Metal recycling methods

Abstract

To provide a metal recovery method that can effectively separate impurity metals from large-diameter sieved material obtained by sieving. [Solution] A method for recovering a metal containing at least one of cobalt and nickel from lithium-ion battery waste, comprising the steps of: heat-treating the waste; crushing the lithium-ion battery waste after the above step to obtain crushed material; separating the crushed material by sieving into small-diameter sieved material with relatively small particle size, large-diameter sieved material with relatively large particle size, and medium-diameter sieved material with a particle size intermediate between the small-diameter sieved material and the large-diameter sieved material; performing magnetic separation on the large-diameter sieved material to extract magnetically attached material from the large-diameter sieved material; crushing the magnetically attached material to obtain re-crushed material; separating the re-crushed material by sieving into unsieved material and sieved material containing copper; and an eddy current separation step in which non-magnetic conductive material containing copper is separated from the sieved material by eddy current separation and magnetic material containing at least one of cobalt and nickel is extracted as magnetically attached material.

Description

Technical Field

[0001] This specification relates to a method for recovering a metal containing at least one of cobalt and nickel from lithium-ion battery waste.

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] The battery cells of the above in-vehicle battery packs generally use secondary batteries that can store electricity by charging and be repeatedly used, especially nickel-hydrogen batteries. In recent years, however, lithium-ion batteries using lithium transition metal composite oxides for the positive electrode have been used. Such in-vehicle lithium-ion batteries contain valuable metals such as cobalt. Therefore, when in-vehicle lithium-ion batteries are discarded after use or the like, from the viewpoint of effective utilization of resources, it is desirable to easily recover the valuable metals that may be contained in the lithium-ion battery waste at a relatively low cost for reuse.

[0004] Incidentally, when recovering valuable metals from lithium-ion battery waste, not limited to automotive batteries, pretreatment of the lithium-ion battery waste is sometimes performed to obtain battery powder that contains as much of the positive electrode active material metal as possible while removing impurities that are not to be recovered. Then, as a wet treatment, the metals in the battery powder may be leached out with acid or the like, and various metals may be recovered from the resulting leached liquid. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2006-179190 [Patent Document 2] Japanese Patent Publication No. 2007-172938 [Patent Document 3] U.S. Patent Application Publication No. 2007 / 0141454 [Patent Document 4] Japanese Patent Publication No. 2007-172939 [Patent Document 5] U.S. Patent Application Publication No. 2007 / 0141455 [Patent Document 6] Japanese Patent Publication No. 2011-198713 [Overview of the project] [Problems that the invention aims to solve]

[0006] In the pretreatment process for obtaining battery powder from lithium-ion battery waste, a sieving process is performed after processes such as heat treatment and crushing. In the sieving process, the material may be separated into at least small-diameter sieved material with relatively small particle sizes, large-diameter sieved material with relatively large particle sizes, and medium-diameter sieved material with particle sizes intermediate between the small-diameter and large-diameter sieved material.

[0007] Of these, the material separated by the small-diameter sieve can be effectively recovered as battery powder through wet processing to recover its metal content.

[0008] On the other hand, while the large-diameter sieved material may contain valuable metals such as nickel and / or cobalt, it also contains a certain amount of impurity metals such as copper and aluminum. If the content of these impurity metals can be reduced by some treatment of the large-diameter sieved material, it is considered possible to include it in the battery powder along with the small-diameter sieved material and subject it to wet processing.

[0009] This specification provides a metal recovery method that can effectively separate impurity metals from large-diameter sieved material obtained by sieving. [Means for solving the problem]

[0010] The metal recovery method disclosed in this specification is a method for recovering a metal containing at least one of cobalt and nickel from lithium-ion battery waste, comprising: a heat treatment step of heat treatment of the lithium-ion battery waste; a crushing step of crushing the lithium-ion battery waste after the heat treatment step to obtain crushed material; and a sieve of the crushed material to obtain at least small-diameter sieved material with a relatively small particle size, large-diameter sieved material with a relatively large particle size, and material with a particle size intermediate between the small-diameter sieved material and the large-diameter sieved material. The process includes a sieving step of separating the material into medium-sized sieved material and large-sized sieved material; a magnetic separation step of performing magnetic separation on the large-sized sieved material to extract magnetically attached material from the large-sized sieved material; a re-crushing step of crushing the magnetically attached material to obtain re-crushed material; a re-sieving step of separating the re-crushed material into unsieved material and unsieved material containing copper by sieving; and an eddy current separation step of separating non-magnetic conductive material containing copper from the unsieved material by eddy current separation and extracting magnetic material containing at least one of cobalt and nickel as magnetically attached material. [Effects of the Invention]

[0011] According to the metal recovery method described above, impurity metals can be effectively separated from the large-diameter sieved material obtained by sieving. [Brief explanation of the drawing]

[0012] [Figure 1] This is a flowchart illustrating a metal recovery method according to one embodiment. [Figure 2] This is a flowchart showing the wet treatment of the battery powder obtained in the metal recovery process shown in Figure 1. [Modes for carrying out the invention]

[0013] The embodiments of the metal recovery method described above will be explained in detail below. One embodiment of the metal recovery method is a method for recovering a metal containing at least one of cobalt and nickel from lithium-ion battery waste.

[0014] As shown in Figure 1, this metal recovery method includes a heat treatment step in which lithium-ion battery waste is subjected to heat treatment, a crushing step in which the lithium-ion battery waste after the heat treatment step is crushed to obtain crushed material, and a sieving step in which the crushed material is separated into at least three types of sieved materials with different particle sizes by sieving. The three types of sieved materials separated in the sieving step are small-diameter sieved materials with relatively small particle sizes, large-diameter sieved materials with relatively large particle sizes, and medium-diameter sieved materials with particle sizes intermediate between the small-diameter and large-diameter sieved materials. Regarding the distinction of small-diameter, medium-diameter, and large-diameter sieved materials by particle size, when sieving is performed using a sieve having a grid-like arrangement of sieve holes with a predetermined side length, the sieved material that passes through the sieve shall have a particle size equal to or greater than the predetermined side length of the sieve holes, or the sieved material that passes below the sieve shall have a particle size less than the side length of the sieve holes.

[0015] If the large-diameter sieved material is included directly in the battery powder, it will increase the purity of impurity metals such as aluminum and copper in the battery powder. On the other hand, if the large-diameter sieved material is not included in the battery powder at all, it will result in a loss of cobalt and / or nickel contained in the large-diameter sieved material. Therefore, it is necessary to separate the aluminum and copper from the large-diameter sieved material and recover the cobalt and / or nickel.

[0016] Therefore, in this embodiment, a magnetic separation step, a re-crushing step, a re-screening step, and an eddy current separation step are performed on the large-diameter screened material. Specifically, as shown in FIG. 1, the metal recovery method of this embodiment includes a magnetic separation step of performing magnetic separation on the large-diameter screened material and removing the magnetically attached material from the large-diameter screened material, a re-crushing step of crushing the magnetically attached material to obtain re-crushed material, a re-screening step of separating the re-crushed material by screening into undersize material and oversize material containing copper, and an eddy current separation step of separating non-magnetic conductive material containing copper from the oversize material by eddy current separation and taking out the magnetic material containing at least one of cobalt and nickel as the magnetically attached material. Thereby, aluminum and copper can be effectively separated from cobalt and / or nickel. Then, by including the undersize material obtained by the re-screening step and the magnetically attached material obtained by the eddy current separation step on the oversize material in the battery powder, the recovery rate of cobalt and nickel can be increased.

