METHOD FOR REMOVING METALS AND METHOD FOR RECOVERING METALS

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 technology]

[0002] Vehicles such as hybrid vehicles, fuel cell vehicles, and electric vehicles are equipped with an in-vehicle battery pack that supplies power to an electric motor as a drive source (see, for example, Patent Documents 1 to 6). In an in-vehicle battery pack, battery cells may be housed inside a frame that forms the skeleton of the exterior. Many in-vehicle battery packs are configured by bundling multiple battery cells into a battery module, and then connecting multiple battery modules together. In-vehicle battery packs may also include a BMS (Battery Management System) that monitors each battery cell, a cooling device that cools the battery, wires that connect them, etc.

[0003] The battery cells of the above-mentioned automotive battery packs are generally secondary batteries, particularly nickel-metal hydride batteries, which can store electricity by charging and be used repeatedly. However, in recent years, lithium-ion batteries using lithium transition metal composite oxides for the positive electrode have been increasingly used. Lithium-ion batteries sometimes have a positive electrode material in which a positive electrode active material containing valuable metals such as cobalt is attached to a positive electrode current collector such as aluminum foil. Therefore, when automotive battery packs are discarded after use, it is desirable to easily recover the valuable metals that may be contained in the lithium-ion battery waste for reuse at a relatively low cost, from the perspective of effective resource utilization.

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

[0005] Specifically, in the wet treatment, metals such as cobalt, nickel, manganese, lithium, aluminum, and iron in the battery powder are leached with acid to obtain a metal-containing solution in which the metals are dissolved. Next, as described in Patent Document 7, for example, aluminum ions, iron ions, and manganese ions 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 nickel ions are separated by extraction, a metal-containing solution containing remaining lithium ions is obtained. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-179190 [Patent Document 2] Japanese Patent Application Laid-Open No. 2007-172938 [Patent Document 3] US Patent Application Publication No. 2007 / 0141454 [Patent Document 4] Japanese Patent Application Laid-Open No. 2007-172939 [Patent Document 5] US Patent Application Publication No. 2007 / 0141455 [Patent Document 6] Japanese Patent Application Laid-Open No. 2011-198713 [Patent Document 7] International Publication No. 2018 / 181816 Summary of the Invention [Problem to be solved by the invention]

[0007] However, some of the lithium-ion battery waste described above contains a cathode material in which the cathode active material is firmly attached or fixed to the cathode current collector, making it difficult to separate the cathode active material from the cathode current collector. In such lithium-ion battery waste, the cathode current collector cannot be sufficiently removed even by crushing or sieving, and a certain amount of aluminum contained in the cathode current collector may be mixed into the battery powder.

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

[0009] This specification provides at least one method for removing metals and a method for recovering metals that can effectively remove metals from lithium ion battery waste. [Means for solving the problem]

[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 cathode material in which a cathode-derived metal is attached to a cathode current collector containing aluminum, which is the metal to be removed, and the method includes, in any order: a crushing process for crushing the lithium-ion battery waste and separating at least a portion of the cathode-derived metal from the cathode current collector; and an alkaline separation process for contacting the lithium-ion battery waste with an alkaline solution to dissolve the aluminum and thereby separate at least a portion of the cathode-derived metal from the cathode current collector; and after the crushing process, further includes a sieving process for sorting the lithium-ion battery waste into an over-sieved material and an under-sieved material containing the cathode-derived metal separated from the cathode current collector in the crushing process; and if the sieving process is performed before the alkaline separation process, at least a portion of the over-sieved material obtained in the sieving process is subjected to the alkaline separation process.

