Lithium recovery method and lithium recovery apparatus

Abstract

This provides a simpler way to recover lithium from waste energy storage devices containing lithium and polyvalent metals. [Solution] The lithium recovery method is a lithium recovery method for recovering lithium from waste of energy storage devices containing lithium and polyvalent metals, and includes a lithium recovery apparatus equipped with a cell having a raw material chamber between an anode and a cathode, an extraction chamber, and a monovalent selective cation permeable membrane separating the raw material chamber and the extraction chamber, and includes an extraction step in which lithium is extracted from an acidic raw material solution containing a leaching solution in which lithium and polyvalent metals contained in the waste are dissolved and leached out with mineral acid, contained in the raw material chamber, by passing an electric current between the anode and the cathode, into an acidic extract solution containing mineral acid contained in the extraction chamber.

Description

[Technical Field]

[0001] This disclosure relates to a lithium recovery method and a lithium recovery apparatus. [Background technology]

[0002] Conventionally, a method has been proposed for recovering lithium from lithium-ion battery waste by roasting the battery waste and then leaching the lithium into the leachate while finely grinding it using wet milling (see, for example, Patent Document 1). Another proposed method involves dissolving the active material powder of waste lithium-ion batteries in mineral acid, neutralizing it with lithium hydroxide, separating metals other than lithium contained in the active material powder by solvent extraction, and then obtaining lithium hydroxide by membrane electrolysis of the resulting lithium salt aqueous solution (see, for example, Patent Document 2). Furthermore, a method has been proposed for producing lithium hydroxide by placing a raw material liquid containing lithium carbonate or mineral oxide in a raw material chamber and generating lithium hydroxide in an alkaline chamber by electrodialysis (see, for example, Patent Documents 3 and 4). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2021-174676 [Patent Document 2] Japanese Patent Publication No. 2023-051705 [Patent Document 3] Japanese Patent Publication No. 2013-173629 [Patent Document 4] Japanese Patent Publication No. 2014-173144 [Overview of the project] [Problems that the invention aims to solve]

[0004] However, in Patent Document 1, it was essential to perform roasting at a high temperature of 550°C to 900°C for 4 to 8 hours in order to change lithium into a form such as lithium oxide or lithium carbonate that is easily soluble in water or the like. Further, in Patent Documents 2 to 4, lithium was recovered by membrane electrolysis or electrodialysis of a solution containing no metal other than lithium. When recovering lithium from waste of a power storage device, it was necessary to remove metals other than lithium before membrane electrolysis or electrodialysis, for example, as shown in Patent Document 2.

[0005] The present disclosure has been made to solve such problems, and the main object is to provide a novel recovery method and recovery device capable of more easily recovering lithium from waste of a power storage device containing lithium and a polyvalent metal.

Means for Solving the Problems

[0006] In order to achieve the above object, the inventors of the present invention conducted intensive research. Then, using a lithium recovery device including a cell having a raw material chamber, an extraction chamber, and a monovalent selective cation permeable membrane separating the raw material chamber and the extraction chamber between an anode and a cathode, by flowing an electric current between the anode and the cathode, from an acidic raw material liquid containing a leaching liquid obtained by dissolving and leaching lithium and polyvalent metals contained in the waste of the power storage device with a mineral acid, it was found that lithium can be more easily recovered, and the invention disclosed in this specification was completed.

[0007] That is, the lithium recovery method of the present disclosure is using a lithium recovery device including a cell having a raw material chamber, an extraction chamber, and a monovalent selective cation permeable membrane separating the raw material chamber and the extraction chamber between an anode and a cathode, and flowing an electric current between the anode and the cathode, from an acidic raw material liquid containing a leaching liquid obtained by dissolving and leaching lithium and polyvalent metals contained in the waste accommodated in the raw material chamber with a mineral acid, extracting lithium into an acidic extraction liquid containing a mineral acid accommodated in the extraction chamber, and includes an extraction step.

[0008] Further, the lithium recovery device of the present disclosure is A lithium recovery device for recovering lithium from waste of a power storage device containing lithium and polyvalent metals, comprising: a cell having a raw material chamber and an extraction chamber between an anode and a cathode, and a monovalent-selective cation-permeable membrane separating the raw material chamber and the extraction chamber; a raw material liquid supply unit for supplying an acidic raw material liquid containing a leaching liquid obtained by dissolving and leaching lithium and polyvalent metals contained in the waste with a mineral acid to the raw material chamber; an extraction liquid supply unit for supplying an acidic extraction liquid containing a mineral acid to the extraction chamber; a control unit for flowing an electric current between the anode and the cathode so as to extract lithium from the raw material liquid stored in the raw material chamber into the extraction liquid stored in the extraction chamber; and the above components.

Advantages of the Invention

[0009] In the present disclosure, lithium can be recovered more simply from waste of a power storage device containing lithium and polyvalent metals. The reason for obtaining such an effect is presumed as follows. For example, since a monovalent-selective cation-permeable membrane is used for the cation-permeable membrane separating the raw material chamber and the extraction chamber, lithium, which is a monovalent metal, can be selectively extracted to the extraction chamber side from the raw material liquid containing lithium and polyvalent metals. Here, even when a monovalent-selective cation-permeable membrane is used, polyvalent metals may slightly permeate. If the extraction chamber side tends to be basic, there is a possibility that a hydroxide of a polyvalent metal may crystallize on the cation-permeable membrane, causing problems in lithium recovery. However, in the present disclosure, since the extraction liquid stored in the extraction chamber is acidic, crystallization of a hydroxide of a polyvalent metal on the cation-permeable membrane can be suppressed. Therefore, it is presumed that lithium can be recovered simply using an electrochemical method from waste of a power storage device containing lithium and polyvalent metals without performing roasting at a high temperature or the like. In addition, in the present disclosure, even after roasting at a high temperature, lithium can be recovered simply using an electrochemical method.

