18-crown-6 modified eutectic solvent, preparation method thereof and method for extracting cobalt and nickel from hydrochloric acid leaching solution of retired lithium ion battery

Abstract

The invention provides an 18-crown-6 modified eutectic solvent, a preparation method thereof and a method for extracting cobalt and nickel from hydrochloric acid leachate of a retired lithium ion battery, and belongs to the technical field of metal recovery. According to the invention, oxygen atoms in 18-crown-6 molecules have strong electron pairs and can form coordinate bonds with metal ions; meanwhile, the structure of the 18-crown-6 has relatively high selectivity and shows relatively strong affinity to cobalt and nickel; when the 18-crown-6 is combined with the metal ions, the solubility and the stability of the metal ions in the eutectic solvent can be remarkably improved, so that the extraction effect is optimized; in addition, the 18-crown-6 can also improve the stability of the eutectic solvent, enhance the hydrophobicity of the solvent, avoid the volatilization and dissolution problems of the solvent, and further improve the extraction selectivity and efficiency; 18-crown-6 is used for modifying and synthesizing a hydrophobic deep-eutectic solvent, and the metal extraction performance of the hydrophobic deep-eutectic solvent can be remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of metal recovery, and in particular to an 18-crown-6 modified deep eutectic solvent and a preparation method thereof, and a method for extracting cobalt and nickel from hydrochloric acid leachate of retired lithium-ion batteries. Background Art

[0002] With the shift to electric vehicles, the demand for lithium-ion batteries (LIBs) has increased significantly, raising the question of the green disposal of spent LIBs. Methods for recovering metals from LIBs include pyrometallurgy, direct recovery, and hydrometallurgy. Solvent extraction is an important metal recovery and separation technique within hydrometallurgy: this technique selectively extracts the metals into the organic phase by mixing a metal-rich aqueous phase with an immiscible organic phase and adding an extractant that forms a hydrophobic complex with the metal.

[0003] Currently, methods for extracting decommissioned lithium-ion batteries include: using carboxylic acid extractants to separate nickel, cobalt, and manganese through multi-stage countercurrent extraction; and using diketone extractants and organophosphine compounds to extract nickel, cobalt, and manganese through multi-stage countercurrent extraction. These methods all employ multi-stage extraction, which is not only complex but also consumes a lot of extractant because only one metal ion can be extracted at a time. Furthermore, the use of traditional extractants also poses the problem of solvent volatility, which places a heavy environmental burden.

[0004] Deep eutectic solvents (DESs) are considered a new type of green solvent due to their low cost, biodegradability, low toxicity and ease of preparation. The technical advantages of DESs, especially in metal selectivity, solvent recyclability and applicability to all surface cathode types, provide new ideas for the separation and recovery of metal ions. Since Abbott et al. first discovered DESs in 2003, researchers have developed a large number of hydrogen bond donors and hydrogen bond acceptors that can form DESs. However, current DESs can only be used for the extraction of a certain metal ion, such as the extraction of cobalt alone, the extraction of nickel alone, etc., and cannot achieve high-efficiency extraction of cobalt and nickel at the same time. Summary of the Invention

[0005] The present invention aims to provide a modified 18-crown-6 deep eutectic solvent, a preparation method thereof, and a method for extracting cobalt and nickel from hydrochloric acid leachate of retired lithium-ion batteries. The modified 18-crown-6 deep eutectic solvent provided by the present invention can efficiently extract cobalt and nickel in a single step.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The present invention provides an 18-crown-6 modified deep eutectic solvent, comprising 18-crown-6 and a deep eutectic solvent. The deep eutectic solvent comprises equimolar amounts of a hydrogen bond acceptor and a hydrogen bond donor, wherein the hydrogen bond acceptor is trioctyl phosphate or tributyl phosphate, and the hydrogen bond donor is lidocaine.

[0008] Preferably, the mass percentage of the 18-crown-6 in the 18-crown-6 modified deep eutectic solvent is 2.5-5%.

[0009] The present invention also provides a method for preparing the 18-crown-6 modified low eutectic solvent described in the above technical solution, comprising: mixing 18-crown-6 with a low eutectic solvent; the mixing temperature is 60 to 80°C.

[0010] Preferably, the mixing time is 0.5 to 1 hour.

