Method for treating lithium-nickel-cobalt-containing material

Abstract

Provided is a method for treating a lithium-nickel-cobalt-containing material, the method comprising: a first leaching step (S01) for obtaining a lithium-nickel-cobalt leachate by adding an acidic solution to a lithium-nickel-cobalt-containing material; a neutralization step (S02) for adding a neutralizing agent to the lithium-nickel-cobalt leachate; a first solid-liquid separation step (S03) for separating a lithium leachate and a nickel-cobalt precipitate; a second leaching step (S04) for leaching the nickel-cobalt precipitate in an acidic solution to obtain a nickel-cobalt leachate; a hydrogen peroxide addition step (S05) for adding hydrogen peroxide to the acidic solution; and a second solid-liquid separation step (S06) for separating the nickel-cobalt leachate and a solid component, wherein in the hydrogen peroxide addition step (S05), hydrogen peroxide is added until the oxidation-reduction potential reaches 200 mV or more within a pH range of 1.5-2.0.

Description

Processing method for materials containing lithium, nickel, and cobalt

[0001] The present invention relates to a method for treating a lithium-nickel-cobalt-containing material, which recovers valuable metals such as lithium, nickel, and cobalt from the lithium-nickel-cobalt-containing material. This application claims priority based on Japanese Patent Application No. 2024-089442, filed May 31, 2024, the contents of which are incorporated herein by reference.

[0002] In recent years, lithium has been recovered and reused from crushed lithium-ion batteries. When recovering lithium from lithium-ion batteries, it is common to use waste lithium-ion battery powder, which is obtained by firing and / or crushing used lithium-ion batteries, a recycled raw material known as black mass, or defective products generated during the secondary battery manufacturing process, known as black powder. The waste lithium-ion battery powder contains metals such as nickel and cobalt in addition to lithium. Therefore, technologies for recovering nickel and cobalt from waste lithium-ion battery powder have been proposed.

[0003] For example, Patent Document 1 proposes a technology for recovering lithium by leaching battery sludge containing lithium aluminate obtained by roasting lithium-ion battery waste in an acidic solution, neutralizing the resulting leachate and performing solid-liquid separation to separate the lithium solution from metals such as aluminum, nickel, and cobalt. Patent Document 2 proposes a method for recovering lithium by crushing and classifying lithium-ion secondary batteries to obtain an electrode material containing cobalt and nickel, immersing the electrode material in a treatment solution containing sulfuric acid and hydrogen peroxide to produce a leachate, separating copper from the leachate to obtain an eluate containing cobalt and nickel, adding an alkali metal hydroxide to the eluate to adjust the pH, adding a hydrogen sulfide compound, stirring, and performing solid-liquid separation to separate the eluate into cobalt sulfide and nickel sulfide and a residual solution containing lithium.

[0004] Japanese Unexamined Patent Publication No. 2019-160429 (A) Japanese Unexamined Patent Application No. 2022-042982 (A)

[0005] Incidentally, used lithium-ion batteries may contain cobalt and nickel in addition to lithium, and may also contain complex compounds that are difficult to dissolve in acid. The method disclosed in Patent Document 1 has a problem in that it is not possible to sufficiently dissolve cobalt and nickel. Furthermore, the method disclosed in Patent Document 2 involves immersing an electrode material in a treatment solution containing sulfuric acid and hydrogen peroxide to obtain a leachate. While it is possible to dissolve cobalt and nickel at this stage, the leachate contains lithium, which makes it difficult to efficiently recover lithium, nickel, and cobalt.

[0006] The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a method for treating a lithium-nickel-cobalt-containing material that can efficiently recover valuable metals such as lithium, nickel, and cobalt from a lithium-nickel-cobalt-containing material that contains lithium, cobalt, and nickel.

