Method for producing nickel leachate

Abstract

Provided is a method for producing a nickel leachate, the method being characterized by including a nickel leaching step (S01) in which a treatment solution containing an inorganic acid is added to a nickel-containing material containing nickel (II) oxide to leach nickel into the treatment solution, the method being also characterized in that a dissolution aid is added to dissolve the nickel (II) oxide in the treatment solution in the nickel leaching step (S01).

Description

Method for producing nickel leachate

[0001] The present invention relates to a method for producing a nickel leachate, in which nickel is recovered as a nickel leachate obtained by leaching nickel from a nickel-containing material containing nickel(II) oxide into a treatment liquid. This application claims priority based on Japanese Patent Application No. 2025-068070 filed in Japan on April 17, 2025, the content of which is incorporated herein by reference.

[0002] In recent years, lithium has been recovered and reused from crushed products of spent lithium-ion batteries obtained by crushing the spent lithium-ion batteries. When recovering lithium from lithium-ion batteries, it is common to use a calcined product of lithium-ion batteries obtained by calcining and crushing spent lithium-ion batteries, i.e., a recycled raw material generally called black mass. The above-described calcined product of lithium-ion batteries contains metals such as nickel and cobalt in addition to lithium. Accordingly, techniques for recovering nickel, which is a valuable metal, from the calcined product of lithium-ion batteries have been proposed.

[0003] For example, Patent Document 1 proposes a method in which a lithium-ion secondary battery is crushed and classified to obtain an electrode material containing nickel and cobalt, the electrode material is immersed in a treatment liquid containing sulfuric acid and hydrogen peroxide to generate a leachate, impurities such as copper and aluminum are removed from the leachate to obtain an eluate containing nickel and cobalt, an alkali metal hydroxide is added to the eluate to adjust the pH, then a hydrogen sulfide compound is added, the mixture is stirred and subjected to solid-liquid separation, and nickel sulfide and cobalt sulfide are recovered.

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

[0005] Incidentally, in Patent Document 1, as described above, by immersing the electrode material in a treatment liquid containing sulfuric acid and hydrogen peroxide, it is possible to efficiently leach nickel and the like from the electrode material into the treatment liquid. However, when a lithium ion secondary battery contains a composite oxide of lithium, nickel, and cobalt as an active material, thermal decomposition may occur during heat treatment to generate nickel (II) oxide. Since this nickel (II) oxide hardly dissolves even when immersed in a treatment liquid containing sulfuric acid and hydrogen peroxide, nickel cannot be efficiently leached, and there is a risk that nickel cannot be sufficiently recovered.

[0006] The present invention has been made in view of the circumstances described above, and an object thereof is to provide a method for producing a nickel leachate capable of efficiently leaching nickel from a nickel-containing substance containing nickel (II) oxide.

[0007] In order to solve the above problems, the method for producing a nickel leachate according to Aspect 1 of the present invention includes a nickel leaching step of adding a treatment liquid containing an inorganic acid to a nickel-containing substance containing nickel (II) oxide to leach nickel into the treatment liquid, wherein in the nickel leaching step, the nickel (II) oxide is dissolved in the treatment liquid by adding a dissolution aid.

[0008] According to the method for producing a nickel leachate of Aspect 1 of the present invention, in the nickel leaching step of leaching nickel into the treatment liquid by adding the treatment liquid containing an inorganic acid to the nickel-containing substance containing nickel (II) oxide, a dissolution aid is further added, so that nickel (II) oxide can be dissolved in the treatment liquid, and it becomes possible to obtain a nickel leachate in which nickel contained in the nickel-containing substance is sufficiently leached.

[0009] A method for producing nickel leaching solution according to aspect 2 of the present invention comprises: a lithium leaching step in which a treatment solution containing an inorganic acid is added to a nickel-containing material containing nickel(II) oxide and lithium to leach lithium into the treatment solution; a neutralization step in which a neutralizing agent is added to the treatment solution after the lithium leaching step to generate a nickel precipitate containing nickel; a nickel precipitate separation step in which the nickel precipitate generated in the neutralization step is separated to obtain a lithium leaching solution; and a nickel leaching step in which a treatment solution containing an inorganic acid is added to the nickel precipitate to leach nickel into the treatment solution, wherein in the nickel leaching step, a solubilizing agent is added to dissolve the nickel(II) oxide in the treatment solution.

[0010] According to the method for producing nickel leaching solution of embodiment 2 of the present invention, the method includes a lithium leaching step of leaching lithium from a nickel-containing material containing nickel(II) oxide and lithium, a neutralization step of adding a neutralizing agent to the treatment solution after the lithium leaching step to generate a nickel precipitate, and a nickel precipitate separation step of separating the nickel precipitate generated in the neutralization step to obtain a lithium leaching solution. As a result, the lithium leaching solution obtained in the nickel precipitate separation step does not contain elements constituting the solubilizing aid, and lithium can be recovered from the lithium leaching solution relatively easily.

[0011] Furthermore, in the nickel leaching step, in which nickel is leached into the treatment solution by adding a treatment solution containing an inorganic acid to the nickel precipitate separated in the nickel precipitate separation step, a solubilizer is added, so that nickel(II) oxide can be dissolved in the treatment solution, and a nickel leaching solution from which nickel contained in the nickel-containing material has been sufficiently leached can be obtained.

[0012] The method for producing nickel leaching according to aspect 3 of the present invention is characterized in that, in the method for producing nickel leaching according to aspect 1 or aspect 2 of the present invention, the nickel-containing material is a battery calcined product obtained by calcining crushed lithium-ion battery material. According to the method for producing nickel leaching according to aspect 3 of the present invention, it is possible to obtain a nickel leaching solution from which nickel contained in lithium-ion batteries has been sufficiently leached, and nickel can be recovered efficiently.

[0013] The method for producing nickel leaching according to aspect 4 of the present invention is characterized in that the solubilizer is a hypochlorite salt in the method for producing nickel leaching according to any one of aspects 1 to 3 of the present invention. According to the method for producing nickel leaching according to aspect 4 of the present invention, since the solubilizer is a hypochlorite salt, it is possible to further promote the dissolution of nickel(II) oxide in the treatment solution, and it is possible to obtain a nickel leaching solution in which the nickel contained in the nickel-containing material has been further sufficiently leached out.

[0014] The method for producing a nickel leached solution according to aspect 5 of the present invention is characterized in that, in the method for producing a nickel leached solution according to aspect 4 of the present invention, the pH of the treatment solution in the nickel leaching step is within the range of 1.7 to 2.6. According to the method for producing a nickel leached solution according to aspect 5 of the present invention, since the pH of the treatment solution in the nickel leaching step is within the range of 1.7 to 2.6, the dissolution of nickel(II) oxide in the treatment solution can be further promoted, and it is possible to obtain a nickel leached solution in which the nickel contained in the nickel-containing material has been further sufficiently leached out.