[0011] The metal recovery method disclosed in this specification involves recovering metals from battery powder obtained by removing target metals from lithium ion battery waste using at least one of the above-mentioned metal removal methods. [Effects of the Invention]

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

[0013] [Figure 1] FIG. 1 is a flow diagram illustrating a metal removal method according to one embodiment. [Figure 2] FIG. 10 is a flow diagram illustrating a metal removal method according to another embodiment. [Figure 3] FIG. 10 is a flow chart showing a metal removal method according to yet another embodiment. [Figure 4] FIG. 1 is a flow chart showing an example of a method for recovering metals from battery powder obtained by a metal removal method. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, embodiments of the above-mentioned metal removal method and metal recovery method will be described in detail. One embodiment of the metal removal method is a method for removing a predetermined metal from lithium-ion battery waste. The lithium-ion battery waste includes a cathode material formed by depositing a cathode-derived metal onto a cathode current collector, and the cathode current collector contains aluminum, such as aluminum foil. In this embodiment, the metal to be removed is at least aluminum. Furthermore, the lithium-ion battery waste may include a negative electrode material having a copper-containing negative electrode current collector, 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 metal described above includes a crushing step and an alkali separation step, in any order, and includes a sieving step after the crushing step. Either the crushing step or the alkali separation step may be performed first, or 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 portion of the positive electrode-derived metal from the positive electrode current collector. The positive electrode-derived metal separated from the positive electrode current collector in the crushing step is then sorted into undersized material in the subsequent sieving step. In the alkali separation step, the lithium-ion battery waste is contacted with an alkaline solution to dissolve the aluminum from the positive electrode current collector. Here, the aluminum on the surface of the positive electrode current collector to which the positive electrode-derived metal was attached dissolves, causing the positive electrode-derived metal to peel off from the positive electrode current collector, or almost all of the aluminum constituting the positive electrode current collector dissolves, thereby separating at least a portion of the positive electrode-derived metal from the positive electrode current collector. The alkali separation step may be followed by a solid-liquid separation step for removing the aluminum-containing solution obtained in the alkali separation step.

[0016] In some cases, the separation of the positive electrode-derived metals from the positive electrode current collector is insufficient when only the crushing step or the alkaline separation step is performed. In contrast, in this embodiment, both the crushing step and the alkaline separation step are performed, so that most of the positive electrode-derived metals are separated from the positive electrode current collector. As a result, aluminum from the positive electrode current collector, which is the metal to be removed, can be effectively removed from lithium-ion battery waste.

[0017] This invention includes flow embodiments shown in Figures 1 to 3, in which the order of the crushing step and the alkaline separation step and the timing of the sieving step are different. Figures 1 and 2 both show the alkaline separation step after the crushing step, but differ in that the sieving step is performed between the crushing step and the alkaline separation step in Figure 1 and after the alkaline separation step in Figure 2. In Figure 3, the crushing step is performed after the alkaline separation step, and these steps are performed in the order of the alkaline separation step, crushing step, and sieving step. Performing the alkaline separation step after the crushing step, as in Figures 1 and 2, is preferable because it enables smooth implementation of the series of steps, for example, by eliminating the need for drying after the alkaline separation step, as in Figure 3, in which the order is reversed. Furthermore, performing the alkaline separation step after the crushing step increases the surface area of ​​the lithium-ion battery waste that comes into contact with the alkaline solution in the alkaline separation step. Therefore, it is preferable to perform the crushing step first in order to effectively perform the alkaline separation step. Although detailed explanation is omitted here, a heat treatment step may be performed at any time before obtaining battery powder from the lithium ion battery waste, in which the lithium ion battery waste is heated at a temperature of, for example, 350°C to 650°C for 1 hour to 8 hours.

[0018] In the following, first, the details of each step will be explained along the flow shown in FIG. 1, and then supplementary explanations will be given of other embodiments shown in FIGS. 2 and 3, focusing on the differences from FIG.

[0019] (Lithium-ion battery waste) Lithium-ion battery waste refers to various automotive lithium-ion batteries that can be installed in vehicles such as hybrid cars, fuel cell cars, and electric cars, which are discarded due to vehicle scrapping, battery replacement, manufacturing defects, or other reasons. Lithium-ion battery waste refers to lithium-ion batteries that are eligible for recycling, regardless of whether they are traded for a price, free of charge, or treated 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 the surrounding aluminum casing, etc. Here, the positive electrode material and the negative electrode material may be formed by fixing a positive electrode active material or a negative electrode active material onto a positive electrode current collector such as aluminum foil or a negative electrode current collector such as copper foil, respectively, with, for example, polyvinylidene fluoride (PVDF) or other organic binders.

