Separation, purification and regeneration method of waste pole piece negative electrode powder

Abstract

The invention discloses a method for separating, purifying and regenerating waste battery negative electrode powder, which belongs to the field of battery recycling and regenerating, and mainly comprises the following process steps of: ball-milling and screening waste battery negative electrode pieces into certain granularity, soaking the waste battery negative electrode pieces in alkali liquor and an impurity removal agent, and stirring for reaction and separation to obtain a negative electrode powder wet material and a copper ion solution; carrying out drying demagnetization and infrared irradiation treatment on the wet negative electrode powder to obtain regenerated negative electrode powder; and the copper ion solution is subjected to extraction, back extraction and reduction to obtain crude copper, and the crude copper is subjected to vacuum distillation to obtain an electronic-grade copper product. Wherein the impurity removal agent comprises an oxidizing agent, the oxidizing agent oxidizes elemental copper and forms soluble substances under the action of alkali liquor, and the excellent separation effect is achieved. The negative electrode powder treatment comprises infrared irradiation treatment, decomposition of an adhesive can be achieved through the dual effects of heat irradiation and heat conduction, the volume heating effect is formed through scattering, surface crusting is effectively avoided, the adhesive can be efficiently removed, and the quality and the recycling efficiency of the regenerated negative electrode powder are guaranteed.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of battery recycling, in particular to a method for separating, purifying and recycling waste negative plate negative powder. BACKGROUND

[0002] Lithium ion batteries have the advantages of low energy consumption, high specific capacity, high working voltage and long cycle life. With the wide application of electronic products, the application of lithium ion batteries is also more and more extensive. However, the disposal and resource recycling of lithium ion battery waste have become a new important problem. The negative plate in waste battery is usually composed of graphite and negative current collector copper foil and other materials. After being crushed by mechanical equipment, negative powder and copper products are obtained. The negative powder obtained by direct crushing contains copper impurities, which not only affects the reuse of negative powder, but also causes waste of copper resources as a valuable metal.

[0003] The common methods for recovering copper from the negative plate of waste lithium ion batteries at present mainly include: (1) chemical treatment method: the negative plate is soaked in an acidic solution, and the copper and graphite negative electrode are separated from each other through chemical reaction; (2) physical separation method: the crushed materials are physically separated to obtain copper foil and graphite negative electrode through screening and classification operation; (3) heat treatment method: the adhesive contained in the negative plate is removed under high temperature conditions by using the heat treatment method to separate the copper foil and graphite in the negative plate, and then the copper is recovered after screening; (4) electrolytic treatment method: the negative plate is placed in an electrolyte for electrolysis to realize the separation of copper foil and graphite through the action of electric current.

[0004] However, the above methods have certain defects. For example, in the chemical treatment method, the dissolution rate of copper in dilute acid solution is very limited, and in high concentration acid solution, high temperature heating is required, which may volatilize toxic gases and pollute the environment. In addition, the reaction temperature, acidity, air inflow, catalyst dosage and other factors in the reaction process will affect the dissolution rate of copper, resulting in low copper recovery rate and low purity of graphite negative electrode. The physical separation method needs to invest appropriate equipment, which has high cost and needs a long time to achieve ideal separation effect, increasing the production cost and recovery period. The heat treatment method can achieve effective separation of copper foil and graphite to a certain extent through high temperature calcination, but it has the disadvantages of high energy consumption, environmental pollution, high loss rate of graphite, and difficult process control. The electrolytic process of electrolytic treatment method needs electrolytic tank, current source and other appropriate equipment and energy supply, which has high equipment cost and causes resource waste. Moreover, the recovery rate of graphite powder and metal copper recovered by conventional methods is limited, and the purity is not high.

[0005] Chinese patent application CN113528824A discloses a method for recycling elemental copper from waste lithium-ion battery powder. The method involves first maturing the battery powder slurry with concentrated sulfuric acid, then performing solid-liquid separation on the leachate after adding water and reducing agent, adjusting the pH value, and then sorting the separated graphite slurry multiple times to finally obtain metallic copper. This method uses a bolt sorting machine, and the concentrated sulfuric acid readily volatilizes the toxic gas sulfur dioxide during the reaction process. Furthermore, multiple sorting operations are required, making the process cumbersome and unsuitable for large-scale batch processing.

[0006] Chinese patent application CN114361639A discloses a method for the efficient separation and recycling of graphite and copper foil from the negative electrode of waste lithium-ion batteries. It provides a relatively simple approach, mainly involving cleaning the negative electrode powder with a surfactant, followed by ultrasonic heating treatment, and then cleaning and separating the copper. However, the surfactant used in this method can cause environmental pollution, and the cleaning waste liquid generated during the cleaning process contains organic substances such as surfactants, which require special treatment to prevent pollution of the environment and water resources, thereby increasing waste treatment costs. Moreover, after cleaning, the recycled materials may still have residual surfactants, which can affect the purity of the recovered copper and graphite and the stability of the recycled products, thus reducing the quality and performance of the products.

