JP2022022747A - Method of suppressing reverse micelle formation in solvent extraction method - Google Patents

Abstract

To provide a method of suppressing reverse micelle formation in a solvent extraction method, capable of properly suppressing formation of entrainment existing in the form of reverse micelle in a solvent extraction method.SOLUTION: A method of suppressing formation of reverse micelle in a solvent extraction method includes adding sulfolane to an organic phase used for extraction treatment. By adding sulfolane to the organic phase used for extraction treatment, formation of reverse micelle, which is one kind of entrainment generated by extraction treatment, can be suppressed.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for suppressing reverse micelle formation in a solvent extraction method.

In the hydrometallurgical method of nickel, the separation of nickel and cobalt contained in an acidic aqueous solution is the most important technical element. Usually, the separation of nickel and cobalt in an acidic aqueous solution is carried out by a solvent extraction method using various organic extractants. Examples of the organic extractant include a phosphoric acid ester-based acidic extractant such as D2EHPA (Di- (2-ethylhexyl) phosphoricacid) having excellent separation performance between nickel and cobalt, and an amine-based extractant such as TNOA (Tri-n-octylamine). An extractant is used. Generally, when the anion is a sulfate ion, a phosphate ester-based acidic extractant is used, and when the anion is a chloride ion, an amine-based extractant is used.

Here, when the chloride ion concentration in the aqueous solution is high (for example, a chloride aqueous solution having a chloride ion concentration of 200 g / L or more), cobalt forms chloro complex ions in the aqueous solution, whereas nickel forms chloro complex ions. Does not form chloro complex ions. Therefore, for such an aqueous solution, an amine-based extractant having a higher separation coefficient between cobalt and nickel than a phosphoric acid ester-based acidic extractant is adopted.
In addition, when a phosphoric acid ester-based acidic extractant is used, hydrogen ions are released from the extractant by extraction of metal ions, so that it is necessary to supply a neutralizing agent for suppressing the generation of hydrogen ions. Clad (a solid such as a metal hydroxide that stays and accumulates between the organic phase and the aqueous phase in the oil-water separation device due to pH fluctuations, and greatly inhibits oil-water separation, which is an important technical element for solvent extraction. ) Occurs.

Therefore, an amine-based extractant is adopted as an organic extractant used when separating cobalt from a cobalt-containing nickel chloride aqueous solution by a solvent extraction method, and industrially, an extraction stage, a washing stage, and a reverse step are adopted. It has been industrialized as a solvent extraction process consisting of an extraction stage.
As the amine-based extractant, a primary amine (RNH ₂ ), a secondary amine (R ₂ NH), or a tertiary amine (R ₃ N) is used (Note that R is an arbitrary saturated or unsaturated hydrocarbon group. show). Such an amine-based extractant possesses the ability to extract metal chloro complex ions by being activated by the addition of hydrochloric acid, and has excellent nickel-cobalt separation properties.

First, in the extraction stage, metal species that form 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 ions of the metal element are extracted. The carried amine is produced. On the other hand, nickel in the nickel chloride aqueous solution does not form a chloro complex ion, so that it remains in the extraction residual liquid and is separated.

The washing step of the next step is a step of washing the organic phase after the extraction step using a highly pure cobalt chloride aqueous solution which is a back extract produced in the back extraction step of the next step. That is, by washing the organic phase after extraction with an aqueous solution of cobalt chloride, the aqueous solution of nickel chloride in the organic phase brought in as an entrainment from the extraction stage is diluted and replaced with the aqueous solution of cobalt chloride to reduce the nickel concentration in the organic phase. It is a process of lowering. Since the aqueous phase washed and removed after washing is a cobalt chloride aqueous solution containing nickel, it is mixed with the extraction starting liquid and repeated in the extraction stage.

The final back extraction step is a step of desorbing cobalt into the aqueous phase by contacting the washed organic phase, that is, an amine carrying a chloro complex ion of cobalt with a weakly acidic aqueous solution (dilute hydrochloric acid or the like). Is. Then, the back extract obtained in the back extraction stage, that is, the cobalt chloride aqueous solution, is further purified (treated to remove impurities such as manganese, copper, zinc) by a treatment route different from that of nickel. After that, it is commercialized as electric cobalt by electrowinning.

By the way, the cobalt chloride aqueous solution after the back extraction step may contain a trace amount of nickel, and it is very difficult to industrially remove such a trace amount of nickel. On the other hand, a small amount of nickel contained in the cobalt chloride aqueous solution contaminates the electric cobalt produced in the electrowinning process and becomes a factor of deteriorating the product quality.
Therefore, in the method for producing a cobalt chloride aqueous solution by solvent-extracting cobalt from a cobalt-containing nickel chloride aqueous solution with an organic solvent containing an amine-based extractant, the nickel concentration in the obtained cobalt chloride aqueous solution is effectively reduced. It has become an important technical issue.

Conventionally, industrially, as a method for cleaning an organic phase, the inside of the mixer tank (stirring tank) is made continuous with the organic phase, and the volume ratio of the organic relative aqueous phase in the mixer tank is set to 3.0 or less. (For example, Patent Document 1).
In Patent Document 1, by making the inside of the mixer tank continuous with the organic phase, the bond between water droplets in the organic phase is promoted, and the nickel concentration in the entrainment (fine droplet emulsion of the aqueous phase) is increased. It is described that the cleaning efficiency can be improved because the entrainment itself can be reduced as well as the reduction.

JP-A-2015-183267A

However, in the cleaning method of Patent Document 1, when the oil-water separation efficiency in the settler portion (oil-water separation tank) is lowered, the entrainment in the organic phase is increased and the nickel concentration in the cobalt chloride aqueous solution is reduced. There is a problem that it cannot be done.

