Method for separating Li / Co / Mn / Ni in mixed metal solution and application thereof

Abstract

The invention discloses a method for separating Li / Co / Mn / Ni in a mixed metal solution and application of the method, and belongs to the technical field of resource recovery. The method comprises the following steps: extracting transition metal ions in a mixed metal solution by using a solution containing an extracting agent D2EHPA to obtain a loaded organic phase B and a raffinate phase C; the volume percentage of the extracting agent D2EHPA solution is 5%-30%; carrying out reverse extraction on the loaded organic phase B to obtain a reverse extraction phase D; extracting the reverse extraction phase D by using a solution containing an extracting agent P507 to obtain a raffinate phase E and a loaded organic phase F; the volume percentage of the extracting agent P507 solution is 50-90%; and adjusting the pH value of the raffinate phase E to 9-10, and extracting the raffinate phase E by using a solution containing an extracting agent Cyanex 272 to obtain a raffinate phase H and a loaded organic phase I. According to the method, the metal recovery rate is high, the purity is high, and Li, Co, Mn and Ni resources in the aqueous solution can be comprehensively recovered.

Description

Technical Field

[0001] The invention relates to the technical field of resource recovery, and in particular to a method for separating Li / Co / Mn / Ni in a mixed metal solution and application thereof. Background Art

[0002] As the global demand for clean energy continues to grow, lithium-ion batteries have been widely used in electric vehicles, consumer electronics, and energy storage systems due to their high energy density, long cycle life, and low self-discharge rate. According to statistics, the current lithium-ion battery market size has grown at an average annual rate of about 20% in the past decade and is expected to exceed US$100 billion by 2025. However, with the large-scale use of lithium-ion batteries, the number of waste lithium batteries is also increasing dramatically.

[0003] Lithium-ion batteries contain a variety of valuable metal elements, such as cobalt (Co), nickel (Ni), lithium (Li), etc. It is estimated that the cobalt contained in each ton of waste lithium batteries is worth about 100,000 yuan and the lithium is worth about 50,000 yuan. Effectively recycling these metal resources can not only reduce dependence on primary mineral resources, but also reduce the environmental pressure brought by mining primary ores. In addition, harmful substances in waste lithium batteries, such as heavy metals and organic electrolytes, may pollute soil, water sources and atmosphere, and cause serious damage to the ecological environment if they are discarded or improperly handled. For example, the accumulation of heavy metals such as cobalt and nickel in the environment may lead to biological toxicity and ecosystem damage. In addition, metals such as cobalt (Co) and nickel (Ni) contained in lithium batteries are important strategic resources, and ensuring the supply of key metal resources is crucial to energy security. By recycling waste lithium batteries, the high degree of external dependence on strategic metal resources such as cobalt and nickel can be alleviated to a certain extent. At the same time, by recycling waste lithium batteries, new economic growth points can be created, the development of related industries can be promoted, and the full life cycle cost of lithium batteries can be reduced.

[0004] At present, the waste lithium battery recycling industry is in a stage of rapid development. Globally, more and more companies and research institutions are investing in the research and development and industrialization of waste lithium battery recycling technology. In China, as of 2024, more than 200 companies have obtained qualifications related to waste lithium battery recycling. In terms of recycling volume, my country's waste lithium battery recycling volume in 2023 is about 500,000 tons, and it is expected to exceed 1 million tons by 2025.

[0005] The lithium battery recycling technologies currently used mainly include the following: 1. Pyrometallurgy: convert the valuable metals in waste lithium batteries into alloys through high-temperature smelting, and then further separate and purify. This method has the advantages of large processing capacity and high efficiency, but it needs to be carried out under high temperature conditions, resulting in high energy consumption, and the metal recovery rate is relatively low. Some metals may be lost during the high temperature process, and secondary pollution may occur; 2. Hydrometallurgy: use chemical reagents such as acids and alkalis to dissolve the metals in waste lithium batteries, and then separate and recover the metals through precipitation, extraction and other methods. The hydrometallurgical process is relatively mature and has a high metal recovery rate, but the consumption of chemical reagents is large and the wastewater treatment is difficult; 3. Physical screening: including crushing, screening, magnetic separation, flotation and other processes, first pre-treating the waste lithium batteries to separate different components, and then carrying out subsequent recycling treatment. This method has the characteristics of simple process and environmental friendliness, but the metal recovery rate is relatively low, and it usually needs to be combined with other methods to improve the recovery effect. Due to the high recovery rate and high purity of hydrometallurgy, it is widely used. However, there are obvious problems in the current recycling: although the existing recycling technology can achieve the recovery of valuable metals in waste lithium batteries to a certain extent, there are generally problems such as low recovery rate, low product purity, and high cost. For example, the recovery rate of lithium by some technologies is less than 80%. At the same time, there are problems such as complex recycling process and cumbersome operation, which leads to high equipment investment, chemical reagent consumption and processing costs in the recycling process, which is not conducive to the development of the waste lithium battery recycling industry. In existing research, SO 2 The process uses two-stage leaching with acid solution, and uses ammonia water to adjust the pH to separate lithium from cobalt, manganese and nickel, and recover lithium carbonate. The SO used in this process 2 Gas is prone to gas leakage, which can cause damage to the environment and human body. In addition, this process only extracts and recycles lithium, and the obtained product is Li 2 CO 3 The precursor of NCM does not completely separate Li, Co, Mn and Ni, and the purpose of fully recycling lithium batteries is not achieved, which has certain limitations. In another study, the shell and battery materials were separated by explosion-proof magnetic crushing and atomization spray crushing, and then the diaphragm and negative electrode were removed by high temperature negative pressure and carbonization roasting in a constant temperature roasting furnace, and the shell and positive electrode materials were graded and recovered by a centrifugal crusher. The positive electrode characteristics of normal pressure H 2 SO 4Sodium sulfite is added for leaching, the pH value of the leachate is adjusted, and fluoride salt is added for impurity removal to obtain high-purity nickel sulfate and cobalt sulfate solutions with impurities ≤ 2.0 mg / L. However, manganese is not recovered, resulting in a certain waste of resources. Some studies have used sulfuric acid and reducing agents to leach waste lithium batteries after disassembly, crushing and discharge, and gradually remove impurities and recover copper, cobalt, manganese and nickel after entering and exiting, and finally recover lithium, resulting in a long route for lithium recovery, which is prone to lithium loss and low recovery rate.

