Method for recycling valuable metal elements from waste lithium batteries through wet ball milling

Abstract

The invention provides a method for recycling valuable metal elements from a waste lithium battery through wet ball milling, and relates to the technical field of resource recycling. The method comprises the following steps: discharging the waste lithium battery, and removing an electrolyte, a diaphragm and a shell to obtain a copper-aluminum-pole piece mixture; crushing the copper-aluminum-pole piece mixture to obtain mixed electrode powder containing copper and aluminum; the mixed electrode powder containing the copper and the aluminum is mixed with a strong electrolyte solution, wet slurrying ball milling is carried out, high-valence metal in the mixed electrode powder is reduced through the copper and the aluminum, and a ball-milled slurrying material is obtained; and finally, valuable metal elements are extracted from the ball-milled slurrying material. The recovery method provided by the invention has the advantages of short flow, no need of a sorting process, low equipment investment, no introduction of an exogenous reducing agent, and realization of clean production; and reduction roasting is not needed, so that residual aluminum in the electrode powder is prevented from being combined with lithium in the reduction roasting process, the leaching rate of lithium is reduced, and meanwhile, energy and medicine consumption caused by high-temperature reaction is also avoided.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of resource recycling, and particularly relates to a method for recycling valuable metal elements from waste lithium batteries by using wet ball milling. BACKGROUND

[0002] In recent years, the rapid development of new energy vehicles is accompanied by the generation of a large number of waste lithium batteries, which will cause serious environmental pollution and resource waste if not properly handled, and there is a certain safety hazard.

[0003] Lithium batteries are classified according to the positive electrode material, mainly including lithium cobalt oxide batteries and ternary lithium batteries (the positive electrode material uses nickel-cobalt-manganese or nickel-cobalt-aluminum). Lithium batteries are mainly composed of a positive current collector (aluminum foil), a negative current collector (copper foil), a positive electrode sheet, a negative electrode sheet (graphite), a separator, an electrolyte and a shell (usually iron). A large number of waste lithium batteries contain rich valuable metals such as cobalt, nickel, manganese, lithium, aluminum and copper, which have great recycling value.

[0004] The mainstream process for recycling valuable metal elements from waste lithium batteries at present is: waste lithium ion battery - electrically broken - low-temperature negative pressure drying (remove electrolyte) - multi-component air separation / screening (remove separator) - magnetic separation (remove iron) - secondary crushing - multi-stage separation (remove Al and Cu) - positive / negative electrode powder - reduction roasting - preferential lithium extraction (i.e. acid leaching to extract lithium) - extraction of other valuable metal elements. The existing recycling process is long, especially in the separation stage, the equipment investment is large; in addition, although most of the iron, copper and aluminum are separated in the magnetic separation and separation processes, but due to the limitation of screening technology, the copper and aluminum in the positive and negative electrode powders are difficult to be completely separated, and the excessive aluminum combines with a large amount of lithium in the subsequent reduction roasting, and the reduction roasting combines lithium, aluminum and other components to form stable oxides, which are difficult to be dissolved, resulting in a low lithium leaching rate (generally 85-90%) when preferentially extracting lithium. SUMMARY

[0005] The present application provides a method for recycling valuable metal elements from waste lithium batteries by using wet ball milling, and the recycling method provided by the present application has a short process, does not need a separation process, has low equipment investment, and has a high lithium leaching rate.

