JP7506951B2 - Method for recovering valuable metals from discarded lithium-ion batteries - Google Patents

Description

The present invention relates to a method for recovering valuable metals from discarded lithium-ion batteries.

In recent years, with the widespread use of lithium-ion batteries, methods are being considered for recovering valuable metals such as lithium, manganese, nickel, and cobalt from used lithium-ion batteries and reusing them as positive electrode active materials for the lithium-ion batteries.

Conventionally, when recovering the valuable metals from the waste lithium-ion batteries, the waste lithium-ion batteries are subjected to a heat treatment (roasting), or are crushed and classified without being subjected to a heat treatment to obtain a powder containing the valuable metals (hereinafter, referred to as battery powder), which is dissolved in an acid, and the valuable metals are leached with the acid, and the obtained leachate is subjected to a solvent extraction (see, for example, Patent Documents 1 to 3).
When the leachate contains cobalt, the cobalt is extracted from the leachate with a solvent, and then back-extracted with sulfuric acid to obtain an aqueous cobalt sulfate solution. Cobalt sulfate can be obtained by crystallizing the aqueous cobalt sulfate solution (see, for example, Patent Document 4).

In addition, when the leachate contains nickel, the nickel can be extracted from the leachate with a solvent and then back-extracted with sulfuric acid to obtain an aqueous nickel sulfate solution (see, for example, Patent Document 6).

Furthermore, in order to reduce the amount of Na contained in nickel sulfate originating from sodium hydroxide used in neutralization after leaching of valuable metals, a method is known in which nickel is extracted from a crude nickel sulfate solution using an acidic organic extractant at a pH range of 6.0 to 7.0, the nickel content in the organic phase after extraction is maintained at 0.6 to 1.7 times the stoichiometric amount of nickel retained by the acidic organic extractant, the nickel-retaining organic phase after extraction is washed, and then back-extraction with sulfuric acid is performed (see, for example, Patent Document 7).

However, when manganese, cobalt, and nickel are successively extracted from the leachate using a solvent according to the method described in Patent Document 1, some of the lithium contained in the leachate is also co-extracted together with the manganese, cobalt, and nickel. This results in the inconvenience that the lithium content in the lithium salt aqueous solution as the final extraction residue is less than the lithium content in the leachate.

Cobalt sulfate produced by the method described in Patent Document 4 has a problem that impurities such as Na derived from sodium hydroxide used in neutralization after leaching of valuable metals and Cl derived from hydrochloric acid used in leaching valuable metals must be kept below a specified range in order to be used as a positive electrode active material for lithium ion batteries. If these impurities are contained in cobalt sulfate beyond the specified range, it will cause inconvenience in ensuring battery characteristics and safety, and will also damage the furnace body when firing the positive electrode material. Therefore, a method has been proposed in which the cobalt sulfate aqueous solution obtained by the back extraction is electrolyzed as an electrolyte to obtain electrolytic cobalt, the electrolytic cobalt is dissolved in acid, and cobalt is further extracted from the obtained cobalt solution with a solvent and back extracted to reduce the impurities contained in the cobalt sulfate to a specified range or less (see Patent Document 5, for example). However, the operation of the method described in Patent Document 5 is complicated.

The method described in Patent Document 6 uses a sulfurizing agent, which poses a risk of suffocation and requires complicated operations, while the method described in Patent Document 7 extracts nickel at a pH range of 6.0 to 7.0, which means there is a high possibility that nickel hydroxide will precipitate during extraction. Moreover, both methods have the disadvantage that it is not possible to reduce the concentrations of Na and Cl to less than 100 mg per kg of nickel.

Patent No. 4865745 Patent No. 6835820 Patent No. 6869444 International Publication No. 2013/099551 JP 2020-105597 A Japanese Patent No. 5904459 Japanese Patent No. 3546912

The present invention aims to eliminate such inconveniences and provide a method for recovering valuable metals with high purity from waste lithium-ion batteries.

The inventors of the present invention have conducted extensive research in light of the above problems and have discovered that it is possible to separate, at high purity, manganese, cobalt, and nickel from the valuable metals contained in the active material powder obtained by pretreating waste lithium-ion batteries, dissolved in a mineral acid, by solvent extraction from the acid solution, and to recover high-purity lithium from the first lithium salt aqueous solution recovered as the residual liquid of the solvent extraction. The present invention has been completed based on these findings.

