Metal leaching methods

Abstract

This invention provides a metal leaching method that can address the generation of phosphine during metal leaching. [Solution] A method for leaching metal from battery powder of lithium-ion battery waste, wherein the battery powder contains phosphorus (P), and after contact with the battery powder, phosphine (PH3) derived from the phosphorus in the battery powder is generated in the acidic leaching solution, and at least a portion of the phosphine is removed.

Description

Technical Field

[0001] This specification describes a method for metal leaching.

Background Art

[0002] The process for recovering metals from lithium-ion battery waste may include, for example, roasting of lithium-ion battery waste and other predetermined pretreatments, and wet treatment of the battery powder obtained after the pretreatment.

[0003] In the wet treatment, specifically, metals such as cobalt, nickel, manganese, lithium, aluminum, and iron in the battery powder may be leached into an acidic leaching solution to obtain a metal-containing solution in which the metals are dissolved. Subsequently, aluminum ions, iron ions, manganese ions, etc. may be sequentially or simultaneously removed from the metal-containing solution by neutralization or solvent extraction, and then cobalt ions or nickel ions in the metal-containing solution may be separated by solvent extraction.

[0004] As a technology related to leaching metals in battery powder with an acid in wet treatment, for example, there are those described in Patent Documents 1 to 5.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Summary of the Invention

Problems to be Solved by the Invention

[0006] Incidentally, battery powder can contain phosphorus (P). When metals in such battery powder are leached into an acidic leaching solution, highly toxic phosphine (PH3) may be produced.

[0007] This specification provides a metal leaching method that can address the generation of phosphine during metal leaching. [Means for solving the problem]

[0008] The metal leaching method described in this specification is a method for leaching metal from battery powder of lithium-ion battery waste, wherein the battery powder contains phosphorus (P), and after contact with the battery powder, phosphine (PH3) derived from the phosphorus in the battery powder is generated in the acidic leaching solution, and at least a portion of the phosphine is removed. [Effects of the Invention]

[0009] The above metal leaching method can address the generation of phosphine during metal leaching. [Brief explanation of the drawing]

[0010] [Figure 1] This is a flowchart showing an example of a metal recovery method, including a metal leaching method according to one embodiment. [Figure 2] This is a schematic diagram showing an example of a metal leaching apparatus that can be used in a metal leaching method according to one embodiment. [Figure 3] This graph shows the changes in pH3 concentration and liquid temperature over time during metal leaching in the comparative example. [Figure 4] These graphs show the changes over time in pH3 concentration and liquid temperature during metal leaching in Example 1, as well as the changes over time in pH and oxidation-reduction potential (ORP) (based on silver / silver chloride potential). [Figure 5] This graph shows the changes in pH3 concentration and liquid temperature over time during metal leaching in Example 2. [Figure 6]It is a graph showing the change over time of the PH3 concentration and the liquid temperature during metal leaching in Example 3. [Figure 7] It is a graph showing the change over time of the PH3 concentration and the liquid temperature during metal leaching in Example 4. [Figure 8] It is a graph showing the change over time of the PH3 concentration and the liquid temperature during metal leaching in Example 5. [Figure 9] It is a graph showing the change over time of the PH3 concentration and the liquid temperature during metal leaching in Example 6.

Mode for Carrying Out the Invention

[0011] Hereinafter, embodiments of the above-described metal leaching method will be described in detail. The metal leaching method of one embodiment is a method for leaching metals in battery powder of lithium ion battery waste, and targets battery powder containing phosphorus (P).

[0012] When such battery powder is brought into contact with an acidic leaching solution, there is a possibility that phosphine (PH3) may be generated by phosphorus in the battery powder. In contrast, in this embodiment, the redox potential (silver / silver chloride potential reference) of the acidic leaching solution after contact with the battery powder is maintained at 0 mV or more. By keeping the redox potential (silver / silver chloride potential reference) at 0 mV or more, it becomes an oxidized state, and the reaction in which phosphorus in the battery powder becomes phosphine is suppressed. As a result, the generation of phosphine is suppressed, so that it is possible to effectively deal with the generation of phosphine during metal leaching.