[0021] Among these, the positive electrode active material may be, for example, a single metal oxide of lithium, nickel, cobalt, or manganese, or a composite metal oxide of two or more of these metals. Examples of such positive electrode active materials include LiCoO2, LiNiO2, Li-Co-Ni-O2, and Li-Co-Ni-Mn-O. It is desirable to recover the metals contained in the positive electrode active material as valuable metals in terms of effective resource utilization. The form of the metals contained in the positive electrode active material may change from the oxides described above through processing, etc., as described below. However, regardless of their form, the metals contained in the positive electrode active material, such as cobalt, nickel, and lithium (hereinafter also referred to as "positive electrode-derived metals"), derived from the positive electrode active material, are the targets of recovery here.

[0022] In addition, carbon-based materials are often used as the negative electrode active material, and electrolytic solutions such as ethylene carbonate or diethyl carbonate are often used as the electrolyte. In addition, waste automotive lithium-ion batteries may contain terminals containing copper and / or iron, iron cases, stainless steel cases, etc.

[0023] Waste automotive lithium-ion batteries have a metal frame such as iron as an exterior skeleton, and lithium-ion battery cells are housed inside the frame. This type of lithium-ion battery waste often contains multiple battery cells, which are bundled together to form a battery module, and then multiple battery modules are connected together.

[0024] Lithium-ion battery waste may also include a BMS (Battery Management System) that monitors each battery cell, a cooling device that cools the battery, and wires that connect them. The wires are made of a metal containing copper, such as copper (Cu wire), and are connected to each battery cell and the BMS to transmit information (such as temperature and voltage) about the temperature and voltage of each battery cell to the BMS. Resin materials may also be provided between or around the battery cells.

[0025] Furthermore, the casing of lithium-ion battery waste typically contains an electrolyte solution, which is made by dissolving an electrolyte such as lithium hexafluorophosphate in an organic solvent, such as ethylene carbonate or diethyl carbonate.

[0026] In some of such lithium-ion battery waste, the positive electrode active material is difficult to separate from the positive electrode current collector, such as aluminum foil, etc. In contrast, in this embodiment, as described below, a pretreatment including a crushing step and an alkali separation step is performed to obtain battery powder from which the aluminum of the positive electrode current collector has been effectively removed.

[0027] In this embodiment, the target may be lithium-ion battery waste that maintains the form of a lithium-ion battery product, but it can also be process scrap. Process scrap is discarded from the lithium-ion battery manufacturing process before the electrolyte is injected to form a lithium-ion battery, and does not contain at least the electrolyte. Typically, process scrap does not include not only the electrolyte but also the aluminum case and copper-containing terminals. Specific examples of process scrap include cathode materials in which a cathode active material is attached to a cathode current collector such as aluminum foil with an organic binder, a laminate in which a cathode material, an anode material, and a separator are stacked, and a wound body in which a cathode material, an anode material, and a separator are wound. In the manufacturing of lithium-ion batteries, terminals are attached to the laminate or wound body and sealed in a housing, and then the electrolyte is injected. Process scrap is discarded from the process before the electrolyte is injected and does not contain the electrolyte. Such process scrap is also referred to as lithium-ion battery waste here.

[0028] Lithium-ion battery waste containing aluminum casings and copper-containing terminals often requires magnetic separation to separate the aluminum and copper-containing terminals from the aluminum foil containing cobalt and other elements. Furthermore, in such lithium-ion battery waste, because cobalt and other elements in the composite oxide form in the positive electrode active material are not magnetic, a heat treatment process may be required before magnetic separation to convert the cobalt and other elements to a magnetic form. On the other hand, among the above-mentioned process scrap, those that do not contain aluminum casings or copper-containing terminals may not require a heat treatment process to magnetize the cobalt and other elements. For process scrap containing casings and copper-containing terminals, the heat treatment process can be omitted if the casings and terminals are thin and crushable. However, if the casings and terminals are thick enough to be crushed, a heat treatment process is desirable. The heat treatment process can change the morphology of lithium, causing it to dissolve in alkaline solution during the alkaline separation process, resulting in lithium loss. Without the heat treatment process, lithium remains in a form that is less soluble in alkaline solution during the alkaline separation process, reducing lithium loss.

