Regenerated copper and waste copper regeneration method, low-oxygen copper bar and preparation method and application thereof

Abstract

The application belongs to the technical field of waste copper recovery, and particularly relates to a method for regenerating waste copper and copper, a low-oxygen copper and a preparation method and application thereof. The method for regenerating waste copper comprises the following steps: after waste copper is impurity-removed by a sulfuric acid solution, solid matter is mixed with nitric acid to obtain a mixed solution; the mixed solution is mixed with a copper masking agent and then mixed with an impurity complexing agent; a filtrate is added with an oxidizing agent and then mixed with a copper complexing agent; and the precipitate is subjected to reduction treatment to obtain regenerated copper. The method for regenerating waste copper provided by the application has high purity, high recovery rate and low oxygen content.

Description

Technical Field

[0001] This invention belongs to the field of waste copper recycling technology, specifically relating to a recycled copper and a waste copper recycling method, a low-oxygen copper busbar and its preparation method and application. Background Technology

[0002] Scrap copper mainly includes new scrap copper and used scrap copper. New scrap copper is waste generated during the production, processing, and manufacturing of copper and copper alloy products; used scrap copper refers to copper materials that have been used and is the main source of scrap copper resources. The main sources of used scrap copper include construction and power facilities, electronics and electrical equipment, industrial equipment, transportation, and other daily consumer goods (such as decorations, musical instruments, hardware, etc.).

[0003] New scrap copper is typically well-defined, clean, and easy to recycle, with most of it being directly recycled within the production system. However, used scrap copper, having undergone use, contains more impurities, making recycling more difficult. Low-grade scrap copper (copper content below 85%) is particularly problematic. While the annual output is large, the dispersed sources of scrap copper, the complexity of existing recycling processes, high recycling costs, and low economic value make its recycling a significant technical challenge for recycled copper. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a method for recycling copper and waste copper, a low-oxygen copper busbar and its preparation method and application, thereby solving at least one aspect of the above-mentioned technical problems.

[0005] This invention is achieved through the following technical solution: In a first aspect, the present invention provides a method for recycling waste copper, comprising the following steps: After impurities are removed from the waste copper with sulfuric acid solution, the solid is mixed with nitric acid to obtain a mixed solution. The mixture is mixed with the copper masking agent and then with the impurity complexing agent; After adding the oxidizing agent to the filtrate, mix it with the copper complexing agent; The precipitate was subjected to reduction treatment to obtain recycled copper.

[0006] Secondly, the present invention provides recycled copper obtained by the above-mentioned waste copper recycling method.

[0007] Thirdly, the present invention provides a low-oxygen copper busbar, the raw material of which includes the aforementioned recycled copper.

[0008] Fourthly, the present invention provides a method for preparing the above-mentioned low-oxygen copper busbar, comprising the following steps: The recycled copper is used to make a copper busbar matrix.

[0009] The waste copper recycling method provided by this invention has at least the following beneficial technical effects compared with the prior art: The waste copper recycling method provided by this invention produces recycled copper with high purity (above 99.3%), high recovery rate (above 98.5%) and low oxygen content (below 30ppm).

[0010] The low-oxygen copper busbar provided by this invention has at least the following beneficial technical effects compared with the prior art: The low-oxygen copper busbar provided by this invention has a tensile strength of over 453 MPa and an electrical conductivity of over 100% IACS. Detailed Implementation

[0011] To make the objectives, technical solutions, and advantages of this invention clearer, the invention is described and illustrated below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. All other embodiments obtained by those skilled in the art based on the embodiments provided by this invention without inventive effort are within the scope of protection of this invention.

[0012] Obviously, the following description is merely some examples or embodiments of the present invention. Those skilled in the art can apply the present invention to other similar scenarios without any inventive effort. Furthermore, it is understood that although the effort involved in such development may be complex and lengthy, for those skilled in the art related to the content disclosed in this invention, modifications to design, manufacturing, or production based on the technical content disclosed in this invention are merely conventional technical means and should not be construed as insufficient disclosure of the present invention.

[0013] However, there may be instances where unnecessary detailed descriptions are omitted. For example, detailed descriptions of well-known matters or repetitive descriptions of essentially the same structures may be omitted. This is to avoid making the following description unnecessarily lengthy and to facilitate understanding by those skilled in the art. Furthermore, the following description is provided to enable those skilled in the art to fully understand the invention and is not intended to limit the subject matter of the claims.

[0014] Unless otherwise specified, all embodiments and optional embodiments of the present invention can be combined with each other to form new technical solutions, and all technical features and optional technical features of the present invention can be combined with each other to form new technical solutions.

