JP2020084198A - Production method of cobalt chloride aqueous solution - Google Patents

Abstract

To provide a method capable of stably producing cobalt chloride aqueous solution with lower nickel concentration, in a production method of cobalt chloride aqueous solution including a step of a solvent extraction of cobalt by an amine-based extractant from nickel chloride aqueous solution containing the cobalt.SOLUTION: A method is for producing cobalt chloride aqueous solution: by utilizing a mixer-settler type solvent extractor; by a solvent extraction method using an organic solvent containing a tertiary amine at an organic phase; and by separating and recovering cobalt from nickel chloride aqueous solution containing the cobalt. The method includes a solvent extraction process composed of: (1) an extraction stage of extracting the cobalt; (2) a cleaning stage of removing nickel contained in the organic phase; (3) a back extraction stage of detaching the cobalt in the organic phase; and (4) a reproduction stage. Then, at least only part of the organic phase after back extraction at the back extraction stage is transported to the reproduction stage to apply a neutralization treatment and the balance of the organic phase is directly transported to the extraction stage.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for producing an aqueous cobalt chloride solution by separating and recovering cobalt from an aqueous nickel chloride solution containing cobalt by solvent extraction of the cobalt with an organic solvent containing an amine-based extractant.

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

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

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

Further, in the case of a phosphoric acid ester-based acidic extractant, hydrogen ions are released from the extractant by extraction of metal ions, so that a neutralizer cost is required, and a clad often occurs due to a change in pH. The clad is a solid such as metal hydroxide, which stays and accumulates between the organic phase and the aqueous phase in the oil-water separator, which greatly impedes oil-water separation, which is an important technical element of solvent extraction. It will be done.

A method for separating cobalt from an aqueous nickel chloride solution containing cobalt with an amine-based extractant is a solvent extraction process comprising an extraction stage, a washing stage, and a back extraction stage, using the technique described below. It is industrialized.

As the amine-based extractant, a primary amine (RNH ₂ ), a secondary amine (R ₂ NH), and a tertiary amine (R ₃ N) are used (wherein R is any saturated or unsaturated hydrocarbon group). Represent). Such an amine-based extractant has a capability of extracting a metal chloro complex ion when activated by addition of hydrochloric acid, and has an excellent nickel-cobalt separation property.

Specifically, in the extraction stage, the metal species forming chloro complex ions such as Co, Cu, Zn, and Fe contained in the nickel chloride aqueous solution are extracted into the organic phase containing the amine-based extractant, and the chloro complex of the metal element is extracted. An amine bearing ions is produced. On the other hand, nickel in the nickel chloride aqueous solution does not form a chloro complex ion and thus remains in the extraction residual liquid and is separated.

The next washing stage is installed if necessary. Generally, in the washing stage, impurities contained in the entrainment (fine aqueous phase droplets suspended in the organic phase) in the organic phase after extraction are diluted and removed by the washing water.

In the washing stage, usually, the organic phase after extraction is washed with a high-purity aqueous solution of cobalt chloride which is a back-extract produced in the next back-extraction stage. In other words, by washing the organic phase after extraction with a 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 to reduce the nickel concentration in the organic phase. Lower. The aqueous phase washed and removed after the washing is a nickel chloride-containing cobalt chloride aqueous solution, and thus is mixed with the initial solution for extraction and repeated in the extraction stage.

Next, in the back extraction stage, the organic phase after washing, that is, the amine carrying the chloro complex ion of cobalt is brought into contact with a weakly acidic aqueous solution (dilute hydrochloric acid, etc.) to remove cobalt into the aqueous phase. To do.

The back extraction liquid obtained in the back extraction stage, that is, the aqueous solution of cobalt chloride, is subjected to a further cleaning treatment (treatment for removing impurities such as manganese, copper, zinc) by a treatment route different from nickel, and then, It is commercialized as electric cobalt by electrowinning.

By the way, for the removal of a trace amount of nickel contained in an aqueous solution of cobalt chloride, even if a means such as neutralization in an oxidizing atmosphere, ion exchange or solvent extraction is used, precipitation removal, adsorption or extraction for cobalt which is a main component is carried out. It is impossible to industrially carry out the above because it is an operation of leaving nickel, which is a trace impurity, in the aqueous solution.

On the other hand, a very small amount of nickel contained in the aqueous solution of cobalt chloride is a factor that deteriorates the product quality by contaminating the electric cobalt produced in the electrolytic extraction process. Therefore, in the method for producing an aqueous cobalt chloride solution by solvent-extracting cobalt from an aqueous nickel chloride solution containing cobalt with an organic solvent containing an amine-based extractant, the nickel concentration in the obtained aqueous cobalt chloride solution is effectively reduced. This is an important technical issue.

In order to solve such a problem, for example, in Patent Document 1, the inside of the mixer tank (stirring tank) in the washing stage is made to be an organic phase continuous, and the volume ratio of the organic relative aqueous phase in the mixer tank is set to 3.0 or less. A method of performing solvent extraction is disclosed. According to the method disclosed in Patent Document 1, the binding of water droplets in the organic phase is promoted by increasing the amount of the cleaning start liquid to make the aqueous phase continuous, instead of making the aqueous phase continuous. As the nickel concentration in the entrainment decreases and the entrainment itself decreases, the cleaning efficiency can be improved.

However, even if the cleaning efficiency in the mixer tank of the cleaning stage is improved, if the oil/water separation efficiency in the settler section (oil/water separation tank) decreases, entrainment in the organic phase increases, so nickel cobalt in the cobalt chloride aqueous solution is increased. The concentration cannot be reduced. In particular, when the chemical and physical properties of the organic phase are changed so that the fine aqueous phase droplets in the organic phase are stably present, both the washing efficiency and the oil-water separation efficiency decrease, and cobalt chloride The nickel concentration in the aqueous solution may suddenly rise to about 1000 times the normal concentration.

Further, for example, in Patent Document 2, after adjusting the redox potential of an aqueous solution of nickel chloride in a strongly oxidizing atmosphere containing a plurality of metal ions to 500 mV (Ag/AgCl electrode reference) or less by a reducing agent, the nickel chloride is adjusted. A method in which an aqueous solution is used as a starting solution for extraction and subjected to a solvent extraction treatment is disclosed.

However, the method disclosed in Patent Document 2 is intended to prevent deterioration of the tertiary amine compound that is an extractant, and does not prevent deterioration of oil-water separation efficiency in the washing stage.