The present invention relates to a method for recovering valuable metals from waste lithium-ion batteries, the method comprising: a dissolving step of dissolving an active material powder obtained by pretreating the waste lithium-ion batteries in a first mineral acid to obtain an acid solution; and a solvent extraction step of separating manganese, cobalt, and nickel from the acid solution by solvent extraction, among the metals contained in the active material powder, to obtain a first aqueous lithium salt solution as a residual liquid of the solvent extraction, the first mineral acid including hydrochloric acid .
The solvent extraction step preferably includes a cobalt extraction step of extracting cobalt using a first extraction solvent containing 2-ethylhexyl (2-ethylhexyl) phosphonate or bis(2,4,4-trimethylpentyl)phosphinic acid, a first cobalt scrubbing step of scrubbing the organic phase obtained in the cobalt extraction step with a second mineral acid for cobalt, and a cobalt stripping step of stripping cobalt with a third mineral acid for cobalt.
The solvent extraction step preferably further comprises a second scrubbing step for cobalt, in which the organic phase obtained in the first scrubbing step for cobalt is scrubbed with a third mineral acid for cobalt or water.
The solvent extraction step preferably includes a nickel extraction step of extracting nickel using an extraction solvent containing bis(2,4,4-trimethylpentyl)phosphinic acid, a first scrubbing step for nickel of scrubbing the organic phase obtained in the nickel extraction step with a second mineral acid for nickel, and a nickel stripping step of stripping nickel with a third mineral acid for nickel.
The method for recovering valuable metals from waste lithium ion batteries of the present invention preferably further includes a second scrubbing step for nickel, in which the organic phase obtained in the first scrubbing step for nickel is scrubbed with a third mineral acid for nickel or water.
The solvent extraction step preferably further comprises a manganese extraction step of performing solvent extraction of manganese with a first organic solvent using the acid solution as a first main extractant to obtain a manganese-containing organic phase and a first extraction residue, a cobalt extraction step of performing solvent extraction of cobalt with a second organic solvent using the first extraction residue as a second main extractant to obtain a cobalt-containing organic phase and a second extraction residue, and a nickel extraction step of performing solvent extraction of nickel with a third organic solvent using the second extraction residue as a third main extractant to obtain a nickel-containing organic phase and the first lithium salt aqueous solution as a third extraction residue. the at least one first scrubbing step for valuable metals in which at least one organic phase of any one of the first to third steps is scrubbed with a second mineral acid for valuable metals, and at least one valuable metal stripping step in which at least one valuable metal selected from the group consisting of manganese, cobalt and nickel is stripped with a third mineral acid for valuable metals, and the second mineral acid for valuable metals after the at least one first scrubbing step for valuable metals is returned to any one of the first to third forward extraction solutions corresponding to the organic phase in the at least one first scrubbing step for valuable metals .
The method for recovering valuable metals from waste lithium ion batteries of the present invention preferably further comprises at least one second scrubbing step for valuable metals, in which at least one organic phase obtained in the at least one first scrubbing step for valuable metals is scrubbed with a third mineral acid for valuable metals or water.
The first organic solvent preferably comprises bis(2-ethylhexyl) hydrogen phosphate, the second organic solvent comprises 2-ethylhexyl (2-ethylhexyl) phosphonate or bis(2,4,4-trimethylpentyl)phosphinic acid, and the third organic solvent comprises bis(2,4,4-trimethylpentyl)phosphinic acid.

The extraction solvent used in said solvent extraction of cobalt preferably comprises at least one linear hydrocarbon compound selected from the group consisting of nonane, decane, and undecane.
The extraction solvent used for said solvent extraction of nickel preferably comprises decane.
Each of the third mineral acid for cobalt and the third mineral acid for nickel preferably contains sulfuric acid.

The dissolving step preferably includes a step of stirring the active material powder in hydrochloric acid having a concentration in the range of 50 to 150 g/L at a mass ratio in the range of 250 to 1000% relative to the hydrogen chloride in the hydrochloric acid to obtain a hydrochloric acid suspension of the active material powder, and a step of adding a predetermined amount of hydrochloric acid to the hydrochloric acid suspension so that the concentration of hydrochloric acid in the hydrochloric acid suspension is in the range of 150 to 350 g/L and the mass ratio of the active material powder in the hydrochloric acid suspension is in the range of 50 to 200% relative to the hydrogen chloride in the hydrochloric acid suspension, and stirring the mixture.

