KR20200046295A - Selective leaching method of trivalent cathode active material - Google Patents

Abstract

The present invention provides a method for recovering manganese (Mn) as a residue from a positive electrode active material of a waste lithium ion secondary battery containing cobalt (Co), nickel (Ni), lithium (Li), and manganese (Mn) and selectively leaching lithium (Li), nickel (Ni), and cobalt (Co). More particularly, according to the present invention, a selective removal method of manganese (Mn) uses Mn II dissolved in sulfuric acid solution as a reducing agent for cobalt (Co) and nickel (Ni), so that nickel (Ni) and cobalt (Co) are dissolved in a divalent state, and manganese (Mn) is left as a residue in the form of a tetravalent oxide.

Description

SELECTION LEACHING METHOD OF TRIVALENT CATHODE ACTIVE MATERIAL}

The present invention relates to a method for selectively leaching valuable metals from a ternary positive electrode active material of a waste lithium ion battery.

In recent years, as the demand for electric vehicle batteries increases, the production of Ni-Co-Mn (NCM) -based lithium ion batteries (LIBs, Lithium Ion Batteries) positive electrode active materials tends to increase. Among the metals in the positive electrode active material, the content of manganese (Mn) is relatively higher than that of expensive cobalt (Co) and nickel (Ni).

The ternary positive electrode active material used in a lithium ion battery that has reached the end of its life contains expensive valuable metals such as cobalt (Co) and nickel (Ni), and to remove or recover manganese (Mn) to recover these valuable metals Must be preceded. Therefore, various techniques for this are known.

As a method of recovering valuable metals from a ternary positive electrode active material, incinerating and crushing the discarded lithium ion battery, and then using a positive electrode active material after leaching with acid, alkali, or organic acid, and then extracting the solvent from the filtrate. There is a method of extracting and separating each metal.

For example, in Korean Patent Application Publication No. 10-2012-0108162 (Patent Document 1), excess acid and reducing agent in the positive electrode active material of a waste cell containing manganese (Mn), cobalt (Co) and nickel (Ni) Is added to dissolve all soluble substances including manganese (Mn), cobalt (Co) and nickel (Ni), and then selectively precipitates manganese (Mn) by adding Na ₂ S ₂ O ₈ as an oxidizing agent to the leachate. Extract and separate. In this method, the reduction and oxidation processes have to be sequentially performed, and since each process requires a reducing agent and an oxidizing agent, it is not only economical but also has low efficiency.

In Korean Patent Application Publication No. 10-2012-0021256 (Patent Document 2), a two-step leaching process was introduced to reduce the use of a reducing agent, and in step 1, after dissolving a soluble component in a sulfuric acid leaching condition without a reducing agent, the slurry It consists of a process of leaching undissolved components such as cobalt (Co), nickel (Ni), and manganese (Mn) by additionally introducing hydrogen peroxide as a reducing agent in two stages. This process can also increase the process cost because a solvent extraction process must be additionally introduced to separate and remove the manganese (Mn) leached together from the second-stage leachate, and the process is complicated because it has to go through several steps of leaching process. can do.

In the case of Chen et al., 2015 (Non-Patent Document 1), after leaching the NCM-based positive electrode active material using sulfuric acid and hydrogen peroxide water as a reducing agent, KMnO ₄ is used as an oxidizing agent to selectively separate manganese (Mn) in the filtrate. The process of selectively removing with MnO ₂ was studied.

In addition, Wang et al., 2017 (Non-Patent Document 2) describes a method for selectively recovering only cobalt (Co) and nickel (Ni) excluding manganese (Mn) under alkaline leaching, particularly ammonia conditions. In this study, there is an advantage that only nickel (Ni) and cobalt (Co) can be selectively recovered as a solution, except for manganese (Mn), which is recovered as an insoluble oxide. However, in the case of ammonia, the regulation of total phosphorus in the wastewater is applied, and an apparatus for recovering and recycling appropriately must be provided, and since the reagent cost is higher than that of inorganic acids, it is not preferable from an economical / environmental point of view.