Brief Description of the Drawings

[0010] [Figure 1]A diagram conceptually illustrating the extraction process using the lithium recovery device 10. [Figure 2] A flowchart showing an example of a lithium recovery flow. [Figure 3] A graph showing the changes over time in lithium recovery rate, lithium purity, and Coulomb efficiency. [Figure 4] Graphs showing the change in Li ion concentration in the extraction chamber in experimental examples 2-4. [Figure 5] Graphs showing the change in Li recovery rate in experimental examples 2-4. [Figure 6] Graphs showing the change in Coulomb efficiency in experimental examples 2-4. [Figure 7] Graphs showing extraction rate and Li purity in experimental examples 2-4. [Modes for carrying out the invention]

[0011] [Lithium recovery method] Preferred embodiments of the lithium recovery method of the present disclosure will be described below. This lithium recovery method is for recovering lithium from waste of energy storage devices containing lithium and polyvalent metals, and includes a lithium recovery apparatus equipped with a cell having a raw material chamber between an anode and a cathode, an extraction chamber, and a monovalent selective cation permeable membrane separating the raw material chamber and the extraction chamber, and includes an extraction step of extracting lithium from an acidic raw material solution containing a leaching solution in which lithium and polyvalent metals contained in the waste are dissolved and leached out with mineral acid, contained in the raw material chamber by passing an electric current between the anode and the cathode, into an acidic extract solution containing mineral acid contained in the extraction chamber.

[0012] The waste of the power storage device only needs to contain lithium and polyvalent metals. For example, the waste of lithium-ion secondary batteries and hybrid capacitors can be cited. The waste of the power storage device preferably contains an electrode active material. For example, it may be an electrode taken out from the power storage device or its crushed material, or an electrode active material separated from the electrode, or black mass produced in the recycling process of the power storage device. The electrode active material is preferably a positive electrode active material. For example, sulfides containing transition metal elements, composite oxides containing lithium and transition metal elements, etc. can be cited. Specifically, transition metal sulfides such as TiS2, TiS3, MoS3, FeS2, the basic composition formula is Li (1-x) MnO2 (0 < x < 1, etc., the same below), and lithium manganese composite oxides such as Li (1-x) Mn2O4, etc., lithium cobalt composite oxides with the basic composition formula of Li (1-x) CoO2, etc., lithium nickel composite oxides with the basic composition formula of Li (1-x) NiO2, etc., lithium nickel cobalt manganese composite oxides with the basic composition formula of Li (1-x) Ni a Co b Mn c O2 (a + b + c = 1), etc., lithium vanadium composite oxides with the basic composition formula of LiV2O3, transition metal oxides with the basic composition formula of V2O5, etc. can be used. Also, the electrode active material may be, for example, lithium iron phosphate (LiFePO4: LFP), etc. Specifically, the electrode active material is, for example, LFP, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (NCM111), LiNi 0.5 Co 0.3 Mn 0.2 O2 (NCM532), LiNi 0.6 Co 0.2 Mn 0.2 O2 (NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O2 (NCM811), LiNi 0.5 Mn 1.5Examples include O4 and LiMn2O4. Note that the term "basic composition formula" means that other elements may be included. Examples of polyvalent metals include one or more of Ni, Co, Mn, Fe, and Cu. Black mass may be produced, for example, in a recycling process by crushing and wet refining, or it may be obtained by deactivating energy storage devices, followed by roasting, crushing, and separation. Black mass is a black powder containing electrode active material, and may contain valuable metals such as cobalt, nickel, manganese, and lithium.

[0013] (extraction process) In the extraction process, lithium is extracted from the raw material solution using a lithium recovery device. The lithium recovery device comprises a cell having a raw material chamber, an extraction chamber, and a monovalent selective cation permeable membrane separating the raw material chamber and the extraction chamber, between the anode and the cathode. The raw material chamber is located on the anode side, and the extraction chamber is located on the cathode side. The raw material chamber contains the raw material solution, and the extraction chamber contains the extract. Preferably, this lithium recovery device further comprises an anode chamber separated from the raw material chamber by a bipolar membrane and containing a conductive anolyte, and a cathode chamber separated from the extraction chamber by a bipolar membrane and containing a conductive cathode. The anode may be positioned in the anode chamber so as to be in contact with the anolyte, and the cathode may be positioned in the cathode chamber so as to be in contact with the cathode. The anode may also be an oxygen generation electrode, for example, Ti-IrO2 can be suitably used. The cathode may also be a hydrogen generation electrode, for example, Pt or Ni can be suitably used. A bipolar membrane is a composite membrane having a structure in which an anion exchange layer and a cation exchange layer are bonded together, and has the function of dissociating water into hydrogen ions and hydroxide ions. In the bipolar membrane between the anode chamber and the raw material chamber, the anion exchange layer is located on the anode chamber side and the cation exchange layer is located on the raw material chamber side. In the bipolar membrane between the extraction chamber and the cathode chamber, the anion exchange layer is located on the extraction chamber side and the cation exchange layer is located on the cathode chamber side. Preferably, this lithium recovery device further includes a raw material liquid supply path for supplying raw material liquid to the raw material chamber, a raw material liquid recovery path for recovering raw material liquid from the raw material chamber, an extractant supply path for supplying extractant to the extraction chamber, and an extractant recovery path for recovering extractant from the extraction chamber. If such supply and recovery paths are provided, lithium can be recovered in a continuous manner rather than in a batch manner. The raw material liquid recovery path may be connected to the raw material liquid supply path and configured to circulate the raw material liquid. Similarly, the extractant recovery path may be connected to the extractant supply path and configured to circulate the extractant.