[0015] There are two main categories of methods for recycling scrap copper: pyrometallurgy and electrolytic refining. While pyrometallurgy can be used to smelt scrap copper ranging from very low to high grades, it generates a large amount of slag for low-grade and lower scrap copper, resulting in a low copper recovery rate. Furthermore, if the scrap copper contains nickel, it easily forms a solid solution with copper, making complete separation through pyrometallurgy difficult and reducing the purity of the recycled copper. Electrolytic refining, although it can significantly improve copper purity, can only refine high-grade scrap copper with a copper content of 96.5% or higher. Its application is narrow, and it has high energy consumption, large equipment investment, and a long production cycle, making it unsuitable for recycling large quantities of low-grade scrap copper.

[0016] To achieve effective recycling and utilization of low-grade scrap copper, this invention provides a scrap copper regeneration method, a low-oxygen copper busbar, its preparation method, and its application. By utilizing the characteristics of the main ionic components in scrap copper, impurities are first removed and then copper is reduced to obtain high-purity oxygen-free copper, which is then made into a low-oxygen copper busbar, enabling the widespread and effective utilization of low-grade scrap copper resources.

[0017] The following is a detailed description of a waste copper recycling method, a low-oxygen copper busbar, its preparation method, and its application according to embodiments of the present invention.

[0018] The first aspect of this invention provides a method for recycling waste copper, comprising the following steps: S10. After the waste copper is purified by sulfuric acid solution, the solid is mixed with nitric acid to obtain a mixed solution.

[0019] S20. The mixture is mixed with the copper masking agent and then mixed with the impurity complexing agent.

[0020] S30. After adding the oxidant to the filtrate, mix it with the copper complexing agent.

[0021] S40. Take the precipitate and perform reduction treatment to obtain recycled copper.

[0022] The waste copper recycling method provided in this invention involves removing impurities from the waste copper using sulfuric acid solution to remove metals more reactive than copper (such as iron, magnesium, and aluminum) that are soluble in sulfuric acid. The copper is then dissolved in nitric acid, and copper ions are masked using a copper masking agent. An impurity complexing agent is then added to further remove impurity ions. An oxidant is added to the solution to release copper ions, and the solution is then mixed with the copper complexing agent to precipitate the copper as a complex. The precipitate is then subjected to reduction treatment to obtain recycled copper. The waste copper recycling method provided in this invention produces elemental copper with high purity, high recovery rate, and low oxygen content.

[0023] In some embodiments, in step S10 above, the copper content in the scrap copper is less than 85%.

[0024] In some embodiments, in step S10 above, the particle size D50 of the scrap copper is 1 mm to 10 mm.

[0025] In some embodiments, in step S10 above, the solid-liquid ratio of waste copper to sulfuric acid is 1:(2~3).

[0026] In some embodiments, in step S10 above, the concentration of the sulfuric acid solution is 0.5 mol / L to 1 mol / L.

[0027] In some embodiments, the purification of the sulfuric acid solution in step S10 above includes the following steps: S101. Under mechanical stirring, waste copper is placed in a sulfuric acid solution for constant temperature impurity removal.

[0028] In some embodiments, in step S101 above, the mechanical stirring speed is 100 rpm to 300 rpm.

[0029] In some embodiments, the isothermal purification temperature in step S101 is 25°C to 35°C. In this case, the reaction between the active metals in the waste copper and sulfuric acid is exothermic, causing the temperature of the reaction system to rise. This increased temperature leads to instability in the reaction system and may cause partial reaction of the copper. It should be noted that the isothermal purification time can be adjusted according to actual production conditions; a higher impurity content requires a corresponding increase in time. This is not specifically limited in the embodiments of the present invention, but for illustrative purposes, the isothermal purification time in the embodiments of the present invention is 0.5 h to 1 h.

[0030] In some embodiments, taking the solid object in step S10 above includes the following steps: S102. After removing impurities with sulfuric acid solution, the reaction system is filtered, washed, and dried to constant weight.

[0031] In some embodiments, the filtration method in step S102 described above includes vacuum filtration.

[0032] In some embodiments, in step S102 above, washing includes the following steps: S1021. Wash the filter residue with water until the water is neutral.

[0033] In some embodiments, in step S102 above, the drying temperature is 80°C to 100°C.

[0034] In some embodiments, in step S10 above, the concentration of nitric acid is 4 mol / L to 8 mol / L.

[0035] In some embodiments, in step S10 above, mixing the solid with nitric acid includes the following steps: S103. Mix the solid with nitric acid under mechanical stirring and constant temperature to obtain a mixture.

[0036] The above-mentioned solids are mixed with nitric acid, and mechanical stirring promotes the dissolution of the solids. Maintaining a constant temperature ensures a stable reaction between the solids and nitric acid, guaranteeing both the dissolution rate of copper and the safety of the reaction system. It should be noted that the amount of nitric acid used can be adjusted according to actual production conditions; generally, an excess of nitric acid is required to ensure complete dissolution of the copper in the solids.