[0017] Depending on the type of lithium-ion battery waste and other conditions, the ratio of aluminum and copper to cobalt and nickel may be high. Also, depending on the crushing conditions in the crushing step, etc., the crushed material may contain crushed pieces where copper foil and aluminum foil overlap. In this case, the copper foil overlapping with the aluminum foil is also transferred to the magnetically attached material as if dragged by the aluminum foil that becomes the magnetically attached material in the subsequent magnetic separation step, and this can be included in the oversize material after passing through the re-crushing step and the re-screening step. Even if a lithium leaching step and an alkali leaching step are performed on the oversize material, copper remains in the residue of each step and is not removed. In contrast, in this embodiment, by performing an eddy current separation step on the oversize material, such copper can be effectively separated. As a result, battery powder with a low copper grade can be obtained.

[0018] (Lithium-ion battery waste) Lithium-ion battery waste refers to various in-vehicle lithium-ion batteries that can be installed in vehicles such as hybrid vehicles, fuel cell vehicles, and electric vehicles. It can be waste discarded due to vehicle scrapping, battery replacement, manufacturing defects, or other reasons. However, it is not limited to in-vehicle lithium-ion battery waste, and various lithium-ion battery wastes for other uses can also be targeted. Lithium-ion battery waste refers to lithium-ion batteries that are targets 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.

[0019] The lithium-ion batteries included in such lithium-ion battery waste contain a positive electrode material, a negative electrode material, an electrolyte, and an aluminum casing around them. Here, the positive electrode material and the negative electrode material can be respectively composed of a positive electrode active material or a negative electrode active material fixed on a positive electrode current collector such as an aluminum foil or a negative electrode current collector such as a copper foil by, for example, polyvinylidene fluoride (PVDF) or other organic binders. Among these, for 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. Examples of such positive electrode active materials include LiCoO2, LiNiO2, Li-Co-Ni-O2, Li-Co-Ni-Mn-O, etc. The metals contained in the positive electrode active material are preferably recovered as valuable metals from the perspective of effective utilization of resources. In this embodiment, the metals contained in the positive electrode active material can change in form from the above oxides in a heat treatment process or the like described later, but regardless of the form, the metals derived from the positive electrode active material (hereinafter also referred to as "positively derived metals"), at least cobalt and / or nickel, are targeted for recovery. Further, lithium may also be targeted for recovery. Note that carbon-based materials are often used for the negative electrode active material, and electrolyte solutions such as ethylene carbonate or diethyl carbonate are often used for the electrolyte. In addition, in-vehicle lithium-ion battery waste may include terminals containing copper and / or iron, an iron casing, a stainless steel casing, etc.

[0020] Automotive lithium-ion battery waste often has a metal frame containing iron as its outer casing, with lithium-ion battery cells housed within this frame. The metal constituting the frame may be primarily composed of iron. This type of lithium-ion battery waste often contains multiple battery cells, which are bundled together to form battery modules, and these modules are then connected to each other. Lithium-ion battery waste may also include a Battery Management System (BMS) for monitoring each battery cell, a cooling device for cooling the battery, and wires connecting them. The wires are made of copper-containing metal, such as copper wires (Cu wires), and connect each battery cell to the BMS to transmit information such as the temperature and voltage of each battery cell to the BMS. In addition, resin components containing glass fibers may be provided between or around the battery cells. The glass fibers may contain calcium and / or magnesium.

[0021] (Heat treatment process) In the heat treatment process, the lithium-ion battery waste described above can be heated directly in the heat treatment furnace without being disassembled. Because automotive lithium-ion battery waste has a robust structure, it is not easy to disassemble it before heat treatment, and disassembling it before heat treatment poses a risk of electric shock due to residual voltage.

[0022] The heat treatment removes the electrolyte from the lithium-ion battery waste, and also pulverizes any resin components that may be present inside the frame of the lithium-ion battery waste, turning them into resin powder.

[0023] During heat treatment, it is preferable to heat the lithium-ion battery waste at a temperature of 350°C to 650°C for 1 to 8 hours. This may convert the positive electrode active material in the lithium-ion battery waste into at least one of metallic cobalt (Co) and cobalt oxide (CoO). The positive electrode active material may also be converted into at least one of metallic nickel (Ni) and nickel oxide (NiO, etc.). The positive electrode active material does not exhibit magnetism, but metallic cobalt and metallic nickel do. Therefore, by adjusting the heating temperature, the magnetic deposits can be made to contain the above-mentioned metallic cobalt and / or metallic nickel in the subsequent magnetic separation and eddy current separation processes, improving the recovery rate of cobalt and nickel. If the heating temperature is too low, there are concerns that the decomposition of lithium metal oxide and the reduction of nickel oxide and cobalt oxide obtained after decomposition will be insufficient, and that organic substances such as electrolytes will not be sufficiently removed. On the other hand, if the heating temperature is too high, there is a risk that the aluminum in the aluminum foil will melt, leading to an increase in the amount of impurities mixed in during wet processing. From this perspective, it is even more preferable that the heating temperature be between 400°C and 600°C.

[0024] Furthermore, if the holding time at the aforementioned heating temperature is too short, especially in the case of automotive lithium-ion battery waste with a robust structure surrounded by a metal frame, the heat treatment may not be sufficient, potentially leaving behind a large amount of organic matter. However, if the holding time is too long, depending on the atmosphere, various components may oxidize and become brittle, raising concerns that they may mix with the battery powder as impurities. For this reason, it is preferable to set the holding time to 2 to 9 hours. The holding time may be 6 to 9 hours or 2 to 4 hours.

[0025] Heating during heat treatment can be carried out in various atmospheres, such as air, a vacuum or other reduced pressure atmosphere, or an inert atmosphere such as nitrogen, but is not limited to these. In particular, heating in a reduced pressure atmosphere or an inert atmosphere prevents the combustion of the flammable electrolyte, thus suppressing the melting of the battery cell housing and the generation of lithium aluminate (LiAlO2). If lithium aluminate is generated, the aluminum foil becomes brittle and is more likely to be mixed into the battery powder. On the other hand, aluminum foil that does not react with lithium aluminate can be easily separated in a subsequent sieving process. Thus, heating in a reduced pressure atmosphere or an inert atmosphere is preferable because it can suppress the mixing of aluminum into the battery powder. When heating in an air atmosphere, the heating temperature may become relatively high depending on the conditions, which can lead to the melting of the housing and pulverization of the aluminum foil. In addition, there is a concern that lithium aluminate may be generated by the reaction of aluminum foil with lithium, a metal derived from the positive electrode, due to oxygen in the atmosphere, and that these may be mixed into the battery powder. An increase in the aluminum content of the battery powder may lead to increased loss of cobalt and nickel during subsequent wet processing to remove the aluminum. Furthermore, if the melting of the battery cell housing is prevented by heating under reduced pressure or an inert atmosphere, it becomes easier to remove the resin powder containing magnesium and calcium derived from the resin components in the component removal process described later.

[0026] The heat treatment under an inert atmosphere can specifically be an atmosphere containing at least one selected from the group consisting of nitrogen, carbon dioxide, and water vapor. Among these, an atmosphere mainly containing nitrogen is preferred. The heat treatment may be carried out while flowing such an inert gas. Oxygen may be included in a certain amount. When the oxygen concentration is sufficiently low, the embrittlement of aluminum in battery waste can be suppressed. If aluminum becomes embrittlement during heat treatment, there is a concern that the separation performance of aluminum will deteriorate during the sieving process described later. When an inert gas is introduced into the heat treatment furnace, the oxygen concentration in the heat treatment furnace should be, for example, 0.05 volume% to 4.00 volume%, preferably less than 1 volume%, and more preferably less than 0.1 volume%.