[0011] The present invention also provides a method for extracting cobalt and nickel from hydrochloric acid leachate of retired lithium-ion batteries, comprising: mixing the hydrochloric acid leachate of retired lithium-ion batteries with an extraction solvent and then performing extraction to obtain an extraction phase and a raffinate phase; the extraction phase is an organic phase enriched in cobalt and nickel, and the raffinate phase is an aqueous phase enriched in lithium; the extraction solvent is the 18-crown-6 modified deep eutectic solvent described in the above technical solution or the 18-crown-6 modified deep eutectic solvent prepared by the preparation method described in the above technical solution.

[0012] Preferably, the volume ratio of the retired lithium-ion battery hydrochloric acid leachate to the extraction solvent is 1:(0.5-2.5).

[0013] Preferably, during the extraction, the pH value of the mixed solution is adjusted to 2-6.

[0014] Preferably, the extraction temperature is 20-100°C.

[0015] Preferably, the extraction time is 0.5 to 5 hours.

[0016] Preferably, the extraction further includes back extraction; the back extraction includes adding hydrochloric acid to the extraction phase and adding sodium carbonate aqueous solution to the residual phase.

[0017] The present invention provides an 18-crown-6 modified low eutectic solvent, comprising 18-crown-6 and a low eutectic solvent, wherein the low eutectic solvent comprises equimolar amounts of hydrogen bond acceptors and hydrogen bond donors, wherein the hydrogen bond acceptor is trioctyl phosphate or tributyl phosphate, and the hydrogen bond donor is lidocaine. The present invention utilizes the characteristics of high electron cloud density and strong extraction ability of the P=O group in trioctyl phosphate and tributyl phosphate, and has good extraction selectivity for cobalt and nickel; utilizes lidocaine's good coordination ability with divalent metal ions, and selectively reacts with cobalt and nickel ions in the aqueous phase; lidocaine can serve as a hydrogen bond donor to form a hydrogen bond network with trioctyl phosphate or tributyl phosphate, thereby increasing the viscosity and stability of the mixed solution, thereby obtaining a hydrophobic low eutectic solvent with a synergistic effect, avoiding the volatilization of the extractant and its dissolution in water during the extraction process, and achieving harmless, one-step, high-efficiency extraction of cobalt and nickel; utilizes the oxygen in the 18-crown-6 molecule to extract the cobalt and nickel. The atom has a strong electron pair and can form a coordination bond with the metal ion. At the same time, the structure of 18-crown-6 has high selectivity and shows a strong affinity for cobalt and nickel. When 18-crown-6 binds to these metal ions, it can significantly improve the solubility and stability of the metal ions in the deep eutectic solvent, thereby optimizing the extraction effect. In addition, 18-crown-6 can also improve the stability of the deep eutectic solvent, enhance the hydrophobicity of the solvent, avoid the volatilization and dissolution problems of the solvent, and further improve the selectivity and efficiency of the extraction. 18-crown-6 is used to modify and synthesize hydrophobic deep eutectic solvents, which can significantly improve their extraction performance for metals. The results of the examples show that the deep eutectic solvent provided by the present invention can be used to efficiently extract cobalt and nickel from the hydrochloric acid leachate of retired lithium-ion batteries in one step, with extraction efficiencies reaching 98.6% and 91%, respectively. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 18-crown-6, the deep eutectic solvent, and the 18-crown-6 modified deep eutectic solvent in Example 1 of the present invention;

[0019] Figure 2 These are the H NMR spectra of 18-crown-6, the deep eutectic solvent, and the 18-crown-6 modified deep eutectic solvent in Example 2 of the present invention. DETAILED DESCRIPTION

[0020] All raw materials of the present invention are not particularly limited in their sources and can be purchased from the market or prepared according to conventional methods well known to those skilled in the art.

[0021] The present invention provides an 18-crown-6 modified deep eutectic solvent, comprising 18-crown-6 and a deep eutectic solvent. The deep eutectic solvent comprises equimolar amounts of a hydrogen bond acceptor and a hydrogen bond donor, wherein the hydrogen bond acceptor is trioctyl phosphate or tributyl phosphate, and the hydrogen bond donor is lidocaine.