[0013] The metal leaching method of this embodiment can be used in the process of recovering metals from lithium-ion battery waste. Hereinafter, the case where the metal leaching method is applied to the leaching of metals in the metal recovery method of lithium-ion battery waste as illustrated in FIG. 1 will be described as an example. However, the metal leaching method is not limited thereto, and can be used in various methods including a step of leaching metals in the battery powder of lithium-ion battery waste into an acidic leaching solution. Further, as the battery powder, it is also possible to use those obtained from battery waste other than lithium-ion battery waste. Here, as an example, the case of obtaining battery powder from lithium-ion battery waste will be described in detail. Battery waste means a battery to be recycled, and it does not matter whether the battery waste is traded at a price or traded free of charge or as industrial waste.

[0014] (Lithium-ion battery waste) Lithium-ion battery waste is a lithium-ion secondary battery for vehicle use or consumer use, etc., which has been discarded due to the life of the battery product, manufacturing defects or other reasons, and it does not matter whether it is traded at a price or traded free of charge or as industrial waste. Examples of vehicle-mounted lithium-ion secondary batteries include those included in vehicle-mounted battery packs mounted on vehicles such as hybrid vehicles and electric vehicles. Examples of consumer lithium-ion secondary batteries include those used in mobile phones and various other electronic devices. Recovering cobalt and nickel from such lithium-ion battery waste is required from the perspective of effective utilization of resources. In addition, manganese and lithium may also be metals to be recovered.

[0015] Lithium-ion battery waste includes a positive electrode material, a negative electrode material, an electrolyte, and an aluminum casing etc. around them. Here, the positive electrode material and the negative electrode material can be each constituted by fixing a positive electrode active material or a negative electrode active material on a positive electrode current collector such as an aluminum foil or a negative electrode current collector such as a copper foil with, for example, polyvinylidene fluoride (PVDF) or other organic binders.

[0016] Of these, the positive electrode active material is, for example, a single metal oxide from among lithium, nickel, cobalt, and manganese, or a composite metal oxide of two or more of these. Examples of such positive electrode active materials include LiCoO2, LiNiO2, Li-Co-Ni-O, and Li-Co-Ni-Mn-O. The positive electrode active material contains valuable metals, and recovering such metals is desirable from the standpoint of effective resource utilization. Even if the form of metals such as cobalt, nickel, and lithium contained in the positive electrode active material changes due to heat treatment or other processes described later, they can still be recovered regardless of their form.

[0017] Furthermore, carbon-based materials are sometimes used as the negative electrode active material, and the electrolyte is often an electrolyte solution in which an electrolyte such as lithium hexafluoride phosphate is dissolved in an organic solvent such as ethylene carbonate or diethyl carbonate.

[0018] (Pre-processing) Pretreatment often involves heat treatment, crushing, and sieving of lithium-ion battery waste in this order or in any order, although at least one of these treatments may be omitted. Battery powder is obtained by pretreatment of lithium-ion battery waste. Here, battery powder refers to the powder obtained by separating and concentrating the positive electrode material components after some pretreatment of lithium-ion battery waste.

[0019] Battery powder can also be obtained by heat-treating lithium-ion battery waste, followed by crushing and sieving, which concentrates the positive electrode material components into a powder. The heat treatment may be performed before the crushing process or between the crushing and sieving processes. Below, as an example, we will describe the case in which heat treatment, crushing, and sieving are performed in this order on lithium-ion battery waste.

[0020] The heat treatment is primarily performed to remove the electrolyte from lithium-ion battery waste. The temperature at which the lithium-ion battery waste is heated during the heat treatment is not particularly important. During the heat treatment, the lithium-ion battery waste may be heated to a temperature at which the electrolyte can be removed, for example, 100°C or higher, typically 100°C to 185°C or 185°C to 350°C. Alternatively, the lithium-ion battery waste may be heated at a relatively high temperature of 300°C or higher, for example 350°C to 650°C, especially 400°C to 600°C, for 1 to 8 hours, either after heating at a low temperature or without heating at a low temperature. High-temperature heating can cause decomposition of LiCoO2 and other materials in the positive electrode active material, potentially generating cobalt oxide, metallic cobalt, lithium carbonate, etc.