[0007] In order to solve the above problems, a method for treating a lithium-nickel-cobalt-containing material according to a first aspect of the present invention includes a first leaching step of adding an acidic solution containing an inorganic acid to a lithium-nickel-cobalt-containing material containing lithium, nickel, and cobalt, and leaching the lithium, nickel, and cobalt into the acidic solution to obtain a lithium-nickel-cobalt leachate; a neutralization step of adding a neutralizing agent to the lithium-nickel-cobalt leachate obtained in the first leaching step to produce a nickel-cobalt precipitate containing nickel and cobalt; and a separation step of separating the lithium leachate and the nickel-cobalt precipitate obtained in the neutralization step. a second leaching step of adding an acidic solution containing an inorganic acid to the nickel-cobalt precipitate to leach nickel-cobalt into the acidic solution, thereby obtaining a nickel-cobalt leachate; a hydrogen peroxide addition step of adding hydrogen peroxide to the nickel-cobalt leachate obtained in the second leaching step to further leach nickel and cobalt; and a second solid-liquid separation step of separating the nickel-cobalt leachate obtained in the hydrogen peroxide addition step from a solid component, wherein the hydrogen peroxide is added in the hydrogen peroxide addition step until the pH of the nickel-cobalt leachate is kept within a range of 1.5 to 2.0 and the oxidation-reduction potential (vs. Ag / AgCl) of the nickel-cobalt leachate reaches 200 mV or higher.

[0008] The method for treating a lithium-nickel-cobalt-containing material according to Aspect 1 of the present invention includes a first leaching step in which lithium, nickel, and cobalt are leached into an acidic solution containing an inorganic acid, a neutralization step in which a neutralizing agent is added to the lithium-nickel-cobalt leachate to produce a nickel-cobalt precipitate containing nickel and cobalt, and a first solid-liquid separation step in which the lithium leachate and the nickel-cobalt precipitate are separated after the neutralization step. This allows separation into the lithium leachate and the nickel-cobalt precipitate, and allows lithium to be recovered as the lithium leachate.

[0009] The method further comprises a second leaching step in which the nickel-cobalt precipitate is leached in an acidic solution containing an inorganic acid to obtain a cobalt-nickel leach solution, and a hydrogen peroxide addition step in which hydrogen peroxide is added to the acidic solution to further leach nickel and cobalt. Therefore, even if the nickel-cobalt precipitate contains poorly soluble composite oxides, the hydrogen peroxide reduces the highly valent nickel and cobalt, making them more soluble, thereby enabling stable leaching of nickel and cobalt. Furthermore, in the hydrogen peroxide addition step, hydrogen peroxide is added until the pH of the nickel-cobalt leach solution is kept within the range of 1.5 to 2.0 and the oxidation-reduction potential (vs. Ag / AgCl) reaches 200 mV or higher, thereby enabling sufficient leaching of the nickel and cobalt contained in the nickel-cobalt precipitate. Furthermore, since the method includes a second solid-liquid separation step for separating the nickel-cobalt leachate from the solid components, nickel and cobalt can be efficiently recovered as the nickel-cobalt leachate.

[0010] A method for treating a lithium-nickel-cobalt-containing material according to Aspect 2 of the present invention is characterized in that, in the method for treating a lithium-nickel-cobalt-containing material according to Aspect 1 of the present invention, the inorganic acid used in the first leaching step is one or more of sulfuric acid, hydrochloric acid, and nitric acid. According to the method for treating a lithium-nickel-cobalt-containing material according to Aspect 2 of the present invention, since the inorganic acid used in the first leaching step is one or more of sulfuric acid, hydrochloric acid, and nitric acid, lithium, nickel, and cobalt can be efficiently dissolved to obtain a lithium-nickel-cobalt leach solution.

[0011] A method for treating a lithium-nickel-cobalt-containing material according to Aspect 3 of the present invention is characterized in that, in the method for treating a lithium-nickel-cobalt-containing material according to Aspect 1 or Aspect 2 of the present invention, the inorganic acid used in the second leaching step is one or more of sulfuric acid, hydrochloric acid, and nitric acid. According to the method for treating a lithium-nickel-cobalt-containing material according to Aspect 3 of the present invention, since the inorganic acid used in the second leaching step is one or more of sulfuric acid, hydrochloric acid, and nitric acid, it is possible to efficiently dissolve nickel and cobalt from the nickel-cobalt precipitate and obtain a nickel-cobalt leach solution.

