Method for treating lithium / nickel / cobalt-containing material

Abstract

To provide a method for treating lithium / nickel / cobalt-containing materials that can efficiently recover lithium, nickel, and cobalt from lithium / nickel / cobalt-containing materials.SOLUTION: A method for treating lithium / nickel / cobalt-containing material includes: a first leaching step S01 of adding an acidic solution to a lithium / nickel / cobalt-containing material to obtain a lithium-nickel-cobalt leachate; a neutralization step S02 of adding a neutralizer to the lithium-nickel-cobalt leachate; a first solid / liquid separation step S03 of separating a lithium leachate and a nickel / cobalt precipitate; a second leaching step S04 of leaching the nickel / cobalt precipitate in an acidic solution to obtain nickel / cobalt leachate; a hydrogen peroxide addition step S05 of adding hydrogen peroxide to an acidic solution; and a second solid / liquid separation step S06 of separating the nickel-cobalt leachate and solid components. In the hydrogen peroxide addition step S05, hydrogen peroxide is added until the oxidation-reduction potential reaches 200 mV or higher within a pH range of 1.5 or higher and 2.0 or lower.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for treating lithium-nickel-cobalt-containing materials, which recovers valuable metals such as lithium, nickel, and cobalt from lithium-nickel-cobalt-containing materials containing lithium, cobalt, and nickel. [Background technology]

[0002] In recent years, lithium has been recovered from crushed lithium-ion batteries and reused. To recover lithium from lithium-ion batteries, it is common to use waste lithium-ion battery powder, commonly known as black mass, obtained by firing and / or crushing used lithium-ion batteries, or defective products generated during the secondary battery manufacturing process, commonly known as black powder. Here, the above-mentioned waste lithium-ion battery powder contains metals other than lithium, such as nickel and cobalt, and therefore, techniques 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 slag 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 in which lithium ion secondary batteries are crushed and classified to obtain an electrode material containing cobalt and nickel, this electrode material is immersed in a treatment solution containing sulfuric acid and hydrogen peroxide to produce a leachate, copper is separated from this leachate to obtain an eluate containing cobalt and nickel, an alkali metal hydroxide is added to this eluate to adjust the pH, a hydrogen sulfide compound is added, and the mixture is stirred and subjected to solid-liquid separation to separate the material into cobalt sulfide and nickel sulfide and a residual solution containing lithium. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-160429 [Patent Document 2] Japanese Patent Publication No. 2022-042982 Summary of the Invention [Problem to be solved by the invention]

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

[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 the lithium-nickel-cobalt-containing material that contains lithium, cobalt, and nickel. [Means for solving the problem]

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

[0008] The method for treating a lithium-nickel-cobalt-containing material according to the first aspect 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 the lithium leachate to be separated from the nickel-cobalt precipitate, and lithium to be recovered as the lithium leachate.

[0009] The process also includes 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.Even if the nickel-cobalt precipitate contains poorly soluble composite oxides, the hydrogen peroxide reduces the high-valent nickel and cobalt, making them more soluble, and nickel and cobalt can be leached stably. Furthermore, in the hydrogen peroxide addition step, hydrogen peroxide is added until the pH of the nickel-cobalt leaching solution is kept within the range of 1.5 to 2.0 and the oxidation-reduction potential (vs Ag / AgCl) is 200 mV or higher, so that the nickel and cobalt contained in the nickel-cobalt precipitate can be sufficiently leached. 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 a second aspect of the present invention is characterized in that, in the method for treating a lithium-nickel-cobalt-containing material according to the first aspect 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 of the second aspect 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, so that lithium, nickel, and cobalt can be efficiently dissolved to obtain a lithium-nickel-cobalt leachate.

[0011] A method for treating a lithium-nickel-cobalt-containing material according to a third aspect of the present invention is characterized in that, in the method for treating a lithium-nickel-cobalt-containing material according to the first or second aspect 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 of aspect 3 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, so that nickel and cobalt can be efficiently dissolved from the nickel-cobalt precipitate to obtain a nickel-cobalt leach solution.

[0012] A method for treating a lithium-nickel-cobalt-containing material according to a fourth aspect of the present invention is characterized in that, in the method for treating a lithium-nickel-cobalt-containing material according to any one of the first to third aspects of the present invention, 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 of 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. This makes it possible to remove fluorine from the electrolyte of a lithium-ion battery dissolved in the leaching step as calcium fluoride, thereby obtaining a lithium leachate with a high lithium purity, and to efficiently produce a nickel-cobalt precipitate containing nickel and cobalt.

