Aluminum extraction method

Abstract

The present invention addresses the problem of providing a method for extracting aluminum from an acid solution without causing precipitation of aluminum. The aluminum extraction method according to the present invention comprises: an aluminum extraction step in which an acid solution containing aluminum is mixed with an organic solvent containing mono-2-ethylhexyl 2-ethylhexyl phosphonate, and aluminum is extracted from the acid solution under conditions in which the equilibrium pH is less than 1.8. When the acid solution further contains fluorine, the aluminum extraction method according to the present invention comprises a fluorine separation and removal step for generating aluminum hydroxide by adjusting the aluminum concentration in the raffinate to an arbitrary range and adjusting the equilibrium pH to 2-7, thereby coprecipitating fluorine and performing solid-liquid separation.

Description

[Technical field]

[0001] The invention relates to an aluminum extraction method. [Background Technology]

[0002] In recent years, as lithium-ion batteries have become more common, research has been conducted on methods for recovering valuable metals such as cobalt, nickel, manganese, and lithium from waste lithium-ion batteries and reusing them as materials for the lithium-ion batteries.

[0003] In the past, when the above-mentioned valuable metals were recovered from the above-mentioned waste lithium-ion batteries, cobalt, nickel, manganese and lithium were separated and refined from the powder containing the above-mentioned valuable metals (hereinafter referred to as active material powder) through a wet process. The above-mentioned powder was obtained by heating (roasting) the waste lithium-ion batteries or by crushing and classifying them without heating treatment.

[0004] In addition, in the present application, waste lithium-ion batteries refer to used lithium-ion batteries whose lifespan as battery products has been exhausted, lithium-ion batteries discarded as defective products in the manufacturing process, positive and negative electrode materials remaining after being used for productization in the manufacturing process, etc. In addition, the active material powder may sometimes contain fluorine ions generated by the decomposition of the electrolyte and the binder during the treatment of the waste lithium-ion batteries.

[0005] When aluminum of the positive electrode material is contained as an impurity in the active material powder, the aluminum is leached out by acid leaching, and it is necessary to separate the aluminum from the acid solution.

[0006] As a method for separating aluminum, there is a method of separating aluminum in the form of hydroxide by adjusting pH. However, this method has the following problem: when aluminum is precipitated, the recovery target metal is also co-precipitated, and the recovery rate of the recovery target metal is reduced.

[0007] Patent Document 1 discloses a solvent extraction method for aluminum, comprising an extraction step of extracting and separating aluminum using an organic solvent containing 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester under the condition of an equilibrium pH of 1.8 to 3.

[0008] [Prior art literature]

[0009] Patent Literature

[0010] Patent Document 1: Japanese Patent Application Publication No. 2012-211386 [Summary of the invention]

[0011] Problems to be solved by the invention

[0012] In the solvent extraction method of aluminum disclosed in Patent Document 1, lithium also begins to precipitate together with aluminum under the condition of pH>1.8. Specifically, in the solvent extraction tank, alkali is added when adjusting to this pH, but precipitation of aluminum hydroxide occurs locally in the tank. Since the aluminum hydroxide does not end to dissolve again within the retention time of the device, precise separation cannot be performed. In addition, the precipitation of aluminum also causes cobalt and nickel to coprecipitate, so the precipitation of aluminum reduces the recovery rate of lithium, cobalt and nickel respectively.

[0013] In recent years, there has been a demand for a method for extracting aluminum from the above-mentioned acid solution without causing aluminum precipitation. The problem to be solved by the present invention is to provide a method for extracting aluminum from the above-mentioned acid solution without causing aluminum precipitation.

[0014] Means for solving problems

[0015] The present inventors have repeatedly conducted research in view of the above-mentioned problems and have found that when an acid solution containing aluminum and an organic solvent containing 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester are mixed and aluminum is extracted from the acid solution under the condition that the equilibrium pH is less than 1.8, aluminum can be extracted from the acid solution without precipitation of aluminum. The present invention has been completed based on these findings.

[0016] The invention relates to an aluminum extraction method, which comprises: an aluminum extraction step, mixing an acid solution containing aluminum and an organic solvent containing 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester, and extracting aluminum from the acid solution under the condition that the equilibrium pH is less than 1.8.

[0017] When the acid solution also contains fluorine, the aluminum extraction method includes: a fluorine separation and removal step, adjusting the aluminum concentration in the raffinate obtained in the aluminum extraction step to an arbitrary range, and adjusting the equilibrium pH to 2 to 7 to generate aluminum hydroxide, thereby co-precipitating fluorine, and performing solid-liquid separation.

