Selective leaching method of valuable metals in retired ternary lithium battery cathode material

Abstract

This invention belongs to the field of resource recycling technology and discloses a selective leaching method for valuable metals in the cathode material of retired ternary lithium batteries. The method involves discharging, disassembling, crushing, sieving, and mechanically milling the retired ternary lithium batteries to obtain cathode material powder. This powder is then mixed with DES solvent for stirring and leaching, followed by solid-liquid separation to obtain a solution rich in metal ions. During the leaching process, substance D is added to the mixture every 10 minutes. Substance D is one or more of ethylenediaminetetraacetic acid, sodium dodecyl sulfate, and sodium citrate. Substance E is added 10-20 minutes after the start of leaching. Substance E is one or more of ethylenediamine, pyridinecarboxylic acid, and sodium dithiocarbamate. This invention enhances the complexation selectivity of metal ions at different pH levels by adding DES solvent and combining it with substance E, thereby achieving stepwise leaching of nickel, cobalt, manganese, and lithium and improving leaching efficiency.

Description

Technical Field

[0001] This invention belongs to the field of resource recycling technology, and in particular relates to a selective leaching method for valuable metals in retired ternary lithium battery cathode materials based on a self-healing DES solvent and micro / nano bubble composite process. Background Technology

[0002] With the rapid development of electric vehicles and energy storage systems, a large number of retired ternary lithium batteries need to be recycled. Ternary lithium battery cathode materials contain abundant metals such as nickel, cobalt, manganese, and lithium. Recycling these metal resources not only reduces resource waste and environmental pollution but also effectively lowers the cost of manufacturing new batteries. Current recycling technologies mainly use eutectic solvents or acidic solvents to leach metal ions from battery materials. However, existing methods have the following drawbacks: some eutectic solvents easily generate metal oxalate precipitates, reducing the metal leaching rate and hindering efficient separation; traditional leaching processes are inefficient and time-consuming, and the solvent is difficult to recycle after leaching, increasing processing costs; the electrode materials regenerated after metal leaching typically have insufficient conductivity and poor battery cycle performance.

[0003] Therefore, there is an urgent need for an innovative method that can efficiently recover nickel, cobalt, manganese and lithium from retired lithium batteries. This method should have higher leaching efficiency, solvent recyclability and be able to process waste battery materials under mild conditions. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the deficiencies and defects mentioned in the background art above, and to provide a selective leaching method for valuable metals in retired ternary lithium battery cathode materials based on a self-healing DES solvent and micro-nano bubble composite process.

[0005] To solve the above-mentioned technical problems, the technical solution proposed by this invention is as follows:

[0006] (1) Discharge, disassemble, crush and sieve retired ternary lithium batteries to obtain positive electrode material powder;

[0007] (2) The positive electrode material powder is mechanically vibrated and milled;

[0008] (3) The positive electrode material powder after mechanical grinding is mixed with DES solvent and stirred for leaching and solid-liquid separation to obtain a solution rich in metal ions; wherein, the DES solvent includes substance A, substance B and substance C in a mass ratio of (2~3):(1~2):1, substance A is one or more of choline chloride, alanine and glycine, substance B is one or more of citric acid, oxalic acid and lactic acid, and substance C is one or more of ethylene glycol, polyethylene glycol and sorbitol; during the leaching process, substance D is added to the mixed system every 10 min, substance D is one or more of ethylenediaminetetraacetic acid, sodium dodecyl sulfate and sodium citrate; 10~20 min after the start of leaching, substance E is added to the mixed system, substance E is one or more of ethylenediamine, pyridinecarboxylic acid and sodium dithiocarbamate.

[0009] In the above-mentioned selective leaching method for valuable metals in the cathode material of retired ternary lithium batteries, preferably, in step (3), the mass of the substance D added is 5% to 10% of the mass of the DES solvent.

[0010] In the above-mentioned selective leaching method for valuable metals in the cathode material of retired ternary lithium batteries, preferably, in step (3), the added mass of substance E is 20% to 30% of the mass of the self-healing DES solvent.