[0027] Heating in an atmospheric environment can suppress the foaming phenomenon that occurs when the battery powder is leached with acid during the subsequent wet treatment process. Heating in an atmospheric environment can also remove tar caused by resin decomposition in the heat treatment furnace and ducts. However, it is important that the oxidation is kept to a degree that does not cause the aluminum to become brittle.

[0028] The heat treatment furnace used to heat lithium-ion battery waste is not particularly limited, but for example, if it is a batch type, an atmosphere-type electric furnace or an atmosphere-type muffle furnace can be used, or if it is a continuous type, a roller hearth kiln or a mesh belt kiln can be used. Among these, roller hearth kilns and pusher kilns are preferred because they are suitable for processing large quantities.

[0029] Furthermore, after heat treatment, certain components may be removed from the lithium-ion battery waste as needed.

[0030] During component removal, metal frames and terminals containing iron (typically made of stainless steel) can be removed from lithium-ion battery waste. This removes most of the iron contained in the lithium-ion battery waste, significantly reducing the amount of iron contaminating the battery powder. As a result, the burden required for iron removal through wet processing can be reduced.

[0031] Furthermore, during component removal, resin powder obtained by pulverizing the resin component during heat treatment can be removed from lithium-ion battery waste. Such resin powder may contain calcium and / or magnesium derived from glass fibers, etc., in the resin component. If calcium is mixed into the battery powder, it can cause problems such as blockage during solvent extraction in subsequent wet processing. Also, magnesium becomes an impurity in the cobalt and nickel finally obtained after wet processing, degrading their quality. For this reason, it is preferable to remove the resin powder during component removal.

[0032] Furthermore, during component removal, it is preferable to remove copper-containing metal wires from lithium-ion battery waste. This is because copper is also an impurity metal, and its presence in the battery powder increases the load on the wet processing stage.

[0033] In addition, during parts removal, it is possible to remove parts other than the frame, leaving the frame intact. In this case, the parts removal process can be automated using a vibratory feeder, trommel sieving machine, air blower, etc., instead of manual labor. When automated, it may be possible to remove 99.5% or more by mass of resin powder and metal wires containing copper. If the frame is left intact during parts removal, it will be crushed in the crushing process described later, but iron originating from the frame may be mixed into the large-diameter sieved material during the sieving process. To remove such iron, as described later, it is desirable to perform a preliminary magnetic separation on the medium-diameter and large-diameter sieved materials obtained in the sieving process, before the eddy current separation process or the magnetic separation process, to separate the iron from the medium-diameter and large-diameter sieved materials by low magnetic force separation.

[0034] (Crushing process) In the crushing process, lithium-ion battery waste that has undergone the heat treatment process is crushed. This crushing destroys the battery cell casing, and metals derived from the positive electrode, such as nickel and cobalt, are separated from the aluminum foil, resulting in crushed material.

[0035] Various known crushers can be used here, but specific examples include impact-type crushers that can crush the case and battery by applying impact while cutting them, such as sample mills, hammer mills, pin mills, wing mills, tornado mills, and hammer crushers. A screen can be installed at the outlet of the crusher, so that the battery is crushed to a size that can pass through the screen and then discharged from the crusher through the screen.

[0036] In the crushing process, for example, lithium-ion battery waste with dimensions of several tens of millimeters (e.g., 120mm x 80mm x 10mm) can be crushed into smaller fragments of several tens of millimeters. When lithium-ion battery waste is finely crushed in the crushing process, the aluminum foil and copper foil are made finer, and impurity metals such as aluminum and copper are included in the small-diameter sieved material in the sieving process, and consequently, are more likely to be included in the battery powder. The size of the crusher screen can be, for example, 10mm to 30mm.

[0037] (sieving process) The crushed material obtained in the crushing process described above is subjected to sieving in a sieving process, and is separated into at least three types of sieved materials with different particle sizes: small-diameter sieved material, medium-diameter sieved material, and large-diameter sieved material.

[0038] For the sieve used in this process, the largest mesh size can be, for example, 9.16 mm. The large-diameter sieved material can be the material that passes through the 9.16 mm sieve and the material that passes through the intermediate mesh sizes described later, and may also include material that passes through the 9.16 mm sieve. The particle size of the large-diameter sieved material may be, for example, 1 mm or larger, and may also be 4.75 mm or larger. The large-diameter sieved material may include materials in which cobalt or nickel is still attached to aluminum foil, or materials in which cobalt or nickel has not been separated from aluminum or copper. The lower limit of the particle size of the sieved material, such as the large-diameter sieved material, means that when sieved with a sieve having grid-like sieve holes with a side length equal to that lower limit, the sieved material will pass through that sieve. On the other hand, the upper limit of the particle size of the sieved material means that when the material is sieved using a sieve with a grid of sieve holes equal to the side length of that upper limit, the sieved material will fall below the sieve's sieving threshold. The same applies to the particle sizes of the magnetic material, re-crushed material, and sieved material, which will be discussed later.

[0039] Furthermore, it is preferable to use a sieve with a mesh size of 0.425 mm or less, for example, 0.25 mm, as the smallest mesh size. If a sieve with a mesh size that is too large is used, impurity metals such as aluminum and copper are more likely to migrate to the small-diameter sieved material, and the amount of impurity metals mixed into the battery powder tends to increase. On the other hand, if a sieve with a mesh size that is too small, nickel and cobalt will not pass through the sieve, and the recovery rate of valuable metals will decrease. For this reason, it is preferable to set the mesh size of the sieve to 0.15 mm or larger. By sieving with the smallest mesh size described above, the particle size of the small-diameter sieved material is preferably less than 0.25 mm, and aluminum and copper are sufficiently removed, while lithium, cobalt, and nickel are present in large quantities. The small-diameter sieved material can be used directly as battery powder for wet processing.

[0040] Furthermore, the mesh size of the intermediate sieve is preferably 1 mm to 4.75 mm, or 1 mm in one example. The intermediate sieve residue is the residue below the intermediate sieve and the residue above the sieve with the smallest mesh size. The particle size of the intermediate sieve residue may be, for example, 0.425 mm or more and less than 4.75 mm, or 0.25 mm or more and less than 4.75 mm. Although intermediate sieve residue of this size may contain impurity metals such as aluminum and copper, the cobalt and nickel are often basically separated from the aluminum and copper, and these can be effectively separated in the eddy current separation process described later. Eddy current separation may be difficult for particles with a particle size of 4.75 mm or more.

[0041] As mentioned earlier, if the frame is not removed in the parts removal process after heat treatment, the iron-based or other metal frame may be crushed in the crushing process, and the crushed fragments may be separated into medium-diameter and large-diameter sieved materials in the sieving process. In this case, it is preferable to perform preliminary magnetic separation before the eddy current separation process for the medium-diameter sieved materials or the magnetic separation process for the large-diameter sieved materials to remove crushed iron or other materials from the medium-diameter and large-diameter sieved materials. Various magnetic separators can be used as long as the iron can be recovered as magnetically deposited material.

