JPH10287864A - Recovery of valuable metal from active material of positive electrode for lithium ion secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable the recovery of a valuable metal such as cobalt or nickel from an active material of a positive electrode for a lithium ion secondary battery at a high extraction ratio by bringing a metal extracting agent into contact with an eluate prepared by adding a mineral acid-containing liquid to the active material of the positive electrode. SOLUTION: (B) A mineral acid or a mixture liquid thereof with hydrogen peroxide is added to (A) an active material of a positive electrode for a lithium ion secondary battery and the obtained eluate is then separated. An organic solvent containing (C) a metal extracting agent such as a compound represented by the formula (X<1> and X<2> are each O or S) is subsequently brought into contact with the separated eluate to carry out the extraction and separation treatment. The mineral acid is then brought into contact with the phase of the extracted organic solvent to perform the reverse extraction separation. The operations are preferably carried out by using the components A and B so as to provide (1:1:1) to (1:5:5) molar ratio of the valuable metal in the component A, mineral acid in the component B and hydrogen peroxide.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method of recovering valuable metals from a positive electrode active material for a lithium ion secondary battery.

[0002]

2. Description of the Related Art In recent years, the demand for lithium ion secondary batteries has been rapidly growing, especially for portable telephones, PHSs, and portable personal computers because of their features of high energy density, small size and light weight. In addition, it is expected that it will be used as a large energy storage medium and a power source for electric vehicles in the future. The lithium ion secondary battery uses LiCo with high electromotive force as its cathode material.
Lithium-containing transition metal oxides such as O ₂ , LiNiO ₂ , and LiMn ₂ O ₄ are used, and currently LiCoO _{2, which} is relatively easy to synthesize and is stable, is mainly used for the positive electrode.

[0003] However, Ni and the like are rare metals, such as Co, and the cost of the materials is high due to the problem of uneven distribution of economic resources. Recovering such precious metals is extremely important as a method of effectively utilizing resources. That is what. Until now, several methods have been proposed for recovering these noble metals from recovering noble metal atoms such as Co from waste lithium secondary batteries. For example, a method of roasting a used secondary battery, then pulverizing, sieving, or magnetically sorting under the sieve (JP-A-6-322452, JP-A-6-3-3)
46160, JP-A-7-245126),
Similarly, a method of roasting, pulverizing, sieving, and acid-treating, and adding an alkali to precipitate and recover Co, Ni, etc. as carbonates and hydroxides (Japanese Patent Laid-Open No. 7-207349)
Publication).

As a method for purifying and separating nickel and cobalt, a solvent extraction method has been known for some time. For example, a method using a primary to tertiary amine or a quaternary ammonium salt (JP-A-50-57022) Gazette, JP-A-54-
68720), a dialkylphosphinic acid compound derived from a dialkylphosphine (JP-A-57-73).
142, JP-A-57-73143, JP-A-61-44139, JP-A-1-315384, JP-A-6-264156) and the like. Further, when producing a positive electrode agent such as lithium cobaltate, it is necessary to recover cobalt from waste lithium cobaltate or the like due to off-specification or production error outside the standard value of the lithium ion secondary battery.

[0005]

In view of the above facts, the present inventors have conducted intensive studies on a method for separating and recovering a noble metal present in a positive electrode active material for a lithium ion secondary battery. It has been confirmed that each valuable metal can be separated and recovered by bringing a valuable metal extractant into contact with an eluate dissolved with a mixed solution of an acid or a mineral acid and hydrogen peroxide, thereby completing the present invention.

[0006]

That is, the first aspect of the present invention is to firstly add a mineral acid or a mixture of a mineral acid and hydrogen peroxide to a positive electrode active material for a lithium ion secondary battery and then remove the eluate. The first step of separation, and the second step of extracting and separating the separated eluate by contacting the separated eluate with an organic solvent containing a metal extractant.
Providing a method for recovering valuable metals from a positive electrode active material for a lithium ion secondary battery, comprising a third step of back-extraction separation by bringing a mineral acid into contact with the organic solvent phase of the extract liquid, followed by a third step. It is.