[0037] In some embodiments, in step S103 above, the mechanical stirring speed is 100 rpm to 300 rpm.

[0038] In some embodiments, in step S103 above, the constant temperature is 15°C to 25°C.

[0039] In some embodiments, in step S20 above, the copper masking agent includes sodium thiosulfate.

[0040] In some embodiments, the mixing of the mixture with the copper masking agent in step S20 above includes the following steps: S201. After adjusting the pH of the mixture to 7-9, mix it with the copper masking agent.

[0041] In the mixing of the above-mentioned solution with the copper masking agent, the pH value of the solution is adjusted to 7-9 to allow the copper ions to fully react with the copper masking agent to form a soluble copper complex. It should be noted that the amount of copper masking agent used can be adjusted according to actual production conditions; generally, an excess is required, and the final solution color is typically dark brownish-purple.

[0042] In some embodiments, in step S20 above, the impurity complexing agent includes component A and component B; Component A includes ethyl hydroxyethylidene diphosphonate; Component B includes dimethylglyoxime reagent.

[0043] Among the above-mentioned impurity complexing agents, component A can remove residual calcium ions, magnesium ions and other impurity metal ions in the mixture, and ethyl hydroxyethylidene diphosphonate can slow down the coordination reaction rate of calcium ions and magnesium ions, thereby reducing the occurrence of side reactions; the dimethylglyoxime contained in component B can specifically remove nickel ions with properties similar to copper, reducing the impurities brought out by subsequent copper precipitation.

[0044] In some embodiments, the preparation of ethyl hydroxyethylidene diphosphonate includes the following steps: Anhydrous hydroxyethylidene diphosphonic acid (HEDP) was mixed with an excess of triethyl phosphite and refluxed under an inert protective atmosphere.

[0045] In the preparation of ethyl hydroxyethylidene diphosphonate described above, the inert protective gas prevents the reaction from contacting water, which could lead to the hydrolysis of triethyl phosphite. The main reaction occurring during reflux is: HEDP + 4(C2H) 50In the reaction 3P→(C2H5O)2P(O)-C(OH)(CH3)-P(O)(OC2H5)2+4C2H5OH, ethanol is distilled off as a byproduct during the reflux reaction. The distilled ethanol can be collected using a fractionating column, which helps shift the reaction equilibrium to the right and increase the yield.

[0046] In some embodiments, the inert protective gas includes at least one of helium, argon, and nitrogen.

[0047] In some embodiments, the reflux reaction temperature is 120℃~140℃. It should be noted that the reflux reaction time is determined by the reaction endpoint and can be adjusted according to the actual preparation situation. In the embodiments of this invention, no special limitation is made. The reaction endpoint is generally when the amount of ethanol distilled reaches or approaches the theoretical calculation amount, that is, 1 mol of HEDP should produce 4 mol of ethanol when it reacts completely. When the amount of distillate reaches more than 90% of the theoretical value and there is no new distillate added per unit time, it is the reaction endpoint.

[0048] In some embodiments, the preparation of ethyl hydroxyethylidene diphosphonate further includes the following steps: The crude product was subjected to high-vacuum distillation to obtain ethyl hydroxyethylidene diphosphonate.

[0049] In some embodiments, the step of obtaining the crude product includes: removing excess triethyl phosphite and residual ethanol by vacuum distillation.

[0050] In some embodiments, the dimethylglyoxime reagent comprises the following components by mass fraction: Dimethylglyoxime 0.5%~1%, balance ethanol.

[0051] In some embodiments, the mixing with the impurity complexing agent in step S20 above includes the following steps: S202. Maintain the pH value at 7-9, mix with component A, and then mix the filtrate with component B.

[0052] In the above-mentioned step of mixing the mixture with the impurity complexing agent, the pH value is maintained at 7-9 to stabilize the copper complex in the solution before mixing with the impurity complexing agent, causing the impurity ions to precipitate out. It should be noted that the amount of impurity complexing agent can be adjusted according to the actual production situation. Generally, an excess is required to ensure that the impurity ions precipitate out as completely as possible. The reaction endpoint is generally when no more precipitate is formed.

[0053] In some embodiments, the oxidant in step S30 above includes ozone. In this case, ozone has extremely strong oxidizing power, which can not only completely destroy the complex, but also does not introduce new impurities. The byproducts of the reaction between oxygen and sodium thiosulfate of copper are O2 and SO4. 2-It should be noted that the amount of oxidant used can be adjusted according to the actual production situation. Generally, an excess is required to completely dissociate copper ions from the complex.

