Method for separating transition metals

Abstract

To provide a method that enables simpler and more efficient separation of transition metals that frequently exhibit chemical or physical similarity.SOLUTION: This invention provides a method in which, from a solution containing at least two transition metals (one being selected from the group consisting of cobalt, nickel, and iron), each transition metal is precipitated respectively as a ferromagnetic metal and as a paramagnetic or diamagnetic material, and is then separated by utilizing their magnetic differences.SELECTED DRAWING: Figure 9

Description

[Technical Field]

[0001] The present invention relates to a method for separating and recovering transition metals. [Background technology]

[0002] Rare metals are contained in waste materials generated during the electronics industry's manufacturing process for electronic materials, as well as in used batteries, such as lithium-ion secondary batteries. Rare metals are essential materials in a wide range of industries, and therefore the development of recycling technologies for rare metals is highly desirable.

[0003] For example, Patent Document 1 discloses a method for producing metal particles (A) of metal (a) by reducing the ions of metal (a) using a mixed solution containing ions of metal (a) and ions of metal (b), which is a different metal species from the metal (a), through the following steps (1) or (2): (1) separating the ions of metal (a) from the mixed solution and converting them into a metal hydroxide of metal (a), and then subjecting the metal hydroxide to a solvothermal reaction in the presence of an organic solvent (C1) capable of reducing the ions of metal (a) to produce metal particles (A); and (2) subjecting the mixed solution to a solvothermal reaction in the presence of an organic solvent (C2) capable of reducing the ions of metal (a) but not the ions of metal (b), to produce metal particles (A).

[0004] Patent Document 2 discloses a method for separating a metal to be separated using a metal coordinate having an oxide of the metal to be separated as a core, the method including the steps of dispersing the metal coordinate in a solution containing the metal to be separated and separating the metal to be separated in the solution as an oxide of the metal to be separated.

[0005] Patent Document 3 discloses a method for recovering metals from lithium-ion battery waste, which includes a wet treatment in which metals including lithium in the lithium-ion battery waste are leached with an acid and the metal is extracted from a metal-containing solution in which the metal is dissolved, and the lithium extracted by the wet treatment is used as a pH adjuster used in the wet treatment. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-53365 [Patent Document 2] Japanese Patent Application Publication No. 2023-153726 [Patent Document 3] Japanese Patent Application Publication No. 2023-100269 Summary of the Invention [Problem to be solved by the invention]

[0007] Lithium-ion secondary batteries (LIBs), which are used as batteries in electric vehicles (EVs), which are becoming increasingly popular around the world, contain rare metals such as cobalt (Co), manganese (Mn), and transition metals including nickel (Ni) as constituent elements. There are concerns that the prices of these rare metals will rise as demand expands in the future.

[0008] Since rare metals are being depleted in domestic mines, LIBs for EVs, which use huge amounts of rare metals, could become effective urban mines of rare metals in the form of discarded batteries after use.

[0009] However, transition metals, especially Co, Mn, and Ni, have similar chemical and / or physical properties, and no cost-effective separation method has yet been established. Table 1 summarizes the properties of each element.

[0010] [Table 1]

[0011] Therefore, at present, these waste batteries are either discarded or used as raw materials for asphalt.

[0012] Meanwhile, the EU (European Union) has imposed regulations requiring the use of recycled rare metals in LIBs. Specifically, the regulations require that 12% of Co and 4% of Ni be replaced with recycled Co and Ni by 2030, and that 20% of Co and 12% of Ni be replaced with recycled Co and Ni by 2035.

[0013] Therefore, the development of an efficient method for separating transition metals including Co, Mn, and Ni is an urgent issue.

[0014] Among transition metals, especially Co, Mn, and Ni, the separation of Mn is carried out by the Volhard reaction (3Mn 2+ +2MnO4 - +2H2O → 5MnO2+4H + ) by Mn 2+ One method is to oxidize the ions and precipitate them as insoluble MnO2, which can separate and recover transition metals, especially Co and Mn, with a recovery rate (%) of Co / Mn / Ni = 8 / 95 / 0 and a purity of 98%.

[0015] However, although Co and Ni are rarer than Mn, an efficient separation method has not yet been established.

[0016] Therefore, an object of the present invention is to provide a simpler and more efficient method for separating transition metals that are often chemically or physically similar to one another. [Means for solving the problem]

[0017] As a result of examining various means for solving the above-mentioned problems, the present inventors have found that in a polyol method used for a reduction reaction of metal ions, a cobalt-nickel solution containing cobalt and nickel as metal ions and an ethylene glycol solution containing ethylene glycol and sodium hydroxide are used as reaction solutions, and the concentrations of each material in the reaction system are controlled by changing the rate at which the cobalt-nickel solution is added dropwise to the ethylene glycol solution, thereby making it possible to produce nickel as metallic Ni, which is a ferromagnetic material, and cobalt as a mixture of Co(OH)2 and metallic Co, which does not exhibit ferromagnetism, and further that these can be separated by magnetic force using a magnet due to the difference in magnetic properties, thereby completing the present invention.

[0018] That is, the gist of the present invention is as follows. (1) A method for separating a first transition metal from a second transition metal, comprising: the first transition metal is a metal selected from the group consisting of cobalt, nickel, and iron; the second transition metal is a transition metal different from the first transition metal; The method comprises: (I) a step of mixing a first solution containing a first transition metal and a second transition metal, each in an ionic form, with a polyol solution containing a polyol and a base to produce a first precipitate, The first solution and the polyol solution are mixed at a contact speed under a certain temperature and atmosphere so that the first precipitate becomes a precipitate containing a first transition metal that is ferromagnetic and a second transition metal that is paramagnetic or diamagnetic; The process and (II) separating the first transition metal, which is a ferromagnetic substance, and the second transition metal, which is a paramagnetic substance or a diamagnetic substance, from the first precipitate by utilizing the difference in magnetic properties; A method comprising: (2) The method according to (1), wherein the second transition metal is a transition metal different from the first transition metal selected from the group consisting of cobalt, nickel, and iron. (3) (I) is (Ii) mixing a second solution containing a first transition metal in ionic form with a polyol solution containing a polyol and a base to form a second precipitate, changing the contact speed at which the second solution and the polyol solution are mixed under the same temperature and atmosphere as in step (I), and determining the contact speed at which the second precipitate becomes a precipitate containing 90 wt % or more of the first transition metal that is a ferromagnetic material relative to the total weight of the second precipitate; Process, and (I-ii) mixing a third solution containing a second transition metal in an ionic form with a polyol solution containing a polyol and a base to produce a third precipitate, changing the contact speed at which the third solution and the polyol solution are mixed under the same temperature and atmosphere as in step (I), and determining the contact speed at which the third precipitate becomes a precipitate containing 90 wt % or more of the oxide and / or hydroxide of the second transition metal that is a diamagnetic material, based on the total weight of the third precipitate; Process Including, In step (I), the first solution and the polyol solution are mixed at a contact speed in a speed range where the contact speed determined in step (Ii) and the contact speed determined in step (I-ii) overlap. The method described in (2). (4) The method according to (1), wherein the second transition metal is a transition metal other than cobalt, nickel, and iron. (5) (I) is (Ii) mixing a second solution containing a first transition metal in ionic form with a polyol solution containing a polyol and a base to form a second precipitate, changing the contact speed at which the second solution and the polyol solution are mixed under the same temperature and atmosphere as in step (I), and determining the contact speed at which the second precipitate becomes a precipitate containing 90 wt % or more of the first transition metal that is a ferromagnetic material relative to the total weight of the second precipitate; Process Including, In step (I), the first solution and the polyol solution are mixed at the contact rate determined in step (Ii). (4) The method described in (4). (6) The method according to any one of (1) to (5), wherein the first transition metal is nickel. (7) The method according to any one of (1) to (3) and (6) (excluding the case where (6) refers to (4) or (5)), wherein the second transition metal is cobalt. (8) The method according to any one of (1) to (7), wherein in step (I), the polyol solution is an ethylene glycol solution, and the solvent of the first solution is ethylene glycol. (9) The method according to any one of (1) to (8), wherein in step (I), the first solution and the polyol solution are mixed at atmospheric pressure at the boiling point of the polyol solution. (10) The method according to any one of (1) to (9), wherein in step (I), the contact rate between the first solution and the polyol solution is 0.070 mmol / min to 1,000 mmol / min. (11) The method according to any one of (1) to (10), wherein in step (I), the content of the first transition metal in the first solution is 0.1 mol / L to 1.0 mol / L, and the content of the second transition metal in the first solution is 0.1 mol / L to 1.0 mol / L. (12) The method according to any one of (1) to (5), wherein the first transition metal is cobalt. (13) The method according to (12), wherein in step (I), the polyol solution is an ethylene glycol solution, and the solvent of the first solution is ethylene glycol. (14) The method according to (12) or (13), wherein in step (I), the first solution and the polyol solution are mixed at atmospheric pressure at the boiling point of the polyol solution. (15) The method according to any one of (12) to (14), wherein in step (I), the contact rate between the first solution and the polyol solution is 0.062 mmol / min or less. (16) The method according to any one of (12) to (15), wherein in step (I), the content of cobalt in the first solution is 0.1 mol / L to 1.0 mol / L, and the content of the second transition metal in the first solution is 0.1 mol / L to 1.0 mol / L. (17) The method according to any one of (1) to (16) for recovering nickel and / or cobalt from waste lithium ion secondary batteries. [Effects of the Invention]

