Copper-aluminum separation and purification method in lithium battery recycling

Abstract

The application discloses a copper-aluminum separation and purification method in lithium battery recycling, and relates to the field of waste lithium ion battery recycling. The method combines multi-stage air separation, magnetic separation and precise screening technology, and is supplemented with a special solution extraction process, so that efficient separation and purification of copper and aluminum are realized, and the recycling value of metal resources in the waste lithium battery is significantly improved.

Description

Technical Field

[0001] This invention relates to the field of waste lithium-ion battery recycling, and in particular to a method for separating and purifying copper and aluminum in lithium battery recycling. Background Technology

[0002] With the widespread application of new energy vehicles, energy storage systems, and consumer electronics, the market demand for lithium-ion batteries has grown rapidly, leading to an explosive increase in the number of used lithium batteries. According to relevant research, the recycling and disposal of used lithium batteries will become a crucial issue for resource recycling and environmental protection in the coming years.

[0003] Waste lithium batteries contain a large amount of valuable metal resources, especially copper and aluminum. These two metals are mainly found in the current collectors of the batteries, used for current collection at the negative and positive electrodes, respectively. The recycling of copper and aluminum not only has significant economic value but also effectively reduces dependence on primary resources and lowers environmental pollution.

[0004] Currently, the recycling of copper and aluminum from spent lithium batteries mainly relies on a combination of physical sorting and chemical treatment. Physical sorting technology includes steps such as crushing, screening, air separation, and magnetic separation, aiming to initially separate the metallic and non-metallic components in the battery. However, due to the similar physical properties of copper and aluminum, traditional physical sorting methods struggle to achieve efficient copper-aluminum separation, resulting in low purity of the recovered metals and limiting their reuse value.

[0005] Chemical processing methods, such as hydrometallurgical techniques, utilize acid leaching and solvent extraction to further extract and purify metals. Although chemical methods have advantages in improving metal recovery rates and purity, they also suffer from complex processes, high costs, and environmental pollution, limiting their widespread adoption in large-scale industrial applications.

[0006] However, existing technologies still face many challenges, such as high energy consumption during the separation process, large equipment investment, and unstable processing efficiency. Therefore, developing an efficient, environmentally friendly, and cost-effective method for copper-aluminum separation and purification has become a key technical problem that urgently needs to be solved in the field of waste lithium battery recycling. Summary of the Invention

[0007] To address these issues, this invention provides a method for separating and purifying copper and aluminum in lithium battery recycling. The method combines multi-stage air separation, magnetic separation, and precision sieving. Furthermore, a selective complexing agent is used for solution extraction to specifically extract copper or aluminum.

[0008] The specific plan is as follows: A method for separating and purifying copper and aluminum in lithium battery recycling, characterized by comprising the following steps: a) Crushing and preliminary screening: The waste lithium-ion batteries are crushed to obtain a mixture with a particle size of 10-30 mm; b) Multi-stage air separation: The mixture is subjected to multi-stage air separation using a multi-stage adjustable wind speed air separator to separate lightweight materials from heavy metal particles; c) Magnetic separation: Heavy metal particles after air separation are subjected to magnetic separation using a high-gradient magnetic separator to remove magnetic impurities; d) Precision screening: The magnetically separated material is precision screened using a multi-layer vibrating screen to obtain a copper-aluminum mixture with uniform particle size; e) Solution extraction and separation: The copper-aluminum mixture is added to a selective complexing agent solution at a temperature of 25–60°C and a pH of 3.0–5.0 for a reaction time of 30–120 minutes. High-purity copper and aluminum are extracted separately through the complexation reaction.

[0009] According to some embodiments of the present invention, the wind speed range in the multi-stage wind separation step is 2.0 to 5.0 m / s.

[0010] According to some embodiments of the present invention, the magnetic field strength in the magnetic separation step is 8000 to 12000 Gauss.

[0011] According to some embodiments of the present invention, the mesh size of the screen in the precision sieving step is 0.5 to 2.0 mm.

[0012] According to some embodiments of the present invention, the mass number of the selective complexing agent solution is 5-10 times that of the copper-aluminum mixture.

[0013] According to some embodiments of the present invention, the selective complexing agent solution comprises: Sodium acetate: 5-15 parts by weight; Acetic acid: 10-20 parts by weight; Deionized water: 65-85 parts by weight; Additives: 0.4-1.2 parts by weight.