[0011] In the above-mentioned selective leaching method for valuable metals in the cathode material of retired ternary lithium batteries, preferably, during the leaching process, acidic or alkaline regulators are added in stages to adjust the pH of the solvent to achieve selective leaching of nickel, cobalt, manganese and lithium. First, the pH of the system is adjusted to 3-4 to leach lithium for 10-20 minutes. Then, the pH is adjusted to 5-6 and substance E is added to enhance the selective leaching of nickel, cobalt and manganese.

[0012] In the process of this invention, substance A in the DES solvent serves as the basic solvent component, forming a eutectic solvent system together with substances B and C. Its hydrogen bond donor / acceptor effect enhances the solvent's complexation capacity for metal ions. Substance B, by providing organic acid anions, improves the complexation of metals such as nickel, cobalt, and manganese, and enhances the stability of the solvent. The addition of substance C effectively reduces the viscosity of the solvent, enhancing its permeability and the mass transfer efficiency of metal ions. During the leaching process, substance E is added. Substance E acts as a complexation enhancer, playing a crucial role in the selective complexation of specific metal ions, making the leaching process more selective and efficient, especially in the enrichment of metals such as nickel, cobalt, and manganese. Substance D, as a self-healing component, ensures solvent activity even when replenished, preventing solvent aging or performance degradation during leaching, while also ensuring the recycling of the solvent.

[0013] In the above-mentioned selective leaching method for valuable metals in the cathode material of retired ternary lithium batteries, preferably, in step (3), the mass ratio of the DES solvent to the cathode material powder is (15~25):1.

[0014] In the above-mentioned selective leaching method for valuable metals in the cathode material of retired ternary lithium batteries, preferably, in step (3), the leaching temperature is 60~80℃, the leaching time is 30~60 min, and the stirring rate during the leaching process is 600~800 rpm.

[0015] In the above-mentioned selective leaching method for valuable metals in the cathode material of retired ternary lithium batteries, preferably, in step (3), micro-nano bubbles are introduced into the mixed system during the leaching process.

[0016] The introduction of micro- and nanobubbles is primarily aimed at enhancing the contact efficiency between the solvent and the material. Due to their small diameter, micro- and nanobubbles have a large specific surface area, enabling them to form a uniform distribution in the liquid phase, thereby increasing the gas-liquid interface area. When micro- and nanobubbles adhere to the material surface, they can generate local turbulence, accelerating the mass transfer process between the solvent and the material. Furthermore, the collapse of micro- and nanobubbles in the solution generates minute shear forces and ultrasonic effects, which facilitate the rapid desorption and dissolution of metal ions, thus significantly improving the metal leaching rate and efficiency.

[0017] In the above-mentioned selective leaching method for valuable metals in the cathode material of retired ternary lithium batteries, preferably, the diameter of the micro-nano bubbles is 10~50 nm, and the introduction rate of the micro-nano bubbles is 10~20 mL / min.

[0018] In the above-mentioned selective leaching method for valuable metals in the cathode material of retired ternary lithium batteries, preferably, the particle size D50 of the cathode material powder is 15~20 μm; the mechanical oscillation frequency is 30~50 Hz, and the oscillation time is 10~30 min. The purpose of oscillation is to form nanoscale cracks and porous structures on the material surface, significantly increasing the specific surface area and improving the contact between the solvent and the material. This structure helps metal ions to dissolve more easily and provides sites for the attachment of micro and nano bubbles, further optimizing the mass transfer effect and thus improving the leaching efficiency.

[0019] The selective leaching method for valuable metals in the above-mentioned retired ternary lithium battery cathode material preferably involves selectively precipitating the metal ion-rich solution obtained after step (3) in steps to obtain metal salt products, and adding substance D to the residual solution to restore its activity and achieve recycling, wherein the added mass of substance D is 60%~70% of the mass of the residual solution.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] (1) In the selective leaching process of valuable metals in the cathode material of retired ternary lithium batteries, the present invention enhances the complexation selectivity of metal ions at different pH by adding DES solvent and combining it with substance E, thereby achieving stepwise leaching of nickel, cobalt, manganese and lithium and improving leaching efficiency.

