Method for separating battery metals

Abstract

This invention provides a compound that functions as an extractant for efficiently separating nickel, or nickel and cobalt, from an acidic aqueous solution containing nickel, cobalt, and manganese; a method for producing this compound; an extraction medium containing this compound; and an extraction method using this extraction medium. [Solution] The selective extraction medium contains a compound represented by the following general formula (1) and a hydrophobic liquid. R1 is a hydrocarbon group having 1 to 16 carbon atoms. R2, R3, and R4 are each independently hydrogen or a hydrocarbon group having 1 to 16 carbon atoms. TIFF2026053910000026.tif60170

Description

Technical Field

[0001] This application relates to a technology for extracting and separating battery metals. More specifically, this application relates to a picolinic acid derivative that is an extractant suitable for extracting and separating battery metals, and a technology for extracting and separating useful metals using this picolinic acid derivative.

Background Art

[0002] Nickel, cobalt, and lithium are called battery metals and are essential metals for manufacturing lithium-ion secondary batteries. Since Japan relies on imports for the supply of nickel and cobalt, technologies for recovering these metals from waste products are important. The positive electrode material of a lithium-ion secondary battery contains nickel, cobalt, and manganese. If this waste positive electrode material is processed to isolate and recover cobalt and nickel, it can be reused as a battery material. Therefore, it is necessary to develop a technology for mutually separating nickel, cobalt, and manganese.

[0003] As a method for mutually separating nickel, cobalt, and manganese from used positive electrode materials, there is a solvent extraction method (Non-Patent Document 1). In the solvent extraction method, the used positive electrode material is heat-treated or the like, and nickel, cobalt, and manganese are leached into an acidic solution such as sulfuric acid. Then, using an extraction medium in which an organic ligand as an extractant is dissolved in a hydrophobic organic solvent, nickel and cobalt are extracted and separated from this acidic solution. The extractants commonly used in industrial solvent extraction methods are acidic extractants based on phosphoric acid-based and carboxylic acid-based compounds.

[0004] For example, nickel, cobalt, and manganese are mutually separated using a phosphoric acid-based extractant in the following procedure. After extracting nickel and cobalt with a phosphoric acid-based extractant and separating them from manganese in an acidic solution, nickel and cobalt in the phosphoric acid-based extractant are back-extracted with hydrochloric acid. Then, cobalt is extracted from this hydrochloric acid solution with an amine-based extractant to mutually separate cobalt and nickel (Non-Patent Documents 2 and Patent Document 1).

[0005] Recently, in order to improve the performance of lithium-ion secondary batteries, the nickel content in cathode materials has tended to increase. Therefore, the importance of extractants that preferentially recover nickel is increasing. To separate nickel, cobalt, and manganese using commercially available acidic extractants based on phosphoric acid or carboxylic acid compounds, adjustment of the hydrogen ion concentration is necessary. These extractants exhibit excellent nickel-cobalt separation capabilities. However, with carboxylic acid extractants, the hydrogen ion concentration condition for separating nickel and cobalt is near neutral pH, and since hydrogen ions are released into the aqueous phase during extraction, precise control of the hydrogen ion concentration is required. On the other hand, phosphoric acid extractants exhibit cobalt extraction selectivity over nickel, making it difficult to extract only nickel in a system where nickel and cobalt coexist.

[0006] One method for preferentially extracting nickel under acidic pH conditions is to use the extractant N-[N,N-di(2-ethylhexyl)aminocarbonylmethyl]glycine (Non-Patent Literature 3). Using this extractant, nickel and cobalt can be separated from manganese when the pH of the waste material solution is 4-5, and nickel can be separated from cobalt and manganese when the pH of the waste material solution is around 3. This method is superior because it allows for the mutual separation of nickel, cobalt, and manganese from a sulfuric acid solution, has high nickel extraction selectivity relative to cobalt and manganese, and the extractant is easy to synthesize. If an extractant can be developed that offers even higher separation of nickel and cobalt, and simultaneously results in a more acidic pH during separation, nickel can be recovered even more efficiently. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2016-113672 [Patent Document 2] Japanese Patent Publication No. 2007-126404 [Non-patent literature]

[0008] [Non-Patent Document 1] R. Sojka, Q. Pan, L. Billmann, Comparative Study of Li-ion battery recycling process, ACCUREC Recycle [Non-Patent Document 2] Junji Shibata, "The Cutting Edge of Rare Metal Recycling Technology" (supervised by Yukiaki Harada), pp. 239-253 (2011) [Non-Patent Document 3] Y. Baba, F. Kubota, N. Kamiya, Masahiro Goto, Ind. Eng. Chem. Res., Vol.53, pp.812-818(2014) [Non-Patent Document 4] W. Liu, H. Su, J. Zhang, L. Wang, Y. Liu, J. Liang, Z. Zhu, Sep. Purif. Technol., Vol.286, pp.120385-120395 (2022) [Overview of the project] [Problems that the invention aims to solve]

[0009] The object of this application is to provide a compound that functions as an extractant capable of selectively and efficiently extracting nickel from manganese and cobalt, or nickel and cobalt from manganese, from an aqueous solution containing nickel, cobalt, and manganese; a method for producing this compound; an extraction medium containing this compound; and an extraction method using this extraction medium. [Means for solving the problem]

[0010] To solve the above problems, the inventors of this invention diligently developed and investigated extractants, and as a result found that by contacting an acidic aqueous solution containing battery metal with a hydrophobic organic solvent containing a compound having a 3-carbamoyl picolinic acid structure or a cation exchanger of this compound, nickel can be efficiently separated from manganese and cobalt, or nickel and cobalt can be separated from manganese, thus completing the present invention.

[0011] A compound according to one embodiment of the present invention is represented by the following general formula (1), where R1 is a hydrocarbon group having 1 to 16 carbon atoms, and R2, R3, and R4 are each independently hydrogen or a hydrocarbon group having 1 to 16 carbon atoms.

[0012] [ka]

[0013] Compounds of other embodiments of this application are represented by the following general formula (2), where R1 is a hydrocarbon group having 1 to 16 carbon atoms. R2, R3, and R4 are each independently hydrogen or a hydrocarbon group having 1 to 16 carbon atoms. Cat is a cation of ammonium, monoalkylammonium, dialkylammonium, trialkylammonium, tetraalkylammonium, tetraalkylphosphonium, lithium, sodium, potassium, rubidium, or cesium.

