Method for removing metal and method for recovering metal

Abstract

Provided are a method for removing at least one metal and a method for recovering a metal, which can effectively remove the metal from lithium-ion battery waste. A method for removing at least one metal from lithium-ion battery waste, wherein the lithium-ion battery waste has a positive electrode material in which a positive electrode-derived metal is adhered onto a positive electrode current collector containing aluminum as a metal to be removed, the method comprising, in any order, a crushing step of crushing the lithium-ion battery waste to separate at least a part of the positive electrode-derived metal from the positive electrode current collector, and an alkali separation step of bringing the lithium-ion battery waste into contact with an alkaline solution to dissolve the aluminum, thereby separating at least a part of the positive electrode-derived metal from the positive electrode current collector, further comprising a screening step of, after the crushing step, screening the lithium-ion battery waste into an oversize product and an undersize product containing the positive electrode-derived metal separated from the positive electrode current collector in the crushing step, and when the screening step is performed before the alkali separation step, at least a part of the oversize product obtained in the screening step is subjected to the alkali separation step.

Description

Technical Field

[0001] This specification relates to a method for removing metals from lithium-ion battery waste and a method for recovering metals.

Background Art

[0002] In vehicles such as hybrid vehicles, fuel cell vehicles, and electric vehicles, an in-vehicle battery pack that supplies power to an electric motor as a drive source is mounted (see, for example, Patent Documents 1 to 6). In the in-vehicle battery pack, battery cells may be housed inside a frame that forms an outer skeleton. Note that many in-vehicle battery packs are configured by bundling a plurality of battery cells into a battery module and further connecting a plurality of battery modules to each other. In addition, the in-vehicle battery pack may further include a BMS (Battery Management System) that monitors each battery cell, a cooling device that cools the battery, wires that connect them, and the like.

[0003] As the battery cells of the above in-vehicle battery pack, a secondary battery that can store electricity by charging and be repeatedly used, particularly a nickel-metal hydride battery, is generally used. In recent years, however, a lithium-ion battery using a lithium transition metal composite oxide for the positive electrode has been increasingly used. In the lithium-ion battery, a positive electrode material in which a positive electrode active material containing a valuable metal such as cobalt is adhered to a positive electrode current collector such as an aluminum foil may be provided. Therefore, when the in-vehicle battery pack is discarded after use or the like, from the viewpoint of effective utilization of resources, it is desirable to easily recover the valuable metal that may be contained in the lithium-ion battery waste at a relatively low cost for reuse.

[0004] The process for recovering valuable metals from lithium-ion battery waste is not limited to in-vehicle use and may include, for example, pretreatment such as heat treatment, crushing, and sieving of lithium-ion battery waste, and wet treatment of the battery powder obtained after the pretreatment.

[0005] In the wet treatment, specifically, metals such as cobalt, nickel, manganese, lithium, aluminum, and iron in the battery powder are leached with an acid to obtain a metal-containing solution in which the metal is dissolved. Next, for example, as described in Patent Document 7, aluminum ions, iron ions, manganese ions, etc. are sequentially or simultaneously removed from the metal-containing solution by neutralization or solvent extraction. Thereafter, cobalt ions and nickel ions in the metal-containing solution are separated by solvent extraction. After separating nickel ions by extraction, a metal-containing solution in which lithium ions remain is obtained.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Patent Document 6

Patent Document 7

Summary of the Invention

Problems to be Solved by the Invention

[0007] By the way, among the above-described lithium-ion battery wastes, there are those having a positive electrode material in which a positive electrode active material is firmly attached or fixed on a positive electrode current collector, and it is difficult to separate the positive electrode active material from the positive electrode current collector. In such lithium-ion battery wastes, even if crushing or sieving is performed, the positive electrode current collector is not sufficiently removed, and a certain amount of aluminum contained in the positive electrode current collector can be mixed into the battery powder.

[0008] When aluminum mixed in battery powder is leached with an acid, it dissolves together with other metals such as cobalt and becomes aluminum ions, which are contained in the metal-containing solution. When the metal-containing solution contains a relatively large amount of aluminum ions, it becomes difficult to remove them sufficiently. Therefore, it is desirable to remove metals such as aluminum before leaching the metals in the battery powder with an acid.

[0009] This specification provides at least one metal removal method and a metal recovery method capable of effectively removing metals from lithium-ion battery waste.