[0042] In the preliminary magnetic separation, low-magnetic force separation is performed to separate ferromagnetic (high-permeability) iron as magnetically attached material. Specifically, it is preferable to use a magnetic force with a surface magnetic flux density of, for example, 900 gauss or less, typically 350 to 550 gauss. Here, surface magnetic flux density refers to the magnetic flux density on the surface at the position where the medium-diameter or large-diameter sieve material is subjected to magnetic force in the magnetic separator. For example, in a pulley-type magnetic separator in which a belt conveyor is wrapped around a magnetic pulley, it is the surface magnetic flux density on the magnetic pulley when the large-diameter sieve material on the belt conveyor passes through the magnetic pulley. The same applies to the surface magnetic flux density in the magnetic separation process described later.

[0043] (Magnetic selection process) In the magnetic separation process, magnetic separation is performed on the large-diameter sieved material to separate the magnetically attached material from the sieved material. Here, various known magnetic separators can be used as long as they can separate the specified magnetically attached material.

[0044] For magnetic separation, it is preferable to use a magnetic force with a surface magnetic flux density of 5000 gauss or more. Metallic cobalt (Co), metallic nickel (Ni), and cobalt-nickel alloys exhibit ferromagnetism. Therefore, if only these ferromagnetic metals are to be recovered as magnetically deposited materials, the magnetic force used for magnetic separation can be relatively weak. On the other hand, the cobalt and nickel in the large-diameter sieved material include those that remain attached to the aluminum foil without being separated from it during the crushing process. Since aluminum is not magnetic, the magnetism of cobalt and nickel is weakened in aluminum foil to which cobalt and nickel are attached, making it difficult for the entire material to be magnetically deposited. For this reason, at low surface magnetic flux densities, it is not possible to magnetically deposit cobalt and nickel onto aluminum foil, and therefore it is not possible to recover the cobalt and nickel. In contrast, as described above, by using a strong magnetic force of 5000 gauss or more, cobalt and nickel attached to aluminum foil can also be magnetically deposited, and a large portion of the nickel and cobalt in the large-diameter sieved material can be included in the magnetically deposited material.

[0045] (Re-crushing process) The magnetic deposits obtained in the magnetic separation process described above are crushed in a re-crushing process to obtain re-crushed material. Here, the magnetic deposits are crushed to a certain degree of fineness, mainly removing the positive electrode-derived metals that adhere to the aluminum foil, while minimizing the crushing of aluminum foil that does not have positive electrode-derived metals attached. For example, if the magnetic deposits have a particle size of about 30 mm or less, the re-crushing process may produce re-crushed material with a particle size of several mm.

[0046] In the re-crushing process, various types of crushers can be used, similar to the crushing process, but the use of a shear-type crusher is preferable. As mentioned above, this is to scrape off the positive electrode-derived metals adhering to the aluminum foil. With a shear-type crusher, good results can be obtained whether a vertical or horizontal crusher is used. If a crusher that is solely for the purpose of fine reduction, such as a single-shaft or twin-shaft crusher, is used, the aluminum foil will also be crushed, which may increase the amount of aluminum impurity metals mixed in. The screen size of the crusher used in the re-crushing process is sometimes set to about 3 mm. The smaller the screen size, the better the removal of cobalt, nickel, and lithium, but if it is too small, fine aluminum fragments from the casing may cause clogging of the screen or chipping of the rotating blades. Note that the aluminum fragments are those that were incorporated into the aluminum foil with positive electrode-derived metals that was rolled up in the crushing process and moved to the magnetic material side during the high-magnetic separation in the magnetic separation process.

[0047] (Re-sieving process) After the re-crushing process, the resulting re-crushed material is sieved in a re-sieving process to separate it into sieved material and unsieved material.

[0048] In the re-sieving process, it is preferable to use a sieve with a mesh size of 0.25 mm or less, as this allows cobalt, nickel, etc., to be sieved down and aluminum to be sieved up. This results in a sieved material containing a large amount of valuable metals such as cobalt and nickel. The sieved material, along with the small-diameter sieved material mentioned above, can be subjected to wet processing as battery powder.

[0049] The particle size range of the sieved material obtained in the re-sieving process, in other words, the particle size range of the sieved material subjected to the eddy current separation process described later, may overlap with the particle size range of the medium-diameter sieved material. For example, the overlapping range between the particle size range of the sieved material and the particle size range of the medium-diameter sieved material may be 0.25 mm to 1 mm. While it is conceivable to repeat the magnetic separation process described above as a method for separating copper and aluminum from cobalt and / or nickel, magnetic separation may result in poor separation efficiency for sieved material containing particles as fine as those of the medium-diameter sieved material. For this reason, eddy current separation is more effective in separating copper and aluminum.

[0050] The particle size of the sieved material obtained in the re-sieving process may be, for example, 0.25 mm or larger, typically within the range of 0.25 mm or larger and less than 3 mm. For sieved material containing such relatively fine particles, eddy current separation of non-magnetic conductive materials and magnetic materials is effective.

[0051] The sieved material obtained in the re-sieving process contains copper, with a copper content of, for example, 5% to 70% by mass, typically ranging from 5% to 55% by mass. Furthermore, the sieved material obtained in the re-sieving process also contains aluminum, with an aluminum content of, for example, 5% to 60% by mass, typically ranging from 10% to 45% by mass.

[0052] (Eddy current sorting process) In the eddy current separation process, eddy current separation is used to separate non-magnetic conductive materials containing copper from the copper-containing sieved material obtained in the re-sieving process, and magnetic materials containing at least one of cobalt and nickel are extracted as magnetically deposited materials. Here, the non-magnetic conductive materials may also contain aluminum.

[0053] It has been found that the sieved material obtained in the re-sieving process sometimes contains a relatively large amount of copper in addition to aluminum. For example, lithium-ion batteries for hybrid vehicles, which are designed with a relatively large amount of current collector relative to the positive electrode active material, tend to contain a large amount of copper in the sieved material. Ideally, the copper foil and aluminum foil should be separated by crushing the lithium-ion battery waste in the crushing process, and in the magnetic separation process, the copper foil is distributed to the non-magnetic material, while the aluminum foil, with cobalt and nickel attached, is distributed to the magnetic material, thus allowing the copper to be removed in the magnetic separation process. However, the reason why the sieved material contains a relatively large amount of copper is that in the crushing process of lithium-ion battery waste after the heat treatment process, the copper foil and aluminum foil cannot be sufficiently separated, and crushed fragments in which copper foil and aluminum foil overlap are included in the crushed material. Consequently, the magnetic material obtained in the magnetic separation process of large-diameter sieved material also contains crushed fragments in which copper foil and aluminum foil overlap. In contrast, according to the metal recovery method of the embodiment described herein, even if the magnetic deposits obtained in the magnetic separation process contain crushed pieces in which copper foil and aluminum foil overlap, by performing an eddy current separation process after the re-crushing process and re-sieving process, at least one of cobalt and nickel becomes magnetic, and copper and aluminum, which are non-magnetic conductors, can be effectively separated from these magnetic deposits.

[0054] For eddy current separation, a known eddy current separator can be used, for example, one equipped with a belt conveyor having a belt for transporting the object (in this case, the sieved material) and a pulley around which the belt is wound and driven to rotate. Inside the pulley is a rotor that rotates at high speed to generate a high-frequency alternating magnetic field. The rotor has alternating north and south poles arranged in the circumferential direction, and when it rotates at high speed, an alternating magnetic field is generated. When conductive metal (non-magnetic conductor) in the object being transported by the belt passes through the alternating magnetic field, eddy currents proportional to the alternating magnetic field are generated in the metal, and the magnetic force generated from these currents creates a repulsive effect with the magnetic force of the rotor, separating the metal (non-magnetic conductor). On the other hand, magnetic metal (magnetic material) in the object basically adheres to the belt surface due to the magnetic force of the rotor, is sent to the lower side of the pulley, and falls off the belt surface when the influence of the magnetic force weakens.