[0007] This shows that current methods for recycling and reusing waste lithium-ion anode sheets are complex, costly, and pollute the environment during production. Therefore, it is of great significance to develop an efficient recycling method that is environmentally friendly, resource-efficient, and harmless. Summary of the Invention

[0008] This invention provides a method for separating, purifying, and regenerating waste electrode powder, which can solve the problems of environmental pollution, resource waste, and low recovery rate and purity of recycled products in the process of recycling waste lithium-ion battery negative electrode sheets in the existing technology.

[0009] A method for separating, purifying, and regenerating waste electrode negative electrode powder includes the following process steps: S1. Waste battery negative electrode sheets are crushed, ball-milled and sieved to obtain waste electrode sheet negative electrode powder; S2. Mix the waste electrode sheet negative electrode powder with deionized water to prepare a negative electrode powder slurry; S3. Add alkaline solution to the negative electrode powder slurry and stir to react. Then add impurity remover and continue stirring to react under an inert gas atmosphere to obtain a negative electrode powder alkaline solution. S4. The negative electrode powder alkaline solution is filtered and centrifuged to obtain wet negative electrode powder and copper ion solution; S5. The wet negative electrode powder is dried and demagnetized to obtain dry negative electrode powder; then it is subjected to infrared irradiation treatment, and finally regenerated negative electrode powder is obtained by sieving and grinding. S6. The copper ion solution is extracted to obtain a copper-loaded organic phase and an aqueous phase; the aqueous phase is evaporated and condensed to recover the alkaline solution; the copper-loaded organic phase is back-extracted, a reducing agent is added, the solvent is evaporated, and crude copper is recovered. S7. Crude copper is vacuum distilled to obtain electronic-grade copper products.

[0010] Preferably, the particle size of the waste electrode negative electrode powder is 100-500 μm.

[0011] Preferably, the solid-liquid ratio of waste electrode negative electrode powder to deionized water is 1g:(5-10)mL.

[0012] Preferably, the extractant used in step S6 includes one or more combinations of tributyl phosphate, methyl isopropyl ketone, dimethylformamide, 2-naphthol and trimethylamine; the back-extraction agent used includes any one of sulfuric acid, hydrochloric acid, formic acid and acetic acid; the reducing agent includes iron and / or sulfur dioxide; and the molar ratio of reducing agent to copper ions is (0.7-1.3):1.

[0013] More preferably, in step S1, zirconium ball milling is used, with a milling temperature of 20-30°C, a milling speed of 300-1100 rpm, and a milling time of 1-12 hours.

[0014] More preferably, in step S5, the drying temperature of the drying process is 50–200°C and the drying time is 1–30 h; the magnetic field strength of the demagnetization process is 0.1–2 T, the feeding speed is 50–300 g / s, and the magnetic separation time is 0.5–3 h.

[0015] By adopting the above technical solution, the recycled waste battery negative electrode sheets are first crushed and ball-milled to obtain waste electrode sheet negative electrode powder with more uniform particles and larger particle size, which is more suitable for large-scale production and application, and is also beneficial to the subsequent separation and recycling process.

[0016] Then, through the combined action of alkali and impurity removal agents, copper ions in the negative electrode powder can be leached into the solution, thereby efficiently separating graphite and metallic copper and significantly reducing metal residue in the graphite negative electrode powder. Subsequently, the obtained wet negative electrode powder and copper ion solution are processed separately. The wet negative electrode powder is dried and treated with infrared irradiation to selectively remove the binder present in the negative electrode powder and separate graphite particles to obtain regenerated negative electrode powder; the copper ion solution is extracted and back-extracted, and then the copper product is recovered through a reaction with a reducing agent.

[0017] The process steps provided by this invention yield high recovery rates of graphite recycled negative electrode powder and copper products. Furthermore, it eliminates the need for harmful chemicals, prevents the generation of toxic gases, reduces environmental pollution, effectively separates impurities from the negative electrode powder, reduces the residue of binders and other impurities, and improves the purity of the recycled products.

[0018] Preferably, the alkaline solution includes any one of sodium hydroxide aqueous solution, potassium hydroxide aqueous solution, ammonia water, and sodium carbonate aqueous solution; the mass ratio of alkaline solution to negative electrode powder slurry is (0.2~0.6):1.

