WO2013069563A1 - Cobalt extraction method - Google Patents

Abstract

The objective of the present invention is to selectively extract cobalt from an acidic solution containing a high concentration of manganese. This cobalt extraction method extracts cobalt from an acidic solution containing manganese and cobalt by subjecting the acidic solution to solvent extraction by means of a valuable metal extraction agent comprising an amide derivative represented by general formula (I). The valuable metal extraction agent is represented by the general formula. In the formula: R¹ and R² each represent the same or different alkyl group; R³ represents a hydrogen atom or an alkyl group; and R⁴ represents a hydrogen atom or any given group aside from an amino group bonded to the α carbon as an amino acid. Preferably, the general formula has a glycine unit, a histidine unit, a lysine unit, an aspartic acid unit, or an N-methylglycine unit. Preferably, the pH of the acidic solution is 3.5-5.5 inclusive.

Description

Cobalt extraction method

The present invention relates to a cobalt extraction method.

Cobalt and rare earth metals are known as valuable metals and are used for various purposes in industry. Cobalt is used in superalloys (high-strength heat-resistant alloys) used for aircraft jet engines and the like, in addition to positive electrode materials for secondary batteries. Rare earth metals are used in phosphor materials, negative electrodes for nickel metal hydride batteries, additives for magnets mounted on motors, abrasives for glass substrates used in liquid crystal panels and hard disk drives, and the like.

In recent years, energy conservation has been strongly promoted, and in the automobile industry, the transition from conventional gasoline vehicles to hybrid vehicles and electric vehicles equipped with secondary batteries using cobalt and rare earth metals is rapidly progressing. In lighting fixtures, the transition from conventional fluorescent tubes to efficient three-wavelength fluorescent tubes using rare earth metals such as lanthanum, cerium, yttrium, terbium and europium is rapidly progressing. The above cobalt and rare earth metals are rare resources, and most of them depend on imports.

However, although yttrium and europium were used as phosphors for CRT televisions for analog broadcasting, in recent years, a large number of CRTs have been discarded as used products with the shift to liquid crystal televisions. In addition, rapidly spreading products such as secondary batteries and three-wavelength fluorescent tubes can easily be expected to become a large amount of waste as used products in the future. As described above, it is not preferable from the viewpoint of resource saving and resource security to use rare resources such as cobalt and rare earth metals as waste without recycling from used products. Recently, it has been strongly desired to establish a method for effectively recovering valuable metals such as cobalt and rare earth metals from such used products.

<Recovery of cobalt from secondary batteries>
By the way, as said secondary battery, a nickel metal hydride battery, a lithium ion battery, etc. are mentioned, Manganese other than cobalt which is a rare metal is used for these positive electrode agents. And in the positive electrode material of a lithium ion battery, it tends to increase the ratio of inexpensive manganese instead of expensive cobalt. Recently, recovery of valuable metals from used batteries has been attempted. As one of the recovery methods, there is a dry method in which used batteries are put into a furnace and dissolved, and separated into metal and slag to recover the metal. However, in this method, since manganese is transferred to slag, only cobalt can be recovered.

In addition, there is also known a wet method in which a used battery is dissolved in an acid and a metal is recovered using a separation method such as a precipitation method, a solvent extraction method, or electrolytic collection. For example, in the precipitation method, there are a method of adjusting the pH of a solution containing cobalt and manganese, a method of obtaining a cobalt sulfide starch by adding a sulfurizing agent, and a method of obtaining a manganese oxide starch by adding an oxidizing agent. It is known (see Patent Document 1). However, this method has problems such as coprecipitation, and it is difficult to completely separate cobalt and manganese.

It is also known that when cobalt is recovered as a metal by electrowinning, manganese oxide is deposited on the anode surface in a system in which high-concentration manganese is present, and the anode deterioration is promoted. In addition, the specific colored fine manganese oxide floats in the electrolytic solution, and the filter cloth used for electrolytic collection is clogged, and the cobalt metal is contaminated with the manganese oxide, so that stable operation is difficult.

