Alloy powder, method for manufacturing the same, and method for recovering valuable metal

Abstract

Provided are an alloy powder in which nickel and cobalt are easily subjected to acid dissolution and stable acid leaching, a production method by which the alloy powder capable of stable acid leaching can be inexpensively obtained, and a valuable metal recovery method using the production method. The alloy powder of the present invention contains copper (Cu), nickel (Ni), and cobalt (Co) as constituent components, has a 50% cumulative diameter (D50) in a volume particle size distribution of 30 μm or more and 85 μm or less, and has an oxygen content of 0.01 mass% or more and 1.00 mass% or less.

Description

Technical Field

[0001] This invention relates to alloy powder, its manufacturing method, and methods for recycling valuable metals. Background Technology

[0002] In recent years, lithium-ion batteries have become widely used as lightweight and high-output batteries. A well-known lithium-ion battery has a structure in which a negative electrode material, a positive electrode material, a spacer, and an electrolyte are sealed within an outer casing. Here, the outer casing is made of metals such as iron (Fe) or aluminum (Al). The negative electrode material consists of a negative electrode active material (such as graphite) fixed to a negative electrode current collector (such as copper foil). The positive electrode material consists of a positive electrode active material (such as lithium nickel oxide or lithium cobalt oxide) fixed to a positive electrode current collector (such as aluminum foil). The spacer is made of a porous resin membrane of polypropylene. The electrolyte contains an electrolyte such as lithium hexafluorophosphate (LiPF6).

[0003] One of the main applications of lithium-ion batteries is in hybrid or electric vehicles. Therefore, it is foreseeable that a large number of lithium-ion batteries will be discarded based on the vehicle's lifecycle. In addition, some lithium-ion batteries are discarded as defective products during manufacturing. There is a demand to reuse these used batteries or defective batteries generated during manufacturing (hereinafter, "waste lithium-ion batteries") as resources.

[0004] As a method of recycling, a dry smelting process has been proposed in the past, in which waste lithium-ion batteries are completely melted in a high-temperature furnace (melting furnace). The dry smelting process involves melting the crushed waste lithium-ion batteries and separating and recycling them by utilizing the difference in oxygen affinity between valuable metals such as cobalt (Co), nickel (Ni), and copper (Cu), which are the targets for recycling, and low-value metals such as iron (Fe) and aluminum (Al). In this method, low-value metals are vigorously oxidized to form slag, while valuable metals are oxidized with maximum restraint to form alloys for recycling.

[0005] The recovered alloy primarily contains copper (Cu), nickel (Ni), and cobalt (Co). If the valuable metals (Cu, Ni, Co) can be separated and recovered from this alloy in a dry smelting process, recovery can be achieved at low cost. One proposed dry smelting method is to feed the recovered alloy into a copper smelting process. However, the recovered alloy typically contains a predetermined amount of iron (Fe). Therefore, if the recovered alloy is fed into the copper smelting process, cobalt (Co) is distributed into oxides along with iron (Fe), making it difficult to recover cobalt (Co) in its elemental form.

[0006] Therefore, methods for recovering valuable metals from recycled alloys using a wet smelting process are being investigated. Specifically, the recycled alloy (copper-nickel-cobalt alloy) undergoes acid leaching to dissolve nickel (Ni) and cobalt (Co) in a solvent. The solution containing nickel and cobalt is then separated from copper as a dissolution residue. Copper, nickel, and cobalt are then recovered using existing smelting processes.

[0007] For example, Patent Document 1 discloses a method for recovering valuable metals containing nickel and cobalt from waste lithium-ion batteries containing nickel and cobalt. The method includes: a melting step of melting waste lithium-ion batteries to obtain a molten material; an oxidation step of oxidizing the molten material or waste batteries; a slag separation step of separating slag from the molten material and recovering the alloy containing the valuable metal; and a dephosphorization step of separating phosphorus contained in the alloy (claim 1 of Patent Document 1). Furthermore, Patent Document 1 discloses a method of performing alloy shot peening on the alloy obtained through the dephosphorization step to form granules, dissolving the alloy in acid, and then performing elemental separation and recovering the valuable metal through steps of iron removal, copper separation and recovery, nickel / cobalt separation, nickel recovery, and cobalt recovery (

[0047] to

[0053] of Patent Document 1).

[0008] Existing technical documents

[0009] Patent documents

[0010] Patent Document 1: Japanese Patent No. 5853585. Summary of the Invention

[0011] The problem the invention aims to solve

[0012] As mentioned above, although methods for recovering valuable metals from recycled alloys (copper-nickel-cobalt alloys) using wet smelting processes have been proposed, there is still room for improvement in previous methods. Specifically, copper-nickel-cobalt alloys generally exhibit high corrosion resistance. Therefore, depending on particle morphology such as particle size, shape, surface roughness, and composition distribution, they sometimes remain completely undissolved even after immersion in sulfuric acid for more than 24 hours. Consequently, even acid leaching of this alloy can sometimes fail to achieve sufficient separation and recovery of nickel and cobalt.

[0013] The inventors conducted focused research on these issues. The results showed that the oxygen content and median particle size of the copper-nickel-cobalt alloy are both important during acid leaching. By appropriately controlling these parameters, nickel and cobalt are readily dissolved in acid, resulting in stable acid leaching of these components. Furthermore, the inventors realized that the alloy powder is produced by water atomization, and the pressure and amount of water sprayed are crucial for obtaining alloy powder capable of stable acid leaching.

[0014] Therefore, the objective of this invention is to provide alloy powders in which nickel and cobalt are readily acid-soluble and can be stably acid-leached. Furthermore, the objective of this invention is to provide a method for inexpensively producing alloy powders capable of stably acid-leaching these components. Further, the objective of this invention is to provide a method for recovering valuable metals using this manufacturing method.

[0015] means for solving problems

[0016] This invention includes the solutions described in (1) to (11) below. It should be noted that the expression “~” in this specification includes the numerical values ​​at both ends. That is, “X~Y” has the same meaning as “X and above and Y and below”.

[0017] (1) An alloy powder comprising copper (Cu), nickel (Ni) and cobalt (Co) as constituent components, wherein the 50% cumulative diameter (D50) of the volume particle size distribution of the alloy powder is 30 μm or more and 85 μm or less, and the oxygen content of the alloy powder is 0.01% by mass or more and 1.00% by mass or less.