[0054] In some embodiments, in step S30 above, the copper complexing agent includes a precipitant and a flocculant.

[0055] In some embodiments, the precipitant comprises zinc dimethyl dithiocarbamate.

[0056] In some embodiments, the CAS number of zinc dimethyl dithiocarbamate is 137-30-4.

[0057] In some embodiments, the flocculant includes polydimethyldiallylammonium chloride.

[0058] In some embodiments, the CAS number of polydimethyldiallylammonium chloride is 26062-79-3.

[0059] In some embodiments, the mixing with the copper complexing agent in step S30 above includes the following steps: S301. Adjust the pH value to 4.0~6.0, mix and stir the filtrate after oxidation with the oxidant and the precipitant, then add the flocculant and continue stirring.

[0060] In some embodiments, in step S301 above, sulfuric acid is used to adjust the pH value of the filtrate.

[0061] In some embodiments, in step S301 above, the mixing speed is 150 rpm to 200 rpm.

[0062] In some embodiments, in step S301 above, the mixing and stirring time is 15 min to 30 min.

[0063] In some embodiments, continuing to stir in step S301 above includes the following steps: S3011. Stir at a stirring speed of 150 rpm to 200 rpm for 2 min to 5 min, then adjust the stirring speed to 30 rpm to 40 rpm and stir for 10 min to 20 min.

[0064] During the continued stirring, stirring at a speed of 150 rpm to 200 rpm can promote the uniform dispersion of flocculant; adjusting the stirring speed to 30 rpm to 40 rpm and stirring at a low speed promotes the growth of flocs.

[0065] In some embodiments, the restoration process in step S40 above includes the following steps: S401. After removing impurities from the precipitate, calcine it under a reducing atmosphere.

[0066] In the above reduction process, the precipitate is cleaned of impurities such as excess water, nitrate, sulfate, and zinc ions. Then, it is calcined in a reducing atmosphere to reduce the copper compound to elemental copper.

[0067] In some embodiments, in step S401 above, removing impurities from the precipitate includes the following steps: S4011. After washing the precipitate with water, dry it at 100℃~150℃ to constant weight.

[0068] In the above process of removing impurities from the precipitate, water is used to wash away impurities such as nitrate, sulfate, and zinc ions, and then the water is removed by drying at 100℃~150℃.

[0069] In some embodiments, in step S401 above, the reducing atmosphere comprises a mixture of hydrogen and helium. In some embodiments, the volume ratio of hydrogen to helium in the mixture is 1:(2~5). In this case, the hydrogen concentration is low and it does not come into contact with oxygen, reducing the risk of hydrogen reduction.

[0070] In some embodiments, in step S401 above, calcination includes the following steps: S4012. After heating to 200℃~300℃ for the first heat preservation, heat to 400℃~600℃ for the second heat preservation.

[0071] In the above roasting process, the first holding temperature is 200℃~300℃ to remove residual moisture and solvent from the precipitate and to initiate the initial decomposition of organic matter; the second holding temperature is 400℃~600℃ to cause the precipitate to decompose and copper to be reduced.

[0072] In some embodiments, in step S4012 above, the heating rate to 200°C to 300°C is 5°C / min to 10°C / min.

[0073] In some embodiments, in step S4012 above, the first heat preservation time is 30 min to 60 min.

[0074] In some embodiments, in step S4012 above, the heating rate to 400°C to 600°C is 5°C / min to 10°C / min.

[0075] In some embodiments, in step S4012 above, the second heat preservation time is 60 min to 120 min.

[0076] A second aspect of the present invention provides a low-oxygen copper busbar, the raw material of which includes recycled copper obtained by the above-mentioned waste copper recycling method.

[0077] The low-oxygen copper busbar provided in this embodiment of the invention comprises recycled copper obtained by the waste copper recycling method provided in this embodiment of the invention, wherein the oxygen content is below 30 ppm.

[0078] In some embodiments, the raw materials for the low-oxygen copper busbar also include silver and magnesium. In this case, trace amounts of silver are dissolved in copper, which can improve the recrystallization temperature and creep resistance without significantly impairing conductivity; magnesium reacts with free oxygen in the recycled copper to generate thermodynamically stable in-situ MgO nanoparticles, which transforms the unstable dissolved oxygen in the recycled copper into a stable and beneficial reinforcing phase.

[0079] In some embodiments, the silver content is 5ppm to 8ppm.

[0080] In some embodiments, the magnesium content is 30ppm to 35ppm.

[0081] A third aspect of this invention provides a method for preparing a low-oxygen copper busbar, comprising the following steps: X10. Use recycled copper to make copper busbar matrix.