[0015] The method for producing a nickel leached solution according to aspect 6 of the present invention is characterized in that, in the method for producing a nickel leached solution according to aspect 4 of the present invention, in the nickel leaching step, it is determined that the leaching of nickel is complete when the oxidation-reduction potential of the treatment solution is maintained at 1100 mV or higher for 2 minutes or more. According to the method for producing a nickel leached solution according to aspect 6 of the present invention, in the nickel leaching step, it is determined that the leaching of nickel is complete when the oxidation-reduction potential of the treatment solution is maintained at 1100 mV or higher for 2 minutes or more, so that a nickel leached solution from which nickel contained in the nickel-containing material has been sufficiently leached can be obtained, the use of inorganic acids and solubilizers can be suppressed to the extent necessary, and costs can be reduced.

[0016] The method for producing nickel leaching solution according to aspect 7 of the present invention is characterized in that, in the method for producing nickel leaching solution according to any one of aspects 1 to 4 of the present invention, hydrogen peroxide is added to the treatment solution after it is determined that the leaching of nickel is complete in the nickel leaching step, thereby bringing the oxidation-reduction potential to a state of 500 mV to 700 mV. According to the method for producing nickel leaching solution according to aspect 7 of the present invention, since hydrogen peroxide is added to the treatment solution after it is determined that the leaching of nickel is complete in the nickel leaching step, thereby bringing the oxidation-reduction potential to a state of 500 mV to 700 mV, the oxidizing power of the acidic liquid after the leaching of nickel is complete is suppressed, making subsequent handling easier.

[0017] According to the present invention, it is possible to provide a method for producing a nickel leaching solution that can efficiently leach nickel from a nickel-containing material containing nickel(II) oxide.

[0018] This is a flow chart showing the method for producing nickel leaching, which is the first embodiment of the present invention. This is a flow chart showing the method for producing nickel leaching, which is the second embodiment of the present invention. This is a graph showing the relationship between processing time and the amount of metal dissolved, the relationship between processing time and the oxidation-reduction potential (ORP), and the relationship between processing time and the amount of reagent in the comparative example. This is a graph showing the relationship between processing time and the amount of metal dissolved, the relationship between processing time and the oxidation-reduction potential (ORP), and the relationship between processing time and the amount of reagent in Example 1 of the present invention. This is a graph showing the XRD measurement results of the raw material, the leaching residue of Example 1 of the present invention, and the leaching residue of the comparative example. This is a graph showing the relationship between processing time and the amount of metal dissolved, the relationship between processing time and the oxidation-reduction potential (ORP), and the relationship between processing time and the amount of reagent in Example 2-1 of the present invention. This is a graph showing the relationship between processing time and the amount of metal dissolved, the relationship between processing time and the oxidation-reduction potential (ORP), and the relationship between processing time and the amount of reagent in Example 2-2 of the present invention. This is a graph showing the relationship between processing time and the amount of metal dissolved, the relationship between processing time and the oxidation-reduction potential (ORP), and the relationship between processing time and the amount of reagent in Example 2-3 of the present invention. This graph shows the relationship between processing time and the amount of metal dissolved, the relationship between processing time and oxidation-reduction potential (ORP), and the relationship between processing time and the amount of reagent in Example 3 of the present invention.

[0019] An example of an embodiment of the present invention will be described below.

[0020] The method for producing nickel leaching in this embodiment involves recovering nickel leaching from a nickel-containing material containing nickel(II) oxide into a processing solution. In this embodiment, the target nickel-containing material is lithium-ion battery calcined material (so-called black mass) obtained by calcining and pulverizing used lithium-ion batteries. This lithium-ion battery calcined material (black mass) contains lithium, nickel, and cobalt as valuable metals.

[0021] In lithium-ion batteries, LiNi is used as the active material. ｘ C ｙ M ｚ O ２When a composite oxide of lithium, nickel, and cobalt (such as M = Al, Mn) is present, this composite oxide may decompose during the heating process in calcination, generating nickel(II) oxide. Since this nickel(II) oxide is poorly soluble in treatment solutions containing sulfuric acid and hydrogen peroxide, it is necessary to sufficiently dissolve the nickel(II) oxide in order to efficiently leach nickel. Therefore, in the nickel leaching solution manufacturing method of this embodiment, the dissolution of nickel(II) oxide is promoted by the following configuration.

[0022] <First Embodiment> First, the method for producing nickel leaching, which is the first embodiment of the present invention, will be described with reference to the flow chart in Figure 1. As shown in Figure 1, the method for producing nickel leaching according to this embodiment includes a nickel leaching step S01 in which a treatment solution containing an inorganic acid is added to a nickel-containing material (black mass) containing nickel(II) oxide to leach nickel into the treatment solution, and a solid-liquid separation step S02 in which solid matter (leaching residue) contained in the treatment solution after the nickel leaching step S01 is separated to obtain nickel leaching.

[0023] (Nickel leaching process S01) In this nickel leaching process S01, a treatment solution containing an inorganic acid is added to the black mass containing nickel(II) oxide to leach the nickel. At this time, a solubilizer is added to the treatment solution to dissolve the sparingly soluble nickel(II) oxide. It is preferable that the temperature of the treatment solution in nickel leaching process S01 be within the range of 50°C to 70°C. By setting the temperature of the treatment solution in nickel leaching process S01 to 50°C or higher, the reactivity between the inorganic acid and the black mass is improved, and the time required for the reaction can be shortened. On the other hand, even if the temperature of the treatment solution in nickel leaching process S01 is heated above 70°C, the reactivity between the inorganic acid and the black mass does not improve significantly. In this embodiment, since the black mass contains lithium and cobalt in addition to nickel, lithium and cobalt will also be leached into the treatment solution along with the nickel.

[0024] The inorganic acid contained in the treatment solution is not particularly limited, and sulfuric acid, hydrochloric acid, nitric acid, etc., can be used. In this embodiment, sulfuric acid is used. In addition, hypochlorites (sodium hypochlorite, potassium hypochlorite, calcium hypochlorite), potassium permanganate, nitric acid, ozone, etc., can be used as solubilizers. In this embodiment, sodium hypochlorite (NaClO) is used.

[0025] When sodium hypochlorite is added, it may react with the inorganic acid to generate chlorine gas. However, if metal elements are present, sodium hypochlorite will preferentially react with these metal elements, thereby suppressing the generation of chlorine gas. Therefore, in this embodiment, it is also possible to suppress the generation of chlorine gas by first adding a treatment solution containing an inorganic acid to the black mass containing nickel(II) oxide and mixing it thoroughly, and then slowly adding sodium hypochlorite.

[0026] In the nickel leaching process S01, the pH of the treatment solution when sodium hypochlorite is added is preferably 1.7 to 2.6, and more preferably 1.7 to 2.2. When the pH is less than 1.7, there is an excess of acid that does not contribute to leaching, resulting in a waste of inorganic acid, and the risk of reaction between sodium hypochlorite and inorganic acid increases. When the pH is greater than 2.6, the leaching ability of cobalt and nickel decreases. In addition, the amount of sodium hypochlorite required to dissolve nickel increases, resulting in poor efficiency of the chemical.

[0027] Furthermore, in this nickel leaching process S01, it is preferable to measure the pH and oxidation-reduction potential of the treatment solution and determine that nickel leaching is complete when the pH is within the range of 1.7 to 2.6 and the oxidation-reduction potential is maintained at 1100 mV or higher for 2 minutes or more. By determining the endpoint of nickel leaching in this way, the amount of solubilizer (sodium hypochlorite) and other substances used can be optimized.