Further, a second aspect of the present invention is a step of bringing the raffinate (aqueous phase) which has been subjected to the second step into contact with an organic solvent containing a metal extractant to carry out an extraction separation treatment. The valuable metal from the positive electrode active material for a lithium ion secondary battery as described above, wherein different valuable metals are separately collected by performing a step of back extraction and separation by contacting a mineral acid with a solvent phase. The present invention provides a method for recovering the above.

[0008] A third aspect of the present invention is the above-mentioned lithium ion, wherein hydrogen peroxide remaining in the elution solution separated in the first step is decomposed with a reducing agent and then subjected to the second step. An object of the present invention is to provide a method for recovering valuable metals from a positive electrode active material for a secondary battery. A fourth aspect of the present invention is a metal extractant represented by the following general formula (1):

[0009]

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Wherein X ¹ and X ² represent an oxygen atom or a sulfur atom, provided that X ¹ and X ² may be the same or different. An object of the present invention is to provide a method for recovering valuable metals from the above-mentioned positive electrode active material for a lithium ion secondary battery, using a (1,3,3-tetramethylbutyl) phosphinic acid compound.

A fifth aspect of the present invention is that the molar ratio of the valuable metal, the mineral acid and the hydrogen peroxide in the positive electrode active material for a lithium ion secondary battery is 1: 1: 1-1: 5: 5, respectively. Another object of the present invention is to provide a method for recovering valuable metals from the positive electrode active material for a lithium ion secondary battery, which is within the above range.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The positive electrode active material for a lithium ion secondary battery to be treated in the method of the present invention, which explains the present invention in more detail, is LiCo as a positive electrode active material.
It refers to defective products generated during the manufacturing process of lithium-containing transition metal oxides such as O ₂ , LiNiO ₂ , LiMn ₂ O ₄ or the like, sampling inspection products for quality control, off-spec products out of specification, and the like. Valuable metals in the lithium ion secondary battery positive electrode agent differ depending on the type of the lithium ion secondary battery positive electrode agent, for example, Al, Co, Ni, Mn.
(Hereinafter referred to as “Co etc.”), but mainly LiCo
O ₂ , LiNiO ₂ , LiMn ₂ O ₄ , LiNix Co
refers to valuable metal components such as Co that results from y O _2.
The valuable metal extractant from such compounds of the present invention is a phosphorus-containing compound and a carboxylic acid compound, an alkylsulfonic acid compound, a tertiary amine compound, a chelate-based compound, preferably a phosphorus-containing compound, and more preferably. Is the general formula (1):

[0013]

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A bis (1,1,3,3-tetramethylbutyl) phosphinic acid compound represented by the formula (X ¹ and X ² are as defined above), for example, bis- (1,1,3,3- Tetramethylbutyl) phosphinic acid, bis- (1,1,3,3-
Tetramethylbutyl) monothiophosphinic acid, bis-
(1,1,3,3-tetramethylbutyl) dithiophosphinic acid and the like.

[0015] Other valuable metal extractants include:
Phosphorus-containing compounds, for example, di- (2-ethylhexyl) phosphoric acid, di- (n-butyl) phosphoric acid, di- (n-propyl) phosphoric acid, di- (n-amyl) phosphoric acid, di- (2 -Ethylbutyl) phosphoric acid, di- (2-ethyldecyl) phosphoric acid, di- (2-ethyldodecyl) phosphoric acid, bis- (2,
Phosphate esters such as (4,4, -trimethylpentyl) phosphoric acid, 2-ethylhexylphosphonic acid-mono-2-ethylhexyl ester, 1-methylheptylphosphonic acid-mono-1-methylheptyl ester, 1-methylheptylphosphonic acid -Phosphonic acid esters such as mono-2-ethylhexyl ester, di- (2,4,4-trimethylpentyl) phosphinic acid, di- (2-ethylhexyl) phosphinic acid, di- (n-octyl) phosphinic acid, di- (2
-Methyl-5-hexenyl) phosphinic acid, di- (p-
Methylcyclohexyl) phosphinic acid, di- (cyclohexyl) phosphinic acid, diphenylphosphinic acid, di-
(P-ethylphenyl) phosphinic acid, di- (p-methylphenyl) phosphinic acid, di- (2-methyl-5-hexenyl) phosphinic acid, di- (2-methyl-5-hexenyl) phosphinic acid, di- And phosphinic acids such as (2-methyl-5-hexenyl) phosphinic acid.
In addition, as the carboxylic acid compounds, Versatic 9, Versa
tic 911, naphthenic acid and the like. As the alkylsulfonic acid compound, 5,8-dinonylnaphthyl sulfate,
Examples of the tertiary amine include tri-n-octylamine, tri-isooctylamine, tri-n-decylamine, tri-isodecylamine, tri-dodecylamine,
Tri-tridecylamine, N-decyl-N-octyl-
Dodecylamine and the like.

