A method of separation of metal powder and graphite powder in spent lithium ion battery electrode powder

Abstract

This invention provides a method for separating metal powder and graphite powder from waste lithium-ion battery electrode powder. The method involves hydrothermal treatment of the electrode powder to decompose the organic binder, followed by solid-liquid separation to obtain electrode powder with the organic binder removed. This slurry is then dispersed in water, and an organic solvent is added and thoroughly mixed before settling to form an aqueous phase and an organic solvent phase. The graphite powder migrates to the organic solvent phase, while the metal powder remains in the aqueous phase. Therefore, this method allows for the direct separation of metal powder and graphite powder, enriching and concentrating valuable metals. It serves as a beneficial pretreatment method for subsequent metallurgical purification processes, effectively reducing the processing volume and costs of subsequent processes, minimizing environmental impact, and promoting the recycling and reuse of metal resources and graphite.

Description

Technical Field

[0001] This invention provides a method for separating metal powder and graphite powder from waste lithium-ion battery electrode powder, and in particular a separation method that can recycle and reuse the organic solvent used, thereby reducing the amount of subsequent metallurgical processing, and thus reducing the amount of reagents used and processing costs. Prior Technology

[0002] The global demand for lithium-ion batteries is growing rapidly every year, and the amount of waste lithium-ion batteries generated will also increase year by year. It is estimated that by 2025, Taiwan's waste lithium-ion battery volume will reach about 1,100 metric tons, and by 2030 it will exceed 10,000 metric tons per year. Therefore, it is necessary to actively develop recycling and processing technologies for waste lithium-ion batteries in order to achieve resource recycling and realize the vision of a circular economy.

[0003] In existing technologies, waste lithium-ion batteries are generally discharged and then mechanically crushed. Then, iron is separated by magnetic separation, aluminum by eddy current separation, and plastic by gravity separation. The result is a black powder mixture containing positive electrode metal powder (containing lithium, cobalt, nickel, manganese, etc.) and negative electrode graphite powder, commonly known as black powder.

[0004] Subsequently, regarding the recycling and processing technology of waste lithium-ion battery electrode powder, most of the methods suggested in various references utilize metallurgical techniques to recover valuable metals from the waste lithium-ion battery electrode powder. These metallurgical techniques include pyrometallurgy and hydrometallurgy. However, the main disadvantages of pyrometallurgy are high temperature and energy consumption, as well as air pollution and smelting residues. Furthermore, the main disadvantages of hydrometallurgy are the need for large amounts of leaching and separation purification reagents, and the generation of large amounts of wastewater.

[0005] Therefore, if the valuable metal powder of the positive electrode material and the graphite powder of the negative electrode material in the waste lithium-ion battery electrode powder can be separated and the valuable metal enriched and concentrated before pyrometallurgical or hydrometallurgical treatment, the amount of subsequent pyrometallurgical or hydrometallurgical treatment can be effectively reduced, thereby reducing the amount of reagents used and the amount of smelting residue or wastewater generated, thus reducing treatment costs and carbon emissions during the recycling process. Summary of the Invention

[0006] To address the aforementioned problems, the present invention aims to provide a method for separating metal powder and graphite powder from waste lithium-ion battery electrode powder. This method directly separates the metal powder and graphite powder from the waste lithium-ion battery electrode powder before pyrometallurgical or hydrometallurgical processes are used to purify the metal, thereby enriching and concentrating valuable metals. This effectively reduces the processing volume in subsequent metallurgical processes, thereby reducing reagent usage and the generation of smelting residues or wastewater. Consequently, it lowers processing costs and carbon emissions during the recycling process, and promotes the recycling and reuse of metal resources and graphite from the waste lithium-ion battery electrode powder.

[0007] Therefore, in order to achieve the aforementioned objective, the present invention provides a method for separating metal powder and graphite powder from waste lithium-ion battery electrode powder, comprising: The hydrothermal treatment step involves mixing electrode powder from waste lithium-ion batteries containing metal powder and graphite powder with water to form a mixture, then subjecting the mixture to hydrothermal treatment to decompose the organic binder in the electrode powder. Subsequently, solid-liquid separation is performed to remove the liquid, resulting in electrode powder with the organic binder removed. The dispersion step involves dispersing the electrode powder, from which the organic binder has been removed, in water to form a slurry; In the phase separation step, an organic solvent is added to the slurry for mixing, followed by standing to form an organic phase and an aqueous phase. The graphite powder moves to the organic phase, while the metal powder remains in the aqueous phase. The liquid-liquid separation step separates the organic phase from the aqueous phase; and The solid-liquid separation step separates the organic solvent in the organic phase from the graphite powder and separates the water in the aqueous phase from the metal powder, thereby recovering the graphite powder and the metal powder.