Here, in the industrialized process, in operation, a new substance may be generated due to deterioration of the organic solvent, or impurities and the like based on the raw material may be mixed. Due to such substances, the entrainment in the organic phase tends to be in a minute shape, and those having a size of about 1000 nm or less (1 to 1000 nm) tend to exist in the form of inverted micelles. Since the entrainment existing in the form of inverted micelles exists in an extremely stable form in the organic phase, when the inverted micelles are formed, they are more dispersed and more dispersed by the washing method of Patent Document 1. It is considered that the oil-water separability deteriorates even in the settler portion with almost no sedimentation.

Therefore, in order to reduce the nickel concentration in the cobalt chloride aqueous solution, it is very important to suppress the decrease in the cleaning efficiency of the entrainment, that is, the formation of reverse micelles that cause cleaning defects, when extracting the solvent. ..

In view of the above circumstances, it is an object of the present invention to provide a method for suppressing the formation of reverse micelles in the solvent extraction method, which can appropriately suppress the formation of entrainments existing in the form of reverse micelles in the solvent extraction method.

The method for suppressing the formation of reverse micelles in the solvent extraction method of the first invention is a method for suppressing the formation of reverse micelles in the solvent extraction method, and is characterized by adding sulfolane to the organic phase used in the extraction treatment. ..
The method for suppressing the formation of reverse micelles in the solvent extraction method of the second invention is the method for suppressing the formation of reverse micelles in the first invention, wherein the sulfolane is a substance causing the formation of reverse micelles contained in the organic phase before the extraction treatment. It is characterized by adding 0.1 equivalent or more with respect to 1 equivalent.
The method for suppressing reverse micelle formation in the solvent extraction method of the third invention is characterized in that, in the second invention, the reverse micelle formation-causing substance is specified based on the reverse micelle formation rate _Erm .
The method for suppressing the formation of reverse _micelles in the solvent extraction method of the fourth invention is as follows. An aqueous phase-dispersed organic solution prepared by centrifuging the solution to remove water to prepare a predetermined amount of the first water-removing organic solution, and adding a predetermined amount of the aqueous solution to the first water-removing organic solution to disperse the solution. Then, the aqueous phase-dispersed organic solution was subjected to centrifugation to remove water to prepare a second water-removing organic solution, and the water content of the first water-removing organic solution was set to _Wb . The water content of the water-removing organic solution was defined as W _rm , and the water content _{ΔW rm} increased from the water content Wb of the first water-removing organic solution in the second aqueous phase dispersed organic solution was obtained (volume of the aqueous solution). The water content W ₀ is obtained from / {(volume of the first water-removing organic solution) + (volume of the aqueous solution)}, calculated based on the ratio of the water content W _rm to the water content W ₀ , and vice versa. The micellar formation-causing substance is characterized by being specified based on the inverse micelle formation rate _Erm when added to any one or more of the organic solution, the preparative organic solution, or the aqueous solution. And.
The method for suppressing reverse micelle formation in the solvent extraction method of the fifth invention is characterized in that, in the third invention or the fourth invention, the reverse micelle formation rate _Erm is calculated by the following formula.
E _rm = ΔW _rm / W ₀
The method for suppressing reverse micelle formation in the solvent extraction method of the sixth invention is the invention according to any one of the first to fifth inventions, wherein the upper limit of the addition amount of the sulfolane is one equivalent of the reverse micelle formation-causing substance. On the other hand, the amount is 10 equivalents or less.
The method for suppressing reverse micelle formation in the solvent extraction method of the seventh invention is characterized in that, in the invention according to any one of the first to sixth inventions, the sulfolane is added to the organic phase before the extraction treatment. And.
In the method for suppressing reverse micelle formation in the solvent extraction method of the eighth invention, in the invention according to any one of the first to seventh inventions, the organic phase is a phosphoric acid ester-based acidic extractant or an amine-based extractant. It is characterized by containing an organic extractant.
The method for suppressing reverse micelle formation in the solvent extraction method of the ninth invention is characterized in that, in the invention according to any one of the first to eighth inventions, the reverse micelle formation-causing substance is heptanic acid.
The method for suppressing reverse micelle formation in the solvent extraction method of the tenth invention is the method in which the solvent extraction method is used for wet smelting of non-ferrous metals in the invention according to any one of the first to ninth inventions. It is characterized by being.

According to the first invention, by adding sulfolane to the organic phase used in the extraction treatment, the formation of reverse micelles generated in the extraction operation can be suppressed.
According to the second invention, the formation of reverse micelles can be appropriately suppressed.
According to the third invention, the fourth invention, and the fifth invention, the substance causing the reverse micelle formation can be appropriately specified by calculating the reverse micelle formation rate _Erm .
According to the sixth invention, the amount of sulfolane added can be controlled.
According to the seventh invention, the formation of reverse micelles can be appropriately suppressed by controlling the timing of addition of sulfolane.
According to the eighth invention, the formation of reverse micelles when a predetermined organic solvent is used can be suppressed.
According to the ninth invention, the formation of reverse micelles can be suppressed based on a predetermined substance causing reverse micelle formation.
According to the tenth invention, the formation of reverse micelles in the solvent extraction used for a predetermined application can be appropriately suppressed.

FIG. 3 is a schematic flow chart for calculating the inverse micelle conversion rate _Erm of the present embodiment. It is a figure which showed the experimental result, and is the graph which showed an example of the relationship between the dispersion time (stirring time) in the dispersion treatment S2, and the moisture content in an organic phase. It is a figure which showed the experimental result, and is the graph which confirmed the influence of sulfolane. It is a figure which showed the experimental result, and is the graph which shows the relationship between the addition amount of sulfolane and the reverse micelle formation rate _Erm .

