Process for the recovery of valuable metals

Abstract

The present invention provides a method capable of easily separating Li, Ni, Co, and Cu from an object containing a water-soluble Li compound, Ni, Co, and Cu, and an immersion agent suitable for reuse. The valuable metal recovery method of the present disclosure includes: a Li, Cu leaching step in which Li and Cu are leached into a first aqueous phase from an object containing a water-soluble Li compound, Ni, Co, and Cu by ammonia leaching; a separation step in which Li is separated from Cu by evaporating ammonia from the first aqueous phase; and a Ni, Co leaching step in which Ni and Co are leached into a second aqueous phase from a solid residue obtained in the Li, Cu leaching step by ammonia leaching.

Description

Technical Field

[0001] This disclosure relates to methods for recycling valuable metals. Background Technology

[0002] Lithium-ion rechargeable batteries are widely used in various fields, such as vehicle power supplies and portable power sources. In recent years, from the perspective of the SDGs (Safety, Government, and Goods Administration), the recycling of materials from used lithium-ion rechargeable batteries is being promoted. Various metal elements are used in lithium-ion rechargeable batteries, and technologies for separating these metal elements from used batteries are being developed for material recycling.

[0003] Representative examples of positive electrode active materials for lithium-ion secondary batteries used in automotive applications include lithium nickel cobalt manganese composite oxide (NCM) and lithium nickel cobalt aluminum composite oxide (NCA), which contain Li, Ni, and Co. Therefore, waste from lithium-ion secondary batteries using these positive electrode active materials contains Li, Ni, and Co. On the other hand, the negative electrode current collector of lithium-ion secondary batteries typically uses copper foil. Therefore, waste from lithium-ion secondary batteries typically contains Cu.

[0004] Regarding techniques for separating metal elements from waste lithium-ion secondary batteries, for example, Patent Document 1 describes a method for separating Li, Ni, Co, and Cu from waste lithium-ion secondary batteries using the following steps: Pre-treatment of the waste lithium-ion secondary batteries yields battery powder containing Li, Ni, Co, and Cu, and aluminum slag. The battery powder is then calcined. Water is added to the calcined battery powder to prepare an aqueous slurry, and Li is leached into the aqueous phase using a metal chloride. After solid-liquid separation, the solid residue is acid-leached to leach Ni, Co, and Cu into the aqueous phase. Aluminum slag is added to the aqueous phase to perform a copper reduction reaction, thereby separating copper. Finally, the pH of the aqueous phase is adjusted to remove the aluminum slag.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: International Publication No. 2023 / 024599 Summary of the Invention

[0008] However, the method described in Patent Document 1 involves acid leaching, which presents the problem of acid contamination during reuse. In other words, the acid is detrimental to the reuse of the leaching agent. Furthermore, the process of adding aluminum dross, reducing copper, and removing aluminum dross to separate copper is complex.

[0009] Therefore, the object of this disclosure is to provide a method for easily separating Li, Ni, Co and Cu from an object containing water-soluble Li compounds, Ni, Co and Cu, and for reusing the leaching agent.

[0010] The method for recovering valuable metals disclosed herein includes: a Li and Cu leaching step, in which Li and Cu are leached from an object containing a water-soluble Li compound, Ni, Co, and Cu into a first aqueous phase by ammonia leaching; a separation step, in which Li and Cu are separated by evaporating ammonia from the first aqueous phase; and a Ni and Co leaching step, in which Ni and Co are leached from the solid residue obtained in the above Li and Cu leaching step into a second aqueous phase by ammonia leaching.

[0011] Based on this configuration, a method can be provided that can easily separate Li, Ni, Co and Cu from an object containing water-soluble Li compounds, Ni, Co and Cu, and the leaching agent is suitable for reuse. Attached Figure Description

[0012] Figure 1 This is a flowchart illustrating the steps of the method for recycling valuable metals disclosed herein.

[0013] Figure 2 This is a schematic diagram illustrating the movement of valuable metals in the method for recovering valuable metals disclosed herein.

[0014] Figure 3 This is a longitudinal cross-sectional view schematically representing the internal structure of an example of a lithium-ion secondary battery.

[0015] Figure 4 It means Figure 3 The diagram shows an exploded view of the electrode structure of a lithium-ion secondary battery. Detailed Implementation

[0016] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. It should be noted that matters not mentioned in this specification but necessary for the implementation of this disclosure can be grasped by those skilled in the art based on existing technology in the field. This disclosure can be implemented based on the content disclosed in this specification and common technical knowledge in the field. Furthermore, in the following drawings, components and parts that perform the same function are labeled with the same symbols. Additionally, the dimensional relationships (length, width, thickness, etc.) in the drawings do not reflect actual dimensional relationships. It should be noted that the numerical range represented as "A~B" in this specification includes both A and B.

[0017] It should be noted that in this specification, "secondary battery" refers to an energy storage device capable of repeated charging and discharging. Furthermore, in this specification, "lithium-ion secondary battery" refers to a secondary battery that utilizes lithium ions as charge carriers and achieves charging and discharging through the movement of lithium ions between the positive and negative electrodes.

[0018] Figure 1 This is a flowchart illustrating the steps of the method for recycling valuable metals disclosed herein. Figure 2 This is a schematic diagram illustrating the movement of valuable metals in the valuable metal recovery method of this disclosure. The valuable metal recovery method of this disclosure includes: a Li and Cu leaching step S101, in which Li and Cu are leached from an object containing a water-soluble Li compound, Ni, Co, and Cu into a first aqueous phase by ammonia leaching; a separation step S102, in which Li and Cu are separated by evaporating ammonia from the first aqueous phase; and a Ni and Co leaching step S103, in which Ni and Co are leached from the solid residue obtained in the Li and Cu leaching step into a second aqueous phase by ammonia leaching.

