Method for producing valuable metals

Abstract

The present invention provides a method capable of efficiently separating manganese contained in a raw material from a metal to a slag without reducing the recovery rate of valuable metals in a dry smelting method such as a method of producing valuable metals from a raw material containing a waste lithium ion battery. The present invention is a method of producing a valuable metal from a raw material containing at least lithium, manganese, and the valuable metal, including: a reduction melting step of performing reduction melting treatment on the raw material to obtain a reduction product containing a molten metal containing the valuable metal and a slag; a slag separation step of recovering the molten metal from the reduction product; and an oxidation purification step of performing oxidation melting treatment by adding silicon dioxide (SiO2) as a flux to the recovered molten metal. Furthermore, in the oxidation purification step, SiO2 as a flux is added so that the weight ratio of SiO2 / MnO in the slag becomes 0.4 or more and 1.0 or less.

Description

TECHNICAL FIELD

[0001] The present application relates to a method for producing valuable metals from a raw material such as a waste lithium ion battery. BACKGROUND

[0002] In recent years, lithium ion batteries are becoming widespread as secondary batteries that are light and have a large output. As a lithium ion battery, a lithium ion battery in which a negative electrode material in which a negative electrode active material such as graphite is fixed to a negative electrode current collector made of a copper foil, a positive electrode material in which a positive electrode active material such as lithium nickelate or lithium cobaltate is fixed to a positive electrode current collector made of an aluminum foil, a separator made of a porous resin film of polypropylene or the like, and an electrolyte solution containing lithium hexafluorophosphate (LiPF6) or the like are enclosed in an outer can made of a metal such as aluminum or iron is known.

[0003] One of the main uses of lithium ion batteries is hybrid electric vehicles or electric vehicles, and it is expected that lithium ion batteries mounted on vehicles will be discarded in large quantities as the life cycle of the vehicles progresses. Many proposals have been made for recycling such used batteries or defective products generated during production (hereinafter referred to as "waste lithium ion batteries") as resources. For example, as a recycling method for waste lithium ion batteries, a dry smelting method in which a waste lithium ion battery is melted in a high-temperature furnace while controlling oxidation and reduction, and valuable metals such as nickel (Ni), cobalt (Co), and copper (Cu) are recovered as metals (hereinafter also referred to as "alloys") has been proposed.

[0004] Then, when valuable metals are recovered from a raw material containing a waste lithium ion battery by a dry smelting method, when a raw material containing manganese (Mn) as a waste lithium ion battery is treated, most of the manganese sometimes ends up in the recovered metals. In this case, although the manganese can be removed by oxidation in a subsequent oxidation purification process, the solid MnO generated by the oxidation treatment causes the viscosity of the slag to increase, and the loss of metals increases due to the metals being entrained, and as a result, there is a problem in that the recovery rate of valuable metals decreases.

[0005] For example, Patent Literature 1 discloses that in a method for recovering valuable metals from a waste lithium ion battery, a pre-oxidation process for performing oxidation treatment is provided before a dry smelting process, and thus a method in which it has been difficult to control the degree of oxidation in the melting process in the past can be realized, and valuable metals can be stably recovered at a high recovery rate. However, in the case where Mn is contained in the molten metal obtained in the melting process, no method for separating this Mn from the molten metal is shown.

[0006] PRIOR ART DOCUMENTS

[0007] PATENT LITERATURE

[0008] Patent Literature 1: Japanese Patent Application Publication No. 2012-172169 SUMMARY

[0009] Problem to be solved by the invention

[0010] The present invention was made in view of the above-described fact, and aims to provide a method capable of efficiently separating manganese contained in a raw material to a slag from a metal without reducing the recovery rate of a valuable metal in a dry smelting method such as a method of producing a valuable metal from a raw material containing a waste lithium ion battery.

[0011] Means for solving the problem

[0012] The present inventors made intensive studies in order to solve the above-described problem. As a result, it was found that, in an oxidizing purification process of removing impurity manganese from a molten metal obtained by reduction melting treatment, adding silicon dioxide (Si02) as a fluxing agent so that the weight ratio of Si02 / MnO in a generated slag becomes a specific range enables recovery of a metal at a high recovery rate and efficient separation and removal of manganese, and thus the present invention was completed.