Means for Solving the Problems

[0010] The metal removal method disclosed in this specification is a method for removing at least one metal from lithium-ion battery waste, wherein the lithium-ion battery waste has a positive electrode material in which a positive electrode-derived metal is adhered onto a positive electrode current collector containing aluminum as the metal to be removed. The method includes, in any order, a crushing step of crushing the lithium-ion battery waste and separating at least a part of the positive electrode-derived metal from the positive electrode current collector, and an alkali separation step of bringing the lithium-ion battery waste into contact with an alkaline solution to dissolve the aluminum, thereby separating at least a part of the positive electrode-derived metal from the positive electrode current collector. After the crushing step, the method further includes a screening step of screening the lithium-ion battery waste into an oversize product and an undersize product containing the positive electrode-derived metal separated from the positive electrode current collector in the crushing step. When the screening step is performed before the alkali separation step, at least a part of the oversize product obtained in the screening step is subjected to the alkali separation step.

[0011] The metal recovery method disclosed in this specification is to recover metals from battery powder obtained by removing the metal to be removed from lithium-ion battery waste by the above-described at least one metal removal method.

Advantages of the Invention

[0012] According to the above metal removal method, at least one kind of metal can be effectively removed from lithium-ion battery waste.

Brief Description of Drawings

[0013]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0014] Hereinafter, embodiments of the above-described metal removal method and metal recovery method will be described in detail. The metal removal method of one embodiment is a method for removing a predetermined metal from lithium-ion battery waste. This lithium-ion battery waste includes a positive electrode material formed by attaching a positive electrode-derived metal to a positive electrode current collector, and the positive electrode current collector contains aluminum such as aluminum foil. The metal to be removed in this embodiment is at least aluminum. In addition, the lithium-ion battery waste may include a negative electrode material provided with a negative electrode current collector containing copper such as copper foil. In this case, the metal to be removed in this embodiment may further include copper.

[0015] The method for removing at least one of the above metals includes a crushing step and an alkali separation step in any order, and a screening step is included after the crushing step. Either the crushing step or the alkali separation step may be performed first, and other steps may be included between the crushing step and the alkali separation step. In the crushing step, the lithium-ion battery waste is crushed to separate at least a part of the metal derived from the positive electrode from the positive electrode current collector. The metal derived from the positive electrode separated from the positive electrode current collector in the crushing step is sorted into the undersize in the subsequent screening step. In the alkali separation step, the lithium-ion battery waste is brought into contact with an alkaline solution to dissolve the aluminum of the positive electrode current collector. Here, the aluminum on the surface of the positive electrode current collector to which the metal derived from the positive electrode adheres is dissolved, so that the metal derived from the positive electrode is peeled off from the positive electrode current collector, or almost all of the aluminum constituting the positive electrode current collector is dissolved, etc., so that at least a part of the metal derived from the positive electrode is separated from the positive electrode current collector. After the alkali separation step, a solid-liquid separation step for removing the aluminum-containing solution obtained in the alkali separation step may be performed.

[0016] If only either the crushing step or the alkali separation step is performed, the separation of the metal derived from the positive electrode from the positive electrode current collector may be insufficient. In contrast, in this embodiment, since both the crushing step and the alkali separation step are performed, most of the metal derived from the positive electrode is separated from the positive electrode current collector. As a result, the aluminum of the positive electrode current collector, which is the metal to be removed, can be effectively removed from the lithium-ion battery waste.

[0017] The present invention includes embodiments of the flow shown in FIGS. 1 to 3 in which the order of the crushing step and the alkali separation step and the timing of performing the screening step are different. In both FIGS. 1 and 2, the alkali separation step is performed after the crushing step, but the screening step is performed between the crushing step and the alkali separation step in FIG. 1, and after the alkali separation step in FIG. 2. In FIG. 3, the crushing step is performed after the alkali separation step, and these steps are performed in the order of the alkali separation step, the crushing step, and the screening step. Performing the alkali separation step after the crushing step as in FIGS. 1 and 2 is preferable because it may enable the smooth implementation of a series of steps, for example, because drying after the alkali separation step in the case of FIG. 3 with the reverse order becomes unnecessary. Further, when the alkali separation step is performed after the crushing step, the surface area of the lithium-ion battery waste that comes into contact with the alkaline solution in the alkali separation step increases, so it is preferable to perform the crushing step first also from the viewpoint of effectively performing the alkali separation step. Here, although detailed description is omitted, a heat treatment step of heating the lithium-ion battery waste, for example, at a temperature of 350°C to 650°C for 1 hour to 8 hours may be performed at any time before obtaining the battery powder from the lithium-ion battery waste.

[0018] Hereinafter, first, the details of each step will be described along the flow shown in FIG. 1, and then, as other embodiments, FIGS. 2 and 3 will be supplemented and explained centering on the points different from FIG. 1.

[0019] (Lithium-ion battery waste) The lithium-ion battery waste is various in-vehicle lithium-ion batteries that can be mounted on vehicles such as hybrid vehicles, fuel cell vehicles, and electric vehicles, and can be waste discarded due to vehicle scrapping, battery replacement, manufacturing defects, or other reasons. The lithium-ion battery waste refers to lithium-ion batteries targeted for recycling, regardless of whether the lithium-ion batteries are traded at a valuable price or are traded free of charge or as industrial waste.