[0018] (2) The alloy powder as described in (1) above, wherein the 50% cumulative diameter (D50) is 35 μm or more and 55 μm or less.

[0019] (3) The alloy powder as described in (1) or (2) above, wherein the 10% cumulative diameter (D10), 50% cumulative diameter (D50) and 90% cumulative diameter (D90) in the volume particle size distribution of the alloy powder satisfy the relationship 2.50≤(D90-D10) / D50≤3.00.

[0020] (4) The alloy powder as described in any one of (1) to (3) above, wherein it comprises: copper (Cu): 24.0 to 80.0% by mass, cobalt (Co): 0.1 to 15.0% by mass, nickel (Ni): 10.0 to 50.0% by mass, iron (Fe): 0.01 to 10.0% by mass and manganese (Mn): 0.01 to 5.0% by mass, with the remainder being unavoidable impurities.

[0021] (5) A method for manufacturing alloy powder according to any one of (1) to (4) above, comprising the following steps: preparing an alloy raw material comprising copper (Cu), nickel (Ni) and cobalt (Co) as constituent components; heating and melting the alloy raw material to form an alloy melt; and cooling the alloy melt by spraying water onto the falling alloy melt in a chamber of an atomizing device to form alloy powder, wherein in the step of forming alloy powder, the pressure of the sprayed water is set to 6 MPa or more and 20 MPa or less, and the mass ratio (specific water ratio) of the amount of water sprayed relative to the amount of the falling alloy melt is set to 5.0 times or more and 7.0 times or less.

[0022] (6) The method as described in (5) above, wherein in the process of forming alloy powder, the falling rate of the alloy melt is set to more than 10 kg / min and less than 75 kg / min.

[0023] (7) The method as described in (5) or (6) above, wherein in the process of forming alloy powder, the temperature of the sprayed water is set to above 2°C and below 35°C.

[0024] (8) The method as described in any one of (5) to (7) above, wherein, in the process of forming the alloy melt, the temperature of the alloy melt is set to 1430°C or higher and 1590°C or lower.

[0025] (9) The method as described in any one of (5) to (8) above, wherein the alloy raw material is a raw material derived from waste lithium-ion batteries.

[0026] (10) A method for manufacturing alloy powder according to any one of (1) to (4) above, comprising the following steps: a step of preparing waste lithium-ion batteries as raw materials; a step of heating and melting the raw materials to form slag and an alloy containing copper (Cu), nickel (Ni) and cobalt (Co); a step of separating the slag and recovering the alloy as alloy raw materials; a step of heating and melting the alloy raw materials to form alloy melt; and a step of causing the alloy melt to fall in the chamber of an atomizing device, spraying water onto the falling alloy melt, thereby cooling it to form alloy powder, wherein in the step of forming alloy powder, the pressure of the sprayed water is set to 6 MPa or more and 20 MPa or less, and the mass ratio (specific water ratio) of the amount of water sprayed relative to the amount of the falling alloy melt is set to 5.0 times or more and 7.0 times or less.

[0027] (11) A method for recovering valuable metals (Ni, Co, Cu), comprising: a step of manufacturing alloy powder by any one of the methods (5) to (10) above; and a step of subjecting the manufactured alloy powder to an acid solvent-based leaching treatment, selectively dissolving nickel (Ni) and cobalt (Co) from the alloy powder in the acid solvent, thereby separating copper (Cu).

[0028] The effects of the invention

[0029] According to the present invention, alloy powders are provided that allow nickel and cobalt to be readily dissolved in acid and that enable stable acid leaching of these components. Furthermore, according to the present invention, a method for manufacturing alloy powders capable of stably acid leaching these components is provided at low cost. Further, according to the present invention, a method for recovering valuable metals using the aforementioned manufacturing method is provided. Attached Figure Description

[0030] Figure 1 This is a schematic diagram showing the production of alloy powder using water atomization.

[0031] Figure 2 An example of a process diagram showing the manufacturing process of alloy powder. Detailed Implementation

[0032] Specific embodiments of the present invention (hereinafter referred to as "this embodiment") will be described below. It should be noted that the present invention is not limited to the following embodiments, and various modifications can be made without changing the spirit of the present invention.

[0033] [Alloy powder]

[0034] The alloy powder of this embodiment contains copper (Cu), nickel (Ni) and cobalt (Co) as constituent components, and the 50% cumulative diameter (D50) in the volume particle size distribution is 30 μm or more and 85 μm or less, and the oxygen content is 0.01% by mass or more and 1.00% by mass or less.

[0035] The alloy powder contains copper, nickel, and cobalt as constituent components. Here, "containing as constituent components" means containing copper, nickel, and cobalt as the main components, and does not exclude the presence of other components or unavoidable impurities. It should be noted that unavoidable impurities are components that are unavoidably mixed in from the raw materials or manufacturing equipment, and their content is typically below 1000 ppm (0.1% by mass).

[0036] There are no particular limitations on the raw materials for the alloy powder. Raw materials can be manufactured by melting and pulverizing metallic copper, metallic nickel, and metallic cobalt. Alternatively, raw materials can be manufactured by reducing and pulverizing oxides such as copper oxide. Among these, alloy powder manufactured using waste lithium-ion batteries as raw material is preferred. This allows for the efficient recovery of valuable metals (Cu, Ni, Co) contained in waste lithium-ion batteries.

[0037] There are no particular limitations on the composition of the alloy powder. That is, it is acceptable as long as it contains copper, nickel, and cobalt in amounts greater than the unavoidable impurities (1000 ppm). The alloy powder may consist of only copper, nickel, and cobalt, or it may contain other components. For example, alloy powder made from waste lithium-ion batteries often contains iron (Fe) and manganese (Mn). Such alloy powder typically has the following composition: copper (Cu): 24.0–80.0% by mass, cobalt (Co): 0.1–15.0% by mass, nickel (Ni): 10.0–50.0% by mass, iron (Fe): 0.01–10.0% by mass, and manganese (Mn): 0.01–5.0% by mass, with the remainder being impurities.

