Process for the recovery of valuable metals

Abstract

Provided is a valuable metal recovery method. In the recovery method, cobalt, nickel, manganese, and lithium are recovered from a spent lithium ion battery at a very high recovery rate using a wet process. The valuable metal recovery method includes a first solvent extraction step in which an organic solvent is added to a solution containing at least one valuable metal selected from the group consisting of transition metals other than manganese, cobalt, and nickel, magnesium, strontium, and aluminum, and lithium, and the valuable metal is extracted, the organic solvent containing at least one selected from the group consisting of a compound represented by formula 1, a phosphonate, a phosphoric acid ester, a phosphinic acid, methyl isobutyl ketone, and trioctylamine, in formula 1, R1, R2 each independently represents a hydrocarbon group having 6 to 20 carbon atoms.

Description

Technical Field

[0001] This invention relates to a method for recycling valuable metals. Background Technology

[0002] In recent years, with the popularization of lithium-ion batteries, research has begun on a method to recover valuable metals such as cobalt, nickel, manganese, and lithium from waste lithium-ion batteries and use them as materials for the lithium-ion batteries.

[0003] In the past, when recovering the valuable metals from the aforementioned waste lithium-ion batteries, the waste lithium-ion batteries were usually subjected to heat treatment (roasting), or, without heat treatment, cobalt, nickel, manganese and lithium were separated and refined from the powder containing the aforementioned valuable metals obtained by crushing, grading, etc. through a wet process (for example, see Patent Document 1).

[0004] It should be noted that, in this invention, "waste lithium-ion batteries" refers to lithium-ion batteries whose lifespan has been exhausted as battery products, lithium-ion batteries discarded as defective products during the manufacturing process, and residual positive and negative electrode materials used in productization during the manufacturing process. Furthermore, the powder containing positive and negative electrodes obtained from the aforementioned waste lithium-ion batteries is used as active material powder. And, impurities refer to metals in the active material powder that do not need to be recycled.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Patent No. 7060899 Summary of the Invention

[0008] The problem that the invention aims to solve

[0009] In the manufacture of lithium-ion batteries, to improve battery performance, attempts have been made to add appropriate amounts of transition metals other than manganese, cobalt, and nickel, as well as magnesium and strontium, to the cathode material, with precise proportions selected according to the desired effect. However, when these transition metals, magnesium, and strontium are mixed into lithium-ion batteries, they can adversely affect the separation and refining of manganese, cobalt, and nickel. Particularly in wet processes using solvent extraction, these elements accumulate in the organic solvent, hindering the extraction of valuable metals such as manganese, cobalt, and nickel that should be recovered. As a result, there is a risk of reduced recovery rates of these valuable metals.

[0010] Despite the aforementioned problems, there is still an urgent need to further improve the recycling rate of cobalt, nickel, manganese and lithium in all waste lithium-ion batteries, including those containing the aforementioned element groups, through wet processes for separation and purification.

[0011] Therefore, the problem to be solved by the present invention is to provide a method for recovering cobalt, nickel, manganese and lithium from waste lithium-ion batteries with extremely high recovery rates through a wet process.

[0012] Methods for solving problems

[0013] The inventors, through repeated research into the aforementioned problems, discovered that by adding a specific organic solvent to a solution containing at least one valuable metal selected from the group consisting of transition metals, magnesium, strontium, and aluminum, and lithium, wherein the transition metal is a transition metal other than manganese, cobalt, and nickel, the present invention was made based on the above discovery.

[0014] The present invention relates to a method for recovering valuable metals, comprising a first solvent extraction step in which an organic solvent is added to a solution containing at least one valuable metal selected from the group consisting of transition metals other than manganese, cobalt and nickel, alkaline earth metals and aluminum, and lithium, to extract the valuable metal, the organic solvent containing at least one selected from the group consisting of a compound represented by Formula 1, a phosphonate, a phosphate ester, a hypophosphonic acid, methyl isobutyl ketone and trioctylamine, wherein R1 and R2 each independently represent a hydrocarbon group having 6 to 20 carbon atoms.