[0014] According to some embodiments of the present invention, the method for preparing the auxiliary agent is as follows: 10-12 parts by weight of allylphosphonic acid, 12-15 parts by weight of itaconic acid, and 14-20 parts by weight of bis[3-(triethoxysilyl)propyl]amine were mixed with toluene as an azeotropic solvent, accounting for 30% of the reaction system volume. 1.4-3 parts by weight of p-toluenesulfonic acid were added as a catalyst, and the reaction was carried out at 100-120°C for 5-8 hours. After the reaction was completed, the mixture was washed with acetone and dried to obtain the auxiliary agent.

[0015] Reaction mechanism 1) Silane amino-phosphonic acid synergistic addition: The amino group of bis[3-(triethoxysilyl)propyl]amine undergoes nucleophilic addition to the double bond of itaconic acid, while allylphosphonic acid is esterified with the carboxyl group of itaconic acid to generate a bifunctional molecule containing Si-OC bonds and POC bonds. After hydrolysis of the siloxy group, a surface adsorption layer is formed.

[0016] 2) Bidentate coordination-interfacial dissociation mechanism: The O atom of the phosphonic acid group forms a bidentate coordination with Cu²⁺ (PO⁻→Cu²⁺), and the silanol group (-SiOH) is adsorbed on the surface of LiCuO2 particles through hydrogen bonding, which destroys the crystal structure and promotes the dissolution of Cu²⁺ as [Cu(PO3)2(SiO)2]²⁻ complex ions.

[0017] Technical effect 1. Through a combination of multi-stage air separation, magnetic separation, and precision sieving, non-metallic and magnetic impurities are initially removed to obtain a copper-aluminum mixture with uniform particle size. Subsequently, a selective complexing agent solution is used for solution extraction and separation, utilizing the complexation reaction to extract high-purity copper and aluminum separately, thereby significantly improving the purity of copper and aluminum and controlling the impurity content.

[0018] 2. This method combines physical sorting with chemical extraction, avoiding the use of large amounts of acid in traditional acid leaching and reducing the generation of harmful waste liquid. Furthermore, the selective complexing agent solution can be recycled, further reducing the risk of environmental pollution.

[0019] 3. Each process step in this method is a mature industrial technology, the equipment is highly versatile, the operation is simple, and it is easy to achieve automated control, making it suitable for large-scale industrial production. Detailed Implementation

[0020] To further understand the present invention, the technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Example 1

[0021] Crushing and preliminary screening: The waste lithium-ion batteries are crushed to obtain a mixture with a particle size of 10 mm; Multi-stage air separation: The mixture is separated into lightweight materials and heavy metal particles by using a multi-stage adjustable wind speed air separator with a wind speed set to 2.0 m / s. Magnetic separation: Heavy metal particles after air separation are separated using a high-gradient magnetic separator with a magnetic field strength of 8000 Gauss to remove magnetic impurities; Precision screening: The magnetically separated material is precisely screened using a multi-layer vibrating screen with a screen aperture of 0.5 mm to obtain a copper-aluminum mixture with uniform particle size; Solution extraction and separation: The copper-aluminum mixture was added to a selective complexing agent solution at a temperature of 25°C and a pH of 3.0 for 30 minutes. The mass of the selective complexing agent solution was five times that of the copper-aluminum mixture. The selective complexing agent solution consisted of: 5g sodium acetate, 10g acetic acid, 85g deionized water, and 0.4g auxiliary agent.

[0022] The auxiliary agent is prepared as follows: 10g of allylphosphonic acid, 12g of itaconic acid, and 14g of bis[3-(triethoxysilyl)propyl]amine are mixed, with toluene as the azeotropic solvent, accounting for 30% of the reaction system volume. 1.4g of p-toluenesulfonic acid is added as a catalyst, and the reaction is carried out at 100℃ for 5 hours. After the reaction is completed, the mixture is washed with acetone and dried to obtain the auxiliary agent. Example 2