[0013] (1) The first invention of the present invention is a method of producing a valuable metal, which is a method of producing the valuable metal from a raw material containing at least lithium, manganese, and a valuable metal, wherein a reduction melting process is performed on the raw material to obtain a reduction product containing a molten metal containing a valuable metal and a slag, a slag separation process is performed to recover the molten metal from the reduction product, and an oxidizing purification process is performed on the recovered molten metal by adding silicon dioxide (Si02) as a fluxing agent to perform oxidizing melting treatment, and in the oxidizing purification process, the Si02 is added as a fluxing agent so that the weight ratio of Si02 / MnO in the slag becomes 0.4 or more and 1.0 or less.

[0014] (2) The second invention of the present invention is a method of producing a valuable metal, wherein, in the first invention, the content of the manganese contained in the raw material is 15% by mass or less.

[0015] (3) The third invention of the present invention is a method of producing a valuable metal, wherein, in the first or second invention, a preheating process of heating the raw material to perform oxidizing roasting is further provided, and in the reduction melting process, the reduction melting treatment is performed on the raw material after oxidizing roasting.

[0016] (4) The fourth invention of the present invention is a method of producing a valuable metal, wherein, in any one of the first to third inventions, the raw material contains a waste lithium ion battery.

[0017] Effects of the invention

[0018] According to the present invention, it is possible to provide a method capable of efficiently separating manganese contained in a raw material to a slag from a metal without reducing the recovery rate of a valuable metal. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 is a process chart showing one example of a flow of a manufacturing method of a valuable metal. DETAILED DESCRIPTION

[0020] Hereinafter, an embodiment of the present application (hereinafter, referred to as "the present embodiment") will be described. Note that the present application is not limited to the following embodiment, and various modifications can be made within the scope of the gist of the present application.

[0021] 1. Manufacturing method of valuable metal

[0022] The manufacturing method of a valuable metal of the present embodiment is a method of separating and recovering the valuable metal from a raw material containing at least lithium, manganese, and a valuable metal. Therefore, it can also be referred to as a recovery method of a valuable metal. The method of the present embodiment is mainly a method based on a dry smelting process, but can also be constituted by a dry smelting process and a wet smelting process.

[0023] As the "raw material containing at least lithium, manganese, and a valuable metal", for example, a raw material including a waste lithium ion battery can be given. The positive electrode material constituting the lithium ion battery contains oxides of nickel and cobalt in addition to lithium. Note that the "waste lithium ion battery" is a concept including not only used lithium ion batteries, but also defective products generated in a manufacturing process of the positive electrode material and the like constituting the battery, residues inside the manufacturing process, generated waste, and the like as waste materials in the manufacturing process of the lithium ion battery. Therefore, the waste lithium ion battery can also be referred to as lithium ion battery waste.

[0024] In addition, the "valuable metal" that can be recovered from the raw material refers to at least nickel (Ni) and cobalt (Co). For example, when the raw material is a raw material including a waste lithium ion battery, as the valuable metal, in addition to nickel and cobalt, copper (Cu) and the like can be given, and further, an alloy constituted by a combination of nickel, cobalt, and copper can be given. Note that the content of each valuable metal included in the waste lithium ion battery is not particularly limited. For example, copper can be contained in an amount of 10% by mass or more.

[0025] Further, in the raw material including a waste lithium ion battery and the like, manganese (Mn) that is an impurity with respect to the above-mentioned valuable metal separated and recovered from the raw material is contained.

[0026] Specifically, the method for producing a valuable metal according to the present embodiment at least includes: a reduction melting step of subjecting a raw material to a reduction melting treatment to obtain a reduction product containing a molten metal containing a valuable metal and a slag; a slag separation step of recovering the molten metal from the reduction product; and an oxidation purification step of subjecting the recovered molten metal to an oxidation melting treatment to thereby purify the molten metal. Also, in the method, it is characterized in that, in the oxidation purification step, the oxidation melting treatment is performed with the addition of silicon dioxide (SiO2) as a flux, and at this time, the SiO2 is added so that the weight ratio of SiO2 / MnO in the generated slag becomes 0.4 or more and 1.0 or less.

