JP2015183267A - Production method of aqueous solution of cobalt chloride - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a production method capable of producing an aqueous solution of cobalt chloride of a low Ni concentration, in a method for solvent-extracting Co from an aqueous solution of nickel chloride containing Co by an organic solvent composed of an amine-based extraction agent and a diluent.SOLUTION: A solvent extraction method is provided, in which Co is solvent-extracted from an aqueous solution of nickel chloride containing Co by an organic solvent composed of an amine-based extraction agent and a diluent using a countercurrent multistage extractor to produce an aqueous solution of cobalt chloride. The solvent extraction method includes three stages of an extraction stage for extracting Co from the aqueous solution of nickel chloride containing Co to the organic phase to obtain the aqueous solution of nickel chloride free of Co, a washing stage for bringing part of a water phase after back extraction into contact with the organic phase to which Co is extracted, to remove Ni in the organic phase, and a back extraction stage for removing Co from the organic phase after washing by a weak acidic aqueous solution to obtain an aqueous solution of cobalt chloride. In the washing stage, the organic phase is continuous in a mixer tank, where a volume ratio of the organic phase to the water phase is 3.0 or less.

Description

  The present invention relates to a nickel and cobalt hydrometallurgical process for separating and recovering cobalt from a nickel chloride aqueous solution containing cobalt by solvent extraction of cobalt with an organic solvent comprising an amine-based extractant and a diluent. More specifically, cobalt chloride is obtained by mixing and contacting a part of the aqueous phase after back-extraction with the organic phase from which cobalt has been extracted to remove nickel in the organic phase, thereby obtaining a cobalt chloride aqueous solution having a low nickel concentration. The present invention relates to a method for producing an aqueous solution.

In the nickel hydrometallurgical process, the separation of nickel and cobalt contained in an acidic aqueous solution is the most important technical element.
In general, separation of nickel and cobalt contained in an acidic aqueous solution is performed by a solvent extraction method using various organic extractants.

In the solvent extraction method for separating nickel and cobalt, phosphoric acid ester-based acid extractants such as D2EHPA (Di- (2-ethylhexyl) phosphoric acid) and amine-based amines such as TNOA (Tri-n-octylamine) are used as organic extractants. An extractant is used.
Both phosphate ester-based acid extractants and amine-based extractants have excellent nickel and cobalt separation performance. However, in general, when anions are sulfate ions, phosphate ester-based acid extractants are anionic chloride salts. In the case of a product ion, an amine-based extractant is used.

  By the way, in the case of a chloride aqueous solution having a sufficiently high chloride ion concentration in the aqueous solution and a chloride ion concentration of 200 g / L or more, cobalt forms chloro complex ions, but nickel does not form chloro complex ions. The amine-based extractant has a higher cobalt and nickel separation factor than the phosphate ester-based acidic extractant.

In addition, in the case of a phosphoric acid ester-based acidic extractant, protons are released from the extractant by extraction of metal ions, so that a neutralizer cost is required, and clad is often generated due to a change in pH.
This clad is a solid such as a metal hydroxide that stays and accumulates between the organic and aqueous phases in the oil / water separator, greatly impairing oil / water separation, an important technical element of solvent extraction. Is.

  The method for separating cobalt from an aqueous nickel chloride solution containing cobalt by an amine-based extractant is industrialized as a solvent extraction composed of an extraction stage, a washing stage, and a back-extraction stage using techniques as described below. ing.

As the extractant, primary amine (RNH ₂ ), secondary amine (R ₂ NH), or tertiary amine (R ₃ N) is used (R represents any saturated or unsaturated hydrocarbon group).
Such an amine-based extractant has the ability to extract metal chloro complex ions when activated by addition of hydrochloric acid, and has excellent nickel and cobalt separation characteristics.

In the extraction stage, metal species that form chloro complex ions such as Co, Cu, Zn, and Fe are extracted into the organic phase, and amines carrying the metal element chloro complex ions are generated.
However, since nickel does not form chloro complex ions, it remains in the extraction residue and is separated.

