Methods for recovering copper
The method uses an aldoxime extractant and mineral acid back-extraction to recover high-purity copper from aqueous solutions, addressing the challenge of copper purity in waste lithium-ion batteries and enabling its reuse in lithium-ion batteries.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- ASAKA RIKEN
- Filing Date
- 2024-12-16
- Publication Date
- 2026-06-26
AI Technical Summary
Existing methods struggle to recover copper with high purity from aqueous solutions containing copper and other valuable metals, such as those derived from waste lithium-ion batteries.
A method involving the use of an aldoxime extractant to extract copper from an aqueous solution, followed by back-extraction with a mineral acid to obtain copper salt, which is then processed to high-purity copper oxide, utilizing a series of pretreatment and extraction steps including grinding, dissolution, and membrane electrolysis.
The method achieves the recovery of very high-purity copper, suitable for use in copper sulfate electrolytes and as a negative electrode material for lithium-ion batteries, while reusing by-products like lithium hydroxide and mineral acid.
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Abstract
Description
Technical Field
[0001] The present invention relates to a method for recovering copper.
Background Art
[0002] In recent years, with the widespread use of lithium-ion batteries, 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 have been studied. Patent Document 1 discloses a dissolution step in which an active material powder obtained by pretreating a waste lithium-ion battery is dissolved in a mineral acid to obtain a dissolution solution, a neutralization step in which the dissolution solution is neutralized with lithium hydroxide, and a metal sulfide removal step in which the acid dissolution solution to which lithium hydroxide is added and a sulfide are mixed in the range of pH 2 to 6 to form a sulfide of at least one metal selected from the group consisting of copper, cadmium, lead, and mercury, and the metal sulfide is removed, and a method for recovering valuable metals from waste lithium-ion batteries.
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0004] In recent years, there has been a demand for a method for recovering copper in which copper with even higher purity is recovered from an aqueous solution containing copper and valuable metals other than copper, such as the acid dissolution solution obtained by dissolving an active material powder obtained by pretreating a waste lithium-ion battery in a mineral acid.
[0005] Therefore, the problem to be solved by the present invention is to provide a method for recovering copper in which copper with very high purity is recovered from an aqueous solution containing copper and valuable metals other than copper.
Means for Solving the Problems
[0006] In view of the above-mentioned problems, the inventors conducted extensive research and found that copper can be extracted from an aqueous solution containing copper using an extractant containing an aldoxime, and then the extract is mixed with a mineral acid to back-extract a copper salt, after which this copper salt can be used to obtain high-purity copper oxide. The present invention was completed based on these findings.
[0007] The present invention relates to a method for recovering copper, comprising: a copper extraction step in which copper is extracted from an aqueous solution containing copper using an extractant containing an aldoxime; a back extraction step in which the extract obtained through the copper extraction step is mixed with a mineral acid to back extract a copper salt; and a copper oxide production step in which the copper salt obtained through the back extraction step is used to obtain copper oxide.