As the chelate compound, 2-hydroxy
-5-dodecylbenzophenone oxime, 2-hydroxy-5-nonylbenzophenone oxime, 2-hydroxy-3-chloro-5-nonylbenzophenone oxime,
5-dodecylsalicylaldoxime, 2-hydroxy
-5-nonylbenzylphenone oxime, 5-nonyl-
Salicylaldoxime, 2-hydroxy-5-nonylacetophenone oxime and the like.

The method of recovering valuable metals, which is a feature of the present invention, is characterized in that (1) a mineral acid or a mixture of a mineral acid and hydrogen peroxide is added to a positive electrode active material for a lithium ion secondary battery, and then an eluate is added. (2) Then, the separated eluate is
A second step in which an extraction and separation treatment is carried out by contacting an organic solvent containing a metal extractant, (3) and then an extract organic solvent phase,
A third step of back extraction and separation by further contacting with a mineral acid.

Further, if other valuable metals still remain in the raffinate (aqueous solution phase) in the second step of the above (2), the conditions are suitable for extracting the remaining valuable metals.
A step (2 ′) of performing extraction and separation treatment by further contacting an organic solvent containing a metal extractant, and then a step (3 ′) of back extraction and separation by further contacting a mineral acid with the organic solvent phase of the extract. In this method, different kinds of valuable metals are separately collected.

In the first step, it is important to first dissolve the positive electrode active material with a mineral acid or a mixture of a mineral acid and hydrogen peroxide. The mineral acids used are hydrochloric acid, sulfuric acid, nitric acid,
Hydrofluoric acid is not particularly limited as long as it is industrially available. When Co and Ni are present as elements contained in the positive electrode active material for a lithium ion secondary battery, any of the compounds cannot be dissolved only with a mineral acid, and the mineral acid and hydrogen peroxide cannot be dissolved. It cannot be completely dissolved unless it is a mixed aqueous solution of this is,
Co and Ni by reducing power of hydrogen peroxide in the presence of acid
Is considered to be dissolved in the acidic solution by reducing the oxidation number of the compound from trivalent to divalent. On the other hand, L
Lithium manganate such as iMn ₂ O ₄ can be dissolved only with a mineral acid, but those containing a part of Co or Ni require the addition of hydrogen peroxide as well.

The reaction / dissolution temperature of such a positive electrode active material and a mineral acid or a mixture of a mineral acid and hydrogen peroxide is not particularly limited, but is usually 0 to 100 ° C, preferably 25 to 60 ° C.
° C, and the reaction / dissolution time is usually 5 minutes to 10 hours, preferably 0.5 to 2 hours. The molar ratio of the valuable metal, mineral acid and hydrogen peroxide in the positive electrode active material at the time of reaction and dissolution is 1: 1: 1-1: 5: 5, preferably 1: 1: 1-1: 1, respectively. 2: 2. The amount of hydrogen peroxide used is preferably as large as the amount of hydrogen peroxide used in order to completely dissolve the positive electrode active material. Need to be minimized.