JP, 2005-183267, A JP, 2005-209582, A

The present invention has been proposed in view of such circumstances, in a method for producing an aqueous cobalt chloride solution by solvent extraction of cobalt from an aqueous nickel chloride solution containing cobalt with an organic solvent containing an amine-based extractant, It is an object of the present invention to provide a method capable of stably producing a cobalt chloride aqueous solution having a low nickel concentration.

The present inventors have discovered that during the treatment in the solvent extraction step, an alkylamine oxide, which is an amphoteric surfactant substance derived from an extractant, is produced, and the alkylamine oxide is accumulated in the organic phase. It was found that entrainment in an organic phase containing an aqueous solution of nickel chloride forms stable reverse micelles, and as a result, the cleaning efficiency of entrainment decreases and the concentration of nickel in the aqueous solution of cobalt chloride increases. Therefore, when the cause of generation of alkylamine oxide was examined, it was found that the organic phase after the back extraction was subjected to a neutralization treatment with an alkali (treatment under high pH conditions). By controlling the amount of the organic phase used for the neutralization treatment with alkali to reduce the load of the neutralization treatment in the system, the production of alkylamine oxide is suppressed and the deterioration of the entrainment cleaning efficiency is prevented. The inventors have found that they can be achieved and have completed the present invention.

[1] A first invention of the present invention is to use a mixer-settler type solvent extraction device and a solvent extraction method using an organic solvent containing a tertiary amine as an extractant in an organic phase to obtain an aqueous solution of nickel chloride containing cobalt. A method for producing an aqueous cobalt chloride solution by separating and recovering cobalt, comprising: (1) an extraction stage for extracting cobalt from the aqueous nickel chloride solution into the organic phase; and (2) the cobalt obtained in the extraction stage. A washing stage for removing nickel contained in the organic phase by mixing a part of the aqueous phase after the back extraction with the containing organic phase, and (3) the organic phase after the washing in the washing stage (the organic phase after washing). ) Is contacted with a weakly acidic aqueous solution as a back-extracting agent to desorb cobalt in the organic phase to obtain an aqueous phase of a cobalt chloride aqueous solution, and (4) a reverse extraction step in the back-extracting step. The organic phase after extraction is subjected to a neutralization treatment with an alkali, and then the neutralized organic phase is subjected to a hydrochloric acid addition treatment with an aqueous hydrochloric acid solution to obtain a regenerated organic phase, which is repeatedly regenerated to the extraction stage. And a solvent extraction step constituted by a stage, wherein at least a part of the organic phase after the back extraction in the back extraction stage is transferred to the regeneration stage and subjected to the neutralization treatment, and the remaining It is a method for producing an aqueous solution of cobalt chloride, in which the organic phase is directly transferred to the extraction stage.

[2] The second invention of the present invention is the same as the first invention, wherein the volume of the organic phase after the back extraction in the back extraction stage is 1/300 or more and 1/30 or less. It is a method for producing an aqueous cobalt chloride solution, in which the organic phase is transferred to the regeneration stage and subjected to the neutralization treatment, and the remaining organic phase is transferred to the extraction stage.

[3] A third invention of the present invention is the method for producing an aqueous cobalt chloride solution according to the first or second invention, wherein the neutralization treatment in the regeneration stage is carried out under the condition of pH 13 or more with addition of alkali. is there.

According to the method of the present invention, it is possible to prevent a decrease in the cleaning efficiency of the entrainment containing nickel in the cleaning stage and to stably manufacture a cobalt chloride aqueous solution having a low nickel concentration.

It is a flowchart which shows an example of the flow of a solvent extraction process. It is a schematic diagram for demonstrating the structure of a mixer-settler type solvent extraction apparatus. It is a figure for demonstrating the presumed mechanism which alkylamine oxide produces|generates from the tertiary amine of an extractant. It is a graph which shows the result of the verification test of the alkylamine oxide formation based on the neutralization process in highly alkaline conditions. FIG. 3 is a graph showing the relationship between the content of heptanoic acid in the organic phase after the activation treatment and the content of entrainment in the organic phase after extraction (degree of nickel content). It is a figure for demonstrating the production mechanism of the aliphatic monocarboxylic acid from an amine type extractant (tertiary amine).

Hereinafter, specific embodiments of the present invention will be described in detail. The present invention is not limited to the following embodiments, and various modifications can be made without changing the gist of the present invention. In this specification, the notation “X to Y” (X and Y are arbitrary numerical values) means “X or more and Y or less”.

<<1. Method for producing cobalt chloride aqueous solution (solvent extraction step)>>
The method for producing an aqueous cobalt chloride solution according to the present invention uses a mixer-settler type solvent extraction device and a solvent extraction method using an organic solvent containing a tertiary amine as an extractant in an organic phase to produce a cobalt chloride-containing nickel chloride aqueous solution. This is a method including a step of separating and recovering cobalt (solvent extraction step).

FIG. 1 is a flow chart showing an example of the flow of a solvent extraction process. As shown in FIG. 1, in the solvent extraction step, an extraction stage for extracting cobalt from an aqueous nickel chloride solution containing cobalt (extraction initial solution) into an organic phase containing an extractant, and washing nickel in the organic phase containing cobalt are performed. It has a washing stage for removal and a back-extraction stage for contacting the organic phase after washing with a weakly acidic aqueous solution to desorb cobalt in the organic phase to obtain an aqueous phase of the aqueous cobalt chloride solution. It also has a regeneration stage in which the organic phase after back extraction is regenerated and repeated in the extraction stage.

The number of extraction stages, washing stages, and back extraction stages is determined by the composition of the extraction starter solution, the type of extractant, the structure of the extraction device, etc., but generally the contact between the organic phase and the aqueous phase is From the viewpoint of surely performing and obtaining a good extraction result, it is preferable that each stage has a plurality of stages.

<Extraction stage>
In the extraction stage, cobalt is extracted from an aqueous nickel chloride solution containing cobalt, which is the starting solution for extraction, into an organic phase composed of an organic solvent containing an extractant.