[0014] In the extraction process, an acidic solution containing a leaching solution obtained by dissolving and extracting lithium and polyvalent metals contained in the waste of the energy storage devices mentioned above with a mineral acid is used as the raw material solution. Suitable mineral acids include sulfuric acid, hydrochloric acid, and nitric acid. The concentration of the mineral acid in the raw material solution may be, for example, 0.1 M (mol / L) or more and 2 M or less. The raw material solution may also be, for example, a leaching solution obtained by dissolving and extracting lithium and polyvalent metals with a mineral acid of 1 M to 5 M, diluted with water or the like. The leaching solution and its dilution may be used after removing any remaining hydrogen peroxide by boiling or the like. It is desirable to remove hydrogen peroxide beforehand, as it can degrade the ion exchange membrane. The leaching solution may also be, for example, a strongly acidic solution obtained by dissolving and extracting cobalt, nickel, manganese, lithium, etc., with sulfuric acid to which hydrogen peroxide has been added. The pH of the raw material solution is preferably set to a value where hydroxides of polyvalent metals (Co, Ni, Mn, etc., especially Ni) contained in the waste of the energy storage devices do not crystallize; for example, it may be 5 or less. The pH of the raw material solution may be 0.2 or higher, 1 or higher, 2 or higher, or 3 or higher. The raw material solution may be pH-adjusted with a pH adjusting agent. For example, setting the pH to 2 or higher can further increase the current efficiency (Coulomb efficiency) and extraction speed. From the viewpoint of suppressing the inclusion of dissimilar metals, it is preferable that the pH adjusting agent does not contain metals other than those contained in the waste of energy storage devices. The pH adjusting agent may be, for example, a hydroxide, or a hydroxide of a metal contained in the waste of energy storage devices. For example, if the waste of energy storage devices contains lithium nickel cobalt manganese composite oxide, the pH adjusting agent may be one or more of lithium hydroxide, nickel hydroxide, cobalt hydroxide, and manganese hydroxide. From the viewpoint of preventing the inclusion of impurities, it is desirable that the pH adjusting agent does not contain sodium hydroxide. The pH adjusting agent may be used as a solution by dissolving it in a solvent such as water. The concentration of the pH adjusting agent in this solution may be, for example, 1 mol / L or more and 5 mol / L or less.

[0015] In the extraction process, an acidic solution containing a mineral acid is used as the extractant. Suitable mineral acids include sulfuric acid, hydrochloric acid, and nitric acid. The lithium salts of these acids have high solubility, allowing for a higher lithium concentration in the extractant and thus efficient lithium recovery. Regarding solubility in water, Li2SO4 can dissolve up to 25.6g per 100g of solution at 25°C, and LiNO3 can dissolve up to 100cm³ at 0°C. 3 Up to 53.4 g of LiCl can be dissolved in water, and up to 55 g of LiCl can be dissolved in 100 g of solution at 25°C. The mineral acid contained in the extract may be the same or different type as the mineral acid contained in the raw material solution. The concentration of the mineral acid in the extract may be, for example, 0.1 M or more and 1 M or less. The pH of the extract is preferably less than 5, but may be 4 or less, or 2 or less. The pH of the extract may be 0.1 or more, or 0.2 or more. In the extraction process, for example, the pH of the extract may rise due to the generation of LiOH as Li is recovered, and consequently, polyvalent metal hydroxides may crystallize on the cation permeable membrane or bipolar membrane, which can cause a decrease in the extraction rate. Therefore, from the viewpoint of preventing hydroxide crystallization, it is desirable that the extract be kept acidic until the extraction is completed, and it is desirable to increase the acid concentration above the target Li recovery concentration.

[0016] In the extraction process, conductive liquids, such as solutions containing electrolytes or mineral acids (electrolytes), can be used as the anolyte contained in the anode chamber and the cathode liquid contained in the cathode chamber (hereinafter collectively referred to as electrode liquids). The electrode liquid may be, for example, an aqueous lithium sulfate solution. The electrode liquid may be selected according to the electrode used. For example, when nickel or iron is used as the anode, an aqueous lithium hydroxide solution can be suitably used as the anolyte; when lead is used as the anode, an aqueous sulfuric acid solution can be suitably used as the anolyte; when platinum is used as the anode, an aqueous sulfuric acid or lithium sulfate solution can be suitably used as the anolyte; and when graphite is used as the anode, an aqueous lithium chloride solution can be suitably used as the anolyte. Furthermore, when nickel, iron, stainless steel (SUS), etc., are used as the cathode, for example, aqueous lithium hydroxide solution, aqueous lithium sulfate solution, or aqueous lithium chloride solution can be suitably used as the cathode liquid. From the viewpoint of suppressing the inclusion of impurities, it is preferable that the electrode liquid does not contain metals other than those contained in the waste of energy storage devices. In the electrode solution, the concentration of the electrolyte and mineral acid may be, for example, 0.1 M or more and 1 M or less, or it may be around 0.25 M.