[0019] The method for recovering valuable metals disclosed herein is applied to materials containing water-soluble Li compounds, Ni, Co, and Cu. The type of material is not particularly limited as long as it contains water-soluble Li compounds, Ni, Co, and Cu. Typically, the material is roasted black powder from lithium-ion secondary batteries. Therefore, lithium-ion secondary batteries will be described in detail first.

[0020] <Lithium-ion secondary batteries>

[0021] Illustrate the general structure of a lithium-ion secondary battery with an example. An example of the general structure of a lithium-ion secondary battery is shown below. Figure 3 and Figure 4 . Figure 3 This is a longitudinal cross-sectional view schematically representing the internal structure of an example of a lithium-ion secondary battery. Figure 4 It is a schematic representation Figure 3 The diagram shows an exploded view of the electrode body of a lithium-ion secondary battery. It should be noted that the following description of the lithium-ion secondary battery is for illustrative purposes only and is not intended to limit the methods for recovering valuable metals disclosed herein in any way.

[0022] like Figure 3 As shown, the lithium-ion secondary battery 100 is a sealed battery in which a flat electrode 20 and a non-aqueous electrolyte (not shown) are housed inside the battery casing 30. Figure 3 As shown, the battery casing 30 consists of an outer body 32 that houses the electrode body 20 and a cover 34 that seals the opening of the outer body 32. The outer body 32 and the cover 34 are sealed by welding, such as laser welding. Materials used for the battery casing 30 include, for example, aluminum, aluminum alloy, and resin.

[0023] In the example shown, the battery casing 30 is square. However, the shape of the battery casing 30 is not limited to this; for example, it can be cylindrical. Alternatively, the battery casing 30 can be a laminated casing having a gas barrier layer, such as an aluminum layer, and a sealing layer containing a thermoplastic resin.

[0024] The battery casing 30 includes a positive terminal 42 and a negative terminal 44 for external connection. Additionally, the battery casing 30 is equipped with a safety valve 36 configured to release internal pressure when the internal pressure of the battery casing 30 rises above a predetermined level. The battery casing 30 also has an injection port (not shown) for injecting a non-aqueous electrolyte. The positive terminal 42 is electrically connected to the positive current collector 42a. The negative terminal 44 is electrically connected to the negative current collector 44a.

[0025] like Figure 3 and Figure 4 As shown, the electrode body 20 has a strip-shaped positive electrode 50 and a strip-shaped negative electrode 60, which are formed by overlapping two strip-shaped insulating sheets 70 and wound along their long sides. Therefore, in this embodiment, the electrode body 20 is a wound electrode body. However, the electrode body 20 is not limited to this, and may also be a stacked electrode body in which multiple positive electrodes and multiple negative electrodes are alternately stacked by insulating sheets.

[0026] like Figure 3 As shown, in the positive electrode 50, a positive active material layer 54 is formed on one or both sides (in this case, both sides) of the positive current collector 52 along the long side direction. The positive electrode 50 has a portion where the positive active material layer 54 is not formed and the positive current collector 52 is exposed, namely, the non-formed portion 52a of the positive active material layer. A positive current collector plate 42a is bonded to the non-formed portion 52a of the positive active material layer.

[0027] Examples of the positive current collector 52 constituting the positive electrode sheet 50 include aluminum foil. The positive electrode active material layer 54 contains a positive electrode active material. The positive electrode active material is typically a lithium transition metal composite oxide containing Ni and Co. Examples of such positive electrode active materials include lithium nickel cobalt manganese composite oxides and lithium nickel cobalt aluminum composite oxides. The positive electrode active material layer 54 may contain conductive materials (e.g., carbon black, carbon nanotubes, etc.), binders (e.g., polyvinylidene fluoride, etc.), etc.

[0028] The content of the positive electrode active material in the positive electrode active material layer 54 is preferably 70% by mass or more, more preferably 85% by mass to 99% by mass. The content of the conductive material in the positive electrode active material layer 54 is preferably 0.1% by mass to 20% by mass, more preferably 0.3% by mass to 15% by mass. The content of the binder in the positive electrode active material layer 54 is preferably 0.4% by mass to 15% by mass, more preferably 0.5% by mass to 10% by mass.

[0029] In the negative electrode sheet 60, a negative electrode active material layer 64 is formed on one or both sides (in this case, both sides) of the negative electrode current collector 62 along the long side direction. The negative electrode sheet 60 has a portion where the negative electrode active material layer 64 is not formed and the negative electrode current collector 62 is exposed, namely, the non-formed portion 62a of the negative electrode active material layer. A negative electrode current collector plate 44a is bonded to the non-formed portion 62a of the negative electrode active material layer.

[0030] The negative electrode current collector 62 constituting the negative electrode sheet 60 is typically copper foil. The negative electrode active material layer 64 contains a negative electrode active material. Examples of negative electrode active materials include carbon-based negative electrode active materials (e.g., graphite, hard carbon, soft carbon, etc.) and silicon-based negative electrode active materials (e.g., silicon, silicon oxide, etc.). The negative electrode active material layer 64 may contain binders (e.g., styrene-butadiene rubber (SBR), thickeners (e.g., carboxymethyl cellulose (CMC), etc.).

[0031] The graphite content in the negative electrode active material layer 64 is preferably 90% by mass or more, more preferably 95% by mass to 99% by mass. The binder content in the negative electrode active material layer 64 is preferably 0.1% by mass to 8% by mass, more preferably 0.5% by mass to 3% by mass. The thickener content in the negative electrode active material layer 64 is preferably 0.3% by mass to 3% by mass, more preferably 0.5% by mass to 2% by mass.

[0032] Examples of spacer 70 include porous resin sheets such as polyethylene and polypropylene. The porous sheet can be a single-layer or multi-layer structure. A heat-resistant layer (HRL) can be provided on the surface of spacer 70.