[0027] Note that, in "SiO2 / MnO", manganese oxide (MnO) refers to a compound generated by oxidation of impurity manganese contained in a molten metal by an oxidation melting treatment performed on the molten metal.

[0028] As a result of the research by the present inventors and others, it was found that, in oxidation purification performed on a molten metal containing impurity manganese, by performing the oxidation melting treatment with the addition of SiO2 as a flux so that the weight ratio of SiO2 / MnO in the generated slag becomes 0.4 or more and 1.0 or less, a MnO-SiO2-based slag with a low melting point can be generated, and an increase in the viscosity of the slag can be suppressed.

[0029] As a result, manganese can be effectively distributed to the slag, and the entrapment of metal in the slag can be reduced, and the decrease in the recovery rate of the valuable metal can be prevented. Also, assuming a case where iron (Fe) is contained as an impurity in a molten metal containing manganese, in this case, even if the iron is contained in the generated MnO-SiO2-based slag in the form of an oxide, since the melting point of the slag is low, manganese can be efficiently separated to the slag, and the entrapment of metal in the slag can be suppressed.

[0030] Here, regarding the amount of SiO2 added as a flux, when the amount is set so that the weight ratio of SiO2 / MnO becomes less than 0.4, the melting point of the generated slag increases, the viscosity of the slag increases in the case where the operating temperature is the same, and the entrapment of the slag to the metal increases. Also, when the amount is set so that the weight ratio of SiO2 / MnO is more than 1.0, likewise, the melting point of the generated slag increases, the viscosity of the slag increases in the case where the operating temperature is the same, and the entrapment of the slag to the metal increases. In addition to this, since the amount of SiO2 added as a flux increases, the cost of the flux increases, or the cost of the slag treatment increases due to an increase in the amount of the slag.

[0031] According to such a method, when a valuable metal is produced from a raw material containing, for example, a waste lithium ion battery by a dry smelting method, manganese contained in the raw material can be efficiently separated to the slag from the metal without decreasing the recovery rate of the valuable metal.

[0032] Hereinafter, the manufacturing method of the valuable metal will be described more specifically, for example, using a raw material containing a waste lithium ion battery as a raw material containing at least lithium, manganese, and a valuable metal.

[0033] <2. Each process of the manufacturing method>

[0034] Figure 1 is a process diagram showing one example of a flow of the manufacturing method of the valuable metal of the present embodiment. As shown in Figure 1 the manufacturing method of the valuable metal has: a waste battery pretreatment process S1 for removing an electrolyte and an outer can of a waste lithium ion battery; a pulverization process S2 for pulverizing the contents of the battery to form a pulverized product; a pre-heating process (also referred to as an "oxidizing roasting process") S3 for pre-heating the pulverized product as necessary; a melting process (also referred to as a "reducing melting process") S4 for subjecting the pulverized product to a reducing melting treatment to obtain a reduction product containing a molten metal containing a valuable metal and a slag; a slag separation process S5 for separating the slag from the reduction product to recover the molten metal; and an oxidizing purification process S6 for subjecting the recovered molten metal to an oxidizing melting treatment to thereby purify the molten metal.

[0035] Here, with respect to the raw material containing a waste lithium ion battery, the amount (content) of manganese contained in the raw material with respect to the total amount of the raw material is preferably 15% by mass or less. When the content of manganese is greater than 15% by mass, the melting point of the CaO-Li2O-Al2O3-based slag is increased in the melting process S4 described later, and at this time, the valuable metal can be increased to be involved in the generated slag, and as a result, the recovery rate of the valuable metal at the time of obtaining the molten metal is decreased. On the other hand, as a lower limit value of the content of manganese, it is preferably 5% by mass or more with respect to the total amount of the raw material. When the content of manganese is less than 5% by mass, the amount of the waste lithium ion battery containing the manganese as an impurity is limited, and the processing efficiency can be decreased.

