Alloy treatment method

Abstract

Provided is an alloy treatment method capable of selectively separating nickel and / or cobalt from an alloy containing copper and nickel and / or cobalt, such as a waste lithium ion battery. The present invention is an alloy treatment method for obtaining a solution containing nickel and / or cobalt from an alloy containing copper and nickel and / or cobalt, the method comprising: a leaching step for obtaining a leachate by subjecting the alloy to a leaching treatment with an acid in the presence of a vulcanizing agent; a reduction step in which the leachate is subjected to a reduction treatment with a reducing agent to obtain a reduced liquid; and an oxidation and neutralization step in which a solution containing nickel and / or cobalt is obtained by adding an oxidizing agent and a neutralizing agent to the reduction solution.

Description

[0001] This application is a divisional application of the application with an application date of February 10, 2021, application number 202180012962.7, and invention name “Method for treating alloys”. Technical Field

[0002] The present invention relates to a method for treating an alloy, and more particularly, to a method for treating an alloy for obtaining a solution containing nickel and / or cobalt from an alloy containing copper and nickel and / or cobalt. Background Art

[0003] Vehicles such as electric vehicles and hybrid vehicles, and electronic devices such as mobile phones, smartphones, and personal computers are equipped with lithium-ion batteries (hereinafter also referred to as "LIBs") that are lightweight and have high output.

[0004] For example, LIB has the following structure: a negative electrode material and a positive electrode material are loaded together with a separator composed of a porous resin film of polypropylene into an outer can made of metal such as aluminum and iron or plastic such as vinyl chloride, and an organic solvent containing an electrolyte such as lithium hexafluorophosphate (LiPF6) is used as an electrolyte and impregnated therein. The negative electrode material is a negative electrode material using copper foil as a negative electrode current collector and having a negative electrode active material such as graphite fixed on the surface. The positive electrode material is a positive electrode material having a positive electrode active material such as lithium nickelate and lithium cobaltate fixed on a positive electrode current collector composed of aluminum foil.

[0005] When LIBs are used in vehicles or electronic devices, they eventually become unusable due to degradation of the vehicle or electronic device or the lifespan of the LIB, becoming waste lithium-ion batteries (waste LIBs). Waste LIBs can also be generated as defective products during the initial manufacturing process.

[0006] These waste LIBs contain valuable components such as nickel, cobalt, and copper. In order to effectively utilize resources, it is also desired to recover and reuse these valuable components.

[0007] When it is desired to efficiently recover valuable components from metal devices, components, and materials, dry processing is generally used. This involves placing the metal into a furnace, melting it at high temperatures, and separating it into metal containing valuables and slag. This process has been widely used for a long time.

[0008] For example, Patent Document 1 discloses a method for recovering valuable metals using a dry process. By applying the method of Patent Document 1 to a process for recovering valuable metals from scrap LIBs, a copper alloy containing nickel and cobalt can be obtained.

[0009] While this dry treatment has the disadvantage of requiring energy to heat the furnace to high temperatures, it has the advantage of simultaneously separating various impurities. Furthermore, the slag obtained from the dry treatment is chemically stable, poses minimal environmental risks, and is easy to handle.

[0010] However, when waste LIBs are treated using a dry process, there is a problem in that a portion of valuable components, especially almost all of cobalt, is distributed into the slag, and the recovery loss of cobalt is unavoidable.

[0011] Furthermore, the metal obtained in the dry process is an alloy containing valuable components. Therefore, in order to reuse it, it is necessary to perform a purification process to separate the components from the alloy one by one and remove impurities.

[0012] Commonly used dry element separation methods involve slowly cooling a molten state from a high temperature, for example, to separate copper from lead or lead from zinc. However, in the case of waste LIBs, where copper and nickel are the primary components, copper and nickel melt uniformly across their entire composition range. Therefore, even with slow cooling, the copper and nickel simply solidify in a layered mixture, rendering them incapable of separation.

[0013] Another purification method involves using carbon monoxide (CO) gas to cause nickel to undergo a disproportionation reaction to volatilize and separate it from copper or cobalt. However, since toxic CO gas is used, there is a problem of difficulty in ensuring safety.

[0014] Another industrially used method for separating copper and nickel is the crude separation of mixed matte (sulfide). This method involves slowly cooling the copper- and nickel-containing matte produced in the smelting process, similar to the above, to separate it into copper-rich sulfide and nickel-rich sulfide. However, even with this separation method, the separation of copper and nickel remains at a crude level, and obtaining high-purity nickel or copper requires additional treatment such as electrolytic purification.

[0015] Separation methods using chlorides and utilizing vapor pressure differences have also been studied. However, since this involves handling large quantities of toxic chlorine, extensive equipment corrosion countermeasures and safety measures are required, making it difficult to say whether this method is industrially suitable.

[0016] As described above, the separation and purification of each element by a dry method has the disadvantages of remaining at the level of crude separation or requiring high-cost treatment, compared with a wet method.

[0017] In contrast, wet treatment (wet process) using wet smelting methods such as acid leaching, neutralization, and solvent extraction has the advantages of consuming less energy and being able to separate and recover mixed valuable components at high purity.

[0018] However, when using wet processing to treat spent LIBs, hexafluorophosphate anions, a component of the electrolyte contained in the spent LIBs, are difficult to treat and cannot be completely decomposed even with high-temperature, high-concentration sulfuric acid. Consequently, they are mixed into the acid solution that leaches out valuable components. Since hexafluorophosphate anions are water-soluble carbonates, recovering phosphorus and fluorine from the aqueous solution after valuable components have been recovered is difficult. This requires various countermeasures to prevent discharge into public waters, resulting in significant environmental restrictions.

[0019] Furthermore, it is not easy to efficiently leach valuable components from waste LIBs using only acid and obtain a solution suitable for purification. Since the waste LIB itself is difficult to leach using acid or the like, it is not easy to completely leach valuable components.

[0020] Furthermore, if strong oxidizing acids are used for forced leaching, impurities such as aluminum, iron, and manganese, which are not suitable for industrial recycling, will be leached out along with the valuable components. This necessitates neutralization or other treatment of the impurities, which increases the cost of the neutralizer and the amount of wastewater and sediment produced.

[0021] Furthermore, there may be residual charges in the waste LIBs. Direct disposal of the waste LIBs carries the risk of heat generation or explosion, and thus requires labor and effort for discharging the residual charges.

[0022] Thus, using only wet treatment to treat waste LIBs cannot be said to be an absolutely advantageous method.

[0023] Therefore, attempts have been made to adopt a combined dry and wet treatment method for the waste LIBs that are difficult to treat using either dry treatment or wet treatment alone. Specifically, a dry treatment such as calcining the waste LIBs is used to remove impurities as much as possible to obtain a uniform waste LIB product. The resulting product is then subjected to wet treatment to separate the valuable components from other components.

[0024] In the combined dry and wet treatment method, fluorine and phosphorus in the electrolyte are volatilized and removed during dry treatment, while organic components such as plastics and separators, which are components of the spent LIBs, are also decomposed by heat. Since the spent LIBs obtained through dry treatment are uniform in texture, they can be easily processed as a uniform raw material during wet treatment.

[0025] However, simply combining dry treatment with wet treatment still has the problem that cobalt contained in the waste LIB is distributed into the slag, resulting in recovery loss, as described above.