[0038] For alloy powders, the 50% cumulative diameter (D50) in the volumetric particle size distribution is 30 μm or more and 85 μm or less. The 50% cumulative diameter (D50) is the diameter in the volumetric particle size distribution where the cumulative proportion accumulated from the smallest particle size side is exactly 50%, also known as the median particle size. If D50 is greater than 85 μm, even if acid leaching treatment is performed by immersing the alloy powder in acids such as sulfuric acid, the dissolution of nickel and cobalt will be insufficient. Therefore, the recovery rate of nickel and cobalt may be reduced. In particular, for alloy powders with D50 greater than 100 μm, most contain coarse particles with a particle size of 500 μm or more, making it difficult to acid leach nickel and cobalt from these coarse particles. More preferably, D50 is 55 μm or less. On the other hand, when D50 is less than 30 μm, separation and recovery may become difficult when separating the solution from the copper residue after acid leaching treatment. In addition, since the dissolution of nickel and cobalt proceeds too quickly, it may be difficult to perform acid leaching stably. More preferably, the D50 is 35 μm or higher.

[0039] The oxygen content of the alloy powder is 0.01% by mass or more and 1.00% by mass or less. If the oxygen content is greater than 1.00% by mass, the dissolution of nickel and cobalt will be insufficient when the alloy powder is immersed in sulfuric acid for acid leaching treatment. Therefore, the recovery rate of nickel and cobalt may be reduced. More preferably, the oxygen content is 0.60% by mass or less. From the viewpoint of facilitating acid leaching, the lower the oxygen content of the alloy powder, the better. However, even if the oxygen content is less than 0.01% by mass, acid leaching of nickel and cobalt will not proceed further. In addition, the manufacturing cost of producing alloy powder with an oxygen content of less than 0.01% by mass is high. Therefore, the oxygen content of the alloy powder is 0.01% by mass or more.

[0040] Furthermore, for alloy powder, it is preferable that the 10% cumulative diameter (D10), 50% cumulative diameter (D50), and 90% cumulative diameter (D90) in its volumetric particle size distribution satisfy the relationship 2.50 ≤ (D90 - D10) / D50 ≤ 3.00. Here, "(D90 - D10) / D50" is an indicator of particle size distribution deviation (width), and the smaller the value, the sharper the particle size distribution. When (D90 - D10) / D50 is greater than 3.00, the particle size distribution deviation becomes larger. Therefore, the alloy powder contains coarse particles, which may make acid leaching of nickel and cobalt more difficult. From the viewpoint of facilitating acid leaching, a smaller particle size distribution deviation is preferred. However, if the particle size distribution deviation is too small, the manufacturing cost of the alloy powder may increase. Therefore, (D90 - D10) / D50 is preferably 2.50 or higher.

[0041] [Method for manufacturing alloy powder according to the first embodiment]

[0042] The method for manufacturing alloy powder according to the first embodiment includes the following steps: a step of preparing an alloy raw material comprising copper (Cu), nickel (Ni), and cobalt (Co) as constituent components (alloy raw material preparation step); a step of heating and melting the prepared alloy raw material to form an alloy molten liquid (molten liquidification step); and a step of causing the obtained alloy molten liquid to fall into the chamber of an atomizing device, spraying water onto the falling alloy molten liquid, thereby cooling it to form alloy powder (alloy powder production step). Furthermore, in the alloy powder formation step (alloy powder production step), the pressure of the sprayed water is set to 6 MPa or more and 20 MPa or less, and the mass ratio (specific water ratio) of the water spray volume to the falling volume of the alloy molten liquid is set to 5.0 times or more and 7.0 times or less. Details of each step are described below.

[0043] <Alloy Raw Material Preparation Process>

[0044] In the alloy raw material preparation process, an alloy raw material containing copper (Cu), nickel (Ni), and cobalt (Co) as constituent components is prepared. There are no particular limitations as long as the alloy raw material contains copper, nickel, and cobalt in a metallic state. It can contain copper, nickel, and cobalt in the form of a mixture of elemental metals, or it can contain copper, nickel, and cobalt in the form of an alloy. It can be in any form as long as it becomes an alloy melt through the subsequent melting process.

[0045] Preferably, the alloy raw material is derived from spent lithium-ion batteries. It is required that spent lithium-ion batteries be reused as a resource. Furthermore, spent lithium-ion batteries contain a large amount of valuable metals (Cu, Ni, Co). Therefore, by using raw materials from spent lithium-ion batteries as the alloy raw material, valuable metals can be separated and recovered efficiently and at low cost. Alternatively, recycled materials other than spent lithium-ion batteries can also be used. For example, electronic components and electronic devices contain a large amount of valuable metals (Cu, Ni, Co). Raw materials from such electronic components and electronic devices can also be used as the alloy raw material.

[0046] <Melting Process>

[0047] In the molten metallization process, the prepared alloy raw materials are heated and melted to form an alloy melt. Specifically, the alloy raw materials are placed into a crucible furnace and heated inside the furnace to form a fluid melt. From the viewpoint of obtaining the desired alloy powder in the alloy powder production process described later, the heating temperature is preferably 1430°C or higher and 1590°C or lower.

[0048] <Alloy Powder Production Process>

[0049] In the alloy powder production process, alloy powder is produced by water atomization. That is, the obtained molten alloy falls into the chamber of an atomization device, and water is sprayed onto the falling molten alloy to cool it and form alloy powder. Figure 1 An example of the configuration of the atomizing device used in this process is shown. The atomizing device has: a tundish (4) with a nozzle (3) at the bottom, a chamber (6), a gas discharge structure (9), a high-pressure water nozzle (11), a water supply pump (15), and a cooler (16).

[0050] The molten metal (1) heated in the crucible furnace (2) is injected into the tundish (4) of the atomizing device. At this time, the molten metal supply is adjusted to keep the molten metal level (5) constant. The molten metal injected into the tundish (4) falls into the chamber (6) through the nozzle (3). Since the molten metal level (5) is constant, the amount of molten metal falling per unit time from the nozzle (the amount of alloy molten metal falling) is constant according to the nozzle diameter. In addition, the chamber (6) is configured to maintain its internal pressure above atmospheric pressure with an inactive gas (7) such as nitrogen to prevent air intrusion. Furthermore, a gas exhaust structure (9) is provided in the chamber (6) so that gases (8) such as hydrogen can be discharged from the chamber (6) when no air flows in. High-pressure water (12) is sprayed onto the alloy molten metal (10) falling in the chamber (6) by a high-pressure water nozzle (11). The angle between the sprayed water and the falling alloy molten metal is adjusted to maximize the yield of the obtained alloy powder. Specifically, an even number of high-pressure water nozzles (11) are arranged relative to each other, with the falling molten alloy (10) as the central axis (e.g., 2, 4, 6). Furthermore, the direction of the high-pressure water nozzles (11) is adjusted so that the relative angle (apex angle) of the water sprayed from the opposing high-pressure water nozzles (11) reaches 30° to 50°. That is, the water spray angle (apex angle) relative to the falling molten alloy (10) is 15° to 25°.