[0019] The present invention provides a simpler and more efficient method for separating transition metals that are often chemically or physically similar. [Brief explanation of the drawings]

[0020] [Figure 1] This is an image diagram of the direction in which magnetism is generated in ferromagnetic, paramagnetic, and diamagnetic materials in response to a magnetic field. [Figure 2] 1 is a scheme illustrating one embodiment of the present invention. [Figure 3] 1 is a diagram schematically illustrating an apparatus used in an experiment of an example and the state of the experiment. FIG. [Figure 4] 1 is a table showing the experimental conditions, the obtained products, magnetic properties, yields, and appearance photographs for Experiments (Ni) 1 to 5 of Experiment 1-1. [Figure 5] 1 is a graph showing XRD spectra of products of Experiments (Ni) 1 to 5 in Experiment 1-1. [Figure 6] 1 is a table showing the experimental conditions, the obtained products, magnetic properties, yields, and appearance photographs for Experiments (Co) 1 to 5 of Experiment 1-2. [Figure 7] 1 is a graph showing XRD spectra of the products of Experiments (Co) 1 to 5 in Experiment 1-2. [Figure 8] 1 is a table summarizing the products formed by changing the dropping rate based on the results of Experiments 1-1 and 1-2. [Figure 9] FIG. 1 shows an outline of a method for separating and recovering Co and Ni from a cobalt-nickel solution ([Co 2+ ] = [Ni 2+ ] = 0.20 mol / L) and the results thereof. [Figure 10] FIG. 1 shows an outline of a method for separating and recovering Co and Ni from a cobalt-nickel solution ([Co 2+ ] = [Ni 2+ ] = 0.15 mol / L) and the results thereof. DETAILED DESCRIPTION OF THE INVENTION

[0021] Preferred embodiments of the present invention will now be described in detail. In this specification, the features of the present invention will be described with reference to the drawings as appropriate. In the drawings, the dimensions and shapes of each part are exaggerated for clarity and do not accurately depict the actual dimensions and shapes. Therefore, the technical scope of the present invention is not limited to the dimensions and shapes of each part shown in these drawings. Note that the present invention is not limited to the following embodiments, and can be embodied in various forms including modifications and improvements that can be made by those skilled in the art without departing from the gist of the present invention.

[0022] The present invention relates to a method for separating a first transition metal and a second transition metal, wherein the first transition metal is one metal selected from the group consisting of cobalt, nickel, and iron, and the second transition metal is a transition metal different from the first transition metal, the method comprising: (I) a step of mixing a first solution containing the first transition metal and the second transition metal, each in an ionic form, with a polyol solution containing a polyol and a base to produce a first precipitate, wherein the first solution and the polyol solution are mixed under a certain temperature and atmosphere at a contact speed such that the first precipitate becomes a precipitate containing the first transition metal that is a ferromagnetic substance and a second transition metal that is a paramagnetic or diamagnetic substance; and (II) a step of separating the ferromagnetic first transition metal and the paramagnetic or diamagnetic second transition metal substance from the first precipitate by utilizing the difference in magnetism.

[0023] In the present invention, the reaction conditions are not limited except for the first transition metal, the second transition metal, and the contact rate between the first solution and the polyol solution, which will be described in detail below. One embodiment of the reaction conditions is shown below.

[0024] <First solution> The first solution contains the first transition metal and the second transition metal, each in the form of an ion. Therefore, the solvent for the first solution is not limited as long as it can dissolve the first transition metal and the second transition metal, each in the form of an ion. Solvents for the first solution include, for example, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-hexadecanediol, 1,4-butanediol, 1,4-pentanediol, methanol, ethanol, propanol, 2-propanol, butanol, water, and mixtures of two or more of these. When the solvent for the first solution is a glycol-based solvent, such as ethylene glycol, the solvent can also function as a reactant that reacts with the ions of the first transition metal and / or the ions of the second transition metal after contact with the polyol solution (particularly the base in the polyol solution) in the polyol method in step (I). In one embodiment, the solvent of the first solution is the same polyol as the polyol contained in the polyol solution, for example, ethylene glycol.

[0025] The first solution may be prepared by placing waste materials such as waste materials discharged in the manufacturing process of electronic materials in the electronics industry or used waste batteries, e.g., waste lithium-ion secondary batteries, in a solvent, e.g., water, and adding an acid, e.g., sulfuric acid, to dissolve the transition metal from the waste materials, and then optionally concentrating the solution or changing the solvent.

[0026] (first transition metal) In the present invention, the first transition metal is one metal selected from the group consisting of cobalt, nickel, and iron. In the present invention, the first transition metal is reduced to a metal by adjusting the contact rate between the first solution and the polyol solution in the polyol method in step (I), and is precipitated as a ferromagnetic transition metal. As a result, in step (II), the first transition metal can be separated by magnetic force due to its difference in magnetic properties from the second transition metal.

[0027] The first transition metal is dissolved in the first solution in the form of an ion. The first transition metal is, for example, Ni 2+ , Co 2+ , Fe 2+ , Fe 3+ The salt of the first transition metal, which allows the first transition metal to exist as an ion in the first solution, is not limited as long as it can be dissolved in the solvent of the first solution, and examples thereof include halides, such as fluorides, chlorides, bromides, and iodides, sulfates, nitrates, phosphates, carboxylates, such as acetates and sulfonates, and mixtures of two or more of the above. Note that the salt of the first transition metal also includes hydrates. In one embodiment, the salt of the first transition metal is a sulfate.

[0028] The concentration of the first transition metal ion in the first solution is not limited as long as the first transition metal forms an ion in the solvent. The concentration of the first transition metal ion in the first solution is usually 0.1 mol / L to 1.0 mol / L, and in one embodiment, 0.2 mol / L to 0.6 mol / L.

[0029] In one embodiment, the first transition metal is nickel. In one embodiment, the salt of the first transition metal is nickel sulfate hexahydrate.

[0030] In one embodiment, the first transition metal is cobalt. In one embodiment, the salt of the first transition metal is cobalt sulfate heptahydrate.

[0031] In one embodiment, the first transition metal is iron. In one embodiment, the salt of the first transition metal is iron sulfate.

[0032] (second transition metal) The second transition metal is a transition metal different from the first transition metal.