Next, the embodiment of the present invention will be described in more detail.
The method for recovering valuable metals from used lithium ion batteries of the present invention includes a dissolving step in which an active material powder obtained by pretreating used lithium ion batteries is dissolved in a mineral acid to obtain an acid solution. In the dissolving step, a powder containing various valuable metals (battery powder) obtained from the used lithium ion batteries is leached with the mineral acid to obtain an acid solution in which various valuable metals including manganese, cobalt, and nickel are dissolved.

In the method of recovering valuable metals from used lithium-ion batteries of the present invention (hereinafter sometimes referred to as the "valuable metal recovery method"), the used lithium-ion batteries refer to used lithium-ion batteries that have reached the end of their life as battery products, lithium-ion batteries that have been discarded as defective products during the manufacturing process, residual positive electrode materials used in the manufacture of products during the manufacturing process, etc.

The powder containing the valuable metals can be obtained, for example, as follows. First, the positive electrode foil (a positive electrode mixture containing a positive electrode active material is applied to an aluminum foil current collector) that is the residual positive electrode material used in the manufacturing process of lithium-ion batteries is heat-treated (roasted) in an electric furnace at a temperature in the range of, for example, 100 to 450°C, or is crushed with a crusher such as a hammer mill or jaw crusher without being heat-treated, and the casing, current collector, etc. that constitute the waste lithium-ion battery are removed (classified) by sieving to obtain a battery powder containing valuable metals.

Alternatively, used lithium ion batteries that have not been discharged or heated may be crushed in the crusher, the casing, current collectors, etc. may be removed by sieving, and then the battery powder may be obtained by heat treatment at a temperature within the above range.

In the valuable metal recovery method of the present invention, the electrode powder is leached with a first mineral acid. As a result, an acid solution of the various valuable metals is obtained. The first mineral acid preferably includes at least one selected from the group consisting of hydrochloric acid, sulfuric acid, and nitric acid, and more preferably includes hydrochloric acid.

The dissolving step may include a step of supplying the active material powder to hydrochloric acid having a concentration in the range of 50 to 150 g/L in a mass ratio in the range of 250 to 1000% relative to the hydrogen chloride in the hydrochloric acid, stirring to obtain a hydrochloric acid suspension of the active material powder, and a step of adding a predetermined amount of hydrochloric acid to the hydrochloric acid suspension so that the concentration of hydrochloric acid in the hydrochloric acid suspension is in the range of 150 to 350 g/L and the mass ratio of the active material powder in the hydrochloric acid suspension is in the range of 50 to 200% relative to the hydrogen chloride in the hydrochloric acid suspension, and stirring the mixture.

The valuable metal recovery method of the present invention preferably includes a neutralization step of neutralizing the acid solution with an alkali. The alkali includes, for example, a hydroxide of an alkali metal. The alkali metal preferably includes at least one selected from the group consisting of lithium, sodium, potassium, rubidium, cesium, and francium, and more preferably includes at least one selected from the group consisting of lithium, sodium, and potassium. The alkali may be added to the acid solution as an aqueous solution, may be added to the acid solution as a solid, or may be added to the acid solution in both an aqueous solution and a solid state.

The valuable metal recovery method of the present invention includes a solvent extraction step in which manganese, cobalt, and nickel, among the metals contained in the active material powder, are separated from the acid solution by solvent extraction, and a first lithium salt aqueous solution is obtained as the residual liquid of the solvent extraction.

In the valuable metal recovery method according to the first embodiment of the present invention, the solvent extraction step includes a cobalt extraction step in which cobalt is extracted using a first extraction solvent containing 2-ethylhexyl (2-ethylhexyl) phosphonate or bis(2,4,4-trimethylpentyl)phosphinic acid. In the cobalt extraction step, manganese is solvent-extracted from the acid solution using bis(2-ethylhexyl) hydrogen phosphate as an extraction solvent, and the resulting extraction residue can be an aqueous cobalt salt solution. The manganese solvent extraction can be performed by, for example, adding 1 mol/L of bis(2-ethylhexyl) hydrogen phosphate (manufactured by Nacalai Tesque, Inc.) diluted with kerosene to the valuable metal leachate and adjusting it.

To the cobalt salt aqueous solution, which is the extraction residue, bis(2,4,4-trimethylpentyl)phosphinic acid diluted with at least one straight-chain hydrocarbon compound selected from the group consisting of nonane, decane, and undecane may be added to perform solvent extraction of cobalt. For example, 1 mol/L of bis(2,4,4-trimethylpentyl)phosphinic acid (manufactured by Solvay) diluted with decane may be added to perform solvent extraction of cobalt.