[0023] Crushing and preliminary screening: The waste lithium-ion batteries are crushed to obtain a mixture with a particle size of 18 mm; Multi-stage air separation: The mixture is separated into lightweight materials and heavy metal particles by using a multi-stage adjustable wind speed air separator with a wind speed set at 3.0 m / s. Magnetic separation: Heavy metal particles after air separation are separated using a high-gradient magnetic separator with a magnetic field strength of 9500 Gauss to remove magnetic impurities; Precision screening: The magnetically separated material is precisely screened using a multi-layer vibrating screen with a screen aperture of 1.0 mm to obtain a copper-aluminum mixture with uniform particle size. Solution extraction and separation: The copper-aluminum mixture was added to a selective complexing agent solution at a temperature of 38°C and a pH of 3.8 for 65 minutes. The mass of the selective complexing agent solution was seven times that of the copper-aluminum mixture. The selective complexing agent solution consisted of: 9g sodium acetate, 14g acetic acid, 75g deionized water, and 0.8g auxiliary agent.

[0024] The auxiliary agent was prepared by mixing 11g of allylphosphonic acid, 13g of itaconic acid, and 17g of bis[3-(triethoxysilyl)propyl]amine, using toluene as an azeotropic solvent (30% of the reaction system volume), adding 2.2g of p-toluenesulfonic acid as a catalyst, and reacting at 110℃ for 6.5 hours. After the reaction was completed, the mixture was washed with acetone and dried to obtain the auxiliary agent. Example 3

[0025] Crushing and preliminary screening: The waste lithium-ion batteries are crushed to obtain a mixture with a particle size of 24 mm; Multi-stage air separation: The mixture is separated into lightweight materials and heavy metal particles by using a multi-stage adjustable wind speed air separator with a wind speed set at 4.0 m / s. Magnetic separation: Heavy metal particles after air separation are separated by a high gradient magnetic separator with a magnetic field strength of 11,000 Gauss to remove magnetic impurities; Precision screening: The magnetically separated material is precisely screened using a multi-layer vibrating screen with a screen aperture of 1.5 mm to obtain a copper-aluminum mixture with uniform particle size. Solution extraction and separation: The copper-aluminum mixture was added to a selective complexing agent solution at a temperature of 50°C and a pH of 4.4 for 95 minutes. The mass of the selective complexing agent solution was eight times that of the copper-aluminum mixture. The selective complexing agent solution consisted of: 13g sodium acetate, 18g acetic acid, 68g deionized water, and 1.0g auxiliary agent.

[0026] The auxiliary agent was prepared as follows: 11.5 g of allylphosphonic acid, 14 g of itaconic acid, and 19 g of bis[3-(triethoxysilyl)propyl]amine were mixed, with toluene as the azeotropic solvent, accounting for 30% of the reaction system volume. 2.7 g of p-toluenesulfonic acid was added as a catalyst, and the reaction was carried out at 115 °C for 7.5 hours. After the reaction was completed, the mixture was washed with acetone and dried to obtain the auxiliary agent. Example 4

[0027] Crushing and preliminary screening: The waste lithium-ion batteries are crushed to obtain a mixture with a particle size of 30 mm; Multi-stage air separation: The mixture is separated into lightweight materials and heavy metal particles by using a multi-stage adjustable wind speed air separator with a wind speed set at 5.0 m / s. Magnetic separation: Heavy metal particles after air separation are separated using a high-gradient magnetic separator with a magnetic field strength of 12,000 Gauss to remove magnetic impurities; Precision screening: The magnetically separated material is precisely screened using a multi-layer vibrating screen with a screen aperture of 2.0 mm to obtain a copper-aluminum mixture with uniform particle size; Solution extraction and separation: The copper-aluminum mixture was added to a selective complexing agent solution at a temperature of 60℃ and a pH of 5.0 for 120 minutes. The mass of the selective complexing agent solution was 10 times that of the copper-aluminum mixture. The selective complexing agent solution consisted of: 15g sodium acetate, 20g acetic acid, 65g deionized water, and 1.2g auxiliaries.

[0028] The auxiliary agent is prepared as follows: 12g of allylphosphonic acid, 15g of itaconic acid, and 20g of bis[3-(triethoxysilyl)propyl]amine are mixed, with toluene as the azeotropic solvent, accounting for 30% of the reaction system volume. 3g of p-toluenesulfonic acid is added as a catalyst, and the reaction is carried out at 120℃ for 8 hours. After the reaction is completed, the mixture is washed with acetone and dried to obtain the auxiliary agent.