The next cleaning stage is installed if necessary.
In general, in the washing stage, the impurities contained in the entrainment in the organic phase after extraction, that is, in the fine water droplets suspended in the organic phase, are diluted and removed by the washing water.

In the method for separating nickel and cobalt by the amine-based extractant according to the present invention, the organic phase after extraction is usually washed using a back extract that is an aqueous cobalt chloride solution having a high purity.
In other words, by washing the organic phase after extraction with a high-purity cobalt chloride aqueous solution, the nickel chloride aqueous solution in the organic phase brought in as an entrainment from the extraction stage is diluted and replaced with the cobalt chloride aqueous solution. It plays the role of reducing the nickel concentration.
In addition, since the aqueous phase after washing becomes a cobalt chloride aqueous solution containing nickel, it is mixed with the extraction start solution and repeated in the extraction stage.

  In the back extraction stage, the organic phase after washing, that is, the amine carrying the cobalt chloro complex ion is brought into contact with a weakly acidic aqueous solution, thereby removing cobalt into the aqueous phase.

  The back extract obtained in this back extraction stage, that is, the aqueous cobalt chloride solution, is further treated with a treatment route different from that of nickel to remove impurities such as manganese, copper, and zinc. Commercialized as cobalt.

  By the way, the removal of a trace amount of nickel contained in the cobalt chloride aqueous solution can be carried out by removing and adsorbing cobalt, which is a main component, even if means such as neutralization in an oxidizing atmosphere, ion exchange or solvent extraction are used. Since it is an operation of extracting and leaving nickel, which is a trace impurity, in the aqueous solution, it cannot be implemented industrially.

On the other hand, a very small amount of nickel contained in the cobalt chloride aqueous solution contaminates electric cobalt in the electrowinning process and deteriorates the product quality.
Therefore, in the method of extracting cobalt from an aqueous solution of nickel chloride containing cobalt with an organic solvent composed of an amine-based extractant and a diluent, reducing the nickel concentration in the aqueous solution of cobalt chloride is the most important issue. Yes.

  As a means for obtaining an aqueous solution of cobalt chloride having a low nickel concentration, a method of increasing the amount of washing starting liquid, that is, the amount of back-extracted liquid is conceivable. If the amount of washing starting liquid is increased, cobalt to be treated in the extraction stage is considered. Since the amount of cobalt chloride recovered increases and the amount of cobalt chloride recovered decreases, the cobalt recovery efficiency in the solvent extraction step decreases, and the cobalt treatment capacity of the entire solvent extraction step decreases.

  Further, increasing the amount of the washing start solution means that the amount of the aqueous phase after washing repeated in the extraction stage is increased, and the chloride ion concentration in the extraction start solution is reduced. Therefore, the extraction rate of cobalt in the extraction stage is also lowered, and the cobalt concentration of the extraction residual liquid, that is, the nickel chloride aqueous solution is increased.

Therefore, there has been a demand for a method for cleaning the organic phase after extraction that can provide a cobalt chloride aqueous solution having a low nickel concentration without increasing the amount of the starting cleaning solution.
In order to solve the above problems, for example, in Patent Document 1, (a) the concentration of the amine-based extractant in the organic phase is 30 to 40% by volume, and (b) the cobalt extraction rate of the organic phase after extraction is 30 to 30%. 40%, (c) O / A ratio of washing stage (volume ratio of organic relative aqueous phase) is 10 to 14, and (d) cobalt concentration in washing starting liquid is 45 to 65 g / L, and solvent extraction is performed. A method of performing is disclosed.

  In the method disclosed in Patent Document 1, instead of increasing the concentration of the amine-based extractant in the organic phase, the ratio of the amine carrying the cobalt chloro complex ion in the amine-based extractant is decreased, thereby cleaning. In the stage, the cobalt in the organic phase is prevented from being back-extracted into the aqueous phase, and the cobalt concentration in the washing starting liquid is controlled to a low level, and the O / A ratio is controlled to a high level, whereby the extraction stage This is intended to reduce the amount of cobalt repeated.