[0033] Non-aqueous electrolytes typically contain a non-aqueous solvent and a supporting salt (in other words, an electrolyte salt). Examples of non-aqueous solvents include carbonates (e.g., ethylene carbonate, ethyl methyl carbonate, dimethyl carbonate, etc.), esters, ethers, etc. Examples of supporting salts include lithium salts such as LiPF6. The concentration of the supporting salt is not particularly limited, but is preferably 0.7 mol / L to 1.3 mol / L. The non-aqueous electrolyte may contain various additives such as gas generators and film-forming agents. It should be noted that in this embodiment, a non-aqueous electrolyte is used as the electrolyte, but the electrolyte can be a solid electrolyte.

[0034] The lithium-ion secondary battery 100 is used, for example, as a power source for automotive applications (i.e., as a drive power source for vehicles such as battery electric vehicles (BEVs), hybrid electric vehicles (HEVs), and plug-in hybrid electric vehicles (PHEVs)) and electronic devices.

[0035] As described above, Li, Ni, and Co are typically used as constituent metal elements of the positive electrode active material in lithium-ion secondary batteries. The positive electrode active material may further include Mn and Al. Al is typically used in the positive electrode current collector. Cu is typically used in the negative electrode current collector. Additionally, Li is used in the non-aqueous electrolyte in lithium-ion secondary batteries. Furthermore, Al can be used in the battery casing. The following describes in detail each step of the method for recovering valuable metals according to this disclosure.

[0036]

[0037] In the Li and Cu leaching process S101, the object containing water-soluble Li compounds, Ni, Co and Cu is subjected to ammonia leaching of Li and Cu.

[0038] There are no particular limitations on the types of water-soluble Li compounds contained in the object, as long as they are water-soluble Li compounds. Examples of water-soluble Li compounds include Li₂CO₃, LiCl, and LiOH.

[0039] As described above, the object containing water-soluble Li compounds, Ni, Co, and Cu is typically roasted black powder from the waste of lithium-ion secondary batteries. It should be noted that in this specification, "waste of lithium-ion secondary batteries" includes not only used lithium-ion secondary batteries, but also components of used lithium-ion secondary batteries (e.g., electrodes), defective lithium-ion secondary batteries, and components of defective lithium-ion secondary batteries (e.g., electrodes).

[0040] Lithium-ion secondary batteries contain Li, Ni, and Co as positive electrode active materials in the form of composite oxides. Additionally, Li is contained as an electrolyte salt. Cu is contained as a metal as a negative electrode current collector. In the calcined black powder from lithium-ion secondary battery waste, Li is mainly converted into water-soluble Li compounds (e.g., Li₂CO₃) during the calcination process due to reactions such as carbon oxidation. Therefore, the calcined black powder from lithium-ion secondary battery waste contains water-soluble Li compounds, Ni, Co, and Cu.

[0041] Furthermore, the oxide forms of Ni and Co contained in lithium-ion secondary batteries can be reduced by calcination. Additionally, the Cu contained in lithium-ion secondary batteries can be oxidized by calcination. Therefore, the calcined black powder from lithium-ion secondary battery waste can contain Ni, Co, and Cu in either metallic or oxide forms. The leaching rates of metallic Ni, Co, and Cu are greater than those of oxide Ni, Co, and Cu; therefore, the calcined black powder from lithium-ion secondary battery waste preferably contains Ni, Co, and Cu in metallic forms.

[0042] Specifically, the calcined black powder can be obtained by, for example, by crushing lithium-ion secondary battery waste according to known methods, sieving as needed, separating specific metal types as needed, and calcining at 650°C to 1500°C (preferably 750°C to 1000°C) for 1 hour to 24 hours (preferably 4 hours to 12 hours). Here, by using an atmosphere with an oxygen concentration of 5% by volume or less (preferably 1% by volume or less) (especially an inactive gas atmosphere such as argon or nitrogen) as the calcination atmosphere, the calcined black powder of lithium-ion secondary battery waste can contain Li in the form of water-soluble Li compounds and Ni, Co, and Cu in the form of metals. On the other hand, if an atmosphere with an oxygen concentration higher than that of the atmosphere is selected as the calcination atmosphere, Li, Ni, Co, and Cu can be contained in the calcined black powder in the form of oxides. Therefore, the object is particularly preferably calcined black powder obtained by calcining lithium-ion secondary battery waste in an atmosphere with a preferred oxygen concentration of 5% by volume or less (especially an inactive gas atmosphere such as argon or nitrogen).

[0043] The roasting atmosphere, besides oxygen, typically includes inert gases such as argon and nitrogen. However, the roasting atmosphere can include gases other than oxygen and inert gases. Here, the type of water-soluble Li compound can be changed depending on the type of gas included in the roasting atmosphere. Specifically, when the roasting atmosphere is an inert gas atmosphere such as argon or nitrogen, the roasted black powder contains Li₂CO₃ as a water-soluble Li compound. When the roasting atmosphere contains chlorine (for example, in the case of a mixed gas atmosphere of chlorine and inert gases), the roasted black powder contains LiCl. In this case, to prevent metals other than Li from forming chlorides, the concentration of chlorine in the atmosphere is preferably 5% by volume or less. When the roasting atmosphere contains hydrogen (for example, in the case of a mixed gas atmosphere of hydrogen and inert gases), the roasted black powder contains LiOH. When the roasting atmosphere contains hydrogen, metal elements such as Ni and Co maintain their metallic state, so their concentration is not particularly limited.

[0044] Therefore, the method for recovering valuable metals disclosed herein may, as an optional step, further include a step of roasting the waste from lithium-ion secondary batteries to obtain an object containing water-soluble Li compounds, Ni, Co, and Cu (i.e., roasted black powder) (hereinafter also referred to as the "roasting step"). This roasting step is performed before the Li and Cu leaching step S101. The roasting conditions for this roasting step are as described above.

[0045] It should be noted that the above-mentioned roasting process can remove liquid components (such as electrolyte) from the waste of lithium-ion secondary batteries and carbonize resin components (such as adhesives, separators, etc.). In addition, roasting can stop the battery from functioning.