[0008] The copper oxide obtained through the copper oxide oxidation step is preferably supplied to the copper sulfate electrolyte in which the copper foil is formed. The copper recovery method preferably further includes a pretreatment step for waste lithium-ion batteries, wherein the copper includes copper obtained in the pretreatment step. The aforementioned pretreatment step includes a grinding step in which the waste lithium-ion battery is pulverized, and a dissolution step in which the pulverized material obtained through the grinding step is dissolved in a mineral acid to obtain an acid solution. The copper recovery method preferably comprises an aluminum extraction step in which aluminum is extracted from the acid solution with a second extractant containing a second organic solvent; a neutralization step in which the acid solution is neutralized with an alkali; an extraction step in which at least one selected from the group consisting of manganese, cobalt, and nickel is extracted from the solution obtained in the neutralization step with a first extractant containing a first organic solvent, and a first lithium salt aqueous solution is obtained as the residue; and a membrane electrolysis step in which the first lithium salt aqueous solution is subjected to membrane electrolysis using an ion exchange membrane to obtain a lithium hydroxide aqueous solution, an acid, and a second lithium salt aqueous solution that is more dilute than the first lithium salt aqueous solution, wherein the lithium hydroxide aqueous solution obtained in the membrane electrolysis step is reused in at least one selected from the group consisting of the copper extraction step, the neutralization step, and the solvent extraction step, and the acid obtained in the membrane electrolysis step is reused as the mineral acid used in the dissolution step. [Effects of the Invention]
[0009] The present invention provides a method for recovering copper in which very high-purity copper is recovered from an aqueous solution containing copper and other valuable metals. [Brief explanation of the drawing]
[0010] [Figure 1] An explanatory diagram showing the configuration of one embodiment of the copper recovery method of the present invention. [Modes for carrying out the invention]
[0011] The present invention will be described in more detail. Unless otherwise specified, the numerical range "X~Y" represents the range from X or greater to Y or less, including both values at both ends. Furthermore, when a numerical range is indicated, the upper and lower limits may be combined as appropriate, and the resulting numerical range will also be disclosed.
[0012] In this invention, "waste lithium-ion battery" refers to a used lithium-ion battery whose lifespan as a battery product has been exhausted, a lithium-ion battery discarded as a defective product during the manufacturing process, and residual positive electrode material, negative electrode material, etc., used in the manufacturing process. Furthermore, the powder containing positive and negative electrodes obtained from the waste lithium-ion battery is the active material powder. In addition, "impurity" refers to metals contained in the active material powder that do not require recovery.
[0013] One embodiment of the valuable metal recovery method of the present invention will be described in more detail with reference to the attached drawings. <Copper extraction step> The present invention provides a copper recovery method comprising a copper extraction step (STEP 2 in Figure 1) in which copper is extracted from an aqueous solution containing copper using an extractant containing an aldoxime. The aldoxime preferably has at least one selected from the group consisting of a condensed polycyclic structure, a condensed polycyclic heterocyclic structure, a diaryl sulfide structure, and a benzene structure. The condensed polycyclic structure preferably has at least one selected from the group consisting of a fluorene structure, a benzofluorene structure, a dibenzofluorene structure, an indene structure, an indane structure, a benzoindene structure, and a benzoindane structure. The condensed polycyclic heterocyclic structure preferably has at least one selected from the group consisting of a carbazole structure, a dibenzofuran structure, a dibenzothiophene structure, a benzocarbazole structure, an indole structure, an indoline structure, a benzoindole structure, a benzoindoline structure, a phenothiazine structure, and a phenothiazine oxide structure. The diaryl sulfide structure preferably has at least one selected from the group consisting of a diphenyl sulfide structure, a naphthylphenyl sulfide structure, and a dinaphthyl sulfide structure.
[0014] Aldoximes are commercially available. An example of a commercially available aldoxime is Acorga, manufactured by CYTEC.
[0015] <Reverse extraction step> The copper recovery method of the present invention includes a back-extraction step (STEP 3 in Figure 1) in which the extract obtained through the copper extraction step is mixed with a mineral acid and the copper salt is back-extracted. The mineral acid preferably 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.
[0016] <Copper oxide generation step> The copper recovery method of the present invention includes a copper oxide generation step (STEP 4 in Figure 1) in which the copper salt obtained through the back extraction step is used to obtain copper oxide. Since the copper oxide has very high purity, it may be used as a copper ion supplement (see Japanese Patent No. 2753855).
[0017] For example, when copper sulfate is subjected to electrolysis using a drum-roll type electrode, copper foil is formed on the electrode, and when the copper foil reaches a certain thickness, it is wound up and recovered. The copper oxide is supplied to the electrolyte as a copper ion supplement and reacts with the sulfuric acid produced in the electrolysis to produce copper sulfate. The copper foil may be used as a negative electrode material for a lithium-ion battery.