[0006] In order to achieve the above-mentioned application purpose, the present application provides the following technical scheme:

[0007] The present application provides a method for recycling valuable metal elements from waste lithium batteries by using wet ball milling, comprising the following steps: discharging the waste lithium battery, removing the electrolyte, the separator and the shell to obtain a copper-aluminum-powder mixture; the waste lithium battery includes waste lithium cobalt oxide battery and / or waste ternary lithium battery;

[0008] The copper-aluminum-pole mixture is crushed to obtain a mixed electrode powder containing copper-aluminum;

[0009] The mixed electrode powder containing copper-aluminum and a strong electrolyte solution are mixed, wet slurry ball milling is performed, copper-aluminum reduces high-valence metals in the mixed electrode powder to obtain a ball-milled slurry; the high-valence metals include one or more of Co 3+ and Mn 4+ ;

[0010] The pH value of the ball-milled slurry is adjusted to 6-7, the slurry with a pH value of 6-7 is subjected to solid-liquid separation to obtain a lithium-containing solution and a first-stage leaching residue;

[0011] The first-stage leaching residue is subjected to acid leaching, the end point pH value of the acid leaching is 0.5-3.0, and solid-liquid separation is performed to obtain a leaching solution containing other valuable metal elements;

[0012] Alternatively, after the ball-milled slurry is obtained, the pH value of the ball-milled slurry is directly adjusted to 0.5-2.0, and solid-liquid separation is performed to obtain a leaching solution containing lithium and other valuable metal elements;

[0013] The other valuable metal elements include one or more of Co, Ni and Mn.

[0014] Preferably, the strong electrolyte in the strong electrolyte solution includes one or more of sodium sulfate, sodium thiosulfate, sodium pyrosulfate and sodium pyrosulfite.

[0015] Preferably, the strong electrolyte includes sodium sulfate and sodium thiosulfate; the mass ratio of the sodium sulfate to the sodium thiosulfate is (2-4):1.

[0016] Preferably, the mass concentration of the strong electrolyte in the strong electrolyte solution is 5-20%.

[0017] Preferably, the volume of the strong electrolyte solution and the mass of the mixed electrode powder containing copper-aluminum are in a mass ratio of (3-4) m 3 :1t.

[0018] Preferably, the rotation speed of the wet slurry ball milling is 20-40 r / min, and the time is 5-15 h.

[0019] Preferably, the ball-to-material ratio of the wet slurry ball milling is (10-20):1.

[0020] Preferably, a sodium bisulfate solution is used to adjust the pH value of the ball-milled slurry to 6-7.

[0021] Preferably, the size of the copper-aluminum-pole mixture is 2-5 cm.

[0022] The method according to claim 1 or 9 is characterized in that the particle size of the copper-aluminum mixed electrode powder is 100-300 mesh.

[0023] This invention provides a method for recovering valuable metal elements from spent lithium batteries using wet ball milling, comprising the following steps: discharging the spent lithium batteries to remove the electrolyte, separator, and casing, obtaining a copper-aluminum electrode mixture; the spent lithium batteries include spent lithium cobalt oxide batteries and / or spent ternary lithium batteries; crushing the copper-aluminum electrode mixture to obtain copper-aluminum mixed electrode powder; mixing the copper-aluminum mixed electrode powder with a strong electrolyte solution, and performing wet ball milling, whereby the copper and aluminum reduce the high-valence metals in the mixed electrode powder to obtain a ball-milled slurry; the high-valence metals include Co. 3+ and Mn 4+ One or more of the following: adjusting the pH of the ball-milled slurry to 6-7, performing solid-liquid separation on the slurry with a pH of 6-7 to obtain a lithium-containing solution and a first-stage leaching residue; subjecting the first-stage leaching residue to acid leaching, with the final pH of the acid leaching being 0.5-3.0, and performing solid-liquid separation to obtain a leachate containing valuable metal elements; the valuable metal elements include Co. 3+ and Mn 4+ One or more of the following; or, after obtaining the ball mill slurry, directly adjust the pH value of the ball mill slurry to 0.5-2.0, perform solid-liquid separation, and obtain a leachate containing lithium and other valuable metal elements; the other valuable metal elements include one or more of Co, Ni and Mn.