[0055] When performing eddy current separation, if the object contains a large amount of iron, which is easily attracted to magnets, the iron will accumulate on the pulley (in this case, on the belt), causing the belt to burn out due to induction heating. As mentioned earlier, when a metal frame containing iron is removed in the parts removal process, or when the crushed frame fragments are separated in the preliminary magnetic separation process, the large-diameter sieve contains almost no iron, and it is possible to apply eddy current separation to the sieved material obtained from the large-diameter sieve. Furthermore, metallic cobalt and metallic nickel that may be contained in the large-diameter sieve after undergoing the heat treatment process have lower magnetic permeability than iron, and CoO and NiO also have lower magnetic permeability than iron. Moreover, since all of them are mixtures with non-magnetic carbon, accumulation on the pulley is unlikely to occur.

[0056] Copper and aluminum contained in the sieved material are non-magnetic conductors. When magnetic materials such as cobalt and nickel are drawn to the belt surface by the rotor's magnetic force, the repulsive force of eddy currents overcomes the effect of these materials, causing them to be pulled away from the belt surface. On the other hand, cobalt and nickel contained in the sieved material are magnetic materials. They adhere to the belt surface due to the rotor's magnetic force and do not separate from the belt surface even when repulsive forces from eddy currents act on them. Therefore, eddy current sorting can separate non-magnetic conductors such as aluminum and copper from the sieved material, allowing for the extraction of magnetic materials such as cobalt and nickel.

[0057] It is presumed that some copper and aluminum particles, among the sieved material, become trapped in cobalt and nickel particles and adhere to the belt. These trapped copper and aluminum particles are thought to be weakly magnetized to the belt surface by the rotor's magnetic force due to the cobalt and nickel present individually.

[0058] The particles contained in the sieved material are thought to be separated around the pulley in the following way: First, due to the inertial force from the movement of the belt, particles composed of copper and aluminum are separated on the upper side of the pulley. Next, although the group of particles containing copper and aluminum and having weak magnetism do not leave the belt surface due to inertial force, they are repelled from the belt surface on the upper side of the pulley by the repulsive effect of eddy currents, causing the copper and aluminum to separate. Subsequently, as the belt separates from the pulley on the lower side, the influence of the magnetic force weakens, so the group of particles that have adhered up to this point, which have a large proportion of copper and aluminum and relatively weak magnetic adhesion, free fall and separate. The particles that remain attached to the belt surface until the end are those composed of cobalt and nickel, and the group of particles with little copper and aluminum attached to the cobalt and nickel, where there is almost no repulsive force, and these are ultimately recovered as magnetic deposits.

[0059] Thus, to separate impurity metals such as aluminum and copper from sieved material containing relatively fine particulate matter such as cobalt, nickel, aluminum, and copper, eddy current separation, which utilizes not only the inertial force from the movement of the belt but also the repulsive force from eddy currents, is effective, and in some cases it can separate aluminum and copper by more than 90% by mass.

[0060] The rotor rotation speed inside the pulley of the eddy current separator is preferably set to 1500 rpm to 2500 rpm. If the rotor rotation speed is too high, nickel and cobalt may also be repelled. Conversely, if the rotor rotation speed is too low, there is a concern that copper and aluminum will not be repelled.

[0061] Below the pulley of the eddy current separator, a partition plate is provided to guide non-magnetic conductive materials separated by eddy current generation and free fall from the sieved material conveyed around the pulley on the belt, and magnetic materials that adhere to the belt surface and then fall, to different discharge ports.

[0062] Incidentally, in eddy current separators, under certain conditions, such as when the belt speed is slow, cobalt and nickel may accumulate on the upper side of the pulley and remain in that one spot, causing the amount of accumulation to gradually increase. To prevent this, it is preferable to use a belt with an uneven surface.

[0063] Furthermore, when performing eddy current separation, the surface magnetic flux density on the pulley when the sieved material on the belt conveyor of the eddy current separator passes through the pulley may be set to, for example, 2000 gauss to 3000 gauss, typically 2500 gauss or less.

[0064] The magnetic deposits obtained by separating non-magnetic conductive materials using the eddy current separation method described above have copper and aluminum removed, resulting in a high purity of cobalt and / or nickel. When these magnetic deposits are subjected to wet processing as battery powder along with the previously mentioned small-diameter sieved materials and unsieved materials, the recovery rate of cobalt and / or nickel can be improved. For example, the cobalt purity of the magnetic deposits obtained by separating non-magnetic conductive materials using the eddy current separation method described above may be 3% to 40% by mass, the nickel purity 3% to 40% by mass, the manganese purity 3% to 40% by mass, the lithium purity 3% to 7% by mass, the aluminum purity 3% to 70% by mass, and the copper purity 1% to 5% by mass.

[0065] On the other hand, since the magnetic deposits extracted by separating non-magnetic conductive materials through eddy current separation may contain a relatively large amount of aluminum attached to cobalt or nickel, it is preferable to subject these magnetic deposits to further appropriate processing rather than treating them as battery powder.

[0066] For example, in this embodiment, it is preferable to include a lithium leaching step in which the magnetic material obtained by eddy current separation is brought into contact with a liquid to leach lithium from the magnetic material into the liquid, the pH of the liquid at the end of the lithium leaching is set to 7 to 13, and the residue and a lithium-containing solution are obtained. Furthermore, it is preferable to include an alkaline leaching step in which the residue after the lithium leaching step is brought into contact with an alkaline solution to leach aluminum from the residue into the alkaline solution, and the residue and an aluminum-containing solution are obtained.

[0067] To remove aluminum from a magnetic deposit, it is effective to leach the aluminum by contacting it with an alkaline solution before acid leaching. However, when a magnetic deposit is brought into contact with an alkaline solution, not only the aluminum but also the lithium in the magnetic deposit leachs into the alkaline solution, resulting in lithium loss. In contrast, in the above embodiment, lithium is separated and recovered to some extent from the magnetic deposit in the lithium leaching step beforehand. This reduces the amount of lithium leached into the alkaline solution in the subsequent alkaline leaching step compared to when the alkaline leaching step is performed without going through the lithium leaching step. More details are described below.

[0068] (Lithium leaching process) In the lithium leaching process, the magnetic material obtained in the eddy current separation process is brought into contact with the liquid by immersing it in the liquid and stirring it, thereby selectively leaching the lithium from the magnetic material into the liquid. The liquid used is one whose pH becomes 7 to 13 after contact with the magnetic material.

[0069] By performing a lithium leaching process prior to the subsequent alkali leaching process, lithium in the magnetic material can be leached into a liquid and recovered. As a result, the loss of lithium that would otherwise leach out along with aluminum during the alkali leaching process can be suppressed.

