A method for preparing copper powder using copper nitrate-containing wastewater

Abstract

This invention provides a method for preparing copper powder from copper nitrate-containing wastewater. The method includes: mixing a reducing agent and a dispersant to obtain a first solution; adding copper nitrate-containing wastewater to the first solution to obtain a second solution; ultrasonically treating the second solution; and performing solid-liquid separation to obtain the copper powder. This invention utilizes ultrasound assistance to improve reaction efficiency, and through precise control of reaction conditions, achieves a copper recovery rate of over 99% from the copper nitrate-containing wastewater, obtaining copper powder with a purity of 5N.

Description

Technical Field

[0001] This invention relates to the field of chemical technology, specifically to the recycling and utilization of copper nitrate-containing wastewater, and more particularly to a method for preparing copper powder using copper nitrate-containing wastewater. Background Technology

[0002] 6N high-purity copper (copper purity > 99.9999%) is widely used in semiconductor fields such as sputtering targets due to its excellent electrical and thermal conductivity and good ductility. 6N high-purity copper is commonly cleaned with nitric acid to remove the oxide layer on the copper surface. The wastewater after cleaning mainly consists of copper nitrate, making copper recovery from this wastewater crucial.

[0003] In traditional technologies for treating copper powder from high-purity copper cleaning wastewater, electrolysis relies on high energy consumption (>40 kWh / kg) and generates acid mist pollution; the purity of the copper powder is limited by impurities in the electrolyte (<99.5%). Chemical reduction methods often use toxic reducing agents such as formaldehyde and sodium borohydride, and the reaction byproducts require high-temperature post-treatment, posing environmental pollution risks. Although wet treatment technology adsorbs copper ions through magnetic composite particles, it requires multiple desorption and regeneration processes, making the process complex and achieving a copper recovery rate of only about 85%. Furthermore, existing technologies have low wastewater recycling rates; for example, the electrolytic wastewater after copper sulfate solution electrowinning needs to be concentrated and crystallized, resulting in high energy consumption and the inability to achieve closed-loop wastewater reuse.

[0004] CN107699697A discloses a method for copper recovery from copper nitrate wastewater. The method involves pretreating the copper nitrate wastewater with ammonia to neutralize the nitric acid and reduce its corrosiveness. The wastewater is then electrolyzed to prevent further corrosion of equipment and the return of precipitated copper. The reaction temperature is controlled below 35°C, and cooling further reduces the corrosiveness of the wastewater. After electrolysis, adding an appropriate amount of nitric acid restores its corrosiveness, allowing for repeated use in production processes, thus maximizing resource utilization and promoting environmental protection.

[0005] CN112410824A discloses a method for copper recovery from copper nitrate wastewater. The method uses a cation exchange membrane to separate the electrolytic cell. The anode zone contains a copper nitrate solution, and the cathode zone contains a sulfuric acid solution. The anode is made of titanium plate, and the cathode is made of copper plate. Copper ions are electrolytically deposited on the copper plate. The acidity of the anode solution is increased in the anode zone, so that the copper nitrate solution in the anode zone can be used as a raw material for preparing a copper corrosion solution after copper removal, thereby realizing the recycling of copper nitrate wastewater.

[0006] CN101906644A discloses a method for recovering copper from copper nitrate wastewater. The method uses an iron rod as an insoluble anode and a copper plate as the cathode, and involves gas stirring of the copper nitrate wastewater in an electrolytic cell to ensure continuous electrolysis. This invention can recover copper with a purity of over 99.97% and a copper recovery rate of over 99.5%.

[0007] In summary, there is an urgent need for a high-purity copper cleaning wastewater treatment technology that is efficient, low-consumption, environmentally friendly, and capable of producing high-purity copper powder. Summary of the Invention

[0008] To address the shortcomings of existing technologies, the present invention aims to provide a method for preparing copper powder from copper nitrate-containing wastewater. This invention utilizes ultrasonic assistance to improve reaction efficiency, and through precise control of reaction conditions, achieves a copper recovery rate of over 99% from the copper nitrate-containing wastewater, obtaining copper powder with a purity of 5N.

[0009] To achieve this objective, the present invention adopts the following technical solution:

[0010] In a first aspect, the present invention provides a method for preparing copper powder using copper nitrate-containing wastewater, the method comprising:

[0011] A first solution is obtained by mixing a reducing agent and a dispersant; copper nitrate-containing wastewater is added to the first solution to obtain a second solution; the second solution is ultrasonically treated; and the copper powder is obtained by solid-liquid separation.