[0018] As shown in Figure 1, the copper recovery method of the present invention may use the active material powder 1 as a starting material. The active material powder 1 will be described. The copper recovery method of the present invention may include a pretreatment step of pretreating a waste lithium ion battery. When the waste lithium ion battery is a used lithium ion battery whose battery life as a battery product has expired, or a lithium ion battery discarded as a defective product or the like in the manufacturing step, first, a discharging process is performed. As the discharging process, various highly safe methods such as resistive discharging can be adopted. By discharging, all the remaining charges are discharged. Then, after an opening is formed in the casing of the waste lithium ion battery, for example, heat treatment (roasting) is performed at a temperature in the range of 100 to 800 ° C, or it is pulverized by a pulverizer such as a hammer mill or a jaw crusher without heat treatment, and the casing, current collector, etc. constituting the waste lithium ion battery are removed (classified) by sieving, and the active material powder 1 is obtained. Alternatively, after the waste lithium ion battery after the discharging process is pulverized by the pulverizer and the casing, current collector, etc. are removed by sieving, heat treatment is performed at the above range of temperature, and the active material powder 1 may be obtained. In the copper recovery method of the present invention, since the active material powder 1 is dissolved in hydrochloric acid, there is no problem even if the reduction of the active material powder 1 in the roasting step is omitted.
[0019] The waste lithium ion battery is not limited to a specific waste lithium ion battery. The waste lithium ion battery may include, for example, at least one selected from the group consisting of a lithium ion battery for a plug-in hybrid vehicle, a lithium ion battery for a hybrid vehicle, a lithium ion battery for an electric vehicle, and a lithium ion battery for a personal computer.
[0020] <Dissolution step> The copper recovery method of the present invention may include a dissolution step (STEP 1 in FIG. 1) in which the active material powder 1 is put into a mineral acid to obtain an acid dissolution solution. In addition to lithium, the active material powder 1 may contain valuable metals such as copper, iron, aluminum, manganese, cobalt, magnesium, nickel, etc. The mineral acid preferably contains at least one selected from the group consisting of hydrochloric acid, sulfuric acid, and nitric acid, more preferably contains hydrochloric acid, and still more preferably is hydrochloric acid. The acid dissolution solution may be subjected to the copper extraction step.
[0021] <First solid-liquid separation step> The copper recovery method of the present invention may include a first solid-liquid separation step in which carbon powder is removed from the acid dissolution solution.
[0022] <Step for removing valuable metals other than lithium, copper, cobalt, manganese and nickel><00001The copper recovery method of the present invention may include an aluminum extraction step in which an acid solution obtained via at least one selected from the group consisting of the first solid-liquid separation step and the valuable metal removal step is mixed with a third extractant containing a third organic solvent, and aluminum is extracted from the acid solution under conditions of equilibrium pH less than 1.8 (see Japanese Patent No. 7453727). The third organic solvent preferably contains 2-ethylhexyl 2-ethylhexyl phosphonate, and more preferably 2-ethylhexyl 2-ethylhexyl phosphonate. The third extractant may contain a diluent, and the concentration of the third organic solvent may be adjusted as appropriate. Examples of the diluent include hydrocarbons such as kerosene and decane. The concentration of the third organic solvent in the third extractant is preferably in the range of 10 to 40% by mass.
[0026] <First Neutralization Step> The copper recovery method of the present invention may optionally include a first neutralization step in which an acid solution obtained via at least one selected from the group consisting of the first solid-liquid separation step, the valuable metal removal step, and the aluminum extraction step is neutralized with an alkali. Aluminum hydroxide may precipitate in the first neutralization step, and fluorine may coprecipitate together with the aluminum hydroxide. The alkali may be added in at least one form selected from the group consisting of an aqueous solution and a solid. The alkali preferably includes at least one selected from the group consisting of alkali metal hydroxides and ammonia. Furthermore, the alkali metal constituting the alkali metal hydroxide preferably includes at least one selected from the group consisting of lithium, sodium, potassium, rubidium, cesium, and francium, more preferably lithium, sodium, and potassium, even more preferably lithium, sodium, or potassium, and particularly preferably lithium.