[0014] [ka]

[0015] A method for producing a compound according to one embodiment of the present invention involves reacting a compound represented by the following general formula (3) with a compound represented by the following general formula (4) to synthesize a compound represented by the following general formula (1). However, R1 is a hydrocarbon group having 1 to 16 carbon atoms. R2, R3, and R4 are each independently hydrogen or a hydrocarbon group having 1 to 16 carbon atoms.

[0016] [Chemistry]

[0017] [Chemistry]

[0018] [Chemistry]

[0019] The extraction medium according to an aspect of the present application is an extraction medium that selectively extracts nickel with respect to manganese and cobalt, or selectively extracts nickel and cobalt with respect to manganese, from an acidic aqueous solution containing nickel, cobalt, and manganese, and contains the compound of the present application and a hydrophobic liquid.

[0020] The extraction method according to an aspect of the present application is an extraction method that selectively extracts nickel with respect to manganese and cobalt, or selectively extracts nickel and cobalt with respect to manganese, from an acidic aqueous solution containing nickel, cobalt, and manganese using the extraction medium of the present application, and has an extraction step of bringing the extraction medium into contact with the aqueous solution to obtain an organic phase in which nickel, or nickel and cobalt, are extracted into the extraction medium. [Advantages of the Invention]

[0021] The compound of the present application has a 3-carbamoylpicolinic acid structure. Further, the extraction medium of the present application contains the compound of the present application. Further, the extraction method of the present application uses the extraction medium of the present application. Therefore, according to the present application, nickel, or nickel and cobalt, can be efficiently separated from an aqueous solution containing nickel, cobalt, and manganese. [Brief Description of the Drawings]

[0022] [Figure 1] 1H-NMR spectrum of a deuterated chloroform solution of 3-(octylcarbamoyl)picolinic acid in Synthesis Example 1. [Figure 2]1H-NMR spectrum of a deuterated chloroform solution of 3-(octylcarbamoyl)picolinic acid from Synthesis Example 1. [Figure 3] 1H-NMR spectrum of a deuterated chloroform solution of 2-(octylcarbamoyl)nicotinic acid from Synthesis Example 1. [Figure 4] 1H-NMR spectrum of a deuterated chloroform solution of 2-(octylcarbamoyl)nicotinic acid from Synthesis Example 1. [Figure 5] ¹H-NMR spectrum of 2-(hexadecanoylcarbamoyl)nicotinic acid in deuterated chloroform solution from Synthesis Example 2. [Figure 6] ¹H-NMR spectrum of 2-(hexadecanoylcarbamoyl)nicotinic acid in deuterated chloroform solution from Synthesis Example 2. [Figure 7] 1H-NMR spectrum of 3-(hexadecanoylcarbamoyl)picolinic acid in deuterated chloroform from Synthesis Example 2. [Figure 8] 1H-NMR spectrum of 3-(hexadecanoylcarbamoyl)picolinic acid in deuterated chloroform from Synthesis Example 2. [Figure 9] A graph showing the relationship between the pH of the aqueous phase in Example 1 and the extraction rates of various metals. [Figure 10] A graph showing the relationship between the pH of the aqueous phase in Example 2 and the extraction rates of various metals. [Figure 11] A graph showing the relationship between the pH of the aqueous phase in Example 3 and the extraction rates of various metals. [Figure 12] A graph showing the relationship between the pH of the aqueous phase in Example 4 and the extraction rates of various metals. [Figure 13] A graph showing the relationship between shaking time and extraction rate of various metals in Example 5. [Figure 14] A graph showing the relationship between sulfuric acid concentration and the back extraction rates of various metals in Example 6. [Figure 15] A graph showing the relationship between hydrochloric acid concentration and the back extraction rates of various metals in Example 6. [Figure 16] A graph showing the relationship between the ammonia water concentration and the back extraction rates of various metals in Example 6. [Figure 17] A graph showing the relationship between the pH of the aqueous phase in Reference Example 1 and the extraction rates of various metals. [Figure 18] A graph showing the relationship between the pH of the aqueous phase in Example 7 and the extraction rates of various metals. [Figure 19] A graph showing the relationship between the pH of the aqueous phase in Example 8 and the extraction rates of various metals. [Figure 20] A graph showing the relationship between the pH of the aqueous phase in Example 9 and the extraction rates of various metals. [Figure 21] A graph showing the relationship between the pH of the aqueous phase in Example 10 and the extraction rates of various metals. [Figure 22] A graph showing the relationship between the pH of the aqueous phase in Example 11 and the extraction rates of various metals. [Figure 23] A graph showing the relationship between the pH of the aqueous phase in Example 12 and the extraction rates of various metals. [Figure 24] A graph showing the relationship between sulfuric acid concentration and the back extraction rates of various metals in Example 12. [Figure 25] A graph showing the relationship between sulfuric acid concentration and the back extraction rates of various metals in Example 13. [Figure 26] A graph showing the relationship between sulfuric acid concentration and the back extraction rates of various metals in Example 14. [Modes for carrying out the invention]

[0023] The compound, method for producing the compound, extraction medium, and extraction method of this application will be described based on embodiments and examples. Repetitive explanations will be omitted as appropriate. In this application, when "~" is used to represent two numerical ranges, these two numerical values ​​are included within that range.

[0024] The compound of the first embodiment of the present application is represented by the following general formula (1), where R1 is a hydrocarbon group having 1 to 16 carbon atoms, and R2, R3, and R4 are each independently hydrogen or a hydrocarbon group having 1 to 16 carbon atoms.

[0025] [ka]

[0026] When the compound of the first embodiment is used as an extractant as described later, if R1, R2, R3, and R4 are hydrocarbon groups, it is preferable that these hydrocarbon groups are n-alkyl groups. Examples of such n-alkyl groups include methyl group, ethyl group, propyl group, n-butyl group, n-pentyl group, n-hexyl group, n-heptyl group, n-octyl group, n-nonyl group, n-decyl group, n-undecyl group, n-dodecyl group, n-tridecyl group, n-tetradecyl group, n-pentadecyl group, and n-hexadecyl group.