[0046] The object may further contain elements (especially metallic elements) other than water-soluble Li compounds, Ni, Co, and Cu. For example, the object may contain other transition metal elements, and in particular, may further contain Mn. For example, the object may further contain Al.

[0047] In the Li and Cu leaching process S101, the target material is leached with ammonia, so a first ammonia solution containing at least water and ammonia is used as the leaching agent.

[0048] The concentration of ammonia in the first ammonia solution is not particularly limited as long as it is sufficient to leach Li and Cu. From the viewpoint of suppressing the dissolution of metals other than Li and Cu, the concentration of ammonia in the first ammonia solution is preferably 0.01% by mass or more, more preferably 0.1% by mass or more. Furthermore, the upper limit of the ammonia concentration is preferably 5% by mass or less, more preferably 2% by mass or less. From the viewpoint of leaching capacity and ease of processing, the ammonia concentration is particularly preferably 0.1% to 2% by mass.

[0049] The first ammonia solution may contain only water and ammonia. That is, the first ammonia solution can be ammonia water.

[0050] On the other hand, the first ammonia solution may further contain other components. For example, the first ammonia solution may further contain ammonium carbonate. The amount of ammonium carbonate in the first ammonia solution is preferably 0.5 to 1.5 times the amount of Cu contained in the target material, more preferably 0.8 to 1.2 times the amount of Cu contained in the target material, and even more preferably equal to the amount of Cu contained in the target material. On the other hand, ammonium carbonate promotes the leaching of Ni and Co. The amount of ammonium carbonate in the first ammonia solution is preferably 0.20 times or less the total amount of Ni and Co contained in the target material, more preferably 0.10 times or less, and even more preferably 0.05 times or less.

[0051] The first ammonia solution may contain only water, ammonia, and ammonium carbonate. The first ammonia solution may further contain components other than water, ammonia, and ammonium carbonate within a range that does not impair the effects of this disclosure (e.g., concentrations of less than 10%, 5%, or 1% by mass).

[0052] There is no particular limitation on the amount of ammonia solution used in the first ammonia solution; it can be the same as the amount used in known ammonia leaching methods. For example, the amount of the first ammonia solution used is enough to completely submerge the object.

[0053] Generally, the dissolution of Cu in ammonia solution is related to oxygen. This oxygen can be dissolved oxygen in the first ammonia solution or oxygen in the atmosphere. Therefore, the Li and Cu leaching process S101 can be carried out in the atmosphere, but from the viewpoint of high dissolution rate, it is preferable to supply oxygen to the first ammonia solution during leaching. The amount of oxygen supplied is preferably equal to or greater than the amount of the target oxidizing element (i.e., Cu) contained in the target material, and preferably more than 1.5 times the amount of oxygen supplied.

[0054] Oxygen can be supplied using known methods. For example, oxygen can be supplied by introducing an oxygen-containing gas (such as oxygen gas, atmosphere, etc.) into ammonia water through bubbling. In this case, the smaller the bubbles, the more effectively the dissolved oxygen content can be increased. Alternatively, oxygen can be supplied, for example, by sealing a container and pressurizing it while introducing oxygen into it.

[0055] The Li and Cu leaching process S101 can be performed as follows, for example. First, a container is prepared. The container can be a known container used in ammonia leaching. As needed, a heating mechanism such as a heater, a temperature measuring mechanism such as a thermometer and temperature sensor, a stirring mechanism such as stirring blades and a magnetic stirring rod are installed in the container. Additionally, as needed, a bubbling device is prepared. The bubbling device can be a known bubbling device used in leaching. The bubbling device can be installed in the container before or after the addition of the target material and the first ammonia solution.

[0056] Add the target substance and the first ammonia solution to the container. The order in which they are added is not particularly important; either can be added first, or they can be added simultaneously. If necessary, use a bubbling device to supply oxygen-containing gas into the first ammonia solution in the form of bubbles.

[0057] The Li and Cu leaching process S101 can be carried out at room temperature (i.e., 25±10°C) or under heating. The leaching temperature is preferably above 0°C and below 80°C. More preferably, it is 10°C to 50°C, and even more preferably, it is 15°C to 35°C.

[0058] The leaching time can be determined based on the leaching temperature. The lower the leaching temperature, the longer the leaching time is preferred. The leaching time is, for example, 0.5 hours to 48 hours, preferably 1 hour to 24 hours, and more preferably 1.5 hours to 12 hours.

[0059] Stirring is preferably performed during ammonia leaching. The stirring speed is not particularly limited, but is preferably 200 rpm or higher, more preferably 300 rpm or higher, and even more preferably 400 rpm or higher. The stirring speed can be 2000 rpm or lower, 1000 rpm or lower, or 800 rpm or lower.

[0060] Ammonia leaching can be completed by solid-liquid separation, such as filtration. Through this solid-liquid separation, such as... Figure 2 As shown, an aqueous phase containing Li and Cu (i.e., a first ammonia solution containing Li and Cu) and a solid residue containing Ni and Co can be obtained. The Li and Cu leaching process S101 can be performed as described above.

[0061] <Separation process S102>

[0062] Next, the separation process S102 will be described. It should be noted that the order in which the separation process S102 and the Ni / Co leaching process S103 are performed is not particularly limited, as long as they occur after the Li / Cu leaching process S101. The separation process S102 can be performed before the Ni / Co leaching process S103, or the Ni / Co leaching process S103 can be performed before the separation process S102. Alternatively, the separation process S102 and the Ni / Co leaching process S103 can be performed in parallel.

[0063] In separation step S102, ammonia is evaporated from the first aqueous phase. If ammonia is evaporated from the first aqueous phase, Cu precipitates as a copper compound. Therefore, Li and Cu can be separated into an aqueous phase containing Li and a solid phase containing Cu.

