A method for recovering copper ions from browning waste liquid

Abstract

This invention discloses a method for recovering copper ions from browning wastewater. The method includes the following steps: subjecting the browning wastewater to be treated to high-speed shear dispersion, followed by ultrasonication, adding hydrogen peroxide, and reacting to obtain a solution rich in copper ions; wherein the high-speed shear dispersion is performed at a speed of 3000 rpm-6000 rpm. The present invention first uses high-speed shear dispersion to disrupt the three-dimensional network structure of the complexes using strong shear force, reducing the complexation bond energy; subsequently, it utilizes the local high temperature and pressure generated by cavitation to disrupt the molecular structure of the organic complexing agent, weakening the binding effect between copper ions and organic matter. After the ultrasonic treatment is initiated, hydrogen peroxide is added at an appropriate time, and the ultrasonication enhances mass transfer, increasing the generation efficiency of hydroxyl radicals, ultimately obtaining a pretreated solution rich in free copper ions. Using this pretreated solution to recover copper yields high-purity copper, and the method is simple to operate and has high copper recovery efficiency.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and specifically to a method for recovering copper ions from browning wastewater. Background Technology

[0002] Browning wastewater is copper-containing wastewater generated during the manufacturing process of printed circuit boards (PCBs), characterized by a high copper concentration (Cu). 2+ It is characterized by a mass concentration of 20-30 g / L and strong acidity (pH 0.5-1.5), and contains stable complexes such as copper-BTA and copper-polyethylene glycol. Traditional processing methods suffer from incomplete complex disruption and low purity of recovered copper.

[0003] Currently, the main pretreatment technologies for browning wastewater include the following: One method is the composite oxidation complex-breaking method (as disclosed in invention patent documents such as CN113666477A and CN116065196A). This method uses potassium permanganate combined with ferrous sulfate, propanol, and other compound additives to utilize their strong oxidizing properties to break down complexing agents such as BTA. However, this technology requires heating at 65℃, resulting in high energy consumption; the dosage of reagents lacks quantitative standards; although the purity of electrolytic copper can reach 95%-98%; moreover, the strong oxidant easily reacts ineffectively with residual hydrogen peroxide in the waste liquid, increasing treatment costs.

[0004] Secondly, there is the co-regeneration process (as disclosed in invention patent documents such as CN116693127A). This process involves mixing browning wastewater with chemical copper wastewater and film stripping wastewater, utilizing the complementary properties of the components to separate organic additives and copper without the need for additional strong oxidants. However, this process has poor versatility, and the recovered copper exists in the form of copper hydroxide, requiring additional reduction treatment, resulting in a copper purity of 85%-90%.

[0005] Thirdly, there is the pretreatment-electrolysis coupling technology (as disclosed in invention patent documents such as CN108249704A and CN106350678A). This technology uses ferrous sulfate to break the complex; however, it lacks quantitative addition indicators suitable for high copper concentrations, resulting in loose electrolytic copper that is difficult to form, with a pass rate of only 70%-80%.

[0006] Therefore, it is of great significance to design a new recycling method that takes into account both copper recovery efficiency and purity. Summary of the Invention

[0007] This invention aims to solve at least one of the technical problems existing in the prior art. To this end, this invention proposes a pretreatment method for recovering copper ions from browning wastewater. This method can effectively solve the problem of efficient removal of copper-organic complexes in browning wastewater, resulting in high recovery efficiency and purity of copper ions in subsequent recovery.

[0008] According to one aspect of the present invention, a pretreatment method for recovering copper ions from browning wastewater is provided, comprising the following steps: The browning waste liquid to be treated is subjected to high-speed shear dispersion treatment, followed by ultrasonication, and hydrogen peroxide is added to react and obtain a solution rich in copper ions; wherein the rotation speed of the high-speed shear dispersion treatment is 3000-6000 rpm.

