A method for selectively extracting cobalt, nickel, and manganese metals from leachate of spent batteries

Abstract

This invention relates to a method for selectively extracting cobalt, nickel, and manganese metals from leachate of spent batteries. The method uses a hydrophobic eutectic solvent prepared from octanol, lidocaine, and di(2-ethylhexyl) phosphate in a 1:1:1 molar ratio as the extractant. The aqueous phase is a mixed metal ion solution containing lithium, cobalt, nickel, and manganese. Extraction efficiency is optimized by adjusting experimental parameters such as pH and temperature. A two-phase mixture with a volume ratio of 3 / 1 to 1 / 3 is used, followed by centrifugation. After extraction, cobalt, nickel, and manganese are enriched in the organic phase, while lithium ions remain in the aqueous phase, achieving selective extraction of cobalt, nickel, and manganese. This method achieves an extraction efficiency of over 90% for cobalt, nickel, and manganese, and significantly reduces lithium co-extraction. The process is simple, energy-efficient, and exhibits good phase separation performance. The hydrophobic eutectic solvent used is easy to prepare, low-cost, and environmentally friendly, making it suitable for the efficient separation and recovery of multiple metal ions from spent batteries.

Description

Technical Field

[0001] This invention belongs to the field of extraction chemistry and chemical separation technology, and specifically relates to a method for selectively extracting cobalt, nickel and manganese metals from leachate of waste batteries. Background Technology

[0002] With the rapid development of new energy vehicles and consumer electronics industries, secondary batteries are playing an increasingly prominent role in energy storage and supply systems. However, if waste batteries are not effectively recycled, the heavy metals, organic electrolytes, and other harmful components they contain can cause continuous pollution to the ecological environment, while also leading to a serious waste of key metal resources such as lithium, cobalt, nickel, and manganese. Due to the complex composition, dense structure, and diverse forms of metal coexistence in waste battery materials, especially when lithium and transition metals coexist with significant differences in content, achieving efficient separation and selective recycling of high-value metals such as cobalt, nickel, and manganese faces considerable challenges. Therefore, developing novel green recycling technologies suitable for complex aqueous systems and capable of selective separation in multi-metal systems is of great significance for improving the resource utilization level of waste batteries.

[0003] Currently, the main methods for recovering valuable metals from waste batteries include pyrometallurgy, hydrometallurgy, and direct recycling. Pyrometallurgy is highly adaptable but suffers from high energy consumption and severe secondary pollution. Direct recycling, while maintaining the integrity of the material structure and producing high added value, has strict requirements on battery type and condition, limiting its applicability and making it difficult to meet the selective recovery needs of cobalt, nickel, and manganese in complex waste battery systems. In contrast, hydrometallurgy combined with solvent extraction technology offers advantages such as high separation accuracy, mild conditions, and strong process adjustability in multi-metal systems, providing a feasible approach for the selective extraction of cobalt, nickel, and manganese in lithium-cobalt coexisting systems in waste batteries. CN108642283B reports a nickel-cobalt synergistic extraction system composed of pyridylphosphamide and dialkylnaphthalenesulfonic acid, which can achieve synergistic extraction of nickel and cobalt in multi-metal coexisting aqueous solutions while suppressing impurity metals such as magnesium, manganese, and calcium, exhibiting good selectivity and phase separation performance. CN109811127A reports a method for removing copper, iron, and aluminum and recovering manganese, nickel, and cobalt from battery leachate by adjusting pH and combining multi-stage extraction, precipitation, and back-extraction processes, while simultaneously obtaining lithium products. This method can achieve multi-metal separation and recovery, but the process is relatively complex.

[0004] Given the limitations of existing multi-metal separation technologies, researchers are continuously exploring more efficient, simplified, and economically feasible separation methods. Liquid-liquid extraction has significant advantages in the field of waste battery metal recycling due to its low energy consumption and flexible operating conditions. However, traditional organic extractants generally suffer from high volatility, high toxicity, and high recycling costs. While ionic liquids exhibit excellent extraction performance, their complex synthesis and high cost limit their large-scale application. Therefore, developing green extractants suitable for complex multi-metal systems such as waste battery leachates and capable of effectively separating lithium from cobalt, nickel, and manganese is of great significance. Eutectic solvents are gradually attracting attention due to their advantages such as low toxicity, biodegradability, wide availability of raw materials, and simple preparation processes. Currently, metal extraction research mainly focuses on binary eutectic systems. However, the extraction thermodynamics and molecular-level mechanisms of ternary hydrophobic eutectic solvents, which have more flexible compositions, stronger hydrophobicity, and are more conducive to the selective extraction of cobalt, nickel, and manganese in aqueous systems, still lack systematic research. Summary of the Invention

[0005] The purpose of this invention is to provide a method for selectively recovering metals from leachate of waste batteries. The method uses a hydrophobic eutectic solvent with high extraction efficiency, good hydrophobicity and excellent thermal stability as the extractant to achieve preferential extraction of cobalt, nickel and manganese ions in a lithium, cobalt, nickel and manganese coexisting system, and effectively suppress the co-extraction behavior of lithium ions. This solves the problems of difficult phase separation after extraction, easy solubility of organic extractants in water and the resulting environmental pollution in the prior art.