[0020] The lithium-ion batteries contained in such lithium-ion battery waste include a positive electrode material, a negative electrode material, an electrolyte, and an aluminum casing or the like around them. Here, the positive electrode material and the negative electrode material can be configured by fixing a positive electrode active material or a negative electrode active material onto a positive electrode current collector such as an aluminum foil or a negative electrode current collector such as a copper foil with, for example, polyvinylidene fluoride (PVDF) or other organic binders.

[0021] Among these, as the positive electrode active material, for example, a single metal oxide of one of lithium, nickel, cobalt, and manganese, or a composite metal oxide of two or more of them is used. As such a positive electrode active material, for example, LiCoO 2 、LiNiO 2 、Li-Co-Ni-O 2 、Li-Co-Ni-Mn-O and the like can be mentioned. The metals contained in the positive electrode active material are desirably recovered as valuable metals from the viewpoint of effective utilization of resources. The metals contained in the positive electrode active material can change in form from the above oxides by treatments described later, but regardless of their form, metals such as cobalt, nickel, and lithium derived from the positive electrode active material (hereinafter also referred to as "positive electrode-derived metals") are targeted for recovery here.

[0022] In addition, carbon-based materials are often used for the negative electrode active material, and electrolytic solutions such as ethylene carbonate or diethyl carbonate are often used for the electrolyte. In addition, on-vehicle lithium-ion battery waste may contain terminals containing copper and / or iron, an iron casing, a stainless steel casing, or the like.

[0023] On-vehicle lithium-ion battery waste has a metal frame such as iron as an outer skeleton, and battery cells, which are lithium-ion batteries, are housed inside the frame. This type of lithium-ion battery waste often contains a plurality of battery cells, and a plurality of battery cells are bundled together to form a battery module, and further, a plurality of battery modules are connected to each other.

[0024] In addition, lithium-ion battery waste may include a BMS (Battery Management System) for monitoring each battery cell, a cooling device for cooling the battery, wires for connecting them, and the like. The wires are made of a metal containing copper, such as copper (Cu wire), etc., which are connected to each battery cell and the BMS to transmit information (such as temperature and voltage) regarding the temperature, voltage, etc. of each battery cell to the BMS. Also, a resin member may be provided between or around the battery cells.

[0025] Furthermore, the housing of the lithium-ion battery waste usually contains an electrolytic solution in which an electrolyte such as lithium hexafluorophosphate is dissolved in an organic solvent. As the organic solvent, for example, ethylene carbonate, diethyl carbonate, etc. may be used.

[0026] Some of such lithium-ion battery waste is such that the positive electrode active material is difficult to separate from the positive electrode current collector such as an aluminum foil. In contrast, in this embodiment, as will be described later, by performing pretreatment including a crushing step and an alkali separation step, battery powder with the aluminum of the positive electrode current collector effectively removed can be obtained.

[0027] In this embodiment, it may be directed to lithium-ion battery waste that maintains the form of a product as a lithium-ion battery, but it can also be directed to process scraps. Process scraps are discarded from the manufacturing process of lithium-ion batteries before injecting the electrolyte to form a lithium-ion battery, and contain at least no electrolyte. Typically, process scraps do not contain only the electrolyte, but also an aluminum casing and terminals containing copper. Specifically, examples of process scraps include a positive electrode material in which a positive electrode active material is adhered to a positive electrode current collector such as an aluminum foil with an organic binder or the like, a laminate in which a positive electrode material, a negative electrode material, and a separator are laminated, a wound body in which a positive electrode material, a negative electrode material, and a separator are wound up, and the like. In the manufacture of lithium-ion batteries, after attaching terminals to the laminate or wound body and enclosing it in an exterior package, the electrolyte is injected. Those discarded from the process before injecting the electrolyte and not containing the electrolyte are defined as process scraps. Such process scraps are also referred to herein as lithium-ion battery waste.

[0028] Lithium-ion battery waste containing an aluminum housing and terminals containing copper often requires magnetic separation to separate the aluminum from the housing, the terminals containing copper, etc., and the aluminum foil with cobalt, etc. attached. Also, in such lithium-ion battery waste, since cobalt, etc. do not have magnetism in the form of composite oxides in the positive electrode active material, it may be necessary to perform a heat treatment process before magnetic separation to convert the cobalt, etc. into a magnetic form. On the other hand, among the above process scraps, those that do not contain an aluminum housing and terminals containing copper may not require a heat treatment process for magnetizing cobalt, etc. Among the process scraps containing the housing and terminals containing copper, if the thickness of those housings and terminals is thin and crushable, the heat treatment process can be omitted, but when it is difficult to crush due to having a certain thickness, it is desirable to perform the heat treatment process. When the heat treatment process is performed, due to the change in the form of lithium, lithium may dissolve in the alkaline solution during the alkali separation process, resulting in a loss of lithium. If the heat treatment process is not performed, lithium remains in a form that is difficult to dissolve in the alkaline solution during the alkali separation process, and this loss of lithium is less likely to occur.

