Organic phosphoric acid extractant capable of selectively recovering manganese from metal mixture and manganese recovery method using same

Abstract

The present invention relates to: an organic phosphoric acid extractant capable of selectively separating and recovering manganese (Mn) from a metal mixture derived from waste secondary batteries; and a method for selectively separating and recovering manganese (Mn) using the organic phosphoric acid extractant. The present invention uses an organic phosphoric acid extractant including organic phosphoric acids of di-octylphosphate (DOPOA) and / or di-decylphosphate (DDPOA), and thus has the advantage of being able to effectively separate and recover manganese from black mass which is a mixture of metals, such as lithium, manganese, cobalt, and nickel, generated from waste secondary batteries.

Description

An organic phosphorus extractant capable of selectively recovering manganese from a metal mixture and a method for recovering manganese using the same

[0001] The present invention relates to an organic phosphorus extractant capable of selectively separating and recovering manganese (Mn) from a metal mixture derived from a waste secondary battery, and a method for selectively separating and recovering manganese (Mn) using such an organic phosphorus extractant. The present invention provides a method for effectively separating and recovering manganese from black mass, which is a metal mixture of lithium, manganese, cobalt, nickel, etc. generated from a waste secondary battery, using an organic phosphorus extractant containing a novel organic phosphorus acid, and an organic phosphorus extractant composition used in the method.

[0002] [Project ID] 20240301

[0003] [Subject Number] 202306

[0004] [Ministry Name] Jeonbuk Special Self-Governing Province

[0005] [Research Management Specialist Organization] Jeonbuk Technopark

[0006] [Research Project Name] Jeonbuk Special Self-Governing Province Secondary Battery Capacity Building Support Project

[0007] [Research Project Title] Development and Commercialization of Mn Extraction Agents for Recycling Cathode Materials from Electric Vehicle Secondary Batteries

[0008] [Organizer] Cosolus Co., Ltd.

[0009] [Research Period] March 1, 2024 - February 28, 2025

[0010] The development of the information and communication industry has led to an increase in the use of various information and communication devices, such as mobile phones, tablet PCs, and digital cameras. Furthermore, to combat global warming caused by greenhouse gases, the use of internal combustion engine vehicles, a major contributor to greenhouse gas emissions, is being curbed, and the production and demand for eco-friendly vehicles, such as electric and hydrogen vehicles, which do not emit greenhouse gases, are increasing. Demand for secondary batteries, particularly lithium-ion secondary batteries, used as power sources for these information and communication devices, portable electronic devices, and eco-friendly electric vehicles, is exploding, and extensive research is being conducted to improve their performance and operating life.

[0011] Meanwhile, the explosive growth in demand for lithium-ion secondary batteries and the shortening life cycles of digital appliances have led to a sharp increase in the amount of waste secondary batteries, particularly lithium-ion secondary batteries. This has fueled growing interest in their processing and recycling. Defective waste battery scrap generated during the lithium-ion secondary battery manufacturing process and used lithium-ion secondary battery scrap contain significant amounts of valuable metals such as nickel, cobalt, and manganese, necessitating the development of technologies to recover and recycle these valuable resources.

[0012] Especially considering the rapidly growing global electric vehicle market, the scale of scrap secondary batteries is expected to increase over time. Therefore, in the case of scrap secondary batteries discharged from electric vehicles, recycling (re-cycle) is attracting attention, which processes scrap batteries back into resources and uses them as raw materials for manufacturing new batteries, rather than reusing them. Black mass is a powder obtained by preprocessing scrap electric vehicle batteries. It is a powdery material containing various byproducts such as Mn, Co, Ni, and Li that can be recycled as raw materials for using new batteries.

[0013] Meanwhile, in relation to the recycling of these waste batteries, it has been reported that the cathode material, which accounts for more than 40% of the cost of lithium-ion secondary batteries, has better battery performance when recovered by recycling waste cathode materials than when pure materials are used. It is expected that in the future, the recycling technology of waste secondary batteries will emerge as an important alternative that can solve the problems of environmental protection and resource depletion.

[0014] Regarding recycling technology for spent batteries, Korean Patent No. 2008582 proposes a method for manufacturing and supplying a ternary (nickel, cobalt, manganese) complex sulfate solution that simultaneously recycles nickel, cobalt, and manganese without separating them. This method reduces process costs and contributes to lower costs for precursor manufacturers. However, this recovery method still produces a mixture of nickel, cobalt, and manganese, making it difficult to effectively recover each individual component.