[0082] The method for preparing low-oxygen copper busbars provided in this invention involves annealing recycled copper busbars to form a copper busbar matrix. The resulting low-oxygen copper busbars have extremely low oxygen content and exhibit high tensile strength and high-temperature resistance.

[0083] In some embodiments, in step X10 above, the process of forming a copper busbar matrix from recycled copper includes the following steps: X101. In an ultra-high vacuum, recycled copper, silver and magnesium are mixed and melted, then subjected to a strong static magnetic field and kept at high temperature.

[0084] X102. The copper billet obtained by high-temperature heat preservation is rolled to obtain the copper busbar matrix.

[0085] In the above-mentioned process of making copper busbar matrix from recycled copper, ultra-high vacuum can prevent recycled copper from coming into contact with oxygen and reduce the melting temperature of recycled copper, silver and magnesium. During melting, magnesium reacts with oxygen in recycled copper to form MgO. After melting, a strong static magnetic field is applied to the melt to suppress atomic diffusion and grain boundary migration, significantly refine the grain size of MgO and make its distribution extremely uniform, prevent the formation of coarse particles, and obtain a fine-grained copper busbar matrix.

[0086] In some embodiments, in step X101 above, the vacuum level of the ultra-high vacuum is <10. -3 Pa.

[0087] In some embodiments, in step X101 above, the mixing and melting of recycled copper, silver, and magnesium includes the following steps: X1011. After the recycled copper is melted, silver and magnesium are added separately.

[0088] In some embodiments, in step X101 above, the magnetic field strength of the strong static magnetic field is 10T or more.

[0089] In some embodiments, in step X101 above, the magnetic field strength of the strong static magnetic field is 10T~20T.

[0090] In some embodiments, in step X101 above, the temperature of the high-temperature insulation is 1150℃~1200℃.

[0091] In some embodiments, in step X101 above, the high-temperature heat preservation time is 1h to 2h.

[0092] In some embodiments, in step X102 above, the rolling process includes the following steps: X1021. Roll the copper billet into a copper strip of a predetermined thickness, and then roll it at a speed of 1.1 × 10⁻⁶. 6 ℃ / s ~1.3×10 6 After cooling to 250℃~350℃ at a cooling rate of ℃ / s, annealing is performed to obtain low-oxygen copper busbars.

[0093] In the above rolling process, with a rolling strength of 1.1 × 10⁻⁶ 6 ℃ / s ~1.3×10 6 Cooling at a rate of ℃ / s allows the copper strip to form a supersaturated solid solution and a non-equilibrium microstructure. Low-temperature annealing releases internal stress in the copper strip, promotes dislocation reorganization, and forms a stable "dislocation wall" substructure. At the same time, nano-oxide particles effectively pin grain boundaries and inhibit grain growth.

[0094] In some embodiments, in step X1021 above, the rolling temperature is 900°C to 1000°C.

[0095] In some embodiments, in step X1021 above, the thickness of the copper strip is 4mm to 10mm.

[0096] In some embodiments, in step X1021 above, during the annealing process, the copper strip is cooled to below 150°C by water cooling, air cooling, or wind cooling.

[0097] The following description, in conjunction with specific embodiments, provides further details. For ease of explanation, the following embodiments and comparative examples involve: (1) The copper content in the scrap copper is 80%±5%, and the particle size D50 of the scrap copper is 8mm.

[0098] (2) The concentration of the sulfuric acid solution is 0.8 mol / L.

[0099] (3) The concentration of nitric acid is 6 mol / L.

[0100] (4) The preparation steps of ethyl hydroxyethylidene diphosphonate are as follows: Under argon protection, anhydrous hydroxyethylidene diphosphonic acid (HEDP) is mixed with an excess of triethyl phosphite and refluxed at 130°C. The reaction endpoint is reached when the amount of distillate reaches more than 90% of the theoretical value and no new distillate is produced per unit time.

[0101] Excess triethyl phosphite and residual ethanol were removed by vacuum distillation to obtain the crude product.

[0102] The crude product was subjected to high-vacuum distillation to obtain ethyl hydroxyethylidene diphosphonate.

[0103] (5) The dimethylglyoxime reagent consists of the following components by mass fraction: Dimethylglyoxime 0.5%~1%, balance ethanol.

[0104] Example 1 Example 1 provides a method for recycling waste copper, the steps of which are as follows: E10. Purification with sulfuric acid solution Waste copper was placed in a sulfuric acid solution under mechanical stirring for constant-temperature impurity removal. The mechanical stirring speed was 200 rpm, the constant-temperature impurity removal temperature was 30℃, and the time was 0.8 h.

[0105] E20. Take solid objects After the reaction system was purified with sulfuric acid solution, it was filtered, and the filter residue was washed with water until neutral and then dried to constant weight. The drying temperature was 100℃.