[0008] In one embodiment of the present invention, in the hydrothermal treatment step, after the hydrothermal treatment and before the solid-liquid separation, the mixture is further washed with water to obtain the electrode powder with the organic binder removed.

[0009] In one embodiment of the invention, the hydrothermal treatment is carried out in a sealed container.

[0010] In one embodiment of the present invention, the liquid-to-solid ratio of the water added in the hydrothermal treatment step to the electrode powder is 1 to 7 mL / g.

[0011] In one embodiment of the present invention, the temperature of the hydrothermal treatment is 160°C to 240°C, and the time of the hydrothermal treatment is 0.25 to 2 hours.

[0012] In one embodiment of the present invention, in the dispersion step, the pH value of the slurry is adjusted to 3 to 11.

[0013] In one embodiment of the present invention, the organic solvent comprises at least one of kerosene, isooctane, and n-butanol.

[0014] In one embodiment of the invention, in the dispersion step, the amount of electrode powder with the organic binder removed is 1 to 3 g based on the amount of water added per 80 mL.

[0015] In one embodiment of the invention, the amount of the organic solvent added in the phase separation step is 5 to 25 mL, based on the amount of water added per 80 mL in the dispersion step.

[0016] In one embodiment of the present invention, the organic solvent separated by the solid-liquid separation step can be recycled and reused.

[0017] The advantages of this invention are as follows: First, by removing the organic binder between metal powder and graphite powder in waste lithium-ion battery electrode powder under relatively low temperature conditions, and then directly separating the metal powder and graphite powder by utilizing the differences in their surface properties, the energy consumption required for removing the organic binder can be reduced, and the use of strong acids and alkalis can be avoided, thereby reducing the generation of waste liquid and the impact on the environment. Second, as a pretreatment method for subsequent separation, purification, and refining processes of valuable metals such as lithium, cobalt, nickel, and manganese, it can reduce the amount and complexity of reagents used in subsequent pyrometallurgical or hydrometallurgical separation, purification, and recovery processes of valuable metals, and reduce wastewater discharge. Third, it can obtain high-purity recovered metal powder and recovered graphite powder, promoting the recycling and reuse of metal resources and graphite in waste lithium-ion battery electrode powder. Fourth, the organic solvent used to separate metal powder and graphite powder can still be reused after use, reducing the amount of reagents used in this invention.

[0018] The effects of this invention are not limited to those described above; other effects not mentioned will be clearly understood by those skilled in the art from the description of the claims. Simple Explanation of the Diagram

[0019] Figure 1 shows a flowchart of a method for separating metal powder and graphite powder from waste lithium-ion battery electrode powder according to the present invention; Figure 2(a) and (b) show the grade, recovery rate and separation efficiency of the metal powder and graphite powder separated and recovered after hydrothermal treatment at different temperatures, respectively; Figures 3(a) and (b) show the grade, recovery rate, and separation efficiency of the metal powder and graphite powder separated and recovered after hydrothermal treatment with different residence times, respectively; Figures 4(a) and (b) show the grade, recovery rate, and separation efficiency of the metal powder and graphite powder separated and recovered after hydrothermal treatment with different hydrothermal liquid-solid ratios, respectively; Figures 5(a) and (b) show the grade, recovery rate, and separation efficiency of the metal powder and graphite powder separated and recovered after phase separation under different organic solvent addition amounts; Figures 6(a) and (b) show the grade, recovery rate, and separation efficiency of the metal powder and graphite powder separated and recovered after the pH value of the aqueous slurry was adjusted to different values ​​in the dispersion step. Figures 7(a) and (b) show the grade, recovery rate, and separation efficiency of the metal powder and graphite powder separated and recovered after different electrode powder treatment rates; and Figure 8(a) and (b) show the grade, recovery rate and separation efficiency of the metal powder and graphite powder separated and recovered after separation treatment using organic solvents with different reuse times. Implementation

[0020] The advantages and features of the present invention and its implementation methods will become clearer from the embodiments described below. However, the present invention is not limited to the embodiments described below, but can be implemented in various different forms.

[0021] Without causing contradictions, any technical feature in any aspect of the present invention may be combined with other aspects of the present invention.

[0022] To achieve the aforementioned objectives, this invention provides a method for separating metal powder and graphite powder from waste lithium-ion battery electrode powder. The method involves decomposing and removing the organic binder used to bind the metal powder and graphite powder in the waste lithium-ion battery electrode powder at a relatively low temperature without the use of strong acids or alkalis. This method offers advantages such as reducing energy consumption for removing the organic binder, reducing wastewater generation and discharge, and minimizing environmental impact. Subsequently, the surface property differences between the metal powder and graphite powder are utilized for direct separation, thereby recovering graphite powder and enriched, concentrated metal powder.