[0029] Comparative Example 1 Crushing and preliminary screening: The waste lithium-ion batteries are crushed to obtain a mixture with a particle size of 10 mm; Multi-stage air separation: The mixture is separated into lightweight materials and heavy metal particles by using a multi-stage adjustable wind speed air separator with a wind speed set to 2.0 m / s. Magnetic separation: Heavy metal particles after air separation are separated using a high-gradient magnetic separator with a magnetic field strength of 8000 Gauss to remove magnetic impurities; Precision screening: The magnetically separated material is precisely screened using a multi-layer vibrating screen with a screen aperture of 0.5 mm to obtain a copper-aluminum mixture with uniform particle size; Solution extraction separation: The copper-aluminum mixture was added to a selective complexing agent solution at a temperature of 25°C and a pH of 3.0 for 30 minutes. The mass of the selective complexing agent solution was five times that of the copper-aluminum mixture. The selective complexing agent solution consisted of 5g sodium acetate, 10g acetic acid, and 85g deionized water.

[0030] Comparative Example 2 Crushing and preliminary screening: The waste lithium-ion batteries are crushed to obtain a mixture with a particle size of 10 mm; Multi-stage air separation: The mixture is separated into lightweight materials and heavy metal particles by using a multi-stage adjustable wind speed air separator with a wind speed set to 2.0 m / s. Magnetic separation: Heavy metal particles after air separation are separated using a high-gradient magnetic separator with a magnetic field strength of 8000 Gauss to remove magnetic impurities; Precision screening: The magnetically separated material is precisely screened using a multi-layer vibrating screen with a screen aperture of 0.5 mm to obtain a copper-aluminum mixture with uniform particle size; Solution extraction and separation: The copper-aluminum mixture was added to a selective complexing agent solution at a temperature of 25°C and a pH of 3.0 for 30 minutes. The mass of the selective complexing agent solution was five times that of the copper-aluminum mixture. The selective complexing agent solution consisted of: 5g sodium acetate, 10g acetic acid, 85g deionized water, and 0.4g auxiliary agent.

[0031] The auxiliary agent is prepared as follows: 12g of itaconic acid and 14g of bis[3-(triethoxysilyl)propyl]amine are mixed, with toluene as the azeotropic solvent, accounting for 30% of the reaction system volume. 1.4g of p-toluenesulfonic acid is added as a catalyst, and the reaction is carried out at 100℃ for 5 hours. After the reaction is completed, the mixture is washed with acetone and dried to obtain the auxiliary agent.

[0032] Comparative Example 3 Crushing and preliminary screening: The waste lithium-ion batteries are crushed to obtain a mixture with a particle size of 10 mm; Multi-stage air separation: The mixture is separated into lightweight materials and heavy metal particles by using a multi-stage adjustable wind speed air separator with a wind speed set to 2.0 m / s. Magnetic separation: Heavy metal particles after air separation are separated using a high-gradient magnetic separator with a magnetic field strength of 8000 Gauss to remove magnetic impurities; Precision screening: The magnetically separated material is precisely screened using a multi-layer vibrating screen with a screen aperture of 0.5 mm to obtain a copper-aluminum mixture with uniform particle size; Solution extraction and separation: The copper-aluminum mixture was added to a selective complexing agent solution at a temperature of 25°C and a pH of 3.0 for 30 minutes. The mass of the selective complexing agent solution was five times that of the copper-aluminum mixture. The selective complexing agent solution consisted of: 5g sodium acetate, 10g acetic acid, 85g deionized water, and 0.4g auxiliary agent.

[0033] The auxiliary agent is prepared by mixing 10g of allylphosphonic acid and 12g of itaconic acid, using toluene as an azeotropic solvent (30% of the reaction system volume), adding 1.4g of p-toluenesulfonic acid as a catalyst, and reacting at 100℃ for 5 hours. After the reaction is complete, the mixture is washed with acetone and dried to obtain the auxiliary agent.

[0034] The testing method involved in this invention is as follows: 1) Purity test (ICPOES quantitative analysis) Sample digestion: Take about 0.1g of copper or aluminum concentrate, add 3mL of concentrated hydrochloric acid + a small amount of nitric acid (aqua regia), heat at 120℃ for 30min, cool and bring the volume to 50mL, then dilute 10 times with deionized water. Instruments and parameters: Agilent 5800 VDV ICP-OES, RF power 1.4kW, atomizer flow rate 0.65L / min, IntelliQuant intelligent screening, three repeated measurements.