The method for suppressing the formation of reverse micelles in the solvent extraction method of the present embodiment is such that the formation of reverse micelles, which is a kind of entrainment generated by the extraction operation, can be suppressed by adding sulfolane to the organic phase in the solvent extraction method. It has a feature in what it did.

The organic phase to which sulfolane is added in the present specification is a concept that includes not only those in the state of an aqueous phase and an organic phase in the solvent extraction method but also those in the state of an organic solution used for this organic phase. That is, the organic phase to which sulfolane is added in the present specification means the organic phase used in the extraction treatment. Specifically, in the solvent extraction method, an organic solution corresponding to the organic phase before contacting with the aqueous solution corresponding to the aqueous phase, an organic phase in a state where the solvent extraction treatment can be performed in contact with the aqueous phase, and an extraction treatment. Refers to the state of each organic phase of the organic phase during solvent extraction in the state of performing.

The organic solution used as the organic phase is not particularly limited as long as it is used as the organic phase in the solvent extraction method.
Specifically, industrial ones such as those used for the organic phase in the solvent extraction method used for wet smelting of non-ferrous metals and those used for the organic phase used for solvent extraction in a general chemical treatment step. Alternatively, any organic solution used for the organic phase in the solvent extraction method used experimentally is not particularly limited.

For example, one or a mixture of two or more general organic solvents and extractants can be used as the organic solution. Examples of general organic solvents include various compounds such as hydrocarbon-based solvents such as hexane, isooctane, and dodecane, aromatic hydrocarbons such as benzene, toluene, and xylene, and halogen-based solvents such as chloroform and dichromethane. can. As the extractant, for example, as various extractants such as an amine-based extractant used for extracting valuable metals, a phosphoric acid ester-based acidic extractant, a carboxylic acid-based extractant, and an organic extractant such as a phosphorus-based neutral extractant. The compounds used can be mentioned. Needless to say, the above organic solution may also contain various additives used industrially and experimentally, such as modifiers such as methanol and decanol.

Further, for example, in the solvent extraction method used for separating nickel and cobalt in an acidic aqueous solution in a nickel hydrometallurgy method, an amine-based extractant is used when the anion of the extraction starting solution is chloride ion. .. As the amine-based extractant, a tertiary amine is used, and examples of the tertiary amine include TNOA (Tri-n-octylamine) and TIOA (Tri-i-octylamine).
When the anion is sulfate ion, a phosphate ester-based acidic extractant is used. Examples of the phosphoric acid ester-based acidic extractant include trade name PC-88A (main component: 2-ethylhexyl 2-ethylhexyl phosphonate) and D2EHPA (Di- (2-ethylhexyl) phosphoricid).
Here, it is known that the amine-based extractant has a higher separation coefficient between cobalt and nickel than the phosphoric acid ester-based acidic extractant.
Therefore, in the separation and purification of nickel and cobalt in the hydrometallurgical method of nickel, an amine-based extractant is generally used in many cases. In particular, tertiary amine-based extractants are often used from the viewpoint of high reactivity and low solubility in water, and among them, TNOA or TIOA is often adopted in terms of handleability and price. There is. That is, in the industrial solvent extraction method, those containing the amine-based extractant TNOA or TIOA in the organic phase tend to be used.

The solvent extraction method for which the formation of reverse micelles of the present specification is suppressed is also not particularly limited.
For example, industrial or experimental solvent extraction methods such as solvent extraction methods used for wet smelting of non-ferrous metals and solvent extraction methods in general chemical treatment steps can be targeted.

As used herein, the term "entration" refers to an aqueous solution (aqueous phase) contained in the organic phase generated by an extraction operation in the form of fine droplets. Hereinafter, this entrainment may be referred to as a water drop emulsion.
The term "reverse micelle" as used herein refers to a molecular assembly of an entrainment in which the hydrophilic base of the surfactant molecule is directed to the inside and the hydrophobic base is directed to the outside in a non-polar solvent. This molecular assembly is thermodynamically stable and has the ability to solubilize a large amount of aqueous phase inside. The size of the inverted micelle is not particularly limited as long as it exists in the organic phase in a stable form. For example, it has a size of about 1000 nm or less (for example, 1 nm to 1000 nm).

(Timing of addition of sulfolane)
The timing of adding sulfolane to the organic phase may be any state as long as it is the organic phase in the above-mentioned state. Specifically, in the solvent extraction method, the organic phase before the solvent extraction treatment (the organic phase in the state of the organic solution before contacting with the aqueous phase, the organic phase in the state of contact with the aqueous phase before the extraction treatment). It can be added to the organic phase during the extraction process.

The timing of adding sulfolane to the organic phase is not particularly limited as described above, but from the viewpoint of operability, it is preferable to add sulfolane in the following order. The first is preferably added to the organic phase in the state of the organic solution before contacting with the aqueous phase, the second is the organic phase in the state of being in contact with the aqueous phase before the extraction treatment, and the third is the extraction treatment. The organic phase inside. For example, sulfolane can be added to the organic phase in the first state prior to the solvent extraction treatment, and then this organic phase can be supplied to the extraction treatment step. Further, if it is added to the state before the extraction treatment, it tends to improve the suppression of the formation of reverse micelles.

(Amount of sulfolane added)
The amount of sulfolane added is not particularly limited as long as it can suppress the formation of reverse micelles. For example, the amount of sulfolane added is economical and from the viewpoint of appropriately suppressing the formation of reverse micelles, the substance M caused by the formation of the contained reverse micelles in the organic phase (hereinafter, simply "substance M caused by reverse micelle formation"). The amount to be added can be adjusted based on the relationship with).