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

[0030] It is preferable that at least a portion of the positive electrode material is sheared by shredding. When the positive electrode material is sheared, the positive electrode-derived metal attached to the positive electrode current collector is scraped off, and the positive electrode-derived metal tends to be easily separated from the positive electrode current collector. Note that crushing the positive electrode current collector may increase the amount of aluminum contained in the positive electrode current collector. When lithium-ion battery waste is process scrap of laminates or wound bodies, the negative electrode material and separator are often sheared along with the positive electrode material by shredding.

[0031] In particular, in the case of lithium-ion battery waste that is process scrap, when the crushing step and the alkaline separation step are performed in this order, by shearing the cathode material in the crushing step, the cathode current collector, which has been broken down to a certain degree, can be effectively dissolved in the alkaline separation step described below, making it easier to separate the cathode-derived metal from the cathode current collector. Furthermore, in process scrap that does not include casings or terminals, the above-mentioned shearing of the cathode material in the crushing step can be effectively performed without being hindered by the casings or terminals.

[0032] Various types of crushers can be used for crushing the cathode material, but it is preferable to use a shearing crusher, as described above. Crushers designed only for pulverization, such as hammer mills and pin mills, may crush the cathode current collector.

[0033] The lithium ion battery waste, positive electrode current collector, and positive electrode material referred to in this specification and claims also include those that have been broken into small pieces, such as fragments, due to being crushed in a crushing process, for example.

[0034] (sieving process) The sieving step is carried out after the crushing step, and the lithium-ion battery waste is separated into an over-sieved material and an under-sieved material containing metals derived from the positive electrode current collector separated in the crushing step. If the sieving step is carried out after the crushing step, other steps may be carried out between the two steps.

[0035] In the sieving step, a sieve with a predetermined mesh size is used, which may be, for example, 0.15 mm to 1 mm, preferably 0.25 mm to 0.425 mm.

[0036] The lithium-ion battery waste as the sieve residue separated in the sieving process includes, for example, cathode materials in which the cathode-derived metals were not separated from the cathode current collector in the crushing process and the cathode-derived metals are still attached to the cathode current collector, and also contains valuable metals such as nickel and cobalt in addition to aluminum. Such lithium-ion battery waste (sieve residue) is subjected to the alkaline separation process described below in order to further separate the cathode-derived metals from the cathode current collector, remove aluminum, and recover the valuable metals.

[0037] On the other hand, sieve under The material mainly contains metals derived from the positive electrode that were separated from the positive electrode current collector during the crushing process. under The aluminum content of the product can sometimes be reduced sufficiently. under The product can be used as battery powder A and subjected to the acid leaching process and metal separation process described below to recover cobalt, nickel, etc.

[0038] (Alkali separation process) In the alkaline separation step, the lithium-ion battery waste (in the case of Figure 1, at least a portion of the sieved material obtained in the sieving step) is brought into contact with an alkaline solution. The contact with the alkaline solution dissolves aluminum from the positive electrode current collector and other components in the lithium-ion battery waste. During this process, for example, the surface of the positive electrode current collector to which the positive electrode-derived metal is attached dissolves, causing at least a portion of the positive electrode-derived metal to peel off from the positive electrode current collector. Alternatively, almost the entire positive electrode current collector may be dissolved in the alkaline solution. As a result, at least a portion 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 alkaline concentration of the alkaline solution, it is possible to adjust whether only the surface of the positive electrode current collector is dissolved or whether almost the entire 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 materials where the positive electrode current collector and the positive electrode material are expected to be easily separated by alkali, the contact time can be shortened or the alkaline concentration can be reduced to peel the metal derived from the positive electrode from the positive electrode current collector. Alternatively, for materials where peeling is not easy, the positive electrode current collector can be dissolved by increasing the contact time or the alkaline concentration.