[0006] In summary, in the relevant technologies for recycling waste lithium-ion batteries, either the recovery of metal elements is incomplete or the metal recovery rate is low. Summary of the invention

[0007] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention provides a method for separating Li / Co / Mn / Ni in a mixed metal solution, which has high metal recovery rate and high purity, and can comprehensively and independently recover Li, Co, Mn and Ni resources in the aqueous solution.

[0008] The invention also provides application of the method.

[0009] According to a first aspect of the present invention, a method for separating Li / Co / Mn / Ni in a mixed metal solution is provided, the method comprising the following steps:

[0010] The mixed metal solution contains Li, Co, Mn and Ni elements;

[0011] S1. Extracting the transition metal ions in the mixed metal solution with a solution containing an extractant D2EHPA to obtain a loaded organic phase B and a raffinate phase C;

[0012] The volume percentage of the extractant D2EHPA solution is 5% to 30%;

[0013] S2. stripping the loaded organic phase B to obtain a stripping phase D;

[0014] S3. Extracting the stripping phase D with a solution containing an extractant P507 to obtain a raffinate phase E and a loaded organic phase F;

[0015] The volume percentage of the extractant P507 solution is 50-90%;

[0016] S4. After adjusting the pH of the raffinate phase E to 9-10, extracting the raffinate phase E with a solution containing the extractant Cyanex 272 to obtain a raffinate phase H and a loaded organic phase I.

[0017] The mechanism of the method is as follows:

[0018] In step S1, Co, Mn and Ni are transferred to the loaded organic phase B, and Li remains in the raffinate phase C, thereby achieving the separation of Li and transition metals;

[0019] In step S2, Co, Mn and Ni are transferred to the stripping phase D;

[0020] In step S3, Mn is transferred to the loaded organic phase F, and Ni and Co remain in the raffinate phase E, thereby achieving the separation of Mn and other transition metals;

[0021] In step S4, Co is transferred to the loaded organic phase I, and Ni remains in the raffinate phase H, thereby achieving separation of Ni and Co.

[0022] The method according to the embodiment of the present invention has at least the following beneficial effects:

[0023] (1) The present invention can gradually achieve the extraction and separation of Li / Mn / Co / Ni metals by utilizing the property that different extractants can selectively react with metal ions under the above conditions. Specifically, in the extraction stage, three types of extractants are used to extract and separate Li / Mn / Co / Ni step by step. In the first stage, the D2EHPA extractant is used to selectively bind to Co / Mn / Ni, so that Co / Mn / Ni is extracted from the leaching solution containing Li / Co / Mn / Ni into the organic phase to separate Li, and Li is retained in the aqueous phase solution (extract phase C); in the second stage, the P507 is used to selectively bind to Mn under specific conditions, so that Mn can be extracted from the Co / Mn / Ni mixed solution into the organic phase to separate Co / Ni, and Co / Ni is retained in the aqueous phase solution. In the third stage, the purpose is to recover Co: Cyanex 272 is used to selectively bind to Co under specific conditions, so that Co is extracted from the mixed solution containing Co / Ni into the organic phase to separate Ni. This process has the advantages of high extraction rate, strong selectivity, simple process, recyclable extractant, low cost, and easy operation.

[0024] (2) In step S1, D2EHPA can efficiently extract Co / Mn / Ni at the above volume percentage, and the metal extraction rate is ≥95%, while its Li extraction rate is less than 10%, and Co / Mn / Ni can be separated from metallic Li. When the volume ratio of D2EHPA extractant in the diluent is less than 5%, the extraction rate of Co / Mn / Ni is greatly reduced, Co can be reduced to about 40%, and Ni can be reduced to 25%, which is not conducive to the separation of Co / Mn / Ni and Li; when the volume ratio of D2EHPA extractant in the diluent is greater than 30%, the extraction capacity of D2EHPA for Li increases with the increase of the volume ratio of the extractant, and the extraction rate of Li can reach up to 50%.

[0025] (3) In step S3, P507 can efficiently extract Mn in the above volume percentage, and the metal extraction rate is ≥95%, while the Co / Ni extraction rate is <10%, and Mn can be separated from the metal Co / Ni. When the volume ratio of the P507 extractant in the diluent is <50%, the extraction rate of Mn is greatly reduced. When the volume fraction of the P507 extractant is >90%, the extraction rate of Ni is greatly increased, and the extraction rate of Ni can be increased to 25%, which is not conducive to the separation of Mn and Co / Ni. In addition, the extraction capacity of P507 for Co, Mn and Ni is related to the external electron distribution of the metal ions, and the extraction order is: Mn>Co>Ni. Therefore, only when the volume fraction of P507 is controlled within the above certain range, can the extraction and separation of Mn by P507 be achieved.

[0026] (4) The present invention limits step S4 to adjust the pH of the raffinate phase E to pH = 9 to 10, and the Cyanex 272 extractant has a high selective extraction capacity for Co, and the single-stage extraction rate of Co is greater than 95%, and within this pH range, the extraction rate of Ni is less than 10%. When the solution pH is less than 9, the extraction rate of Co will drop significantly, less than 50%; when the solution pH is greater than 10, although the extraction rate of Co also increases, the extraction capacity of Ni will increase with the increase of pH, and can reach nearly 40%, which is not conducive to the separation of Co and Ni.

[0027] In summary, the process of the present invention is simple, the production process is safe and reliable, and the stability is high. Specifically, the process adopts an acid leaching method to leach the valuable metals Li / Co / Mn / Ni in the black powder of waste lithium batteries, and the leaching rate can reach 100%; low-cost D2EHPA, P507 and Cyanex 272 are used to extract and separate the Li / Mn / Co / Ni in the leachate, respectively, which can not only recover lithium, but also recover other valuable metals.