[0017] In the extraction process, the raw material liquid is placed in the raw material chamber, the extract in the extraction chamber, the anode liquid in the anode chamber, and the cathode liquid in the cathode chamber, and an electric current is passed between the anode and the cathode. The current can be controlled by, for example, constant current control or constant voltage control. The current and voltage should be set appropriately according to the scale and configuration of the lithium recovery system, the composition of the raw material liquid and extract, etc. The current density is, for example, 2.5 mA / cm². 2 The above or 10mA / cm 2 The above is also acceptable, 200mA / cm 2 The following and 100mA / cm 2The following may also be used. The voltage may be, for example, 1V or more, 2V or more, or 5V or less. When the film structure is used by stacking it as a repeating structure, the applied voltage may be increased by multiplication by the number of times the film structure is repeated. In this extraction process, the raw material liquid may be circulated in the raw material chamber and the extract may be circulated in the extraction chamber while current is passed between the anode and the cathode. It is preferable to carry out this extraction process under conditions in which crystallization does not occur in the extraction chamber. For example, the energizing time may be adjusted so that the concentration of mineral acid and salts of lithium or polyvalent metals contained in the extract does not exceed the solubility in the extract.

[0018] Figure 1 shows a conceptual diagram illustrating an extraction process using a lithium recovery device 10 as an example of an extraction process. In this extraction process, a leaching solution obtained by dissolving lithium and divalent metal M in an H2SO4 aqueous solution is used as the raw material solution, and the H2SO4 aqueous solution is used as the extractant solution. The lithium recovery device 10 has a cell 20. The cell 20 has an anode 21 and a cathode 22, and has a structure consisting of four chambers arranged in the order of anode chamber 30, raw material chamber 40, extraction chamber 50, and cathode chamber 60 from the anode 21 side. Control units (not shown) are connected to the anode 21 and cathode 22, and it is possible to pass an electric current between the anode 21 and cathode 22. The cell 20 may also function as an electrodialysis cell. A bipolar membrane 23 is arranged between the anode chamber 30 and the raw material chamber 40 such that the anion exchange layer is on the anode chamber 30 side and the cation exchange layer is on the raw material chamber 40 side. A monovalent selective cation permeable membrane 24 is positioned between the raw material chamber 40 and the extraction chamber 50. A bipolar membrane 25 is positioned between the extraction chamber 50 and the cathode chamber 60 such that the anion exchange layer is on the extraction chamber 50 side and the cation exchange layer is on the cathode chamber 60 side. An anode chamber 30 is connected to an anode liquid supply passage 32 and an anode liquid recovery passage 33, and is configured to allow anode liquid to flow through the anode chamber 30. A pump 35 is also provided in the anode liquid supply passage 32, and the anode liquid in the anode chamber 30 is recovered to a tank 31 via the anode liquid recovery passage 33, and after the pH etc. is adjusted in the tank 31, it is supplied back to the anode chamber 30 via the anode liquid supply passage 32. A raw material liquid supply passage 42 and a raw material liquid recovery passage 43 are connected to the raw material chamber 40, and is configured to allow raw material liquid to flow through the raw material chamber 40. Furthermore, a branching channel 44 is provided in the raw material liquid recovery channel 43, and a pump 45 is provided in the raw material liquid supply channel 42. Part or all of the raw material liquid in the raw material chamber 40 is recovered into the tank 41 via the raw material liquid recovery channel 43 and the branching channel 44, and after the pH and other parameters are adjusted in the tank 41, it is supplied back to the raw material chamber 40 via the raw material liquid supply channel 42. The extraction chamber 50 is connected to an extract supply channel 52 and an extract recovery channel 53, and is configured to allow the extract to flow through the extraction chamber 50.Furthermore, a branching path 54 is provided in the extract recovery path 53, and a pump 55 is provided in the extract supply path 52. Part or all of the extract in the extraction chamber 50 is recovered to the tank 51 via the extract recovery path 53 and the branching path 54, and after the pH and other parameters are adjusted in the tank 51, it is supplied back to the extraction chamber 50 via the extract supply path 52. The cathode chamber 60 is connected to a cathode liquid supply path 62 and a cathode liquid recovery path 63, and is configured so that cathode liquid flows through the cathode chamber 60. Furthermore, a pump 65 is provided in the cathode liquid supply path 62, and the cathode liquid in the cathode chamber 60 is recovered to the tank 61 via the cathode liquid recovery path 63, and after the pH and other parameters are adjusted in the tank 61, it is supplied back to the cathode chamber 60 via the cathode liquid supply path 62.