[0040] As shown in Figure 1, when an alkaline separation process is performed after the crushing process, the cathode current collectors in the cathode material are broken down to a certain size due to shearing of the cathode material during the crushing process. When the alkaline separation process is performed on lithium-ion battery waste containing such cathode current collectors, the alkaline solution is more likely to come into contact with many parts of the cathode current collectors. This promotes the separation of cathode-derived metals from the cathode current collectors. The same can be said for Figure 2.

[0041] Furthermore, when the crushing step, sieving step, and alkali separation step are performed in that order, only the sieved material obtained in the sieving step is subjected to the alkali separation step, thereby reducing the amount of chemicals and chemical costs used in the alkali separation step.

[0042] The manner of contacting the lithium-ion battery waste with the alkaline solution is not particularly limited as long as the contact dissolves at least a portion of the aluminum and separates at least a portion of the metal derived from the positive electrode from the positive electrode current collector. For example, the lithium-ion battery waste may be immersed in the alkaline solution, or the alkaline solution may be poured onto the surface of the positive electrode current collector to which the metal derived from the positive electrode of the lithium-ion battery waste is attached.

[0043] The alkaline solution to be brought into contact with the lithium ion battery waste is preferably one having a pH of 13.0 or higher before contact. - The alkaline solution should have a pH of 13.0 or higher and an OH concentration of 5 mol / L or less after contact with lithium-ion battery waste. - The concentration may be maintained below 5 mol / L. If an alkaline solution with too high a pH is used, even if the lithium-ion battery waste can be partially dissolved to remove the metal from the cathode current collector, the alkaline solution will dissolve most of the cathode current collector, resulting in high final wastewater treatment costs. On the other hand, if the pH of the alkaline solution is too low, there is a concern that the aluminum will not dissolve sufficiently. Examples of alkaline solutions that can be used include sodium hydroxide solution and potassium hydroxide solution.

[0044] In addition, in the alkaline separation step, it is preferable to maintain the 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, which may result in the sudden generation of hydrogen and a sudden rise in liquid temperature. If the liquid temperature is too low, the reactivity will decrease, and the alkaline separation step may take a long time. The pulp concentration can be, for example, 20g / L to 500g / L. This pulp concentration refers to 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 hours to 3.0 hours.

[0045] If the heat treatment step is not performed before the alkaline separation step, the lithium in the lithium-ion battery waste may not change into a form such as lithium carbonate that dissolves in an alkaline solution, but may remain in the form of the aforementioned single or composite metal oxide. In this case, the lithium in the lithium-ion battery waste is almost insoluble in the alkaline solution in the alkaline separation step. Therefore, from the viewpoint of suppressing lithium loss in the alkaline separation step, it is preferable that the metal removal method does not include a heat treatment step.

[0046] After the alkaline separation step, an aluminum-containing solution containing dissolved aluminum from the lithium-ion battery waste and fragmented or powdery residue that did not dissolve upon contact with the alkaline solution are obtained. The aluminum-containing solution can be separated and removed in a solid-liquid separation step described below. The aluminum ion concentration of the aluminum-containing solution can 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 alkaline separation step, the residue may contain powdery or other positive electrode-derived metals, as well as fragmented or other shaped positive electrode current collectors such as aluminum foil from which the positive electrode-derived metals have separated. For the purpose of separating and removing such positive electrode current collectors from the positive electrode-derived metals, the re-sieving step described below is preferably performed. Alternatively, when almost the entire positive electrode current collector is dissolved in the alkaline separation step, the residue may not contain the positive electrode current collector. In this case, the re-sieving step can be omitted.

