Method for manufacturing nickel-cobalt-manganese composite salt

Abstract

A method for manufacturing a composite salt of nickel, cobalt, and manganese, and a method for manufacturing a cathode active material precursor for a lithium secondary battery including same are provided, the method for manufacturing a composite salt of nickel, cobalt, and manganese comprising: preparing a black mass of a lithium secondary battery, an alloy including nickel, cobalt, and manganese separated from a spent lithium secondary battery, or a mixed metal solution including nickel, cobalt, and manganese separated from a leachate of a spent cathode material; preparing a mixture of a compound represented by Chemical Formula 1 and a compound represented by Chemical Formula 2; preparing a mixed solvent in which the mixture is saponified; obtaining a mixed organic solvent in which nickel, cobalt, and manganese are simultaneously extracted from the mixed metal solution using the mixed solvent as an extraction solvent; and adding an aqueous strong acid solution to the mixed organic solvent in which nickel, cobalt, and manganese are simultaneously extracted, to back-extract nickel, cobalt, and manganese. (Chemical formula 1) (Chemical formula 2) In chemical formula 1, R1 and R2 are each independently a C1 to C6 alkyl group, with the total number of carbon atoms of R1 and R2 accounting for 7.

Description

Method for manufacturing nickel-cobalt-manganese complex salt

[0001] The present invention relates to a method for manufacturing a nickel-cobalt-manganese composite salt, particularly a method for manufacturing a nickel-cobalt-manganese composite salt, specifically a high-purity nickel-cobalt-manganese composite salt, from black mass, alloy, or leachate generated from spent cathode material of a lithium secondary battery.

[0002] The present invention claims priority based on Korean Patent Application No. 10-2024-0191895 filed on December 19, 2024, the entire contents of said application incorporated herein by reference.

[0003] As the electric vehicle market grows rapidly, the industry for recovering valuable metals such as lithium, nickel, cobalt, and manganese from spent batteries is gradually developing. To recover these valuable metals from spent batteries, it is necessary to obtain black mass, which is primarily composed of components of positive and negative active materials, through pretreatment processes such as discharge, dismantling, heat treatment, and crushing. Alternatively, the metallic components of the positive and negative active materials can be obtained in the form of an alloy by heat-treating a large quantity of spent batteries at high temperatures. By using strong acids such as sulfuric acid or hydrochloric acid as leaching agents on the black mass or alloy obtained as described above, a metal solution containing a mixture of various metals is obtained. This solution can then be applied to a solvent extraction process using various metal extractants to separate and recover each of the valuable metals.

[0004] However, existing methods for separating valuable metals involve separating each type of valuable metal individually. This approach has the problem of incurring high processing costs and time due to the large number of process steps and the complexity of the process. Furthermore, the recovery rate of the valuable metals obtained through such complex and numerous steps is low, and the impurity content is also high.

[0005] The present invention aims to solve the above-mentioned problems and provide a new method capable of simultaneously extracting nickel, cobalt, and manganese using a solvent extraction method, while producing a high-purity nickel-cobalt-manganese complex salt with low impurity content.

[0006] A method for manufacturing a nickel-cobalt-manganese composite salt according to one embodiment of the present invention is,

[0007] Prepare black mass of a lithium secondary battery, an alloy containing nickel, cobalt, and manganese separated from a spent lithium secondary battery, or an aqueous metal mixture containing nickel, cobalt, and manganese separated from a spent cathode material leaching solution, and

[0008] Prepare a mixture of a compound represented by the following chemical formula 1 and a compound represented by the following chemical formula 2, and prepare a mixed solvent by saponifying the mixture:

[0009] (Chemical Formula 1)

[0010]

[0011] (In the above chemical formula 1, R 1 and R 2 Each is independently a C1 to C6 alkyl group, wherein R 1 and R 2 The sum of the carbon atoms is 7.

[0012] (Chemical Formula 2)

[0013] ,

[0014] Using the above mixed solvent as an extraction solvent, an organic solvent is obtained in which nickel, cobalt, and manganese are simultaneously extracted from the above metal mixed aqueous solution, and,

[0015] It includes adding a strong acid aqueous solution to the organic solvent from which nickel, cobalt, and manganese were simultaneously extracted to back-extract nickel, cobalt, and manganese.

[0016] The saponification of the above mixture includes adding an aqueous sodium hydroxide solution to the above mixture.

[0017] The saponification of the above mixture includes saponifying the mixture by 20% to 60%.

[0018] The saponification of the above mixture includes saponifying the mixture by 40% to 55%.

[0019] The compound represented by the above chemical formula 2 is included in a range of 0.5% to 2% based on the total volume of the compound represented by the above chemical formula 1 and the compound represented by the above chemical formula 2.

[0020] The compound represented by the above chemical formula 2 is included in a range of 1% based on the total volume of the compound represented by the above chemical formula 1 and the compound represented by the above chemical formula 2.

[0021] The pH of the extraction solvent is maintained in the range of 6 or higher and less than 7.

[0022] The pH of the extraction solvent is maintained in the range of 6.5 or higher and 6.8 or lower.

[0023] Simultaneous extraction of nickel, cobalt, and manganese from the above-mentioned metal mixture aqueous solution using the above-mentioned mixed solvent as an extraction solvent is carried out by an ion exchange reaction.

[0024] Simultaneous extraction of nickel, cobalt, and manganese from the metal mixed aqueous solution using the above mixed solvent as an extraction solvent is performed with the ratio of the aqueous phase to the organic phase at 1:1.

[0025] The above strong acid aqueous solution includes a sulfuric acid aqueous solution.

[0026] The concentration of the above aqueous sulfuric acid solution is 0.5M to 2.5M.

[0027] The concentration of the above aqueous sulfuric acid solution is 1M to 2M.

[0028] The above complex salt of nickel, cobalt, and manganese includes sulfates of nickel, cobalt, and manganese.

