Method for recovering copper and aluminum from copper-clad aluminum processing waste

Abstract

The embodiment of the present application provides a method for recovering copper and aluminum from copper-coated aluminum processing waste, and relates to the technical field of hydrometallurgy. The method comprises the following steps: using an electrolytic cell provided with an anion exchange membrane, the anion exchange membrane separates the electrolytic cell into an anode area and a cathode area; placing the copper-coated aluminum processing waste as an anode in the anode area and a cathode in the cathode area; filling the anode area with an anolyte containing sulfuric acid and an alkali metal sulfate, the alkali metal being potassium, rubidium or cesium; filling the cathode area with a catholyte containing sulfuric acid and copper sulfate; electrolyzing under power, depositing metallic copper at the cathode, generating alum precipitate in the anode area, and recovering the metallic copper and the alum precipitate respectively. The method for recovering copper and aluminum from copper-coated aluminum processing waste in the embodiment of the present application electrolyzes the copper-coated aluminum processing waste by electrolysis, the copper in the waste is preferentially dissolved, the exposed aluminum is synchronously dissolved and immediately combined with alkali metal ions and sulfate radicals in situ to generate alum precipitate, thereby realizing efficient and complete separation of copper and aluminum components.

Description

Technical Field

[0001] This invention relates to the field of hydrometallurgical technology, and in particular to a method for recovering copper and aluminum from copper-clad aluminum processing waste. Background Technology

[0002] Copper-clad aluminum composite material is a typical bimetallic functional material. It is formed by coating a high-purity aluminum core with a layer of dense pure copper, and then forming a robust integral structure through metallurgical bonding or atomic diffusion at the interface. This material combines the excellent conductivity and oxidation resistance of copper with the low density and low cost of aluminum, and is therefore widely used in high-end electrical fields such as high-frequency coaxial cables, high-current busbars, and power transmission wires.

[0003] However, during the rolling, drawing, annealing, and subsequent processing of copper-clad aluminum materials, limitations such as process control precision, equipment stability, and material deformation coordination inevitably generate a large amount of scrap, defective billets, broken wires, and decommissioned conductors. In these scraps, copper and aluminum coexist in a tightly metallurgically bonded state, making physical separation extremely difficult. Therefore, efficient recycling technologies are urgently needed to achieve resource recycling.

[0004] Currently, the recycling of such composite waste mainly relies on two traditional methods: one is pyrometallurgical smelting, which involves melting the waste at high temperatures and then separating it into layers or slag. Although aluminum has a lower melting point than copper, it is easily oxidized and burned off during high-temperature smelting, and copper and aluminum easily form high-melting-point intermetallic compounds, resulting in low aluminum recovery rates, high energy consumption, and severe dust pollution. The second method is conventional wet acid leaching, which typically uses hydrochloric acid or sulfuric acid systems to dissolve the metal. However, because copper and aluminum dissolve simultaneously in acid, Cu is formed. 2+ With Al 3+ The mixed solution requires subsequent separation through multi-stage extraction, precipitation, or ion exchange, which is lengthy, consumes a lot of reagents, and produces wastewater containing heavy metals and high salt content, resulting in high treatment costs and difficulty in obtaining high-value products.

[0005] Therefore, existing technologies for processing copper-clad aluminum processing waste generally suffer from problems such as incomplete component separation, low recovery rate of valuable metals, low added value of products, and high risk of secondary pollution, making it difficult to meet the development requirements of green metallurgy and circular economy. Summary of the Invention

[0006] To address the technical problems existing in the prior art, this invention provides a method for recovering copper and aluminum from copper-clad aluminum processing waste. The technical solution is as follows:

[0007] This invention provides a method for recovering copper and aluminum from copper-clad aluminum processing waste, comprising: using an electrolytic cell equipped with an anion exchange membrane, wherein the anion exchange membrane divides the electrolytic cell into an anode region and a cathode region; placing the copper-clad aluminum processing waste as the anode in the anode region and the cathode in the cathode region; filling the anode region with an anolyte containing sulfuric acid and an alkali metal sulfate, wherein the alkali metal is potassium, rubidium, or cesium; filling the cathode region with a catholyte containing sulfuric acid and copper sulfate; electrolyzing by means of electricity, wherein metallic copper is deposited at the cathode and alum precipitate is generated in the anode region, and the metallic copper and alum precipitate are recovered separately.