[0106] E30. Preparation of the mixture A solid was mixed with nitric acid under mechanical stirring and constant temperature to obtain a mixture. The mechanical stirring speed was 200 rpm, and the constant temperature was 20℃.

[0107] E40. Masking copper ions After adjusting the pH of the mixture to 8, it is mixed with sodium thiosulfate to obtain a solution with copper ions masked.

[0108] E50. Mixed with impurity complexing agents Maintain the pH at 8, mix the copper-masked solution with ethyl hydroxyethylidene diphosphonate, filter the solution, and mix the filtrate with dimethylglyoxime reagent.

[0109] E60. Oxidative complex E60-1. Filter the solution system obtained in step E50 and collect the filtrate.

[0110] E60-2. Oxidize the filtrate by introducing excess ozone.

[0111] E60-3. Adjust the pH to 5.0, add excess zinc dimethyl dithiocarbamate and mix. The mixing speed is 180 rpm and the time is 20 min.

[0112] E60-4. Add polydimethyldiallylammonium chloride, stir at 180 rpm for 3 min, then adjust the stirring speed to 35 rpm and stir for 18 min; to obtain a complex precipitate.

[0113] E70. Reduction Processing E70-1. Filter the complexed precipitate to obtain the precipitate.

[0114] E70-2. After washing the precipitate with water, dry it at 120°C to constant weight.

[0115] E70-3. Under a reducing atmosphere of a mixture of hydrogen and helium in a volume ratio of 1:3, the temperature is increased to 250℃ at a heating rate of 8℃ / min and held for 40 min; then the temperature is increased to 500℃ at a heating rate of 8℃ / min and held for 80 min to obtain recycled copper.

[0116] Example 2 Example 2 provides a method for recycling waste copper, the steps of which are basically the same as those in Example 1, except that: E60-3. Adjust the pH to 4.0, add excess zinc dimethyl dithiocarbamate and mix. The mixing speed is 150 rpm and the time is 15 min.

[0117] E60-4. Add polydimethyldiallylammonium chloride, stir at 200 rpm for 2 min, then adjust the stirring speed to 40 rpm and stir for 10 min; to obtain a complex precipitate.

[0118] E70-3. Under a reducing atmosphere of a mixture of hydrogen and helium in a volume ratio of 1:2, the temperature is increased to 200℃ at a heating rate of 5℃ / min and held for 60 min; then the temperature is increased to 400℃ at a heating rate of 5℃ / min and held for 120 min; thus, recycled copper is obtained.

[0119] Example 3 Example 3 provides a method for recycling waste copper, the steps of which are basically the same as those in Example 1, except that: E60-3. Adjust the pH to 6.0, add excess zinc dimethyl dithiocarbamate and mix. The mixing speed is 200 rpm and the time is 30 min.

[0120] E60-4. Add polydimethyldiallylammonium chloride, stir at 150 rpm for 5 min, then adjust the stirring speed to 30 rpm and stir for 20 min; to obtain a complex precipitate.

[0121] E70-3. Under a reducing atmosphere of a mixture of hydrogen and helium in a volume ratio of 1:5, the temperature is increased to 300℃ at a heating rate of 10℃ / min and held for 30 min; then the temperature is increased to 600℃ at a heating rate of 10℃ / min and held for 60 min; thus, recycled copper is obtained.

[0122] Comparative Example 1 Comparative Example 1 provides a method for recycling waste copper, the steps of which are as follows: D10. Preparation of the mixture Waste copper was mixed with nitric acid under mechanical stirring and constant temperature to obtain a mixture. The mechanical stirring speed was 200 rpm, and the constant temperature was 20℃.

[0123] D20. Masking copper ions After adjusting the pH of the mixture to 8, it is mixed with sodium thiosulfate to obtain a solution with copper ions masked.

[0124] D30. Mixed with impurity complexing agents Maintain the pH at 8, mix the copper-masked solution with ethyl hydroxyethylidene diphosphonate, filter the solution, and mix the filtrate with dimethylglyoxime reagent.

[0125] D40. Oxidative complex D40-1. Filter the solution system obtained in step D30 and collect the filtrate.

[0126] D40-2. Oxidize the filtrate by introducing excess ozone.

[0127] D40-3. Adjust the pH to 5.0, add excess zinc dimethyl dithiocarbamate and mix. The mixing speed is 180 rpm and the time is 20 min.

[0128] D40-4. Add polydimethyldiallylammonium chloride, stir at 180 rpm for 3 min, then adjust the stirring speed to 35 rpm and stir for 18 min; to obtain a complex precipitate.

[0129] D50. Reduction Process D50-1. Filter the complexed precipitate to obtain the precipitate.

[0130] D50-2. After washing the precipitate with water, dry it at 120°C to constant weight.