[0064] When only ammonia is evaporated from the first aqueous phase, the precipitated copper compound is copper oxide (CuO).

[0065] When ammonia is evaporated after adding a hydroxide (e.g., LiOH, NaOH, KOH, etc.) to the first aqueous phase, the precipitated copper compound is copper hydroxide (Cu(OH)₂). Here, it is advantageous that the Cu precipitation rate is higher when ammonia is evaporated after adding a hydroxide to the first aqueous phase. Lithium hydroxide (LiOH) is preferred as the hydroxide because it does not contain metallic elements that would become impurities.

[0066] In the separation step S102, it is preferable to recover the evaporated ammonia. Then, it is advantageous to reuse the recovered ammonia in at least one of the Li, Cu leaching step S101 and the Ni, Co leaching step S103 in a reagent cycle that does not generate waste.

[0067] Separation process S102 can be carried out according to known methods. Specifically, it can be carried out as follows: Prepare an open container (i.e., a container that is not sealed and is open to the atmosphere). This open container can be a known type of container. Install heating mechanisms such as heaters, temperature measuring mechanisms such as thermometers and temperature sensors, stirring mechanisms such as stirring blades and magnetic stirring rods, etc., into the open container.

[0068] In the case of ammonia recovery, an ammonia capture device is prepared. Known ammonia capture devices can be used. For example, an ammonia capture device includes an suction hood and an ammonia capture section. The suction hood is, for example, positioned above an open container. The ammonia capture section, for example, cools the attracted ammonia gas and recovers it as ammonia water. Alternatively, the ammonia capture section may contain an ammonia capture liquid (e.g., an aqueous solution of acid with a pH less than 7, particularly an aqueous solution of sulfuric acid with a pH less than 7), configured such that the gas attracted from the suction hood can pass through the ammonia capture liquid. The ammonia capture device may have an ammonia separation section and an ammonia recovery section. The ammonia separation section is configured to separate ammonia from the capture liquid by distillation, adsorption using an adsorbent material, membrane separation, etc. The ammonia recovery section is a tank or the like connected to the ammonia separation section via piping, configured to recover the ammonia separated in the ammonia separation section. It should be noted that the configuration of the ammonia capture device is not limited to the above.

[0069] The first aqueous phase obtained in the Li and Cu leaching step S101 is added to an open container. If copper hydroxide is generated using hydroxide, hydroxide is added to the first aqueous phase to dissolve it. Next, the first aqueous phase is heated. This allows ammonia to evaporate from the first aqueous phase. The heating temperature is not particularly limited as long as ammonia evaporates, but is preferably 50°C or higher, more preferably 70°C or higher, and even more preferably 90°C or higher. Alternatively, the heating temperature can be lower than the boiling point of water (i.e., 100°C).

[0070] The heating time can be appropriately determined based on the heating temperature. The longer the heating time, the shorter the heating duration can be. The heating time is, for example, 0.5 hours or more, preferably 1 hour or more, more preferably 2 hours or more, and even more preferably 3 hours or more. The heating time is preferably 24 hours or less, more preferably 12 hours or less, and even more preferably 8 hours or less.

[0071] Stirring can be performed while heating. The stirring speed is not particularly limited, but is preferably 200 rpm or higher, more preferably 400 rpm or higher, and even more preferably 600 rpm or higher. The stirring speed can be 2000 rpm or lower, 1000 rpm or lower, or 800 rpm or lower.

[0072] In the case of ammonia recovery, the ammonia evaporated by heating is recovered using an ammonia capture device. Specifically, for example, ammonia evaporated from the suction hood is drawn in, and the ammonia is captured using the capture liquid in the ammonia capture section.

[0073] like Figure 2 As shown, if ammonia is evaporated from the first aqueous phase, Cu precipitates as a copper compound, while Li remains in the first aqueous phase. Therefore, Cu and Li can be separated. Furthermore, by performing solid-liquid separation such as filtration, Li and Cu can be recovered separately.

[0074] The recovered Li can be used as a raw material for positive electrode active materials according to known methods, or for other uses. The recovered Cu can be used as a raw material for negative electrode current collectors according to known methods, or for other uses.

[0075] <Ni and Co leaching process S103>

[0076] The solid residue obtained in the Li and Cu leaching process S101 contains Ni and Co. In the Ni and Co leaching process S103, the solid residue obtained in the Li and Cu leaching process S101 is subjected to ammonia leaching, so that the Ni and Co contained in the solid residue are leached into the second aqueous phase.

[0077] In the Ni and Co leaching process S103, a second ammonia solution containing water, ammonia (NH3), and an inorganic ammonium salt as a pH adjuster is used as the leaching agent for ammonia leaching. Preferably, this inorganic ammonium salt is at least one selected from ammonium sulfate ((NH4)2SO4) and ammonium carbonate ((NH4)2CO3).

[0078] In the second ammonia solution, the concentration of ammonia is not particularly limited, but the higher the concentration, the higher the leaching capacity. Therefore, the concentration of ammonia in the second ammonia solution is, for example, 1% by mass or more, preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more. Furthermore, the upper limit of the ammonia concentration is the saturation concentration of ammonia in water, and therefore approximately 35% by mass. From the viewpoint of leaching capacity and ease of processing, the ammonia concentration is particularly preferably 15% to 25% by mass.

[0079] The inorganic ammonium salt used is a pH adjuster. Here, the pH of the second ammonia solution at 25°C is preferably 9 to 12, more preferably 10 to 11. Therefore, the amount of inorganic ammonium salt in the second ammonia solution is such that the pH of the second ammonia solution is, for example, 9 to 12, preferably 10 to 11. The concentration of the inorganic ammonium salt in the second ammonia solution is preferably 0.5 mol / L or more, more preferably 1 mol / L or more, and even more preferably 1.5 mol / L or more. On the other hand, the concentration of the inorganic ammonium salt in the second ammonia solution can be 3 mol / L or less or 2.5 mol / L or less.