The extractant is not particularly limited as long as it is an amine-based extractant. Among them, it is preferable to use a tertiary amine-based extractant from the viewpoint of high reactivity and low solubility in water. Considering handleability and price, TNOA (Tri-n-octylamine) or TIOA (Tria) is used. It is more preferable to use -i-octylamine). The organic solvent that constitutes the organic phase is obtained by diluting such an extractant with a diluent. As the diluent constituting the organic solvent, it is preferable to use an aromatic hydrocarbon from the viewpoint of low solubility in water and good oil-water separability. The concentration of the extractant in the mixture of the extractant and the diluent (organic phase) is preferably adjusted appropriately according to the desired viscosity range of the organic phase, but is, for example, in the range of 10 to 40% by volume. be able to.

The tertiary amine as an extractant is activated by the addition of hydrochloric acid as shown in the following formula [i] to extract metal chloro complex ion as shown in formula [ii] and formula [iii]. Possesses and has excellent nickel-cobalt separation properties.

R ₃ N:+HCl→R ₃ N:HCl... [i]
^{_{2R 3 N: HCl + MCl 4}} 2- → (R 3 N: H) 2MCl 4 + 2Cl - ··· [ii]
_{R 3 N: HCl + MCl 4} - → R 3 N: HMCl 4 + Cl - ··· [iii]

M in the above formula [ii] represents a metal species that forms a chloro complex ion such as Co, Cu, and Zn, but since the form of the chloro complex ion differs depending on the valence of the metal ion, for example, in the case of trivalent Follows the formula [iii] below. In addition, “:” in the formulas [i] to [iii] represents an unshared electron pair of a nitrogen atom.

In the extraction stage, the metal species forming chloro complex ions such as Co, Cu, Zn, and Fe are extracted into the organic phase by the reactions represented by the formulas [ii] and [iii], and the chloro complex ions of the metal elements are extracted. A supported amine is produced. Since nickel in the initial solution for extraction does not form a chloro complex ion, it remains in the residual solution for extraction and is separated.

The composition of the nickel chloride aqueous solution containing cobalt which is the initial solution for extraction is not particularly limited, but it is preferable to use the nickel chloride aqueous solution obtained by leaching the nickel sulfide raw material with chlorine, for example, the nickel concentration is 140 to 240 g. /L, a nickel chloride aqueous solution having a cobalt concentration of 3 to 10 g/L can be used. The nickel chloride aqueous solution obtained by leaching the nickel sulfide raw material with chlorine contains copper, zinc, iron, etc. in addition to nickel and cobalt. As described above, copper, zinc, and iron are metal species that form chloro complex ions in a solution containing chloride ions, and thus are extracted into the organic phase together with cobalt.

Now, the solvent extraction process in the extraction stage is performed using a mixer-settler type solvent extraction device. In addition, the treatment using the mixer-settler type solvent extraction device is similarly performed in the washing stage and the back extraction stage described later.

FIG. 2 is a schematic diagram for explaining the configuration of the mixer-settler type solvent extraction device. Note that the schematic diagram of 2 is an example of the case used for the solvent extraction process in the extraction stage. The mixer-settler type solvent extraction device 1 is a countercurrent multi-stage solvent extraction device and includes a mixer part (extraction part) 11, a settler part (stationary part) 12, and a discharge part 13. The embodiment shown in FIG. 2 shows a specific example of the mixer-settler type solvent extraction device, and the configuration is not limited to this.

In the mixer section 11, the aqueous phase and the organic phase are charged, and the extraction target is transferred to the organic phase and extracted by contact mixing of the aqueous phase and the organic phase. For example, in the treatment in the extraction stage, an aqueous nickel chloride solution (aqueous phase) containing cobalt, which is the starting solution for the extraction, and an organic solvent (organic phase) containing an extractant are charged, and the aqueous phase and the organic phase are subjected to contact mixing. As a result, cobalt, which is the object of extraction, is transferred to the organic phase and extracted. The mixer section 11 has, for example, a water phase charging port 11a and an organic phase charging port 11b, and the water phase and the organic phase are charged into the mixer section 11 (mixer tank) through the charging ports 11a and 11b. It

The mixer unit 11 also includes a stirring device 20 including, for example, a stirring shaft 20a and a stirring blade 20b. In the mixer section 11, the liquid of the mixed phase in which the water phase and the organic phase are mixed is efficiently stirred by the stirring force of the stirring device 20. The mixed and mixed liquid of the mixed phase overflows, flows through the gutter 14, and moves to the next settler unit 12.

In the settler section 12, the mixed phase obtained by mixing the aqueous phase and the organic phase in the mixer section 11 is allowed to stand, and the aqueous phase and the organic phase are phase-separated by the difference in specific gravity. For example, in the treatment in the extraction stage, the mixed phase of the aqueous phase of the nickel chloride aqueous solution and the organic phase composed of the organic solvent from which cobalt is extracted is phase-separated in the settler section 12 due to the difference in specific gravity.

In the settler portion 12, the aqueous phase and the organic phase are phase-separated, and the aqueous phase is separated into the lower layer and the organic phase is separated into the upper layer with the oil-water interface as a boundary.

In the discharge part 13, the water phase and the organic phase separated in the settler part 12 are separated into oil and water and discharged so as not to be mixed. The discharge part 13 is provided with a partition wall 13w which is separated from the settler part 12, and the lower end of the partition wall 13w whose lower end is opened is the aqueous phase that has been phase-separated in the settler part 12 to form a lower layer. Discharged from. Further, the organic phase that has been phase-separated in the settler section 12 to form the upper layer overflows above the partition wall 13w and is transferred to the discharge section 13.

For example, in the treatment in the extraction stage, the aqueous phase composed of the nickel chloride aqueous solution that has constituted the lower layer in the settler section 12 is discharged from the lower portion of the partition wall 13w. On the other hand, the organic phase made of the organic solvent containing cobalt, which has constituted the upper layer in the settler section 12, overflows the upper portion of the partition wall 13w and is transferred to the discharge section 13. The organic phase discharged to the discharge part 13 is discharged through the organic discharge port and transferred to the next stage (washing stage).

Here, in the solvent extraction process in the extraction stage, as schematically shown as a partially enlarged view (“Z”) in FIG. 2, fine droplets of an aqueous phase containing an aqueous nickel chloride solution in the organic phase ( Entrainment) becomes suspended. The nickel thus incorporated in the organic phase in the form of entrainment is washed away in the next washing stage.