[0033] Embodiment 1 In embodiment 1, the second transition metal includes one transition metal different from the first transition metal selected from the group consisting of cobalt, nickel, and iron. In this embodiment, the second transition metal may further include a transition metal other than cobalt, nickel, and iron. In this embodiment, the second transition metal is preferably one transition metal different from the first transition metal selected from the group consisting of cobalt, nickel, and iron. In this embodiment, the one transition metal different from the first transition metal selected from the group consisting of cobalt, nickel, and iron is precipitated as a compound, most of which is diamagnetic, such as an oxide and / or hydroxide, by adjusting the contact rate between the first solution and the polyol solution in the polyol method in step (I). Therefore, in the polyol method in step (I), the one transition metal selected from the group consisting of cobalt, nickel, and iron in the second transition metal is prevented from being reduced to a ferromagnetic metal. Furthermore, among the second transition metals, transition metals other than cobalt, nickel, and iron are precipitated in the polyol method in step (I) as one or more paramagnetic or diamagnetic compounds, such as oxides and hydroxides, and metals. Note that transition metals other than cobalt, nickel, and iron do not become ferromagnetic, whether precipitated as compounds, such as oxides and / or hydroxides, or as metals. As a result, the second transition metal can be separated by magnetic force in step (II) due to its difference in magnetic properties from the first transition metal.

[0034] In the first embodiment, the second transition metal is dissolved in the first solution in the form of an ion. The second transition metal is, for example, Ni 2+ , Co 2+ , Fe 2+ , Fe 3+The salt of the second transition metal, which allows the second transition metal to exist as an ion in the first solution, is not limited as long as it can be dissolved in the solvent of the first solution, and examples thereof include halides, such as fluorides, chlorides, bromides, and iodides, sulfates, nitrates, phosphates, carboxylates, such as acetates and sulfonates, and mixtures of two or more of these salts of the second transition metal. Note that the salt of the second transition metal also includes hydrates. In one embodiment, the salt of the second transition metal is a sulfate.

[0035] In embodiment 1, the second transition metal comprises cobalt. In embodiment 1, the second transition metal is cobalt. In one embodiment, the salt of the second transition metal comprises a sulfate, for example, cobalt sulfate heptahydrate.

[0036] In embodiment 1, the second transition metal comprises nickel. In embodiment 1, the second transition metal is nickel. In one embodiment, the salt of the second transition metal comprises a sulfate, for example, nickel sulfate hexahydrate.

[0037] In embodiment 1, the second transition metal comprises iron. In embodiment 1, the second transition metal is iron. In one embodiment, the salt of the second transition metal is a sulfate, for example, iron sulfate.

[0038] Embodiment 2 In embodiment 2, the second transition metal includes one or more transition metals other than cobalt, nickel, and iron, e.g., one, two, three, four, or five or more. In embodiment 2, the second transition metal is precipitated in the polyol method as one or more paramagnetic or diamagnetic compounds, such as oxides and hydroxides, and metals. In embodiment 2, the second transition metal is a transition metal other than cobalt, nickel, and iron. Therefore, as described above, the second transition metal does not become ferromagnetic whether precipitated as a compound, such as an oxide and / or hydroxide, or as a metal. Therefore, in embodiment 2, the second transition metal may be precipitated as an oxide and / or hydroxide or reduced to a metal in the polyol method in step (I). As a result, the second transition metal can be separated by magnetic force in step (II) due to its difference in magnetic properties from the first transition metal.

[0039] In embodiment 2, the second transition metal is scandium (Sc), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), copper (Cu), yttrium (Y), zirconium (Zr), niobium (Nb), molybdenum (Mo), technetium (Tc), ruthenium (Ru), rhodium (Rh), palladium (Pd), silver (Ag), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), The metal is one or more, for example, one, two, three, four, or five or more metals selected from the group consisting of gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Lu), hafnium (Hf), tantalum (Ta), tungsten (W), rhenium (Re), osmium (Os), iridium (Ir), platinum (Pt), gold (Au), zinc (Zn), cadmium (Cd), and mercury (Hg).

[0040] In embodiment 2, the second transition metal is dissolved in ionic form in the first solution. The second transition metal is, for example, Sc 3+, T.I. 3+ , V 2+ , Cr 2+ , Cr 3+ In the second embodiment, the salt of the second transition metal, which allows the second transition metal to exist as an ion in the first solution, is not limited as long as it can be dissolved in the solvent of the first solution, and examples thereof include halides of the second transition metal, such as fluorides, chlorides, bromides, and iodides, sulfates, nitrates, phosphates, carboxylates, such as acetates and sulfonates, and mixtures of two or more thereof. Note that the salt of the second transition metal also includes hydrates. In the second embodiment, the salt of the second transition metal is a sulfate.

[0041] In the first and second embodiments, the concentration of the second transition metal ions in the first solution is not limited as long as the second transition metal forms ions in the solvent. The concentration of the second transition metal ions in the first solution is typically 0.1 mol / L to 1.0 mol / L, and in one embodiment, 0.2 mol / L to 0.6 mol / L.

[0042] In Embodiment 1 and Embodiment 2, the molar ratio of the first transition metal ions to the second transition metal ions in the first solution (first transition metal ions / second transition metal ions) is not limited. The molar ratio is, for example, typically 0.1 to 10, 0.5 to 2 in one embodiment, 0.6 to 1.5 in one embodiment, 0.8 to 1.2 in another embodiment, e.g., 1.

[0043] <Polyol solution> The polyol contained in the polyol solution is a reactant that becomes a polyol ion under the action of a base and reacts with ions of a first transition metal and / or a second transition metal. This polyol is not limited to polyols used in polyol processes known in the art, and can be any polyol. Here, "polyol ion" refers to an ion formed by removing a proton from a hydroxyl group in a polyol. Polyol ions include monopolyol ions, dipolyol ions, and the like. Examples of polyols include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-hexadecanediol, 1,4-butanediol, and 1,4-pentanediol, as well as mixtures of two or more of these. In one embodiment, the polyol is ethylene glycol. Polyols that do not become polyol ions under the action of a base can also function as a solvent in the polyol solution.

[0044] The concentration of the polyol in the polyol solution is not limited. The concentration of the polyol in the polyol solution is usually adjusted so that the amount of polyol ions formed by the base is equal to or greater than the amount (equivalent) that reacts with the ions of the first transition metal and the second transition metal. The concentration of the polyol ions in the polyol solution is usually 0.1 mol / L to 5.0 mol / L, in one embodiment 0.2 mol / L to 2.0 mol / L, and in one embodiment 0.2 mol / L to 1.0 mol / L.

[0045] The base contained in the polyol solution is not limited, and any base used in a polyol method known in the art can be used, including, for example, lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide, tetramethylammonium hydroxide, tetraethylammonium hydroxide, calcium hydroxide, strontium hydroxide, barium hydroxide, and mixtures of two or more thereof.

[0046] The concentration of the base in the polyol solution is not limited. The concentration of the base in the polyol solution is usually adjusted to an amount necessary to form polyol ions in an amount (equivalent) equal to or greater than the amount of polyol reacting with the ions of the first transition metal and the second transition metal. The concentration of the base in the polyol solution is usually 0.1 mol / L to 5.0 mol / L, in one embodiment 0.2 mol / L to 2.0 mol / L, and in one embodiment 0.2 mol / L to 1.0 mol / L.

[0047] The polyol solution may further contain a solvent, such as, but not limited to, methanol, ethanol, propanol, 2-propanol, butanol, water, and a mixture of two or more of these.

[0048] The quantitative relationship between the first transition metal and second transition metal ions in the first solution and the polyol ions and / or hydroxide ions in the polyol solution is not limited. The quantitative relationship between the first transition metal and second transition metal ions in the first solution and the polyol ions and / or hydroxide ions in the polyol solution is usually adjusted so that all of the first transition metal and second transition metal ions contained in the first solution react with the polyol ions and / or hydroxide ions in the polyol solution. Therefore, the polyol ions and / or hydroxide ions in the polyol solution may be present in excess relative to all of the first transition metal and second transition metal ions contained in the first solution.

[0049] The quantitative relationship between the first solution and the polyol solution is not limited. The volume ratio between the first solution and the polyol solution (first solution / polyol solution) is usually 0.1 to 10, and in one embodiment, 0.5 to 2. By setting the quantitative relationship between the first solution and the polyol solution within the above range, the reaction can be carried out efficiently.

