JPH0878042A - Manufacture of electrolyte of redox flow type cell - Google Patents

Abstract

PURPOSE: To provide an electrolyte for a redox flow type cell with high charge/ discharge efficiency by mixing an organic solvent to a hydrochloric acid aqueous solution containing chromium ions and impurity metal ions and extracting the impurity metal ions with the organic solvent for removing. CONSTITUTION: Ferrochrome and the like is dissolved in a specified concentration of hydrochloric acid aqueous solution to prepare a hydrochloric acid aqueous solution containing chromium ions and other impurity metal ions, and this hydrochloric acid aqueous solution is mixed with an organic solvent comprising an organic extraction agent (trioctylmethylammonium chloride and the like) and a diluent (kerosine and the like), and the impurity metal ions are extracted in the organic solvent. The organic solvent is separated from the chromium- containing hydrochloric acid aqueous solution, and a specified concentration of hydrochloric acid aqueous solution is added to the organic solvent to extract Fe ions contained in the organic solvent. The hydrochloric acid aqueous solution containing Fe ions is separated from the organic solvent, mixed with the Cr ion-containing hydrochloric acid aqueous solution to use as an electrolyte of a redox flow type cell. The electrolyte with high charge/discharge efficiency is easily, simply manufactured at low cost.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an electrolytic solution for a redox flow type battery.

[0002]

2. Description of the Related Art The growth of power demand in Japan continues to increase with the years, but the fluctuation of power demand tends to be remarkable year by year, reflecting the sophistication of the industrial structure and the improvement of national living standards. .

For example, assuming that the daytime power demand in summer is 100, that at dawn is 30 or less.

On the other hand, from the viewpoint of power supply, the proportion of nuclear power generation, large-scale thermal power generation, and large-scale hydroelectric power generation, whose output fluctuations are not desirable, tends to increase, so that there is a need for a facility for storing power. It is rising.

Current electric power storage is performed by pumped storage power generation, but it is said that there is a high possibility of realizing a new electric power storage technology, especially technically and economically, due to its limited location. Secondary batteries are being actively researched,
Among them, redox flow type batteries have been particularly attracting attention.

Next, the structure and operating principle of the redox flow type battery will be described below. FIG. 6 is a configuration diagram schematically showing a specific example of a redox flow battery.

Referring to FIG. 6, this redox flow type battery 31 comprises a battery reaction cell 32, a positive electrode liquid tank 33, and a negative electrode liquid tank 34.

The inside of the battery reaction cell 32 is partitioned by a diaphragm 35 made of, for example, an ion exchange membrane, and one side constitutes a positive electrode cell 32a and the other side constitutes a negative electrode cell 32b.

A positive electrode 36 is accommodated in the positive electrode cell 32a, and a negative electrode 37 is accommodated in the negative electrode cell 32b.

The positive electrode cell 32a and the positive electrode liquid tank 33 are
A positive electrode liquid supply conduit 38 for supplying the positive electrode electrolyte solution from the positive electrode liquid tank 33 to the positive electrode cell 32a and a positive electrode liquid recovery conduit 39 for recovering the positive electrode electrolyte solution from the positive electrode cell 32a to the positive electrode liquid tank 33 are connected. It

A pump 40 is provided in the positive electrode liquid supply conduit 38 as a circulating means for circulating the positive electrode electrolytic solution, and the positive electrode electrolytic solution flows between the positive electrode cell 32a and the positive electrode liquid tank 33. It can be circulated.

On the other hand, the negative electrode cell 32b and the negative electrode liquid tank 34
Means that the negative electrode electrolyte is supplied from the negative electrode liquid tank 34 to the negative electrode cell 32.
and a negative electrode liquid supply conduit 41 for supplying the negative electrode liquid to b, and a negative electrode liquid recovery conduit 42 for recovering the negative electrode electrolyte solution from the negative electrode cell 32b to the negative electrode liquid tank 34.

A pump 43 is provided in the negative electrode liquid supply conduit 41 as a means for circulating and circulating the negative electrode electrolytic solution, and the negative electrode electrolytic solution flows between the negative electrode cell 32b and the negative electrode liquid tank 34. It can be circulated.

A positive electrode electrolyte solution is stored in the positive electrode solution tank 43, and a negative electrode electrolyte solution is stored in the negative electrode solution tank 34.

As the positive electrode electrolyte, for example, an aqueous solution of ions whose valence changes, such as iron ions, is used.
Further, as the negative electrode electrolyte, for example, an aqueous solution of ions whose valence changes such as chromium ions is used.