[0036] [Pre-treatment process of waste battery]

[0037] The pre-treatment process of the waste battery S1 is performed for the purpose of preventing explosion or harmless of the waste lithium ion battery, removing the outer can, and the like when recovering the valuable metal from the waste lithium ion battery.

[0038] That is, for example, the waste lithium ion battery such as a used lithium ion battery is a closed system, and has an electrolyte and the like in the inside, and thus, when performing the pulverization treatment in the original state thereof, there is a risk of explosion. Therefore, it is necessary to perform a discharge treatment or a removal treatment of the electrolyte by some means. In this way, in the pre-treatment process of the waste battery S1, by removing the electrolyte and the outer can, the safety can be improved, and in addition, the recovery productivity of the valuable metal such as copper, nickel, and cobalt can be improved.

[0039] As a specific method of the pretreatment, there is no particular limitation, and for example, the battery can be physically punctured by using a needle-like blade tip to cause the internal electrolyte to flow out and be removed. In addition, the waste lithium ion battery can be directly heated to be detoxified by causing the electrolyte to burn.

[0040] Note that the outer can that constitutes the battery is mostly made of metal aluminum, iron, or the like, and by performing such a pretreatment, the metal outer can can be relatively easily recovered as a valuable metal. For example, in the case where aluminum or iron included in the outer can is recovered, the removed outer can can be crushed and sieved using a shaker screen. In the case of aluminum, even slight crushing can easily be made into a powder, and thus recovery can be efficiently performed. In addition, the iron included in the outer can can be recovered by magnetic screening.

[0041] [Crushing process]

[0042] In the crushing process S2, the battery contents obtained by the waste battery pretreatment process S1 are crushed to obtain a crushed product. The process in the crushing process S2 is performed with the aim of improving the reaction efficiency in the dry smelting process in the next process, and by improving the reaction efficiency, the recovery rate of valuable metals such as copper, nickel, and cobalt can be improved.

[0043] As the crushing method, there is no particular limitation, and a publicly known crusher such as a cutting mixer can be used to crush the contents of the battery.

[0044] [Preheating process]

[0045] As needed, the preheating process S3 can be provided to heat the crushed product of the waste lithium ion battery subjected to the crushing process S2 to a predetermined temperature to perform the oxidation roasting process. By performing the oxidation roasting process in the preheating process S3, impurities included in the contents of the battery can be removed by volatilization or thermal decomposition.

[0046] In the preheating process S3, for example, oxidation roasting is preferably performed by heating at a temperature (preheating temperature) of 700°C or higher. By setting the preheating temperature to 700°C or higher, the removal efficiency of impurities included in the battery can be improved. On the other hand, as an upper limit value of the preheating temperature, 900°C or lower is preferable, and thus the thermal energy cost can be suppressed, and the processing efficiency can be improved.

[0047] The heat treatment is preferably performed in the presence of an oxidizing agent. Thereby, carbon contained in the contents of the battery can be efficiently oxidized and removed, and aluminum can be oxidized. In particular, by oxidizing and removing carbon, molten particles of valuable metals locally generated in the subsequent melting step S4 can be agglomerated without physical obstacles caused by carbon, and thus, the alloy obtained as a melt can be easily recovered in an integrated manner. Note that, generally, the main elements constituting the waste lithium-ion battery are easily oxidized in the order of aluminum > lithium > carbon > manganese > phosphorus > iron > cobalt > nickel > copper according to the difference in affinity with oxygen.

[0048] The oxidizing agent is not particularly limited, and from the viewpoint of ease of handling, an oxygen-containing gas such as air, pure oxygen, or oxygen-rich gas is preferably used. In addition, the amount of introduction of the oxidizing agent can be, for example, about 1.2 times the stoichiometric amount required for oxidation of each substance that is the object of the oxidation treatment.