[0024] In the powder preparation stage, this invention only requires separating the battery casing and separator, eliminating the need to separate copper and aluminum, thus reducing equipment requirements, shortening the process flow, and saving costs. During ball milling, the aluminum and copper components contained in the current collector of the lithium battery itself are used to convert high-valence metals in the electrode powder to low-valence states without introducing exogenous reducing agents, enabling clean production. Reduction roasting and reduction leaching are unnecessary; ball milling at room temperature can achieve the conversion of high-valence metals to low-valence states, preventing residual aluminum in the electrode powder from combining with lithium during reduction roasting, which would reduce the lithium leaching rate. It also avoids the energy and chemical consumption associated with high-temperature reactions, providing a new approach for room-temperature lithium extraction and enabling the comprehensive recycling and reuse of multiple valuable metals within a shorter process. Detailed Implementation

[0025] This invention provides a method for recovering valuable metal elements from waste lithium batteries using wet ball milling, comprising the following steps: discharging the waste lithium batteries to remove the electrolyte, separator and shell, and obtaining a copper-aluminum electrode mixture;

[0026] The copper-aluminum electrode mixture is crushed to obtain copper-aluminum mixed electrode powder;

[0027] The copper-aluminum mixed electrode powder is mixed with a strong electrolyte solution and then subjected to wet ball milling. The copper and aluminum reduce the high-valence metals in the mixed electrode powder to obtain a ball-milled slurry. The high-valence metals include Co. 3+ and Mn 4+ One or more of the following;

[0028] The pH value of the ball mill slurry is adjusted to 6-7, and the slurry with a pH value of 6-7 is subjected to solid-liquid separation to obtain a lithium-containing solution and a first-stage leaching residue;

[0029] The leaching residue is subjected to acid leaching, with the final pH value of the acid leaching being 0.5 to 3.0. Solid-liquid separation is then performed to obtain a leachate containing other valuable metal elements.

[0030] Alternatively, after obtaining the ball mill slurry, the pH value of the ball mill slurry is directly adjusted to 0.5-2.0, and solid-liquid separation is performed to obtain a leachate containing lithium and other valuable metal elements;

[0031] The other valuable metallic elements include one or more of Co, Ni, and Mn.

[0032] Unless otherwise specified, the materials and equipment used in this invention are all commercially available products in the field.

[0033] This invention discharges used lithium batteries to remove the electrolyte, separator, and casing, resulting in a copper-aluminum electrode mixture.

[0034] In this invention, the waste lithium batteries include waste lithium cobalt oxide batteries and / or waste ternary lithium batteries.

[0035] The present invention preferably involves discharge under the protection of an inert gas. In the present invention, the inert gas preferably includes nitrogen, and the volume content of oxygen in the inert gas is preferably less than 1%.

[0036] In this invention, the removal of electrolyte preferably includes: drying the discharged waste lithium battery at a low temperature; the temperature of the low-temperature drying is preferably 300-400°C, and the time is preferably 1.0-3.0h.

[0037] In this invention, the removal of the separator and the outer shell preferably includes: shredding the waste lithium battery after removing the electrolyte, feeding the shredded product into a drum screen for dispersing, and having the battery separator and the outer shell sucked away by an induced draft fan and an external magnetic separator to obtain a copper-aluminum electrode mixture.

[0038] This invention utilizes a drum screener to remove the outer shell, reducing the amount of electrode powder entrained and resulting in a higher electrode powder yield.

[0039] In this invention, the size of the copper-aluminum electrode mixture is preferably 2 to 5 cm.

[0040] After obtaining the copper-aluminum electrode mixture, the present invention crushes the copper-aluminum electrode mixture to obtain copper-aluminum mixed electrode powder.

[0041] The present invention does not have special requirements for the crushing method; any crushing method well known in the art can be used. In the present invention, the particle size of the copper-aluminum mixed electrode powder is preferably 100-300 mesh.