[0015] (Equation 1)

[0016]

[0017] The preferred method for recovering valuable metals further includes: a dissolution step, in which active material powder obtained by pretreatment of waste lithium-ion batteries is dissolved in an inorganic acid to obtain a solution; a neutralization step, in which the solution is neutralized with an alkali; a second solvent extraction step, in which at least one selected from the group consisting of manganese, cobalt, and nickel is separated from the residue of the first solvent extraction step using an organic solvent extraction, and the residue of the solvent extraction is used as a first lithium salt aqueous solution; and a membrane electrolysis step, in which the first lithium salt aqueous solution is electrolyzed using an ion exchange membrane to obtain a lithium hydroxide aqueous solution, an acid, and a second lithium salt aqueous solution that is more dilute than the first lithium salt aqueous solution.

[0018] The lithium hydroxide aqueous solution obtained in the membrane electrolysis step is reused in at least one step selected from the group consisting of the neutralization step, the first solvent extraction step and the second solvent extraction step, and the acid obtained in the membrane electrolysis step is reused as the inorganic acid used in the dissolution step.

[0019] The inorganic acid preferably comprises at least one acid selected from the group consisting of hydrochloric acid, sulfuric acid and nitric acid, and more preferably comprises hydrochloric acid.

[0020] The alkali used in the neutralization step preferably includes lithium hydroxide.

[0021] The concentration of at least one component in the organic solvent selected from the group consisting of the compound represented by Formula 1 above, phosphonates, phosphates, hypophosphonic acid, methyl isobutyl ketone and trioctylamine is preferably in the range of 0.001 M to 1.5 M.

[0022] The electricity used in the membrane electrolysis step preferably includes electricity obtained from renewable energy sources, and more preferably includes electricity obtained from at least one selected from the group consisting of solar power, wind power, geothermal power, hydropower and biomass power.

[0023] The effects of the invention

[0024] The present invention provides a method for recovering valuable metals, namely cobalt, nickel, manganese and lithium from spent lithium-ion batteries using a wet process with extremely high recovery rates. Attached Figure Description

[0025] Figure 1 This is an explanatory diagram illustrating the structure of one embodiment of the method for recycling valuable metals according to the present invention.

[0026] Figure 2 This is an illustrative cross-sectional view showing the structure of the ion exchange membrane electrolyzer used in the method for recovering valuable metals according to the present invention. Detailed Implementation

[0027] The present invention will now be described in more detail.

[0028] It should be noted that, unless otherwise specified, the "~" in numerical range indicates above to below, and includes both ends of the value. Furthermore, when showing numerical ranges, upper and lower limits can be appropriately combined, and the resulting numerical ranges are also considered publicly available.

[0029] Furthermore, in the accompanying drawings, the same reference numerals are used for the same elements, and redundant descriptions are omitted. In addition, for ease of explanation, the dimensions of the drawings are exaggerated and sometimes differ from the actual scale.

[0030] The method for recovering valuable metals according to the present invention includes a first solvent extraction step, in which an organic solvent is added to a solution containing at least one valuable metal selected from the group consisting of (1) transition metals other than manganese, cobalt and nickel, (2) alkaline earth metals and (3) aluminum and lithium, and the valuable metal, namely at least one valuable metal selected from the group consisting of the valuable metals (1) to (3), is extracted. The alkaline earth metal (2) recovered by the method for recovering valuable metals according to the present invention preferably includes at least one selected from the group consisting of beryllium, magnesium, calcium, strontium and barium, more preferably at least one selected from the group consisting of magnesium, calcium and strontium, and even more preferably magnesium, calcium or strontium.

[0031] The aforementioned organic solvent comprises at least one selected from the group consisting of compounds represented by Formula 1 below, phosphonates, phosphates, hypophosphonic acids, methyl isobutyl ketones, and trioctylamine. Preferably, the aforementioned organic solvent is selected from at least one of these compounds.

[0032] (Equation 2)

[0033]

[0034] In Formula 1 above, R1 and R2 independently represent hydrocarbon groups with 6 to 20 carbon atoms. The hydrocarbon group is not particularly limited, but is preferably alkyl, cycloalkyl, alkenyl, alkynyl, aryl, heteroaryl (aromatic heterocyclic group) or aliphatic heterocyclic group.