[0008] During electrolysis, copper at the anode is preferentially oxidized and dissolved to form Cu. 2+ Subsequently, the internal aluminum was exposed and continued to oxidize into Al. 3+ In a highly acidic environment, Al 3+ With alkali metal ions (K) in solution + / Rb + / Cs + The alum combines with sulfate ions, crystallizing in situ to form an insoluble alum precipitate; simultaneously, Cu in the cathode region... 2+ Under the influence of an electric field, it is reduced, and high-purity metallic copper is deposited on the cathode surface. Since the anion exchange membrane only allows SO42-... 2- Anions pass through to maintain electroneutrality, while effectively blocking Cu. 2+ Al 3+ The cations migrate across regions, ensuring that the aluminum component is confined to the anode region to form alum, while the copper ions remain stable in the cathode region for pure deposition. After electrolysis, the metallic copper obtained from the cathode and the alum precipitate obtained from filtration in the anode region are recovered separately, thereby achieving efficient separation and high-value recovery of copper and aluminum.

[0009] Optionally, the concentration of copper ions in the catholyte is 50-60 g / L, and the concentration of sulfuric acid in the catholyte is 150-220 g / L.

[0010] Optionally, the catholyte further contains an additive; the additive is thiourea or bone glue, with a concentration of 0.1-0.2 g / L.

[0011] Optionally, the amount of alkali metal sulfate added to the anolyte satisfies the molar ratio of alkali metal ions to aluminum ions being (1.0-1.2):1, and the concentration of sulfuric acid in the anolyte is 150-220 g / L.

[0012] Optionally, the current density of the electrolysis is 150-250 A / m. 2 The electrolysis temperature is 20-40℃.

[0013] Optionally, the cathode is a stainless steel plate or a copper plate; the distance between the cathode and the anode is 3-4 cm.

[0014] Optionally, the process further includes a surface activation treatment step for copper-clad aluminum processing waste; the surface activation treatment for copper-clad aluminum processing waste includes:

[0015] The copper-clad aluminum processing waste is first alkali washed to remove oil, and then the oxide film is removed by acid leaching.

[0016] Optionally, after electrolysis is completed, the anolyte is filtered, and the filtrate is used as the catholyte for the next round of electrolysis.

[0017] After electrolysis, the anolyte in the anode region undergoes solid-liquid separation treatment, specifically including filtration or centrifugation to remove precipitated alum crystals and any possible traces of insoluble impurities, yielding a clear filtrate. This filtrate is rich in Cu produced from the dissolution of copper-clad aluminum scrap at the anode. 2+ And residual H2SO4, whose composition meets the basic requirements of the cathode electrolyte. After online pH monitoring and ion concentration analysis, the Cu in the cathode electrolyte will be adjusted according to the next round of electrolysis process. 2+ To meet the requirements for H2SO4 concentration, the composition of the filtrate was fine-tuned, adjusting its concentration to satisfy the process standards for catholyte. Subsequently, the adjusted filtrate was transferred to the cathode area for recycling as catholyte for the next round of electrolysis. This closed-loop recycling mechanism not only achieves efficient copper resource recovery and avoids copper ion loss, but also significantly reduces the consumption of acid and copper salts, while eliminating the discharge of wastewater containing heavy metals, thus greatly reducing operating costs and environmental impact.

[0018] Optionally, after electrolysis, the remaining metal residue in the anode area is recovered and returned to the copper-clad aluminum material processing procedure for recycling. Metal residue that was not completely dissolved in the anode area is recovered, and newly prepared waste material is added to the anode area. The collected remaining aluminum blocks are returned to the copper-clad aluminum material processing procedure for reuse. Based on the consumption of ions in the electrolyte, a fixed amount of alkali metal salts and sulfuric acid are added, and the electrolysis procedure is restarted.

[0019] Optionally, the anolyte and the catholyte are analyzed by online pH monitoring and acid-base titration, based on H... + Sulfuric acid is added in real time to maintain the sulfuric acid concentration within the range of 150-220 g / L.