[0018] Preferably, the aluminum concentration in the raffinate is 0.1 to 30 g / L.

[0019] Preferably, the aluminum extraction method further comprises: an acid dissolution step of dissolving the active material powder obtained from the waste lithium-ion battery in an inorganic acid to obtain the acid solution.

[0020] Preferably, the inorganic acid includes at least one selected from the group consisting of hydrochloric acid, sulfuric acid and nitric acid, and more preferably includes hydrochloric acid.

[0021] Effects of the Invention

[0022] The present invention provides an aluminum extraction method capable of extracting aluminum from the above-mentioned acid solution without causing aluminum precipitation. [Specific implementation method]

[0023] Hereinafter, the present invention will be described in more detail.

[0024] In addition, unless otherwise specified, "-" in a numerical range means above to below, and both ends of the numerical value are included. In addition, when expressing a numerical range, the upper limit and the lower limit can be appropriately combined, and the numerical range obtained thereby is also disclosed.

[0025] <Acid solution>

[0026] The acid solution containing aluminum used in the aluminum extraction method of the present invention is a solution in which aluminum is dissolved in a solution containing an acid, and is not limited to a specific solution. The preferred acid solution is obtained by dissolving the active material powder obtained from a waste lithium-ion battery in an inorganic acid. The inorganic acid preferably includes at least one selected from the group consisting of hydrochloric acid, sulfuric acid and nitric acid, more preferably at least one selected from the group consisting of hydrochloric acid, sulfuric acid and nitric acid, further preferably hydrochloric acid, sulfuric acid or nitric acid, and particularly preferably hydrochloric acid. The active material powder contains valuable metals such as lithium, iron, aluminum, cobalt, nickel, and manganese. Therefore, by dissolving the active material powder using the inorganic acid, an acid solution containing the valuable metals represented by aluminum contained in the active material powder can be obtained. The acid solution may also contain fluorine.

[0027] If the same active material composition is used in the acid dissolution step, the concentration of the valuable metals other than aluminum in the acid dissolution solution becomes higher according to the liquid volume, and the recovery efficiency of the valuable metals from the acid dissolution solution is improved. At this time, the aluminum concentration in the acid dissolution solution also changes, for example, to 0.1 to 30 g / L. In addition, the fluorine concentration in the acid dissolution solution also changes, for example, to 0.1 to 30 g / L.

[0028] <Extraction Agent>

[0029] The extractant used in the aluminum extraction method of the present invention is an organic solvent containing 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester. The above-mentioned organic solvent dissolves 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester and is not limited to a specific organic compound. The above-mentioned organic solvent preferably contains a hydrocarbon, and more preferably a hydrocarbon. As the above-mentioned hydrocarbon, for example, a linear or branched saturated or unsaturated hydrocarbon, an aromatic hydrocarbon can be cited. As the above-mentioned hydrocarbon, kerosene can be exemplified.

[0030] The concentration of mono-2-ethylhexyl 2-ethylhexylphosphonate in the organic solvent is preferably 0.1 to 3.1 mol / L, more preferably 0.5 to 2 mol / L, and even more preferably 0.7 to 1.5 mol / L.

[0031] <Aluminum Extraction Process>

[0032] The aluminum extraction method of the present invention comprises: an aluminum extraction step, mixing the above-mentioned acid solution containing aluminum and the above-mentioned organic solvent containing 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester. The mixing ratio of the above-mentioned acid solution and the above-mentioned organic solvent is preferably the above-mentioned acid solution: the above-mentioned organic solvent = 1: 0.5 to 10, more preferably the above-mentioned acid solution: the above-mentioned organic solvent = 1: 1 to 5, and further preferably the above-mentioned acid solution: the above-mentioned organic solvent = 1: 2 to 4.

[0033] The equilibrium pH in the aluminum extraction step is less than 1.8. When the equilibrium pH is 1.8 or higher, aluminum may precipitate from the acid solution.

[0034] The aluminum concentration in the raffinate obtained by the aluminum extraction step can be made very low, but it can also be adjusted to any concentration. By adjusting the aluminum concentration according to the residual fluorine concentration, the dissolved fluorine concentration after the fluorine separation and removal step described later can be adjusted.