For example, as such a positive electrode electrolyte, an aqueous hydrochloric acid solution containing a positive electrode active material Fe ³⁺ / Fe ²⁺ is used in view of characteristics such as iron solubility and charge / discharge reaction rate.

As the negative electrode electrolyte, the negative electrode active material Cr ²⁺ /
A hydrochloric acid aqueous solution containing Cr ³⁺ is used.

Redox flow using such an electrolytic solution
The negative electrode liquid tank is used when charging with the battery cell 31.
Cr stored in C34³⁺Aqueous hydrochloric acid solution containing ions
It is sent to the negative electrode cell 32b by the pump 43, and the negative electrode 37
Received electrons at Cr ²⁺Reduced to ions, negative
It is collected in the polar liquid tank 34.

On the other hand, Fe stored in the positive electrode liquid tank 33
^The hydrochloric acid aqueous solution containing ²⁺ ions is sent to the positive electrode cell 32a by the pump 40, releases electrons to the external circuit at the positive electrode 36, is oxidized to Fe ³⁺ , and is collected in the positive electrode liquid tank 33.

During discharge, the negative electrode liquid tank 3
The hydrochloric acid aqueous solution containing the Cr ²⁺ ions stored in 4 is sent to the negative electrode cell 32b by the pump 43, releases electrons to the external circuit at the negative electrode 37, is oxidized to Cr ³⁺ ions, and is stored in the negative electrode liquid tank 34. Be recovered.

On the other hand, Fe stored in the positive electrode liquid tank 33
^The hydrochloric acid aqueous solution containing ³⁺ ions is sent to the positive electrode cell 32a by the pump 40, receives electrons from the external circuit at the positive electrode 36 and is reduced to Fe ²⁺ ions, and the positive electrode liquid tank 33
Will be collected.

In such a redox flow battery, the charge / discharge reaction at the positive electrode 36 and the negative electrode 37 is
It becomes like the following formula.

[0023]

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The electric power surplus at night is converted into alternating current through an inverter 44, and then charged into a redox flow type battery, and the reaction in the charging direction of the above formulas (1) and (2) causes Fe ³⁺ / Cr. ^{Stored in 2+} form.

When the electric power becomes insufficient during the daytime, the electric power is discharged by the reaction in the discharge direction of the above equations (1) and (2), orthogonally converted by the inverter 44, and then supplied to the electric power system.

This is an electric power storage system using a redox flow battery. By the way, as mentioned above,
As the electrolytic solution used in the redox flow battery, an aqueous hydrochloric acid chloride solution is used because of its characteristics such as the solubility of iron and chromium and the charge / discharge reaction rate.

Of these, in particular, the aqueous hydrochloric acid solution containing chromium (Cr) uses high-purity electrolytic chromium in order to suppress the generation of hydrogen, which is a side reaction, and since it is expensive, redox flow is used. This is a big problem in putting the type battery into practical use.

As a technique for solving such a problem, there is a method for producing an electrolytic solution for a redox flow type battery, which comprises producing an aqueous hydrochloric acid solution containing chromium (Cr) from inexpensive chromium ore, a reduced substance of chromium ore, ferrochrome and the like. Various proposals have been made.

A method for producing an electrolytic solution for such a redox flow battery is disclosed in, for example, JP-A-60-115.
There is an invention as described in Japanese Patent Publication No. 174.

The method for producing an electrolyte for a redox flow battery described in JP-A-60-115174 uses a chromium ore or the like as a starting material, and dissolves the chromium ore or the like in hydrochloric acid to form chromium (Cr) ions. And a step of preparing a hydrochloric acid aqueous solution (hereinafter referred to as raw material hydrochloric acid aqueous solution) containing impurity metal ions other than chromium (Cr) ions, and introducing the raw material hydrochloric acid aqueous solution into the cathode chamber of the electrolytic cell to perform electrolysis. A step of electrodepositing an impurity metal on the electrode of the cathode chamber to remove impurity metal ions other than chromium (Cr) ions contained in the raw hydrochloric acid aqueous solution and taking out a hydrochloric acid aqueous solution containing chromium (Cr) ions as an electrolytic solution. It has and.

Further, in Japanese Patent Laid-Open No. 63-76268, a reduction product of chromium ore and / or ferrochrome is dissolved in hydrochloric acid in an atmosphere in which oxygen gas is blocked, and thereafter,
There has been proposed a method for producing an electrolyte solution for a redox flow battery, in which a residue is filtered off under an atmosphere in which oxygen gas is blocked.