[0023] Therefore, as a pretreatment method for subsequent separation, purification, and refining processes of valuable metals such as lithium, cobalt, nickel, and manganese, the method of this invention helps reduce the processing volume, reagent usage, and complexity of subsequent metallurgical purification processes for valuable metals, and also reduces wastewater discharge. Furthermore, the separated and recovered graphite powder can also be reused as a secondary resource.

[0024] Referring to Figure 1, the method for separating metal powder and graphite powder in waste lithium-ion battery electrode powder of the present invention includes: hydrothermal treatment step S1, dispersion step S2, phase separation step S3, liquid-liquid separation step S4, and solid-liquid separation step S5.

[0025] First, in the hydrothermal treatment step S1, the electrode powder of the waste lithium-ion battery containing metal powder and graphite powder is mixed with water to form a mixture, and then subjected to hydrothermal treatment to decompose the organic binder in the electrode powder. Subsequently, solid-liquid separation is performed to remove the liquid, so as to obtain electrode powder with the organic binder removed.

[0026] Since hydrothermal treatment is a thermochemical transformation process using water under high temperature and high pressure, it is preferable to carry out the heating in a closed container to maintain the high pressure state of the reaction environment. The closed container can be a hydrothermal reactor, but it is not limited to this; any container that allows the mixture of electrode powder and water to be heated in its closed environment is acceptable.

[0027] Preferably, in the hydrothermal treatment step S1, after hydrothermal treatment and before solid-liquid separation, the hydrothermally treated mixture is first cooled to room temperature, and then the cooled mixture is further washed with water to remove the decomposed organic binder. After solid-liquid separation to remove the liquid, the mixture with the organic binder removed is dried to obtain the dried electrode powder with the organic binder removed.

[0028] The liquid-to-solid ratio of water to electrode powder added in the hydrothermal treatment step S1 can be 1 to 7 mL / g, preferably 3 to 7 mL / g, more preferably 5 to 7 mL / g, and most preferably 5 mL / g.

[0029] In one embodiment, the hydrothermal treatment temperature can be from 160°C to 240°C, more preferably from 200°C to 220°C, and even more preferably 220°C.

[0030] In one embodiment, the hydrothermal treatment time can be from 0.25 to 2 hours, preferably from 1 to 2 hours, and more preferably 1 hour.

[0031] Subsequently, in dispersion step S2, the electrode powder, from which the organic binder has been removed, is dispersed in water to form a slurry. Dispersion step S2 can be performed, for example, by ultrasonic oscillation.

[0032] In the dispersion step S2, the pH value of the slurry can be adjusted to 3 to 11, preferably to 7 to 11, more preferably to 9 to 10, and most preferably to 9.

[0033] Subsequently, in phase separation step S3, an organic solvent is added to the slurry and thoroughly mixed before being allowed to stand for a period of time to form an organic phase and an aqueous phase. The graphite powder moves to the organic phase while the metal powder remains in the aqueous phase, thereby achieving the effect of separating the graphite powder and the metal powder from each other.

[0034] Phase separation step S3 can be carried out in a separatory funnel, and the mixing in phase separation step S3 can be carried out by a shaker. That is, the slurry and organic solvent can be placed in a separatory funnel and placed on a shaker for thorough mixing.

[0035] The organic solvent added in phase separation step S3 may include at least one of kerosene, isooctane and n-butanol, preferably kerosene.

[0036] Preferably, based on the amount of water added per 80 mL in the dispersion step S2, the amount of the organic solvent added in the phase separation step S3 can be 5 to 25 mL, more preferably 5 to 15 mL, and even more preferably 15 mL.

[0037] Preferably, in the dispersion step S2, based on the amount of water added per 80 mL, the amount of electrode powder with the organic binder removed can be 1 to 3 g, more preferably 1 to 1.5 g, and even more preferably 1 g.

[0038] That is, in the dispersion step S2, based on the amount of 1 g of electrode powder with binder removed, the amount of water added can be about 25 to 80 mL, more preferably about 50 to 80 mL, and even more preferably 80 mL.

[0039] Therefore, based on the amount of electrode powder with binder removed added in dispersion step S2, the volume ratio of water added in dispersion step S2 to the organic solvent added in phase separation step S3 can be about 25 to 80 mL: 5 to 25 mL, more preferably about 50 to 80 mL: 5 to 15 mL, and even more preferably 80 mL: 15 mL.

[0040] Subsequently, in the liquid-liquid separation step S4, the organic phase is separated from the aqueous phase. For example, the aqueous phase can be discharged from the bottom of the separating funnel and the organic phase can be discharged from the top of the separating funnel; or, the aqueous phase and the organic phase can be discharged from the bottom of the separating funnel in sequence.