When hydrogen peroxide remains, divalent cobalt ions are easily oxidized to trivalent. The trivalent cobalt ion oxidizes the extractant and the diluent due to its strong oxidizing power, and in particular, the hydrocarbon-based diluent is oxidized to partly carboxylic acid during long-term use. It is preferable to remove residual hydrogen peroxide as much as possible, since this may cause problems such as phase separation and a decrease in selectivity.
Therefore, when hydrogen peroxide is used, a 10- to 1000-fold, preferably 10- to 100-fold, molar amount of a reducing agent is added to decompose the hydrogen peroxide remaining in the solution. The reducing agent to be used is, for example, ascorbic acid, sodium hypophosphite, sodium hydrogen sulfite and the like, and is not particularly limited as long as it is industrially available. The reaction temperature at this time is usually 0 to 100 ° C, preferably 25 to 60 ° C, and the reaction time is usually 5 minutes to 10 hours, preferably 0.5 to 2 hours.

Next, in the second step, the separated eluate is brought into contact with an organic solvent containing such a metal extractant to perform an extraction separation treatment. As the metal extractant, the extractants listed above can be used, but Co and Ni are contained in the solution.
Can be easily separated and recovered by adjusting the pH of the solution with bis- (1,1,3,3-tetramethylbutyl) phosphinic acid. The phosphinic acid compound may be selected without limitation.

The organic solvent for the extractant is not particularly limited, but is usually used, for example, aromatics such as toluene, xylene and benzene, aliphatics such as hexane, heptane, octane, kerosene and n-paraffin. Unnecessary organic solvents for the water used can be used. These organic solvents may be used alone or in combination of two or more. The mixing ratio (weight) of the extractant and the diluent is 1:99 to 99:
1, preferably 5:95 to 50:50. The volume ratio between the acid-treated solution and the extraction solvent at the time of extraction is not particularly limited, but is usually 20: 1 to 1:20, preferably 5: 1 to 1: 5. The extraction temperature is between 10 and
100 ° C, preferably 20-70 ° C. The extraction time is 5 minutes to 2 hours, preferably 30 minutes to 1 hour.

In the above solvent extraction, additives such as higher alcohols and neutral phosphates may be added to the extraction system in order to improve the phase separation. As higher alcohols, for example, isodecanol, 1-octanol,
2-octanol, 2-ethyl-1hexanol, 1-
Nonanol, 1-undecanol, 1-dodecanol,
Cyclopentanol, cyclohexanol and the like can be mentioned.

Examples of the neutral phosphate include tributyl phosphate, dibutyl butylphosphonate, dibutyl phosphine dibutyl ester, tricresyl phosphate, tributyl phosphine oxide, and trioctyl phosphine oxide. The use amount of the above additives is 1 to 50% by volume, preferably 2 to 20% by volume, based on the extraction solvent.

Then, as a third step, an aqueous solution of a mineral acid is brought into contact with the organic solvent phase of the extract containing valuable metals to carry out back-extraction separation. The mineral acids used are hydrochloric acid, sulfuric acid, nitric acid and the like, and the mixing ratio (volume) with the organic phase is 20: 1 to 1:20,
Preferably 5: 1 to 1: 5, back extraction temperature is 10 to 100
° C, preferably 20-70 ° C. The extraction time is 5 minutes to 2 hours, preferably 0.5 to 1 hour. By this treatment, valuable metals are back-extracted into the aqueous phase, and valuable metals are recovered from the aqueous phase. The organic phase after back extraction is used again for extraction and can be used repeatedly. Since the recovered valuable metal is a high-purity product, it can be reused as a raw material for a lithium secondary battery.

The raffinate (aqueous phase) after the extraction is a high-purity lithium solution, and can be separated and purified by a known method such as adding sodium carbonate and / or sodium hydrogen carbonate. The extraction method is usually performed by contact-mixing an organic solvent containing an extractant with an aqueous solution containing a valuable metal, and selectively extracting a desired valuable metal from the aqueous solution to an organic solvent phase. It is industrially preferable that the contact method is a continuous multi-stage treatment using an apparatus such as a mixer-settler.