[0022] In the present invention, the mass percentage of 18-crown-6 in the 18-crown-6 modified deep eutectic solvent is preferably 2.5-5%, more preferably 3-4%. As one embodiment of the present invention, the mass percentage of 18-crown-6 in the 18-crown-6 modified deep eutectic solvent may be 2.5%, 3%, 3.5%, 4%, 4.5%, or 5%. The mass percentage of 18-crown-6 in the 18-crown-6 modified deep eutectic solvent within the above range is beneficial for 18-crown-6 to modify the deep eutectic solvent, further improving extraction efficiency.

[0023] In the present invention, the deep eutectic solvent includes a hydrogen bond acceptor, which is trioctyl phosphate or tributyl phosphate. In the present invention, trioctyl phosphate and tributyl phosphate contain P=O groups, have high electron cloud density, and exhibit good extraction selectivity for cobalt and nickel. Furthermore, trioctyl phosphate and tributyl phosphate can also act as hydrogen bond acceptors to form a hydrogen bond network with hydrogen bond donors, thereby increasing the viscosity and stability of the mixed solution and forming a hydrophobic deep eutectic solvent.

[0024] In the present invention, the deep eutectic solvent also includes a hydrogen bond donor, which is lidocaine. In the present invention, the lidocaine has good coordination ability with divalent metal ions and selectively reacts with divalent metal ions in the aqueous phase. At the same time, the molecular structure of lidocaine does not contain hydroxyl or carboxyl groups, which does not increase the hydrogen bonding force of the hydrogen bond acceptor itself, thus avoiding the inability to form a stable deep eutectic system due to the enhanced hydrogen bonding force of the hydrogen bond acceptor itself. The nitrogen in the lidocaine molecule forms a strong hydrogen bonding force with the hydrogen bond acceptor, forming a stable hydrogen bond network with the hydrogen bond acceptor's own hydrogen bonds and the lidocaine's own hydrogen bonds, thereby obtaining a stable deep eutectic solvent.

[0025] In the present invention, the hydrogen bond acceptor and the hydrogen bond donor are in equimolar amounts. Equimolar amounts of hydrogen bond acceptor and hydrogen bond donor are beneficial to improving the stability of the hydrogen bond network within the deep eutectic solvent, thereby improving hydrophobicity and reducing the dissolution consumption of the extractant during the extraction process.

[0026] The invention utilizes the characteristics of high electron cloud density and strong extraction ability of the P=O group in trioctyl phosphate and tributyl phosphate, and has good extraction selectivity for cobalt and nickel; utilizes the good coordination ability of lidocaine with metal ions and reacts with metal ions in the aqueous phase; lidocaine can serve as a hydrogen bond donor to form a hydrophobic deep eutectic solvent with trioctyl phosphate or tributyl phosphate with a synergistic effect, thereby avoiding the dissolution of the extractant in water during the extraction process; utilizes the strong electron pair of the oxygen atom in the 18-crown-6 molecule to form a coordination bond with the metal ion; and The structure of 18-crown-6 has high selectivity and shows strong affinity for cobalt and nickel; when 18-crown-6 combines with these metal ions, it can significantly improve the solubility and stability of metal ions in low eutectic solvents, thereby optimizing the extraction effect; in addition, 18-crown-6 can also improve the stability of low eutectic solvents, enhance the hydrophobicity of the solvent, avoid the volatilization and dissolution problems of the solvent, and further improve the selectivity and efficiency of the extraction; 18-crown-6 is used to modify the synthesis of hydrophobic low eutectic solvents, which can significantly improve their extraction performance for metals.

[0027] The present invention also provides a method for preparing the 18-crown-6 modified low eutectic solvent described in the above technical solution, comprising: mixing 18-crown-6 with a low eutectic solvent; the mixing temperature is 60 to 80°C.

[0028] The present invention has no particular requirements for the specific manner of mixing, and conventional mixing methods in the art can be used. As an embodiment of the present invention, stirring can be used during the mixing, and the stirring speed can be adjusted according to actual needs.

[0029] In the present invention, the mixing temperature is 60-80° C., preferably 60-70° C.; as one embodiment of the present invention, the mixing temperature can be 62° C., 65° C., 67° C., 72° C., 75° C., 77° C., or 78° C. A mixing temperature within the above range is conducive to the reaction between 18-crown-6 and the deep eutectic solvent to obtain an 18-crown-6 modified deep eutectic solvent.