[0019] Preferably, the amount of impurity remover added is 0.1 to 0.5 wt% of the mass of the waste electrode negative electrode powder; The impurity removal agent includes an oxidizing agent, which includes one or more combinations of sodium peroxide, potassium oxide, hydrogen peroxide, and potassium chlorate.

[0020] Preferably, the reaction temperature of the stirring reaction in step S3 is 30–85°C, and the reaction time is 2–48 h.

[0021] By adopting the above technical solution, the main purpose of the stirring reaction in step S3 is to separate copper ions from the negative electrode powder, transferring the copper ions from the negative electrode powder to the solution. This process mainly relies on the dual action of the alkaline solution and the impurity removal agent. Specifically: First, this invention creates an alkaline environment for the separation of copper ions. Then, a purification agent is added. The oxidant included in the purification agent can oxidize the elemental copper in the negative electrode powder, resulting in C... Oxidized to Cu 2+ Then, through the action of alkaline solution, the oxidized copper ions gradually form soluble substances, breaking the chemical equilibrium and allowing the dissolution reaction to continue. Other substances in the negative electrode powder, such as graphite, are relatively stable in an alkaline environment and will not be oxidized or easily dissolved by alkaline solution. Under these reaction conditions, the negative electrode active substances, such as graphite, are almost completely retained in the solid residue, achieving excellent separation effect. Therefore, the method provided by this invention has high selectivity for the separation of copper ions, avoids the introduction of impurity ions in the copper ion solution, and thus improves the purity and recovery rate of the recovered product.

[0022] Furthermore, compared to traditional acid leaching, the copper ion dissolution of this invention is carried out in an alkaline environment. On the one hand, alkaline solutions are less corrosive to reaction tanks, pipelines and other equipment than acidic solutions. On the other hand, compared to acidic solutions, alkaline solutions do not produce toxic gases during the reaction process. Moreover, the alkaline solution can be recovered through simple distillation and condensation in subsequent processing and reused in the reaction process, thus saving production resources.

[0023] Furthermore, in an alkaline environment, the oxidant more readily generates highly reactive free radicals. These free radicals can rapidly oxidize and degrade elemental copper into soluble products. The reaction, carried out under an inert gas atmosphere, further prevents the oxidant from decomposing or deactivating in air, thus improving reaction stability. In contrast, acidic leaching results in slow or even incomplete reactions of the oxidant. Acidic conditions inhibit the generation of reactive free radicals and easily lead to side reactions. Therefore, alkaline solutions and oxidants are well-matched to improve the separation of copper ions from the negative electrode powder.

[0024] Preferably, the impurity remover also includes copper tartrate; the mass ratio of copper tartrate to oxidant is (0.2-0.4):1.

[0025] By adopting the above technical solution, copper tartrate can also be added along with the oxidant. Copper tartrate can introduce new copper ions and work synergistically with the oxidant to oxidize C. and Cu 1+ Oxidized to Cu 2+ It accelerates the leaching of elemental copper and enhances the oxidation process. Pre-stored copper ions can accelerate the initial slow oxidation process, directly start the catalytic chain, thereby shortening the reaction cycle, improving the leaching efficiency of copper ions, and enhancing the stability of the system while suppressing the generation of disproportionation side reactions.

[0026] On the other hand, under alkaline conditions, tartrate ions preferentially complex copper ions to form stable water-soluble complexes, which can prevent the hydrolysis of copper ions, maintain the soluble state of copper ions, and further enhance the solubility of copper ions in the solution, thereby increasing the leaching amount of copper ions and improving the extraction efficiency of copper ions.

[0027] Therefore, by adding copper tartrate, the upper limit of copper ion leaching can be increased, the loss of copper ions can be reduced, and the leaching efficiency and leaching amount of copper ions can be enhanced. This is not only beneficial to improving the recovery efficiency and purity of copper products, but also beneficial to the separation of copper impurities in graphite anode powder, thereby improving the recovery efficiency and purity of regenerated anode powder.

[0028] Preferably, the infrared irradiation treatment in step S5 specifically includes: The negative electrode powder is placed in an infrared baking device and heated to 120-180°C under vacuum conditions for infrared irradiation baking. Stirring is turned on for 3-5 minutes every 10-20 minutes, and the baking time is 2-4 hours. The infrared wavelength of the infrared irradiation is 4-10 μm.