[0021] Heating in the heat treatment can be carried out under various atmospheres, such as an air atmosphere, an inert atmosphere, or a reduced-pressure atmosphere such as a vacuum. The atmosphere may be switched midway through the process, and heating under an air atmosphere and heating under an inert atmosphere may be performed in any order. Battery powder obtained by heat treatment of lithium-ion battery waste under an inert atmosphere tends to have phosphorus contained therein readily converted to phosphine when in contact with an acidic leachate. For this reason, this embodiment is particularly effective when applied to battery powder subjected to heat treatment under an inert atmosphere.

[0022] The heat treatment furnace is not particularly limited, but for example, if it is a batch type, an atmosphere-type or vacuum-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.

[0023] After heat treatment, lithium-ion battery waste can be crushed. This crushing process destroys the casing of the lithium-ion battery waste and separates metals derived from the positive electrode, such as nickel and cobalt, from the aluminum foil. Various known crushers can be used for the crushing process, but specific examples include impact-type crushers that can crush the casing by applying impact while cutting it, such as sample mills, hammer mills, pin mills, wing mills, tornado mills, and hammer crushers.

[0024] After crushing, the crushed lithium-ion battery waste is further crushed or pulverized into a powder as needed, and then sieved using a sieve with an appropriate mesh size. This process leaves, for example, aluminum and copper on the sieve, while removing a certain amount of aluminum and copper to obtain battery powder containing lithium, cobalt, nickel, etc., below the sieve.

[0025] Furthermore, if necessary, the battery powder can be brought into contact with a liquid such as water before the metal leaching method described below to selectively leach lithium. In this case, tap water, industrial water, distilled water, purified water, ion-exchanged water, pure water, ultrapure water, etc., can be used, and the liquid temperature at the time of contact between the battery powder and the liquid can be 10°C to 60°C. The lithium solution obtained by lithium leaching can be subjected to treatments such as solvent extraction, neutralization, and carbonation to recover lithium in the lithium solution as lithium carbonate. The lithium carbonate obtained in this way may be purified as necessary to reduce the impurity content. When lithium leaching is performed in this manner, the residue after leaching is used as battery powder, and the metal leaching method described below is then carried out on it.

[0026] When battery powder contains nickel as a metal, the nickel content is, for example, 1% to 30% by mass, typically 5% to 20% by mass. When it contains cobalt, the cobalt content in the battery powder is, for example, 1% to 30% by mass, typically 5% to 20% by mass. Furthermore, battery powder may contain, for example, 2% to 8% by mass of lithium, 1% to 30% by mass of manganese, 1% to 10% by mass of aluminum, 1% to 5% by mass of iron, and 1% to 10% by mass of copper. The content of each metal in the battery powder can be measured by ICP emission spectrometry after leaching and dissolving the battery powder.

[0027] The metals in battery powder, such as cobalt and nickel, may be reduced from metal oxides in lithium-ion battery waste through the heat treatment under the inert atmosphere described above, resulting in elemental metals. When battery powder containing elemental metals is brought into contact with an acidic leaching solution for metal leaching, the oxidation-reduction potential decreases, leading to a reduced state, which makes phosphine formation more likely. Even with such battery powder, leaching the metal using the metal leaching method described later can suppress phosphine formation and / or remove any phosphine that is formed, thus effectively addressing phosphine formation. The presence of elemental metals in battery powder can be confirmed by X-ray diffraction (XRD).

[0028] This embodiment focuses on battery powder containing phosphorus. When such battery powder comes into contact with an acidic leaching solution during metal leaching, the phosphorus may react and produce phosphine. The phosphorus content in battery powder is, for example, 0.1% to 1.0% by mass, typically 0.3% to 0.6% by mass. The phosphorus content can be measured by ICP emission spectrometry after the battery powder has been leached and dissolved.