[0029] The method for preparing the above-mentioned complex salt of nickel, cobalt, and manganese further comprises drying the obtained back-extract after back-extracting the nickel, cobalt, and manganese.

[0030] The above method for manufacturing a complex salt of nickel, cobalt, and manganese has a recovery rate of 99% or more for each of nickel, cobalt, and manganese.

[0031] A method for manufacturing a positive electrode active material precursor for a lithium secondary battery according to another embodiment of the present invention includes a method for manufacturing a complex salt of nickel, cobalt, and manganese according to the above embodiment.

[0032] The method for preparing a complex salt of nickel, cobalt, and manganese according to the present invention is a method that enables the simultaneous extraction of valuable metals such as nickel, cobalt, and manganese by solvent extraction using an extraction solvent containing a mixture of compounds represented by a specific chemical formula. Furthermore, the recovery rate of each of the nickel, cobalt, and manganese simultaneously extracted as described above is high at 99% or higher, while the impurity content is very low at less than 5%. Accordingly, the present invention can provide a method advantageous for separating and recovering valuable metals that can be used as precursors for cathode active materials of lithium-ion secondary batteries from spent lithium-ion secondary batteries, and this presents a highly desirable solution in terms of the environment and resource recycling.

[0033] FIG. 1 is a flowchart showing an example of a process for recovering a mixed solution of a complex salt of nickel, cobalt, and manganese according to one embodiment, and

[0034] FIG. 2 is a graph showing the concentration of nickel extracted according to the number of extraction stages in a process for recovering nickel, cobalt, and manganese using a solvent extractant according to one embodiment, and

[0035] FIG. 3 is a graph showing the extraction rates of nickel, cobalt, manganese, magnesium, and lithium according to the metal ion extraction equilibrium pH when the molar concentration of the solvent extractant according to one embodiment is 1.2M, and

[0036] FIG. 4 is a graph showing the extraction rates of nickel, cobalt, manganese, magnesium, and lithium according to the metal ion extraction equilibrium pH when the molar concentration of the solvent extractant according to one embodiment is 2.0 M, and

[0037] FIG. 5 is a graph showing the extraction rates of nickel, cobalt, manganese, magnesium, and lithium according to the metal ion extraction equilibrium pH when the molar concentration of the solvent extractant according to one embodiment is 2.3M, and

[0038] FIG. 6 is a graph showing the extraction rates of nickel, cobalt, manganese, magnesium, and lithium according to the metal ion extraction equilibrium pH when the molar concentration of the solvent extractant according to one embodiment is 3.1M, and

[0039] Figure 7 is a graph showing the extraction rates of nickel, magnesium, and lithium according to changes in the metal ion extraction equilibrium pH, for the case where only 3.1M Versatic acid 10 (VA10) was used as the solvent extractant, and for mixed solvents in which 1 vol%, 3 vol%, and 5 vol% of D2EHPA were mixed with 3.1M VA10, respectively.

[0040] FIG. 8 is a graph showing the extraction rates of nickel, magnesium, and lithium according to changes in the metal ion extraction equilibrium pH, for the case where only 3.1M Versatic acid 10 (VA10) was used as the solvent extractant, and for mixed solvents in which 1 vol%, 3 vol%, and 5 vol% of Alamine336 were mixed with 3.1M VA10, respectively.

[0041] Figure 9 is a graph showing the extraction rates of nickel, magnesium, and lithium according to changes in the metal ion extraction equilibrium pH, for the case where only 3.1M Versatic acid 10 (VA10) was used as the solvent extractant, and for mixed solvents in which 1 vol%, 3 vol%, and 5 vol% of Ion quest 290 were mixed with 3.1M VA10, respectively.

[0042] FIG. 10 is a graph showing the extraction rates of nickel, magnesium, and lithium according to changes in metal ion extraction equilibrium pH for a mixed solvent of 1 volume% Ion quest 290 mixed in 3.1M VA10 and a mixed solvent of 1 volume% D2EHPA mixed in 3.1M VA10, respectively.

[0043] Figure 11 is a graph showing the extraction rates of nickel, cobalt, manganese, magnesium, and lithium according to changes in the metal ion extraction equilibrium pH for a solvent containing only 3.1M VA10 and not saponified, and

[0044] Figure 12 is a graph showing the extraction rates of nickel, cobalt, manganese, magnesium, and lithium according to changes in the metal ion extraction equilibrium pH for a solvent containing only 3.1M VA10 and having a saponification rate of 50%, and

[0045] Figure 13 is a graph showing the extraction rates of nickel, cobalt, manganese, magnesium, and lithium according to changes in the metal ion extraction equilibrium pH for a mixed solvent in which 1 volume% of Ion quest 290 was mixed with 3.1M VA10 and no saponification occurred.

[0046] Figure 14 is a graph showing the extraction rates of nickel, cobalt, manganese, magnesium, and lithium according to changes in the metal ion extraction equilibrium pH for a mixed solvent in which 1 volume% of Ion quest 290 is mixed with 3.1M VA10 and the saponification rate is 50%.

[0047] Figure 15 is a MaCabe-Thiele diagram showing the change in manganese concentration in the organic phase with respect to the manganese concentration in the aqueous phase of a solvent containing only 3.1M VA10 and 50% saponified, and

[0048] Figure 16 is a MaCabe-Thiele diagram showing the change in manganese concentration in the organic phase versus the manganese concentration in the aqueous phase of a mixed solvent prepared by mixing 1 volume% of Ion quest 290 with 3.1M VA10 and saponifying it to 50%, and

[0049] Figure 17 is a graph showing the removal rates of nickel, cobalt, and manganese removed from the extraction solvent according to the molar concentration of sulfuric acid.

[0050] Hereinafter, embodiments of the present invention are described in detail so that those skilled in the art can easily implement them. However, the structure actually applied may be implemented in various different forms and is not limited to the embodiments described herein.