[0029] By employing the above technical solution, on the one hand, by limiting the infrared wavelength, within this wavelength range, the binder contained in the negative electrode powder undergoes molecular chain breakage due to molecular resonance, causing graphite particles to separate from each other, increasing the exposed area of ​​the binder molecules. Then, under the dual effects of thermal irradiation and thermal conduction, the binder undergoes thermal decomposition and escapes, thereby achieving effective separation of the binder and improving the purity of the regenerated negative electrode powder. Furthermore, the reaction is carried out in a vacuum environment, which can significantly reduce the thermal decomposition temperature of the binder, thus reducing the risk of graphite oxidation or deformation at high temperatures. Simultaneously, stirring is performed at regular intervals to ensure effective reaction of the powder, allowing sufficient time for heat to penetrate the powder pile and enabling the binder to fully decompose and escape.

[0030] On the other hand, this wavelength range has low energy and shallow penetration depth but strong scattering ability. It will not be completely absorbed by the surface powder, but will diffuse inside the powder pile through multiple scatterings, forming a "volume heating" effect. This achieves uniform heating from the inside out, effectively avoiding surface crusting. Surface crusting not only affects the quality of the regenerated negative electrode powder, but also affects the removal of the binder, thereby reducing the recovery rate and purity of the negative electrode powder.

[0031] Preferably, step S7 specifically includes the following steps: S701. Place the crude copper in a vacuum furnace with a vacuum degree of 2 to 15 Pa; S702. Perform the first stage of heating at a rate of 20-40℃ / min, raising the temperature to 950-1100℃; then perform the second stage of heating at a rate of 40-60℃ / min, raising the temperature to 1200-1600℃, and then hold the temperature for 1-6 hours. S703. Cool to 100-200℃ for condensation and recovery to obtain electronic-grade copper products.

[0032] By adopting the above technical solution, after recovering crude copper, this invention uses vacuum distillation to further obtain electronic-grade copper products. Specifically, under high vacuum conditions, the volatilization of low-boiling-point impurities in the crude copper can be accelerated, and oxidation under high-temperature conditions can be effectively suppressed. Then, a staged heating method is used to raise the temperature to the target temperature. This staged heating method not only effectively helps to remove impurities contained in the crude copper, but also better controls the evaporation rate and separation effect of copper, achieving efficient separation of impurities and copper, further improving the purity of the copper product, and obtaining electronic-grade copper products.

[0033] The beneficial effects of this invention are: 1. This invention provides a method for separating, purifying, and regenerating waste battery negative electrode powder. Waste battery negative electrode sheets are crushed and ball-milled to obtain waste negative electrode powder, which is then treated with an alkaline solution and a purification agent. This method can efficiently separate the negative electrode powder and copper ions. The purification agent includes an oxidant, which can oxidize elemental copper and form a soluble substance under the action of the alkaline solution, thereby achieving excellent separation results. The separation of copper ions is highly selective, and compared with traditional acid dissolution, it has low corrosiveness and is environmentally friendly. The alkaline solution can also be recycled and reused.

[0034] 2. The impurity removal agent of the present invention also includes copper tartrate, which can enhance the oxidation process, catalyze the conversion process of copper ions, shorten the reaction cycle, and improve the leaching efficiency of copper ions. Moreover, tartrate ions can react with copper ions to form a stable water-soluble complex, maintain the leaching amount of copper ions, thereby improving the recovery efficiency and purity of copper products.

[0035] 3. The recycling process of waste electrode negative electrode powder in this aspect also includes infrared irradiation. The effective separation and decomposition of binder can be achieved through the dual effects of thermal irradiation and thermal conduction, thereby improving the purity of the regenerated negative electrode powder. Furthermore, infrared irradiation treatment can form a "volume heating" effect through scattering, thereby achieving uniform heating from the inside out, effectively avoiding surface crusting. While efficiently removing the binder, it can also ensure the quality and recycling efficiency of the regenerated negative electrode powder. Attached Figure Description

[0036] Figure 1 This is a process flow diagram of the separation, purification and regeneration method of waste electrode negative electrode powder in Embodiment 1 of the present invention. Detailed Implementation

[0037] The specific embodiments of the present invention will be described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0038] Example