In the case of the existing literature and patents, in order to recover cobalt (Co) and nickel (Ni) contained in the NCM-based positive electrode active material, all soluble substances including manganese (Mn) are dissolved and leached under conditions in which an acid and a reducing agent are added in excess. Manganese (Mn) is added to the thick solution again to selectively remove and remove manganese (Mn) by oxidizing or separating manganese (Mn) by a separate solvent extraction process. .

Domestic Patent Application Publication No. 10-2012-0108162 Domestic Patent Application Publication No. 10-2012-0021256

 Chen X. et al., 2015. “Separation and recovery of metal values from leaching liquor of mixed-type of spent lithium-ion batteries”, Separation and Purification Technology 144, pp. 197-205.  Wang et al., 2017. “Recovery of Lithium, Nickel, and Cobalt from Spent Lithium-Ion Battery Powders by Selective Ammonia Leaching and an Adsorption Separation System”, ACS Sustainable Chemistry & Engineering 5, pp. 11489-11495.

An object of the present invention is to provide a method of economically and efficiently recovering valuable metals in a positive electrode active material of a lithium ion battery by saving a reducing agent and simplifying the process by excluding a separate manganese (Mn) separation process.

In order to achieve the above object, the present invention, (a) preparing a positive electrode active material powder comprising a first metal and a second metal from a ternary positive electrode active material containing a first metal and a second metal of the lithium ion battery ; (b) by dissolving the positive electrode active material powder in an aqueous sulfuric acid solution, the first leach solution containing the first metal, dissolved in an ionic state by the aqueous sulfuric acid solution, and reducing the first metal again, is oxidized by itself. Obtaining a solution containing the insoluble residue of the second metal; And (c) recovering the insoluble residue from the solution into the filtered first leach solution. Here, the first metal includes cobalt (Co), nickel (Ni), and lithium (Li), and the second metal includes manganese (Mn). The present invention provides a method of selectively leaching a first metal such as cobalt (Co) and nickel (Ni), which are manganese (Mn) -removed valuable metals from a ternary positive electrode active material. According to the present invention, only nickel (Ni) and cobalt (Co) can be selectively dissolved without adding a large amount of reducing agent or adding an additional oxidizing agent.

In addition, in the leaching step (b) of the present invention, the reaction temperature is preferably 50-95 ℃. When the reaction temperature is less than 50 ℃, the reduction leaching reaction rate of nickel (Ni) and cobalt (Co) by manganese (II) is slow, so the leaching efficiency decreases. When the reaction temperature is higher than 95 ℃, the evaporation reaction of the aqueous solution under atmospheric pressure conditions actively causes leaching efficiency. Falls.

In addition, the concentration of the aqueous solution of sulfuric acid of the present invention is preferably a molar concentration of 3 to 4.5 times the molar concentration of nickel (Ni) + cobalt (Co) + manganese (Mn) in the solution. In the case of less than 3M, the leaching rate of cobalt (Co) and nickel (Ni) was significantly reduced, and when it exceeds 4M, the leaching rate may increase, but the pH of the leaching solution is too low to increase the amount of neutralizing agent.

In addition, in the leaching step (b) of the present invention, the ratio of the positive electrode active material powder and the aqueous sulfuric acid solution (solid solution ratio (mL / g)) is preferably 10 mL / g or more. When the solid-liquid ratio is less than 10 mL / g, the leaching rate of cobalt (Co) and nickel (Ni) is significantly reduced, and the viscosity of the leaching liquid is increased, thereby significantly slowing the filtration rate.

In addition, in the leaching step (b) of the present invention, when leaching the positive electrode active material powder in sulfuric acid, it is preferable to further add a reducing agent such as sulfuric acid. Accordingly, the amount of Mn (II) ions in the leachate increases compared to when leaching with sulfuric acid alone, and the increased Mn (II) ions act again as a reducing agent for nickel (Ni) and cobalt (Co), and cobalt (Co) and The leaching rate of nickel (Ni) increases.

