Method for extracting metal ions in leaching solution of lithium ion battery by using composite system extracting agent

Abstract

The invention belongs to the technical field of recycling of positive electrode materials of waste lithium ion batteries. The invention provides a method for extracting lithium ion battery lixivium metal ions by using a composite system extractant, which comprises the following steps: mixing a phosphoric acid extractant and an ionic liquid to obtain a composite extraction system, extracting, separating, reextracting and the like, so that the metal ions in the waste lithium ion battery lixivium can be extracted and separated without finely adjusting and balancing the pH value; the extraction agent is good in stability, can be recycled for multiple times and is high in extraction capacity.

Description

Technical Field

[0001] The invention relates to the technical field of recycling and reusing waste lithium-ion battery positive electrode materials, and in particular to a method for extracting metal ions from lithium-ion battery leachate using a composite system extractant. Background Art

[0002] In the past 30 years of commercial applications, lithium-ion batteries have been widely used in mobile electronic devices such as personal computers, cameras and mobile phones due to their electrochemical advantages, such as long life, high voltage, high energy density and wide operating temperature range. At present, driven by the demand for low-carbon and environmental protection, the rapid development of electric vehicles and electrochemical energy storage has further promoted the production of lithium-ion batteries in order to replace fossil fuels and achieve the widespread application of renewable energy. However, during the charge and discharge cycle, factors such as electrode volume changes, electrode-electrolyte chemical reactions or electrodeposition lead to irreversible capacity loss, which eventually causes the scrapping of lithium batteries and forms a large number of "urban mines". This phenomenon quickly triggered concerns about the supply security of key battery metals such as lithium, nickel and cobalt, as well as the safe disposal of waste lithium batteries. Therefore, various technologies have emerged, including mechanical methods, pyrometallurgy and hydrometallurgy (including bioleaching and electrochemical methods), aiming to recover valuable metals from waste lithium-ion batteries and reduce the risks of solid waste management.

[0003] Among the many recycling methods, solvent extraction is considered to be one of the most popular technologies due to its high recovery rate, good element separation effect, mild experimental conditions, and simple operation. Solvent extraction is based on the principle of coordination chemistry and achieves efficient material and energy utilization through the recycling cycle of reagents. In addition, this technology also has the environmental advantage of reducing harmful gas emissions.

[0004] In the current extraction technology, phosphoric acid extractants or ionic liquids are mostly used for extraction. However, when each is used alone, the extraction process is relatively complicated, which can easily cause component loss and low recovery efficiency. Therefore, it is particularly important to develop a green and sustainable extraction process. Summary of the invention

[0005] The present invention provides a method for extracting metal ions from lithium-ion battery leachate using a composite system extractant, aiming to improve at least one of the above-mentioned technical problems.

[0006] In order to solve the above technical problems, the present invention provides a method for extracting metal ions from lithium ion battery leachate using a composite system extractant, comprising the following steps:

[0007] Step S1: saponifying the phosphoric acid extractant with an alkali, and mixing it with an ionic liquid to obtain a phosphoric acid extractant-ionic liquid system.

[0008] Step S2: The phosphoric acid extractant-ionic liquid system and the lithium battery positive electrode metal ion leaching solution are mixed according to a volume ratio, and oscillated and centrifuged at 20-80° C. to separate the extraction phase and the raffinate phase.

[0009] As a further optimization, the step S2 further includes a step S21: mixing and diluting the phosphoric acid extractant-ionic liquid system with sulfonated kerosene to reduce the viscosity.

[0010] As a further optimization, the step S2 also includes a step S22: mixing the metal ion leaching solution of the lithium battery positive electrode sheet with a sodium hydroxide solution to adjust the pH value, and the adjusted pH value can be in the range of 1.0-5.0.

[0011] As a further optimization, in step S2, during centrifugation, the centrifugal speed is 5000 r / min and the centrifugal time is 2 minutes.

[0012] As a further optimization, in step S2, the volume ratio of the phosphoric acid extractant-ionic liquid system to the metal ion leachate of the lithium battery positive electrode sheet is any one of 2:1, 1:1, 1:2 or 1:3.