[0035] The alkyl group is preferably an alkyl group with 6 to 15 carbon atoms, more preferably an alkyl group with 10 to 15 carbon atoms. R1 and R2 are further preferably dodecyl groups.

[0036] The alkenyl group mentioned above is preferably an alkenyl group with 6 to 15 carbon atoms, and more preferably an alkenyl group with 10 to 15 carbon atoms.

[0037] The alkynyl group mentioned above is preferably an alkynyl group with 6 to 15 carbon atoms, and more preferably an alkynyl group with 10 to 15 carbon atoms.

[0038] The aryl group is preferably an aryl group with 6 to 18 carbon atoms, and more preferably an aryl group with 6 to 10 carbon atoms. Examples of aryl groups include phenyl groups.

[0039] When the aforementioned aromatic heterocycle is a fused ring, in addition to groups consisting only of a monocyclic aromatic heterocycle, it also includes groups consisting of fused heterocycles formed by fused other rings, such as aromatic hydrocarbon rings, aliphatic hydrocarbon rings, or heterocycles, onto a monocyclic aromatic heterocycle. The number of heteroatoms constituting the aromatic heterocycle need to be one or more; nitrogen, oxygen, and sulfur atoms are preferred as heteroatoms. Furthermore, the number of ring members in the aromatic heterocycle is preferably 3 to 8 members, more preferably 5 or 6 members. Examples of 5-membered aromatic heterocycles and fused heterocycles containing 5-membered aromatic heterocycles include: pyrrole rings, imidazole rings, pyrazole rings, oxazole rings, thiazole rings, triazole rings, furan rings, thiophene rings, benzimidazole rings, benzoxazole rings, benzothiazole rings, indoline rings, and indazole rings. In addition, aromatic heterocycles that are 6-membered rings and fused heterocycles that contain aromatic heterocycles that are 6-membered rings include, for example, pyridine rings, pyrazine rings, triazine rings, quinoline rings, quinazoline rings, and other cyclic groups.

[0040] The aforementioned aliphatic heterocyclic groups include monocyclic groups consisting solely of aliphatic heterocycles, and groups consisting of aliphatic fused heterocycles formed by the fusion of aliphatic heterocycles with other rings (e.g., aliphatic rings). The number of heteroatoms constituting the aliphatic heterocycle is only one or more, and nitrogen, oxygen, and sulfur atoms are preferred as heteroatoms. Furthermore, the number of ring members in the aliphatic heterocycle is preferably 3 to 8 members, more preferably 5 or 6 members. Specific examples of preferred aliphatic heterocycles include: pyrrolidine rings, oxetane rings, thiophene rings, piperidine rings, tetrahydrofuran rings, ethylene oxide rings (tetrahydropyran rings), thiane rings, piperazine rings, morpholine rings, quinine rings, pyrrolidine rings, azahexacyclic butane rings, oxetane rings, azahexacyclic propane rings, dialkyl rings, pentamethyl sulfide rings, γ-butyrolactone, etc.

[0041] Other examples of hydrocarbon groups mentioned above include the following groups.

[0042] Alkoxy, aryloxy, heterocyclic oxy (groups with an -O- group bonded to the above heterocyclic groups), alkoxycarbonyl, aryloxycarbonyl, amino (with 6 to 20 carbon atoms), aminosulfonyl, acyl (including alkylcarbonyl, alkenylcarbonyl, alkynylcarbonyl, arylcarbonyl, and heterocyclic carbonyl groups with 6 to 20 carbon atoms, such as octanoyl, hexadecanoyl, benzoyl, naphthoyl, nicotinyl, etc.),

[0043] Acyloxy groups (including alkyl carbonyloxy, alkenyl carbonyloxy, alkynyl carbonyloxy, aryl carbonyloxy, heterocyclic carbonyloxy, and acyloxy groups with 6 to 20 carbon atoms, such as octanoyloxy, hexadecanoyloxy, benzoyloxy, naphthoyloxy, nicotinyloxy, etc.), aromatic acyloxy groups, carbamoyl groups,

[0044] Acylamino groups (acylamino groups with 6 to 20 carbon atoms, such as benzoylamino, etc.)

