Selective leaching method for valuable metal in retired ternary lithium battery positive electrode material

Abstract

The invention belongs to the technical field of resource recycling, and discloses a selective leaching method for valuable metal in a decommissioned ternary lithium battery positive electrode material, which comprises the following steps: discharging, disassembling, crushing, screening and mechanically shaking and milling a decommissioned ternary lithium battery, mixing the obtained positive electrode material powder with a DES solvent, stirring and leaching, and carrying out solid-liquid separation, so as to obtain the valuable metal in the decommissioned ternary lithium battery positive electrode material. A solution rich in metal ions is obtained; in the leaching process, a substance D is added into a mixed system every 10 min, and the substance D is one or more of ethylenediaminetetraacetic acid, lauryl sodium sulfate and sodium citrate; a substance E is added 10-20 min after leaching is started, and the substance E is one or more of ethanediamine, picolinic acid and sodium dithiocarbamate. In the leaching process, by adding the DES solvent and combining with the substance E, the complexing selectivity on metal ions under different pH values is enhanced, so that step-by-step leaching of nickel, cobalt, manganese and lithium is realized, and the leaching efficiency is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of resource recycling, and in particular relates to a method for selectively leaching valuable metals in retired ternary lithium battery positive electrode materials based on a self-healing DES solvent and a micro-nano bubble composite process. Background Art

[0002] With the rapid development of electric vehicles and energy storage systems, a large number of retired ternary lithium batteries need to be recycled. The positive electrode materials of ternary lithium batteries are rich in metals such as nickel, cobalt, manganese and lithium. The recycling of these metal resources can not only reduce resource waste and environmental pollution, but also effectively reduce the cost of manufacturing new batteries. The current recycling technology mainly uses low eutectic solvents or acidic solvents to leach metal ions from battery materials, but the existing methods have the following disadvantages: some low eutectic solvents are prone to generate metal oxalate precipitation, which reduces the leaching rate of metals and cannot achieve efficient separation; the traditional leaching process is inefficient and time-consuming, and the solvent is difficult to recycle after leaching, which increases the processing cost; the electrode materials regenerated after metal leaching usually have insufficient conductivity and perform poorly in terms of battery cycle performance.

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

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

[0005] In order to solve the above technical problems, the technical solution proposed by the present invention is: (1) Discharging, disassembling, crushing and screening retired ternary lithium batteries to obtain positive electrode material powder; (2) mechanically vibrating and grinding the positive electrode material powder; (3) Mixing the positive electrode material powder after mechanical vibration grinding with DES solvent for stirring 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, wherein 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, adding substance D to the mixed system every 10 minutes, wherein substance D is one or more of ethylenediaminetetraacetic acid, sodium dodecyl sulfate and sodium citrate; and adding substance E to the mixed system 10-20 minutes after the start of leaching, wherein substance E is one or more of ethylenediamine, picolinic acid and sodium dithiocarbamate.

[0006] In the above-mentioned method for selectively leaching valuable metals from retired ternary lithium battery positive electrode materials, preferably, in step (3), the added mass of the substance D is 5% to 10% of the mass of the DES solvent.

[0007] In the above-mentioned method for selectively leaching valuable metals from the retired ternary lithium battery positive electrode material, preferably, in step (3), the added mass of the substance E is 20% to 30% of the mass of the self-healing DES solvent.

[0008] The above-mentioned method for selective leaching of valuable metals in the positive electrode material of retired ternary lithium batteries, preferably, during the leaching process, acidic or alkaline regulators are added in stages to control the pH of the solvent to achieve selective leaching of nickel, cobalt, manganese and lithium. The system pH is first adjusted to 3-4 to leach lithium for 10-20 min, and then the pH is adjusted to 5-6 and substance E is added to enhance the selective leaching of the three elements of nickel, cobalt and manganese.