[0012] The “copper nitrate-containing wastewater” mentioned in this invention refers to the wastewater generated after cleaning 6N high-purity copper with nitric acid.

[0013] In this invention, a reducing agent and a dispersant are used in combination in the first solution. The reducing agent reacts with copper ions to produce elemental copper. The dispersant prevents the copper from agglomerating after the reaction, helping to control the particle size of the copper powder, ultimately resulting in copper powder with good dispersibility and controllable particle size. Ultrasonic treatment of the second solution ensures a complete reaction and prevents copper powder agglomeration. This invention utilizes ultrasound assistance to improve reaction efficiency, and through precise control of reaction conditions, achieves a copper recovery rate of over 99% from copper nitrate-containing wastewater, obtaining copper powder with a purity of 5N (copper purity > 99.999%).

[0014] Preferably, in the first solution, the molar ratio of reducing agent to dispersant is (2~3):1.

[0015] Preferably, in the second solution, the molar ratio of the reducing agent to the copper ions in the copper nitrate-containing wastewater is (1.1~1.5):1.

[0016] Preferably, the reducing agent includes any one or a combination of at least two of ascorbic acid, sodium phosphite, hydrazine hydrate, isopropanol, octadecyl mercaptan, or propyl gallate, with ascorbic acid being the most preferred.

[0017] Preferably, the dispersant comprises any one or a combination of at least two of polyvinylpyrrolidone, octadecylamine, triethanolamine, or sodium dodecyl sulfonate.

[0018] Preferably, the solvent includes water.

[0019] Preferably, before adding copper nitrate-containing wastewater to the first solution, the pH of the first solution is adjusted to 11-13.

[0020] Preferably, adjusting the pH of the first solution involves adding sodium hydroxide solution and / or potassium hydroxide solution to the first solution, wherein the concentration of the sodium hydroxide solution and / or potassium hydroxide solution is 4 mol / L to 8 mol / L.

[0021] Preferably, before adding copper nitrate-containing wastewater to the first solution, the first solution is further heated to 45°C to 60°C.

[0022] Preferably, the power of the ultrasonic treatment is 30kHz to 50kHz.

[0023] Preferably, the ultrasonic treatment time is 30 min to 60 min.

[0024] Preferably, the solid-liquid separation method includes centrifugation.

[0025] Preferably, the method further includes washing, drying and sieving the copper powder.

[0026] Preferably, the washing method includes rinsing with dilute sulfuric acid and ethanol in sequence.

[0027] Preferably, the wash water after washing can be recycled after impurities are removed by an activated carbon filter and a 1μm filter.

[0028] Preferably, the drying method includes vacuum drying.

[0029] Preferably, the apparent vacuum degree of the vacuum drying is -0.1 MPa.

[0030] Preferably, the vacuum drying temperature is 60℃~80℃.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] The method provided by this invention is simple and easy to implement. It utilizes ultrasound assistance to improve reaction efficiency, and through precise control of reaction conditions, it achieves a copper recovery rate of over 99% in copper nitrate-containing wastewater, with the obtained copper powder reaching a purity of 5N. Detailed Implementation

[0033] 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.

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention; the terms “comprising” and “having” and any variations thereof in this invention are intended to cover non-exclusive inclusion.

[0035] In the description of this invention, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this invention, "a plurality of" means two or more, unless otherwise explicitly defined.

[0036] In one specific embodiment, the present invention provides a method for preparing copper powder using copper nitrate-containing wastewater, the method comprising:

[0037] A first solution is obtained by mixing a reducing agent and a dispersant; copper nitrate-containing wastewater is added to the first solution to obtain a second solution; the second solution is ultrasonically treated; and the copper powder is obtained by solid-liquid separation.

[0038] In this invention, a reducing agent and a dispersant are used in combination in the first solution. The reducing agent reacts with copper ions to produce elemental copper. The dispersant prevents the copper from agglomerating after the reaction, helping to control the particle size of the copper powder, ultimately resulting in copper powder with good dispersibility and controllable particle size. Ultrasonic treatment of the second solution ensures a complete reaction and prevents copper powder agglomeration. This invention utilizes ultrasound assistance to improve reaction efficiency, and through precise control of reaction conditions, achieves a copper recovery rate of over 99% from copper nitrate-containing wastewater, obtaining copper powder with a purity of 5N.

[0039] In this invention, a suitable molar ratio of reducing agent to dispersant is beneficial for controlling the particle size of the prepared copper powder and avoiding agglomeration.

