Method for separating li / co / mn / ni in mixed metal solution and application thereof

Abstract

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

Description

TECHNICAL FIELD

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

[0002] With the growing demand for clean energy, 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 market size of lithium-ion batteries has grown at an average annual rate of about 20% in the past decade, and is expected to exceed $100 billion by 2025. However, with the large-scale use of lithium-ion batteries, the number of waste lithium batteries has also increased 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 value of cobalt contained in each ton of waste lithium batteries is about 100,000 yuan, and the value of lithium is about 50,000 yuan. Effective recovery of these metal resources not only can reduce the dependence on primary mineral resources, but also can reduce the environmental pressure brought by mining primary minerals. In addition, harmful substances in waste lithium batteries, such as heavy metals and organic electrolytes, if discarded or improperly treated, can pollute soil, water and air, causing serious damage to the ecological environment. For example, the accumulation of heavy metals such as cobalt and nickel in the environment can cause biological toxicity and ecological system 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 situation of high dependence on foreign strategic metal resources such as cobalt and nickel can be alleviated to some extent. At the same time, by recycling waste lithium batteries, new economic growth points can be created, promoting the development of related industries, while reducing the life cycle cost of lithium batteries.

[0004] Currently, the waste lithium battery recycling industry is in a stage of rapid development. Globally, more and more enterprises 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 enterprises have obtained qualifications related to waste lithium battery recycling. In terms of recycling volume, in 2023, China's waste lithium battery recycling volume was about 500,000 tons, and is expected to exceed 1 million tons by 2025.

[0005] The current recycling technologies for lithium batteries mainly include the following: 1. Pyrometallurgy: valuable metals in waste lithium batteries are converted into alloys through high-temperature smelting, and then further separated and purified. 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 large energy consumption, and the metal recovery rate is relatively low, part of the metal may be lost in the high-temperature process, and secondary pollution may be produced; 2. Hydrometallurgy: using acid, alkali and other chemical reagents to dissolve the metals in waste lithium batteries, and then separating and recovering the metals by precipitation, extraction and other methods. The hydrometallurgical process is relatively mature, and the metal recovery rate is high, but the consumption of chemical reagents is large, and the wastewater treatment is difficult; 3. Physical separation: including crushing, screening, magnetic separation, flotation and other processes, first the waste lithium batteries are pretreated to separate different components, and then the subsequent recovery treatment is carried out. 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 realize the recovery of valuable metals in waste lithium batteries to some extent, it generally has the problems of low recovery rate, low product purity, high cost, etc. For example, the recovery rate of lithium in some technologies is less than 80%. At the same time, there are problems such as complex recycling process and tedious operation, resulting in high equipment investment, chemical reagent consumption and processing cost in the recycling process, which is not conducive to the development of the waste lithium battery recycling industry. In the existing research, SO2 and acid solution are used for two-stage leaching, and ammonia water is used to adjust the pH value to realize the separation of lithium, cobalt, manganese and nickel, and the recovery of lithium carbonate. In this process, SO2 gas is used, which is easy to cause gas leakage hazards, causing harm to the environment and human body. In addition, this process only extracts and recovers lithium, and the obtained product is Li2CO3 and NCM precursor, and Li, Co, Mn and Ni are not completely separated, which does not achieve the purpose of full recovery of lithium batteries, and has certain limitations. In another research, the shell and battery material are first separated by explosion-proof magnetic crushing and atomization spray crushing, then high-temperature negative pressure and carbonization roasting are carried out in a constant temperature roasting furnace to remove the separator and negative electrode, and a centrifugal pulverizer is used to separate the shell and positive electrode material. Using the characteristics of the positive electrode, H2SO4 and sodium sulfite are added to leach, the pH value of the leaching solution is adjusted, and impurities are removed to obtain high-purity nickel sulfate and cobalt sulfate solution with impurities ≤2.0 mg / L. However, manganese is not recovered, causing a certain waste of resources. Some research uses sulfuric acid and reducing agent to leach the disassembled, crushed and discharged waste lithium batteries, and then gradually removes and recovers copper, cobalt, manganese and nickel, and finally recovers lithium, resulting in a long route for recovering lithium, which is easy to cause loss of lithium and low recovery rate.