[0041] Subsequently, in the solid-liquid separation step S5, the organic solvent in the organic phase is separated from the graphite powder, and the water in the aqueous phase is separated from the metal powder, and the separated graphite powder and metal powder are recovered.

[0042] The solid-liquid separation means used in any procedure of the present invention can be centrifugation or filtration, preferably centrifugation, but is not limited thereto.

[0043] The separated graphite powder and metal powder can be dried in an oven and then cooled at room temperature to obtain dried recycled graphite powder and metal powder.

[0044] After the above steps, the content (grade) of metal powder separated and recovered from the aqueous phase can be increased from 64.59% to 88.43%, and the recovery rate can reach 96.59%; the content (grade) of graphite powder separated and recovered from the oil phase can reach 92.53%, and the recovery rate can reach 76.96%.

[0045] On the other hand, the organic solvent recovered after the solid-liquid separation step S5 can be reused without affecting the separation effect of metal powder and graphite powder, so it can be recovered and reused. [Example] []

[0046] To illustrate in detail the method of separating metal powder and graphite powder from waste lithium-ion battery electrode powder of the present invention, so that those skilled in the art can clearly understand the effectiveness of the present invention, the experimental results and optimal conditions of the present invention will be described in detail below with examples. [Material] []

[0047] The waste lithium-ion battery electrode powder sample used in this embodiment of the invention has a metal powder content of 64.59 wt% and a graphite powder content of 35.41 wt% (determined using the following grade calculation method).

[0048] The organic solvents used in the embodiments of this invention include n-butanol, isooctane, kerosene, etc. [Experimental Methods] []

[0049] The following method is used for separation and recovery in this embodiment of the invention.

[0050] Hydrothermal treatment steps: Weigh 4 g of waste lithium-ion battery electrode powder sample and place it in a hydrothermal reactor (sealed container). Add deionized water, then place the hydrothermal reactor in a high-temperature furnace and heat it to the required temperature. After reaching the required reaction time, stop heating and let it cool to room temperature. Remove the waste lithium-ion battery electrode powder from the hydrothermal reactor and centrifuge it at 3500 rpm for 15 minutes. Wash the solid obtained after separation with deionized water 3 times to remove the decomposed organic binders. Place the washed solid in an oven at 105°C and dry it for 24 hours to obtain electrode powder with the organic binders removed.

[0051] Dispersion steps: Weigh 1 g of electrode powder with organic binder removed and place it in 80 mL of deionized water. Disperse it using ultrasonic shaking for 20 minutes, and then adjust the pH value.

[0052] Phase separation and liquid-liquid separation steps: Pour the pH-adjusted mixture into a 250 mL separatory funnel, add organic solvent, place it on a shaker and shake for 30 minutes to mix evenly, then let it stand for a period of time to form two phases: an aqueous phase and an organic solvent phase. Take out the aqueous phase and organic phase separately from the bottom of the separatory funnel.

[0053] Solid-liquid separation steps: The aqueous phase and organic phase were centrifuged at 3500 rpm for 15 minutes to separate the solids and liquids. The separated solids were dried in an oven at 105 °C for 24 hours and then cooled to room temperature. The weights of the recovered aqueous and organic phases were measured. The grades of metal powder and graphite powder in the recovered aqueous and organic phases were analyzed, and the recovery rates were calculated. The separation efficiency was calculated from the grades and recovery rates. [Grade Calculation] []

[0054] The solid recovered from the aqueous or organic phase is placed in a high-temperature furnace and heat-treated at 850°C for 3 hours. After heat treatment, the graphite powder is released in the form of carbon dioxide, and the remaining solid is the metal powder.

[0055] Therefore, for aqueous phase recoveries, the weight after heat treatment is the weight of the recovered metal powder; for organic phase recoveries, the weight difference before and after heat treatment is the weight of the recovered graphite powder. The grade calculation formula is as follows: [Recovery Rate Calculation] []

[0056] Take another 4 g of the original waste lithium-ion battery electrode powder from the hydrothermal treatment step and place it in a high-temperature furnace. Heat it at 850°C for 3 hours. After heat treatment, the graphite powder and organic matter (such as organic binder) will be released in the form of gas, and the remaining solid is metal powder.