[0045] Alkylthio groups (alkoxythio groups with 6 to 20 carbon atoms, such as benzylthio groups, etc.)

[0046] Arylthiols (arylthiols with 6 to 20 carbon atoms, such as phenylthiols, 1-naphthiols, 3-methylphenylthiols, 4-methoxyphenylthiols, etc.)

[0047] Heterocyclic thio groups (groups with -S- groups bonded to the above heterocyclic groups),

[0048] Alkyl sulfonyl (alkyl sulfonyl with 6 to 20 carbon atoms)

[0049] Arylsulfonyl groups (arylsulfonyl groups with 6 to 20 carbon atoms, such as benzenesulfonyl groups, etc.)

[0050] Alkylsilane (alkylsilanes with 6 to 20 carbon atoms, such as triethylsilane, etc.)

[0051] Arylsilanes (arylsilanes with 6 to 20 carbon atoms, such as triphenylsilanes, etc.)

[0052] Phosphoryl group (a phosphate group with 6 to 20 carbon atoms, such as -OP (=O) (R) P )2)

[0053] Phosphonoyl group (phosphonoyl group with 6 to 20 carbon atoms, such as -P (=O) (R) P )2)

[0054] phosphinyl groups (phosphinyl groups with 6 to 20 carbon atoms, for example, -P(R)) P 2).

[0055] Among them, R P It is a hydrogen atom or a substituent (preferably a group selected from the substituents mentioned above).

[0056] Furthermore, each of the substituents listed above can be further replaced by the aforementioned substituents.

[0057] As a compound represented by Formula 1 above, N,N-bisdodecyl-2-hydroxyacetamide can be listed.

[0058] Commercially available products of the aforementioned phosphonates include, for example, PC-88A manufactured by Daiichi Chemical Industry Co., Ltd.

[0059] Examples of the aforementioned phosphate esters include tributyl phosphate (TBP) and di(2-ethylhexyl) phosphate (D2EHPA).

[0060] Commercially available products of the aforementioned phosphonic acids include, for example, CYANEX272 manufactured by Solvay.

[0061] The concentration of at least one component selected from the group consisting of compounds represented by Formula 1, phosphonates, phosphates, hypophosphonic acids, methyl isobutyl ketone, and trioctylamine in the aforementioned organic solvent is preferably in the range of 0.001 M to 1.5 M, more preferably in the range of 0.005 M to 1 M. When the concentration is within the aforementioned range, the valuable metal obtained by extraction from the aforementioned organic solvent in the aforementioned first solvent extraction step can be back-extracted from the aforementioned organic solvent more stably, thereby allowing the aforementioned organic solvent to be reused repeatedly.

[0062] The method for recycling valuable metals according to the present invention will be described in more detail with reference to the accompanying drawings.

[0063] like Figure 1 As shown, the method for recovering valuable metals of the present invention can use active material powder 1 as a starting material.

[0064] Next, in STEP 1 (step 1), the above-mentioned active material powder 1 is dissolved in an inorganic acid to obtain an acid solution containing at least lithium of the above-mentioned active material powder 1. The inorganic acid is preferably at least one acid selected from the group consisting of hydrochloric acid, sulfuric acid, and nitric acid, more preferably an inorganic acid containing hydrochloric acid, and even more preferably hydrochloric acid. In addition to lithium, the active material powder 1 also contains valuable metals such as iron, transition metals, magnesium, strontium, and aluminum.

[0065] In the method for recovering valuable metals according to the present invention, the aforementioned acid solution is subsequently neutralized in STEP 2 (step 2) by adding an alkali. The alkali may be added in at least one form selected from the group consisting of aqueous solutions and solids. The alkali preferably comprises at least one selected from the group consisting of alkali metal hydroxides and ammonia. Furthermore, the alkali metal constituting the aforementioned alkali metal hydroxide preferably comprises at least one selected from the group consisting of lithium, sodium, potassium, rubidium, cesium, and francium, more preferably lithium, sodium, and potassium, further preferably lithium, sodium, or potassium, and particularly preferably lithium.

