Note: Descriptions are shown in the official language in which they were submitted.
CA 02827601 2013-08-16
COBALT EXTRACTION METHOD
TECHNICAL FIELD
The present invention relates to a cobalt extraction
method.
BACKGROUND ART
Cobalt and rare earth metals are known as valuable metals
and used for various applications in industry. Cobalt is used
for positive electrode materials for secondary batteries, and,
furthermore, superalloys (high strength heat-resistant alloys)
used for e.g. jet engines for aircraft, and the like. Rare
earth metals are used for fluorescent materials, negative
electrode materials for nickel-hydrogen batteries, additives
for magnets installed in motors, abrasives for glass
substrates used for liquid crystal display panels and hard
disk drives, and the like.
In recent years, energy savings have been strongly
promoted, and in the automobile industry, conventional
gasoline-engined cars are being rapidly replaced by hybrid
cars and electric cars equipped with secondary batteries using
cobalt and rare earth metals. In lighting equipment,
conventional fluorescent lamps are being rapidly replaced by
efficient three band fluorescent lamps using rare earth metals
such as lanthan, cerium, yttrium, terbium and europium. The
above cobalt and rare earth metals are scarce resources, and
most of them depend on imports.
12-00470 (SMMF-010)
CA 02827601 2013-08-16
2
Yttrium and europium have been used for fluorescent
substances in cathode ray tube television sets in analog
broadcasting; however, in recent years, large numbers of
cathode ray tubes have been put out of use because of the
transition to liquid crystal television sets. Products which
have rapidly spread, such as secondary batteries and three
band fluorescent lamps, can be also easily expected to cause a
large amount of waste in the future as used products. Thus,
cobalt and rare earth metals, scarce resources, are treated as
waste without recycling of the used products, which is not
preferred in terms of resource savings and resource security.
Nowadays, the establishment of a method for effectively
retrieving valuable metals such as cobalt and rare earth
metals from such used products is strongly demanded.
Retrieval of cobalt from secondary batteries
The above secondary batteries, incidentally, include
nickel-hydrogen batteries, lithium ion batteries and the like,
and in addition to cobalt, a rare earth metal, manganese is
used for positive electrode materials thereof. In positive
electrode materials in lithium ion batteries, the ratio of low
cost manganese tends to be increased in place of high cost
cobalt. The retrieval of valuable metals from used batteries
has been attempted recently, and as one of the retrieval
methods, there is a dry method in which used batteries are
thrown into a furnace and melted, and metals and slag are
separated to retrieve the metals. In this method, however,
manganese moves to slag, and thus the metal that can be
12-00470 (SMMF-010)
CA 02827601 2013-08-16
3
retrieved is only cobalt.
Further, a wet method is known, in which used batteries
are dissolved in an acid and metals are retrieved using a
separation method such as a precipitation method, a solvent
extraction method or an electrowinning method. In the
precipitation method, for example, a method in which the pH of
a solution comprising cobalt and manganese is adjusted and a
sulphurizing agent is added thereto to obtain a cobalt
sulphide precipitate, and a method in which an oxidizing agent
is added thereto to obtain a manganese oxide precipitate are
known (see Patent Document 1). The methods, however, have
problems such as the occurrence of coprecipitation, and it is
difficult to completely separate cobalt and manganese.
It is known that when cobalt is retrieved as a metal by
the electrowinning method, in a system in which a high
concentration of manganese exists, manganese oxides are
precipitated on the surface of an anode and deterioration of
the anode is promoted. In addition, a peculiar colored fine
manganese oxide is suspended in an electrolytic solution, and
thus, for example, clogging of the filter cloth used for
electrowinning and contamination of cobalt metal by the
manganese oxide occur. Therefore, stable operations are
difficult.
When cobalt is retrieved using the solvent extraction
method, an acid extraction agent is widely used. As described
above, however, nowadays manganese is used in large amounts
for positive electrode materials in lithium ion batteries, and
12-00470 (SMMF-010)
CA 02827601 2013-08-16
4
thus a high concentration of manganese exists In the solution
in the batteries. Efficient extraction agents which
selectively and efficiently extract cobalt from such a system
do not exist in the existing circumstances.
