Method for recovering aqueous manganese compound solution

Abstract

To provide a method for collecting the aqueous solution of a calcium content-reduced manganese compound from a valuable metal solution which is obtained by dissolving in an acid solution, the valuable metals being included in battery powders obtained from waste lithium-ion battery.SOLUTION: A collection method for an aqueous solution of manganese compounds is characterized by comprising processes of: dissolving valuable metals included in battery powders 2 obtained from waste lithium-ion battery in a first acid solution to obtain a valuable metal solution 3 including manganese at 10 g / L or more and calcium as an impurity; performing a first solvent extraction from the valuable metal solution 3 using D2EHPA as an extraction solvent; performing a second solvent extraction from the extraction residual liquid 5 of the first solvent extraction using D2EHPA as the extraction solvent; and carrying out a back extraction from an extract 6 obtained by the second solvent extraction using a second acid solution as the extraction solvent to collect an aqueous solution 10 of manganese compounds as a reverse extraction liquid.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for recovering an aqueous manganese compound solution. [Background technology]

[0002] In recent years, with the widespread use of lithium ion batteries, various methods have been proposed 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 lithium ion batteries, etc. In this application, 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 in the manufacturing process, and residual positive electrode materials used in the manufacturing process for commercialization.

[0003] Conventionally, as a method for recovering valuable metals from used lithium-ion batteries, there has been known a method in which the valuable metals contained in a powder obtained by roasting used lithium-ion batteries and then pulverizing them, or by roasting them after pulverization, etc. (hereinafter referred to as battery powder) are dissolved in an acid solution to obtain a valuable metal solution, and the valuable metals are extracted and recovered by solvent extraction from the valuable metal solution (see, for example, Patent Document 1).

[0004] In addition, bis(2-ethylhexyl) hydrogen phosphate (hereinafter sometimes abbreviated as D2EHPA) is known as an extractant for extracting manganese as the valuable metal from a battery powder solution (see, for example, Non-Patent Document 1).

[0005] The manganese as the valuable metal is, for example, extracted from the valuable metal solution using D2EHPA as an extraction solvent, the resulting extract is stripped with sulfuric acid, and the stripped liquid is crystallized to recover a manganese compound such as manganese sulfate monohydrate, which is then reused as a raw material for lithium manganate, the positive electrode active material. In this case, the manganese compound such as manganese sulfate monohydrate is required to have a calcium content of, for example, less than 50 mg / kg in order to reuse it as a raw material for the positive electrode active material. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 6714226 [Non-patent literature]

[0007] [Non-Patent Document 1] Manuel Aguilar, Jose Luis Cortina, “Solvent Extraction and Liquid Membranes - Fundamentals and Applications in New Materials”, (US), 2008.11, pp.159 Summary of the Invention [Problem to be solved by the invention]

[0008] However, the battery powder contains calcium that is thought to originate from the aluminum used in the casing or current collector (electrode foil) of the lithium-ion battery. On the other hand, according to Non-Patent Document 1, D2EHPA tends to co-extract manganese and calcium.

[0009] As a result, the manganese sulfate aqueous solution (stripping solution) obtained by extracting manganese from the valuable metal solution using D2EHPA as an extraction solvent and stripping the resulting extract with sulfuric acid contains 50 mg / kg or more of calcium relative to the manganese sulfate. Therefore, the manganese sulfate monohydrate obtained by crystallization of the manganese sulfate aqueous solution has a calcium content of 50 mg / kg or more, which is disadvantageous in that it is difficult to reuse it as a raw material for lithium manganate for the positive electrode active material of lithium ion batteries.

[0010] The present invention aims to eliminate such inconveniences and provide a method for recovering an aqueous manganese compound solution having a reduced calcium content from a valuable metal solution obtained by dissolving valuable metals contained in battery powder obtained from waste lithium ion batteries in an acid solution. [Means for solving the problem]

[0011] In order to achieve this object, the method for recovering a manganese compound aqueous solution of the present invention is a method for recovering a manganese compound aqueous solution from battery powder containing valuable metals obtained from waste lithium-ion batteries, comprising the steps of dissolving the battery powder in a first acid solution to obtain a valuable metal solution containing 10 g / L or more of manganese and calcium as an impurity, and extracting manganese from the valuable metal solution using bis(2-ethylhexyl) hydrogen phosphate as an extraction solvent. , at a pH in the range of 1-2 A step of performing a first solvent extraction, and extracting the valuable metal from the extraction residue after performing the first solvent extraction from the valuable metal solution using bis(2-ethylhexyl) hydrogen phosphate as an extraction solvent. , at a pH in the range of 1.4 to 3 The method comprises the steps of: performing a second solvent extraction; and performing stripping from the extract obtained by the second solvent extraction using a second acid solution as an extraction solvent, and recovering an aqueous manganese compound solution as a stripped solution.

