Starting material for dry smelting, method for producing starting material for dry smelting, method for producing valuable metal using said starting material for dry smelting, and method for producing nickel sulfate and / or cobalt sulfate

Abstract

The present invention provides a starting material for dry smelting, with which it is possible to efficiently produce a metal that contains a valuable metal, while suppressing the discharge amount of carbon dioxide.　A starting material for dry smelting according to the present invention contains carbon (C) and at least one valuable metal selected from among nickel (Ni) and cobalt (Co), and has a C content of 25% by mass or less and C / (Ni + Co) of 2.5 or less. This starting material for dry smelting can be produced by a method which includes: a step for preparing a starting material that contains carbon and at least one valuable metal selected from among Ni and Co; a first classification step for subjecting the starting material to classification so as to divide the starting material into a coarse grain powder A1 that contains the valuable metal and a fine grain powder A2; and a second classification step for subjecting the fine grain powder A2 to classification so as to divide the fine grain powder into a coarse grain powder B1 and a fine grain powder B2. Specifically, the coarse grain powder A1 and the coarse grain powder B1 are recovered so as to be used as a starting material for dry smelting.

Description

Pyrometallurgical raw materials, method for producing pyrometallurgical raw materials, method for producing valuable metals using the pyrometallurgical raw materials, and method for producing nickel sulfate and / or cobalt sulfate

[0001] The present invention relates to a raw material for pyrometallurgy, a method for producing a raw material for pyrometallurgy, a method for producing valuable metals using the raw material for pyrometallurgy, and a method for producing nickel sulfate and / or cobalt sulfate.

[0002] In recent years, as environmental regulations have become stricter, renewable energy has been attracting a great deal of attention, with lithium-ion batteries in particular attracting attention as lightweight, high-power secondary batteries.

[0003] A typical lithium-ion battery has a structure in which an external can contains a negative electrode material, a positive electrode material, a separator, and an electrolyte. For example, the external can is made of a metal such as aluminum (Al) or iron (Fe). The negative electrode material is made of a negative electrode active material (graphite, etc.) fixed to a negative electrode current collector (copper foil, etc.). The positive electrode material is made of a positive electrode active material (lithium nickel oxide, lithium cobalt oxide, etc.) fixed to a positive electrode current collector (aluminum foil, etc.). The separator is made of a porous resin film such as polypropylene. The electrolyte is made of lithium hexafluorophosphate (LiPF ６ ) and other electrolytes.

[0004] One of the main uses of lithium-ion batteries is in hybrid and electric vehicles. Therefore, it is expected that a large amount of lithium-ion batteries installed in these vehicles will be discarded in the future as they reach the end of their lifecycle. In addition, some lithium-ion batteries are discarded as defective during manufacturing. There is a demand for recycling these used batteries and batteries that are defective during manufacturing (hereinafter referred to as "waste lithium-ion batteries") as resources.

[0005] One proposed recycling method is a pyrometallurgical process in which all used lithium-ion batteries are melted in a high-temperature furnace. The pyrometallurgical process involves melting shredded used lithium-ion batteries to separate and recover valuable metals, such as cobalt (Co), nickel (Ni), and copper (Cu), from low-value-added metals, such as iron (Fe) and aluminum (Al), by utilizing the difference in oxygen affinity between them. In this process, low-value-added metals are oxidized as much as possible to produce slag, while valuable metals are recovered as alloys by minimizing their oxidation.

[0006] For example, Patent Document 1 discloses a method for recovering valuable metals from waste lithium-ion batteries using a pyrometallurgical process. However, conventional pyrometallurgical processes involve burning a large amount of carbon to melt the metals and then reducing the metal oxides in a strongly reducing atmosphere using the large amount of carbon, which results in the emission of a large amount of carbon dioxide during the process. Furthermore, the resulting alloy of valuable metals (hereinafter also referred to as "valuable metal alloy") may contain a large amount of impurities, which complicates the subsequent hydrometallurgical process and increases the refining costs for recovering valuable metals.

[0007] Furthermore, Patent Document 2 discloses a method for recovering valuable metals by a process centered on solvent extraction in a wet environment. However, such a treatment technique that relies solely on a hydrometallurgical process still has significant problems. Specifically, in a hydrometallurgical process, a leaching treatment using an acid such as sulfuric acid dissolves not only valuable metals but also impurities, necessitating the use of a large amount of acid and neutralizing agent. Furthermore, numerous solvent extraction steps are required to isolate each metal element. Thus, a valuable metal recovery treatment that relies solely on a hydrometallurgical process has the problem of extremely high costs for smelting for recovery.

[0008] Patent Document 3 also discloses a method for recovering nickel and cobalt from the magnetized materials with a high yield and removing copper from the non-magnetized materials by magnetically separating the raw materials in advance. However, this method fails to recover copper, a valuable metal, and requires the addition of a reducing agent to reduce the oxidized nickel and cobalt in the subsequent dry smelting process. Furthermore, adding silicon dioxide or the like as a reducing agent makes the slag less soluble and reduces the lithium concentration in the slag. For these reasons, while it is preferable to use carbon as a reducing agent, it is desirable to reduce its amount in terms of carbon dioxide emissions.

[0009] Patent Document 4 discloses a method for roasting and crushing waste lithium-ion batteries to separate and separate valuable metals. The resulting processed material is known to contain approximately 50% by mass of valuable metals such as nickel, cobalt, and copper, and approximately 30% by mass of carbon.

[0010] JP 2017-526820 A JP 2020-105599 A JP 2022-18616 A JP 2019-171267 A

[0011] The present invention has been proposed in view of the above-described conventional circumstances, and aims to provide a raw material for pyrometallurgy, a method for producing the raw material for pyrometallurgy, and a method for producing valuable metals using the raw material for pyrometallurgy, which can efficiently produce metals containing valuable metals while suppressing carbon dioxide emissions.

[0012] The present inventors have conducted extensive research to solve the above-mentioned problems, and as a result, in a method for producing valuable metals contained in raw materials by reducing and melting the raw materials, they have focused on the carbon (C) content of the raw materials (raw materials for pyrometallurgy) used and the ratio expressed as C / (Ni+Co), and found that when these are within a specific range, metals containing valuable metals can be efficiently produced while suppressing carbon dioxide emissions, which led to the completion of the present invention.