[0131] D50-3. Under a reducing atmosphere of a mixture of hydrogen and helium in a volume ratio of 1:3, the temperature is increased to 250℃ at a heating rate of 8℃ / min and held for 40 min; then the temperature is increased to 500℃ at a heating rate of 8℃ / min and held for 80 min to obtain recycled copper.

[0132] Comparative Example 2 Comparative Example 2 provides a method for recycling waste copper, the steps of which are as follows: D11. Purification with sulfuric acid solution Waste copper was placed in a sulfuric acid solution under mechanical stirring for constant-temperature impurity removal. The mechanical stirring speed was 200 rpm, the constant-temperature impurity removal temperature was 30℃, and the time was 0.8 h.

[0133] D21. Take solid objects After the reaction system was purified with sulfuric acid solution, it was filtered, and the filter residue was washed with water until neutral and then dried to constant weight. The drying temperature was 100℃.

[0134] D31. Preparation of the mixture A solid was mixed with nitric acid under mechanical stirring and constant temperature to obtain a mixture. The mechanical stirring speed was 200 rpm, and the constant temperature was 20℃.

[0135] D41. Complexation D41-1. Adjust the pH to 5.0, add excess zinc dimethyl dithiocarbamate and mix. The mixing speed is 180 rpm and the mixing time is 20 min.

[0136] D41-2. Add polydimethyldiallylammonium chloride, stir at 180 rpm for 3 min, then adjust the stirring speed to 35 rpm and stir for 18 min; to obtain a complex precipitate.

[0137] D51. Reduction Process D51-1. Filter the complexed precipitate to obtain the precipitate.

[0138] D51-2. After washing the precipitate with water, dry it at 120°C to constant weight.

[0139] D51-3. Under a reducing atmosphere of a mixture of hydrogen and helium in a volume ratio of 1:3, the temperature is increased to 250℃ at a heating rate of 8℃ / min and held for 40 min; then the temperature is increased to 500℃ at a heating rate of 8℃ / min and held for 80 min to obtain recycled copper.

[0140] Comparative Example 3 Comparative Example 3 provides a method for recycling waste copper, the steps of which are basically the same as those in Example 1, except that: In step E40, the pH of the mixture is adjusted to 11.

[0141] Comparative Example 4 Comparative Example 4 provides a method for recycling waste copper, the steps of which are basically the same as those in Example 1, except that: In step E60-2, the oxidant is potassium permanganate.

[0142] Example 4 Example 4 provides a low-oxygen copper busbar, the raw material of which consists of the following components by mass fraction: 7 ppm silver, 32 ppm magnesium, the remainder being recycled copper; The recycled copper was obtained by the waste copper recycling method of Example 1.

[0143] This embodiment also provides a method for preparing low-oxygen copper busbars, the steps of which are as follows: F10. Melting In an ultra-high vacuum environment, molten recycled copper is added to silver and magnesium separately. After melting, a strong static magnetic field is applied and the mixture is held at high temperature. The vacuum level in the ultra-high vacuum is <10. -3 Pa; the magnetic field strength of the strong static magnetic field is 15T; the high temperature holding temperature is 1180℃ and the time is 1.5h.

[0144] F20. Rolling treatment The copper billet is rolled into a copper strip of a predetermined thickness, and then rolled at 1.1 × 10⁻⁶ mm. 6 The temperature was reduced to 300°C at a cooling rate of ℃ / s, and then air-cooled to below 150°C to obtain the low-oxygen copper busbar of this embodiment. The rolling temperature was 950°C.

[0145] Example 5 Example 5 provides a low-oxygen copper busbar, the raw material of which consists of the following components by mass fraction: 5 ppm silver, 30 ppm magnesium, and the remainder is recycled copper; The recycled copper was obtained by the waste copper recycling method of Example 2.

[0146] This embodiment also provides a method for preparing low-oxygen copper busbars, the steps of which are basically the same as those in Example 4, except that the recycled copper is obtained by the waste copper recycling method in Example 2.

[0147] Example 6 Example 6 provides a low-oxygen copper busbar, the raw material of which consists of the following components by mass fraction: 8 ppm silver, 35 ppm magnesium, and the remainder is recycled copper; The recycled copper was obtained by the waste copper recycling method of Example 3.

[0148] This embodiment also provides a method for preparing low-oxygen copper busbars, the steps of which are basically the same as those in Example 4, except that the recycled copper is obtained by the waste copper recycling method in Example 3.

[0149] Comparative Example 5 Comparative Example 5 provides a copper busbar, the raw material of which is composed of the following components by mass fraction: 7 ppm silver, the remainder is recycled copper; The recycled copper was obtained by the waste copper recycling method of Example 1.