[0013] A fifth aspect of the present invention is a method for treating a lithium-nickel-cobalt-containing material according to any one of the first to fourth aspects of the present invention, characterized in that the pH of the lithium-nickel-cobalt leaching solution in the first leaching step is in the range of 1.5 to 2.0. According to the method for treating a lithium-nickel-cobalt-containing material of the fifth aspect of the present invention, the pH of the lithium-nickel-cobalt leaching solution in the first leaching step is set to a 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 sixth aspect of the present invention is a method for treating a lithium-nickel-cobalt-containing material according to any one of the first to fifth aspects of the present invention, characterized in that the pH of the lithium-nickel-cobalt leaching 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 of the sixth aspect of the present invention, the pH of the lithium-nickel-cobalt leaching solution in the second leaching step is set to a 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 seventh aspect of the present invention is a method for treating a lithium-nickel-cobalt-containing material, which is the method for treating a lithium-nickel-cobalt-containing material according to any one of the first to sixth aspects of the present invention, characterized in that the second leaching step and the oxidation leaching step are carried out simultaneously. According to the method for treating a lithium-nickel-cobalt-containing material of the seventh aspect of the present invention, by adding hydrogen peroxide to an acidic solution and simultaneously carrying out the second leaching step and the oxidative leaching step, nickel and cobalt can be leached more efficiently from the nickel-cobalt precipitate. [Effects of the Invention]

[0016] According to the present invention, a method for treating lithium-nickel-cobalt-containing material can be provided, which enables efficient recovery of valuable metals such as lithium, nickel, and cobalt from lithium-nickel-cobalt-containing material containing lithium, cobalt, and nickel. [Brief explanation of the drawings]

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

[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 recovers valuable metals such as lithium, nickel, and cobalt from a lithium-nickel-cobalt-containing material that contains lithium, cobalt, and nickel. In this embodiment, the lithium-nickel-cobalt-containing materials of interest are waste lithium-ion battery powder (so-called black mass) obtained by firing and / or pulverizing used lithium-ion batteries, and defective products (so-called black powder) generated in the manufacturing process of cathode materials for secondary batteries, etc.

[0020] The above-mentioned waste lithium-ion battery powder (black mass) and defective products (black powder) contain (a) compounds formed by combining lithium with nickel and cobalt (e.g., LiNiO2, LiCoO2, etc.), (b) compounds derived from the electrolyte (e.g., Li2CO3, etc.), and (c) other compounds (e.g., LiAlO2, metallic Co, metallic Ni, NiO, CoO, etc.). Here, (b) those derived from the electrolyte (e.g., Li2CO3, etc.) are easily soluble in acidic solutions, but (a) those in which lithium is combined with nickel and cobalt (e.g., LiNiO2, LiCoO2, etc.) tend to be less soluble in acidic solutions because nickel and cobalt are trivalent and tetravalent, respectively. Note that (c) others (e.g., LiAlO2, metallic Co, metallic Ni, NiO, CoO, etc.) are almost insoluble 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] (1st 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 acid 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 or more and 24 hours or less) to dissolve the lithium, nickel, and cobalt in the lithium-nickel-cobalt-containing material, thereby obtaining a lithium-nickel-cobalt leachate. In this embodiment, the pH of the lithium-nickel-cobalt leachate in the first leaching step S01 is preferably within 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, it is preferable to use one or more of calcium hydroxide, calcium oxide, and calcium carbonate as the neutralizing agent added in the neutralization step S02. This makes it possible to remove fluorine from the electrolyte of the lithium-ion battery dissolved in the first leaching step S01 as calcium fluoride, thereby obtaining a lithium leachate with high lithium purity, and efficiently produce a nickel-cobalt precipitate containing nickel and cobalt. The pH in the neutralization step S02 is not particularly limited, but is preferably within the range of 8 or more and 12 or less.

[0025] (1st 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. The nickel-cobalt precipitate and the lithium leachate can be separated by solid-liquid separation methods such as gravity settling, centrifugation, or filter cloth filtration using a filter press or the like.

[0026] (Second leaching step S04) In the 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, thereby further leaching 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) is 200 mV or higher.