[0042] After obtaining the copper-aluminum mixed electrode powder, the present invention mixes the copper-aluminum mixed electrode powder with a strong electrolyte solution and performs wet slurry ball milling. The copper and aluminum reduce the high-valence metals in the mixed electrode powder to obtain the ball-milled slurry.

[0043] In this invention, the strong electrolyte in the strong electrolyte solution preferably includes one or more of sodium sulfate, sodium thiosulfate, sodium pyrosulfate, and sodium metabisulfite, more preferably sodium sulfate and sodium thiosulfate; the mass ratio of sodium sulfate to sodium thiosulfate is preferably (2-4):1, more preferably (2.5-3.5):1, and even more preferably 3:1. In this invention, the mass concentration of the strong electrolyte in the strong electrolyte solution is preferably 5-20%, more preferably 10-15%.

[0044] In this invention, the preferred volume ratio of the strong electrolyte solution to the mass ratio of the copper-aluminum mixed electrode powder is (3-4) m. 3 1t, more preferably (3.2~3.7)m 3 :1t.

[0045] In this invention, the strong electrolyte solution serves to facilitate electron conduction and promote the reduction reaction.

[0046] In this invention, the rotation speed of the wet ball mill is preferably 20-40 r / min, more preferably 25-35 r / min; the time of the wet ball mill is preferably 5-15 h, more preferably 8-12 h; and the ball-to-material ratio is preferably (10-20):1, more preferably (13-18):1.

[0047] In the wet slurry ball milling process of this invention, elemental aluminum and elemental copper (mainly elemental aluminum) reduce the high-valence metals in the mixed electrode powder to low-valence states. In this invention, the high-valence metals include Co. 3+ and Mn 4+ One or more of the following; more specifically, when the waste lithium battery is a waste lithium cobalt oxide battery, the high-valence metal refers to Co. 3+When the cathode material is nickel-cobalt-manganese from spent ternary lithium batteries, the high-valence metal refers to Co. 3+ and Mn 4+ When the cathode material is nickel-cobalt-aluminum used in discarded ternary lithium batteries, the high-valence metal refers to Co. 3+ .

[0048] After wet ball milling, Co 3+ Reduced to Co 2+ Mn 4+ Reduced to Mn 2+ Metals in lower valence states are more likely to dissolve.

[0049] After obtaining the ball mill slurry, the present invention can process the ball mill slurry in two ways.

[0050] The first approach is as follows:

[0051] The pH value of the ball mill slurry is adjusted to 6-7, and the slurry with a pH value of 6-7 is subjected to solid-liquid separation to obtain a lithium-containing solution and a first-stage leaching residue; the first-stage leaching residue is subjected to acid leaching, and the final pH value of the acid leaching is 0.5-3.0, and solid-liquid separation is performed to obtain a leachate containing other valuable metal elements.

[0052] In this invention, sodium bisulfate solution is preferably used to adjust the pH of the ball-milled slurry to 6-7. The concentration of the sodium bisulfate solution is not specifically required in this invention. Adjusting the pH of the slurry to 6-7 prevents aluminum and copper, which reacted with high-valence cobalt earlier, from transferring into the solution, thus achieving impurity removal. Furthermore, when the pH of the slurry is 6-7, other valuable metal elements besides lithium (i.e., the reduced low-valence metals) are insoluble in water, thereby preferentially extracting lithium.

[0053] In this invention, the solid-liquid separation preferably includes pressure filtration.

[0054] After obtaining a leaching residue, the present invention performs acid leaching on the leaching residue, with the final pH value of the acid leaching being 0.5 to 3.0, followed by solid-liquid separation to obtain a leachate containing other valuable metal elements.

[0055] In this invention, the acid solution used for acid leaching preferably comprises a sulfuric acid solution, and the mass concentration of the sulfuric acid solution is preferably 25-40%, more preferably 30-35%. In this invention, the volume ratio of the sulfuric acid to the mass of the first-stage leaching residue (also called the acid-to-material ratio) is preferably (0.4-0.8) m³ / s. 3 1t, more preferably (0.65~0.72)m 3 :1t.