Specifically, the sulfolane is added to the amount of the reverse micelle formation-causing substance M1 equivalent contained in the organic phase before the extraction treatment (that is, the first organic phase or the second organic phase at the above-mentioned sulfolane addition timing). On the other hand, it is added so as to be 0.1 equivalent or more. For example, as described in Examples, when the reverse micelle formation-causing substance M is enanthic acid and its concentration is 3.5 mmol / L, sulfolane can be added so as to be 0.35 mmol / L or more. The formation of micelles can be suppressed.

This is because if the amount of sulfolane added is lower than 0.1 equivalent with respect to the M1 equivalent of the substance causing reverse micelle formation, the concentration of sulfolane in the organic phase becomes too low and the suppression rate of reverse micelle tends to decrease. On the other hand, the upper limit of the amount of sulfolane added is not particularly limited, but even if sulfolane is added in an amount of 10 equivalents or more with respect to the amount of M1 equivalent of the substance causing reverse micelle formation, the effect of suppressing the formation of reverse micelles tends not to be improved.
Therefore, when adjusting the addition amount of sulfolane based on the reverse micelle formation-causing substance M, the addition amount of sulfolane is preferably 0.1 equivalent or more and 10 equivalents or less with respect to the reverse micelle formation-causing substance M1 equivalent. It is preferably 0.1 equivalent or more and 5 equivalents or less, and more preferably 0.1 equivalent or more and 3 equivalents or less.

The concentration of the reverse micelle formation-causing substance M in the organic phase can be determined by a general measuring method. For example, in the case of carboxylic acid, it can be measured by a gas chromatography method (JIS K 0123: 2018), and in the case of heptanic acid, it can be measured by a liquid chromatography mass spectrometry method or the above gas chromatography method. ..

(Calculation method of inverse micelle conversion rate _Erm )
The substance M caused by the formation of reverse micelles refers to a substance caused by the formation of reverse micelles as described above. This reverse micelle formation-causing substance M can be specified based on the reverse micelle formation rate _Erm .
Hereinafter, a method for calculating the inverse micelle formation rate _Erm will be described with reference to FIG.
First, the outline will be briefly described.

In the present specification, the ratio of the aqueous phase (a part of the aqueous solution A) incorporated into the reverse micelles out of the aqueous solution A added to the organic solution L is defined as the reverse _{micelleization} rate Erm.
The aqueous phase (a part of the aqueous solution A) inside the reverse micelle can also be regarded as being extracted into the organic phase when the organic solution L and the aqueous solution A are mixed. In this case, the inverse micelle conversion rate _Erm can be considered as the inverse micelle extraction rate.
If the size of the reverse micelle as described above is about 1000 nm or less (1 nm to 1000 nm), it remains dispersed in the organic phase of FIG. 1 even after centrifugation S1 and S3. ..

First, a sample for measuring the water content W is prepared.
A sample is separated from the predetermined organic phase L0 (organic phase used in the extraction operation), and the separated organic solution L1 is subjected to centrifugation S1 to remove water to remove the first water-removing organic solution L2. Prepare. Then, a predetermined amount of the aqueous solution A is added to the first water-removing organic solution L2, and the aqueous phase-dispersed organic solution L3 in which the aqueous solution A is dispersed S2 is prepared by stirring or the like. The aqueous phase-dispersed organic solution L3 is again subjected to the centrifugation treatment S3 to remove water to prepare a second water-removing organic solution L4.

Then, the moisture content W of each prepared sample is measured.
From the prepared first water-removing organic solution L2 and second water-removing organic solution L4, the respective water content W (moisture rate W _b , water content W _rm ) is measured.
In the second aqueous phase dispersed organic solution L4, the water content _ΔWrm increased from the water content _Wb of the first water-removing organic solution L2 is calculated from the formula 3) or the formula 4) described later.
Then, the theoretical moisture content W0 obtained from (volume of aqueous solution A) / {(volume of first water-removing organic solution L2) + (volume of aqueous solution A) _} is obtained from equations 5) or 6) described later. calculate.
Then, by substituting the calculated water content W ₀ and the water content ΔW _rm into the formula 7) described later, among the fine droplets (that is, entrainment) contained in the aqueous phase dispersed organic solution L3, the reverse micelle The inverse _{micelleization} rate Erm of the entrainment existing in the form is calculated.

If the calculated inverse micelle formation rate _Erm is large, it means that the amount of minute entrainments contained in the organic solution L (that is, the entrainments existing in the form of inverse micelles) increases, and vice versa. If the micelle formation rate _Erm is small, it means that the amount of minute entrainment contained in the organic solution L is reduced.

This will be described in detail below.
<Adjustment of organic phase L0>
The organic phase L0 used for calculating the inverse micelle formation rate _Erm is the above-mentioned organic phase before the extraction treatment (organic phase before contacting with the aqueous phase in the solvent extraction method (organic solution before becoming the organic phase state). ) Or the organic phase before the extraction treatment in contact with the aqueous phase).
For example, a solution corresponding to the organic solution used as the organic phase in the solvent extraction method of the above-mentioned wet smelting method of nickel may be prepared and used at the laboratory level, or the organic phase used in the operation may be used. May be good.

As the organic phase L0, the target organic phase may be prepared as described above, or the organic phase itself used for operation may be used. For example, the organic phase L0 uses an amine-based extractant, a phosphoric acid ester-based acidic extractant, a carboxylic acid-based extractant, an organic extractant such as a phosphorus-based neutral extractant, and the like, in addition to the above-mentioned general organic solvent. Can be prepared.
In particular, when the target organic phase is a nickel hydrometallurgy method, as described above, an amine-based extractant is generally used in the separation and purification of nickel and cobalt in the nickel hydrometallurgy method. Often. In particular, tertiary amine-based extractants are often used from the viewpoint of high reactivity and low solubility in water, and among them, TNOA or TIOA is often adopted in terms of handleability and price. There is. Therefore, when such an organic phase is targeted, it is preferable to prepare the organic phase L so as to contain the amine-based extractant TNOA or TIOA.