[0150] This comparative example also provides a method for preparing the above-mentioned copper busbar, the steps of which are basically the same as those in Example 4, except that: In step F10, only recycled copper and silver are melted.

[0151] Comparative Example 6 Comparative Example 6 provides a method for preparing a copper busbar, the steps of which are basically the same as those in Example 4, except that: In step F10, the magnetic field strength of the strong static magnetic field during melting is 5T.

[0152] To verify the advancements of the waste copper recycling method, low-oxygen copper busbar, and preparation method provided in this invention, the oxygen content, recovery rate, and purity of the recycled copper prepared in the embodiments and comparative examples of this invention were tested, and the results are shown in Table 1 below. The tensile strength and electrical conductivity of the copper busbars prepared in the embodiments and comparative examples of this invention were tested, and the results are shown in Table 2 below.

[0153] Table 1

[0154] Table 2

[0155] From the table above, at least the following conclusions can be drawn: (1) The present invention provides a method for recycling waste copper. Waste copper is purified by sulfuric acid solution to remove metals more reactive than copper (such as iron, magnesium, and aluminum) that are soluble in sulfuric acid. Then, copper is dissolved by mixing with nitric acid. After the copper ions are masked by a copper masking agent, an impurity complexing agent is added and mixed to further remove impurity ions. An oxidant is added to the solution to release copper ions. Then, the solution is mixed with a copper complexing agent to precipitate copper in the form of a complex. The precipitate is subjected to reduction treatment to obtain recycled copper. The oxygen content of the recycled copper is below 30 ppm. The purity is above 99.3%, which meets the standard of high-grade copper. The recovery rate is above 98.5%, which fully realizes the resource utilization of low-grade waste copper.

[0156] (2) The low-oxygen copper busbar provided in this embodiment of the invention contains silver and magnesium, and is prepared in combination with the preparation method of this embodiment of the invention, so that the tensile strength of the low-oxygen copper busbar of this embodiment of the invention is above 453 MPa and the electrical conductivity is above 100% IACS.

[0157] It should be noted that the present invention is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments that have the same structure and perform the same effects as the technical concept within the scope of the present invention are included within the scope of the present invention. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of the present invention, are also included within the scope of the present invention.

Claims

1. A method for recycling waste copper, characterized in that, Includes the following steps: After impurities are removed from the waste copper with sulfuric acid solution, the solid is mixed with nitric acid to obtain a mixed solution. The mixture is mixed with the copper masking agent and then with the impurity complexing agent; After adding the oxidizing agent to the filtrate, mix it with the copper complexing agent; The precipitate was subjected to reduction treatment to obtain recycled copper; The copper masking agent includes sodium thiosulfate; The impurity complexing agent comprises component A and component B; Component A includes ethyl hydroxyethylidene diphosphonate; Component B includes dimethylglyoxime reagent; The copper complexing agent includes a precipitant and a flocculant; The precipitant includes zinc dimethyl dithiocarbamate.

2. The waste copper recycling method according to claim 1, characterized in that, It satisfies at least one of the following characteristics (1) to (7): (1) The copper content in the scrap copper is below 85%; (2) The particle size D50 of the scrap copper is 1mm~10mm; (3) The solid-liquid ratio of the waste copper to sulfuric acid is 1:2~3; (4) The concentration of the sulfuric acid solution is 0.5 mol / L to 1 mol / L; (5) The concentration of the nitric acid is 4 mol / L to 8 mol / L; (6) The oxidant includes ozone; (7) The flocculant includes polydimethyldiallylammonium chloride.

3. The waste copper recycling method according to claim 1 or 2, characterized in that, It satisfies at least one of the following characteristics (1) to (7): (1) The purification of the sulfuric acid solution includes the following steps: The waste copper was placed in the sulfuric acid solution under mechanical stirring for constant temperature impurity removal; (2) The process of taking solid objects includes the following steps: The reaction system, after being purified with sulfuric acid solution, was filtered, washed, and dried to constant weight. (3) The mixing of the solid with nitric acid includes the following steps: Under mechanical stirring and constant temperature conditions, the solid was mixed with nitric acid to obtain a mixture. (4) The mixing of the mixture with the copper masking agent includes the following steps: After adjusting the pH of the mixture to 7-9, it is mixed with the copper masking agent; (5) The mixing with the impurity complexing agent includes the following steps: Maintain the pH value at 7-9, mix with component A, and then mix the filtrate with component B. (6) The mixing with the copper complexing agent includes the following steps: Adjust the pH value to 4.0~6.0, mix the filtrate after oxidation with the precipitant and stir, then add the flocculant and continue stirring; (7) The reduction process includes the following steps: After removing impurities from the precipitate, it was calcined under a reducing atmosphere.

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