[0056] In this invention, the final pH value of the acid leaching is preferably 1.0 to 2.5, more preferably 1.5 to 2.0. During the acid leaching process, the pH value continuously increases and eventually stabilizes; during the acid leaching process, each valuable metal element is converted into a dissolved state.

[0057] The present invention does not have any special requirements for the solid-liquid separation method; any solid-liquid separation method well known in the art can be used, such as pressure filtration.

[0058] In this invention, the other valuable metallic elements include one or more of Co, Ni, and Mn. After acid leaching, Cu and Al also enter the leachate in ionic form.

[0059] The second method for processing pulping materials is described below.

[0060] After obtaining the ball mill slurry, the pH value of the ball mill slurry is adjusted to 0.5-2.0, and solid-liquid separation is performed to obtain a leachate containing lithium and other valuable metal elements.

[0061] In this invention, dilute sulfuric acid is preferably used to adjust the pH value of the ball mill slurry to 0.5–2.0. By adjusting the pH value of the ball mill slurry to 0.5–2.0, this invention promotes the full dissolution of various metal elements, resulting in a leachate containing lithium and other valuable metal elements. In this invention, the other valuable metal elements have already been discussed above and will not be repeated here.

[0062] In the powder preparation stage, this invention only requires separating the battery casing and separator, eliminating the need to separate copper and aluminum, thus significantly reducing equipment requirements, shortening the process flow, and saving costs. During ball milling, the aluminum and copper components contained in the current collector of the lithium battery itself are used to convert high-valence metals in the electrode powder to low-valence states without introducing exogenous reducing agents, enabling clean production. This invention eliminates the need for reduction roasting; ball milling at room temperature can achieve the conversion of high-valence metals to low-valence states, preventing residual aluminum in the electrode powder from combining with lithium during reduction roasting, reducing the lithium leaching rate, and avoiding the energy and chemical consumption caused by high-temperature reactions. This provides a new approach for room-temperature lithium extraction, achieving comprehensive recycling and reuse of multiple valuable metals in a shorter process.

[0063] The following detailed description, in conjunction with embodiments, illustrates the method for recovering valuable metal elements from spent lithium batteries using wet ball milling, but these descriptions should not be construed as limiting the scope of protection of this invention.

[0064] Example 1

[0065] The waste lithium batteries used in this embodiment are 523 ternary lithium batteries. The waste lithium batteries are crushed and discharged under nitrogen protection, dried at 350℃ for 1 hour, then shredded. The shredded product is fed into a drum screen for further dispersion. The battery separator and casing are removed by an induced draft fan and an external magnetic separator, resulting in a copper-aluminum electrode mixture with a size of 2-5 cm. This copper-aluminum electrode mixture is then crushed to obtain a copper-aluminum mixed electrode powder with a particle size of 150-200 mesh (composition shown in Table 1). A ball mill is metered to 1 ton, and a 3 ml solution containing sodium sulfate and sodium thiosulfate in a 3:1 ratio is pumped into the ball mill. 3 (20% by mass) was wet-milled at a ball mill speed of 20 r / min and a ball-to-material ratio of 15:1. After 7 hours of ball milling, the mixture was transferred to a transfer tank and the pH was adjusted to 6.5 with sodium bisulfate solution. The mixture was then filtered to obtain a lithium-containing solution and a first-stage leaching residue. The lithium leaching rate was 96.46%.

[0066] The leaching residue was mixed with a sulfuric acid solution and acid leaching was performed at an acid-to-material ratio of 0.65. After leaching for 2 hours, the pH value at the leaching endpoint reached 1.0. The solution was then filtered to obtain a leachate with a nickel leaching rate of 97.65%, a cobalt leaching rate of 92.34%, and a manganese leaching rate of 96.63%.