[0027] <Hydroxylation step> The copper recovery method of the present invention may optionally include a hydrosulfidation step in which an acid solution obtained via at least one selected from the group consisting of the first solid-liquid separation step, the aluminum extraction step, and the first neutralization step is mixed with a sodium hydrosulfide salt, and copper not extracted in the copper extraction step reacts with the sodium hydrosulfide salt to precipitate copper sulfide. The hydrosulfide salt preferably comprises at least one selected from the group consisting of sodium hydrosulfide and lithium hydrosulfide, more preferably comprises lithium hydrosulfide, and even more preferably lithium hydrosulfide.
[0028] <Second solid-liquid separation step> The copper recovery method of the present invention may include a second solid-liquid separation step in which aluminum hydroxide is separated from the acid solution obtained via the hydrosulfidation step. If fluorine coprecipitates with the aluminum hydroxide separated in the second solid-liquid separation step, fluorine is also separated together with the aluminum hydroxide.
[0029] <Calcium Removal Steps> The copper recovery method of the present invention may optionally include a calcium removal step in which calcium is removed from the acid solution obtained via at least one selected from the group consisting of the first solid-liquid separation step, the valuable metal removal step, the aluminum extraction step, the first neutralization step, the hydrosulfidation step, and the second solid-liquid separation step. For example, the acid solution is mixed with an organic solvent containing di(2-ethylhexyl) phosphate (D2EHPA), and calcium is extracted from the acid solution. The organic solvent may contain a diluent, and the concentration of D2EHPA may be adjusted as appropriate. Examples of the diluent include hydrocarbons such as kerosene and decane. The concentration of D2EHPA in the organic solvent is preferably in the range of 10 to 40% by mass. The pH during extraction is preferably adjusted to the range of 1.5 to 2.02 to 2.5 by adding lithium hydroxide. The extract obtained via the calcium removal step may be scrubbed, and the aqueous solution after scrubbing may be returned to the calcium removal step. The extract contains cobalt and manganese. Cobalt and manganese are returned to the acid solution by scrubbing. If necessary, the extract containing calcium, after scrubbing, is back-extracted to recover the calcium salt.
[0030] At least one of the steps selected from the group consisting of the first solid-liquid separation step, the valuable metal removal step, the aluminum extraction step, the first neutralization step, the hydrosulfidation step, the second solid-liquid separation step, and the calcium removal step may preferably be performed between the dissolution step and the extraction step described later. If two or more of these steps are performed, the order in which the steps are performed may be set as appropriate.
[0031] <Extraction Step> The copper recovery method of the present invention may include an extraction step (STEP 5 in Figure 1) in which at least one selected from the group consisting of manganese, cobalt, and nickel is separated from the acid solution using a first extractant containing a first organic solvent, and a first lithium salt aqueous solution is obtained as the residue of the organic solvent extraction.
[0032] In the extraction step, manganese, cobalt, and nickel, excluding lithium, are each extracted separately by the first extractant, or iron is separated and removed as an aqueous metal sulfate solution. If the alkali is lithium hydroxide, an aqueous first lithium salt solution can be obtained. If the alkali is at least one selected from the group consisting of sodium hydroxide and potassium hydroxide, the aqueous first lithium salt solution and at least one salt of sodium and potassium are separated from the aqueous alkali mixed salt solution obtained in the extraction step by the method disclosed in Japanese Patent Publication No. 7084669. The lithium salt contained in the aqueous first lithium salt solution becomes lithium chloride when hydrochloric acid is used as the mineral acid in the dissolution step. The first organic solvent is at least one selected from the group consisting of organophosphorus compounds such as phosphate esters, phosphonic acid esters, phosphinic acid, and phosphine oxide, hydrooximes, and organic amine compounds. Each of the aqueous metal sulfate solutions may be scrubbed, during which magnesium is removed.