[0006] In summary, in the related technologies for recycling waste lithium ion batteries, or the recovery of metal elements is not comprehensive, or the metal recovery rate is low. SUMMARY

[0007] The present application aims to at least solve one of the technical problems existing in the prior art. To this end, the present application 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 an aqueous solution.

[0008] The present application also provides the use of the above method.

[0009] According to a first aspect of the present application, 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 transition metal ions in the mixed metal solution with an extractant D2EHPA solution 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 to 90%;

[0016] S4. Adjusting the pH of the raffinate phase E to 9 to 10 and then extracting the raffinate phase E with a solution containing an 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, realizing 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, realizing 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, realizing the separation of Ni and Co.

[0022] According to the method of the embodiment of the present application, at least the following beneficial effects are achieved:

[0023] (1) The present application can realize the extraction and separation of Li / Mn / Co / Ni metals gradually by using 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 gradually. In the first stage, D2EHPA extractant is used to selectively bind with Co / Mn / Ni, so that Co / Mn / Ni is extracted from the leaching solution containing Li / Co / Mn / Ni into the organic phase, realizing the separation from Li, and Li remains in the aqueous solution (the raffinate phase C); in the second stage, P507 is used to selectively bind with Mn under specific conditions, so that Mn is extracted from the Co / Mn / Ni mixed solution into the organic phase, realizing the separation from Co / Ni, and Co / Ni remains in the aqueous solution; in the third stage, the purpose is to recover Co: Cyanex 272 is used to selectively bind with Co under specific conditions, so that Co is extracted from the Co / Ni mixed solution into the organic phase, realizing the separation from Ni. This process has the advantages of high extraction rate, strong selectivity, simple process, recyclable extractant, low cost, easy operation, etc.

[0024] (2) In step S1, D2EHPA can efficiently extract Co / Mn / Ni under the above volume percentage, and the extraction rate of metals is all ≥95%, while the extraction rate of Li is less than 10%, so that Co / Mn / Ni can be separated from Li. When the volume ratio of D2EHPA extractant in the diluent is <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 from Li; when the volume ratio of D2EHPA extractant in the diluent is >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 50% at most.

[0025] (3) In step S3, P507 can efficiently extract Mn in the above-mentioned volume percentage, the extraction rate of the metal is all ≥95%, and the extraction rate of Co / Ni is all <10%, so that Mn can be separated from Co / Ni. When the volume ratio of P507 extractant in the diluent is <50%, the extraction rate of Mn is greatly reduced, when the volume fraction of 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 distribution of external electrons of metal ions, and the extraction order is: Mn>Co>Ni. Therefore, only by controlling the volume fraction of P507 in the above-mentioned range, can the extraction separation of P507 for Mn be realized.

[0026] (4) In step S4, by adjusting the pH of the raffinate phase E to pH=9-10, the Cyanex 272 extractant has high selective extraction capacity for Co, the single-stage extraction rate for Co is >95%, and in this pH range, the extraction rate for Ni is less than 10%. When the solution pH is <9, the extraction rate for Co will be greatly reduced, less than 50%; when the solution pH is >10, although the extraction rate for Co is also increasing, but at the same time, the extraction capacity for Ni will increase with the increase of pH, which can reach nearly 40%, which is not conducive to the separation between Co and Ni.

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

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

[0029] According to some embodiments of the present application, the mixed metal solution is a leaching solution of waste lithium ion positive electrode material, or a leaching solution of a mineral.

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

[0031] The solid-liquid ratio of the mixed leaching is 1 g: 20-100 mL; for example, it can be about 1 g: 40 mL, 1 g: 50 mL or about 1 g: 60 mL; thus, there is enough acid to react with the waste lithium ion positive electrode material, and within this range, there are 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 in the mixed leaching includes at least one of HCl, H2SO4 and HNO3;

[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 in the acid is 5-20%. For example, it can be about 8%, 9%, 10% or about 15%.