[0015] The present invention is intended to solve the problems of the prior art, and to provide a solvent extraction method for separating manganese (Mn) with high purity from a cathode active material of a lithium-ion secondary battery, and a highly efficient organic phosphorus extractant that can be used in this process. More specifically, the present invention is intended to efficiently separate and extract manganese (Mn) from an aqueous metal mixture solution containing manganese (Mn), cobalt (Co), and nickel (Ni) in an organic solvent phase by mixing a new type of organic phosphorus, which has not been used as a conventional solvent extractant, with an organic solvent to prepare an organic phosphorus extractant, and then using a solvent extraction method that uses the organic phosphorus extractant as an organic phase.

[0016] A method for selectively extracting manganese (Mn) from a metal mixture containing manganese, cobalt, nickel, and lithium according to one embodiment of the present invention comprises: an aqueous phase preparation step (S100) of dissolving the metal mixture in an acid aqueous solution to prepare an aqueous phase; an organic phase preparation step (S200) of mixing an organic phosphoric acid and an organic solvent to prepare an organic phosphoric acid extractant; a first separation step (S300) of mixing the aqueous phase and the organic phase in equal volumes, stirring, and allowing to stand to separate phases; a pH control step (S400) of adding an alkaline substance to the aqueous phase separated in the first separation step to adjust pH; and a second separation step (S500) of adding distilled water to the pH-adjusted aqueous phase, adding the organic solvent to the organic phase separated in the first separation step to make the volumes of the aqueous phase and the organic phase equal, and then mixing, stirring, allowing to stand to separate phases.

[0017] The above acid solution is preferably 0.5 to 2.5 M sulfuric acid, the organic solvent is preferably kerosene, and the organic phosphoric acid is preferably dioctylphosphate (DOPOA) and / or didecylphosphate (DDPOA).

[0018] In addition, it is preferable that the alkaline substance is a sodium hydroxide aqueous solution, and it is more preferable that the pH is controlled in the range of 1 to 5 in the pH control step (S400).

[0019] In another embodiment of the present invention, there is provided an extractant capable of selectively extracting manganese from a metal mixture comprising manganese, cobalt, nickel, and lithium, wherein the extractant is an organic phase in which a kerosene solvent and an organic phosphoric acid are mixed, and the organic phosphoric acid is dioctylphosphate (DOPOA) and / or didecylphosphate (DDPOA), and when an aqueous phase, which is an acidic metal mixture aqueous solution of manganese, cobalt, nickel, and lithium, is mixed with the organic phase, the extractant is characterized in that manganese in the aqueous phase is selectively extracted into the organic phase at a pH in the range of 1 to 5.

[0020] The organic phosphorus extractant according to the present invention is formed by mixing organic phosphoric acids such as Di-octylphosphate (DOPOA) and / or Di-decylphosphate (DDPOA) with kerosene, an organic solvent, at a specific concentration, and can separate and extract manganese (Mn) with high purity in an acidic region from an aqueous metal mixture solution containing manganese (Mn), cobalt (Co), nickel (Ni), and lithium (Li). By effectively recovering high-purity manganese (Mn) using such an organic phosphorus extractant, there is an advantage in that metal resources can be efficiently recycled.

[0021] In addition, through the selective extraction method according to the present invention, in the process of recycling waste lithium secondary battery cathode materials, high-purity manganese is selectively recovered from an acidic aqueous solution of a metal mixture of nickel-cobalt-manganese-lithium, thereby enabling efficient use of limited mineral resources and having the effect of protecting the environment.

[0022] The effects according to the present invention include, in addition to the effects explicitly described above, effects that can be clearly recognized by a person skilled in the art from the description of this specification.

[0023] Figure 1 shows the extraction performance (Recovery, %) of each metal according to pH change when using the existing extractant, Di-(2-ethylhexyl)phosphoric acid (D2EHPA).

[0024] Figure 2 shows the extraction performance (Recovery, %) of each metal according to pH change when using dioctylphosphate (DOPOA), an extractant according to the present invention.

[0025] Figure 3 shows the extraction performance (Recovery, %) of each metal according to pH change when didecylphosphate (DDPOA), an extractant according to the present invention, was used.

[0026] Figure 4 shows the results of measuring the extraction performance of manganese according to the type of extractant and the pH value.