[0027] Examples of compounds in the first embodiment include 3-(octylcarbamoyl)picolinic acid in which R1 is an n-octyl group and R2, R3, and R4 are hydrogen atoms, 3-(hexadecanoylcarbamoyl)picolinic acid in which R1 is an n-hexadecyl group and R2, R3, and R4 are hydrogen atoms, and 3-(octylcarbamoyl)-5-octylpicolinic acid in which R1 and R3 are n-octyl groups and R2 and R4 are hydrogen atoms.

[0028] The compound of the first embodiment is synthesized by reacting a compound represented by the following general formula (3) with a compound represented by the following general formula (4). Note that R1, R2, R3, and R4 are the same as those in general formula (1) above.

[0029] [ka]

[0030] [ka]

[0031] When R2, R3, and R4 are hydrogen, the synthesis is carried out, for example, by the following procedure: 2,3-Pyridinedicarboxylic acid anhydride and a mono-n-alkylamine compound represented by the above general formula (4) are dissolved in an organic solvent such as dichloromethane and reacted. The resulting product contains a 3-carbamoyl picolinate compound represented by the above general formula (1) and a 2-carbamoyl nicotinic acid compound represented by the following general formula (5). By separating these compounds by column chromatography or reprecipitation, the 3-carbamoyl picolinate compound can be obtained.

[0032] [ka]

[0033] When R3 is an alkyl group and R2 and R4 are hydrogen, the synthesis can be carried out, for example, by the following procedure: 5-Bromo-2,3-pyridinedicarboxylic acid anhydride is reacted with an alkylboronic acid under basic conditions under palladium catalysis to synthesize 5-alkyl-2,3-pyridinedicarboxylic acid anhydride. Then, the 5-alkyl-2,3-pyridinedicarboxylic acid anhydride is reacted with an alkylamine to obtain a mixture of 5-alkyl-3-alkylcarbamoylpicolinic acid and 5-octyl-2-octylcarbamoylnicotinic acid. 5-alkyl-3-alkylcarbamoylpicolinic acid is obtained from this mixture by purification using column chromatography.

[0034] The compound of the second embodiment of the present application is represented by the following general formula (2), where R1 is a hydrocarbon group having 1 to 16 carbon atoms. R2, R3, and R4 are each independently hydrogen or a hydrocarbon group having 1 to 16 carbon atoms. Cat is a cation of ammonium, monoalkylammonium, dialkylammonium, trialkylammonium, tetraalkylammonium, tetraalkylphosphonium, lithium, sodium, potassium, rubidium, or cesium.

[0035] [ka]

[0036] The compound of the second embodiment dissolves in a hydrophobic liquid by mixing the compound of the first embodiment with the salt of the cation in a hydrophobic liquid. The salt of the cation functions as a cation exchanger, exchanging the hydrogen of the carboxyl group of the compound of the first embodiment with Cat. When the compound of the second embodiment is used as an extractant as described later, if an alkyl group is included in Cat, this alkyl group is preferably an n-alkyl group. Examples of n-alkyl groups include methyl, ethyl, propyl, n-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, n-nonyl, and n-decyl groups.

[0037] The extraction medium in the embodiments of this application selectively extracts nickel from manganese and cobalt, or selectively extracts nickel and cobalt from manganese, from an acidic aqueous solution containing nickel, cobalt, and manganese (hereinafter sometimes referred to as "aqueous solution to be extracted"). In this application, metal ions such as nickel ions may be simply referred to as nickel, etc. Furthermore, in this application, "extractant that selectively extracts B from A" or "extraction medium that selectively extracts B from A" refers to an extractant or extraction medium in which, after extracting A and B from a liquid containing A and B, the concentration of B is at least twice the concentration of A. This ratio is preferably 4 times or more, and more preferably 10 times or more. Furthermore, in this application, "extraction selectivity of D to C" refers to the ratio of the concentration of D to the concentration of C in the extraction medium after extracting C and D from a liquid containing C and D (concentration of D / concentration of C).

[0038] The aqueous solution to be extracted is preferably an aqueous sulfuric acid solution. This is because by leaching used positive electrode material from lithium-ion secondary batteries into sulfuric acid, an aqueous sulfuric acid solution containing nickel, cobalt, and manganese can be obtained, and by separating the nickel and cobalt from the aqueous sulfuric acid solution using the extraction medium of the embodiment, it can be reused as battery material. The aqueous solution to be extracted may further contain lithium, sodium, aluminum, iron, and copper, etc.

[0039] The extraction medium of the embodiment contains one or more compounds from the first embodiment and the second embodiment that function as extractants, and a hydrophobic liquid. The hydrophobic liquid is hydrophobic enough that, after mixing with the aqueous phase and centrifuging, the aqueous phase and the hydrophobic liquid phase can be collected separately. Examples of hydrophobic liquids include organic solvents such as alkanes, alkynes, alkenes, alcohols, alkyl halides, and aromatic compounds, as well as salts of ionic liquids. When the hydrophobic liquid is an organic solvent, the hydrophobic phase may be described as the organic phase. The extraction medium of the embodiment may also contain other extractants, modifiers, and by-products or unreacted materials from the synthesis of the extractants.

[0040] The extraction medium of the embodiment selectively extracts nickel relative to manganese and cobalt when the aqueous solution to be extracted is more acidic, for example, when the pH of the aqueous solution to be extracted is 1.5 or less. When the aqueous solution to be extracted is acidic and more alkaline than when nickel can be selectively extracted, for example, when the pH is 1.6 to 6.0, it selectively extracts nickel and cobalt relative to manganese. Furthermore, when the extractant in the extraction medium of the embodiment is the compound of the second embodiment, the extraction medium of the embodiment preferentially extracts nickel.

[0041] The extraction method of the embodiment of the present application selectively extracts nickel from manganese and cobalt, or nickel and cobalt from manganese, using the extraction medium of the embodiment. The extraction method of the embodiment comprises an extraction step. In the extraction step, the extraction medium of the embodiment is brought into contact with the aqueous solution to be extracted to obtain a hydrophobic phase in which nickel, or nickel and cobalt, are extracted into the extraction medium.