[0051] In describing the embodiments of the present invention, detailed descriptions of known technologies related to the present invention are omitted if it is determined that such detailed descriptions may unnecessarily obscure the essence of the present invention. Furthermore, terms described below are defined considering their functions in the present invention, and these may vary depending on the intentions or practices of the user or operator. Accordingly, each term should be defined based on the content described throughout this specification. Terms used in the detailed description are intended merely to describe the embodiments of the present invention and should not be interpreted as limiting the present invention.

[0052] Unless explicitly stated otherwise, expressions in the singular form include the meaning of the plural form. In the drawings, parts unrelated to the description may be omitted to clearly explain the embodiments, and the same reference numerals are used for identical or similar components throughout the specification.

[0053] In the following, the terms 'lower' and 'upper' are used merely for convenience of explanation and do not limit positional relationships.

[0054] Unless otherwise defined below, expressions such as “include” or “equip” are intended to refer to certain characteristics, numbers, steps, actions, elements, parts thereof, or combinations thereof, and should not be interpreted to exclude the existence or possibility of one or more other characteristics, numbers, steps, actions, elements, parts thereof, or combinations thereof other than those described.

[0055]

[0056] Unless otherwise specifically provided in this specification, % units mean weight %.

[0057] The present invention will be described in detail below through each embodiment or example of the present invention. It should be noted that each embodiment or example described in this specification is not limited to a single embodiment or example, but may also be combined with other embodiments or examples. Accordingly, the citation of claims in the claims is merely an example of an embodiment, and the technical concept of the present invention should not be interpreted as being limited only to a combination with the cited claims; rather, combinations with various claims are also included within the scope of the technical concept of the present invention.

[0058] In conventional recycling processes, metals are leached from black mass, and a solvent extraction process is applied to extract each metal. In this process, individual metals are extracted and separated, with appropriate metal extractants and organic solvents used at each extraction step. When extracting individual metals in this manner, large quantities of the aforementioned metal extractants and organic solvents are used, resulting in a high number of extraction stages and potentially leading to an increase in the scale of the equipment.

[0059] Furthermore, conventional solvent extraction has utilized pH-raising agents such as sodium hydroxide (NaOH) and sodium carbonate (Na2CO3). In this case, sodium sulfate (Na2SO4) is inevitably generated, and the recycling or disposal of sodium sulfate presents a difficult problem.

[0060] The inventors of the present invention have discovered a new method for simultaneously extracting valuable metals such as nickel, cobalt, and manganese from a metal mixed solution containing some impurities and valuable metals such as manganese, cobalt, and nickel obtained by partially extracting and removing lithium and impurities from the leaching solution of the black mass, black alloy, or waste cathode material. This method is much simpler than existing methods of extracting single metals by separate processes or separating them using crystallization, and can reduce the scale of the facility. Furthermore, the inventors have discovered that the recovery rate of each of the simultaneously extracted nickel, cobalt, and manganese exceeds 99%, and the content of other impurities is very low at less than 5%, allowing for the production of high-purity complex salts of nickel, cobalt, and manganese, thereby completing the present invention.

[0061] The method for preparing a composite salt of nickel, cobalt, and manganese according to the present invention described above can simultaneously extract nickel, cobalt, and manganese by solvent extraction using an ion exchange method with an extraction solvent composed of a combination of specific compounds from a mixed solution containing manganese, cobalt, and nickel, and other impurities, obtained by partially extracting and removing lithium and impurities from a leaching solution of black mass, black alloy, or spent cathode material. Specifically, the method for preparing a composite salt of nickel, cobalt, and manganese according to one embodiment of the present invention comprises preparing a mixture of a compound represented by Chemical Formula 1 below and a compound represented by Chemical Formula 2 below, and using a mixed solvent obtained by saponifying the mixture as an extraction solvent to simultaneously extract nickel, cobalt, and manganese by an ion exchange method from a mixed solution containing nickel, cobalt, and manganese, and other impurities, obtained from a leaching solution of an alloy containing nickel, cobalt, and manganese separated from a spent lithium secondary battery or a spent cathode material.

[0062] (Chemical Formula 1)

[0063]

[0064] (In the above chemical formula 1, R 1 and R 2 Each is independently a C1 to C6 alkyl group, wherein R 1 and R 2 The sum of the carbon atoms is 7.

[0065] (Chemical Formula 2)

[0066] .

[0067] The compound represented by the above chemical formula 1 is R 1 and R 2 The sum of the carbon atoms present in is 7, and the total number of carbon atoms in the compound is 10. Accordingly, the above compound is also called “neodecanoic acid” and “Versatic TMYou may also purchase and use a substance sold under the trade name "Acid 10". The above compound exists as a transparent liquid, like water, at room temperature. Versatic TM Acid 10 has been known for a long time as a metal extractant, particularly suitable for nickel extraction.

[0068] The compound represented by Chemical Formula 2 above is a liquid in the form of a paste that is colorless to yellow at room temperature and is a type of solvent extractant also named Cyanex 272, Ionquest 290, etc. The compound represented by Chemical Formula 2 above is known to be able to extract metal ions, etc. by forming a type of pseudo-chelate compound with a metal, and said compound is also commercially available.

[0069] The inventors of the present invention [use] Versatic, previously known as a nickel extractant TM We aimed to develop a new mixed solvent capable of simultaneously extracting nickel, cobalt, and manganese with high efficiency by using Acid 10 as the main solvent and maximizing the extraction rates of manganese or cobalt in addition to nickel; as demonstrated by the examples described below, Versatic TM The present invention was completed by confirming that the objective of the present invention can be achieved by using a mixed solvent, in which a compound represented by Chemical Formula 2 is mixed within a certain content range, as an extraction solvent, as a result of experiments conducted by mixing various substances known as solvent extractants with Acid 10.