[0027] Before describing in detail the preferred embodiments of the present invention below, it should be noted that the terms and words used in this specification and claims should not be interpreted as limited to their usual or dictionary meanings, but should be interpreted as meanings and concepts that are consistent with the technical spirit of the present invention.

[0028] Throughout this specification, whenever a part is said to “include” a component, this does not mean that it excludes other components, but rather that it may include other components, unless otherwise stated.

[0029] Throughout this specification, “%” used to indicate the concentration of a specific substance means (weight / weight)% for solid / solid, (weight / volume)% for solid / liquid, and (volume / volume)% for liquid / liquid, unless otherwise stated.

[0030] The identifiers used in each step are for convenience of explanation and do not indicate the order of the steps. The steps may be performed in a different order than stated, unless the context clearly dictates otherwise. In other words, the steps may be performed in the same order as stated, substantially simultaneously, or in the opposite order.

[0031] Hereinafter, embodiments of the present invention will be described in detail. However, the scope of the present invention is not limited to the following preferred embodiments. Anyone skilled in the art to which the present invention pertains can implement the present invention in various modified forms based on the contents described herein without adding any special technical configurations, based on what is already known in the art, within the scope of the present invention.

[0032] In the present invention, by using an organic phosphorus extractant containing an organic phosphorus acid, manganese (Mn) can be separated and extracted with high purity from a metal mixture aqueous solution containing manganese (Mn), cobalt (Co), nickel (Ni), and lithium (Li).

[0033] The organic phosphorus acid included in the organic phosphorus extractant used at this time may be dioctylphosphate (hereinafter referred to as 'DOPOA') or didecylphosphate (hereinafter referred to as 'DDPOA').

[0034] In order to verify the extraction performance of the organic phosphorus extractant according to the present invention, and to compare it with the case where the organic phosphorus or alkylamine is used alone, extraction experiments were performed from a metal mixture for each metal element such as manganese, cobalt, and nickel. The metal concentrations in the aqueous solution layer before and after solvent extraction were measured using ICP-OES, and the extraction performance was calculated using the following equation (1).

[0035] (Formula 1)

[0036] Below, the process of selectively extracting and recovering manganese (Mn) from a metal mixture containing manganese is described in more detail.

[0037] First, a metal mixture containing manganese is dissolved in a 0.5 to 2.5 M sulfuric acid aqueous solution to prepare an aqueous solution (S100), and an organic phase is prepared by dissolving each of the organic phosphoric acids of chemical formula 1 and chemical formula 2 or a mixture thereof in kerosene, an organic solvent (S200).

[0038] At this time, the metal mixture may include manganese, cobalt, nickel, and lithium, which are substances contained in waste lithium-ion secondary batteries.

[0039] Optionally, 33.5 wt% of hydrogen peroxide (H2O2) may be added to the sulfuric acid aqueous solution in a range of 4 to 7 vol% during the aqueous solution manufacturing process. The addition of hydrogen peroxide can promote oxidation of the metal mixture and promote the formation of an aqueous solution of a metal mixture including manganese, cobalt, nickel, and lithium.

[0040] The aqueous phase and organic phase prepared in this manner were weighed in equal volumes and mixed, and stirred for approximately 10 minutes. The mixed result was transferred to a phase separation device such as a separating funnel or allowed to stand until the organic phase and the aqueous phase were completely separated, and then the aqueous phase was separated (first separation step, S300).

[0041] In the first separation step, a pH control step (S400) is performed to adjust the pH by adding an alkaline aqueous solution to the phase-separated aqueous solution. Distilled water is added to the pH-adjusted aqueous solution, or kerosene, an organic solvent, is added to the phase-separated organic phase in the first separation step to make the volumes of the aqueous solution and the organic phase the same, and then they are mixed, stirred, and allowed to stand to separate the phases in the second separation step (S500).

[0042] In this way, an additional step (S600) of recovering manganese (Mn) from the organic phase separated in the second separation step can be performed.

[0043] In the above organic phase manufacturing step (S200), the concentration of the organic phosphorus extractant included in the organic phase is preferably about twice the concentration of the individual metal included in the metal mixture, and more preferably, the concentration of the individual metal included in the metal mixture is 0.1 M, and the concentration of the organic phosphorus extractant included in the organic phase is preferably 0.1 M.