[0026] To address this issue, a method has been considered, in which the cobalt is distributed to the metal rather than the slag by adjusting the dry treatment conditions, thereby reducing the amount of cobalt distributed to the slag and performing reduction melting. However, the metal obtained by this method is a refractory corrosion-resistant alloy containing nickel and cobalt in a copper-based matrix. Even if the valuable components are to be separated and recovered from the corrosion-resistant alloy, acid dissolution is difficult and cannot be effectively recovered.

[0027] Furthermore, when chlorine gas is used, for example, to leach corrosion-resistant alloys, the resulting solution (leachate) contains high concentrations of copper and relatively low concentrations of nickel or cobalt. While nickel and cobalt can be easily separated using known methods such as solvent extraction, it is particularly difficult to easily and cost-effectively separate copper from nickel and cobalt.

[0028] As described above, it is difficult to effectively separate copper from nickel and cobalt from alloys derived from, for example, scrap LIBs, which contain various other valuable components in addition to copper, nickel, and cobalt. It should be noted that the aforementioned issues also apply when separating copper from scrap batteries containing copper, nickel, and cobalt other than scrap LIBs. Similarly, similar issues arise when separating copper from alloys containing copper, nickel, and cobalt other than scrap batteries.

[0029] Prior art literature

[0030] Patent Literature

[0031] Patent Document 1: Japanese Patent Application Laid-Open No. 2012-172169;

[0032] Patent Document 2: Japanese Patent Application Laid-Open No. 63-259033. Summary of the Invention

[0033] The present invention has been proposed in view of such circumstances, and its object is to provide a treatment method capable of selectively separating nickel and / or cobalt alloys from alloys containing copper and nickel and / or cobalt, such as waste lithium-ion batteries.

[0034] As a result of intensive studies, the present inventors have found that the above-mentioned problems can be solved by the following means, thereby completing the present invention.

[0035] (1) The first invention of the present invention is a method for treating an alloy, which is a method for treating an alloy containing copper and nickel and / or cobalt to obtain a solution containing nickel and / or cobalt, wherein the method comprises: a leaching step, in the presence of a sulfiding agent, leaching the alloy with an acid to obtain a leachate; a reduction step, in which the leachate is reduced with a reducing agent to obtain a reduced solution; and an oxidation-neutralization step, in which an oxidizing agent and a neutralizing agent are added to the reduced solution to obtain a solution containing nickel and / or cobalt.

[0036] (2) The second invention of the present invention is a method for processing an alloy, wherein the alloy in the first invention is an alloy obtained by melting waste lithium-ion batteries.

[0037] (3) The third invention of the present invention is a method for processing an alloy, wherein in the first or second invention, the alloy is in a powdery form.

[0038] (4) The fourth invention of the present invention is a method for treating an alloy according to any one of the first to third inventions, wherein in the reduction step, a metal containing nickel and / or cobalt is used as the reducing agent, and the reduction treatment is carried out by bringing the leaching solution into contact with the metal.

[0039] (5) The fifth invention of the present invention is an alloy processing method according to any one of the first to fourth inventions, wherein in the oxidation-neutralization step, the oxidizing agent and the neutralizing agent are added to the reducing solution simultaneously, or the neutralizing agent is added after the oxidizing agent is added.

[0040] (6) The sixth invention of the present invention is a method for treating an alloy according to the first invention, wherein in the leaching step, the leaching treatment is carried out using an acid solution while controlling the redox potential (reference electrode: silver / silver chloride electrode) within a range of 240 mV to 300 mV.

[0041] (7) A seventh invention of the present invention is an alloy processing method according to the sixth invention, wherein in the leaching step, an oxidant is added to control the redox potential.

[0042] (8) An eighth invention of the present invention is an alloy treatment method according to the first invention, wherein in the leaching step, the leaching treatment is performed by controlling the pH of the alloy using an acid solution within a range of 0.8 to 2.0.

[0043] (9) The ninth invention of the present invention is an alloy treatment method according to the eighth invention, wherein a solution containing sulfuric acid is used as the acid solution in the leaching step.

[0044] (10) The tenth invention of the present invention is an alloy treatment method according to the first invention, wherein in the leaching step, the leaching treatment is performed using an acid solution while controlling the leaching temperature within a range of 50° C. to 80° C.

[0045] (11) The eleventh invention of the present invention is a method for processing an alloy, wherein in the first invention, the particle size of the alloy is less than 500 μm.

[0046] (12) The twelfth invention of the present invention is a method for processing an alloy, wherein the alloy is an atomized powder obtained by atomization treatment in the eleventh invention.

[0047] (13) The thirteenth invention of the present invention is a method for processing an alloy, wherein in the eleventh or twelfth invention, the alloy is a powder having a particle size of less than 150 μm.

[0048] (14) The fourteenth invention of the present invention is a method for treating an alloy. In the first invention, the alloy contains zinc, and the treatment method further includes: a dezincification step of removing the zinc by subjecting the neutralized liquid obtained through the oxidation neutralization step to ion exchange treatment or solvent extraction treatment.

[0049] (15) The fifteenth invention of the present invention is a method for processing an alloy, wherein the alloy in the first invention is an atomized powder obtained by dry treatment, and the dry treatment comprises: a process of placing waste lithium-ion batteries into a roasting furnace for oxidative roasting; a process of placing the oxidative roasted product together with a reducing agent into a reduction furnace for reduction melting to obtain molten metal and reduced slag; and a process of performing an atomization treatment, wherein the atomization treatment solidifies the molten metal in a fine powder state.

[0050] According to the present invention, nickel and / or cobalt can be selectively separated and processed from an alloy containing copper, nickel and / or cobalt such as waste lithium-ion batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 This is a process diagram showing the flow of the alloy processing method.

[0052] Figure 2 This is a graph showing the relationship between the redox potential of the leachate and the leaching rate of nickel and copper in Examples.

[0053] Figure 3 This is a graph showing the relationship between the leaching time of the leachate in Example 3 and the leaching rate of nickel in the leachate.

[0054] Figure 4 This is a graph showing the consumption transition of the sulfuric acid aqueous solution used to maintain the pH in the slurry in Example 3.

[0055] Figure 5 This is a diagram showing the distribution of the consumption of each element in the aqueous sulfuric acid solution used under various pH conditions in Example 3.

[0056] Figure 6 This is a graph showing the relationship between the leaching time and the nickel leaching rate in Example 4.

[0057] Figure 7 This is a graph showing the relationship between sulfuric acid consumption and ORP in Example 4.

[0058] Figure 8This is a graph showing the transition of the ORP value with respect to the leaching time during the leaching treatment of atomized powders of various particle sizes in Example 5. DETAILED DESCRIPTION

[0059] The following describes in detail a specific embodiment of the present invention (hereinafter referred to as "the present embodiment"). It should be noted that the present invention is not limited to the following embodiment at all and can be implemented with appropriate changes within the scope of the purpose of the present invention. It should be noted that in this specification, the expression "X to Y" (X and Y are arbitrary numerical values) means "X or more and Y or less".

[0060] 1. Alloy processing method

[0061] The alloy processing method of this embodiment is a method for obtaining a solution containing nickel and / or cobalt from an alloy containing copper and nickel and / or cobalt. In other words, the nickel and / or cobalt constituting the alloy are selectively separated from the copper.

[0062] Examples of alloys containing copper, nickel, and / or cobalt that can be processed include alloys obtained by heating, melting, and reducing waste batteries such as waste generated by deterioration of automobiles and electronic equipment, waste lithium-ion batteries generated over the life of lithium-ion batteries, and defective batteries in the battery manufacturing process.