[0080] The second ammonia solution may contain only water, ammonia, and inorganic ammonium salts. The second ammonia solution may further contain components other than water, ammonia, and inorganic ammonium salts to a extent that does not impair the effects of this disclosure (e.g., concentrations of less than 10%, 5%, or 1% by mass).

[0081] There is no particular limitation on the amount of ammonia solution used in the second ammonia solution; it can be the same as the amount used in known ammonia leaching methods. For example, the amount of ammonia solution used is enough to completely submerge the solid residue.

[0082] In the Ni and Co leaching process S103, it is advantageous to perform leaching while simultaneously supplying an oxygen-containing gas to the second ammonia solution. This improves the selectivity and leaching rate of Ni and Co.

[0083] The higher the oxygen concentration of the supplied gas, the higher the leaching rate and selectivity of Ni and Co. Therefore, the oxygen concentration of the supplied gas is preferably 21% by volume or more, more preferably 30% by volume or more, even more preferably 50% by volume or more, particularly preferably 90% by volume or more, and most preferably 99% by volume or more.

[0084] The oxygen concentration of the supplied gas can be adjusted using known methods. For example, oxygen can be mixed with an inert gas (such as nitrogen, argon, etc.) to achieve a predetermined oxygen concentration, thereby adjusting the oxygen concentration. Furthermore, when only oxygen is used as the supplied gas, i.e., when the supplied gas contains only oxygen, the oxygen concentration can be made 99% by volume or higher (especially 100% by volume). Additionally, since the oxygen concentration of the atmosphere is 21% by volume, the atmosphere can be used as the oxygen-containing gas.

[0085] The supply of oxygen-containing gas to the second ammonia solution can be carried out according to known methods. For example, it can be done by bubbling. Here, when only oxygen is supplied to the second ammonia solution by bubbling, the leaching rate and selectivity of Ni and Co become extremely high. In this case, the smaller the bubbles, the more effectively the dissolved oxygen content can be increased. Alternatively, the supply of oxygen-containing gas can be carried out, for example, by sealing the container and pressurizing it while supplying oxygen-containing gas to it.

[0086] The Ni and Co leaching process S103 can be performed as follows, for example. First, a container is prepared. The container can be a known container used in ammonia leaching. As needed, a heating mechanism such as a heater, a temperature measuring mechanism such as a thermometer and temperature sensor, and a stirring mechanism such as stirring blades and a magnetic stirring rod are installed in the container. Additionally, a bubbling device is prepared as needed. The bubbling device can be a known bubbling device used in leaching. The bubbling device can be installed in the container before or after the addition of the solid residue and the second ammonia solution.

[0087] Add the solid residue and the second ammonia solution to the container. There is no particular order in which they are added; either can be added first, or they can be added simultaneously. If necessary, use a bubbling device to supply oxygen-containing gas into the second ammonia solution in the form of bubbles.

[0088] The amount of oxygen-containing gas supplied can be appropriately determined based on the amount of solid residue and the second ammonia solution. Regarding the gas supply amount, the amount of oxygen supplied relative to potentially oxidizable elements (especially Ni and Co) contained in the solid residue is preferably at least equal in moles, more preferably at least twice in moles, and even more preferably at least three times in moles. The amount of oxygen supplied relative to potentially oxidizable elements contained in the solid residue can be less than 100 times in moles.

[0089] The Ni and Co leaching process S103 can be carried out at room temperature (i.e., 25±10°C) or under heating. The leaching temperature is preferably above 0°C and below 80°C. More preferably, it is 10°C to 50°C, and even more preferably, it is 15°C to 35°C.

[0090] The leaching time can be appropriately determined based on leaching conditions such as leaching temperature. Higher leaching temperatures allow for faster leaching completion. Therefore, the Ni and Co leaching process S103 is preferably carried out at a temperature of 80°C or higher for at least 2 hours (more preferably 6 hours or higher, particularly preferably 10 hours or higher). Alternatively, it is preferably carried out at a temperature of 70°C or higher for at least 4 hours (more preferably 9 hours or higher). Alternatively, the Ni and Co leaching process S103 is preferably carried out at a temperature of 60°C or higher for at least 6 hours (more preferably 12 hours or higher). The leaching time for the Ni and Co leaching process S103 can be 24 hours or less or 48 hours or less at any temperature.

[0091] Stirring is preferably performed during leaching. The stirring speed is not particularly limited, but is preferably 200 rpm or higher, more preferably 300 rpm or higher, and even more preferably 400 rpm or higher. The stirring speed can be 2000 rpm or lower, 1000 rpm or lower, or 800 rpm or lower.

[0092] As described above, Ni and Co can be leached into the second aqueous phase (i.e., the second ammonia solution). That is, the Ni and Co leaching process S103 can be performed. Ammonia leaching can be completed by solid-liquid separation such as filtration. Figure 2 As shown, through this solid-liquid separation, a second aqueous phase containing Ni and Co (i.e., a second ammonia solution containing Ni and Co) and solid residue can be obtained.

[0093] The Ni and Co extracted into the second aqueous phase can be recovered using known methods. The recovered Ni and Co can be used as raw materials for positive electrode active materials using known methods, or for other purposes. For example, Ni and Co can advantageously be recovered by evaporating ammonia from the second aqueous phase to convert it into nickel carbonate and cobalt carbonate. Alternatively, they can be recovered by adding sulfuric acid or the like to the aqueous phase to convert it into nickel sulfate and cobalt sulfate. In this case, if the evaporated ammonia is recovered, it is advantageous to reuse it in at least one of the Li, Cu leaching process S101 and the Ni, Co leaching process S103.