[0028] Nickel-cobalt precipitates contain nickel and cobalt, and may contain complex compounds that are difficult to dissolve in acid. In these complex oxides, nickel and cobalt exist in high valence states such as trivalent and tetravalent. Here, by adding the hydrogen peroxide until the pH of the nickel-cobalt leachate obtained in the second leaching step S04 is within the range of 1.5 to 2.0 and the oxidation-reduction potential (vs. Ag / AgCl) is 200 mV or higher, trivalent and tetravalent nickel and cobalt are reduced to divalent, thereby facilitating leaching into the acidic solution. In other words, this promotes the dissolution of (a) lithium-nickel-cobalt combinations (e.g., LiNiO2, LiCoO2, etc.) contained in lithium-ion battery powder (black mass), etc., and enables leaching into the acidic solution. The above-mentioned oxidation-reduction potential is more preferably 300 mV or more, and particularly preferably 400 mV or more. 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. The nickel-cobalt leachate can be separated from other solid components by solid-liquid separation methods such as gravity settling, centrifugation, or filter cloth filtration using a filter press or the like.

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

[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 sparingly 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 within the range of 1.5 to 2.0 and the oxidation-reduction potential (vs Ag / AgCl) is 200 mV or higher, so that the nickel and cobalt contained in the nickel-cobalt precipitate can be sufficiently leached. In addition, 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 leachate.

[0035] In the method for treating a lithium-nickel-cobalt-containing material according to 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 this 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 this 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 addition 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. [Example]

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

[0041] (First leaching process) At room temperature, 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 higher (neutralization step). The slurry obtained in the neutralization step was filtered and separated into liquid and dregs (first solid-liquid separation step). The obtained liquid and dregs were subjected to elemental analysis by ICP. Next, 47 vol % sulfuric acid was added to the dregs obtained in the first solid-liquid separation step at room temperature until the pH became 2 or less (second leaching step). Then, hydrogen peroxide solution was added to the slurry whose pH had dropped below 2 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 process was continued until the ORP (oxidation-reduction potential) reached 200 mV (Ag / AgCl) or higher (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] Figure 2 shows the relationship between ORP (oxidation-reduction potential) and metal ion concentration (concentration of dissolved Co and Ni) in the hydrogen peroxide addition step. 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 of Ni in the liquid in the first solid-liquid separation step (g) + amount of Ni in the liquid in the second solid-liquid separation step (g)) / (amount of Ni in the liquid in the first solid-liquid separation step (g) + amount of Ni in the liquid in the second solid-liquid separation step (g) + amount of Ni in the slag in the second solid-liquid separation step (g))] × 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] [Table 1]

[0047] As shown in Figure 2, when hydrogen peroxide is added to the nickel-cobalt leachate in the pH range of 1.5 to 2.0 during the hydrogen peroxide addition process, the ORP (oxidation-reduction potential) increases and the dissolution of Co and Ni progresses. It was confirmed that when the ORP (oxidation-reduction potential) exceeds 200 mV, the increasing trend in the amount of dissolved Co and Ni becomes more gradual. As shown in Table 1, Ni, Co, and Li were sufficiently leached into the liquid, confirming 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 materials that can efficiently recover valuable metals such as lithium, nickel, and cobalt from lithium-nickel-cobalt-containing materials containing 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 nickel-cobalt into the acidic solution to obtain a nickel-cobalt leachate; a hydrogen peroxide addition step in which hydrogen peroxide is added to the nickel-cobalt leachate obtained in the second leaching step to further leach nickel and cobalt; a second solid-liquid separation step of separating the nickel-cobalt leachate obtained in the hydrogen peroxide addition step from a solid component, a step of adding hydrogen peroxide to the nickel-cobalt leachate 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. 2. The method for treating a lithium-nickel-cobalt-containing material according to claim 1, wherein the inorganic acid used in the first leaching step is one or more of sulfuric acid, hydrochloric acid, and nitric acid.

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

4. 4. The method for treating a lithium-nickel-cobalt-containing material according to claim 1, wherein the neutralizing agent added in the neutralization step is one or more of calcium hydroxide, calcium oxide, and calcium carbonate.

5. 4. The method for treating a lithium-nickel-cobalt-containing material according to claim 1, wherein the pH of the lithium-nickel-cobalt leaching solution in the first leaching step is in the range of 1.5 to 2.

0.

6. 4. The method for treating a lithium-nickel-cobalt-containing material according to claim 1, wherein the pH of the nickel-cobalt leachate in the second leaching step is in the range of 1.5 to 2.

5.

7. 4. The method for treating a lithium-nickel-cobalt-containing material according to claim 1, wherein the second leaching step and the hydrogen peroxide addition step are carried out simultaneously.

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