[0009] The pretreatment method according to embodiments of the present invention has at least the following beneficial effects: First, the present invention employs high-speed shear dispersion treatment, utilizing strong shear force to disrupt the three-dimensional network structure of the complex and reduce the complexation bond energy. Subsequently, the localized high temperature and pressure generated by cavitation effect disrupts the molecular structure of the organic complexing agent, weakening the binding interaction between copper ions and organic matter. After the ultrasonic treatment is initiated, hydrogen peroxide is added at an appropriate time. Ultrasonic enhancement of mass transfer improves the generation efficiency of hydroxyl radicals, ultimately obtaining a pretreatment solution rich in free copper ions. Copper is recovered using this pretreatment solution, yielding high-purity copper. Furthermore, the method is simple to operate and has high copper recovery efficiency.

[0010] According to some embodiments of the present invention, the rotational speed of the high-speed shear dispersion treatment is 4000 rpm to 6000 rpm, such as 4500 rpm.

[0011] According to some embodiments of the present invention, the high-speed shear dispersion treatment lasts for 5-10 minutes.

[0012] According to some embodiments of the present invention, the high-speed shear dispersion treatment lasts for 5-8 minutes.

[0013] According to some embodiments of the present invention, the power of the ultrasound is 300-600W.

[0014] According to some embodiments of the present invention, the power of the ultrasound is 300-500W.

[0015] According to some embodiments of the present invention, the frequency of the ultrasound is 20~60kHz.

[0016] According to some embodiments of the present invention, the hydrogen peroxide is added to the browning waste liquid at a volume ratio of 0.2 to 0.8%.

[0017] According to some embodiments of the present invention, the hydrogen peroxide is added to the browning waste liquid at a volume ratio of 0.2 to 0.6%.

[0018] According to some embodiments of the present invention, the hydrogen peroxide and the Cu in the browning waste liquid 2+ The molar ratio is 1:8~10.

[0019] According to some embodiments of the present invention, the hydrogen peroxide and the Cu in the browning waste liquid 2+ The molar ratio is 8.5~9.5. For example, it is about 1:9.

[0020] According to some embodiments of the present invention, ultrasound is maintained during the reaction process. Ultrasound is synchronously applied during the reaction.

[0021] According to some embodiments of the present invention, the reaction time is 30-60 minutes. Controlling the reaction time to 30-60 minutes ensures both a complete reaction and better guarantees the copper recovery rate and purity.

[0022] According to some embodiments of the present invention, the browning waste liquid to be treated is a filtered browning waste liquid.

[0023] According to another aspect of the present invention, a method for recovering copper ions from browning waste liquid is provided, comprising the following steps: pretreatment by the above-described pretreatment method, and electrolytic recovery of copper from the pretreated browning waste liquid.

[0024] According to some embodiments of the present invention, the electrolysis includes at least one of the following parameters: 1) Current density is 220~260A / m 2 ; 2) The electrolysis temperature is 30~40℃; 3) Electrolysis time is 4~20h.

[0025] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Detailed Implementation

[0026] The following will clearly and completely describe the concept and technical effects of the present invention in conjunction with embodiments, so as to fully understand the purpose, features and effects of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention. Unless otherwise specified, the experimental methods used in the embodiments are conventional methods; the materials and reagents used, unless otherwise specified, are commercially available. Unless otherwise specified, the same parameter value is the same in all embodiments. The embodiments described below are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0027] In the description of this invention, references to terms such as "some embodiments" indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0028] In the description of this invention, room temperature refers to 25±5℃, and specifically 25℃ in the embodiments.

[0029] Example 1 This example demonstrates a method for recovering copper ions from browning wastewater, as follows: Take 2L of browning waste liquid (initial Cu) 2+ A solution with a concentration of 29 g / L and an acidity of 2.2 mol / L was pumped into a high-speed shear disperser and sheared at 4500 r / min for 5 min. It was then placed in an ultrasonic reactor with a theoretical copper content of 58.0 g. 10.4 mL of 30 wt% H₂O₂ was added, and the mixture was subjected to a synergistic reaction at 500 W ultrasonic power and room temperature for 30 min. Key experimental phenomena were observed: ultrasonic cavitation effect promoted the vigorous generation and uniform diffusion of bubbles, resulting in a lighter solution color and no obvious residue formation. After treatment, electrolysis was performed (current density 240 A / m³). 2 Electrolysis temperature: 35℃; Electrolysis time: 10h; Residual Cu 2+ With a concentration of 2.3 g / L, the cathode copper weighed 53.4 g after electrolysis. After being calcined at 800℃ for 1 h to remove surface impurities, the Cu mass after calcination was 32.04 g. The copper recovery rate (after calcination) was (32.04 g / 58.0 g) × 100% = 55.24%.

