Metal recovery method

Abstract

This metal recovery method is for leaching metal in a battery powder of a lithium-ion battery waste and for separating and recovering the metal from a thus obtained metal-containing solution. The metal recovery method comprises an elution step for bringing, into contact with an acidic eluent, a cation exchange resin and / or a chelate resin in which metal ions derived from the battery powder are adsorbed as adsorption target ions, and eluting the adsorption target ions from the cation exchange resin and / or the chelate resin to obtain a post-elution liquid including the adsorption target ions. An acidic liquid that is obtained by electrodialysis and contains the metal ions is used as at least a part of the acidic eluent in the elution step to cause the metal ions contained in the acidic liquid to be included in the post-elution liquid, and the post-elution liquid is brought back to and is used in steps included in the steps for leaching metal in the battery powder, and for separating and recovering the metal.

Description

Metal recovery method

[0001] This specification describes a metal recovery method.

[0002] In recent years, from the perspective of effective resource utilization, recovery of valuable metals from waste batteries such as waste lithium-ion batteries discarded due to product life, manufacturing defects, or other reasons has been widely considered.

[0003] To recover metals from lithium-ion battery waste, for example, battery powder obtained through heat treatment or other processes is brought into contact with an acidic leachate such as sulfuric acid to leach the metals in the battery powder into the acidic leachate, thereby obtaining a metal-containing solution in which nickel, cobalt, manganese, aluminum, iron, etc. are dissolved.

[0004] Next, the metals are separated from the metal-containing solution. Specifically, as described in Patent Documents 1 to 3, for example, impurities such as aluminum and iron, and manganese are sequentially or simultaneously separated from the metals dissolved in the metal-containing solution by neutralization or solvent extraction. Thereafter, nickel and cobalt are separated by solvent extraction and concentrated for extraction.

[0005] In such processes, electrodialysis may be performed to convert anions in a metal-containing solution, such as a post-extraction solution, into other anions.

[0006] For example, Patent Document 4 discloses "a method for producing lithium hydroxide, in which an electrolysis device is composed of an anode cell, a cathode cell, and a cation exchange membrane, an aqueous solution or suspension of lithium carbonate is supplied to the anode cell to perform electrolysis, and an aqueous solution of lithium hydroxide is produced in the cathode cell via the cation exchange membrane."

[0007] Furthermore, Patent Document 5 proposes a method for producing lithium hydroxide, comprising: "An electrodialysis apparatus in which cation exchange membranes and anion exchange membranes are alternately arranged between an anode and a cathode, the anode and the cation exchange membrane form an anode chamber; then, from the anode side to the cathode side, an acid chamber partitioned by the cation exchange membrane and an anion membrane, a salt chamber partitioned by the anion exchange membrane and another cation exchange membrane, an alkaline chamber partitioned by this cation exchange membrane and another anion exchange membrane, and a water electrolysis chamber partitioned by this anion exchange membrane and a new cation exchange membrane, with one or more sets of acid chambers, salt chambers, alkaline chambers, and water electrolysis chambers arranged in this order; and in which the water electrolysis chamber formed by the anion membrane closest to the cathode is partitioned by a cathode instead of a cation membrane, and serves as the cathode chamber; and an aqueous solution of lithium salts is supplied to the salt chamber, and acid is extracted from the acid chamber and lithium hydroxide aqueous solution is extracted from the alkaline chamber."

[0008] JP 2010-180439 A U.S. Patent Application Publication No. 2011 / 0135547 JP 2014-162982 A JP 2009-270188 A JP 2011-31232 A

[0009] When electrodialysis is performed as described above, certain metal ions are mainly contained in the post-dialysis solution, but some may also be contained in the acid solution obtained together with the post-dialysis solution. Therefore, discarding the acid solution results in a loss of the metal.

[0010] Furthermore, prior to electrodialysis, it is desirable to wash the metal-containing solution using a cation exchange resin or a chelating resin to remove impurity metal ions other than the specified metal ions in the metal-containing solution by adsorbing them onto the cation exchange resin or chelating resin. The cation exchange resin or chelating resin used for washing can be contacted with an acidic eluent such as sulfuric acid to elute the adsorbed impurity metal ions, which can then be regenerated. Here, the impurity metal ions are referred to as impurities to distinguish them from the metal ions that are the main component of the metal-containing solution to be subjected to electrodialysis. However, if these impurity metal ions could also be recovered, the loss of such metals could be reduced.

[0011] This specification provides a metal recovery method that can effectively suppress metal loss.