[0070] The liquid brought into contact with the magnetic material during the lithium leaching process is not particularly limited as long as its pH is between 7 and 13 at the end of the lithium leaching process; the pH before contact with the magnetic material may be less than 7. The pH of the liquid before contact with the magnetic material may be between 2 and 10. Here, pH refers to the value measured at room temperature (typically 20°C), and if the liquid temperature is higher, the pH after it has cooled to room temperature shall be used. The liquid is typically water, and specifically, tap water, industrial water, distilled water, purified water, deionized water, pure water, ultrapure water, etc., can be used. The liquid temperature at the time of contact between the magnetic material and the liquid can be between 10°C and 80°C. The pulp concentration can be between 25 g / L and 450 g / L. This pulp concentration refers to the ratio of the dry weight (g) of the magnetic material to the amount (L) of liquid brought into contact with the magnetic material. The lithium leaching time can be between 0.1 hours and 5 hours. If the lithium leaching time is too short, the lithium will not leach out sufficiently, and if the lithium leaching time is too long, a large amount of LiAl2(OH)7 hydrate, which is difficult to leach out in the subsequent alkaline leaching, will be produced. For this reason, it is preferable to leach the lithium for 0.5 to 3 hours.

[0071] When water, as an example of the liquid mentioned above, comes into contact with a magnetic material, the pH may rise to around 11-12 due to the leaching of lithium carbonate and other substances from the magnetic material. During lithium leaching, an acid such as sulfuric acid may be added as needed to adjust the pH. The amount of acid added can be adjusted so that the pH is 7-13, preferably 7-12, at the end of lithium leaching. This is because if the pH is below 7, cobalt and other substances may dissolve, and if it exceeds 12, there is a concern that aluminum and other substances may dissolve.

[0072] After lithium leaching is complete, solid-liquid separation is performed by filtration using known apparatus and methods such as filter presses and thickeners to obtain a lithium-containing solution mainly containing lithium ions and a residue containing aluminum and other metals such as cobalt and nickel.

[0073] Depending on the conditions (grade of the magnetic material, pulp concentration, leaching rate, etc.), lithium may not leach into the liquid to the desired solubility. In this case, the liquid (lithium-containing solution) after lithium leaching can be used again for further lithium leaching, and the liquid can be reused for lithium leaching. This can reduce costs and the amount of liquid used.

[0074] The lithium ion concentration of the lithium-containing solution is preferably 1.0 g / L to 2.5 g / L. The lithium leaching rate in the lithium leaching process may be, for example, 40% to 60%. The lithium leaching rate can be calculated by mass from the lithium content of the object (magnetic material in this case) before the lithium leaching process and the lithium content of the residue obtained in the lithium leaching process.

[0075] A lithium-containing solution can be concentrated to remove lithium ions by solvent extraction, for example, followed by carbonation to recover lithium carbonate. When performing carbonation, for example, the liquid temperature can be set to 20°C to 50°C and the pH to 10 to 13, and a carbonate such as sodium carbonate or carbon dioxide can be added to the lithium-containing solution, followed by stirring. This yields lithium carbonate. Further purification may be performed to improve the quality of the lithium carbonate. Specifically, the lithium carbonate is repulped and washed, carbon dioxide is blown into the solution to dissolve carbon dioxide, solid impurities are removed by solid-liquid separation, then deoxidation and concentration are performed, and high-quality lithium carbonate is separated and recovered by solid-liquid separation. In this way, lithium can be recovered.

[0076] (Alkali leaching process) In the alkaline leaching process, the residue after the lithium leaching process is immersed in an alkaline solution and stirred to bring it into contact with the alkaline solution, thereby leaching the aluminum from the residue into the alkaline solution. Because lithium has been leached in the lithium leaching process described above, the residue after the lithium leaching process contains a relatively small amount of lithium. Therefore, even if some lithium leaches out from the residue along with aluminum in the alkaline leaching process, the amount of lithium leached out is reduced. This helps to suppress lithium loss.

[0077] The alkaline solution used in the alkaline leaching process should have a pH of, for example, 13.0 or higher, before contact with the residue. - The concentration can be 8 mol / L or less. It is preferable to maintain the pH of the alkaline solution after contact with the residue at 12.0 or higher, and more preferably at 13.0 or higher. The OH of the alkaline solution after contact with the residue... - The concentration may be 8 mol / L or less. By maintaining the pH within the above range when leaching aluminum, the solubility of aluminum is high, allowing leaching to occur in a pH range where aluminum dissolves sufficiently, and preventing deterioration of filterability due to high alkalinity. From this perspective, the OH of the alkaline solution after contact with the residue - The concentration is preferably 5 ml / L or less. - By lowering the concentration to a certain extent, components such as sodium derived from the alkaline solution can be easily removed during washing after solid-liquid separation, and there is also the advantage that the increase in acid consumption in the subsequent acid leaching process due to these components is suppressed. As the alkaline solution, for example, sodium hydroxide solution or potassium hydroxide solution can be used. The above pH refers to the value measured at room temperature (typically 20°C), and if the temperature of the alkaline solution is higher than that, the pH should be the value when it has cooled down to room temperature.

[0078] In the alkaline leaching process, the temperature of the alkaline solution used to leach aluminum from the residue is preferably maintained within the range of 10°C to 80°C, and more preferably, within the range of 10°C to 50°C. If the temperature is too high, the reactivity will increase, potentially leading to rapid hydrogen generation or an uncontrollable rapid rise in temperature. If the temperature is too low, the reactivity will decrease, potentially prolonging the alkaline separation process. The pulp concentration can be, for example, 20 g / L to 500 g / L. This pulp concentration refers to the ratio of the dry weight (g) of the residue to the amount (L) of alkaline solution that comes into contact with the residue. The leaching time for aluminum may be, for example, 0.5 hours to 3.0 hours.

[0079] Depending on the conditions (residue quality, pulp concentration, leaching rate, etc.), aluminum may not leach to the desired solubility in the alkaline solution. In this case, the alkaline solution (aluminum-containing solution) used after alkaline leaching may be used again for alkaline leaching, and the alkaline solution may be reused for alkaline leaching. This can reduce costs and liquid volume.

[0080] After the leaching of aluminum is complete, solid-liquid separation is performed to obtain an aluminum-containing solution containing aluminum ions and a residue containing cobalt, nickel, etc. The aluminum ion concentration in the aluminum-containing solution may be, for example, 2 g / L to 60 g / L, or 2 g / L to 40 g / L. For example, the lithium content of the residue obtained in the alkaline leaching process is 0.5 mass% to 8 mass%, the cobalt content is 1 mass% to 30 mass%, the nickel content is 1 mass% to 40 mass%, the manganese content is 1 mass% to 40 mass%, the aluminum content is 0.5 mass% to 40 mass%, and the copper content is 1 mass% to 20 mass%.

[0081] Furthermore, aluminum may be present in the magnetic deposit before the lithium leaching process in the form of Al (metal) or trace amounts of LiAlO2. LiAlO2 is thought to be generated during the heat treatment mentioned earlier. When the lithium leaching process is performed on this magnetic deposit, the residue after the lithium leaching process may contain Al (metal), trace amounts of LiAlO2, hydrated LiAl2(OH)7, etc. In the alkali leaching process, the hydrated LiAl2(OH)7 often does not dissolve. For this reason, a small amount of aluminum may remain in the residue after the alkali leaching process.

[0082] If the residue obtained in the alkali leaching process is used in place of the magnetic material obtained in the eddy current separation process described above, along with the aforementioned small-diameter sieved material and unsieved material, as battery powder and subjected to further wet processing, the recovery rate of cobalt and / or nickel can be improved.

[0083] (Processing of materials using a medium-diameter sieve) Since the medium-diameter sieved material described above may contain impurity metals such as aluminum and copper, it is preferable to separate non-magnetic conductive materials from the medium-diameter sieved material by eddy current separation and extract magnetic materials containing at least one of cobalt and nickel as magnetically attached materials.