[0028] According to some embodiments of the present invention, the mixed metal solution is an aqueous solution.

[0029] According to some embodiments of the present invention, the mixed metal solution is a leachate of waste lithium-ion positive electrode materials, or a leachate of minerals.

[0030] According to some embodiments of the present invention, the leaching solution of the waste lithium ion positive electrode material is obtained by mixing an acid, a reducing agent, and the waste lithium ion positive electrode material for leaching.

[0031] Among them, the solid-liquid ratio of the mixed leaching is 1g:20~100mL; for example, it can be about 1g:40mL, 1g:50mL or about 1g:60mL; thereby, there is enough acid to react with the waste lithium ion positive electrode material, and within this range, it has the advantages of resource saving (acid / reducing agent) and easy solid-liquid separation.

[0032] The concentration of the acid used in the mixed leaching is 2-4 mol / L; for example, it can be about 3 mol / L or about 3.5 mol / L;

[0033] The acid used for the mixed leaching includes HCl, H 2 SO 4 and HNO 3 At least one of;

[0034] The reducing agent is hydrogen peroxide, and the concentration is 25-35 vol %; for example, it can be about 28%, 30% or about 32%.

[0035] The volume percentage of the reducing agent to the acid is 5-20%, for example, about 8%, 9%, 10% or about 15%.

[0036] The mixed solution of acid and hydrogen peroxide of the above concentration is helpful to oxidize the metal, thereby converting the metal into a stable ionic state existing in the aqueous phase, which is beneficial to subsequent extraction.

[0037] The temperature of the mixed leaching is 25-90° C., for example, about 40° C., 60° C. or about 80° C. The increase in temperature can increase the kinetic energy of molecules, accelerate molecular motion, and thus promote diffusion, which is beneficial to leaching. In this temperature range, the evaporation rate of the water phase used in the mixed leaching can be controlled to avoid the situation where the water phase is evaporated to dryness.

[0038] The duration of the mixed leaching is 1 to 2 hours; for example, it can be about 1.5 hours. Studies have found that when the leaching time is about 1 hour, the leaching rate begins to tend to equilibrium. Generally, the leaching amount is proportional to the leaching time, but when the diffusion reaches equilibrium, time no longer plays a role. In order to ensure that the leaching reaction is completely leached, all metals in the metal powder are leached as much as possible, and all metals are recovered, the leaching time is 1 hour to 2 hours. Within this time range, the leaching efficiency and production efficiency can be guaranteed, and the leaching of waste can be avoided.

[0039] During the mixed leaching process, Li / Co / Mn / Ni can be transformed from a metal oxidation state (or other solid form) to an ionic state soluble in water, and transferred from the solid to the leachate; the addition of a reducing agent such as hydrogen peroxide helps to reduce the metal and accelerate the mixed leaching process.

[0040] According to some embodiments of the present invention, the waste lithium ion positive electrode material includes at least one of lithium cobalt oxide, lithium nickel oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt oxide and lithium cobalt manganese oxide. Among them, the ratio of nickel, cobalt and manganese in lithium nickel cobalt manganese oxide is not strictly limited. In other words, no matter which waste lithium ion positive electrode material is used, it does not affect the implementation of the method provided by the present invention.

[0041] According to some embodiments of the present invention, in step S1, in the extraction step with the extractant D2EHPA solution: the O / A value is 0.5 to 1.5:1. For example, it can be about 0.5:1, 0.8:1, 1:1, 1.2:1, 1.5:1.

[0042] The O / A volume ratio is between 1 / 2 and 1.5 / 1 because when the ratio of the organic phase to the aqueous phase is greater than 1.5, the extraction rate of D2EHPA for Li also increases with the increase of the volume of the organic phase, which is not conducive to the separation of Li and Co / Mn / Ni; when O / A is less than 1 / 2, its extraction rate for Co / Mn will be greatly reduced, among which the extraction rate of Co will be reduced to less than 60%, and the extraction rate of Mn will be reduced to only 35%, and a good separation of Co / Mn / Ni and Li cannot be achieved.

[0043] According to some embodiments of the present invention, step S1 further comprises adjusting the pH of the mixed metal solution to 2 to 8 before extraction. For example, the pH may be about 2, 3, 4, 5, 6, 7, or 8.

[0044] In step S1, alkali solution is used to adjust the solution pH to 2-8. The reason is that the aqueous phase solution after leaching is strongly acidic, and an overly acidic aqueous phase solution causes the organic solvent to fail, which is not conducive to extraction. When the solution is at pH = 2-8, the extraction rate of Mn / Co / Ni by the D2EHPA extractant at the optimal volume fraction is > 95%, while the extraction rate of Li is < 5%. When the pH is too high and the solution is highly alkaline, the metal ions in the solution will form a precipitate, which is not conducive to extraction. This is because between pH = 2 and 8, the distribution of metal ion species is conducive to the valence bond binding of metal compound ions and the extractant, so that Mn / Co / Ni can be extracted by D2EHPA.

[0045] According to some embodiments of the present invention, in step S1, the extraction includes mixing and phase separation in sequence. The mixing time is 15 to 35 minutes; for example, it can be about 15 minutes; the mixing is performed by mechanical stirring. The phase separation method includes standing and centrifugation; if centrifugation is used, the time is 3 to 8 minutes; for example, it can be about 5 minutes.

[0046] According to some embodiments of the present invention, the method further comprises precipitating lithium carbonate from the raffinate phase C.

[0047] According to some embodiments of the present invention, the step of precipitating lithium carbonate includes: adjusting the pH of the raffinate phase C to 11-12, and precipitating lithium at 80-90° C. using a saturated carbonate aqueous solution.

[0048] According to some embodiments of the present invention, in the step of precipitating lithium carbonate: the molar ratio of the lithium to the carbonate is 1:1.2 to 1.5.

[0049] Under the above conditions, due to the inverse temperature effect of lithium carbonate solubility, the lithium carbonate content in the product generally increases with the increase of precipitation temperature. When the temperature is 80-90°C, the lithium carbonate precipitation rate is optimal at pH = 11-12. Under this condition, the generated lithium carbonate is stable; excess saturated Na 2 CO 3 , which is conducive to the full reaction of Li ions to form lithium carbonate precipitation.