The valuable metal recovery method of the first embodiment of the present invention includes a first scrubbing step for cobalt in which the organic phase obtained in the cobalt extraction step is scrubbed with a second mineral acid for cobalt, and a cobalt stripping step in which cobalt is stripped with a third mineral acid for cobalt. The valuable metal recovery method of the first embodiment of the present invention may further include a second scrubbing step for cobalt in which the organic phase obtained in the first scrubbing step for cobalt is scrubbed with a third mineral acid for cobalt or water. Each of the second mineral acid for cobalt and the third mineral acid for cobalt includes at least one selected from the group consisting of hydrochloric acid, sulfuric acid, and nitric acid, more preferably includes hydrochloric acid or sulfuric acid, and even more preferably is hydrochloric acid or sulfuric acid. The organic phase from which the cobalt has been extracted is subjected to a first scrubbing for cobalt using a second mineral acid for cobalt, and the organic phase after the first scrubbing for cobalt is subjected to back extraction using a third mineral acid for cobalt, thereby obtaining an aqueous cobalt salt solution, the aqueous cobalt salt solution having reduced contents of Na and Cl as impurities below the range required for a positive electrode active material of a lithium ion battery.

The concentrations of valuable metals and Na contained in the cobalt salt aqueous solution can be measured, for example, by an inductively coupled plasma optical emission spectrometer (PerkinElmer, product name: Optima-8300, hereinafter sometimes referred to as "ICP-OES"). The concentration of Cl contained in the cobalt salt aqueous solution can be measured by an ion chromatograph (Metrhom, product name: 930 Compact IC Flex, hereinafter sometimes referred to as "IC").

In the valuable metal recovery method according to the second embodiment of the present invention, the solvent extraction step includes a nickel extraction step in which nickel is extracted using an extraction solvent containing bis(2,4,4-trimethylpentyl)phosphinic acid. In the nickel extraction step, nickel can be extracted from the acid solution, but it is also possible to extract cobalt from the manganese extraction residue obtained by solvent-extracting manganese from the acid solution using bis(2-ethylhexyl) hydrogen phosphate as an extraction solvent, and further extract nickel from the cobalt extraction residue using 2-ethylhexyl (2-ethylhexyl) phosphonate or bis(2,4,4-trimethylpentyl)phosphinic acid as an extraction solvent. The manganese solvent extraction can be performed, for example, by adding 1 mol/L of bis(2-ethylhexyl) hydrogen phosphate (manufactured by Nacalai Tesque, Inc.) diluted with kerosene to the acid solution.

The cobalt can be extracted with a solvent, for example, by neutralizing the manganese extraction residue, precipitating the manganese that was not extracted in the manganese solvent extraction, filtering off the precipitate, and then adding 1 mol/L of bis(2,4,4-trimethylpentyl)phosphinic acid (manufactured by Solvay) diluted with at least one linear hydrocarbon compound selected from the group consisting of nonane, decane, and undecane.

Nickel can be extracted from the cobalt extraction residue by adding 1 mol/L of bis(2,4,4-trimethylpentyl)phosphinic acid (manufactured by Solvay) diluted with decane to the cobalt extraction residue.

The valuable metal recovery method of the second embodiment of the present invention includes a first scrubbing step for nickel in which the organic phase obtained in the nickel extraction step is scrubbed with a second mineral acid for nickel, and a nickel stripping step in which nickel is stripped with a third mineral acid for nickel. Furthermore, the valuable metal recovery method of the second embodiment of the present invention may further include a second scrubbing step for nickel in which the organic phase obtained in the first scrubbing step for nickel is scrubbed with a third mineral acid for nickel or water. Each of the second mineral acid for nickel and the third mineral acid for nickel includes at least one selected from the group consisting of hydrochloric acid, sulfuric acid, and nitric acid, more preferably sulfuric acid, and even more preferably sulfuric acid. The organic phase from which nickel has been extracted is subjected to a first scrubbing for nickel using the second mineral acid for nickel, and the organic phase after the first scrubbing for nickel is stripped using the third mineral acid for nickel, thereby obtaining an aqueous cobalt salt solution. The contents of Na and Cl as impurities in the nickel salt aqueous solution are preferably reduced to a range of less than 100 mg per kg of nickel required as a positive electrode active material for lithium ion batteries.

The concentrations of valuable metals and Na contained in the nickel salt aqueous solution can be measured, for example, by an inductively coupled plasma optical emission spectrometry (ICP-OES). The concentration of Cl contained in the nickel salt aqueous solution can be measured by an ion chromatography (IC).