[0029] (Metal leaching method) In the metal leaching method, the battery powder is brought into contact with an acidic leaching solution containing an inorganic acid such as sulfuric acid, hydrochloric acid, or nitric acid, and the metal in the battery powder is leached into the acidic leaching solution. The leaching of metal from the battery powder may be carried out in a leaching tank 2 of a metal leaching facility 1 as illustrated in Figure 2. For example, battery powder may be placed in leaching tank 2, water or other liquid such as pure water is added, the temperature is heated to about 60°C to 80°C, and the battery powder is brought into contact with the acidic leaching solution containing water and inorganic acid while an inorganic acid such as sulfuric acid is added, thereby leaching the metal into the acidic leaching solution. The amount of inorganic acid to be added can be determined based on the composition of the battery powder, and it may be added to the liquid at a relatively slow rate over a period of about 1 to 2 hours. The rate of addition of inorganic acid may be kept constant.

[0030] In this case, if the battery powder contains phosphorus, there is a risk that toxic phosphine may be generated by the reaction of that phosphorus. To suppress this, it is effective to maintain the oxidation-reduction potential (based on silver / silver chloride potential) of the acidic leachate at 0mV or higher from the moment the acidic leachate comes into contact with the battery powder. This is because it creates a reducing state in which phosphine generation is less likely. From the viewpoint of further suppressing phosphine generation, it is preferable to maintain the oxidation-reduction potential (based on silver / silver chloride potential) of the acidic leachate in contact with the battery powder at 100mV or higher. The oxidation-reduction potential is measured using an ORP electrode.

[0031] Simply bringing battery powder into contact with an acidic leachate may not be sufficient to raise the oxidation-reduction potential (based on silver / silver chloride potential) of the acidic leachate as described above. In such cases, it is preferable to add an oxidizing agent to the acidic leachate. Adding an oxidizing agent can raise the oxidation-reduction potential (based on silver / silver chloride potential) of the acidic leachate. Examples of oxidizing agents include hydrogen peroxide and potassium permanganate (KMnO4). Among these, using an oxidizing agent containing hydrogen peroxide is preferable from the viewpoint of suppressing the contamination of the acidic leachate with impurities.

[0032] When phosphine derived from phosphorus in the battery powder is generated after contact with the battery powder in an acidic leachate, at least a portion, preferably almost all, of that phosphine can be removed. Here, at least a portion of the phosphine generated by contact between the battery powder and the acidic leachate can be removed without performing the oxidation-reduction cell preparation described above. Alternatively, at least a portion of the phosphine generated despite maintaining the oxidation-reduction potential (based on silver / silver chloride potential) of the acidic leachate above 0mV, and even above 100mV, after contact with the battery powder can be removed.

[0033] Phosphine removal can be performed, for example, by using the metal leaching equipment 1 shown in Figure 2. This metal leaching equipment 1, as an example, includes, in addition to the leaching tank 2 described above, an adsorption tower 4 connected to the leaching tank 2 by a gas supply pipe 3a, a measuring container 5 connected to the adsorption tower 4 by a gas supply pipe 3b, and collection tanks 6a and 6b connected to the adsorption tower 4 via the measuring container 5 by further gas supply pipes 3c and 3d.

[0034] In the leaching tank 2 of such a metal leaching facility 1, if phosphine is generated by contact between phosphorus-containing battery powder and an acidic leaching solution, the pH3-containing gas containing the phosphine is sent to the adsorption tower 4 via the gas supply pipe 3a. The adsorption tower 4 is equipped with porous silica gel containing SiO2·nH2O, and at least a portion of the phosphine contained in the pH3-containing gas sent to the adsorption tower 4 is adsorbed therein.

[0035] As described above, by passing a pH3-containing gas through an adsorption tower 4 equipped with silica gel inside, at least a portion of the phosphine in the pH3-containing gas can be removed.