[0012] The metal recovery method disclosed in this specification is a method for leaching metals in battery powder of lithium-ion battery waste, and separating and recovering the metals from the resulting metal-containing solution, and includes an elution step in which a cation exchange resin and / or a chelating resin, onto which metal ions derived from the battery powder have been adsorbed as ions to be adsorbed, is contacted with an acidic eluent to elute the ions to be adsorbed from the cation exchange resin and / or chelating resin, thereby obtaining a post-elution solution containing the ions to be adsorbed, and an acid solution containing metal ions obtained by electrodialysis is used as at least a part of the acidic eluent in the elution step, so that the metal ions contained in the acid solution are contained in the post-elution solution, and the post-elution solution is returned to and used in the steps involved in leaching the metals in the battery powder and separating and recovering the metals.

[0013] According to the above-described metal recovery method, metal loss can be effectively suppressed.

[0014] Fig. 1 is a flow chart showing an example of a metal recovery process including the metal recovery method of one embodiment. Fig. 2 is a flow chart showing an example of a pretreatment step for obtaining battery powder from lithium ion battery waste. Fig. 3 is a flow chart showing an aspect of repeated use of a cation exchange resin and / or a chelating resin in the metal recovery method of one embodiment. Fig. 4 is a cross-sectional view schematically showing an example of a bipolar membrane electrodialysis device that can be used in the electrodialysis step that can be included in the metal recovery method of one embodiment.

[0015] The following describes in detail an embodiment of the metal recovery method. One embodiment of the metal recovery method involves leaching metals from battery powder in lithium-ion battery waste and then separating and recovering the metals from the resulting metal-containing solution. This method includes an elution step in which a cation exchange resin and / or a chelating resin having metal ions adsorbed thereon is contacted with an acidic eluent to elute the metal ions from the cation exchange resin and / or the chelating resin.

[0016] The cation exchange resin and / or chelating resin used in the elution step has previously come into contact with a metal-containing solution, thereby adsorbing metal ions derived from the battery powder as ions to be adsorbed. When the resin is brought into contact with an acidic eluent in the elution step, the ions to be adsorbed are eluted from the cation exchange resin and / or chelating resin, and the ions to be adsorbed are contained in the post-elution solution.

[0017] Incidentally, electrodialysis in the electrodialysis step described below may produce an acid solution containing metal ions. By using this acid solution as at least a part of the acidic eluent in the elution step, the post-elution solution contains not only the target ions for adsorption but also the metal ions contained in the acid solution. By using the post-elution solution in at least one step involved in leaching and separating and recovering the metals in the battery powder, it is possible to effectively suppress metal loss from the target ions for adsorption and the metal ions contained in the acid solution.

[0018] The metal recovery method of this embodiment may be implemented, for example, in a metal recovery method having the steps shown in FIG. 1. In FIG. 1, battery powder from lithium-ion battery waste is subjected to an acid leaching step, a metal separation step, a washing step, an electrodialysis step, and a crystallization step, in this order. As shown in FIG. 2, the battery powder can be obtained by subjecting lithium-ion battery waste to a pretreatment step. FIG. 3 also shows an example of a case in which the cation exchange resin and / or chelating resin used in the washing step is repeatedly used. Here, the description will be made with reference to FIGS. 1 to 3, but FIGS. 1 to 3 are merely examples and are not limited to such specific flows.

[0019] (Lithium-ion battery waste) The target lithium-ion battery waste is lithium-ion secondary batteries that can be used in mobile phones and various other electronic devices, etc., that have been discarded due to the end of the battery product's life, manufacturing defects, or other reasons. Recovering valuable metals from such lithium-ion battery waste is preferable from the perspective of effective resource utilization.

[0020] Lithium-ion battery waste may have an aluminum casing containing a cathode active material made of a single metal oxide containing lithium and one or more selected from the group consisting of nickel, cobalt, and manganese, or a composite metal oxide containing two or more selected from the group consisting of lithium and nickel, cobalt, and manganese, or an aluminum foil (cathode substrate) to which the cathode active material is coated and fixed with, for example, polyvinylidene fluoride (PVDF) or other organic binders. Lithium-ion battery waste may also contain copper, iron, etc. Furthermore, the casing may contain an electrolyte solution prepared by dissolving an electrolyte such as lithium hexafluorophosphate in an organic solvent such as ethylene carbonate or diethyl carbonate.