[0050] According to some embodiments of the present invention, in step S2, the stripping process includes mixing and phase separation in sequence. The mixing time is 10 to 20 minutes; for example, it can be about 15 minutes; the mixing is performed by mechanical stirring. The phase separation method includes standing and centrifugation; if centrifugation is used, the time is 3 to 8 minutes; for example, it can be about 5 minutes.

[0051] According to some embodiments of the present invention, step S3 further comprises adjusting the pH of the stripping phase D to 1 to 4 before the extraction. For example, it can be about 1, 2, 3, or 4.

[0052] The reason is that when the solution is at pH = 1-4, the extraction rate of Mn by P507 extractant is greater than 80%, the extraction rate of Mn by P507 at the optimal volume fraction and the optimal pH can reach 95%, the extraction rate of Co is less than 10%, and Ni is basically not extracted; and as the pH increases, the extraction rate of Co / Ni by P507 increases, which is not conducive to the separation of Mn and Co / Ni. Too high pH will also lead to metal precipitation, which is not conducive to extraction. The principle is that when pH = 1-4, Mn mainly exists in the form of Mn2+, Co and Ni exist in the form of Co2+ and Ni2+, and when the pH increases, the distribution of ionic species will change, which is not conducive to the organic phase and the extraction of Mn.

[0053] According to some embodiments of the present invention, in step S3, in the extraction step with the extractant P507 solution: the O / A value is 2 to 4:1. For example, it can be about 2:1, 2.5:1, 3:1, 3.5:1, 4:1.

[0054] The O / A volume ratio is between 2 / 1 and 4 / 1 because when the ratio of the organic phase to the aqueous phase is greater than 4, the extraction rate of Co by P507 also increases with the increase of the volume of the organic phase, which is not conducive to the separation of Mn and Co / Ni; when O / A is less than 2, its extraction rate of Mn will also be less than 50%. The main purpose of controlling the O / A ratio within a certain range is to control the mass transfer capacity between the organic molecules of the extractant and the metal ions. When there is too much organic phase, the viscosity of the extraction system will increase, thereby hindering the mass transfer collision between molecules and ions, which is not conducive to the combination between organic molecules and metal ions.

[0055] According to some embodiments of the present invention, in step S3, the extraction includes mixing and phase separation in sequence. The mixing time is 15 to 35 minutes; for example, it can be about 15 minutes; the mixing is performed by mechanical stirring. The phase separation method includes standing and centrifugation; if centrifugation is used, the time is 3 to 8 minutes; for example, it can be about 5 minutes.

[0056] According to some embodiments of the present invention, the method further comprises: stripping the loaded organic phase F to obtain a stripping phase G; and precipitating a manganese salt from the stripping phase G.

[0057] According to some embodiments of the present invention, the step of precipitating manganese salt includes: adjusting the pH of the stripping phase G to 9-10, adding an excess of 2-3 mol / L alkaline aqueous solution with an excess coefficient of 1.1-1.2, and precipitating manganese at 50-70°C.

[0058] In the step of precipitation of manganese, the temperature is 50-70°C, which is conducive to the precipitation of metal. Too low a temperature is not conducive to the dissolution of manganese hydroxide in the aqueous solution, and too high a temperature is not conducive to the precipitation of metal. 2+ Can be used with OH - Combined to form Mn(OH) 2 Too low a pH value will not allow the formation of manganese oxide precipitation, and too high a pH value will affect the precipitation rate.

[0059] According to some embodiments of the present invention, in step S4, in the extraction step using a solution containing the extractant Cyanex 272, the O / A value is 0.5 to 3:1.

[0060] According to some embodiments of the present invention, in step S4, the volume percentage of the extractant Cyanex 272 solution is 5% to 30%.

[0061] According to some embodiments of the present invention, in step S4, the diluent of the extractant Cyanex 272 solution is kerosene.

[0062] The extraction rate of Co by Cyanex 272 at the above concentrations is >95%. The extraction rate of Co by Cyanex 272 at the optimal extraction volume is ≥98%, while the extraction rate of Ni is <10%, which means that Co can be separated from Ni. Too low a volume fraction will reduce the extraction rate of Co by Cyanex 272, making it difficult to separate Co from Ni. When the volume fraction of Cyanex 272 is higher than 90%, its extraction rate of Ni also increases, which is not conducive to the separation of Co / Ni. The reason for controlling the volume fraction of Cyanex 272 is that Cyanex 272 has the ability to extract Co / Ni under certain conditions, and the order of extraction ability is Co>Ni. This is because Co 2+ with Ni 2+ The different external electron configurations of Cyanex 272 lead to different binding abilities with Cyanex 272. Therefore, the extraction ability of Cyanex 272 for Ni will increase with the increase of volume fraction. It is necessary to control a certain volume fraction so that Cyanex 272 has the ability to extract Co but not Ni.

[0063] According to some embodiments of the present invention, in step S4, the stripping process includes mixing and phase separation in sequence. The mixing time is 10 to 20 minutes; for example, it can be about 15 minutes; the mixing is performed by mechanical stirring. The phase separation method includes standing and centrifugation; if centrifugation is used, the time is 3 to 8 minutes; for example, it can be about 5 minutes.

[0064] According to some embodiments of the present invention, in step S4, the pH of the raffinate phase E is adjusted to 9-10 with aqueous ammonia.

[0065] According to some embodiments of the present invention, in step S4, the concentration of aqueous ammonia is 2-3 mol / L.

[0066] Adjusting the solution pH to 9-10 with ammonia water has a high selective extraction capacity for Co, and the single-stage extraction rate of Co is >95%, and within this pH range, the extraction rate of Ni is less than 10%. When the solution pH is less than 9, the extraction rate of Co will drop significantly, less than 50%; when the solution pH is >10, although the extraction rate of Co is also increasing, the extraction capacity of Ni will increase with the increase of pH, and can reach nearly 40%, which is not conducive to the separation of Co and Ni.