[0070] Specifically, in the case of solvent extractants other than the compound represented by Chemical Formula 2, the extraction rate of nickel increases with the mixing of the solvent extractant, but at the same time, the extraction rate of impurities such as magnesium also increases. On the other hand, in the case of the compound represented by Chemical Formula 2, when mixed within a certain content range, the extraction rate of nickel increases, but the degree of increase in the extraction rate of impurities such as magnesium is lower compared to other solvent extractants. Thus, it was confirmed that using a mixed solvent of the compound represented by Chemical Formula 1 and the compound represented by Chemical Formula 2 is suitable as a mixed solvent for preparing a complex salt of nickel, cobalt, and manganese.

[0071] Accordingly, the compound represented by Chemical Formula 2 may be included in a range of 0.5% to 2% based on the total volume of the compound represented by Chemical Formula 1 and the compound represented by Chemical Formula 2, preferably in a range of 0.5% to 1.5% based on the total volume of the compound represented by Chemical Formula 1 and the compound represented by Chemical Formula 2, more preferably in a range of 1%.

[0072] A mixed solvent comprising the compound represented by Chemical Formula 1 and the compound represented by Chemical Formula 2 can be used as is or diluted with a diluent such as kerosene. The diluent does not participate in the extraction reaction of the solvent.

[0073] In addition, the above mixed solvent can be used after partial saponification.

[0074] In the saponification process, when hydrogen ions generated during the extraction of metal ions into the mixed solvent are introduced into the solvent, the pH of the solvent may decrease, which can cause a decrease in the extraction rate of metal ions; therefore, through the saponification process, the hydrogen ions present in the mixed solvent are converted into sodium ions (Na +This is a method to minimize the decrease in pH of the solution by reducing the amount of hydrogen ions generated after metal ion extraction through substitution. However, if all hydrogen ions in the solvent are replaced with sodium ions, that is, if the saponification rate is 100%, the viscosity of the mixed solvent increases after saponification, resulting in very low fluidity and making the process unoperable. Therefore, an appropriate saponification rate must be determined to minimize the decrease in pH of the solvent and ensure the fluidity of the mixed solvent. Accordingly, the mixed solvent can be adjusted to 20% to 60%, for example, 30% to 60%, for example, 40% to 55%, or 40% to 50%. In one embodiment, the mixed solvent was saponified to 50% and used for solvent extraction. As a result, as can be seen from the examples described below, the extraction rate of metal ions, particularly the extraction rate of manganese ions, was significantly higher compared to the case where an unsaponified mixed solvent was used. Since the extraction rate of manganese ions is lower than that of nickel ions or cobalt ions, saponification of the mixed solvent is particularly desirable in that it can particularly improve the extraction rate of manganese ions. Saponification can be performed by adding an aqueous sodium hydroxide solution to the said mixed solvent.

[0075] The extraction solvent may be adjusted to maintain an appropriate equilibrium pH range. For example, the pH of the mixed solvent may be maintained in a range of 6 or higher and less than 7, for example, 6.5 or higher and 6.8 or lower, for example, 6.6 to 6.8, for example, 6.7, but is not limited thereto.

[0076] As can be seen from the examples described below, as the concentration of the compound represented by Chemical Formula 1 increases and the extraction equilibrium pH of the extraction solvent increases, the extraction rate of nickel, cobalt, and manganese ions, which are the targets for extraction, increases, while the extraction rate of impurities not to be extracted, such as magnesium and lithium, is maintained at less than 5%, and in particular, the extraction rate of lithium is relatively low. However, as the pH increases, the rate of formation of precipitates in the form of metal hydroxides due to the dissolution of metal ions may increase; therefore, to prevent this, the extraction equilibrium pH may be preferably in the neutral range mentioned above. In addition, the concentration of the compound represented by Chemical Formula 1 can be appropriately adjusted by considering the content of metal ions in a metal mixed solution containing nickel, cobalt, and manganese, for example, to a range of 1M to 5M, 2M to 5M, 2M to 4.5M, 2.5M to 4.5M, 2.5M to 4M, 2.5M to 3.8M, 2.8M to 3.7M, 2.8M to 3.5M, 2.9M to 3.4M, 3.0M to 3.4M, 3.0M to 3.3M, 3.1M to 3.3M, 3.1M to 3.2M, or 3.1M, but is not limited to these ranges.

[0077] Simultaneous extraction of nickel, cobalt, and manganese from the metal mixed solution using the above mixed solvent as an extraction solvent can be performed with the ratio of the aqueous phase to the organic phase at approximately 1:1 (volume ratio), and the number of extractions can be determined by confirming the extraction concentration of metal ions that are maximally extracted from the metal mixed solution. As can be seen from the examples described below, when nickel, cobalt, and manganese ions are simultaneously extracted using the mixed solvent according to one embodiment, it is confirmed that the maximum extraction rate can be achieved starting from approximately three extraction stages.

[0078] As described above, a mixture of the compound represented by Chemical Formula 1 and the compound represented by Chemical Formula 2 is prepared and saponified, and then the saponified mixed solvent is used as an extraction solvent to solvent extract a metal mixed solution containing nickel, cobalt, and manganese and other impurities, thereby allowing valuable metal ions such as nickel, cobalt, and manganese contained in the metal mixed solution to be simultaneously extracted into the extraction solvent. Subsequently, in order to obtain the valuable metal ions extracted from the extraction solvent, a strong acid aqueous solution can be added to the solvent to back-extract nickel, cobalt, and manganese.

[0079] The above strong acid aqueous solution may include an aqueous sulfuric acid solution. The molar concentration of sulfuric acid in the aqueous sulfuric acid solution may be 0.5 M to 2.5 M, for example, 0.5 M to 2 M, for example, 1 M to 2 M, for example, 2 M. As can be confirmed from the examples described below, as the concentration of sulfuric acid increases, the rate at which metal ions are back-extracted from the extraction solvent into the aqueous sulfuric acid solution, i.e., the removal rate of metal ions, tends to decrease. In other words, it is determined that an excess amount of sulfate ions hinders the removal of metal ions, and accordingly, the appropriate concentration of the aqueous sulfuric acid solution can be controlled within the above range, and preferably, it may be about 2 M.