In addition to recycling used batteries, in cobalt
smelting which is currently carried out to produce cobalt, a
raw material is a nickel ore such as a nickel oxide ore. The
percentage of manganese is however higher than that of cobalt
in the nickel oxide ore, and the existing percentage thereof
is about 5 to 10 times that of cobalt. When cobalt is smelted,
separation from manganese is a major problem.
Patent Document 1: Japanese Unexamined Patent Application,
Publication No. 2000-234130
Non-Patent Document 1: 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., 23, 1427-30, 2007 Dec.
DISCLOSURE OF THE INVENTION
Problems to be Solved by the Invention
An object of the present invention is to provide a method
for selectively extracting cobalt from an acid solution
comprising a high concentration of manganese.
As a result of repeated intensive investigation to solve
the above problem, the present inventors found that the above
object could be achieved by using a valuable metal extraction
agent comprising an amide derivative represented by the
12-00470 (SMMF-010)
CA 02827601 2013-08-16
following general formula (I), completing the present
invention.
Means for Solving the Problems
Specifically, the present invention provides as follows.
(1) The present invention is a cobalt extraction method,
wherein an acid solution containing manganese and cobalt is
subjected to solvent extraction by a valuable metal extraction
agent comprising an amide derivative represented by the
following general formula (I) to extract the cobalt from the
acid solution:
R4
R1
R2
(I)
0 R3 0
(wherein, Rl and R2 each represent the same or different alkyl
groups;the alkyl group can be a straight chain or a branched
chain; R3 represents a hydrogen atom or an alkyl group; and R4
represents a hydrogen atom or any group other than an amino
group, which is bound to the a carbon as an amino acid).
(2) The present invention is also the cobalt extraction
method according to (1), wherein the amide derivative is any
one or more of glycinamide derivatives, histidinamide
derivatives, lysinamide derivatives, aspartic acid amide
derivatives and N-methylglycine derivatives.
(3) The present invention is also the cobalt extraction
method according to (1) or (2), wherein the acid solution is
subjected to the solvent extraction with the pH of the acid
12-00470 (SMMF-010)
CA 02827601 2013-08-16
6
solution adjusted to a range of 3.5 or more to 5.5 or less.
Effects of the Invention
According to the present invention, cobalt can be
selectively extracted from an acid solution comprising a high
concentration of manganese.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a figure showing a 1H-NMR spectrum of a
glycinamide derivative synthesized in Example 1.
Fig. 2 is a figure showing a 13C-NMR spectrum of a
glycinamide derivative synthesized in Example 1.
Fig. 3 shows the results of the extraction of cobalt from
an acid solution comprising cobalt and manganese using the
valuable metal extraction agent of Example 1.
Fig. 4 shows the results of the extraction of cobalt from
an acid solution comprising cobalt and manganese using the
valuable metal extraction agent of Example 2.
Fig. 5 shows the results of the extraction of cobalt from
an acid solution comprising cobalt and manganese using the
valuable metal extraction agent of Example 3.
Fig. 6 shows the results of the extraction of cobalt from
an acid solution comprising cobalt and manganese using the
valuable metal extraction agent of Comparative Example 1.
PREFERRED MODE FOR CARRYING OUT THE INVENTION
The specific embodiments of the present invention will now
be described in detail. It should be noted, however, that the
12-00470 (SMMF-010)
CA 02827601 2013-08-16
7
present invention is not restricted to the following
embodiments and can be carried out with proper modification
within the scope of the object of the present invention.
Cobalt extraction method
In the cobalt extraction method of the present invention,
cobalt is extracted from an acid solution by solvent
extraction by a valuable metal extraction agent comprising an
amide derivative represented by the following general formula
(I).
R4
R1
R2
1 (1)
0 R3 0
In the formula, substituents R1 and R2 each represent the
same or different alkyl groups. The alkyl group can be a
straight chain or a branched chain. R3 represents a hydrogen
atom or an alkyl group. R4 represents a hydrogen atom or any
group other than an amino group, which is bound to the a
carbon as an amino acid. In the present invention,
lipophilicity is increased by introducing alkyl groups into
the amide skeleton, and the compound can be used as an
extraction agent.