  According to the above method, the amount of cobalt repeated in the extraction stage can be reduced without greatly increasing the nickel concentration of the back extract, that is, the aqueous solution of cobalt chloride.

  However, the nickel concentration in the obtained cobalt chloride aqueous solution is about 5 mg / L, and further improvement has been desired for the other problem of producing a low nickel concentration cobalt chloride aqueous solution.

JP 2011-006759 A

  In order to solve the above problems, the present invention provides a method for extracting cobalt from a nickel chloride aqueous solution containing cobalt with an organic solvent comprising an amine-based extractant and a diluent. An object of the present invention is to provide a method for producing an aqueous cobalt chloride solution that can be produced.

  In order to achieve the above-mentioned object, the present inventors have conducted researches focusing on the organic solvent cleaning method in the mixer tank. As a result, the O / A ratio (organic relative By reducing the volume ratio of the aqueous phase, it was found that an aqueous cobalt chloride solution having a lower nickel concentration than that of the prior art can be produced, and the present invention has been completed.

  The first invention of the present invention uses a counter-current multi-stage type extraction device, and extracts cobalt from an aqueous solution of nickel chloride containing cobalt using an organic solvent comprising an amine-based extractant and a diluent to extract cobalt from the aqueous solution of cobalt chloride. Of the aqueous solution of cobalt chloride in the solvent extraction method comprising the following three treatments of extraction stage, washing stage and back-extraction stage of (1) to (3): And the volume ratio of the organic relative aqueous phase in the mixer tank is 3.0 or less.

(1) An extraction stage in which cobalt is extracted from the nickel chloride aqueous solution containing cobalt into an organic phase to obtain a nickel chloride aqueous solution from which cobalt has been removed.
(2) A washing stage in which a part of the aqueous phase after back extraction is mixed and brought into contact with the organic phase from which cobalt has been extracted to remove nickel in the organic phase.
(3) A back extraction stage in which cobalt is removed from the washed organic phase with a weakly acidic aqueous solution to obtain an aqueous cobalt chloride solution.

  In the second invention of the present invention, the nickel concentration of the nickel chloride aqueous solution containing cobalt in the first invention is 140 to 240 g / L, the cobalt concentration is 3 to 10 g / L, and the cobalt concentration of the cobalt chloride aqueous solution is 60 to It is a manufacturing method of cobalt chloride aqueous solution characterized by being 80 g / L.

  According to a third aspect of the present invention, an organic solvent is constituted using a tertiary amine extractant as the amine extractant in the first and second inventions and an aromatic hydrocarbon as a diluent. It is a manufacturing method of cobalt chloride aqueous solution characterized by the concentration of an extractant in it being 10 to 40% by volume.

  According to a fourth aspect of the present invention, the tertiary amine extractant in the third aspect is tri-n-octylamine (TNOA) or tri-iso-octylamine (TIOA: Tri-i). -Octylamine), which is a method for producing an aqueous cobalt chloride solution.

  According to the method for producing an aqueous solution of cobalt chloride of the present invention, the amount of washing starting liquid is not increased as compared with the prior art. Therefore, it is possible to produce an aqueous cobalt chloride solution having a nickel concentration lower than that of the prior art without increasing the cobalt concentration, and thus the nickel content of the product electric cobalt can be reduced.

1 is a schematic flow sheet of a solvent extraction process according to the present invention. It is the figure which showed the relationship between O / A ratio in a washing | cleaning stage mixer tank, and Ni density | concentration in a water phase.

Below, the manufacturing method of the cobalt chloride aqueous solution of this invention is demonstrated in detail.
In the method for producing an aqueous cobalt chloride solution according to the present invention, cobalt is extracted from an aqueous nickel chloride solution containing cobalt from an aqueous solution containing an amine-based extractant and a diluent, using a countercurrent multi-stage extraction apparatus, A method for producing a cobalt chloride aqueous solution for producing a cobalt chloride aqueous solution, wherein the inside of the mixer tank of the washing stage in the solvent extraction method including the following three treatments is made an organic phase continuous, and the O / A ratio in the mixer tank, ie, organic The volume ratio of the relative aqueous phase is 3.0 or less.