[0067] In particular, the extraction of Ni by Cyanex 272 requires the use of NH 3 ·H 2 O is used for regulation instead of NaOH, because NaOH will cause Ni to produce Ni(OH) 3 —Plasma, even generate Ni(OH)2 In addition, the reason why pH is 9 to 10 is that under this condition, Ni 2+ It will generate Ni(NH 3 ) 2 2+ ions, can be bound by Cyanex 272 while avoiding the formation of precipitation.

[0068] According to some embodiments of the present invention, the method further comprises precipitating a nickel salt from the raffinate phase H.

[0069] According to some embodiments of the present invention, the precipitating nickel salt comprises the following steps:

[0070] The pH of the raffinate phase H is adjusted to 9-10; for example, it can be about 9;

[0071] Adjust the pH value of the aqueous phase to 9-10, and add an excess of 3-4 mol / L alkaline aqueous solution with an excess coefficient of 1.1-1.2, and stir at 50-70°C to precipitate nickel.

[0072] At the above temperature, the best precipitation effect is achieved. When the pH is too low, Ni precipitation cannot be generated. When the pH is too high, the precipitation rate is too fast, which is not conducive to the formation of stable metal crystals. Therefore, when the pH is controlled between 9 and 10, the best precipitation effect can be achieved.

[0073] According to some embodiments of the present invention, the method further comprises stripping the loaded organic phase I to obtain a stripping phase I, and precipitating a cobalt compound from the stripping phase I.

[0074] According to some embodiments of the present invention, the precipitation of the cobalt compound comprises the following steps:

[0075] The pH of the stripping phase I is adjusted to 8-10; for example, it can be about 8, 9, or 10;

[0076] A 3-4 mol / L aqueous alkali solution is added thereto with an excess coefficient of 1.1-1.2, and cobalt hydroxide is precipitated at 55-75° C. The alkali used includes at least one of sodium hydroxide and potassium hydroxide.

[0077] The above temperature is conducive to the formation of metal precipitation, while avoiding excessive dissolution of metal in the solution. pH = 8-10 is conducive to Co 2+ The pH value has a great influence on the cobalt precipitation rate. With the increase of pH value, the cobalt precipitation rate increases accordingly. When pH>10, the increase of cobalt precipitation rate slows down. This is because too high pH is not conducive to the precipitation reaction.

[0078] According to some embodiments of the present invention, in the stripping step, the O / A value is 0.5 to 5:1; for example, it may be specifically about 1:1.

[0079] According to some embodiments of the present invention, the aqueous phase used for the stripping of the loaded organic phase is an acid aqueous solution of 0.1 to 3 mol / L. The acid used specifically includes at least one of sulfuric acid, hydrochloric acid and nitric acid. The specific concentration can be about 0.5 mol / L, 1 mol / L, 1.5 mol / L, 2 mol / L or about 2.5 mol / L.

[0080] More specifically, the water phase used in the stripping of the loaded organic phase is a 2-3 mol / L hydrochloric acid aqueous solution.

[0081] Alternatively, the aqueous phase used in the stripping of the loaded organic phase is a 0.1-3 mol / L aqueous sulfuric acid solution, and the specific concentration may be about 1 mol / L, 2 mol / L or about 2.5 mol / L.

[0082] Alternatively, the aqueous phase used in the stripping of the loaded organic phase is a 0.1-3 mol / L aqueous nitric acid solution, and the specific concentration may be about 1 mol / L, 2 mol / L or about 2.5 mol / L.

[0083] According to some embodiments of the present invention, the stripping of the loaded organic phase includes sequential mixing and phase separation. The mixing time is 10 to 20 minutes; for example, it can be about 15 minutes; the mixing is performed by mechanical stirring. The phase separation method includes standing and centrifugation; if centrifugation is used, the time is 3 to 8 minutes; for example, it can be about 5 minutes.

[0084] According to some embodiments of the present invention, the stripping of the loaded organic phase includes sequential mixing and phase separation. The mixing time is 10 to 20 minutes; for example, it can be about 15 minutes; the mixing is performed by mechanical stirring. The phase separation method includes standing and centrifugation; if centrifugation is used, the time is 3 to 8 minutes; for example, it can be about 5 minutes.

[0085] According to some embodiments of the present invention, the mixed metal solution satisfies at least one of the following parameters:

[0086]

[0087] According to an embodiment of the second aspect of the present invention, there is provided an application of the method in hydrometallurgy.

[0088] Since the application adopts all the technical solutions of the method of the above embodiment, it has at least all the beneficial effects brought by the technical solutions of the above embodiment.

[0089] According to some embodiments of the present invention, the object of hydrometallurgy includes at least one of minerals and waste lithium-ion batteries, and is particularly aimed at waste lithium-ion battery positive electrode materials in waste lithium-ion batteries.

[0090] According to an embodiment of the third aspect of the present invention, there is provided an application of the method described in recycling of waste lithium batteries.

[0091] Since the application adopts all the technical solutions of the method of the above embodiment, it has at least all the beneficial effects brought by the technical solutions of the above embodiment.

[0092] According to some embodiments of the present invention, the waste lithium battery recycling includes sequentially disassembling and sorting to obtain the waste lithium-ion battery positive electrode material, and leaching the waste lithium-ion battery positive electrode material, and treating the obtained leachate by the method.

[0093] If not otherwise specified, the reagent used to adjust pH in the present invention is at least one of 2 mol / L sodium hydroxide aqueous solution, 2 mol / L ammonia water and 2-4 mol / L hydrochloric acid aqueous solution. If ammonia water is used to adjust pH, ammonia water also has a complexing effect, so the precipitation of transition metal ions can be avoided under higher pH conditions.

[0094] Unless otherwise specified, the diluent used in the organic phase of the present invention is kerosene, which can improve the physical properties of the organic phase, specifically change the viscosity, fluidity and density, increase the density difference between the organic phase and the aqueous phase, and be more conducive to phase separation during the extraction / stripping process.

[0095] If there is no special explanation, the actual meaning of “about” in the present invention is that the error is allowed to be within the range of ±2%, for example, about 100 is actually 100±2%×100.