[0029] (Crushing process) In the crushing process, the lithium-ion battery waste is crushed to separate at least a part of the positive electrode-derived metal from the positive electrode current collector.

[0030] Preferably, at least a part of the positive electrode material is sheared by crushing. When the positive electrode material is sheared, the positive electrode-derived metal attached to the positive electrode current collector at that time is likely to be scraped off, etc., and thus the positive electrode-derived metal is likely to be separated from the positive electrode current collector. Note that if the positive electrode current collector is pulverized, the amount of aluminum mixed in the positive electrode current collector may increase. When the lithium-ion battery waste is a laminated body or wound body process scrap, the negative electrode material and separator are often sheared together with the positive electrode material by crushing.

[0031] Particularly in the case of lithium-ion battery waste from process scrap, when the crushing process and the alkali separation process are carried out in this order, by shearing the positive electrode material in the crushing process, in the subsequent alkali separation process, the positive electrode current collector that has been made somewhat finer effectively dissolves, and the metal derived from the positive electrode is more easily separated therefrom. Further, in process scrap that does not include a housing and terminals, the shearing of the positive electrode material as described above in the crushing process can be effectively carried out without being hindered by the housing and terminals.

[0032] As the crusher for performing such crushing, various types can be used, but among them, it is preferable to use a shearing type crusher. This is for shearing the positive electrode material as described above. In crushers aimed only at fine pulverization such as hammer mills and pin mills, there is a concern that the positive electrode current collector may be pulverized.

[0033] The lithium-ion battery waste, positive electrode current collector, and positive electrode material referred to in this specification and claims include those that have become somewhat minute, such as in flake form, for example, due to being crushed in the crushing process.

[0034] (Screening process) The screening process is carried out after the crushing process, and the lithium-ion battery waste is sorted into oversize and undersize containing the metal derived from the positive electrode separated from the positive electrode current collector in the crushing process. If the screening process is after the crushing process, other processes may be carried out between those processes.

[0035] In the screening process, a screen with a predetermined mesh size is used. As the mesh size of the screen, for example, it can be 0.15 mm to 1 mm, preferably 0.25 mm to 0.425 mm.

[0036] Among the lithium-ion battery waste selected as the oversize product in the screening process, for example, there are positive electrode materials and the like in which the positive electrode-derived metal remains attached to the positive electrode current collector without being separated from the positive electrode current collector in the crushing process, and valuable metals such as nickel and cobalt are also included together with aluminum. For such lithium-ion battery waste (oversize product), in order to further separate the positive electrode-derived metal from the positive electrode current collector, remove aluminum, and recover the valuable metal, the following alkali separation process is performed.

[0037] On the other hand, the oversize product mainly contains the positive electrode-derived metal separated from the positive electrode current collector in the crushing process. The aluminum content of the oversize product may be sufficiently reduced. Therefore, the oversize product can be used as battery powder A and subjected to an acid leaching process and a metal separation process as described below to recover cobalt, nickel, etc.

[0038] (Alkali Separation Process) In the alkali separation process, the lithium-ion battery waste (at least a part of the oversize product obtained in the screening process in the case of FIG. 1) is brought into contact with an alkaline solution. By contacting with the alkaline solution, aluminum such as the positive electrode current collector in the lithium-ion battery waste dissolves. At this time, for example, at least a part of the positive electrode-derived metal is peeled off from the positive electrode current collector due to dissolution of the surface of the positive electrode current collector to which the positive electrode-derived metal is attached. Alternatively, almost all of the positive electrode current collector may be dissolved in the alkaline solution. As a result, at least a part of the positive electrode-derived metal can be separated from the positive electrode current collector.

[0039] By changing the contact time between the lithium-ion battery waste and the alkaline solution and the alkali concentration of the alkaline solution, it is possible to adjust whether only the surface of the positive electrode current collector is dissolved or almost all of the positive electrode current collector is dissolved. Depending on the positive electrode current collector of the lithium-ion battery waste, the resistance to alkali may vary. For those in which the separation of the positive electrode current collector and the positive electrode material is easily expected with an alkali, the positive electrode-derived metal can be peeled off from the positive electrode current collector by shortening the contact time or reducing the alkali concentration. Alternatively, for those that are not easily peeled off, the positive electrode current collector may be dissolved by increasing the contact time or increasing the alkali concentration.