[0094] According to the valuable metal recovery method disclosed herein, Ni, Co, and Cu can be recovered with high recovery rates from materials containing water-soluble Li compounds, Ni, Co, and Cu (especially roasted black powder from lithium-ion secondary batteries). Furthermore, in this valuable metal recovery method, ammonia, a component of the leaching agent used in the extraction of Li and Cu, can be recovered and reused, thus making the leaching agent suitable for reuse. Additionally, the valuable metal recovery method of this disclosure is simple to implement. Moreover, the valuable metal recovery method of this disclosure can be used as a method for regenerating cathode materials. Therefore, the valuable metal recovery method of this disclosure is extremely useful in the material recovery of lithium-ion secondary batteries.

[0095] The following describes in detail test examples related to this disclosure, but it is not intended to limit this disclosure to the contents shown in these test examples.

[0096] [Preparation of the object to be leached]

[0097] First, prepare the roasted black powder for the leaching target in the following order. The powder will be applied to an aluminum (Al) foil containing a lithium nickel cobalt manganese composite oxide (LiNi). 0.6 Co 0.2 Mn 0.2 The positive electrode with an active material layer containing O2 was crushed. The crushed positive electrode was passed through a 500 μm sieve to prepare positive electrode powder. Separately, the negative electrode with a graphite-containing active material layer on copper foil was crushed. The pulverized negative electrode was passed through a 500 μm sieve to prepare negative electrode powder. The obtained positive and negative electrode powders were mixed to obtain black powder. This black powder was calcined at 750°C for 6 hours under a low-oxygen atmosphere to obtain calcined black powder with most of the metal reduced. This calcined black powder contains Li in the form of Li2CO3 and Ni, Co, and Cu in metallic form. 1 g of this calcined black powder was dissolved in acid and subjected to high-frequency inductively coupled plasma (ICP) emission spectroscopy analysis. Based on the analysis results, the amounts of Li, Ni, Co, and Cu in the calcined black powder were determined.

[0098] [Li and Cu Leaching Studies]

[0099] [Experimental Example 1]

[0100] The calcined black powder was added to a sufficient amount of water. While supplying oxygen to the water by bubbling, leaching was carried out at room temperature (25°C) for 3 hours with stirring at 800 rpm. Then, solid-liquid separation was performed by filtration to obtain leachate and solid residue.

[0101] [Experimental Example 2]

[0102] The calcined black powder was added to 0.5 mol / L (approximately 0.9% by mass) of ammonia water. Ammonia leaching was carried out for 3 hours at room temperature (25°C) with stirring at 800 rpm while supplying oxygen to the ammonia water by bubbling. Then, solid-liquid separation was performed by filtration to obtain leachate and solid residue.

[0103] [Experimental Example 3]

[0104] An ammonia solution containing ammonium carbonate dissolved in 0.5 mol / L (approximately 0.9% by mass) ammonia solution was obtained, with an equimolar amount of ammonium carbonate relative to the total molar amount of Ni and Co contained in the calcined black powder. The calcined black powder was then added to this ammonia solution. Ammonia leaching was carried out for 3 hours at room temperature (25°C) with stirring at 800 rpm while supplying oxygen to the ammonia solution via bubbling. Solid-liquid separation was then performed by filtration to obtain the leachate and solid residue.

[0105] [Leaching Rate Evaluation]

[0106] ICP emission spectroscopy analysis was performed on the leachates obtained in Examples 1-3 to determine the amounts of Li, Ni, Co, and Cu in the leachates. Using the determined values ​​and the initial amounts in the calcined black powder, the leaching rates (%) of Li, Ni, Co, and Cu were calculated. The average of the Ni leaching rate (%) and the Co leaching rate (%) was taken as the "Ni and Co loss rate (%)". The results are shown in Table 1.

[0107]

[0108] [Li and Cu Separation Study]

[0109] [Experimental Example 4]

[0110] The leachate obtained in Example 3 was heated to 80°C and stirred at 800 rpm for 6 hours while maintaining the temperature at 80°C. This evaporated the ammonia. Then, solid-liquid separation was performed by filtration to obtain an aqueous phase and solid residue.

[0111] [Experimental Example 5]

[0112] In the leachate obtained in Example 3, a molar amount of lithium hydroxide (LiOH) exceeding the amount of Li contained in the leachate was dissolved. The solution was heated to 80°C and stirred at 800 rpm for 6 hours while maintaining the temperature at 80°C. This evaporated the ammonia. Solid-liquid separation was then performed by filtration to obtain an aqueous phase and a solid residue.

[0113] [Evaluation of Li and Cu Recovery Rates]

[0114] ICP emission spectroscopy analysis was performed on the aqueous phases obtained in Experiments 4 and 5 to determine the amounts of Li and Cu in the aqueous phase. Using the determined values ​​and the initial amounts of Li and Cu in the calcined black powder mentioned above, the residual proportions (%) of Li and Cu in the aqueous phase were calculated. The residual proportion of Li (%) was taken as the Li recovery rate (%), and the value obtained by subtracting the residual proportion of Cu (%) from 100% was taken as the Cu recovery rate (%). The results are shown in Table 2.

[0115]

[0116] [Ni and Co leaching studies]

[0117] [Experimental Example 6]

[0118] Ammonium carbonate, in an amount equal to 1.5 moles of the total Ni and Co contained in the solid residue obtained in Example 3, was dissolved in 13 mol / L (approximately 24.3% by mass) ammonia water to obtain an ammonia solution. The solid residue obtained in Example 3 was then added to this ammonia solution. Ammonia leaching was carried out for 3 hours at room temperature (25°C) with stirring at 800 rpm while supplying oxygen to the ammonia solution by bubbling. Solid-liquid separation was then performed by filtration to obtain the leachate and the solid residue.

[0119] [Experimental Example 7]

[0120] The amount of ammonium carbonate used was changed from 1.5 moles to 2.0 moles, and the same operation as in Experiment 6 was performed to obtain leachate and solid residue.

[0121] [Experimental Example 8]

[0122] The amount of ammonium carbonate used was changed from 1.5 moles to 2.5 moles, and the same operation as in Experiment 6 was performed to obtain leachate and solid residue.