[0013] As a further optimization, in step S2, the oscillation time is 2-60 minutes.

[0014] Step S3: Mix the extract phase and the stripping agent, shake them at 20-80° C., separate them after stratification, and obtain a regenerated extractant, wherein the shaking time is 2-60 minutes.

[0015] As a further optimization, the phosphoric acid extractant is any one of D2EHPA, PC-88A, Cyanex 272 or Cyanex301.

[0016] As a further optimization, the ionic liquid is any one of trihexyltetradecylphosphine chloride, trihexyltetradecylphosphine bromide, tri-n-butyltetradecylphosphine chloride or trihexyltetradecylphosphine bis(2,4,4-trimethylpentyl) hypophosphite.

[0017] As a further optimization, the metal ion leachate of the lithium battery positive electrode sheet is any one of a lithium cobalt oxide battery leachate, a nickel cobalt manganese oxide battery leachate, a lithium manganese oxide battery leachate or a lithium iron phosphate battery leachate.

[0018] By adopting the above technical solution, the present invention can achieve the following beneficial effects:

[0019] 1) Introducing green solvent ionic liquids based on traditional phosphoric acid extractants to achieve metal ion extraction and separation of waste lithium battery leachate, reducing the delicate requirements for balanced pH and optimizing the extraction process

[0020] 2) The stripping agent is simple and easy to obtain, and no acid solution stripping is required;

[0021] 3) The regenerated extractant has good stability and can be recycled many times;

[0022] 4) The phosphoric acid extractant and ionic liquid system has a high extraction capacity for metal ion leaching solution of waste lithium batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0024] Figure 1 This is a flow chart of extracting metal ions from lithium-ion battery leachate using a composite system extractant of the present invention;

[0025] Figure 2 The invention is the distribution coefficient of various metal ions in the extraction system and the stripping rate of cobalt when the phosphoric acid extractant-ionic liquid system is used for extraction-stripping cycle;

[0026] Figure 3 It is the extraction rate of various metal ions in the extraction system and the cumulative extraction capacity of cobalt when the phosphoric acid extractant-ionic liquid system is continuously extracted and circulated (without back extraction) in the present invention; DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the invention claimed for protection, but merely represents the selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0028] like Figure 1 As shown, an embodiment of the present invention provides a method for extracting metal ions from lithium-ion battery leachate using a composite system extractant, comprising the following steps:

[0029] Step S1: saponifying the phosphoric acid extractant with an alkali, and mixing it with an ionic liquid to obtain a phosphoric acid extractant-ionic liquid system.

[0030] Step S2: The phosphoric acid extractant-ionic liquid system and the lithium battery positive electrode metal ion leaching solution are mixed according to a volume ratio, and oscillated and centrifuged at 20-80° C. to separate the extraction phase and the raffinate phase.

[0031] Preferably, the step S2 further comprises a step S21: mixing and diluting the phosphoric acid extractant-ionic liquid system with sulfonated kerosene to reduce the viscosity.

[0032] Preferably, the step S2 further includes a step S22: mixing the metal ion leaching solution of the lithium battery positive electrode plate with a sodium hydroxide solution to adjust the pH value, and the adjusted pH value can be in the range of 1.0-5.0.

[0033] Preferably, in step S2, during centrifugation, the centrifugal speed is 5000 r / min and the centrifugal time is 2 minutes.

[0034] Preferably, in step S2, the volume ratio of the phosphoric acid extractant-ionic liquid system to the lithium battery positive electrode metal ion leachate is any one of 2:1, 1:1, 1:2 or 1:3.

[0035] Preferably, in step S2, the oscillation time is 2-60 minutes.

[0036] Step S3: Mix the extract phase and the stripping agent, oscillate at 20-80°C, separate after stratification, and obtain a regenerated extractant. The oscillation time is 2-60 minutes. The extractant regenerated in the above manner can be used for cyclic extraction, and the cyclic effect is stable.

[0037] Preferably, the phosphoric acid extractant is any one of D2EHPA, PC-88A, Cyanex 272 or Cyanex 301.