According to JP-A-63-76268,
By carrying out the dissolution operation of dissolving the chromium ore reduced product, ferrochrome in hydrochloric acid, with the oxygen gas blocked,
Iron (Fe) is dissolved in the form of divalent ions, and chromium (Cr) is dissolved in the form of divalent or trivalent ions, and the potential of the solution obtained by this dissolving operation is based on a saturated ampholytic electrode.
Since the electric potential becomes baser than 0.4 V, it is said that the chromium ore reduction product and the impurity metal contained in ferrochrome are difficult to dissolve in the solution.

As a result, the electrolyte solution of the redox flow type battery described in JP-A-63-76268 is acceptable as the electrolyte solution of the redox flow type battery because the concentration of the impurity metal ions contained in the electrolyte solution is acceptable. It is said that the concentration will be less than the concentration of impurity metal ions.

Further, according to Japanese Patent Laid-Open No. 63-76268, when a chromium ore reduction product and ferrochrome are dissolved in hydrochloric acid, a conductive carbon material is allowed to coexist during the dissolution operation, so that only a slight amount is dissolved during the dissolution operation. It is said that the impurity metal can be removed from the solution by precipitating the impurity metal ions thus formed on the surface of the conductive carbon material according to the following equation.

M ^{n +} + nCr ²⁺ → M ↓ + nCr ^{3+ In} the above formula, M represents an impurity metal.

[0036]

As described above, in the method for producing an electrolytic solution for a redox flow battery by dissolving high-purity electrolytic chromium in hydrochloric acid, the starting high-purity electrolytic chromium is expensive. Therefore, there is a problem that the manufacturing cost of the electrolytic solution becomes high, and as a result, the manufacturing cost of the power storage system becomes high, and the economical efficiency of the power storage system cannot be obtained.

Further, as described in JP-A-60-115174 and JP-A-63-76268, redox flow can be obtained from inexpensive starting materials such as chrome ore, chrome ore reduction product, and ferrochrome. Although the method of electrochemically producing the electrolytic solution of the alkaline battery has the effect of reducing the production cost of the electrolytic solution, removal of impurity metal ions, particularly manganese (Mn) ions mixed in the electrolytic solution is not possible. However, the electrolytic solution produced according to these methods has a drawback that the negative electrode has a side reaction such as generation of hydrogen and the like, and the charge / discharge efficiency is low.

The present invention has been made to solve the above problems. That is, the first invention is a method for producing an electrolytic solution of a redox flow battery using a hydrochloric acid aqueous solution containing chromium (Cr) ions as an electrolytic solution, which comprises chromium (Cr) and an impurity metal other than chromium (Cr). An aqueous hydrochloric acid solution containing chromium (Cr) ions and impurity metal ions is prepared from an inexpensive raw material containing and, and the impurity metal ions are easily and easily used as an electrolytic solution for a redox flow battery from the aqueous hydrochloric acid solution. It is an object of the present invention to provide a method capable of separating and removing impurities at a concentration not higher than an allowable concentration of impurity metal ions.

Further, the second invention or the fourth invention is a method for producing an electrolytic solution of a redox flow type battery, which uses an aqueous hydrochloric acid solution containing iron (Fe) ions as an electrolytic solution. An aqueous hydrochloric acid solution containing iron (Fe) ions and impurity metal ions is prepared from an inexpensive raw material containing an impurity metal other than iron (Fe), and the impurity metal ions are easily and easily prepared from the aqueous hydrochloric acid solution. It is an object of the present invention to provide a method capable of separating and removing impurity metal ions at a concentration equal to or lower than the concentration allowed as an electrolytic solution of a redox flow battery.

In the third or fifth invention, a hydrochloric acid aqueous solution containing iron (Fe) ions is used as an electrolytic solution as the positive electrode active material, and chromium (C) is used as the negative electrode active material.
r) A method for producing an electrolytic solution of a redox flow battery, which uses an aqueous hydrochloric acid solution containing ions as an electrolytic solution,
Containing iron (Fe) ions, chromium (Cr) ions and impurity metal ions from an inexpensive raw material containing iron (Fe), chromium (Cr) and iron (Fe) and impurity metals other than chromium (Cr) To provide a method capable of easily and easily separating and removing the impurity metal ions from the hydrochloric acid aqueous solution to a concentration equal to or lower than the concentration of the impurity metal ions allowed as the electrolytic solution of the redox flow battery. To aim.