[0028] (Solid-liquid separation step S02) In this solid-liquid separation step S02, a nickel leachate is obtained by separating the solid matter (leaching residue) contained in the processing liquid after the nickel leaching step S01. There are no particular restrictions on the method of separating the solid matter (leaching residue), and various existing methods can be appropriately selected and used. In this embodiment, a vacuum filtration method is applied.

[0029] Through the processes described above, a nickel leaching solution can be obtained in which nickel has leached into the processing liquid. Furthermore, it is possible to recover nickel, a valuable metal, from this nickel leaching solution. In addition, as mentioned above, the nickel leaching solution of this embodiment also contains lithium and cobalt, so it is possible to recover lithium and cobalt, as well as nickel, from this nickel leaching solution.

[0030] In the nickel leaching method of this embodiment, which has the above configuration, in the nickel leaching step S01, in which nickel is leached into the treatment solution by adding a treatment solution containing an inorganic acid (sulfuric acid) to a nickel-containing material (black mass) containing nickel(II) oxide, a solubilizing agent (sodium hypochlorite in this embodiment) is added, so that nickel(II) oxide can be dissolved in the treatment solution, and it is possible to obtain a nickel leaching method in which the nickel contained in the nickel-containing material has been sufficiently leached out.

[0031] Furthermore, in this embodiment, if the nickel-containing material containing nickel(II) oxide is a battery calcined product obtained by calcining crushed lithium-ion battery material, a nickel leachate can be obtained in which the nickel contained in the lithium-ion battery has been sufficiently leached out, making it possible to efficiently recover nickel. In addition, lithium and cobalt, which are valuable metals other than nickel, can also be leached out, and a nickel leachate containing these lithium and cobalt can be obtained.

[0032] Furthermore, in this embodiment, if, in the nickel leaching process S01, the nickel leaching is determined to be complete when the pH is within the range of 1.7 to 2.6 and the oxidation-reduction potential is maintained at 1100 mV or higher for 2 minutes or more, a nickel leaching solution can be obtained in which the nickel contained in the nickel-containing material has been sufficiently leached out. This reduces the need to use inorganic acids and solubilizers (sodium hypochlorite) more than necessary, thereby reducing costs.

[0033] Furthermore, in this embodiment, it is preferable to add hydrogen peroxide solution after determining that the nickel leaching process S01 is complete, thereby bringing the oxidation-reduction potential of the treatment solution to a state of 500 mV to 700 mV. This suppresses the oxidizing power of the acidic liquid after leaching is complete, making the subsequent solid-liquid separation process S02 and the handling of the equipment and components easier.

[0034] <Second Embodiment> Next, a method for producing nickel leaching solution, which is a second embodiment of the present invention, will be described with reference to the flow chart in Figure 2. As shown in Figure 2, the method for producing nickel leaching solution according to this embodiment comprises: a lithium leaching step S11 in which a treatment solution containing an inorganic acid is added to a nickel-containing material (black mass) containing nickel(II) oxide and lithium to leach lithium into the treatment solution; a neutralization step S12 in which a neutralizing agent is added to the treatment solution after the lithium leaching step S11 to generate a nickel precipitate containing nickel; a nickel precipitate separation step S13 in which the nickel precipitate generated in the neutralization step S12 is separated to obtain a lithium leaching solution; a nickel leaching step S14 in which a treatment solution containing an inorganic acid is added to the nickel precipitate to leach nickel into the treatment solution; and a solid-liquid separation step S15 in which solid matter (leaching residue) contained in the treatment solution after the nickel leaching step S14 is separated to obtain a nickel leaching solution.

[0035] (Lithium leaching process S11) In this lithium leaching process S11, a treatment solution containing an inorganic acid is added to the black mass containing nickel(II) oxide to leach lithium. In this embodiment, the black mass contains nickel and cobalt in addition to lithium, but simply adding a treatment solution containing an inorganic acid will not dissolve some of the nickel and cobalt, such as nickel(II) oxide, in the treatment solution, resulting in the selective leaching of lithium. There are no particular limitations on the inorganic acid contained in the treatment solution, and sulfuric acid, hydrochloric acid, nitric acid, etc., can be used. In this embodiment, sulfuric acid is used. Furthermore, it is preferable that the temperature of the treatment solution in the lithium leaching process S11 be within the range of 20°C to 80°C. In addition, it is preferable that the pH of the treatment solution in the lithium leaching process S11 be within the range of 1 to 3.

[0036] (Neutralization step S12) Next, a neutralizing agent is added to the treatment solution from the lithium leaching step S11 to generate a nickel precipitate containing nickel. In this embodiment, as mentioned above, since the black mass being treated contains cobalt, this nickel precipitate will also contain cobalt. Here, an alkali such as calcium hydroxide or sodium hydroxide can be used as the neutralizing agent. In this embodiment, calcium hydroxide is used. Furthermore, the pH of the treatment solution after adding the neutralizing agent is preferably in the range of 8 to 12, and more preferably in the range of 9 to 11.

[0037] (Nickel precipitate separation step S13) Next, the nickel precipitate formed in the neutralization step S12 is separated from the processing liquid to obtain a lithium leachate. The nickel precipitate contains insoluble components from the lithium leaching step S11, including nickel(II) oxide (NiO). There are no particular restrictions on the method of separating the nickel precipitate, and various existing methods such as gravity sedimentation, centrifugal separation, or filter cloth filtration using a filter press can be appropriately selected and used. In this embodiment, a vacuum filtration method is applied.

[0038] (Nickel leaching process S14) In this nickel leaching process S14, a treatment solution containing an inorganic acid is added to the nickel precipitate separated in the nickel precipitate separation process S13 to leach nickel. At this time, a solubilizer is added to the treatment solution to dissolve the sparingly soluble nickel(II) oxide. It is preferable that the temperature of the treatment solution in the nickel leaching process S14 be within the range of 50°C to 70°C. In this embodiment, since the nickel precipitate contains cobalt in addition to nickel, cobalt will also be leached into the treatment solution along with the nickel.

[0039] The inorganic acid contained in the treatment solution is not particularly limited, and sulfuric acid, hydrochloric acid, nitric acid, etc., can be used. In this embodiment, sulfuric acid is used. In addition, hypochlorites (sodium hypochlorite, potassium hypochlorite, calcium hypochlorite), potassium permanganate, nitric acid, ozone, etc., can be used as solubilizers. In this embodiment, sodium hypochlorite (NaClO) is used.

[0040] When sodium hypochlorite is added, it may react with the inorganic acid to generate chlorine gas. However, if metal elements are present, sodium hypochlorite will preferentially react with these metal elements, thereby suppressing the generation of chlorine gas. Therefore, in this embodiment, it is also possible to suppress the generation of chlorine gas by first adding a treatment solution containing an inorganic acid to a nickel precipitate containing nickel(II) oxide and mixing it thoroughly, and then slowly adding sodium hypochlorite.