[0057] Therefore, the weight of the electrode powder after heat treatment (with binder removed) is the weight of the metal powder in the electrode powder, and the weight difference of the electrode powder before and after heat treatment (with binder removed) is the weight of the graphite powder in the electrode powder. These weights are then used in conjunction with the weights of the metal powder recovered from the aqueous phase and the graphite powder recovered from the organic phase to calculate the recovery rate. The recovery rate calculation formula is as follows: [Separation efficiency calculation] []

[0058] Separation efficiency is the product of grade and recovery rate, reflecting the overall effectiveness of the separation process, i.e., the degree of success of the separation process. Higher separation efficiency indicates that not only can a large amount of the target component be effectively recovered, but the grade of the recovered material can also be guaranteed. Low separation efficiency suggests potential problems such as loss of target components or insufficient grade during the separation process. The formula for calculating separation efficiency is as follows: [Example] [1] [Temperature of hydrothermal treatment] []

[0059] Electrode powder separation and recovery were carried out under the following conditions: hydrothermal treatment – ​​hydrothermal time 2 hours, hydrothermal liquid-solid ratio (liquid-solid ratio of added water to original electrode powder) 5 mL / g; dispersion treatment – ​​1 g of electrode powder with binder removed, liquid-solid ratio of water to electrode powder 80 mL / g, slurry pH adjusted to 7; phase separation treatment – ​​20 mL of kerosene (organic solvent) added.

[0060] Among them, after hydrothermal treatment at different temperatures and overall separation and recovery process, the separation results of metal powder and graphite powder are shown in Figure 2(a) and (b), respectively.

[0061] Figure 2(a) shows that as the hydrothermal temperature increases from 160℃ to 220℃, the grade of recovered metal powder increases from 77.34% to 90.71%; when the hydrothermal temperature continues to increase to 240℃, the grade of metal powder does not change significantly. However, as the hydrothermal temperature increases, the recovery rate of metal powder ranges from 53.60% to 61.94%, without significant change. Therefore, as the hydrothermal temperature increases, the separation efficiency of metal powder increases accordingly, reaching a maximum separation efficiency of 53.06% at a hydrothermal temperature of 220℃.

[0062] Figure 2(b) shows that as the hydrothermal temperature increases from 160℃ to 220℃, the grade of recovered graphite powder increases from 48.52% to 54.05%, and the recovery rate increases from 67.55% to 89.07%. When the hydrothermal temperature continues to increase to 240℃, the grade and recovery rate of graphite powder do not change significantly. Therefore, as the hydrothermal temperature increases, the separation efficiency of graphite powder increases accordingly, reaching a maximum separation efficiency of 48.15% at a hydrothermal temperature of 220℃.

[0063] In other words, the separation effect of both metal powder and graphite powder is significantly improved with increasing hydrothermal temperature. The optimal separation effect is achieved at a hydrothermal temperature of 220℃, with a recovered metal powder grade of 90.71%, a recovery rate of 58.49%, and a separation efficiency of 53.06%; and a recovered graphite powder grade of 54.05%, a recovery rate of 89.07%, and a separation efficiency of 48.15%. [Example] [2] [Hydrothermal treatment time] []

[0064] Electrode powder separation and recovery were carried out under the following conditions: hydrothermal treatment—hydrothermal temperature 220℃, hydrothermal liquid-solid ratio 5 mL / g; dispersion treatment—weight of electrode powder with binder removed 1 g, liquid-solid ratio of water to electrode powder 80 mL / g, pH value of slurry adjusted to 7; phase separation treatment—addition of kerosene (organic solvent) 20 mL.

[0065] Among them, the separation results of metal powder and graphite powder after hydrothermal treatment with different residence (processing) times and overall separation and recovery process are shown in Figure 3(a) and (b), respectively.

[0066] Figure 3(a) shows that as the residence time increases from 0.25 hours to 0.5 hours, the grade of the recovered metal powder ranges from 66.88% to 66.97%, the recovery rate ranges from 51.65% to 52.30%, and the separation efficiency ranges from 34.54% to 35.03%, with no significant changes in any of the three. As the residence time increases from 0.5 hours to 1 hour, the grade of the metal powder increases from 66.97% to 89.24%, the recovery rate increases from 52.30% to 62.66%, and the separation efficiency increases from 35.03% to 55.91%. As the residence time increases from 1 hour to 2 hours, there are no significant changes in the grade, recovery rate, and separation efficiency of the metal powder.

[0067] Figure 3(b) shows that as the hydrothermal time increased from 0.25 hours to 0.5 hours, the grade of recovered graphite powder ranged from 37.69% to 37.83%, the recovery rate ranged from 52.95% to 53.35%, and the separation efficiency ranged from 20.03% to 20.11%, with no significant changes in any of the three. As the hydrothermal time increased from 0.5 hours to 1 hour, the grade of graphite powder increased from 37.83% to 55.86%, the recovery rate increased from 53.35% to 86.22%, and the separation efficiency increased from 20.11% to 48.17%. As the hydrothermal time increased from 1 hour to 2 hours, the grade, recovery rate, and separation efficiency of graphite powder did not change significantly.