<Washing stage>
In the washing stage, the entrainment in the extracted organic phase is diluted and removed with washing water. In other words, by washing the organic phase after extraction, the nickel chloride aqueous solution brought in as an entrainment from the extraction stage is diluted and replaced with washing water to reduce the nickel concentration in the organic phase. Note that, as described above, the treatment in the washing stage is also performed using the mixer-settler type solvent extraction device as schematically shown in FIG. 2, and the organic phase from which cobalt has been extracted and the washing water (aqueous phase) Are contact mixed to wash away the entrainment.

In this washing stage, a part of the aqueous phase after the back extraction in the next back extraction stage, that is, the aqueous solution of cobalt chloride to be back-extracted (back extraction liquid) is used as the washing liquid. Since the aqueous phase after washing becomes an aqueous cobalt chloride solution containing nickel contained in the entrainment, it is mixed with the initial solution for extraction and repeated in the extraction stage.

Here, in the treatment in the washing stage, it is important to prevent the efficiency of washing and removing the nickel chloride aqueous solution brought in as entrainment from decreasing and further improving it. If the cleaning efficiency of the entrainment is low, nickel is extracted together with cobalt into the back extraction liquid in the next back extraction stage, and an aqueous cobalt chloride solution containing nickel is produced. The small amount of nickel contained in the aqueous solution of cobalt chloride contaminates the electric cobalt produced in the electrowinning process and causes deterioration of product quality. Therefore, it is required to prevent the reduction of the cleaning efficiency of the entrainment containing nickel in the cleaning stage and to stably manufacture the cobalt chloride aqueous solution having a low nickel concentration.

It is also considered that the cleaning efficiency can be improved by increasing the flow rate of the aqueous phase in the cleaning stage. However, in that case, the repeating amount of the back extraction liquid (cobalt chloride aqueous solution) used as the washing water increases, so that the amount of cobalt recovered as cobalt chloride decreases and the cobalt recovery efficiency decreases. Further, not only the cobalt treatment capacity is lowered, but also the chloride ion concentration of the back extraction liquid is low, so that the back extraction amount of cobalt in the washing stage is increased. From this, it is required to effectively wash and remove the entrainment without increasing the flow rate of the aqueous phase (wash water) in the wash stage.

<Back extraction stage>
In the back-extraction stage, the organic phase after washing (the organic phase after washing) is brought into contact with a weakly acidic aqueous solution such as dilute hydrochloric acid as a back-extracting agent, so that the cobalt carrying the chloro complex ion of cobalt in the organic phase can Is removed to obtain an aqueous phase of cobalt chloride aqueous solution.

In the back extraction stage, cobalt is desorbed into the aqueous phase according to the following formula [iv] which is a reverse reaction of the above formula [ii]. As a result, an aqueous cobalt chloride solution from which nickel has been separated is obtained.
(R ₃ N:H) 2CoCl ₄ →2R ₃ N:HCl+CoCl ₂ ... [iv]

As described above, the treatment in the back extraction stage is also performed using the mixer-settler type solvent extraction device as schematically shown in FIG. Specifically, after washing, the organic phase and the weakly acidic aqueous solution (aqueous phase) are contact-mixed in the mixer section, and cobalt in the organic phase is distributed to the aqueous phase. Then, by leaving it to stand in the settler section, the organic phase and the aqueous phase consisting of the aqueous cobalt chloride solution are separated.

<Play stage>
In the regeneration stage, a treatment for regenerating the organic phase after the back extraction in the back extraction stage is performed, and the process is repeated as the organic phase containing the extractant used in the extraction stage. Specifically, in the regeneration stage, the organic phase after back extraction is subjected to a neutralization treatment with an alkali, and then the organic phase after the neutralization treatment is subjected to a hydrochloric acid addition treatment with an aqueous hydrochloric acid solution to remove the organic phase after regeneration. Obtain and repeat for extraction stage.

(Neutralization process)
As described above, in the extraction stage, impurities such as zinc, iron and copper are extracted into the organic phase together with cobalt. The extracted cobalt is back-extracted into the aqueous phase in the back-extraction stage, but the impurities (zinc, iron, copper) remain in the organic phase without being back-extracted. However, if the concentration of impurities in the organic phase rises and such an organic phase is repeated in the extraction stage, the amount of cobalt extracted in the extraction stage may decrease and impurities may elute into the nickel chloride solution or cobalt chloride solution. There is a nature. Therefore, the organic phase after the back extraction is neutralized with an alkali to remove impurities such as zinc, iron and copper.

Specifically, in the neutralization treatment using an alkali, an aqueous alkaline solution is added to an organic phase containing an amine carrying a chloro complex ion of a metal element (impurity element such as zinc, iron and copper) produced from the back extraction stage. Add and mix. As a result, an organic phase from which the metal element is desorbed, a neutralized precipitate of the metal element, and an aqueous phase are formed. Then, the organic phase, the neutralized precipitate, and the aqueous phase are subjected to oil-water separation to separate the organic phase consisting of the supernatant of the organic phase and free of the neutralized precipitate.

The alkali is not particularly limited, but it is preferable to use an aqueous solution of sodium hydroxide. It is also preferable to use an alkali such as an aqueous solution of sodium hydroxide under the conditions of pH 9 or higher, preferably pH 10 or higher, more preferably pH 13 or higher.

The neutralization treatment in this regeneration stage is performed in the neutralization treatment tank.

(Activation process)
In the activation treatment, the neutralized organic phase is subjected to a hydrochloric acid addition treatment with an aqueous hydrochloric acid solution to obtain a regenerated organic phase. The organic phase obtained through the neutralization treatment with alkali was a clear organic phase from which impurity elements such as zinc, iron, and copper were desorbed, and the neutralized precipitate was not mixed, and thus the organic phase was obtained. It is activated (regenerated) by adding hydrochloric acid to the organic phase and can be reused in the extraction stage. In addition, hydrochloric acid is added and activated as shown in the above formula [i]. In the present specification, the activation treatment is also referred to as “hydrochloric acid addition treatment”.

The hydrochloric acid addition treatment in this regeneration stage is performed in a hydrochloric acid addition treatment tank.