[0012] The method for recovering a manganese compound aqueous solution of the present invention first involves dissolving battery powder containing valuable metals obtained from waste lithium-ion batteries in a first acid solution to obtain a valuable metal solution containing 10 g / L or more of manganese and calcium as an impurity.

[0013] Next, a first solvent extraction is carried out from the valuable metal solution using D2EHPA as an extraction solvent. At this time, since D2EHPA co-extracts manganese and calcium, the valuable metal solution contains 10 g / L or more of manganese, so that substantially all of the calcium as an impurity can be extracted into the organic phase, and a valuable metal solution substantially free of calcium can be obtained as an extraction residue after the first solvent extraction is carried out from the valuable metal solution.

[0014] Then, by carrying out a second solvent extraction from the residual liquid using D2EHPA as an extraction solvent, it is possible to extract substantially only manganese into the organic phase and obtain an extract substantially free of calcium.Then, by carrying out stripping from the extract obtained by the second solvent extraction using a second acid solution as an extraction solvent, it is possible to recover, as a stripping liquid, an aqueous solution of manganese compounds as acid salts contained in the second acid solution and substantially free of calcium.

[0015] In the method for recovering an aqueous manganese compound solution of the present invention, the first acid solution can be at least one acid solution selected from the group consisting of hydrochloric acid, sulfuric acid, and nitric acid, and the second acid solution can be one acid solution selected from the group consisting of hydrochloric acid, sulfuric acid, and nitric acid.

[0016] In the method for recovering a manganese compound aqueous solution of the present invention, the first solvent extraction is carried out at a pH in the range of 1 to 2. stomach The second solvent extraction is carried out at a pH in the range of 1.4 to 3. stomach Preferably, said back extraction is carried out at a pH in the range below 1.

[0017] In the method for recovering an aqueous manganese compound solution of the present invention, the extract obtained by the second solvent extraction is substantially free of calcium, but may contain small amounts of valuable metals other than the manganese contained in the battery powder. Therefore, in the method for recovering an aqueous manganese compound solution of the present invention, it is preferable to scrub the extract obtained by the second solvent extraction with a third acid solution prior to the stripping. By carrying out the scrubbing, valuable metals other than manganese can be removed from the extract obtained by the second solvent extraction, and then by carrying out the stripping, an aqueous manganese compound solution of even higher purity can be obtained as the stripping solution.

[0018] In the method for recovering an aqueous manganese compound solution of the present invention, the third acid solution used in the scrubbing can be one acid solution selected from the group consisting of hydrochloric acid, sulfuric acid, and nitric acid. In the method for recovering an aqueous manganese compound solution of the present invention, the scrubbing is preferably carried out at a pH in the range of 2 to 4. [Brief description of the drawings]

[0019] [Figure 1] 1 is a flow chart showing an example of the steps of the method for recovering an aqueous manganese compound solution of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Next, embodiments of the present invention will be described in more detail with reference to the accompanying drawings.

[0021] 1, in the method for recovering an aqueous manganese compound solution of this embodiment, first, raw material 1 is pretreated in STEP 1 to obtain battery powder 2. Examples of raw material 1 include used, discarded lithium ion batteries that have reached the end of their life as battery products, discarded lithium ion batteries discarded due to manufacturing defects or the like, and residual positive electrode materials used in the manufacturing process of lithium ion batteries.

[0022] Specifically, the pretreatment in STEP 1 can be carried out, for example, by discharging the waste lithium ion batteries in salt water, heating and roasting the waste lithium ion batteries and raw material 1 such as the positive electrode material in an electric furnace at a temperature in the range of 200 to 500°C for 1 to 60 minutes, pulverizing the waste lithium ion batteries using a pulverizing device such as a jaw crusher or a hammer mill, and separating the casings, current collectors (electrode foils), and the like of the waste lithium ion batteries using a sieve with mesh openings of 0.1 to 50 mm.

[0023] The battery powder 2 obtained as a result of the pretreatment is mainly a powder of a positive electrode active material, and contains valuable metals such as Mn, Ni, Co, etc. derived from the positive electrode active material, and calcium as an impurity. The calcium is derived from, for example, aluminum used in the casing or current collector (electrode foil) of the waste lithium ion battery, and is mixed into the battery powder 2.

[0024] Next, in STEP 2, a first acid solution is added to the battery powder 2 to dissolve the battery powder 2 in acid. At least one acid solution selected from the group consisting of hydrochloric acid, sulfuric acid, and nitric acid can be used as the first acid solution, and as a result of the acid dissolution, a valuable metal solution 3 containing 10 g / L or more of manganese (Mn) and calcium (Ca) as an impurity can be obtained.