[0038] Preferably, the ionic liquid is any one of trihexyltetradecylphosphine chloride, trihexyltetradecylphosphine bromide, tri-n-butyltetradecylphosphine chloride or trihexyltetradecylphosphine bis(2,4,4-trimethylpentyl) hypophosphite.

[0039] Preferably, the metal ion leachate of the lithium battery positive electrode sheet is any one of a lithium cobalt oxide battery leachate, a nickel cobalt manganese oxide battery leachate, a lithium manganese oxide battery leachate or a lithium iron phosphate battery leachate.

[0040] Example 1: Phosphoric acid extractant-ionic liquid system extraction-stripping cycle.

[0041] The specific contents are as follows:

[0042] Extraction process:

[0043] The phosphoric acid extractant Cyanex 272 is saponified with alkali, mixed with the ionic liquid trihexyltetradecylphosphonium chloride, and sulfonated kerosene is added for dilution to reduce the viscosity to obtain a phosphoric acid extractant-ionic liquid system, and the reagent of the system is used as the organic phase;

[0044] The metal ion leaching solution of the lithium battery positive electrode sheet is mixed with the sodium hydroxide solution to adjust the pH value to the range of 1.0-5.0;

[0045] The phosphoric acid extractant-ionic liquid system obtained above was mixed with the metal ion leachate of the lithium battery positive electrode sheet after adjusting the pH value above according to a volume ratio, and oscillated and mixed for 15 minutes at 25° C. The concentration of each metal ion in the metal ion leachate of the lithium battery positive electrode sheet was 5780 ppm for cobalt ions and 604 ppm for lithium ions.

[0046] Separation process:

[0047] The centrifugation was performed at a rotation speed of 5000 r / min for 2 minutes to separate the extract phase and the raffinate phase.

[0048] Stripping process:

[0049] A certain volume of water was added to the extract phase obtained after separation, and the mixture was shaken and mixed at 25 degrees Celsius for 10 minutes. The two phases were separated after stratification to obtain a regenerated extractant.

[0050] Cyclic extraction process:

[0051] Take 5 mL of the regenerated extractant and mix it with an equal volume of the metal ion leachate of the lithium battery positive electrode, and repeat the extraction-separation-strip extraction process. The metal ion concentration in the aqueous phase is measured by inductively coupled plasma optical emission spectrometry (ICP-OES), and the metal ion distribution ratio is calculated. The results are shown in Figure 2 As shown in the figure, the extraction cycle effect of phosphoric acid extractant and ionic liquid system is stable.

[0052] Among them, Cyanex 272 is a commercial dialkyl phosphate extractant that is completely miscible with aromatic and aliphatic hydrocarbon diluents. Due to its excellent thermal stability and hydrolytic stability, it is widely used in the recovery of cobalt from spent lithium-ion batteries. Ionic liquids are considered green solvents due to their stability in air and water, low volatility and non-flammability, and show great potential in hydrometallurgy. By extending the alkyl chain length, the component loss of ionic liquids during metal extraction can be optimized, thereby improving their extraction efficiency and stability.

[0053] By combining phosphoric acid extractants with ionic liquids to form a composite extraction system, efficient recycling of waste lithium-ion batteries is achieved, while the extraction process is optimized.

[0054] Example 2: Continuous extraction cycle of phosphoric acid extractant-ionic liquid system.

[0055] The specific contents are as follows:

[0056] Extraction process:

[0057] The phosphoric acid extractant Cyanex 272 is saponified with alkali, mixed with the ionic liquid trihexyltetradecylphosphonium chloride, and sulfonated kerosene is added to dilute it to reduce the viscosity, thereby obtaining a phosphoric acid extractant-ionic liquid system, and the reagent of the system is used as an organic phase;

[0058] The metal ion leaching solution of the lithium battery positive electrode sheet is mixed with the sodium hydroxide solution to adjust the pH value to the range of 1.0-5.0;

[0059] The phosphoric acid extractant-ionic liquid system obtained above was mixed with the metal ion leachate of the lithium battery positive electrode sheet after adjusting the pH value above according to a volume ratio, and oscillated and mixed for 15 minutes at 25° C. The concentration of each metal ion in the metal ion leachate of the lithium battery positive electrode sheet was 5780 ppm for cobalt ions and 604 ppm for lithium ions.