In addition, in the leaching step (b) of the present invention, the amount of the reducing agent added is 0.4 compared to the equivalent of the reducing agent required to reduce (cobalt (Co) + nickel (Ni) + manganese (Mn)) contained in the positive electrode active material powder sample. It is preferable to add in the ratio of -0.7. When the amount of the reducing agent is excessive (more than 0.7 equivalents), manganese (Mn) does not act as a reducing agent and there is a problem that a large amount of manganese (Mn) is leached, and in the case of a small amount (less than 0.4 compared to the equivalent), the effect is insufficient. Do.

In addition, in the leaching step (b), the reducing agent is hydrogen peroxide, SO ₂ , Na ₂ S ₂ O ₅ , NaHSO ₃ , Na ₂ SO ₃ , KHSO ₃ , K ₂ SO ₃ , FeSO ₄ , H ₂ S, glucose , It is preferable to select at least one from the group consisting of citric acid and malic acid.

In addition, the reaction time in the leaching step (b) is preferably 240-480 minutes. When the reaction time is less than 240 minutes, the reduction leaching efficiency of cobalt (Co) and nickel (Ni) by manganese (II) is low, and when it is more than 480 minutes, the increase in leaching rate is negligible, which is 240-480 minutes. It is assumed.

In addition, the ternary positive electrode active material powder of step (a) is physically separated from the ternary positive electrode active material (Li (Ni _x Co _y Mn _z ) O ₂ ) (x + y + z = 1) of the waste battery. It is preferable to remove the battery case, separator, anode (Al), cathode (Cu) and the like.

In addition, adding the positive electrode active material powder to the solution obtained in step (b) to adjust the pH and remove impurities such as Al, Fe; Filtering the neutralized solution to recover a second leachate containing insoluble residues and valuable metals; And it is preferable to further include the step of finally recovering lithium (Li), cobalt (Co) and nickel (Ni) from the second leachate through solvent extraction or precipitation.

Further, with respect to the residue recovered in step (c), the concentration of sulfuric acid aqueous solution 3-4M H ₂ SO ₄ , the ratio of the recovered residue and the aqueous sulfuric acid solution (solid solution ratio (mL / g)) 5 mL / g or more, reaction Re-leaching the residue under the conditions of time 6-8 hours; And it is preferable to further include the step of recovering the insoluble residue and the third leachate by filtering again after re-leaching the residue. Through re-leaching of the residue, recovery of cobalt (Co) and nickel (Ni) that has escaped into the residue is possible.

According to the present invention, in recovering valuable metals from a ternary positive electrode active material (Li (Ni _x Co _y Mn _z ) O ₂ ) (x + y + z = 1) of a lithium ion battery, a reducing agent is significantly saved while Since the oxidation process can be omitted, it is possible to improve economic efficiency and efficiency.

1 is a schematic diagram of a method for leaching a ternary positive electrode active material of the present invention.
2 is a schematic diagram of adding a neutralizing step to the leaching method of the present invention.
Figure 3 is a graph of the results of XRD analysis of the recovered residue prepared according to the leaching method of the present invention.

Hereinafter, the configuration and operation of the embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description of the present invention, for convenience of description, parts not directly related to the present invention are omitted, and even when it is determined that a detailed description of related known functions or configurations may unnecessarily obscure the subject matter of the present invention. Detailed description is omitted. In addition, the following examples are examples for explaining the present invention, and the scope of the present invention is not limited by the exemplary embodiments.

The positive electrode active material to be leached according to the present invention is a material constituting the positive electrode of a lithium ion battery, and a ternary positive electrode active material obtained by synthesizing various elements is used. There are NCM, NCA, LMO and LFP depending on the type of element, and these examples were tested with NCM-based cathode materials composed of the most representative nickel (Ni), cobalt (Co) and manganese (Mn).