[0050] <Step (I)> In step (I), a first solution containing a first transition metal and a second transition metal, each in the form of an ion, is mixed with a polyol solution containing a polyol and a base to produce a first precipitate. The first solution and the polyol solution are mixed at a constant temperature and atmosphere at a contact speed such that the first precipitate contains a ferromagnetic first transition metal and a paramagnetic or diamagnetic second transition metal.

[0051] The "constant temperature" in step (I) refers to the reaction temperature at which step (I) is carried out. The constant temperature is not limited, and temperatures used in polyol processes known in the art can be used. The constant temperature usually does not fluctuate and is between the melting point and boiling point of the solvents in the first solution and the polyol solution, for example, usually 0°C or higher, in one embodiment 10°C or higher, in one embodiment 50°C or higher, and in one embodiment 100°C or higher, and for example, usually 500°C or lower, in one embodiment 400°C or lower, and in one embodiment 300°C or lower. In one embodiment, the constant temperature is the boiling point of the solvent, for example, about 200°C, specifically 197°C, when the solvent is ethylene glycol.

[0052] The "certain atmosphere" in step (I) refers to the reaction atmosphere in which step (I) is carried out. The certain atmosphere is not limited, and an atmosphere used in a polyol method known in the art can be used. The certain atmosphere is usually unchanged and is an inert atmosphere, such as a nitrogen (N) atmosphere, an argon (Ar) atmosphere, or a reducing atmosphere, such as a hydrogen (H) atmosphere.

[0053] The mixing conditions in step (I) are not limited. For example, the mixing of the first solution and the polyol solution may be carried out by dropping the first solution into the polyol solution at atmospheric pressure. For example, the mixing of the first solution and the polyol solution may be carried out by dropping the polyol solution into the first solution at atmospheric pressure. For example, the mixing of the first solution and the polyol solution may be carried out by dropping the first solution and the polyol solution simultaneously into a reaction site, for example, a reaction solvent, at atmospheric pressure. Here, atmospheric pressure refers to a reduced pressure, for example, a low vacuum, 10 5 Pa~10 2 10 Pa, which is a medium vacuum 2 Pa~10 -1 10 Pa, high vacuum -1 Pa~10 -5 10 Pa, which is ultra-high vacuum -5 Pa~10 -8 10 Pa, or extremely high vacuum -8 It may be changed to Pa or less.

[0054] Here, the mixing is carried out so that the first solution and the polyol solution come into contact with each other quickly. That is, for example, when the first solution and the polyol solution are mixed by adding the first solution dropwise to the polyol solution, the mixing is carried out by stirring the polyol solution so that the ions of the first transition metal and / or the second transition metal in the first solution that react upon dropping (e.g., one or more selected from the group consisting of ions, complexes, oxides, hydroxides, carbonates, and metals containing the first transition metal and / or the second transition metal) move immediately after the reaction, more specifically, move at a speed faster than the contact speed described below, so that the ions of the first transition metal and / or the second transition metal in the newly added first solution can react with the polyol ions and / or hydroxide ions in the new polyol solution. Similarly, for example, when the first solution and the polyol solution are mixed by adding the polyol solution dropwise to the first solution, the mixing is carried out by stirring the first solution so that the polyol ions and / or hydroxide ions (e.g., one or more selected from the group consisting of ions, complexes, hydroxides, and oxides containing polyol ions and / or hydroxide ions) in the polyol solution that have reacted by adding the polyol dropwise move immediately after the reaction, more specifically, move at a rate faster than the contact rate described below, so that the polyol ions and / or hydroxide ions in the newly added polyol can react with the ions of the first transition metal and / or the second transition metal in the new first solution. Furthermore, for example, when the first solution and the polyol solution are mixed by simultaneously dropping the first solution and the polyol solution into a reaction site, for example, a reaction solvent, the mixing is carried out by stirring the reaction site so that the ions of the first transition metal and / or the second transition metal in the dropped first solution and the polyol ions and / or hydroxide ions in the dropped polyol solution come into contact with each other immediately after dropping, more specifically, at a contact rate described below, so that they can react.

[0055] In one embodiment, the mixing is carried out under stirring as described above. The stirring means is not limited. The stirring means may be, for example, stirring with a stirrer, such as a propeller stirrer or a magnetic stirrer (stir bar), stirring by flowing the reaction solution itself, or bubbling, for example, stirring by microbubbles.

[0056] The stirring speed is usually higher than the contact speed described below. By setting the stirring speed higher than the contact speed, the first solution and the polyol solution can react in a manner that depends on the contact speed.

[0057] The "contact rate" in step (I) refers to the rate at which equivalent amounts of first transition metal or second transition metal ions in the first solution come into contact with polyol ions and / or hydroxide ions in the polyol solution that react with the ions. "Equivalent amount" refers to the amount of substances that react with each other in the exact amount. In the present invention, equivalent amount refers to the amount based on the number of moles of first transition metal or second transition metal ions. Therefore, equivalent amount refers to the number of moles of polyol ions and / or hydroxide ions in the polyol solution that react with 1 mole of first transition metal or second transition metal ions. For example, when the first solution and the polyol solution are mixed by adding the first solution dropwise to the polyol solution, the contact rate refers to the rate at which the first transition metal or second transition metal ions in the first solution are added dropwise. For example, when the first solution and the polyol solution are mixed by adding the polyol solution dropwise to the first solution, the contact rate is the rate at which an equivalent amount of polyol ions and / or hydroxide ions in the polyol solution is added dropwise. For example, when the first solution and the polyol solution are mixed by simultaneously adding the first solution and the polyol solution dropwise to a reaction site, such as a reaction solvent, the contact rate is the slower of the rate at which the ions of the first transition metal or the second transition metal in the first solution are added dropwise to the reaction site and the rate at which an equivalent amount of polyol ions and / or hydroxide ions in the polyol solution are added dropwise to the reaction site. In one embodiment, in consideration of ease of setting the contact rate, the first solution and the polyol solution are mixed by adding the first solution dropwise to the polyol solution, and the contact rate is set as the rate at which the ions of the first transition metal or the second transition metal in the first solution are added dropwise.

[0058] In the polyol method of step (I), the contact rate between the first solution and the polyol solution for precipitating the first transition metal as a metal exhibiting ferromagnetism can be determined by, for example, (Ii) a step of mixing a second solution containing a first transition metal in an ionic form with a polyol solution containing a polyol and a base to produce a second precipitate, wherein the contact speed at which the second solution is mixed with the polyol solution is changed under the same temperature and atmosphere as in step (I) to determine the contact speed at which the second precipitate contains 90% by weight or more, in one embodiment 91% by weight or more, in one embodiment 92% by weight or more, in one embodiment 95% by weight or more, and in one embodiment 99% by weight or more of the first transition metal that is a ferromagnetic material, based on the total weight of the second precipitate. This can be carried out by:

[0059] More specifically, it is as follows. (Ii-1) A second solution containing a first transition metal in ionic form is prepared. (Ii-2) A polyol solution containing a polyol and a base is prepared. (Ii-3) The second solution and the polyol solution are mixed at a constant contact speed under the same temperature and atmosphere as in step (I) to produce a second precipitate. (Ii-4) Confirm the composition of the second precipitate. (Ii-5) Steps (Ii-1) to (Ii-4) are repeated with the contact speed changed. (Ii-6) By repeating steps (Ii-1) to (Ii-5), the contact speed is determined so that the second precipitate contains the first transition metal, which is a ferromagnetic material, in an amount of 90% by weight or more, in one embodiment 91% by weight or more, in one embodiment 92% by weight or more, in one embodiment 95% by weight or more, and in one embodiment 99% by weight or more, based on the total weight of the second precipitate.

[0060] When the second transition metal is a transition metal different from the first transition metal selected from the group consisting of cobalt, nickel, and iron as in the first embodiment, in the polyol method in step (I), the contact rate between the first solution and the polyol solution for precipitating the second transition metal as a diamagnetic compound, for example, an oxide and / or hydroxide, can be determined by, for example, (I-ii) a step of mixing a third solution containing a second transition metal in an ionic form with a polyol solution containing a polyol and a base to produce a third precipitate, in which the contact speed at which the third solution is mixed with the polyol solution is changed under the same temperature and atmosphere as in step (I) to determine the contact speed at which the third precipitate contains diamagnetic oxides and / or hydroxides of the second transition metal in an amount of 90% by weight or more, in one embodiment 91% by weight or more, in one embodiment 92% by weight or more, in one embodiment 95% by weight or more, and in one embodiment 99% by weight or more, based on the total weight of the third precipitate; It can be carried out by a process.