[0042] The pH of the aqueous solution to be extracted is preferably 6.0 or lower, and more preferably 4.0 or lower. This is because the pH of the aqueous solution to be extracted is easy to control, and furthermore, there are pH ranges in which only nickel is extracted into the extraction medium and pH ranges in which both nickel and cobalt are extracted into the extraction medium. If only nickel can be selectively extracted into the extraction medium, nickel can be directly separated from the sulfuric acid solution containing battery metals. Then, in the aqueous solution to be extracted from which nickel has been separated and removed, it becomes easier to separate other battery metals such as cobalt. The amount of extractant in the extraction medium that is brought into contact with the aqueous solution to be extracted is preferably 2 times (2 equivalents) or more the amount of the metal to be extracted contained in the aqueous solution to be extracted, and more preferably 3 times (equivalents) or more.

[0043] COO - When an extraction medium containing an extractant equipped with a Cat portion comes into contact with an acidic aqueous solution to be extracted, COO - The extractant is dissolved in a hydrophobic liquid with hydrogen added to the carboxyl group. - When an extraction medium containing an extractant with a Cat portion is in contact with the extraction aqueous solution, if the aqueous solution becomes more alkaline, hydrogen or COO is released from the carboxyl group of the extractant. - The "Cat" is removed from "Cat," and the extractant coordinates with nickel or cobalt, forming a metal complex that dissolves in hydrophobic liquids and is extracted into the hydrophobic phase.

[0044] Since the addition and removal of hydrogen or Cat from such extractants are involved in the formation of nickel and cobalt complexes, the extraction rate of nickel and cobalt changes depending on the hydrogen ion concentration. By utilizing this property, the extraction and back-extraction of nickel and cobalt can be performed depending on the hydrogen ion concentration of the back-extract. The extraction method of the embodiment may further include a back-extraction step in which an acidic solution with a pH of 1 or less is brought into contact with the hydrophobic phase that has undergone the extraction step, and nickel, or nickel and cobalt, is back-extracted into the acidic solution.

[0045] As with the compounds of the first and second embodiments which are extractants, having a carboxyl group or a hydrogenated form thereof at the 2-position of the pyridine ring and a carbamoyl group at the 3-position allows for selective extraction of nickel from manganese and cobalt, or selective extraction of nickel and cobalt from manganese. On the other hand, similar compounds such as 2-carbamoylnicotinic acid, 6-carbamoyl-2-picolinic acid, and 4-carbamoylpyridine alone cannot selectively extract nickel from cobalt (Patent Document 2 and Non-Patent Document 4).

[0046] The pyridine ring nitrogen and carboxyl group oxygen of the extractant coordinate to nickel or cobalt, forming a metal complex that is extracted into the extraction medium. Here, the carbamoyl group at position 3 interacts with the carboxyl group via intramolecular hydrogen bonding, causing steric hindrance. Due to this steric hindrance, the extractant is more likely to coordinate to nickel, which has a smaller ionic radius, than to cobalt, which has a larger ionic radius. In other words, nickel is more easily extracted into the extraction medium than cobalt.

[0047] On the other hand, the coordination form of manganese to the extractant is significantly different from that of nickel and cobalt to the extractant. In other words, complex formation between manganese and the extractant does not proceed as smoothly as complex formation between nickel or cobalt and the extractant. For this reason, the extractability of manganese to the extractant is considered to be lower than that of nickel and cobalt. Thus, the molecular structure of the extractant of this application is very suitable for the extraction and separation of nickel and cobalt from sulfuric acid solutions, and especially for the extraction and separation of nickel. Furthermore, the extraction method of the embodiment allows for the direct extraction of nickel and cobalt from sulfuric acid aqueous solutions with high hydrogen ion concentrations, and also enables their mutual separation. For this reason, the extraction method of the embodiment is particularly suitable for the separation and purification of nickel and cobalt. [Examples]

[0048] <Synthesis of extractants> (Synthesis Example 1) 88 g of 2,3-pyridinedicarboxylic acid anhydride (chemical formula (6) below) and 76 g of n-octylamine (chemical formula (7) below) were dissolved in dichloromethane and reacted at -5°C for 1 hour. This reaction yielded a mixture of 3-(octylcarbamoyl)picolinic acid (chemical formula (8) below) in 11.6% yield and 2-(octylcarbamoyl)nicotinic acid (chemical formula (9) below) in 65.5% yield.

[0049] [ka]

[0050] [ka]

[0051] [ka]

[0052] [ka]

[0053] The mixture was purified using a silica gel column, and 3-(octylcarbamoyl)picolinic acid and 2-(octylcarbamoyl)nicotinic acid were separated by reprecipitation with ethyl acetate and hexane. 3-(octylcarbamoyl)picolinic acid with a purity of 96% was obtained. Each compound was dissolved in deuterated chloroform for ¹H-NMR spectroscopy. Figures 1 and 2 show the ¹H-NMR spectrum of 3-(octylcarbamoyl)picolinic acid. Figures 3 and 4 show the ¹H-NMR spectrum of 2-(octylcarbamoyl)nicotinic acid.

[0054] (Synthesis Example 2) 13 g of 2,3-pyridinedicarboxylic acid anhydride (chemical formula (6) above) and 21 g of n-hexadecylamine (chemical formula (10) below) were dissolved in dichloromethane and reacted at -5°C for 10 minutes, followed by 40°C for 50 minutes. This reaction yielded 2-(hexadecanoylcarbamoyl)nicotinic acid (chemical formula (11) below) in 83.4% yield and 3-(hexadecanoylcarbamoyl)picolinic acid (chemical formula (12) below) in 14.9% yield.

[0055] [ka]

[0056] [ka]

[0057] [ka]

[0058] The reaction mixture was filtered to obtain 2-(hexadecanoylcarbamoyl)nicotinic acid as an insoluble solid. Figures 5 and 6 show the 1H-NMR spectra of 2-(hexadecanoylcarbamoyl)nicotinic acid. The solvent was removed from the filtrate, and the solid was redissolved in chloroform. The dissolved product was reprecipitated with hexane and separated from 2-(hexadecanoylcarbamoyl)nicotinic acid to obtain 3-(hexadecanoylcarbamoyl)picolinic acid with a purity of 98%. Figures 7 and 8 show the 1H-NMR spectra of 3-(hexadecanoylcarbamoyl)picolinic acid.