[0036] The acid and hydrogen peroxide mixed solution with the above concentration helps to oxidize the metal, so that the metal is converted 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, it can be about 40°C, 60°C or about 80°C. The increase of temperature can increase the molecular kinetic energy, accelerate the molecular motion and thus promote the diffusion, which is beneficial to leaching. Within this temperature range, the evaporation speed of the aqueous phase in the mixed leaching is controllable, and the aqueous phase is prevented from being evaporated dry.

[0038] The time length of the mixed leaching is 1-2 h; for example, it can be about 1.5 h. It is found that when the leaching time is about 1 h, the leaching rate begins to balance, and generally the leaching amount is proportional to the leaching time, but when the diffusion reaches the balance, the time is no longer effective. In order to ensure that the leaching reaction is completely leached, all the metals in the metal powder are leached as much as possible, and the metal is fully recovered. Within this time range, the leaching efficiency and production efficiency can be ensured, and the child can be prevented from being leached.

[0039] During the mixed leaching, Li / Co / Mn / Ni can be converted from the metal oxidation state (or other solid state) to the ionic state dissolved in water, and transferred from the solid to the leaching solution; the addition of the 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 application, the waste lithium-ion positive electrode material comprises at least one of lithium cobaltate, lithium nickelate, lithium nickel cobalt manganese oxide, lithium nickel cobalt oxide and lithium cobalt manganese oxide. Among them, the ratio of nickel cobalt manganese in lithium nickel cobalt manganese oxide is not strictly limited, in other words, no matter which waste lithium-ion positive electrode material, it does not affect the implementation of the method provided by the present application.

[0041] According to some embodiments of the present application, in the extraction step with D2EHPA-containing extractant solution in step S1: the O / A value is 0.5-1.5:1. 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 organic phase is greater than 1.5 times the aqueous phase, the extraction rate of D2EHPA to 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, the extraction rate of Co / Mn will be greatly reduced, among them, the extraction rate of Co will be reduced to below 60%, and the extraction rate of Mn will be reduced to only 35%, which cannot achieve good separation of Co / Mn / Ni and Li.

[0043] According to some embodiments of the present application, in step S1, the pH of the mixed metal solution is adjusted to 2-8 before extraction. For example, it can be about 2, 3, 4, 5, 6, 7, 8.

[0044] In step S1, the solution pH is adjusted by alkali. The reason is that the aqueous solution after leaching is strongly acidic, and the aqueous solution with too much acid causes the organic solvent to fail, which is not conducive to extraction. When the solution pH is 2-8, the extraction rate of D2EHPA extractant to Mn / Co / Ni is all >95%, and the extraction rate to Li is <5%. When the pH is too large, the solution is strongly basic, and the metal ions in the solution will form a precipitate, which is not conducive to extraction. This is because between pH=2-8, the metal ion species distribution is conducive to the valence bond combination of metal compound ions and extractants, so that Mn / Co / Ni can be extracted by D2EHPA.

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

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

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

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

[0049] Under the above conditions, due to the inverse temperature effect of the solubility of lithium carbonate, the content of lithium carbonate in the product generally tends to increase with the increase of the precipitation temperature. When the temperature is 80-90°C, the pH is 11-12, and the precipitation rate of lithium carbonate is optimal, under which the generated lithium carbonate is stable; and the excess saturated Na2CO3 is conducive to the full reaction of Li ions to generate lithium carbonate precipitate.

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

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

[0052] The reason is that when the pH of the solution is 1-4, the extraction rate of P507 extractant for Mn is greater than 80%, the extraction rate of P507 for Mn at the optimal volume fraction and the optimal pH can reach 95%, the extraction rate for Co is less than 10%, and there is basically no extraction for Ni; and when the pH increases, the extraction rate of P507 for Co / Ni increases, which is not conducive to the separation of Mn and Co / Ni. Too high pH will also cause metal precipitation, which is not conducive to extraction. The principle is that when the pH is 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 ion species distribution will change, which is not conducive to the extraction of Mn by the organic phase.