[0030] Example 2 This example demonstrates a method for recovering copper ions from browning wastewater, as follows: Take 2L of browning waste liquid (initial Cu) 2+ A solution (29 g / L concentration, 2.2 mol / L acidity) was pumped into a high-speed shear disperser and sheared at 4500 r / min for 5 min. The solution was then placed in an ultrasonic reactor. The theoretical copper content was 58.0 g. 10.4 mL of 30 wt% H₂O₂ was added, and the mixture was subjected to a synergistic reaction at 400 W ultrasonic power and room temperature for 60 min. Key experimental phenomena included: continuous and stable release of bubbles; a clear, light blue-green solution; and the presence of a small amount of fine organic residue after standing, indicating the presence of free Cu. 2+ The proportion has increased significantly. Electrolysis is performed after treatment (current density 240 A / m³). 2 Electrolysis temperature: 35℃; Electrolysis time: 10h; Residual Cu 2+With a concentration of 1.8 g / L, the cathode copper weighed 54.2 g after electrolysis. After being calcined at 800℃ for 1 h to remove surface impurities, the Cu mass after calcination was 38.08 g. The copper recovery rate (after calcination) was (38.08 g / 58.0 g) × 100% = 65.64%.

[0031] Example 3 This example demonstrates a method for recovering copper ions from browning wastewater, as follows: Take 2L of browning waste liquid (initial Cu) 2+ A solution with a concentration of 29 g / L and an acidity of 2.2 mol / L was pumped into a high-speed shear disperser and sheared at 4500 r / min for 5 min. The solution was then placed in an ultrasonic reactor with a theoretical copper content of 58.0 g. 10.4 mL of 30 wt% H₂O₂ was added, and the mixture was subjected to a synergistic reaction at 500 W ultrasonic power and room temperature for 60 min. Key experimental phenomena included: strong cavitation and deep oxidation synergistic effects, resulting in vigorous turbulence and dense bubbles in the solution, a pure blue-green color, and only trace amounts of degradation residue at the bottom. After treatment, electrolysis was performed (current density 240 A / m³). 2 Electrolysis temperature: 35℃; Electrolysis time: 10h; Residual Cu 2+ With a concentration of 0.8 g / L, the cathode copper weighed 56.4 g after electrolysis. After being calcined at 800℃ for 1 h to remove surface impurities, the Cu mass after calcination was 39.48 g, and the copper recovery rate (after calcination) was (39.48 g / 58.0 g) × 100% = 68.07%.

[0032] Example 4 This example demonstrates a method for recovering copper ions from browning wastewater, as follows: Take 2L of browning waste liquid (initial Cu) 2+ A solution with a concentration of 29 g / L and an acidity of 2.2 mol / L was pumped into a high-speed shear disperser and sheared at 4500 r / min for 8 min. The solution was then placed in an ultrasonic reactor with a theoretical copper content of 58.0 g. 10.4 mL of 30 wt% H₂O₂ was added, and the mixture was subjected to a synergistic reaction at 500 W ultrasonic power and room temperature for 60 min. Key experimental phenomena included: strong cavitation and deep oxidation synergistic effects, resulting in vigorous turbulence and dense bubbles in the solution, a pure blue-green color, and only trace amounts of degradation residue at the bottom. After treatment, electrolysis was performed, and residual Cu... 2+ With a concentration of 0.8 g / L, the cathode copper weighed 57.1 g after electrolysis. After being calcined at 800℃ for 1 h to remove surface impurities, the Cu mass after calcination was 42.69 g, and the copper recovery rate (after calcination) was (42.69 g / 58.0 g) × 100% = 73.6%.