[0059] <Extraction with 3-(octylcarbamoyl)picolinic acid> (Example 1) Nickel(II) sulfate hexahydrate, cobalt(II) sulfate heptahydrate, and manganese(II) sulfate pentahydrate were dissolved in sulfuric acid whose pH was adjusted according to concentration to prepare the sulfuric acid aqueous solutions of Example 1 with a pH of 2 to 6, such that the concentrations of nickel, cobalt, and manganese were each 0.33 mM and the pH after the extraction reaction was 2.5 to 3.6. 3-(octylcarbamoyl)picolinic acid, the extractant, was dissolved in chloroform to a concentration of 3 mM to prepare the extraction medium of Example 1.

[0060] 2.0 mL of sulfuric acid solution and 2.0 mL of extraction medium were placed in centrifuge tubes. These centrifuge tubes were shaken for 1 hour at 200 spm using a shaker (Yayoi, YS-8D). In all centrifuge tubes, a white solid, presumably precipitated extractant, was observed between the organic and aqueous phases. The organic and aqueous phases in these centrifuge tubes were centrifuged at 2000 rpm for 20 minutes using a centrifuge (Kubota Shoji, S500T). The pH of the aqueous phase was measured using a pH meter (Toa DKK, HM-30R), and the concentrations of various metals in the aqueous phase were measured using a high-frequency inductively coupled plasma emission spectrometer (SPECTRO, ARCOS).

[0061] The extraction rates of various metals were calculated using the following formula (the same applies hereafter). Extraction rate [%] = (Concentration of target metal in sulfuric acid solution before shaking - Concentration of target metal in sulfuric acid solution after shaking) / Concentration of target metal in sulfuric acid solution before shaking × 100 Figure 9 shows the relationship between the pH of the aqueous phase after the extraction reaction (indicated as "pH of the aqueous phase after extraction" (hereinafter the same)) and the extraction rate of various metals (indicated as "metal extraction rate" (hereinafter the same)).

[0062] When the sulfuric acid solution before the extraction reaction was more acidic, for example, below pH 3.0, the pH of the sulfuric acid solution after the extraction reaction did not change significantly from the pH of the sulfuric acid solution before the extraction reaction. On the other hand, when the sulfuric acid solution before the extraction reaction was more alkaline, for example, between pH 4.0 and 6.0, the pH of the sulfuric acid solution after the extraction reaction changed to the more acidic side than the pH of the sulfuric acid solution before the extraction reaction. This is because hydrogen ions released during the extraction reaction with metal ions were incorporated into the aqueous phase from the extractant in the organic solvent. As shown in Figure 9, when the pH of the aqueous phase after the extraction reaction was between 2.5 and 3.6, nickel and cobalt were selectively extracted into the extraction medium relative to manganese. When the pH of the aqueous phase after the extraction reaction was 2.5, the extraction selectivity of nickel relative to manganese was slightly higher than that of cobalt relative to manganese. Manganese was hardly extracted into the extraction medium.

[0063] (Example 2) Using the same procedure as for preparing the sulfuric acid aqueous solution in Example 1, an aqueous sulfuric acid aqueous solution of Example 2 was prepared with concentrations of nickel, cobalt, and manganese at 0.33 mM each, and with a pH of 0.5 to 3.5 after the extraction reaction, so that the pH was between 0.5 and 3.5. The extraction medium of Example 2, containing a cation exchanger of 3-(octylcarbamoyl)picolinic acid as the extractant, was prepared by dissolving 3-(octylcarbamoyl)picolinic acid and tetrabutylammonium perchlorate in chloroform to a concentration of 3 mM each.

[0064] Subsequently, mixing, shaking, and centrifugation were performed under the same conditions as in Example 1, and the extraction rates of various metals were calculated. Figure 10 shows the relationship between the pH of the aqueous phase after the extraction reaction and the extraction rates of various metals. As shown in Figure 10, when the pH of the aqueous phase after the extraction reaction was between 0.9 and 1.6, nickel was selectively extracted into the extraction medium compared with manganese and cobalt. When the pH of the aqueous phase after the extraction reaction was 1.6 or higher, cobalt was extracted into the extraction medium. Manganese was hardly extracted into the extraction medium. When the pH of the aqueous phase after the extraction reaction was around 1, a white solid, which is thought to be precipitated extractant, was observed between the organic phase and the aqueous phase.

[0065] (Example 3) Following the same procedure as in the preparation of the sulfuric acid aqueous solution in Example 1, an aqueous sulfuric acid aqueous solution for Example 3 was prepared with concentrations of nickel, cobalt, and manganese at 0.33 mM each, and with a pH of 0 to 6 such that the pH after the extraction reaction was 0 to 5.8. 3-(octylcarbamoyl)picolinic acid was dissolved in chloroform at a concentration of 3 mM, and tetrabutylammonium perchlorate was dissolved at a concentration of 300 mM, to prepare the extraction medium for Example 3 containing a cation exchanger of 3-(octylcarbamoyl)picolinic acid as the extractant. The extraction medium, mixed with the aqueous sulfuric acid aqueous solution whose pH after the extraction reaction was 5.8, was pre-contacted with a metal-free aqueous phase at pH 12 to suppress the change in pH of the sulfuric acid aqueous solution during metal extraction.

[0066] Subsequently, mixing, shaking, and centrifugation were performed under the same conditions as in Example 1, and the extraction rates of each metal were calculated. Figure 11 shows the relationship between the pH of the aqueous phase after the extraction reaction and the extraction rates of each metal. As shown in Figure 11, when the pH of the aqueous phase after the extraction reaction was between 0.8 and 2.2, nickel was selectively extracted into the extraction medium in relation to manganese and cobalt. When the pH of the aqueous phase after the extraction reaction was 1.8 or higher, cobalt was extracted into the extraction medium. When the pH of the aqueous phase after the extraction reaction was 2.6 or higher, nickel and cobalt were selectively extracted into the extraction medium in relation to manganese. Manganese was hardly extracted into the extraction medium.

[0067] (Example 4) Using the same procedure as for preparing the sulfuric acid aqueous solution in Example 1, an aqueous sulfuric acid aqueous solution of Example 4 was prepared with a pH of 0.5 to 1, such that the concentrations of nickel, cobalt, and manganese were each 0.33 mM, and the pH after the extraction reaction was 0.6 to 1.6. 3-(octylcarbamoyl)picolinic acid was dissolved in chloroform to a concentration of 3 mM, tetrabutylammonium perchlorate to a concentration of 3 mM, and trioctylmethylammonium perchlorate to a concentration of 300 mM, to prepare the extraction medium of Example 4 containing a cation exchanger of 3-(octylcarbamoyl)picolinic acid as the extractant.