(1) An extraction stage in which cobalt is extracted into an organic phase from a nickel chloride aqueous solution containing cobalt to obtain a nickel chloride aqueous solution from which cobalt has been removed.

(2) A washing stage in which a part of the aqueous phase after back extraction is mixed and brought into contact with the organic phase from which cobalt has been extracted to remove nickel in the organic phase.

(3) A back extraction stage in which cobalt is removed from the washed organic phase with a weakly acidic aqueous solution to obtain an aqueous cobalt chloride solution.

FIG. 1 shows a schematic flow sheet of a solvent extraction process according to the present invention.
Solvent extraction is performed in a countercurrent multi-stage system, and is composed of an extraction stage, a washing stage, and a back extraction stage.

  The number of extraction stages, washing stages, and back-extraction stages required depends on the composition of the extraction starting liquid, the extractant, and the extraction device. In general, however, the organic phase and the aqueous phase are reliably in contact with each other. In order to obtain the extraction result, it is preferable to use a plurality of stages.

The extractant used in the present invention is not particularly limited as long as it is an amine-based extractant, but a tertiary amine-based extractant is preferably used depending on its high reactivity and low solubility in water, and handling properties, cost, etc. In view of the above, it is more preferable to use TNOA (Tri-n-octylamine) or TIOA (Tri-i-octylamine).
As the diluent constituting the organic solvent used for the extraction by diluting the extractant, it is preferable to use an aromatic hydrocarbon because of its low solubility in water and good oil / water separation properties.

  In order to adjust the viscosity of the organic phase, the concentration of the extractant in the organic phase, that is, the mixture of the extractant and the diluent, is 10 to 40% by volume.

  Tertiary amine has the ability to extract metal chloro complex ions as shown in formula (2) and formula (2 ′) by adding hydrochloric acid and activating according to the following formula (1), and is excellent. It has the separation characteristics of nickel and cobalt.

M in the above formula (2) represents a metal species that forms a chloro complex ion such as Co, Cu, Zn, etc., but the form of the chloro complex ion differs depending on the valence of the metal ion. In accordance with the following formula (2 ′).
In the formula (1), formula (2), and formula (2 ′), “:” represents a lone pair of nitrogen atoms.

In the extraction stage, metal species that form chloro complex ions such as Co, Cu, Zn, and Fe are extracted into the organic phase by the reaction represented by the formula (2) or the formula (2 ′), and the metal element chloro An amine carrying complex ions is produced.
Since nickel does not form chloro complex ions, it remains in the extraction residual liquid and is separated.

  In the back extraction stage, the washed organic phase, that is, an amine carrying cobalt chloro complex ions is brought into contact with a weakly acidic aqueous solution, whereby cobalt is obtained according to the following formula (3), which is the reverse reaction of formula (2). Is released into the aqueous phase.

  Further, in the present invention, the composition of the nickel chloride aqueous solution containing cobalt used as the extraction starting liquid is not particularly limited, but it is preferable to use a nickel chloride aqueous solution obtained by leaching a nickel sulfide raw material, for example, A nickel chloride aqueous solution having a nickel concentration of 140 to 240 g / L and a cobalt concentration of 3 to 10 g / L can be used. In that case, in order to make the washing of the organic phase more effective and achieve the object of the present invention, the cobalt concentration of the aqueous cobalt chloride solution obtained as the back extract is preferably 60 to 80 g / L.

  In the washing stage, the entrainment in the organic phase after extraction, that is, impurities contained in fine water droplets suspended in the organic phase is diluted and removed by washing water, but the amine extraction according to the present invention is performed. In the method of separating nickel and cobalt with an agent, the organic phase after extraction is washed with a back extract solution in a highly pure cobalt chloride aqueous solution.

In other words, by washing the organic phase after extraction with high-purity cobalt chloride aqueous solution, the nickel chloride aqueous solution brought in as an entrainment from the extraction stage is diluted and replaced with high-purity cobalt chloride aqueous solution, so that the nickel concentration in the organic phase Reduce.
In addition, since the aqueous phase after washing becomes a cobalt chloride aqueous solution containing nickel, it is mixed with the extraction start solution and repeated in the extraction stage.