[0049] [Melting Step]

[0050] In the melting step (reduction melting step) S4, the crushed product of the waste lithium-ion battery is melted (reduction melted) together with a fluxing agent, and a reduction product composed of a molten metal containing valuable metals and a slag is obtained. Thereby, impurity elements such as aluminum are contained in the slag as oxides, and phosphorus is also incorporated into the fluxing agent and contained in the slag. On the other hand, valuable metals such as copper, which are difficult to form oxides, can be melted and recovered as an integrated alloy (molten alloy) from the melt. Note that the "molten alloy" refers to an alloy in a molten state obtained from the melt.

[0051] As the fluxing agent, an element that incorporates impurity elements to form a low-melting basic oxide is preferably contained, and among them, a calcium compound is more preferably contained in terms of being inexpensive and stable at normal temperature conditions. Phosphorus as an impurity element becomes an acidic oxide upon oxidation, and thus, the more basic the slag formed by the melting treatment, the more easily phosphorus is incorporated into the slag.

[0052] As the calcium compound, for example, calcium oxide, calcium carbonate can be added. In addition, as the amount of calcium to be added, since an Al2O3-CaO-Li2O system is used as the slag system, it is preferable to add an appropriate amount for melting aluminum oxide in the sample by eutectic, that is, an amount of CaO / (Al2O3+CaO) = 0.15 or more in terms of weight ratio.

[0053] In the melting step S4, in order to appropriately adjust the oxidation-reduction degree at the time of melting the waste lithium-ion battery, it can be performed in the presence of an oxidizing agent or a reducing agent.

[0054] As the oxidizing agent, a publicly known oxidizing agent can be used, and a solid oxidizing agent can be added, or a gaseous oxidizing agent can be introduced into the furnace. Also, as the reducing agent, a publicly known reducing agent can be used, and a carbon atom-containing reducing agent is preferable. By adding a carbon atom-containing reducing agent to the waste lithium ion battery, oxides of valuable metals such as copper, nickel, cobalt, and the like, which are the objects of recovery, can be easily reduced.

[0055] Specifically, as examples of the carbon atom-containing reducing agent, graphite that can reduce 2 moles of oxides of valuable metals such as copper oxides or nickel oxides per 1 mole of carbon can be given. Also, as the supply source of carbon, a hydrocarbon that can reduce 2 moles to 4 moles of valuable metal oxides per 1 mole of carbon, or carbon monoxide that can reduce 1 mole of valuable metal oxides per 1 mole of carbon, or the like can be added. Thus, by performing the reduction melting treatment in the presence of carbon as the reducing agent, the valuable metals can be efficiently reduced, and the molten metal containing the valuable metals can be more efficiently obtained. Also, compared to, for example, the case of using an aluminothermic reaction that uses a metal powder such as aluminum as the reducing agent to perform reduction, the reduction treatment using carbon has the advantage of being very safe.

[0056] Note that, in the case where carbon is added as the reducing agent, an excess amount of carbon can also be added. When the amount of carbon added is too much, in the case where the waste lithium ion battery contains a compound of phosphorus, there is a possibility that the phosphorus is reduced by the carbon and contained in the molten alloy phase, and by adding an oxidizing agent as necessary and melting the waste lithium ion battery in the presence of a flux, the phosphorus can be incorporated into the flux to be removed.

[0057] As the heating temperature (melting temperature) in the melting treatment, there is no particular limitation, and it is preferable to be 1300°C or higher, and more preferably 1350°C or higher. By performing the melting treatment at a temperature of 1300°C or higher, the valuable metals such as copper, cobalt, and nickel are efficiently melted, and a molten alloy is formed in a state where the fluidity is sufficiently improved. Thus, the separation efficiency of the valuable metals from the impurity components in the later-described slag separation process S5 can be improved. Note that, when the heating temperature is less than 1300°C, the separation efficiency of the valuable metals from the impurities can possibly be insufficient. Also, as the upper limit value of the heating temperature in the melting treatment, it is preferable to be 1500°C or lower. When the heating temperature is greater than 1500°C, the thermal energy is wasted, the consumption of the refractory materials such as the crucible and the furnace wall becomes intense, and the productivity can possibly decrease.