[0030] In the present invention, the mixing time is preferably 0.5 to 1 hour, more preferably 0.6 to 0.8 hours. As one embodiment of the present invention, the mixing time can be 0.5 hours, 0.6 hours, 0.7 hours, 0.8 hours, 0.9 hours, or 1 hour. Mixing time within the above range is conducive to the reaction between 18-crown-6 and the deep eutectic solvent to obtain the 18-crown-6 modified deep eutectic solvent.

[0031] The present invention also provides a method for extracting cobalt and nickel from hydrochloric acid leachate of retired lithium-ion batteries, comprising: mixing the hydrochloric acid leachate of retired lithium-ion batteries with an extraction solvent and then performing extraction to obtain an extraction phase and a raffinate phase; the extraction phase is an organic phase enriched in cobalt and nickel, and the raffinate phase is an aqueous phase enriched in lithium; the extraction solvent is the 18-crown-6 modified deep eutectic solvent described in the above technical solution or the 18-crown-6 modified deep eutectic solvent prepared by the preparation method described in the above technical solution.

[0032] The present invention has no special requirements on the method of obtaining the hydrochloric acid leachate of retired lithium-ion batteries. The hydrochloric acid leachate of retired lithium-ion batteries obtained by conventional methods can be used. As an embodiment of the present invention, the ion concentration in the hydrochloric acid leachate of retired lithium-ion batteries can be Li + (1.15~1.41)g / L,Co 2+ (1.8~2.2)g / L, Ni 2+ (2.9~3.5)g / L.

[0033] In the present invention, the volume ratio of the hydrochloric acid leachate of retired lithium-ion batteries to the extraction solvent is preferably 1:(0.5-2.5), more preferably 1:1. As one embodiment of the present invention, the volume ratio of the hydrochloric acid leachate of retired lithium-ion batteries to the extraction solvent can be 1:0.8, 1:1.2, 1:1.5, 1:1.8, 1:2, or 1:2.2. A volume ratio of the hydrochloric acid leachate of retired lithium-ion batteries to the extraction solvent within the above range is conducive to the extraction of cobalt and nickel by the extractant, further improving the extraction efficiency of cobalt and nickel.

[0034] In the present invention, during the extraction, the pH value of the mixed solution is preferably adjusted to 2-6, more preferably 3-4. As one embodiment of the present invention, the pH value of the mixed solution may be 2, 3, 4, 5, or 6. A pH value of the mixed solution within the above range is conducive to the selective extraction of cobalt and nickel by the extractant, further improving the extraction efficiency.

[0035] In the present invention, the extraction temperature is preferably 20-100°C, more preferably 60-80°C. As one embodiment of the present invention, the extraction temperature can be 25°C, 35°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 80°C, 90°C, or 100°C. Extraction temperatures within the above ranges are beneficial to the selective extraction of cobalt and nickel by the extractant, further improving the extraction efficiency.

[0036] In the present invention, the extraction time is preferably 0.5 to 5 hours, more preferably 2 to 4 hours. As an embodiment of the present invention, the extraction time can be 0.6 hours, 1 hour, 1.5 hours, 2 hours, 3 hours, 4 hours, or 5 hours. Extraction time within the above range is conducive to the selective extraction of cobalt and nickel by the extractant, further improving the extraction efficiency.

[0037] The present invention has no particular requirements for the extraction apparatus; conventional extraction apparatuses in the art may be used. In an embodiment of the present invention, the extraction is performed in a constant temperature water ring liquid-liquid phase equilibrium kettle. As one embodiment of the present invention, stirring may be performed during the extraction, and the stirring speed may be 10 to 600 rpm.

[0038] In the present invention, the extraction preferably includes back extraction; the back extraction preferably includes adding hydrochloric acid to the extract phase and adding an aqueous sodium carbonate solution to the raffinate phase. In the present invention, the addition of hydrochloric acid to the extract phase allows the cobalt and nickel in the extract phase to be back extracted into the aqueous phase, thereby obtaining a CoCl2 and NiCl2 solution and a regenerated 18-crown-6 modified deep eutectic solvent. The addition of an aqueous sodium carbonate solution to the raffinate phase allows the cobalt and nickel in the extract phase to react with the lithium ions in the raffinate phase to form a Li2CO3 precipitate.

[0039] The present invention has no specific requirements for the amount of hydrochloric acid added, and the amount of hydrochloric acid added can be adjusted according to the amount of cobalt and nickel. As an embodiment of the present invention, the concentration of the hydrochloric acid can be 0.1 to 0.5 mol / L, and the volume ratio of the extract phase to the hydrochloric acid can be (1 to 3): (3 to 1).