[0040] As shown in FIG. 1, when the alkali separation step is performed after the crushing step, the positive electrode current collector in the positive electrode material becomes finer to some extent due to the shearing of the positive electrode material in the crushing step. When the alkali separation step is performed on the lithium-ion battery waste containing such a positive electrode current collector, the alkaline solution easily contacts many parts of the positive electrode current collector. Thereby, the separation of the positive electrode-derived metal from the positive electrode current collector is promoted. The same can be said for FIG. 2.

[0041] In addition, when the crushing step, the screening step, and the alkali separation step are performed in this order, only the oversize obtained in the screening step becomes the object of the alkali separation step, so the amount of chemicals and the chemical cost of the alkali separation step can be reduced.

[0042] The mode of contact between the lithium-ion battery waste and the alkaline solution is not particularly limited as long as at least a part of aluminum is dissolved by the contact and at least a part of the positive electrode-derived metal can be separated from the positive electrode current collector. For example, immersing the lithium-ion battery waste in the alkaline solution, or pouring the alkaline solution onto the surface of the positive electrode current collector to which the positive electrode-derived metal of the lithium-ion battery waste adheres, etc. can be mentioned.

[0043] As the alkaline solution to be brought into contact with lithium-ion battery waste, it is preferable to use one with a pH of 13.0 or higher before the contact. Also, the OH - concentration of the alkaline solution before contact with the lithium-ion battery waste is preferably 5 mol / L or less. After contact with the lithium-ion battery waste, the alkaline solution may have a pH of 13.0 or higher and an OH - concentration maintained at 5 mol / L or less. If an alkaline solution with too high a pH is used, even in the case of lithium-ion battery waste where the positive electrode-derived metal can be peeled off by partial dissolution of the positive electrode current collector, the alkaline solution will dissolve most of the positive electrode current collector, resulting in a high final wastewater treatment cost. On the other hand, if the pH of the alkaline solution is too low, there is concern that aluminum may not dissolve sufficiently. As the alkaline solution, for example, a sodium hydroxide solution, a potassium hydroxide solution, etc. can be used.

[0044] Also, in the alkali separation step, it is preferable to maintain the liquid temperature of the alkaline solution brought into contact with the lithium-ion battery waste within the range of 10°C to 80°C, and more preferably within the range of 10°C to 50°C. If the liquid temperature is too high, the reactivity will increase, and there is a risk of rapid generation of hydrogen and a rapid rise in the liquid temperature. If the liquid temperature is too low, the reactivity will decrease, and the alkali separation step may take a long time. The pulp concentration can be, for example, 20 g / L to 500 g / L. This pulp concentration means the ratio of the dry weight (g) of the lithium-ion battery waste to the amount (L) of the alkaline solution brought into contact with the lithium-ion battery waste. The time for dissolving aluminum may be, for example, 0.5 hour to 3.0 hours.

[0045] When the heat treatment step is not performed before the alkali separation step, lithium in the lithium-ion battery waste may not change into forms such as lithium carbonate that dissolve in the alkaline solution, and may remain in the form of the aforementioned single or composite metal oxides. In this case, in the alkali separation step, lithium in the lithium-ion battery waste hardly dissolves in the alkaline solution. Therefore, from the viewpoint of suppressing the loss of lithium in the alkali separation step, it is preferable that the metal removal method does not include the heat treatment step.

[0046] After the alkali separation step, an aluminum-containing solution in which aluminum in the lithium-ion battery waste is dissolved, and residues such as flakes and powders that remain undissolved upon contact with the alkaline solution are obtained. The aluminum-containing solution can be separated and removed in the solid-liquid separation step described later. The aluminum ion concentration of the aluminum-containing solution may be, for example, 0.7 g / L to 6 g / L.

[0047] When the surface of the positive electrode current collector is dissolved in the alkali separation step, the above-mentioned residue may contain, in addition to the positive electrode-derived metal in the form of powder, etc., the positive electrode current collector such as flakes and other shapes of aluminum foil from which the positive electrode-derived metal has been separated. For the purpose of separating and removing such a positive electrode current collector from the positive electrode-derived metal, it is preferable to perform the re-screening step described below. Alternatively, when almost all of the positive electrode current collector is dissolved in the alkali separation step, the above-mentioned residue may not contain the positive electrode current collector. In this case, the re-screening step can be omitted.

[0048] (Re-screening step) In the re-screening step, the residue after the alkali separation step is screened, and the residue is separated into an oversize product containing the positive electrode current collector from which the positive electrode-derived metal has been separated in the alkali separation step, and an undersize product containing the positive electrode-derived metal separated from the positive electrode current collector in the alkali separation step. The undersize product mainly contains valuable metals such as cobalt and nickel, and can be used as battery powder B to be subjected to the acid leaching step.