[0041] In the nickel leaching process S14, the pH of the treatment solution when sodium hypochlorite is added is preferably 1.7 to 2.6, and more preferably 1.7 to 2.2. When the pH is less than 1.7, there is an excess of acid that does not contribute to leaching, resulting in a waste of inorganic acid, and the risk of reaction between sodium hypochlorite and inorganic acid increases. When the pH is greater than 2.6, the leaching ability of cobalt and nickel decreases. In addition, the amount of sodium hypochlorite required to dissolve nickel increases, resulting in poor efficiency of the chemical.

[0042] Furthermore, in this nickel leaching process S14, it is preferable to measure the pH and oxidation-reduction potential of the treatment solution and determine that nickel leaching is complete when the pH is within the range of 1.7 to 2.6 and the oxidation-reduction potential is maintained at 1100 mV or higher for 2 minutes or more. By determining the endpoint of nickel leaching in this way, the amount of solubilizer (sodium hypochlorite) and other substances used can be optimized.

[0043] (Solid-liquid separation step S15) In this solid-liquid separation step S15, a nickel leachate is obtained by separating the solid matter (leaching residue) contained in the processing liquid after the nickel leaching step S14. There are no particular restrictions on the method of separating the solid matter (leaching residue), and various existing methods can be appropriately selected and used. In this embodiment, a vacuum filtration method is applied.

[0044] Through the processes described above, a nickel leachate can be obtained in which nickel has leached into the processing liquid. It is then possible to recover nickel, a valuable metal, from this nickel leachate. Furthermore, in this embodiment, since the nickel leachate also contains cobalt, as described above, it is possible to recover cobalt in addition to nickel, a valuable metal, from this nickel leachate. Additionally, it is possible to recover lithium, a valuable metal, from the lithium leachate obtained in the nickel precipitate separation step S13.

[0045] The method for producing nickel leaching according to this embodiment, which has the above configuration, includes a lithium leaching step S11 for leaching lithium from a nickel-containing material (black mass) containing nickel(II) oxide and lithium, a neutralization step S12 for adding a neutralizing agent to the treated liquid after the lithium leaching step S11 to generate a nickel precipitate, and a nickel precipitate separation step S13 for separating the nickel precipitate generated in the neutralization step S12. As a result, the lithium leaching obtained in the nickel precipitate separation step S13 is not contaminated with elements constituting the solubilizing agent (sodium hypochlorite in this embodiment) (sodium, etc. in this embodiment), and lithium can be recovered from the lithium leaching relatively easily.

[0046] In other words, because lithium and sodium have similar properties, if sodium is mixed into the lithium leachate, it becomes difficult to separate the lithium and sodium, and there is a risk that lithium cannot be efficiently recovered from the lithium leachate. In this embodiment, since no solubilizer (sodium hypochlorite) is used when leaching lithium, sodium does not mix into the lithium leachate, and lithium can be efficiently recovered from the lithium leachate.

[0047] Furthermore, in the nickel leaching step S14, in which nickel is leached into the treatment solution by adding a treatment solution containing an inorganic acid to the nickel precipitate separated in the nickel precipitate separation step S13, a hypochlorite salt is added, which allows nickel(II) oxide to dissolve in the treatment solution, making it possible to obtain a nickel leaching solution from which nickel contained in the nickel-containing material has been sufficiently leached.

[0048] Furthermore, in this embodiment, if the nickel-containing material containing nickel(II) oxide is a battery calcined product obtained by calcining crushed lithium-ion battery material, a nickel leachate can be obtained in which the nickel contained in the lithium-ion battery has been sufficiently leached out, making it possible to efficiently recover nickel. In addition, lithium and cobalt, which are valuable metals other than nickel, can also be leached out, and a nickel leachate containing these lithium and cobalt can be obtained.

[0049] Furthermore, in this embodiment, in the nickel leaching step S14, the pH and oxidation-reduction potential of the treatment solution are measured, and when it is determined that nickel leaching is complete when the pH is within the range of 1.7 to 2.6 and the oxidation-reduction potential is 1100 mV or higher for 2 minutes or more, a nickel leaching solution can be obtained in which the nickel contained in the nickel-containing material has been sufficiently leached out. This reduces the need to use inorganic acids and solubilizers (sodium hypochlorite) more than necessary, thereby reducing costs.

[0050] Furthermore, in the present embodiment, after it is determined that the nickel leaching is completed in the nickel leaching step S14, it is preferable to add hydrogen peroxide solution to set the oxidation-reduction potential of the treatment liquid to a state of 500 mV or more and 700 mV or less. Thereby, the oxidizing power of the acidic liquid after the completion of leaching can be suppressed, and the subsequent solid-liquid separation step S15 and the handling of apparatuses and members are facilitated.

[0051] The embodiments of the present invention have been described above, but the present invention is not limited thereto, and can be appropriately modified within the range not departing from the technical idea of the invention.

[0052] Hereinafter, the results of confirmation experiments conducted to verify the effectiveness of the present invention will be described.

[0053] As the treatment target, LiNi ｘ Co ｙ M ｚ O ２ (M = Al, Mn, etc.), a lithium ion battery calcined product (black mass) obtained by calcining and pulverizing a lithium ion battery containing a composite oxide of lithium, nickel and cobalt was prepared.

[0054] (Comparative Example) 80 g of the above-mentioned black mass was charged into a 1 L separable flask. Next, 800 mL of water (H ２ O) and 90 mL of 47 mass% sulfuric acid (H ２ SO ４ ) were added and stirred, and the pH was adjusted to 2 or less, and the liquid temperature was adjusted to 60°C. Next, while maintaining the liquid temperature at 60°C, addition of 30 mass% hydrogen peroxide (H ２ O ２ ) and 47 mass% sulfuric acid (H ２ SO ４ ) and stirring were repeated. At this time, after measuring the oxidation-reduction potential after stirring, a part of the liquid component was collected, and the concentrations of lithium, nickel, cobalt, manganese, iron, and copper were measured using an inductively coupled plasma optical emission spectrometry (ICP-OES) method, and the dissolved amount of each metal in the liquid component was calculated from the liquid volume of the liquid component and each measured metal concentration. Hydrogen peroxide was added until the dissolved amount of nickel in the liquid component no longer changed, and finally a total of 40 mL of hydrogen peroxide was added. During this period, sulfuric acid (H ２ SO ４A total of 8.0 mL of the solution was added, and the pH was adjusted to between 1.87 and 1.97, and the liquid temperature to 60°C.

[0055] Next, the liquid component (leachate) and solid component (cake) were separated by vacuum filtration. The amount of leachate obtained was 867 mL. The oxidation-reduction potential was measured using a portable ion / pH meter (Toa DKK Corporation, IM-32P model) and an ORP composite electrode (Toa DKK Corporation, PST-5721C). The separated cake was washed with distilled water to obtain 336 mL of the post-wash solution. By drying the post-wash cake, 41.35 g of leachate residue was obtained.

[0056] Tables 1-3 show the evaluation results of the nickel, cobalt, and manganese content in the obtained leachate, wash solution, and leachate residue. The amount of each element in the leachate and wash solution was measured using inductively coupled plasma optical emission spectroscopy (ICP-OES), and the amount of each element in the leachate residue was measured using X-ray fluorescence spectroscopy (XRF). Figure 3 shows the relationship between treatment time and metal dissolution, the relationship between treatment time and oxidation-reduction potential (ORP), and the relationship between treatment time and reagent amount.