[0096] Unless otherwise specified, “between” in the present invention includes the number itself, for example, “between 2 and 3” includes the endpoint values ​​2 and 3.

[0097] Other features and advantages of the present invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0098] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0099] Figure 1 It is a schematic diagram of the process of Example 1 of the present invention. DETAILED DESCRIPTION

[0100] The following will be combined with the embodiments to clearly and completely describe the concept of the present invention and the technical effects produced, so as to fully understand the purpose, characteristics and effects of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, other embodiments obtained by those skilled in the art without creative work are all within the scope of protection of the present invention.

[0101] In the description of the present invention, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0102] Example 1

[0103] refer to Figure 1 This example provides a method for separating Li / Co / Mn / Ni in a solution, and applies it to waste lithium batteries, especially the recovery of waste lithium battery positive electrode materials. The specific steps are as follows:

[0104] S1. Take 2g of waste lithium battery powder in a three-necked flask and add 100mL of 4M H 2 SO 4 and 10 vol% H 2 O 2 The mixed solution (a mixed solution formed by 30% hydrogen peroxide in a volume ratio of 10:100) was heated in a constant temperature water bath at 80°C with stirring for 1 hour for leaching. The solution after the reaction was filtered to remove the powder to obtain an ion-rich filtrate A. The concentrations of various ions in the leaching solution are shown in Table 1.

[0105] Table 1 Composition of the mixed metal solution used in Example 1

[0106] Li Co Mn Ni Ion concentration (mg / L) 1423.46 2365.08 3658.71 6149.35

[0107] Take 10 mL of filtrate A, adjust pH to 8 with 2 mol / L NaOH and place in a centrifuge tube, add 10 mL of D2EHPA extractant (the diluent is kerosene, and the volume fraction of the extractant is 10%, i.e. 1 mL of D2EHPA and 9 mL of kerosene), and perform Mn / Co / Ni extraction by magnetic stirring for 15 min at room temperature. After the extraction, place the centrifuge tube in a centrifuge and centrifuge for 5 min before taking it out, separate the organic phase and the aqueous phase, and obtain a loaded organic phase B containing Co / Mn / Ni and a raffinate phase C containing Li; in order to ensure the purity of the extraction, a three-stage extraction is performed at this stage;

[0108] Lithium salt precipitation: Take the raffinate phase C, adjust the pH of the aqueous phase to 11.5 with 2 mol / L NaOH, and add 13 mL of saturated Na 2 CO 3 The solution (excess coefficient is 1.3) was stirred at 85°C for precipitation, and then filtered and dried to obtain white Li 2 CO 3 powder;

[0109] S2. Stripping loaded organic phase B: Take 10mL 2mol / LH 2 SO 4 Add to organic phase B, stir magnetically for 10 min at room temperature to perform Co / Mn / Ni stripping, after stripping, place the centrifuge tube in a centrifuge for 5 min, take it out, separate the organic phase and the aqueous phase, and obtain stripping phase D containing Mn / Co / Ni;

[0110] S3. Second stage extraction: 10 mL of stripping phase D was taken, pH=2 was adjusted with 2 mol / L NaOH, and then placed in a centrifuge tube, 30 mL of P507 extractant (the diluent was kerosene, and the volume fraction of the extractant was 60%, i.e. 18 mL of P507 and 12 mL of kerosene) was added, and Mn was extracted by magnetic stirring for 15 min at room temperature. After the extraction, the centrifuge tube was placed in a centrifuge and centrifuged for 5 min, and then taken out, and the organic phase and the aqueous phase were separated to obtain a raffinate phase E containing Co / Ni and an organic phase F containing Mn; in order to ensure the purity of the extraction, a three-stage extraction was performed in this stage;

[0111] Stripping loaded organic phase F: Take 20mL 2mol / LH 2 SO 4 Add to the organic phase F, stir magnetically for 10 minutes at room temperature to perform Mn stripping, after stripping, place the centrifuge tube in a centrifuge for 5 minutes, take it out, separate the organic phase and the aqueous phase, and obtain the aqueous phase G containing Mn;

[0112] Precipitation of manganese salt: Take the aqueous phase G containing Mn, adjust the pH of the aqueous phase to 10 with 2 mol / L NaOH, and add 24 mL of 3 mol / L NaOH solution (excess coefficient is 1.2), stir at 60 ° C for precipitation, filter and dry after stirring to obtain white Mn (OH) 2 powder;

[0113] S4. Take the remaining phase E and use 2 mol / L NH 3 ·H 2 O was adjusted to pH = 9 and placed in a centrifuge tube, 10 mL of Cyanex 272 extractant (the diluent was kerosene, and the volume fraction of the extractant was 30%, i.e. 3 mL Cyanex 272 and 7 mL kerosene) was added, and Co was extracted by magnetic stirring for 15 min at room temperature. After the extraction, the centrifuge tube was placed in a centrifuge and centrifuged for 5 min, and then taken out, and the organic phase and the aqueous phase were separated to obtain the aqueous phase H containing Ni and the organic phase I containing Co; in order to ensure the purity of the extraction, three-stage extraction was performed at this stage;

[0114] Stripping loaded organic phase I: Take 10mL 2mol / LH 2 SO 4 Add to the organic phase I, stir magnetically for 10 min at room temperature to perform Co stripping, after stripping, place the centrifuge tube in a centrifuge for 5 min, take it out, separate the organic phase and the aqueous phase, and obtain the aqueous phase J containing Co;

[0115] Precipitation of cobalt salt: Take the aqueous phase J after stripping and separation, adjust the pH of the aqueous phase to 8.5 with 2 mol / L NaOH, and add an excess of 11 mL 4 mol / L NaOH solution (excess coefficient is 1.1), stir at 65 ° C for precipitation, filter and dry after stirring to obtain rose red Co(OH) 2 powder;

[0116] Precipitation of nickel salt: Take the raffinate phase H, adjust the pH of the aqueous phase to 9 with 2 mol / L NaOH, add 11 mL of 4 mol / L NaOH solution (excess coefficient is 1.1), stir at 65 °C for precipitation, filter and dry after stirring to obtain green Ni(OH) 2 powder.