[0006] Technical solution

[0007] This invention addresses the challenge of separating multiple metals coexisting in leachate from spent batteries by proposing a method for selectively extracting cobalt, nickel, and manganese from a lithium, cobalt, nickel, and manganese system. This method is mild and environmentally friendly, achieving single-stage extraction efficiencies of up to 94.81%, 92.49%, and 97.32% for cobalt, nickel, and manganese, respectively, while the extraction rate for lithium is only 15.56%.

[0008] The present invention is achieved through the following technical solution.

[0009] A method for selectively extracting cobalt, nickel, and manganese metals from leachate of spent batteries includes the following steps: (1) Synthesize the extractable organic phase; the extractable organic phase is mainly a hydrophobic eutectic solvent; wherein the hydrophobic eutectic solvent is prepared by mixing octanol, lidocaine and di(2-ethylhexyl) phosphate in a molar ratio of 1:1:1 under the condition of 353.15K; (2) Prepare the extractable aqueous phase; the contents of lithium, cobalt, nickel and manganese metal ions in the extractable aqueous phase are 1.74 g / L, 2.95 g / L, 7.34 g / L and 4.12 g / L respectively; (3) Change the extraction conditions; wherein the specific conditions include: the molar ratio of octanol, lidocaine and di(2-ethylhexyl) phosphate, the volume ratio of organic phase and aqueous phase, the pH value of aqueous phase and extraction temperature; (4) After thoroughly mixing the extractable organic phase and the aqueous phase in a volume ratio of 3 / 1-1 / 3, let it stand and perform phase separation to obtain an organic phase enriched with cobalt, nickel and manganese ions and a lithium-rich raffinate aqueous phase.

[0010] As a further optimization of the method for selectively extracting cobalt, nickel, and manganese metals from waste battery leachate of the present invention: considering the influence of the molar ratio of hydrogen bond donors and acceptors on the extraction efficiency, the molar ratio of octanol, lidocaine, and di(2-ethylhexyl) phosphate was determined to be 1:1:1.

[0011] As a further optimization of the method for selectively extracting cobalt, nickel, and manganese metals from waste battery leachate of the present invention: considering the influence of extraction temperature on extraction efficiency, the extraction temperature is determined to be 298.15K.

[0012] As a further optimization of the method for selectively extracting cobalt, nickel, and manganese metals from waste battery leachate of the present invention: considering the influence of aqueous phase pH on extraction efficiency, the pH value of the aqueous solution is determined to be 1.

[0013] As a further optimization of the method for selectively extracting cobalt, nickel, and manganese metals from waste battery leachate of the present invention: considering the effect of the ratio (O / A) on the extraction efficiency, the O / A ratio is determined to be 3:1.

[0014] Beneficial effects

[0015] This invention introduces a hydrophobic eutectic solvent into the leachate of waste batteries containing lithium, cobalt, nickel, and manganese, thereby achieving effective separation of cobalt, nickel, and manganese ions from the aqueous phase. The maximum extraction efficiency of the target metals can reach over 90%, while reducing the co-extraction behavior of lithium ions, so that the metal ion content in the treated aqueous phase meets national emission standards. Attached Figure Description

[0016] Figure 1 This is a process flow diagram of the method for selectively extracting cobalt, nickel, and manganese metals from waste battery leachate according to the present invention. Detailed Implementation

[0017] Example 1:

[0018] A method for selectively extracting cobalt, nickel, and manganese metals from leachate of spent batteries includes the following steps: A hydrophobic eutectic solvent synthesized from octanol, lidocaine, and di(2-ethylhexyl) phosphate was added to the leachate of spent batteries containing lithium, cobalt, nickel, and manganese. Liquid-liquid extraction was performed at 298.15 K with an organic phase to aqueous phase volume ratio of 1:1. The mixture was stirred at 600 r / min for 20 min on a magnetic stirrer until extraction equilibrium was reached. The mixture was then transferred to centrifuge tubes and centrifuged at 6000 r / min for 10 min to achieve complete phase separation and a clear phase interface. Atomic absorption spectrometry analysis of the separated solution showed that the extraction efficiencies for cobalt, nickel, and manganese ions were 93.95%, 91.81%, and 96.57%, respectively, while the extraction efficiency for lithium ions was only 14.37%, demonstrating good selectivity for cobalt, nickel, and manganese.