[0057]

[0058]

[0059]

[0060] (Example 1 of the present invention) Put 80 g of the above-mentioned black mass into a 1 L separable flask and water (H ２ O) 800 mL was added and stirred. Next, 47% by mass sulfuric acid (H) was added to the slurry while stirring. ２ SO ４ 90.0 mL was added, and the pH was adjusted to 2 or less, and the liquid temperature to 60°C. Next, while maintaining the liquid temperature at 60°C, 12% by mass sodium hypochlorite (NaClO) and 47% by mass sulfuric acid (H) were added. ２ SO ４The addition and stirring of sulfuric acid (H) was repeated. During this process, the oxidation-reduction potential was measured after stirring, and a portion of the liquid was taken. The concentrations of lithium, nickel, cobalt, manganese, iron, and copper were measured using inductively coupled plasma optical emission spectroscopy (ICP-OES), and the amount of each metal dissolved in the liquid was calculated from the volume of the liquid and the measured concentrations of each metal. Sodium hypochlorite was added until the amount of nickel dissolved in the liquid stopped changing, and a total of 44.0 mL of sodium hypochlorite was added in total. During this time, sulfuric acid (H) was added. ２ SO ４ A total of 17.0 mL of the solution was added, and the pH was adjusted to between 1.85 and 2.26. The oxidation-reduction potential was measured using a portable ion / pH meter (Toa DKK Corporation, IM-32P model) and an ORP composite electrode (Toa DKK Corporation, PST-5721C).

[0061] After the amount of nickel dissolved in the liquid component stops changing and nickel leaching is complete, hydrogen peroxide (H ２ O ２ ) 2.0 mL and sulfuric acid (H ２ SO ４ 6.0 mL was added, and the pH was adjusted to 2 or less and the liquid temperature to 60°C. Next, solid-liquid separation was performed by vacuum filtration to separate the liquid component (leachate) from the solid component (cake). The amount of leachate obtained was 874 mL. Note that hydrogen peroxide (H) ２ O ２ The addition of ) is to suppress contact of highly oxidative acidic liquids with materials and test equipment during the solid-liquid separation process after leaching is complete. The separated cake was then washed with distilled water to obtain 310 mL of the post-wash solution. By drying the post-wash cake, 33.32 g of leaching residue was obtained.

[0062] Tables 4-6 show the evaluation results of the nickel, cobalt, and manganese content in the obtained leachate, wash solution, and leachate residue. The amount of each element in the leachate and wash solution was measured using inductively coupled plasma optical emission spectroscopy (ICP-OES), and the amount of each element in the leachate residue was measured using X-ray fluorescence spectroscopy (XRF). Figure 4 shows the relationship between treatment time and metal dissolution, the relationship between treatment time and oxidation-reduction potential (ORP), and the relationship between treatment time and reagent amount.

[0063]

[0064]

[0065]

[0066] Here, we calculate the nickel leaching rate (Ni leaching rate) and the cobalt leaching rate (Co leaching rate) in the leaching solution of the comparative example and Example 1 of the present invention. The nickel leaching rate (Ni leaching rate) and the cobalt leaching rate (Co leaching rate) are calculated using the following formulas: Ni leaching rate (%) = [Amount of nickel in leaching solution (g) + Amount of nickel in the solution after washing (g)] / [Amount of nickel in leaching solution (g) + Amount of nickel in the solution after washing (g) + Amount of nickel in the leaching residue (g)] × 100 ... (1) Co leaching rate (%) = [Amount of cobalt in leaching solution (g) + Amount of cobalt in the solution after washing (g)] / [Amount of cobalt in leaching solution (g) + Amount of cobalt in the solution after washing (g) + Amount of cobalt in the leaching residue (g)] × 100 ... (2)

[0067] In Comparative Example 1, which used hydrogen peroxide, the leaching rate of nickel was 71% and the leaching rate of cobalt was 70%. In contrast, in Example 1 of the present invention, which used sodium hypochlorite, the leaching rate of nickel was 96% and the leaching rate of cobalt was 96%. It was confirmed that using sodium hypochlorite when leaching nickel significantly improved the leaching rates of both nickel and cobalt.

[0068] Here, Figure 5 shows the XRD measurement results for the raw material (black mass), the leaching residue of the comparative example, and the leaching residue of Example 1 of the present invention. The XRD patterns shown in Figure 5 are, from top to bottom, the XRD patterns of the leaching residue of Example 1 of the present invention, the leaching residue of the comparative example, and the raw material (black mass). In the black mass, peaks for Ni and NiO (nickel(II) oxide) are observed. In the leaching residue of the comparative example, no peak for Ni is observed, but a peak for NiO is observed, confirming that Ni was dissolved but NiO was not. In the leaching residue of Example 1 of the present invention, no peaks for Ni or NiO (nickel(II) oxide) are observed, confirming that both Ni and NiO are dissolved.

[0069] Furthermore, in the comparative example, as shown in Figure 3, the amount of nickel and cobalt dissolved did not increase even when the amount of hydrogen peroxide added increased. On the other hand, in Example 1 of the present invention, as shown in Figure 4, the amount of nickel and cobalt dissolved increased as the amount of sodium hypochlorite added increased. It was confirmed that the dissolution of nickel and cobalt was promoted by the addition of sodium hypochlorite. Also, as shown in Figure 4, the oxidation-reduction potential (ORP) increased with the increase in the amount of nickel dissolved, and it was confirmed that the oxidation-reduction potential (ORP) exceeded 1100 mV when the amount of nickel dissolved stopped changing. At this time, the state of oxidation-reduction potential (ORP) of 1100 mV or higher was maintained for more than 2 minutes. Thus, it was confirmed that the endpoint of nickel dissolution can be determined by the oxidation-reduction potential (ORP).

[0070] (Example 2 of the present invention) Next, we will describe the experimental results obtained by carrying out the second embodiment of the present invention described above, and confirming the appropriate pH range when sodium hypochlorite (NaClO) is added as a dissolving aid in the nickel leaching process.

[0071] (Example 2-1 of the present invention) 80 g of the above-mentioned black mass was placed in a 1 L separable flask. Water (H) was added to it. ２ O) 400 mL and 47% by mass sulfuric acid (H ２ SO ４) 42.0 mL was added and the pH was adjusted to 2 or less. Next, calcium hydroxide (Ca(OH)) was added as a neutralizing agent. ２ 11 g was added to form a precipitate containing nickel and cobalt. Next, solid-liquid separation was performed by vacuum filtration to separate the liquid component (Li leachate) from the solid component (cake). The resulting Li leachate was 329 mL. The separated cake was washed with distilled water to obtain 407 mL of the post-wash solution (Li post-wash solution) and 140.57 g (wet) of the post-wash cake (corresponding to the nickel precipitate).