[0036] Inside the measuring container 5, the phosphine concentration and humidity of the gas that has passed through the adsorption tower 4 and flowed in from the gas supply pipe 3b can be measured. A concentration meter and a humidity meter may be installed inside the measuring container 5.

[0037] In the illustrated metal leaching apparatus 1, if phosphine in the pH3-containing gas is not completely removed in the adsorption tower 4 and phosphine remains in the pH3-containing gas, the pH3-containing gas passes sequentially through the gas supply pipe 3b, the measuring container 5, and the gas supply pipe 3c to the collection tanks 6a and 6b. Potassium permanganate (KMnO4) aqueous solution is stored in the collection tanks 6a and 6b. When the pH3-containing gas is supplied from the gas supply pipe 3c into the potassium permanganate aqueous solution in the collection tanks 6a and 6b, at least a portion of the phosphine contained in it is absorbed and removed by the potassium permanganate aqueous solution.

[0038] While it is possible to have only one collection tank 6a and 6b, as shown in the figure, there may be multiple collection tanks, including an upstream collection tank 6a and a downstream collection tank 6b that are interconnected by a gas supply pipe 3d. When multiple collection tanks 6a and 6b are provided, the PH3-containing gas passes through these collection tanks 6a and 6b sequentially, allowing for more effective removal of phosphine from the PH3-containing gas.

[0039] Furthermore, a gas discharge pipe 7 connected to a gas scrubbing tower (not shown) can be provided further downstream of the collection tanks 6a and 6b. In the illustrated example, the downstream collection tank 6b is connected to the gas discharge pipe 7. In this case, the gas that has passed through the collection tank 6b can be sent from the gas discharge pipe 7 to the gas scrubbing tower.

[0040] The phosphine in the pH3-containing gas generated in the leaching tank 2 can be removed by reacting it with copper ions contained in the acidic leaching solution, in addition to or instead of removing it using the adsorption tower 4 described above. In this case, the phosphine generated in the acidic leaching solution reacts with the copper ions, for example, using formula 8Cu 2+ +PH3+4H2O→8Cu + +4 3- +11H + Reactions such as those described above may occur, leading to decomposition and removal.

[0041] To ensure that the acidic leaching solution contains copper ions, copper that may be present in the battery powder can be leached into the acidic leaching solution. However, the battery powder targeted in this embodiment may contain copper as a single metal, and single metal copper may not dissolve easily into the acidic leaching solution due to its relationship with other metals.

[0042] To introduce copper ions into the acidic leaching solution, a copper compound may be added to the solution. The copper compound will leach into the acidic leaching solution, generating copper ions. The copper compound may be added to the acidic leaching solution along with the battery powder, as it may be contained in the battery powder, or it may be added to the acidic leaching solution separately from the battery powder. As an example, the battery powder and copper compound may be placed in the leaching tank 2 beforehand, and then water and an inorganic acid may be added to the solution to introduce the copper compound into the acidic leaching solution.

[0043] Specific examples of copper compounds to be added to acidic leaching include copper(II) sulfate (CuSO4) and copper(II) oxide (CuO). Since such copper sulfates and copper oxides readily leach into acidic leaching, they are suitable for generating copper ions in the acidic leaching solution.

[0044] It is preferable to add the copper compound to the acidic leaching solution in the early stages of leaching. This is because, in the early stages of the reaction, there are many components that dissolve, so the leaching reaction proceeds easily and the oxidation-reduction potential tends to decrease. As a result, phosphine is easily generated in the early stages of leaching, while it tends not to be generated in the later stages. As a specific example, when obtaining an acidic leaching solution by adding an inorganic acid to a liquid such as water, as described above, the addition of the copper compound to the liquid can be started and stopped between the start and end of the addition of the inorganic acid to the liquid. Furthermore, it is preferable to gradually add the copper compound to the acidic leaching solution in the first half of the above period. This is because if the copper compound is added all at once in the early stages of leaching, there is a concern that the copper ions generated in the acidic leaching solution will be largely used for substitution reactions (cementation) with cobalt and other elements in the battery powder, and will not be used as much for the reaction with phosphine. In the above example, for example, an amount of copper compound equal to the total amount of copper compound added divided by the acid addition time can be added at a constant rate from the start to the end of the acid addition. The rate at which the copper compound is added may be somewhat slow, similar to the rate at which the inorganic acid is added as described earlier. In this case, the copper compound may be added continuously or intermittently.