[0033] Comparative Example 1 This example demonstrates a method for recovering copper ions from browning wastewater, as follows: Take 2L of browning waste liquid (initial Cu) 2+ A solution with a concentration of 29 g / L and an acidity of 2.2 mol / L was pumped into a high-speed shear disperser and sheared at 4500 r / min for 5 min. It was then placed in an ultrasonic apparatus, with a theoretical copper content of 58.0 g, and treated for 30 min at a power of 400 W, a frequency of 40 kHz, and a constant temperature of 40 °C. Key experimental phenomena included: the generation of fine bubbles in the waste liquid, a significantly enhanced cavitation effect, a slight lightening of the solution color (still a deep green, characteristic color of complexed copper), and residual Cu. 2+ The concentration decreased slightly but remained predominantly in complexed form. Electrolysis was then performed after treatment (current density 240 A / m³). 2 Electrolysis temperature: 35℃; Electrolysis time: 10h; Residual Cu 2+ With a concentration of 22.1 g / L, the cathode copper weighed 13.8 g after electrolysis. After being calcined at 800℃ for 1 h to remove surface impurities, the Cu mass after calcination was 8.28 g. The copper recovery rate (after calcination) was (8.28 g / 58.0 g) × 100% = 14.28%.

[0034] Comparative Example 2 This example demonstrates a method for recovering copper ions from browning wastewater, as follows: Take 2L of browning waste liquid (initial Cu) 2+ A solution with a concentration of 29 g / L and an acidity of 2.2 mol / L was pumped into a high-speed shear disperser and sheared at 4500 r / min for 5 min. It was then placed in an ultrasonic apparatus, with a theoretical copper content of 58.0 g, and treated for 60 min at a power of 500 W, a frequency of 40 kHz, and a constant temperature of 40 °C. Key experimental phenomena included: localized and intense disturbances at the concentrated ultrasonic energy points, accompanied by dense overflow of tiny bubbles; a significant lightening of the solution color; and trace amounts of organic residue at the bottom after settling. (Cu content was also observed.) 2+ The removal rate remains low. Electrolysis (current density 240 A / m³) is then performed after treatment. 2 Electrolysis temperature: 35℃; Electrolysis time: 10h; Residual Cu 2+ With a concentration of 16.5 g / L, the cathode copper weighed 25.0 g after electrolysis. After being calcined at 800℃ for 1 h to remove surface impurities, the Cu mass after calcination was 15.0 g. The copper recovery rate (after calcination) was (15.0 g / 58.0 g) × 100% = 25.86%.

[0035] Comparative Example 3 This example demonstrates a method for recovering copper ions from browning wastewater, as follows: Take 2L of browning waste liquid (initial Cu) 2+Ferrous sulfate (FeSO4) with a concentration of 29 g / L and an acidity of 2.2 mol / L was pumped into a high-speed shear disperser and sheared at 4500 r / min for 5 min. The mixture was then placed in a reaction vessel with a theoretical copper content of 58.0 g. 0.5 g / L of ferrous sulfate (FeSO4) was added sequentially. 7H2O) and 10.4 mL of 30wt% H2O2 were reacted at room temperature with stirring for 60 min. Key experimental phenomena included: the appearance of a small amount of brownish-yellow flocculents in the solution; a slight increase in bubble production compared to the single hydrogen peroxide system; and a dark greenish-yellow color in the solution (initially showing the characteristic color of iron ions). Electrolysis was then performed (current density 240 A / m). 2 Electrolysis temperature: 35℃; Electrolysis time: 10h; Residual Cu 2 + With a concentration of 22.5 g / L, the cathode copper weighed 13.0 g after electrolysis. After being calcined at 800℃ for 1 h to remove surface impurities, the Cu mass after calcination was 7.8 g, and the copper recovery rate (after calcination) was (7.8 g / 58.0 g) × 100% = 13.45%.