[0066] Next, in step 3A, the first solvent extraction step is performed on the neutralized acid solution. The raffinate from the first solvent extraction step contains valuable metals such as lithium, manganese, cobalt, and nickel. In addition, the extract 2A from the first solvent extraction step contains at least one valuable metal selected from the group consisting of the valuable metals (1) to (3). Zirconium is a typical example of the valuable metal (1) contained in the extract of the first solvent extraction step. The valuable metals (1) to (3) are the cause of the obstacles to the recovery of lithium, manganese, cobalt, and nickel contained in the acid solution.

[0067] The raffinate from the first solvent extraction step is then used for a second organic solvent extraction in step 3B. In the second organic solvent extraction, manganese, cobalt, and nickel (excluding lithium) are extracted with an organic solvent, or iron is separated and removed as a metal sulfate aqueous solution 2B. When the alkali is lithium hydroxide, a first lithium salt aqueous solution is obtained. Furthermore, when the alkali is at least one selected from the group consisting of sodium hydroxide and potassium hydroxide, the first lithium salt aqueous solution and at least one salt of sodium and potassium can be separated from the alkali-mixed salt aqueous solution obtained in the first solvent extraction step using the method disclosed in Japanese Patent No. 7084669. If hydrochloric acid is used in the acid dissolution in STEP 1 (step 1), the lithium salt contained in the first lithium salt aqueous solution is lithium chloride. The organic solvent is at least one selected from the group consisting of organophosphorus compounds such as phosphate esters, phosphonates, hypophosphonic acids, and phosphine oxides, hydroxyoxime compounds, and organic amine compounds.

[0068] Examples of the aforementioned phosphine oxides include tri-n-octylphosphine oxide (TOPO). Examples of the aforementioned hydroxyoxime compounds include 7-hydroxy-5,8-diethyl-6-dodecanoate oxime (LIX-63), 5-dodecyl-2-hydroxybenzaldehyde oxime (LIX 860), 2-hydroxy-5-nonylbenzophenone oxime (LIX 65N), 2-hydroxy-5-nonylacetophenone oxime (SME529), and 2-hydroxy-5-nonylphenylbenzyl oxime (Acorga P-17). Examples of the aforementioned organic amine compounds include, for instance, Primene (registered trademark) JM-T produced by Dow Chemical Company as a primary amine, Amberlite (registered trademark) LA-2 produced by Sigma-Aldrich Company as a secondary amine, Alamine 336 (trioctylamine) produced by Sigma-Aldrich Company as a tertiary amine, and Aliquat (registered trademark) 336 produced by Sigma-Aldrich Company as a quaternary ammonium salt.

[0069] In the valuable metal recovery method of the present invention, the first lithium salt aqueous solution is then subjected to membrane electrolysis using an ion exchange membrane in step 4. For example, an ion exchange membrane can be used. Figure 2 The electrolytic cell 11 shown is used to perform the membrane electrolysis in step 4 above.

[0070] The electrolytic cell 11 has an anode plate 12 on one inner side and a cathode plate 13 on the inner side opposite to the anode plate 12. The anode plate 12 is connected to the anode 14 of the power supply, and the cathode plate 13 is connected to the cathode 15 of the power supply. In addition, the electrolytic cell 11 is divided into an anode chamber 17 with the anode plate 12 and a cathode chamber 18 with the cathode plate 13 by an ion exchange membrane 16.

[0071] In the electrolytic cell 11, when lithium chloride, which is the above-mentioned second lithium salt aqueous solution, is supplied to the anode chamber 17 and electrolysis is performed, chloride ions generate chlorine gas (Cl2) on the anode plate 12, while lithium ions move to the cathode chamber 18 via the ion exchange membrane 16.

[0072] In cathode chamber 18, water (H2O) ionizes into hydroxide ions (OH-). - ) and hydrogen ions (H + Hydrogen ions generate hydrogen gas (H2) on the cathode plate 13. On the other hand, hydroxide ions combine with lithium to generate an aqueous solution of lithium hydroxide 3.