[0045] The amount of copper added to the acidic leaching solution from the copper compound is preferably 1 to 3 times the molar equivalent of the total content of the base metal in the battery powder in the substitution reaction between copper ions and base metals (metals baser than copper) in the battery powder. If the amount of copper added to the acidic leaching solution from the copper compound is too small, there is a concern that many of the resulting copper ions will be used in the substitution reaction, and the phosphine will not be removed to a sufficient extent. On the other hand, if the copper content is too high, some copper ions will remain in the post-leaching solution obtained after the metal has been leached, which may increase the burden of removing these copper ions from the metal-containing solution in subsequent processes. However, it is expected that copper ions that were not used in the reaction with phosphine will be reduced by the substitution reaction as the metal in the battery powder is leached, and precipitate as solid copper, which can be removed by solid-liquid separation after leaching. From the standpoint of thoroughly removing phosphine, it is desirable to add a large amount of copper (copper compound) to the acidic leachate so that copper ions remain in the leachate after extraction.

[0046] When the metal leaching is complete, the acidic leaching solution is discharged from the leaching tank 2, and then the leaching residue can be separated from the acidic leaching solution using a solid-liquid separation device such as a filter press or thickener. This yields a metal-containing solution as a post-leaching solution containing various metal ions derived from the metal in the battery powder.

[0047] (Impure removal and metal recovery) The metal-containing solution obtained by the metal leaching method described above can be subjected to a process to remove impurities and then recover metals such as cobalt and nickel. For example, impurity removal can be done by removing some aluminum and iron by neutralization, or by removing the remaining aluminum and manganese by solvent extraction. For metal recovery, cobalt and nickel can be sequentially extracted by solvent extraction, and then recovered by back-extraction. Furthermore, lithium can be recovered from the post-extraction solution after the extraction of cobalt and nickel by various methods. For example, if the post-extraction solution is a lithium sulfate solution, a lithium hydroxide solution can be prepared from that lithium sulfate solution, and lithium hydroxide can be crystallized from it. [Examples]

[0048] Next, we will describe the tests conducted to confirm the effectiveness of the metal leaching method described above. However, this description is for illustrative purposes only and is not limited to this method.

[0049] (Test Example 1) Ten grams of battery powder (Mn: 1.8% by mass, Co: 4.1% by mass, Ni: 27.4% by mass, Li: 3.7% by mass, Cu: 0.5% by mass, P: 0.6% by mass) obtained from lithium-ion battery waste was brought into contact with an acidic leachate containing 411 mL of water and 5.2 mL of 98% sulfuric acid, and the metals in the battery powder were leached into the acidic leachate at a liquid temperature of 70°C. More specifically, after adding the battery powder to the water in the leachate, the temperature was heated and maintained at 70°C, and then sulfuric acid was added.

[0050] The leaching tank was connected to the measuring container by a gas supply pipe, and the pH3 concentration in the gas generated in the leaching tank during metal leaching was measured using a Dräger Pac8000 installed inside the measuring container. The gas flow rate supplied from the leaching tank to the measuring container during metal leaching was 650 mL / min.

[0051] In the comparative example, no oxidizing agent was added during metal leaching. In Example 1, 30% hydrogen peroxide was intermittently added as an oxidizing agent from the moment the battery powder was brought into contact with the acidic leaching solution, so that the oxidation-reduction potential (based on silver / silver chloride potential) of the acidic leaching solution was 100 mV or higher. The results are shown in Figures 3 and 4, respectively.

[0052] In the comparative example, as shown in Figure 3, the pH3 concentration increased sharply, especially in the initial stages of leaching. In contrast, in Example 1, as shown in Figure 4, the pH3 concentration remained low even in the initial stages of leaching.