[0013] (1) A first aspect of the present invention is a raw material for pyrometallurgy, which contains at least one valuable metal selected from nickel (Ni) and cobalt (Co) and carbon (C), in which the C content is 25 mass% or less and the C / (Ni+Co) ratio is 2.5 or less.

[0014] (2) A second aspect of the present invention is a raw material for pyrometallurgy according to the first aspect, wherein the average particle size is 270 μm or more.

[0015] (3) A third aspect of the present invention is the raw material for pyrometallurgy, according to the first or second aspect, wherein the C content is 15 mass% or less.

[0016] (4) A fourth aspect of the present invention is a method for producing a raw material for dry smelting according to the first aspect of the present invention, comprising: a preparation step of preparing a starting material containing at least one valuable metal selected from the group consisting of nickel (Ni) and cobalt (Co) and carbon (C); a first classification step of classifying the starting material into coarse powder A and fine powder A containing the valuable metal; and a second classification step of classifying the fine powder A into coarse powder B and fine powder B, wherein the coarse powder A obtained from the first classification step and the coarse powder B obtained from the second classification step are recovered and used as a raw material for dry smelting.

[0017] (5) A fifth aspect of the present invention is a method for producing a raw material for pyrometallurgy, according to the fourth aspect, wherein in the first classification step, classification treatment is carried out with a classification point of 50 μm to 250 μm.

[0018] (6) A sixth aspect of the present invention is a method for producing a raw material for pyrometallurgy, according to the fifth aspect, wherein in the second classification step, classification treatment is carried out with a classification point of 25 μm or more.

[0019] (7) A seventh aspect of the present invention is a method for producing valuable metals or alloys containing valuable metals from a pyro-smelting raw material containing the valuable metal, the method comprising: a reduction-melting step of reducing and melting the pyro-smelting raw material; and using the pyro-smelting raw material according to the first aspect as the pyro-smelting raw material.

[0020] (8) An eighth aspect of the present invention is a method for producing valuable metals according to the seventh aspect, which includes a raw material preparation step of preparing the raw material for pyrometallurgy from a starting material containing valuable metals, in which the raw material preparation step prepares the raw material for pyrometallurgy by carrying out the method described in claim 3, and the obtained raw material for pyrometallurgy is subjected to the reduction melting step.

[0021] (9) A ninth aspect of the present invention is a method for producing valuable metals according to the seventh or eighth aspect of the present invention, wherein the starting material includes detoxified battery powder obtained by burning used lithium-ion batteries to render them harmless and pulverizing them to a predetermined size.

[0022] (10) A tenth aspect of the present invention is a method for producing valuable metals according to any one of the seventh to ninth aspects, wherein the reducing and melting step involves subjecting the dry smelting raw materials to a reducing and melting treatment in a melting furnace to obtain a reducing melt containing slag and a metal containing the valuable metal.

[0023] (11) An eleventh aspect of the present invention is a method for producing nickel sulfate and / or cobalt sulfate using the raw material for pyrometallurgy according to the first aspect, the method comprising: a dry treatment step of producing the valuable metal or an alloy containing the valuable metal by a dry treatment process using the raw material for pyrometallurgy; and a hydrotreatment step of producing nickel sulfate and / or cobalt sulfate from the valuable metal or the alloy containing the valuable metal obtained in the dry treatment step through a hydrotreatment process including a leaching treatment with sulfuric acid.

[0024] (12) A twelfth aspect of the present invention is a method for producing nickel sulfate and / or cobalt sulfate according to the eleventh aspect, wherein the raw material for pyrometallurgy contains nickel (Ni) and cobalt (Co), and a mixed aqueous solution of nickel sulfate and cobalt sulfate is produced through a hydrometallurgy process in the hydrometallurgy step.

[0025] (13) A thirteenth aspect of the present invention is a method for producing nickel sulfate and / or cobalt sulfate according to the eleventh or twelfth aspect, wherein in the dry treatment step, the raw material for dry smelting is subjected to a reduction melting treatment in a melting furnace to obtain a reduced product containing a metal containing the valuable metal and slag, and the slag is separated from the reduced product to obtain the valuable metal or an alloy containing the valuable metal.

[0026] According to the present invention, it is possible to provide a raw material for pyrometallurgy, a method for producing the raw material for pyrometallurgy, and a method for producing valuable metals using the raw material for pyrometallurgy, which can efficiently produce metals containing valuable metals while suppressing carbon dioxide emissions.

[0027] 1 is a process diagram showing an example of the flow of a method for producing a raw material for pyrometallurgy.

[0023] FIG. 2 is a process diagram showing an example of the flow of a method for producing valuable metals.

[0028] A specific embodiment of the present invention (hereinafter referred to as "the present embodiment") will be described in detail below. Note that the present invention is not limited to the following embodiment, and various modifications are possible within the scope of the present invention.

[0029] <1. Raw material for pyrometallurgy> (1) Regarding raw material for pyrometallurgy The raw material for pyrometallurgy according to this embodiment contains valuable metals and is a processing raw material for a smelting process that is subjected to a dry process such as a reduction melting process to produce the valuable metals contained in the raw material.

[0030] Specifically, the pyrometallurgical raw material contains at least one valuable metal selected from nickel (Ni) and cobalt (Co), and carbon (C). The pyrometallurgical raw material has a C content of 25 mass% or less and a C / (Ni+Co) ratio of 2.5 or less.

[0031] Such a raw material for pyrometallurgy can reduce the amount of carbon dioxide emitted during dry processes such as reduction melting and oxidizing roasting. Furthermore, since the ratio expressed as C / (Ni+Co) is 2.5 or less, valuable metals such as nickel and cobalt can be effectively reduced by dry processes, preventing these valuable metals from being distributed as oxides to slag and suppressing a decrease in the production yield of valuable metals.

[0032] The ratio represented by C / (Ni+Co) is preferably 1.0 or less, more preferably 0.8 or less, and even more preferably 0.6 or less. In particular, when the ratio of C / (Ni+Co) is 0.6 or less, valuable metals such as nickel and cobalt can be reduced more effectively, and the reduction of impurity metals that are not the target of recovery can be suppressed, which leads to a reduction in the number of steps in the wet treatment process after the dry treatment process, for example.