[0019] Using the lithium recovery apparatus 10 described above, when anolyte is passed through the anode chamber 30, raw material liquid through the raw material chamber 40, extractant liquid through the extraction chamber 50, and cathode liquid through the cathode chamber 60, and an electric current is passed between the anode 21 and the cathode 22, ions move using the energy from oxygen generation at the anode 21 and hydrogen generation at the cathode 22 as the driving force. Specifically, H produced by the dissociation of water in the anode chamber 30 + The material is supplied to the raw material chamber 40 through the bipolar membrane 23, and the OH produced by the dissociation of water in the cathode chamber 60 - The Li permeates through the bipolar membrane 25 and is supplied to the extraction chamber 50, and consequently, the Li in the raw material chamber 40 + Ya M 2+ It moves towards extraction chamber 50. + Ya M 2+ When it reaches the monovalent selective cation permeable membrane 24, Li + The ions selectively permeate and move to the extraction chamber 50. This allows for the selective extraction of lithium into the extraction chamber 50. The extract in the extraction chamber 50 from which lithium has been extracted is a Li2SO4 aqueous solution, and lithium can be recovered in the form of a Li2SO4 aqueous solution. Incidentally, although the cation permeable membrane 24 is monovalent, the M in the raw material chamber 40 2+A small amount of liquid may permeate through. If the extraction chamber 50 is alkaline, M(OH)2 may crystallize on the cation permeable membrane 24, which can cause problems in lithium recovery. However, in this extraction process, the extractant in the extraction chamber 50 is acidic, so the crystallization of M(OH)2 on the cation permeable membrane 24 can be suppressed. Therefore, lithium can be easily recovered from waste of energy storage devices containing lithium and divalent metal M using an electrochemical method.

[0020] (Processes other than the extraction process) The lithium recovery method may include steps other than the extraction step. For example, a raw material preparation step may be performed prior to the extraction step to prepare the raw material solution. In the raw material preparation step, acid leaching may be performed to obtain a leaching solution by dissolving and leaching lithium and polyvalent metals from waste of energy storage devices with mineral acid, and further adjustments such as boiling, dilution, and pH adjustment may be performed on the leaching solution.

[0021] In a lithium recovery method, a polyvalent metal recovery step may be performed in parallel with an extraction step for selectively extracting Li, in which polyvalent metals are recovered from the raw material liquid after Li recovery. In the polyvalent metal recovery step, polyvalent metals may be recovered individually by solvent extraction or the like.

[0022] In the lithium recovery method, a purification step may be performed to increase the purity of the Li extract obtained in the extraction step. In the purification step, for example, polyvalent metal components may be selectively crystallized by pH adjustment, and the polyvalent metal components may be removed by solid-liquid separation to increase the purity of the Li extract. In the purification step, for example, lithium purity may be increased by generating precipitates of cobalt, nickel, and manganese with oxalic acid and removing them by solid-liquid separation. In the purification step, for example, lithium purity may be increased by generating precipitates of cobalt, nickel, and manganese hydroxides and removing them by solid-liquid separation. The polyvalent metal components removed by solid-liquid separation can be dissolved in a leaching solution and used again in the extraction step to recover them without loss. In the lithium recovery method, a LiOH conversion step may be performed on the Li extract purified in the purification step, for example, by performing electrodialysis as shown in Patent Document 4 to generate LiOH. In this way, Li can be recovered in the form of LiOH, which is suitable as a raw material for active materials. Furthermore, in the electrodialysis method described in Patent Document 4, not only LiOH but also mineral acid is produced, making it possible to regenerate mineral acid as well.

[0023] Figure 2 shows an example of a lithium recovery flow for a lithium recovery method that includes steps other than the extraction step. In this recovery flow, the extraction step is performed using the lithium recovery apparatus 10 described above, and a leaching solution obtained by dissolving and leaching lithium and divalent metal M in an H2SO4 aqueous solution is used as the raw material solution, and the H2SO4 aqueous solution is used as the extractant solution. First, lithium and divalent metal M are dissolved and leached (acid leaching) from the waste 70 of the energy storage device with sulfuric acid to prepare a leaching solution 71. Then, the leaching solution 71 is subjected to one or more of the following adjustments: boiling, dilution, and pH adjustment to prepare the raw material solution 72 (raw material solution preparation step). In the raw material solution preparation step, impurities may be crystallized by pH adjustment, etc., and the raw material solution 72 from which impurities have been removed by filtration may also be prepared. Next, Li is selectively extracted from the raw material solution 72 by electrodialysis using the lithium recovery apparatus 10 to obtain a Li extractant solution 73 (extraction step). In parallel with this, the raw material solution after Li recovery, the extracted raw material solution 74, is recovered, and the divalent metal M contained in the extracted raw material solution 74 is individually recovered by solvent extraction or the like (multivalent metal recovery step). The Li extract 73 obtained in the extraction step is an aqueous Li2SO4 solution, but it may contain a small amount of divalent metal M that has permeated through the cation permeable membrane 24. In order to remove such divalent metal M, the divalent metal M is crystallized as MSO4 crystals 76 or the like by pH adjustment, and then solid-liquid separation is performed to remove M 2+ A Li2SO4 aqueous solution 75 is obtained from which SO4 has been removed (purification step). The MSO4 crystals 76 obtained by solid-liquid separation are dissolved in a leaching solution and used again in the extraction step. Finally, the purified Li2SO4 aqueous solution 75 is subjected to electrodialysis as shown in Patent Document 4 to remove SO4 from the Li2SO4 aqueous solution 75. 2- The substance is removed to produce LiOH77 (LiOH conversion step). This allows lithium to be recovered in the form of LiOH. Alternatively, instead of the LiOH conversion step, Li2CO3 may be produced by adding Na2CO3 to a highly purified Li2O4 aqueous solution 75. In this way, lithium can be recovered in the form of Li2CO3.