[0025] Next, in STEP 3, bis(2-ethylhexyl) hydrogen phosphate (hereinafter sometimes abbreviated as D2EHPA) is added as an extraction solvent to the valuable metal solution 3, and a first solvent extraction using D2EHPA is carried out. The D2EHPA may be used after dilution with kerosene or the like. As a result of the first solvent extraction, a first extraction liquid 4 can be obtained in the organic phase, and a first extraction residue 5 can be obtained in the aqueous phase.

[0026] Since the D2EHPA co-extracts Mn and Ca, the first solvent extraction is preferably carried out at a pH of 1 to 2 for the valuable metal solution 3 containing 10 g / L or more of Mn and Ca as an impurity, so that substantially all of the Ca contained in the valuable metal solution 3 is extracted into the organic phase. The first solvent extraction is more preferably carried out at a pH of 1 to 1.6, even more preferably at a pH of 1.2 to 1.6, and most preferably at a pH of 1.3 to 1.5.

[0027] As a result, the first extraction liquid 4 contains substantially all of the Ca contained in the valuable metal solution 3 and only a trace amount of Mn, while the first extraction residue 5 contains valuable metals such as Mn, Ni, Co, etc., but does not substantially contain Ca.

[0028] Next, a second solvent extraction with D2EHPA is carried out in STEP 4 by adding D2EHPA as an extraction solvent to the first extraction residue 5. As a result of the second solvent extraction, a second extraction liquid 6 can be obtained in the organic phase, and a second extraction residue 7 can be obtained in the aqueous phase.

[0029] Since the first extractant 5 is substantially free of Ca, the second solvent extraction is preferably carried out at a pH range of 1.4 to 3 with respect to the first extractant 5, whereby substantially all of the Mn contained in the first extractant 5 is extracted into the organic phase. The second solvent extraction is more preferably carried out at a pH range of 1.4 to 2.5, even more preferably at a pH range of 1.4 to 2.0, and most preferably at a pH range of 1.4 to 1.8.

[0030] As a result, the second extraction liquid 6 contains substantially all of the Mn contained in the first extraction residue 5, as well as trace amounts of Ni and Co, but contains substantially no Ca. The second extraction residue 7 contains valuable metals such as Ni and Co, but contains substantially no Mn.

[0031] Next, in STEP 5, scrubbing with the third acid solution is performed by adding a third acid solution to the second extract 6. As the third acid solution, one acid solution selected from the group consisting of hydrochloric acid, sulfuric acid, and nitric acid can be used. As a result of the scrubbing, a scrubbing extract 8 can be obtained in the aqueous phase, and a scrubbing residual liquid 9 can be obtained in the organic phase.

[0032] Since the second extract solution 6 contains trace amounts of Ni and Co, the scrubbing is preferably performed at a pH range of 2 to 4 on the second extract solution 6, whereby substantially all of the Ni and Co contained in the second extract solution 6 is extracted into the aqueous phase.

[0033] As a result, the scrubbing extract 8 contains substantially all of the Ni and Co contained in the second extract 6, and the scrubbing bottoms 9 contains substantially only Mn.

[0034] Next, in STEP 6, a second acid solution is added to the scrubbing residual liquid 9 to perform stripping with the second acid solution. The second acid solution may be one acid solution selected from the group consisting of hydrochloric acid, sulfuric acid, and nitric acid. As a result of the stripping, an aqueous manganese compound solution 10 can be obtained as a stripping liquid in the aqueous phase, and a stripping residual liquid 11 can be obtained in the organic phase.

[0035] The back extraction is carried out on the scrubbing residual liquid 9 at a pH range preferably of less than 1, whereby substantially all of the Mn contained in the scrubbing residual liquid 9 reacts with the second acid solution, and manganese compounds are extracted into the aqueous phase as salts of Mn and an acid contained in the acid solution used as the second acid solution.

[0036] As a result, an aqueous manganese compound solution 10 can be obtained as the stripping liquid. On the other hand, the stripping residue 11 is a result of substantially all of the Mn being extracted from the scrubbing residue 9, and consists only of D2EHPA, which is the extraction solvent in the second solvent extraction.

[0037] The Mn compound contained in the Mn compound aqueous solution 10 is, for example, manganese chloride when the acid solution used as the second acid solution is hydrochloric acid, manganese sulfate when the acid solution is sulfuric acid, and manganese nitrate when the acid solution is nitric acid.

[0038] The Mn compound aqueous solution 10 recovered in this embodiment can be used for producing a manganese compound such as lithium manganate in the form of itself, in the form of a concentrated solution, or in the form of crystals such as a monohydrate or pentahydrate after crystallization.

[0039] In this embodiment, the second extract 6 is scrubbed in STEP 5. However, scrubbing need not be performed. In this case, the second extract 6 is subjected to back extraction in STEP 6.