Also, when trying to recover cobalt using a solvent extraction method, an acidic extractant is widely used. However, as described above, since a large amount of manganese is recently used in the positive electrode of lithium ion batteries, the battery solution contains a high concentration of manganese. There is no effective extractant to extract effectively.

In addition to recycling used batteries, cobalt smelting currently used to produce cobalt is made of nickel ore such as nickel oxide ore, but nickel oxide ore has a manganese ratio compared to cobalt. It is high, and its abundance ratio is about 5 to 10 times that of cobalt, and separation of manganese is a major issue when smelting cobalt.

JP 2000-234130 A

K. Shimojo, H. Naganawa, J. Noro, F. Kubota and M. Goto; Extraction behavior and separation of lanthanides with a diglycol amic acid derivative and a nitrogen-donor ligand; Anal. Sci. 427, 23. 2007 Dec.

An object of the present invention is to provide a method for selectively extracting cobalt from an acidic solution containing manganese at a high concentration.

As a result of intensive studies to solve the above problems, the present inventors have found that the above object can be achieved by using a valuable metal extractant comprising an amide derivative represented by the following general formula (I), The present invention has been completed.

Specifically, the present invention provides the following.

（式中、Ｒ^１及びＲ^２は、それぞれ同一又は別異のアルキル基を示す。アルキル基は直鎖でも分鎖でも良い。Ｒ^３は水素原子又はアルキル基を示す。Ｒ^４は水素原子、又はアミノ酸としてα炭素に結合される、アミノ基以外の任意の基を示す。） (1) In the present invention, an acidic solution containing manganese and cobalt is subjected to solvent extraction with a valuable metal extractant composed of an amide derivative represented by the following general formula (I), and the cobalt is extracted from the acidic solution. This is a cobalt extraction method.

(In the formula, R ¹ and R ² each represent the same or different alkyl group. The alkyl group may be linear or branched. R ³ represents a hydrogen atom or an alkyl group. R ⁴ represents a hydrogen atom, Or any group other than an amino group bonded to the α-carbon as an amino acid.)

(2) Further, the present invention provides the cobalt extraction according to (1), wherein the amide derivative is any one or more of a glycinamide derivative, a histidine amide derivative, a lysine amide derivative, an aspartic acid amide derivative and a normal-methylglycine derivative. Is the method.

(3) Moreover, this invention attaches | subjects the said acidic solution to the said solvent extraction, adjusting the pH of the said acidic solution to the range of 3.5 or more and 5.5 or less, The cobalt as described in (1) or (2) Extraction method.

According to the present invention, cobalt can be selectively extracted from an acidic solution containing manganese at a high concentration.

1 is a diagram showing a ¹ H-NMR spectrum of a glycinamide derivative synthesized in Example 1. FIG. 1 is a diagram showing a ¹³ C-NMR spectrum of a glycinamide derivative synthesized in Example 1. FIG. The result when cobalt is extracted from the acidic solution containing cobalt and manganese using the valuable metal extractant of Example 1 is shown. The result when cobalt is extracted from the acidic solution containing cobalt and manganese using the valuable metal extractant of Example 2 is shown. The result when cobalt is extracted from an acidic solution containing cobalt and manganese using the valuable metal extractant of Example 3 is shown. The result when cobalt is extracted from the acidic solution containing cobalt and manganese using the valuable metal extractant of Comparative Example 1 is shown.

Hereinafter, specific embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments, and may be implemented with appropriate modifications within the scope of the object of the present invention. Can do.

<Cobalt extraction method>
The cobalt extraction method of the present invention is subjected to solvent extraction with a valuable metal extractant composed of an amide derivative represented by the following general formula (I) to extract the cobalt from the acidic solution.