More specifically, the object of the present invention is to obtain, among the impurity metals contained in inexpensive raw materials, the conventional method:
Regarding manganese (Mn), which was technically impossible,
An object of the present invention is to provide a method for producing an electrolyte solution for a redox flow battery, which can separate and remove to a concentration not higher than an allowable concentration as an electrolyte solution for a redox flow battery.

[0042]

The inventors of the present invention are technically impossible by the conventional method among the impurity metals contained in inexpensive raw materials such as chromium ore, reduced products of chromium ore, and ferrochrome. Also, manganese (Mn) has been researched for many years on a method for producing an electrolyte solution for a redox flow battery, which can separate and remove manganese (Mn) to a concentration below an allowable concentration as an electrolyte solution for a redox flow battery.

As a result, by using the solvent extraction method, among the impurity metals contained in the inexpensive raw material, manganese (Mn), which was technically impossible by the conventional method, is also used in the redox flow battery. The inventors have found that they can be separated and removed to a concentration not higher than the concentration allowed as the electrolytic solution of, and have completed the present invention.

That is, the method for producing an electrolytic solution for a redox flow battery according to the first invention is a method for producing an electrolytic solution for a redox flow battery using an aqueous hydrochloric acid solution containing chromium (Cr) ions as an electrolytic solution. A step of preparing an aqueous hydrochloric acid solution containing chromium (Cr) ions and impurity metal ions other than chromium (Cr) ions; and mixing an organic solvent with the aqueous hydrochloric acid solution to remove the impurity metal ions contained in the aqueous hydrochloric acid solution from the organic solvent. And then extracted into an organic solvent containing impurity metal ions and an aqueous hydrochloric acid solution containing chromium (Cr) ions to separate chromium (Cr)
And a step of taking out an aqueous hydrochloric acid solution containing ions as an electrolytic solution.

The aqueous hydrochloric acid solution containing chromium (Cr) ions and impurity metal ions other than chromium (Cr) ions is used as a starting material for chromium ore, reduced products of chromium ore, ferrochrome, wastes containing chromium (Cr), and the like. Raw materials,
It may be dissolved in hydrochloric acid. The waste containing chromium (Cr) includes, for example, a chromium (Cr) waste liquid generated at the time of dyeing with a mordant dye, as well as chromium (Cr),
Examples include various industrial wastes.

The organic solvent is a quaternary ammonium compound such as trioctylmethylammonium chloride,
Tertiary amines such as trioctylamine, tri-n-butyl phosphate, trioctylphosphine oxide,
It contains an extracting agent (extracting reagent) selected from the group consisting of organic phosphoric acid compounds such as bis (2,4,4-trimethylpentyl) octylphosphine oxide.

The organic solvent more preferably contains trioctylmethylammonium chloride as an extractant.

Further, the chlorine concentration of the aqueous hydrochloric acid solution containing chromium (Cr) ions and impurity metal ions ([C
l ^-]), the kind of organic solvent varies depending on the kind of the starting material, the case of using an organic solvent containing the above-mentioned extractant (extraction reagent), but are not limited to the case, especially below, For example, 300 grams (g) / liter (li
ter) or less, more preferably 230 g (g) / liter (liter) or less. Incidentally, chromium (Cr) concentration of chlorine hydrochloric aqueous solution containing ions and impurity metal ions ([Cl ^-]) is diluted and with water, the chlorine concentration adjusting consisting chlorides represented by calcium chloride (CaCl ₂₎ It may be adjusted by adding an agent.

The concentration of hydrochloric acid aqueous solution containing chromium (Cr) ions and impurity metal ions ([HCl])
Is 1.5 mol (mol) / in consideration of workability, etc.
It is preferably from liter (liter) to 3.5 mol (mol) / liter (liter).

A method for producing an electrolytic solution for a redox flow battery according to a second aspect of the present invention is a method for producing an electrolytic solution for a redox flow battery using an aqueous hydrochloric acid solution containing iron (Fe) ions as an electrolytic solution. A step of preparing a first hydrochloric acid aqueous solution containing (Fe) ions and an impurity metal ion other than iron (Fe) ions; mixing an organic solvent with the first hydrochloric acid aqueous solution; A step of extracting contained iron (Fe) ions and impurity metal ions into an organic solvent; and mixing an organic solvent containing iron (Fe) ions and impurity metal ions with a second aqueous hydrochloric acid solution containing no metal ions. The iron (Fe) ion contained in the organic solvent is extracted into the second hydrochloric acid aqueous solution, and thereafter, the organic solvent containing the impurity metal ion and the hydrochloric acid aqueous solution containing the iron (Fe) ion are extracted. Apart, and a step of taking out the aqueous hydrochloric acid solution containing iron (Fe) ions as an electrolytic solution.