[0040] In addition, since the first extraction liquid 4 contains a trace amount of Mn, after removing Ca, it can be returned to the first solvent extraction in STEP 3. In addition, the second extraction residue 7 can be supplied to a Co, Ni extraction step to separately extract Co and Ni, and the scrubbing extraction liquid 8 can be added to the second extraction residue 7.

[0041] Furthermore, the stripping residue 11 can be purified, if necessary, and then reused as an extraction solvent in the first solvent extraction or the second solvent extraction.

[0042] Next, examples of the present invention and comparative examples will be described. EXAMPLES

[0043] Example 1 In this example, first, 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 under 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).

[0044] Next, 10 kg of the positive electrode powder was dissolved in 7.8 mol / L hydrochloric acid to obtain 80 L of valuable metal solution. -2 The aqueous solution contained 100 g / L Ca, 19 g / L Co, 6.9 g / L Li, 25 g / L Mn, and 14 g / L Ni.

[0045] Next, 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 valuable metal solution, and the equilibrium pH was adjusted to 1.4, followed by a first solvent extraction to obtain 75 L of extraction residue substantially free of Ca. The pH was adjusted using a 20% by mass aqueous sodium hydroxide solution. The extraction residue had a pH of 1.0×10 -3 The aqueous solution contained 100 g / L Ca, 17 g / L Co, 6.5 g / L Li, 15 g / L Mn, and 13 g / L Ni.

[0046] Next, 50 L of 1 mol / L bis(2-ethylhexyl) hydrogen phosphate (manufactured by Nacalai Tesque, Inc.) diluted with kerosene was added to 50 L of the extraction residue, and the equilibrium pH was adjusted to 1.8, followed by a second solvent extraction to obtain 50 L of extract. The pH was adjusted using a 20% by mass aqueous sodium hydroxide solution.

[0047] Next, 50 L of 0.02 mol / L sulfuric acid was added to 50 L of the extract, the equilibrium pH was adjusted to 2.6, and scrubbing was performed to obtain 50 L of scrubbing residual liquid. The pH was adjusted using 0.02 mol / L sulfuric acid.

[0048] Next, 6 L of 2.5 mol / L sulfuric acid was added to 50 L of the scrubbing residual liquid to carry out back extraction, thereby obtaining 6 L of an aqueous manganese sulfate solution as a back extraction liquid.

[0049] The manganese sulfate aqueous solution contained 0.007 g / L of Ca and 40 g / L of Mn, and it was expected that manganese sulfate monohydrate obtained by crystallization of the manganese sulfate aqueous solution would contain less than 50 mg / kg of Ca. [Explanation of symbols]

[0050] 1...raw material, 2...battery powder, 3...valuable metal solution, 5...extraction residue, 6...extract, 10...manganese compound aqueous solution.

Claims

1. A method for recovering an aqueous manganese compound solution from battery powder obtained from waste lithium ion batteries, comprising the steps of: a step of dissolving the valuable metals contained in the battery powder in a first acid solution to obtain a valuable metal solution containing 10 g / L or more of manganese and calcium as an impurity; carrying out a first solvent extraction from the valuable metal solution using bis(2-ethylhexyl) hydrogen phosphate as an extraction solvent at a pH in the range of 1 to 2; carrying out a second solvent extraction from the residual liquid after carrying out the first solvent extraction from the valuable metal solution, using bis(2-ethylhexyl) hydrogen phosphate as an extraction solvent at a pH in the range of 1.4 to 3; A method for recovering an aqueous manganese compound solution, comprising the steps of: stripping the extract obtained in the second solvent extraction using a second acid solution as an extraction solvent to obtain an aqueous manganese compound solution as a stripped solution.

2. 2. The method for recovering an aqueous manganese compound solution according to claim 1, wherein the first acid solution is at least one acid solution selected from the group consisting of hydrochloric acid, sulfuric acid, and nitric acid.

3. 3. The method for recovering an aqueous manganese compound solution according to claim 1, wherein the second acid solution is one acid solution selected from the group consisting of hydrochloric acid, sulfuric acid, and nitric acid.

4. 4. The method for recovering an aqueous manganese compound solution according to claim 1, wherein the stripping is carried out at a pH in the range of less than 1.

5. The method for recovering an aqueous manganese compound solution according to any one of claims 1 to 4, characterized in that the extract obtained in the second solvent extraction is subjected to scrubbing with a third acid solution prior to the stripping.

6. 6. The method for recovering an aqueous manganese compound solution according to claim 5, wherein the third acid solution is one acid solution selected from the group consisting of hydrochloric acid, sulfuric acid and nitric acid.

7. 7. The method for recovering an aqueous manganese compound solution according to claim 5 or 6, wherein the scrubbing is carried out at a pH in the range of 2 to 4.

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