[0009] In the process of the present invention, substance A in the DES solvent serves as a solvent base component, and together with substance B and substance C, forms a low eutectic solvent system, and its hydrogen bond donor / acceptor effect enhances the solvent's ability to complex metal ions; substance B improves the complexation of metals such as nickel, cobalt, and manganese by providing organic acid radical ions, and enhances the stability of the solvent; the addition of substance C effectively reduces the viscosity of the solvent, enhances the permeability of the solvent and the mass transfer efficiency of metal ions. During the leaching process, substance E is added, and substance E is a complexation enhancer, which plays an important role in the selective complexation of specific metal ions, making the leaching process more selective and efficient, especially in the enrichment process of metals such as nickel, cobalt, and manganese; substance D, as a self-healing component, can ensure the activity of the solvent even if it is supplemented, prevent the solvent from aging or performance attenuation during the leaching process, and ensure the recycling of the solvent.

[0010] In the above-mentioned method for selectively leaching valuable metals in the retired ternary lithium battery positive electrode material, preferably, in step (3), the mass ratio of the DES solvent to the positive electrode material powder is (15~25):1.

[0011] In the above-mentioned method for selectively leaching valuable metals in the retired ternary lithium battery positive electrode material, preferably, in step (3), the leaching temperature is 60~80°C, the leaching time is 30~60 min, and the stirring rate during the leaching process is 600~800rpm.

[0012] In the above-mentioned method for selectively leaching valuable metals in the retired ternary lithium battery positive electrode material, preferably, in step (3), micro-nano bubbles are introduced into the mixed system during the leaching process.

[0013] The introduction of micro-nano bubbles is mainly to enhance the contact efficiency between the solvent and the material. Micro-nano bubbles have a small diameter and a large specific surface area, which can form a uniform distribution in the liquid phase, thereby increasing the gas-liquid interface area; when micro-nano bubbles are attached to the surface of the material, local turbulence can be generated, accelerating the mass transfer process between the solvent and the material; in addition, when micro-nano bubbles collapse in the solution, they will produce tiny shear forces and ultrasonic effects, which will help the rapid desorption and dissolution of metal ions, thereby significantly improving the metal leaching rate and efficiency.

[0014] In the above-mentioned method for selective leaching of valuable metals in the positive electrode 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.

[0015] In the above-mentioned method for selective leaching of valuable metals in the positive electrode material of retired ternary lithium batteries, preferably, the particle size D50 of the positive electrode material powder is 15~20 μm; the mechanical vibration frequency is 30~50 Hz, and the vibration time is 10~30 min. The purpose of vibration is to form nano-scale cracks and porous structures on the surface of the material, significantly increase the specific surface area, and enhance the contact between the solvent and the material; this structure helps the metal ions to dissolve more easily, and provides sites for the attachment of micro-nano bubbles, further optimizing the mass transfer effect, thereby improving the leaching efficiency.

[0016] In the above-mentioned method for selectively leaching valuable metals in the positive electrode material of retired ternary lithium batteries, preferably, the metal ion-rich solution obtained after step (3) is subjected to step-by-step selective precipitation to obtain a metal salt product, and substance D is added to the residual solution to restore its activity for recycling, wherein the added mass of substance D is 60% to 70% of the mass of the residual solution.

[0017] Compared with the prior art, the present invention has the following beneficial effects: (1) In the selective leaching process of valuable metals in the retired ternary lithium battery positive electrode material, the present invention enhances the complexing selectivity of metal ions at different pH values ​​by adding DES solvent and combining with substance E, thereby realizing step-by-step leaching of nickel, cobalt, manganese and lithium, and improving the leaching efficiency.

[0018] (2) In the selective leaching process of valuable metals in the retired ternary lithium battery positive electrode material, the activity of the solvent system is continuously restored by adding substance D, which prevents the solvent from aging or performance degradation during the leaching process, and also ensures the multiple recycling of the solvent, reduces solvent loss, reduces process costs, and enhances environmental protection.

[0019] (3) In the process of selective leaching of valuable metals in the positive electrode materials of retired ternary lithium batteries, the present invention introduces micro-nano bubbles, 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.