The first hydrochloric acid aqueous solution containing iron (Fe) ions and impurity metal ions other than iron (Fe) ions is, for example, iron ore casting, chrome ore reduction product, ferrochromium, iron casting produced from a machine factory or the like. Starting materials such as iron scraps such as shavings, iron ore, and wastes containing iron (Fe) may be dissolved in hydrochloric acid. The waste containing iron (Fe) includes, for example, an etching solution containing iron (Fe), which is generated when a copper (Cu) wiring such as a printed circuit board is produced, and various kinds of waste containing iron (Fe). Industrial waste can be mentioned.

The organic solvent is a quaternary ammonium compound such as trioctylmethylammonium chloride,
Tertiary amines such as trioctylamine, tri-n-butyl phosphate, trioctylphosphine oxide,
It contains an extracting agent (extracting reagent) selected from the group consisting of organic phosphoric acid compounds such as bis (2,4,4-trimethylpentyl) octylphosphine oxide.

The organic solvent more preferably contains trioctylmethylammonium chloride as an extractant.

The chlorine concentration of the first hydrochloric acid aqueous solution containing iron (Fe) ions and impurity metal ions ([C
l ^-]), the kind of organic solvent varies depending on the kind of the starting material, the case of using an organic solvent containing the above-mentioned extractant (extraction reagent), but are not limited to the case, especially below, For example, 300 grams (g) / liter (li
ter) or less, more preferably 230 g (g) / liter (liter) or less.

The chlorine concentration of the first hydrochloric acid aqueous solution containing iron (Fe) ions and impurity metal ions ([C
l ^-]) is diluted and with water, calcium chloride (CaC
It may be adjusted by adding a chlorine concentration adjusting agent consisting of chloride represented by l ₂ ).

The concentration of the first hydrochloric acid aqueous solution containing iron (Fe) ions and impurity metal ions ([HCl])
Is 1.5 mol (mol) / in consideration of workability, etc.
It is preferably from liter (liter) to 3.5 mol (mol) / liter (liter).

The hydrochloric acid concentration ([HCl]) of the second hydrochloric acid aqueous solution containing no metal ion is 0.01 mol (mo
It is preferable that the ratio is l) / liter (liter) or more and 1.5 mol (mol) / liter (liter) or less.

In the method for producing an electrolytic solution for a redox flow battery according to the third invention, iron (Fe) is used as the positive electrode active material.
A method for producing an electrolytic solution for a redox flow battery, which uses an aqueous hydrochloric acid solution containing ions as an electrolytic solution and uses an aqueous hydrochloric acid solution containing chromium (Cr) ions as an electrolytic solution as a negative electrode active material. Ions, chromium (Cr) ions, and a step of preparing a first hydrochloric acid aqueous solution containing iron (Fe) ions and impurity metal ions other than chromium (Cr) ions, and an organic solvent in the first hydrochloric acid aqueous solution. After mixing, the iron (Fe) ion and the impurity metal ion contained in the first aqueous hydrochloric acid solution are extracted into an organic solvent, and thereafter, an organic solvent containing the iron (Fe) ion and the impurity metal ion, and chromium. A step of separating the aqueous hydrochloric acid solution containing (Cr) ions and taking out the aqueous hydrochloric acid solution containing chromium (Cr) ions as an electrolytic solution;
e) An organic solvent containing ions and impurity metal ions is mixed with a second aqueous hydrochloric acid solution containing no metal ions, and iron (Fe) ions contained in the organic solvent are extracted into the second aqueous hydrochloric acid solution. Then, a step of separating the organic solvent containing the impurity metal ions and the aqueous hydrochloric acid solution containing the iron (Fe) ions and taking out the aqueous hydrochloric acid solution containing the iron (Fe) ions as an electrolytic solution is provided.

The first hydrochloric acid aqueous solution containing iron (Fe) ions, chromium (Cr) ions, and iron (Fe) ions and impurity metal ions other than chromium (Cr) ions is, for example, chromium ore or chromium. Starting materials such as ore reduction products, ferrochrome, and wastes containing chromium (Cr) and iron (Fe) may be dissolved in hydrochloric acid.

The organic solvent is a quaternary ammonium compound such as trioctylmethylammonium chloride,
Tertiary amines such as trioctylamine, tri-n-butyl phosphate, trioctylphosphine oxide,
It contains an extracting agent (extracting reagent) selected from the group consisting of organic phosphoric acid compounds such as bis (2,4,4-trimethylpentyl) octylphosphine oxide.