[0012] A method for treating a lithium-nickel-cobalt-containing material according to Aspect 4 of the present invention is the method for treating a lithium-nickel-cobalt-containing material according to any one of Aspects 1 to 3 of the present invention, characterized in that the neutralizing agent added in the neutralization step is one or more of calcium hydroxide, calcium oxide, and calcium carbonate. According to the method for treating a lithium-nickel-cobalt-containing material according to Aspect 4 of the present invention, the neutralizing agent added in the neutralization step is one or more of calcium hydroxide, calcium oxide, and calcium carbonate. Therefore, fluorine derived from the electrolyte of a lithium-ion battery dissolved in the leaching step can be removed as calcium fluoride to obtain a lithium leachate with a high lithium purity, and a nickel-cobalt precipitate containing nickel and cobalt can be efficiently produced.

[0013] A method for treating a lithium-nickel-cobalt-containing material according to Aspect 5 of the present invention is the method for treating a lithium-nickel-cobalt-containing material according to any one of Aspects 1 to 4 of the present invention, characterized in that the pH of the lithium-nickel-cobalt leach solution in the first leaching step is within the range of 1.5 to 2.0. According to the method for treating a lithium-nickel-cobalt-containing material according to Aspect 5 of the present invention, the pH of the lithium-nickel-cobalt leach solution in the first leaching step is within the range of 1.5 to 2.0, so that lithium, nickel, and cobalt can be efficiently leached from the lithium-nickel-cobalt-containing material into the acidic solution.

[0014] A method for treating a lithium-nickel-cobalt-containing material according to Aspect 6 of the present invention is the method for treating a lithium-nickel-cobalt-containing material according to any one of Aspects 1 to 5 of the present invention, characterized in that the pH of the lithium-nickel-cobalt leach solution in the second leaching step is in the range of 1.5 to 2.5. According to the method for treating a lithium-nickel-cobalt-containing material according to Aspect 6 of the present invention, the pH of the lithium-nickel-cobalt leach solution in the second leaching step is in the range of 1.5 to 2.5, so that nickel and cobalt can be efficiently leached from the nickel-cobalt precipitate into the acidic solution.

[0015] A method for treating a lithium-nickel-cobalt-containing material according to Aspect 7 of the present invention is characterized in that the second leaching step and the oxidative leaching step are carried out simultaneously in the method for treating a lithium-nickel-cobalt-containing material according to any one of Aspects 1 to 6 of the present invention. According to the method for treating a lithium-nickel-cobalt-containing material according to Aspect 7 of the present invention, by adding hydrogen peroxide to an acidic solution and carrying out the second leaching step and the oxidative leaching step simultaneously, nickel and cobalt can be leached more efficiently from the nickel-cobalt precipitate.

[0016] According to the present invention, it is possible to provide a method for treating a lithium-nickel-cobalt-containing material that can efficiently recover valuable metals such as lithium, nickel, and cobalt from a lithium-nickel-cobalt-containing material that contains lithium, cobalt, and nickel.

[0017] 1 is a flow chart showing a method for treating a lithium-nickel-cobalt-containing material according to an embodiment of the present invention. 2 is a graph showing the relationship between the amount of hydrogen peroxide added and the metal ion concentration and ORP (oxidation-reduction potential) in Examples.

[0018] An example of an embodiment of the present invention will be described below.

[0019] The method for treating a lithium-nickel-cobalt-containing material according to this embodiment is for recovering valuable metals such as lithium, nickel, and cobalt from a lithium-nickel-cobalt-containing material containing lithium, cobalt, and nickel. In this embodiment, the target lithium-nickel-cobalt-containing material is waste lithium-ion battery powder (so-called black mass) obtained by firing and / or pulverizing used lithium-ion batteries, or defective products (so-called black powder) generated in the manufacturing process of positive electrode materials for secondary batteries, etc.