[0063] As a method for obtaining alloys using waste lithium-ion batteries and the like as raw materials and heating and melting them, a dry treatment method can be cited. This dry treatment includes: mechanically disassembling the waste lithium-ion batteries and performing oxidative roasting to separate carbon or aluminum from electrode materials or containers, and fluorine or phosphorus from the electrolyte, to obtain a roasted product (oxidized roasted product); adding a reducing agent to the obtained oxidized roasted product and performing reduction melting to obtain reduced metal and slag; and finely refining the obtained reduced metal through atomization or other means. This method controls the degree of reduction by appropriately managing the oxygen partial pressure of the reduction melting environment, thereby effectively separating impurities while preventing cobalt from being distributed into the slag.

[0064] Note that, by refining the alloy, specifically, by making the alloy into a particle size suitable for acid leaching in the leaching step described later, the leaching efficiency can be improved.

[0065] Figure 1 It is a process diagram showing the flow of the alloy processing method according to the present embodiment.

[0066] Specifically, the alloy treatment method of this embodiment includes: a leaching step S1, in which the alloy to be treated is leached with an acid in the presence of a sulfiding agent to obtain a leachate; a reduction step S2, in which the leachate is reduced with a reducing agent to obtain a reduced solution; and an oxidation-neutralization step S3, in which an oxidizing agent and a neutralizing agent are added to the obtained reduced solution to obtain a solution containing nickel and / or cobalt.

[0067] In the leaching step S1 , it is preferred that the leaching treatment be performed with an acid solution while controlling the redox potential (reference electrode: silver / silver chloride electrode) within a predetermined range.

[0068] In the leaching step S1 , it is preferred to perform the leaching treatment while controlling the pH within a predetermined range using an acid solution.

[0069] Furthermore, in the leaching step S1 , it is preferred that the leaching treatment be performed with an acid solution while controlling the leaching temperature within a predetermined range.

[0070] In addition, it is preferable to use an alloy that has been made into a powder having a predetermined particle size by a method such as atomization as the alloy to be leached in the leaching step S1.

[0071] More specifically, the alloy treatment method will be described below using an alloy containing copper, nickel, and / or cobalt obtained by melting waste lithium-ion batteries (waste LIB) as an example to be treated.

[0072] (1) Leaching process

[0073] In the leaching step S1, the alloy is leached with acid in the presence of a sulfiding agent to obtain a leachate. That is, the sulfiding agent and the acid are brought into contact with the alloy simultaneously, and the leaching is performed with the acid.

[0074] The reactions occurring during the leaching treatment in the leaching step S1 are shown in the following reaction formulas [1] to [5]. The following formulas show the reactions when solid sulfur (S) is used as the sulfiding agent and sulfuric acid is used as the acid.

[0075] Cu+S→CuS[1]

[0076] ·Ni+H2SO4+1 / 2O2→NiSO4+H2O···[2]

[0077] ·Co+H2SO4+1 / 2O2→CoSO4+H2O···[3]

[0078] ·H2S+1 / 2O2→S+H2O···[4]

[0079] CuS+2O2→CuSO4[5]

[0080] As shown in the above reaction formula, a leaching reaction occurs while the alloy is in contact with the sulfiding agent, generating copper sulfide that is leached from the alloy by reaction with the acid (Formula [1]). Furthermore, nickel and / or cobalt are leached by the acid and exist in the leachate as ions (Formulas [2], [3]). It should be noted that even when the leached nickel and / or cobalt reacts with the sulfiding agent to form sulfide, the sulfide is decomposed by the presence of the acid, and the nickel or cobalt exists in the leachate as ions.

[0081] [About alloys]

[0082] The alloy obtained by melting spent lithium-ion batteries contains, in addition to copper, nickel, and cobalt, various impurities that are not intended for recycling. In this embodiment, such an alloy is leached in the presence of an acid and a sulfiding agent, whereby the copper leached from the alloy is precipitated and separated as copper sulfide. Meanwhile, the alloy is leached with acid to leach nickel and / or cobalt, yielding a leachate. It should be noted that impurities such as copper, iron, and / or phosphorus, as well as zinc and manganese, that have not reacted with the sulfiding agent may remain in the leachate.

[0083] Here, as the alloy to be processed, which is obtained by melting waste lithium-ion batteries, there are powdered materials such as alloys cast into plates, alloys stretched into wires and appropriately cut into rods, and alloy powders obtained by applying an atomization method (hereinafter, for convenience, the alloy powders are also referred to as "atomized powders"), and their shapes are not particularly limited.

[0084] Among them, by using a powdered material such as atomized powder as the treatment object, it is possible to effectively carry out an acid leaching treatment, and nickel and / or cobalt can be effectively leached. It should be noted that the atomization method is a method of obtaining a powder by causing the molten metal to be dispersed and rapidly cooled (solidified) by contact with high-pressure gas or water.

[0085] When the alloy is formed into a powder such as an atomized powder, its particle size is preferably approximately less than 300 μm, allowing for more efficient leaching. On the other hand, if the particle size is too small, not only will the processing costs required for micronization be increased, but it may also cause dust generation and fire. Therefore, the particle size of the powdered alloy is preferably approximately 10 μm or larger.

[0086] Furthermore, when the alloy is subjected to leaching treatment, it is preferred to pre-clean the alloy with a dilute acid in advance, thereby activating the surface of the alloy and promoting the leaching reaction.

[0087] [About acid]

[0088] As an acid, there is no particular limitation as long as the pH can be controlled within the range of more than 0.8 and less than 2.0 to implement the leaching process as described later. For example, strong acids such as hydrochloric acid, sulfuric acid, and nitric acid can be used alone or in combination. In addition, chloride can also be contained in sulfuric acid and used as an acid. Among them, in the case of an ideal recycling method of recycling waste batteries of lithium ion batteries and supplying them to lithium ion battery raw materials again, i.e., the so-called "battery to battery", it is preferred to use an acid containing sulfuric acid. By using sulfuric acid as an acid, a leachate can be obtained in the form of a sulfate that is easily used for the positive electrode material of a lithium ion battery.

[0089] The amount of acid used in the leaching treatment is 1 equivalent or more, preferably 1.2 equivalents or more, and more preferably 1.2 equivalents or more and 11 equivalents or less, relative to the total amount of nickel and / or cobalt contained in the alloy. Increasing the acid concentration can accelerate the leaching reaction. Specifically, to adjust the acid amount to a pH of 0.8 or more, it is preferably 1.2 equivalents or more and 2 equivalents or less.

[0090] Furthermore, during the leaching process, the acid and alloy may be supplied to a device having multiple stages of mixing sections, such as concentrators, connected together, so that the acid and alloy come into countercurrent contact in multiple stages. For example, the alloy may be supplied to the mixing section at the top of the device, and the acid may be supplied to the mixing section at the bottom of the device, so that the acid and alloy come into countercurrent contact in multiple stages.

[0091] [About vulcanizing agents]

[0092] As the sulfiding agent added together with the acid, for example, sodium hydrosulfide or elemental sulfur can be used. When elemental sulfur is used, it is preferably pulverized appropriately to promote the reaction.

[0093] The amount of the sulfiding agent is preferably 1 equivalent or more relative to the amount of copper contained in the alloy.

[0094] Regarding the vulcanizing agent, it can be added to the alloy at the same time as the acid, but it is preferably added first and then the acid. When the acid and the vulcanizing agent are added to the alloy at the same time, there is a possibility that the reaction will proceed violently and bumping will occur. By adding the vulcanizing agent first and then the acid to contact, it is possible to suppress the violent reaction. When adding the vulcanizing agent first and then the acid, for example, the alloy and the vulcanizing agent are placed in a solvent such as water, and then the acid is added. In addition, in order to uniformly carry out the reaction, bubbling with air or the like can be used.