[0020] (4) In the selective leaching process of valuable metals in the retired ternary lithium battery positive electrode material, the present invention can complete the leaching of metal ions at a lower temperature (60-80°C) and a shorter leaching time (30-60 min), thereby reducing energy consumption requirements and meeting the requirements of energy conservation and environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a process flow chart for selective leaching of valuable metals in retired ternary lithium battery positive electrode materials involved in an embodiment of the present invention. DETAILED DESCRIPTION

[0022] In order to facilitate the understanding of the present invention, the present invention will be described more comprehensively and meticulously below in conjunction with the accompanying drawings and preferred embodiments of the present invention, but the protection scope of the present invention is not limited to the following specific embodiments.

[0023] Unless otherwise defined, all professional terms used below have the same meanings as those generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0024] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0025] The retired ternary lithium battery positive electrode materials treated in the following examples and comparative examples are from the same batch of materials, and their chemical formula is Li(Ni 0.5 Co 0.2 Mn 0.3 )O2.

[0026] Embodiment 1: A selective leaching method for valuable metals in the cathode material of retired ternary lithium batteries of the present invention, the process flow chart of which is as follows Figure 1 As shown, the following steps are included: (1) Discharging, disassembling, crushing and sieving retired ternary lithium batteries to obtain cathode material powder under a 200-mesh sieve with a D50 of 15 μm; (2) Mechanically vibrate the cathode material powder at a frequency of 30 Hz for 10 min; (3) Take 10 g of the positive electrode material powder after mechanical vibration 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), and stir and leach at 60°C and 600 rpm; at the beginning of leaching, the pH of the solution system is adjusted to 3, and 5% of the initial DES solvent mass of ethylenediaminetetraacetic acid is added every 10 min; at the 10th minute, the pH is adjusted to 5, and 20% of the initial DES solvent mass of ethylenediamine is added. During the leaching process, micro-nano bubbles are continuously introduced at a rate of 10 ml / min, and the diameter of the bubbles is 10~50 nm. The leaching process lasts for 30 min, followed by solid-liquid separation. 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; (4) The leachate obtained in step (3) was adjusted in turn for selective precipitation, the pH was adjusted to 8, the temperature was 30°C, and solid sodium carbonate was added to precipitate lithium carbonate; the pH was adjusted to 6, the temperature was 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, the temperature was 50°C, and solid sodium hydroxide was added to precipitate cobalt hydroxide; the pH was adjusted to 8, the temperature was 30°C, and solid sodium hypobromite was added to precipitate manganese dioxide, wherein the reagents used to adjust the pH were 0.5 mol / L sodium hydroxide solution and 3% sulfuric acid solution; then ethylenediaminetetraacetic acid accounting for 65% of the mass of the residual solution was added to the residual solution, and this solution was used as a new DES solvent, and the valuable metals in the retired ternary lithium battery positive electrode material were leached according to the above steps (1), (2) and (3), and 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 shown.

[0027] Embodiment 2: A selective leaching method for valuable metals in the cathode material of retired ternary lithium batteries of the present invention, the process flow chart of which is as follows Figure 1 As shown, the following steps are included: (1) Discharging, disassembling, crushing and sieving retired ternary lithium batteries to obtain cathode material powder under a 200-mesh sieve with a D50 of 15 μm; (2) Mechanically vibrate the cathode material powder at a frequency of 50 Hz for 30 min; (3) Take 10 g of the positive electrode material powder after mechanical vibration 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), and stir and leach at 80°C and 800 rpm; at the beginning of leaching, the pH of the solution system is adjusted to 4, and sodium dodecyl sulfate (10% of the initial DES solvent mass) is added every 20 min; at the 20th minute, the pH is adjusted to 6, and picolinic acid (30% of the initial DES solvent mass) is added; during the leaching process, micro-nano bubbles are continuously introduced at a rate of 20 ml / min, and the micro-nano diameter is 10~50 nm. The leaching process lasts for 60 min, followed by solid-liquid separation. 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; (4) The leachate obtained in step (3) was adjusted in turn for selective precipitation, the pH was adjusted to 8, the temperature was 30°C, and solid sodium carbonate was added to precipitate lithium carbonate; the pH was adjusted to 6, the temperature was 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, the temperature was 50°C, and solid sodium hydroxide was added to precipitate cobalt hydroxide; the pH was adjusted to 8, the temperature was 30°C, and solid sodium hypobromite was added to precipitate manganese dioxide, wherein the reagents used to adjust the pH were 0.5 mol / L sodium hydroxide solution and 3% sulfuric acid solution; then ethylenediaminetetraacetic acid accounting for 65% of the mass of the residual solution was added to the residual solution, and this solution was used as a new DES solvent, and the valuable metals in the retired ternary lithium battery positive electrode material were leached according to the above steps (1), (2) and (3), and 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 shown.