[0020] In addition, the above-mentioned waste lithium-ion battery powder (black mass) and defective products (black powder) contain: (a) lithium, nickel, and cobalt combined together (for example, LiNiO ２ , LiCoO ２ etc.), (b) those derived from the electrolyte (e.g., Li ２ CO ３ (c) Others (e.g., LiAlO ２ , metallic Co, metallic Ni, NiO, CoO, etc.) are mixed. Here, (b) those derived from the electrolyte (for example, Li ２ CO ３ (a) lithium combined with nickel and cobalt (e.g., LiNiO ２ , LiCoO ２ (c) Others (e.g., LiAlO ２ , metallic Co, metallic Ni, NiO, CoO, etc.) are hardly soluble in acidic solutions.

[0021] The method for treating a lithium-nickel-cobalt-containing material according to this embodiment includes at least a first leaching step S01, a neutralization step S02, a first solid-liquid separation step S03, a second leaching step S04, a hydrogen peroxide addition step S05, and a second solid-liquid separation step S06, as shown in FIG. 1 .

[0022] (First leaching step S01) In this first leaching step S01, lithium-nickel-cobalt-containing material, such as waste lithium-ion battery powder, is immersed in an acidic solution to leach lithium, nickel, and cobalt into the acidic solution, thereby obtaining a lithium-nickel-cobalt leachate. The acidic solution may be, for example, an inorganic acid such as hydrochloric acid, sulfuric acid, or nitric acid, either singly or in combination. In this embodiment, sulfuric acid is used as the acid.

[0023] In this embodiment, the lithium-nickel-cobalt-containing material is mixed with an acidic solution and stirred (stirring time: 1 hour to 24 hours) to dissolve the lithium, nickel, and cobalt in the lithium-nickel-cobalt-containing material, thereby obtaining a lithium-nickel-cobalt leachate. Here, in this embodiment, the pH of the lithium-nickel-cobalt leachate in the first leaching step S01 is preferably in the range of 1.5 to 2.0.

[0024] (Neutralization Step S02) Next, a neutralizing agent is added to the lithium-nickel-cobalt leachate obtained in the first leaching step S01 to produce a nickel-cobalt precipitate containing nickel and cobalt. In this embodiment, the neutralizing agent added in the neutralization step S02 is preferably one or more of calcium hydroxide, calcium oxide, and calcium carbonate. This removes fluorine from the lithium-ion battery electrolyte dissolved in the first leaching step S01 as calcium fluoride, thereby obtaining a lithium leachate with high lithium purity and efficiently producing a nickel-cobalt precipitate containing nickel and cobalt. While there are no particular limitations on the pH in the neutralization step S02, it is preferably within the range of 8 to 12.

[0025] (First solid-liquid separation step S03) In this first solid-liquid separation step S03, the nickel-cobalt precipitate produced in the neutralization step S02 is separated from the lithium leachate. As a method for separating the nickel-cobalt precipitate from the lithium leachate, a solid-liquid separation method such as gravity settling, centrifugal separation, or filter cloth filtration using a filter press or the like can be used.

[0026] (Second leaching step S04) In this second leaching step S04, the nickel-cobalt precipitate separated in the first solid-liquid separation step S03 is leached in an acidic solution containing an inorganic acid to obtain a nickel-cobalt leachate. The inorganic acid used in the second leaching step S04 can be one or more of sulfuric acid, hydrochloric acid, and nitric acid. The pH of the lithium-nickel-cobalt leachate in the second leaching step S04 is preferably in the range of 1.5 to 2.5, more preferably in the range of 1.5 to 2.0.

[0027] (Hydrogen peroxide addition step S05) In this hydrogen peroxide addition step S05, hydrogen peroxide is added to the acidic solution to further leach nickel and cobalt from the nickel-cobalt precipitate into the acidic solution. In the hydrogen peroxide addition step S05, hydrogen peroxide is added until the pH of the nickel-cobalt leachate obtained in the second leaching step S04 is kept within the range of 1.5 to 2.0 and the oxidation-reduction potential (vs. Ag / AgCl) becomes 200 mV or higher.