[0053] (Test Example 2) In Example 2, the metal in the battery powder was leached in an acidic leaching solution under the same conditions and procedures as in Example 1 of Test Example 1, except that a metal leaching apparatus as shown in Figure 2 was used. The results are shown in Figure 5.

[0054] As can be seen from Figure 5, in Example 2, the pH3 in the gas generated in the leaching tank was adsorbed and removed by silica gel in the adsorption tower, resulting in a pH3 concentration below the detection limit during metal leaching.

[0055] (Test Example 3) In Examples 3 to 6, the metal in the battery powder was leached in an acidic leaching solution under the same conditions and procedures as in Example 1 of Test Example 1, except that hydrogen peroxide as an oxidizing agent was not added and a copper compound was added to the acidic leaching solution. As the copper compound, 43 g of copper sulfate was used in Example 3, 13.7 g of copper oxide was used in Example 4, 125 g of copper sulfate was used in Example 5, and 40 g of copper oxide was used in Example 6. The results are shown in Figures 6 to 9, respectively.

[0056] In Examples 3 and 4, as shown in Figures 6 and 7, the maximum pH3 concentration during the metal leaching period was significantly lower compared to the comparative example in Figure 3. Furthermore, as can be seen from Figures 8 and 9, in Examples 5 and 6, where copper sulfate or copper oxide was added in excess, the maximum pH3 concentration decreased even further.

[0057] From the above, it was found that the metal leaching method described above can address the generation of phosphine during metal leaching.

[0058] (Potential contribution to the SDGs) According to the embodiments described above, the generation of phosphine during metal leaching can be addressed, making it possible to safely recover metal from battery powder in various lithium-ion battery wastes, including battery powder that may generate phosphine during metal leaching. Therefore, these embodiments 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. [Explanation of Symbols]

[0059] 1. Metal leaching equipment 2. Leaching tank 3a~3d Gas supply pipe 4 Adsorption tower 5. Measuring container 6a, 6b Collection tank 7. Gas exhaust pipe

Claims

1. A method for leaching metals from battery powder of lithium-ion battery waste, The aforementioned battery powder contains phosphorus (P), In the acidic leachate after contact with the battery powder, the phosphine (pH) derived from the phosphorus in the battery powder was detected. 3 ) generates, A metal leaching method for removing at least a portion of the phosphine.

2. The leaching of metal from the aforementioned battery powder is carried out in a leaching tank. The PH containing the phosphine generated in the leaching tank 3 The contained gas is sent to an adsorption tower connected to the leaching tank and containing silica gel inside, and the pH 3 The metal leaching method according to claim 1, wherein at least a portion of the phosphine in the contained gas is adsorbed onto the silica gel in the adsorption tower.

3. Said PH 3 After the contained gas passes through the adsorption tower, potassium permanganate (KMnO) is introduced into the adsorption tower. 4 ) Send to a collection tank where the aqueous solution is stored, and the pH 3 The metal leaching method according to claim 2, wherein at least a portion of the phosphine in the contained gas is collected with an aqueous potassium permanganate solution in the collection tank.

4. The metal leaching method according to any one of claims 1 to 3, wherein the acidic leaching solution contains copper ions, and at least a portion of the phosphine generated in the acidic leaching solution is reacted with the copper ions.

5. The metal leaching method according to claim 4, further comprising adding a copper compound to the acidic leaching solution and leaching the copper compound into the acidic leaching solution to generate copper ions.

6. The metal leaching method according to claim 5, wherein the copper compound is added to the acidic leaching solution separately from the battery powder.

7. The metal leaching method according to claim 5, wherein the copper compound is added between the time the addition of an inorganic acid to the liquid to obtain the acidic leaching solution is started and the time the addition is finished.

8. The metal leaching method according to claim 5, wherein the copper compound comprises copper sulfate and / or copper oxide.

9. The metal leaching method according to claim 5, wherein copper ions not used in the reaction with phosphine are reduced by a substitution reaction and deposited as copper as metal leaching occurs in the battery powder.

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