[0040] The present invention has no particular requirements for the concentration of the sodium carbonate aqueous solution, and the concentration of the sodium carbonate aqueous solution well known in the art can be used. As an embodiment of the present invention, the concentration of the sodium carbonate aqueous solution can be 0.1 to 2 mol / L, and the volume ratio of the raffinate phase to the sodium carbonate aqueous solution can be 1:1.

[0041] The method for extracting cobalt and nickel from hydrochloric acid leachate of retired lithium-ion batteries provided by the present invention is easy to operate and low in cost. During the extraction process, almost no loss of the extractant in the aqueous solution occurs, thereby avoiding the problem of contaminating the aqueous solution. Cobalt and nickel in the hydrochloric acid leachate of retired lithium-ion batteries can be efficiently extracted. The obtained extract phase can be easily stripped to obtain a cobalt and nickel solution and a regenerated extractant, and at the same time, has a good enrichment effect on lithium ions. The 18-crown-6 modified low eutectic solvent provided by the present invention can be recycled and reused after extraction, effectively reducing production costs and improving resource utilization.

[0042] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions of the present invention. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0043] Example 1

[0044] A 18-crown-6 modified deep eutectic solvent, comprising 18-crown-6 and a deep eutectic solvent, wherein the mass percentage of 18-crown-6 in the 18-crown-6 modified deep eutectic solvent is 5%, recorded as 18-CE-6+HDES[TOP][Lid]; the deep eutectic solvent is composed of equimolar amounts of trioctyl phosphate (TOP) and lidocaine (Lid), recorded as HDES[TOP][Lid].

[0045] The preparation method of the 18-crown-6 modified deep eutectic solvent is as follows: 18-crown-6 and HDES[TOP][Lid] are mixed at 60° C. and stirred for 1 hour to obtain the 18-crown-6 modified deep eutectic solvent.

[0046] Example 2

[0047] A 18-crown-6 modified deep eutectic solvent comprises 18-crown-6 and a deep eutectic solvent, wherein the mass percentage of 18-crown-6 in the 18-crown-6 modified deep eutectic solvent is 5%, recorded as 18-CE-6+HDES[TBP][Lid]; the deep eutectic solvent comprises equimolar amounts of tributyl phosphate (TBP) and Lid, recorded as HDES[TBP][Lid].

[0048] The preparation method of the 18-crown-6 modified deep eutectic solvent is as follows: 18-crown-6 and HDES[TBP][Lid] are mixed at 60° C. and stirred for 1 hour to obtain the 18-crown-6 modified deep eutectic solvent.

[0049] Comparative Examples 1-2

[0050] A deep eutectic solvent composed of a hydrogen bond acceptor and a hydrogen bond donor in a molar ratio of 1:1, wherein the hydrogen bond acceptor is TBP or TOP and the hydrogen bond donor is Lid, denoted as HDES[TOP][Lid] and HDES[TBP][Lid] respectively.

[0051] Test Example 1

[0052] The 18-CE-6+HDES[TOP][Lid] and HDES[TOP][Lid] and 18-crown-6 (denoted as 18-CE-6) provided in Example 1 were analyzed by nuclear magnetic resonance.1 H NMR spectroscopy analysis revealed 1 H-NMR spectrum Figure 1 As shown in the figure, the box is a partial enlarged view. Figure 1 It can be seen that in the 18-crown-6 modified deep eutectic solvent, the chemical shift of the methylene hydrogen in 18-crown-6 changes. From the information in the magnified box, it can be found that the characteristic peak of 18-CE-6+HDES[TOP][Lid] contains all the signals from 18-CE-6 and HDES[TOP][Lid], which proves the successful synthesis of the modified deep eutectic solvent 18-CE-6+HDES[TOP][Lid].

[0053] The 18-CE-6+HDES[TBP][Lid] and HDES[TBP][Lid] and 18-crown-6 (denoted as 18-CE-6) provided in Example 2 were analyzed by nuclear magnetic resonance. 1 H NMR spectroscopy analysis revealed 1 H-NMR spectrum Figure 2 As shown in the figure, the box is a partial enlarged view. Figure 2 It can be seen that in the 18-crown-6 modified deep eutectic solvent, the chemical shift of the methylene hydrogen in 18-crown-6 changes. From the information in the magnified box, it can be found that the characteristic peak of 18-CE-6+HDES[TBP][Lid] contains all the signals from 18-CE-6 and HDES[TBP][Lid], which proves the successful synthesis of the modified deep eutectic solvent 18-CE-6+HDES[TOP][Lid].