[0073] The electricity used in the above-mentioned membrane electrolysis step preferably includes electricity obtained from renewable energy sources, and more preferably includes electricity obtained from at least one selected from the group consisting of solar power, wind power, geothermal power, hydropower and biomass power.

[0074] Hydrogen (H2) generated by the above membrane electrolysis is reacted with chlorine (Cl2) to obtain hydrochloric acid as inorganic acid 4, which can be used to dissolve active substance powder 1 in STEP 1 (step 1).

[0075] The lithium hydroxide aqueous solution 3 obtained by the above membrane electrolysis can also be recovered in step 5 as lithium hydroxide monohydrate (LiOH·H2O) by crystallization, or it can be recovered as lithium carbonate (Li2CO3) by carbonation in step 6. The above carbonation can be carried out by reacting the lithium hydroxide aqueous solution 3 with carbon dioxide (CO2).

[0076] When lithium hydroxide aqueous solution 3 is used for extraction from at least one solvent selected from the group consisting of steps 3A and 3B, lithium hydroxide aqueous solution 3 is added to the extraction solvent. Since the extraction solvent selected from the group consisting of STEP3A (step 3A) and STE3B (step 3B) is a cation exchange extractant, the solution properties tend to become acidic with continued use, resulting in a decrease in extraction rate. However, by adding lithium hydroxide aqueous solution 3, the decrease in extraction rate can be suppressed.

[0077] In addition, when lithium hydroxide aqueous solution 3 is used for solvent extraction in step 3B, lithium hydroxide aqueous solution 3 can be used for at least one solvent extraction in the separate solvent extraction of manganese, cobalt, and nickel.

[0078] Furthermore, in the membrane electrolysis described above, the first lithium salt aqueous solution is electrolyzed by the membrane, resulting in a second lithium salt aqueous solution that is more dilute than the first lithium salt aqueous solution. Therefore, in the valuable metal recovery method of the present invention, the second lithium salt aqueous solution can be concentrated in step 7 and added to the first lithium salt aqueous solution. For example, the concentration in step 7 can be performed using a reverse osmosis membrane (RO membrane).

[0079] In the valuable metal recovery method of the present invention, lithium, manganese, cobalt, and nickel can be separated from valuable metals that hinder the recovery of these valuable metals, thereby improving the recovery rate of lithium, manganese, cobalt, and nickel from spent lithium-ion batteries. In the valuable metal recovery method of the present invention, since no alkaline source other than lithium is provided, a high-concentration lithium salt aqueous solution can be obtained. Furthermore, in the valuable metal recovery method of the present invention, lithium hydroxide can be obtained by membrane electrolysis of the aforementioned high-concentration lithium salt aqueous solution, thereby improving the lithium recovery rate. Moreover, in the valuable metal recovery method of the present invention, since there is no unnecessary alkaline source other than lithium, the lithium hydroxide obtained by membrane electrolysis can be directly returned to the process for use, thereby achieving resource recycling.

[0080] Example

[0081] The present invention will now be described in more detail with reference to embodiments, but the present invention is not limited thereto.

[0082] In the examples and comparative examples, the content of valuable metals in each solution was determined using an inductively coupled plasma optical emission spectrometer (ICP-OES) manufactured by PerkinElmer Optima 8300.

[0083] (Example 1)

[0084] 10 kg of positive electrode powder obtained from spent lithium-ion batteries was dissolved in hydrochloric acid adjusted to a concentration of 9–10 mol / L to obtain 50 L of solution. In this solution, the concentrations of cobalt were 13 g / L, manganese 13 g / L, nickel 39 g / L, zirconium 100 mg / L, calcium 7 mg / L, magnesium 3 mg / L, and tungsten 0.1 mg / L. A kerosene solution of 1 M di(2-ethylhexyl) phosphate (D2EHPA) was added as an extractant to the solution, and the equilibrium pH was adjusted to 3 with a 6 mol / L lithium hydroxide aqueous solution, thereby separating lithium from the valuable metals in the solution. The extraction rates of each valuable metal are shown in Table 1.