In the valuable metal recovery method of the third embodiment of the present invention, the solvent extraction process includes a manganese extraction process (a) in which manganese is solvent extracted with a first organic solvent using the acid solution as a first positive extraction liquid to obtain a manganese-containing organic phase and a first extraction residue, a cobalt extraction process (b) in which cobalt is solvent extracted with a second organic solvent using the first extraction residue as a second positive extraction liquid to obtain a cobalt-containing organic phase and a second extraction residue, and a nickel extraction process (c) in which nickel is solvent extracted with a third organic solvent using the second extraction residue as a third positive extraction liquid to obtain a nickel-containing organic phase and the first lithium salt aqueous solution as the third extraction residue.

The first organic solvent preferably comprises bis(2-ethylhexyl) hydrogen phosphate, the second organic solvent preferably comprises 2-ethylhexyl (2-ethylhexyl) phosphonate or bis(2,4,4-trimethylpentyl)phosphinic acid, and the third organic solvent preferably comprises bis(2,4,4-trimethylpentyl)phosphinic acid.

The valuable metal recovery method of the third embodiment of the present invention includes at least one first scrubbing step for valuable metals, in which at least one organic phase of any one of the first to third methods is scrubbed with a second mineral acid for valuable metals, and at least one valuable metal stripping step for stripping at least one valuable metal selected from the group consisting of manganese, cobalt, and nickel with a third mineral acid for the organic phase. Furthermore, the valuable metal recovery method of the third embodiment of the present invention may further include at least one second scrubbing step for valuable metals, in which at least one organic phase obtained in the first scrubbing step for valuable metals is scrubbed with a third mineral acid for valuable metals or water. Each of the second mineral acid for valuable metals and the third mineral acid for valuable metals includes at least one selected from the group consisting of hydrochloric acid, sulfuric acid, and nitric acid, more preferably includes sulfuric acid, and even more preferably is sulfuric acid. The organic phase from which the valuable metals have been extracted is subjected to a first scrubbing for valuable metals using a second mineral acid for valuable metals, and the organic phase after the first scrubbing for valuable metals is subjected to back extraction using a third mineral acid for valuable metals, thereby obtaining an aqueous solution of a valuable metal salt.

The extraction steps (a) to (c) are carried out, for example, as follows.
75 L of the valuable metal solution as the acid dissolution solution is used as a first main extraction solution, and 75 L of 1 mol/L bis(2-ethylhexyl) hydrogen phosphate (manufactured by Nacalai Tesque, Inc.) diluted with kerosene is added to perform a solvent extraction of manganese, and 80 L of an aqueous cobalt salt solution is obtained as a first extraction residue. The 80 L of the aqueous cobalt salt solution is neutralized, and the resulting precipitate is filtered off to obtain 83 L of an aqueous cobalt salt solution.

83 L of the aqueous cobalt salt solution as the first extraction residue is used as the second positive extraction liquid, and 83 L of 1 mol/L bis(2,4,4-trimethylpentyl)phosphinic acid (Solvay) diluted with at least one selected from the group consisting of nonane, decane, and undecane is added to perform solvent extraction of cobalt. The obtained second organic phase is scrubbed using 16.6 L of hydrochloric acid, and the hydrochloric acid after scrubbing is returned to the second positive extraction liquid. In addition, the second organic phase after scrubbing is subjected to a back extraction operation using 11 L of sulfuric acid.

83 L of the nickel salt aqueous solution as the second extraction residue is used as the second main extraction liquid, and 83 L of 1 mol/L bis(2,4,4-trimethylpentyl)phosphinic acid (manufactured by Solvay) diluted with decane is added to perform solvent extraction of nickel.

In the method for recovering lithium from waste lithium-ion batteries according to the third embodiment of the present invention, any one of the first to third organic phases is scrubbed with hydrochloric acid, and the hydrochloric acid after the scrubbing is returned to any one of the first to third positive extracts corresponding to the organic phase that was scrubbed. For example, the third organic phase is scrubbed using 16.6 L of hydrochloric acid solution, and the hydrochloric acid after the scrubbing is returned to the second positive extract. In addition, the third organic phase after scrubbing is back-extracted using 15 L of sulfuric acid solution.

The present invention will now be described in further detail with reference to examples, but the present invention is not limited to these.