[0095] [Regarding the conditions for leaching treatment]

[0096] In the leaching treatment, it is preferable to conduct preliminary experiments to determine appropriate ranges for the treatment time, the concentration of the slurry obtained by adding an acid and a sulfiding agent to the alloy, and other treatment conditions.

[0097] In particular, during the leaching process, it is preferred to measure the oxidation-reduction potential (ORP) or pH of the leachate and monitor and control the range of the measured ORP or pH. Furthermore, by adjusting the temperature range of the leaching reaction, the ORP or pH can be more appropriately controlled, thereby facilitating the leaching process. Furthermore, for the alloy being treated, using an alloy within a specified particle size range allows for more appropriate control of the leaching process conditions. In the alloy treatment method of this embodiment, one of these leaching process conditions can be controlled within a respective appropriate range, but it is more preferred to combine two or more conditions to select an optimal region.

[0098] (ORP control)

[0099] Specifically, regarding the control of ORP, it is preferably controlled to be 240 mV or more and 300 mV or less, and particularly preferably controlled to be 240 mV or more and 280 mV or less, based on a silver / silver chloride electrode.

[0100] As a specific scheme for controlling ORP, for example, a method of adding an oxidant can be cited. As the oxidant, conventionally known oxidants such as oxygen, air, hydrogen peroxide, and ozone gas can be used. For example, when a gaseous oxidant is used as the oxidant, the ORP of the leachate during the leaching process can be controlled by bubbling it into the solution and adjusting its supply rate (gas supply rate). Specifically, when the ORP of the leachate rises too much, the ORP can be lowered by reducing or stopping the supply of the oxidant. Conversely, when the ORP drops to near the lower limit, the ORP can be raised by increasing the supply of the oxidant.

[0101] By controlling the ORP within the above range and performing the leaching treatment, for example, the leaching of nickel and / or cobalt can be promoted, and the redissolution of the precipitated copper sulfide due to excessive oxidation can be suppressed, thereby more effectively separating copper from nickel and / or cobalt.

[0102] (pH control)

[0103] Regarding pH control, the ORP is controlled and maintained, and the pH of the acid solution is preferably controlled within a range of 0.8 to 1.6, particularly preferably within a range of 0.8 to 2.0. Controlling and maintaining the pH within this range promotes the leaching reaction and suppresses redissolution of precipitated copper sulfide due to excessive oxidation. Furthermore, by performing the leaching treatment while controlling the pH within a range of 0.8 to 2.0, the leaching process can be performed more efficiently, reducing the amount of acid used and the amount of neutralizer used to neutralize the acid, which is also beneficial in terms of productivity.

[0104] The pH can be controlled by adjusting the amount of acid added. For example, to control the pH to 0.8 or higher, the acid is added in an amount of 1.2 equivalents to 2 equivalents relative to the total amount of nickel and / or cobalt contained in the alloy.

[0105] In particular, when sulfuric acid is used as the acid, the generation of hydrogen sulfide gas can be effectively suppressed by controlling the pH to be in the range of 0.8 or higher and performing the leaching treatment.

[0106] By controlling and maintaining the ORP or pH range during the leaching process, the leaching reaction can be promoted and the redissolution of the precipitated copper sulfide due to excessive oxidation can be suppressed. It should be noted that since ORP fluctuates with pH and temperature, it is preferable to simultaneously measure ORP, pH, and liquid temperature during the leaching process and control them so that they are maintained within their respective appropriate ranges.

[0107] (Control of leaching reaction)

[0108] Furthermore, the reaction temperature also has a significant impact on the leaching treatment in leaching step S1 and subsequent treatments. In the alloy treatment method of this embodiment, when the alloy is leached with acid in the presence of a sulfiding agent, the leaching reaction temperature is preferably controlled within a range of 50°C to 80°C. It should be noted that the leaching reaction temperature (leaching temperature) refers to the temperature of the reaction solution (leachate) during leaching.

[0109] When the leaching temperature is less than 50°C, the ORP of the leachate is not within the range suitable for nickel and / or cobalt leaching, the reaction rate in the above reaction formulas [2] and [3] is reduced, and leaching may require a long time.

[0110] In contrast, by setting the leaching temperature to 50°C or higher, the reaction rates of reaction formulas [2] and [3] are accelerated, allowing nickel and / or cobalt to be leached in a shorter time. Furthermore, by accelerating leaching, the leaching rate of nickel and / or cobalt can be increased. It should be noted that the leaching temperature is more preferably 55°C or higher, and particularly preferably 60°C or higher.

[0111] In addition, when the leaching temperature exceeds 80°C, the reactions of the above reaction formulas [2] and [3] become excessive, and it may be difficult to control the ORP of the leachate. In this case, the coexisting sulfiding agent will be discharged from the leachate as hydrogen sulfide gas. When hydrogen sulfide gas is discharged from the leachate, the sulfidation reaction of the copper leached by acid shown in the above reaction formula [1] does not proceed, and copper is difficult to precipitate as copper sulfide. It should be noted that hydrogen sulfide gas is oxidized by oxygen to sulfur (the above reaction formula [4]), but since hydrogen gas is also generated along with the hydrogen sulfide gas, the oxidation reaction of the reaction formula [4] is also difficult to occur.

[0112] In contrast, by setting the leaching temperature to 80°C or lower, the alloy can be suitably leached in the presence of a sulfiding agent, effectively separating copper as copper sulfide. The leaching temperature is more preferably 75°C or lower, and particularly preferably 70°C or lower.

[0113] (Alloy particle size)

[0114] The alloy to be subjected to the leaching treatment preferably has a particle size of less than 500 μm. For example, it is preferable to use a pulverized product obtained by pulverizing the alloy to a particle size of less than 500 μm.

[0115] Here, when an alloy containing copper and nickel and / or cobalt is brought into contact with an acid in the presence of a sulfiding agent, the nickel and / or cobalt present on the alloy surface is converted into ions and leached out, and copper sulfide (copper sulfide) sulfided by the sulfiding agent is formed on the alloy surface. The copper sulfide formed in this process is then released from the particle surface due to contact between particles or collision with baffles within the reaction vessel, leaving unreacted nickel and / or cobalt and copper exposed again on the alloy surface.

[0116] As described above, since the leaching process of the alloy begins at the surface, when the alloy particle size is 500 μm or larger, the leaching reaction takes a long time to reach the center of the particle. In contrast, by subjecting the leaching process to alloys with a particle size of less than 500 μm, the leaching rate of nickel and / or cobalt is accelerated, enabling efficient leaching in a short time.

[0117] Furthermore, the alloy to be processed is preferably in the form of a powder having a particle size of less than 300 μm, more preferably in the form of a powder having a particle size of less than 150 μm.

[0118] In particular, by subjecting powders with a particle size of less than 150 μm to leaching treatment, not only the leaching rate of nickel and / or cobalt can be further increased, but also the leaching rate of nickel and / or cobalt can be increased. The reason for this is not necessarily clear, but it is believed that by subjecting powders with a particle size of less than 150 μm to leaching treatment, the leaching rate can be adjusted to an ORP suitable for leaching treatment.