[0020] The beneficial effects of the technical solutions provided in the embodiments of the present invention include at least the following:

[0021] This invention provides a method for recovering copper and aluminum from copper-clad aluminum processing waste. The method involves placing the copper-clad aluminum processing waste as a soluble anode in an electrolytic cell separated by anion exchange membranes. An electrolyte containing sulfuric acid and potassium, rubidium, or cesium sulfates is introduced into the anode region. This allows the copper in the waste to dissolve preferentially, while the exposed aluminum dissolves simultaneously in the strongly acidic environment and immediately combines with alkali metal ions and sulfate ions in situ to form a well-crystallized and easily separable alum precipitate. This fundamentally avoids the loss of copper and aluminum. 2+ With Al 3+ This method eliminates cross-contamination and achieves efficient and thorough separation of copper and aluminum components. The entire process can operate at low temperatures of 20-40℃, with energy consumption far lower than high-temperature pyrometallurgical methods. Furthermore, the composition of the electrolyte is adjusted after filtration to remove alum and then recycled back to the cathode area. Combined with online pH monitoring and precise reagent replenishment, this achieves closed-loop circulation of the electrolyte and near-zero wastewater discharge. Simultaneously, the electrolysis process is simple to control and highly automated, requiring no complex extraction or multi-stage precipitation steps, resulting in a streamlined process and low operating costs. Moreover, this method is applicable to various forms of copper-clad aluminum waste, including scrap, defective billets, waste wires, and end-of-service scrap, demonstrating strong raw material adaptability and promising prospects for industrial application. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with specific embodiments of the present invention. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0023] Example 1

[0024] Take 10 kg of scrap blanks generated during the processing of copper-clad aluminum materials. First, wash the scrap blanks with alkali to remove oil, then immerse them in a 5% dilute sulfuric acid solution at room temperature for 5 minutes to activate them, removing the surface oxide scale and processing oil. After removing them, rinse them with deionized water and let them air dry for later use.

[0025] Electrolyte is injected into a dedicated electrolytic cell equipped with an anion exchange membrane. The cathode solution is 55 g / L Cu. 2+ A mixed solution of 180 g / L H2SO4 and 0.1 g / L bone glue, the anolyte containing a 200 g / L H2SO4 solution, and according to K + / Al 3 + K2SO4 was added at a molar ratio of 1.1:1.

[0026] The activated waste material was filled into the titanium mesh anode basket and properly compacted to ensure good electrical contact between the fragments. A 304 stainless steel plate of the same specification was placed in the cathode area and connected to a DC regulated power supply. The electrode spacing was adjusted and fixed at 3.5 cm, and the current density was set to 250 A / m. 2 The electrolyte temperature is controlled at 25℃ by a constant temperature system.

[0027] After electrolysis began, the initial stable cell voltage was monitored at 0.18 V. Electrolysis continued until the anode waste was significantly consumed. When the cell voltage rose to 0.3 V, a stop signal was triggered and the power supply was cut off. The cathode plate was removed, and the copper foil was peeled off and collected. After washing and drying, the copper purity was found to be 99.95%, the current efficiency reached 95.1%, and the copper recovery rate reached 99.2%. The potassium alum in the anode area was collected, and combined with the mass of the remaining aluminum blocks, the overall aluminum recovery rate reached 85.4%.

[0028] Example 2

[0029] The method in this embodiment is the same as in Embodiment 1, except for the electrolyte composition, electrolysis conditions, and electrolysis results (see Table 1): the cathode liquid is 60 g / L Cu. 2+ A mixed solution of 220 g / L H2SO4 and 0.15 g / L bone glue, the anolyte containing a 200 g / L H2SO4 solution, and according to K + / Al 3+ K2SO4 was added at a molar ratio of 1.2:1.

[0030] Example 3

[0031] The method in this embodiment is the same as in Embodiment 1, except for the electrolyte composition, electrolysis conditions, and electrolysis results (see Table 1): the cathode liquid is 50 g / L Cu. 2+ A mixed solution of 200 g / L H2SO4 and 0.1 g / L thiourea, the anolyte containing a 180 g / L H2SO4 solution, and according to Rb + / Al 3+ Rb2SO4 was added at a molar ratio of 1.1:1.