[0028]

The present invention will be further described with reference to the following examples. Example 1 In a 300 mL four-necked flask equipped with a stirrer, a thermometer, a dropping funnel, and a condenser, LiC obtained from a nonstandard product of a positive electrode active material for a lithium ion secondary battery was added.
6.50 g (66.3 mmol) of oO ₂ , 16N sulfuric acid 1
0 ml and 85 ml of pure water were put thereinto, and 5.0 g of 35% hydrogen peroxide solution was added dropwise at room temperature. After the dropwise addition, the mixture was reacted and eluted at 100 ° C. for 1 hour. After the eluate was cooled to room temperature, uneluted lithium cobaltate was separated by filtration. From the weight of the residual lithium cobaltate, it was found that 90% of the lithium cobaltate was dissolved in the eluate. The eluate was titrated with a 1 / 10N aqueous solution of potassium permanganate. As a result, 100 ppm of hydrogen peroxide remained. Therefore, 90.6 mg of ascorbic acid (0.515) was added to the aqueous solution.
mmol) was added to reduce the remaining hydrogen peroxide.
In a 300 mL Erlenmeyer flask, an O / A volume ratio of the aqueous solution after the above-mentioned reduction treatment and an n-hexane solution containing 14.5% by weight of bis (1,1,3,3-tetramethylbutyl) phosphinic acid as an extraction solvent was added. After mixing at 1: 1 and adjusting the pH to 5.4 with 28% aqueous ammonia, and contacting at room temperature for 1 hour,
The organic phase and the aqueous phase were transferred to a separating funnel, allowed to stand for 30 minutes, and separated. The organic phase and a 1N aqueous sulfuric acid solution are mixed in a 300 mL Erlenmeyer flask at an O / A volume ratio of 1: 1. The mixture is brought into contact at room temperature for 1 hour to perform reverse extraction. After allowing to stand for 30 minutes, the organic phase and the aqueous phase are separated. did. The cobalt ion concentration in the aqueous phase after extraction and the aqueous phase after back-extraction were measured by ICP analysis and lithium ion concentration by atomic absorption analysis. Table 1 shows the results.

(Example 2) 5.00 g (51.0 mmol) of LiNi _0.8 Co _0.2 O ₂ was placed in a 300 mL four-necked flask equipped with a stirrer, a thermometer, a dropping funnel, and a condenser.
l), 10 ml of 16N sulfuric acid and 85 ml of pure water were put thereinto, and 5.0 g of 35% hydrogen peroxide solution was added dropwise at room temperature. After the addition, the mixture was reacted and eluted at 100 ° C. for 1 hour, and the eluate was cooled to room temperature. The eluate was titrated with a 1 / 10N aqueous solution of potassium permanganate to find that 4.23% of hydrogen peroxide remained. Therefore, ascorbic acid 38.
3 g (218 mmol) were added to reduce the remaining hydrogen peroxide (first step). An aqueous solution after the reduction treatment and an n-hexane solution containing 14.5% by weight of bis (1,1,3,3-tetramethylbutyl) phosphinic acid as an extraction solvent are mixed at an O / A volume ratio of 1: 1. Mix and contact pH
Was adjusted to 5.3 to extract cobalt (second step). The organic phase is mixed with a 1N sulfuric acid aqueous solution at an O / A volume ratio of 1: 1 and brought into contact at room temperature for 1 hour to perform back extraction. After allowing to stand for 30 minutes, the organic phase and the aqueous phase are separated, and cobalt is separated. Collected (third step).

Further, the raffinate (aqueous phase) after extraction of cobalt in the second step containing nickel and bis (1,1,3,3-tetramethylbutyl) phosphinic acid as an extraction solvent were added at 14.5 weight%. % N-hexane solution and O
/ A mixed at a volume ratio of 1: 1 and p with 28% aqueous ammonia
H was adjusted to 8.5, and after contacting at room temperature for 1 hour, the organic phase and the aqueous phase were transferred to a separating funnel, allowed to stand for 30 minutes, and separated (2 ′ step). The organic phase is mixed with a 1N aqueous solution of sulfuric acid at an O / A volume ratio of 1: 1 and brought into contact at room temperature for 1 hour to perform back extraction. After allowing to stand for 30 minutes, the organic phase and the aqueous phase are separated, and after the cobalt extraction. Nickel was separated and recovered from the raffinate (3 ′ step). Table 1 shows the results.