[0044] The alkaline aqueous solution used in the above pH control step (S400) may be a sodium hydroxide aqueous solution, and for example, a 6.25 M NaOH aqueous solution may be used to control the pH value of the aqueous solution. In the present invention, the pH value was controlled using such an alkaline aqueous solution, and in order to find the pH condition with the optimal separation efficiency, the pH range of the aqueous solution was varied within the range of 1 to 11, and changes in the extraction efficiency or extraction performance of manganese were observed.

[0045] As confirmed in the experimental results described below, in the pH control step (S400), it is preferable that the pH be controlled in the range of 1 to 5, preferably 1 to 4.

[0046] Afterwards, distilled water was added to the pH-controlled aqueous phase, and kerosene, an organic solvent, was further added to the organic phase separated in the first separation step to adjust the volumes of the aqueous phase and the organic phase to the same, and then they were mixed again. The reason for additionally adding distilled water or organic solvent to the aqueous phase or the organic phase, respectively, after the pH control step is that different amounts of NaOH aqueous solution were used for pH control, and to adjust them to have the same volume as the organic phase.

[0047] When the organic layer and the aqueous layer were completely separated through the second separation step (S500), the separated aqueous layer was recovered, filtered, diluted 1 / 1000 times, and then ICP-OES was measured to confirm the amount of residual metal.

[0048] By measuring the amount of metal remaining in the aqueous solution in this way, the amount of metal separated and recovered through the organic phosphorus extractant according to the present invention in the organic phase could be known, and the manganese extraction performance of the organic phosphorus extractant was calculated through the equation (1) discussed above.

[0049]

[0050] [Example 1]

[0051] After each metal component of lithium, manganese, cobalt, and nickel was quantified, they were mixed with a 1 M sulfuric acid aqueous solution to prepare a metal mixture aqueous solution. Specifically, 2.75 g of lithium sulfate, 8.45 g of manganese chloride tetrahydrate (0.6 g of Mn), 14.55 g of cobalt nitrate hexahydrate, and 11.88 g of nickel chloride hexahydrate were weighed and mixed to prepare a model metal mixture. The model metal mixture thus prepared was dissolved in 500 ml of a 1 M sulfuric acid aqueous solution to prepare a metal mixture aqueous solution.

[0052] Existing manganese extractants, D2EHPA (comparative example), DOPOA (experimental example 1), and DDPOA (experimental example 2), were each dissolved in kerosene, an organic solvent, to prepare an extractant composition having a concentration of 0.05 M.

[0053] The metal mixture aqueous solution and the extractant composition were mixed in equal volumes (10 ml) and stirred for 10 minutes. Thereafter, the mixture was transferred to a separatory funnel to separate the organic layer and the aqueous layer. The aqueous layer was separated, and a small amount of 6.25 M NaOH was added to the aqueous layer to adjust the pH within the range of 1 to 11.

[0054] Afterwards, distilled water was additionally added so that the final volume of the aqueous layer became 40 ml, and kerosene organic solvent was added so that the volume of the organic phase also became 40 ml.

[0055] The pH-adjusted aqueous layer and the organic layer containing the organic phosphorus extractant having the same volume as the aqueous layer were mixed again, stirred, placed in a separatory funnel, and waited until the organic and aqueous layers were completely separated. The phase-separated aqueous layer was recovered, the final pH of the aqueous layer was measured, filtered, and diluted 1 / 1000 times, and then measured by ICP-OES. In each case, the extraction performance of Mn, Co, and Ni according to the pH change was calculated using the previously discussed equation (1).

[0056] After performing the extraction process in the same manner as previously described using each organic phosphorus extractant thus produced, the extraction performance of each metal was confirmed, and the results are summarized in Tables 1 to 3 below and illustrated in Figures 1 to 3, respectively.

[0057] Table 1 and Figure 1 summarize the extraction performance of Mn, Co, and Ni according to the pH value controlled in the pH adjustment step when D2EHPA, a comparative example, was used as an organic phosphorus extractant, Table 2 and Figure 2 show the extraction performance of Mn, Co, and Ni according to the pH when DOPOA, Example 1, was used as an organic phosphorus extractant, and Table 3 and Figure 3 show the extraction performance of Mn, Co, and Ni according to the pH when DDPOA, Example 2, was used as an organic phosphorus extractant.