This cleaning stage has two problems as described above.
The first is to improve the cleaning efficiency when the organic phase after extraction is washed and the nickel chloride aqueous solution brought in as entrainment is diluted and replaced with a cobalt chloride aqueous solution.

  Second, increasing the aqueous phase flow rate in the cleaning stage improves the cleaning efficiency, but as a result, the amount of back extract, that is, the amount of cobalt chloride aqueous solution increases, reduces the amount of cobalt recovered as cobalt chloride. Thus, not only the cobalt recovery efficiency is reduced, but also the cobalt treatment capacity is lowered, and the chloride ion concentration of the back extract is low, which increases the back extract amount of cobalt in the cleaning stage.

Moreover, since the aqueous phase after washing is processed by mixing with the extraction start liquid, it is a problem of reducing the chloride ion concentration of the extraction start liquid and reducing the cobalt extraction rate in the extraction stage.
That is, there is a need for a technique that enhances cleaning without increasing the aqueous phase flow rate in the cleaning stage.

Therefore, the present invention is characterized in that the inside of the mixer tank of the washing stage is made continuous with an organic phase, and the O / A ratio in the mixer tank, that is, the volume ratio of the organic relative aqueous phase is made 3.0 or less.
Here, the organic phase continuity means a state in which water droplets are dispersed in the organic phase. Conversely, the continuous aqueous phase refers to a state where organic phase particles are dispersed in the aqueous phase.

  When the organic phase is continuous, binding of water droplets in the organic phase is promoted, so that the nickel concentration in the entrainment is greatly reduced to 0.1 g / L or less, and the entrainment is reduced. It is to do.

  On the other hand, when the aqueous phase is continuous, the entrainment in the organic phase and the aqueous phase are not sufficiently mixed and contacted, so the nickel concentration in the entrainment is a high value of 5 to 10 g / L.

Whether the organic phase is continuous or the aqueous phase is continuous can be easily determined by installing a conductivity meter in the mixer tank.
That is, the conductivity in the mixer tank rapidly increases when the organic phase is continuously changed to the aqueous phase.

On the contrary, when the water phase is continuously changed to the organic phase, the electrical conductivity in the mixer tank is rapidly lowered.
Therefore, the state of organic phase continuity can be easily maintained by managing the threshold value of conductivity.

  The O / A ratio is set to 3.0 or less in order to promote the bonding of water droplets in the organic phase, enhance washing, improve oil / water separation, and reduce entrainment in the organic phase. It is.

For example, when an aqueous nickel chloride solution obtained by leaching a nickel sulfide raw material as a starting extraction liquid is used, the organic flow rate after extraction is 1160 L / min, and the flow rate of the aqueous phase in the washing stage is 18 L / min.
Although the flow rate of the water phase in the washing stage is small, this is intended to reduce the amount of cobalt repetition described above and to prevent a decrease in the cobalt extraction rate in the extraction stage.
Here, considering the flow ratio, O / A is about 1160 ÷ 18 = 64, but in order to make the volume ratio in the mixer tank O / A 3.0 or less, the water after oil-water separation by recycle piping is used. The phase is self-circulated into the mixer tank.

  If a flow meter and a control valve are provided in the recycle piping, the O / A ratio in the mixer tank can be controlled to 3.0 or less relatively easily.

  The present invention will be further described below with reference to examples.

  In accordance with the flow sheet shown in FIG. 1, a solvent extraction apparatus comprising a three-stage extraction stage, a three-stage washing stage, and a three-stage back-extraction stage using a countercurrent multistage mixer settler is used. Solvent extraction operation was performed using an organic solvent containing 20% by volume of a certain tri-normal-octylamine (TNOA) and the remainder being 80% by volume of the aromatic hydrocarbon (Swazole 1800 manufactured by Maruzen Petrochemical Co., Ltd.) as a diluent. It was.