[0072] Here, the amounts of lithium, nickel, and cobalt in the obtained Li leachate, the post-wash solution, and the post-wash cake (nickel precipitate) were evaluated. The amounts of each element in the leachate and post-wash solution were measured using inductively coupled plasma optical emission spectroscopy (ICP-OES), and the amounts of each element in the leachate residue were measured using X-ray fluorescence spectroscopy (XRF). The evaluation results are shown in Tables 7 to 9.

[0073]

[0074]

[0075]

[0076] Next, in a 1 L separable flask, add 140.57 g (wet) of the washed cake (nickel precipitate) and water (H ２ O) 800 mL was added and stirred. Next, 47% by mass sulfuric acid (H) was added to the slurry while stirring. ２ SO ４ ) 70.0 mL was added, and the pH was adjusted to 2 or less and the liquid temperature to 60°C. Next, while maintaining the liquid temperature at 60°C, 12% by mass sodium hypochlorite (NaClO) and 47% by mass sulfuric acid (H ２ SO ４The addition and stirring of sodium hypochlorite and sulfuric acid were repeated. During this process, the oxidation-reduction potential was measured after stirring, and a portion of the liquid was taken. The concentrations of lithium, nickel, cobalt, manganese, iron, and copper were measured using inductively coupled plasma optical emission spectroscopy (ICP-OES). The amount of each metal dissolved in the liquid was calculated from the volume of the liquid and the measured concentrations of each metal. Sodium hypochlorite and sulfuric acid were added until the amount of nickel dissolved in the liquid stopped changing, and a total of 44.0 mL of sodium hypochlorite was added in total. During this time, a total of 19 mL of sulfuric acid was added to adjust the pH to between 1.7 and 2.2. The oxidation-reduction potential was measured using a portable ion / pH meter (Toa DKK Corporation, IM-32P model) and an ORP composite electrode (Toa DKK Corporation, PST-5721C).

[0077] Next, 30% by mass hydrogen peroxide (H ２ O ２ ) 2.0 mL and 47% by mass sulfuric acid (H ２ SO ４ ) 4.0 mL was added, and the pH was adjusted to 2 or less, and the liquid temperature to 60°C. Note that hydrogen peroxide (H ２ O ２ The addition of ) is to prevent the highly oxidative acidic liquid from coming into contact with the materials and test equipment in the process after leaching is complete. Next, the liquid component (leached liquid) and solid component (cake) were separated by vacuum filtration. The amount of leached liquid obtained was 882 mL. The separated cake was washed with distilled water to obtain 362 mL of post-wash liquid. By drying the post-wash cake, 48.20 g of leaching residue was obtained.

[0078] The amounts of nickel, cobalt, and lithium in the obtained leachate, wash solution, and leachate residue were evaluated. The amounts of each element in the leachate and wash solution were measured using inductively coupled plasma optical emission spectroscopy (ICP-OES), and the amounts of each element in the leachate residue were measured using X-ray fluorescence spectroscopy (XRF). The evaluation results are shown in Tables 10 to 12. Furthermore, Figure 6 shows the relationship between treatment time and the amount of metal dissolved, the relationship between treatment time and oxidation-reduction potential (ORP), and the relationship between treatment time and the amount of reagent in the process of leaching nickel precipitate.

[0079]

[0080]

[0081]

[0082] Here, the lithium leaching rate into the Li leaching solution of Example 2-1 of the present invention was calculated. The lithium leaching rate (Li leaching rate) is calculated using the following formula. Note that the amount of lithium remaining in the cake after washing is small and has little effect on the lithium balance, so it was calculated using the following formula. Li leaching rate (%) = [Amount of lithium in Li leaching solution (g) + Amount of lithium in Li post-wash solution (g)] / [Amount of lithium in Li leaching solution (g) + Amount of lithium in Li post-wash solution (g) + Amount of lithium in leaching solution (g) + Amount of lithium in post-wash solution (g)] × 100 ... (3) The lithium leaching rate was 93%, indicating that lithium could be sufficiently leached using sulfuric acid. Furthermore, as shown in Table 9, nickel and cobalt were not contained in the Li leaching solution or the Li post-wash solution, and it was confirmed that nickel and cobalt had migrated to the cake (nickel precipitate) after washing.

[0083] Next, the leaching rates of nickel (Ni leaching rate) and cobalt (Co leaching rate) in the leaching solution were calculated using the above-mentioned formulas (1) and (2) when the cake (nickel precipitate) after washing following lithium leaching was subjected to leaching treatment. In Example 2-1 of the present invention, which used sodium hypochlorite, the nickel leaching rate was 98% and the cobalt leaching rate was 98%.

[0084] Furthermore, as shown in Figure 6, the oxidation-reduction potential (ORP) increases with increasing nickel dissolution, and it can be confirmed that the ORP exceeds 1100 mV when the nickel dissolution rate stops changing. At this point, the ORP remained above 1100 mV for more than two minutes. Thus, it is confirmed that the endpoint of nickel dissolution can be determined by the oxidation-reduction potential (ORP).

[0085] (Example 2-2 of the present invention) 80 g of the above-mentioned black mass was placed in a 1 L separable flask. Water (H) was added to it. ２O) 400 mL and 47% by mass sulfuric acid (H ２ SO ４ ) 40.0 mL was added and the pH was adjusted to 2 or less. Next, calcium hydroxide (Ca(OH)) was added as a neutralizing agent. ２ 10 g of ) was added to form a precipitate containing nickel and cobalt. Next, solid-liquid separation was performed by vacuum filtration to separate the liquid component (Li leachate) from the solid component (cake). The resulting Li leachate was 340 mL. The separated cake was washed with distilled water to obtain 846 mL of the post-wash solution (Li post-wash solution) and 153.80 g (wet) of the post-wash cake (corresponding to the nickel precipitate).

[0086] Here, the amounts of lithium, nickel, and cobalt in the obtained Li leachate, Li wash solution, and wash cake (nickel precipitate) were evaluated. The evaluation results are shown in Tables 13 to 15. The amounts of each element in the leachate and wash solution were measured using inductively coupled plasma optical emission spectroscopy (ICP-OES), and the amounts of each element in the leachate residue were measured using X-ray fluorescence spectroscopy (XRF).

[0087]

[0088]

[0089]

[0090] Next, in a 1 L separable flask, add 148.80 g (wet) of the washed cake (nickel precipitate) and water (H ２ O) 800 mL was added and stirred. Next, 47% by mass sulfuric acid (H) was added to the slurry while stirring. ２ SO ４ 60.0 mL was added, and the pH was adjusted to 2 or less and the liquid temperature to 60°C. Next, while maintaining the liquid temperature at 60°C, 12% by mass sodium hypochlorite (NaClO) and 47% by mass sulfuric acid (H) were added. ２ SO ４The addition and stirring of sodium hypochlorite and sulfuric acid were repeated. During this process, the oxidation-reduction potential was measured after stirring, and a portion of the liquid was taken. The concentrations of lithium, nickel, cobalt, manganese, iron, and copper were measured using inductively coupled plasma optical emission spectroscopy (ICP-OES). The amount of each metal dissolved in the liquid was calculated from the volume of the liquid and the measured concentrations of each metal. Sodium hypochlorite and sulfuric acid were added until the amount of nickel dissolved in the liquid stopped changing, and a total of 44.0 mL of sodium hypochlorite was added in total. During this time, a total of 24 mL of sulfuric acid was added to adjust the pH between 2.2 and 2.6. The oxidation-reduction potential was measured using a portable ion / pH meter (Toa DKK Corporation, IM-32P model) and an ORP composite electrode (Toa DKK Corporation, PST-5721C).