[0033] The lower limit of the ratio C / (Ni+Co) is preferably 0.2 or more. By setting the ratio to 0.2 or more, it is possible to prevent valuable metals such as nickel and cobalt from being reduced insufficiently.

[0034] As described above, the carbon (C) content is 25% by mass or less. This makes it possible to reduce the amount of carbon dioxide emitted during dry treatments such as reduction melting and oxidation roasting. The C content is preferably 20% by mass or less, and more preferably 15% by mass or less.

[0035] The lower limit of the C content is preferably 2% by mass or more. By setting the C content to 2% by mass or more, it is possible to prevent valuable metals such as nickel and cobalt from being reduced insufficiently.

[0036] The pyrometallurgical smelting raw material may contain metal elements other than the above-mentioned valuable metals. For example, other metal elements include iron (Fe) and aluminum (Al). However, the Fe content in the pyrometallurgical smelting raw material is preferably 2% by mass or less. Furthermore, the Al content in the pyrometallurgical smelting raw material is preferably 1% by mass or less. By preferably having the Fe content and Al content in the above-mentioned ranges, it is possible to suppress the generation of excessive slag through the pyrometallurgical treatment process.

[0037] Here, the raw material for pyrometallurgy preferably has an average particle size of 270 μm or more. In this specification, the average particle size refers to the average particle size measured by measuring 1,000 powder particles using a laser light diffraction / scattering particle size distribution analyzer (model LA950V2) manufactured by Horiba.

[0038] As will be described in detail later, the pyrometallurgical raw material according to this embodiment can be produced by using, for example, a raw material containing waste lithium-ion batteries as a starting material, pulverizing the waste lithium-ion batteries, deactivating them by heating, and then performing a predetermined classification process. The pyrometallurgical raw material is composed of the coarse powder (the powder with a larger particle size) obtained by the classification process and separating the coarse powder from the fine powder. This coarse powder contains a large amount of valuable metals and a small amount of carbon (C), which is easily pulverized by pulverization.

[0039] For this reason, a raw material for pyrometallurgy, preferably having an average particle size of 270 μm or more, stably satisfies the above-mentioned composition, i.e., the relationship that the C concentration is 25 mass% or less and C / (Ni+Co) is 2.5 or less.

[0040] In this specification, the metal content is a value measured using an ICP optical emission spectrometer (manufactured by Agilent Technologies, model ICP-OES Agilent 5900), and the carbon (C) content is a value measured using a carbon / sulfur analyzer (model CS844) manufactured by LECO Corporation.

[0041] (2) Method for Producing Raw Materials for Pyrometallurgy The raw materials for pyrometallurgy having the above-described characteristic compositions can be produced by the following method.

[0042] 1 is a process diagram showing an example of the flow of a method for producing a pyrometallurgical raw material according to the present embodiment. The method for producing a pyrometallurgical raw material comprises a preparation step S0 of preparing a starting material containing at least one valuable metal selected from nickel (Ni) and cobalt (Co) and carbon (C), and a preparation step S1 of preparing (producing) a pyrometallurgical raw material from the starting material.

[0043] In addition, the preparation step S1 for preparing the raw material for pyrometallurgy is a step of classifying the starting material to obtain a coarse powder A containing valuable metals. １ and fine powder A ２ and the first classification step S11, which divides the obtained fine powder A into ２ Coarse powder B is obtained by classifying the powder. １ and fine powder B ２ The preparation step S1 includes a second classification step S12 for dividing the coarse powder A obtained from the first classification step S11 into １ and the coarse powder B obtained from the second classification step S12. １ and are recovered as raw materials for pyrometallurgy.

[0044] (2-1) Preparation Step In the preparation step S0, a starting material containing at least one valuable metal selected from nickel (Ni) and cobalt (Co) and carbon (C) is prepared.

[0045] The starting material is not particularly limited as long as it contains at least one valuable metal, such as nickel or cobalt, and carbon, and examples thereof include raw materials containing waste lithium-ion batteries. Waste lithium-ion batteries refer to used batteries and defective batteries generated during battery manufacturing. These waste lithium-ion batteries contain valuable metals, such as nickel and cobalt, as components constituting the cathode material, and also contain copper (Cu) as a valuable metal. Furthermore, waste lithium-ion batteries contain carbon as a component constituting the anode material, etc.

[0046] As described above, the starting material may be a waste lithium-ion battery or the like, and contains at least one valuable metal, i.e., nickel or cobalt. The total content of nickel and cobalt in the starting material is not particularly limited, but is preferably 10% by mass or more, and more preferably 15% by mass or more. By producing a raw material for pyrometallurgy from a starting material containing valuable metals in such amounts, and then using the raw material for pyrometallurgy to undergo a recovery process, such as a pyrotreatment process, valuable metals can be effectively recovered.

[0047] The starting material is not limited to waste lithium-ion batteries, but may also be waste electronic components containing valuable metals such as nickel and cobalt, ore, etc. The valuable metals in the starting material may be present in the form of a compound such as an oxide, or in the form of an alloy. The starting material may also contain organic or inorganic substances other than those mentioned above. Furthermore, the shape of the starting material is not particularly limited, and may be particulate or other shapes.

[0048] For example, when raw materials containing used lithium-ion batteries are used as starting materials, in the preparation step S0, the used lithium-ion batteries constituting the starting material are detoxified by combustion and crushed to a predetermined size to produce detoxified battery powder. Because used lithium-ion batteries have a sealed structure and contain an electrolyte, crushing them in their original state poses a risk of explosion and is therefore dangerous. Therefore, it is preferable to perform a detoxification process that removes or deactivates the electrolyte in some way. The detoxification process can be performed, for example, by burning the used lithium-ion batteries.

[0049] After the waste lithium-ion batteries are detoxified, they are crushed into small particles and then classified by sieving or other methods to produce a powder (detoxified battery powder) with a particle size of several millimeters or less. By classifying and recovering the powder with a particle size of several millimeters or less by sieving or other methods, a starting material with reduced amounts of excess iron (Fe) and aluminum (Al) can be obtained. In the dry treatment process, metal components such as iron and aluminum contained in the raw material are oxidized and distributed in the slag, so it is preferable for the content of these components to be low from the raw material stage. The classification point in the sieving or other treatment in the preparation step S0 is not particularly limited, but is preferably approximately 3.0 mm, more preferably approximately 2.4 mm, and even more preferably approximately 1.0 mm.