[0021] (Pretreatment Process) A pretreatment process is often performed on lithium-ion battery waste. The pretreatment process may include at least one of roasting, crushing, and sieving. Lithium-ion battery waste is converted into battery powder through the pretreatment process. The roasting, crushing, and sieving processes of the pretreatment process may be performed individually as needed, or may be performed in any order. Battery powder refers to powder obtained by separating and concentrating positive electrode material components from lithium-ion battery waste through some kind of pretreatment. Battery powder may also be obtained as a powder by concentrating positive electrode material components by crushing and sieving lithium-ion battery waste with or without heat treatment.

[0022] In the roasting process, the lithium-ion battery waste is heated. The roasting process decomposes and removes the electrolyte and organic binder, and metals such as lithium and cobalt contained in the lithium-ion battery waste may be converted into forms that are easily soluble in the acid leaching solution during the acid leaching process. Although the composition of the positive electrode active material changes during roasting, the roasted material is still referred to as the positive electrode active material. During roasting, the lithium-ion battery waste is preferably heated and maintained at a temperature ranging from 600°C to 800°C for 0.5 to 6 hours. The roasting process can be carried out in air or an inert atmosphere such as nitrogen. The roasting process can be carried out in this order or the reverse order. For example, a batch-type stationary furnace, a continuous rotary kiln furnace, or other various furnaces can be used as the roasting furnace.

[0023] After roasting, crushing can be performed. In crushing, the housing of the lithium-ion battery waste is broken and the positive electrode active material is selectively separated from the aluminum foil on which the positive electrode active material is applied. Various known devices or equipment can be used for crushing, but it is particularly preferable to use an impact crusher that can crush the lithium-ion battery waste by applying impact while cutting it. Examples of such impact crushers include a sample mill, hammer mill, pin mill, wing mill, tornado mill, and hammer crusher.

[0024] After shredding the lithium-ion battery waste, it is sieved using a sieve with appropriate mesh size. This leaves aluminum and copper on the sieve, while leaving battery powder with some of the aluminum and copper removed. When the battery powder contains nickel, the nickel content is, for example, 1% to 30% by mass, typically 5% to 20% by mass. When cobalt is contained, the cobalt content in the battery powder is, for example, 1% to 30% by mass, typically 5% to 20% by mass. The battery powder may also contain, for example, 2% to 8% by mass of lithium, 1% to 30% by mass of manganese, 1% to 10% by mass of aluminum, 1% to 5% by mass of iron, and 1% to 10% by mass of copper.

[0025] In order to extract substantially only lithium from the battery powder, the battery powder may be brought into contact with water before the acid leaching step described below, and the lithium in the battery powder may be leached into water. In this case, the battery powder as a water leaching residue is subjected to the acid leaching step. However, the battery powder may also be subjected to the acid leaching step without water leaching. If water leaching is not performed, it becomes easier to maintain a high lithium ion concentration in the solution in the wet treatment after the acid leaching step.

[0026] (Acid Leaching Step) In the acid leaching step, the metals in the battery powder are brought into contact with an acidic leaching solution containing a mineral or inorganic acid such as sulfuric acid, hydrochloric acid, or nitric acid to leach the metals. This dissolves the metals in the battery powder, resulting in a leached solution containing the metals as metal ions. Here, the solution containing the metals in the battery powder as metal ions is referred to as a metal-containing solution. The metal-containing solution includes the leached solution obtained in the acid leaching step and sent to the subsequent metal separation step, as well as a solution in which at least one of the metals in the battery powder is dissolved during the metal separation step and subsequent steps.

[0027] The pH of the acidic leachate during leaching is preferably -0.5 to 3.0, and the pH of the post-leaching solution after leaching may be 0.5 to 2.0. During leaching, for example, the acidic leachate may be stirred at 100 rpm to 400 rpm using a stirrer as needed, and the solution temperature may be set to 50°C to 80°C, or further 65°C to 70°C.

[0028] Here, the post-elution solution obtained in the elution step described below is preferably returned to the acid leaching step for use. As will be described in detail later, the post-elution solution contains at least one target ion for adsorption selected from the group consisting of nickel ions, cobalt ions, manganese ions, and magnesium ions, as well as metal ions, such as lithium ions, that were contained in the acid solution obtained by electrodialysis. By returning this post-elution solution to the acid leaching step rather than discarding it, the target ions for adsorption and metal ions can be separated and recovered in the metal separation step, or circulated through a series of wet treatment steps (here, the metal separation step, the washing step, and the electrodialysis step) following the acid leaching step, contributing to an increase in the lithium ion concentration in the solution. This effectively suppresses metal loss.