[0080] As described above, by back-extracting nickel, cobalt, and manganese ions extracted with a mixed solvent by adding an aqueous sulfuric acid solution, the final nickel, cobalt, and manganese obtained may exist in the aqueous solution in the form of sulfates, for example, as a complex salt of nickel sulfate, cobalt sulfate, and manganese sulfate. The nickel, cobalt, and manganese ions back-extracted with the aqueous sulfuric acid solution exist in the aqueous sulfuric acid solution with a high recovery rate of over 99%, based on the content present in the initial metal ion mixed solution. On the other hand, the remaining impurity elements, excluding these valuable metals, such as lithium, magnesium, and sodium, have a very low proportion of less than 5% each present in the aqueous sulfuric acid solution. Therefore, it can be seen that the method for preparing a complex salt of nickel, cobalt, and manganese according to one embodiment is a method capable of separating and recovering each of the metals with high purity.

[0081] By drying an aqueous sulfuric acid solution containing the above nickel, cobalt, and manganese ions, a complex salt of nickel sulfate, cobalt sulfate, and manganese sulfate can be obtained. The nickel sulfate, cobalt sulfate, and manganese sulfate obtained in this way can be used as precursors for the positive electrode active material of a lithium-ion secondary battery.

[0082] Accordingly, a method for preparing a composite salt of nickel, cobalt, and manganese according to one embodiment can be advantageously used in a method for preparing a precursor of a cathode active material for a lithium secondary battery comprising a composite salt of nickel, cobalt, and manganese. That is, according to one embodiment, a method for preparing a cathode active material for a lithium secondary battery can be provided, comprising preparing an aqueous sulfuric acid solution comprising a composite salt of nickel, cobalt, and manganese and drying the solution.

[0083] Meanwhile, the mixed metal solution containing valuable metals such as nickel, cobalt, and manganese and other impurities, which is a starting material for applying the method for preparing a complex salt of nickel, cobalt, and manganese according to one embodiment, may be a solution containing black mass, black alloy, or a leaching solution obtained by adding a strong acid thereto, obtained by disassembling and crushing spent lithium-ion secondary batteries by various conventional methods, and is not limited to being prepared by a specific method or containing a specific material. The solution may be prepared using various methods well known to those skilled in the art, or a metal mixed solution prepared according to the method described in the inventor's prior Korean Patent Application No. 10-2024-0179730 may be used. The contents described in the aforementioned Korean Patent Application No. 10-2024-0179730 are incorporated herein by reference in their entirety.

[0084] Referring to the above Korean Patent Application No. 10-2024-0179730, a mixed solution of metals containing nickel, cobalt, and manganese and other impurities can be prepared through steps indicated by 100 to 400 as shown in FIG. 1. FIG. 1 is a flowchart schematically illustrating a method for preparing a composite salt of nickel, cobalt, and manganese according to one embodiment of the present invention in the order of process.

[0085] As described in 100 to 400 of FIG. 1, first, a leaching solution is prepared by treating black mass, black alloy, or waste cathode material generated when manufacturing a lithium-ion secondary battery with a strong acid (step 100), and this is mixed with a leaching solution of black mass, black alloy, or waste cathode material produced through a recycling process of a waste lithium-ion secondary battery (step 200), and lithium is selectively recovered from the mixture using methods such as cementation, solvent extraction, or neutralization precipitation (step 300), and then impurities are extracted and removed from the remaining mixture using a 'pre-loading solvent extraction process' (step 400), thereby obtaining a mixed solution containing nickel, cobalt, and manganese used as starting materials in one embodiment of the present invention, and other impurities. In the mixed solution obtained in this manner, valuable metals such as nickel, manganese, and cobalt can be recovered with a high recovery rate from the mixed solution by using an extraction solvent obtained by saponifying the mixed solution of the compound represented by Formula 1 and the compound represented by Formula 2, according to the method according to one embodiment of the present invention described above, and by solvent extraction of the mixed solution using an ion exchange method. The details of the process for each step indicated by 100 to 400 in FIG. 1 can be confirmed by referring to the aforementioned Korean Patent Application No. 10-2024-0179730, and a detailed description of each step is omitted in this specification.

[0086] The present invention will be described in detail below through examples. The examples are intended solely to illustrate embodiments of the present invention, and it is evident that the scope of the present invention is not limited by these examples.

[0087]

[0088] Examples

[0089] Preparation Example 1: Preparation of a metal mixed solution containing nickel, cobalt, and manganese

[0090] A metal mixed solution comprising valuable metals such as nickel, cobalt, and manganese, and other impurities such as lithium, magnesium, and sodium, is prepared in the following manner to apply the manufacturing method of the present invention.

[0091] First, a spent lithium secondary battery is dry-smelted to obtain an alloy (black alloy) containing nickel, cobalt, and manganese, which is then crushed by cup milling to prepare metal powder. A 17.5 wt% aqueous sulfuric acid solution is added to this to obtain a slurry, which is then reacted at 80°C for 6 hours to obtain a leaching solution and a residue. A 22.5 wt% aqueous sulfuric acid solution is added to the residue to obtain a slurry, which is then reacted again at 90°C for 8 hours to perform additional leaching. Afterward, a cementation agent such as Ni or Ni3S2 is added to the leaching solution and reacted at 85°C for 3 hours to remove copper. Subsequently, a neutralization precipitation is performed on the solution using a sodium-free neutralizing agent such as NiCO3 or Mg(OH)2, thereby obtaining a solution from which aluminum and iron have been removed by precipitation.

[0092] Finally, a pre-loading solvent extraction process is performed to further remove impurities other than nickel, cobalt, and manganese from the above solution. A solvent extractant for performing the pre-loading solvent extraction can be prepared as follows.