[0050] (2-2) Preparation Step The preparation step S1 is a step of preparing (producing) raw materials for pyrometallurgy from prepared starting materials. As shown in FIG. 1, the preparation step S1 is a step of preparing (producing) raw materials for pyrometallurgy from prepared starting materials. １ and fine powder A ２ and the first classification step S11, which divides the obtained fine powder A into ２ Coarse powder B is obtained by classifying the powder. １ and fine powder B ２ and a second classification step S12 of classifying the raw material into the raw material and the raw material.

[0051] In the preparation step S1, the coarse powder A obtained in the first classification step S11 is １ and the coarse powder B obtained from the second classification step S12. １ and are recovered as raw materials for pyrometallurgy.

[0052] As described above, the resulting pyrometallurgical raw material contains at least one valuable metal selected from nickel (Ni) and cobalt (Co) and carbon (C), with a C content of 25 mass% or less and a C / (Ni+Co) ratio of 2.5 or less. Therefore, the method for producing a pyrometallurgical raw material according to this embodiment makes it possible to produce a pyrometallurgical raw material that can reduce the amount of carbon dioxide emitted during dry treatments such as reduction melting and oxidizing roasting. Furthermore, it is possible to produce a pyrometallurgical raw material that can effectively reduce valuable metals such as nickel and cobalt through dry treatment, thereby preventing the valuable metals from being distributed as oxides to the slag and suppressing a decrease in the production yield of valuable metals.

[0053] The particle size of the powder recovered by the classification process is based on the classification point in the classification process, and the particle size of the powder does not necessarily have to be a predetermined value. Controlling the particle size of the powder means controlling the classification point in each classification process.

[0054] [First Classification Step] In the first classification step S11, the starting material prepared in the preparation step S0 is subjected to classification at a predetermined classification point (first classification point) to obtain a coarse powder A containing valuable metals. １ and fine powder A ２ Divide into:

[0055] The classification method is not particularly limited, and examples thereof include methods using a vibrating sieve, a multistage vibrating sieve, a dry cyclone, a wet vibrating table, an air table, an elbow jet classifier, an aero fine classifier, a dry fine powder classifier, a hydrocyclone, a concentrator, a gravity separator, a laboratory mineral separator, etc. Among these, a method using a vibrating sieve is preferred because it allows for inexpensive processing and is easy to operate.

[0056] The classification point (first classification point) of the classification process in the first classification step S11 is not particularly limited and can be appropriately designed depending on the composition of the starting material. Specifically, for example, the classification point is preferably set in the range of 50 μm to 250 μm, more preferably in the range of 50 μm to 150 μm, and even more preferably in the range of 75 μm to 100 μm. By setting the first classification point in the range of 50 μm to 250 μm, the coarse powder A containing valuable metals such as nickel and cobalt can be obtained. １ It is possible to effectively recover the carbon-containing fine powder A and improve the yield. ２ Furthermore, the accuracy of the classification process in the next second classification step S12 can be improved.

[0057] In the classification process in the first classification step S11, the coarse powder A obtained on the classification point (i.e., on the sieve) １ is then used as a raw material for pyrometallurgy. On the other hand, fine powder A obtained below the classification point (i.e., undersieve) ２ is transferred to the second classification step S12 to be classified again.

[0058] Here, coarse powder A １ As for the concentration of valuable metals, it is preferable that the concentration of (Ni+Co) (total concentration of valuable metals nickel and cobalt) is 40 mass % or more.

[0059] [Second Classification Step] In the second classification step S12, the fine powder A obtained below the classification point by the classification treatment in the first classification step S11 is ２ The coarse powder B is then classified again at a predetermined classification point (second classification point). １ and fine powder B ２ Divide into:

[0060] The classification method is not particularly limited, and examples thereof include methods using a vibrating sieve, a multistage vibrating sieve, a dry cyclone, a wet vibrating table, an air table, an elbow jet classifier, an aero fine classifier, a dry fine powder classifier, a hydrocyclone, a concentrator, a gravity separator, a laboratory mineral separator, etc. Among these, methods using an elbow jet or a dry cyclone are preferred because they allow for more effective and efficient removal of fine carbon.

[0061] The classification point (second classification point) of the classification treatment in the second classification step S12 is not particularly limited, and may vary depending on the composition of the starting material, the processing result in the first classification step, the fine powder A, ２ Specifically, for example, it is preferable to set the classification point at 25 μm or more, and more preferably at 30 μm or more. By setting the second classification point at 25 μm or more, the coarse powder B obtained by separation can be １ The quality of valuable metals such as nickel and cobalt can be improved, and the coarse powder B １ This can prevent carbon (C) from being mixed into the mold.

[0062] In the classification process in the second classification step S12, the coarse powder B obtained on the classification point (i.e., on the sieve) １ The coarse powder B is then used as a raw material for pyrometallurgy. １ is the coarse powder A recovered in the first classification step S11 １ It may be mixed with the above and used as a raw material for pyrometallurgy, or it may be used alone as a raw material for pyrometallurgy.

[0063] On the other hand, fine powder B obtained below the classification point (i.e., under the sieve) ２ contains a relatively large amount of carbon and is not very suitable as a raw material for pyrometallurgy. ２ The magnetic particles such as nickel and cobalt (fine powder B) are separated by magnetic separation. ２ The fine powder B may be recovered and used as a raw material for pyrometallurgy. ２ Since lithium, a valuable metal, may be present in a few percent of fine powder B,２ The fine powder B may be subjected to acid leaching to recover lithium. ２ Since it has a high carbon (C) concentration, it can be effectively used as a heat source or reducing agent.

[0064] In addition, fine powder B ２ The magnetic separation treatment for the raw material (fine powder B) can be carried out by a known method such as a contact method using a permanent magnet or an electromagnet, or a non-contact method. Examples of magnetic separators used for the treatment include a drum type magnetic separator and a counter pole type magnetic separator. The treatment conditions such as magnetic flux density and partition position can also be determined by the raw material (fine powder B). ２ ) can be appropriately designed. The magnetic separation treatment may be performed in one stage or in multiple stages. By performing the treatment in two or more stages, carbon can be removed more effectively and valuable metals can be concentrated.