[0051] In the process of forming the alloy powder, the pressure of the sprayed water is set to between 6 MPa and 20 MPa. When the pressure is less than 6 MPa, the resulting alloy powder has an excessively large particle size. Therefore, the recovery rate of nickel and cobalt may decrease when acid leaching this alloy powder. On the other hand, when the pressure is greater than 20 MPa, the alloy powder is too fine. Therefore, stable acid leaching may be difficult to achieve, and the separation and recovery of the solution from the dissolved residue (copper residue) will decrease. Furthermore, increasing the pressure requires the use of expensive pumps, increasing the manufacturing cost of the alloy powder. Considering various factors such as commercial viability, the water pressure is set to 20 MPa or less.

[0052] The mass ratio of water spray volume to the amount of molten alloy falling (specific water ratio) is set to be between 5.0 and 7.0. Here, the falling volume is the average falling volume per unit time, and the spray volume is the average spray volume per unit time. That is, it is the average value of the falling volume and spray volume as they change over time. When the specific water ratio is less than 5.0, the cooling of the molten alloy becomes insufficient, resulting in alloy powder with an excessively large particle size. On the other hand, when the specific water ratio is greater than 7.0, the cooling of the molten alloy proceeds too quickly, resulting in alloy powder that is too fine.

[0053] Preferably, the flow rate of the molten alloy is set to be between 10 kg / min and 75 kg / min. If the flow rate is too low, fine powder with a particle size smaller than 10 μm is easily generated, making it difficult to stably leach the alloy powder during acid leaching and potentially reducing separation and recovery. Furthermore, the reduced alloy powder productivity becomes a problem from a manufacturing cost perspective. On the other hand, an excessive flow rate requires increasing the pump's water supply pressure or the number of pumps, increasing manufacturing costs. By setting the flow rate of the molten alloy within the aforementioned range, the hourly processing capacity of the molten alloy can be between 600 kg and 4500 kg. As a result, the manufacturing of alloy powder can be scaled up to the cost of a smelting operation.

[0054] Furthermore, it is preferable to set the temperature of the sprayed water to above 2°C and below 35°C. If the water temperature is too low, it may freeze in the piping when the equipment is stopped, leading to leaks and other problems. On the other hand, if the water temperature is too high, the particle size of the resulting alloy powder tends to increase. Therefore, this may worsen acid leaching performance or cause problems in production management during acid leaching. Moreover, the water temperature can be controlled by adjusting the set temperature of the cooler.

[0055] Furthermore, it is preferable that the temperature of the alloy melt is above 1430°C and below 1590°C. If the melt temperature is too low, the flow of melt from the tundish nozzle becomes poor, potentially causing nozzle blockage. Additionally, the crushing process using high-pressure water will be less efficient, and the alloy powder may become coarse. On the other hand, if the melt temperature is too high, heating energy is wasted, and the lifespan of the refractory material during heating may be shortened. Furthermore, due to the increased temperature of the circulating high-pressure water, the cooling capacity of the cooler needs to be increased, leading to increased costs.

[0056] As described above, by manufacturing alloy powder through water atomization and then adjusting the atomization conditions, copper-nickel-cobalt alloy powder can be manufactured commercially and inexpensively. This alloy powder exhibits a 50% cumulative diameter (D50) of 30 μm or more and 85 μm or less, and an oxygen content of 0.01% by mass or more and 1.00% by mass or less. Furthermore, the alloy powder demonstrates excellent acid leaching and separation / recovery properties. Therefore, by subjecting this alloy powder to acid leaching treatment using sulfuric acid, copper can be precipitated as copper sulfide, and nickel and cobalt can be separated and recovered in solution form. Thus, the separation and recovery of valuable metals (Cu, Ni, Co) can be achieved with high efficiency and low cost.

[0057] Furthermore, gas atomization, which involves blowing high-pressure gas into the molten alloy for cooling, is considered as an alternative to water atomization. Alloy powder produced by gas atomization has a lower oxygen content and excellent acid leaching properties. However, gas atomization requires manufacturing the alloy powder in a vacuum chamber, resulting in low productivity. Therefore, water atomization is employed in this embodiment. The following difference was observed in the manufactured alloy powder: the alloy powder produced by gas atomization is nearly spherical, while the alloy powder produced by water atomization exhibits many irregularly shaped particles.

[0058] [Method for manufacturing alloy powder according to the second embodiment]

[0059] The method for manufacturing alloy powder according to the second embodiment includes the following steps: a step of preparing waste lithium-ion batteries as raw materials (raw material preparation step); a step of heating and melting the prepared raw materials to form slag and an alloy containing copper (Cu), nickel (Ni), and cobalt (Co) (melting step); a step of separating the slag and recovering the alloy as alloy raw material (slag separation step); a step of heating and melting the recovered alloy raw material to form an alloy melt (molten alloying step); and a step of causing the alloy melt to fall in the chamber of an atomizing device, spraying water onto the falling alloy melt, thereby cooling it to form alloy powder (alloy powder manufacturing step). Furthermore, in the alloy powder forming step (alloy powder manufacturing step), the pressure of the sprayed water is set to 6 MPa or more and 20 MPa or less, and the mass ratio (specific water ratio) of the water spray volume to the falling volume of the alloy melt is set to 5.0 times or more and 7.0 times or less. Figure 2 An example of a process diagram for this embodiment is shown. Details of each process are described below.

[0060] <Raw Material Preparation Process - Waste Battery Pre-treatment Process>

[0061] In the raw material preparation process, the waste batteries are first pre-treated. The waste battery pre-treatment process (S1) aims to prevent explosions of waste lithium-ion batteries, ensure their harmlessness, and remove the outer packaging cans. Since lithium-ion batteries are closed systems, they contain electrolytes and other substances. Therefore, if they are crushed in their original state, there is a risk of explosion. Thus, it is preferable to perform discharge treatment and electrolyte removal treatment through certain methods. Furthermore, the outer packaging cans are mostly made of metals such as aluminum (Al) and iron (Fe), making them relatively easy to recycle directly. As described above, by removing the electrolyte and outer packaging cans in the waste battery pre-treatment process (S1), safety and the recovery rate of valuable metals (Cu, Ni, Co) can be improved.