[0028] The nickel-cobalt precipitate may contain complex compounds containing nickel and cobalt that are difficult to dissolve in acid. In such complex oxides, nickel and cobalt exist in high valence states such as trivalent and tetravalent. The nickel-cobalt leachate obtained in the second leaching step S04 is added with hydrogen peroxide until the pH of the leachate is in the range of 1.5 to 2.0 and the oxidation-reduction potential (vs. Ag / AgCl) is 200 mV or higher. This reduces the trivalent and tetravalent nickel and cobalt to divalent states, thereby accelerating their leaching into the acidic solution. Specifically, the lithium-ion battery powder (black mass) contains (a) a compound in which lithium is combined with nickel and cobalt (e.g., LiNiO ２ , LiCoO ２This promotes dissolution of the ferrous metals (e.g., ferrous metals) and allows them to be leached into the acidic solution. The oxidation-reduction potential is more preferably 300 mV or higher, and particularly preferably 400 mV or higher. The second leaching step S04 and the hydrogen peroxide addition step S05 can also be carried out simultaneously.

[0029] (Second solid-liquid separation step S06) In this second solid-liquid separation step S06, the nickel-cobalt leachate obtained in the second leaching step S04 and the hydrogen peroxide addition step S05 is separated from other solid components. As a method for separating the nickel-cobalt leachate from other solid components, a solid-liquid separation method such as gravity settling, centrifugation, or filter cloth filtration using a filter press or the like can be used.

[0030] By carrying out these steps, lithium is recovered as a lithium leachate, and cobalt and nickel are recovered as a nickel-cobalt leachate from the lithium-nickel-cobalt-containing material.

[0031] The method for treating a lithium-nickel-cobalt-containing material of this embodiment configured as described above includes a first leaching step S01 in which lithium, nickel, and cobalt are leached into an acidic solution containing an inorganic acid, a neutralization step S02 in which a neutralizing agent is added to the lithium-nickel-cobalt leachate to produce a nickel-cobalt precipitate containing nickel and cobalt, and a first solid-liquid separation step S03 in which the lithium leachate and the nickel-cobalt precipitate are separated after the neutralization step S02.Therefore, the lithium leachate and the nickel-cobalt precipitate can be separated, and lithium can be recovered as the lithium leachate.

[0032] The method for treating a lithium-nickel-cobalt-containing material according to this embodiment includes a second leaching step S04 in which the nickel-cobalt precipitate is leached in an acidic solution containing an inorganic acid to obtain a cobalt-nickel leachate, and a hydrogen peroxide addition step S05 in which hydrogen peroxide is added to the acidic solution to further leach nickel and cobalt. Therefore, even if the nickel-cobalt precipitate contains poorly soluble composite oxides, nickel and cobalt can be stably leached. Furthermore, in the hydrogen peroxide addition step S05, hydrogen peroxide is added until the pH of the nickel-cobalt leachate obtained in the second leaching step S04 is kept within the range of 1.5 to 2.0 and the oxidation-reduction potential (vs. Ag / AgCl) is 200 mV or higher. This enables the nickel and cobalt contained in the nickel-cobalt precipitate to be sufficiently leached. Furthermore, since the second solid-liquid separation step S06 for separating the nickel-cobalt leachate from the solid components is provided, nickel and cobalt can be efficiently recovered as the nickel-cobalt leachate.

[0033] In the method for treating a lithium-nickel-cobalt-containing material according to this embodiment, when the inorganic acid used in the first leaching step S01 is one or more of sulfuric acid, hydrochloric acid, and nitric acid, lithium, nickel, and cobalt can be efficiently dissolved to obtain a lithium-nickel-cobalt leachate.

[0034] In the method for treating a lithium-nickel-cobalt-containing material according to this embodiment, when the inorganic acid used in the second leaching step S04 is one or more of sulfuric acid, hydrochloric acid, and nitric acid, nickel and cobalt can be efficiently dissolved from the nickel-cobalt precipitate to obtain a nickel-cobalt leach solution.