[0022] (2) In the selective leaching process of valuable metals in the cathode material of retired ternary lithium batteries, the activity of the solvent system can be continuously restored by adding substance D, which prevents solvent aging or performance degradation during the leaching process, and also ensures the multiple recycling of the solvent, reduces solvent loss, lowers process costs, and enhances environmental protection.

[0023] (3) In the selective leaching process of valuable metals in the cathode material of retired ternary lithium batteries, the present invention introduces micro-nano bubbles, which increases the interfacial contact area between the solvent and the material, significantly improves the mass transfer rate and leaching speed of metal ions, shortens the processing time, and improves the overall process efficiency.

[0024] (4) In the selective leaching process of valuable metals in the cathode material of retired ternary lithium batteries, the present invention can complete the leaching of metal ions at a lower temperature (60-80℃) and a shorter leaching time (30-60 min), which reduces energy consumption and meets the requirements of energy conservation and environmental protection. Attached Figure Description

[0025] Figure 1 This is a process flow diagram of selective leaching of valuable metals in the cathode material of retired ternary lithium batteries involved in the embodiments of the present invention. Detailed Implementation

[0026] To facilitate understanding of the present invention, the present invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0027] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0028] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0029] The retired ternary lithium battery cathode materials treated in the following examples and comparative examples are from the same batch of materials, with the chemical formula Li(Ni) 0.5 Co 0.2 Mn 0.3 )O2.

[0030] Example 1:

[0031] A selective leaching method for valuable metals in retired ternary lithium battery cathode materials according to the present invention is shown in the process flow diagram below. Figure 1 As shown, it includes the following steps:

[0032] (1) The retired ternary lithium battery was discharged, disassembled, crushed and sieved to obtain positive electrode material powder with a D50 of 15 μm through a 200-mesh sieve.

[0033] (2) The positive electrode material powder was mechanically vibrated at a frequency of 30 Hz for 10 min;

[0034] (3) Take 10 g of the positive electrode material powder after mechanical grinding in step (2) and mix it with 150 g of DES solvent (composed of choline chloride, citric acid and ethylene glycol in a mass ratio of 2:1:1). Stir and leach at 60℃ and 600 rpm. At the beginning of leaching, adjust the pH of the solution system to 3 and add 5% of the initial DES solvent mass of ethylenediaminetetraacetic acid every 10 min. At the 10 min, adjust the pH to 5 and add 20% of the initial DES solvent mass of ethylenediaminetetraacetic acid. Micro-nano bubbles are continuously introduced during the leaching process at a bubble introduction rate of 10 ml / min and a diameter of 10~50 nm. The leaching process lasts for 30 min. Then, solid-liquid separation is performed, the leachate is collected and the metal leaching rate is detected by ICP-OES. The results are shown in Table 1. 1 Ni 1 Co 1 Mn 1 As shown;

[0035] (4) The leachate obtained in step (3) was subjected to selective precipitation by adjusting the conditions in sequence. The pH was adjusted to 8 and the temperature to 30°C, and solid sodium carbonate was added to precipitate lithium carbonate. The pH was adjusted to 6 and the temperature to 30°C, and hydrogen sulfide gas with a flow rate of 0.5 L / min was introduced to precipitate nickel sulfide. The pH was adjusted to 9 and the temperature to 50°C, and solid sodium hydroxide was added to precipitate cobalt hydroxide. The pH was adjusted to 8 and the temperature to 30°C, and solid sodium hypobromite was added to precipitate manganese dioxide. The reagents used to adjust the pH were 0.5 mol / L sodium hydroxide solution and 3% sulfuric acid solution. Then, 65% ethylenediaminetetraacetic acid (EDTA) was added to the residual solution. This solution was used as the new DES solvent. The valuable metals in the cathode material of the retired ternary lithium battery were leached according to the above steps (1), (2) and (3). The metal leaching rate of the leachate was detected by ICP-OES. The results are shown in Table 1. 2 Ni 2 Co 2 Mn 2 As shown.