[0084] The eddy current separation process for medium-diameter sieved material can be carried out in much the same manner as the eddy current separation process for sieved material obtained from large-diameter sieved material, by adjusting the conditions appropriately so that cobalt and nickel in the medium-diameter sieved material migrate to the magnetic deposits. The resulting magnetic deposits can be used as battery powder for wet processing, etc., along with the small-diameter sieved material mentioned above. However, since the magnetic deposits may contain some aluminum, it is preferable to perform lithium leaching and alkali leaching processes on the magnetic deposits obtained from the eddy current separation process for medium-diameter sieved material, similar to the magnetic deposits obtained from the sieved material obtained from large-diameter sieved material.

[0085] In the lithium leaching process for magnetic deposits (magnetic deposits derived from medium-diameter sieves) obtained in the eddy current separation process for medium-diameter sieves, the magnetic deposits are brought into contact with a liquid to leach lithium from the magnetic deposits into the liquid. The liquid used has a pH of 7 to 13 after contact with the magnetic deposits. The lithium leaching process for magnetic deposits derived from medium-diameter sieves can be carried out in much the same manner as the lithium leaching process for magnetic deposits (magnetic deposits derived from large-diameter sieves) obtained in the eddy current separation process for sieved material obtained from large-diameter sieves, as described above. The resulting residue can be subjected to an alkali leaching process, and lithium can be recovered from the liquid (lithium-containing solution) after lithium leaching.

[0086] In the alkali leaching process for the residue obtained from the magnetic deposits derived from medium-diameter sieves via the lithium leaching process (residue derived from medium-diameter sieves), the residue derived from medium-diameter sieves is immersed in an alkaline solution and stirred, bringing it into contact with the alkaline solution, and the aluminum in the residue is leached into the alkaline solution. The alkali leaching process for the residue derived from medium-diameter sieves can be carried out in much the same manner as the alkali leaching process for the residue obtained from the magnetic deposits derived from large-diameter sieves via the lithium leaching process (residue derived from large-diameter sieves) described above.

[0087] (Wet processing) To recover metals from battery powder, it is preferable to perform an acid leaching step, as shown in Figure 2, in which the battery powder is leached with acid to obtain a metal-containing solution containing various metal ions, and a metal separation step, in which each metal ion is separated from the metal-containing solution.

[0088] Battery powder refers to powder obtained by treating lithium-ion battery waste in some way to separate and concentrate the positive electrode material components. Battery powder can be obtained as a powder in which the positive electrode material components are concentrated by treating lithium-ion battery waste with processes such as heat treatment, crushing, and sieving. In this embodiment, the residue obtained after the alkali leaching process described above can also be treated as battery powder.

[0089] In the acid leaching process, the battery powder is added to an acidic leaching solution of sulfuric acid, nitric acid, hydrochloric acid, or other inorganic acid to leach the metals in the residue. This yields a metal-containing solution in which various metals are dissolved.

[0090] The acid leaching process 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, based on silver / silver chloride potential) may be 0 mV or less.

[0091] 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 filter presses and thickeners. Much of the copper in the battery powder can sometimes be contained within the leaching residue. This solid-liquid separation is optional, and neutralization in the metal separation process may be performed directly after acid leaching without solid-liquid separation.

[0092] The metal-containing solution obtained in the acid leaching process 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, and typically contains cobalt ions and / or nickel ions.

[0093] The metal-containing solution obtained in the acid leaching process may have the following concentrations: cobalt ion concentration of 10 g / L to 50 g / L, nickel ion concentration of 10 g / L to 50 g / L, manganese ion concentration of 0 g / L to 50 g / L, aluminum ion concentration of 1.0 g / L to 20 g / L, iron ion concentration of 0.1 g / L to 5.0 g / L, copper ion concentration of 0.005 g / L to 0.2 g / L, and fluoride ion concentration of 0.01 g / L to 20 g / L.

[0094] In the metal separation process, metals such as cobalt and nickel can be separated from a metal-containing solution using various known methods, and the desired metals can be recovered. Specifically, the metal-containing solution can be neutralized and / or extracted using solvents to separate and recover each metal in the solution. [Examples]

[0095] Next, we experimentally implemented the metal recovery method described above and confirmed its effectiveness, which will be explained below. However, this explanation is merely illustrative and not intended to be the sole limiting factor.

[0096] (Example 1) Lithium-ion battery waste was subjected to heat treatment, crushing, and sieving, separating it into small-diameter, medium-diameter, and large-diameter sieved materials. The particle size of the small-diameter sieved material was less than 0.25 mm, the particle size of the medium-diameter sieved material was between 0.25 mm and less than 1.0 mm, and the particle size of the large-diameter sieved material was 1.0 mm or larger.

[0097] Large-diameter sieved material was further subjected to magnetic separation, re-crushing (shear crushing), and re-sieving in sequence. The particle size of the re-sieved material was 0.25 mm or larger, and the particle size of the unsieved material was less than 0.25 mm. Furthermore, the grade (ratio of the mass of each metal to the mass of the re-sieved or unsieved material (mass%)) and distribution rate (mass%) of the main metals in the re-sieved and unsieved materials are shown in Tables 1 and 2. Table 1 shows the grade and distribution rate of the re-sieved material, and Table 2 shows the grade and distribution rate of the unsieved material. The distribution rate is the percentage of each metal distributed to the target material (referred to here as the re-sieved or unsieved material) when the grade of each metal contained in the heat-treated lithium-ion battery waste is set to 100% on a mass basis (the distribution rates in Tables 3 and later are similar).

[0098] [Table 1]

[0099] [Table 2]

[0100] Eddy current separation was performed on the re-sieved material using an eddy current separator. The surface magnetic flux density during eddy current separation was 2500 gauss, the belt speed was 90 m / s, and the magnet rotation speed was 2500 rpm. Tables 3 and 4 show the grade (ratio of the mass of each metal to the mass of the magnetic material or repulsive material (mass %)) and distribution rate (mass %) of the main metals obtained after eddy current separation, for the magnetic material and repulsive material (non-magnetic conductor). Table 3 shows the grade and distribution rate of the magnetic material, and Table 4 shows the grade and distribution rate of the repulsive material (non-magnetic conductor). In addition, Table 5 shows the ratio of the mass of the magnetic material and the repulsive material to the total mass of the magnetic material and repulsive material obtained after eddy current separation, for the main metals contained in the magnetic material and the repulsive material, respectively.

[0101] [Table 3]

[0102] [Table 4]

[0103] [Table 5]

[0104] As can be seen from Table 5, 99.7% by mass of copper and 55% by mass of aluminum were removed from the re-sieved material as repulsive material by eddy current separation. It was found that by incorporating the magnetic deposits obtained by eddy current separation of the re-sieved material into the battery powder, impurity metals could be effectively separated from the large-diameter sieved material obtained by sieving, and the recovery rate of cobalt and / or nickel could be improved.

[0105] On the other hand, since the aluminum content in the magnetic material obtained by eddy current separation was 69% by mass, further aluminum removal was performed after separating lithium, as described below.

[0106] Specifically, lithium leaching was performed on the magnetic material obtained by eddy current separation using a pulp concentration of 100 g / L and a liquid temperature of room temperature (20°C) for 1 hour. Distilled water with a pH of 5.8 was used for lithium leaching. The pH at the end of leaching was 11.8. All cobalt and nickel migrated to the residue and were not leached. Table 6 shows the grade (ratio of the mass of each metal to the mass of the dry residue (mass%)) and distribution rate (mass%) of the main metals in the residue after lithium leaching. Table 7 shows the distribution rate (mass%) of distilled water (lithium-containing solution) after lithium leaching. The lithium leaching rate in the lithium leaching process was 50%.