The organic solvent more preferably contains trioctylmethylammonium chloride as an extractant.

Further, iron (Fe) ions, chromium (Cr)
The chlorine concentration ([Cl ⁻ ]) of the first hydrochloric acid aqueous solution containing ions and impurity metal ions varies depending on the type of organic solvent and the type of starting material. When the organic solvent containing is used, it is not particularly limited to the following cases, but for example, 300
It is preferably adjusted to gram (g) / liter (liter) or less, more preferably 230 gram (g) / liter (liter) or less.

The chlorine concentration of the first hydrochloric acid aqueous solution ([C
Since]) adjustment method is the same as the first invention, ^- l
The description here is omitted.

Further, iron (Fe) ions, chromium (Cr)
The concentration of hydrochloric acid ([HCl]) in the first hydrochloric acid aqueous solution containing ions and impurity metal ions is 1.5 mol (mol) / liter (liter) in consideration of workability.
) Or more and 3.5 mol (mol) / liter (liter) or less.

The hydrochloric acid concentration ([HCl]) of the second hydrochloric acid aqueous solution containing no metal ion is 0.01 mol (mo
It is preferable that the ratio is l) / liter (liter) or more and 1.5 mol (mol) / liter (liter) or less.

A method for producing an electrolytic solution for a redox flow battery according to a fourth aspect of the present invention is a method for producing an electrolytic solution for a redox flow battery using an aqueous hydrochloric acid solution containing iron (Fe) ions as an electrolytic solution. A step of preparing a first hydrochloric acid aqueous solution containing (Fe) ions and an impurity metal ion other than iron (Fe) ions; mixing an organic solvent with the first hydrochloric acid aqueous solution; A step of extracting contained iron (Fe) ions into an organic solvent;
e) An organic solvent containing ions is mixed with a second aqueous hydrochloric acid solution containing no metal ions, iron (Fe) ions contained in the organic solvent are extracted into the second aqueous hydrochloric acid solution, and then an organic solvent is added. And a step of separating the aqueous hydrochloric acid solution containing iron (Fe) ions, and taking out the aqueous hydrochloric acid solution containing iron (Fe) ions as an electrolytic solution.

In the fourth invention, the step of preparing the first aqueous hydrochloric acid solution containing iron (Fe) ions and impurity metal ions other than iron (Fe) ions is the same as in the second invention. The description here is omitted.

The organic solvent used in the fourth invention may be any organic solvent used in the second invention.

In the fourth invention, in particular, manganese (Mn) is efficiently separated and removed to a concentration equal to or lower than the concentration allowed as an electrolyte for redox flow type batteries, to efficiently produce an electrolyte for redox flow type batteries. To this end, it is more preferable to use an organic solvent containing tri-n-butyl phosphate as the extractant.

The chlorine concentration of the first hydrochloric acid aqueous solution containing iron (Fe) ions and impurity metal ions ([C
l ^-]), the kind of organic solvent varies depending on the kind of the starting material, the case of using an organic solvent containing the above-mentioned extractant (extraction reagent), but are not limited to the case, especially below, For example, 300 grams (g) / liter (li
ter) It is preferably adjusted to the following.

The chlorine concentration ([C
The method of adjusting l ⁻ ]) is the same as the method already described in the second aspect of the invention, so description thereof will be omitted here.

The chlorine concentration of the first hydrochloric acid aqueous solution containing iron (Fe) ions and impurity metal ions ([HC
l]) is 1 mol in consideration of workability and the like.
/ Liter (liter) or more and 5 mol (mol) / liter (liter) or less is preferable.

The hydrochloric acid concentration ([HCl]) of the second hydrochloric acid aqueous solution containing no metal ion is 0.01 mol (mo
It is preferable that the ratio is l) / liter (liter) or more and 1.5 mol (mol) / liter (liter) or less.