[0036] Example 2:

[0037] A selective leaching method for valuable metals in retired ternary lithium battery cathode materials according to the present invention is shown in the process flow diagram below. Figure 1 As shown, it includes the following steps:

[0038] (1) The retired ternary lithium battery was discharged, disassembled, crushed and sieved to obtain positive electrode material powder with a D50 of 15 μm through a 200-mesh sieve.

[0039] (2) The positive electrode material powder was mechanically vibrated at a frequency of 50 Hz for 30 min;

[0040] (3) Take 10 g of the positive electrode material powder after mechanical grinding in step (2) and mix it with 250 g of DES solvent (composed of alanine, oxalic acid and polyethylene glycol in a mass ratio of 3:2:1). Stir and leach at 80℃ and 800 rpm. At the beginning of leaching, adjust the pH of the solution system to 4 and add sodium dodecyl sulfate (10% of the initial DES solvent mass) every 20 min. At the 20 min, adjust the pH to 6 and add pyridinecarboxylic acid (30% of the initial DES solvent mass). Micro-nano bubbles are continuously introduced during the leaching process at a rate of 20 ml / min. The micro-nano bubble diameter is 10~50 nm. The leaching process lasts for 60 min. Then, solid-liquid separation is performed, the leachate is collected, and the metal leaching rate is detected by ICP-OES. The results are shown in Table 1. 1 Ni 1 Co 1 Mn 1 As shown;

[0041] (4) The leachate obtained in step (3) was subjected to selective precipitation by adjusting the conditions in sequence. The pH was adjusted to 8 and the temperature to 30°C, and solid sodium carbonate was added to precipitate lithium carbonate. The pH was adjusted to 6 and the temperature to 30°C, and hydrogen sulfide gas with a flow rate of 0.5 L / min was introduced to precipitate nickel sulfide. The pH was adjusted to 9 and the temperature to 50°C, and solid sodium hydroxide was added to precipitate cobalt hydroxide. The pH was adjusted to 8 and the temperature to 30°C, and solid sodium hypobromite was added to precipitate manganese dioxide. The reagents used to adjust the pH were 0.5 mol / L sodium hydroxide solution and 3% sulfuric acid solution. Then, 65% ethylenediaminetetraacetic acid (EDTA) was added to the residual solution. This solution was used as the new DES solvent. The valuable metals in the cathode material of the retired ternary lithium battery were leached according to the above steps (1), (2) and (3). The metal leaching rate of the leachate was detected by ICP-OES. The results are shown in Table 1. 2 Ni 2 Co 2 Mn 2 As shown.

[0042] Example 3:

[0043] A selective leaching method for valuable metals in retired ternary lithium battery cathode materials according to the present invention is shown in the process flow diagram below. Figure 1 As shown, it includes the following steps:

[0044] (1) The retired ternary lithium battery was discharged, disassembled, crushed and sieved to obtain positive electrode material powder with a D50 of 15 μm through a 200-mesh sieve.

[0045] (2) The positive electrode material powder was mechanically vibrated at a frequency of 30 Hz for 30 min;

[0046] (3) Take 10 g of the positive electrode material powder after mechanical grinding in step (2) and mix it with 250 g of DES solvent (composed of glycine, lactic acid and sorbitol in a mass ratio of 2:1:1). Stir and leach at 60℃ and 800 rpm. At the beginning of leaching, adjust the pH to 3 and add 5% sodium citrate of the initial DES solvent mass every 20 min. At the 20 min, adjust the pH to 5 and add 20% sodium dithiocarbamate of the initial DES solvent mass. Micro-nano bubbles are continuously introduced during the leaching process at a bubble introduction rate of 10 ml / min and a diameter of 10~50 nm. The leaching process lasts for 60 min. Then, solid-liquid separation is performed, the leachate is collected and the metal leaching rate is detected by ICP-OES. The results are shown in Table 1. 1 Ni 1 Co 1 Mn 1 As shown;