In the examples, various physical properties were measured or calculated as follows.
<Measurement of the mass of valuable metals and Na contained in the aqueous solution of valuable metal salts>
The masses of the valuable metals and Na contained in each aqueous solution of valuable metal salt were measured by an inductively coupled plasma optical emission spectrometer (ICP-OES).

<Measurement of the mass of Cl contained in the aqueous solution of valuable metal salt>
The mass of Cl contained in each aqueous solution of valuable metal salt was measured by an ion chromatograph (IC).

Example 1
A positive electrode foil (a positive electrode mixture containing a positive electrode active material is applied to an aluminum foil current collector) that is a residual positive electrode material used in the manufacturing process of a lithium ion battery was heated in an electric furnace in an air atmosphere at a temperature of 400° C. for 10 minutes. Next, the positive electrode foil was crushed using a jaw crusher, and the aluminum foil was separated using a sieve with a mesh size of 1 mm to obtain a positive electrode powder (battery powder).
Next, 10 kg of the positive electrode powder was dissolved in a mixed solution of 48 kg (40 L) of hydrochloric acid and 35 kg (35 L) of water to obtain 75 L of an acid solution. 75 L of 1 mol/L bis(2-ethylhexyl) hydrogen phosphate (manufactured by Nacalai Tesque, Inc.) diluted with kerosene was added to the 75 L of the acid solution, and a 20 mass % aqueous sodium hydroxide solution was further added to perform solvent extraction of manganese, and 80 L of an aqueous crude cobalt salt solution was obtained as an extraction residue.
Next, 0.025 L was sampled from the obtained 0.5 L of the crude cobalt salt aqueous solution, and 0.025 L of 1 mol/L bis(2,4,4-trimethylpentyl)phosphinic acid (manufactured by Solvay) adjusted with nonane was added thereto, Co was subjected to a solvent extraction operation, and a 20 mass % aqueous sodium hydroxide solution was added thereto.
0.020 L of the extracted organic phase was sampled and scrubbed with 0.0010 L of 2.3% by mass hydrochloric acid adjusted to pH 0.2. 0.012 L of the scrubbed organic phase was sampled and stripped with 0.0020 L of 1.8 M sulfuric acid to obtain a stripped solution.
The masses of metals contained in the stripped solution were measured by ICP-OES and IC, and were found to contain 18 mg of Co, 0.014 mg of Na, and 0.020 mg (1100 mg/kg) of Cl. In other words, the stripped solution contained 770 mg of Na per kg of Co and 1100 mg of Cl per kg of Co.

Example 2
From 0.5 L of the crude cobalt salt aqueous solution, 0.025 L was taken, and 0.025 L of 1 mol/L bis(2,4,4-trimethylpentyl)phosphinic acid (manufactured by Solvay) adjusted with decane was added thereto, Co was subjected to a solvent extraction operation, and a 20 mass % aqueous sodium hydroxide solution was added thereto.
0.020 L of the extracted organic phase was collected and scrubbed with 0.0010 L of diluted sulfuric acid adjusted to pH 0.2. 0.012 L of the scrubbed organic phase was stripped with 0.0020 L of 1.8 M sulfuric acid to obtain a stripped solution.
The masses of metals contained in the stripped solution were measured by ICP-OES and IC, and were found to contain 18 mg of Co, 0.044 mg of Na, and 0.057 mg of Cl. In other words, the stripped solution contained 2400 mg of Na per kg of Co and 3100 mg of Cl per kg of Co.

Example 3
From 0.5 L of the crude cobalt salt aqueous solution, 0.025 L was taken, and 0.025 L of 1 mol/L bis(2,4,4-trimethylpentyl)phosphinic acid (manufactured by Solvay) adjusted with undecane was added to perform a solvent extraction operation of Co. A 20 mass % aqueous sodium hydroxide solution was added until the equilibrium pH reached 3.9.
0.020 L of the extracted organic phase was collected and scrubbed with 0.0010 L of diluted sulfuric acid adjusted to pH 0.2. 0.012 L of the scrubbed organic phase was collected and stripped with 0.0020 L of 1.8 M sulfuric acid to obtain a stripped solution.
The masses of metals contained in the stripped solution were measured by ICP-OES and IC, and were found to contain 19 mg of Co, 0.046 mg of Na, and 0.061 mg of Cl. In other words, the stripped solution contained 2400 mg of Na per kg of Co and 3200 mg of Cl per kg of Co.