[0119] As described above, the alloy to be processed can be any pulverized product obtained by pulverizing by a conventionally known method, and the pulverization is performed to obtain an alloy pulverized product having a particle size of less than 500 μm. In addition, as the pulverized product, a powder such as an atomized powder obtained by an atomization method is preferably used. By using the atomized powder as the processing object, a pulverized product having a particle size of less than 500 μm that is controlled to be suitable for leaching treatment can be obtained. It should be noted that the atomization method refers to a method of obtaining a powder by causing the molten metal to be dispersed and rapidly cooled (solidified) by contact with high-pressure gas or water.

[0120] In particular, atomized powders produced from reduced metals obtained through dry processing of waste lithium-ion batteries can contain virtually no powders with particle sizes larger than 500 μm. Furthermore, atomized powders produced from waste lithium-ion batteries can contain a high proportion of powders with particle sizes smaller than 150 μm, achieving a highly preferred nickel and / or cobalt leaching rate.

[0121] (other)

[0122] The endpoint of the leaching reaction can be determined by measuring the ORP of the leachate. For example, if no new alloy is added to the reaction tank, the endpoint of nickel and / or cobalt leaching can be determined by observing that the ORP value of the leachate no longer decreases.

[0123] It should be noted that after the leaching treatment of the alloy is completed, copper may be leached again when the precipitated copper sulfide is oxidized. Therefore, it is preferable to maintain the ORP of the leachate within the range of 240 mV to 300 mV until the leachate and copper sulfide are separated.

[0124] Furthermore, divalent copper ions may be added during the leaching process, whereby the divalent copper ions act as a catalyst and promote the leaching reaction.

[0125] (2) Reduction process

[0126] In the reduction step S2, the leachate obtained in the leaching step S1 is reduced with a reducing agent to obtain a reduced solution containing nickel and / or cobalt. During the leaching process in the leaching step S1, copper constituting the alloy may be acid-leached along with the nickel and / or cobalt and dissolved in the solution, but some copper may remain in the solution without reacting with the sulfiding agent. Therefore, in the reduction step S2, the trace amount of copper remaining in the leachate is reduced to form a copper-containing precipitate. The resulting precipitate is then separated by solid-liquid separation to obtain a reduced solution containing nickel and / or cobalt.

[0127] In particular, in the leaching step S1, when the leaching treatment is performed while the ORP of the leachate is controlled to be 280 mV or higher, although the leaching rate of nickel and / or cobalt is improved, copper is also leached, and thus copper is likely to be included in the leachate. Similarly, when the leaching treatment is performed while the pH of the leachate is controlled to be 1.6 or lower, although the leaching rate of nickel and / or cobalt is improved, copper is also leached, and thus copper is likely to be included in the leachate.

[0128] In this regard, by subjecting the leachate obtained in the leaching step S1 to a reduction treatment with a reducing agent, copper can be selectively separated while maintaining a high leaching rate of nickel and / or cobalt.

[0129] As a reducing agent, for example, a metal cheaper than copper can be used. Among these, a metal containing nickel and / or cobalt is preferably used, and the copper is reduced by bringing the leachate into contact with the metal. In the alloy treatment method of this embodiment, since a solution containing nickel and / or cobalt is obtained, the use of the metal containing nickel and / or cobalt, which is the target of recovery, as a reducing agent eliminates the need for separate recovery of the reducing agent in a subsequent step, which is industrially advantageous.

[0130] It should be noted that, in addition to the above-mentioned metals, sulfides can also be used as reducing agents. The sulfides can be solid, liquid, or gaseous. Alternatively, a mixture of the alloy powder to be treated in the above-mentioned leaching process and sulfur can be used. Furthermore, an atomized powder obtained by rapidly cooling and pulverizing a molten alloy to be treated can be used.

[0131] The reduction treatment method is not particularly limited. When a solid or liquid reducing agent is used, the reducing agent may be directly added to the leachate. When the reducing agent is a gas (gaseous state), the reducing agent may be added by bubbling the reducing agent in the leachate.

[0132] It is preferred to conduct preliminary experiments to select the optimal range of the amount of reducing agent added or the reaction temperature. In addition, during the reduction treatment, it is preferred to monitor the oxidation-reduction potential (ORP) or pH and appropriately control the amount of reducing agent added. It is preferred to select the optimal range of ORP or pH through preliminary experiments.

[0133] (3) Oxidation Neutralization Process

[0134] In the oxidation neutralization step S3 , an oxidizing agent and a neutralizing agent are added to the reduced solution obtained in the reduction step S2 to perform oxidation neutralization treatment, thereby obtaining a solution containing nickel and / or cobalt.

[0135] Specifically, in the oxidation-neutralization step S3, an oxidizing agent is added to the reducing solution to initiate an oxidation reaction, and a neutralizing agent is added to control the pH of the solution within a predetermined range. This generates a precipitate of impurities such as iron and / or phosphorus contained in the reducing solution. Thus, in the oxidation-neutralization step S3, the impurities such as iron and / or phosphorus are separated as a precipitate to obtain a purified nickel- and / or cobalt-containing solution.

[0136] As the oxidizing agent, a conventionally known oxidizing agent such as hydrogen peroxide or hypochlorous acid can be used. Alternatively, an oxygen-containing gas such as air, pure oxygen, or ozone gas can be used.

[0137] The oxidation-reduction potential (ORP) of the solution is preferably monitored, and the addition of the oxidant is controlled so that the ORP falls within a predetermined range. Specifically, the oxidant is added to the solution so that the ORP (reference electrode: silver / silver chloride) falls within a range of, for example, 380 mV to 430 mV.

[0138] In addition, after initiating the oxidation reaction with an oxidizing agent, a neutralizing agent is added to preferably control the pH of the solution to a range of 3.8 to 4.5. By performing an oxidation neutralization treatment in which the pH is controlled within this range, impurities such as iron and / or phosphorus can be effectively precipitated.

[0139] The neutralizing agent is not particularly limited, and a conventionally known base such as sodium hydroxide or potassium hydroxide can be used.

[0140] In the oxidation-neutralization treatment, the oxidizing agent can be added to the reducing solution after the neutralizing agent is added. However, it is preferred to add the oxidizing agent and the neutralizing agent simultaneously or to add the neutralizing agent after the oxidizing agent is added. As described above, it is more preferred to add the neutralizing agent after the oxidizing agent is added to the reducing solution. For example, when the oxidizing agent is added to the reducing solution at a high pH due to the addition of the neutralizing agent, if the impurities contain iron, the iron is not fully oxidized, and a precipitate of Fe(OH)3 (iron precipitate) is not effectively formed, resulting in inadequate separation of the impurities.

[0141] Here, when zinc is contained as an impurity in the reducing solution, it is difficult to remove it by oxidation neutralization alone. If zinc needs to be removed as an impurity, it can be removed by ion exchange or solvent extraction.

[0142] Specifically, under the situation of removing zinc from reducing solution by ion exchange method, for example, use resin (ion exchange resin) that zinc absorption etc. are removed.As such resin, can use the resin of aminophosphoric acid system.By using the resin of aminophosphoric acid system, the zinc in the solution can be reduced to the concentration of about 1 / 10.It should be noted that, as the resin of aminophosphoric acid system, the commercially available DUOLITE C747 (trade name) of CHEMTEX company system is available.

[0143] Furthermore, when removing zinc from the reduced solution by solvent extraction, the concentration of zinc in the solution can be reduced to approximately 1 / 10 by using an acidic phosphorus compound-based extractant. An example of an acidic phosphorus compound-based extractant is di-2-ethylhexyl phosphate (D2EHPA).