[0024] [Lithium recovery device] The lithium recovery apparatus is a lithium recovery apparatus for recovering lithium from waste energy storage devices containing lithium and polyvalent metals, and comprises a cell having a raw material chamber, an extraction chamber, and a monovalent selective cation permeable membrane separating the raw material chamber and the extraction chamber between an anode and a cathode; a raw material supply unit that supplies an acidic raw material solution containing a leaching solution obtained by dissolving and leaching lithium and polyvalent metals contained in the waste with a mineral acid to the raw material chamber; an extraction solution supply unit that supplies an acidic extraction solution containing a mineral acid to the extraction chamber; and a control unit that passes an electric current between the anode and the cathode to extract lithium from the raw material solution contained in the raw material chamber into the extraction solution contained in the extraction chamber. This lithium recovery apparatus is configured to perform the lithium recovery method described above. The control unit may be configured as a controller that controls the entire apparatus.

[0025] This lithium recovery device may be the lithium recovery device 10 described above. The raw material supply unit is, for example, the tank 41 described above, and the extract supply unit is, for example, the tank 51 described above. The control unit, although not shown in the figures, is connected to the anode 21 and the cathode 22 and is configured to extract lithium from the raw material supply unit in the raw material chamber 40 into the extract supply unit in the extract chamber 50. The control unit may be connected to a raw material supply unit adjustment device (not shown) provided in tank 41, or an extract supply unit adjustment device (not shown) provided in tank 51, and is configured to adjust the composition and pH of the raw material supply unit and the extract supply unit. The control unit may also be connected to pumps 45 and 55 and is configured to control the supply amount of the raw material supply unit and the extract supply unit.

[0026] In the embodiments described above, as mentioned above, lithium can be recovered more easily from waste energy storage devices containing lithium and polyvalent metals. Furthermore, a "lithium-first" approach, in which lithium is extracted before polyvalent metals, can be achieved.

[0027] It goes without saying that this disclosure is not limited in any way to the embodiments described above, and can be implemented in various forms as long as they fall within the technical scope of the present invention.

[0028] This disclosure may be any of the following [1] to [7]. [1] A lithium recovery method for recovering lithium from waste of energy storage devices containing lithium and polyvalent metals, comprising: a lithium recovery apparatus having a cell having a raw material chamber, an extraction chamber, and a monovalent selective cation permeable membrane separating the raw material chamber and the extraction chamber between an anode and a cathode, wherein an extraction step is performed by passing an electric current between the anode and the cathode to extract lithium from an acidic raw material solution containing a leaching solution in which lithium and polyvalent metals contained in the waste are dissolved and leached with a mineral acid, contained in the raw material chamber, into an acidic extract solution containing a mineral acid contained in the extraction chamber. [2] The lithium recovery method according to [1], wherein in the extraction step, the raw material liquid is circulated in the raw material chamber, and while the extract is circulated in the extraction chamber, an electric current is passed between the anode and the cathode. [3] The lithium recovery method according to [1] or [2], wherein in the extraction step, a sulfuric acid solution is used as the extractant. [4] The lithium recovery method according to any one of [1] to [3], wherein the extraction step is carried out under conditions in which crystallization does not occur in the extraction chamber. [5] The lithium recovery method according to any one of [1] to [4], wherein in the extraction step, a solution with a pH of 2 or higher and a pH of 5 or lower is used as the raw material solution. [6] The lithium recovery method according to any one of [1] to [5], wherein in the extraction step, a solution containing a hydroxide which is one or more of the hydroxides of lithium and polyvalent metals as a pH adjuster is used as the raw material solution. [7] A lithium recovery apparatus for recovering lithium from waste of energy storage devices containing lithium and polyvalent metals, comprising: a cell having a raw material chamber, an extraction chamber, and a monovalent selective cation permeable membrane separating the raw material chamber and the extraction chamber between an anode and a cathode; a raw material supply unit for supplying an acidic raw material solution containing a leaching solution obtained by dissolving and leaching lithium and polyvalent metals contained in the waste with a mineral acid to the raw material chamber; an extractant supply unit for supplying an acidic extractant containing a mineral acid to the extraction chamber; and a control unit for passing an electric current between the anode and the cathode to extract lithium from the raw material solution contained in the raw material chamber into the extractant contained in the extraction chamber. [Examples]

[0029] The following describes specific examples of the lithium recovery method described herein. Experimental Examples 1 to 4 all correspond to examples. It goes without saying that this disclosure is not limited in any way to the following examples and can be implemented in various forms as long as they fall within the technical scope of this disclosure.

[0030] [Experimental Example 1] To a 2M sulfuric acid solution to which hydrogen peroxide has been added to a concentration of 3 wt%, the positive electrode active material LiNi of the battery was added to a concentration of 0.5 mol / L. 0.33 Co 0.33 Mn 0.33 The raw material solution was prepared by dissolving the substance, removing residual hydrogen peroxide by boiling, and then diluting the solution twice. A 0.25 M sulfuric acid solution was prepared as the extract. In addition, a 0.25 M Li2SO4 solution adjusted to pH=2 was prepared as the electrode solution.

[0031] As a lithium recovery system, an electrodialysis electrolytic cell (effective membrane area 1cm x 4cm, chamber frame thickness 3mm, 4 chambers) was prepared. The raw material solution was placed in the raw material solution tank, the extract solution in the extract solution tank, and the electrode solution in the electrode solution tank. The raw material solution was placed in the raw material solution chamber, the extract solution in the extract solution chamber, and the electrode solution in the anode and cathode chambers, and these were circulated to each chamber at a rate of 30 mL / min using a liquid transfer pump (Takumina Co., Ltd., QI-100). As the monovalent selective cation permeable membrane, CXP-S manufactured by Astom Co., Ltd. was used. As the bipolar membrane, a bipolar membrane (BPU) manufactured by Astom Co., Ltd. was used. The current flow rate was 12.5 mA / cm². 2 Electrodialysis was performed by applying current at the specified current density for a total of 18 hours. At 6, 12, and 18 hours of operation of the electrodialysis machine, the pH of the raw material solution in the raw material chamber was measured, and the extract from the extraction chamber was sampled and measured for ICP.