[0067] In this invention, the leaching rate (%) = leaching amount (g) / raw material amount (g) × 100%.

[0068] Table 1. Main composition (wt%) of copper-aluminum hybrid electrode powder in Example 1

[0069] Composition Ni Co Mn Li Fe Al Cu % of share 20.76 5.25 7.21 3.58 0.93 2.19 3.56

[0070] Example 2

[0071] In this embodiment, the waste lithium batteries used are 622-type ternary lithium batteries. The waste lithium batteries are crushed and discharged under nitrogen protection, dried at 350℃ for 1 hour, then shredded. The shredded product is fed into a drum screen for further dispersion. The battery separator and casing are removed by an induced draft fan and an external magnetic separator, resulting in a copper-aluminum electrode mixture with a size of 2-5 cm. This copper-aluminum electrode mixture is then crushed to obtain a copper-aluminum mixed electrode powder with a particle size of 200-300 mesh (composition shown in Table 2). 1 ton of this powder is metered into a ball mill, and 4 ml of a mixed solution containing sodium sulfate and sodium thiosulfate in a 4:1 ratio is pumped into the ball mill. 3 (20% mass concentration) was wet-milled at a ball mill speed of 40 r / min and a ball-to-material ratio of 15:1. After 14 hours of ball milling, the mixture was transferred to a transfer tank and the pH value was adjusted to 6.3 with sodium bisulfate solution. After pressure filtration, a lithium-containing solution and a first-stage leaching residue were obtained. The lithium leaching rate was 97.85%.

[0072] The leaching residue was mixed with a sulfuric acid solution and acid leaching was performed at an acid-to-material ratio of 0.72. The final pH of the leaching was 0.61. After pressure filtration, the leachate was obtained. The nickel leaching rate was 98.36%, the cobalt leaching rate was 92.25%, and the manganese leaching rate was 97.13%.

[0073] Table 2. Main composition (wt%) of copper-aluminum hybrid electrode powder in Example 2

[0074] Composition Ni Co Mn Li Fe Al Cu % of share 21.8 6.47 6.45 3.64 0.5297 3.53 3.23

[0075] Example 3

[0076] The waste lithium batteries used in this embodiment are lithium cobalt oxide batteries. The waste lithium batteries are crushed and discharged under nitrogen protection, dried at 350℃ for 1 hour, and then shredded. The shredded product is fed into a drum screen for further dispersion. The battery separator and casing are removed by an induced draft fan and an external magnetic separator, resulting in a copper-aluminum electrode mixture with a size of 2-5 cm. This copper-aluminum electrode mixture is then crushed to obtain a copper-aluminum mixed electrode powder with a particle size of 200-300 mesh (composition shown in Table 3). 1 t of the powder is metered into a ball mill, and 4 ml of a mixed solution containing sodium sulfate and sodium thiosulfate in a 4:1 ratio is pumped into the ball mill. 3 (20% by mass) was wet-milled at a ball mill speed of 40 r / min and a ball-to-material ratio of 10:1. After 14 hours of ball milling, the mixture was transferred to a transfer tank and the pH was adjusted to 0.55 with sulfuric acid solution. The mixture was then filtered to obtain a leaching solution containing lithium and cobalt. The lithium leaching rate was 97.76% and the cobalt leaching rate was 89.21%.

[0077] Table 3. Main composition (wt%) of copper-aluminum mixed electrode powders in Examples 3 and 4

[0078] Element Li Ni Co Mn Cu Al Fe C Content % 6.51 6.23 63.25 1.33 0.27 1.32 12.70 2.37