[0068] Subsequently, mixing, shaking, and centrifugation were performed under the same conditions as in Example 1, and the extraction rates of each metal were calculated. Figure 12 shows the relationship between the pH of the aqueous phase after the extraction reaction and the extraction rates of each metal. As shown in Figure 12, when the pH of the aqueous phase after the extraction reaction was 0.7 or higher, nickel was selectively extracted into the extraction medium compared with manganese and cobalt. When the pH of the aqueous phase after the extraction reaction was 1.5 or higher, cobalt was extracted into the extraction medium. Manganese was hardly extracted into the extraction medium.

[0069] (Example 5) Using the same procedure as in Example 1 for preparing the sulfuric acid aqueous solution, an aqueous sulfuric acid aqueous solution for Example 5 was prepared with a pH of 3.7, such that the concentrations of nickel, cobalt, and manganese were each 0.33 mM, and the pH after the extraction reaction was 3.0. The extraction medium for Example 5 was the same as that used in Example 3. 2.0 mL of the sulfuric acid aqueous solution and 2.0 mL of the extraction medium were placed in a centrifuge tube, and the mixture was shaken using a shaker for 10 to 240 minutes. After that, the mixture was centrifuged under the same conditions as in Example 1, and the extraction rates of each metal were calculated. Figure 13 shows the relationship between shaking time and the extraction rate of each metal. As shown in Figure 13, the extraction reaction of nickel and cobalt reached equilibrium within 10 minutes of shaking.

[0070] <Back extraction after extraction with 3-(octylcarbamoyl)picolinic acid> (Example 6) For Example 6, the sulfuric acid aqueous solution from Example 5 was used. For Example 6, the extraction medium from Example 3 was used. 4.0 mL of the sulfuric acid aqueous solution and 4.0 mL of the extraction medium were placed in a centrifuge tube and shaken for 1 hour using a shaker. After that, the mixture was centrifuged into an aqueous phase and an organic phase under the same conditions as in Example 1, and 2.0 mL of the organic phase from Example 6 was collected. The concentrations of nickel and cobalt in the organic phase before shaking were calculated by "concentration of the target metal in the sulfuric acid aqueous solution of Example 5 - concentration of the target metal in the aqueous phase after the extraction reaction" (the same method was used in the following back-extraction examples).

[0071] 0.1 M, 1.0 M, and 3.0 M sulfuric acid, 0.1 M, 1.0 M, and 3.0 M hydrochloric acid, and 1.0 M aqueous ammonia were used as the back extracts for Example 6. 2.0 mL of the organic phase and 2.0 mL of the back extract were placed in a centrifuge tube and shaken for 1 hour using a shaker. After that, centrifugation was performed under the same conditions as in Example 1, and the concentrations of nickel and cobalt in the back extract were measured, respectively. The back extraction rates of each metal were calculated using the following formula (the same applies to the following back extraction examples). Back extraction rate [%] = Concentration of target metal in back extract after shaking / Concentration of target metal in organic phase before shaking × 100

[0072] Figures 14 to 16 show the relationship between the concentration of the backextract and the backextraction rate of various metals. Figure 14 shows the backextraction rate when sulfuric acid, Figure 15 shows the rate when hydrochloric acid, and Figure 16 shows the rate when ammonia water is used as the backextract. As shown in Figures 14 and 15, nickel and cobalt were backextracted when sulfuric acid or hydrochloric acid with a concentration of 0.1 M or higher was used. From these results, it was found that nickel and cobalt can be efficiently backextracted with an acidic solution with a concentration of 0.1 M or higher. As shown in Figure 16, nickel and cobalt were also backextracted when ammonia water was used, but some of the metal was recovered as a precipitate due to contact between the organic phase and ammonia water during backextraction.

[0073] <Extraction with 2-(octylcarbamoyl)nicotinic acid> (Reference example 1) Following the same procedure as in the preparation of the sulfuric acid aqueous solution in Example 1, sulfuric acid aqueous solutions of Reference Example 1 were prepared with concentrations of nickel, cobalt, and manganese at 0.33 mM each, and with a pH of 0 to 6 such that the pH after the extraction reaction was 0.1 to 6.1. 2-(octylcarbamoyl)nicotinic acid was dissolved in chloroform to a concentration of 3 mM, and tetrabutylammonium perchlorate was dissolved in chloroform to a concentration of 300 mM, to prepare the organic solution of Reference Example 1 containing the cation exchanger of 2-(octylcarbamoyl)nicotinic acid. The extraction medium, mixed with the sulfuric acid aqueous solution whose aqueous phase pH after the extraction reaction was 6.1, was pre-contacted with a metal-free aqueous phase with a pH of 12 to suppress the change in the pH of the sulfuric acid aqueous solution during metal extraction. Subsequently, mixing, shaking, and centrifugation were performed under the same conditions as in Example 1, and the extraction rates of each metal were calculated.

[0074] Figure 17 shows the relationship between the pH of the aqueous phase after the extraction reaction and the extraction rate of various metals. As shown in Figure 17, when the pH of the aqueous phase after the extraction reaction was between 0.1 and 4.4, nickel, cobalt, and manganese were hardly extracted into the extraction medium. Furthermore, when the pH of the aqueous phase after the extraction reaction was 6.1, nickel and cobalt were selectively extracted into the extraction medium relative to manganese. In other words, when the pH of the aqueous phase after the extraction reaction was more acidic, below 3.5, nickel, cobalt, and manganese could not be separated.

[0075] <Extraction with 3-(octylcarbamoyl)picolinic acid, including by-products> (Example 7) Using the same procedure as for preparing the sulfuric acid aqueous solution in Example 1, an aqueous sulfuric acid aqueous solution of Example 7 was prepared with concentrations of nickel, cobalt, and manganese at 0.33 mM each, and with a pH of 0 to 6 such that the pH after the extraction reaction was 0.1 to 6.3. 2-(octylcarbamoyl)nicotinic acid, 3-(octylcarbamoyl)picolinic acid, and tetrabutylammonium perchlorate were dissolved in chloroform at a concentration of 3 mM to prepare the extraction medium of Example 7, which contains the by-product 2-(octylcarbamoyl)nicotinic acid and the cation exchange of the extractant 3-(octylcarbamoyl)picolinic acid.