[0028] Embodiment 3: A selective leaching method for valuable metals in the cathode material of retired ternary lithium batteries of the present invention, the process flow chart of which is as follows Figure 1As shown, the following steps are included: (1) Discharging, disassembling, crushing and sieving retired ternary lithium batteries to obtain cathode material powder under a 200-mesh sieve with a D50 of 15 μm; (2) Mechanically vibrate the cathode material powder at a frequency of 30 Hz for 30 min; (3) Take 10 g of the positive electrode material powder after mechanical vibration 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), and stir and leach at 60°C and 800 rpm; at the beginning of leaching, adjust the pH to 3, and add sodium citrate at a mass ratio of 5% of the initial DES solvent every 20 min; at the 20th minute, adjust the pH to 5, and add sodium dithiocarbamate at a mass ratio of 20% of the initial DES solvent; during the leaching process, continuously introduce micro-nano bubbles at a rate of 10 ml / min and a diameter of 10~50 nm. The leaching process lasts for 60 min, followed by solid-liquid separation. Collect the leachate and use ICP-OES to detect the metal leaching rate. The results are shown in Table 1. 1 、Ni 1 、Co 1 , Mn 1 As shown; (4) The leachate obtained in step (3) was adjusted in turn for selective precipitation, the pH was adjusted to 8, the temperature was 30°C, and solid sodium carbonate was added to precipitate lithium carbonate; the pH was adjusted to 6, the temperature was 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, the temperature was 50°C, and solid sodium hydroxide was added to precipitate cobalt hydroxide; the pH was adjusted to 8, the temperature was 30°C, and solid sodium hypobromite was added to precipitate manganese dioxide, wherein the reagents used to adjust the pH were 0.5 mol / L sodium hydroxide solution and 3% sulfuric acid solution; then ethylenediaminetetraacetic acid accounting for 65% of the mass of the residual solution was added to the residual solution, and this solution was used as a new DES solvent, and the valuable metals in the retired ternary lithium battery positive electrode material were leached according to the above steps (1), (2) and (3), and 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 shown.

[0029] Embodiment 4: A selective leaching method for valuable metals in the cathode material of retired ternary lithium batteries of the present invention, the process flow chart of which is as follows Figure 1 As shown, the following steps are included: (1) Discharging, disassembling, crushing and sieving retired ternary lithium batteries to obtain cathode material powder under a 200-mesh sieve with a D50 of 15 μm; (2) Mechanically vibrate the cathode material powder at a frequency of 50 Hz for 10 min; (3) Take 10 g of the positive electrode material powder after mechanical vibration 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), and stir and leach at 80°C 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 minute, adjust the pH to 6, and add 30% of the initial DES solvent mass of picolinic acid; during the leaching process, continuously introduce micro-nano bubbles, the bubble introduction rate is 20 ml / min, and the diameter is 10~50 nm; the leaching process lasts for 30 min, followed by solid-liquid separation, collect the leachate and use ICP-OES to detect the metal leaching rate. The results are shown in Table 1. 1 、Ni 1 、Co 1 , Mn 1 As shown; (4) The leachate obtained in step (3) was adjusted in turn for selective precipitation, the pH was adjusted to 8, the temperature was 30°C, and solid sodium carbonate was added to precipitate lithium carbonate; the pH was adjusted to 6, the temperature was 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, the temperature was 50°C, and solid sodium hydroxide was added to precipitate cobalt hydroxide; the pH was adjusted to 8, the temperature was 30°C, and solid sodium hypobromite was added to precipitate manganese dioxide, wherein the reagents used to adjust the pH were 0.5 mol / L sodium hydroxide solution and 3% sulfuric acid solution; then ethylenediaminetetraacetic acid accounting for 65% of the mass of the residual solution was added to the residual solution, and this solution was used as a new DES solvent, and the valuable metals in the retired ternary lithium battery positive electrode material were leached according to the above steps (1), (2) and (3), and 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 shown.