The inventor of the present invention excludes manganese (Mn) from the NCM ternary positive electrode active material (Li (Ni _x Co _y Mn _z ) O ₂ ) (x + y + z = 1) of a lithium ion battery, and is a valuable metal cobalt (Co ) And nickel (Ni) was recovered using sulfuric acid at a high recovery rate, and at the same time, a method of reducing the amount of reducing agent required for the existing process and removing the oxidizing agent addition process to significantly reduce the cost of recovering valuable metals was invented. .

The recovery process of the valuable metal from the ternary positive electrode active material according to the present invention, as shown in Figure 1, (a) lithium (Li), cobalt (Co) and nickel (Ni), manganese (Mn), iron ( Fe), preparing a positive electrode active material powder from a lithium ion battery containing a metal such as aluminum (Al); (b) dissolving the ternary positive electrode active material powder with an aqueous sulfuric acid solution to obtain a solution containing the first leach solution containing cobalt (Co) and nickel (Ni) and an insoluble residue of manganese (Mn) oxide; And (c) recovering the first leachate from which the insoluble residue is filtered from the solution.

The ternary positive electrode active material powder of step (a) is a battery by physical separation process from the ternary positive electrode active material (Li (Ni _x Co _y Mn _z ) O ₂ ) (x + y + z = 1) of the waste battery. It is preferable to remove the case, separator, anode (Al), cathode (Cu), and the like.

Since the positive electrode active material contains a component that can be leached by sulfuric acid, first, an aqueous solution of sulfuric acid is added to these components to leach to make a leaching solution. Manganese (Mn) ions leached in the leaching solution act as a reducing agent (reduction leaching with manganese (Mn)), whereby the desired product can be obtained without the addition of a reducing agent.

In the present invention, the possible leaching reaction in step (b) is as follows.

(Sulfuric acid leaching)

4LiMeO ₂ + 6H ₂ SO ₄ = 2Li ₂ SO ₄ + 4MeSO ₄ + 6H ₂ O + O ₂ (g) (Me = Co, Ni, Mn)

(Reduction leaching with manganese (Mn))

MnSO ₄ + Co ₂ O ₃ + 4H ⁺ = 2CoSO ₄ + 1 / 2MnO ₂ + 2H ₂ O

MnSO ₄ + Ni ₂ O ₃ + 4H ⁺ = 2NiSO ₄ + 1 / 2MnO ₂ + 2H ₂ O

As can be seen from the above equations, Mn (II) ions generated during the sulfuric acid leaching process act as a reducing agent for Co (III) and Ni (III) present in the positive electrode active material again, and manganese (Mn) is a tetravalent It becomes an oxide form and serves to dissolve Co (II) and Ni (II) in a divalent state. In this way, valuable metals other than manganese (Mn) can be reduced and leached without a reducing agent.

[Example]

[Table 1] shows an example of raw material composition (wt.%) Of the NCM positive electrode active material used in the experiment.

[Example 1: leaching with sulfuric acid]

This embodiment compares the leaching rate of each metal according to changes in the concentration of sulfuric acid, high liquid ratio (mineral liquid concentration), and reaction time at the same reaction temperature when the leaching process is performed using only sulfuric acid without a reducing agent.

From the positive electrode active material having the composition of [Table 1], each condition was changed as shown in [Table 2] to perform leaching. As can be seen from the results of Table 2, the concentration of manganese (Mn) in the leachate according to the present invention was 2.0 g / L or less, which was significantly lower than that of cobalt (Co) and nickel (Ni). In addition, the concentrations of cobalt (Co) and nickel (Ni) in sulfuric acid concentration 3M, reaction time 8hr, and high liquid ratio 10 conditions (No.6) were 10.2g / L and 29.5g / L, respectively, and the leaching rate was 96%, respectively. And 99%. At this time, the leaching rate of manganese (Mn) was 10%.

It can be seen that without using a reducing agent, only manganese (Mn) can be efficiently removed / separated from the leachate.