[0029] In this case, specifically, the post-elution solution can be used as the acid leaching solution by itself, or it can be mixed with a separately prepared acid leaching solution. In this case, the need for a new acid leaching solution in the acid leaching step is eliminated or the amount of acid leaching solution used can be reduced, thereby reducing the cost of the acid. In addition, the post-elution solution can be added before, during, and / or after leaching. The post-elution solution can also be added to the post-leaching solution.

[0030] The metal-containing solution (post-leaching solution) obtained in the acid leaching step may have, for example, a cobalt ion concentration of 10 g / L to 50 g / L, a nickel ion concentration of 10 g / L to 50 g / L, a manganese ion concentration of 0 g / L to 50 g / L, an aluminum ion concentration of 1.0 g / L to 20 g / L, an iron ion concentration of 0.1 g / L to 5.0 g / L, and a copper ion concentration of 0.005 g / L to 0.2 g / L.

[0031] (Metal Separation Step) In the metal separation step, each metal ion is separated from the metal-containing solution obtained in the acid leaching step. The metal separation step may include, for example, neutralization, manganese extraction, cobalt extraction, and nickel extraction, in this order, as described below.

[0032] In the neutralization step, the pH of the metal-containing solution is increased, and the neutralization residue is separated to obtain a neutralized solution. Neutralization may include, for example, a dealumination step in which the pH of the metal-containing solution is increased to precipitate and remove at least a portion of the aluminum ions, followed by a de-ironization step in which an oxidizing agent is added to oxidize the iron ions, and if necessary, the pH is further increased to precipitate and remove the iron ions. However, if the metal-containing solution does not substantially contain iron ions, the de-ironization step may be omitted. In each of the dealumination step and the de-ironization step, the pH may be set within a range of 3.0 to 4.5. In the de-ironization step, the ORP value during oxidation may be set to 300 mV to 900 mV. After precipitating aluminum in the dealumination step and after precipitating iron in the de-ironization step, the neutralization residue as the precipitate can be removed by solid-liquid separation such as filtration using known devices and methods such as a filter press or a thickener.

[0033] In the dealumination and iron removal steps, alkaline pH adjusters such as lithium hydroxide, sodium hydroxide, sodium carbonate, and ammonia can be used. The lithium hydroxide aqueous solution obtained in the electrodialysis step described below can be used. In this case, lithium ions circulate within the series of steps in the wet treatment. The oxidizing agent used in the iron removal step is not particularly limited as long as it can oxidize iron, but manganese dioxide, a positive electrode active material, and / or a manganese-containing leaching residue obtained by leaching the positive electrode active material are preferred.

[0034] The metal-containing solution as the post-neutralization solution can be subjected to solvent extraction to extract and remove manganese ions, and in some cases, residual aluminum ions as well. In this case, the manganese ions and residual aluminum ions are extracted, thereby obtaining a post-manganese-extracted solution from which they have been removed.

[0035] Manganese extraction can use a phosphate ester extractant (such as di-2-ethylhexyl phosphoric acid (abbreviation: D2EHPA or trade name: DP-8R)), or a mixture of a phosphate ester extractant and an aldoxime or an oxime extractant containing aldoxime as the main component (such as 2-hydroxy-5-nonylacetophenone oxime (trade name: LIX84), 5-dodecylsalicyldoxime (trade name: LIX860), a mixture of LIX84 and LIX860 (trade name: LIX984), or 5-nonylsalicylaldoxime (trade name: ACORGAM5640)). During extraction, the equilibrium pH is preferably adjusted to 2.3 to 3.5, more preferably 2.5 to 3.0. The alkaline pH adjuster used here is preferably a lithium hydroxide solution obtained in the electrodialysis step described below, but separately prepared sodium hydroxide or the like may also be used.

[0036] During extraction, it is desirable to perform extraction by countercurrent multistage extraction, in which the aqueous phase and solvent used in each extraction flow in opposite directions. This can suppress the extraction of other metal ions such as cobalt ions, nickel ions, and lithium ions, and increase the extraction rate of manganese ions. When using countercurrent multistage extraction, it is effective to set the equilibrium pH during the first extraction stage within the above-mentioned range and lower the equilibrium pH during each subsequent extraction stage. Countercurrent multistage extraction is also suitable for cobalt extraction and nickel extraction, which will be described later.

[0037] Next, cobalt extraction can be carried out. In cobalt extraction, cobalt ions are separated by solvent extraction from the manganese extraction solution obtained after manganese extraction. In cobalt extraction, a solvent containing a phosphonate ester extractant such as 2-ethylhexyl 2-ethylhexylphosphonate (trade name: PC-88A, Ionquest 801) is preferably used. During extraction, the equilibrium pH can be adjusted to preferably 5.0 to 6.0, more preferably 5.0 to 5.5. In this case, as a pH adjuster, it is preferable to use a lithium hydroxide solution obtained in the electrodialysis step described below, but separately prepared sodium hydroxide or the like may also be used.