[0117] The collected product was weighed after drying and analyzed for product purity; and the leaching liquid was analyzed for Li + / Co 2+ / Mn 2+ / Ni 2+ The concentration of Li / Co / Mn / Ni in the ion-rich filtrate A is measured using an ICP-OES spectrometer.

[0118] The analysis results are as follows: 2 CO 3 The product purity reaches 98.0%, and the recovery rate of valuable metal Li reaches 98.5%; Mn(OH) 2 The product purity reaches 97.0%, and the recovery rate of valuable metal Mn can reach 97.0%; Co(OH) 2 The product purity reached 96.5%, and the recovery rate of valuable metal Co reached 97.0%; NiCO 3 The product purity is 99.0%, and the recovery rate of valuable metal Ni is 96.0%.

[0119] Example 2

[0120] This example provides a method for separating Li / Co / Mn / Ni in a solution, and applies it to waste lithium batteries, especially the recovery of the positive electrode materials of waste lithium batteries. The specific steps are different from those in Example 1 in that:

[0121] (1) In step S1, the volume fraction of DE2HPA used in the organic phase A is different, as follows:

[0122] Take 10 mL of solution A after leaching in step S1, adjust the pH to 8 with 2 mol / L NaOH and place it in a centrifuge tube, add 10 mL of D2EHPA extractant (the diluent is kerosene, and the volume fraction of the extractant is 20%, i.e. 2 mL of D2EHPA and 8 mL of kerosene), and perform Mn / Co / Ni extraction by magnetic stirring for 15 min at room temperature. After the extraction, place the centrifuge tube in a centrifuge and centrifuge for 5 min before taking it out, separate the organic phase and the aqueous phase, and obtain an organic phase B containing Co / Mn / Ni and an aqueous phase C containing Li; in order to ensure the purity of the extraction, three-stage extraction is performed at this stage.

[0123] Example 3

[0124] This embodiment provides a method for separating Li / Co / Mn / Ni in a solution, and applies the method to waste lithium batteries, especially the recovery of the positive electrode materials of waste lithium batteries. The specific steps are different from those in Embodiment 1 in that:

[0125] In step S3, different volumes of P507 are added (i.e. different extraction O / A ratios), as follows:

[0126] Take 10 mL of the aqueous phase D after the first stage stripping in step S4, adjust the pH to 2 with 2 mol / L NaOH and place it in a centrifuge tube, add 20 mL of P507 extractant (the diluent is kerosene, and the volume fraction of the extractant is 60%, i.e., 12 mL of P507 and 8 mL of kerosene), and perform Mn extraction by magnetic stirring for 15 min at room temperature. After the extraction, place the centrifuge tube in a centrifuge and centrifuge for 5 min, then take it out, separate the organic phase and the aqueous phase, and obtain an aqueous phase E containing Co / Ni and an organic phase F containing Mn. In order to ensure the purity of the extraction, three-stage extraction is performed in this stage.

[0127] Example 4

[0128] This example provides a method for separating Li / Co / Mn / Ni in a solution, and applies it to waste lithium batteries, especially the recovery of the positive electrode materials of waste lithium batteries. The specific steps are different from those in Example 1 in that:

[0129] In step S4, the pH of the aqueous phase E after the second stage extraction and separation is adjusted differently, specifically as follows:

[0130] The third stage of extraction: Take the aqueous phase E after the second stage of extraction and separation in step S5, and use 2 mol / L NH 3 ·H 2 After adjusting the pH to 10, the mixture was placed in a centrifuge tube, 10 mL of Cyanex 272 extractant (the diluent was kerosene, and the volume fraction of the extractant was 30%, i.e., 3 mL of Cyanex 272 and 7 mL of kerosene) was added, and Co was extracted by magnetic stirring for 15 min at room temperature. After the extraction, the centrifuge tube was placed in a centrifuge and centrifuged for 5 min, then taken out, and the organic phase and the aqueous phase were separated to obtain an aqueous phase H containing Ni and an organic phase I containing Co. In order to ensure the purity of the extraction, three-stage extraction was performed in this stage.

[0131] Comparative Example 1

[0132] This example provides a method for separating Li / Co / Mn / Ni in a solution, which is different from Example 1 in that:

[0133] In step S1, the composition of the D2EHPA extractant is 5 mL of D2EHPA and 5 mL of kerosene.

[0134] Comparative Example 2

[0135] This example provides a method for separating Li / Co / Mn / Ni in a solution, which is different from Example 1 in that:

[0136] In step S3, 10 mL of P507 extractant (the diluent is kerosene, and the volume fraction of the extractant is 60%, namely 6 mL of P507 and 4 mL of kerosene) is added to the D solution.

[0137] Comparative Example 3

[0138] This example provides a method for separating Li / Co / Mn / Ni in a solution, which is different from Example 1 in that:

[0139] In step S4, the pH of the aqueous phase E after the second stage extraction and separation is adjusted to 5.

[0140] Comparative Example 4

[0141] This example provides a method for separating Li / Co / Mn / Ni in a solution, which is different from Example 1 in that:

[0142] In step S1, the composition of the extractant is 1 mL [C 2 min][NTf 2 ](CAS:174899-82-2) extractant and 9mL of kerosene.

[0143] Test Case

[0144] This example tests the quality and purity of lithium carbonate, manganese carbonate, nickel carbonate and cobalt hydroxide obtained in the examples and comparative examples; and calculates the yields of lithium, nickel, cobalt and manganese. The purity test method is to dissolve the corresponding solid product, use ICP-OES to test the concentration of lithium, nickel, cobalt or manganese therein, and calculate the ratio of the concentration to the theoretical concentration, which is the purity (the purity of the corresponding compound).

[0145] The test results of the above items are shown in Table 3.