[0054] Test Example 2

[0055] Extraction tests were carried out using the 18-crown-6 modified deep eutectic solvent provided in Examples 1 and 2 and the deep eutectic solvent provided in Comparative Examples 1 and 2 as extractants with a series of low-concentration metal ion aqueous solutions.

[0056] The metal ion in the low concentration metal ion aqueous solution is Li + 、Co 2+ 、Ni 2+ The concentrations of the three metal ions are the same, and the concentrations of each metal ion in the series of low-concentration metal ion aqueous solutions are 50 mg / L, 75 mg / L, and 100 mg / L, respectively.

[0057] The extraction device is a constant temperature water ring liquid-liquid phase equilibrium kettle. The volume ratio of the extractant to the low concentration metal ion aqueous solution is 1:1, the extraction pH value is 4, the extraction temperature is 40 ° C, the extraction time is 1 hour, and the stirring speed is 100 rpm. After the extraction is completed, the concentration of each metal ion in the raffinate phase is measured and the extraction rate of each metal ion E is calculated. i, and the results are recorded in Tables 1 to 3.

[0058] Table 1 Effect of different extractants on Co 2+ Extraction rate record sheet

[0059]

[0060]

[0061] Table 2 Effect of different extractants on Ni 2+ Extraction rate record sheet

[0062] / <![CDATA[E i (Neither 2+ 50mg / L)]]> <h2 style=";text-align:left;direction:ltr"><![CDATA[E <h2 style=";text-align:left;direction:ltr"> i <h2 style=";text-align:left;direction:ltr"> (Ni<h2 style=";text-align:left;direction:ltr"> 2+ <h2 style=";text-align:left;direction:ltr"> 75mg / L)]]><h2 style=";text-align:left;direction:ltr"> <![CDATA[E i (Ni 2+ 100mg / L)]]> 18-CE-6+HDES[TOP][Lid] 0.9319 0.9121 0.8955 18-CE-6+HDES[TBP][Lid] 0.9481 0.9238 0.9075 HDES[TOP][Lid] 0.8794 0.8462 0.7987 HDES[TBP][Lid] 0.8945 0.8576 0.8146

[0063] Table 3 Effect of different extractants on Li + Extraction rate record sheet

[0064] / <![CDATA[E i (That + 50mg / L)]]> <![CDATA[E i (That + 75mg / L)]]> <![CDATA[E i (That + 100mg / L)]]> 18-CE-6+HDES[TOP][Lid] 0.2057 0.1849 0.1149 18-CE-6+HDES[TBP][Lid] 0.2986 0.2337 0.1782 HDES[TOP][Lid] 0.1536 0.1466 0.0909 HDES[TBP][Lid] 0.2536 0.2057 0.1542

[0065] From the data in Tables 1 to 3, it can be seen that the 18-crown-6 modified deep eutectic solvent provided in the embodiment of the present invention has a significant effect on the performance of Co 2+ 、Ni 2+ It has good selectivity and high extraction efficiency.

[0066] Application Examples

[0067] The 18-crown-6 modified low eutectic solvent provided in Examples 1 and 2 was used as an extractant to extract cobalt and nickel from the simulated leachate of retired batteries. The process was as follows: using the 18-crown-6 modified low eutectic solvent as an organic extractant system to extract the simulated leachate of retired batteries to obtain a raffinate phase (aqueous phase) and an extraction phase (organic phase); Na2CO3 was added to the aqueous phase to recover the metal (lithium); and hydrochloric acid was added to the organic phase to regenerate the 18-crown-6 modified low eutectic solvent.