[0038] The solvent from which the cobalt ions have been extracted can be scrubbed as needed, and then stripped using a stripping solution containing sulfuric acid, hydrochloric acid, nitric acid, or the like, at a pH of, for example, 2.0 to 4.0. The stripped solution can then be heated and concentrated to crystallize the cobalt ions as a cobalt salt.

[0039] In nickel extraction, in order to separate nickel ions from the cobalt-extracted solution after cobalt ions have been extracted, the nickel ions are extracted into a solvent containing a carboxylic acid extractant such as neodecanoic acid or naphthenic acid. At this time, the equilibrium pH is preferably 6.0 to 8.0, more preferably 6.8 to 7.2. The pH adjuster used to adjust the pH may be sodium hydroxide or the like, but it is preferable to use a lithium hydroxide solution obtained in the electrodialysis step described below.

[0040] The solvent from which the nickel ions have been extracted can be scrubbed as needed, and then stripped using a stripping solution containing sulfuric acid, hydrochloric acid, nitric acid, or the like, at a pH of, for example, 1.0 to 3.0. The stripped solution can then be electrolyzed and dissolved as needed, and then heated to concentrate, allowing the nickel ions to crystallize as a nickel salt such as nickel sulfate.

[0041] At least a portion of the metal-containing solution from which nickel ions have been extracted can be mixed with the acid leaching solution in the acid leaching step and used. This allows the lithium ions contained in the lithium-containing solution to be circulated through a series of steps including the acid leaching step and the metal separation step. Preferably, after the lithium ions have been circulated in this way and the lithium ion concentration in the lithium-containing solution has increased to a certain extent, the washing step and electrodialysis step described below are carried out.

[0042] (Washing step) The metal-containing solution after the metal separation step mainly contains lithium ions, but may also contain trace amounts of at least one metal ion selected from the group consisting of nickel ions, cobalt ions, manganese ions, and magnesium ions. Here, these metal ions are referred to as impurity metal ions because they remain in the metal-containing solution other than lithium ions at this stage. However, it can be said that it is desirable to recover impurity metal ions from the overall process of recovering metals from lithium-ion battery waste.

[0043] Since the impurity metal ions are cations like lithium ions, they behave similarly to lithium ions during electrodialysis in the electrodialysis process, making them difficult to separate from lithium ions. Furthermore, when electrodialysis is performed on a metal-containing solution containing the above metal ions, hydroxides of nickel, magnesium, etc. are generated in the resulting lithium hydroxide solution, which may cause process troubles that make it impossible to continue the electrodialysis.

[0044] Therefore, prior to the electrodialysis step, a washing step can be performed to remove impurity metal ions from the metal-containing solution. In the washing step, the metal-containing solution is brought into contact with a cation exchange resin and / or a chelating resin, and the impurity metal ions in the metal-containing solution are adsorbed onto the cation exchange resin and / or the chelating resin as ions to be adsorbed. In this way, the metal-containing solution is washed and the impurity metal ions are separated, resulting in a washed solution.

[0045] The cation exchange resin that can be used in the washing process is a synthetic resin that binds to cations by having acidic groups on its surface. The chelating resin that can be used in addition to or instead of the cation exchange resin in the washing process is a resin with functional groups that form complexes with metal ions. Note that the metal-containing solution may be contacted with either the cation exchange resin or the chelating resin in the washing process, and then with the other. In other words, the resin adsorption process may be performed in multiple stages. Since the metal-containing solution contains lithium ions in addition to impurity metal ions (ions to be adsorbed), it is desirable to use a cation exchange resin and / or a chelating resin with a high selectivity for lithium ions in the washing process.

[0046] Specifically, the washing step can be carried out, for example, by packing the resin in a column and passing the metal-containing solution through the column. The spatial velocity (SV) of the metal-containing solution in the column is preferably in the range of 10 to 20. This spatial velocity (SV) refers to the ratio (times) of the amount of metal-containing solution passing through the column per hour to the amount of resin packed in the column. If the spatial velocity (SV) is too fast, there is a concern that the impurity metal ions will not be adsorbed onto the resin for sufficient time, and the impurity metal ions in the metal-containing solution will not be sufficiently removed. On the other hand, if the spatial velocity (SV) is too slow, the treatment speed will decrease and the treatment time will increase.