<<2. Entrainment cleaning failure in the cleaning stage ≫
<2-1. Poor cleaning due to alkylamine oxide formation>
As described above, in the method for producing an aqueous cobalt chloride solution, in the cleaning process in the cleaning step of the solvent extraction step, it is possible to prevent a decrease in the efficiency of cleaning and removing the aqueous nickel chloride solution brought into the organic phase as entrainment (cleaning efficiency). Is important. If the cleaning efficiency of the entrainment is low, nickel will be extracted with cobalt in the back extraction liquid in the next back extraction stage, and a cobalt chloride aqueous solution containing nickel will be generated, which will be obtained through the electrolysis step of the next step. Deteriorate the quality of electric cobalt products.

As a result of repeated studies on the reduction of the cleaning efficiency of the entrainment in the cleaning stage (cleaning failure), the present inventors have found that the surface-active substances in the solvent extraction process (extraction stage, washing stage, back-extraction stage, and regeneration stage). It was found that the cause was that the surfactant substance was generated and accumulated in the system.

Specifically, it is speculated that the surface-active substance is an alkylamine oxide which is an amphoteric surface-active substance. When the alkylamine oxide, which is an amphoteric surface active substance, is accumulated in the system and reaches a certain value, the alkylamine oxide causes fine water droplets constituting entrainment to form a stable reverse micelle. For example, in the case of an emulsion having a size of more than 1000 nm, since it has a relatively unstable form, it can be easily removed by causing physical destruction by washing with washing water. On the other hand, in the case of reverse micelles having a size of about 1000 nm or less (1 to 1000 nm), since they have an extremely stable form, physical destruction due to washing cannot occur. As a result, it is considered that the cleaning efficiency of the entrainment decreases, that is, cleaning failure occurs.

Alkylamine oxide is a decomposition product derived from an amine-based extractant (tertiary amine) used as an extractant in the extraction stage. FIG. 3 is a diagram (chemical reaction formula) for explaining a presumed mechanism in which an alkylamine oxide is produced from a tertiary amine that is an extractant. As shown in FIG. 3, one of the reasons why the alkylamine oxide is produced is considered to be that the tertiary amine, which is an extractant, is oxidatively decomposed by an oxide (oxidant) mainly composed of air. .. In addition, it is considered that the organic phase containing the tertiary amine in the regeneration stage is neutralized under highly alkaline conditions. When the tertiary amine is TNOA (tri-n-octylamine), n-octylamine oxide is produced.

(Verification of alkylamine oxide formation based on oxidative decomposition by air)
Here, the present inventors conducted positive air bubbling in the neutralization treatment using the organic phase obtained through the back extraction stage, and changed the alkylamine oxide (TNOA oxide) concentration when the bubbling time was changed. A test to measure was performed. In the neutralization treatment, the treatment was performed under the condition of pH 13 using an aqueous sodium hydroxide solution. Further, the concentration of TNOA oxide contained in the organic phase before the neutralization treatment was measured and found to be less than the detection lower limit of 5 ppm.

The TNOA oxide concentration in the organic phase was measured using a liquid chromatograph mass spectrometer. Specifically, the peak of TNOA oxide was searched from the chromatogram obtained by the liquid chromatograph mass spectrometer, and the concentration of TNOA oxide existing in the organic phase was calculated based on the peak area.

In Table 1 below, the measurement results of the TNOA oxide concentrations of Test Example 1 in which air bubbling was performed for 1.6 hours in the neutralization treatment and Test Example 2 in which air bubbling was performed for 14 hours, and after such neutralization treatment, The results of the washing efficiency in the washing stage when hydrochloric acid is added to regenerate and repeated in the extraction stage are shown. The washing efficiency is a percentage of the nickel concentration in the aqueous phase (cobalt chloride aqueous solution) obtained through the washing stage with respect to the nickel concentration in the extracted organic phase that is subjected to the washing stage.

As shown in Table 1, in Test Examples 1 and 2 in which air was positively taken in by bubbling, the TNOA oxide concentration after the neutralization treatment was significantly increased as compared with the reference example in which air was not bubbled. .. Further, also in the comparison between Test Example 1 and Test Example 2, in Test Example 2 in which the bubbling time was lengthened and the air intake amount was increased, the TNOA oxide concentration was more than doubled. From this, it is understood that the tertiary amine contained in the organic phase is decomposed by the oxide mainly composed of air, and as a result, the alkylamine oxide is generated.

Although no significant difference was found between Test Example 1 and Test Example 2, it was found that the cleaning efficiency of entrainment in the cleaning stage was lowered when the concentration of TNOA oxide increased due to oxidative decomposition by air.

(Verification of alkylamine oxide formation by neutralization under high alkaline conditions)
In addition, the inventors of the present invention, in the neutralization treatment using the organic phase obtained through the back extraction stage, alkylamine oxide when the pH condition is changed from an acidic region to an alkaline region (pH 0 to 14). A test for measuring the (TNOA oxide) concentration was conducted. The TNOA oxide concentration in the organic phase was measured using a liquid chromatograph mass spectrometer.

FIG. 4 is a graph showing the measurement results. As shown in the graph of FIG. 4, generation of TNOA oxide was not observed under acidic conditions, and the concentration of TNOA oxide increased rapidly under high alkaline conditions (for example, alkaline conditions exceeding pH 12). From this, it is understood that the alkylamine oxide is produced by the neutralization treatment under the highly alkaline condition.

<2-2. Poor cleaning due to carboxylic acid formation>
Now, the present inventors have found that, in addition to the alkylamine oxide which is an amphoteric surfactant, the carboxylic acid which is a decomposition product of an amine-based extractant (tertiary amine) accumulates in the system, so It was discovered that poor cleaning of the entrainment occurs in.

FIG. 5 shows the concentration of heptanoic acid contained in the organic phase after the activation treatment in the regeneration stage and the entrainment concentration in the organic phase after extraction after performing cobalt extraction in the extraction stage using the organic phase. It is a graph which shows the relationship with (nickel concentration). Heptanoic acid is an aliphatic monocarboxylic acid that is a decomposition product of tertiary amine TNOA (tri-n-octylamine).

As shown in FIG. 5, there is a correlation between the concentration of heptanoic acid in the organic phase and the concentration of entrainment in the organic phase after extraction, and an aliphatic monocarboxylic acid that is a decomposition product of an amine-based extractant The higher the concentration of, the higher the entrainment concentration in the organic phase after extraction. That is, it is understood that the higher the concentration of the aliphatic monocarboxylic acid, the larger the amount of nickel brought into the washing stage as the extracted organic matter, and the higher the concentration of nickel in the organic phase after washing becomes.