[0048] (Re-sieving process) In the re-sieving step, the residue after the alkali separation step is sieved, and the residue is separated into an over-sieve material containing the positive electrode current collector from which the positive electrode-derived metals were separated in the alkali separation step, and an under-sieve material containing the positive electrode-derived metals separated from the positive electrode current collector in the alkali separation step. The under-sieve material 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] The alkaline separation process described above effectively strips the positive electrode-derived metal from the positive electrode current collector. The positive electrode current collector may have a fragmented or other shape and may be larger in size than the positive electrode-derived metal. Therefore, by selecting and using a sieve with an appropriate mesh size in the re-sieving process, the positive electrode current collector containing aluminum can be effectively removed as the sieved material. In this case, not only the positive electrode current collector but also the negative electrode current collector and separator, which are similarly large in size to the positive electrode current collector and are made of copper or the like, may be removed as the sieved material.

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

[0051] When the solid-liquid separation step is performed after the re-sieving step, the residue after the alkali separation step can be subjected to wet sieving while the residue is still contained in the aluminum-containing solution. When the solid-liquid separation step is performed before the re-sieving step, the residue after the aluminum-containing solution has been separated in the solid-liquid separation step can be subjected to dry sieving in the re-sieving step.

[0052] (solid-liquid separation process) After the alkali separation step, a re-sieving step may be carried out in some cases, followed by a solid-liquid separation step in which the aluminum-containing solution is separated and removed from the residue obtained in the alkali separation step (the under-sieved material in the case of the re-sieving step).

[0053] The solid-liquid separation can be carried out 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) 2, the crushing step, alkali separation step, and sieving step are performed in this order. When the surface of the positive electrode current collector is dissolved in the alkali separation step to separate the positive electrode-derived metal from the positive electrode current collector, the residue after the alkali separation step can be separated into an over-sieved material containing the positive electrode current collector from which the positive electrode-derived metal has been separated in the crushing step and the alkali separation step, and an under-sieved material containing the positive electrode-derived metal separated from the positive electrode current collector in the crushing step and the alkali separation step, respectively.

[0056] Alternatively, in Figure 2, if the alkaline separation step is performed under conditions that dissolve almost the entire positive electrode current collector, the residue after the alkaline separation step may be substantially free of the positive electrode current collector but may contain a negative electrode current collector containing copper. The negative electrode current collector contains copper, the metal to be removed, and is crushed in a crushing step prior to the alkaline separation step. The copper is not dissolved in the alkaline solution in the alkaline separation step and is included in the residue. In this case, a subsequent sieving step can be performed to separate the residue after the alkaline separation step into an oversized material containing the negative electrode current collector crushed in the crushing step and an undersized material containing the positive electrode-derived metal separated from the positive electrode current collector in the crushing step.

[0057] Although not shown in Fig. 2, the solid-liquid separation step can be performed after the alkali separation step and before or after the sieving step. When the solid-liquid separation step is performed before the sieving step, the sieving step can be dry sieving, and when the solid-liquid separation step is performed after the sieving step, the sieving step can be wet sieving.

[0058] 3, the alkali separation step, crushing step, and sieving step are performed in this order. Here, a preliminary sieving step may be performed between the alkali separation step and the crushing step. In the preliminary sieving step, the material is separated into an over-sieved material containing the positive electrode current collector from which the positive electrode-derived metals have been separated in the alkali separation step, and an under-sieved material containing the positive electrode-derived metals separated from the positive electrode current collector in the alkali separation step.

[0059] The mesh size of the sieve used in the preliminary sieving step to separate the oversized material from the undersized material is, for example, 0.15 mm to 1 mm, preferably 0.25 mm to 0.425 mm. The oversized material obtained in the preliminary sieving step contains the positive electrode current collector with the positive electrode-derived metal remaining thereon, and at least a portion of it is subjected to a crushing step to recover the positive electrode-derived metal therefrom. Meanwhile, the undersized material can be used as battery powder A.

[0060] When a preliminary sieving process is performed, in the sieving process after the crushing process, the material is separated into over-sieved material containing positive electrode current collectors from which positive electrode-derived metals have been separated in the crushing process, and under-sieved material containing positive electrode-derived metals separated from the positive electrode current collectors in the crushing process.