[0107] [Table 6]

[0108] [Table 7]

[0109] Subsequently, the residue after lithium leaching was immersed in an alkaline solution to leach aluminum using alkali. Here, a 50 g / L sodium hydroxide solution was used as the alkaline solution, with a pulp concentration of 50 g / L, a solution temperature of room temperature (20°C), and a leaching time of 2 hours. Table 8 shows the grade (ratio of the mass of each metal to the mass of the dry residue (mass%)) and distribution rate (mass%) of the main metals in the residue after aluminum leaching. Table 9 shows the distribution rate (mass%) of the alkaline solution (aluminum-containing solution) after aluminum leaching.

[0110] [Table 8]

[0111] [Table 9]

[0112] As can be seen from Table 8, the aluminum content in the magnetic deposits obtained by eddy current separation was 69% by mass (distribution rate 11% by mass), whereas in the residue after aluminum leaching, the aluminum content could be reduced to 28% by mass (distribution rate 3.8% by mass), demonstrating that a large amount of aluminum could be removed from the magnetic deposits. It was found that by incorporating the residue after aluminum leaching into the battery powder instead of the magnetic deposits obtained by eddy current separation, impurity metals could be more effectively separated from the large-diameter sieved material obtained by sieving, and the recovery rate of cobalt and / or nickel could be improved.

[0113] The distribution ratio (mass %) of each major metal was determined for the total of the magnetic material obtained by eddy current separation of the small-diameter sieved material and the medium-diameter sieved material using the same method as the re-sieved upper sieved material, the re-sieved lower sieved material, the residue (dried material) after aluminum leaching, and the lithium-containing solution. The results are shown in Table 10.

[0114] [Table 10]

[0115] Table 10 shows that cobalt and nickel can be recovered with very high recovery rates.

[0116] (Comparative Example 1) The grade (mass%) and distribution rate (mass%) of each major metal were determined for the total of the small-diameter sieved material obtained in Example 1, the magnetic material obtained by eddy current sorting of the medium-diameter sieved material using the same method as the re-sieved upper sieved material, and the re-sieved lower sieved material. The results are shown in Table 11. These results do not include the re-sieved upper sieved material.

[0117] [Table 11]

[0118] As shown in Table 11, the distribution ratio of cobalt and nickel is 95% by mass. To improve the recovery rate, it is desirable to further recover cobalt and / or nickel from the large-diameter sieved material (specifically, the material on the sieved surface after re-sieving).

[0119] (Comparative Example 2) Lithium-ion battery waste was treated in the same manner as in Example 1, and the re-sieved sieved material shown in Table 1 was prepared. Lithium leaching and aluminum leaching were performed on this re-sieved sieved material without eddy current separation. In Comparative Example 2, lithium leaching and aluminum leaching were performed in the same manner as in Example 1, except that the target of lithium leaching was changed to the re-sieved sieved material. The grade (ratio of the mass of each metal to the mass of the dry residue (mass%)) and distribution rate (mass%) of the main metals in the residue after lithium leaching and the residue after aluminum leaching are shown in Tables 12 and 14. Table 12 shows the grade and distribution rate of the residue after lithium leaching, and Table 14 shows the grade and distribution rate of the residue after aluminum leaching. In addition, the distribution rate (mass%) of the main metals in distilled water (lithium-containing solution) after lithium leaching and alkaline solution (aluminum-containing solution) after aluminum leaching are shown in Tables 13 and 15. Table 13 shows the distribution ratio of distilled water after lithium leaching, and Table 15 shows the distribution ratio of alkaline solution after aluminum leaching.

[0120] [Table 12]

[0121] [Table 13]

[0122] [Table 14]

[0123] [Table 15]

[0124] The distribution ratio (mass %) of each major metal was determined for the total of the magnetic material obtained by eddy current separation of small-diameter and medium-diameter sieved materials, the unsieved material after re-sieving, the residue after aluminum leaching, and the lithium-containing solution. The results are shown in Table 16.

[0125] [Table 16]

[0126] Tables 12, 14, and 16 show that when attempting to recover cobalt and / or nickel from the re-sieved material without eddy current separation, the recovery rate of impurity metals such as copper and aluminum also increases. In particular, the final copper distribution rate in Comparative Example 2 shown in Table 16 is significantly higher than the final copper distribution rate in Example 1 shown in Table 10.

[0127] (Potential contribution to the SDGs) According to the embodiment described above, impurity metals can be effectively separated from the large-diameter sieved material obtained by sieving, which may improve the recovery rate of valuable metals from lithium-ion battery waste. For this reason, this embodiment may contribute to Goal 9 "Build resilient infrastructure, promote inclusive and sustainable industrialization and foster innovation" and Goal 12 "Ensure sustainable consumption and production patterns" of the United Nations-led Sustainable Development Goals (SDGs) by promoting waste reuse and improving resource utilization efficiency.

Claims

1. A method for recovering a metal containing at least one of cobalt and nickel from lithium-ion battery waste, A heat treatment step in which heat is applied to the lithium-ion battery waste, A crushing step to crush the lithium-ion battery waste after the heat treatment step to obtain crushed material, A sieving step in which the crushed material is separated by sieving into at least small-diameter sieved material with a relatively small particle size, large-diameter sieved material with a relatively large particle size, and medium-diameter sieved material with a particle size intermediate between the small-diameter sieved material and the large-diameter sieved material. A magnetic separation process in which magnetic separation is performed on the large-diameter sieved material, and the magnetically attached material is extracted from the large-diameter sieved material. A re-crushing step to crush the magnetic material and obtain a re-crushed material, The re-sieving process involves separating the re-crushed material into the material below the sieve and the material above the sieve containing copper by sieving, and Eddy current separation process: Separating non-magnetic conductive materials containing copper from the sieved material by eddy current separation, and extracting magnetic materials containing at least one of cobalt and nickel as magnetic materials. A metal recovery method, including

2. The metal recovery method according to claim 1, further comprising a lithium leaching step in which the magnetic material obtained in the eddy current separation step is brought into contact with a liquid to leach lithium from the magnetic material into the liquid, the pH of the liquid at the end of the lithium leaching is set to 7 to 13, and a residue and a lithium-containing solution are obtained.

3. The metal recovery method according to claim 2, further comprising an alkaline leaching step in which the residue from the lithium leaching step is brought into contact with an alkaline solution to leach the aluminum in the residue into the alkaline solution, thereby obtaining a residue and an aluminum-containing solution.

4. The metal recovery method according to any one of claims 1 to 3, wherein the particle size of the sieved material in the re-sieving step is 0.25 mm or larger.

5. The metal recovery method according to any one of claims 1 to 3, wherein the particle size range of the sieved material in the re-sieving step overlaps with the particle size range of the medium-diameter sieved material.

6. The metal recovery method according to any one of claims 1 to 3, wherein the copper content of the sieved material obtained in the re-sieving step is 5% by mass to 70% by mass.

7. The metal recovery method according to any one of claims 1 to 3, wherein the non-magnetic conductive material in the eddy current separation step further includes aluminum.

8. The metal recovery method according to claim 7, wherein the magnetic material obtained in the magnetic separation step includes crushed pieces in which copper foil and aluminum foil are overlapping.

9. The metal recovery method according to claim 7, wherein the sieved material obtained in the re-sieving step contains aluminum, and the aluminum content of the sieved material is 5% by mass to 60% by mass.

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