[0085] (Examples 2-6)

[0086] As the extractants, kerosene solutions of 0.1M di(2-ethylhexyl) phosphate (D2EHPA) (Example 2), kerosene solutions of 1M ethylhexylphosphonate mono-2-ethylhexyl ester (PC-88A, manufactured by Daihachi Chemical Industry Co., Ltd.) (Example 3), kerosene solutions of 0.1M ethylhexylphosphonate mono-2-ethylhexyl ester (Example 4), decane solutions of 1M hypophosphonic acid (CYANEX 272, manufactured by Solvay Co., Ltd.) (Example 5), and decane solutions of 0.1M hypophosphonic acid (Example 6) were used instead of kerosene solutions of 1M di(2-ethylhexyl) phosphate (D2EHPA). The lithium in the solutions was separated from the valuable metals using the same method as in Example 1. The extraction rates of each valuable metal are shown in Table 1.

[0087] (Table 1)

[0088]

[0089] Therefore, it can be confirmed that calcium and zirconium can be extracted from a solution containing the above-mentioned valuable metals using di(2-ethylhexyl) phosphate (D2EHPA), zirconium can be extracted using 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester, and magnesium can be extracted using hypophosphonic acid.

[0090] Explanation of reference numerals in the attached figures

[0091] 1…active substance powder, 2A…extract, 2B…aqueous solution of metal sulfate, 3…aqueous solution of lithium hydroxide, 4…inorganic acid, 11…electrolytic cell, 16…ion exchange membrane.

Claims

1. A method for recycling valuable metals, characterized in that, include: In the first solvent extraction step, an organic solvent is added to a solution containing at least one valuable metal selected from the group consisting of transition metals other than manganese, cobalt, and nickel, alkaline earth metals, and aluminum, and lithium, to extract the valuable metal. The organic solvent contains at least one compound selected from the group consisting of compounds represented by Formula 1 below, phosphonates, phosphates, hypophosphitic acids, methyl isobutyl ketones, and trioctylamine. In Formula 1, R1 and R2 independently represent hydrocarbon groups with 6 to 20 carbon atoms.

2. The method for recycling valuable metals according to claim 1, characterized in that, Also includes: The dissolution step involves dissolving the active material powder obtained by pre-treating waste lithium-ion batteries in an inorganic acid to obtain a solution. The neutralization step involves neutralizing the solution with alkali. The second solvent extraction step involves using organic solvent extraction to separate at least one selected from the group consisting of manganese, cobalt, and nickel from the residue of the first solvent extraction step, thereby obtaining a first lithium salt aqueous solution as the residue of the solvent extraction. as well as The membrane electrolysis step involves electrolyzing the first lithium salt aqueous solution using an ion exchange membrane to obtain an aqueous solution of lithium hydroxide, an acid, and an aqueous solution of a second lithium salt that is more dilute than the first lithium salt aqueous solution. The lithium hydroxide aqueous solution obtained in the membrane electrolysis step can be reused in at least one step selected from the group consisting of the neutralization step, the first solvent extraction step, and the second solvent extraction step. The acid obtained in the membrane electrolysis step is reused as the inorganic acid used in the dissolution step.

3. The method for recycling valuable metals according to claim 2, characterized in that, The inorganic acid comprises at least one acid selected from the group consisting of hydrochloric acid, sulfuric acid, and nitric acid.

4. The method for recycling valuable metals according to claim 3, characterized in that, The inorganic acid includes hydrochloric acid.

5. The method for recycling valuable metals according to claim 2, characterized in that, The alkali used in the neutralization step includes lithium hydroxide.

6. The method for recycling valuable metals according to claim 1, characterized in that, The concentration of at least one component in the organic solvent selected from the group consisting of the compound represented by Formula 1, phosphonates, phosphates, hypophosphonic acids, methyl isobutyl ketone and trioctylamine is in the range of 0.001 M to 1.5 M.

7. The method for recovering valuable metals according to any one of claims 1 to 6, characterized in that, The electricity used in the membrane electrolysis step includes electricity obtained from renewable energy sources.

8. The method for recycling valuable metals according to claim 7, characterized in that, The electricity obtained through renewable energy includes electricity obtained by selecting at least one from the group consisting of solar power, wind power, geothermal power, hydropower and biomass power.

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