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

[0054] The O / A volume ratio is between 2 / 1 and 4 / 1, because when the organic phase is greater than 4 times the aqueous phase, the extraction rate of P507 to Co 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, the extraction rate of Mn will also be lower 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 the organic phase is too much, it will cause the viscosity of the extraction system to rise, thereby hindering the mass transfer collision between the molecules and the ions, which is not conducive to the combination between the organic molecules and the metal ions.

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

[0056] According to some embodiments of the present application, 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 application, the step of precipitating the manganese salt comprises: adjusting the pH of the stripping phase G to 9-10, and adding an excess of 2-3 mol / L aqueous alkali solution, the excess coefficient being 1.1-1.2, and precipitating manganese at 50-70°C.

[0058] In the step of precipitating manganese, the temperature is 50-70°C, which is conducive to the precipitation of the metal. Too low a temperature is not conducive to the dissolution of manganese hydroxide in the aqueous solution, and too high a temperature will not be conducive to the precipitation of the metal. The pH is 9-10, and at this pH, Mn 2+ can combine with OH - to form Mn(OH)2. Too low a pH cannot form manganese hydroxide precipitate, and too high a pH will affect the precipitation rate.

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

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

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

[0062] The extraction rate of Cyanex 272 for Co at the above concentration is all > 95%, the extraction rate of Cyanex 272 for Co at the optimal extraction volume is all ≥ 98%, and the extraction rate of Ni is all < 10%, so that Co and Ni can be separated, and too low volume fraction will result in the extraction rate of Cyanex 272 for Co being reduced, which is difficult to separate from Ni, and when the volume fraction of Cyanex 272 is higher than 90%, the extraction rate of Ni is also increased, 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 extraction capacity for Co / Ni under certain conditions, and the extraction capacity order is Co > Ni, which is due to the difference in the combination capacity of Cyanex 272 caused by the difference in the outer electron arrangement of Co and Ni. Therefore, the extraction capacity of Cyanex 272 for Ni will increase with the increase of the volume fraction, and it is necessary to control a certain volume fraction so that Cyanex 272 has extraction capacity for Co and does not have extraction behavior for Ni. 2+ and Ni 2+ Therefore, the extraction capacity of Cyanex 272 for Ni will increase with the increase of the volume fraction, and it is necessary to control a certain volume fraction so that Cyanex 272 has extraction capacity for Co and does not have extraction behavior for Ni.

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

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

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

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

[0067] In particular, Cyanex 272 needs to use NH3·H2O for adjustment, not NaOH, because NaOH will cause Ni to produce Ni(OH)3— plasma, even generate Ni(OH)2 and other precipitates, which is not conducive to extraction. In addition, the reason for pH = 9-10 is that under this condition, Ni2+ Ni(NH3)2 2+ ions, Cyanex 272 can be combined while avoiding the generation of precipitates.

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

[0069] According to some embodiments of the present application, the step of precipitating the nickel salt comprises:

[0070] adjusting the pH of the raffinate phase H to 9-10; for example, specifically, about 9;

[0071] adjusting the pH of the aqueous phase to 9-10, adding an excess of 3-4 mol / L aqueous alkali solution, with an excess coefficient of 1.1-1.2, and stirring at 50-70°C to precipitate the nickel.

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

[0073] According to some embodiments of the present application, 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 application, the step of precipitating the cobalt compound comprises:

[0075] adjusting the pH of the stripping phase I to 8-10; for example, specifically, about 8, 9, or 10;

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

[0077] The above temperature is conducive to the generation of metal precipitates, while avoiding excessive dissolution of the metal in the solution, and the pH=8-10 is conducive to the hydrolysis of Co 2+ The pH value has a large effect on the cobalt precipitation rate, and as the pH value increases, the cobalt precipitation rate also increases. When the pH>10, the increase in the cobalt precipitation rate slows down, because too high a pH is not conducive to the precipitation reaction.

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

[0079] According to some embodiments of the present application, the stripping of the loaded organic phase is performed using an aqueous phase of 0.1-3 mol / L of an acid. The acid used can specifically include at least one of sulfuric acid, hydrochloric acid and nitric acid. The 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] Further specifically, the stripping of the loaded organic phase is performed using an aqueous phase of 2-3 mol / L of hydrochloric acid.