[0068] The 18-crown-6 modified deep eutectic solvent provided in Examples 1 and 2 was used as an extractant and mixed with the simulated leachate of retired batteries (the concentration of metal ions was Li + 1.28g / L, Co 2+ 2.03g / L,Ni 2+ 3.19g / L, Cl -Extraction experiments were conducted in a pre-assembled thermostatic water-ring liquid-liquid equilibrium reactor using a 1:1 volume ratio of 18-CE-6 (12.77 g / L) and 18-CE-6 (18-CE-6 + HDES[TOP][Lid]). The extraction pH was 4, the extraction temperature was 40°C, the extraction time was 1 hour, and the stirring speed was 100 rpm. After the extraction experiment, the mixed solution was transferred to a 10 mL centrifuge tube and centrifuged at 8000 rpm for 5 minutes to completely separate the aqueous and organic phases. 1 mL of the aqueous phase was diluted and the metal ion concentration in the aqueous phase was determined using an atomic absorption spectrophotometer. The metal ion concentration in the organic phase was determined using the law of conservation of mass. The extraction efficiencies of 18-CE-6 + HDES[TOP][Lid] for cobalt and nickel were 99.0% and 93.0% respectively; the extraction efficiencies of 18-CE-6 + HDES[TBP][Lid] for cobalt and nickel were 98.6% and 91% respectively.

[0069] The extract and raffinate phases were subjected to stripping experiments under different extraction conditions in a preassembled constant-temperature water-ring liquid-liquid phase equilibrium reactor. After the stripping experiments, the mixture was centrifuged at 8000 rpm for 5 minutes to complete phase separation. The upper organic phase was removed using a pipette, and the aqueous phase flowed out from the lower phase. One gram of the aqueous phase was weighed and diluted, and the concentration of valuable metals in the aqueous phase was determined using an atomic absorption spectrophotometer. The stripping experiments used a 0.3 mol / L hydrochloric acid concentration and a 0.3 mol / L Na2CO3 aqueous solution. The volume ratio of the extract phase to hydrochloric acid was 1:1, and the volume ratio of the raffinate phase to the Na2CO3 aqueous solution was 1:1. Valuable metals were stripped from the extract and raffinate phases, respectively, to obtain high-purity CoCl2 and NiCl2 solutions, Li2CO3 powder, and regenerated 18-crown-6 modified deep eutectic solvent.

[0070] It can be seen from the above examples that the deep eutectic solvent provided by the present invention can efficiently extract cobalt and nickel from the simulated leachate of lithium-ion batteries, enrich lithium, and achieve the separation of cobalt, nickel and lithium.

[0071] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A 18-crown-6 modified deep eutectic solvent comprising 18-crown-6 and a deep eutectic solvent, wherein the deep eutectic solvent comprises equimolar amounts of a hydrogen bond acceptor and a hydrogen bond donor, wherein the hydrogen bond acceptor is trioctyl phosphate or tributyl phosphate, and the hydrogen bond donor is lidocaine.

2. The 18-crown-6 modified deep eutectic solvent according to claim 1, characterized in that The mass percentage of the 18-crown-6 in the 18-crown-6 modified deep eutectic solvent is 2.5-5%.

3. The method for preparing the 18-crown-6 modified deep eutectic solvent according to claim 1 or 2, characterized in that: include: 18-crown-6 is mixed with a deep eutectic solvent; the mixing temperature is 60-80°C.

4. The preparation method according to claim 3, characterized in that The mixing time is 0.5 to 1 hour.

5. A method for extracting cobalt and nickel from hydrochloric acid leachate of retired lithium-ion batteries, characterized in that: include: The hydrochloric acid leachate of retired lithium-ion batteries is mixed with an extraction solvent and then extracted to obtain an extraction phase and a raffinate phase; the extraction phase is an organic phase enriched in cobalt and nickel, and the raffinate phase is an aqueous phase enriched in lithium; the extraction solvent is the 18-crown-6 modified low eutectic solvent according to claim 1 or 2, or the 18-crown-6 modified low eutectic solvent obtained by the preparation method according to claim 3 or 4.

6. The method according to claim 5, characterized in that The volume ratio of the retired lithium-ion battery hydrochloric acid leachate to the extraction solvent is 1:(0.5-2.5).

7. The method according to claim 5, characterized in that During the extraction, the pH value of the mixed solution is adjusted to 2-6.

8. The method according to claim 5, characterized in that The extraction temperature is 20-100°C.

9. The method according to claim 5 or 8, characterized in that The extraction time is 0.5 to 5 hours.

10. The method according to claim 5, characterized in that The extraction further includes back extraction; the back extraction includes adding hydrochloric acid to the extraction phase and adding sodium carbonate aqueous solution to the residual phase.

Images