[0079] Example 4

[0080] The waste lithium batteries used in this embodiment are lithium cobalt oxide batteries. The waste lithium batteries are crushed and discharged under nitrogen protection, dried at 350℃ for 1 hour, and then shredded. The shredded product is fed into a drum screen for further dispersion. The battery separator and casing are removed by an induced draft fan and an external magnetic separator, resulting in a copper-aluminum electrode mixture with a size of 2-5 cm. This copper-aluminum electrode mixture is then crushed to obtain a copper-aluminum mixed electrode powder with a particle size of 200-300 mesh (composition shown in Table 3). 1 t of the powder is metered into a ball mill, and 4 ml of a mixed solution containing sodium sulfate and sodium thiosulfate in a 4:1 ratio is pumped into the ball mill. 3 (20% by mass) was wet-milled at a ball mill speed of 40 r / min and a ball-to-material ratio of 10:1. After 14 hours of ball milling, the mixture was transferred to a transfer tank and the pH value was adjusted to 1.55 with sulfuric acid solution. The mixture was then filtered to obtain a leaching solution containing lithium and cobalt. The lithium leaching rate was 95.99% and the cobalt leaching rate was 88.27%.

[0081] As can be seen from the above embodiments, the present invention provides a method for recovering valuable metal elements from waste lithium batteries using wet ball milling. The recovery method provided by the present invention has a short process, requires no sorting process, has low equipment investment, and has a high lithium leaching rate.

[0082] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for recovering valuable metal elements from spent lithium batteries using wet ball milling, comprising the following steps: The waste lithium batteries are discharged to remove the electrolyte, separator and shell, to obtain a copper-aluminum electrode mixture; the waste lithium batteries include waste lithium cobalt oxide batteries and / or waste ternary lithium batteries. The copper-aluminum electrode mixture is crushed to obtain copper-aluminum mixed electrode powder; The copper-aluminum mixed electrode powder is mixed with a strong electrolyte solution and then subjected to wet ball milling. The copper and aluminum reduce the high-valence metals in the mixed electrode powder to obtain a ball-milled slurry. The high-valence metals include Co. 3+ and Mn 4+ One or more of the following; The pH value of the ball mill slurry is adjusted to 6-7, and the slurry with a pH value of 6-7 is subjected to solid-liquid separation to obtain a lithium-containing solution and a first-stage leaching residue; The leaching residue is subjected to acid leaching, with the final pH value of the acid leaching being 0.5 to 3.

0. Solid-liquid separation is then performed to obtain a leachate containing other valuable metal elements. Alternatively, after obtaining the ball mill slurry, the pH value of the ball mill slurry is directly adjusted to 0.5-2.0, and solid-liquid separation is performed to obtain a leachate containing lithium and other valuable metal elements; The other valuable metallic elements include one or more of Co, Ni, and Mn.

2. The method according to claim 1, characterized in that, The strong electrolyte in the strong electrolyte solution includes one or more of sodium sulfate, sodium thiosulfate, sodium pyrosulfate, and sodium metabisulfite.

3. The method according to claim 2, characterized in that, The strong electrolyte includes sodium sulfate and sodium thiosulfate; the mass ratio of sodium sulfate to sodium thiosulfate is (2-4):

1.

4. The method according to any one of claims 1 to 3, characterized in that, The mass concentration of the strong electrolyte in the strong electrolyte solution is 5-20%.

5. The method according to any one of claims 1 to 3, characterized in that, The volume ratio of the strong electrolyte solution to the mass ratio of the copper-aluminum mixed electrode powder is (3-4) m. 3 :1t.

6. The method according to claim 1, characterized in that, The wet ball milling speed is 20-40 r / min, and the time is 5-15 h.

7. The method according to claim 1 or 6, characterized in that, The ball-to-material ratio of the wet slurry ball mill is (10-20):

1.

8. The method according to claim 1, characterized in that, The pH value of the ball mill slurry was adjusted to 6-7 using sodium bisulfate solution.

9. The method according to claim 1, characterized in that, The size of the copper-aluminum electrode mixture is 2-5 cm.

10. The method according to claim 1 or 9, characterized in that, The particle size of the copper-aluminum mixed electrode powder is 100-300 mesh.