[0061] Specifically, it can be carried out as follows. (I-ii-1) A third solution containing a second transition metal in ionic form is prepared. (I-ii-2) A polyol solution containing a polyol and a base is prepared. (I-ii-3) The third solution and the polyol solution are mixed at a constant contact speed under the same temperature and atmosphere as in step (I) to produce a third precipitate. (I-ii-4) Confirm the composition of the third precipitate. (I-ii-5) Steps (I-ii-1) to (I-ii-4) are repeated with the contact speed changed. (I-ii-6) By repeating steps (I-ii-1) to (I-ii-5), a contact speed is determined at which the third precipitate becomes a precipitate containing a compound of the second transition metal, which is a diamagnetic material, in an amount of 90% by weight or more, in one embodiment 91% by weight or more, in one embodiment 92% by weight or more, in one embodiment 95% by weight or more, and in one embodiment 99% by weight or more, based on the total weight of the third precipitate.

[0062] Furthermore, when the second transition metal further contains a transition metal other than cobalt, nickel, and iron in addition to one type of transition metal different from the first transition metal selected from the group consisting of cobalt, nickel, and iron, the transition metal other than cobalt, nickel, and iron does not become a ferromagnetic material whether it is precipitated as a compound, for example, an oxide and / or hydroxide, or as a metal, and therefore the contact speed can be determined as in the step (I-ii) described above.

[0063] Step (Ii), for example, steps (Ii-1) to (Ii-6), and step (I-ii), for example, steps (I-ii-1) to (I-ii-6), are steps carried out to determine the deposition forms of the first transition metal and the second transition metal in step (I). As described above, reaction conditions in step (I), as well as steps (Ii) and (I-ii), include the solvent used in each solution, i.e., the first solution, the second solution, or the third solution, the salt of each transition metal, the concentration of each transition metal, the type of polyol in each polyol solution, the concentration of each component in each polyol solution, the volume ratio of each solution, and the mixing conditions for each solution. These reaction conditions are not limited as long as the contact rate characteristic of the present invention can be accurately set in step (I), as well as steps (Ii) and (I-ii), and the reaction conditions for steps (Ii) and (I-ii) can be determined in the same manner as the reaction conditions for step (I) described above. In one embodiment, in steps (Ii), (I-ii), and (I), the solvent (e.g., ethylene glycol) used in the first solution, the second solution, and the third solution, the type of polyol in each polyol solution (e.g., an ethylene glycol solution containing ethylene glycol and sodium hydroxide), the concentration of each component in each polyol solution, and the mixing conditions (e.g., adding the first solution, the second solution, or the third solution dropwise to the ethylene glycol solution) are the same.

[0064] Therefore, as in embodiment 1, when the second transition metal is or contains a transition metal different from the first transition metal selected from the group consisting of cobalt, nickel, and iron, in step (I), the first solution and the polyol solution are mixed at a contact speed in a speed range in which the contact speed determined in step (Ii), for example, steps (Ii-1) to (Ii-6), and the contact speed determined in step (I-ii), for example, steps (I-ii-1) to (I-ii-6), overlap.

[0065] When the second transition metal is a transition metal other than cobalt, nickel, and iron as in embodiment 2, the second transition metal becomes paramagnetic or diamagnetic in either case, whether it is precipitated as a compound, for example, an oxide and / or hydroxide, or as a metal in the polyol method, as described above. Therefore, in this embodiment, the first solution and the polyol solution are mixed under conditions under which the first transition metal is precipitated as a metal, i.e., at the contact speed determined in step (Ii), for example, steps (Ii-1) to (Ii-6).

[0066] The time for step (I), and steps (Ii) and (I-ii), i.e., the mixing time, is not limited. In one embodiment, the time for step (I), and steps (Ii) and (I-ii) is usually 0.1 to 10 hours, and in one embodiment, 1 to 3 hours, after the contact of all of the first solution, second solution, or third solution with the polyol solution (e.g., dropwise addition of the first solution, second solution, or third solution and / or dropwise addition of the polyol solution) is completed.

[0067] <Step (II)> In step (II), the first transition metal, which is a ferromagnetic substance, and the second transition metal, which is a paramagnetic substance or a diamagnetic substance, are separated from the first precipitate by utilizing the difference in magnetism.

[0068] In step (II), the first precipitate may or may not be separated from the liquid component after the reaction. If separation of the first precipitate from the liquid component after the reaction is performed, a solid-liquid separation method known in the art, such as filtration, decantation, or centrifugation, can be used.

[0069] The liquid component after the reaction contains the solvent, reaction intermediates such as complexes, by-products such as oxides of polyol ions, unreacted ions of the first transition metal and the second transition metal and their counterions, and a polyol solution such as a polyol, polyol ions, and a base. Therefore, if transition metals remain in the liquid component after separating the first precipitate from the liquid component after the reaction, the liquid component after the reaction can be combined with, for example, a base in an excess amount of base, to precipitate and recover the ions of the first transition metal and / or the second transition metal again as hydroxides.

[0070] The first precipitate contains a first transition metal that is a ferromagnetic first transition metal, and a second transition metal that is a paramagnetic or diamagnetic second transition metal.

[0071] The first transition metal contained in the first precipitate typically contains ferromagnetic metals in an amount of 90 wt % or more, in one embodiment 91 wt % or more, in one embodiment 92 wt % or more, in one embodiment 95 wt % or more, and in one embodiment 99 wt % or more, based on the total weight of the first transition metal in the first precipitate. Thus, although the first precipitate may also contain oxides and / or hydroxides of the first transition metal, the amount thereof is small.

[0072] When the second transition metal includes a transition metal different from the first transition metal selected from the group consisting of cobalt, nickel, and iron, as in the first embodiment, the substance of the second transition metal different from the first transition metal selected from the group consisting of cobalt, nickel, and iron is at least one selected from the group consisting of a compound of the transition metal, such as an oxide or hydroxide, and a metal. Here, the transition metal contained in the first precipitate typically comprises diamagnetic compounds of the transition metal in an amount of 90 wt% or more, in one embodiment 91 wt% or more, in one embodiment 92 wt% or more, in one embodiment 95 wt% or more, and in one embodiment 99 wt% or more, based on the total weight of the transition metal in the first precipitate. Therefore, although the first precipitate may also contain the transition metal, the amount is small. Of the second transition metals, the substance of a transition metal other than cobalt, nickel, and iron is one or more selected from the group consisting of paramagnetic or diamagnetic compounds of the transition metal, such as oxides and hydroxides, and metals.

[0073] When the second transition metal is a transition metal other than cobalt, nickel, and iron, as in embodiment 2, the substance of the second transition metal is one or more selected from the group consisting of paramagnetic or diamagnetic compounds of the second transition metal, such as oxides and hydroxides, and metals.

[0074] Therefore, in step (II), the first transition metal and the second transition metal can be separated from the first precipitate by utilizing the difference in their magnetic properties, and each can be recovered separately. A separation method utilizing the difference in magnetic properties can be carried out, for example, by applying a magnetic or magnetic field, for example, by using a magnet.

[0075] Figure 1 shows an image of the direction in which magnetism is generated in ferromagnetic, paramagnetic, and diamagnetic materials in response to a magnetic field. As can be seen from Figure 1, ferromagnetic materials have the property of becoming strongly magnetized in the same direction as the magnetic field when a magnetic field is applied. This property causes ferromagnetic materials to be attracted to magnets. Paramagnetic materials have the property of becoming weakly magnetized in the same direction as the magnetic field when a magnetic field is applied. However, the magnetism generated by this property is not strong enough to attract paramagnetic materials to magnets. On the other hand, diamagnetic materials have the property of becoming weakly magnetized in the opposite direction to the magnetic field when a magnetic field is applied. This property causes diamagnetic materials to repel magnets. However, the force of this repulsion is not strong.