[0019] Example 2:

[0020] A method for selectively extracting cobalt, nickel, and manganese metals from leachate of spent batteries includes the following steps: The pH of the aqueous solution was adjusted to 1 using NaOH or HCl. A hydrophobic eutectic solvent was added, and the volume ratio of the hydrophobic eutectic solvent to the metal ion aqueous solution was 1:1 at 298.15 K. The mixture was thoroughly stirred at 600 r / min for 20 minutes on a magnetic stirrer. Liquid-liquid extraction experiments were then performed. After thorough mixing, the mixture was allowed to reach equilibrium and transferred to centrifuge tubes. Centrifugation at 6000 r / min for 10 minutes resulted in a clear phase interface and complete phase separation. Atomic absorption spectrometry was used to analyze the phase-separated solution. The results showed that the extraction efficiencies for cobalt, nickel, and manganese ions were 95.14%, 91.44%, and 95.49%, respectively, while the extraction efficiency for lithium ions was only 18.07%.

[0021] Example 3:

[0022] A method for selectively extracting cobalt, nickel, and manganese metals from leachate of spent batteries includes the following steps: A hydrophobic eutectic solvent was added to an aqueous solution of metal ions at a volume ratio of 3:1 at 298.15°C. The mixture was stirred thoroughly at 600 rpm for 20 minutes using a magnetic stirrer. Liquid-liquid extraction was then performed. After thorough mixing and equilibration, the mixture was transferred to centrifuge tubes and centrifuged at 6000 rpm for 10 minutes. A clear phase interface appeared, indicating complete phase separation. Atomic absorption spectrometry was used to analyze the separated solution. The results showed that the extraction efficiencies for cobalt, nickel, and manganese ions were 97.85%, 94.77%, and 98.85%, respectively, while the extraction efficiency for lithium ions was only 18.56%.

Claims

1. A method for selectively extracting cobalt, nickel, and manganese metals from leachate of spent batteries, characterized in that, Including the following steps: (1) Preparation of an extractable organic phase, wherein the extractable organic phase is a hydrophobic eutectic solvent, which is obtained by mixing octanol, lidocaine and di(2-ethylhexyl) phosphate in a molar ratio of 1:1:1; (2) Prepare an aqueous phase for extraction. The contents of lithium, cobalt, nickel and manganese ions in the aqueous phase are 1.74 g / L, 2.95 g / L, 7.34 g / L and 4.12 g / L, respectively. (3) Adjust the extraction conditions, which include: the molar ratio of octanol, lidocaine and di(2-ethylhexyl) phosphate, the volume ratio of organic phase and aqueous phase, the pH value of aqueous phase and extraction temperature; (4) The extracted organic phase and the aqueous phase are thoroughly mixed at a volume ratio of 3 / 1 to 1 / 3 and then separated to obtain an organic phase enriched with cobalt, nickel and manganese ions and a lithium-rich raffinate aqueous phase.

2. The method for selectively extracting metal ions from leachate of spent batteries according to claim 1, characterized in that, The extractant is a hydrophobic eutectic solvent, which is synthesized from octanol, lidocaine and di(2-ethylhexyl) phosphate at 353.15 K.

3. The method for selectively extracting metal ions from leachate of spent batteries according to claim 1, characterized in that, The octanol, lidocaine, and di(2-ethylhexyl) phosphate are mixed in a molar ratio of 1:1:1 to achieve selective extraction of cobalt, nickel, and manganese ions and suppress co-extraction of lithium ions.

4. The method for selectively extracting metal ions from leachate of spent batteries according to claim 1, characterized in that, The extraction temperature was 298.15 K.

5. The method for selectively extracting metal ions from leachate of spent batteries according to claim 1, characterized in that, The concentrations of lithium, cobalt, nickel, and manganese ions in the extracted aqueous phase were 1.74 g / L, 2.95 g / L, 7.34 g / L, and 4.12 g / L, respectively.

6. The method for selectively extracting metal ions from leachate of spent batteries according to claim 1, characterized in that, The extraction time during the extraction process is 5 min to 90 min.

7. The method for selectively extracting metal ions from leachate of spent batteries according to claim 1, characterized in that, The volume ratio of the extracted organic phase to the aqueous phase is 3 / 1 to 1 / 3.

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