[0035] In the method for treating a lithium-nickel-cobalt-containing material of this embodiment, when the neutralizing agent added in the neutralization step S02 is one or more of calcium hydroxide, calcium oxide, and calcium carbonate, it becomes possible to efficiently produce a nickel-cobalt precipitate containing nickel and cobalt from the lithium-nickel-cobalt leachate.

[0036] In the method for treating a lithium-nickel-cobalt-containing material according to the present embodiment, when the pH in the first leaching step S01 is set to a range of 1.5 or more and 2.0 or less, it becomes possible to efficiently leach lithium, nickel, and cobalt from the lithium-nickel-cobalt-containing material into the acidic solution.

[0037] In the method for treating a lithium-nickel-cobalt-containing material according to the present embodiment, when the pH in the second leaching step S04 is set to a range of 1.5 or more and 2.5 or less, nickel and cobalt can be efficiently leached from the nickel-cobalt precipitate into the acidic solution.

[0038] In the method for treating a lithium-nickel-cobalt-containing material according to this embodiment, when hydrogen peroxide is added to the acidic solution and the second leaching step S04 and the hydrogen peroxide adding step S05 are carried out simultaneously, nickel and cobalt can be leached more efficiently from the nickel-cobalt precipitate.

[0039] Although the embodiment of the present invention has been described above, the present invention is not limited to this and can be modified as appropriate within the scope of the technical idea of ​​the invention.

[0040] The results of confirmation experiments conducted to confirm the effectiveness of the present invention will be described below.

[0041] At room temperature (20°C to 30°C, 25°C in this example), 50 g of black mass was stirred with 47 vol.% sulfuric acid added until the pH reached 2 or less (first leaching step). After the reaction in the first leaching step was completed, calcium hydroxide solution was added and stirred until the pH reached 10 or more (neutralization step). The slurry obtained in the neutralization step was filtered and separated into a liquid and a dregs (first solid-liquid separation step). The obtained liquid and dregs were subjected to elemental analysis by ICP. Next, at room temperature, 47 vol.% sulfuric acid was added to the dregs obtained in the first solid-liquid separation step until the pH reached 2 or less (second leaching step). Then, hydrogen peroxide water was added to the slurry whose pH reached 2 or less in the second leaching step. During this time, 47 vol.% sulfuric acid was added as needed to maintain the pH in the range of 1.5 to 2.0. This operation was continued until the ORP (oxidation-reduction potential) reached 200 mV (Ag / AgCl) or more (hydrogen peroxide addition step). Next, the slurry obtained in the hydrogen peroxide addition step was filtered and separated into a liquid and a dregs (second solid-liquid separation step). The obtained liquid and dregs were subjected to elemental analysis by ICP.

[0042] The relationship between ORP (oxidation-reduction potential) and metal ion concentration (concentration of dissolved Co and Ni) in the hydrogen peroxide addition step is shown in Figure 2. Furthermore, from the results of the above elemental analysis, the leaching rates (%) of Ni, Co, and Li were calculated using the following formulas. The calculation results are shown in Table 1.

[0043] Ni leaching rate (%)=[(amount (g) of Ni in the liquid in the first solid-liquid separation step + amount (g) of Ni in the liquid in the second solid-liquid separation step)) / (amount (g) of Ni in the liquid in the first solid-liquid separation step + amount (g) of Ni in the liquid in the second solid-liquid separation step + amount (g) of Ni in the dregs in the second solid-liquid separation step)]×100

[0044] Co leaching rate (%) = [(amount of Co in the liquid in the first solid-liquid separation step (g) + amount of Co in the liquid in the second solid-liquid separation step (g)) / (amount of Co in the liquid in the first solid-liquid separation step (g) + amount of Co in the liquid in the second solid-liquid separation step (g) + amount of Co in the slag in the second solid-liquid separation step (g))] × 100