[0061] However, for example, if almost all of the positive electrode current collector is dissolved in the alkaline separation step, the preliminary sieving step can be omitted. If the preliminary sieving step is not performed, the residue after the alkaline separation step is subjected to the crushing step. In this case, in the sieving step after the crushing step, the negative electrode current collector and the like crushed in the crushing step can be separated into oversized material. The oversized material contains the positive electrode-derived metals separated from the positive electrode current collector in the crushing step, and this can be used as battery powder B.

[0062] (Acid leaching process) In the acid leaching step, the battery powder is added to an acidic leaching solution such as sulfuric acid, nitric acid, hydrochloric acid, or other inorganic acid to leach the metals in the battery powder with the acid, thereby obtaining a metal-containing solution in which various metals are dissolved.

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

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

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

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

[0067] The metal-containing solution obtained from 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 process) In the metal separation step, metals such as cobalt and nickel can be separated from the metal-containing solution by various known techniques, and the necessary metals can be recovered. Specifically, the metal-containing solution can be neutralized and / or subjected to solvent extraction, etc., to separate and recover the metals in the metal-containing solution.

[0069] (Test example) The following test examples were carried out as tests relating to the above-described metal removal method. The description of these test examples is merely illustrative and is not intended to be limiting.

[0070] We attempted to separate cathode-derived metals from the cathode current collector of lithium-ion battery waste, consisting of process scraps A to C, which did not contain electrolyte, aluminum casings, or copper-containing terminals, by crushing and sieving or alkaline separation. Process scraps A to C differ in the components and structure of the cathode material and their manufacturing methods. In this test, multiple test pieces were extracted from each of process scraps A to C. One test piece was subjected to only crushing and sieving, while the other test piece was subjected to only alkaline separation. Crushing and sieving correspond to the crushing and sieving processes shown in Figures 1 to 3. In other words, in the crushing and sieving process, after the crushing process, the cathode-derived metals and other materials separated from the cathode current collector during the crushing process were sieved under the sieve, while the cathode current collector and other materials were sieved over the sieve in the sieving process. Specifically, in the crushing and sieving step, one of the test pieces was crushed by shear using a crusher, HM-20, manufactured by Orient Crusher Co., Ltd., and then sieved using a sieve with 0.25 mm openings to obtain the under-sieved material. In the alkaline separation step, a sodium hydroxide solution with a concentration of 50 g / L and a pH of 14 was used as the alkaline solution, and the other test piece was immersed in the alkaline solution for 10 to 30 minutes.

[0071] Table 1 shows the recovery rate, grade, and loss of each metal in the undersize material obtained by crushing and sieving and the residue obtained by alkaline separation. In Table 1, "%" is based on mass, and the recovery rate and loss respectively represent the amount after treatment relative to the content in process scraps A to C before treatment. Furthermore, "alkaline stripping" in Table 1 refers to alkaline separation in which, as mentioned above, aluminum on the surface of the positive electrode current collector is dissolved to strip the positive electrode-derived metal from the positive electrode current collector.

[0072] [Table 1]

[0073] As can be seen from Table 1, for process scrap B, nickel, cobalt, and lithium were effectively separated from aluminum in both crushing and sieving and alkaline separation, and the aluminum grade in the under-sieve material and residue was low. Furthermore, lithium loss was minimized. However, for process scrap A, while nickel, cobalt, and lithium were effectively separated from aluminum in alkaline separation, crushing and sieving was insufficient, resulting in a low recovery rate of nickel and cobalt, and the aluminum grade in the under-sieve material was high. Furthermore, for process scrap C, cobalt, nickel, and lithium did not peel off from the aluminum foil in alkaline separation, but nickel, cobalt, and lithium could be separated from aluminum in crushing and sieving.