[0058] In addition, in the heating in the melting treatment, the fluidity of the melt is low at the stage of reaching the heating temperature, and there are molten residues, so it is necessary to maintain the heating temperature for 30 minutes or more, for example. Note that it is preferable to finally observe the inside of the crucible and confirm whether or not the melt has been completed using an iron measuring rod. After melting, the molten metal and the slag whose fluidity has become high are separated in the crucible according to their specific gravities, with the lower layer being the metal and the upper layer being the slag. At this time, after collecting the supernatant slag using the iron measuring rod, cooling and pulverization treatment are performed.

[0059] Note that in the melting treatment, dust, exhaust gas, and the like are sometimes generated, but can be rendered harmless by performing exhaust treatment that has been known in the past.

[0060] [Slag separation process]

[0061] In the slag separation process S5, the slag is separated from the reduction product obtained in the melting process S4 to recover the molten metal containing valuable metals. As described above, the molten metal and the slag as the reduction product are separated in the crucible due to the difference in specific gravity, so the slag can be separated and the molten metal can be recovered efficiently.

[0062] [Oxidation purification process]

[0063] In the oxidation purification process S6, the molten metal recovered is subjected to oxidation melting treatment to oxidize and remove impurities such as manganese, and to purify the molten metal. Specifically, in the oxidation melting treatment, heating is performed to a temperature at which the molten metal is maintained in a molten state, and an oxidizing agent such as air is blown into the molten metal. Thereby, the impurities mainly manganese contained in the molten metal can be oxidized and effectively distributed to the slag, and the metal can be purified.

[0064] Here, in the method of the present embodiment, it is characterized that in the oxidation purification process S6, the oxidation melting treatment is performed with the addition of silicon dioxide (Si02) as a flux to the molten metal, and at this time, the Si02 / MnO weight ratio in the generated slag is set to be 0.4 or more and 1.0 or less.

[0065] As described above, regarding the amount of addition of Si02, when the Si02 / MnO weight ratio is set to be less than 0.4, the melting point of the generated slag increases, the viscosity of the slag increases in the case of the same working temperature, and the entrainment of the slag into the metal increases. In addition, when the Si02 / MnO weight ratio is set to be more than 1.0, similarly, the melting point of the generated slag also increases, the viscosity of the slag increases in the case of the same working temperature, and the entrainment of the slag into the metal increases. In addition to this, since the amount of Si02 added as a flux increases, the use cost of the flux increases, or the slag treatment cost increases due to the increase in the amount of slag.

[0066] By purifying the molten metal from which the impurity manganese is removed by the oxidative melting treatment, a MnO-SiO2-based slag having a low melting point can be produced, and an increase in the viscosity of the slag can be suppressed. Thus, manganese can be effectively distributed to the slag, and the entrainment of the metal into the slag can be reduced, preventing a decrease in the recovery rate of the valuable metal.

[0067] Example

[0068] Hereinafter, examples of the present application are given to explain more specifically, and the present application is not limited by any of the following examples.

[0069] Recovery treatment of valuable metals (Examples, Comparative Examples)

[0070] (Pretreatment process of waste batteries)

[0071] As the charge containing at least lithium, manganese, and valuable metals, a raw material containing waste lithium ion batteries (18650 type cylindrical batteries, used batteries of square batteries for vehicles, and defective products recovered in a battery manufacturing process) was prepared. After the waste lithium ion batteries were immersed in brine and discharged, the moisture was scattered and calcination was performed in the atmosphere at a temperature of 260°C to decompose and remove the electrolyte and the outer can, and the battery contents were obtained.

[0072] (Pulverization process)

[0073] Then, the battery contents were pulverized using a pulverizer (trade name: GOOD CUTTER, manufactured by Shigekiya Mfg. Co., Ltd.) to obtain a pulverized product.

[0074] (Preheating process)

[0075] Then, the obtained pulverized product was charged into a rotary kiln, and oxidation calcination was performed in the atmosphere at a preheating temperature of 800°C for 180 minutes.