[0065] The valuable metal powders of nickel and cobalt recovered by such magnetic separation treatment are referred to as coarse powder A. １ Coarse powder B １ It can be effectively used as a raw material for pyrometallurgy, similarly to the above. Carbon is not magnetic and is not magnetized by magnetic separation treatment, but it may be mixed in a small amount with nickel or cobalt into the magnetized material. However, even if carbon is mixed in the magnetized material, it is at most about 10 mass % and is not included in the raw material for pyrometallurgy (coarse powder A). １ , coarse powder B １ ) can be mixed with it without any problems.

[0066] <2. Method for Producing Valuable Metals by a Pyrometallurgical Process> Next, a method for producing valuable metals by a pyrometallurgical process (pyrometallurgical process) using the above-described raw materials for pyrometallurgy will be described.

[0067] 2 is a process diagram showing an example of the flow of a valuable metal production method according to this embodiment. The valuable metal production method is a method for producing a valuable metal or an alloy (valuable metal alloy) made of the valuable metal from a pyrometallurgical raw material containing the valuable metal. The valuable metal is at least one of nickel (Ni) and cobalt (Co).

[0068] Specifically, the method for producing valuable metals includes a reduction melting step S2 in which the pyrometallurgical raw materials are reduced and melted. In the reduction melting step S2, the pyrometallurgical raw materials are subjected to a reduction melting process in a melting furnace, thereby obtaining a reduced product (reduced melt) containing slag and metals including valuable metals. Then, in a slag separation step S3, the slag is separated from the reduced product, thereby recovering valuable metals or alloys containing valuable metals.

[0069] As shown in the process flow diagram of FIG. 2, in the method for producing valuable metals, a raw material for pyrometallurgy can be prepared via a raw material preparation step S1 in which a raw material for pyrometallurgy can be prepared from a starting material containing valuable metals.

[0070] The method for producing valuable metals according to this embodiment is characterized in that the pyrometallurgical raw material described in detail above is used as the pyrometallurgical raw material to be subjected to the reduction melting step S2, which is a pyrometallurgical treatment process. That is, the pyrometallurgical raw material to be subjected to the reduction melting step S2 contains at least one valuable metal selected from nickel (Ni) and cobalt (Co) and carbon (C), with a C content of 25 mass% or less and a C / (Ni+Co) ratio of 2.5 or less.

[0071] Therefore, according to the method for producing valuable metals using such raw materials for pyrometallurgy, it is possible to reduce the amount of carbon dioxide emitted during dry processes such as reduction melting. Furthermore, valuable metals such as nickel and cobalt can be effectively reduced by dry processes, which prevents the valuable metals from being distributed as oxides to the slag, thereby suppressing a decrease in the production yield of valuable metals.

[0072] (1) Raw Material Preparation Step As described above, the raw material for pyrometallurgy is used as the raw material for pyrometallurgy to be treated in the reduction melting step S2, as described in detail above. Therefore, the treatment in the raw material preparation step S1 corresponds to the method for producing raw materials for pyrometallurgy, as described in detail above. For this reason, the preparation step S1 in the method for producing raw materials for pyrometallurgy, as well as the raw material preparation step S1, will both be referred to as "S1," and a detailed description thereof will be omitted.

[0073] The raw material preparation step S1 is composed of a preparation step S0 of preparing a starting material containing at least one valuable metal selected from nickel (Ni) and cobalt (Co) and carbon (C), and a preparation step S1 of preparing (manufacturing) a raw material for pyrometallurgy from the starting material. The preparation step S1 also includes a classification process for the starting material to produce a coarse powder A containing valuable metals. １ and fine powder A ２ and a first classification step S11 for separating fine powder A. ２ Coarse powder B is obtained by classifying the powder. １ and fine powder B ２ and a second classification step S12 of classifying the raw material into the raw material and the raw material.

[0074] In the raw material preparation step S1, the coarse powder A obtained in the first classification step S11 is １ and the coarse powder B obtained from the second classification step S12. １ and are recovered as raw materials for pyrometallurgy.

[0075] The starting material may be a waste lithium-ion battery containing at least one valuable metal, such as nickel (Ni) or cobalt (Co). When a waste lithium-ion battery is used, the battery is rendered harmless by combustion and crushed to a predetermined size to prepare a detoxified battery powder, which is then subjected to classification (first classification step S11, second classification step S12).

[0076] (2) Reduction Melting Step In the reduction melting step S2, the raw materials for pyrometallurgy are charged into a melting furnace and subjected to reduction melting treatment. This produces a reduced product (reduction melt product) containing slag and metals including valuable metals. In other words, the reduction melting step S2 is a step in which a pyrometallurgical treatment process is carried out.

[0077] Specifically, in the reduction melting process in the reduction melting step S2, the raw materials for pyrometallurgy are heated to a high temperature and melted, thereby reducing metal oxides and the like. As a result, nickel oxide and cobalt oxide are reduced and discharged as metals (mixed metals), and valuable metals or alloys of these valuable metals (valuable metal alloys) are produced. Furthermore, in the reduction melting process, impurity metal elements that are not valuable metals are not reduced, but are separated from the valuable metals as slag in the form of oxides. In this way, the reduction melting process maintains low-value-added metals as oxides, while reducing and melting valuable metals (Ni, Co, etc.) to recover them as metals.

[0078] Carbon (C) is a highly suitable reducing agent for reducing the valuable metals to be recovered, such as nickel (Ni) and cobalt (Co). For example, one mole of carbon can reduce two moles of valuable metal oxide. The metals reduced by carbon depend on the affinity of each metal with oxygen. Generally, aluminum (Al), lithium (Li), carbon (C), manganese (Mn), phosphorus (P), iron (Fe), cobalt (Co), nickel (Ni), and copper (Cu) are reduced in the following order: Al<Li<C<Mn<P<Fe<Co<Ni<Cu. In other words, by controlling the amount of carbon, valuable metals (Ni, Co, etc.) are preferentially reduced.

[0079] However, the more carbon used in the reduction melting treatment, the more carbon dioxide is discharged from the system after the treatment.On the other hand, if the amount of carbon is too small, the oxides of valuable metals cannot be effectively reduced, as mentioned above, making it difficult to effectively recover them as metals.