[0032] Example 4

[0033] The method in this embodiment is the same as in Embodiment 1, except for the electrolyte composition, electrolysis conditions, and electrolysis results (see Table 1): the cathode liquid is 60 g / L Cu. 2+ A mixed solution of 180 g / L H2SO4 and 0.1 g / L bone glue, the anolyte containing a 180 g / L H2SO4 solution, and according to Rb + / Al 3+ Rb2SO4 was added at a molar ratio of 1.2:1.

[0034] Example 5

[0035] The method in this embodiment is the same as in Embodiment 1, except for the electrolyte composition, electrolysis conditions, and electrolysis results (see Table 1): the cathode liquid is 60 g / L Cu. 2+ A mixed solution of 200 g / L H2SO4 and 0.2 g / L thiourea, the anolyte containing a 190 g / L H2SO4 solution, and according to Cs + / Al 3+ Cs2SO4 was added at a molar ratio of 1.2:1.

[0036] Example 6

[0037] The method in this embodiment is the same as in embodiment 1, except for the electrolyte composition, electrolysis conditions, and electrolysis results (see Table 1): the cathode liquid is 55 g / L Cu. 2+ A mixed solution of 160 g / L H2SO4 and 0.1 g / L bone glue, the anolyte containing a 200 g / L H2SO4 solution, and according to Cs + / Al 3+ Cs2SO4 was added at a molar ratio of 1.1:1.

[0038] Table 1

[0039]

[0040] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for recovering copper and aluminum from copper-clad aluminum processing waste, characterized in that, include: An electrolytic cell equipped with an anion exchange membrane is used, which divides the electrolytic cell into an anode zone and a cathode zone. Copper-clad aluminum processing waste is placed in the anode zone as the anode and the cathode zone as the cathode. The anode zone is filled with an anolyte containing sulfuric acid and alkali metal sulfate, wherein the alkali metal is potassium, rubidium, or cesium. The cathode zone is filled with a catholyte containing sulfuric acid and copper sulfate. Electrolysis is performed, and metallic copper is deposited at the cathode, while alum precipitate is generated in the anode zone. The metallic copper and alum precipitate are recovered separately.

2. The method for recovering copper and aluminum from copper-clad aluminum processing waste according to claim 1, characterized in that, The concentration of copper ions in the catholyte is 50-60 g / L, and the concentration of sulfuric acid in the catholyte is 150-220 g / L.

3. The method for recovering copper and aluminum from copper-clad aluminum processing waste according to claim 2, characterized in that, The catholy solution also contains additives; the additives are thiourea or bone glue, with a concentration of 0.1-0.2 g / L.

4. The method for recovering copper and aluminum from copper-clad aluminum processing waste according to claim 1, characterized in that, The amount of alkali metal sulfate added to the anolyte satisfies the molar ratio of alkali metal ions to aluminum ions of (1.0-1.2):1, and the concentration of sulfuric acid in the anolyte is 150-220 g / L.

5. The method for recovering copper and aluminum from copper-clad aluminum processing waste according to claim 1, characterized in that, The current density of the electrolysis is 150-250 A / m. 2 The electrolysis temperature is 20-40℃.

6. The method for recovering copper and aluminum from copper-clad aluminum processing waste according to claim 1, characterized in that, The cathode is a stainless steel plate or a copper plate; the distance between the cathode and the anode is 3-4 cm.

7. The method for recovering copper and aluminum from copper-clad aluminum processing waste according to claim 1, characterized in that, It also includes a surface activation treatment step for copper-clad aluminum processing waste; the surface activation treatment for copper-clad aluminum processing waste includes: pre-washing the copper-clad aluminum processing waste with alkali to remove oil, and then removing the oxide film by acid leaching.

8. The method for recovering copper and aluminum from copper-clad aluminum processing waste according to claim 1, characterized in that, After electrolysis is complete, the anolyte is filtered, and the filtrate is used as the catholyte for the next round of electrolysis.

9. The method for recovering copper and aluminum from copper-clad aluminum processing waste according to claim 1, characterized in that, After electrolysis, the remaining metal residue in the anode area is recovered and returned to the copper-clad aluminum material processing procedure for recycling.

10. The method for recovering copper and aluminum from copper-clad aluminum processing waste according to claim 1, characterized in that, The anolyte and the catholyte are analyzed by online pH monitoring and acid-base titration, based on H... + Sulfuric acid is added in real time to maintain the sulfuric acid concentration within the range of 150-220 g / L.

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