[0032] [Results and Discussion] Table 1 summarizes the operating time of the electrodialysis machine in Experimental Example 1, the pH of the raw material solution in the raw material chamber, the cell voltage, the Li ion concentration of the extract in the extraction chamber, and the Li recovery rate and purity. Table 2 summarizes the elemental concentrations in the extract measured by ICP in Experimental Example 1. Figure 3 summarizes the time course of the lithium recovery rate, purity, and Coulomb efficiency in Experimental Example 1.

[0033] In Experimental Example 1, electrodialysis resulted in an increase in the Li concentration in the recovered solution to 0.08 mol / L, recovering approximately 30% of the Li from the raw material solution. Furthermore, ICP measurement of the elemental concentrations in the recovered solution revealed that the proportion of Li (Li purity) was over 80%. It was estimated that the recovery rate could be increased to approximately 100% by further extending the electrolysis time or using a larger cell.

[0034] [Table 1]

[0035] [Table 2]

[0036] Experimental examples 2-4 were used to investigate the effect of pH on the raw material solution. [Experimental Example 2] In preparing the raw material solution, hydrogen peroxide was added to 2M sulfuric acid to a concentration of 3 wt%, and then LiNi, the positive electrode active material of the battery, was added to a concentration of 0.5 mol / L. 0.33 Co 0.33 Mn 0.33 The solution obtained by dissolving the compound and removing residual hydrogen peroxide by boiling was used as the stock solution. A 0.5 M sulfuric acid solution was used as the extract. Electrodialysis was performed with a current density of 20 mA / cm for a total of 17 hours. The procedure was the same as in Experimental Example 1, except for the conditions other than those mentioned above, and the timing of pH measurement of the raw material solution in the raw material chamber and ICP measurement of the extract taken from the extraction chamber were changed.

[0037] [Experimental Example 3] The procedure was the same as in Experiment 2, except that a solution was prepared by dissolving lithium sulfate monohydrate, cobalt(II) sulfate heptahydrate, nickel(II) sulfate hexahydrate, and manganese(II) sulfate pentahydrate in water to a concentration of 0.17 mol / L each, and then adding a small amount of 9M sulfuric acid to adjust the pH to 2. Electrodialysis was performed for a total of 24 hours.

[0038] [Experimental Example 4] The procedure was the same as in Experimental Example 2, except that a solution prepared by dissolving lithium sulfate monohydrate, cobalt(II) sulfate heptahydrate, nickel(II) sulfate hexahydrate, and manganese(II) sulfate pentahydrate in water to a concentration of 0.17 mol / L was used as the raw material solution, and electrodialysis was performed for a total of 24 hours.

[0039] [Results and Discussion] ICP measurements were performed on the raw material solutions of Experimental Examples 2-4 to confirm the concentrations of the contained elements, and the results are summarized in Table 3. It was confirmed that the raw material solutions of Experimental Examples 2-4 contained Li, Ni, Co, and Mn in similar proportions and concentrations.

[0040] Figure 4 and Table 4 summarize the Li ion concentrations in the extraction chambers for Experimental Examples 2-4. Figure 5 and Table 4 summarize the Li recovery rates for Experimental Examples 2-4. In Experimental Example 3, which used a pH 2 raw material solution, the Li concentration in the extraction chamber could be increased to 0.32 mol / L (recovery rate 40%), and in Experimental Example 4, which used a pH 5 raw material solution, it could be increased to 0.41 mol / L (recovery rate 46%). It was inferred that the recovery rate could be increased to approximately 100% by further extending the energizing time or using a larger cell.

[0041] Figure 6 and Table 4 summarize the Coulomb efficiencies in Experimental Examples 2-4. As extraction progressed, the pH of the stock solution decreased, and consequently, the Coulomb efficiency gradually decreased. This was presumed to be because protons dissociated on the bipolar membrane were supplied into the stock solution as charge compensation for the movement of lithium.

[0042] Figure 7 and Table 4 summarize the extraction rate and Li purity in Experimental Examples 2-4. The extraction rate indicates the increase in Li concentration per unit membrane area per hour from the start of extraction to the end of extraction (17 hours in Experimental Example 2, and 24 hours in Experimental Examples 3 and 4). Compared to Experimental Example 2, which used a pH 0 raw material solution, the extraction rate in Experimental Example 3, which used a pH 2 raw material solution, was approximately 2.7 times higher, and in Experimental Example 4, which used a pH 5 raw material solution, the extraction rate was approximately 3.2 times higher. H is present in the monovalent selective cation membrane. + and Li + It is possible for it to permeate, and as the pH increases, the proton concentration decreases, Li + H for transmission + It was inferred that competition between elements decreased, leading to increased Li permeation and improved extraction speed. Furthermore, when the elemental concentrations in the recovered solution were examined by ICP measurement, the Li purity was over 70% in Experimental Example 3, which used a raw material solution with a pH of 2, and over 90% in Experimental Example 4, which used a raw material solution with a pH of 5. The reason why the purity of Experimental Example 3 was lower than that of Experimental Example 4 is unknown, but it was found that the highest effect can be expected by raising the pH to around 5, from the perspective of both the purity of recovered Li and the recovery speed (extraction speed).