[0040] In some embodiments, the molar ratio of reducing agent to dispersant in the first solution is (2~3):1, for example, it can be 2:1, 2.2:1, 2.4:1, 2.6:1, 2.8:1 or 3:1, including but not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0041] In this invention, the molar ratio of the reducing agent to copper ions in copper nitrate-containing wastewater affects the purity of the prepared copper powder and the reaction process. Insufficient reducing agent will lead to incomplete reduction and residual copper ions in the solution; while excessive reducing agent will result in an excessively fast reaction rate, uneven particle size, and, when excessive, it is prone to oxidative degradation during the reaction. For example, when ascorbic acid is used as the reducing agent, oxalate ions (C2O4) are easily generated. 2- Oxalate ions combine with residual copper ions in the solution to form slightly soluble copper oxalate precipitate. This impurity is difficult to completely remove by conventional water washing and is detected as a non-metallic impurity (high C content) in the final product purity test, resulting in a decrease in the purity of copper powder.

[0042] In some embodiments, the molar ratio of the reducing agent to copper ions in the copper nitrate-containing wastewater in the second solution is (1.1~1.5):1, for example, it can be 1.1:1, 1.2:1, 1.3:1, 1.4:1 or 1.5:1, including but not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0043] In some embodiments, the reducing agent includes any one or a combination of at least two of ascorbic acid, sodium phosphite, hydrazine hydrate, isopropanol, octadecyl mercaptan, or propyl gallate. Typical but non-limiting combinations include a combination of ascorbic acid and sodium phosphite, a combination of hydrazine hydrate and isopropanol, or a combination of octadecyl mercaptan and propyl gallate.

[0044] In some embodiments, the dispersant comprises any one or a combination of at least two of polyvinylpyrrolidone, octadecylamine, triethanolamine, or sodium dodecyl sulfonate. Typical but non-limiting combinations include a combination of polyvinylpyrrolidone and octadecylamine, or a combination of triethanolamine and sodium dodecyl sulfonate.

[0045] In some embodiments, the solvent includes water and / or ethanol.

[0046] In some embodiments, before adding copper nitrate-containing wastewater to the first solution, the pH of the first solution is adjusted to 11-13, for example, 11, 11.5, 12, 12.5 or 13, including but not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0047] In some embodiments, adjusting the pH of the first solution includes adding a sodium hydroxide solution and / or a potassium hydroxide solution to the first solution, wherein the concentration of the sodium hydroxide solution and / or potassium hydroxide solution is 4 mol / L to 8 mol / L, for example, 4 mol / L, 5 mol / L, 6 mol / L, 7 mol / L or 8 mol / L, including but not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0048] In some embodiments, before adding copper nitrate-containing wastewater to the first solution, the first solution is further heated to 45°C to 60°C, for example, 45°C, 50°C, 55°C or 60°C, including but not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0049] In this invention, the power of the ultrasonic treatment affects the rate of reaction.

[0050] In some embodiments, the power of the ultrasonic treatment is 30kHz to 50kHz, for example, it can be 30kHz, 35kHz, 40kHz, 45kHz or 50kHz, including but not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0051] In some embodiments, the ultrasonic treatment time is 30 min to 60 min, for example, it can be 30 min, 35 min, 40 min, 45 min, 50 min, 55 min or 60 min, including but not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0052] In some embodiments, the solid-liquid separation method includes centrifugation.

[0053] In some embodiments, the method further includes washing, drying, and sieving the copper powder.

[0054] In some embodiments, the washing method includes rinsing with dilute sulfuric acid and ethanol in sequence.

[0055] In some embodiments, the wash water after washing can be recycled after impurities are removed by an activated carbon filter and a 1μm filter.

[0056] In some embodiments, the drying method includes vacuum drying.

[0057] In some embodiments, the apparent vacuum degree of the vacuum drying is -0.1 MPa.

[0058] In some embodiments, the vacuum drying temperature is 60°C to 80°C, for example, it can be 60°C, 65°C, 70°C, 75°C or 80°C, including but not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0059] In some embodiments, the concentration of copper ions in the copper nitrate wastewater is 20 g / L to 40 g / L, for example, it can be 20 g / L, 25 g / L, 30 g / L, 35 g / L or 40 g / L, including but not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0060] To clearly illustrate the technical solution of this invention, in the specific embodiments, the copper nitrate-containing wastewater used refers to the wastewater generated from washing 6N copper powder with nitric acid, and the purity of the other raw materials used in the preparation of copper powder is analytical grade. The above description is only for clearly illustrating the technical solution of this invention and is not intended to further limit the invention.