  The O / A in the mixer tank is set to 2.4, the extraction starting liquid flow rate is 851 L / min, the organic flow rate is 1035 L / min, the flow rate of the water phase in the wash stage is 17 L / min, and the continuous phase in the wash stage mixer tank is The operation was carried out as a continuous organic phase.

The composition of the extraction starting solution (mixed aqueous solution of nickel chloride and cobalt chloride) has a nickel concentration of 198 g / L and a cobalt concentration of 6.0 g / L, and the cobalt concentration of the back extract (cobalt chloride aqueous solution) is 62 g / L. Met.
The results are shown in Table 1. The Ni concentration in the back extract was 0.97 mg / L, the organic entrainment was 992 ppm (volume ratio), and the Co concentration in the cleaning final solution was 92 g / L.

In the same solvent extraction apparatus as in Example 1, a solvent extraction operation was performed using an organic solvent composed of an extractant and a diluent having the same component composition.
The O / A in the mixer tank is set to 2.0, the extraction start liquid flow rate is 850 L / min, the organic flow rate is 1126 L / min, the flow rate of the water phase in the wash stage is 19 L / min, and the continuous phase in the wash stage mixer tank is The operation was carried out as a continuous organic phase.

The composition of the extraction starting solution (mixed aqueous solution of nickel chloride and cobalt chloride) is a nickel concentration of 194 g / L, a cobalt concentration of 6.0 g / L, and the cobalt concentration of the back extract (cobalt chloride aqueous solution) is 62 g / L. Met.
The results are shown in Table 1. The Ni concentration in the back extract was 0.33 mg / L, the organic entrainment was 427 ppm (volume ratio), and the Co concentration in the washing final solution was 90 g / L.

Using the same solvent extraction apparatus as in Example 1, a solvent extraction operation was performed using an organic solvent composed of an extractant and a diluent having the same component composition.
The O / A in the mixer tank is 1.2, the extraction starting liquid flow rate is 891 L / min, the organic flow rate is 1110 L / min, the flow rate of the water phase in the wash stage is 19 L / min, and the continuous phase in the wash stage mixer tank is The operation was carried out as a continuous organic phase.

  The composition of the extraction starting solution (mixed aqueous solution of nickel chloride and cobalt chloride) is a nickel concentration of 192 g / L and a cobalt concentration of 6.5 g / L, and the cobalt concentration of the back extract (cobalt chloride aqueous solution) is 60 g / L. Met.

  The results are shown in Table 1. The Ni concentration in the back extract was 0.28 mg / L, the organic entrainment was 368 ppm (volume ratio), and the Co concentration in the cleaning final solution was 89 g / L.

Using the same solvent extraction apparatus as in Example 1, a solvent extraction operation was performed using an organic solvent composed of an extractant and a diluent having the same component composition.
The O / A in the mixer tank is set to 2.8, the extraction starting liquid flow rate is 879 L / min, the organic flow rate is 1095 L / min, the flow rate of the water phase of the washing stage is 18 L / min, and the continuous phase in the washing stage mixer tank is The operation was carried out as a continuous organic phase.

  The composition of the extraction starting solution (mixed aqueous solution of nickel chloride and cobalt chloride) is a nickel concentration of 197 g / L and a cobalt concentration of 6.2 g / L, and the cobalt concentration of the back extract (cobalt chloride aqueous solution) is 65 g / L. Met.

  The results are shown in Table 1. The Ni concentration in the back extract was 1.27 mg / L, the organic entrainment was 1341 ppm (volume ratio), and the Co concentration in the cleaning final solution was 94 g / L.

(Comparative Example 1)
Using the same solvent extraction apparatus as in Example 1, a solvent extraction operation was performed using an organic solvent composed of an extractant and a diluent having the same component composition.
The O / A in the mixer tank is 3.1, the extraction starting liquid flow rate is 910 L / min, the organic flow rate is 1185 L / min, the flow rate of the water phase in the wash stage is 20 L / min, and the continuous phase in the wash stage mixer tank is The operation was carried out as a continuous organic phase.

  The composition of the extraction starting solution (mixed aqueous solution of nickel chloride and cobalt chloride) is a nickel concentration of 186 g / L and a cobalt concentration of 6.8 g / L, and the cobalt concentration of the back extract (cobalt chloride aqueous solution) is 60 g / L. Met.