[Example 2: Leaching according to change in reaction time]

[Table 2] No. 1 to 4 showed the leaching behavior of cobalt (Co), nickel (Ni), and manganese (Mn) according to the reaction time under conditions of sulfuric acid concentration 4M and reaction temperature 80 ° C.

When the reaction time is short within 1 hour, the leaching rate of manganese (Mn) also tends to increase. When the reaction time was 2 hours (No. 2), the concentrations of cobalt (Co) and nickel (Ni) were 6.3 g / L and 28.6 g / L, and the leaching rates were 59.4 and 96%, respectively. The concentration was 1.6 g / L and the leaching rate was 13.6%. In addition, nickel (Ni) can be recovered with a leaching efficiency of 96% within 2 hours of the reaction time, but cobalt (Co) shows a leaching rate of 90% or more at a minimum reaction time of 4 hours or more (No. 3). ) And at least 4 hours of reaction time is required for simultaneous extraction of nickel (Ni). In addition, the leaching rate of manganese (Mn) also tends to decrease continuously as the reaction time increases from 1 hour (No. 1) to 4 hours (No. 4), resulting in low leaching of manganese (Mn) and cobalt (Co). It can be seen that in order to improve the leaching rate of nickel (Ni), a minimum reaction time of 4 hours or more is required.

[Example 3: Leaching according to the change in the concentration of aqueous sulfuric acid solution]

In order to leach all the cobalt (Co), nickel (Ni), and manganese (Mn) presented in Table 1, an acid of about 0.9 mol is theoretically required. The 1.5M sulfuric acid concentration shown in Table 3 was 70% of the maximum cobalt (Co) leaching rate when about 1.7 times the acid concentration compared to the theoretically consumed acid concentration was added, and 3M of Table 2 (about 3.3 times). And 4M (approximately 4.5 times) at 80 ° C., respectively, exhibiting 93% and 96% cobalt (Co) leaching rates under 6 and 8 hours respectively. Therefore, considering the minimum acid concentration of 1.5M (1.7 times the theoretical requirement), the reaction rate (8 hr or less) and the leaching rate (more than 90%), 3M or more (3.3 times the theoretical requirement), 4M or less (4.5 times) It is preferable to proceed to H ₂ SO ₄ molar concentration. When it is increased to 4M or more, the leaching rate may be partially improved (94 ~ 96%), but it is not desirable because the pH of the leaching solution is too low (pH <0), increasing the cost of the neutralizing agent consumed to neutralize. .

[Example 4: Leaching according to the change in the high liquid ratio]

In the case of a change in the liquid-liquid ratio, the leaching rate of cobalt (Co) and nickel (Ni) at a high liquid-liquid ratio 10 (No. 6) of [Table 2] below was 96% and 99%, respectively, and the high liquid-liquid ratio was 5 As (No. 7) increases the concentration of the liquid solution, the cobalt (Co) and nickel (Ni) leaching rates tend to decrease significantly to 53% and 50%, so the high liquid-liquid ratio (light-liquid concentration) is preferably 10 or more. Do. On the other hand, when the sulfuric acid concentration was increased to 6M (No. 5) under the high liquid-liquid ratio 5, the leaching rate of cobalt (Co) and nickel (Ni) was high at 93% and 99%, respectively, but the viscosity of the leaching solution increased to increase the filtration rate. It is judged to be significantly slower, which is not desirable in operation.

[Example 5: Leaching according to reaction temperature change]

In this embodiment, the difference in leaching rate of each metal can be seen according to a change in reaction temperature.

Sulfuric acid concentration, solid-liquid ratio, and reaction time were examined for the leaching behavior of cobalt (Co), nickel (Ni), and manganese (Mn) while changing the reaction temperature from 25 to 80 ° C under fixed conditions. As shown in Table 3 below, when the reaction temperature is 25 ° C, the concentrations of cobalt (Co), nickel (Ni), and manganese (Mn) are leached at 4.7 g / L, 13.3 g / L, and 4.5 g / L. The rate was 40-42%, and leaching proceeded at a similar rate for each metal. On the other hand, the concentration in the leachate of manganese (Mn) is markedly reduced from the reaction temperature of 50 ° C, and in the case of 50 ° C and 80 ° C, the concentration of manganese (Mn) in the leachate was 0.08 g / L and 0.18 g / L. The rate was 0.7% and 1.5%, respectively, which was significantly reduced compared to 25 ° C.

