional non-conflicting elements beyond the listed elements unless otherwise specified. They are considered to disclose both closed-ended features or solutions consisting solely of the listed elements and open-ended features or solutions that may include additional non-conflicting elements beyond the listed elements. For example, if A includes a1, a2, and a3, unless otherwise specified, this means that A can consist only of a1, a2, and a3, or it can include other non-conflicting elements based on a1, a2, and a3. This corresponds to the disclosure of technical solutions such as "A consists of a1, a2, and a3," "A is selected from a1, a2, and a3," and "A not only includes a1, a2, and a3, but may also include other non-conflicting elements." All embodiments and optional embodiments of this invention, unless otherwise specified and without technical conflict, can be combined to form new technical solutions, and such combinations fall within the scope of this invention. The term "embodiment" as used in this invention means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment or implementation of the invention. The appearance of this phrase in various locations throughout the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art will understand, explicitly and implicitly, that the embodiments described in this invention can be combined with other embodiments that do not conflict with the technology. The ordinal numbers "first," "second," "third," and "fourth," etc., used in the expressions "first aspect," "second aspect," "third aspect," and "fourth aspect" in this invention are for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly specifying the importance or quantity of the indicated technical features. They serve only as a non-exhaustive enumeration and do not constitute a closed limitation on quantity.

[0054] In this invention, the order in which the steps are written in the methods described in each embodiment does not imply a strict execution order. The actual execution order of each step should be determined based on its function and possible internal logic. Unless otherwise specified, all steps of this invention can be executed in the order they are written, or in any order without technical conflict. For example, if the method includes steps (a) and (b), it means that the method may include steps (a) and (b) executed sequentially, or it may include steps (b) and (a) executed sequentially. If the method also includes step (c), then step (c) can be added to the method in any order without conflict, including but not limited to the execution order of steps (a), (b), and (c), steps (a), (c), and (b), steps (c), (a), and (b), etc.

[0055] Example 1 This embodiment provides a method for regenerating and reusing copper nitrate stripping waste liquid, the process flow diagram of which is shown below. Figure 1As shown, the regeneration and reuse method includes the following steps: (1) Provide copper nitrate stripping waste liquid; the copper nitrate stripping waste liquid is taken from the aged copper nitrate stripping liquid generated in the copper stripping process of the electroplating industry; the concentration of copper ions in the aged copper nitrate stripping liquid is 101 g / L and the acidity is 1.3 mol / L.

[0056] (2) Mix aminosulfonic acid and urea, then add them to the copper nitrate stripping waste liquid, and stir at a rate of 40 rpm for 35 min to obtain a mixed solution.

[0057] The amount of aminosulfonic acid added is 1 wt% of the mass of the copper nitrate stripping waste liquid; the amount of urea added is 2.0 wt% of the mass of the copper nitrate stripping waste liquid; and the mass ratio of aminosulfonic acid to urea is 0.5:1.

[0058] (3) The mixed solution is transferred to a diaphragmless electrolytic cell and subjected to a current density of 250 A / m 2 Under the condition of electrolysis temperature of 25℃, constant current electrolysis is carried out for 960 minutes to reduce and precipitate metallic copper at the cathode, and at the same time, the electrolytic solution and waste gas are obtained.

[0059] The anode of the diaphragmless electrolytic cell is a titanium plate, and the cathode is a copper sheet; the purity of the metallic copper is 99.2%, and the average particle size is 40 μm; the concentration of copper ions in the electrolytic solution is 10 g / L; and the acidity of the electrolytic solution is 3.4 mol / L.

[0060] (4) The electrolyzed solution is mixed with concentrated nitric acid with a concentration of 15.5 mol / L to replenish the acid, resulting in a regenerated copper nitrate solution with an acidity of 7 mol / L.

[0061] Example 2 This embodiment provides a method for regenerating and reusing copper nitrate stripping waste liquid, which includes the following steps: (1) Provide the same copper nitrate stripping waste liquid as in Example 1.

[0062] (2) Mix aminosulfonic acid and urea, then add them to the copper nitrate stripping waste liquid, and stir at a rate of 40 rpm for 35 min to obtain a mixed solution.

[0063] The amount of aminosulfonic acid added is 0.8 wt% of the mass of the copper nitrate stripping waste liquid; the amount of urea added is 2.0 wt% of the mass of the copper nitrate stripping waste liquid; and the mass ratio of aminosulfonic acid to urea is 0.4:1.