The above amide derivative is any one or more of
glycinamide derivatives, histidinamide derivatives, lysinamide
derivatives, aspartic acid amide derivatives and N-
methylglycine derivatives. When the amide derivative is a
glycinamide derivative, the above glycinamide derivative can
12-00470 (SMMF-010)
CA 02827601 2013-08-16
8
be synthesized by the following method. First, a 2-halogenated
acetyl halide is added to an alkylamine having a structure
represented by NHR1R2 (Rl and R2 are the same as the above
substituents Rl and R2), and the hydrogen atom of amine is
substituted with a 2-halogenated acetyl by the nucleophilic
substitution reaction to obtain a 2-halogenated (N,N-
di)alkylacetamide.
Next, the above 2-halogenated (N,N-di)alkylacetamide is
added to glycine or an N-alkylglycine derivative, and one of
the hydrogen atoms of the glycine or N-alkylglycine derivative
is substituted with an (N,N-di)alkylacetamide group by the
nucleophilic substitution reaction. A glycine alkylamide
derivative can be synthesized by the two-step reactions.
A histidinamide derivative, a lysinamide derivative or an
aspartic acid amide derivative can be synthesized by
substituting glycine with histidine, lysine or aspartic acid.
The extraction behavior of lysine and aspartic acid
derivatives is, however, thought to be within the range of the
results obtained by using a glycine derivative and a
histidinamide derivative according to the complex stability
constant of manganese, cobalt and the like, which are targets.
To extract valuable metal ions using an extraction agent
synthesized by the above method, with an acid aqueous solution
comprising the objective valuable metal ions being adjusted,
the acid aqueous solution is added to an organic solution of
the above extraction agent, and mixed. Therefore, the
objective valuable metal ions can be selectively extracted in
12-00470 (SMMF-010)
CA 02827601 2013-08-16
9
the organic phase.
The organic solvent after extraction of the valuable metal
ions is collected, and to this, a starting solution for back
extraction is added and stirred to separate the objective
valuable metal ions by extraction to an organic solvent, which
starting solution is adjusted to a pH lower than that of the
above acid aqueous solution. The objective valuable metal ions
can be further retrieved from the organic solvent in an
aqueous solution by back extraction of the objective valuable
metal ions. As a solution for back extraction, for example, an
aqueous solution in which nitric acid, hydrochloric acid or
sulfuric acid is diluted is suitably used. In addition, the
objective valuable metal ions can be concentrated by suitably
changing the ratio of the organic phase and the aqueous phase.
Any organic solvent can be used, as long as an extraction
agent and the extracted species of metals are dissolved with
the solvent, and examples thereof include chlorine-based
solvents such as chloroform and dichloromethane, aromatic
hydrocarbons such as benzene, toluene and xylene, aliphatic
hydrocarbons such as hexane, and the like. These organic
solvents can be used individually, or two or more organic
solvents can be mixed, and alcohols such as 1-octanol can be
mixed therewith.
The concentration of the extraction agent can be properly
set depending on the types and concentrations of valuable
metals. In addition, the equilibrium arrival time varies
depending on the types and concentrations of valuable metals
12-00470 (SMMF-010)
CA 02827601 2013-08-16
and the amounts of extraction agent to be added, and thus the
stirring time and extraction temperature can be suitably set
depending on the conditions of an acid aqueous solution of
valuable metal ions and an organic solution of the extraction
agent. The pH of an acid aqueous solution comprising metal
ions can be also suitably adjusted depending on the types of
valuable metal.
Extraction of cobalt
When cobalt is efficiently retrieved from an acid aqueous
solution containing cobalt and manganese, any amino derivative
of the above amino derivatives can be used as an extraction
agent. Among these, it is preferred to use an N-methylglycine
derivative or a histidinamide derivative since the suitable pH
range is wide and thus the convenience is greater when cobalt
is industrially extracted. Regarding pH, it is preferred that,
with the pH of an acid aqueous solution comprising cobalt and
manganese adjusted to 3.5 or more and 5.5 or less, an organic
solution of an extraction agent be added thereto, and it is
more preferred that, with the above pH adjusted to 4.0 or more
and 5.0 or less, an organic solution of an extraction agent be
added thereto. When the pH is less than 3.5, there is a
possibility that cobalt cannot be sufficiently extracted
depending on the types of extraction agent. When the pH is
above 5.5, there is a possibility that not only cobalt but
also manganese is extracted depending on the types of
extraction agent.