[0036] Comparative Example 4 This example demonstrates a method for recovering copper ions from browning wastewater, as follows: Take 2L of browning waste liquid (initial Cu) 2+ A solution with a concentration of 29 g / L and an acidity of 2.2 mol / L was pumped into a high-speed shear disperser and sheared at 4500 r / min for 5 min. The solution was then placed in a reaction vessel with a theoretical copper content of 58.0 g. 1.0 g / L ferrous sulfate and 10.4 mL of 30 wt% H₂O₂ were added sequentially. The reaction was carried out under stirring at room temperature for 60 min. Key experimental phenomena included an increase in brownish-yellow flocculent matter, an increase in solution turbidity, a significant increase in bubble release, and a change in solution color from dark green to dark greenish-yellow. After treatment, electrolysis was performed (current density 240 A / m³). 2 Electrolysis temperature: 35℃; Electrolysis time: 10h; Residual Cu 2+ With a concentration of 19.8 g / L, the cathode copper weighed 18.4 g after electrolysis. After being calcined at 800℃ for 1 h to remove surface impurities, the Cu mass after calcination was 11.04 g. The copper recovery rate (after calcination) was (11.04 g / 58.0 g) × 100% = 19.03%.

[0037] Experimental test: Cu in browning waste liquid before pretreatment 2+ The concentration test method is as follows: The browning waste liquid was vacuum filtered through an 18μm microporous membrane (refer to patent CN110106523A) to remove suspended organic residues and fine particulate impurities. 10mL of the filtrate was placed in a PTFE digestion vessel, along with 4mL of concentrated sulfuric acid (98wt%) and 2mL of 30wt% hydrogen peroxide. The temperature was increased to 120℃ over 5 minutes and maintained for 15 minutes; then increased to 160℃ over another 5 minutes and maintained for 20 minutes. The strong acidity of sulfuric acid and the synergistic oxidizing effect of hydrogen peroxide broke the Cu-BTA and Cu-EDTA complex bonds, resulting in a complexed Cu... 2+ The copper is completely converted to a free state. After cooling, the volume is adjusted to 50 mL with DI water. Detection is performed using an inductively coupled plasma optical emission spectrometer (ICP-OES, such as an Optima 8300), selecting the characteristic emission wavelength of copper at 327.4 nm. A standard curve is plotted using 0.1-100 mg / L copper standard solutions, and the correlation coefficient R is required. 2 ≥0.9995, the average value is taken from 3 parallel tests of the sample.

[0038] The concentration of Cu ions after treatment was determined by EDTA complexometric titration (referencing the method in patent CN117849264A). The residual Cu in the waste liquid of each treatment group was also determined. 2+ The specific procedure for determining the concentration is as follows: Take 10 mL of the filtered liquid after treatment and place it in an Erlenmeyer flask. Add 5 mL of acetate-sodium acetate buffer solution (pH 5.5) to adjust the acidity of the system. Add 2 drops of PAN indicator (0.1% ethanol solution). At this point, the solution turns purple-red. Titrate with 0.05 mol / L EDTA standard solution, shaking thoroughly while titrating, until the solution color changes abruptly from purple-red to bright yellow and does not fade within 30 seconds. This is the titration endpoint. Record the volume of EDTA standard solution consumed. Calculate the residual Cu using the formula. 2+ Concentration: ρ(Cu) 2+ The formula is calculated as follows: (c × V × 63.55 × 1000) / V0, where c is the concentration of the EDTA standard solution (mol / L), V is the volume of EDTA consumed (L), 63.55 is the molar mass of Cu (g / mol), and V0 is the sampling volume (L). Each experiment was performed in triplicate, and the average value was taken as the final result. The results are shown in Table 1 below.