[0033] Examples of the oxidized phosphine include Toly n-octylphosphine (TOPO). Examples of the hydrooximes include 7-hydroxy-5,8-diethyl-6-dodecanone oxime (LIX-63), 5-dodecyl-2-hydroxybenzaldehyde oxime (LIX 860), 2-hydroxy-5-nonylbenzophenone oxime (LIX 65N), 2-hydroxy-5-nonylacetophenone oxime (SME 529), and 2-hydroxy-5-nonylphenylbenzylketone oxime (Acorga P-17). Examples of the aforementioned organic amine compounds include Primene® JM-T, a primary amine manufactured by Dow Chemical; Amberlite® LA-2, a secondary amine manufactured by Sigma-Aldrich; Alamine 336 (trioctylamine), a tertiary amine manufactured by Sigma-Aldrich; and Aliquat® 336, a quaternary ammonium salt manufactured by Sigma-Aldrich.
[0034] <Membrane electrolysis step> The method for recovering valuable metals according to the present invention may include a membrane electrolysis step (STEP 6 in Figure 1) in which the first lithium salt aqueous solution is electrolyzed using an ion exchange membrane to obtain a lithium hydroxide aqueous solution, an acid, and a second lithium salt aqueous solution that is more dilute than the first lithium salt aqueous solution. The membrane electrolysis step is carried out in the same manner as the membrane electrolysis step using an ion exchange membrane disclosed in International Publication No. 2023 / 195533.
[0035] The lithium hydroxide aqueous solution obtained in the membrane electrolysis step, which may be included in the method for recovering valuable metals of the present invention, may be reused in at least one selected from the group consisting of the copper extraction step, the aluminum extraction step, the first neutralization step, and the extraction step, and the acid obtained in the membrane electrolysis step may be reused as the mineral acid used in at least one selected from the group consisting of the dissolution step and the copper dissolution step. [Explanation of Symbols]
[0036] 1...Active material powder.
Claims
1. A method for recovering copper, A copper extraction step in which copper is extracted from an aqueous solution containing copper using an extractant containing aldoxime. The extract obtained through the copper extraction step is mixed with a mineral acid in a back-extraction step in which copper salts are back-extracted, and A method for recovering copper, comprising a copper oxide production step in which the copper salt obtained through the back-extraction step is used to obtain copper oxide.
2. A method for recovering copper according to claim 1, A method for recovering copper, wherein the copper oxide obtained through the copper oxide oxidation step is supplied to the electrolysis of copper sulfate in which copper foil is formed.
3. A method for recovering copper according to claim 1, The process further includes a pretreatment step for waste lithium-ion batteries, A method for recovering copper, wherein the copper includes the copper obtained in the pretreatment step.
4. A method for recovering copper according to claim 3, The aforementioned pretreatment step includes a crushing step in which the waste lithium-ion battery is crushed, A method for recovering copper, comprising a dissolution step in which the pulverized material obtained through the pulverization step is dissolved in a mineral acid to obtain an acid solution.
5. A method for recovering copper according to any one of claims 1 to 4, An aluminum extraction step in which aluminum is extracted from the acid solution with a second extractant containing a second organic solvent, A neutralization step in which the acid solution is neutralized with an alkali, An extraction step is performed in which at least one selected from the group consisting of manganese, cobalt, and nickel is extracted from the liquid obtained in the neutralization step using a first extractant containing a first organic solvent, and the remaining liquid is an aqueous solution of a first lithium salt, and The first lithium salt aqueous solution is subjected to membrane electrolysis using an ion exchange membrane to obtain a lithium hydroxide aqueous solution, an acid, and a second lithium salt aqueous solution that is more dilute than the first lithium salt aqueous solution, further comprising a membrane electrolysis step. The aqueous lithium hydroxide solution obtained in the membrane electrolysis step is reused in at least one selected from the group consisting of the copper extraction step, the neutralization step, and the extraction step. A method for recovering copper, wherein the acid obtained in the film electrolysis step is reused as the mineral acid used in the dissolution step.