When the target organic phase uses a plurality of types of solvents or solvents, the organic phase L0 may be prepared by similarly mixing two or more types. For example, in the solvent extraction method of the nickel wet smelting method described above, the organic phase L0 can be prepared by mixing the organic extractant and the organic solvent that functions as a diluent.
The organic solvent that functions as a diluent is not particularly limited as described above. For example, aromatic hydrocarbons, naphthenic hydrocarbons, and the like can be used from the viewpoint of low solubility in water and good oil-water separability.

The concentration of the organic extractant in the mixture of the organic extractant and the organic solvent (diluent) is preferably adjusted appropriately according to the desired viscosity range of the organic phase L0. For example, it can be adjusted to be within the range of 10 to 40% by volume of the total organic solution used.

The organic phase L0 may contain the above-mentioned modifier in addition to the above-mentioned organic solvent or organic extractant.

(Reverse micelle formation-causing substance M)
As the reverse micelle formation-causing substance M, a substance that is supposed to contribute to the increase of entrainment (hereinafter, also simply referred to as reverse micelle) existing in the form of reverse micelle in the organic phase in the solvent extraction method is added to the organic phase L. Then, it can be specified from the relationship between the reverse micelle formation-causing substance M and the reverse micelle.

The reverse micelle formation-causing substance M may be added to, for example, the prepared organic phase L0, the preparative organic solution L1 or the aqueous solution A, or two or more of the organic phase L0, the preparative organic solution L1 and the aqueous solution A. It may be added to the solution.
That is, the reverse micelle formation-causing substance M may be added to any one of the above three solutions, may be added to two solutions, or may be added to all three solutions. good. Further, when considering a plurality of substances as the reverse micelle formation-causing substance M as described later, they may be added to the same solution or may be added to different solutions.
The addition concentration is not particularly limited as long as it can evaluate the relationship with the reverse micelle, and may be appropriately adjusted so as to be within a range expected to be industrially mixed, for example.

As the substance M causing the formation of reverse micelles, various substances assumed in operation can be evaluated.
For example, substances obtained by lowering the amine-based extractant, carboxylic acids such as methanic acid, enanthic acid, propanoic acid, butanoic acid, pentanoic acid, hexanoic acid, heptanic acid, and octanic acid, and amide compounds can be mentioned. , Not limited to such substances.
Further, for example, in addition to MNOA (Mono-n-octylamine) and methanesulfonic acid, TNOA used as an amine-based extractant can also be mentioned as an evaluation target as a substance M causing reverse micelle formation.
Further, the reverse micelle formation-causing substance M is not limited to one kind, and two or more kinds of substances may be adopted. For example, different substances may be adopted as the reverse micelle formation-causing substance M1 and the reverse micelle formation-causing substance M2. In this case, for example, the reverse micelle formation-causing substances M1 and M2 are added to different solutions (for example, the reverse micelle formation-causing substance M1 is added to the preparative organic solution L1 and the reverse micelle formation-causing substance M1 is added to the aqueous solution A. The substance M2 may be added), or it may be added to the same solution. Further, the reverse micelle formation-causing substance M may be prepared to contain two or more kinds of reverse micelle formation-causing substances M1, M2, and so on.

(Centrifugal separation treatment S1, S3)
The first water-removing organic solution L2 is prepared by separating a predetermined amount from the organic phase L0, subjecting the separated separated organic solution L1 to a centrifuge, and then removing the aqueous phase.
Further, the second water-removing organic solution L4 is prepared by subjecting the aqueous phase-dispersed organic solution L3 in which the aqueous solution A is dispersed to a centrifuge and then removing the aqueous phase.
Centrifugation treatment S1 is an operation of removing water that can be separated by centrifugation from the organic solution L1 because water that cannot be seen by appearance may be dissolved.
Centrifugation treatment S3 is an operation for removing centrifugable water in the separable aqueous phase and the organic phase. That is, this centrifugation treatment S3 is an operation of removing the entrainment having a size larger than 1000 nm dispersed in the organic phase by the dispersion treatment S2 from the aqueous phase dispersed organic solution L3. In other words, from the centrifugation treatment S3, the aqueous phase-dispersed organic solution L3 contains only the entrainments that are extremely stable in the form of inverted micelles having a size of 1000 nm or less. It is an operation to make.
The device or the like used for the centrifuge treatments S1 and S3 is not particularly limited as long as it is a device or device capable of exerting the above-mentioned functions, and for example, a commercially available centrifuge or the like may be adopted. Can be done.

(Distributed processing S2)
The aqueous phase-dispersed organic solution L3 is prepared by separating a predetermined amount (volume _Vorg1 ) from the first water-removing organic solution L2 from which the aqueous phase has been removed by separating the water separable by the above-mentioned method by centrifugation. A predetermined amount (volume V _aq1 ) of the aqueous solution A is added to a predetermined amount (volume V org ₁ ) of the water-removing organic solution L2, and the solution is dispersed S2 by stirring or the like.

The amount of the first water-removing organic solution L2 (volume _Vorg1 ) is not particularly limited. For example, from the viewpoint of operability, it can be prepared to be 10 ml to 100 ml.