[0076] <One embodiment of the present invention> One embodiment of the present invention is a method for separating cobalt and nickel, comprising the steps of: The method comprises: (I') a step of mixing a cobalt-nickel solution containing cobalt and nickel in the form of ions with an ethylene glycol solution containing ethylene glycol and a base at a certain temperature and in an atmosphere to produce a cobalt-nickel precipitate; Here, the cobalt nickel solution and the ethylene glycol solution are: (I-i') a step of mixing a nickel solution containing nickel in an ionic form with an ethylene glycol solution containing ethylene glycol and a base to produce a nickel precipitate containing metallic nickel, wherein the contact speed at which the nickel solution and the ethylene glycol solution are mixed is changed under the same temperature and atmosphere as in step (I') to determine the contact speed at which the nickel precipitate contains metallic nickel in an amount of 90% by weight or more based on the total weight of the nickel precipitate; (I-ii') a step of mixing a cobalt solution containing cobalt in an ionic form with an ethylene glycol solution containing ethylene glycol and a base to produce a cobalt precipitate containing cobalt oxide and / or cobalt hydroxide, wherein the contact speed at which the cobalt solution and the ethylene glycol solution are mixed is changed under the same temperature and atmosphere as in step (I') to determine the contact speed at which the cobalt precipitate becomes a precipitate containing 90 wt % or more of cobalt oxide and / or cobalt hydroxide based on the total weight of the cobalt precipitate; Based on A contact speed in a speed range where the contact speed determined in step (I-i') and the contact speed determined in step (I-ii') overlap. and (II') a step of separating metallic nickel and cobalt oxide and / or cobalt hydroxide from the cobalt-nickel precipitate using magnetic force due to differences in magnetic properties; The method includes:

[0077] In the above embodiment, the solvent for the cobalt solution, the nickel solution, and the cobalt-nickel solution may be ethylene glycol.

[0078] In the above embodiment, the temperature of steps (I'), (I-i'), and (I-ii') may be about 200°C, specifically 197°C, which is the boiling point of ethylene glycol.

[0079] In the above embodiment, the cobalt-nickel solution, nickel solution, or cobalt solution may be mixed with the ethylene glycol solution by adding the cobalt-nickel solution, nickel solution, or cobalt solution dropwise to the ethylene glycol solution at atmospheric pressure.

[0080] In the above embodiment, in steps (I-i') and (I-ii'), the contact rate is determined by dropwise adding the cobalt-nickel solution, nickel solution, or cobalt solution to the ethylene glycol solution under mixing conditions of ethylene glycol as the solvent for the cobalt solution, nickel solution, and cobalt-nickel solution, a constant temperature of 197°C, an inert atmosphere, and atmospheric pressure, and the contact rate in step (I') is in the range of 0.070 mmol / min or more, and in one embodiment 0.080 mmol / min or more, and in one embodiment 0.090 mmol / min or more, for the ions of the first transition metal or the second transition metal. It is 100 mmol / min or more, and in one embodiment 0.110 mmol / min or more, in one embodiment 0.120 mmol / min or more, and in one embodiment 0.125 mmol / min or more, and is 1.000 mmol / min or less, and in one embodiment 0.900 mmol / min or less, and in one embodiment 0.800 mmol / min or less, and in one embodiment 0.700 mmol / min or less, and in one embodiment 0.650 mmol / min or less, and in one embodiment 0.630 mmol / min or less, and in one embodiment 0.620 mmol / min or less, and in one embodiment 0.610 mmol / min or less, and in one embodiment 0.600 mmol / min or less.

[0081] According to the above embodiment, nickel can be separated and recovered at a recovery rate of typically 40% or more, in one embodiment, 50% or more, in one embodiment, 60% or more, in one embodiment, 70% or more, in one embodiment, 80% or more, and in one embodiment, 90% or more. Furthermore, nickel can be separated and recovered at a purity of typically 85% or more, in one embodiment, 90% or more, in one embodiment, 95% or more, and in one embodiment, 99% or more. Furthermore, cobalt can be separated and recovered at a recovery rate of typically 40% or more, in one embodiment, 50% or more, in one embodiment, 60% or more, in one embodiment, 70% or more, in one embodiment, 80% or more, and in one embodiment, 85% or more. Furthermore, cobalt can be separated and recovered at a purity of typically 85% or more, in one embodiment, 90% or more, in one embodiment, 95% or more, and in one embodiment, 99% or more.

[0082] An example of the embodiment is shown in Figure 2. In Figure 2, in Step 1, which is known in the technical field, cobalt, nickel, and manganese are separated by the Volhard reaction, and manganese is removed. Then, in Step 2 of the method of the present invention, the cobalt-nickel solution is added dropwise to an ethylene glycol (EG) solution containing ethylene glycol and sodium hydroxide while controlling the contact rate, and the resulting precipitate containing metallic nickel and cobalt hydroxide is separated and collected by magnetic force.

[0083] Another embodiment of the present invention Another embodiment of the present invention is a method for separating cobalt from a transition metal other than cobalt, nickel, and iron (hereinafter also referred to as "transition metal A"), the method comprising the steps of: The method comprises: (I'') mixing a cobalt-transition metal A solution containing cobalt and transition metal A in ionic form with an ethylene glycol solution containing ethylene glycol and a base at a certain temperature and in an atmosphere to produce a cobalt-transition metal A precipitate; Here, the cobalt transition metal A solution and the ethylene glycol solution are: (I-i'') A step of mixing a cobalt solution containing cobalt with an ethylene glycol solution containing ethylene glycol and a base to produce a cobalt precipitate containing metallic cobalt, wherein the contact speed at which the cobalt solution and the ethylene glycol solution are mixed is changed under the same temperature and atmosphere as in step (I'') to determine the contact speed at which the cobalt precipitate contains metallic cobalt in an amount of 90 wt % or more based on the total weight of the cobalt precipitate. Based on Contact velocity determined in step (I-i'') and (II'') magnetically separating the cobalt and the transition metal A from the cobalt-transition metal A precipitate due to their different magnetic properties; The method includes:

[0084] In another embodiment, the solvent for the cobalt solution and the cobalt transition metal A solution may be ethylene glycol.

[0085] In the another embodiment, the temperature in steps (I'') and (I-i'') may be about 200°C, specifically 197°C, which is the boiling point of ethylene glycol.

[0086] In another embodiment, the mixing of the cobalt transition metal A solution or the cobalt solution with the ethylene glycol solution may be carried out by adding the cobalt transition metal A solution or the cobalt solution dropwise to the ethylene glycol solution at atmospheric pressure.

[0087] In another embodiment, in step (I-i"), the contact rate is determined by dropwise adding the cobalt transition metal A solution or the cobalt solution to the ethylene glycol solution under the following mixing conditions: ethylene glycol is used as the solvent for the cobalt solution and the cobalt transition metal A solution; the temperature is set to 197°C; the atmosphere is an inert atmosphere; and atmospheric pressure is used. Thus, the contact rate range in step (I") is 0.062 mmol / min or less.

[0088] <Another embodiment of the present invention> Yet another embodiment of the present invention is a method for separating nickel from a transition metal other than cobalt, nickel, and iron (hereinafter also referred to as "transition metal A"), the method comprising the steps of: The method comprises: (I''') a step of mixing a nickel transition metal A solution containing nickel and transition metal A in ionic form with an ethylene glycol solution containing ethylene glycol and a base at a certain temperature and in a certain atmosphere to produce a nickel transition metal A precipitate, The solvent for the nickel transition metal A solution is ethylene glycol, The constant temperature is the boiling point of ethylene glycol The process and (II''') magnetically separating metallic nickel and transition metal A from the nickel-transition metal A precipitate due to their different magnetic properties; The method includes:

[0089] The separation method of the present invention is a method for separating two or more transition metals (wherein one is selected from the group consisting of cobalt, nickel, and iron) from a solution containing the metals, by precipitating each transition metal as a ferromagnetic metal and a paramagnetic or diamagnetic substance, respectively, and separating them based on their magnetic properties. The separation method of the present invention can be used, in particular, to recover rare ferromagnetic transition metals, particularly cobalt and / or nickel, from waste materials such as waste generated in the electronics industry during the manufacturing process of electronic materials and used batteries, e.g., lithium-ion secondary batteries. [Example]

[0090] The present invention will be specifically explained below with reference to examples, but the present invention is not limited to the descriptions in the examples.