[0047] The pH of the metal-containing solution when it is brought into contact with the resin is preferably 3.0 to 8.0. If the pH is too low or too high, the resin may be destroyed and may no longer function effectively.

[0048] The post-cleaning solution may have, for example, a lithium ion concentration of 1.0 g / L to 30.0 g / L, a fluoride ion concentration of 0.01 g / L to 5.0 g / L, a phosphorus concentration of 0.001 g / L to 1.0 g / L, and a silicon concentration of 0.001 g / L to 1.0 g / L.

[0049] (Elution Step) The resin used in the washing step has adsorbed thereon the above-mentioned impurity metal ions, which are metal ions derived from the battery powder, as ions to be adsorbed. In order to elute the ions to be adsorbed from the resin after the washing step and regenerate the resin, the resin can be subjected to an elution step as shown in FIG.

[0050] In the elution step, the resin is contacted with an acidic eluent to elute the target ions adsorbed to the resin. As a result, the target ions are transferred from the resin to a solution, and an eluted solution containing the target ions is obtained. The target ions correspond to the above-mentioned impurity metal ions and may include at least one selected from the group consisting of nickel ions, cobalt ions, manganese ions, and magnesium ions.

[0051] If the acidic eluent brought into contact with the resin in the elution step contains a mineral or inorganic acid such as sulfuric acid, hydrochloric acid, or nitric acid, the ions to be adsorbed can be effectively eluted from the resin with which it has been brought into contact.

[0052] In this embodiment, the acid solution obtained by electrodialysis in the electrodialysis step described below is used as at least a part of the acidic eluent. In the electrodialysis step, as will be described in detail later, a post-dialysis solution (lithium hydroxide solution), an acid solution, and a desalted solution are obtained after electrodialysis. While most of the lithium ions are contained in the post-dialysis solution, a small amount is also contained in the acid solution. The acid solution may also contain metal ions other than lithium ions. Discarding the acid solution containing such metal ions, such as lithium ions, would result in a loss of the metals. Therefore, the acid solution is used as at least a part of the acidic eluent in the elution step. In this case, the metal ions contained in the acid solution pass through the resin and are contained in the post-elution solution. Therefore, the post-elution solution contains not only the ions to be adsorbed but also the metal ions contained in the acid solution.

[0053] If this post-elution solution is recycled to the processes involved in leaching, separating, and recovering metals from the battery powder, it is possible to effectively recover or utilize the ions to be adsorbed and the metal ions contained in the acid solution. Specifically, nickel ions, cobalt ions, and manganese ions that may be included in the ions to be adsorbed may be separated and recovered in the metal separation process. Furthermore, lithium ions, one example of metal ions contained in the acid solution, can contribute to increasing the lithium ion concentration in the solution throughout the series of processes in the wet treatment. As a result, it is possible to suppress metal loss.

[0054] The post-elution solution is preferably returned to the acid leaching step, as described above, among the steps involved in leaching and separating and recovering metals from the battery powder, or may be returned to the stripping solution after at least one of the extractions described above for manganese extraction, cobalt extraction, and nickel extraction.

[0055] The acidic eluent can be composed of only an acid solution, or it may be a solution obtained by mixing an acid solution with a solution containing sulfuric acid, hydrochloric acid, nitric acid, or the like. The acid concentration of the acidic eluent when contacting the resin can be 1 M to 2 M. If the acid concentration of the acidic eluent is too low, there is a concern that the elution of the component to be eluted from the resin may be insufficient, while if the acid concentration is too high, the resin may be damaged, making it difficult to reuse. The elution step can be performed, for example, by passing the acidic eluent through the resin packed in a column.

[0056] The resin after the elution step is regenerated by separating the ions to be adsorbed, and can be reused in the next washing step.

[0057] (Pre-adsorption step) When a cation exchange resin and / or a chelating resin is used in the washing step, the resin may be subjected to a pre-adsorption step prior to the washing step.

[0058] In the pre-adsorption step, for example, an exchange ion-containing solution containing predetermined metal ions as exchange ions is passed through a column packed with a resin, thereby bringing the exchange ion-containing solution into contact with the resin and allowing the exchange ions to be adsorbed onto the resin.

[0059] The exchange ions are metal ions that exhibit an ion exchange action with the target ions to be adsorbed onto the resin in the cleaning process. When the exchange ions are lithium ions, when the resin with the adsorbed lithium ions comes into contact with the metal-containing solution containing the target ions in the cleaning process, ion exchange occurs between the lithium ions and the target ions to be adsorbed, so that the target ions to be adsorbed onto the resin and the lithium ions migrate into the metal-containing solution.