Example 3 5.00 g (39.7 mmol) of LiMn ₂ O ₄ was placed in a 300 mL four-necked flask equipped with a stirrer, thermometer, dropping funnel and condenser.
Add 6 ml of 6N sulfuric acid and 85 ml of pure water,
The reaction was allowed to proceed for an hour, and the reaction solution was cooled to room temperature. The aqueous solution after the treatment and n containing 14.5% by weight of bis (1,1,3,3-tetramethylbutyl) phosphinic acid as an extraction solvent
-Hexane solution was mixed at an O / A volume ratio of 1: 1 to adjust the contact pH to 8.09, and the same operation as in Example 1 was performed. Table 1 shows the results.

Example 4 The procedure of Example 1 was repeated except that the contact pH was adjusted to 0.8 using a 20.5% by weight xylene solution of tri-isooctylamine as the extraction solvent. Table 1 shows the results.

Example 5 The contact pH was adjusted to 6.1 using a kerosene solution of 20.0% by weight of 5,8-diethyl-7-hydroxy-6-dodecanone oxime as an extraction solvent. Was performed in the same manner as in Example 1. Table 1 shows the results.

Example 6 Using a 11.7% by weight solution of naphthenic acid in kerosene as an extraction solvent, the pH of the contact was adjusted to 8.
The procedure was performed in the same manner as in Example 1 except that the value was adjusted to 4. Table 1 shows the results.

Example 7 The procedure of Example 1 was repeated except that the pH of the contact was adjusted to 6.5 using a 16.1% by weight solution of di- (2-ethylhexyl) phosphoric acid in kerosene as the extraction solvent. went. Table 1 shows the results.

[0036]

[Table 1]

[0037]

[Table 2]

[0038]

As can be seen from Table 1, according to the extraction method of the present invention, valuable metals such as cobalt and nickel can be recovered from the positive electrode active material for a lithium ion secondary battery at an extremely high extraction rate. it can.

Claims (5)

[Claims] 1. A first step in which a mineral acid or a mixture of a mineral acid and hydrogen peroxide is added to a positive electrode active material for a lithium ion secondary battery, followed by separation of an eluate, and then metal extraction into the separated eluate A second step of performing extraction and separation treatment by contacting an organic solvent containing the agent, and then a third step of back extraction and separation by contacting a mineral acid with the organic solvent phase of the extract,
A method for recovering valuable metals from a positive electrode active material for a lithium ion secondary battery. 2. A step of subjecting the raffinate (aqueous phase) passed through the second step to an organic solvent containing a metal extractant to carry out extraction separation treatment, and then contacting a mineral acid with the organic solvent phase of the extract. The method for recovering valuable metals from a positive electrode active material for a lithium ion secondary battery according to claim 1, wherein different valuable metals are separately recovered by performing a step of back extraction and separation. 3. The lithium ion according to claim 1, wherein hydrogen peroxide remaining in the elution solution separated in the first step is decomposed with a reducing agent and then subjected to the second step. A method for recovering valuable metals from a positive electrode active material for a secondary battery. 4. The metal extractant has the following general formula (1): (Wherein X ¹ and X ^{2 each} represent an oxygen atom or a sulfur atom, provided that X ¹ and X ² may be the same or different) (1,1,3) The method for recovering valuable metals from a positive electrode active material for a lithium ion secondary battery according to any one of claims 1 to 3, wherein the method is a (3,3-tetramethylbutyl) phosphinic acid compound. 5. The molar ratio of a valuable metal, a mineral acid, and hydrogen peroxide in a positive electrode active material for a lithium ion secondary battery is in the range of 1: 1: 1-1: 5: 5, respectively. 5. The method for recovering valuable metals from a positive electrode active material for a lithium ion secondary battery according to any one of items 1 to 4.