[0039] Example 1: A method for separating, purifying, and regenerating waste electrode negative electrode powder, comprising the following process steps: S1. Take 75kg of waste battery negative electrode sheets and crush them. Then use a zirconium ball mill for 45min, 25℃, and 600rpm. After sieving through a 200-mesh sieve, waste electrode sheet negative electrode powder is obtained. S2. Mix the waste electrode negative electrode powder obtained above with deionized water, wherein the solid-liquid ratio of the waste electrode negative electrode powder to deionized water is 1g:8mL, and prepare a negative electrode powder slurry. S3. Add a 1 mol / L sodium hydroxide aqueous solution to the obtained negative electrode powder slurry and stir to react. Specifically, nitrogen gas is introduced into the reaction equipment as a protective gas, and the 1 mol / L sodium hydroxide aqueous solution is added to the negative electrode powder slurry at a flow rate of 50 mL / min. The temperature is adjusted to 50℃, and the reaction is stirred at a speed of 750 rpm. The mass ratio of the negative electrode powder slurry to the 1 mol / L sodium hydroxide aqueous solution is 1:0.6. Then, add sodium peroxide as a purification agent. The amount of sodium peroxide added is 0.2% of the mass of the waste electrode negative electrode powder. Prepare a 0.5 mol / L sodium peroxide aqueous solution and add it at a flow rate of 20 mL / min while stirring to react. After all the addition is completed, let it stand for 2 hours to obtain the negative electrode powder alkaline solution. S4. The negative electrode powder alkaline solution is filtered and centrifuged to obtain wet negative electrode powder and copper ion solution; S5. The wet negative electrode powder is dried at 130℃ for 4 hours, and then demagnetized with a magnetic field strength of 0.75T, a material feeding rate of 75g / s, and a magnetic separation time of 0.5 hours to obtain dry negative electrode powder. Then, the dry negative electrode powder was placed in an infrared baking device, and under vacuum conditions, the temperature was raised to 145°C for infrared irradiation baking. The infrared wavelength of the infrared irradiation was 8μm, and stirring was turned on for 3 minutes every 15 minutes. The baking time was 3 hours. The regenerated negative electrode powder was obtained by sieving and grinding. S6. Add 45 L of extractant tributyl phosphate to the obtained copper ion solution, start stirring at 750 rpm, react for 45 min, and after complete extraction, let stand for 30 min to obtain copper-loaded organic phase and aqueous phase; the obtained aqueous phase is evaporated and condensed to recover the alkaline solution. Back-extraction was performed by adding 0.5 mol / L sulfuric acid solution as a back-extraction agent to a copper-supported organic phase, followed by reduction by introducing sulfur dioxide, wherein the molar ratio of sulfur dioxide to copper ions was 0.7:1. After evaporating the solvent, crude copper was recovered. S7. Crude copper is vacuum distilled to obtain electronic-grade copper products, specifically: S701. Place the crude copper in a vacuum furnace with a vacuum degree of 8 Pa; S702. The first stage of heating is carried out at a rate of 30℃ / min, and the temperature is increased to 1000℃; then the second stage of heating is carried out at a rate of 50℃ / min, and the temperature is increased to 1400℃, and then held for 3 hours. S703. Cool to 120°C for condensation and recovery to obtain electronic-grade copper products.

[0040] Example 2, a method for separating, purifying and regenerating waste electrode negative electrode powder, includes the following process steps: S1. Take 75kg of waste battery negative electrode sheets and crush them. Then use a zirconium ball mill for 30min, milling temperature of 25℃, milling speed of 600rpm. After sieving through a 200-mesh sieve, waste electrode sheet negative electrode powder is obtained. S2. Mix the waste electrode negative electrode powder obtained above with deionized water, wherein the solid-liquid ratio of the waste electrode negative electrode powder to deionized water is 1g:5mL, and prepare a negative electrode powder slurry. S3. Add ammonia water with a total concentration of 3 mol / L to the above-obtained negative electrode powder slurry and stir to react. Specifically, nitrogen gas is introduced into the reaction equipment as a protective gas, and ammonia water with a total concentration of 3 mol / L is added to the negative electrode powder slurry at a flow rate of 50 mL / min. The temperature is adjusted to 60℃, and the reaction is stirred at a speed of 800 rpm. The mass ratio of the negative electrode powder slurry to the ammonia water with a total concentration of 3 mol / L is 1:0.3. Then, sodium peroxide is added. The amount of sodium peroxide added is 0.25% of the mass of the waste electrode negative electrode powder. The sodium peroxide is prepared into a sodium peroxide aqueous solution with a concentration of 0.5 mol / L and then added at a flow rate of 20 mL / min while stirring to react. After all the sodium peroxide has been added, it is allowed to stand for 2 hours to obtain the negative electrode powder alkaline solution. S4. The negative electrode powder alkaline solution is filtered and centrifuged to obtain wet negative electrode powder and copper ion solution; S5. The wet negative electrode powder is dried at 120℃ for 6 hours, and then demagnetized with a magnetic field strength of 0.8T, a material feeding rate of 50g / s, and a magnetic separation time of 0.5 hours to obtain dry negative electrode powder. Then, the dry negative electrode powder was placed in an infrared baking device, and under vacuum conditions, the temperature was raised to 160°C for infrared irradiation baking. The infrared wavelength of the infrared irradiation was 6μm, and stirring was turned on for 3 minutes every 15 minutes. The baking time was 2.5 hours. Finally, the regenerated negative electrode powder was obtained by sieving and grinding. S6. Add 45 L of extractant methyl isopropyl ketone to the obtained copper ion solution, start stirring at 800 rpm, react for 45 min, and after complete extraction, let stand for 30 min to obtain copper-loaded organic phase and aqueous phase; the obtained aqueous phase is evaporated and condensed to recover the alkaline solution. Back-extraction was performed by adding 0.6 mol / L sulfuric acid solution as a back-extraction agent to a copper-supported organic phase, followed by reduction by introducing sulfur dioxide, wherein the molar ratio of sulfur dioxide to copper ions was 0.7:1. After evaporating the solvent, crude copper was recovered. S7. Crude copper is vacuum distilled to obtain electronic-grade copper products, specifically: S701. Place the crude copper in a vacuum furnace with a vacuum degree of 8 Pa; S702. The first stage of heating is carried out at a rate of 30℃ / min, and the temperature is increased to 1000℃; then the second stage of heating is carried out at a rate of 50℃ / min, and the temperature is increased to 1400℃, and then held for 3 hours. S703. Cool to 120°C for condensation and recovery to obtain electronic-grade copper products.