[0060] The resin that has undergone the pre-adsorption step is used in the washing step. As described above, the washing step can be followed by an elution step, and the resin that has undergone these washing and elution steps may be used repeatedly by being subjected to the pre-adsorption step and then a further washing step. Note that the resin may be washed with water such as pure water between the pre-adsorption step and the washing step, between the washing step and the elution step, and / or between the washing step and the elution step.

[0061] (Electrodialysis Step) The post-washing solution obtained in the washing step can be subjected to an electrodialysis step, in which electrodialysis is performed using, for example, a commercially available bipolar membrane electrodialysis device, and a lithium hydroxide solution is produced from the post-washing solution.

[0062] As an example, a bipolar membrane electrodialysis device 1 (hereinafter simply referred to as "electrodialysis device 1") shown in Figure 4 has an anode 2, a cathode 3, and a bipolar membrane 4, an anion exchange membrane 5, a cation exchange membrane 6, and a bipolar membrane 7 arranged in this order from the anode 2 side to the cathode 3 side between the anode 2 and the cathode 3. As a result, the interior of the cell is partitioned into a deionization chamber R1 between the anion exchange membrane 5 and the cation exchange membrane 6, an acid chamber R2 between the bipolar membrane 4 and the anion exchange membrane 5, and an alkaline chamber R3 between the cation exchange membrane 6 and the bipolar membrane 7. Each of the bipolar membranes 4 and 7 is constructed by stacking a cation exchange layer and an anion exchange layer.

[0063] To perform electrodialysis using the illustrated electrodialysis device 1, the post-wash solution is placed in the deionization compartment R1, and pure water is placed in each of the acid compartment R2 and alkaline compartment R3. A predetermined voltage is then applied between the anode 2 and the cathode 3. This causes the lithium ions (Li + ) passes through the cation exchange membrane 6 and moves to the alkaline chamber R3. In the alkaline chamber R3, water (HO) is decomposed by the bipolar membrane 7 to form hydroxide ions (OH - ) is present, a lithium hydroxide solution is obtained as the post-dialysis solution.

[0064] On the other hand, the anions of inorganic acids in the post-wash liquid in the deionization compartment R1 pass through the anion exchange membrane 5 and move to the acid compartment R2. In the acid compartment R2, the anions and hydrogen ions (H + ) produces an acid solution such as a sulfuric acid solution. As a result, the post-dialysis solution (lithium hydroxide solution) obtained in the alkaline chamber R3 contains almost no inorganic acid anions. In the illustrated example, the inorganic acid anions are sulfate ions (SO 2- ), but depending on the type of acid used in the acid leaching process, nitrate ions (NO3 - ) or chloride ions (Cl - ) may be.

[0065] In the deionization chamber R1, the lithium salt is separated from the post-wash solution as described above, and the deionized solution remains. The anion concentration of the inorganic acid tends to be higher in the acid solution than in the post-dialysis solution (lithium hydroxide solution), and also tends to be higher in the deionized solution than in the post-dialysis solution (lithium hydroxide solution).

[0066] The dialyzed solution (lithium hydroxide solution) obtained by electrodialysis can be effectively used as a pH adjuster in the metal separation step. After electrodialysis, the lithium ion concentration of the lithium hydroxide solution may be increased by heating or other methods, and then the resulting solution may be used as a pH adjuster.

[0067] The acid solution produced in the acid chamber R2 may contain small amounts of metal ions such as lithium ions. To prevent loss of such metals, the acid solution is not discarded but is used as at least a part of the acidic eluent in the elution step, as described above.

[0068] (Crystallization Step) A portion of the lithium hydroxide solution obtained in the electrodialysis step can be subjected to a crystallization step. For example, if the lithium hydroxide solution is returned to the wet treatment as a pH adjuster as described above, the lithium ion concentration in the solution may gradually increase due to the lithium in the battery powder newly added to the wet treatment. Depending on the lithium ion concentration, a crystallization step may be performed to recover lithium hydroxide.

[0069] In the crystallization step, a crystallization procedure such as heat concentration or vacuum distillation can be performed to precipitate lithium hydroxide. In the case of heat concentration, a higher temperature during crystallization is preferable because the process proceeds more quickly. However, after crystallization, the temperature during drying of the crystallized product is preferably less than 60°C, at which water of crystallization does not desorb. This is because anhydrous lithium hydroxide from which water of crystallization has been desorbed is deliquescent and therefore difficult to handle. The lithium hydroxide produced in the crystallization step may be subjected to a pulverization process or the like to adjust it to the required physical properties.