[0035] 2) Recovery rate test Calculation method: Recovery rate = Mass of recovered metal (kg) / Mass of copper and aluminum input (kg) × 100% recovery rate Accurately weigh the mass of the crushed copper-aluminum mixture and the mass of the recovered copper / aluminum concentrate, calculate the recovery rate, and retain two decimal places.

[0036] Test results: Cu purity % Cu recovery rate % Al purity % Al recovery rate % Example 1 99.50 98.10 99.61 96.44 Example 2 99.58 98.22 99.67 96.56 Example 3 99.64 98.28 99.72 96.63 Example 4 99.67 98.34 99.75 96.70 Comparative Example 1 98.85 96.80 99.02 94.85 Comparative Example 2 99.08 97.25 99.18 95.15 Comparative Example 3 99.17 97.33 99.24 95.22 The experimental data above clearly demonstrate the advantages of this invention in terms of purity and recovery rate: the combination of multi-stage physical sorting and chemical extraction improves purity; precise sorting reduces losses and selective precipitation maximizes metal recovery.

[0037] The applicant declares that the detailed process equipment and process flow of this invention are illustrated through the above embodiments, but this invention is not limited to the above detailed process equipment and process flow, that is, it does not mean that this invention must rely on the above detailed process equipment and process flow to be implemented. Those skilled in the art should understand that any improvements to this invention, equivalent substitutions of raw materials for the products of this invention, additions of auxiliary components, and selection of specific methods, all fall within the protection scope and disclosure scope of this invention.

Claims

1. A method for separating and purifying copper and aluminum in lithium battery recycling, characterized in that, Includes the following steps: a) Crushing and preliminary screening: The waste lithium-ion batteries are crushed to obtain a mixture with a particle size of 10-30 mm; b) Multi-stage air separation: The mixture is subjected to multi-stage air separation using a multi-stage adjustable wind speed air separator to separate lightweight materials from heavy metal particles; c) Magnetic separation: Heavy metal particles after air separation are subjected to magnetic separation using a high-gradient magnetic separator to remove magnetic impurities; d) Precision screening: The magnetically separated material is precision screened using a multi-layer vibrating screen to obtain a copper-aluminum mixture with uniform particle size; e) Solution extraction and separation: The copper-aluminum mixture is added to a selective complexing agent solution at a temperature of 25–60°C and a pH of 3.0–5.0 for a reaction time of 30–120 minutes. High-purity copper and aluminum are extracted separately through the complexation reaction.

2. The method for copper-aluminum separation and purification in lithium battery recycling according to claim 1, characterized in that: The wind speed range in the multi-stage wind separation process is 2.0 to 5.0 m / s.

3. The method for copper-aluminum separation and purification in lithium battery recycling according to claim 1, characterized in that: The magnetic field strength in the magnetic separation step is 8000 to 12000 Gauss.

4. The method for copper-aluminum separation and purification in lithium battery recycling according to claim 1, characterized in that: The screen aperture in the precision sieving step is 0.5 to 2.0 mm.

5. The method for copper-aluminum separation and purification in lithium battery recycling according to claim 1, characterized in that: The mass of the selective complexing agent solution is 5-10 times that of the copper-aluminum mixture.

6. The method for copper-aluminum separation and purification in lithium battery recycling according to claim 1, characterized in that: The selective complexing agent solution comprises: Sodium acetate: 5-15 parts by weight; Acetic acid: 10-20 parts by weight; Deionized water: 65-85 parts by weight; Additives: 0.4-1.2 parts by weight.

7. The method for copper-aluminum separation and purification in lithium battery recycling according to claim 6, characterized in that: The preparation method of the auxiliary agent: 10-12 parts by mass of allylphosphonic acid, 12-15 parts by mass of itaconic acid and 14-20 parts by mass of bis[3-(triethoxysilyl)propyl]amine were mixed, and toluene was used as an azeotropic solvent, accounting for 30% of the reaction system volume. 1.4-3 parts by mass of p-toluenesulfonic acid were added as a catalyst, and the reaction was carried out at 100-120℃ for 5-8 hours. After the reaction was completed, the mixture was washed with acetone and dried to obtain the auxiliary agent.