[0058] pHMn Extraction Performance (%)Co Extraction Performance (%)Ni Extraction Performance (%)1.200.70.32.31.563.70.22.51.804.00.22.72.079.10.22.82.2010.90.232.5115.20.23.52.7019.61.14.23.0030.82.14.93.4042.12.95.54.8680.216.63.76.2493.847.16.47.2597.776.335.37.9899.294.391.910.9899.999.999.911.5299.999.999.9

[0059] pHMn Extraction Performance (%)Co Extraction Performance (%)Ni Extraction Performance (%)1.2011.300.000.001.8015.100.100.102.1718.700.600.202.4520.200.800.902.7023.201.101.503.0126.103.502.803.4032.905.103.204.2950 .3022.2018.805.3474.3027.7027.306.5690.7066.4074.307.0695.8084.4089.707.7896.6094.7091.609.3699.7099.7099.6011.5399.9099.9099.90

[0060] pHMn Extraction Performance (%)Co Extraction Performance (%)Ni Extraction Performance (%)1.2021.750.802.101.8025.221.452.302.0727.581.602.502.3432.301.602.402.4433.801.832.882.7037.702.104.302.8139.852.804.703.405 4.945.807.904.2478.3816.8012.725.6486.2831.6729.376.5294.3561.7257.277.4793.3483.0578.809.0999.1399.1199.0011.4899.6099.7099.71

[0061] As confirmed in the above experimental results, when the existing D2EHPA is used as an organophosphate extractant, the extraction performance of Mn is higher than that of Co and Ni in the pH range of 5 to 7, resulting in an excellent extraction effect. However, in the acidic range of pH 1 to 4, the extraction performance of Mn is relatively low, making selective extraction of Mn difficult. On the other hand, when DOPOA or DDPOA is used as an organophosphate extractant, the extraction performance of Mn is significantly higher than that of Co and Ni even in the acidic range of pH 1 to 4. This means that DOPOA or DDPOA, which is an organophosphate extractant according to the present invention, is effective in selectively extracting Mn even in the strongly acidic range of pH 1 to 4 compared to the existing organophosphate extractant.

[0062] In particular, when DOPOA was used as an organic phosphorus extractant (Example 1), it exhibited significantly higher Mn extraction performance than the existing organic phosphorus extractant, di-2-ethylhexylphosphoric acid (Di-(2-ethylhexyl)phosphoric acid, D2EHPA), in a strongly acidic low pH range of 1 to 4, more preferably in a pH range of 1.20 to 2.7, and exhibited excellent Mn extraction performance even in a range of pH 5 or lower (see Table 2 and Fig. 2).

[0063] In addition, even when DDPOA was used as an organic phosphorus extractant (Example 2), it showed higher Mn extraction performance than D2EHPA evenly in the acidic range of pH 1.2 to 4.24, which means that, like DOPOA, effective Mn extraction is possible up to the range of 1 to 4 and 1 to 5, which are strong acidic low pH ranges (see Table 3 and Fig. 3).

[0064] Meanwhile, when the pH is higher than the above pH range, for example, when it exceeds pH 5, it was confirmed that the extraction performance of not only Mn but also Co and Ni increases together, making selective recovery of Mn alone difficult. Therefore, it can be seen that when DOPOA or DDPOA according to the present invention is used as an organic phosphorus extractant, the preferable pH range is 1 to 5, and more preferably, it can be used in the region of pH 1 to 4. In particular, it can be confirmed that Mn can be extracted most effectively in the range of pH 1 to 3.5.

[0065] [Example 2]

[0066] As confirmed in Example 1 above, it can be seen that it is desirable to keep the pH low in terms of Mn extraction performance, and from pH 1 to 2.7, both DOPOA and DDPOA showed superior Mn extraction performance compared to D2EHPA, and in the pH range of 3 to 5, DDPOA showed superior Mn extraction performance than D2EHPA (see Fig. 4).

[0067] Extractant pHCo Mn Separation Factor for NiD2EHPA1.202.30.3DOPOA1.20127395.6127395.6DDPOA1.2034.513.0D2EHPA1.8020.81.5DOPOA1.80177.7177.7DDPOA1.8022.914.3D2EHPA2.7021.95.6DOPOA2.7027.219.8DDPOA2.7028.213.5D2EHPA3.4024.312.5DOPOA3.409.114.8DDPOA3.4019.814.2

[0068] Table 4 above compares the Mn separation coefficients by type of organic phosphorus extractant at each pH. The separation coefficients were calculated using the following equation (2), and the distribution coefficient used in equation (2) is defined as in equation (3).