[0062] There are no particular limitations on the specific methods for pre-treatment of waste batteries. For example, one method could be to physically open the waste battery with a needle-like tip to remove the electrolyte. Another method could be to heat the waste lithium-ion battery and burn off the electrolyte to render it harmless.

[0063] <Raw Material Preparation Process - Crushing Process>

[0064] In the crushing step (S2), the contents of the waste lithium-ion batteries are crushed to form crushed material. This crushed material becomes the raw material for melting. This step aims to improve the reaction efficiency in the dry smelting process. By improving reaction efficiency, the recovery rate of valuable metals (Cu, Ni, Co) can be increased. There are no particular limitations on the specific crushing method. Conventionally known pulverizers such as shredder mixers can be used for crushing.

[0065] Furthermore, when recovering aluminum (Al) and iron (Fe) contained in the outer packaging cans of spent lithium-ion batteries, the crushed material can be screened using a vibrating screen after crushing. Aluminum (Al) is easily pulverized through light crushing, thus enabling its efficient recovery. Additionally, iron (Fe) contained in the outer packaging cans can be recovered using magnetic screening.

[0066] <Oxidative roasting process>

[0067] If necessary, a process can be set up before the melting process to oxidize and roast the crushed waste lithium-ion batteries (crushed material) to form an oxidized roasted product (oxidation roasting process; S3). In the oxidation roasting process, the carbon content of the waste lithium-ion batteries is reduced. By setting up this process, even if the waste lithium-ion batteries contain excessive carbon, the carbon can be oxidized and removed, thereby promoting the alloying of valuable metals in the subsequent melting process. That is, in the melting process, valuable metals are reduced to become localized molten particles, and carbon sometimes becomes a physical obstacle when the molten particles (valuable metals) agglomerate. Therefore, if an oxidation roasting process is not set up for oxidation roasting treatment, carbon will hinder the agglomeration and integration of molten particles and the resulting separation of the alloy (metal) from the slag, sometimes resulting in a decrease in the recovery rate of valuable metals. In contrast, by removing carbon through pre-oxidation roasting treatment and agglomerating the molten particles (valuable metals) in the melting process, the recovery rate of valuable metals can be further improved. Furthermore, since phosphorus (P) is a relatively easily reduced impurity element, if excess carbon is present, phosphorus may be reduced and incorporated into the alloy along with valuable metals. This can be prevented by removing excess carbon beforehand. It should be noted that the carbon content of the oxidized roasted product is preferably less than 1% by mass.

[0068] Furthermore, by incorporating an oxidation roasting process, oxidation deviations can be suppressed. In this process, it is preferable to treat the waste lithium-ion batteries at a degree of oxidation sufficient to oxidize low-value metals (such as Al). On the other hand, the degree of oxidation can be easily controlled by adjusting the processing temperature, time, and / or environment of the oxidation roasting. Oxidation roasting allows for more precise control of the degree of oxidation, thus suppressing oxidation deviations.

[0069] The degree of oxidation is adjusted as follows. Aluminum (Al), lithium (Li), carbon (C), manganese (Mn), phosphorus (P), iron (Fe), cobalt (Co), nickel (Ni), and copper (Cu) are generally oxidized in the order Al > Li > C > Mn > P > Fe > Co > Ni > Cu. In the oxidative roasting process, oxidation continues until all aluminum (Al) is oxidized. Oxidation can be promoted until some iron (Fe) is oxidized, but the degree of oxidation is limited to the extent that cobalt (Co) is not oxidized and is distributed into the slag.

[0070] The preferred oxidative roasting process is carried out in the presence of an oxidant. This allows for the efficient removal of carbon (C) as an impurity and the oxidation of aluminum (Al). The oxidant is not particularly limited, but from the viewpoint of ease of processing, an oxygen-containing gas (air, pure oxygen, oxygen-enriched gas, etc.) is preferred. Furthermore, the amount of oxidant introduced is preferably, for example, about 1.2 times the stoichiometric amount required for the oxidation of each substance targeted for the oxidation treatment.

[0071] The heating temperature in the oxidative roasting is preferably 600°C or higher, more preferably 700°C or higher. This further improves the carbon oxidation efficiency and shortens the heating time. Alternatively, the heating temperature is preferably 900°C or lower. This helps to reduce thermal energy costs and improve the efficiency of the oxidative roasting.

[0072] The oxidative roasting process can be carried out using a known roasting furnace. Furthermore, it is preferable to use a different furnace (preparatory furnace) than the melting furnace used in the subsequent melting process, and to perform the roasting within this preparatory furnace. As an oxidative roasting furnace, any type of furnace can be used, as long as it can simultaneously roast the raw material and supply an oxidant (oxygen, etc.) and carry out the oxidation process inside. Examples include conventionally known rotary kilns and hearth furnaces.

[0073] <Melting Process>

[0074] In the melting process (reduction melting process; S4), the raw material (crushed or oxidized roasted waste lithium-ion batteries) is heated and melted to form an alloy (metal) containing copper (Cu), nickel (Ni), and cobalt (Co), and a slag formed above the alloy due to its density difference. Specifically, the raw material is heated and melted to form a melt. This melt contains the alloy and slag in a molten state. Next, the resulting melt is formed into a molten material. This molten material contains the alloy and slag in a solidified state. The alloy mainly contains valuable metals. Therefore, valuable metals and other components can be separated as the alloy and slag, respectively. This is because metals with low added value (such as Al) have a high oxygen affinity, while valuable metals have a low oxygen affinity. For example, aluminum (Al), lithium (Li), carbon (C), manganese (Mn), phosphorus (P), iron (Fe), cobalt (Co), nickel (Ni), and copper (Cu) are generally oxidized in the order Al > Li > C > Mn > P > Fe > Co > Ni > Cu. That is, aluminum (Al) is the easiest to oxidize, while copper (Cu) is the most difficult. Therefore, low-value metals (Al, etc.) are easily oxidized to become slag, while valuable metals (Cu, Ni, Co) are reduced to become alloys. As described above, it is possible to separate low-value metals and valuable metals into slag and alloys.