[0068] That is, when the residence time of hydrothermal treatment is 1 hour, the separation effect of metal powder and graphite powder is the best. The grade of recovered metal powder is 89.24%, the recovery rate is 62.66%, and the separation efficiency is 55.91%; the grade of recovered graphite powder is 55.86%, the recovery rate is 86.22%, and the separation efficiency is 48.17%. [Example] [3] [Liquid-to-solid ratio in hydrothermal treatment] []

[0069] Electrode powder separation and recovery were carried out under the following conditions: hydrothermal treatment – ​​hydrothermal temperature 220℃, hydrothermal time 1 hour; dispersion treatment – ​​1 g of electrode powder with binder removed, liquid-solid ratio of water to electrode powder 80 mL / g, pH of slurry adjusted to 7; phase separation treatment – ​​20 mL of kerosene (organic solvent) added.

[0070] Among them, hydrothermal treatment was carried out with different hydrothermal liquid-solid ratios (the liquid-solid ratio of water added in hydrothermal treatment to the original electrode powder). After the overall separation and recovery process, the separation results of metal powder and graphite powder are shown in Figure 4(a) and (b), respectively.

[0071] Figure 4(a) shows that as the hydrothermal liquid-solid ratio increases from 1 mL / g to 5 mL / g, the grade of the recovered metal powder increases from 62.70% to 89.24%, while the recovery rate remains relatively stable, ranging from 55.13% to 62.66%. When the hydrothermal liquid-solid ratio continues to increase to 7 mL / g, neither the grade of the metal powder nor the recovery rate changes significantly. Therefore, the highest separation efficiency of 55.91% for the metal powder is achieved when the hydrothermal liquid-solid ratio is 5 mL / g.

[0072] Figure 4(b) shows that as the hydrothermal liquid-solid ratio increased from 1 mL / g to 5 mL / g, the grade of recovered graphite powder increased from 32.93% to 55.86%, and the recovery rate increased from 40.19% to 86.22%. When the hydrothermal liquid-solid ratio continued to increase to 7 mL / g, the grade and recovery rate of graphite powder did not change significantly. Therefore, the highest separation efficiency of 48.17% for graphite powder was achieved when the hydrothermal liquid-solid ratio was 5 mL / g.

[0073] That is, when the hydrothermal liquid-solid ratio is 5 mL / g, the separation effect of metal powder and graphite powder is the best. The grade of recovered metal powder is 89.24%, the recovery rate is 62.66%, and the separation efficiency is 55.91%; the grade of recovered graphite powder is 55.86%, the recovery rate is 86.22%, and the separation efficiency is 48.17%. [Example] [4] Types of organic solvents used in phase separation processes []

[0074] Electrode powder separation and recovery were carried out under the following conditions: hydrothermal treatment (optimal conditions) – hydrothermal temperature 220℃, hydrothermal time 1 hour, hydrothermal liquid-solid ratio 5 mL / g; dispersion treatment – ​​1 g of electrode powder with binder removed, liquid-solid ratio of water to electrode powder 80 mL / g, slurry pH adjusted to 7; phase separation treatment – ​​20 mL of organic solvent added.

[0075] Different types of organic solvents were used as organic phases for phase separation treatment. After the overall separation and recovery process, the separation results of metal powder and graphite powder are shown in Table 1.

[0076] Table 1. Final separation results of phase separation treatment using different organic solvents Recycle metal powder Recycle graphite powder grade (%) Recovery rate (%) Separation efficiency (%) grade(%) Recovery rate (%) Separation efficiency (%) kerosene 89.24 62.66 55.91 55.86 86.22 48.17 Isooctane 72.20 82.69 59.70 57.03 41.91 23.90 n-Butanol 69.53 75.26 52.33 46.89 39.85 18.69

[0077] The results above show that, compared with the original waste lithium-ion battery electrode powder sample containing 64.59 wt% metal powder and 35.41 wt% graphite powder, the grade of recovered metal powder and graphite powder is significantly improved regardless of whether kerosene, isooctane, or n-butanol is used as the organic phase for phase separation. Among them, the separation effect of using kerosene is the best. [Example] [5] [Amount of organic solvent added for phase separation treatment] []

[0078] Electrode powder separation and recovery were carried out under the following conditions: hydrothermal treatment (optimal conditions) – hydrothermal temperature 220℃, hydrothermal time 1 hour, hydrothermal liquid-solid ratio 5 mL / g; dispersion treatment – ​​1 g of electrode powder with binder removed, liquid-solid ratio of water to electrode powder 80 mL / g, and pH of slurry adjusted to 7; phase separation treatment – ​​kerosene as organic solvent.

[0079] Among them, phase separation treatment was carried out under different amounts of organic solvent. After the overall separation and recovery process, the separation results of metal powder and graphite powder are shown in Figure 5(a) and (b), respectively.