[0091] Next, 30% by mass hydrogen peroxide (H ２ O ２ 2.0 mL of hydrogen peroxide (H) was added to adjust the pH to 2 or less and the temperature to 60°C. ２ O ２ The addition of ) is to prevent the highly oxidative acidic liquid from coming into contact with the components and test equipment in the process after leaching is complete. Next, solid-liquid separation was performed by vacuum filtration to separate the liquid component (leached liquid) from the solid component (cake). The amount of leached liquid obtained was 910 mL. The separated cake was washed with distilled water to obtain 295 mL of post-wash liquid. By drying the post-wash cake, 46.69 g of leaching residue was obtained.

[0092] The amounts of nickel, cobalt, and lithium in the obtained leachate, wash solution, and leachate residue were evaluated. The evaluation results are shown in Tables 16 to 18. The amounts of each element in the leachate and wash solution were measured using inductively coupled plasma optical emission spectroscopy (ICP-OES), and the amounts of each element in the leachate residue were measured using X-ray fluorescence spectroscopy (XRF). Furthermore, Figure 7 shows the relationship between treatment time and the amount of metal dissolved, the relationship between treatment time and oxidation-reduction potential (ORP), and the relationship between treatment time and the amount of reagent in the process of leaching nickel precipitate.

[0093]

[0094]

[0095]

[0096] In this example, the lithium leaching rate into the Li leaching solution of Example 2-2 was 95%, indicating that lithium could be sufficiently leached using sulfuric acid. Furthermore, as shown in Table 15, nickel and cobalt were not present in the Li leaching solution or the Li post-wash solution, confirming that nickel and cobalt had migrated to the post-wash cake (nickel precipitate).

[0097] Next, the leaching rates of nickel (Ni leaching rate) and cobalt (Co leaching rate) in the leaching solution were calculated using the above formula when the cake (nickel precipitate) after washing following lithium leaching was subjected to leaching treatment. In Example 2-2 of the present invention, which used sodium hypochlorite, the nickel leaching rate was 94% and the cobalt leaching rate was 94%.

[0098] Furthermore, in Example 2-2 of the present invention, as shown in Figure 7, it was confirmed that the amount of nickel and cobalt dissolved increased as the amount of sodium hypochlorite added increased. Also, as shown in Figure 7, the oxidation-reduction potential (ORP) increased with the increase in the amount of nickel dissolved, and it was confirmed that the oxidation-reduction potential (ORP) exceeded 1100 mV when the amount of nickel dissolved stopped changing. At this time, the state of oxidation-reduction potential (ORP) being 1100 mV or higher was maintained for more than 2 minutes. Thus, it was confirmed that the endpoint of nickel dissolution can be determined by the oxidation-reduction potential (ORP).

[0099] (Example 2-3 of the present invention) 80 g of the above-mentioned black mass was placed in a 1 L separable flask. Water (H) was added to it. ２ O) 400 mL and 47% by mass sulfuric acid (H ２ SO ４ ) 35.0 mL was added and the pH was adjusted to 2 or less. Next, calcium hydroxide (Ca(OH)) was added as a neutralizing agent. ２7.3 g was added to form a precipitate containing nickel and cobalt. Next, solid-liquid separation was performed by vacuum filtration to separate the liquid component (Li leachate) from the solid component (cake). The resulting Li leachate was 348 mL. The separated cake was washed with distilled water to obtain 770 mL of the post-wash solution (Li post-wash solution) and 130.91 g (wet) of the post-wash cake (corresponding to the nickel precipitate).

[0100] Here, the amounts of lithium, nickel, and cobalt in the obtained Li leachate, Li wash solution, and wash cake (nickel precipitate) were evaluated. The evaluation results are shown in Tables 19 to 21. The amounts of each element in the leachate and wash solution were measured using inductively coupled plasma optical emission spectroscopy (ICP-OES), and the amounts of each element in the leachate residue were measured using X-ray fluorescence spectroscopy (XRF).

[0101]

[0102]

[0103]

[0104] Next, add 125.70 g (wet) of the washed cake (nickel precipitate) to a 1 L separable flask, and add water (H ２ O) 800 mL was added and stirred. Next, 47% by mass sulfuric acid (H) was added to the slurry while stirring. ２ SO ４ 60.0 mL was added, and the pH was adjusted to 2 or less and the liquid temperature to 60°C. Next, while maintaining the liquid temperature at 60°C, 12% by mass sodium hypochlorite (NaClO) and 47% by mass sulfuric acid (H) were added. ２ SO ４The addition and stirring of the solution was repeated. After stirring, the oxidation-reduction potential was measured, and a portion of the solution was taken. The concentrations of lithium, nickel, cobalt, manganese, iron, and copper were measured by inductively coupled plasma optical emission spectroscopy (ICP-OES). The amount of each metal dissolved in the solution was calculated from the volume of the solution and the measured concentrations of each metal. Sodium hypochlorite and sulfuric acid were added until the amount of nickel dissolved in the solution no longer changed. Finally, a total of 44.0 mL of sodium hypochlorite and 20 mL of sulfuric acid were added. During this time, the pH was adjusted to between 2.5 and 3.0. The oxidation-reduction potential was measured using a portable ion / pH meter (Toa DKK Corporation, IM-32P model) and an ORP composite electrode (Toa DKK Corporation, PST-5721C).

[0105] Next, 30% by mass hydrogen peroxide (H ２ O ２ 2.0 mL of hydrogen peroxide (H) was added to adjust the pH to 2 or less and the temperature to 60°C. ２ O ２ The addition of ) is to prevent the highly oxidative acidic liquid from coming into contact with the components and test equipment in the process after leaching is complete. Next, solid-liquid separation was performed by vacuum filtration to separate the liquid component (leached liquid) from the solid component (cake). The amount of leached liquid obtained was 870 mL. The separated cake was washed with distilled water to obtain 479 mL of post-wash liquid. By drying the post-wash cake, 46.68 g of leaching residue was obtained.

[0106] The amounts of nickel, cobalt, and lithium in the obtained leachate, wash solution, and leachate residue were evaluated. The evaluation results are shown in Tables 22 to 24. The amounts of each element in the leachate and wash solution were measured using inductively coupled plasma optical emission spectroscopy (ICP-OES), and the amounts of each element in the leachate residue were measured using X-ray fluorescence spectroscopy (XRF). Furthermore, Figure 8 shows the relationship between treatment time and the amount of metal dissolved, the relationship between treatment time and oxidation-reduction potential (ORP), and the relationship between treatment time and the amount of reagent in the process of leaching nickel precipitate.

[0107]

[0108]

[0109]

[0110] In this example, the lithium leaching rate into the Li leaching solution in Example 2-3 of the present invention was 93%, indicating that lithium could be sufficiently leached using sulfuric acid. Furthermore, as shown in Table 21, nickel and cobalt were not present in the Li leaching solution or the Li post-wash solution, confirming that nickel and cobalt had migrated to the post-wash cake (nickel precipitate).