From this, as the reaction temperature increases, the removal efficiency in the solution of manganese (Mn) increases, and at the same time, the leaching reaction of cobalt (Co) and nickel (Ni) becomes active, so the reaction temperature is 25 ° C. or higher, preferably 50 ° C. or higher. It is preferable to perform under conditions of 95 ° C. or lower, which is below the boiling point.

[Example 6: Sulfuric acid + hydrogen peroxide leaching]

This example is for changing the leaching rate of manganese (Mn), nickel (Ni), and cobalt (Co) by leaching by adding a reducing agent to sulfuric acid. In this embodiment, the reducing agent used is hydrogen peroxide, which is a representative reducing agent, but the reducing agent is not only hydrogen peroxide, but also SO ₂ , Na ₂ S ₂ O ₅ , NaHSO ₃ , Na ₂ SO ₃ , KHSO ₃ , K ₂ SO ₃ , FeSO ₄ , H ₂ S, at least one selected from the group consisting of glucose (glucose), citric acid (citric acid) and malic acid (malic acid) is irrelevant.

The same raw material as the sulfuric acid leaching As a result of examining the leaching behavior by adding hydrogen peroxide water as a reducing agent in the sulfuric acid conditions for the above [Table 1], as shown in [Table 4], hydrogen peroxide was added in excess (No. 1) Under conditions, cobalt (Co), nickel (Ni), and manganese (Mn) were simultaneously leached with a leaching rate of 99% or more, and the amount of reducing agent added was reduced to 50%, similar to the results presented in the existing patents or documents. The concentration of manganese (Mn) in the leaching solution (No. 2) was markedly reduced to 0.59 g / L and 3.2% leaching rate. At this time, the leaching rates of cobalt (Co) and nickel (Ni) were 93% and 97%, respectively. It was.

In the case of adding a reducing agent, it can be seen that the leaching rate of manganese (Mn) is significantly reduced, and the leaching rate of nickel (Ni) and cobalt (Co) is increased, compared to when only sulfuric acid is used. In addition, when an excessive amount of a reducing agent is added, manganese (Mn) is also reduced and leached, whereas when only an appropriate amount of a reducing agent is added, the leached Mn (II) is added again to cobalt (Co) and nickel (Ni). It can be seen that it acts as a reducing agent for separating itself into residues in the form of oxides.

[Example 7: Sulfuric acid + Na ₂ S ₂ O ₅ leaching (equivalent ratio change)]

This example was conducted to find out the effect of the leaching rate according to the change in the reaction time and equivalent ratio using another reducing agent Na ₂ S ₂ O ₅ .

The leaching behavior of metals according to the effect of the equivalent ratio of the reducing agent Na ₂ S ₂ O ₅ and the reaction time under conditions of sulfuric acid concentration 2M and reaction temperature 80 ° C. was investigated for the same raw material as the sulfuric acid leaching (Table 1 above). In Table 5, when the equivalent ratio of Na ₂ S ₂ O ₅ to the molar ratio of (Co + Ni + Mn) in the raw material is 1, the concentration of manganese (Mn) in the leachate is 28.3 g / L, resulting in a 94% leaching rate. In addition, the leaching rates of cobalt (Co) and nickel (Ni) were similar to 96% and 95%, respectively. On the other hand, when the Na ₂ S ₂ O ₅ equivalent ratio was reduced to 0.5 and the reaction time was increased to 6 hours, the leaching concentration of manganese (Mn) decreased significantly from 5.9 g / L to 0.6 g / L, and nickel (Ni) and cobalt ( The leaching rate of Co) tended to increase significantly.