[0144] In this manner, when the reduced solution obtained through the reduction step S2 contains zinc, a step (dezincification step) can be provided in which the neutralized solution (neutralized solution) generated by the oxidative neutralization treatment is subjected to ion exchange or solvent extraction to remove the zinc. This allows a solution containing nickel and / or cobalt from which zinc, an impurity, is effectively removed as the dezincified solution.

[0145] It should be noted that the reduced solution obtained through the reduction step S2 may contain manganese. In this case, during the oxidation neutralization treatment, by stepwise controlling the pH or ORP to a range different from the pH or ORP range when precipitating and removing iron and / or phosphorus, a manganese precipitate can be generated and separated.

[0146] Example

[0147] Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples at all.

[0148] [Example 1: Alloy Treatment]

[0149] (Leaching process)

[0150] The calcined product obtained by oxidative roasting of spent lithium-ion batteries (waste LIBs) undergoes a dry treatment by adding a reducing agent, heating, melting, and reducing the product. The molten alloy obtained by reduction melting is poured into a small crucible with a hole in the bottom. High-pressure gas or water is blown into the molten metal flowing out of the hole to disperse and solidify the molten metal, thereby obtaining a powder (atomized powder) with a particle size of less than 300 μm. The obtained atomized powder is used as the alloy to be processed. The composition of the atomized powder (powder) analyzed using an ICP analyzer is shown in Table 1 below.

[0151] Table 1

[0152]

[0153] The powdered material with the composition shown in Table 1 was prepared into a slurry with a concentration of 200 g / L. A vulcanizing agent (elemental sulfur, in the form of button-shaped sulfur granules with a diameter of 4-5 mm and a thickness of 1 mm) and sulfuric acid were added, and acid leaching was performed in the presence of the vulcanizing agent. The leaching temperature was 70°C and the leaching time was 6 hours. After leaching, the solid-liquid separation was achieved by filtration, and the resulting filtrate (leachate) was analyzed using an ICP analyzer to determine the concentrations of various elemental components (referred to as "leachate" in Table 2 below).

[0154] (Reduction process)

[0155] Next, nickel powder (reducing agent) with a particle size of 1 to 300 μm was added to the resulting leachate, and the leachate was subjected to a reduction treatment. After the reduction treatment, the leachate was filtered to separate the solid and liquid. The resulting filtrate (reduced solution) was analyzed using an ICP analyzer to determine the concentrations of the various elemental components (referred to as "reduced solution" in Table 2 below).

[0156] (Oxidation Neutralization Process)

[0157] Next, while maintaining the temperature of the resulting reduced solution between 60°C and 70°C, a 30% concentration of hydrogen peroxide solution (oxidant) was added. Following the addition of the hydrogen peroxide solution (oxidant), a sodium hydroxide solution (neutralizer) was added to perform an oxidative neutralization treatment on the reduced solution. The oxidation-reduction potential (ORP) at this point was in the range of 380 mV to 430 mV, using a silver / silver chloride electrode as a reference electrode, and the pH was in the range of 3.8 to 4.5. After the oxidative neutralization treatment, the solution was filtered to separate the solid and liquid, and the resulting filtrate (neutralized solution) was analyzed using an ICP analyzer to determine the concentrations of the various elemental components (referred to as "neutralized solution" in Table 2 below).

[0158] Table 2

[0159] (g / L) Ni Co Cu Fe P leachate 76 38 5 3 1 Reduction fluid 80 38 0.001 3 1 Neutralizing liquid 80 38 0.001 0.001 0.001

[0160] The analysis results in Table 2 show that the alloy before leaching contained 38% copper by mass (see Table 1). However, the copper concentration in the leachate was 5 g / L, which was lower than the concentrations of nickel or cobalt. This is believed to be because the leaching treatment caused most of the copper in the alloy (powder) to precipitate and separate as copper sulfide.

[0161] Furthermore, while the copper concentration in the leachate was 5 g / L, the copper concentration in the reduced solution was as low as 0.001 g / L. This is believed to be because the trace amount of copper remaining in the leachate was reduced by the reduction treatment and separated as a precipitate.

[0162] Furthermore, while the iron concentration in the reducing solution was 3 g / L and the phosphorus concentration was 1 g / L, the iron concentration in the neutralized solution was 0.001 g / L and the phosphorus concentration was as low as 0.001 g / L. This is believed to be because impurities such as iron and phosphorus were separated as precipitates during the oxidative neutralization process.

[0163] [Example 2: Regarding ORP conditions]

[0164] Scrap LIBs were dry-treated in the same manner as in Example 1. The molten alloy obtained by reduction melting was poured into a small crucible with a hole in the bottom. High-pressure gas or water was then blown into the molten metal flowing out of the hole to disperse and solidify the metal, producing a powder (atomized powder) with a particle size of 300 μm or less. The resulting atomized powder was used as the alloy to be processed. Table 3 below shows the composition of the atomized powder (powder) analyzed using an ICP analyzer.

[0165] Table 3

[0166]

[0167] Next, 25.0 g of the atomized powder was collected and a sulfurizing agent (elemental sulfur, button-shaped sulfur particles with a diameter of 4 to 5 mm and a thickness of 1 mm) was prepared in an amount equivalent to 1.25 times the copper in the alloy (in terms of mol).

[0168] Next, the alloy powder and the sulfiding agent were placed in a 500 ml capacity, heat-resistant glass separable flask equipped with four baffles, and 250 ml of pure water was added. The mixture was then stirred into a slurry using a stirring blade equipped with four Teflon (registered trademark) inclined blades at a rotation speed of 1000 rpm, sufficient to prevent the atomized powder from accumulating at the bottom of the reaction vessel.

[0169] In order to maintain the environment during the reaction in an oxidative state, an oxidizing agent (air) was bubbled through a glass filter at a flow rate of 0.5 L / min.

[0170] Then, after air bubbling, the slurry was heated to a set temperature of 60°C, and an acid solution (a 64% by weight aqueous sulfuric acid solution) was added at a flow rate of 15 ml / h to reduce the pH of the slurry to 1.2. Thereafter, while maintaining the pH and temperature, the atomized powder was subjected to leaching while adding an oxidant and controlling the oxidation-reduction potential (ORP). More specifically, the leaching process was carried out while controlling the ORP by bubbling air as an oxidant into the slurry. After the addition of sulfuric acid, 2 ml of the supernatant of the leached slurry was collected every hour and analyzed using an ICP analyzer to determine the concentrations of each component: copper, nickel, cobalt, iron, and sulfur.

[0171] After 6 hours of leaching, the leached slurry was recovered and solid-liquid separation was performed to confirm the amount of liquid and residue after leaching. Table 4 below shows the leaching conditions and the treatment results (final values) based on the condition settings, and Table 5 below shows the leaching rates of copper, nickel, and cobalt measured by ICP. Figure 2 Graph showing the relationship between the ORP of the leachate (reference electrode: silver / silver chloride electrode) and the leaching rates of nickel and copper.

[0172] Table 4

[0173]

[0174] Table 5

[0175]

[0176] like Figure 2 As shown in Table 5, the ORP increases with the addition of an oxidant and the implementation of the leaching treatment. Furthermore, it is clear that an ORP of 240 mV or higher improves the leaching rate of nickel and cobalt, enabling sufficient leaching. Furthermore, it is clear that when the ORP exceeds 300 mV, the leaching rate of copper tends to increase.

[0177] In summary, it can be seen that by controlling the ORP (reference electrode: silver / silver chloride electrode) within the range of 240 mV to 300 mV and performing an acid leaching treatment in the presence of a sulfiding agent, copper can be separated from the alloy and nickel and / or cobalt can be efficiently obtained.