[0080] Figure 5(a) shows that as the amount of organic solvent added increased from 5 mL to 15 mL, the grade of the recovered metal powder increased from 73.98% to 86.56%, the recovery rate increased from 89.87% to 96.05%, and the separation efficiency increased from 66.49% to 83.15%. When the amount of organic solvent added continued to increase to 20 mL and 25 mL, the grade of the metal powder also increased to 89.24% and 96.92%, respectively. However, the recovery rates decreased to 62.66% and 60.83%, respectively, and the separation efficiencies decreased to 55.91% and 58.95%, respectively.

[0081] Figure 5(b) shows that as the amount of organic solvent added increased from 5 mL to 15 mL, the grade of recovered graphite powder increased from 69.62% to 91.00%, the recovery rate increased from 42.33% to 72.80%, and the separation efficiency increased from 29.47% to 66.25%. When the amount of organic solvent added continued to increase to 20 mL and 25 mL, the recovery rate of graphite powder also increased to 86.22% and 96.47%, respectively; however, the grade decreased to 55.86% and 57.45%, respectively, and the separation efficiency decreased to 48.17% and 55.42%, respectively.

[0082] The results above indicate that, based on the amount of water added per 80 mL in the dispersion treatment, the optimal amount of organic solvent added in the phase separation treatment is 15 mL. [Example] [6] [Aqueous slurry] [pH] [value] []

[0083] Electrode powder separation and recovery were carried out under the following conditions: hydrothermal treatment (optimal conditions) – hydrothermal temperature 220℃, hydrothermal time 1 hour, hydrothermal liquid-solid ratio 5 mL / g; dispersion treatment – ​​1 g of electrode powder with binder removed, liquid-solid ratio of water to electrode powder 80 mL / g; phase separation treatment – ​​15 mL of kerosene (organic solvent) added.

[0084] In the dispersion process, the pH value of the aqueous slurry was adjusted to different values. After the overall separation and recovery process, the separation results of metal powder and graphite powder are shown in Figure 6(a) and (b), respectively.

[0085] Figure 6(a) shows that as the pH value increases from 3 to 7, the grade of the recovered metal powder increases from 72.96% to 86.56%, the recovery rate increases from 79.05% to 96.05%, and the separation efficiency increases from 57.68% to 83.15%. As the pH value increases from 7 to 11, the grade, recovery rate, and separation efficiency of the metal powder do not change significantly.

[0086] Figure 6(b) shows that as the pH value increases from 3 to 7, the grade of recovered graphite powder increases from 54.93% to 91.00%, the recovery rate increases from 46.57% to 72.80%, and the separation efficiency increases from 25.58% to 66.25%; as the pH value increases from 7 to 11, the grade, recovery rate, and separation efficiency of graphite powder do not change significantly.

[0087] That is, it has a better separation effect on metal powder and graphite powder when the pH value of the aqueous phase is 7 to 11. []

[0088] Considering that the initial pH value of the electrode powder obtained after hydrothermal treatment and with the binder removed is about 9 to 10 in the aqueous slurry, in order to minimize the amount of acid-base neutralizing agents used in the separation and recovery process, and at the same time reduce the processing cost and its carbon footprint, pH 9 can be selected as the optimal pH value for the aqueous slurry. []

[0089] When the pH of the aqueous slurry is 9, the grade of the recovered metal powder is 88.43%, the recovery rate is 96.59%, and the separation efficiency is 85.42%; the grade of the recovered graphite powder is 92.53%, the recovery rate is 76.96%, and the separation efficiency is 71.21%. [] [Example] [7] [:dispersion] [The liquid-to-solid ratio of the treated aqueous phase ()] [Liquid-to-solid ratio of water to electrode powder] []

[0090] Electrode powder was separated and recovered under the following conditions: hydrothermal treatment (optimal conditions) – hydrothermal temperature 220℃, hydrothermal time 1 hour, hydrothermal liquid-solid ratio 5 mL / g; dispersion treatment – ​​slurry pH adjusted to 9; phase separation treatment – ​​kerosene (organic solvent) added 15 mL.

[0091] In the dispersion process, 80 mL of deionized water was added at a fixed rate, and electrode powder with different weights (different treatment amounts) of the removed organic binder was added. After the overall separation and recovery process, the separation results of the metal powder and graphite powder are shown in Figure 7(a) and (b), respectively.

[0092] Figure 7(a) shows that as the electrode powder treatment amount increased from 1 g / 80 mL (1 g electrode powder / 80 mL deionized water) to 3 g / 80 mL, the grade of the recovered metal powder decreased from 88.43% to 70.95%, while the recovery rate ranged from 93.46% to 96.59%, without significant change. Therefore, the separation efficiency of the metal powder decreased from 85.42% to 66.88%.