[0093] First, a solvent extractant, bis(2-ethylhexyl) phosphate (D2EHPA), is diluted in kerosene to a concentration of 30 volume%, and the prepared solvent extractant is mixed with an aqueous solution of sodium hydroxide (NaOH) to saponify it to a saponification rate of 40%. Then, the saponified solvent extractant is reacted with a 0.3 M aqueous solution of nickel hydroxide (NiOH) at pH 6.42 to obtain a solvent extractant from which nickel is pre-extracted through a substitution reaction between nickel and sodium.

[0094] Subsequently, the metal leaching solution from which copper, iron, and aluminum had been removed and the pre-extracted nickel (Ni) solvent extractant prepared above were mixed such that the volume ratio (O:A) of the organic phase (O) and aqueous phase (A) was 0.9:1, and the solvent extraction was performed five times in a countercurrent multi-stage manner (maintaining the pH at approximately 2 to 3.0) to obtain a metal mixed solution containing the following metals at the concentrations shown in Table 1 below.

[0095] Metal Type NiCoMnLiMgNa Concentration in Mixed Solution (g / L) 46.3 12.9 6.8 0.2 10.0 6 20.45

[0096]

[0097] Reference Example 1: Selection of First Solvent Extractant and Determination of Extraction Stages

[0098] In order to produce a nickel-cobalt-manganese complex salt with improved purity from the metal mixed solution prepared in Preparation Example 1 above, Versatic Acid 10 (hereinafter VA10) was selected as a first solvent extractant for simultaneously extracting nickel, cobalt, and manganese, and a test was performed to confirm its ability to extract nickel, a major element. Specifically, considering the concentration of nickel in the metal mixed solution, the concentration of VA10 was selected to be 3.1M, and this was mixed with ISD-159, a kerosene-based diluent, and used as an extraction solvent. The diluent does not participate in the solvent extraction reaction, and any kerosene-based diluent other than ISD-159 may be used.

[0099] For the test, the mixing ratio (A:O) of the aqueous phase (A) and the organic phase (O) was set to a volume ratio of 1:1, and the maximum amount of nickel extracted was measured at a reaction temperature of 25°C, and the results are shown in the graph of Figure 2. As can be seen from Figure 2, from the third extraction stage, the molar concentration of the solvent extractant capable of extracting the target nickel extraction value of 46.3 g / L can be identified.

[0100]

[0101] Reference Example 2: Confirmation of extraction rate according to the concentration of the first solvent extractant and the metal ion extraction equilibrium pH

[0102] Using the metal mixed solution prepared in Preparation Example 1 above, the extraction rate of metal ions according to the molar concentration of the first solvent extractant, VA10, and the metal ion extraction equilibrium pH was investigated. Specifically, the molar concentration of VA10 was selected in four values: 1.2 M, 2.0 M, 2.3 M, and 3.1 M, and the experiment was conducted by selecting five conditions for the metal ion extraction equilibrium pH: pH 6.0, pH 6.25, pH 6.5, pH 6.75, and pH 7.0.

[0103] Figure 3 is a graph showing the extraction rate of metal ions according to the metal ion extraction equilibrium pH when the molar concentration of VA10 is 1.2 M, Figure 4 is a graph showing the extraction rate of metal ions according to the metal ion extraction equilibrium pH when the molar concentration of VA10 is 2.0 M, Figure 5 is a graph showing the extraction rate of metal ions according to the metal ion extraction equilibrium pH when the molar concentration of VA10 is 2.3 M, and Figure 6 is a graph showing the extraction rate of metal ions according to the metal ion extraction equilibrium pH when the molar concentration of VA10 is 3.1 M.

[0104] Referring to Figures 3 to 6, it can be seen that as the molar concentration of VA10 increases and the metal ion extraction equilibrium pH increases, the extraction rates of nickel, cobalt, and manganese, which are the elements to be extracted, increase, while the extraction rates of magnesium and lithium, which are not to be extracted, are less than 5%, and in particular, the extraction rate of lithium is relatively low. Therefore, it can be determined that it is possible to simultaneously extract nickel, cobalt, and manganese using the VA10 extraction solvent. Considering the concentration of metal ions in the solution, a molar concentration of 3.1 M is appropriate for VA10, and an extraction equilibrium pH of around 6.7 is appropriate in terms of preventing the formation of precipitates in the form of metal hydroxides due to the solubility of metal ions.

[0105]

[0106] Example 1: Preparation of Mixed Solvent and Evaluation of Extraction Rate

[0107] Using the metal mixed solution prepared in Preparation Example 1 above, the extraction rate of metal ions according to the metal ion extraction equilibrium pH of a mixed solvent in which VA10, a first solvent extractant at a concentration of 3.1 M, and another solvent as a second solvent extractant were mixed was investigated.

[0108] Specifically, mixed solvents were prepared by mixing D2EHPA, Alamine 336, and Ion quest 290 with VA10 at a concentration of 3.1 M in volume ratios of 1%, 3%, and 5%, respectively, and then the extraction rate of metal ions in these mixed solvents was investigated. The evaluation of the metal ion extraction rate using the mixed solvents was conducted through the analysis of the extraction rates of nickel, magnesium, and lithium, which clearly demonstrate the characteristics of VA10, the first solvent extractant.

[0109] Referring to Figure 7, as the volume ratio of D2EHPA mixed with 3.1M VA10 increases, the extraction rate of nickel increases, but the extraction rate of magnesium, an impurity, also increases significantly, so it can be confirmed that D2EHPA is not suitable as a second extraction solvent.

[0110] Referring to Figure 8, as it can be seen that the extraction rate of nickel tends to decrease as the volume ratio of Alamine 336 mixed with 3.1M VA10 increases, it can be seen that Alamine 336 is also not suitable as a second solvent extractant.