The mechanism in which the extraction agent of the present
12-00470 (SMMF-010)
CA 02827601 2013-08-16
II
invention has an extraction behavior different from
conventional extraction agents is not accurately grasped, and
it is thought that the effects which conventional extraction
agents do not have are obtained by the structural
characteristics of the extraction agent of the present
invention.
EXAMPLES
The present invention will now be described in more detail
by way of examples. It should be noted, however, that the
present invention is not restricted to these descriptions.
Example 1 (Synthesis of glycinamide derivatives)
As an example of amide derivatives forming an extraction
agent, a glycinamide derivative represented by the following
general formula (I) was synthesized, that is, N-[N,N-bis(2-
ethylhexyl)aminocarbonylmethyl]glycine (or also referred to as
N,N-di(2-ethylhexyl)acetamide-2-glycine), hereinafter referred
to as "D2EHAG"), into which two 2-ethylhexyl groups are
introduced.
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 collected. These were dissolved by
adding chloroform, and 13.5 g (0.12 mol) of 2-chloroacetyl
chloride was then added by drops thereto, followed by washing
with 1 mol/1 hydrochloric acid once. After this, washing was
carried out with ion exchanged water and the chloroform phase
12-00470 (SMMF-010)
CA 02827601 2013-08-16
12
was collected.
Next, anhydrous sodium sulphate was added in a suitable
amount (approximately 10 to 20 g) for dehydration, followed by
filtration to obtain 29.1 g of yellow liquid. When the
structure of this yellow liquid (reaction product) was
identified using a nuclear magnetic resonance spectrometer
(NMR), the above yellow liquid was confirmed to have the
structure of 2-chloro-N,N-di(2-ethylhexyl)acetamide
(hereinafter referred to as "CDEHAA"). The percent yield of
CDEHAA was 90% relative to di(2-ethylhexyl)amine, a raw
material.
0
NH 0
Et3N/CHCI3
HCI
cIcI
CDEHAA
Next, as shown in the following reaction formula (III),
8.0 g (0.2 mol) of sodium hydroxide was dissolved by adding
methanol, and 15.01 g (0.2 mol) of glycine was further added
thereto. While stirring the obtained solution, 12.72 g (0.04
mol) of the above CDEHAA was slowly added by drops thereto and
stirred. After completion of stirring, the solvent in the
reaction liquid was distilled off, and the residue was
dissolved by adding chloroform. To this solution, 1 mol/1
sulphuric acid was added for acidification, followed by
washing with ion exchanged water, and the chloroform phase was
collected.
To this chloroform phase, anhydrous magnesium sulphate was
12-00470 (SMMF-010)
CA 02827601 2013-08-16
13
added in a suitable amount for dehydration, followed by
filtration. The solvent was removed under reduced pressure
again to obtain 12.5 g of yellow paste. The percent yield
based on the amount of the above CDEHAA was 87%. When the
structure of the yellow paste was identified by NMR and
elemental analysis, the paste was confirmed to have the
structure of D2EHAG as shown in Fig. 1 and Fig. 2. The above
steps were carried out to obtain a valuable metal extraction
agent of Example 1.
0
0
H,14
OH
OH +HCI (HT
0
D2E HAG
Example 2 (Synthesis of N-methylglycine derivatives)
As another example of amide derivatives forming an
extraction agent, an N-methylglycine derivative represented by
the following general formula (I) was synthesized, that is, N-
[N,N-bis(2-ethylhexyl)aminocarbonylmethyl]sarcosine (or also
referred to as N,N-di(2-ethylhexyl)acetamide-2-sarcosine),
hereinafter referred to as "D2EHAS"), into which two 2-
ethylhexyl groups are introduced.
D2EHAS was synthesized as follows. As shown in the
following reaction formula (IV), 5.3 g (0.132 mol) of sodium
hydroxide was dissolved by adding methanol, and 11.8 g (0.132
mol) of sarcosine (N-methylglycine) was also added thereto.