[0039] Table 1

[0040] As can be seen from the table above, the copper recovery effect of the embodiment of the present invention is significantly better than that of the comparative example. This indicates that the shear-ultrasound synergistic hydrogen peroxide pretreatment process proposed in this invention achieves efficient removal of copper-organic complexes in browning waste liquid through the synergistic cooperation between each treatment step, laying the foundation for subsequent electrolytic recovery. The filtered browning waste liquid is pumped into a high-speed shear disperser, where the three-dimensional network structure of the complexes is destroyed by strong shear force under high-speed shearing, reducing the complex bond energy. Subsequently, the browning waste liquid is sent to an ultrasonic treatment unit, where the local high temperature and pressure generated by cavitation effect destroy the molecular structure of the organic complexing agent, weakening the binding force between copper ions and organic matter. Hydrogen peroxide (optimally 5.2 mL / L, corresponding to the concentration of copper in the browning waste liquid) is added immediately after ultrasonic treatment is started. 2+ The molar ratio is approximately 1:9), utilizing ultrasound-enhanced mass transfer to increase hydroxyl radical ( The formation efficiency of OH was improved, and a small amount of oxidation residue was removed by microporous membrane filtration after the reaction, resulting in a product rich in free Cu. 2+ The pretreatment solution. Furthermore, comparing the effects between control groups shows that while adding ferrous sulfate can slightly improve the copper removal rate, it introduces iron impurities and produces iron sludge.

[0041] This pretreatment process allows free Cu to be released. 2+ The proportion of free Cu increased from less than 50% to over 90% of the original waste liquid. EDTA complexometric titration was used to determine the optimal parameters for free Cu. 2+ The proportion can reach over 95%.

[0042] In summary, this invention addresses the limitations of existing technologies in terms of adaptability, poor copper recovery efficiency, and high costs by innovatively coupling a synergistic system of "high-speed shearing disruption + ultrasonic cavitation - hydrogen peroxide oxidation." First, a high-speed shearing disperser forcefully disrupts the three-dimensional network structure of the copper-BTA complex, reducing the complex bond energy by 45%-55% and breaking down the protective film of the hydrogen peroxide stabilizer. Then, ultrasonic cavitation and hydrogen peroxide oxidation are coupled, with the hydrogen peroxide reacting with the browning waste liquid. This effectively avoids the carbonization and slagging of organic matter, and leaves no excessive reagent residue. Electrolytic recovery of copper achieves both high purity and high recovery rate, without requiring acid adjustment or producing iron sludge, thus solving the problems of difficult and low-purity copper recovery from browning waste liquid.

[0043] The embodiments of the present invention have been described in detail above, but the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A pretreatment method for recovering copper ions from browning wastewater, characterized in that: Includes the following steps: The browning waste liquid to be treated is subjected to high-speed shear dispersion treatment, followed by ultrasonication, and hydrogen peroxide is added to react and obtain a solution rich in copper ions; wherein the rotation speed of the high-speed shear dispersion treatment is 3000-6000 rpm.

2. The pretreatment method for recovering copper ions from browning wastewater according to claim 1, characterized in that: The high-speed shear dispersion treatment is performed at a rotation speed of 4000 rpm to 6000 rpm; and / or the high-speed shear dispersion treatment is performed for 5-10 minutes.

3. The pretreatment method for recovering copper ions from browning wastewater according to claim 1, characterized in that: The high-speed shear dispersion treatment lasts for 5-8 minutes.

4. The pretreatment method for recovering copper ions from browning wastewater according to claim 1, characterized in that: The power of the ultrasound is 300-600W; and / or the frequency of the ultrasound is 20-60kHz.

5. The pretreatment method for recovering copper ions from browning wastewater according to claim 1, characterized in that: The hydrogen peroxide is added to the browning waste liquid at a volume ratio of 0.2-0.8%.

6. The pretreatment method for recovering copper ions from browning wastewater according to claim 1, characterized in that: The hydrogen peroxide and the Cu in the browning waste liquid 2+ The molar ratio is 1:8~10.

7. The pretreatment method for recovering copper ions from browning wastewater according to claim 1, characterized in that: The reaction process continues with ultrasound.

8. The pretreatment method for recovering copper ions from browning wastewater according to claim 1, characterized in that: The reaction time is 30-60 minutes.

9. A method for recovering copper ions from browning wastewater, characterized in that: The process includes the following steps: pretreatment by the pretreatment method described in any one of claims 1 to 8, followed by electrolytic recovery of copper from the pretreated browning waste liquid.

10. The method according to claim 9, characterized in that: The electrolysis includes at least one of the following parameters: 1) Current density is 220~260A / m 2 ; 2) The electrolysis temperature is 30~40℃; 3) Electrolysis time is 4~20h.

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