[0111] Next, the leaching rates of nickel (Ni leaching rate) and cobalt (Co leaching rate) in the leaching solution were calculated using the above formula when the cake (nickel precipitate) after washing following lithium leaching was subjected to leaching treatment. In Example 2-3 of the present invention, which used sodium hypochlorite, the nickel leaching rate was 85% and the cobalt leaching rate was 85%.

[0112] Furthermore, in Example 2-3 of the present invention, as shown in Figure 8, it was confirmed that the amount of nickel and cobalt dissolved increased as the amount of sodium hypochlorite added increased. Also, as shown in Figure 8, the oxidation-reduction potential (ORP) increased with the increase in the amount of nickel dissolved, and it was confirmed that the oxidation-reduction potential (ORP) exceeded 1100 mV when the amount of nickel dissolved stopped changing. At this time, the state of oxidation-reduction potential (ORP) being 1100 mV or higher was maintained for more than 2 minutes. Thus, it was confirmed that the endpoint of nickel dissolution can be determined by the oxidation-reduction potential (ORP).

[0113] From the results of Examples 2-1 to 2-3 of the present invention, nickel and cobalt can be recovered in high yield by setting the pH of sodium hypochlorite (NaClO) added as a solubilizing agent within the range of 1.7 to 2.6, and particularly within the range of 1.7 to 2.2.

[0114] (Example 3 of the present invention) Next, the experimental results of Example 3 of the present invention, in which potassium permanganate was used as a solubilizing agent, will be described.

[0115] In a 1 L separable flask, add 123.57 g of the washed cake (nickel precipitate) obtained in Example 2-1 of the present invention described above, and water (H ２ O) 800 mL was added and stirred. 47% sulfuric acid (H) was added to the slurry during stirring. ２ SO ４ 60.0 mL was added, and the pH was adjusted to 2 or less and the liquid temperature to 60°C. Next, while maintaining the liquid temperature at 60°C, potassium permanganate (KMnO) at a concentration of 60 g / L was added. ４ ) and 47% by mass sulfuric acid (H ２ SO ４ The addition and stirring of ) was repeated. During this process, after stirring, the oxidation-reduction potential was measured, and a portion of the liquid was taken. The concentrations of lithium, nickel, cobalt, manganese, iron, and copper were measured by inductively coupled plasma optical emission spectroscopy (ICP-OES), and the amount of each metal dissolved in the reaction solution was calculated from the volume of the reaction solution and the measured concentrations of each metal. Potassium permanganate was added until the amount of nickel dissolved in the liquid component no longer changed, and finally a total of 120.0 mL of potassium permanganate was added. During this time, 47% by mass sulfuric acid (H ２ SO ４ A total of 28.0 mL of the solution was added to adjust the pH to between 1.90 and 2.58. The oxidation-reduction potential was measured using a portable ion / pH meter (Toa DKK Corporation, IM-32P model) and an ORP composite electrode (Toa DKK Corporation, PST-5721C).

[0116] After the amount of nickel dissolved in the liquid component no longer changes and nickel leaching is complete, add 30% by mass hydrogen peroxide (H ２ O ２ 5.0 mL was added, and the pH was adjusted to 2 or less, and the liquid temperature to 60°C. Note that hydrogen peroxide (H ２ O ２ The addition of this substance is to prevent the highly oxidizing acidic liquid from coming into contact with the components or test equipment in the process after the leaching is complete.

[0117] Next, the liquid component (leachate) and solid component (cake) were separated by vacuum filtration. The resulting leachate was 963 mL. The separated cake was washed with distilled water to obtain 224 mL of the post-wash solution. The post-wash cake was dried to obtain 44.75 g of leachate residue.

[0118] Figure 9 shows the relationship between treatment time and the amount of various metals dissolved, the relationship between treatment time and oxidation-reduction potential (ORP), and the relationship between treatment time and the amount of reagent in the process of leaching nickel precipitate.

[0119] In Example 3 of the present invention, the leaching rate of nickel (Ni leaching rate) and cobalt (Co leaching rate) into the leaching solution when the cake (nickel precipitate) after washing and lithium leaching was subjected to leaching treatment was calculated using the above formula. In Example 3 of the present invention, in which potassium permanganate was used as a solubilizer, the nickel leaching rate was 97% and the cobalt leaching rate was 95%.

[0120] Furthermore, in Example 3 of the present invention, as shown in Figure 9, it is confirmed that the amount of nickel and cobalt dissolved increases as the amount of potassium permanganate added increases. Also, as shown in Figure 9, the oxidation-reduction potential (ORP) rises with increasing nickel dissolution, and it is confirmed that the endpoint of nickel dissolution can be determined by the oxidation-reduction potential (ORP).

[0121] Based on the experimental results described above, it has been confirmed that the present invention provides a method for producing a nickel leaching solution that can efficiently extract nickel from nickel-containing materials containing nickel(II) oxide.

[0122] According to the present invention, it is possible to provide a method for producing a nickel leaching solution that can efficiently leach nickel from a nickel-containing material containing nickel(II) oxide.

Claims

1. A method for producing a nickel leaching solution, comprising a nickel leaching step in which a treatment solution containing an inorganic acid is added to a nickel-containing material containing nickel(II) oxide, and nickel is leached into the treatment solution, wherein in the nickel leaching step, a solubilizer is added to dissolve the nickel(II) oxide in the treatment solution.

2. A method for producing a nickel leached solution, comprising: a lithium leaching step of adding a treatment solution containing an inorganic acid to a nickel-containing material containing nickel(II) oxide and lithium to leach lithium into the treatment solution; a neutralization step of adding a neutralizing agent to the treatment solution after the lithium leaching step to generate a nickel precipitate containing nickel; a nickel precipitate separation step of separating the nickel precipitate generated in the neutralization step to obtain a lithium leached solution; and a nickel leaching step of adding a treatment solution containing an inorganic acid to the nickel precipitate to leach nickel into the treatment solution, wherein in the nickel leaching step, a solubilizing agent is added to dissolve the nickel(II) oxide in the treatment solution.

3. The method for producing nickel leaching according to claim 1 or 2, characterized in that the nickel-containing material is a battery calcined product obtained by calcining crushed lithium-ion battery material.

4. A method for producing nickel leaching according to claim 1 or 2, characterized in that the solubilizer is a hypochlorite salt.

5. The method for producing a nickel leaching solution according to claim 4, characterized in that, in the nickel leaching step, the pH of the treatment solution is within the range of 1.7 to 2.

6.

6. The method for producing a nickel leaching solution according to claim 5, characterized in that, in the nickel leaching step, the nickel leaching is determined to be complete when the oxidation-reduction potential of the treatment solution is maintained at 1100 mV or higher for 2 minutes or more.

7. The method for producing a nickel leaching solution according to claim 1 or 2, characterized in that, in the nickel leaching step, after determining that the leaching of nickel is complete, hydrogen peroxide solution is added to the processing solution to bring the oxidation-reduction potential to a state of 500 mV or more and 700 mV or less.

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