Note that FIG. 6 is a diagram for explaining the mechanism of production of the aliphatic monocarboxylic acid from the amine-based extractant (tertiary amine). As shown in FIG. 6, tertiary amines such as TNOA are decomposed by oxides such as air, and heptanoic acid (indicated by “A” in FIG. 6) and octanoic acid (indicated by “B” in FIG. 6) are removed. To generate.

<<3. Manufacturing method of cobalt chloride aqueous solution (prevention of deterioration of entrainment cleaning efficiency)>>
The manufacturing method of the cobalt chloride aqueous solution which concerns on this invention mixes (1) the extraction stage which extracts cobalt into an organic phase from nickel chloride aqueous solution, and (2) mixes a part of aqueous phase after back extraction with the organic phase containing cobalt. Then, the washing step for removing nickel contained in the organic phase is carried out, and (3) after washing, the organic phase is brought into contact with a weakly acidic aqueous solution as a back-extracting agent to remove cobalt in the organic phase, and an aqueous cobalt chloride solution. And the organic phase after the back extraction in the (4) back extraction stage is subjected to neutralization treatment with an alkali, and then the neutralized organic phase is subjected to hydrochloric acid addition treatment with an aqueous hydrochloric acid solution. The organic phase after regeneration is obtained by subjecting to the above, and a solvent extraction step constituted by a regeneration stage repeated to the extraction stage is included.

In addition, the following (1)-(4) display shows each process in a solvent extraction process. In addition, a processing region including the processing stages (1) to (4) in the solvent extraction step is referred to as a “system”.

And in the manufacturing method of the cobalt chloride aqueous solution which concerns on this invention, the following is provided based on the knowledge about the cause of the fall of the cleaning efficiency of the entrainment as mentioned above. In the following, four of the first to fourth embodiments are independently shown, but the embodiments may be combined and processed.

<3-1. First embodiment>
Specifically, in the first embodiment, at least one or more treatment stages of (1) to (4) in the solvent extraction step, the mixer section of the mixer-settler type solvent extraction apparatus, the neutralization treatment tank, and the addition of hydrochloric acid are added. It is characterized in that the treatment is performed by adjusting the oxygen concentration in the gas phase portion of each treatment tank to be lower than the oxygen concentration in the atmosphere.

As described above, the reason why the cleaning efficiency of entrainment in the cleaning stage (2) is lowered is that the tertiary amine of the extractant is oxidized by the oxide containing air to form the alkylamine oxide which is an amphoteric surfactant. It has been found that Here, in each processing stage ((1) to (3)) of the solvent extraction step, processing using a mixer-settler type solvent extraction device is performed. In the neutralization treatment in the regeneration stage (4), a treatment using a neutralization treatment tank is performed, and in a hydrochloric acid addition treatment, a treatment using a hydrochloric acid addition treatment tank is performed. For example, in the mixer-settler type solvent extraction device, as shown in FIG. 2, in the mixer section 11, the organic phase and the aqueous phase are agitated and mixed by the agitation device 20 including the agitation shaft 20a and the agitation blade 20b. With this configuration, the air in the gas phase is taken into the mixed phase with the stirring. Therefore, in the first aspect of the method for producing an aqueous solution of cobalt chloride according to the present invention, the oxygen concentration in the gas phase portion of the mixer is adjusted to be lower than the oxygen concentration in the atmosphere for treatment. The same applies to the neutralization treatment tank and the hydrochloric acid addition treatment tank, and the treatment is performed by adjusting the oxygen concentration in the gas phase to be lower than the oxygen concentration in the atmosphere.

By doing so, since the oxygen concentration in the gas phase portion is lower than the oxygen concentration in the atmosphere, the amount of air (oxygen amount) entrained in the mixed phase by the stirring by the stirring device 20 is effective. Can be reduced to As a result, the amount of oxide that oxidizes the tertiary amine can be reduced, so that the oxidation of the tertiary amine can be suppressed and the amount of alkylamine oxide produced can be suppressed. Then, it is possible to prevent the reverse micelles of entrainment due to the alkylamine oxide, and effectively suppress the decrease in cleaning efficiency.

The state in which the oxygen concentration is lower than the atmospheric oxygen concentration in the gas phase portion means that the oxygen substance amount concentration (mol/m ³ ) in the gas phase portion atmosphere is lower than the atmospheric oxygen substance amount concentration. It means that the volume concentration of oxygen is lower than the volume concentration of oxygen in the atmosphere at atmospheric pressure.

Specifically, it is more preferable to adjust the oxygen concentration in the gas phase portion to a state of 10 to 16% by volume for treatment. If the oxygen concentration exceeds 16% by volume, the oxidation of the tertiary amine by oxygen may not be suppressed. On the other hand, in order to control the oxygen concentration in the vapor phase portion to be less than 10% by volume, excessive operation is required, cost is increased, and efficient treatment cannot be performed.

Further, in particular, during the neutralization treatment using an alkali in the regeneration stage (4), it is preferable to adjust the oxygen concentration in the gas phase portion of the neutralization treatment tank to be lower than the oxygen concentration in the atmosphere. .. The neutralization treatment in the regeneration stage (4) is considered to increase the production amount of alkylamine oxide in combination with the treatment under the highly alkaline condition. Therefore, among the treatments in the solvent extraction step, during the neutralization treatment with an alkali in the regeneration stage (4), the oxygen concentration in the gas phase part is set to be lower than the oxygen concentration in the atmosphere, and the system is treated. It is possible to more efficiently reduce the amount of the alkylamine oxide that is generated and accumulated inside, and it is possible to suppress a decrease in the cleaning efficiency of entrainment in the cleaning stage.

The method for adjusting the oxygen concentration in the gas phase part is not particularly limited, but it can be adjusted by, for example, substituting a part of oxygen in the gas phase part with an inert gas. Nitrogen gas, argon gas, or the like can be used as the inert gas, but nitrogen gas is preferable from the viewpoint of cost, handleability, and the like.

Further, when substituting a part of the oxygen in the gas phase portion with an inert gas, it can be performed by blowing an inert gas into the gas phase portion, but at that time, near the gas-liquid interface in the gas phase portion of the mixer portion. It is preferable to blow it toward (the vicinity). It is also effective to blow an inert gas near the stirring shaft of the stirring device provided in the mixer section. Since the air near the gas-liquid interface and the vicinity of the stirring shaft is easily taken into the mixed phase as it is stirred, the inert gas is blown into the vicinity to replace it with oxygen. The amount of oxygen entering can be reduced more efficiently.