[0080] In this regard, the present embodiment is characterized by using a pyrometallurgical raw material containing at least one valuable metal selected from nickel (Ni) and cobalt (Co) and carbon (C), with a C content of 25 mass% or less and a C / (Ni+Co) ratio of 2.5 or less. This pyrometallurgical raw material allows for processing with reduced carbon dioxide emissions, and since the relationship C / (Ni+Co) is 2.5 or less, valuable metal oxides can be effectively reduced.

[0081] The heating temperature in the reducing melting treatment is not particularly limited, but is preferably in the range of 1300°C to 1550°C, and more preferably in the range of 1350°C to 1450°C. Heating temperatures above 1550°C waste thermal energy and accelerate wear of the refractories in the melting furnace, which can reduce productivity. On the other hand, heating temperatures below 1300°C can result in poor separation of the slag and metal, reducing the recovery rate.

[0082] The furnace (melting furnace) used in the reduction melting treatment is not particularly limited, and examples of the melting furnace include a submerged arc furnace, an arc furnace, and an induction furnace.

[0083] In the reduction melting process, a flux may be added to lower the melting point of the slag. Examples of the flux include calcium oxide and calcium carbonate. The flux may be added by being poured into the melting furnace containing the pyrometallurgical raw materials, or may be mixed with the pyrometallurgical raw materials before being added.

[0084] Furthermore, if the degree of reduction during the reduction melting process is too high, resulting in impurity metals being reduced and distributed among the valuable metals, the degree of oxidation may be adjusted by supplying an oxidizing agent. The degree of oxidation can be adjusted appropriately by known methods. For example, an oxidizing agent such as oxygen may be blown into the melt produced by the reduction melting process. More specifically, a metal tube (lance) is inserted into the melt, and the oxidizing agent is blown in by bubbling, thereby carrying out the oxidation process. The oxidizing agent used in this case may be an oxygen-containing gas such as air, pure oxygen, or an oxygen-enriched gas.

[0085] In the method for producing valuable metals, an oxidizing roasting step can be provided as necessary, in which a part or all of the raw materials for pyrometallurgy are oxidized and roasted prior to the treatment in the reduction melting step S2. By providing the oxidizing roasting step in this way and performing oxidizing roasting, it is possible to suppress variations in the oxidation of the metal elements contained in the raw materials for pyrometallurgy.

[0086] In the oxidizing roasting step, the raw material for pyrometallurgy is preferably treated (oxidizing roasting treatment) at an oxidation degree sufficient to oxidize low-value metals (e.g., Al) contained in the raw material for pyrometallurgy. Meanwhile, the oxidation degree can be easily controlled by adjusting the treatment temperature, time, and / or atmosphere of the oxidizing roasting.

[0087] The degree of oxidation is adjusted as follows. That is, aluminum (Al), lithium (Li), carbon (C), manganese (Mn), phosphorus (P), iron (Fe), cobalt (Co), nickel (Ni), and copper (Cu) are generally oxidized in the following order: Al > Li > C > Mn > P > Fe > Co > Ni > Cu. In the oxidizing roasting process, oxidation is allowed to proceed until all of the aluminum contained in the pyrometallurgical raw material is oxidized. While oxidation may be accelerated until a portion of the iron is oxidized, it is preferable to limit the degree of oxidation to a level that prevents cobalt from being oxidized and distributed to the slag.

[0088] The oxidizing agent used in the oxidizing roasting treatment is not particularly limited, but is preferably an oxygen-containing gas (air, quasi-oxygen, oxygen-enriched gas, etc.). The amount of the oxidizing agent to be supplied is preferably, for example, 1.2 times or more the chemical equivalent required for oxidizing each substance to be subjected to the oxidation treatment.

[0089] The heating temperature in the oxidizing roasting treatment is not particularly limited, but is preferably 600°C or higher, and more preferably 700°C or higher. By using such a heating temperature, the heating time can be shortened. In addition, the heating temperature is preferably 900°C or lower, which can reduce the thermal energy cost and improve the efficiency of the oxidizing roasting treatment.

[0090] The oxidizing roasting treatment can be carried out using a known roasting furnace. The same furnace as the melting furnace used in the subsequent reducing melting step S2 may be used, but it is more preferable to carry out the oxidizing roasting treatment using a different furnace (preparatory furnace). The furnace (oxidizing roasting furnace) used in the oxidizing roasting treatment can be of any type, as long as it is capable of supplying an oxidizing agent (oxygen, etc.) to the charge while roasting it, thereby carrying out the oxidation treatment therein. Examples of such furnaces include a rotary kiln, a tunnel kiln (hearth furnace), and a fluidized bed roasting furnace.

[0091] (4) Slag Separation Step The slag separation step S3 is a step of separating slag from the reduced product (reducing melt) obtained through the reduction melting step S2 to recover valuable metals or alloys of valuable metals (valuable metal alloys). Slag and metal have different specific gravities, and slag, which has a smaller specific gravity than metal, tends to collect above the metal in the melting furnace. Therefore, gravity separation allows for efficient separation and recovery of slag and metal.

[0092] 3. Method for recovering valuable metals by hydrometallurgical process The metal containing valuable metals obtained through the above-described hydrometallurgical process is, for example, an alloy containing nickel (Ni) and cobalt (Co). Furthermore, for example, when a hydrometallurgical process is performed using waste lithium-ion batteries as a starting material and a pyrometallurgical raw material prepared from the starting material, an alloy (Ni-Co-Cu alloy) containing copper (Cu) as a valuable metal in addition to nickel (Ni) and cobalt (Co) can be obtained. By subjecting such an alloy to a hydrometallurgical process (hydrometallurgical process), the respective valuable metals can be separated, refined, and recovered.

[0093] Wet treatment processes for alloys include leaching using acids such as sulfuric acid, solvent extraction to extract specific impurity elements and valuable metal elements, and liquid purification to purify a solution containing valuable metals by oxidation and / or neutralization. Leaching, solvent extraction, liquid purification, etc. can be performed using known methods. By undergoing such wet treatment processes, the valuable metals to be recovered can be purified, concentrated, and separated and recovered.

[0094] For example, an aqueous solution of nickel and cobalt sulfates can be produced by adding sulfuric acid to an alloy (Ni-Co-Cu alloy) to leach nickel (Ni) and cobalt (Co) from the alloy.