[0061] Example 1

[0062] This embodiment provides a method for preparing copper powder using copper nitrate-containing wastewater, the method comprising:

[0063] Ascorbic acid and polyvinylpyrrolidone were mixed at a molar ratio of 2.5:1 to obtain a first solution. 25 g / L of copper nitrate-containing wastewater was added to the first solution to obtain a second solution, wherein the molar ratio of ascorbic acid to copper ions in the copper nitrate-containing wastewater was 1.2:1. 6 mol / L sodium hydroxide solution was added to the second solution to adjust the pH to 12, and the solution was heated to 50°C and then subjected to ultrasonic treatment at 40 kHz for 40 min. After ultrasonic treatment, copper powder was separated by centrifugation and rinsed with ethanol. The solution was then dried at 70°C under vacuum with a displayed vacuum degree of -0.1 MPa.

[0064] In this embodiment, the wash water obtained from washing copper powder is used for subsequent washing of copper powder after removing residual impurities through an activated carbon filter and a 1μm filter.

[0065] Example 2

[0066] This embodiment provides a method for preparing copper powder using copper nitrate-containing wastewater, the method comprising:

[0067] Ascorbic acid and polyvinylpyrrolidone were mixed in a molar ratio of 2:1 to obtain a first solution. 20 g / L of copper nitrate-containing wastewater was added to the first solution to obtain a second solution, wherein the molar ratio of ascorbic acid to copper ions in the copper nitrate-containing wastewater was 1.1:1. A 5 mol / L potassium hydroxide solution was added to the second solution to adjust the pH to 11, and the solution was heated to 45°C and then subjected to ultrasonic treatment at 30 kHz for 30 min. After ultrasonic treatment, copper powder was separated by centrifugation and rinsed with ethanol. The solution was then dried at 60°C under vacuum with a displayed vacuum degree of -0.1 MPa.

[0068] In this embodiment, the wash water obtained from washing copper powder is used for subsequent washing of copper powder after removing residual impurities through an activated carbon filter and a 1μm filter.

[0069] Example 3

[0070] This embodiment provides a method for preparing copper powder using copper nitrate-containing wastewater, the method comprising:

[0071] Ascorbic acid and polyvinylpyrrolidone were mixed in a molar ratio of 3:1 to obtain a first solution. 40 g / L of copper nitrate-containing wastewater was added to the first solution to obtain a second solution, wherein the molar ratio of ascorbic acid to copper ions in the copper nitrate-containing wastewater was 1.5:1. An 8 mol / L potassium hydroxide solution was added to the second solution to adjust the pH to 13, and the solution was heated to 60°C and then subjected to ultrasonic treatment at 50 kHz for 60 min. After ultrasonic treatment, copper powder was separated by centrifugation and washed sequentially with dilute sulfuric acid and ethanol. The solution was then dried at 80°C under vacuum with a displayed vacuum degree of -0.1 MPa.

[0072] In this embodiment, the wash water obtained from washing copper powder is used for subsequent washing of copper powder after removing residual impurities through an activated carbon filter and a 1μm filter.

[0073] Example 4

[0074] This embodiment provides a method for preparing copper powder using copper nitrate-containing wastewater. The method is the same as in Example 1, except that the molar ratio of ascorbic acid and polyvinylpyrrolidone is 1:1.

[0075] Example 5

[0076] This embodiment provides a method for preparing copper powder using copper nitrate-containing wastewater. The method is the same as in Example 1, except that the molar ratio of ascorbic acid to polyvinylpyrrolidone is 1:4.

[0077] Example 6

[0078] This embodiment provides a method for preparing copper powder using copper nitrate-containing wastewater. Except that the molar ratio of ascorbic acid to copper ions in the copper nitrate-containing wastewater in the second solution is 1:1, the method is the same as in Example 1.

[0079] Example 7

[0080] This embodiment provides a method for preparing copper powder using copper nitrate-containing wastewater. Except for the fact that the molar ratio of ascorbic acid to copper ions in the copper nitrate-containing wastewater in the second solution is 1:1.8, the method is the same as in Example 1.

[0081] Example 8

[0082] This embodiment provides a method for preparing copper powder using copper nitrate-containing wastewater. Except for the ultrasonic treatment power being 25 kHz, the method is the same as in Example 1.

[0083] Example 9

[0084] This embodiment provides a method for preparing copper powder using copper nitrate-containing wastewater. Except for the ultrasonic treatment power being 55 kHz, the method is the same as in Example 1.