The amount of the aqueous solution A to be added is preferably adjusted so that the first water-removing organic solution L2 has a continuous phase. For example, the amount of the aqueous solution A added (volume V _aq1 ) is preferably 10% by volume or less with respect to the water-removing organic solution L2 (volume V _org 1).
If the amount of the aqueous solution A added is too small, it becomes difficult to measure the water content. Therefore, it is preferable to set the measurement within a range in which the measurement can be appropriately performed in consideration of the total amount of the liquid, the sampling amount, and the like. The dispersion treatment S2 is preferably performed at a temperature near room temperature, but if the viscosity of the organic solution (moisture-removing organic solution L2) is high, the temperature may be raised. However, when raising the temperature, it is necessary to consider the decrease due to the evaporation of water.

In the dispersion treatment S2, as long as the aqueous solution A can be dispersed in the first water-removing organic solution L2, the instruments and devices used are not particularly limited, and a commercially available stirring device or the like can be adopted. For example, when a commercially available magnetic stirrer is used, the aqueous phase dispersed organic solution L3 can be prepared if the treatment conditions are a rotation speed of 500 rpm to 2000 rpm and a stirring time of 1 minute or more.

(Dispersion time)
In particular, the dispersion time (stirring time) in the dispersion treatment S2 is not particularly limited as long as the added aqueous solution A is in a stable state, and may be appropriately adjusted depending on the treatment conditions and the like.
For example, when the treatment conditions for a predetermined amount of the aqueous solution A are room temperature (temperature around 25 ° C.) and a rotation speed of 500 to 1500 rpm, 1 minute or more is preferable, 3 minutes or more is more preferable, and 5 minutes or more is more preferable. Stir to be.

The state in which the added aqueous solution A is appropriately dispersed can be grasped from the relationship between the dispersion time (stirring time) and the increased water content ΔW in the aqueous phase dispersed organic solution L3.
For example, FIG. 2 shows the dispersion time (stirring time) in the dispersion treatment S2 and the increased water content ΔW in the aqueous phase dispersed organic solution L3 when the aqueous solution A corresponding to 3000 volume ppm is added to the water-removed organic solution L2. It is a figure which showed the relationship of.

The increased water content ΔW in the aqueous phase dispersed organic solution L3 is the water content Wa of the sampled organic phase (that is, the aqueous phase dispersed organic solution L3) and the background water content W _b (that is, the water removing organic solution L2 ₎ described later. It can be calculated from the difference in water content W).
Specifically, the increased water content ΔW in the aqueous phase dispersed organic solution L3 can be calculated from the following formula 1) or the following formula 2).

ΔW = {W _a × (V _org + V _aq ) −W _b × V _org } / (V _org + V _aq ) ・ ・ ・ Equation 1)

In the case of V _org >> V _aq ,

_{ΔW≈W a-W b ...} Equation 2)

Can be approximated.

As shown in FIG. 2, in the initial stage of stirring, the water content ΔW increased by the addition of the aqueous phase increases with the increase of the stirring time, and it is considered that it takes about 5 minutes to stabilize. Therefore, when a predetermined amount of the aqueous solution A is added under the above conditions, it is preferable to perform sampling after stirring for 5 minutes or more.

Further, the sampling location is preferably at least one-third the height from the bottom of the water-removing organic solution L2 in the container containing the water-removing organic solution L2. The reason for this is that when the aqueous solution A is difficult to disperse in the water-removing organic solution L2, the specific gravity of the aqueous solution A may be larger than that of the organic solution, and in this case, the aqueous solution A tends to be unevenly distributed toward the bottom. Because.

(Measurement of moisture content W)
The water content W ( _Wb , Wa, _Wrm ) of the prepared first water-removing organic solution L2, aqueous phase-dispersed organic solution L3, and second water-removing organic solution L4 is determined by the Karl Fisher method (based on JIS _K0113 ). Can be measured.

In particular, even if the dissolved water that can be centrifuged is removed by the centrifugation treatment S1, the water cannot be completely removed, and a certain amount of water molecules are present in the first water-removing organic solution L2. Therefore, the moisture content W in the first moisture-removing organic solution L2 is measured using a Karl Fisher Moisture Meter, and the background existing in the first moisture-removing organic solution L2 that cannot be completely removed by the centrifugation treatment S1. It is desirable to know the moisture content Wb of.

Further, the water content _ΔWrm increased from the water content _Wb of the first water-removing organic solution L2 in the second water-removing organic solution L4 can be calculated from the following formula 3) or the following formula 4). ..
In the formula, V _aq1 is the added volume of the added aqueous solution A, _Vorg1 is the volume of the prepared first water-removing organic solution L2, and _Vorg2 is the prepared second water-removing organic. The volume of solution L4.

ΔW _rm = (W _rm × V _org2 -W _b × V _org1 ) / _Vorg2 ... Equation 3)

In the case of V _org1 >> V _aq1 , V _org1 ≈ V _org2 .

ΔW _rm ≒ W _rm −W _b・ ・ ・ Equation 4)

Can be approximated.

(Calculation of inverse micelle conversion rate _Erm )
First, the water content W0 obtained from (volume of the added aqueous solution A) / {(volume of the first water-removing organic solution L2) + (volume of the added aqueous solution A) _} is calculated by the following formula 5) or 6). Calculated from.
In the ideal state where the added aqueous solution A is uniformly dispersed, the water content _W0 is obtained no matter where the sample is sampled.

W ₀ = V _aq1 / ( _Vorg1 + V _aq1 ) ... Equation 5)

In the case of V _org1 >> V _aq1

W ₀ ≒ V _aq1 / V _org1 ... Equation 6)

Can be approximated.
Further, the same result can be obtained by using (ΔW _rm × V _org2 + V _aq2 ) instead of V _aq1 .