[0081] Alternatively, the stripping of the loaded organic phase is performed using an aqueous phase of 0.1-3 mol / L of sulfuric acid. The concentration can be about 1 mol / L, 2 mol / L or about 2.5 mol / L.

[0082] Alternatively, the stripping of the loaded organic phase is performed using an aqueous phase of 0.1-3 mol / L of nitric acid. The concentration can be about 1 mol / L, 2 mol / L or about 2.5 mol / L.

[0083] According to some embodiments of the present application, the stripping of the loaded organic phase includes mixing and phase separation performed in sequence. The mixing is performed for 10-20 min, for example, about 15 min. The mixing is performed by mechanical stirring. The phase separation is performed by standing and centrifugation. If the centrifugation is used, the time is 3-8 min, for example, about 5 min.

[0084] According to some embodiments of the present application, the stripping of the loaded organic phase includes mixing and phase separation performed in sequence. The mixing is performed for 10-20 min, for example, about 15 min. The mixing is performed by mechanical stirring. The phase separation is performed by standing and centrifugation. If the centrifugation is used, the time is 3-8 min, for example, about 5 min.

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

[0086]

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

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

[0089] According to some embodiments of the present application, the object of the hydrometallurgy includes at least one of a mineral and a waste lithium ion battery. It is particularly aimed at waste lithium ion battery cathode material in waste lithium ion batteries.

[0090] According to the third aspect of the present application, the method is applied to the recycling of waste lithium batteries.

[0091] The application adopts all the technical solutions of the above-mentioned method, and thus has all the beneficial effects brought by the technical solutions of the above-mentioned embodiments.

[0092] According to some embodiments of the present application, the recycling of waste lithium batteries comprises disassembling, sorting and obtaining waste lithium ion battery positive materials, and leaching of the waste lithium ion battery positive materials in sequence, and the leaching solution obtained by the method is treated.

[0093] Unless otherwise specified, the reagent for adjusting pH in the present application 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 complexing effect, so that 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 application is kerosene. Thus, the physical properties of the organic phase can be improved, and the viscosity, flowability and density are changed, the density difference between the organic phase and the aqueous phase is enlarged, which is more conducive to the phase separation in the extraction / stripping process.

[0095] Unless otherwise specified, the meaning of "about" in the present application actually means that the allowable error is within ±2%, for example, about 100 actually means 100±2%×100.

[0096] Unless otherwise specified, "between" in the present application includes the number, for example, "between 2-3" includes the end point values 2 and 3.

[0097] Other features and advantages of the present application will be set forth in the following description, and in part will become apparent from the description, or will be learned by practice of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0098] The above and / or additional aspects and advantages of the present application will become apparent and be readily understood from the following description, taken in conjunction with the accompanying drawings, in which:

[0099] Figure 1 is a flowchart of embodiment 1 of the present application. DETAILED DESCRIPTION

[0100] The following will describe the concept and technical effects of the present invention clearly and completely with reference to embodiments, so as to fully understand the purpose, features and effects of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention.

[0101] In the description of this invention, the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0102] Example 1

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

[0104] S1. Take 2g of waste lithium battery powder into a three-necked flask, add 100mL of a mixed solution of 4M H2SO4 and 10vol% H2O2 (a mixed solution of 30% hydrogen peroxide at a volume ratio of 10:100), stir and heat in a constant temperature water bath at 80℃ for 1h to leach out the powder. Filter the solution after the reaction to remove the powder and obtain ion-rich filtrate A. The concentrations of each ion in the leachate 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 the pH to 8 using 2 mol / L NaOH, and place it in a centrifuge tube. Add 10 mL of D2EHPA extractant (the diluent is kerosene, and the extractant volume fraction is 10%, i.e., 1 mL D2EHPA and 9 mL kerosene). Stir magnetically at room temperature for 15 min to perform Mn / Co / Ni extraction. After extraction, centrifuge the centrifuge tube for 5 min and then remove it. Separate the organic phase and the aqueous phase to obtain a loaded organic phase B containing Co / Mn / Ni and a raffinate phase C containing Li. To ensure the purity of the extraction, this stage involves three-stage extraction.