[0047] (4) The leachate obtained in step (3) was subjected to selective precipitation by adjusting the conditions in sequence. The pH was adjusted to 8 and the temperature to 30°C, and solid sodium carbonate was added to precipitate lithium carbonate. The pH was adjusted to 6 and the temperature to 30°C, and hydrogen sulfide gas with a flow rate of 0.5 L / min was introduced to precipitate nickel sulfide. The pH was adjusted to 9 and the temperature to 50°C, and solid sodium hydroxide was added to precipitate cobalt hydroxide. The pH was adjusted to 8 and the temperature to 30°C, and solid sodium hypobromite was added to precipitate manganese dioxide. The reagents used to adjust the pH were 0.5 mol / L sodium hydroxide solution and 3% sulfuric acid solution. Then, 65% ethylenediaminetetraacetic acid (EDTA) was added to the residual solution. This solution was used as the new DES solvent. The valuable metals in the cathode material of the retired ternary lithium battery were leached according to the above steps (1), (2) and (3). The metal leaching rate of the leachate was detected by ICP-OES. The results are shown in Table 1. 2 Ni 2 Co 2 Mn 2 As shown.

[0048] Example 4:

[0049] A selective leaching method for valuable metals in retired ternary lithium battery cathode materials according to the present invention is shown in the process flow diagram below. Figure 1 As shown, it includes the following steps:

[0050] (1) The retired ternary lithium battery was discharged, disassembled, crushed and sieved to obtain positive electrode material powder with a D50 of 15 μm through a 200-mesh sieve.

[0051] (2) The positive electrode material powder was mechanically vibrated at a frequency of 50 Hz for 10 min;

[0052] (3) Take 10 g of the positive electrode material powder after mechanical grinding in step (2) and mix it with 150 g of DES solvent (composed of choline chloride, lactic acid and ethylene glycol in a mass ratio of 3:2:1). Stir and leach at 80℃ and 800 rpm. At the beginning of leaching, adjust the pH to 4 and add 10% of the initial DES solvent mass of ethylenediaminetetraacetic acid every 10 min. At the 10th min, adjust the pH to 6 and add 30% of the initial DES solvent mass of pyridinecarboxylic acid. Micro-nano bubbles are continuously introduced during the leaching process. The bubble introduction rate is 20 ml / min and the diameter is 10~50 nm. The leaching process lasts for 30 min. Then, solid-liquid separation is performed, the leachate is collected and the metal leaching rate is detected by ICP-OES. The results are shown in Table 1. 1 Ni 1 Co 1 Mn 1 As shown;

[0053] (4) The leachate obtained in step (3) was subjected to selective precipitation by adjusting the conditions in sequence. The pH was adjusted to 8 and the temperature to 30°C, and solid sodium carbonate was added to precipitate lithium carbonate. The pH was adjusted to 6 and the temperature to 30°C, and hydrogen sulfide gas with a flow rate of 0.5 L / min was introduced to precipitate nickel sulfide. The pH was adjusted to 9 and the temperature to 50°C, and solid sodium hydroxide was added to precipitate cobalt hydroxide. The pH was adjusted to 8 and the temperature to 30°C, and solid sodium hypobromite was added to precipitate manganese dioxide. The reagents used to adjust the pH were 0.5 mol / L sodium hydroxide solution and 3% sulfuric acid solution. Then, 65% ethylenediaminetetraacetic acid (EDTA) was added to the residual solution. This solution was used as the new DES solvent. The valuable metals in the cathode material of the retired ternary lithium battery were leached according to the above steps (1), (2) and (3). The metal leaching rate of the leachate was detected by ICP-OES. The results are shown in Table 1. 2 Ni 2 Co 2 Mn 2 As shown.

[0054] Comparative Example 1:

[0055] The selective leaching method for valuable metals in the cathode material of retired ternary lithium batteries in this comparative example includes the following steps:

[0056] (1) The retired ternary lithium battery was discharged, disassembled, crushed and sieved to obtain positive electrode material powder with a D50 of 15 μm through a 200-mesh sieve.