[0030] Comparative Example 1: The method for selectively leaching valuable metals in the retired ternary lithium battery positive electrode material of this comparative example comprises the following steps: (1) Discharging, disassembling, crushing and sieving retired ternary lithium batteries to obtain cathode material powder under a 200-mesh sieve with a D50 of 15 μm; (2) Mechanically vibrate the cathode material powder at a frequency of 90 Hz for 10 min; (3) Take 10 g of the positive electrode material powder after mechanical vibration 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), and stir and leach at 120°C 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 minute, adjust the pH to 4, and add 5% of the initial DES solvent mass of ethylenediamine; during the leaching process, continuously introduce micro-nano bubbles, and the bubble introduction rate is 5 ml / min; the leaching process lasts for 30 min, followed by solid-liquid separation, collect the leachate and use ICP-OES to detect the metal leaching rate. The results are shown in Table 1. 1 、Ni 1 、Co 1 , Mn 1 As shown; (4) The leachate obtained in step (3) was adjusted in turn for selective precipitation, the pH was adjusted to 8, the temperature was 30°C, and solid sodium carbonate was added to precipitate lithium carbonate; the pH was adjusted to 6, the temperature was 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, the temperature was 50°C, and solid sodium hydroxide was added to precipitate cobalt hydroxide; the pH was adjusted to 8, the temperature was 30°C, and solid sodium hypobromite was added to precipitate manganese dioxide, wherein the reagents used to adjust the pH were 0.5 mol / L sodium hydroxide solution and 3% sulfuric acid solution; then ethylenediaminetetraacetic acid accounting for 65% of the mass of the residual solution was added to the residual solution, and this solution was used as a new DES solvent, and the valuable metals in the retired ternary lithium battery positive electrode material were leached according to the above steps (1), (2) and (3), and 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 shown.

[0031] Comparative Example 2: The difference between this comparative example and Example 1 is that micro-nano bubbles are not introduced during the leaching process in step (3), and other processes and parameters are consistent with Example 1.

[0032] Comparative Example 3: The difference between this comparative example and Example 1 is that in the leaching process in step (3), the DES solvent used is composed of choline chloride and hydrogen peroxide in a mass ratio of 1:1, substance D is zinc chloride, and substance E is tartaric acid. Other processes and parameters are consistent with Example 1.

[0033] Comparative Example 4: The difference between this comparative example and Example 1 is that EDTA is not introduced during the leaching process in step (3), and other processes and parameters are consistent with those in Example 1.

[0034] Comparative Example 5: The difference between this comparative example and Example 1 is that ethylenediamine is not introduced during the leaching process in step (3), and other processes and parameters are consistent with Example 1.

[0035] Comparative Example 6: The difference between this comparative example and Example 1 is that the pH of the system is not regulated during the leaching process in step (3), and other processes and parameters are consistent with Example 1.

[0036] Table 1 Leaching rate of each metal element in Examples 1-4 and Comparative Examples 1-3

[0037] In Examples 1-4, the leaching rates of the four metals are generally high, especially the leaching rate of cobalt is close to 99.5%, and the leaching rates of other metals such as nickel, manganese and lithium are also maintained at more than 95%. This shows that Examples 1-4 have been effectively optimized in parameter setting, process flow and reagent selection to ensure the efficient leaching process. By reasonably controlling the DES solvent selection and ratio, process parameters, and using micro-nano bubbles to assist, all target metals can be stably recovered, and the leaching effect is relatively ideal in the two-step leaching.