[0049] By the above-described alkali separation step, the metal derived from the positive electrode is effectively peeled off from the positive electrode current collector. The positive electrode current collector may have a shape such as a flake shape and may be larger in size than the metal derived from the positive electrode. Therefore, if a sieve with an appropriate mesh size is selected and used in the re-screening step, the positive electrode current collector containing aluminum can be favorably removed as an oversize product. At this time, not only the positive electrode current collector but also a negative electrode current collector made of copper or the like and a separator having a size as large as that of the positive electrode current collector may be included in the oversize product and removed.

[0050] The mesh size of the sieve used in the re-screening step is, for example, 0.15 mm to 1 mm, preferably 0.25 mm to 0.425 mm.

[0051] When a solid-liquid separation step is performed after the re-screening step, in the re-screening step, wet screening can be performed on the residue after the alkali separation step while the residue is contained in the aluminum-containing solution. When a solid-liquid separation step is performed before the re-screening step, in the re-screening step, dry screening can be performed on the residue after the aluminum-containing solution is separated in the solid-liquid separation step.

[0052] (Solid-Liquid Separation Step) After the alkali separation step, in some cases, after performing a re-screening step, a solid-liquid separation step may be performed to separate and remove the aluminum-containing solution from the residue obtained in the alkali separation step (the undersize product in the case after the re-screening step).

[0053] Solid-liquid separation can be performed by filtration or the like using a known device such as a filter press or a thickener.

[0054] The battery powder obtained as described above may have a lithium content of 5% by mass to 6% by mass, a cobalt content of 2% by mass to 20% by mass, a nickel content of 18% by mass to 46% by mass, a manganese content of 0.1% by mass to 15% by mass, an aluminum content of 0.1% by mass to 3.0% by mass, and an iron content of 0% by mass.

[0055] (Other Embodiments) In the embodiment shown in FIG. 2, these processes are carried out in the order of the crushing process, the alkali separation process, and the screening process. In the alkali separation process, when the surface of the positive electrode current collector is dissolved to peel off the positive electrode-derived metal from the positive electrode current collector, in the subsequent screening process, the residue after the alkali separation process is separated into an oversize product containing the positive electrode current collector from which the positive electrode-derived metal has been separated in each of the crushing process and the alkali separation process, and an undersize product containing the positive electrode-derived metal separated from the positive electrode current collector in each of the crushing process and the alkali separation process.

[0056] Alternatively, in FIG. 2, when the alkali separation process is carried out under conditions where almost all of the positive electrode current collector is dissolved, the residue after the alkali separation process may substantially not contain the positive electrode current collector and may contain a negative electrode current collector containing copper. The negative electrode current collector contains copper, which is a metal to be removed, is crushed in the crushing process before the alkali separation process, and is contained in the residue without being dissolved in the alkaline solution in the alkali separation process. In this case, the subsequent screening process can be carried out to separate the residue after the alkali separation process into an oversize product containing the negative electrode current collector crushed in the crushing process and an undersize product containing the positive electrode-derived metal separated from the positive electrode current collector in the crushing process.

[0057] Although not shown in FIG. 2, the solid-liquid separation process can be carried out before or after the screening process after the alkali separation process. When the solid-liquid separation process is carried out before the screening process, the screening process can be a dry screening, and when the solid-liquid separation process is carried out after the screening process, the screening process can be a wet screening.

[0058] In the embodiment shown in FIG. 3, these processes are carried out in the order of the alkali separation process, the crushing process, and the screening process. Here, a preliminary screening process may be carried out between the alkali separation process and the crushing process. In the preliminary screening process, the material is separated into an oversize product containing the positive electrode current collector from which the positive electrode-derived metal has been separated in the alkali separation process and an undersize product containing the positive electrode-derived metal separated from the positive electrode current collector in the alkali separation process.

[0059] In order to separate the above-mentioned oversize material and undersize material, the mesh size of the sieve used in the preliminary screening step is, for example, 0.15 mm to 1 mm, preferably 0.25 mm to 0.425 mm. The oversize material obtained in the preliminary screening step contains the positive electrode current collector with the positive electrode-derived metal remaining thereon. In order to recover the positive electrode-derived metal therefrom, at least a part of it is subjected to a crushing step. On the other hand, the undersize material can be used as battery powder A.

[0060] When the preliminary screening step is performed, in the screening step after the crushing step, it is sorted into an oversize material containing the positive electrode current collector from which the positive electrode-derived metal has been separated in the crushing step and an undersize material containing the positive electrode-derived metal separated from the positive electrode current collector in the crushing step.

[0061] However, for example, when almost all of the positive electrode current collectors are dissolved in the alkali separation step, etc., it is possible to omit the preliminary screening step. When the preliminary screening step is not performed, the residue after the alkali separation step is subjected to the crushing step. In this case, in the screening step after the crushing step, the crushed negative electrode current collector, etc. can be sorted into the oversize material. The undersize material contains the positive electrode-derived metal separated from the positive electrode current collector in the crushing step, and this can be used as battery powder B.