In the formula, the substituents R ¹ and R ² each represent the same or different alkyl group. The alkyl group may be linear or branched. R ³ represents a hydrogen atom or an alkyl group. R ⁴ represents a hydrogen atom or an arbitrary group other than an amino group bonded to the α-carbon as an amino acid. In the present invention, by introducing an alkyl group into the amide skeleton, the lipophilicity can be increased and used as an extractant.

The amide derivative is one or more of a glycinamide derivative, a histidine amide derivative, a lysine amide derivative, an aspartic acid amide derivative and a normal-methylglycine derivative. When the amide derivative is a glycinamide derivative, the above glycinamide derivative can be synthesized by the following method. First, 2-halogenated acetyl halide is added to an alkylamine having a structure represented by NHR ¹ R ² (R ¹ and R ² are the same as the above substituents R ¹ and R ² ), and an amine is obtained by nucleophilic substitution reaction. Is substituted with 2-halogenated acetyl to give 2-halogenated (N, N-di) alkylacetamide.

Next, the above-mentioned 2-halogenated (N, N-di) alkylacetamide is added to glycine or an N-alkylglycine derivative, and one of hydrogen atoms of the glycine or N-alkylglycine derivative is (N, N) by a nucleophilic substitution reaction. Substitution with N-di) alkylacetamide groups. A glycine alkylamide derivative can be synthesized by these two-step reactions.

Replacing glycine with histidine, lysine, and aspartic acid can synthesize histidine amide derivatives, lysine amide derivatives, and aspartic acid amide derivatives. From the constant, it is considered to be within the range of the results using the glycine derivative and the histidine amide derivative.

In order to extract valuable metal ions using the extractant synthesized by the above method, this acidic aqueous solution is added to the organic solution of the extractant and mixed while adjusting the acidic aqueous solution containing the target valuable metal ions. Thereby, the target valuable metal ion can be selectively extracted into the organic phase.

The organic solvent after extracting the valuable metal ions is separated, and the reverse extraction starting liquid whose pH is adjusted lower than that of the acidic aqueous solution is added thereto and stirred to extract the desired valuable metal ions into the organic solvent. The target valuable metal ions can be recovered in the aqueous solution by separating and further back extracting the target valuable metal ions from the organic solvent. As the back extraction solution, for example, an aqueous solution in which nitric acid, hydrochloric acid, or sulfuric acid is diluted is preferably used. Moreover, the objective valuable metal ion can also be concentrated by changing suitably the ratio of an organic phase and an aqueous phase.

The organic solvent may be any solvent as long as the extractant and the metal extraction species are dissolved, for example, a chlorinated solvent such as chloroform and dichloromethane, an aromatic hydrocarbon such as benzene, toluene, and xylene, Examples thereof include aliphatic hydrocarbons such as hexane. These organic solvents may be used alone or in combination, and alcohols such as 1-octanol may be mixed.

The concentration of the extractant can be appropriately set depending on the type and concentration of valuable metals. The stirring time and extraction temperature are appropriately set according to the conditions of the acidic aqueous solution of valuable metal ions and the organic solution of the extractant because the equilibrium time varies depending on the type and concentration of the valuable metal and the amount of extractant added. do it. The pH of the acidic aqueous solution containing metal ions can also be adjusted as appropriate depending on the type of valuable metal.

[Extraction of cobalt]
When efficiently recovering cobalt from an acidic aqueous solution containing cobalt and manganese, any amino derivative may be used as an extractant as long as it is the above amino derivative. Among them, normal-methylglycine derivative or histidine amide derivative Is preferable because it has a wide pH range and is more convenient for cobalt extraction industrially. About pH, it is preferable to add the organic solution of an extractant, adjusting the pH of the acidic aqueous solution containing cobalt and manganese to 3.5 or more and 5.5 or less, and adjusting the said pH to 4.0 or more and 5.0 or less More preferably, an organic solution of the extractant is added. If the pH is less than 3.5, cobalt may not be sufficiently extracted depending on the type of the extractant. When pH exceeds 5.5, depending on the kind of extractant, not only cobalt but also manganese may be extracted.