[0178] [Example 3: pH conditions]

[0179] Scrap LIBs were dry-treated in the same manner as in Example 1. The molten alloy obtained by reduction melting was poured into a small crucible with a hole in the bottom. High-pressure gas or water was then blown into the molten metal flowing out of the hole to disperse and solidify the metal, producing a powder (atomized powder) with a particle size of 300 μm or less. The resulting atomized powder was used as the alloy to be processed. Table 6 below shows the composition of the atomized powder (powder) analyzed using an ICP analyzer.

[0180] Table 6

[0181]

[0182] Next, 25.0 g of the atomized powder was collected and a sulfurizing agent (elemental sulfur, button-shaped sulfur particles with a diameter of 4 to 5 mm and a thickness of 1 mm) was prepared in an amount equivalent to 1.25 times the copper in the alloy (in terms of mol).

[0183] Next, the alloy powder and the sulfiding agent were placed in a 500 ml capacity, heat-resistant glass separable flask equipped with four baffles, and 250 ml of pure water was added. The mixture was then stirred into a slurry using a stirring blade equipped with four Teflon (registered trademark) inclined blades at a rotation speed of 1000 rpm, sufficient to prevent the atomized powder from accumulating at the bottom of the reaction vessel.

[0184] In order to maintain the environment during the reaction in an oxidative state, an oxidizing agent (air) was bubbled through a glass filter at a flow rate of 0.5 L / min.

[0185] Then, after air bubbling, the slurry is heated to a set temperature of 60°C, and an acid solution (a 64% by weight sulfuric acid aqueous solution) is added at a flow rate of 15 ml / h to reduce the pH of the slurry to 0.8-2.0. Thereafter, the pH and temperature are maintained, and the atomized powder is subjected to leaching treatment while adding the acid solution to control the pH. More specifically, air is bubbled into the slurry, and the leaching treatment is carried out while controlling the pH by adding a sulfuric acid aqueous solution. After adding sulfuric acid, 2 ml of the supernatant of the leached slurry is collected every hour, and the concentrations of each component of copper, nickel, cobalt, iron and sulfur are measured using an ICP analyzer.

[0186] After 3 hours of leaching, the leached slurry was recovered and solid-liquid separation was performed to confirm the amount of liquid and residue after leaching. Table 7 below shows the leaching conditions and the treatment results (final values) based on the condition settings, and Table 8 shows the leaching rates of copper, nickel, and cobalt measured by ICP. Figure 3 A graph showing the relationship between the leaching time of the leaching solution and the leaching rate of nickel. Figure 4 The figure shows the consumption of the sulfuric acid aqueous solution used to maintain the pH in the slurry. Figure 5 This figure shows the distribution of the consumption of each element in the aqueous sulfuric acid solution used under various pH conditions.

[0187] Table 7

[0188]

[0189] Table 8

[0190]

[0191] like Figure 3 As shown in Table 8, in Test Examples 3-1 to 3-4 in which the acid leaching treatment was carried out in the presence of a sulfiding agent while controlling the pH in the range of 0.8 to 2.0 using an acid solution, copper was separated from the alloy and nickel and / or cobalt was efficiently obtained.

[0192] In addition, if Figure 4 As shown, the lower the pH is maintained, the higher the consumption of the aqueous sulfuric acid solution. Specifically, in Test Example 3-4, where the pH is maintained at 0.8, the consumption is approximately twice that of Test Example 3-1, where the pH is maintained at 2.0.

[0193] In addition, if Figure 5As shown, the lower the pH, the greater the amount of so-called free acid (free acid) that is not involved in the leaching of each metal element. The greater the amount of free acid, the greater the amount of neutralizer used to neutralize the solution in the post-leaching process. Therefore, when leaching an alloy at a pH below 0.8, it is considered to increase the amount of acid used and the amount of neutralizer used to neutralize the acid in subsequent steps.

[0194] [Example 4: Temperature conditions]

[0195] Scrap LIBs were dry-treated in the same manner as in Example 1. The molten alloy obtained by reduction melting was poured into a small crucible with a hole in the bottom. High-pressure gas or water was blown into the molten metal flowing out of the hole to disperse and solidify the metal, producing a powder (atomized powder) with a particle size of 300 μm or less. The resulting atomized powder was used as the alloy to be processed. The composition of the atomized powder (powder) analyzed using an ICP analyzer is shown in Table 9 below.

[0196] Table 9

[0197]

[0198] Next, 25.0 g of the atomized powder was collected, and 11.0 g of a sulfurizing agent (elemental sulfur, button-shaped sulfur particles with a diameter of 4 to 5 mm and a thickness of 1 mm) was prepared in an amount equivalent to 1.25 times (in mol) the copper in the alloy.

[0199] Next, the alloy powder and the sulfiding agent were placed in a 500 ml capacity, heat-resistant glass separable flask equipped with four baffles, and 250 ml of pure water was added. The mixture was then stirred into a slurry using a stirring blade equipped with four Teflon (registered trademark) inclined blades at a rotation speed of 1000 rpm, sufficient to prevent the atomized powder from accumulating at the bottom of the reaction vessel.

[0200] In order to maintain the environment during the reaction in an oxidative state, an oxidizing agent (air) was bubbled through a glass filter at a flow rate of 0.5 L / min.

[0201] After air bubbling, the slurry was heated to a predetermined temperature (the set temperatures shown in Table 10 below). An acid solution (a 64% by weight aqueous sulfuric acid solution) was added at a rate of 15 ml / h to lower the slurry's pH to 1.2. Thereafter, while maintaining the pH and temperature, an oxidant was added to control the ORP, and the atomized powder was subjected to a leaching process. More specifically, the leaching process was performed while air was bubbled through the slurry to control the ORP at each set temperature. After the addition of sulfuric acid, 2 ml of the supernatant from the leached slurry was collected every hour, and the concentrations of copper, nickel, cobalt, iron, and sulfur were measured using an ICP analyzer.

[0202] To prevent oxidation of the generated copper sulfide, the ORP (reference electrode: silver / silver chloride electrode) value during the reaction was controlled within the range of 240mV to 300mV. Specifically, the flow rate of the oxidant (air) was halved when the ORP reached 270mV, and further halved if the ORP continued to rise. This operation was repeated, and the air bubbling was finally stopped.

[0203] Table 10 below shows the leaching treatment conditions and the treatment results (final values) based on the condition settings, and Table 11 below shows the leaching rates of copper, nickel, and cobalt measured by ICP. Figure 6 A graph showing the relationship between leaching time and nickel leaching rate. Figure 7 A graph showing the relationship between sulfuric acid consumption and ORP. Note that in Table 10, the leaching results show that the liquid volume is less than 250 ml of the initial liquid volume due to evaporation caused by heating, and the ORP value exceeds 300 mV due to the tendency (air entrainment due to stirring) to increase after the air bubbling is stopped.

[0204] Table 10

[0205]

[0206] Table 11

[0207]

[0208] like Figure 6 As shown in Table 11, in Test Examples 4-1 to 4-4, in which the leaching treatment was carried out with an acid in the presence of a sulfiding agent while controlling the leaching temperature within the range of 50°C to 80°C, copper could be separated from the alloy and nickel and / or cobalt could be obtained efficiently.

[0209] In particular, Figure 7 As shown, when the leaching temperature was controlled within the range of 60°C to 80°C and the leaching treatment was carried out (Test Examples 4-2 to 4-4), the ORP reached 240 mV, the leaching rate of nickel and / or cobalt was accelerated, and the treatment could be carried out in a short leaching time.