[0111] Referring to Fig. 9, it can be seen that as the volume ratio of mixing Ion quest 290 with 3.1M VA10 increases, the extraction rate of nickel increases, and while the extraction rate of magnesium, an impurity, also increases, the degree of increase is much lower compared to the case where D2EHPA is mixed as shown in Fig. 7. Accordingly, it can be confirmed that Ion quest 290 can be used as a second solvent extractant together with VA10.

[0112] In addition, as shown in Figure 10, it can be confirmed that when 1% of Ion quest 290 is mixed by volume with 3.1M VA10, the difference in separation coefficients between nickel and lithium can be increased, thereby improving the extraction rate of nickel and decreasing the extraction rate of lithium. On the other hand, when 1% of D2EHPA is mixed by volume with 3.1M VA10, compared to the case where 1% of Ion quest 290 is mixed by volume, it can be seen that as the extraction rate of nickel increases, the extraction rates of impurities magnesium and lithium also increase significantly.

[0113] From the above results, it can be seen that Ion quest 290 can be used as a second solvent extractant by mixing it with VA10, the first solvent extractant, and that the optimal extraction rate can be achieved when the mixing ratio of Ion quest 290, the second solvent extractant, is 1% based on the total volume of the mixed solvent.

[0114]

[0115] Example 2: Comparison of extraction rates according to saponification rate

[0116] For each case where VA10 at a concentration of 3.1 M was used as the sole extraction solvent and a mixed solvent containing 1 volume% of Ion quest 290 mixed with 3.1 M VA10 was used as the extraction solvent, the extraction trend of metal ions was compared with and without saponification of each extraction solvent at a saponification rate of 50% by adding an aqueous sodium hydroxide solution, using the metal mixed solution prepared in Preparation Example 1 above, and the results are shown in FIGS. 11 to 14.

[0117] Referring to Figures 11 to 14, first, it can be seen that when saponification is applied, the extraction rate of impurities magnesium and lithium decreases, whether VA10 is used as a solvent alone or in combination with Ion quest 290. It was confirmed that when a solvent without saponification is used and the pH becomes 7 or higher, process interruption may occur due to the formation of precipitates caused by the solubility of metals. On the other hand, when saponification is applied, no precipitates are formed even when the metal ion extraction equilibrium is at pH 7 or higher, and phase separation is also good. Therefore, it is judged that process operation is possible even at pH 7 or higher by maximizing the extraction rates of manganese, cobalt, and nickel.

[0118] However, from the results of FIGS. 11 to 14, it can be seen that the condition with the lowest process stability and extraction rate of impurities magnesium and lithium is to simultaneously extract nickel, cobalt, and manganese at a metal ion extraction equilibrium pH of 6.7 after saponifying a mixed solvent of VA10 mixed with 1 volume% Ion quest 290 at a saponification rate of 50% (see FIG. 14).

[0119]

[0120] Example 3: Determination of optimal extraction stage based on the volume ratio of aqueous and organic phases

[0121] For each case using the metal mixed solution prepared in Preparation Example 1 above, where VA10 at a concentration of 3.1 M was used as the sole extraction solvent, and where a mixed solvent containing 1 volume% of Ion quest 290 mixed with 3.1 M VA10 was used as the extraction solvent, an aqueous sodium hydroxide solution was added to saponify each extraction solvent to a saponification rate of 50%. Then, the extraction ability of manganese ions was compared by varying the volume ratio of the aqueous and organic phases (Aqueous / Organic, A / O) to 0.25, 0.5, 0.75, 1.0, 1.25, 1.5, and 2.0, and the optimal number of extraction stages was compared by plotting a MaCabe-Thele diagram (see Figs. 15 and 16). At this time, the extraction equilibrium pH was fixed at 6.7.

[0122] The reason manganese ions were selected for the comparison of extraction capabilities is that, from the results of Reference Example 1, Preparation Example 1, and Example 1 and Example 2 above, it can be seen that the extraction rate of manganese ions is lower than that of nickel ions and cobalt ions. Therefore, in order to extract nickel, cobalt, and manganese simultaneously, if the condition is to extract all of the manganese, which has a low extraction rate, then it can be predicted that cobalt and nickel will naturally be extracted as well.

[0123] The extraction trends of manganese ions appear to be similar when using a single solvent of 3.1M concentration VA10 (applied for saponification) and when using a mixed solvent of 3.1M concentration VA10 mixed with 1 volume% of Ion quest 290 (applied for saponification). It can be seen that the manganese extraction rate increased by about 1% when using the mixed solvent, but this can be considered to be at a similar level. Accordingly, after plotting and analyzing the MaCabe-Thiele diagrams for the two cases, it was confirmed that manganese can be extracted at a rate of over 99.9% when operating three extraction stages at an extraction equilibrium pH of 6.7 and a volume ratio of aqueous to organic phases of 0.85.

[0124] Figure 15 is a MaCabe-Thiele diagram for a single solvent of 3.1 M concentration VA10 (applied to saponification), and Figure 16 is a MaCabe-Thiele diagram for a mixed solvent of 3.1 M concentration VA10 mixed with 1 volume% Ion quest 290 (applied to saponification). From Figures 15 and 16, it can be confirmed that nickel, cobalt, and manganese can be extracted simultaneously with high yield by saponifying a mixed solvent of 3.1 M concentration VA10 mixed with 1 volume% Ion quest 290 and using it as an extraction solvent.

[0125]

[0126] Example 4: Preparation of an aqueous solution containing a complex salt of nickel, cobalt, and manganese

[0127] Extraction was performed on the metal mixed solution prepared in Preparation Example 1 above by using the mixed solvent prepared in Example 2 above, which is a mixture of 3.1M VA10 and 1 volume% of Ion Quest 290, as an extraction solvent, saponified to a saponification rate of 50% using an aqueous sodium hydroxide solution, with an extraction equilibrium pH of 6.7 and an aqueous-to-organic phase ratio (A:O) of 1:1, and then removing a strong sulfuric acid (sulfuric acid concentration 18.7 wt%) aqueous solution from the organic solvent from which the metal was extracted at an aqueous-to-organic phase ratio of 1:1, and analyzing the amount of extracted metal, which is shown in Table 2 below.