<3-2. Second embodiment>
In the second embodiment, at least a part of the organic phase after the back extraction in the back extraction stage (3) is transferred to the regeneration stage (4) for neutralization treatment, and the remaining organic phase is left. It is characterized in that the phases are transferred directly to the extraction stage (1).

As described above, it has been found that the reason why the cleaning efficiency of entrainment in the cleaning stage (2) is lowered is that the formation of alkylamine oxide is the cause, and the formation of the alkylamine oxide is caused by the oxide containing air. It is presumed that, in addition to the oxidation by, the neutralization treatment under the highly alkaline condition (preferably pH 13 or more) using an alkali in the regeneration stage (4). Therefore, in the second embodiment of the method for producing an aqueous solution of cobalt chloride according to the present invention, at least a part of the organic phase after the back extraction in the back extraction stage (3) is transferred to the regeneration stage (4). While being subjected to neutralization treatment, the remaining organic phase is directly transferred to the extraction stage (1).

In other words, not all of the organic phase after back-extraction is subjected to neutralization treatment under highly alkaline conditions, but at least part of it is subjected to neutralization treatment, and the rest is neutralized. It is transferred directly to the extraction stage (1) without performing.

By doing so, a part of the organic phase after the back extraction is subjected to the neutralization treatment under the highly alkaline condition, so that the alkylamine oxide is one of the extractants flowing in the system. It is possible to relatively reduce the amount that may be decomposed into the product, and as a result, it is possible to effectively reduce the amount of alkylamine oxide accumulated in the system. From this, it is possible to prevent reverse micelles of entrainment due to alkylamine oxide, and effectively suppress a decrease in cleaning efficiency.

Regarding the organic phase directly transferred to the extraction stage (1), when it is used as the organic phase in the extraction stage (1), hydrochloric acid is added to activate the extractant in the organic phase. This enables effective reuse.

Specifically, the proportion of the organic phase after the back extraction in the back extraction stage (3) that is transferred to the neutralization treatment in the regeneration stage (4) is 1/300 or more and 1/30 or less in volume ratio. It is preferable to adjust the ratio to the above, and the remaining organic phase is transferred to the extraction stage (1). When the ratio of the organic phase transferred to the neutralization treatment is less than 1/300 in volume ratio, most of the organic phases are in a state where the neutralization treatment is not performed, and therefore impurity elements (zinc, iron, copper) in the organic phase May not be removed, resulting in a decrease in cobalt extraction capacity in the extraction stage (1). On the other hand, if the volume ratio of the organic phase transferred to the neutralization treatment exceeds 1/30, the production amount of alkylamine oxide may relatively increase.

In addition, since the amount of the organic phase used for the neutralization treatment in the regeneration stage (4) is only a part, the neutralization treatment for removing the impurity element is not performed for a part thereof, and as a result, the impurity element is not added. It is also thought to lead to an increase in However, in the method for producing an aqueous solution of cobalt chloride, it is general that a purification treatment step such as a deironing step is provided prior to the solvent extraction step, and the cobalt is used in the extraction stage (1) in the solvent extraction step. In addition, the impurity elements carried by the amine in the organic phase are very small. Therefore, even if only a part of the organic phase after the back extraction (for example, a volume ratio of 1/300 or more and 1/30 or less) is subjected to the neutralization treatment, the organic phase is circulated in the system. Impurity elements are effectively reduced and the effect is not impaired.

<3-3. Third embodiment>
Further, in the third embodiment, in the hydrochloric acid addition treatment in the regeneration stage (4), the flow rate of the hydrochloric acid aqueous solution (hydrochloric acid aqueous solution flow rate: A) is higher than the flow rate of the organic phase after neutralization treatment (organic phase flow rate: O). ) Is increased and processed.

As described above, it has been found that the reason why the cleaning efficiency of the entrainment in the cleaning stage (2) is lowered is the formation of alkylamine oxide, which is an amphoteric surfactant. Alkylamine oxide is considered to be produced by oxidation of tertiary amine, which is an extractant, when it contacts oxides such as air, and by neutralization under high alkaline conditions (preferably pH 13 or higher) for the organic phase after back extraction. Be done. Therefore, in the third embodiment of the method for producing an aqueous solution of cobalt chloride according to the present invention, in the hydrochloric acid addition treatment in the regeneration stage (4), the flow rate of the aqueous hydrochloric acid solution is made higher than the flow rate of the organic phase after the neutralization treatment (O <A) It is characterized by processing.

Hydrochloric acid addition treatment in the regeneration stage (4) is also called activation treatment, and by adding hydrochloric acid to the tertiary amine using an aqueous hydrochloric acid solution, cobalt in the initial solution for extraction (nickel chloride aqueous solution) is converted into a chloro complex ion. It is activated so that it can be supported in the form. At this time, by increasing the amount of the hydrochloric acid aqueous solution necessary for activation, that is, by increasing the flow rate of the hydrochloric acid aqueous solution higher than the flow rate of the organic phase after the neutralization treatment, the tertiary amine is activated and the hydrochloric acid aqueous solution is activated. Can be used as washing water.

Alkylamine oxide is an amphoteric surfactant as described above. Therefore, the alkylamine oxide, which is an amphoteric surface-active substance, can be effectively washed and removed by the hydrochloric acid aqueous solution having a larger flow rate than the organic phase after the neutralization treatment.

By doing so, the alkylamine oxide generated in the system (in particular, the neutralization treatment in the regeneration stage (4)) is effectively washed and removed by the aqueous hydrochloric acid solution, and the alkylamine oxide accumulated in the system is accumulated. Can be effectively reduced. From this, it is possible to prevent reverse micelles of entrainment due to alkylamine oxide, and effectively suppress a decrease in cleaning efficiency.

Specifically, it is preferable that the ratio (O/A) of the flow rate (O) of the organic phase after the neutralization treatment and the flow rate (A) of the aqueous hydrochloric acid solution be in the range of 0.2 to 0.5. When O/A is less than 0.2, the flow rate of the hydrochloric acid aqueous solution becomes too large, which increases the cost. On the other hand, when O/A exceeds 0.5, the effect of the hydrochloric acid aqueous solution as washing water is reduced, and the alkylamine oxide may not be efficiently removed.