[0210] In Test Examples 4-1 to 4-3, in which the leaching treatment was carried out by controlling the leaching temperature within the range of 50°C to 70°C, the ORP of the leaching treatment was always within the positive range, and the reaction of copper sulfide due to the generation of hydrogen sulfide gas or hydrogen gas was effectively suppressed.

[0211] On the other hand, in Test Example 4-5, in which the leaching temperature was controlled at 90°C and the leaching treatment was carried out, the copper leaching rate was higher than that of Test Examples 4-1 to 4-4. This is believed to be because the ORP became negative, and a large amount of sulfiding agent was discharged from the solution as hydrogen sulfide gas, preventing the reaction of copper sulfide, or because the rapidly increased ORP caused the precipitated copper sulfide to be oxidized and leached into the leachate.

[0212] Furthermore, in Test Example 4-5, the leaching rates of nickel and cobalt were lower than those in Test Examples 4-1 to 4-4. This is believed to be due to sulfidation of the nickel and / or cobalt due to excessive leaching reactions, or to insufficient leaching due to precipitation of sulfur, a sulfiding agent, on the alloy surface. Alternatively, it is believed that hydrogen ions in the leachate were released as hydrogen sulfide gas or hydrogen gas from the leachate due to excessive leaching reactions, resulting in insufficient leaching.

[0213] [Example 5: Particle Size of Alloy to be Processed]

[0214] Scrap LIBs were dry-treated in the same manner as in Example 1. The molten alloy obtained by reduction melting was poured into a small crucible with a hole in the bottom. High-pressure gas or water was then blown into the molten metal flowing out of the hole, causing it to disperse and solidify, yielding a powder (atomized powder) with a particle size of 300 μm or less. The resulting atomized powder was used as the alloy to be processed. Table 12 below shows the composition of the atomized powder (powder) analyzed using an ICP analyzer.

[0215] Table 12

[0216]

[0217] The obtained atomized powder was then sieved and classified into three particle sizes. Table 13 below shows the mass and distribution ratio of each particle size.

[0218] Table 13

[0219]

[0220] As can be seen from Table 12, as long as the atomized powder of waste LIBs is used, there is almost no powder with a particle size exceeding 500 μm, and powder with a particle size of less than 150 μm can be obtained at a ratio of nearly 90%.

[0221] Next, 25.0 g of atomized powder of each particle size was collected, and 9.7 g of a sulfurizing agent (elemental sulfur, button-shaped sulfur particles with a diameter of 4 to 5 mm and a thickness of 1 mm) was prepared in an amount equivalent to 1.25 times the copper in the alloy (in mol terms).

[0222] Next, the alloy powder and the sulfiding agent were placed in a 500 ml capacity heat-resistant glass separable flask equipped with four baffles, and 250 ml of pure water was added. The mixture was then stirred into a slurry using a stirring blade equipped with four Teflon (registered trademark) inclined blades at a rotation speed of 1000 rpm, sufficient to prevent the atomized powder from accumulating at the bottom of the reaction vessel.

[0223] In order to maintain the environment during the reaction in an oxidative state, an oxidizing agent (air) was bubbled through a glass filter at a flow rate of 0.5 L / min.

[0224] After air bubbling, the slurry was heated to 60°C, and an acid solution (64% by weight aqueous sulfuric acid solution) was added at a rate of 15 ml / h to lower the slurry's pH to 1.6. Leaching was then continued while maintaining pH and temperature until the ORP reached 250 mV. The leached slurry was recovered for solid-liquid separation, and the concentrations of copper, nickel, cobalt, iron, and sulfur in the filtrate were measured using an ICP analyzer.

[0225] Table 14 below shows the leaching treatment conditions and the treatment results (final values) based on the condition settings, and Table 15 below shows the leaching rates of copper, nickel, and cobalt measured by ICP. Figure 8 This graph shows the transition of the ORP value with respect to the leaching time during the leaching treatment of atomized powders of various particle sizes.

[0226] Table 14

[0227]

[0228] Table 15

[0229]

[0230] like Figure 8 As shown in Table 15, in Test Examples 5-1 to 5-3 in which the alloy in the form of powder less than 500 μm was leached with acid in the presence of a sulfiding agent, copper could be separated from the alloy and nickel and / or cobalt could be obtained efficiently.

[0231] Furthermore, as shown in Tables 14 and 15, it can be seen that in Test Example 5-1, in which a powder having a particle size of less than 150 μm was leached, the treatment could be performed with a shorter leaching time than in Test Examples 5-2 and 5-3, and the leaching rate of nickel and / or cobalt could be increased.

Claims

1. A method for treating an alloy, wherein the method comprises obtaining a solution containing nickel and / or cobalt from an alloy containing copper and nickel and / or cobalt. in, include: a leaching step of leaching the alloy with an acid in the presence of a sulfiding agent to obtain a leachate; a reduction step, performing a reduction treatment on the leachate with a reducing agent to obtain a reduced solution; and an oxidation-neutralization step, wherein an oxidizing agent and a neutralizing agent are added to the reducing solution to obtain a solution containing nickel and / or cobalt; In the reduction step, a metal containing nickel and / or cobalt is used as the reducing agent, and the leachate is brought into contact with the metal to perform a reduction treatment, thereby obtaining the reduced solution having a copper concentration of 0.001 g / L or less.

2. The alloy processing method according to claim 1, wherein: The alloy is obtained by melting waste lithium-ion batteries.

3. The alloy processing method according to claim 1 or 2, wherein: The alloy is in powder form.

4. The alloy processing method according to claim 1 or 2, wherein: In the oxidation-neutralization step, the oxidizing agent and the neutralizing agent are added to the reducing solution simultaneously, or the neutralizing agent is added after the oxidizing agent is added.

5. The alloy processing method according to claim 1, wherein: In the leaching step, the leaching treatment is carried out with an acid solution while the oxidation-reduction potential is controlled within the range of 240 mV to 300 mV. The reference electrode for the redox potential is a silver / silver chloride electrode.

6. The alloy processing method according to claim 5, wherein: In the leaching process, the redox potential is controlled by adding an oxidant.

7. The alloy processing method according to claim 1, wherein: In the leaching step, the leaching treatment is performed by controlling the pH of the solution to be within the range of 0.8 to 2.

0.

8. The alloy processing method according to claim 7, wherein: In the leaching step, a solution containing sulfuric acid is used as the acid solution.

9. The alloy processing method according to claim 1, wherein: In the leaching step, leaching treatment is performed using an acid solution while controlling the leaching temperature within a range of 50° C. to 80° C.

10. The alloy processing method according to claim 1, wherein: The alloy has a particle size of less than 500 μm.

11. The method for treating an alloy according to claim 10, wherein: The alloy is an atomized powder obtained by atomization treatment.

12. The method for treating an alloy according to claim 10 or 11, wherein: The alloy is in powder form with a particle size of less than 150 μm.

13. The method for treating an alloy according to claim 1, wherein: The alloy contains zinc, The alloy treatment method further includes a dezincification step of removing zinc by subjecting the neutralized solution obtained in the oxidation neutralization step to an ion exchange treatment or a solvent extraction treatment.

14. The method for treating an alloy according to claim 1, wherein: The alloy is an atomized powder obtained by dry processing. The dry treatment has: The waste lithium-ion batteries are placed in a roasting furnace for oxidation roasting; A step of placing the oxidized roasted product together with a reducing agent into a reduction furnace for reduction melting to obtain molten metal and reduced slag; and A step of performing an atomization process to solidify the molten metal into a fine powder state.

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