[0075] The oxygen partial pressure can also be controlled during the melting of the raw materials. Oxygen partial pressure can be controlled by known methods. For example, a reducing agent or an oxidizing agent can be introduced into the raw materials or their melt. As a reducing agent, materials with a high carbon content (graphite powder, graphite granules, coal, coke, etc.) and carbon monoxide can be used. Alternatively, components of the raw materials with a high carbon content can also be used as reducing agents. As an oxidizing agent, oxidizing gases (air, oxygen, etc.) and materials with a low carbon content can be used. Alternatively, components of the raw materials with a low carbon content can also be used as oxidizing agents.

[0076] The introduction of reducing agents and oxidizing agents can be carried out using any known method. If the reducing agent or oxidizing agent is a solid, it can be added to the raw material or melt. If the reducing agent or oxidizing agent is a gas, it can be introduced through an inlet such as a lance in the melting furnace. There are no restrictions on the timing of introducing the reducing agent or oxidizing agent. The reducing agent and oxidizing agent can be introduced simultaneously when the raw material is added to the melting furnace, or they can be introduced when the raw material has melted into a melt.

[0077] In the heating and melting process, a flux can be introduced (added). By adding a flux, the melting temperature can be lowered, energy costs can be reduced, and phosphorus (P) removal can be further promoted. As a flux, a flux containing elements that form basic oxides is preferred, which can incorporate impurity elements and have a low melting point. Since phosphorus oxidizes into acidic oxides, the more basic the slag formed by heating and melting, the easier it is to incorporate phosphorus into the slag for removal. More preferably, a calcium compound that is inexpensive and stable at room temperature is included. Examples of calcium compounds include, for example, calcium oxide (CaO) and calcium carbonate (CaCO3).

[0078] There is no particular limitation on the heating temperature for melting the raw materials, but it is preferably 1400°C or higher and 1600°C or lower, more preferably 1450°C or higher and 1550°C or lower. By setting the heating temperature to 1400°C or higher, the valuable metals (Cu, Co, Ni) are fully melted, forming an alloy in a state of increased fluidity. Therefore, the alloy and slag can be separated efficiently in the slag separation process described later. In addition, by setting the heating temperature to 1450°C or higher, the fluidity of the alloy becomes very good, and the separation efficiency of impurities and valuable metals is further improved. On the other hand, when the heating temperature is higher than 1600°C, heat energy is wasted, and the consumption of refractory materials such as crucibles and furnace walls becomes severe, which may reduce productivity.

[0079] <Slag Separation Process>

[0080] In the slag separation process, slag is separated from the molten material obtained in the melting process, and the alloy containing valuable metals, which is used as an alloying raw material, is recovered. The slag and the alloy have different specific gravities. Since the slag, which has a lower specific gravity than the alloy, concentrates in the upper part of the alloy, it can be easily separated and recovered by gravity separation.

[0081] <Melting Process>

[0082] In the molten alloying process (S5), the recovered alloy is used as a raw material and heated to melt it to form an alloy melt. The details of this process are as described in the first embodiment.

[0083] <Alloy Powder Production Process>

[0084] In the alloy powder production step (S6), the obtained molten alloy is allowed to fall into the chamber of an atomizing device, and water is sprayed onto the falling molten alloy to cool it and form alloy powder. The details of this step are as described in the first embodiment.

[0085] Methods for recycling valuable metals

[0086] The method for recovering valuable metals (Cu, Ni, Co) according to this embodiment includes: a step of manufacturing alloy powder (alloy powder manufacturing step); and a step of performing an acid solvent-based leaching treatment on the manufactured alloy powder to selectively dissolve nickel (Ni) and cobalt (Co) from the alloy powder in the acid solvent, thereby separating copper (Cu) (valuable metal separation step). It should be noted that the valuable metal being recovered is at least one metal or alloy selected from the group consisting of copper (Cu), nickel (Ni), cobalt (Co), and combinations thereof.

[0087] <Alloy Powder Manufacturing Process>

[0088] In the alloy powder manufacturing process, the alloy powder is manufactured by the method described in the first or second embodiment above.

[0089] <Metal Recycling Process>

[0090] In the valuable metal recovery process, the manufactured alloy powder is subjected to an acid-based leaching treatment, selectively dissolving nickel (Ni) and cobalt (Co) from the alloy powder in the acid solvent. Copper (Cu) is thus separated. Known acid solutions used in valuable metal recovery can be used as the acid solvent. Sulfuric acid is an example of such an acid solution. When the alloy powder is leached in sulfuric acid, the nickel and cobalt in the alloy powder dissolve in the sulfuric acid solution, becoming nickel sulfate and cobalt sulfate in the solution. On the other hand, the copper in the alloy powder becomes copper sulfate, which has low solubility, and precipitates as a residue. Therefore, the copper component (copper sulfate) as a precipitate can be separated and recovered from the solution containing nickel and cobalt.

[0091] The alloy powder of this embodiment has excellent acid leaching and separation / recovery properties. Therefore, according to the valuable metal recovery method of this embodiment using the alloy powder, valuable metals (Cu, Ni, Co) can be separated and recovered with high efficiency and low cost.

[0092] Example

[0093] The invention is described in more detail using the following examples and comparative examples, but the invention is not limited to the following examples.

[0094] (1) Preparation of alloy powder

[0095] [Example 1]

[0096] In Example 1, waste lithium-ion batteries are used as raw materials to produce alloy powder via water atomization. Specifically, semi-finished waste from lithium-ion battery factories circulating in the waste battery market or used waste batteries that have been rendered harmless are mixed as a sample (raw material). Next, the sample is processed through a melting process (S4) to obtain the alloy raw material, and then alloy powder production experiments are conducted through a liquefaction process (S5) and an alloy powder production process (S6). Table 1 shows the manufacturing conditions for the alloy powder.

[0097] In the molten alloying process (S5), the temperature of the molten alloy inside the furnace is adjusted by the output of the induction furnace at a frequency of 400 Hz. In the alloy powder preparation process (S6), the induction furnace is tilted to allow the molten alloy to flow into an alumina tundish equipped with zirconia nozzles with a diameter of 4-7 mm installed at the bottom. By keeping the molten alloy level in the tundish constant, the output rate per unit time is kept constant, and the output rate is adjusted by changing the orifice diameter of the zirconia nozzles. Furthermore, the water pressure and flow rate are adjusted by regulating the output of the high-pressure pump and the opening and closing of the valves, and the temperature of the sprayed water is adjusted by regulating the cooling capacity of the cooler.