[0076] (Melting process)

[0077] The pulverized product after the oxidation calcination was charged into an alumina crucible, and reduction melting treatment was performed at a heating temperature (reduction temperature) of 1400°C. In the reduction melting treatment, calcium oxide as a flux was added to the pulverized product. In addition, graphite powder as a reducing agent was added and mixed to adjust the oxidation-reduction degree. In addition, in the reduction melting treatment, the temperature was raised to the heating temperature by a resistance heating furnace, and after confirming that the molten state was reached with a measuring rod, the molten state was maintained for 40 minutes.

[0078] (Slag separation process)

[0079] The reduction product of the molten metal and the slag obtained by the reduction melting treatment is separated into the slag using the difference in specific gravity, and the molten metal is recovered.

[0080] (Oxidation purification step)

[0081] Then, the molten metal is recovered, and the molten metal is subjected to an oxidation melting treatment to oxidize and remove the impurity manganese, thereby purifying the molten metal. In the oxidation melting treatment, SiO2is added as a fluxing agent to the molten metal.

[0082] Specifically, SiO2is added in an amount such that the SiO2 / MnO weight ratio in the slag generated by the oxidation melting becomes the weight ratio shown in Table 1 below in each test. In the oxidation melting treatment, a crucible composed of a MgO carbon particle heating tube having an outer diameter of 40 mm, an inner diameter of 34 mm, and a height of 150 mm is used. The molten metal charged in the crucible is heated at a temperature of 1400°C, an alumina tube having an inner diameter of 5 mm and an outer diameter of 8 mm is inserted into the molten metal, and the oxidation removal of manganese is performed while air is blown from the alumina tube at a flow rate of 0.72 L / min for 80 minutes. Note that the amount of air is appropriately adjusted so that the molten metal does not splash.

[0083] Results

[0084] The results of the manganese (Mn) grade in the metal and the recovery rate of the valuable metal (Ni-Co-Cu alloy) obtained in each test are shown in Table 1 below. Note that the recovery rate of the valuable metal refers to the percentage of the amount of the valuable metal (Ni-Co-Cu metal) obtained after the treatment with respect to the amount of the valuable metal (Ni-Co-Cu metal) charged in the oxidation purification step.

[0085] Table 1

[0086]

[0087] As shown in the results of Table 1, in Examples 1 and 2 in which SiO2was added so that the SiO2 / MnO weight ratio in the generated slag became 1.0 and 0.45, respectively, in the oxidation purification step, the manganese grade in the molten metal was reduced, and the recovery rate of the obtained Ni-Co-Cu metal was the highest.

[0088] On the other hand, in Comparative Example 1 in which SiO2was not added as a fluxing agent, Comparative Example 2 in which SiO2was added so that the SiO2 / MnO weight ratio in the slag became in the range of less than 0.4 and greater than 1.0, and Comparative Example 3, the viscosity of the purified slag increased, causing the entrapment of the metal into the slag, and the recovery rate of the obtained Ni-Co-Cu alloy decreased.

Claims

1. A method for producing a valuable metal, which is a method for producing the valuable metal from a raw material containing at least lithium, manganese, and the valuable metal, wherein, comprises: a reduction melting process of subjecting the raw material to a reduction melting treatment to obtain a reduction product containing molten metal containing a valuable metal and a slag; a slag separation process of recovering the molten metal from the reduction product; and an oxidation purification process of subjecting the recovered molten metal to an oxidation melting treatment by adding silica SiO2 as a flux, in the oxidation purification process, the SiO2 as the flux is added so that the weight ratio of SiO2 / MnO in the slag becomes 0.4 or more and 1.0 or less.

2. The method of producing a valuable metal according to claim 1, wherein the content of the manganese contained in the raw material is 15 mass% or less.

3. The method of producing a valuable metal according to claim 1 or 2, wherein a pre-heating process of heating the raw material to perform oxidation roasting is further provided, in the reduction melting process, the reduction melting treatment is performed on the raw material after the oxidation roasting.

4. The method of producing a valuable metal according to claim 1 or 2, wherein the raw material contains a waste lithium ion battery. ​

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