[0062] (Acid leaching step) In the acid leaching step, the above-mentioned battery powder is added to an acidic leaching solution of sulfuric acid, nitric acid, hydrochloric acid or other inorganic acids, etc., to leach the metals in the battery powder with an acid. Thereby, a metal-containing solution in which various metals are dissolved is obtained.

[0063] The acid leaching step can be carried out by known methods or conditions, but the pH is preferably 0.0 to 2.0, and the oxidation-reduction potential (ORP, silver / silver chloride electrode reference) may be 0 mV or less.

[0064] When the heat treatment step is not performed when obtaining battery powder from lithium-ion battery waste, lithium in the battery powder may be contained in the form of a composite metal oxide as described above. In this case, in order to dissolve such a composite metal oxide, it is desirable to add a reducing agent such as hydrogen peroxide to the acidic leaching solution.

[0065] The residue remaining undissolved by acid leaching can be separated from the metal-containing solution by solid-liquid separation such as filtration using known apparatuses and methods such as a filter press and a thickener. Much of the copper in the battery powder may be included in the leaching residue. This solid-liquid separation can be omitted, and neutralization or the like in the metal separation step may be carried out without solid-liquid separation after acid leaching.

[0066] The metal-containing solution obtained in the acid leaching step may contain at least one selected from the group consisting of lithium ions, cobalt ions, nickel ions, manganese ions, aluminum ions, iron ions, and copper ions. Typically, cobalt ions and / or nickel ions are included.

[0067] The metal-containing solution obtained in the acid leaching step may have 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, a copper ion concentration of 0.005 g / L to 0.2 g / L, and a fluoride ion concentration of 0.01 g / L to 20 g / L.

[0068] (Metal separation step) In the metal separation step, metals such as cobalt and nickel can be separated from the metal-containing solution by various known methods and the like, and the necessary metals among them can be recovered. Specifically, neutralization and / or solvent extraction or the like can be performed on the metal-containing solution to separate and recover each metal in the metal-containing solution.

[0069] (Test example) As tests related to the metal removal method described above, the following test examples were conducted. The description of this test example is merely illustrative and not limited thereto.

[0070] As lithium-ion battery waste, for process scraps A to C of the cathode material that do not contain electrolyte, an aluminum casing, and terminals containing copper, attempts were made to separate the cathode-derived metal from the cathode current collector of the cathode material by crushing, screening, or alkali separation. Here, process scraps A to C each have different components, structures, and manufacturing methods that make up the cathode material. In this test example, for each of process scraps A to C, a plurality of test pieces were taken out from the process scrap. Only crushing and screening were performed on one test piece, and only alkali separation was performed on the other test piece. Crushing and screening correspond to the crushing process and the screening process in FIGS. 1 to 3. That is, in crushing and screening, after the crushing process, the cathode-derived metal and the like separated from the cathode current collector by the crushing process were separated by the screening process with the cathode current collector and the like on the sieve and the material passing through the sieve below the sieve. Specifically, in crushing and screening, for one of the above test pieces, shear crushing was performed using an HM-20 manufactured by Orient Crusher Co., Ltd. as a crusher, and then sieving was performed using a sieve with an opening size of 0.25 mm to obtain the material passing through the sieve. In alkali separation, as an alkaline solution, a sodium hydroxide solution with a concentration of 50 g / L and a pH of 14 was used, and the other test piece was immersed in the alkaline solution for 10 to 30 minutes.

[0071] The recovery rate, grade, and loss of each metal in the material passing through the sieve obtained by crushing and screening and the residue obtained by alkali separation are shown in Table 1. In Table 1, “%” is based on mass, and the recovery rate and loss respectively mean the amount after treatment relative to the content in process scraps A to C before treatment. Also, “alkali stripping” in Table 1 means alkali separation that peels the cathode-derived metal from the cathode current collector by dissolving aluminum on the surface of the cathode current collector as described above.

[0072]

Table 1

[0073] As can be seen from Table 1, in both crushing / sieving and alkali separation, process scrap B was able to effectively separate nickel, cobalt, and lithium from aluminum, and the aluminum grade in the undersize and residue was low. Also, the loss of lithium could be suppressed to a small extent. However, in process scrap A, nickel, cobalt, and lithium could be effectively separated from aluminum in alkali separation, but in crushing / sieving, they could not be sufficiently separated, resulting in a low recovery rate of nickel and cobalt, and a high aluminum grade in the undersize. In addition, in process scrap C, cobalt, nickel, and lithium did not peel off from the aluminum foil in alkali separation, but in crushing / sieving, nickel, cobalt, and lithium could be separated from aluminum.