Although the mechanism by which the extractant of the present invention takes an extraction behavior different from that of the conventional extractant is not precisely understood, it is considered that an unprecedented effect was obtained by the structural characteristics of the extractant of the present invention.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these descriptions.

<Example 1> (Synthesis of glycinamide derivative)
As an example of an amide derivative as an extractant, a glycinamide derivative represented by the following general formula (I), that is, N- [N, N-bis (2-ethylhexyl) aminocarbonyl into which two 2-ethylhexyl groups are introduced Methyl] glycine (N- [N, N-Bis (2-ethylhexyl) aminocarbonylmethyl] glycine) (or N, N-di (2-ethylhexyl) acetamido-2-glycine (N, N-di (2-ethylhexyl) acetamide) -2-glycine), hereinafter referred to as “D2EHAG”).

D2EHAG was synthesized as follows. First, as shown in the following reaction formula (II), 23.1 g (0.1 mol) of commercially available di (2-ethylhexyl) amine and 10.1 g (0.1 mol) of triethylamine were separated into chloroform. Then, 13.5 g (0.12 mol) of 2-chloroacetyl chloride was added dropwise, then washed once with 1 mol / l hydrochloric acid, then with ion-exchanged water, and the chloroform phase was separated. did.
Next, an appropriate amount (about 10 to 20 g) of anhydrous sodium sulfate was added and dehydrated, followed by filtration to obtain 29.1 g of a yellow liquid. When the structure of this yellow liquid (reaction product) was identified using a nuclear magnetic resonance analyzer (NMR), the yellow liquid was identified as 2-chloro-N, N-di (2-ethylhexyl) acetamide (hereinafter “ CDEHAA ”)). The yield of CDEHAA was 90% with respect to di (2-ethylhexyl) amine as a raw material.

Next, as shown in the following reaction formula (III), methanol is added to and dissolved in 8.0 g (0.2 mol) of sodium hydroxide, and the solution in which 15.01 g (0.2 mol) of glycine is further added is stirred. Then, 12.72 g (0.04 mol) of the above CDEHAA was slowly added dropwise and stirred. After completion of the stirring, the solvent in the reaction solution was distilled off, and chloroform was added to the residue to dissolve it. The solution was acidified by adding 1 mol / l sulfuric acid, washed with ion-exchanged water, and the chloroform phase was separated.
An appropriate amount of anhydrous magnesium sulfate was added to the chloroform phase for dehydration and filtration. The solvent was removed again under reduced pressure to obtain 12.5 g of a yellow paste. The yield based on the above CDEHAA amount was 87%. When the structure of the yellow paste was identified by NMR and elemental analysis, it was confirmed that it had a D2EHAG structure as shown in FIGS. The valuable metal extractant of Example 1 was obtained through the above steps.

<Example 2> (Synthesis of normal-methylglycine derivative)
As another example of an amide derivative serving as an extractant, a normal-methylglycine derivative represented by the following general formula (I), that is, N- [N, N-bis (2- Ethylhexyl) aminocarbonylmethyl] sarcosine (N- [N, N-Bis (2-ethylhexyl) aminocarbonylmethyl) sarcosine) (or N, N-di (2-ethylhexyl) acetamido-2-sarcosine (N, N-di (2 -Ethylhexyl) acetamide-2-sarcocine), hereinafter referred to as "D2EHAS").