Example 4
From 0.5 L of the crude cobalt salt aqueous solution, 0.025 L was taken, and 0.025 L of 1 mol/L bis(2,4,4-trimethylpentyl)phosphinic acid (manufactured by Solvay) adjusted with kerosene was added to perform a solvent extraction operation of Co. A 20 mass % aqueous sodium hydroxide solution was added until the equilibrium pH reached 3.9.
0.020 L of the extracted organic phase was collected and scrubbed with 0.0010 L of diluted sulfuric acid adjusted to pH 0.2. 0.012 L of the scrubbed organic phase was collected and stripped with 0.0020 L of 1.8 M sulfuric acid to obtain a stripped solution.
The masses of metals contained in the stripped solution were measured by ICP-OES and IC, and were found to contain 20 mg of Co, 0.15 mg of Na, and 0.20 mg of Cl. In other words, the stripped solution contained 7,700 mg of Na per kg of Co and 10,000 mg of Cl per kg of Co.

Example 5
A positive electrode foil (a positive electrode mixture containing a positive electrode active material is applied to an aluminum foil current collector) that is a residual positive electrode material used in the manufacturing process of a lithium ion battery was heated in an electric furnace in an air atmosphere at a temperature of 400° C. for 10 minutes. Next, the positive electrode foil was crushed using a jaw crusher, and the aluminum foil was separated using a sieve with a mesh size of 1 mm to obtain a positive electrode powder (battery powder).
Next, 10 kg of the positive electrode powder was dissolved in a mixture of 48 kg (40 L) of hydrochloric acid and 35 kg (35 L) of water to obtain 75 L of an acid solution.
Next, 75 L of 1 mol/L bis(2-ethylhexyl) hydrogen phosphate (manufactured by Nacalai Tesque, Inc.) diluted with kerosene was added to 75 L of the crude valuable metal solution, and a 20 mass% aqueous sodium hydroxide solution was added to adjust the amount, to perform solvent extraction of manganese, and 80 L of an aqueous cobalt salt solution was obtained as an extraction residue.
A 20% by mass aqueous solution of sodium hydroxide was added to 80 L of the aqueous cobalt salt solution to carry out neutralization, and the precipitate was separated by filtration to obtain 83 L of an aqueous cobalt salt solution.
To 83 L of the extraction residue, 83 L of 1 mol/L bis(2,4,4-trimethylpentyl)phosphinic acid (manufactured by Solvay) diluted with decane was added to perform a solvent extraction operation of Co. The extracted organic phase was subjected to a scrubbing operation using 16.6 L of 2.3 mass % hydrochloric acid. The organic phase after scrubbing was subjected to a back extraction operation using 11 L of a sulfuric acid solution.
To 83 L of the extraction residue, 83 L of 1 mol/L bis(2,4,4-trimethylpentyl)phosphinic acid (manufactured by Solvay) diluted with decane was added, and a Ni solvent extraction operation was performed. The extracted organic phase was scrubbed using 16.6 L of 2.3 mass% hydrochloric acid. The organic phase after scrubbing was back-extracted using 15 L of sulfuric acid solution. The nickel salt aqueous solution after back extraction contained 980 g (65 g/kg) of Ni, 10 mg (10 mg/kg) of Li, and 10 mg (10 mg/kg) of Na.

Claims (13)