[0128] Concentration in solution after removal of metal components NiCoMnLiMgNa (g / L) 46.28 12.8 6.78 0.01 Not detected 0.005 Recovery rate (%) 99.96 99.22 99.71 4.76 -1.11 Content relative to nickel (%) --- 0.02 -0.01

[0129]

[0130] As shown in Table 2 above, nickel, cobalt, and manganese can be simultaneously extracted using the mixed solvent. High recovery rates are obtained, with each of the extracted metals exceeding 99%, whereas the impurities lithium and sodium exhibit very low recovery rates of less than 5% and 2%, respectively. Furthermore, since lithium and sodium are extracted at levels of 5% and 2%, respectively, relative to quality specifications, it can be seen that the quality standards are also satisfied. Here, the specifications for lithium and sodium are as follows:

[0131] - Lithium specification: 0.421% relative to nickel content,

[0132] - Sodium specification: 0.521% relative to nickel content.

[0133]

[0134] Example 5: Determination of the optimal concentration of sulfuric acid for recovering nickel, cobalt, and manganese from the extraction solvent

[0135] In the above Example 4, to determine the optimal sulfuric acid concentration for back-extracting nickel, cobalt, and manganese from an organic solvent, the removal rate of metal ions according to the molar concentration of sulfuric acid was investigated, and the results are shown in Fig. 17.

[0136] As can be seen from Figure 17, the removal rate tends to decrease as the molar concentration of sulfuric acid increases, and it is determined that an excess amount of sulfate ions hinders the removal of metal ions. Accordingly, it can be considered that the optimal sulfuric acid concentration is at the level of 2M.

[0137] Although embodiments of the present invention have been described in detail with reference to the examples above, it is evident that the scope of the present invention is not limited by the examples, and that the basic concepts defined in the claims, as well as various modifications and improvements made by those skilled in the art using the same, also fall within the scope of the present invention.

Claims

1. Prepare a black mass of a lithium secondary battery, an alloy containing nickel, cobalt, and manganese separated from a spent lithium secondary battery, or a metal mixed solution containing nickel, cobalt, and manganese separated from a spent cathode material leaching solution, and Prepare a mixture of a compound represented by the following chemical formula 1 and a compound represented by the following chemical formula 2, and prepare a mixed solvent by saponifying the mixture: (Chemical Formula 1) (In the above chemical formula 1, R 1 and R 2 Each is independently a C1 to C6 alkyl group, wherein R 1 and R 2 The sum of the carbon atoms is 7.), (Chemical Formula 2) , Using the above mixed solvent as an extraction solvent, a mixed organic solvent is obtained in which nickel, cobalt, and manganese are simultaneously extracted from the above metal mixed solution, and, A method comprising adding a strong acid aqueous solution to a mixed organic solvent from which nickel, cobalt, and manganese are simultaneously extracted to back-extract nickel, cobalt, and manganese, Method for preparing a complex salt of nickel, cobalt, and manganese.

2. A method for preparing a complex salt of nickel, cobalt, and manganese, wherein the saponification of the mixture according to claim 1 comprises adding an aqueous sodium hydroxide solution to the mixture.

3. A method for preparing a complex salt of nickel, cobalt, and manganese, wherein, in claim 1, the saponification of the mixture comprises saponifying the mixture by 20% to 60%.

4. A method for preparing a complex salt of nickel, cobalt, and manganese according to claim 1, wherein the saponification of the mixture comprises saponifying the mixture by 40% to 55%.

5. A method for preparing a complex salt of nickel, cobalt, and manganese according to claim 1, wherein the compound represented by Chemical Formula 2 is included in a range of 0.5% to 2% based on the total volume of the compound represented by Chemical Formula 1 and the compound represented by Chemical Formula 2.

6. A method for preparing a complex salt of nickel, cobalt, and manganese according to claim 1, wherein the pH of the extraction solvent is maintained in a range of 6 or higher and less than 7.

7. A method for preparing a complex salt of nickel, cobalt, and manganese, wherein, in claim 1, the simultaneous extraction of nickel, cobalt, and manganese from the metal mixed solution using the mixed solvent as an extraction solvent is performed by an ion exchange reaction.

8. A method for preparing a complex salt of nickel, cobalt, and manganese according to claim 1, wherein the simultaneous extraction of nickel, cobalt, and manganese from the metal mixed solution using the mixed solvent as an extraction solvent is performed with the ratio of the aqueous phase to the organic phase being 1:

1.

9. A method for preparing a complex salt of nickel, cobalt, and manganese, wherein the strong acid aqueous solution of claim 1 comprises an aqueous sulfuric acid solution.

10. A method for preparing a complex salt of nickel, cobalt, and manganese according to claim 9, wherein the concentration of the aqueous sulfuric acid solution is 0.5 M to 2.5 M.

11. A method for preparing a complex salt of nickel, cobalt, and manganese according to claim 9, wherein the concentration of the aqueous sulfuric acid solution is 1M to 2M.

12. A method for preparing a complex salt of nickel, cobalt, and manganese according to claim 1, wherein the complex salt of nickel, cobalt, and manganese comprises a sulfate of nickel, cobalt, and manganese.

13. A method for preparing a complex salt of nickel, cobalt, and manganese, wherein, in claim 1, after back-extracting the nickel, cobalt, and manganese, the obtained back-extract is further dried.

14. A method for manufacturing a complex salt of nickel, cobalt, and manganese according to claim 1, wherein the recovery rates of nickel, cobalt, and manganese are each 99% or higher.

15. A method for manufacturing a positive electrode active material precursor for a lithium secondary battery, comprising a method for manufacturing a complex salt of nickel, cobalt, and manganese according to any one of claims 1 to 14.

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