[0123] [Ni and Co recovery rate evaluation]

[0124] ICP emission spectroscopy analysis was performed on the leachates obtained in Examples 6-8 to determine the amounts of Ni and Co in the leachates. Using the determined values ​​and the initial values ​​of Ni and Co in the calcined black powder mentioned above, the Ni leaching rate (%) and Co leaching rate (%) in the aqueous phase were calculated. The average value of the Ni leaching rate (%) and Co leaching rate (%) was taken as the "Ni and Co recovery rate (%)". The results are shown in Table 3.

[0125]

[0126] As shown in Table 1, the Li and Cu leaching steps of the valuable metal recovery method of this disclosure can separate Li and Cu from the object containing water-soluble Li compounds, Ni, Co, and Cu. Furthermore, as shown in Table 2, the separation steps of the valuable metal recovery method of this disclosure can separate Li and Cu from an aqueous phase containing Li and Cu. Moreover, as shown in Table 3, the Ni and Co leaching steps of the valuable metal recovery method of this disclosure can separate Ni and Co.

[0127] Furthermore, as shown in the above experimental examples, it can be seen that the valuable metal recovery method of this disclosure can easily separate Li, Ni, Co, and Cu from an object containing water-soluble Li compounds, Ni, Co, and Cu. Additionally, in the valuable metal recovery method of this disclosure, the ammonia in the leaching agent used to separate Li and Cu is suitable for reuse.

[0128] The specific examples of this disclosure have been described in detail above, but these are merely illustrative and do not limit the scope of patent protection. The technology described in the scope of patent protection includes technologies that have undergone various modifications and alterations to the specific examples described above.

[0129] That is, the method for recycling valuable metals disclosed herein is as follows [1] to

[10] .

[0130] [1] A method for recycling valuable metals, comprising:

[0131] In the Li and Cu leaching process, Li and Cu are leached from the substrate containing water-soluble Li compounds, Ni, Co, and Cu into the first aqueous phase via ammonia leaching.

[0132] The separation process involves evaporating ammonia from the first aqueous phase to separate Li from Cu, and...

[0133] In the Ni and Co leaching process, Ni and Co are leached from the solid residue obtained in the above Li and Cu leaching process into the second aqueous phase through ammonia leaching.

[0134] [2] According to the method of [1], wherein, in the above separation process, the evaporated ammonia is recovered.

[0135] The recovered ammonia is reused in at least one of the above-mentioned Li and Cu leaching processes and the above-mentioned Ni and Co leaching processes.

[0136] [3] The method according to item [1] or [2], wherein the ammonia leaching of the above-mentioned Li, Cu leaching process is carried out using a first ammonia solution containing water and ammonia.

[0137] [4] The method according to item [3], wherein the first ammonia solution further comprises ammonium carbonate.

[0138] The amount of ammonium carbonate in the first ammonia solution is 0.5 to 1.5 times the amount of Cu contained in the above-mentioned object.

[0139] [5] According to the method described in item [3], the ammonia leaching process of the above-mentioned Li and Cu leaching steps is carried out while supplying oxygen-containing gas to the first ammonia solution.

[0140] [6] The method according to any one of [1] to [5], wherein, in the separation step described above, lithium hydroxide is added to the first aqueous phase and then ammonia is evaporated.

[0141] [7] The method according to any one of [1] to [6], wherein the ammonia leaching of the above-mentioned Ni and Co leaching steps is carried out using a second ammonia solution containing water, ammonia and at least one inorganic ammonium salt selected from ammonium sulfate and ammonium carbonate.

[0142] [8] According to the method described in item [7], the ammonia leaching of the Ni and Co leaching process is carried out while supplying oxygen-containing gas to the second ammonia solution.

[0143] [9] The method according to any one of [1] to [8], wherein the object contains Ni, Co and Cu in the form of metals.

[0144]

[10] The method according to any one of [1] to [9], wherein the object is calcined black powder from waste lithium-ion secondary batteries.

Claims

1. A method for recycling valuable metals, comprising: In the Li and Cu leaching process, Li and Cu are leached from the substrate containing water-soluble Li compounds, Ni, Co, and Cu into the first aqueous phase via ammonia leaching. The separation process involves evaporating ammonia from the first aqueous phase to separate Li from Cu, and... In the Ni and Co leaching process, Ni and Co are leached from the solid residue obtained in the Li and Cu leaching process into the second aqueous phase through ammonia leaching.

2. The method according to claim 1, wherein, In the separation process, the evaporated ammonia is recovered. The recovered ammonia is reused in at least one of the Li, Cu leaching process and the Ni, Co leaching process.

3. The method according to claim 1, wherein, The ammonia leaching process of the Li and Cu is carried out using a first ammonia solution containing water and ammonia.

4. The method according to claim 3, wherein, The first ammonia solution further contains ammonium carbonate. The amount of ammonium carbonate in the first ammonia solution is 0.5 to 1.5 times the amount of Cu contained in the object.

5. The method according to claim 3, wherein, While supplying oxygen-containing gas to the first ammonia solution, ammonia leaching of the Li and Cu leaching process is carried out.

6. The method according to claim 1, wherein, In the separation process, lithium hydroxide is added to the first aqueous phase, and then ammonia is evaporated.

7. The method according to claim 1, wherein, The ammonia leaching process of the Ni and Co leaching steps is carried out using a second ammonia solution containing water, ammonia, and at least one inorganic ammonium salt selected from ammonium sulfate and ammonium carbonate.

8. The method according to claim 7, wherein, While supplying oxygen-containing gas to the second ammonia solution, ammonia leaching of the Ni and Co leaching process is carried out.

9. The method according to claim 1, wherein, The object contains Ni, Co, and Cu in metallic form.

10. The method according to claim 1, wherein, The object being referred to is the calcined black powder from waste lithium-ion secondary batteries.

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