A method for recovering valuable metals from waste lithium ion batteries, comprising:
a dissolving step of dissolving the active material powder obtained by pretreating the waste lithium ion batteries in a first mineral acid to obtain an acid solution;
a solvent extraction step of separating manganese, cobalt, and nickel from the acid solution by solvent extraction, among the metals contained in the active material powder, and obtaining a first lithium salt aqueous solution as a residue of the solvent extraction ;
The method for recovering valuable metals from waste lithium ion batteries, wherein the first mineral acid comprises hydrochloric acid . The method for recovering valuable metals from waste lithium ion batteries according to claim 1,
a cobalt extraction step, the solvent extraction step extracting cobalt using a first extraction solvent comprising 2-ethylhexyl (2-ethylhexyl) phosphonate or bis(2,4,4-trimethylpentyl) phosphinic acid;
The method for recovering valuable metals from waste lithium-ion batteries comprises a first cobalt scrubbing step in which the organic phase obtained in the cobalt extraction step is scrubbed with a second mineral acid for cobalt, and a cobalt stripping step in which cobalt is stripped with a third mineral acid for cobalt. The method for recovering valuable metals from waste lithium ion batteries according to claim 2,
A method for recovering valuable metals from waste lithium ion batteries, further comprising a second scrubbing step for cobalt, in which the organic phase obtained in the first scrubbing step for cobalt is scrubbed with a third mineral acid for cobalt or water. The method for recovering valuable metals from waste lithium ion batteries according to claim 1,
The solvent extraction step is a nickel extraction step in which nickel is extracted using an extraction solvent containing bis(2,4,4-trimethylpentyl)phosphinic acid;
The method for recovering valuable metals from waste lithium-ion batteries comprises: a first scrubbing step for nickel in which the organic phase obtained in the nickel extraction step is scrubbed with a second mineral acid for nickel; and a nickel stripping step in which nickel is stripped with a third mineral acid for nickel. The method for recovering valuable metals from waste lithium ion batteries according to claim 4,
A method for recovering valuable metals from waste lithium-ion batteries, further comprising a second scrubbing step for nickel, in which the organic phase obtained in the first scrubbing step for nickel is scrubbed with the third mineral acid for nickel or water. The method for recovering valuable metals from waste lithium ion batteries according to claim 1,
the solvent extraction step includes a manganese extraction step of performing solvent extraction of manganese with a first organic solvent using the acid solution as a first main extract to obtain a manganese-containing organic phase and a first extraction residue;
a cobalt extraction step of performing solvent extraction of cobalt with a second organic solvent using the first extraction residue as a second main extraction liquid to obtain a cobalt-containing organic phase and a second extraction residue;
a nickel extraction step of performing a solvent extraction of nickel with a third organic solvent using the second extraction bottom solution as a third extraction bottom solution to obtain a nickel-containing organic phase and the first lithium salt aqueous solution as a third extraction bottom solution;
At least one first scrubbing step for valuable metals, in which at least one of the organic phases of any one of the first to third steps is scrubbed with a second mineral acid for valuable metals;
A method for recovering valuable metals from waste lithium-ion batteries, comprising at least one valuable metal stripping step in which at least one valuable metal selected from the group consisting of manganese, cobalt, and nickel is stripped with a third mineral acid for valuable metals , and the second mineral acid for valuable metals after the at least one first scrubbing step for valuable metals is returned to any one of the first to third forward extraction solutions corresponding to the organic phase in the at least one first scrubbing step for valuable metals. The method for recovering valuable metals from waste lithium ion batteries according to claim 6,
1. A method for recovering valuable metals from waste lithium ion batteries, comprising the steps of: scrubbing at least one organic phase obtained in said at least one first scrubbing step for valuable metals with a third mineral acid for valuable metals or water; The method for recovering valuable metals from waste lithium ion batteries according to claim 6,
A method for recovering valuable metals from waste lithium ion batteries, characterized in that the first organic solvent contains bis(2-ethylhexyl) hydrogen phosphate, the second organic solvent contains 2-ethylhexyl(2-ethylhexyl)phosphonate or bis(2,4,4-trimethylpentyl)phosphinic acid, and the third organic solvent contains bis(2,4,4-trimethylpentyl)phosphinic acid. The method for recovering valuable metals from waste lithium ion batteries according to any one of claims 1 to 3 and 6 to 8,
1. A method for recovering valuable metals from waste lithium ion batteries, characterized in that the extraction solvent used in the solvent extraction of cobalt contains at least one linear hydrocarbon compound selected from the group consisting of nonane, decane, and undecane. The method for recovering valuable metals from waste lithium ion batteries according to any one of claims 1 and 4 to 8,
2. A method for recovering valuable metals from waste lithium ion batteries, characterized in that the extraction solvent used for the solvent extraction of nickel contains decane. 4. The method for recovering valuable metals from waste lithium ion batteries according to claim 2 or 3 , wherein the third mineral acid for cobalt contains sulfuric acid . 6. The method for recovering valuable metals from waste lithium ion batteries according to claim 4 or 5 , wherein the third mineral acid for nickel contains sulfuric acid . In the method for recovering valuable metals from waste lithium ion batteries according to any one of claims 1 to 8, the dissolving step comprises:
supplying the active material powder to hydrochloric acid having a concentration in the range of 50 to 150 g/L in a mass ratio in the range of 250 to 1000% relative to hydrogen chloride in the hydrochloric acid to obtain a hydrochloric acid suspension of the active material powder;
a step of adding a predetermined amount of hydrochloric acid to the hydrochloric acid suspension to adjust the concentration of hydrochloric acid in the hydrochloric acid suspension to a range of 150 to 350 g/L and adjusting the mass ratio of the active material powder in the hydrochloric acid suspension to the hydrogen chloride in the hydrochloric acid suspension to a range of 50 to 200%, and stirring the mixture.