  The results are shown in Table 1. The Ni concentration in the back extract was 2.59 mg / L, the organic entrainment was 3116 ppm (volume ratio), and the Co concentration in the cleaning final solution was 88 g / L.

(Comparative Example 2)
In the same solvent extraction apparatus as in Example 1, a solvent extraction operation was performed using an organic solvent composed of an extractant and a diluent having the same component composition.
The O / A in the mixer tank is 0.6, the extraction starting liquid flow rate is 451 L / min, the organic flow rate is 633 L / min, the water phase flow rate in the washing stage is 13 L / min, and the continuous phase in the washing stage mixer tank is The operation was carried out as a continuous water phase.

  The composition of the extraction starting solution (mixed aqueous solution of nickel chloride and cobalt chloride) is a nickel concentration of 182 g / L and a cobalt concentration of 6.0 g / L, and the cobalt concentration of the back extract (cobalt chloride aqueous solution) is 58 g / L. Met.

  The results are shown in Table 1. The Ni concentration in the back extract was 16.4 mg / L, and the Co concentration in the washing final solution was 89 g / L.

FIG. 2 shows the relationship between the O / A ratio in the mixer tank and the Ni concentration in the back extract with respect to the results of Examples 1 to 4, Comparative Example 1, and Comparative Example 2.
As a result of managing the continuous phase and O / A ratio in the mixer tank, the concentration of Ni in the aqueous phase is reduced by reducing the O / A ratio while maintaining the organic phase in the washing stage mixer tank as shown in FIG. Could be reduced.
However, if the O / A ratio is lowered below 1.0, the aqueous phase becomes continuous, so this O / A ratio 1.0 becomes a critical value, and the nickel concentration starts to increase below 1.0. Become.

In addition, in any of Examples 1-4 and Comparative Examples 1-2, the amount of washing | cleaning final liquid (flow volume of the water phase of a washing | cleaning stage) has not increased.
Further, the cobalt concentration in the cleaning final solution is around 90 g / L, and the repetition amount of cobalt as the cleaning final solution does not increase.

Claims (4)

A method for producing an aqueous cobalt chloride solution using a counter-current multistage extraction device and using an organic solvent comprising an amine-based extractant and a diluent from an aqueous nickel chloride solution containing cobalt to produce an aqueous cobalt chloride solution by solvent extraction of cobalt. The mixer tank (stirring tank) in the washing stage in the solvent extraction method including the following three treatments of extraction stage, washing stage and back-extraction stage of (1) to (3) is used as a continuous organic phase, and the mixer A method for producing an aqueous cobalt chloride solution, wherein the volume ratio of the organic relative aqueous phase in the tank is 3.0 or less.
(Record)
(1) An extraction stage in which cobalt is extracted from the nickel chloride aqueous solution containing cobalt into an organic phase to obtain a nickel chloride aqueous solution from which cobalt has been removed.
(2) A washing stage in which a part of the aqueous phase after back extraction is mixed and brought into contact with the organic phase from which cobalt has been extracted to remove nickel in the organic phase.
(3) A back extraction stage in which cobalt is removed from the washed organic phase with a weakly acidic aqueous solution to obtain an aqueous cobalt chloride solution.   The nickel concentration of the nickel chloride aqueous solution containing cobalt is 140 to 240 g / L, the cobalt concentration is 3 to 10 g / L, and the cobalt concentration of the cobalt chloride aqueous solution is 60 to 80 g / L. 2. A method for producing a cobalt chloride aqueous solution according to 1.   A tertiary amine extractant is used as the amine extractant, an aromatic hydrocarbon is used as a diluent, and an organic solvent is formed. The extractant concentration in the organic solvent is 10 to 40% by volume. The method for producing an aqueous cobalt chloride solution according to claim 1 or 2.   The method for producing an aqueous cobalt chloride solution according to claim 3, wherein the tertiary amine-based extractant is tri-normal-octylamine (TNOA) or tri-iso-octylamine (TIOA).

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