From this, it is a reaction in which the leaching rate of cobalt (Co) and nickel (Ni) by manganese (II) is very slow. When the reaction proceeds for 6 hours or more, a significant difference in the leaching rate can be seen. In addition, when compared with the sulfuric acid leaching condition without the addition of a reducing agent ([Table 2]), in the 3M condition of sulfuric acid leaching, the leaching rate was significantly reduced to around 50% when the mineral liquid concentration was increased to a high liquid ratio of 5, while at the same sulfuric acid concentration. When the reducing agent was added, the reaction time could be shortened from 8 hours to 6 hours, and the leaching rate of cobalt (Co) and nickel (Ni) was maintained at 98% or more even at a high liquid-liquid ratio of 5, and the filtration rate was high. From this, compared with the sulfuric acid alone leaching reaction, sulfuric acid and reducing agent input reaction can be seen to have an effect of reducing the process cost by reducing the reactor and improving the leaching rate with a relatively high liquid-liquid ratio.

[Example 8: Analysis of leaching residues and releaching of residues]

The following [Table 6] is the result of analyzing the components of the residue separated after leaching under three conditions: sulfuric acid, sulfuric acid-sodium bisulfite (Na ₂ S ₂ O ₅ ), sulfuric acid-hydrogen peroxide (H ₂ O ₂ ), [Table 7] is a table analyzing the leaching rate (%) of each metal according to the residue re-leaching conditions.

Manganese (Mn) in the residue was present in concentrations of 3 times or more from about 10% to about 30% in the initial stage, and some undissolved cobalt (Co) and nickel (Ni) coexisted in about 3%. In order to recover cobalt (Co) and nickel (Ni) undissolved from the residue, cobalt (Co) and nickel ( The leaching behavior of Ni) and manganese (Mn) was investigated. 3-4M H ₂ SO ₄ , solid-liquid ratio 5 mL / g or more, and the result of re-analysis of the residue after reacting for 6-8 hours at a reaction temperature of 80 ° C (residual re-leaching, [Table 6]), manganese (Mn ), The quality was improved to 46% or more, and cobalt (Co) and nickel (Ni) were analyzed to be less than 1% in the residue, indicating a significant difference compared to other conditions.

The final leaching rate (sulfuric acid leaching + residue re-leaching) after re-leaching of the residue at 8 hours under conditions of optimal conditions of 4M H ₂ SO ₄ , high liquid ratio 5, and reaction temperature of 80 ° C is 99.3% of cobalt (Co) and manganese (Mn). It was 10.4% and nickel (Ni) 99.9%, and the leaching solution was reusable as an NCM positive electrode active material leaching solution.

The residue obtained through re-leaching of the residue was subjected to XRD analysis after drying. 3 is an XRD analysis result of the residue. As can be seen in the graph, the chemical crystalline form of the residue is manganese (Mn) oxide, H _{1. 78} Na _{0 . 22 In the} form of Mn ₈ O ₁₆ 2.4H ₂ O, Mn (III) and Mn (IV) mixed crystals existed in low oxide form, and cobalt (Co) and nickel (Ni) peaks were not observed.

[Example 9: Neutralizing the leach solution]

The following [Table 8] is a table analyzing the composition after the neutralization process by adding a positive electrode active material to the solution after leaching of the positive electrode active material.

After the sulfuric acid leaching of the NCM positive electrode active material, the pH of the filtrate is from 0.7 to 0.8, and an additional neutralizing agent is needed to neutralize the pH of the filtrate when a solvent extraction or precipitation method is applied through the separation and purification process of cobalt (Co) and nickel (Ni). . Instead of using alkali neutralizing agents such as NaOH, CaO, and CaCO ₃ to reduce the use of neutralizing agents and remove impurities such as Al, Fe, NCM positive electrode active material is additionally added to raise the pH to 4 or higher and filter it to remove the second leachate. The process of recovering was added to proceed. [Table 8] shows the results of the composition of the first leachate and the composition change of the second leachate recovered after additional injection of NCM samples. After addition of NCM, the pH increased from 0.8 to 4 after the reaction at a solid-liquid ratio of 5, reaction temperature of 80 ° C, and reaction time of 2hr. In addition, it can be seen that, in addition to the additional leaching effect of lithium (Li), cobalt (Co), and nickel (Ni) excluding manganese (Mn), it is very effective in reducing the amount of neutralizing agent for subsequent processes and removing impurities such as Fe and Al.