[0108] Precipitation of lithium salt: take the raffinate phase C, adjust the water phase pH = 11.5 with 2 mol / L NaOH, and add 13 mL of saturated Na2CO3 solution (excess coefficient is 1.3), stir at a temperature of 85°C to precipitate, filter and dry after stirring to obtain white Li2CO3 powder;

[0109] S2. Stripping of the loaded organic phase B: take 10 mL of 2 mol / L H2SO4 and add it to the organic phase B, magnetically stir at room temperature for 10 min to strip Co / Mn / Ni, after stripping, centrifuge the tube in a centrifuge for 5 min, then take it out, separate the organic phase and the water phase to obtain the stripping phase D containing Mn / Co / Ni;

[0110] S3. Second stage extraction: take 10 mL of the stripping phase D, adjust the pH = 2 with 2 mol / L NaOH, then place it in a centrifuge tube, add 30 mL of P507 extractant (diluent is kerosene, extractant volume fraction is 60%, i.e. 18 mL of P507 and 12 mL of kerosene), magnetically stir at room temperature for 15 min to extract Mn, after extraction, centrifuge the tube in a centrifuge for 5 min, then take it out, separate the organic phase and the water phase to obtain the raffinate phase E containing Co / Ni and the organic phase F containing Mn; in order to ensure the purity of the extraction, three-stage extraction is performed in this stage;

[0111] Stripping of the loaded organic phase F: take 20 mL of 2 mol / L H2SO4 and add it to the organic phase F, magnetically stir at room temperature for 10 min to strip Mn, after stripping, centrifuge the tube in a centrifuge for 5 min, then take it out, separate the organic phase and the water phase to obtain the water phase G containing Mn;

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

[0113] S4. Take the raffinate phase E, adjust the pH = 9 with 2 mol / L NH3·H2O, then place it in a centrifuge tube, add 10 mL of Cyanex 272 extractant (diluent is kerosene, extractant volume fraction is 30%, i.e. 3 mL of Cyanex 272 and 7 mL of kerosene), magnetically stir at room temperature for 15 min to extract Co, after extraction, centrifuge the tube in a centrifuge for 5 min, then take it out, separate the organic phase and the water phase to obtain the water phase H containing Ni and the organic phase I containing Co; in order to ensure the purity of the extraction, three-stage extraction is performed in this stage;

[0114] Stripping of the loaded organic phase I: 10 mL of 2 mol / L H2SO4 was added to the organic phase I, and Co stripping was carried out under magnetic stirring at room temperature for 10 min. After the stripping was completed, the centrifuge tube was placed in a centrifuge and centrifuged for 5 min, and then the organic phase and the aqueous phase were separated to obtain the aqueous phase J containing Co;

[0115] Precipitation of cobalt salt: the aqueous phase J after stripping separation was taken, the pH of the aqueous phase was adjusted to 8.5 by using 2 mol / L NaOH, and an excess of 11 mL of 4 mol / L NaOH solution (excess coefficient 1.1) was added. The precipitation was carried out under stirring at a temperature of 65℃, and after stirring, filtration and drying, rose red Co(OH)2 powder was obtained;

[0116] Precipitation of nickel salt: the raffinate phase H was taken, the pH of the aqueous phase was adjusted to 9 by using 2 mol / L NaOH, and 11 mL of 4 mol / L NaOH solution (excess coefficient 1.1) was added. The precipitation was carried out under stirring at 65℃, and after stirring, filtration and drying, green Ni(OH)2 powder was obtained.

[0117] The obtained products were collected, dried and weighed, and the product purity was analyzed; and the leaching liquid was taken to analyze the concentration of Li + / Co 2+ / Mn 2+ / Ni 2+ (measurement of the content of elements Li / Co / Mn / Ni in the ion-rich filtrate A was carried out by using ICP-OES spectrometer).