[0076] For samples where the pH after the extraction reaction was 6.3, the pH change during metal extraction was suppressed by contacting the extraction medium with a metal-free aqueous phase with a pH of 12. Subsequently, mixing, shaking, and centrifugation were performed under the same conditions as in Example 1, and the extraction rates of each metal were calculated. Figure 18 shows the relationship between the pH of the aqueous phase after the extraction reaction and the extraction rates of each metal. As shown in Figure 18, nickel was extracted into the extraction medium when the pH of the aqueous phase after the extraction reaction was 0.6 or higher, cobalt was extracted into the extraction medium when the pH of the aqueous phase after the extraction reaction was 1.6 or higher, and manganese was extracted into the extraction medium when the pH of the aqueous phase after the extraction reaction was 6.3. In addition, when the pH of the aqueous phase after the extraction reaction was between 0.6 and 1.5, nickel was selectively extracted into the extraction medium relative to manganese and cobalt. Furthermore, when the pH of the aqueous phase after the extraction reaction was 2.6 or higher, nickel and cobalt were selectively extracted into the extraction medium relative to manganese.

[0077] Thus, even if 2-(octylcarbamoyl)nicotinic acid, a by-product of the synthesis of 3-(octylcarbamoyl)picolinic acid, is present in the extraction medium, that is, even without separating and removing the by-product 2-(octylcarbamoyl)nicotinic acid from the extractant 3-(octylcarbamoyl)picolinic acid, nickel could be selectively extracted into the extraction medium relative to manganese and cobalt, or nickel and cobalt could be selectively extracted relative to manganese.

[0078] <3-Extraction with (hexadecanoyl carbamoyl)picolinic acid> (Example 8) Using the same procedure as for preparing the sulfuric acid aqueous solution in Example 1, an aqueous sulfuric acid aqueous solution for Example 8 was prepared with a pH of 0 to 6, such that the concentrations of nickel, cobalt, and manganese were each 0.33 mM, and the pH after the extraction reaction was 0 to 3.2. The extraction medium for Example 8 was prepared by dissolving 3-(hexadecanoylcarbamoyl)picolinic acid, the extractant, in chloroform to a concentration of 3 mM.

[0079] 3.0 mL of sulfuric acid aqueous solution and 3.0 mL of extraction medium were placed in a centrifuge tube. Then, under the same conditions as in Example 1, shaking and centrifugation were performed, and the extraction rates of various metals were calculated. Figure 19 shows the relationship between the pH of the aqueous phase after the extraction reaction and the extraction rates of various metals. As shown in Figure 19, when the pH of the aqueous phase after the extraction reaction was 0.9 to 1.7, nickel was selectively extracted into the extraction medium relative to manganese and cobalt. When the pH of the aqueous phase after the extraction reaction was 1.8 to 3.2, nickel and cobalt were selectively extracted into the extraction medium relative to manganese. When the pH of the aqueous phase after the extraction reaction was 1.1 or higher, a white solid, considered to be precipitated extractant, was observed between the organic phase and the aqueous phase.

[0080] <Extraction with 3-(hexadecanoylcarbamoyl)picolinic acid, including by-products> (Example 9) Using the same procedure as for preparing the sulfuric acid aqueous solution in Example 1, an aqueous sulfuric acid aqueous solution for Example 9 was prepared with a pH of 0 to 1.8, such that the concentrations of nickel, cobalt, and manganese were each 0.33 mM, and the pH after the extraction reaction was 0 to 1.8. The extraction medium for Example 9 was prepared by dissolving 2-(hexadecanoylcarbamoyl)nicotinic acid and the extractant 3-(hexadecanoylcarbamoyl)picolinic acid in chloroform to a concentration of 3 mM each.

[0081] 4.0 mL of sulfuric acid aqueous solution and 4.0 mL of extraction medium were placed in a centrifuge tube. Then, under the same conditions as in Example 1, shaking and centrifugation were performed, and the extraction rates of various metals were calculated. Figure 20 shows the relationship between the pH of the aqueous phase after the extraction reaction and the extraction rates of various metals. As shown in Figure 20, when the pH of the aqueous phase after the extraction reaction was 0.8 to 1.8, nickel was selectively extracted into the extraction medium compared to manganese and cobalt. Furthermore, a white solid, presumably precipitated from the extractant, was observed between the organic phase and the aqueous phase in all centrifuge tubes.

[0082] <Extraction with 3-(octylcarbamoyl)-5-octylpicolinic acid> (Example 10) Using the same procedure as for preparing the sulfuric acid aqueous solution in Example 1, an aqueous sulfuric acid aqueous solution for Example 10 was prepared with a pH of 0 to 4.5, such that the concentrations of nickel, cobalt, and manganese were each 0.33 mM, and the pH after the extraction reaction was 0 to 3.2. The extraction medium for Example 10 was prepared by dissolving 3-(octylcarbamoyl)-5-octyl picolinic acid, the extractant, in chloroform to a concentration of 3 mM.

[0083] 4.0 mL of sulfuric acid aqueous solution and 4.0 mL of extraction medium were placed in a centrifuge tube. Then, under the same conditions as in Example 1, shaking and centrifugation were performed, and the extraction rates of various metals were calculated. Figure 21 shows the relationship between the pH of the aqueous phase after the extraction reaction and the extraction rates of various metals. As shown in Figure 21, when the pH of the aqueous phase after the extraction reaction was 0.8 to 2.0, nickel was selectively extracted into the extraction medium compared with manganese and cobalt. Also, when the pH of the aqueous phase after the extraction reaction was 2.4 to 3.2, cobalt was extracted into the extraction medium.

[0084] (Example 11) Following the same procedure as in the preparation of the sulfuric acid aqueous solution in Example 1, sulfuric acid aqueous solutions for Example 11 were prepared with concentrations of nickel, cobalt, and manganese at 0.33 mM each, and pH values ​​of 1.8 and 4.5 respectively, so that the pH after the extraction reaction would be 1.8 and 3.1. The extraction medium for Example 11 was prepared by dissolving 3-(octylcarbamoyl)-5-octyl picolinic acid, the extractant, at a concentration of 3 mM, and 1-octanol, the modifier, at a concentration of 5 vol%, in kerosene. 4.0 mL of the sulfuric acid aqueous solution and 4.0 mL of the extraction medium were placed in a centrifuge tube. Thereafter, shaking and centrifugation were performed under the same conditions as in Example 1, and the extraction rates of each metal were calculated. Figure 22 shows the relationship between the pH of the aqueous phase and the extraction rates of each metal. As shown in Figure 22, when the pH of the aqueous phase after the extraction reaction was 1.8 and 3.1, nickel and cobalt were selectively extracted into the extraction medium relative to manganese.