[0074] Thus, among the process scraps, there are those that cannot effectively separate nickel, cobalt, and lithium from aluminum with only one of crushing / sieving and alkali separation. Also, which of crushing / sieving and alkali separation can effectively separate depends on the process scrap. However, even for such process scraps, if the other of crushing / sieving and alkali separation is carried out, nickel, cobalt, and lithium can be effectively separated from aluminum. That is, if both crushing / sieving and alkali separation are carried out, regardless of the process scrap, nickel, cobalt, and lithium can be effectively separated from aluminum in either process.

[0075] This suggests that according to the metal removal method described above, there is a possibility of effectively removing aluminum from lithium-ion battery waste.

Claims

1. A method for removing at least one metal from lithium-ion battery waste, comprising: the lithium-ion battery waste having a positive electrode material in which a metal derived from the positive electrode is adhered onto a positive electrode current collector containing aluminum as the metal to be removed; a crushing step of crushing the lithium-ion battery waste to separate at least a part of the metal derived from the positive electrode from the positive electrode current collector; an alkali separation step of bringing the lithium-ion battery waste into contact with an alkaline solution to dissolve the aluminum, thereby separating at least a part of the metal derived from the positive electrode from the positive electrode current collector in any order, further comprising a screening step of, after the crushing step, screening the lithium-ion battery waste into an oversize product and an undersize product containing the metal derived from the positive electrode separated from the positive electrode current collector in the crushing step; When the screening step is performed before the alkali separation step, at least a part of the oversize product obtained in the screening step is subjected to the alkali separation step, the method for removing at least one metal.

2. The method for removing at least one metal according to Claim 1, wherein in the alkali separation step, the pH of the alkaline solution brought into contact with the lithium-ion battery waste is 13.0 or more.

3. In the alkali separation step, the OH of the alkaline solution that has come into contact with the lithium-ion battery waste - The method for removing at least one kind of metal according to claim 1 or 2, wherein the concentration is 5 mol / L or less.

4. The method for removing at least one metal according to Claim 1 or 2, wherein in the alkali separation step, the liquid temperature of the alkaline solution is 10°C to 80°C.

5. The method for removing at least one metal according to Claim 1 or 2, wherein the oversize product obtained in the screening step contains the positive electrode current collector from which the metal derived from the positive electrode was separated in the crushing step.

6. The method for removing at least one metal according to Claim 1 or 2, wherein the alkali separation step is performed after the crushing step.

7. The method for removing at least one metal according to Claim 6, wherein the crushing step, the screening step, and the alkali separation step are performed in that order.

8. The method for removing at least one metal according to Claim 7, further comprising a re-screening step of, after the alkali separation step, screening the residue after the alkali separation step into an oversize product containing the positive electrode current collector from which the metal derived from the positive electrode was separated in the alkali separation step and an undersize product containing the metal derived from the positive electrode separated from the positive electrode current collector in the alkali separation step.

9. The method for removing at least one metal according to Claim 8, wherein in the re-screening step, a screen having an aperture size of 0.15 mm to 1 mm is used.

10. The method for removing at least one metal according to claim 6, wherein the steps are performed in the order of the crushing step, the alkali separation step, and the sieving step.

11. The lithium-ion battery waste has a negative electrode current collector containing copper, which is the metal to be removed, In the sieving step, the lithium-ion battery waste is separated into an oversize product containing the negative electrode current collector crushed in the crushing step and an undersize product. The method for removing at least one metal according to claim 10.

12. The method for removing at least one metal according to claim 1 or 2, wherein the steps are performed in the order of the alkali separation step, the crushing step, and the sieving step.

13. After the alkali separation step and before the crushing step, a preliminary sieving step is further included, in which the residue after the alkali separation step is separated into an oversize product containing the positive electrode current collector from which the positive electrode-derived metal has been separated in the alkali separation step and an undersize product containing the positive electrode-derived metal separated from the positive electrode current collector in the alkali separation step, The method for removing at least one metal according to claim 12, wherein at least a part of the oversize product obtained in the preliminary sieving step is subjected to the crushing step.

14. The method for removing at least one metal according to claim 13, wherein a sieve with an aperture size of 0.15 mm to 1 mm is used in the preliminary sieving step.

15. The method for removing at least one metal according to claim 1 or 2, further including a solid-liquid separation step of removing the aluminum-containing solution obtained in the alkali separation step after the alkali separation step.

16. The method for removing at least one metal according to claim 1 or 2, wherein a sieve with an aperture size of 0.15 mm to 1 mm is used in the sieving step.

17. A metal recovery method for recovering a metal from battery powder obtained by removing a metal to be removed from lithium-ion battery waste by the method for removing at least one metal according to claim 1 or 2.

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