[0085] Comparative Example 1

[0086] This embodiment provides a method for preparing copper powder using copper nitrate-containing wastewater. The method is the same as in Example 1, except that the second solution is not ultrasonically treated but stirred for 40 minutes.

[0087] Comparative Example 2

[0088] This embodiment provides a method for preparing copper powder using copper nitrate-containing wastewater. The method is the same as in Example 1, except that the first solution is not prepared and ascorbic acid and polyvinylpyrrolidone are directly added to the copper nitrate-containing wastewater.

[0089] Performance testing:

[0090] The purity of the copper powder prepared in all the above examples and comparative examples was tested using GDMS (glow discharge mass spectrometry), and the test results are shown in Table 1.

[0091] In this invention, the copper recovery rate in wastewater is calculated as follows:

[0092] Copper ion recovery rate = (1 - copper ion concentration in the solution after reaction / copper ion concentration in the copper nitrate wastewater before reaction) × 100%.

[0093] Table 1

[0094]

[0095] According to the test results in Table 1, the method for preparing copper powder using copper nitrate-containing wastewater provided by this invention has a copper recovery rate of over 99% in the wastewater, and the purity of the prepared copper powder can reach 5N.

[0096] According to the test results of Example 1 and Comparative Example 1, if ultrasonic treatment is not performed, the copper powder will severely agglomerate, easily encapsulating impurities and resulting in a decrease in purity.

[0097] According to the test results of Example 1 and Comparative Example 2, if the first solution is not prepared and ascorbic acid and polyvinylpyrrolidone are directly added to the wastewater containing copper nitrate, the prepared copper powder particles are large and uneven, and contain impurities, resulting in a decrease in purity.

[0098] According to the test results of Examples 1, 4 and 5, if the molar ratio of ascorbic acid to PVP is too large, the excess ascorbic acid will be oxidized to produce oxalate, which will combine with copper ions to form copper oxalate, affecting the purity and recovery rate of copper powder; if the molar ratio of ascorbic acid to PVP is too small, PVP will easily remain, affecting the purity of copper powder.

[0099] According to the test results of Examples 1, 6 and 7, if the molar ratio of ascorbic acid to copper ions is too large, the reduction reaction will be incomplete and the copper ion recovery rate will be too low; if the molar ratio of ascorbic acid to copper ions is too small, excess ascorbic acid will be easily oxidized to produce oxalate, which will combine with copper ions to form copper oxalate, affecting the purity and recovery rate of copper powder.

[0100] According to the test results of Examples 1, 8 and 9, if the ultrasonic power is too high, the prepared copper powder particles are small and more easily oxidized, affecting the purity of the copper powder; if the ultrasonic power is too low, the copper powder will agglomerate, encapsulate impurities, and the purity of the copper powder will deteriorate.

[0101] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing copper powder using copper nitrate-containing wastewater, characterized by, The method includes: A reducing agent and a dispersant are mixed in a solvent to obtain a first solution; copper nitrate wastewater is added to the first solution to obtain a second solution; the second solution is ultrasonically treated; and the copper powder is obtained by solid-liquid separation.

2. The method of claim 1, wherein, In the first solution, the molar ratio of reducing agent to dispersant is (2~3):1; And / or, in the second solution, the molar ratio of the reducing agent to copper ions in the copper nitrate-containing wastewater is (1.1~1.5):

1.

3. The method of claim 1, wherein, The reducing agent includes any one or a combination of at least two of ascorbic acid, sodium phosphite, hydrazine hydrate, isopropanol, octadecyl mercaptan, or propyl gallate; And / or, the dispersant comprises any one or a combination of at least two of polyvinylpyrrolidone, octadecylamine, triethanolamine, or sodium dodecyl sulfonate.

4. The method of claim 1, wherein, Before adding copper nitrate-containing wastewater to the first solution, the pH of the first solution is adjusted to 11-13.

5. The method of claim 1, wherein, Before adding copper nitrate-containing wastewater to the first solution, the process also includes heating the first solution to 45°C~60°C.

6. The method of claim 1, wherein, The power of the ultrasonic treatment is 30kHz~50kHz; And / or, the duration of the ultrasonic treatment is 30 min to 60 min.

7. The method of claim 1, wherein, The solid-liquid separation method includes centrifugation.

8. The method of claim 1, wherein, The method also includes washing, drying and sieving the copper powder.

9. The method of claim 8, wherein, The washing method includes rinsing with dilute sulfuric acid and ethanol in sequence.

10. The method of claim 8, wherein, The drying method includes vacuum drying.

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