[0085] (Example 12) The extraction rates of various metals were calculated in the same manner as in Example 11, except that the modifier was changed to tributyl phosphate. Figure 23 shows the relationship between the pH of the aqueous phase after the extraction reaction and the extraction rates of various metals. As shown in Figure 23, when the pH of the aqueous phase after the extraction reaction was 1.8, nickel was selectively extracted into the extraction medium in relation to manganese and cobalt. Also, when the pH of the aqueous phase after the extraction reaction was 3.1, nickel and cobalt were selectively extracted into the extraction medium in relation to manganese.

[0086] <Back extraction after extraction with 3-(octylcarbamoyl)-5-octylpicolinic acid> (Example 13) 2.0 mL of the organic phase containing 3-(octylcarbamoyl)-5-octyl picolinic acid, the extraction medium, was collected when the pH of the aqueous phase after the extraction reaction in Example 9 was 3.2. 0.1 M, 1.0 M, and 3.0 M sulfuric acid were used as the back-extracts for Example 13. 2.0 mL of the organic phase and 2.0 mL of the back-extract were placed in a centrifuge tube and shaken for 1 hour using a shaker. Afterward, centrifugation was performed under the same conditions as in Example 1, and the concentrations of nickel and cobalt in the back-extract were measured. Figure 24 shows the relationship between the concentration of the back-extract and the back-extraction rates of various metals. As shown in Figure 24, nickel and cobalt were back-extracted when sulfuric acid with a concentration of 0.1 M or higher was used. Furthermore, it was found that nickel and cobalt could be efficiently back-extracted using sulfuric acid with a concentration of 1.0 M or higher.

[0087] (Example 14) 2.0 mL of the organic phase containing 3-(octylcarbamoyl)-5-octyl picolinic acid, the extraction medium, was taken when the pH of the aqueous phase after the extraction reaction in Example 11 was 3.1. 3.0 M sulfuric acid was used as the back-extract in Example 14. The concentrations of nickel and cobalt in the back-extract were then measured in the same manner as in Example 13. Figure 25 shows the relationship between the concentration of the back-extract and the back-extraction rates of various metals. As shown in Figure 25, nickel and cobalt were efficiently back-extracted.

[0088] (Example 15) 2.0 mL of the organic phase containing 3-(octylcarbamoyl)-5-octyl picolinic acid, the extraction medium, was taken when the pH of the aqueous phase after the extraction reaction in Example 12 was 3.1. 3.0 M sulfuric acid was used as the back-extract in Example 15. The concentrations of nickel and cobalt in the back-extract were then measured in the same manner as in Example 13. Figure 26 shows the relationship between the concentration of the back-extract and the back-extraction rates of various metals. As shown in Figure 26, nickel and cobalt were efficiently back-extracted.

Claims

1. A compound represented by the following general formula (1). 【Chemistry 1】 However, R １ R is a hydrocarbon group having 1 to 16 carbon atoms. ２ , R ３ , and R ４ Each of these is independently either hydrogen or a hydrocarbon group having 1 to 16 carbon atoms.

2. A compound represented by the following general formula (2). 【Chemistry 2】 However, R １ R is a hydrocarbon group having 1 to 16 carbon atoms. ２ , R ３ , and R ４ Each of these is independently a hydrogen atom or a hydrocarbon group having 1 to 16 carbon atoms. Cat is a cation of ammonium, monoalkylammonium, dialkylammonium, trialkylammonium, tetraalkylammonium, tetraalkylphosphonium, lithium, sodium, potassium, rubidium, or cesium.

3. In claim 1 or 2, R １ is an n-octyl group, and R ２ , R ３ , and R ４ is a compound where R is hydrogen.

4. In claim 1 or 2, R １ is an n-hexadecyl group, R ２ , R ３ , and R ４ A compound in which hydrogen is present.

5. In claim 1 or 2, R １ and R ３ is an n-octyl group, R ２ and R ４ A compound in which hydrogen is present.

6. A method for producing a compound, comprising reacting a compound represented by the following general formula (3) with a compound represented by the following general formula (4) to synthesize a compound represented by the following general formula (1). 【Transformation 3】 【Chemistry 4】 【Chemistry 1】 However, R １ R is a hydrocarbon group having 1 to 16 carbon atoms. ２ , R ３ , and R ４ Each of these is independently either hydrogen or a hydrocarbon group having 1 to 16 carbon atoms.

7. An extraction medium for selectively extracting nickel from manganese and cobalt, or selectively extracting nickel and cobalt from manganese, from an acidic aqueous solution containing nickel, cobalt, and manganese, An extraction medium containing one or more compounds represented by the following general formula (1) and / or the following general formula (2), and a hydrophobic liquid. 【Chemistry 1】 【Chemistry 2】 However, R １ R is a hydrocarbon group having 1 to 16 carbon atoms. ２ , R ３ , and R ４ Each of these is independently a hydrogen atom or a hydrocarbon group having 1 to 16 carbon atoms. Cat is a cation of ammonium, monoalkylammonium, dialkylammonium, trialkylammonium, tetraalkylammonium, tetraalkylphosphonium, lithium, sodium, potassium, rubidium, or cesium.

8. An extraction method for selectively extracting nickel from manganese and cobalt, or selectively extracting nickel and cobalt from manganese, using the extraction medium of claim 7, wherein the extraction method is for selectively extracting nickel from manganese and cobalt, or selectively extracting nickel and cobalt from manganese, An extraction method comprising an extraction step of contacting the extraction medium with the aqueous solution to obtain a hydrophobic phase in which nickel, or nickel and cobalt, are extracted into the extraction medium.

9. In claim 8, An extraction method wherein the pH of the aqueous solution is 6.0 or less.

10. In claim 8 or 9, An extraction method further comprising a back-extraction step of contacting the hydrophobic phase with an acidic solution with a pH of 1 or less to back-extract nickel, or nickel and cobalt, into the acidic solution.

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