The synthesis of D2EHAS was performed as follows. As shown in the following reaction formula (IV), methanol is added to and dissolved in 5.3 g (0.132 mol) of sodium hydroxide, and 11.8 g (0.132 mol) of sarcosine (N-methylglycine) is further added. While stirring, 36.3 g (0.12 mol) of the above CDEHAA was slowly added dropwise and stirred. After completion of the stirring, the solvent in the reaction solution was distilled off, and chloroform was added to the residue to dissolve it. The solution was acidified by adding 1 mol / l sulfuric acid, washed with ion-exchanged water, and the chloroform phase was separated.
An appropriate amount of anhydrous magnesium sulfate was added to the chloroform phase for dehydration and filtration. The solvent was removed again under reduced pressure to obtain 26.8 g of a tan paste. The yield based on the above CDEHAA amount was 60%. When the structure of the yellow paste was identified by NMR and elemental analysis, it was confirmed to have a D2EHAS structure. The valuable metal extractant of Example 2 was obtained through the above steps.

<Example 3> (Synthesis of histidine amide derivative)
As another example of the amide derivative used as an extractant, a histidine amide derivative represented by the following general formula (I), that is, N- [N, N-bis (2-ethylhexyl) into which two 2-ethylhexyl groups are introduced Aminocarbonylmethyl] histidine (N- [N, N-Bis (2-ethylhexyl) aminocarbenylmethyl) histidine) (or N, N-di (2-ethylhexyl) acetamido-2-histidine (N, N-di (2-ethylhexyl)) ) Acetamide-2-histidine), hereinafter referred to as “D2EHAH”).

The synthesis of D2EHAH was performed as follows. As shown in the following reaction formula (V), methanol was added to 16 g (0.4 mol) of sodium hydroxide to dissolve it, and further, 31.0 g (0.2 mol) of histidine was further added, while stirring, the CDEHAA13. 2 g (0.04 mol) was slowly added dropwise. After completion of dropping, the mixture was stirred while maintaining alkaline conditions. After completion of the stirring, the solvent in the reaction solution was distilled off, and the residue was dissolved by adding ethyl acetate. This solution was washed and the ethyl acetate phase was separated.
An appropriate amount of anhydrous magnesium sulfate was added to the ethyl acetate phase for dehydration and filtration. The solvent was removed again under reduced pressure to obtain 9.9 g of a tan paste. The yield based on the above CDEHAA amount was 57%. When the structure of the yellowish brown paste was identified by NMR and elemental analysis, it was confirmed to have the structure of D2EHAH. The valuable metal extractant of Example 3 was obtained through the above steps.

<Comparative Example 1>
As the valuable metal extractant of Comparative Example 1, a commercially available carboxylic acid-based cobalt extractant (trade name: VA-10, neodecanoic acid, manufactured by Hexion Specialty Chemicals Japan) was used.

<Comparative example 2>
As the valuable metal extractant of Comparative Example 2, N, N-dioctyl-3-oxapentane-1,5-amidic acid (hereinafter referred to as “DODGAA”), which is a conventionally known europium extractant, was used.

The synthesis of DODGAA was performed as follows. First, as shown in the following reaction formula (VI), 4.2 g of diglycolic anhydride was placed in a round bottom flask and suspended in 40 ml of dichloromethane. Thereafter, 7 g of dioctylamine (purity 98%) was dissolved in 10 ml of dichloromethane and slowly added with a dropping funnel. While stirring at room temperature, it was confirmed that diglycolic anhydride reacted and the solution became transparent, and the reaction was terminated.

Subsequently, the solution was washed with water to remove water-soluble impurities. Then, sodium sulfate was added as a dehydrating agent to the solution after washing with water. The solution was filtered with suction, and then the solvent was evaporated. And after recrystallizing (three times) using hexane, it vacuum-dried. The yield of the obtained substance was 9.57 g, and the yield based on the above diglycolic anhydride was 94.3%. And when the structure of the obtained substance was identified by NMR and elemental analysis, it was confirmed that it was DODGAA having a purity of 99% or more.

<Extraction of cobalt>
Using the valuable metal extractant of Examples 1 to 3 and Comparative Example 1, cobalt was extracted and separated.