[0098] Here, to ensure that the temperature of the molten alloy inside the induction furnace is as similar as possible to the temperature of the molten alloy exiting from the tundish nozzle, the interior of the empty tundish is preheated to over 1000°C using an LPG burner. This operation eliminates the temperature difference between the molten alloy in contact with the high-pressure water and the temperature inside the induction furnace for a short period after the molten alloy exits.

[0099] [Example 2 and Example 3]

[0100] In Examples 2 and 3, the manufacturing conditions of the alloy powder were changed as shown in Table 1. Otherwise, the alloy powder was prepared in the same manner as in Example 1.

[0101] [Example 4~Example 7]

[0102] In Examples 4 through 7, the proportions of waste lithium-ion batteries were adjusted to change the composition of the alloy powder as shown in Table 3. Furthermore, the manufacturing conditions of the alloy powder were changed as shown in Table 1. Otherwise, the alloy powder was prepared in the same manner as in Example 1.

[0103] [Example 8 (Comparative Example)]

[0104] In Example 8, waste lithium-ion batteries are used as raw materials to produce alloy powder via gas atomization. Specifically, in the melting process (S5), the alloy is melted in an argon atmosphere using an induction furnace with a vacuum chamber. Then, in the alloy powder production process (S6), the molten alloy is powdered by argon atomization to produce alloy powder.

[0105] [Example 9 (Comparative Example)]

[0106] In Example 9, the manufacturing conditions of the alloy powder were changed as shown in Table 1. Specifically, the water absorption pressure during water atomization was reduced to 3.1 MPa. Otherwise, the alloy powder was prepared in the same manner as in Example 1.

[0107] [Example 10 (Comparative Example)]

[0108] In Example 10, the alloy powder prepared in Example 5 was oxidized in the atmosphere.

[0109] (2) Evaluation

[0110] The alloy powders obtained in Examples 1 to 10 are evaluated for various properties as follows.

[0111] <Particle Size Distribution>

[0112] The particle size distribution of the alloy powder was evaluated by dry sieving. Furthermore, the 10% cumulative diameter (D10), 50% cumulative diameter (median particle size; D50), and 90% cumulative diameter (D90) were obtained from the obtained particle size distribution, and (D90-D10) / D50 was calculated.

[0113] <Composition>

[0114] The composition of the alloy powder was determined using an ICP analyzer.

[0115] <Oxygen content>

[0116] The oxygen content of alloy powder was determined by infrared absorption method.

[0117] <Acid leaching properties (recovery rate)>

[0118] The acid leaching property (recovery rate) of the alloy powder is determined by dividing the mass of the target element in the filtrate by the mass of the target element in the alloy powder.

[0119] Based on the evaluation results of acid leaching properties, the alloy powder was evaluated according to the following criteria.

[0120] ◎: Through 6 hours of acid leaching, the recovery rate of nickel and cobalt is over 98%;

[0121] 〇: Through 9 hours of acid leaching, the recovery rate of nickel and cobalt is over 96%;

[0122] ×: The recovery rate of nickel and cobalt is less than 96% after 9 hours of acid leaching.

[0123] <Cost>

[0124] From a manufacturing cost perspective, the alloy powder was evaluated according to the following criteria.

[0125] 〇: The manufacturing equipment is inexpensive and has high productivity;

[0126] ×: The manufacturing equipment is expensive and has low productivity.

[0127] <Overall Evaluation>

[0128] Based on a comprehensive assessment of acid leaching properties and cost, the alloy powder was evaluated according to the following criteria.

[0129] ◎: The evaluation result for acid leaching performance is "◎", and the evaluation result for cost is "〇";

[0130] 〇: The evaluation results for acid leaching and cost are both "〇";

[0131] ×: The evaluation results for acid leaching properties and cost are both "×".

[0132] (3) Results

[0133] Based on Examples 1 to 10, the evaluation results are summarized in Table 2.

[0134] The alloy powders of Examples 1 and 2 have an oxygen content of ≥0.01% by mass and ≤1% by mass, and a particle size D50 of ≥60μm and ≤85μm. They exhibit good acid leaching properties in sulfuric acid, with nickel and cobalt recoveries exceeding 96% within 9 hours. Therefore, the overall evaluation is "0".

[0135] The alloy powders in Examples 3 to 7 have an oxygen content of 0.01% by mass or more and 1% by mass or less, and a particle size D50 of 35 μm or more and 55 μm or less. They exhibit excellent acid leaching properties in sulfuric acid, with nickel and cobalt recoveries exceeding 98% within 6 hours. Therefore, their overall evaluation is "◎".

[0136] The alloy powders of Examples 1 to 7, prepared by water atomization, contain a large number of irregularly shaped particles, and the (D90-D10) / D50 ratio of the alloy powder is 2.58 to 2.93.

[0137] The alloy powder in Example 8 has a low oxygen content of 0.002% by mass. Furthermore, by adjusting the gas flow rate, the particle size D50 of the alloy powder was controlled to 45 μm. Therefore, it exhibits good acid leaching properties, with nickel and cobalt recoveries of approximately 98.5% within 6 hours.

[0138] However, air atomization requires a vacuum chamber. Furthermore, due to its low productivity, multiple units must be installed in air atomization to ensure the same throughput as water atomization. Because of these issues related to initial investment and space, from a commercial perspective, this is judged as "×".

[0139] Furthermore, the alloy powder of Example 8, produced by gas atomization, contains nearly spherical particles. Additionally, the (D90-D10) / D50 ratio of the alloy powder is 2.38.

[0140] The alloy powder in Example 9 has a low oxygen content of 0.14% by mass. However, its particle size D50 is relatively large, at 110 μm. Therefore, its acid leaching performance is poor, and the recovery rates of nickel and cobalt are low, less than 96% after 9 hours. Therefore, from a commercial perspective, it is judged as "×".

[0141] The alloy powder in Example 10 has an oxygen content as high as 2.2% by mass. Therefore, its acid leaching properties are poor, and the recovery rates of nickel and cobalt are low, less than 96% after 9 hours. Therefore, from a commercial point of view, it is judged as "×".