[0035] <Fluorine Separation and Removal Step>

[0036] In the case where the acid solution also contains fluorine, the aluminum extraction method of the present invention includes: a fluorine separation and removal step, wherein the aluminum concentration in the raffinate obtained in the aluminum extraction step is adjusted to an arbitrary range, and the equilibrium pH is adjusted to 2 to 7 to generate aluminum hydroxide, thereby co-precipitating fluorine, and performing solid-liquid separation. The generated aluminum hydroxide containing fluorine is subjected to solid-liquid separation. The equilibrium pH of the raffinate can be adjusted by adding a base to the raffinate. As the base, at least one selected from the group consisting of alkali metal hydroxides and ammonia can be used. At least one selected from the group consisting of a solid and an aqueous solution of the alkali is added to the raffinate.

[0037] The alkali metal of the alkali metal hydroxide includes at least one selected from the group consisting of lithium, sodium, potassium, rubidium, cesium and francium. The alkali metal preferably includes at least one selected from the group consisting of lithium, sodium and potassium, and more preferably lithium, sodium or potassium.

[0038] The raffinate after the aluminum extraction step or the treated solution obtained by further separation and removal of fluorine contains valuable metals such as lithium, cobalt, nickel, and manganese. Therefore, valuable metals other than lithium are extracted from these solutions, and lithium is recovered from the aqueous solution containing lithium obtained after the extraction.

[0039] Example

[0040] Hereinafter, the present invention will be described in more detail based on Examples, but the present invention is not limited thereto.

[0041] In Examples and Comparative Examples, various physical properties were measured or calculated as follows.

[0042] <Concentration of Valuable Metal Contained in Valuable Metal Salt Solution>

[0043] The concentration of the valuable metal contained in the valuable metal salt solution was measured by an inductively coupled plasma emission spectrometer (Optima-8300 manufactured by Perkin Elmer).

[0044] Example 1

[0045] The positive electrode material, that is, the positive electrode foil (formed by coating the positive electrode mixture containing the positive electrode active material on the aluminum foil as the current collector) remaining after the productization in the manufacturing process of the lithium-ion battery was kept heated at 400°C for 10 minutes in an electric furnace under an air atmosphere. Then, 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).

[0046] 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. The concentration of aluminum in the acid solution was 6.7 g / L, the concentration of cobalt was 8.7 g / L, the concentration of manganese was 8.7 g / L, the concentration of nickel was 26.0 g / L, and the concentration of lithium was 6.0 g / L.

[0047] In addition, hereinafter, each metal concentration in the above-mentioned acid solution is referred to as a metal concentration before extraction.

[0048] Next, 225 L of 1 mol / L 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (PC-88A manufactured by Daihachi Chemical Industry Co., Ltd.) diluted with kerosene was added to 75 L of the above acid solution, and the equilibrium pH was adjusted to 1.1 with 6.1 mol / L of sodium hydroxide to perform solvent extraction of aluminum, thereby obtaining 82 L of a valuable metal salt aqueous solution as a raffinate. The aluminum concentration in the above valuable metal salt aqueous solution was 1.5 g / L, the cobalt concentration was 7.9 g / L, the manganese concentration was 7.9 g / L, the nickel concentration was 23.8 g / L, and the lithium concentration was 5.5 g / L. The removal rate of each metal is shown in Table 1.

[0049] In addition, hereinafter, the concentration of each metal in the above-mentioned aqueous solution of the valuable metal salt is referred to as the metal concentration after extraction.

[0050] [Table 1]

[0051] Table 1

[0052] Al Co Mn Ni Li Extracted metal concentration (g / L) 6.7 8.7 8.7 26.0 6.0 Metal concentration after extraction (g / L) 1.5 7.9 7.9 23.8 5.5 Extraction rate (%) 75 0 0 0 0

[0053] The extraction rates shown in Table 1 were calculated by the following formula (1). In addition, the concentration correction factor is a dilution ratio based on the operation.

[0054] Extraction rate = 1-(metal concentration after extraction × concentration correction factor / metal concentration before extraction)…(1)

[0055] Comparative Example 1

[0056] The positive electrode material, that is, the positive electrode foil (formed by coating the positive electrode mixture containing the positive electrode active material on the aluminum foil as the current collector) remaining after the productization in the manufacturing process of the lithium-ion battery was kept heated at 400°C for 10 minutes in an electric furnace under an air atmosphere. Then, 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).

[0057] 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. The concentration of aluminum in the acid solution was 6.7 g / L, the concentration of cobalt was 8.7 g / L, the concentration of manganese was 8.7 g / L, the concentration of nickel was 26.0 g / L, and the concentration of lithium was 6.0 g / L.