[0091] Experiment 1: Dropping rate study of nickel or cobalt solution containing NiSO4 or CoSO4 and ethylene glycol into ethylene glycol solution We investigated the production of different magnetic compounds using the polyol method by varying the drop speed of a metal solution containing metal sulfate hydrates (NiSO4·6H2O (also simply referred to as "NiSO4"), CoSO4·7H2O (also simply referred to as "CoSO4")) and ethylene glycol into an ethylene glycol solution containing ethylene glycol and sodium hydroxide (NaOH).

[0092] Experiment 1-1. Investigation of the dripping rate of nickel solution containing NiSO4 and ethylene glycol Using the apparatus shown in Figure 3, an ethylene glycol solution containing ethylene glycol and NaOH ([NaOH] = 0.4 mol / L, 20 mL) was added to a nickel solution containing NiSO4 and ethylene glycol ([Ni 2+] = 0.4 mol / L, 10 mL) was added dropwise at various rates, followed by stirring at 197 °C for 2 hours. The nickel ion addition rate (mmol / min) was gradually changed (0.630 mmol / min, 0.315 mmol / min, 0.125 mmol / min, 0.062 mmol / min, or 0.050 mmol / min). It was found that ferromagnetic metallic Ni was produced at all of the addition rates. The results are shown in Figure 4. The product, i.e., metallic Ni, was identified by X-ray powder diffraction. The results are shown in Figure 5.

[0093] Experiment 1-2. Dropping rate study of cobalt solution containing CoSO4 and ethylene glycol Using the apparatus shown in Figure 3, an ethylene glycol solution containing ethylene glycol and NaOH ([NaOH] = 0.4 mol / L, 20 mL) was added to a cobalt solution containing CoSO4 and ethylene glycol ([Co 2+ [] = 0.4 mol / L, 10 mL) was added dropwise at various rates and then stirred at 197 °C for 3 hours. The cobalt ion addition rate (mmol / min) was gradually increased (0.630 mmol / min, 0.315 mmol / min, 0.125 mmol / min, 0.062 mmol / min, or 0.050 mmol / min). At rates of 0.630 mmol / min, 0.315 mmol / min, and 0.125 mmol / min, a mixture of ferromagnetic metallic Co and diamagnetic Co(OH) was formed. However, the majority of this mixture, i.e., over 90 wt% of the total weight of the mixture, was Co(OH) and therefore did not exhibit ferromagnetism. On the other hand, at rates of 0.062 mmol / min and 0.050 mmol / min, only metallic Co was formed, demonstrating ferromagnetism. The results are shown in Figure 6. The products, i.e., metallic Co and Co(OH)2, were identified by X-ray powder diffraction. The results are shown in Figure 7.

[0094] Experiment 2: Separation of Ni and Co by dropping a cobalt-nickel solution containing NiSO4, CoSO4, and ethylene glycol into an ethylene glycol solution Figure 8 summarizes the products formed by changing the dropping rate based on the results of Experiments 1-1 and 1-2. Table 3 shows that in the reaction involving the dropping of nickel solution, metallic Ni, a ferromagnetic substance, was produced at all dropping rates, whereas in the reaction involving the dropping of cobalt solution, a mixture of metallic Co and Co(OH)2 was produced at dropping rates of 0.630 mmol / min, 0.315 mmol / min, and 0.125 mmol / min, and this mixture did not exhibit ferromagnetic properties. By utilizing these dropping rate conditions, it is possible to separate nickel and cobalt using magnetic force. That is, if a cobalt-nickel solution containing nickel and cobalt is dropped into an ethylene glycol solution containing NaOH and ethylene glycol at a dropping rate of 0.630 mmol / min, 0.315 mmol / min, or 0.125 mmol / min, metallic Ni and a mixture of metallic Co and Co(OH)2 are produced, and the ferromagnetic metallic Ni can be attached to a magnet using magnetic force, for example, and separated, while the remaining material that does not attach to the magnet becomes a mixture of metallic Co and Co(OH)2 that does not exhibit ferromagnetic properties, indicating a high possibility of selectively separating Ni and Co.

[0095] Experiment 2-1. Separation and evaluation of nickel and cobalt by creating ferromagnetic metals and diamagnetic compounds 1 Based on the above results, in this experiment, we first investigated the effects of the drop rate and metal sulfate hydrate concentration on the separation of Co and Ni. A cobalt-nickel solution containing NiSO4, CoSO4, and ethylene glycol ([NiSO4] = [CoSO4] = 0.2 mol / L, 10 mL) was added dropwise to an ethylene glycol solution containing NaOH and ethylene glycol ([NaOH] = 0.2 mol / L, 20 mL) at various drop rates ([NiSO4] = [CoSO4] = 0.630 mmol / min, 0.315 mmol / min, or 0.125 mmol / min) and then stirred at 197 °C for 3 h. Ferromagnetic Ni metal and a mixture of non-ferromagnetic Co precipitated. The ferromagnetic Ni metal was recovered using a neodymium magnet, washed with distilled water, and then vacuum-dried at room temperature for one day. The resulting ferromagnetic Ni metal was dissolved in a 1.0 mol / L nitric acid solution, and the purity and recovery rate of Ni were determined using atomic absorption spectrophotometry. The nonferromagnetic Co mixture was washed with distilled water and then recovered by filtration (1). Furthermore, excess NaOH (0.32 g, 0.08 mol) was added to the filtrate to precipitate the remaining cobalt ions as hydroxides. This was then filtered, washed with water, and dried at room temperature for one day (2). (1) and (2) were combined and dissolved in a 1.0 mol / L nitric acid solution, and the purity and recovery rate of Co were determined using atomic absorption spectrophotometry. Figure 9 shows an outline of the separation and recovery method for Co and Ni from the cobalt-nickel solution and the results. As shown in Figure 9(a), for ferromagnetic metallic Ni, high Ni purity was obtained when the drop rates were [NiSO4] = 0.630 mmol / min, 0.315 mmol / min, or 0.125 mmol / min. In particular, the highest Ni purity (95%) and Ni recovery rate (88%) were obtained at [NiSO4] = 0.125 mmol / min. On the other hand, as shown in Figure 9(b), in the case of a non-ferromagnetic Co mixture, high Co purity was obtained when the drop rate was [CoSO4] = 0.630 mmol / min, 0.315 mmol / min, or 0.125 mmol / min. In particular, the highest Co purity (90%) and Co recovery rate (94%) were obtained at [CoSO4] = 0.125 mmol / min. Therefore, it was found that Ni and Co can be selectively separated by performing separation under these drop rate conditions.