The inventors conducted a test of adding an aqueous hydrochloric acid solution to the organic phase after the neutralization treatment at O/A of 0.5 to perform the hydrochloric acid addition treatment. As a result, while the concentration of alkylamine oxide in the organic phase after the neutralization treatment was 7 ppm, the alkylamine oxide in the organic phase after the hydrochloric acid addition treatment was carried out at a higher flow rate of the hydrochloric acid aqueous solution than the organic phase flow rate. The amine oxide concentration was 5 ppm, and it was confirmed that the alkylamine oxide was effectively washed and removed by the hydrochloric acid aqueous solution. The concentration of alkylamine oxide in the organic phase was measured using a liquid chromatograph mass spectrometer.

<3-4. Fourth embodiment>
As described above, the reason why the cleaning efficiency of the entrainment in the cleaning stage (2) is lowered is not only due to the alkylamine oxide which is an amphoteric surface-active substance, but also because the tertiary amine of the extractant is an oxide such as air. It has also been found that the carboxylic acid (aliphatic monocarboxylic acid) generated by decomposition by (1) is accumulated in the system (see FIGS. 5 and 6).

Therefore, in the fourth embodiment of the method for producing an aqueous cobalt chloride solution according to the present invention, the content of the aliphatic monocarboxylic acid contained in the organic phase (organic phase containing cobalt) obtained through the extraction stage (1) is 45 It is characterized in that the treatment is carried out so that the volume is maintained at ppm or less.

When TNOA (tri-n-octylamine) is used as the tertiary amine of the extractant, heptanoic acid is included as the aliphatic monocarboxylic acid decomposed and produced by air or the like.

As shown in FIG. 5, when the content of heptanoic acid that is an aliphatic monocarboxylic acid in the organic phase exceeds 45 ppm by volume, the organic phase after extraction in the extraction stage (1) (extracted organic phase) It can be seen that the entrainment content in the composition exceeds 1000 ppm. Therefore, by maintaining the content of the aliphatic monocarboxylic acid contained in the organic phase obtained through the regeneration stage (4) to be 45 ppm by volume or less, the amount of entrainment in the organic phase after extraction, that is, The amount of nickel brought into the washing stage as extracted organics can be effectively reduced, in other words, the nickel concentration in the post-washing organic phase obtained through the washing stage (2) can be reduced.

Here, as a method for maintaining the content of the aliphatic monocarboxylic acid contained in the organic phase, it is preferable to execute any one or more of the following (a) to (d). In addition, the content of the aliphatic monocarboxylic acid in the organic phase obtained through the regeneration stage (4) is regularly measured and monitored, and when the content exceeds 45 ppm by volume. Any one or more of the following methods (a) to (d) may be executed.

Specifically, the following method is used.
(A) At least one or more treatment stages of (1) to (4) in the solvent extraction step, a gas phase in a treatment tank such as a mixer section of a mixer-settler type solvent extraction device, a neutralization treatment tank, and a hydrochloric acid addition treatment tank. The oxygen concentration in the area is adjusted to be lower than the oxygen concentration in the atmosphere before processing.
(B) At least a part of the organic phase after the back extraction in the back extraction stage is transferred to the regeneration stage for neutralization treatment, and the remaining organic phase is transferred directly to the extraction stage.
(C) In the hydrochloric acid addition treatment in the regeneration stage, the flow rate of the hydrochloric acid aqueous solution (hydrochloric acid aqueous solution flow rate: A) is made higher than the flow rate of the organic phase after neutralization treatment (organic phase flow rate: O).
(D) The addition ratio of the new extractant supplied to the extraction stage is adjusted.

Methods (a), (b), and (c) are the methods described in the above-described first embodiment, second embodiment, and third embodiment, respectively, and detailed description thereof will be given here. Is omitted.

Regarding the method (d), in the solvent extraction step, a new extractant (tertiary amine) is appropriately added in the extraction stage (1). From this, the amount of the aliphatic monocarboxylic acid can be relatively reduced by executing the method of adjusting the addition ratio of the new extractant according to the content of the aliphatic monocarboxylic acid contained in the organic phase. Can be made Moreover, the extraction ability of the extractant contained in the organic phase can be stably maintained.

1 Mixer Settler Type Solvent Extractor 11 Mixer 11a Water Phase Inlet 11b Organic Phase Inlet 12 Settler 13 Outlet 13w Partition 14 Gutter 20 Stirrer 20a Stirring Shaft 20b Stirring Blade

Claims (3)

A cobalt-chloride aqueous solution is produced by separating and recovering cobalt-containing nickel chloride aqueous solution by a solvent extraction method using an organic solvent containing a tertiary amine as an extractant in an organic phase using a mixer-settler type solvent extraction device. Method,
(1) an extraction stage for extracting cobalt into the organic phase from the nickel chloride aqueous solution,
(2) A washing stage in which a part of the aqueous phase after back extraction is mixed with the cobalt-containing organic phase obtained in the extraction stage to remove nickel contained in the organic phase,
(3) Cobalt in the organic phase after washing in the washing stage is brought into contact with the organic phase after washing (organic phase after washing) to desorb cobalt in the organic phase, and water in the aqueous solution of cobalt chloride is removed. A back extraction stage to obtain the phase,
(4) The organic phase after regeneration by subjecting the organic phase after the back extraction in the back extraction stage to neutralization treatment with an alkali, and then subjecting the organic phase after the neutralization treatment to hydrochloric acid addition treatment with an aqueous hydrochloric acid solution And a regeneration stage repeated in the extraction stage,
Comprising a solvent extraction step consisting of
At least a part of the organic phase after the back extraction in the back extraction stage is transferred to the regeneration stage and subjected to the neutralization treatment, and the remaining organic phase is transferred directly to the extraction stage Aqueous cobalt chloride solution Manufacturing method. Of the organic phase after back-extraction in the back-extraction stage, the organic phase in a volume ratio of 1/300 or more and 1/30 or less is transferred to the regeneration stage and subjected to the neutralization treatment, The method for producing an aqueous cobalt chloride solution according to claim 1, wherein the remaining organic phase is transferred to the extraction stage. The method for producing an aqueous cobalt chloride solution according to claim 1 or 2, wherein the neutralization treatment in the regeneration stage is performed under conditions of pH 13 or higher with addition of an alkali.

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