[0074] As such, there is some process scrap in which nickel, cobalt, and lithium cannot be effectively separated from aluminum by either crushing and sieving or alkaline separation alone. Furthermore, whether effective separation is possible by either crushing and sieving or alkaline separation depends on the process scrap. However, even with such process scrap, nickel, cobalt, and lithium can be effectively separated from aluminum by performing either crushing and sieving or alkaline separation. In other words, by performing both crushing and sieving and alkaline separation, nickel, cobalt, and lithium can be effectively separated from aluminum in either process, regardless of the process scrap.

[0075] This suggests that the aforementioned metal removal method may be able to effectively remove aluminum from lithium-ion battery waste.

Claims

1. 1. A method for removing at least one metal from lithium ion battery waste, comprising: The lithium ion battery waste has a positive electrode material in which a metal derived from a positive electrode is attached to a positive electrode current collector containing aluminum, which is a metal to be removed, a crushing step of shearing and crushing the lithium ion battery waste to separate at least a portion of the metal derived from the positive electrode from the positive electrode current collector; an alkaline separation step of contacting the lithium ion battery waste with an alkaline solution to dissolve the aluminum, thereby separating at least a portion of the metal derived from the positive electrode from the positive electrode current collector; in no particular order, The method further comprises a sieving step of separating the lithium ion battery waste into an over-sieve material and an under-sieve material containing the positive electrode-derived metal separated from the positive electrode current collector in the shredding step, after the shredding step; A method for removing at least one metal, wherein when the sieving step is carried out before the alkali separation step, at least a portion of the sieve residue obtained in the sieving step is subjected to the alkali separation step.

2. 2. The method for removing at least one metal according to claim 1, wherein the alkaline solution with which the lithium ion battery waste is contacted in the alkaline separation step has a pH of 13.0 or higher.

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

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

5. 3. The method for removing at least one metal according to claim 1 or 2, wherein the sieved matter obtained in the sieving step includes the positive electrode current collector from which the positive electrode-derived metal has been separated in the crushing step.

6. 3. The method for removing at least one metal according to claim 1, wherein the alkali separation step is carried out after the crushing step.

7. 7. The method for removing at least one metal according to claim 6, wherein the crushing step, the sieving step, and the alkali separation step are carried out in this order.

8. 8. The method for removing at least one type of metal according to claim 7, further comprising, after the alkali separation step, a re-sieving step of separating the residue from the alkali separation step into an over-sieved material containing the positive electrode current collector from which the positive electrode-derived metal has been separated in the alkali separation step, and an under-sieved material containing the positive electrode-derived metal separated from the positive electrode current collector in the alkali separation step.

9. 9. The method for removing at least one metal according to claim 8, wherein a sieve having an opening size of 0.15 mm to 1 mm is used in the re-sieving step.

10. 7. The method for removing at least one metal according to claim 6, wherein the crushing step, the alkali separation step, and the sieving step are carried out in this order.

11. The lithium ion battery waste has a negative electrode current collector containing copper, which is a metal to be removed, 11. The method for removing at least one type of metal according to claim 10, wherein in the sieving step, the lithium ion battery waste is separated into the over-sieve material containing the negative electrode current collectors crushed in the crushing step and the under-sieve material.

12. 3. The method for removing at least one metal according to claim 1, wherein the alkali separation step, the crushing step, and the sieving step are carried out in this order.

13. the method further includes a preliminary sieving step, performed after the alkali separation step and before the crushing step, of separating a residue from the alkali separation step into an over-sieved material containing the positive electrode current collector from which the positive electrode-derived metal has been separated in the alkali separation step and an under-sieved material containing the positive electrode-derived metal separated from the positive electrode current collector in the alkali separation step, 13. The method for removing at least one type of metal according to claim 12, wherein at least a portion of the over-sieved material obtained in the pre-sieving step is subjected to the crushing step.

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

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

16. 3. The method for removing at least one metal according to claim 1 or 2, wherein the sieving step uses a sieve having an opening size of 0.15 mm to 1 mm.

17. A metal recovery method for recovering metals from battery powder obtained by removing target metals from lithium ion battery waste using at least one method for removing metals according to claim 1 or 2.

Images