[0038] In contrast, the leaching effects of Comparative Examples 1-6 are significantly poor, especially Comparative Example 3, where almost no metal is recovered. The leaching rate of Comparative Example 1 has dropped significantly, which may be due to the unreasonable setting of process parameters, resulting in low metal leaching efficiency; the leaching effect of Comparative Example 2 has further deteriorated, which may be due to the lack of micro-nano bubble auxiliary process; the worst Comparative Example 3 may be due to the improper selection of reagents, resulting in almost zero leaching effect; from the leaching effects of Comparative Examples 4-6, the addition of substance D and substance E and the reasonable regulation of pH in the process of this application can maintain the activity of the solvent during the leaching process, thereby ensuring the recovery rate of valuable metals.

[0039] In summary, the present invention successfully improves the leaching efficiency of metals in retired ternary lithium batteries by rationally selecting DES solvent and rationally matching process parameters, combined with micro-nano bubble technology, and realizes the recycling of DES solvent through sophisticated reagent design. It has obvious advantages over traditional processes, and at the same time, it makes the economic value and environmental sustainability of the recycling process have broad development prospects.

Claims

1. A method for selectively leaching valuable metals from retired ternary lithium battery positive electrode materials, characterized in that: The following steps are involved: (1) Discharging, disassembling, crushing and screening retired ternary lithium batteries to obtain positive electrode material powder; (2) mechanically vibrating and grinding the positive electrode material powder; (3) The positive electrode material powder obtained by mechanical vibration grinding is mixed with a DES solvent for stirring leaching and solid-liquid separation to obtain a solution rich in metal ions; wherein the DES solvent comprises a substance A, a substance B and a substance C in a mass ratio of (2-3):(1-2):1, wherein the substance A is one or more of choline chloride, alanine and glycine, the substance B is one or more of citric acid, oxalic acid and lactic acid, and the substance C is one or more of ethylene glycol, polyethylene glycol and sorbitol; during the leaching process, a substance D is added to the mixed system every 10 minutes, wherein the substance D is one or more of ethylenediaminetetraacetic acid, sodium dodecyl sulfate and sodium citrate; and a substance E is added to the mixed system 10-20 minutes after the start of leaching, wherein the substance E is one or more of ethylenediamine, picolinic acid and sodium dithiocarbamate.

2. The selective leaching method of valuable metals in the retired ternary lithium battery positive electrode material according to claim 1, characterized in that: In step (3), the added mass of the substance D is 5% to 10% of the mass of the DES solvent.

3. The selective leaching method of valuable metals in the retired ternary lithium battery positive electrode material according to claim 1, characterized in that: In step (3), the added mass of the substance E is 20% to 30% of the mass of the DES solvent.

4. The selective leaching method of valuable metals in the retired ternary lithium battery positive electrode material according to claim 1, characterized in that: In step (3), during the leaching process, the pH of the system is first adjusted to 3-4 for 10-20 min, and then the pH is adjusted to 5-6 and substance E is added.

5. The selective leaching method of valuable metals in the retired ternary lithium battery positive electrode material according to claim 1, characterized in that: In step (3), the mass ratio of the DES solvent to the positive electrode material powder is (15-25):

1.

6. The method for selectively leaching valuable metals from the retired ternary lithium battery positive electrode material according to claim 1, characterized in that: In step (3), the leaching temperature is 60-80°C, the leaching time is 30-60 min, and the stirring rate during the leaching process is 600-800 rpm.

7. The method for selectively leaching valuable metals from retired ternary lithium battery positive electrode materials according to any one of claims 1 to 6, characterized in that: In step (3), micro-nano bubbles are introduced into the mixed system during the leaching process.

8. The method for selectively leaching valuable metals from the retired ternary lithium battery positive electrode material according to 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 method for selectively leaching valuable metals from retired ternary lithium battery positive electrode materials according to 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 frequency is 30-50 Hz, and the vibration time is 10-30 min.

10. The method for selectively leaching valuable metals from retired ternary lithium battery positive electrode materials according to any one of claims 1 to 6, characterized in that: The metal ion-rich solution obtained after step (3) is selectively precipitated step by step to obtain a metal salt product, and substance D is added to the residual solution to restore its activity for recycling, wherein the added mass of the substance D is 60% to 70% of the mass of the residual solution.

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