[0041] Example 3, a method for separating, purifying and regenerating waste electrode negative electrode powder, differs from Example 1 only in that the impurity removal agent also includes copper tartrate, and the mass ratio of copper tartrate to sodium peroxide is 0.3:1; the amount of impurity removal agent added is 0.2% of the mass of waste electrode negative electrode powder.

[0042] Comparative Example

[0043] Comparative Example 1: A method for separating, purifying, and regenerating waste electrode negative electrode powder, comprising the following process steps: S1. Take 75kg of waste battery negative electrode sheets and crush them. Then use a zirconium ball mill for 45min, 25℃, and 600rpm. After sieving through a 200-mesh sieve, waste electrode sheet negative electrode powder is obtained. S2. Mix the waste electrode negative electrode powder obtained above with deionized water, wherein the solid-liquid ratio of the waste electrode negative electrode powder to deionized water is 1g:8mL, and prepare a negative electrode powder slurry. S3. Add a 1 mol / L sodium hydroxide aqueous solution to the obtained negative electrode powder slurry and stir to react. Specifically, nitrogen gas is introduced into the reaction equipment as a protective gas, and the 1 mol / L sodium hydroxide aqueous solution is added to the negative electrode powder slurry at a flow rate of 50 mL / min. The temperature is adjusted to 50℃, and the reaction is stirred at a speed of 750 rpm. The mass ratio of the negative electrode powder slurry to the 1 mol / L sodium hydroxide aqueous solution is 1:0.6. Then, add sodium peroxide as a purification agent. The amount of sodium peroxide added is 0.2% of the mass of the waste electrode negative electrode powder. Prepare a 0.5 mol / L sodium peroxide aqueous solution and add it at a flow rate of 20 mL / min while stirring to react. After all the addition is completed, let it stand for 2 hours to obtain the negative electrode powder alkaline solution. S4. The negative electrode powder alkaline solution is filtered and centrifuged to obtain wet negative electrode powder and copper ion solution; S5. The wet negative electrode powder is dried at 130℃ for 4 hours, and then demagnetized with a magnetic field strength of 0.75T, a material feeding rate of 75g / s, and a magnetic separation time of 0.5 hours to obtain dry negative electrode powder. Then, the dry negative electrode powder is heated to 220℃ and baked for 3 hours; the regenerated negative electrode powder is obtained by sieving and grinding. S6. Add 45 L of extractant tributyl phosphate to the obtained copper ion solution, start stirring at 750 rpm, react for 45 min, and after complete extraction, let stand for 30 min to obtain copper-loaded organic phase and aqueous phase; the obtained aqueous phase is evaporated and condensed to recover the alkaline solution. Back-extraction was performed by adding 0.5 mol / L sulfuric acid solution as a back-extraction agent to a copper-supported organic phase, followed by reduction by introducing sulfur dioxide, wherein the molar ratio of sulfur dioxide to copper ions was 0.7:1. After evaporating the solvent, crude copper was recovered. S7. Crude copper is vacuum distilled to obtain electronic-grade copper products, specifically: S701. Place the crude copper in a vacuum furnace with a vacuum degree of 8 Pa; S702. The first stage of heating is carried out at a rate of 30℃ / min, and the temperature is increased to 1000℃; then the second stage of heating is carried out at a rate of 50℃ / min, and the temperature is increased to 1400℃, and then held for 3 hours. S703. Cool to 120°C for condensation and recovery to obtain electronic-grade copper products.