[0045] Li leaching rate (%)=[(amount of Li in the liquid in the first solid-liquid separation step (g)+amount of Li in the liquid in the second solid-liquid separation step (g)) / (amount of Li in the liquid in the first solid-liquid separation step (g)+amount of Li in the liquid in the second solid-liquid separation step (g)+amount of Li in the dregs in the second solid-liquid separation step (g))]×100

[0046]

[0047] As shown in Figure 2, it was confirmed that when hydrogen peroxide is added in the hydrogen peroxide addition step to a nickel-cobalt leachate whose pH is in the range of 1.5 to 2.0, the ORP (oxidation-reduction potential) increases and the dissolution of Co and Ni progresses, and when the ORP (oxidation-reduction potential) exceeds 200 mV, the increasing trend in the amount of dissolved Co and Ni becomes gradual. Furthermore, as shown in Table 1, it was confirmed that Ni, Co, and Li were sufficiently leached into the leachate, and that these valuable metals could be efficiently recovered.

[0048] As a result of the above confirmatory experiments, it was confirmed that the present invention can provide a method for treating lithium-nickel-cobalt-containing material that can efficiently recover valuable metals such as lithium, nickel, and cobalt from lithium-nickel-cobalt-containing material containing lithium, cobalt, and nickel.

[0049] According to the present invention, it is possible to provide a method for treating a lithium-nickel-cobalt-containing material that can efficiently recover valuable metals such as lithium, nickel, and cobalt from a lithium-nickel-cobalt-containing material that contains lithium, cobalt, and nickel.

Claims

1. A first leaching step of adding an acidic solution containing an inorganic acid to a lithium-nickel-cobalt-containing material containing lithium, nickel, and cobalt, and leaching the lithium, nickel, and cobalt into the acidic solution to obtain a lithium-nickel-cobalt leachate; a neutralization step of adding a neutralizing agent to the lithium-nickel-cobalt leachate obtained in the first leaching step to produce a nickel-cobalt precipitate containing nickel and cobalt; a first solid-liquid separation step of separating the lithium leachate obtained in the neutralization step from the nickel-cobalt precipitate; a second leaching step of adding an acidic solution containing an inorganic acid to the nickel-cobalt precipitate to leach the nickel-cobalt into the acidic solution to obtain a nickel-cobalt leachate; and a hydrogen peroxide addition step of adding hydrogen peroxide to the nickel-cobalt leachate obtained in the second leaching step to further leach nickel and cobalt. and a second solid-liquid separation step of separating the nickel-cobalt leachate obtained in the hydrogen peroxide addition step from a solid component, wherein in the hydrogen peroxide addition step, hydrogen peroxide is added until the pH of the nickel-cobalt leachate is kept within a range of 1.5 to 2.0 and the oxidation-reduction potential (vs. Ag / AgCl) of the nickel-cobalt leachate reaches 200 mV or higher.

2. The method for treating lithium-nickel-cobalt-containing material according to claim 1, characterized in that the inorganic acid used in the first leaching step is one or more of sulfuric acid, hydrochloric acid, and nitric acid.

3. The method for treating lithium-nickel-cobalt-containing material according to claim 1, characterized in that the inorganic acid used in the second leaching step is one or more of sulfuric acid, hydrochloric acid, and nitric acid.

4. A method for treating lithium-nickel-cobalt-containing material according to any one of claims 1 to 3, characterized in that the neutralizing agent added in the neutralization step is one or more of calcium hydroxide, calcium oxide, and calcium carbonate.

5. A method for treating lithium-nickel-cobalt-containing material described in any one of claims 1 to 3, characterized in that the pH of the lithium-nickel-cobalt leaching solution in the first leaching step is within the range of 1.5 to 2.

0.

6. A method for treating lithium-nickel-cobalt-containing material according to any one of claims 1 to 3, characterized in that the pH of the nickel-cobalt leaching solution in the second leaching step is in the range of 1.5 to 2.

5.

7. A method for treating a lithium-nickel-cobalt-containing material according to any one of claims 1 to 3, characterized in that the second leaching step and the hydrogen peroxide addition step are carried out simultaneously.

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