[0095] Therefore, from this, it is possible to define a method for producing an aqueous nickel sulfate solution and / or an aqueous cobalt sulfate solution using the pyrometallurgical raw materials described in detail above. Specifically, it is possible to define a method for producing nickel sulfate and / or cobalt sulfate, comprising: a dry treatment step (a step of the dry treatment process) of producing valuable metals or alloys containing the valuable metals by a dry treatment process using the pyrometallurgical raw materials; and a hydrotreatment step (a step of the hydrotreatment process) of producing nickel sulfate and / or cobalt sulfate from the valuable metals or alloys containing the valuable metals obtained in the dry treatment step through a hydrotreatment process including a leaching treatment using sulfuric acid.

[0096] The nickel sulfate and / or cobalt sulfate produced by the method for producing nickel sulfate and / or cobalt sulfate conceptually includes both the form of an aqueous solution and the form of a solid.

[0097] The acid leaching method is not particularly limited and can be performed by any known method. For example, a strong acid such as hydrochloric acid, sulfuric acid, or nitric acid can be used alone or in combination. The acid solution is added to the alloy (alloy powder) and the pH is controlled to a range of 0.8 to 2.0. As described above, among acids, when realizing the so-called "battery-to-battery" recycling method, which is an ideal recycling method for recycling used lithium-ion batteries and using them again as lithium-ion battery raw materials, it is preferable to use an acid containing sulfuric acid. By using sulfuric acid as the acid, a leachate can be obtained in the form of sulfates (nickel sulfate, cobalt sulfate) that are easily usable as cathode materials for lithium-ion batteries.

[0098] The amount of acid used in the leaching treatment is 1 equivalent or more, preferably 1.2 equivalents or more, and more preferably in the range of 1.2 to 11 equivalents, relative to the total amount of nickel and / or cobalt contained in the alloy. Increasing the acid concentration can increase the rate of the leaching reaction. As a specific example, to adjust the amount of acid so that the pH is 0.8 or higher, it is preferable to use an amount that results in 1.2 to 2 equivalents.

[0099] In addition, in the leaching treatment, it is preferable to add a sulfiding agent before or simultaneously with contacting the valuable metal or an alloy containing the valuable metal with acid, and to perform the leaching treatment under conditions in which the sulfiding agent coexists. For example, when a Ni-Co-Cu alloy is to be treated, performing the leaching treatment in the presence of the sulfiding agent in this manner allows copper to be efficiently immobilized as a solid sulfide, and allows effective separation into a leachate in which nickel and / or cobalt are dissolved and a leach residue mainly containing copper sulfide.

[0100] The sulfurizing agent may be a known agent such as solid sulfur (S), sodium hydrosulfide, hydrogen sulfide, etc. The amount of sulfurizing agent added is preferably equal to or greater than the equivalent required to sulfurize the copper contained in the alloy (1 equivalent or greater), and more preferably equal to or greater than 1.2 equivalents.

[0101] Furthermore, for example, in a leaching treatment of a Ni—Co—Cu alloy, at least a portion of the Ni—Co—Cu alloy may be sulfurized prior to the leaching treatment. Copper (Cu) is more easily sulfurized than nickel (Ni) or cobalt (Co), and preferentially becomes copper sulfide. Therefore, by sulfurizing a portion of the Ni—Co—Cu alloy, a mixture of copper sulfide and the Ni—Co alloy is obtained. This fixes the copper as a solid, and nickel and cobalt can be selectively leached into acid. Therefore, by subjecting the Ni—Co—Cu alloy to sulfurization treatment in advance, nickel and cobalt can be more efficiently leached into acid. The sulfurization method is not particularly limited, and solid sulfur (S), hydrogen sulfide (H ２ Examples of such methods include introducing sulfur-containing substances such as sulfur-containing hydroxybenzoates (S).

[0102] When carrying out the leaching treatment, it is preferable to crush the alloy to a predetermined size in advance. By crushing, the specific surface area of ​​the alloy increases, thereby improving the leaching efficiency. The crushing treatment is not particularly limited, and can be carried out using a known crusher such as a ball mill, a rod mill, or a disk mill. Alternatively, the alloy may be crushed by a method such as gas atomization or water atomization to prepare atomized powder, which is then subjected to the leaching treatment.

[0103] In this way, an aqueous solution of nickel sulfate and / or cobalt sulfate can be produced by subjecting a valuable metal or an alloy containing the valuable metal to a leaching treatment with sulfuric acid. For example, when an alloy containing nickel and cobalt obtained from a pyrometallurgical raw material containing nickel and cobalt through a pyrometallurgical treatment process is subjected to a leaching treatment, a mixed aqueous solution of nickel sulfate and cobalt sulfate can be produced.

[0104] The resulting leachate containing nickel and / or cobalt can then be subjected to a solution purification treatment including neutralization and a solvent extraction treatment, which allows impurity elements to be separated and removed, yielding an aqueous solution containing concentrated nickel and / or cobalt.

[0105] Specifically, for example, by subjecting a mixed aqueous solution of nickel sulfate and cobalt sulfate obtained through a leaching treatment to a solution purification treatment, impurity elements such as iron (Fe) and zinc (Zn) in the aqueous solution can be removed, and a mixed aqueous solution of nickel sulfate and cobalt sulfate in which nickel and cobalt are concentrated can be obtained. Furthermore, by subjecting the mixed aqueous solution after the solution purification treatment to a solvent extraction treatment using a predetermined extractant, nickel and cobalt can be further concentrated.

[0106] Thereafter, nickel sulfate and / or cobalt sulfate can be converted into a solid form from the aqueous solution of nickel sulfate and / or cobalt sulfate by a known method.

[0107] The present invention will be explained in more detail below by showing examples, but the present invention is not limited to the following examples in any way.

[0108] (Preparation step) Waste lithium ion batteries containing nickel (Ni) and cobalt (Co) as valuable metals were roasted to render them harmless, pulverized, and then the pulverized material was sieved to a classification point of 1 mm. The resulting under-sieve black mass was collected and used as the starting material.

[0109] (Preparation Step) A raw material for pyrometallurgy was prepared from the starting material, black mass, by the following process: Specifically, the starting material was first subjected to a first classification process at the classification points (first classification points) shown in Table 1 below, and separated into coarse powder A (oversized material) and fine powder A (undersized material).