In the method for producing an electrolytic solution for a redox flow battery according to the fifth aspect of the present invention, iron (Fe) is used as the positive electrode active material.
A method for producing an electrolytic solution for a redox flow battery, which uses an aqueous hydrochloric acid solution containing ions as an electrolytic solution and uses an aqueous hydrochloric acid solution containing chromium (Cr) ions as an electrolytic solution as a negative electrode active material. Ion, chromium (Cr) ion, and a step of preparing a first hydrochloric acid aqueous solution containing iron (Fe) ions and impurity metal ions other than chromium (Cr) ions; An organic solvent is mixed, iron (Fe) ions and impurity metal ions contained in the first hydrochloric acid aqueous solution are extracted into the first organic solvent, and thereafter, iron (Fe) ions and impurity metal ions are contained. The first organic solvent to be used, and chromium (C
r) a step of separating an aqueous hydrochloric acid solution containing ions and taking out an aqueous hydrochloric acid solution containing chromium (Cr) ions as an electrolytic solution; a first organic solvent containing iron (Fe) ions and impurity metal ions Is mixed with a second aqueous hydrochloric acid solution containing no metal ions to extract iron (Fe) ions and impurity metal ions contained in the first organic solvent into the second aqueous hydrochloric acid solution, and then the first Organic solvent and iron (Fe)
A step of separating a second aqueous hydrochloric acid solution containing ions and impurity metal ions to prepare an aqueous hydrochloric acid solution containing iron (Fe) ions and impurity metal ions; and iron (Fe)
In a hydrochloric acid aqueous solution containing ions and impurity metal ions,
A second organic solvent is mixed, iron (Fe) ions contained in the hydrochloric acid aqueous solution are extracted into the second organic solvent, and thereafter, a hydrochloric acid aqueous solution containing impurity metal ions and iron (Fe) ions are contained. A step of separating the second organic solvent and a second organic solvent containing iron (Fe) ions are mixed with a third hydrochloric acid aqueous solution containing no metal ions to be contained in the second organic solvent. The iron (Fe) ion is extracted into the third hydrochloric acid aqueous solution, and then the second organic solvent and the hydrochloric acid aqueous solution containing the iron (Fe) ion are separated to obtain the hydrochloric acid containing the iron (Fe) ion. And a step of taking out the aqueous solution as an electrolytic solution.

In the fifth invention, iron (Fe) ions,
A step of preparing a first hydrochloric acid aqueous solution containing chromium (Cr) ions and iron (Fe) ions and impurity metal ions other than chromium (Cr) ions; and a first organic solvent in the first hydrochloric acid aqueous solution To extract the iron (Fe) ions and the impurity metal ions contained in the first hydrochloric acid aqueous solution into the first organic solvent, and thereafter to contain the iron (Fe) ions and the impurity metal ions. Organic solvent and chromium (C
The step of separating the r) ion-containing hydrochloric acid aqueous solution and taking out the chromium (Cr) ion-containing hydrochloric acid aqueous solution as the electrolytic solution is the same as that of the first invention, and therefore the description thereof is omitted here.

In the fifth invention, the first organic solvent containing iron (Fe) ions and the impurity metal ions is mixed with the second aqueous hydrochloric acid solution containing no metal ions, and the mixture is added to the first organic solvent. The contained iron (Fe) ions and impurity metal ions are extracted into the second aqueous hydrochloric acid solution. This is because the fifth invention is particularly effective in that manganese (Mn) is the electrolytic solution of the redox flow battery. This is for efficiently producing the electrolyte solution of the redox flow type battery that has been separated and removed to a concentration not higher than the allowable concentration.

That is, the iron (Fe) ions and the impurity metal ions contained in the first organic solvent are extracted into the second hydrochloric acid aqueous solution, and then the first organic solvent, the iron (Fe) ions and the impurity metal ions are extracted. The second hydrochloric acid aqueous solution containing the ions is separated from the second hydrochloric acid aqueous solution containing the iron (Fe) ions and the impurity metal ions to obtain a chlorine concentration ([C
l ^-]) and a respective concentration of hydrochloric acid ([HCl]),
The second organic solvent is adjusted to have a concentration at which iron (Fe) ions are selectively extracted, and an aqueous hydrochloric acid solution containing iron (Fe) ions and impurity metal ions is prepared.

The second organic solvent is mixed with a hydrochloric acid aqueous solution containing iron (Fe) ions and impurity metal ions, and the iron (Fe) ions contained in the hydrochloric acid aqueous solution are mixed with the second organic solvent. The step of extracting and then separating the aqueous hydrochloric acid solution containing the impurity metal ions and the second organic solvent containing the iron (Fe) ions, and the second organic solvent containing the iron (Fe) ions into the metal A third aqueous hydrochloric acid solution containing no ions is mixed to produce iron (F) contained in the second organic solvent.
e) extraction of the ions into a third aqueous hydrochloric acid solution, followed by a second extraction
The step of separating the organic solvent from the aqueous hydrochloric acid solution containing iron (Fe) ions and taking out the aqueous hydrochloric acid solution containing iron (Fe) ions as an electrolytic solution is the same as in the fourth invention. The description of is omitted.