[0057] (2) The positive electrode material powder was mechanically vibrated at a frequency of 90 Hz for 10 min;

[0058] (3) Take 10 g of the positive electrode material powder after mechanical grinding in step (2) and mix it with 60 g of DES solvent (composed of choline chloride, citric acid and ethylene glycol in a mass ratio of 4:5:1). Stir and leach at 120℃ and 800 rpm. At the beginning of leaching, adjust the pH to 9 and add 1% of the initial DES solvent mass of ethylenediaminetetraacetic acid every 10 min. At the 10th min, adjust the pH to 4 and add 5% of the initial DES solvent mass of ethylenediaminetetraacetic acid. Micro-nano bubbles are continuously introduced during the leaching process at a bubble introduction rate of 5 ml / min. The leaching process lasts for 30 min. Then, solid-liquid separation is performed, the leachate is collected and the metal leaching rate is detected by ICP-OES. The results are shown in Table 1. 1 Ni 1 Co 1 Mn 1 As shown;

[0059] (4) The leachate obtained in step (3) was subjected to selective precipitation by adjusting the conditions in sequence. The pH was adjusted to 8 and the temperature to 30°C, and solid sodium carbonate was added to precipitate lithium carbonate. The pH was adjusted to 6 and the temperature to 30°C, and hydrogen sulfide gas with a flow rate of 0.5 L / min was introduced to precipitate nickel sulfide. The pH was adjusted to 9 and the temperature to 50°C, and solid sodium hydroxide was added to precipitate cobalt hydroxide. The pH was adjusted to 8 and the temperature to 30°C, and solid sodium hypobromite was added to precipitate manganese dioxide. The reagents used to adjust the pH were 0.5 mol / L sodium hydroxide solution and 3% sulfuric acid solution. Then, 65% ethylenediaminetetraacetic acid (EDTA) was added to the residual solution. This solution was used as the new DES solvent. The valuable metals in the cathode material of the retired ternary lithium battery were leached according to the above steps (1), (2) and (3). The metal leaching rate of the leachate was detected by ICP-OES. The results are shown in Table 1. 2 Ni 2 Co 2 Mn 2 As shown.

[0060] Comparative Example 2:

[0061] The only difference between this comparative example and Example 1 is that micro-nano bubbles are not introduced during the leaching process in step (3). Other processes and parameters are the same as in Example 1.

[0062] Comparative Example 3:

[0063] The only difference between this comparative example and Example 1 is that in the leaching process of step (3), the DES solvent used is composed of choline chloride and hydrogen peroxide in a 1:1 mass ratio, substance D is zinc chloride, and substance E is tartaric acid. Other processes and parameters are consistent with those of Example 1.

[0064] Comparative Example 4:

[0065] The only difference between this comparative example and Example 1 is that ethylenediaminetetraacetic acid is not introduced during the leaching process in step (3). Other processes and parameters are the same as in Example 1.

[0066] Comparative Example 5:

[0067] The only difference between this comparative example and Example 1 is that ethylenediamine is not introduced during the leaching process in step (3). The other processes and parameters are the same as in Example 1.

[0068] Comparative Example 6:

[0069] The only difference between this comparative example and Example 1 is that the pH of the system is not adjusted during the leaching process in step (3). Other processes and parameters are the same as in Example 1.

[0070] Table 1. Leaching rates of various metal elements in Examples 1-4 and Comparative Examples 1-3

[0071]

[0072] In Examples 1-4, the leaching rates of the four metals were generally high, especially cobalt, which had a leaching rate approaching 99.5%. The leaching rates of other metals, such as nickel, manganese, and lithium, also remained above 95%. This indicates that Examples 1-4 effectively optimized the parameter settings, process flow, and reagent selection, ensuring efficient leaching. By rationally controlling the selection and ratio of DES solvents and process parameters, and employing micro / nano bubble assistance, all target metals could be stably recovered, and the leaching effect was quite ideal in both steps.

[0073] In contrast, the leaching effects of Comparative Examples 1-6 were significantly worse, especially Comparative Example 3, which recovered almost no metal. The leaching rate of Comparative Example 1 had dropped sharply, possibly due to unreasonable process parameter settings, resulting in low metal leaching efficiency. The leaching effect of Comparative Example 2 further deteriorated, possibly due to the lack of micro / nano bubble-assisted process. The worst Comparative Example 3 was likely due to unsuitable reagent selection, resulting in almost zero leaching effect. Judging from the leaching effects of Comparative Examples 4-6, the addition of substances D and E and the reasonable pH control in the process of this application can maintain solvent activity during the leaching process, thereby ensuring the recovery rate of valuable metals.