[0096] Experiment 2-2. Separation and evaluation of nickel and cobalt by creating ferromagnetic metals and diamagnetic compounds 2 A cobalt-nickel solution containing NiSO4, CoSO4, and ethylene glycol ([NiSO4] = [CoSO4] = 0.15 mol / L, 10 mL) was added dropwise to an ethylene glycol solution containing NaOH and ethylene glycol ([NaOH] = 0.15 mol / L, 20 mL) at various drop rates ([NiSO4] = [CoSO4] = 0.630 mmol / min, 0.315 mmol / min, or 0.125 mmol / min), followed by stirring at 197 °C for 3 h. Ferromagnetic Ni metal and a mixture of non-ferromagnetic Co precipitated. The ferromagnetic Ni metal was recovered using a neodymium magnet, washed with distilled water, and then vacuum-dried at room temperature for one day. The resulting ferromagnetic Ni metal was dissolved in a 1.0 mol / L aqueous nitric acid solution, and the purity and recovery rate of Ni were determined using atomic absorption spectrophotometry. The non-ferromagnetic Co mixture was washed with distilled water and recovered by filtration (1). Furthermore, excess NaOH (0.32 g, 0.08 mol) was added to the filtrate to precipitate the remaining cobalt ions as hydroxides. The precipitate was then filtered, washed with water, and dried at room temperature for one day (2). (1) and (2) were combined and dissolved in a 1.0 mol / L aqueous nitric acid solution, and the purity and recovery rate of Co were determined using atomic absorption spectrophotometry. Figure 9 shows an outline of the separation and recovery method for Co and Ni from the cobalt-nickel solution and the results. As shown in Figure 9(a), for ferromagnetic Ni metal, high Ni purity was obtained when the drop rates were [NiSO4] = 0.630 mmol / min, 0.315 mmol / min, or 0.125 mmol / min. In particular, the highest Ni purity (96%) and Ni recovery rate (91%) were obtained at [NiSO4] = 0.315 mmol / min. On the other hand, as shown in Figure 9(b), in the case of a non-ferromagnetic Co mixture, high Co purity was obtained when the drop rate was [CoSO4] = 0.630 mmol / min, 0.315 mmol / min, or 0.125 mmol / min. In particular, the highest Co purity (91%) and Co recovery rate (89%) were obtained at [CoSO4] = 0.315 mmol / min. Therefore, it was found that Ni and Co can be selectively separated by performing separation under these drop rate conditions.

[0097] In the polyol method, when CoSO4 or NiSO4 is used as a raw material, Co is produced according to the following reaction formula: 2+ and Ni 2+ The reduction reaction proceeds.

[0098] [ka]

[0099] First, metal sulfate [M(II)SO4] reacts with NaOH to produce metal hydroxide [M(II)(OH)2]. Then, hydroxide ions (OH) of [M(II)(OH)2] or NaOH are released. - ) is the proton (H + ) is extracted, and the monoethylene glycolate ion (HOCH2CH2O - Na + ) and metal ion(II) complexes (HOCH2CH2O - M(II)X) is then generated. The H of the monoethylene glycolate ligand is then released. +The hydroxide ions are abstracted to form metal glycolate [M(II)(OCH2CHO)]. This metal glycolate dissolves in the solvent and is subsequently reduced to metal M, i.e., metallic Co or metallic Ni. The greater the concentration ratio of HOCH2CH2OH to M(II)(OH)2, the more readily M(II)(OCH2CHO) is formed and the reduction reaction proceeds. In the present invention, we discovered that by varying the dropwise addition rate of the M(II)SO4 solution, we can control the concentration ratio of HOCH2CH2OH to M(II)SO4 in the reaction system, thereby producing either ferromagnetic metallic Ni or a mixture of non-ferromagnetic Co(OH)2 and metallic Co. Therefore, for example, to proceed with the reduction reaction, the concentration ratio of HOCH2CH2OH to M(II)SO4 in the reaction system must be increased, which requires a large amount of HOCH2CH2OH, necessitating the use of a large reactor. However, according to the present invention, the desired concentration ratio can be achieved by slowing down the dripping speed of the M(II)SO4 solution, which makes it possible to use a space-saving reaction device as the reaction site, making it an effective method.

Claims

1. 1. A method for separating a first transition metal from a second transition metal, comprising: the first transition metal is a metal selected from the group consisting of cobalt, nickel, and iron; the second transition metal is a transition metal different from the first transition metal; The method comprises: (I) mixing a first solution containing a first transition metal and a second transition metal, each in an ionic form, with a polyol solution containing a polyol and a base to produce a first precipitate, The first solution and the polyol solution are mixed at a contact speed under a certain temperature and atmosphere such that the first precipitate becomes a precipitate containing a first transition metal that is ferromagnetic and a second transition metal that is paramagnetic or diamagnetic; The process and (II) separating the first transition metal, which is a ferromagnetic substance, and the second transition metal, which is a paramagnetic substance or a diamagnetic substance, from the first precipitate by utilizing the difference in magnetic properties; A method comprising:

2. 2. The method of claim 1, wherein the second transition metal is a transition metal different from the first transition metal selected from the group consisting of cobalt, nickel, and iron.

3. The step (I) (I-i) mixing a second solution containing a first transition metal in an ionic form with a polyol solution containing a polyol and a base to produce a second precipitate, changing the contact speed at which the second solution and the polyol solution are mixed under the same temperature and atmosphere as in step (I), and determining the contact speed at which the second precipitate becomes a precipitate containing the first transition metal, which is a ferromagnetic material, in an amount of 90 wt % or more based on the total weight of the second precipitate; Process, and (I-ii) mixing a third solution containing a second transition metal in an ionic form with a polyol solution containing a polyol and a base to produce a third precipitate, changing the contact speed at which the third solution is mixed with the polyol solution under the same temperature and atmosphere as in step (I), and determining the contact speed at which the third precipitate becomes a precipitate containing 90 wt % or more of the oxide and / or hydroxide of the second transition metal that is a diamagnetic material, based on the total weight of the third precipitate; process Including, In step (I), the first solution and the polyol solution are mixed at a contact speed in a speed range in which the contact speed determined in step (I-i) and the contact speed determined in step (I-ii) overlap. The method of claim 2.

4. 10. The method of claim 1, wherein the second transition metal is a transition metal other than cobalt, nickel, and iron.

5. The step (I) (I-i) mixing a second solution containing a first transition metal in an ionic form with a polyol solution containing a polyol and a base to produce a second precipitate, changing the contact speed at which the second solution and the polyol solution are mixed under the same temperature and atmosphere as in step (I), and determining the contact speed at which the second precipitate becomes a precipitate containing the first transition metal, which is a ferromagnetic material, in an amount of 90 wt % or more based on the total weight of the second precipitate; process Including, In step (I), the first solution and the polyol solution are mixed at the contact speed determined in step (I-i). The method of claim 4.

6. The method of any one of claims 1 to 5, wherein the first transition metal is nickel.

7. 7. The method of claim 6, wherein the second transition metal is cobalt.

8. The method according to claim 7, wherein in step (I), the polyol solution is an ethylene glycol solution, and the solvent of the first solution is ethylene glycol.

9. 9. The method according to claim 8, wherein in step (I), the first solution and the polyol solution are mixed at atmospheric pressure at the boiling point of the polyol solution.

10. The method according to claim 9, wherein in step (I), the contact rate between the first solution and the polyol solution is 0.070 mmol / min to 1.000 mmol / min.

11. 11. The method according to claim 10, wherein in step (I), the first solution contains the first transition metal at a concentration of 0.1 mol / L to 1.0 mol / L and the second transition metal at a concentration of 0.1 mol / L to 1.0 mol / L.

12. 6. The method of claim 4 or 5, wherein the first transition metal is cobalt.

13. 13. The method according to claim 12, wherein in step (I), the polyol solution is an ethylene glycol solution, and the solvent of the first solution is ethylene glycol.

14. 14. The method according to claim 13, wherein in step (I), the first solution and the ethylene glycol solution are mixed at atmospheric pressure at the boiling point of the ethylene glycol solution.

15. 15. The method according to claim 14, wherein in step (I), the contact rate between the first solution and the ethylene glycol solution is 0.062 mmol / min or less.

16. 16. The method according to claim 15, wherein in step (I), the first solution has a cobalt content of 0.1 mol / L to 1.0 mol / L and a second transition metal content of 0.1 mol / L to 1.0 mol / L.

17. 1. A method for separating nickel and a secondary transition metal, comprising: the second transition metal is a transition metal other than cobalt, nickel, and iron; The method comprises: (I''') A step of mixing a solution containing nickel and a second transition metal in ionic form with an ethylene glycol solution containing ethylene glycol and a base at a certain temperature and in an atmosphere to produce a precipitate containing nickel and the second transition metal, the solvent of the solution is ethylene glycol; The constant temperature is the boiling point of ethylene glycol The process and (II''') separating metallic nickel and the second transition metal substance from the precipitate using magnetic force due to differences in magnetic properties; A method comprising:

18. The method according to claim 1 for recovering nickel and / or cobalt from waste lithium-ion secondary batteries.

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