[Examples 1 to 3]
Contains several types of sulfuric acid acid solutions containing 1 × 10 ⁻⁴ mol / l of cobalt and manganese each and pH adjusted to 2.5 to 7.5, and 0.01 mol / l of valuable metal extractant with the same volume. The normal dodecane solution was added to a test tube, placed in a thermostatic chamber at 25 ° C., and shaken for 24 hours. At this time, the pH of the sulfuric acid solution was adjusted using sulfuric acid, ammonium sulfate and ammonia having a concentration of 0.1 mol / l.

After shaking, the aqueous phase was fractionated and the cobalt concentration and manganese concentration were measured using an induction plasma emission spectroscopic analyzer (ICP-AES). The organic phase was back extracted with 1 mol / l sulfuric acid. Then, the cobalt concentration and the manganese concentration in the back extraction phase were measured using ICP-AES. From these measurement results, the extraction rate of cobalt and manganese was defined by the quantity in the organic phase / (the quantity in the organic phase + the quantity in the aqueous phase). The result when using the valuable metal extractant of Example 1 is shown in FIG. 3, the result when using the valuable metal extractant of Example 2 is shown in FIG. 4, and the valuable metal extractant of Example 3 is used. FIG. 5 shows the result of the measurement. 3 to 5, the horizontal axis represents the pH of the sulfuric acid acidic solution, and the vertical axis represents the extraction rate (unit:%) of cobalt or manganese. In the graph, squares indicate cobalt extraction rates, and circles indicate manganese extraction rates.

[Comparative Example 1]
Except that the pH of the sulfuric acid acidic solution was adjusted to 4.0 to 7.5 and that the concentration of the normal dodecane solution containing the valuable metal extractant was 0.1 mol / l, which is 10 times that of the example. Cobalt was extracted in the same manner as in the example. The results are shown in FIG. The horizontal axis of FIG. 6 is the pH of the sulfuric acid acidic solution, and the vertical axis is the extraction rate (unit:%) of cobalt or manganese. In the graph, the square indicates the extraction rate of cobalt, and the diamond shape indicates the extraction rate of manganese.

It was confirmed that when the valuable metal extractant of the example was used, cobalt could be extracted at an extraction rate exceeding 20% in the range of pH 3.0 to 5.5 (FIGS. 3 to 5). In particular, when normal-methylglycine derivatives or histidine amide derivatives were used, it was confirmed that the pH range was wide and more convenient when industrially performing the cobalt extraction of the present invention (FIG. 4, FIG. 4). 5). Regardless of the type of derivative, it was confirmed that cobalt could be extracted at an extraction rate exceeding 80% and manganese was hardly extracted when the pH ranged from 4.0 to 5.0 (FIG. 3 to FIG. 3). FIG. 5). On the other hand, when the valuable metal extractant of Comparative Example 1 was used, even if the concentration of the extractant was 10 times that of the Example, it was confirmed that cobalt could be extracted only with an extraction rate of less than 20% (FIG. 6). .

Claims (3)

A cobalt extraction method comprising subjecting an acidic solution containing manganese and cobalt to solvent extraction with a valuable metal extractant composed of an amide derivative represented by the following general formula (I) to extract the cobalt from the acidic solution.

(In the formula, R ¹ and R ² each represent the same or different alkyl group. The alkyl group may be linear or branched. R ³ represents a hydrogen atom or an alkyl group. R ⁴ represents a hydrogen atom, Or any group other than an amino group bonded to the α-carbon as an amino acid.) The cobalt extraction method according to claim 1, wherein the amide derivative is one or more of a glycinamide derivative, a histidine amide derivative, a lysine amide derivative, an aspartic acid amide derivative and a normal-methylglycine derivative. The cobalt extraction method according to claim 1 or 2, wherein the acidic solution is subjected to the solvent extraction while adjusting a pH of the acidic solution to a range of 3.5 or more and 5.5 or less.

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