Using the above water content W ₀ and the water content ΔW _rm increased from the water content W _b of the first water removal organic solution L2 in the second water removal organic solution L4, the inverse micelle formation rate E _rm is calculated by the following formula. Obtained by 7).

E _rm = ΔW _rm / W ₀ ... Equation 7)

Since the dispersed state of the aqueous solution A may not always be uniform, it is preferable to perform sampling a plurality of times and obtain an average value for evaluation. Further, in order to improve the accuracy of the measured value of the Karl Fischer moisture meter, it is desirable to use the average value measured a plurality of times.

Then, the inverse micelle conversion rate _Erm in which the aqueous solution A dispersed in the organic phase exists in the form of the inverse micelle of fine droplets can be easily calculated.
The aqueous solution A dispersed in the organic phase L is contained in the form of fine droplets, and corresponds to the entrainment in the organic phase in the solvent extraction method. The entrainment existing in the form corresponds to a finer droplet that is difficult to be separated from the organic phase in the general centrifugations S1 and S3.
That is, by using the above method, it becomes possible to easily grasp the inverted micelle-ized emulsion, which was difficult to grasp by the conventional method. Then, based on the calculated reverse micelle formation rate _Erm , the reverse micelle formation-causing substance M can be appropriately specified. In other words, a substance that affects the formation of reverse micelles, which is a minute entrainment (reverse micelle formation-causing substance M), is easily identified based on the increase or decrease in the calculated value of the reverse micelle formation rate _Erm . You can do it.

As described above, by adding sulfolane to the organic phase in the solvent extraction method, it becomes possible to suppress the formation of reverse micelles, which is a kind of entrainment generated by the extraction operation. Moreover, if the substance M that causes the formation of reverse micelles that contributes to the formation of reverse micelles is identified and the amount of sulfolane added is adjusted based on the relationship with such the substance, the formation of reverse micelles can be suppressed more appropriately. Will be.

Moreover, if it is possible to suppress the formation of the reverse micelle-ized entrainment existing in the organic phase in the solvent extraction method, fine impurities (form of reverse micelle formation) in industrial products, which have been difficult to grasp in the past, can be suppressed. Since it becomes possible to appropriately suppress the minute entrainment existing in the above, it becomes possible to appropriately manage high-quality industrial products. For example, when cobalt is separated and recovered from a cobalt-containing nickel chloride aqueous solution by solvent-extracting cobalt using an organic phase containing an amine-based extractant to produce a cobalt chloride aqueous solution, an organic containing an amine-based extractant is used. By adding a predetermined amount of sulfolane to the phase, it is possible to suppress a small amount of nickel contained in the form of a reverse micelle in the cobalt chloride aqueous solution during operation, so the quality of the cobalt chloride aqueous solution is appropriately controlled so as to be in a high state. You will be able to.

Hereinafter, examples of the present invention will be shown and more specifically described. The present invention is not limited to the following examples.

(Experiment 1)
In Experiment 1, it was confirmed that sulfolane itself is not caused by the formation of reverse micelles.
A predetermined amount is separated from an organic solvent (trade name Swazole 1800 manufactured by Maruzen Petroleum Co., Ltd.) (corresponding to the organic phase L0 of the present embodiment) containing an amine-based extractant TNOA (Farmin T-08 manufactured by Kao Co., Ltd.). Sulfolane (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd., model number 195-05703) was added to the separated organic solvent to prepare an organic solution (corresponding to the separated organic solution L1 of the present embodiment).
The prepared organic solution was centrifuged (rotation speed 3000 rpm, treatment time 10 minutes) using a centrifuge (5220 manufactured by Kubota Shoji Co., Ltd.) (corresponding to the centrifuge treatment S1 of the present embodiment). The aqueous phase separated by centrifugation was removed to prepare a 25 mL organic phase (corresponding to the first water-removing organic solution L2 of the present embodiment).
It should be noted that the enanthic acid described later (corresponding to the reverse micelle formation-causing substance M of the present embodiment) is not contained.
10 μL was collected from the prepared organic phase (corresponding to the first water-removing organic solution L2 of the present embodiment) using a macrosyring, and the water content was W with a Karl Fisher Moisture Meter (MKH-710M manufactured by Kyoto Electronics Industry Co., Ltd.). _b was measured.

Subsequently, this organic phase (corresponding to the first water-removing organic solution L2 of the present embodiment) is a nickel chloride solution containing cobalt as the extraction starting solution of the solvent extraction step corresponding to 3000 volume ppm of the organic phase as the aqueous phase. After adding (corresponding to the aqueous solution A of the present embodiment), stirring was performed at room temperature (about 25 ° C.) at a rotation speed of 800 rpm for 10 minutes (corresponding to the dispersion treatment S2 of the present embodiment) to disperse the nickel chloride solution. An organic phase (aqueous phase dispersed organic solution L3 of the present embodiment) was prepared.
From this prepared organic phase (aqueous phase dispersed organic solution L3 of the present embodiment), 10 μL of the organic phase was sampled using _a macrosyringe, and the moisture content Wa was measured using a Karl Fischer moisture meter.

Next, this organic phase (aqueous phase dispersed organic solution L3 of the present embodiment) is centrifuged again (corresponding to the centrifugal separation treatment S3 of the present embodiment) to separate the aqueous phase from the organic phase, and then centrifuged again. Separation was performed to prepare an organic phase (second water-removing organic solution L4 of the present embodiment).
From this prepared organic phase (second water-removing organic solution L4 of the present embodiment), 10 μL of the organic phase was collected with a macrosyringe.
For the water content W of the collected organic phase, the water content W _rm was measured with a Karl Fischer moisture meter.