[0118] The analysis results are as follows: the purity of Li2CO3 product is 98.0%, the recovery rate of valuable metal Li is 98.5%; the purity of Mn(OH)2 product is 97.0%, the recovery rate of valuable metal Mn can reach 97.0%; the purity of Co(OH)2 product is 96.5%, the recovery rate of valuable metal Co is 97.0%; the purity of NiCO3 product 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 is applied to waste lithium batteries, especially the recovery of positive electrode materials in waste lithium batteries. The specific steps and example 1 are different in that:

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

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

[0123] Example 3

[0124] 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 cathode materials. The specific steps are different from example 1 as follows:

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

[0126] Take 10 mL of aqueous phase D after the first stage stripping in step S4, adjust pH = 2 with 2 mol / L NaOH, and then place it in a centrifuge tube. Add 20 mL of P507 extractant (diluent is kerosene, extractant volume fraction is 60%, i.e. 12 mL of P507 and 8 mL of kerosene), and perform Mn extraction at room temperature for 15 min. After the extraction is completed, place the centrifuge tube in a centrifuge and centrifuge for 5 min, then take it out. Separate the organic phase and the aqueous phase to obtain aqueous phase E containing Co / Ni and 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 waste lithium battery cathode materials. The specific steps are different from example 1 as follows:

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

[0130] Third stage extraction: take the water phase E separated in step S5 second stage extraction, adjust pH = 10 by using 2 mol / L NH3·H2O, and then place in a centrifugal tube, add 10 mL of Cyanex 272 extractant (diluent is kerosene, and the volume fraction of the extractant is 30%, that is, 3 mL of Cyanex 272 and 7 mL of kerosene), and perform Co extraction by magnetic stirring at room temperature for 15 min, after the extraction is completed, the centrifugal tube is placed in a centrifuge for 5 min, and then taken out, and the organic phase and the water phase are separated, to obtain the water phase H containing Ni and the organic phase I containing Co; in order to ensure the purity of the extraction, three-stage extraction is performed in this stage.

[0131] Comparative example 1

[0132] This example provides a method for separating Li / Co / Mn / Ni in a solution, and the difference from example 1 is 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, and the difference from example 1 is that:

[0136] In step S3, 10 mL of P507 extractant (diluent is kerosene, and the volume fraction of the extractant is 60%, that is, 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, and the difference from example 1 is that:

[0139] In step S4, the pH of the water phase E separated in the second stage extraction is adjusted to 5.

[0140] Comparative example 4

[0141] This example provides a method for separating Li / Co / Mn / Ni in a solution, and the difference from example 1 is that:

[0142] In step S1, the composition of the extractant is 1 mL of [C2min][NTf2] (CAS: 174899-82-2) extractant and 9 mL of kerosene.

[0143] Test example

[0144] The mass, purity of lithium carbonate, manganese carbonate, nickel carbonate and cobalt hydroxide obtained in the examples and comparative examples were tested, and the yield of lithium, nickel, cobalt and manganese was calculated. The test method for purity is that after the corresponding solid product is dissolved, the concentration of lithium, nickel, cobalt or manganese is tested by ICP-OES, and the ratio of the concentration to the theoretical concentration is calculated, which is the purity (the purity of the corresponding compound).

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

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

[0147]

[0148] It can be known from the results of Comparative Examples 1-4 that within the scope provided by the present application, the type, ratio of the change extraction agent, the composition of the mixed metal solution and even part of the process parameters can all obtain products with high purity, and the yield of the corresponding metal is high. 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; and the yield of nickel is ≥96.0%, which can reach 96.5% in actual production.

[0149] It can be known from Comparative Example 1 and Comparative Example 1 that if the ratio of the complex extraction agent in step S2 is not within the scope required by the present application, the extraction agent also has a high extraction rate for Li, which can reach 40%, resulting in that it cannot separate Co, Mn, Ni and Li, reduces the recovery rate and purity of lithium, and also causes that the subsequent metals cannot be separated one by one, and the purity of the corresponding metal compounds also decreases, especially having a significant impact on nickel.