[0142] Table 1 Manufacturing conditions of alloy powder

[0143]

[0144] Note 1) "*" indicates that it is a comparative example.

[0145] Note 2) "-" indicates that no water supply has been provided.

[0146] Table 2 Evaluation Results of Alloy Powder

[0147] D50(μm) Oxygen content (mass%) cost Recovery rate judge Example 1 60～85 0.14 〇 〇 〇 Example 2 60～85 0.50 〇 〇 〇 Example 3 35～55 0.15 〇 ◎ ◎ Example 4 35～55 0.54 〇 ◎ ◎ Example 5 35～55 0.15 〇 ◎ ◎ Example 6 35～55 0.20 〇 ◎ ◎ Example 7 35～55 0.18 〇 ◎ ◎ Example 8* 45 0.002 × ◎ × Example 9* 110 0.14 〇 × × Example 10* 35～55 2.20 〇 × ×

[0148] Note 1) "*" indicates that it is a comparative example.

[0149] Table 3. Quantitative Chemical Analysis Results of Alloy Powder

[0150] Ni Cu Co Fe Mn other Other detection elements Example 1 11.3 75.4 11.4 1.5 0.4 <0.01 - Example 2 11.3 75.4 11.4 1.5 0.4 <0.01 - Example 3 11.3 75.4 11.4 1.5 0.4 <0.01 - Example 4 23.9 74.3 0.4 1.26 0.07 0.1 P, W, Cr, Zn, Si Example 5 12.2 73.7 12.5 1.5 0.1 <0.01 - Example 6 45.8 43.9 5.1 3.1 1.9 0.2 P, W, Cr, Zn, Si Example 7 33.6 61.4 2.9 0.96 0.097 0.1 P, W, Cr, Zn, Si Example 8* 12.1 73.7 12.5 1.6 0.1 <0.01 - Example 9* 11.3 75.4 11.4 1.5 0.4 <0.01 - Example 10* 12.2 73.7 12.5 1.5 0.1 <0.01 -

[0151] Note 1) "*" indicates that it is a comparative example.

[0152] Note 2) "-" indicates that it was not detected.

[0153] Explanation of reference numerals in the attached figures

[0154] 1: Copper, nickel, cobalt;

[0155] 2: Crucible furnace;

[0156] 3: Nozzle;

[0157] 4: Intermediate package;

[0158] 5: Height of the molten metal surface;

[0159] 6: Chamber;

[0160] 7: Inactive gases such as nitrogen;

[0161] 8: Filled with gas;

[0162] 9: Gas exhaust structure;

[0163] 10: Falling molten alloy;

[0164] 11: High-pressure water nozzle;

[0165] 12: High-pressure water;

[0166] 13: Aqueous phase;

[0167] 14: Alloy granules;

[0168] 15: Water supply pump;

[0169] 16: Cooler.

Claims

1. An alloy powder, wherein, It contains copper (Cu), nickel (Ni), and cobalt (Co) as constituent elements. The cumulative diameter D50 of 50% of the volumetric particle size distribution of the alloy powder is greater than 35 μm and less than 55 μm. The 10% cumulative diameter D10, 50% cumulative diameter D50, and 90% cumulative diameter D90 in the volumetric particle size distribution of the alloy powder satisfy the relationship 2.50 ≤ (D90 - D10) / D50 ≤ 3.

00. The oxygen content of the alloy powder is above 0.01% by mass and below 0.60% by mass.

2. The alloy powder as described in claim 1, wherein, The alloy powder comprises: copper Cu: 24.0–80.0% by mass, cobalt Co: 0.1–15.0% by mass, nickel Ni: 10.0–50.0% by mass, iron Fe: 0.01–10.0% by mass, and manganese Mn: 0.01–5.0% by mass, with the remainder being unavoidable impurities.

3. A method for manufacturing the alloy powder according to claim 1 or 2, wherein, The process includes the following steps: The process of preparing alloy raw materials containing copper Cu, nickel Ni and cobalt Co as constituent components; The process of heating and melting the alloy raw materials to form an alloy melt; and The process involves causing the molten alloy to fall within the chamber of an atomizing device, spraying water onto the falling molten alloy, and thereby cooling it to form alloy powder. In the process of forming alloy powder, the pressure of the sprayed water is set to 6 MPa or more and 20 MPa or less, and the mass ratio of the sprayed water to the amount of molten alloy falling, i.e., the water ratio, is set to 5.0 times or more and 7.0 times or less. In the process of forming alloy powder, the falling rate of the alloy molten liquid is set to be more than 10 kg / min and less than 75 kg / min.

4. The method of claim 3, wherein, In the process of forming alloy powder, the temperature of the sprayed water is set to be above 2°C and below 35°C.

5. The method as described in claim 3 or 4, wherein, In the process of forming the alloy melt, the temperature of the alloy melt is set to above 1430°C and below 1590°C.

6. The method as described in claim 3 or 4, wherein, The alloy raw material is derived from waste lithium-ion batteries.

7. A method for manufacturing the alloy powder according to claim 1 or 2, wherein, The process includes the following steps: The process of preparing waste lithium-ion batteries as raw materials; The process of heating and melting the raw materials to form slag and an alloy containing copper (Cu), nickel (Ni), and cobalt (Co); The process of separating and recovering the slag as an alloy raw material; The process of heating and melting the alloy raw materials to form an alloy melt; and The process involves causing the molten alloy to fall within the chamber of an atomizing device, spraying water onto the falling molten alloy, and thereby cooling it to form alloy powder. In the process of forming alloy powder, the pressure of the sprayed water is set to 6 MPa or more and 20 MPa or less, and the mass ratio of the sprayed water to the amount of molten alloy falling, i.e., the water ratio, is set to 5.0 times or more and 7.0 times or less. In the process of forming alloy powder, the falling rate of the alloy molten liquid is set to be more than 10 kg / min and less than 75 kg / min.

8. A method for recovering valuable metals, wherein the valuable metals are Ni, Co, or Cu, and in the recovery method, include: The process of manufacturing alloy powder by any one of claims 3 to 7; as well as The process of performing an acid-based leaching treatment on the manufactured alloy powder to selectively dissolve nickel (Ni) and cobalt (Co) from the alloy powder in the acid solvent, thereby separating copper (Cu).

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