[0044] Comparative Example 2, a method for separating, purifying, and regenerating waste electrode negative electrode powder, includes the following process steps: S1. Take 75kg of waste battery negative electrode sheets and crush them. Then use a zirconium ball mill for 45min, 25℃, and 600rpm. After sieving through a 200-mesh sieve, waste electrode sheet negative electrode powder is obtained. S2. Mix the waste electrode negative electrode powder obtained above with deionized water, wherein the solid-liquid ratio of the waste electrode negative electrode powder to deionized water is 1g:8mL, and prepare a negative electrode powder slurry. S3. Add a sulfuric acid aqueous solution with a total concentration of 1 mol / L to the negative electrode powder slurry obtained above and stir to react. Specifically, nitrogen gas is introduced into the reaction equipment as a protective gas, and the sulfuric acid aqueous solution with a total concentration of 1 mol / L is added to the negative electrode powder slurry at a flow rate of 30 mL / min. The temperature is adjusted to 50℃, and the reaction is stirred at a speed of 750 rpm. The mass ratio of the negative electrode powder slurry to the sulfuric acid aqueous solution with a total concentration of 1 mol / L is 1:0.6. Then, sodium peroxide, a purification agent, is added. The amount of sodium peroxide added is 0.2% of the mass of the waste electrode negative electrode powder. The sodium peroxide is prepared into a sodium peroxide aqueous solution with a total concentration of 0.5 mol / L and then added at a flow rate of 20 mL / min while stirring to react. After all the addition is completed, let it stand for 2 hours to obtain the negative electrode powder acid solution. S4. The negative electrode powder acid solution is filtered and centrifuged to obtain wet negative electrode powder and copper ion solution; S5. The wet negative electrode powder is dried at 130℃ for 4 hours, and then demagnetized with a magnetic field strength of 0.75T, a material feeding rate of 75g / s, and a magnetic separation time of 0.5 hours to obtain dry negative electrode powder. Then, the dry negative electrode powder was placed in an infrared baking device, and under vacuum conditions, the temperature was raised to 145°C for infrared irradiation baking. The infrared wavelength of the infrared irradiation was 8μm, and stirring was turned on for 3 minutes every 15 minutes. The baking time was 3 hours. The regenerated negative electrode powder was obtained by sieving and grinding. S6. Add 45 L of extractant tributyl phosphate to the obtained copper ion solution, start stirring at 750 rpm, react for 45 min, and after complete extraction, let stand for 30 min to obtain copper-loaded organic phase and aqueous phase. Back-extraction was performed by adding 0.5 mol / L sulfuric acid solution as a back-extraction agent to a copper-supported organic phase, followed by reduction by introducing sulfur dioxide. The molar ratio of sulfur dioxide to copper ions was 0.7:1. After evaporating the solvent, crude copper was recovered. S7. Crude copper is vacuum distilled to obtain electronic-grade copper products, specifically: S701. Place the crude copper in a vacuum furnace with a vacuum degree of 8 Pa; S702. The first stage of heating is carried out at a rate of 30℃ / min, and the temperature is increased to 1000℃; then the second stage of heating is carried out at a rate of 50℃ / min, and the temperature is increased to 1400℃, and then held for 3 hours. S703. Cool to 120°C for condensation and recovery to obtain electronic-grade copper products.

[0045] Performance testing: The recovery rates of the recycled negative electrode powder and electronic-grade copper products obtained in the examples and comparative examples were calculated, and the copper impurities in the recycled negative electrode powder were tested. The test results are shown in Table 1. Table 1 Performance Test Results

[0046] According to Table 1, it can be seen that the recovery rate of electronic-grade copper products in Example 3 is higher than that in Example 1, and the copper impurity content in the regenerated negative electrode powder is lower than that in Example 1. The reason may be that copper tartrate was added in the process of removing impurities from the waste negative electrode powder in Example 3, which can accelerate the leaching efficiency and leaching amount of copper ions, thereby improving the yield and purity of crude copper, and further improving the purity and yield of electronic-grade copper products. The recovery rates of the recycled products in Comparative Examples 1 and 2 were also lower than those in Example 1, and the copper impurity content in the regenerated negative electrode powder was higher than that in Example 1. This may be because in Comparative Example 1, thermal decomposition was used to remove the binder residue in the dry negative electrode powder. Compared with infrared irradiation treatment, the removal rate of binder is very limited, and high temperature may cause graphite oxidation and deactivation, which will directly affect the recovery rate of the regenerated negative electrode powder. In Comparative Example 2, acidic solution and oxidant were used to synergistically separate the negative electrode powder and copper ions. The acidic environment will affect the oxidation process of the oxidant, and compared with the alkaline environment, the acidic solution may also corrode the graphite negative electrode powder, resulting in a decrease in the recovery rate of both the regenerated negative electrode powder and copper, and a significant increase in the copper impurity content in the regenerated negative electrode powder.