[0146] Table 3 Purity of the products obtained in the examples and comparative examples, and the yields of lithium, nickel, cobalt and manganese

[0147]

[0148] By comparing the results of Examples 1 to 4, it can be seen that within the scope provided by the present invention, by changing the type, proportion, composition of the mixed metal solution and even some process parameters of the extractant, a product with higher purity can be obtained, and the yield of the corresponding metal is higher; specifically, the purity of lithium carbonate is ≥97.5%, which can reach 98.0% in actual production; the yield of lithium is ≥98.0%, which can reach 98.5% in actual production; the purity of cobalt hydroxide is ≥96.5%, which can reach 97.0% in actual production; the yield of cobalt is ≥97.0%, which can reach 97.5% in actual production; the purity of manganese carbonate is ≥97.0%, which can reach 97.5% in actual production; the yield of manganese is ≥97.0%, which can reach 97.5% in actual production; the purity of nickel carbonate is ≥99.0%, which can reach 99.5% in actual production; the yield of nickel is ≥96.0%, which can reach 96.5% in actual production.

[0149] By comparing Example 1 and Comparative Example 1, it can be seen that if the proportion of the composite extractant in step S2 is not within the range required by the present invention, the extractant also has a high extraction rate for Li, and the extraction rate can reach 40%, resulting in the inability to separate Co, Mn, Ni and Li, reducing the recovery rate and purity of lithium, and will also lead to the subsequent inability to separate the metals one by one normally, and the purity of the corresponding metal compounds will also decrease, especially having a significant impact on nickel.

[0150] By comparing Example 1 and Comparative Example 2, it can be seen that if the volume of the extractant P507 in step S5 is not within the required range of the present invention, the extraction rate of manganese is reduced to less than 50%, resulting in a decrease in the recovery rate of Mn, and incomplete separation of manganese, affecting the subsequent separation of Co and Ni. Since Cyanex 272 also has an extraction effect on Mn in the presence of Mn, the recovery rate of Co and Ni and the purity of the compound are reduced.

[0151] By comparing Example 1 and Comparative Example 3, it can be seen that if the pH of the aqueous phase E after the second stage extraction and separation in step S8 is not within the range of 9 to 10, the extraction rate of Co by Cyanex 272 is reduced to less than 5%, and Co and Ni cannot be separated normally, and effective recovery of Co and Ni cannot be achieved.

[0152] By comparing Example 1 with Comparative Example 4, it can be seen that if the extractant used in the present invention is replaced with [C 2 min][NTf 2 ], even if [C 2 min][NTf 2 ] has the ability to extract lithium, but it also has good extraction capabilities for Co, Mn, and Ni, which makes it impossible to separate the four metal ions and achieve metal recovery.

[0153] It can also be seen from the processes of the embodiments and comparative examples that in the method provided by the present invention, the implementation temperature of all procedures is less than 100° C., and the process is safe, reliable and highly stable.

[0154] In summary, in the method provided by the present invention, through the design of steps and parameters, Li / Co / Mn / Ni can be recovered separately, and the purity of the recovered products is high, and the operation is simple, safe and reliable. Because of the above advantages, the method provided by the present invention is expected to be widely used in hydrometallurgy, especially in the recovery of waste lithium-ion batteries.

[0155] The above is a detailed description of the embodiments of the present invention, but the present invention is not limited to the above embodiments. Various changes can be made within the knowledge of ordinary technicians in the relevant technical field without departing from the purpose of the present invention. In addition, the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

Claims

1. A method for separating Li / Co / Mn / Ni in a mixed metal solution, characterized in that: The mixed metal solution contains Li, Co, Mn and Ni elements; The method comprises the following steps: S1. Extracting the transition metal ions in the mixed metal solution with a solution containing an extractant D2EHPA to obtain a loaded organic phase B and a raffinate phase C; The volume percentage of the extractant D2EHPA solution is 5% to 30%; S2. stripping the loaded organic phase B to obtain a stripping phase D; S3. Extracting the stripping phase D with a solution containing an extractant P507 to obtain a raffinate phase E and a loaded organic phase F; The volume percentage of the solution of the extractant P507 is 50-90%; S4. After adjusting the pH of the raffinate phase E to 9-10, extracting the raffinate phase E with a solution containing the extractant Cyanex 272 to obtain a raffinate phase H and a loaded organic phase I.

2. The method according to claim 1, characterized in that The method further comprises the step of precipitating lithium carbonate from the raffinate phase C; and / or the step of precipitating lithium carbonate comprises: adjusting the pH of the raffinate phase C to 11-12, and using a saturated carbonate aqueous solution to precipitate lithium.

3. The method according to claim 1, characterized in that The method further comprises: a step of stripping the loaded organic phase F to obtain a stripping phase G; and a step of precipitating a manganese salt from the stripping phase G; and / or the step of precipitating a manganese salt comprises: adjusting the pH of the stripping phase G to 9-10 and precipitating manganese at 50-70°C.

4. The method according to claim 1, characterized in that: The method further comprises precipitating a nickel salt from the raffinate phase H; and / or, the method further comprises stripping the loaded organic phase I to obtain a stripping phase I, and precipitating a cobalt compound from the stripping phase I.

5. The method according to any one of claims 1 to 4, characterized in that: The mixed metal solution satisfies at least one of the following parameters: (A) Li 1~2g / L; (B) Co 2-3 g / L; (C) Mn 3~4.5g / L; (D)Ni 6~7g / L.

6. The method according to any one of claims 1 to 4, characterized in that: In step S1, in the extraction step with the extractant D2EHPA solution: the O / A value is 0.5-1.5:1; and / or, it also includes controlling the pH of the mixed metal solution to be 2-8 before extraction.

7. The method according to any one of claims 1 to 4, characterized in that: Step S3 further includes controlling the pH of the stripping phase D to 1 to 4 before the extraction; and / or, in step S3, in the extraction step with the extractant P507 solution: the O / A value is 2 to 4:

1.

8. The method according to any one of claims 1 to 4, characterized in that: In step S4, in the extraction step using a solution containing the extractant Cyanex272, the O / A value is 0.5 to 3:

1.

9. Use of the method according to any one of claims 1 to 8 in hydrometallurgy.

10. Use of the method according to any one of claims 1 to 8 in the recycling of waste lithium batteries.

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