[0093] Figure 7(b) shows that as the electrode powder treatment amount increased from 1 g / 80 mL to 3 g / 80 mL, the grade of recovered graphite powder decreased from 92.53% to 73.88%, and the recovery rate decreased from 76.96% to 29.61%, so the separation efficiency decreased from 71.21% to 21.87%. []

[0094] Experimental results show that as the amount of electrode powder treated increases, the separation effect on both metal powder and graphite powder decreases. From the above, it can be concluded that, in the dispersion process, based on the amount of water added per 80 mL, it is preferable to treat less than 1 g of electrode powder with the organic binder removed; that is, the preferred liquid-solid ratio of water added in the dispersion step to electrode powder with the organic binder removed is 80 mL / g. [] [Example] [8] [:] [Number of times organic solvents can be reused] []

[0095] Electrode powder separation and recovery were carried out under the following conditions: hydrothermal treatment (optimal conditions) – hydrothermal temperature 220℃, hydrothermal time 1 hour, hydrothermal liquid-solid ratio 5 mL / g; dispersion treatment – ​​1 g of electrode powder with binder removed, liquid-solid ratio of water to electrode powder 80 mL / g, slurry pH adjusted to 9; phase separation treatment – ​​15 mL of kerosene (organic solvent) added.

[0096] In the phase separation process, organic solvents with different reuse times were used. After the overall separation and recovery process, the separation results of metal powder and graphite powder are shown in Figure 8(a) and (b), respectively.

[0097] Figure 8(a) shows that as the number of times the organic solvent is reused increases, the grade of the recovered metal powder ranges from 87.99% to 89.04%, the recovery rate ranges from 95.19% to 97.20%, and the separation efficiency ranges from 84.75% to 85.52%, with no significant changes in any of the three.

[0098] Figure 8(b) shows that as the number of times the organic solvent is reused increases, the grade of the recovered graphite powder ranges from 89.95% to 93.68%, the recovery rate ranges from 75.80% to 78.62%, and the separation efficiency ranges from 70.72% to 71.21%, with no significant changes among the three.

[0099] The above results show that even when using organic solvents with different reuse counts, there is no significant change in the separation effect on metal powder and graphite powder, confirming that the organic solvents used in the method of the present invention can be recycled and reused.

[0100] S1: Hydrothermal treatment steps S2: Dispersion Steps S3: Phase separation step S4: Liquid-liquid separation step S5: Solid-Liquid Separation Step

Claims

1. A method for separating metal powder and graphite powder from waste lithium-ion battery electrode powder, comprising: The hydrothermal treatment step involves mixing the electrode powder from the waste lithium-ion battery, which contains metal powder and graphite powder, with water to form a mixture. The mixture is then subjected to hydrothermal treatment to decompose the organic binder in the electrode powder. Subsequently, solid-liquid separation is performed to remove the liquid, thereby obtaining electrode powder with the organic binder removed. The dispersion step involves dispersing the electrode powder, from which the organic binder has been removed, in water to form a slurry; The process includes a phase separation step in which an organic solvent is added to the slurry, mixed, and allowed to stand to form an organic phase and an aqueous phase, wherein the graphite powder moves to the organic phase and the metal powder remains in the aqueous phase; a liquid-liquid separation step in which the organic phase and the aqueous phase are separated; and a solid-liquid separation step in which the organic solvent in the organic phase is separated from the graphite powder, and the water in the aqueous phase is separated from the metal powder, thereby recovering the graphite powder and the metal powder, wherein the organic solvent comprises at least one of kerosene, isooctane, and n-butanol.

2. The method as described in claim 1, wherein in the hydrothermal treatment step, after the hydrothermal treatment and before the solid-liquid separation, the mixture is further washed with water to obtain the electrode powder from which the organic binder has been removed.

3. The method as described in claim 1 or 2, wherein, The hydrothermal treatment is carried out in a closed container.

4. The method as described in claim 1 or 2, wherein, The liquid-to-solid ratio of the water added in this hydrothermal treatment step to the electrode powder is 1 to 7 mL / g.

5. The method as described in claim 1 or 2, wherein, The hydrothermal treatment temperature is 160°C to 240°C, and the hydrothermal treatment time is 0.25 to 2 hours.

6. The method as described in claim 1 or 2, wherein, In this dispersion step, the pH of the slurry is adjusted to between 3 and 11.

7. The method as described in request item 1 or 2, wherein, In this dispersion step, the amount of electrode powder with the organic binder removed is 1 to 3 g, based on the amount of water added per 80 mL.

8. The method as described in claim 1 or 2, wherein, Based on the amount of water added per 80 mL in the dispersion step, the amount of the organic solvent added in the phase separation step is 5 to 25 mL.

9. The method as described in claim 1 or 2, wherein, The organic solvent separated by this solid-liquid separation step can be recycled and reused.

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