[0060] Separation process:

[0061] The centrifugation was performed at a rotation speed of 5000 r / min for 2 minutes to separate the extract phase and the raffinate phase.

[0062] Cyclic extraction process:

[0063] Take 5 mL of the extractant separated during the separation process and mix it with an equal volume of the metal ion leaching solution of the lithium battery positive electrode, and repeat the extraction-separation-extraction process. The extractant was not back-extracted. The metal ion concentration in the aqueous phase was determined by inductively coupled plasma optical emission spectrometry (ICP-OES), and the extraction rate and extraction capacity of the metal ions were calculated. The results are shown in Figure 3 In the present invention, the ionic liquid is circulated continuously for 5 times, and the cumulative extraction capacity of cobalt reaches 10.41 g / L.

[0064] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for extracting metal ions from lithium-ion battery leachate using a composite system extractant, characterized in that: The following steps are involved: Step S1: saponifying the phosphoric acid extractant with an alkali, and mixing it with an ionic liquid to obtain a phosphoric acid extractant-ionic liquid system; Step S2: mixing the phosphoric acid extractant-ionic liquid system and the lithium battery positive electrode sheet metal ion leachate according to a volume ratio, and oscillating and centrifuging at 20-80° C. to separate the extraction phase and the raffinate phase; Step S3: Mix the extraction phase and the stripping agent, shake them at 20-80° C., separate them after stratification, and obtain a regenerated extraction agent.

2. The method for extracting metal ions from lithium-ion battery leachate using a composite system extractant according to claim 1, characterized in that , the phosphoric acid extractant is any one of D2EHPA, PC-88A, Cyanex 272 or Cyanex301.

3. The method for extracting metal ions from lithium-ion battery leachate using a composite system extractant according to claim 1, characterized in that , the ionic liquid is any one of trihexyltetradecylphosphine chloride, trihexyltetradecylphosphine bromide, tri-n-butyltetradecylphosphine chloride or trihexyltetradecylphosphine bis(2,4,4-trimethylpentyl) hypophosphite.

4. The method for extracting metal ions from lithium-ion battery leachate using a composite system extractant according to claim 1, characterized in that The metal ion leaching solution of the lithium battery positive electrode sheet is any one of a lithium cobalt oxide battery leaching solution, a nickel cobalt manganese oxide battery leaching solution, a lithium manganese oxide battery leaching solution or a lithium iron phosphate battery leaching solution.

5. The method for extracting metal ions from lithium-ion battery leachate using a composite system extractant according to claim 1, characterized in that , the step S2 also includes a step S21: mixing and diluting the phosphoric acid extractant-ionic liquid system with sulfonated kerosene to reduce the viscosity.

6. The method for extracting metal ions from lithium-ion battery leachate using a composite system extractant according to claim 1, characterized in that , the step S2 also includes step S22: mixing the metal ion leaching solution of the lithium battery positive electrode sheet with the sodium hydroxide solution to adjust the pH value, and the adjusted pH value is 1.0-5.

0.

7. The method for extracting metal ions from lithium-ion battery leachate using a composite system extractant according to claim 1, characterized in that In step S2, during centrifugation, the centrifugal speed is 5000r / min and the centrifugal time is 2 minutes.

8. The method for extracting metal ions from lithium-ion battery leachate using a composite system extractant according to claim 1, characterized in that In step S2, the volume ratio of the phosphoric acid extractant-ionic liquid system to the metal ion leaching solution of the lithium battery positive electrode sheet is any one of 2:1, 1:1, 1:2 or 1:

3.

9. The method for extracting metal ions from lithium-ion battery leachate using a composite system extractant according to claim 1, characterized in that ,In step S2, the oscillation time is 2-60 minutes.

10. The method for extracting metal ions from lithium-ion battery leachate using a composite system extractant according to claim 1, characterized in that ,In step S3, the oscillation time is 2-60 minutes.

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