[0047] The above-disclosed embodiments are merely a few specific examples of the present invention. However, the embodiments of the present invention are not limited thereto, and any variations that can be conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. A method for separating, purifying, and regenerating waste electrode negative electrode powder, characterized in that, The process includes the following steps: S1. Waste battery negative electrode sheets are crushed, ball-milled and sieved to obtain waste electrode sheet negative electrode powder; S2. Mix the waste electrode sheet negative electrode powder with deionized water to prepare a negative electrode powder slurry; S3. Add alkaline solution to the negative electrode powder slurry and stir to react. Then add impurity remover and continue stirring to react under an inert gas atmosphere to obtain a negative electrode powder alkaline solution. S4. The negative electrode powder alkaline solution is filtered and centrifuged to obtain wet negative electrode powder and copper ion solution; S5. The wet negative electrode powder is dried and demagnetized to obtain dry negative electrode powder; then it is subjected to infrared irradiation treatment, and finally regenerated negative electrode powder is obtained by sieving and grinding. S6. The copper ion solution is extracted to obtain a copper-loaded organic phase and an aqueous phase; the aqueous phase is evaporated and condensed to recover the alkaline solution; the copper-loaded organic phase is back-extracted, a reducing agent is added, the solvent is evaporated, and crude copper is recovered. S7. Crude copper is vacuum distilled to obtain electronic-grade copper products.

2. The method for separating, purifying, and regenerating waste electrode negative electrode powder according to claim 1, characterized in that, The particle size of the waste electrode negative electrode powder is 100-500 μm.

3. The method for separating, purifying, and regenerating waste electrode negative electrode powder according to claim 1, characterized in that, The solid-liquid ratio of the waste electrode negative electrode powder and deionized water is 1g:(5-10)mL.

4. The method for separating, purifying, and regenerating waste electrode negative electrode powder according to claim 1, characterized in that, The alkaline solution includes any one of sodium hydroxide aqueous solution, potassium hydroxide aqueous solution, ammonia water, and sodium carbonate aqueous solution; the mass ratio of the alkaline solution to the negative electrode powder slurry is (0.2~0.6):

1.

5. The method for separating, purifying, and regenerating waste electrode negative electrode powder according to claim 1, characterized in that, The amount of the impurity removal agent added is 0.1 to 0.5 wt% of the mass of the waste electrode negative electrode powder; The impurity removal agent includes an oxidizing agent, which includes one or more combinations of sodium peroxide, potassium oxide, hydrogen peroxide, and potassium chlorate.

6. The method for separating, purifying, and regenerating waste electrode negative electrode powder according to claim 5, characterized in that, The impurity removal agent also includes copper tartrate; the mass ratio of copper tartrate to oxidant is (0.2-0.4):

1.

7. The method for separating, purifying, and regenerating waste electrode negative electrode powder according to claim 1, characterized in that, The reaction temperature of the stirring reaction in step S3 is 30–85°C, and the reaction time is 2–48 h.

8. The method for separating, purifying, and regenerating waste electrode negative electrode powder according to claim 1, characterized in that, The infrared irradiation treatment in step S5 specifically includes: The negative electrode powder is placed in an infrared baking device and heated to 120-180°C under vacuum conditions for infrared irradiation baking. Stirring is turned on for 3-5 minutes every 10-20 minutes, and the baking time is 2-4 hours. The infrared wavelength of the infrared irradiation is 4-10 μm.

9. The method for separating, purifying, and regenerating waste electrode negative electrode powder according to claim 1, characterized in that, The extractant used in step S6 includes one or more combinations of tributyl phosphate, methyl isopropyl ketone, dimethylformamide, 2-naphthol, and trimethylamine; the back-extraction agent used includes any one of sulfuric acid, hydrochloric acid, formic acid, and acetic acid; the reducing agent includes iron and / or sulfur dioxide; and the molar ratio of the reducing agent to copper ions is (0.7–1.3):

1.

10. The method for separating, purifying, and regenerating waste electrode negative electrode powder according to claim 1, characterized in that, Step S7 specifically includes the following steps: S701. Place the crude copper in a vacuum furnace with a vacuum degree of 2 to 15 Pa; S702. Perform the first stage of heating at a rate of 20-40℃ / min, raising the temperature to 950-1100℃; then perform the second stage of heating at a rate of 40-60℃ / min, raising the temperature to 1200-1600℃, and then hold the temperature for 1-6 hours. S703. Cool to 100-200℃ for condensation and recovery to obtain electronic-grade copper products.

Images