[0058] In addition, hereinafter, each metal concentration in the above-mentioned acid solution is referred to as the metal concentration before NaOH addition.

[0059] Next, 75 L of the acid solution was adjusted to an equilibrium pH of 4.0 using a 6.1 mol / L sodium hydroxide aqueous solution and filtered to obtain 82 L of a filtrate. The filtrate had an aluminum concentration of 0.7 g / L, a cobalt concentration of 6.8 g / L, a manganese concentration of 7.1 g / L, a nickel concentration of 19.6 g / L, and a lithium concentration of 4.9 g / L.

[0060] In addition, hereinafter, each metal concentration in the above-mentioned filtrate is referred to as the metal concentration after the addition of NaOH.

[0061] [Table 2]

[0062] Table 2

[0063] Al Co Mn Ni Li Metal concentration before NaOH addition (g / L) 6.7 8.7 8.7 26.0 6.0 Metal concentration after NaOH addition (g / L) 0.7 6.8 7.1 19.6 4.9 Removal rate (%) 93 15 10 18 10

[0064] The removal rates shown in Table 2 were calculated from the following formula (2).

[0065] Removal rate = 1-(metal concentration after NaOH addition × concentration correction constant / metal concentration before NaOH addition)…(2)

[0066] All valuable metals represented by lithium in the acid solution used in Comparative Example 1 were removed by adding sodium hydroxide. On the other hand, manganese, cobalt, nickel and lithium in the acid solution used in Example 1 were not extracted by the above-mentioned extraction solvent. Manganese, cobalt, nickel and lithium in the above-mentioned acid solution can be recovered after the above-mentioned aluminum extraction step. The aluminum extraction method of Example 1, in which manganese, cobalt, nickel and lithium among the valuable metals contained in the acid solution used in Example 1 and Comparative Example 1 cannot or are difficult to be extracted (removed) together with aluminum, is obviously very superior in industry compared with the aluminum removal method of Comparative Example 1.

[0067] Comparative Example 2

[0068] The positive electrode material, that is, the positive electrode foil (formed by coating the positive electrode mixture containing the positive electrode active material on the aluminum foil as the current collector) remaining after the productization in the manufacturing process of the lithium-ion battery was kept heated at 400°C for 10 minutes in an electric furnace under an air atmosphere. Then, 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).

[0069] 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. The concentration of aluminum in the acid solution was 6.7 g / L, the concentration of cobalt was 8.7 g / L, the concentration of manganese was 8.7 g / L, the concentration of nickel was 26.0 g / L, and the concentration of lithium was 6.0 g / L.

[0070] Next, 225 L of 1 mol / L 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (PC-88A manufactured by Daihachi Chemical Industry Co., Ltd.) diluted with kerosene was added to 75 L of the acid solution, and the equilibrium pH was adjusted to 2.0 with 6.1 mol / L sodium hydroxide to perform solvent extraction of aluminum, thereby obtaining 82 L of a valuable metal salt aqueous solution as a raffinate. The valuable metal salt aqueous solution had an aluminum concentration of 0.5 g / L, a cobalt concentration of 6.7 g / L, a manganese concentration of 7.5 g / L, a nickel concentration of 20.2 g / L, and a lithium concentration of 4.9 g / L.

[0071] Furthermore, when the extraction operation was continued, aluminum hydroxide was precipitated in the tank. In addition, cobalt, manganese, nickel and lithium as valuable metals were confirmed in the aluminum hydroxide.

[0072] Example 2

[0073] 10 kg of the positive electrode powder was dissolved in hydrochloric acid adjusted to 9 mol / L to 10 mol / L, and the pH of the obtained acid solution was adjusted to 1.0 with sodium hydroxide. The aluminum concentration in the acid solution was 10 g / L, the cobalt concentration was 13 g / L, the manganese concentration was 13 g / L, the nickel concentration was 39 g / L, the fluorine concentration was 1 g / L, and the liquid volume was 50 L.

[0074] Next, 150 L of 1 mol / L 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (PC-88A manufactured by Daihachi Chemical Industry Co., Ltd.) diluted with kerosene was added to 50 L of the above acid solution, and the equilibrium pH was adjusted to 0.8 to 1.5 with 6.1 mol / L sodium hydroxide aqueous solution, and aluminum was extracted with a solvent to obtain 60 L of a valuable metal salt aqueous solution as a raffinate. The aluminum concentration in the above valuable metal salt aqueous solution was 1.5 g / L, the cobalt concentration was 11 g / L, the manganese concentration was 10.8 g / L, the nickel concentration was 32.5 g / L, and the fluorine concentration was 0.8 g / L. The molar ratio of aluminum ions to fluoride ions in the above valuable metal salt aqueous solution was 0.4.