[0150] It can be known from Comparative Example 1 and Comparative Example 2 that if the volume of the extraction agent P507 in step S5 is not within the scope required by the present application, the extraction rate for manganese is reduced to less than 50%, resulting in that the recovery rate of Mn is reduced, and the separation of manganese is not complete, which affects the separation of Co and Ni. Since Cyanex 272 also has an extraction effect on Mn in the presence of Mn, the recovery rate and compound purity of Co and Ni are reduced.

[0151] From comparative example 1 and comparative example 3, if the pH of the aqueous phase E after the second stage extraction separation in step S8 is not within 9-10, the extraction rate of Cyanex 272 to Co is reduced to less than 5%, Co and Ni cannot be normally separated, and effective recovery of Co and Ni cannot be achieved.

[0152] From comparative example 1 and comparative example 4, if the extractant used in the present application is replaced by [C2min][NTf2] which has lithium extraction capacity, even if [C2min][NTf2] has extraction capacity to lithium, it also has good extraction capacity to Co, Mn and Ni, which leads to that it cannot separate the four metal ions and cannot achieve recovery of the metals.

[0153] From the processes of the examples and comparative examples, it can also be seen that in the method provided by the present application, the implementation temperature of all procedures is <100℃, the process is safe and reliable, and has high stability.

[0154] In summary, in the method provided by the present application, through the design of steps and parameters, the recovery of Li / Co / Mn / Ni can be achieved, 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 application is expected to be widely used in hydrometallurgy, especially in the recovery of waste lithium ion batteries.

[0155] The above is a detailed description in combination with the embodiments of the present application, but the present application is not limited to the above embodiments, and various changes can be made within the knowledge range of ordinary skilled persons in the art without departing from the purpose of the present application. In addition, the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

Claims

1. A method of separating Li / Co / Mn / Ni in a mixed metal solution, characterized by, The mixed metal solution contains Li, Co, Mn and Ni elements; The method comprises the following steps: S1. Controlling the pH of the mixed metal solution to be 2-8, extracting transition metal ions in the mixed metal solution with a solution containing extractant D2EHPA to obtain loaded organic phase B and raffinate phase C, precipitating lithium carbonate from the raffinate phase C, and the volume percentage of the solution containing extractant D2EHPA is 5%-30%; S2. Stripping the loaded organic phase B to obtain stripping phase D; S3. Controlling the pH of the stripping phase D to be 1-4, extracting the stripping phase D with a solution containing extractant P507 to obtain raffinate phase E and loaded organic phase F, stripping the loaded organic phase F to obtain stripping phase G, and precipitating manganese salt from the stripping phase G; The volume percentage of the solution containing extractant P507 is 50-90%; S4. After adjusting the pH of the raffinate phase E to be 9-10 with ammonia water, extracting the raffinate phase E with a solution containing extractant Cyanex 272 to obtain raffinate phase H and loaded organic phase I, precipitating nickel salt from the raffinate phase H, stripping the loaded organic phase I to obtain stripping phase I, and precipitating cobalt compound from the stripping phase I.

2. The method of claim 1, wherein, The step of precipitating lithium carbonate comprises adjusting the pH of the raffinate phase C to be 11-12 and using saturated aqueous carbonate solution to precipitate lithium.

3. The method of claim 1, wherein, The step of precipitating manganese salt comprises adjusting the pH of the stripping phase G to be 9-10 and precipitating manganese at 50-70°C.

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

5. The method according to any one of claims 1 to 3, characterized in that, In the extraction step with a solution containing extractant D2EHPA in step S1: O / A value is 0.5-1.5:

1.

6. The method of any one of claims 1-3, wherein, In the extraction step with a solution containing extractant P507 in step S3: O / A value is 2-4:

1.

7. The method of any one of claims 1-3, wherein, In the extraction step with a solution containing extractant Cyanex 272 in step S4: O / A value is 0.5-3:

1.

8. Use of the method according to any one of claims 1-7 in hydrometallurgy.

9. Use of the method according to any one of claims 1-7 in recycling of waste lithium batteries.

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