[0043] In Experimental Examples 2-4, the elemental concentrations in the raw material solution were kept nearly constant, and a model solution was used for the raw material solution to investigate only the effect of pH changes. The pH of the actual leaching solution can be adjusted, for example, by adding lithium hydroxide solution (concentration of approximately 4 mol / L) dropwise to the leaching solution using a pH controller. Since actual leaching solutions may contain impurities such as Al, Fe, and Cu, precipitation may occur during pH adjustment. In such cases, the filtered solution may be used as the raw material solution. Furthermore, as the pH increases, polyvalent metals (e.g., Co, Ni, Mn) are more likely to crystallize as hydroxides. In particular, Ni hydroxide precipitation begins around pH 5, so it was inferred that pH adjustment should be kept below this range.

[0044] Table 5 summarizes the ion concentrations in the extracts for Experimental Examples 2-4. The separation ratios calculated from the solution composition after 24 hours in Experimental Example 4 were Li / Co = 22.9, Li / Ni = 22.9, and Li / Mn = 82.6, respectively, indicating that lithium was preferentially extracted compared to other divalent ions. The monovalent selective cation membrane repels divalent ions and allows monovalent ions to permeate more easily due to the strong charge repulsion between the cation coating layer modified on the cation exchange membrane and the permeated ions. Therefore, in principle, leakage of divalent ions is unavoidable. To increase the Li purity in the recovered solution, it was hypothesized that adjusting the pH by adding lithium hydroxide to the recovered solution, or adding oxalic acid to crystallize and filter out Co, Ni, and Mn, would be effective in removing divalent ions. Furthermore, it was hypothesized that the filtered Co, Ni, and Mn precipitates could be recovered and dissolved again in the leaching solution to prevent loss.

[0045] [Table 3]

[0046] [Table 4]

[0047] [Table 5] [Industrial applicability]

[0048] This disclosure is applicable to the technology field of lithium recycling and manufacturing. [Explanation of symbols]

[0049] 10 Lithium recovery unit, 20 Cell, 21 Anode, 22 Cathode, 23 Bipolar membrane, 24 Cation permeable membrane, 25 Bipolar membrane, 30 Anode chamber, 31 Tank, 32 Anodelithe supply channel, 33 Anodelithe recovery channel, 35 Pump, 40 Raw material chamber, 41 Tank, 42 ​​Raw material liquid supply channel, 43 Raw material liquid recovery channel, 44 Branch channel, 45 Pump, 50 Extraction chamber, 51 Tank, 52 Extraction liquid supply channel, 53 Extraction liquid recovery channel, 54 Branch channel, 55 Pump, 60 Cathode chamber, 61 Tank, 62 Cathodelithe supply channel, 63 Cathodelithe recovery channel, 65 Pump, 70 Waste from energy storage devices, 71 Leaching liquid, 72 Raw material liquid, 73 Li extract, 74 Raw material liquid after extraction, 75 Li2SO4 aqueous solution, 76 MSO4 crystallized, 77 LiOH.

Claims

1. A lithium recovery method for recovering lithium from waste of energy storage devices containing lithium and polyvalent metals, A lithium recovery apparatus is used, which includes a cell having a raw material chamber, an extraction chamber, and a monovalent selective cation permeable membrane separating the raw material chamber and the extraction chamber, and includes an extraction step in which lithium is extracted from an acidic raw material solution contained in the raw material chamber, which contains a leaching solution in which lithium and polyvalent metals contained in the waste are dissolved and leached with mineral acid, into an acidic extract solution contained in the extraction chamber, by passing an electric current between the anode and the cathode. Lithium recovery methods.

2. The lithium recovery method according to claim 1, wherein in the extraction step, the raw material liquid is circulated in the raw material chamber, and while the extract is circulated in the extraction chamber, an electric current is passed between the anode and the cathode.

3. The lithium recovery method according to claim 1 or 2, wherein a sulfuric acid solution is used as the extractant in the extraction step.

4. The lithium recovery method according to claim 1 or 2, wherein the extraction step is performed under conditions in which crystallization does not occur in the extraction chamber.

5. The lithium recovery method according to claim 1 or 2, wherein in the extraction step, a solution with a pH of 2 or higher and a pH of 5 or lower is used as the raw material solution.

6. The lithium recovery method according to claim 1 or 2, wherein in the extraction step, a solution containing a hydroxide which is one or more of the hydroxides of lithium and polyvalent metals as a pH adjusting agent is used as the raw material solution.

7. A lithium recovery device for recovering lithium from waste of energy storage devices containing lithium and polyvalent metals, A cell having a raw material chamber, an extraction chamber, and a monovalent selective cation permeable membrane separating the raw material chamber and the extraction chamber between the anode and the cathode, A raw material supply unit supplies an acidic raw material solution containing a leaching solution obtained by dissolving and leaching lithium and polyvalent metals contained in the waste with mineral acid to the raw material chamber. An extract supply unit that supplies an acidic extract containing mineral acid to the extraction chamber, A control unit that passes an electric current between the anode and the cathode so as to extract lithium from the raw material liquid contained in the raw material chamber into the extract contained in the extraction chamber, A lithium recovery device equipped with the following features.

Images