[0070] Next, tests related to the above-described metal recovery method were conducted and are described below. However, this description is for illustrative purposes only and is not intended to be limiting.

[0071] The battery powder was leached with sulfuric acid to obtain a metal-containing solution, which was then neutralized, followed by extraction of manganese, cobalt, and nickel, and washing using a chelating exchange resin (AMBERSEP 748UPS manufactured by Organo Corporation) to obtain a post-wash solution. The post-wash solution had a Li concentration of 19 g / L, a Ni concentration of 0.8 g / L, and a Mg concentration of 0.02 g / L.

[0072] The post-washing solution was then subjected to electrodialysis using a bipolar membrane electrodialysis device (manufactured by Astom Corporation) having the structure shown in Figure 4. Here, the post-washing solution was placed in the deionization compartment, and pure water was placed in the alkaline and acid compartments. The electrodialysis conditions were a constant voltage of 32 V.

[0073] The desalted solution obtained after electrodialysis had a Li concentration of 0.6 g / L to 1.0 g / L and a Na concentration of 0.01 g / L to 0.03 g / L, the post-dialysis solution (lithium hydroxide solution) had a Li concentration of 10 g / L to 30 g / L and a Na concentration of 0.1 g / L to 0.3 g / L, and the acid solution had a Li concentration of 0.6 g / L to 3.0 g / L and a Na concentration of <0.001 g / L to 0.01 g / L. Each solution also contained S, P, F, etc., but their concentrations were unknown.

[0074] It was found that the acid solution obtained by electrodialysis contained lithium ions. Therefore, it was suggested that the loss of lithium could be suppressed by using the acid solution as at least a part of the acidic eluent in the elution step and further recycling the resulting eluate to the steps involved in leaching, separating, and recovering the metals in the battery powder.

[0075] 1 Bipolar membrane electrodialysis device 2 Anode 3 Cathode 4, 7 Bipolar membrane 5 Anion exchange membrane 6 Cation exchange membrane R1 Deionization chamber R2 Acid chamber R3 Alkaline chamber

Claims

1. A method for leaching metals in battery powder from lithium-ion battery waste, and separating and recovering the metals from the resulting metal-containing solution, comprising an elution step of contacting a cation exchange resin and / or a chelating resin, onto which metal ions derived from the battery powder have been adsorbed as ions to be adsorbed, with an acidic eluent to elute the ions to be adsorbed from the cation exchange resin and / or chelating resin, and obtaining a post-elution solution containing the ions to be adsorbed; an acid solution containing metal ions obtained by electrodialysis is used as at least a part of the acidic eluent in the elution step, so that the post-elution solution contains the metal ions contained in the acid solution; and the post-elution solution is returned to and used in the steps involved in leaching, separating, and recovering the metals from the battery powder.

2. The metal recovery method according to claim 1, wherein the ions to be adsorbed include at least one selected from the group consisting of nickel ions, cobalt ions, manganese ions, and magnesium ions, and the metal ions in the acid solution include lithium ions.

3. A metal recovery method according to claim 1 or 2, which includes a washing step of washing the metal-containing solution to obtain a washed liquid by contacting the metal-containing solution with the cation exchange resin and / or chelating resin, and causing impurity metal ions in the metal-containing solution to be adsorbed onto the cation exchange resin and / or chelating resin as the ions to be adsorbed.

4. The metal recovery method according to claim 3, further comprising an electrodialysis step of subjecting the post-washing liquid to electrodialysis using a bipolar membrane to obtain at least the acid solution and the post-dialysis liquid.

5. A metal recovery method according to claim 3, which comprises a pre-adsorption step of contacting an exchange ion-containing solution containing, as exchange ions, metal ions that exhibit ion exchange activity with the ions to be adsorbed in the washing step with the cation exchange resin and / or chelating resin before the washing step, thereby adsorbing the exchange ions onto the cation exchange resin and / or chelating resin.

6. The metal recovery method of claim 5, wherein the exchange ions comprise lithium ions.

7. The metal recovery method according to claim 3, wherein the washing step is carried out after the elution step, and the cation exchange resin and / or chelating resin are used repeatedly.

8. A metal recovery method according to claim 1 or 2, comprising an acid leaching step in which the metal in the battery powder is brought into contact with an acidic leaching solution to obtain the metal-containing solution, and the post-elution solution is returned to and used in the acid leaching step among the steps involved in leaching and separating and recovering the metal in the battery powder.

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