While stirring the obtained solution, 36.3 g (0.12 mol) of the
above CDEHAA was slowly added by drops thereto and stirred.
2-00470 (SMo F-0 w)
CA 02827601 2013-08-16
14
After completion of stirring, the solvent in the reaction
liquid was distilled off, and the residue was dissolved by
adding chloroform. To this solution, 1 mo1/1 sulphuric acid
was added for acidification, followed by washing with ion
exchanged water, and the chloroform phase was collected.
To this chloroform phase, anhydrous magnesium sulphate was
added in a suitable amount for dehydration, followed by
filtration. The solvent was removed under reduced pressure
again to obtain 26.8 g of yellowish brown paste. The percent
yield based on the amount of the above CDEHAA was 60%. When
the structure of the yellow paste was identified by NMR and
elemental analysis, the paste was confirmed to have the
structure of D2EHAS. The above steps were carried out to
obtain a valuable metal extraction agent of Example 2.
CIN Hõ
0 Na0H/Me0H c8 CH,
0 7%; HCI \
+/ )
C3Flie'lr'N---y IV
H3C OH
0 OH
Example 3 (Synthesis of histidinamide derivatives)
As another example of amide derivatives forming an
extraction agent, a histidinamide derivative represented by
the following general formula (I) was synthesized, that is, N-
[N,N-bis(2-ethylhexyl)aminocarbonylmethyl]histidine (or also
referred to as N,N-di(2-ethylhexyl)acetamide-2-histidine),
hereinafter referred to as "D2EHAH"), into which two 2-
ethylhexyl groups are introduced.
D2EHAH was synthesized as follows. As shown in the
following reaction formula (V), 16 g (0.4 mol) of sodium
12-00470 (SMMF-010)
CA 02827601 2013-08-16
hydroxide was dissolved by adding methanol, and 31.0 g (0.2
mol) of histidine was also added thereto. While stirring the
obtained solution, 13.2 g (0.04 mol) of the above CDEHAA was
slowly added by drops thereto. After completion of the drop-
by-drop addition, stirring was carried out with alkaline
conditions maintained. After completion of stirring, the
solvent in the reaction liquid was distilled off, and the
residue was dissolved by adding ethyl acetate. This solution
was washed, and the ethyl acetate phase was collected.
To this ethyl acetate phase, anhydrous magnesium sulphate
was added in a suitable amount for dehydration, followed by
filtration. The solvent was removed under reduced pressure
again to obtain 9.9 g of yellowish brown paste. The percent
yield based on the amount of the above CDEHAA was 57%. When
the structure of the yellowish brown paste was identified by
NMR and elemental analysis, the paste was confirmed to have
the structure of D2EHAH. The above steps were carried out to
obtain a valuable metal extraction agent of Example 3.
NH
0 0
4'
NaOH / Me0H 001,7 N
<,,Nyyt,OH
,NI
HN NH2C8H1)r--N
HCI (V)
OH
Comparative Example 1
As a valuable metal extraction agent of Comparative
Example 1, a commercially available carboxylic acid-based
cobalt extraction agent (Product name: VA-10, neodecanoic acid,
manufactured by Hexion Specialty Chemicals Japan) was used.
Comparative Example 2
12-00470 (SMMF-010)
CA 02827601 2013-08-16
16
As a valuable metal extraction agent of Comparative
Example 2, N,N-diocty1-3-oxapentan-1,5-amic acid (hereinafter
referred to as "DODGAA"), a conventionally known europium
extraction agent was used.
DODGAA was synthesized as follows. First, as shown in the
following reaction formula (VI), 4.2 g of anhydrous diglycolic
acid was put into a round bottom flask, and 40 ml of
dichloromethane was put therein and suspended. After that, 7 g
of dioctylamine (purity 98%) was dissolved in 10 ml of
dichloromethane, and the obtained solution was slowly added
thereto using a dropping funnel. While stirring the solution
at room temperature, the solution was confirmed to become
clear by the reaction of anhydrous diglycolic acid, and the
reaction was completed.