[0074] In summary, this invention, through the rational selection of DES solvent and the appropriate combination of process parameters, combined with micro-nano bubble technology, successfully improves the leaching efficiency of metals in retired ternary lithium batteries. Furthermore, through meticulous reagent design, it achieves the recycling of DES solvent, which has significant advantages over traditional processes. At the same time, it makes the economic value and environmental sustainability of the recycling process promising.

Claims

1. A method for selective leaching of valuable metals in the cathode material of retired ternary lithium batteries, characterized in that, Includes the following steps: (1) Discharge, disassemble, crush and sieve retired ternary lithium batteries to obtain positive electrode material powder; (2) The positive electrode material powder is mechanically vibrated and milled; (3) The positive electrode material powder obtained by mechanical vibration milling is mixed with DES solvent and stirred for leaching and solid-liquid separation to obtain a solution rich in metal ions; wherein, the DES solvent includes substance A, substance B and substance C in a mass ratio of (2~3):(1~2):1, substance A is one or more of choline chloride, alanine and glycine, substance B is one or more of citric acid, oxalic acid and lactic acid, and substance C is one or more of ethylene glycol, polyethylene glycol and sorbitol; during the leaching process, substance D is added to the mixed system every 10 min, substance D is one or more of ethylenediaminetetraacetic acid, sodium dodecyl sulfate and sodium citrate; 10~20 min after the start of leaching, substance E is added to the mixed system, substance E is one or more of ethylenediamine, pyridinecarboxylic acid and sodium dithiocarbamate.

2. The selective leaching method for valuable metals in the cathode material of retired ternary lithium batteries as described in claim 1, characterized in that, In step (3), the mass of substance D added is 5% to 10% of the mass of DES solvent.

3. The selective leaching method for valuable metals in the cathode material of retired ternary lithium batteries as described in claim 1, characterized in that, In step (3), the mass of substance E added is 20% to 30% of the mass of DES solvent.

4. The selective leaching method for valuable metals in the cathode material of retired ternary lithium batteries as described in claim 1, characterized in that, In step (3), the pH of the system is first adjusted to 3-4 during the leaching process and held for 10-20 minutes. Then the pH is adjusted to 5-6 and substance E is added.

5. The selective leaching method for valuable metals in the cathode material of retired ternary lithium batteries as described in claim 1, characterized in that, In step (3), the mass ratio of the DES solvent to the cathode material powder is (15~25):

1.

6. The selective leaching method for valuable metals in the cathode material of retired ternary lithium batteries as described in claim 1, characterized in that, In step (3), the leaching temperature is 60~80℃, the leaching time is 30~60 min, and the stirring rate during the leaching process is 600~800 rpm.

7. The selective leaching method for valuable metals in the cathode material of retired ternary lithium batteries as described in any one of claims 1 to 6, characterized in that, In step (3), micro-nano bubbles are introduced into the mixing system during the leaching process.

8. The selective leaching method for valuable metals in the cathode material of retired ternary lithium batteries as described in claim 7, characterized in that, In step (3), the diameter of the micro-nano bubbles is 10~50 nm, and the introduction rate of the micro-nano bubbles is 10~20 mL / min.

9. The selective leaching method for valuable metals in the cathode material of retired ternary lithium batteries as described in any one of claims 1 to 6, characterized in that, The particle size D50 of the positive electrode material powder is 15~20 μm; the mechanical vibration grinding frequency is 30~50Hz, and the vibration grinding time is 10~30 min.

10. The selective leaching method for valuable metals in the cathode material of retired ternary lithium batteries as described in any one of claims 1 to 6, characterized in that, The metal ion-rich solution obtained after step (3) is subjected to stepwise selective precipitation to obtain metal salt products. Substance D is added to the residual solution to restore its activity and achieve recycling. The mass of substance D added is 60% to 70% of the mass of the residual solution.

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