[0069] Formula (2)

[0070] Formula (3)

[0071] The separation coefficient in Equation (2) is an indicator of the ability of an extractant to selectively extract a specific metal compared to other metals in a metal mixture solution. A higher separation coefficient means that the separation and extraction performance of the specific metal is superior to that of other metals.

[0072] The amount of metal in the organic layer used in calculating the distribution coefficient of formula (3) is the value obtained by subtracting the concentration of the corresponding metal in the aqueous layer after solvent extraction from the concentration of the corresponding metal in the aqueous layer before solvent extraction, and the amount of metal in the aqueous layer means the concentration of the corresponding metal in the aqueous layer after solvent extraction.

[0073] It was confirmed that the DOPOA and DDPOA extractants according to the present invention had significantly superior selective extraction performance of Mn compared to the conventional extractant D2EHPA in the pH range of 1.20 to 2.70.

[0074] The present invention is not limited to the specific embodiments and descriptions described above, and anyone with ordinary skill in the art to which the invention pertains can make various modifications without departing from the gist of the present invention as claimed in the claims, and such modifications are within the scope of protection of the present invention.

[0075] The present invention provides a solvent extraction method for separating manganese (Mn) with high purity from a cathode active material of a lithium-ion secondary battery and a highly efficient organic phosphorus extractant that can be used in this process. The organic phosphorus extractant is prepared by mixing a new type of organic phosphorus that has not been used as a conventional solvent extractant with an organic solvent, and then, through a solvent extraction method using the organic phosphorus extractant as an organic phase, manganese (Mn) can be efficiently separated and extracted in an organic solvent phase from an aqueous metal mixture solution containing manganese (Mn), cobalt (Co), and nickel (Ni), etc., and therefore, there is industrial applicability.

Claims

1. A method for selectively extracting manganese (Mn) from a metal mixture containing manganese, cobalt, nickel and lithium, Aqueous solution preparation step (S100) of preparing an aqueous solution by dissolving a metal mixture in an acidic aqueous solution; An organic phase preparation step (S200) of preparing an organic phosphoric acid extractant by mixing organic phosphoric acid and an organic solvent; A first separation step (S300) of mixing the aqueous solution phase and the organic phase in equal volumes, stirring, and allowing the phases to separate; A pH control step (S400) for controlling the pH by adding an alkaline substance to the aqueous solution phase separated in the first separation step; and A method for selectively extracting manganese (Mn) from a metal mixture using an organic phosphoric acid extractant, comprising: a second separation step (S500) of adding distilled water to an aqueous solution whose pH is adjusted, adding an organic solvent to the organic phase separated in the first separation step to make the volumes of the aqueous solution phase and the organic phase the same, mixing and stirring them again, and allowing them to stand to separate the phases.

2. In paragraph 1, A method for selectively extracting manganese (Mn) from a metal mixture using an organic phosphoric acid extractant, characterized in that the acid solution is 0.5 to 2.5 M sulfuric acid.

3. In paragraph 1, A method for selectively extracting manganese (Mn) from a metal mixture using an organic phosphoric acid extractant, characterized in that the organic solvent is kerosene.

4. In paragraph 1, A method for selectively extracting manganese (Mn) from a metal mixture using an organophosphate extractant, characterized in that the organophosphate is di-octylphosphate (DOPOA) and / or didecylphosphate (DDPOA).

5. In paragraph 1, A method for selectively extracting manganese (Mn) from a metal mixture using an organic phosphoric acid extractant, characterized in that the alkaline substance is an aqueous sodium hydroxide solution.

6. In paragraph 1, A method for selectively extracting manganese (Mn) from a metal mixture using an organic phosphoric acid extractant, characterized in that in the above pH control step (S400), pH is controlled to a range of 1 to 5.

7. In an extractant that selectively extracts manganese from a metal mixture, The above extractant is an organic phase mixed with a kerosene solvent and an organic phosphoric acid, The above organic phosphoric acid is di-octylphosphate (DOPOA) and / or di-decylphosphate (DDPOA). An organic phosphoric acid extractant for selectively extracting manganese from a metal mixture, characterized in that when an aqueous solution phase, which is an acidic metal mixture aqueous solution containing manganese, cobalt, nickel and lithium, is mixed with an organic phase, manganese in the aqueous solution phase is selectively extracted into the organic phase at a pH in the range of 1 to 5.

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