[0110] Subsequently, the recovered fine powder A was subjected to a second classification process at the classification point (second classification point) shown in Table 1 below, and separated into coarse powder B (oversized material) and fine powder B (undersized material).

[0111] The coarse powder A and the coarse powder B obtained through the above-described preparation process were mixed to prepare a raw material for pyrometallurgy.

[0112] The carbon (C) content and the ratio C / (Ni+Co) of the pyrometallurgical raw materials used in each of the Examples and Comparative Examples were measured. The average particle size of the pyrometallurgical raw materials was also measured. The measurement results are summarized in Table 1 below.

[0113] The metal content was measured using an ICP optical emission spectrometer (manufactured by Agilent Technologies, model ICP-OES Agilent 5900). The carbon content was measured using a carbon / sulfur analyzer (model CS844) manufactured by LECO. The average particle size is the average particle size measured when 1,000 powder particles were measured using a laser light diffraction / scattering particle size distribution analyzer (model LA950V2) manufactured by Horiba.

[0114] (Pyrometallurgical Treatment Process) Next, a pyrometallurgical treatment process for producing valuable metals was carried out using the obtained pyrometallurgical raw materials. Specifically, the pyrometallurgical raw materials were charged into a submerged arc furnace, heated and melted at a temperature of 1400°C, and subjected to a reduction melting process to reduce the oxides of the valuable metals. This reduction melting process produced a slag consisting of oxides of impurity elements and a reduced melt containing an alloy of nickel and cobalt.

[0115] The slag was separated from the resulting reduced melt to recover an alloy of nickel and cobalt.

[0116] (Measurement of Treatment Results) The amount of carbon dioxide (CO ) emitted by carrying out the dry treatment process was measured. ２ ) emissions, the carbon (C) that was not used for reduction in the process is CO ２ The purity of the recovered nickel-cobalt alloy (Ni-Co alloy) was measured using an ICP optical emission spectrometer (manufactured by Agilent Technologies, Inc., model ICP-OES Agilent 5900). The measurement results are summarized in Table 1 below.

[0117]

[0118] As shown in the results in Table 1, in Examples 1 to 7, which used raw materials for pyrometallurgy in which the carbon (C) content was 25 mass% or less and the ratio expressed as C / (Ni+Co) was 2.5 or less, alloys with high purity of valuable metals could be obtained, and the amount of carbon dioxide emissions in the pyrometallurgy process was effectively reduced.

[0119] In contrast, in Comparative Examples 1 to 3, the carbon (C) content exceeded 25 mass% and the ratio of C / (Ni+Co) exceeded 2.5, resulting in increased carbon dioxide emissions in the pyrometallurgical treatment process compared to the Examples. In addition, excessive reduction reactions occurred in the pyrometallurgical treatment, resulting in the reduction of impurity elements as well, resulting in a decrease in the purity of the alloy.

Claims

1. A raw material for dry smelting, comprising at least one valuable metal selected from the group consisting of nickel (Ni) and cobalt (Co) and carbon (C), the C content being 25 mass% or less, and the C / (Ni+Co) ratio being 2.5 or less.

2. The raw material for pyrometallurgy according to claim 1, having an average particle size of 270 μm or more.

3. The raw material for pyrometallurgy according to claim 1, wherein the C content is 15 mass% or less.

4. A method for producing a raw material for dry smelting according to claim 1, comprising the steps of: preparing a starting material containing at least one valuable metal selected from the group consisting of nickel (Ni) and cobalt (Co) and carbon (C); and classifying the starting material to produce a coarse powder A containing the valuable metal. １ and fine powder A ２ a first classification step of dividing the fine powder A into fine powder B and fine powder C; ２ The powder is classified into coarse powder B. １ and fine powder B ２ and a second classification step of classifying the coarse powder A obtained from the first classification step. １ and the coarse powder B obtained from the second classification step. １ and recovering the above-mentioned raw materials for pyrometallurgy as raw materials for pyrometallurgy.

5. The method for producing a raw material for dry smelting according to claim 4, wherein in the first classification step, classification is performed with a classification point of 50 μm to 250 μm.

6. The method for producing a raw material for dry smelting according to claim 5, wherein in the second classification step, classification is performed with a classification point of 25 μm or more.

7. A method for producing valuable metals or alloys containing valuable metals from a raw material for pyro-smelting containing valuable metals, comprising: a reduction-melting step of reducing and melting the raw material for pyro-smelting, and using the raw material for pyro-smelting according to claim 1 as the raw material for pyro-smelting.

8. A method for producing valuable metals as set forth in claim 7, comprising a raw material preparation step of preparing the raw material for pyro-smelting from a starting material containing valuable metals, in which the raw material preparation step prepares the raw material for pyro-smelting by carrying out the method as set forth in claim 4, and the obtained raw material for pyro-smelting is subjected to the reduction melting step.

9. The method for producing valuable metals according to claim 7, wherein the starting material comprises detoxified battery powder obtained by burning used lithium ion batteries to render them harmless and pulverizing them to a predetermined size.

10. The method for producing valuable metals according to claim 7, wherein in the reduction and melting step, the raw material for dry smelting is subjected to a reduction and melting treatment in a melting furnace to obtain a reduction and melt product containing slag and metal including the valuable metal.

11. A method for producing nickel sulfate and / or cobalt sulfate using the raw material for dry smelting as defined in claim 1, comprising: a dry treatment step of producing the valuable metal or an alloy containing the valuable metal by a dry treatment process using the raw material for dry smelting; and a wet treatment step of producing nickel sulfate and / or cobalt sulfate from the valuable metal or the alloy containing the valuable metal obtained in the dry treatment step through a wet treatment process including a leaching treatment with sulfuric acid.

12. The method for producing nickel sulfate and / or cobalt sulfate according to claim 11, wherein the raw material for dry smelting contains nickel (Ni) and cobalt (Co), and a mixed aqueous solution of nickel sulfate and cobalt sulfate is produced through a wet treatment process in the wet treatment step.

13. A method for producing nickel sulfate and / or cobalt sulfate as described in claim 11, wherein in the dry treatment step, a reduction melting process is performed on the raw material for dry smelting in a melting furnace to obtain a reduced product containing a metal containing the valuable metal and slag, and the valuable metal or an alloy containing the valuable metal is obtained by separating the slag from the reduced product.

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