[0075] Next, sodium hydroxide was added to 60 L of the metal salt aqueous solution to adjust the pH of the metal salt aqueous solution to 5. The aluminum concentration in the adjusted valuable metal salt aqueous solution was 0.003 g / L, the cobalt concentration was 11 g / L, the manganese concentration was 10.5 g / L, the nickel concentration was 32 g / L, and the fluorine concentration was 0.010 g / L. The metal concentration before extraction, the metal concentration after extraction, and the metal concentration after the fluorine separation and removal step (metal concentration after the fluorine separation and removal step) are shown in Table 3.

[0076] [Table 3]

[0077] Table 3

[0078] Al Co Mn Ni F Metal concentration before extraction (g / L) 10.0 13.0 13.0 39.0 1.0 Metal concentration after extraction (g / L) 1.5 11.0 10.8 32.5 0.8 Metal concentration after fluorine separation and removal process (g / L) 0.003 11.0 10.5 32.0 0.010

[0079] Example 3

[0080] 150 L of 1 mol / L 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (PC-88A manufactured by Daihachi Chemical Industry Co., Ltd.) diluted with kerosene was added to 50 L of the above acid solution, and 6.1 mol / L of sodium hydroxide aqueous solution was further added to adjust the equilibrium pH of the above acid solution to 0.8-1.5, and the solvent extraction of aluminum was performed to obtain 58 L of a valuable metal salt aqueous solution as a raffinate. The aluminum concentration in the above valuable metal salt aqueous solution was 3 g / L, the cobalt concentration was 11.2 g / L, the manganese concentration was 11 g / L, the nickel concentration was 33.6 g / L, and the fluorine concentration was 0.8 g / L. The molar ratio of aluminum ions to fluoride ions in the above valuable metal salt aqueous solution was 0.8.

[0081] Next, sodium hydroxide was added to 58 L of the metal salt aqueous solution to adjust the pH of the metal salt aqueous solution to 5. The aluminum concentration in the adjusted valuable metal salt aqueous solution was 0.003 g / L, the cobalt concentration was 10.8 g / L, the manganese concentration was 10.5 g / L, the nickel concentration was 32.8 g / L, and the fluorine concentration was 0.008 g / L. The metal concentrations before extraction, after extraction, and after the fluorine separation and removal step are shown in Table 4.

[0082] [Table 4]

[0083] Table 4

[0084] Al Co Mn Ni F Metal concentration before extraction (g / L) 10.0 13.0 13.0 39.0 1.0 Metal concentration after extraction (g / L) 3.0 11.2 11.0 33.6 0.8 Metal concentration after fluorine separation and removal process (g / L) 0.003 10.8 10.5 32.8 0.005

[0085] Example 4

[0086] 150 L of 1 mol / L 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (PC-88A manufactured by Daihachi Chemical Industry Co., Ltd.) diluted with kerosene was added to 50 L of the above acid solution, and 6.1 mol / L of sodium hydroxide aqueous solution was further added to adjust the equilibrium pH of the above acid solution to 0.8-1.5, and the solvent extraction of aluminum was performed to obtain 62 L of a valuable metal salt aqueous solution as a raffinate. The aluminum concentration in the above valuable metal salt aqueous solution was 0.7 g / L, the cobalt concentration was 10.5 g / L, the manganese concentration was 11 g / L, the nickel concentration was 31.2 g / L, and the fluorine concentration was 0.8 g / L. The molar ratio of aluminum ions to fluoride ions in the above valuable metal salt aqueous solution was 1.6.

[0087] Next, sodium hydroxide was added to 62 L of the metal salt aqueous solution to adjust the pH of the metal salt aqueous solution to 5. The aluminum concentration in the adjusted valuable metal salt aqueous solution was 0.003 g / L, the cobalt concentration was 10.4 g / L, the manganese concentration was 11 g / L, the nickel concentration was 31 g / L, and the fluorine concentration was 0.021 g / L. The metal concentrations before extraction, after extraction, and after the fluorine separation and removal step are shown in Table 5.