[0064] (3) The mixed solution is transferred to a diaphragmless electrolytic cell and subjected to a current density of 250 A / m 2 Under the condition of electrolysis temperature of 25℃, constant current electrolysis is carried out for 960 minutes to reduce and precipitate metallic copper at the cathode, and at the same time, the electrolytic solution and waste gas are obtained.

[0065] The anode of the diaphragmless electrolytic cell is a titanium plate, and the cathode is a copper sheet; the purity of the metallic copper is 99.1%, and the average particle size is 40 μm; the concentration of copper ions in the electrolytic solution is 10 g / L; and the acidity of the electrolytic solution is 3.3 mol / L.

[0066] (4) The electrolyzed solution is mixed with concentrated nitric acid with a concentration of 15.5 mol / L to replenish the acid, resulting in a regenerated copper nitrate solution with an acidity of 7 mol / L.

[0067] Example 3 The difference between this embodiment and Embodiment 1 is that the amount of aminosulfonic acid added is adjusted to 0.5 wt%, so that the mass ratio of aminosulfonic acid to urea is 0.2:1.

[0068] The remaining recycling methods and parameters are consistent with those in Example 1.

[0069] Example 4 The difference between this embodiment and Embodiment 1 is that the amount of aminosulfonic acid added is adjusted so that the mass ratio of aminosulfonic acid to urea is 0.1:1.

[0070] The remaining recycling methods and parameters are consistent with those in Example 1.

[0071] Example 5 The difference between this embodiment and Embodiment 1 is that the amount of aminosulfonic acid added is adjusted so that the mass ratio of aminosulfonic acid to urea is 1:1.

[0072] The remaining recycling methods and parameters are consistent with those in Example 1.

[0073] Example 6 The difference between this embodiment and Embodiment 1 is that the electrolysis temperature is set to 35°C during the electrolysis process.

[0074] The remaining recycling methods and parameters are consistent with those in Example 1.

[0075] Example 7 The difference between this embodiment and Embodiment 1 is that the current density during the electrolytic treatment is 50 A / m. 2 .

[0076] The remaining recycling methods and parameters are consistent with those in Example 1.

[0077] Example 8 The difference between this embodiment and Embodiment 1 is that the current density during the electrolytic treatment is 400 A / m. 2 .

[0078] The remaining recycling methods and parameters are consistent with those in Example 1.

[0079] Comparative Example 1 The difference between this comparative example and Example 1 is that aminosulfonic acid is replaced with an equal mass of urea.

[0080] The remaining recycling methods and parameters are consistent with those in Example 1.

[0081] Comparative Example 2 The difference between this comparative example and Example 1 is that urea is replaced with an equal mass of aminosulfonic acid.

[0082] The remaining recycling methods and parameters are consistent with those in Example 1.

[0083] Performance testing I. The metallic copper and the electrolytic solution obtained in the recycling and reuse methods provided in the above embodiments and comparative examples are characterized, including the purity and average particle size of the metallic copper, as well as the copper ion concentration and acidity in the electrolytic solution.

[0084] 2. Conduct current efficiency tests for electrolytic copper extraction. The calculation formula is as follows: Current efficiency (%) = (actual mass of deposited copper / theoretical mass of deposited copper) × 100%.

[0085] The characterization results are shown in Table 1.

[0086] Table 1 analyze: As shown in Table 1, this invention, by adding sulfamic acid and urea as additives, achieves excellent compatibility with copper nitrate stripping waste liquid. This significantly improves the efficiency of copper extraction via electrolysis, with a current efficiency exceeding 90% and remarkable copper ion extraction, resulting in efficient and high-value recovery of copper ions. Simultaneously, it effectively increases the acidity of the solution after electrolysis. Based on this, only a small amount of acid replenishment is needed to adjust the solution acidity to the process value, thereby restoring its copper stripping capacity. This not only significantly reduces the consumption of acid replenishment materials and lowers production costs but also allows for direct reuse in the copper stripping process, achieving low-cost recycling and reuse of the copper nitrate stripping solution. This method is simple to operate, has a high resource recovery rate, and effectively reduces the raw material and environmental treatment costs of the copper stripping process in the electroplating industry, offering both economic and environmental benefits.

[0087] As can be seen from the comparison between Example 1 and Examples 3-5, if the mass ratio of aminosulfonic acid to urea is too small, the copper nitrate solution cannot be effectively electrolyzed; if the mass ratio of aminosulfonic acid to urea is too large, the regenerated solution after electrolysis has no etching ability and cannot be reused.

[0088] As can be seen from the comparison between Example 1 and Example 6, if the electrolysis temperature is too high during the electrolysis process, the cathode electrolytic copper cannot be deposited normally and will be etched away.