From the second leach obtained through filtration, cobalt (Co) and nickel (Ni) are finally separated and recovered through solvent extraction or precipitation using an organic solvent. After separation and recovery of cobalt (Co) and nickel (Ni), lithium (Li) remaining in the filtrate can be recovered in the form of Li ₂ CO ₃ or Li ₃ PO ₄ by precipitation.

Claims (10)

In the selective leaching method of the ternary positive electrode active material,
(A) preparing a positive electrode active material powder comprising a first metal and a second metal;
(b) dissolving the positive electrode active material powder in an aqueous sulfuric acid solution to dissolve an insoluble residue of the first leach solution containing the first metal and the second metal produced by the aqueous solution of sulfuric acid and reducing the first metal. Obtaining a solution comprising; And
(c) recovering the first leachate by filtering the insoluble residue from the solution
Selective leaching method of ternary positive electrode active material containing According to claim 1,
The first metal is lithium (Li), nickel (Ni) and cobalt (Co), the second metal is manganese (Mn), characterized in that the selective leaching method of the ternary positive electrode active material According to claim 1,
In step (b), the reaction temperature is 50-95 ° C, and the method of selectively leaching a ternary positive electrode active material is characterized in that According to claim 2,
The concentration of the aqueous sulfuric acid solution is a method of selectively leaching a ternary positive electrode active material, characterized in that the molar concentration of 3 to 4.5 times the molar concentration of nickel (Ni) + cobalt (Co) + manganese (Mn) in the solution. According to claim 1,
In the step (b), the ratio of the positive electrode active material powder and the aqueous sulfuric acid solution is 10 mL / g or more, characterized in that the selective leaching method of the ternary positive electrode active material According to claim 1,
The aqueous sulfuric acid solution contains a reducing agent,
The amount of the reducing agent added is a ternary positive electrode characterized in that it is added at a ratio of 0.4-0.7 compared to the equivalent of the reducing agent required to reduce all of the cobalt (Co), nickel (Ni) and manganese (Mn) contained in the positive electrode active material powder. Method of selective leaching of active substances The method of claim 6,
The reducing agent is hydrogen peroxide, SO ₂ , Na ₂ S ₂ O ₅ , NaHSO ₃ , Na ₂ SO ₃ , KHSO ₃ , K ₂ SO ₃ , FeSO ₄ , H ₂ S, glucose, citric acid and malic acid Selective leaching method of a ternary positive electrode active material, characterized in that at least one is selected from the group consisting of (malic acid) According to claim 1,
In step (b), the reaction time is 240-480 minutes, characterized in that the selective leaching method of the ternary positive electrode active material According to claim 1,
Adjusting the pH and removing impurities by adding the positive electrode active material powder to the solution obtained in step (b);
Filtering the neutralized solution to recover a second leachate containing insoluble residues and valuable metals; And
Separating and recovering lithium (Li), cobalt (Co), and nickel (Ni) from the second leachate
Selective leaching method of a ternary positive electrode active material characterized in that it further comprises According to claim 1,
Regarding the residue recovered in step (c), the concentration of sulfuric acid aqueous solution 3-4M H ₂ SO ₄ , the ratio of the recovered residue and the aqueous sulfuric acid solution is 5 mL / g or more, and the residue is re-leached under conditions of reaction time of 6-8 hours. Proceeding; And
After re-leaching the residue, filtering again to recover the insoluble residue and the third leachate
Selective leaching method of a ternary positive electrode active material characterized in that it further comprises

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