[0088] [Table 5]

[0089] Table 5

[0090] Al Co Mn Ni F Metal concentration before extraction (g / L) 10.0 13.0 13.0 39.0 1.0 Metal concentration after extraction (g / L) 0.7 10.5 11.0 31.2 0.8 Metal concentration after fluorine separation and removal process (g / L) 0.003 10.4 11.0 31.0 0.021

[0091] Comparative Example 3

[0092] 150 L of 1 mol / L 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (PC-88A manufactured by Daihachi Chemical Industry Co., Ltd.) diluted with kerosene was added to 50 L of the acid solution, and 6.1 mol / L of sodium hydroxide aqueous solution was further added to adjust the equilibrium pH of the acid solution to 0.8 to 1.5, and the solvent extraction of aluminum was performed to obtain 65 L of a valuable metal salt aqueous solution as a raffinate. The aluminum concentration in the valuable metal salt aqueous solution was 0.1 g / L or less, the cobalt concentration was 10 g / L, the manganese concentration was 10.5 g / L, the nickel concentration was 30 g / L, and the fluorine concentration was 0.8 g / L.

[0093] Next, sodium hydroxide was added to 65 L of the metal salt aqueous solution to adjust the pH of the metal salt aqueous solution to 5. The aluminum concentration in the adjusted valuable metal salt aqueous solution was 0.003 g / L, the cobalt concentration was 9.8 g / L, the manganese concentration was 10.4 g / L, the nickel concentration was 29.8 g / L, and the fluorine concentration was 0.7 g / L. The metal concentrations before extraction, after extraction, and after the fluorine separation and removal step are shown in Table 6.

[0094] [Table 6]

[0095] Table 6

[0096] Al Co Mn Ni F Metal concentration before extraction (g / L) 10.0 13.0 13.0 39.0 1.0 Metal concentration after extraction (g / L) ＜0.1 10.0 10.5 30.0 0.8 Metal concentration after fluorine separation and removal process (g / L) 0.003 9.8 10.4 29.8 0.7

[0097] In the case where aluminum was substantially removed from the aqueous solution of the valuable metal salt used in Comparative Example 3, aluminum hydroxide was not generated in the subsequent neutralization reaction, and thus fluorine could not be removed by coprecipitation. On the other hand, in the case where aluminum was intentionally left in the aluminum removal step from the aqueous solution of the valuable metal salt used in Example 1, aluminum hydroxide was generated in the subsequent neutralization reaction, and thus fluorine could be removed by coprecipitation.

[0098] The aluminum concentration in the acid solution can be made very low by the aluminum extraction process, but on the other hand, it can also be adjusted to any concentration. By adjusting the aluminum concentration according to the residual fluorine concentration, the dissolved fluorine concentration after the aluminum removal process can be adjusted. For example, in the subsequent process, when the acid solution is discharged without being diluted, if the conditions as in Example 3 are used, since the standard of fluorine concentration in the discharged water in Japan is 8 mg / L or less, it is possible to discharge the water without an additional fluorine treatment process.

[0099] Even under the conditions of Examples 2 and 4, when extraction operations of cobalt, nickel and manganese are performed in subsequent steps, the fluorine in the acid solution is diluted, and thus a level close to the above-mentioned emission standards can be achieved.

Claims

1. A method for extracting aluminum, characterized in that: include: In the aluminum extraction step, an acid solution containing aluminum and an organic solvent containing 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester are mixed, and aluminum is extracted from the acid solution under the condition that the equilibrium pH is less than 1.

8.

2. The aluminum extraction method according to claim 1, characterized in that: The acid solution also contains fluorine, The aluminum extraction method includes a fluorine separation and removal step, wherein the aluminum concentration in the raffinate obtained in the aluminum extraction step is adjusted to an arbitrary range, and the equilibrium pH is adjusted to 2 to 7 to generate aluminum hydroxide, thereby coprecipitating fluorine, and performing solid-liquid separation.

3. The aluminum extraction method according to claim 2, characterized in that: The aluminum concentration in the raffinate is 0.1 to 30 g / L.

4. The aluminum extraction method according to any one of claims 1 to 3, characterized in that: Also includes: In the acid dissolution step, the active material powder obtained from the waste lithium-ion battery is dissolved in an inorganic acid to obtain the acid solution.

5. The aluminum extraction method according to claim 4, characterized in that: The inorganic acid includes at least one selected from the group consisting of hydrochloric acid, sulfuric acid, and nitric acid.

6. The aluminum extraction method according to claim 5, characterized in that: The inorganic acid includes hydrochloric acid.