//0 OH
(C81-117)2NH
Dioctylamine
0 0 ________________ 0
in dichlorcmothanc 0 (VI)
\r1 (
anhydrous diglycolic acid
C8H17
dioctyl diglycoi amic acid
(DODGAA)
Subsequently, the above solution was washed with water to
remove water-soluble impurities. After washing with water,
sodium sulphate was added to the solution as a dehydrating
agent. The solution was subjected to suction filtration, and
12-00470 (SMMF-010)
CA 02827601 2013-08-16
17
the solvent was then vaporized. Recrystallization was carried
out with hexane (three times), followed by vacuum drying. The
yield of the obtained substance was 9.57 g, and the percent
yield based on the above anhydrous diglycolic acid was 94.3%.
When the structure of the obtained substance was identified by
NMR and elemental analysis, the substance was confirmed to be
DODGAA with a purity of 99% or more.
Extraction of cobalt
Cobalt was extracted and separated using the valuable
metal extraction agents of Examples 1 to 3 and Comparative
Example 1.
Examples 1 to 3
Several types of acid solution of sulphuric acid
comprising cobalt and manganese each in an amount of 1 x 10-4
mo1/1 and being adjusted to pH 2.5 to 7.5, and an equal volume
of an n-dodecane solution comprising 0.01 mo1/1 of a valuable
metal extraction agent were added together in test tubes, and
the test tubes were put into a constant temperature oven at
25 C and shaken for 24 hours. At this time, the pH of the
sulphuric acid solution was adjusted using 0.1 mo1/1 sulphuric
acid, ammonium sulphate and ammonia.
After shaking, the aqueous phase was collected, and the
cobalt concentration and the manganese concentration were
measured using inductively coupled plasma-atomic emission
spectroscopy (ICP-AES). The organic phase was subjected to
back extraction using 1 mo1/1 sulphuric acid. The cobalt
concentration and the manganese concentration in the back
12-00470 (SMMF-010)
CA 02827601 2013-08-16
18
extraction phase were measured using ICP-AES. From these
measurement results, the extraction rates of cobalt and
manganese were defined as the amount of material in the
organic phase/(the amount of material in the organic phase +
the amount of material in the aqueous phase) and measured. The
results of the use of the valuable metal extraction agent of
Example 1 are shown in Fig. 3, the results of the use of the
valuable metal extraction agent of Example 2 are shown in Fig.
4, and the results of the use of the valuable metal extraction
agent of Example 3 are shown in Fig. 5. In Figs. 3 to 5, the
abscissa is the pH of an acid solution of sulphuric acid, and
the ordinate is the extraction rate (unit: %) of cobalt or
manganese. In the graphs, the square indicates the extraction
rate of cobalt and the circle indicates the extraction rate of
manganese.
Comparative Example 1
Cobalt was extracted by the same method as in the Examples
except that the pH of an acid solution of sulphuric acid was
adjusted to 4.0 to 7.5 and the concentration of the n-dodecane
solution comprising the valuable metal extraction agent was
changed to 0.1 mo1/1, which is ten times the concentration in
the Examples. The results are shown in Fig. 6. In Fig. 6, the
abscissa is the pH of an acid solution of sulphuric acid, and
the ordinate is the extraction rate (unit: %) of cobalt or
manganese. In the graph, the square indicates the extraction
rate of cobalt and the diamond indicates the extraction rate
of manganese.
12-00470 (SMMF-010)
CA 02827601 2013-08-16
19
It was recognized that by using the valuable metal
extraction agents of the Examples, cobalt could be extracted
at an extraction rate of at least above 20% in a pH range of
3.0 or more to 5.5 or less (Fig. 3 to Fig. 5). In particular,
it was recognized that by using an N-methylglycine derivative
or a histidinamide derivative, the suitable pH range was wide,
and convenience was greater when industrially carrying out the
cobalt extraction of the present invention (Fig. 4, Fig. 5).
It was also recognized that cobalt could be extracted at an
extraction rate of above 80% and manganese was hardly
extracted in a pH range of 4.0 or more to 5.0 or less
regardless of the types of derivative (Fig. 3 to Fig. 5).
Meanwhile, it was recognized that by using the valuable metal
extraction agent of Comparative Example 1, cobalt could be
extracted only at an extraction rate of less than 20% even
when the concentration of the extraction agent was ten times
that in the Examples (Fig. 6).
12-00470 (SMMF-010)