Then, for the organic phase in which the nickel chloride solution was dispersed (the aqueous phase dispersed organic solution L3 of the present embodiment), the inverse micelle formation rate _Erm was calculated by the above formula 7).

(Experimental result)
The result of the experiment (1) is shown in FIG.
FIG. 3 shows the relationship between the concentration of sulfolane added to the organic phase (mmol / L) and the reverse micelle formation rate (%) of minute entrainments in the organic phase. Under any of the conditions (0 mmol / L, 0.7 mmol / L, 2.5 mmol / L, 3.5 mmol / L, 7.0 mmol / L), reverse micelle formation hardly occurred regardless of the addition of sulfolane. rice field. That is, it was confirmed that sulfolane itself does not cause reverse micelles.

(Experiment 2)
To an organic solvent obtained by separating a predetermined amount from an organic solvent containing an amine-based extractant TNOA (Farmin T-08 manufactured by Kao Co., Ltd.), 3.5 mmol / L of enanthic acid is added to an organic solution (preparation of the present embodiment). The inverse micelle formation rate (%) was calculated by the same method as in the experiment (1) except that (corresponding to the organic solution L1) was prepared.
The amount of sulfolane added was 0 mmol / L, 0.35 mmol / L, 1.41 mmol / L, 2.47 mmol / L, and 3.50 mmol / L. That is, it was added so as to be 0 equivalent, 0.1 equivalent, 0.4 equivalent, 0.7 equivalent, and 1 equivalent with respect to 1 equivalent of heptanic acid, respectively.

(Experimental result)
The result of the experiment (2) is shown in FIG.
FIG. 4 shows the relationship between the concentration of sulfolane added to the organic phase (mmol / L) and the reverse micelle formation rate (%) of minute entrainments in the organic phase.
As shown in FIG. 4, when the amount of sulfolane added is zero, the addition of enanthic acid results in a reverse micelle formation rate of more than 80%, so that enanthic acid is the causative substance (causative substance) of reverse micelles. It could be confirmed.
Then, as the sulfolane concentration increases, the reverse micelle formation rate decreases, and the formation of reverse micelles is completely suppressed at a concentration of 3.5 mmol / L, which is equivalent to the addition of heptanic acid and an equivalent amount of sulfolane. did it.

The method for suppressing the formation of reverse micelles in the solvent extraction method of the present invention is a method for suppressing the formation of entrainments existing in the form of reverse micelle formation in the organic phase in the solvent extraction used in wet smelting of non-ferrous metals. Are suitable.

A aqueous solution L1 preparative organic solution L2 first water removal organic solution L3 aqueous phase dispersion organic solution L4 second water removal organic solution M reverse micelle formation causative substance S1 centrifuge treatment S2 water solution dispersion treatment S3 second centrifuge treatment W Moisture rate _Erm inverse micelle formation rate

Claims (10)

It is a method of suppressing the formation of reverse micelles in the solvent extraction method.
A method for suppressing reverse micelle formation in a solvent extraction method, which comprises adding sulfolane to an organic phase used in an extraction process. The sulfolane is
The solvent extraction method according to claim 1, wherein 0.1 equivalent or more is added to 1 equivalent of the reverse micelle formation-causing substance contained in the organic phase before the extraction treatment. Method of suppressing reverse micelle formation in. The method for suppressing reverse micelle formation in the solvent extraction method according to claim 2, wherein the substance causing reverse micelle formation is specified based on the reverse micelle formation rate _Erm . The reverse _{micelleization} rate Erm is
The organic solution used for the organic phase is separated, and the separated organic solution is subjected to centrifugation to remove water to prepare a predetermined amount of the first water-removing organic solution, and the first water removal is performed. After preparing an aqueous phase-dispersed organic solution in which a predetermined amount of an aqueous solution is added to the organic solution and dispersed, the aqueous phase-dispersed organic solution is subjected to centrifugation to remove water to prepare a second water-removing organic solution. death,
The water content of the first water-removing organic solution is W _b , and the water content of the second water-removing organic solution is W _rm .
The water content _ΔWrm increased from the water content _Wb of the first water-removing organic solution in the second aqueous phase dispersed organic solution was obtained.
Obtain the water content W0 from (volume of the aqueous solution) / _{ (volume of the first water-removing organic solution) + (volume of the aqueous solution)}.
Calculated based on the ratio of the water content W _rm and the water content W ₀ ,
The substance causing the reverse micelle formation is
The third aspect of claim 3, wherein the specification is made based on the reverse micelle formation rate _Erm when added to any one or more of the organic solution, the preparative organic solution, and the aqueous solution. A method for suppressing reverse micelle formation in the solvent extraction method of. The method for suppressing reverse micelle formation in the solvent extraction method according to claim 3 or 4, wherein the reverse micelle formation rate _Erm is calculated by the following formula.
E _rm = ΔW _rm / W ₀
The upper limit of the amount of sulfolane added is
The method for suppressing reverse micelle formation in the solvent extraction method according to claim 1 to 5, wherein the amount is 10 equivalents or less with respect to 1 equivalent of the substance causing reverse micelle formation. The sulfolane is
The method for suppressing reverse micelle formation in the solvent extraction method according to claim 1 to 6, wherein the substance is added to the organic phase before the extraction treatment. The organic phase is
The method for suppressing reverse micelle formation in the solvent extraction method according to claim 1 to 7, which comprises an organic extractant which is a phosphoric acid ester-based acidic extractant or an amine-based extractant. The method for suppressing reverse micelle formation in the solvent extraction method according to claim 1 to 8, wherein the substance causing reverse micelle formation is heptonic acid. The method for suppressing reverse micelle formation in the solvent extraction method according to claim 1 to 9, wherein the solvent extraction method is a method used for hydrometallurgy of nonferrous metals.

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