[0089] As can be seen from the comparison between Example 1 and Examples 7-8, if the current density is too low during the electrolytic process, the electrolytic copper efficiency will be too slow; if the current density is too high during the electrolytic process, the chemical temperature will rise too quickly, causing the cathode copper to be etched back.

[0090] As can be seen from the comparison between Example 1 and Comparative Example 1, if only urea is used as an additive, the copper nitrate solution cannot be effectively electrolyzed.

[0091] As can be seen from the comparison between Example 1 and Comparative Example 2, if only aminosulfonic acid is used as an additive, the electrolysis efficiency is too low.

[0092] It should be noted that the present invention is illustrated through the above embodiments, but the present invention is not limited to the above process steps, that is, it does not mean that the present invention must rely on the above process steps to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials used in the present invention, additions of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for regenerating and reusing copper nitrate stripping waste liquid, characterized in that, The recycling method includes the following steps: Provide copper nitrate stripping waste solution; The copper nitrate stripping waste liquid and additives are mixed and electrolyzed to obtain metallic copper and an electrolyzed solution; wherein the additives include aminosulfonic acid and urea. The electrolyzed solution is then acidified to obtain a regenerated copper nitrate copper stripping solution.

2. The recycling method according to claim 1, characterized in that, The copper ion concentration in the copper nitrate stripping waste liquid is ≥100g / L, and the acidity is ≤1.5mol / L.

3. The recycling method according to claim 1 or 2, characterized in that, The amount of aminosulfonic acid added is 0.5-1.5 wt% of the mass of the copper nitrate stripping waste liquid; And / or, the amount of urea added is 1.5-2.5 wt% of the mass of the copper nitrate stripping waste liquid.

4. The recycling method according to any one of claims 1-3, characterized in that, The mass ratio of aminosulfonic acid to urea is (0.3-0.6):

1.

5. The recycling method according to any one of claims 1-4, characterized in that, The copper nitrate stripping waste liquid and additives are mixed with stirring at a speed of 30-60 rpm. And / or, the mixing time is ≥30 min.

6. The recycling method according to any one of claims 1-5, characterized in that, During the electrolytic treatment, the electrolysis temperature is ≤25℃; And / or, during the electrolytic treatment, the current density is 100-300 A / m 2 .

7. The recycling method according to any one of claims 1-6, characterized in that, The purity of the copper metal is ≥99%; And / or, the average particle size of the metallic copper is 5-50 μm.

8. The recycling method according to any one of claims 1-7, characterized in that, The concentration of copper ions in the solution after electrolysis is ≤10g / L; And / or, the acidity of the solution after electrolysis is ≥3.25 mol / L.

9. The recycling method according to any one of claims 1-8, characterized in that, The acid replenishment process uses concentrated nitric acid as the acid replenishment solution. And / or, the acidity of the regenerated copper nitrate copper stripping solution is 6.5-7.5 mol / L.

10. The recycling method according to any one of claims 1-9, characterized in that, The regeneration and reuse method includes the following steps: (1) Provide copper nitrate stripping waste solution; The copper ion concentration in the copper nitrate stripping waste liquid is ≥100g / L, and the acidity is ≤1.5mol / L; (2) Mix aminosulfonic acid and urea, then add them to the copper nitrate stripping waste liquid, and stir at a rate of 30-60 rpm for ≥30 min to obtain a mixed solution; The amount of aminosulfonic acid added is 0.5-1.5 wt% of the mass of the copper nitrate stripping waste liquid; the amount of urea added is 1.5-2.5 wt% of the mass of the copper nitrate stripping waste liquid; and the mass ratio of aminosulfonic acid to urea is (0.3-0.6):

1. (3) Transfer the mixed solution to a diaphragmless electrolytic cell and apply it at a current density of 100-300 A / m 2 Under the condition of electrolysis temperature ≤25℃, constant current electrolysis is carried out for 960-1020 min, so as to reduce and deposit metallic copper at the cathode and obtain the electrolytic solution at the same time. The anode of the diaphragmless electrolytic cell includes a titanium plate, and the cathode includes a copper sheet; the purity of the metallic copper is ≥99%, and the average particle size is 5-50 μm; the concentration of copper ions in the electrolytic solution is ≤10 g / L; and the acidity of the electrolytic solution is ≥3.25 mol / L. (4) The electrolyzed solution is mixed with an acid replenishing solution with a concentration of 15-15.8 mol / L to replenish the acid, thereby obtaining a regenerated copper nitrate copper stripping solution with an acidity of 6.5-7.5 mol / L; The acid replenishing solution includes concentrated nitric acid.

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