The term "first hydrochloric acid aqueous solution" used in the fifth invention corresponds to the "hydrochloric acid aqueous solution" of the first invention, and the term "first organic solvent" used in the fifth invention is The term "hydrochloric acid aqueous solution containing iron (Fe) ions and impurity metal ions", which corresponds to the "organic solvent" of the first invention and is used in the fifth invention, means the "iron (Fe) ions of the fourth invention. And the impurity metal ions are contained in the first hydrochloric acid aqueous solution ", and the term" second organic solvent "used in the fifth invention corresponds to the" organic solvent "in the fourth invention. It should be additionally noted that the term "third hydrochloric acid aqueous solution" used in the invention corresponds to the "second hydrochloric acid aqueous solution" of the fourth invention.

Any of the first organic solvent and the second organic solvent used in the fifth invention is applicable as long as it is the organic solvent used in the first invention.

The first organic solvent used in the fifth invention more preferably contains trioctylmethylammonium chloride as an extracting agent, and the second organic solvent is more preferably tri-n- as an extracting agent. Contains butyl phosphate.

The concentration of the second hydrochloric acid aqueous solution used in the fifth invention is not particularly limited, but in consideration of workability, it is 1.5 mol (mol) / liter (liter) or more. 3.5 mol / liter (liter
) It is preferable that it is the following.

[0083]

In all of the present inventions, the solvent extraction method is used in the step of producing the electrolytic solution of the redox flow battery.

The solvent extraction method is also called a liquid-liquid extraction method,
It is a method that utilizes the distribution of substances between two liquid phases that do not mix with each other.

4 and 5 are diagrams schematically showing the principle of solvent extraction according to the present invention. Referring to FIG.
The operation of the first to third inventions will be described below.

The first invention comprises the following steps. (1) A step of preparing an aqueous hydrochloric acid solution containing chromium (Cr) ions and impurity metal ions other than chromium (Cr) ions is provided.

(2) An organic solvent is mixed with a hydrochloric acid aqueous solution,
The impurity metal ions contained in the hydrochloric acid aqueous solution are extracted into an organic solvent, and then the organic solvent containing the impurity metal ions and the hydrochloric acid aqueous solution containing chromium (Cr) ions are separated to obtain chromium (Cr) ions. And a step of taking out an aqueous hydrochloric acid solution containing

Referring to FIG. 4, the first invention applies the extraction process. That is, in an aqueous hydrochloric acid solution (raw hydrochloric acid aqueous solution) containing chromium (Cr) ions and impurity metal ions other than chromium (Cr) ions, an organic solvent containing an extracting agent (indicated by an organic solvent (extracting agent) in FIG. 4). The chlorine concentration ([Cl
^- ]), Or solutes such as iron (Fe) ions and manganese (Mn) ions contained in the starting hydrochloric acid aqueous solution, depending on the type of organic solvent, include an organic solvent containing an extractant (organic solvent in FIG. 4). (Indicated by (extracting agent)).

When this step (hereinafter referred to as “washing step”) is repeated several times, chromium (Cr) ions remain on the aqueous solution phase side, and the concentration of impurity metal ions contained on the aqueous solution phase side becomes
The concentration is less than the concentration of impurity metal ions that is allowed as the electrolytic solution of the redox flow battery.

Next, a hydrochloric acid aqueous solution (aqueous solution phase) containing chromium (Cr) ions is taken out as an electrolytic solution to obtain an electrolytic solution for a redox flow battery.

The second invention comprises the following steps. (1) A step of preparing a first hydrochloric acid aqueous solution containing iron (Fe) ions and impurity metal ions other than iron (Fe) ions is provided.

(2) A step of mixing an organic solvent with the first hydrochloric acid aqueous solution and extracting iron (Fe) ions and impurity metal ions contained in the first hydrochloric acid aqueous solution into the organic solvent is provided.

(3) An organic solvent containing iron (Fe) ions and impurity metal ions is mixed with a second aqueous hydrochloric acid solution containing no metal ions to remove the iron (Fe) ions contained in the organic solvent. 2 into the aqueous hydrochloric acid solution, and then the organic solvent containing the impurity metal ions and the aqueous hydrochloric acid solution containing the iron (Fe) ions are separated, and the aqueous hydrochloric acid solution containing the iron (Fe) ions is used as the electrolytic solution. Equipped with a process of taking out.

Referring to FIG. 4, the second invention is an application of the back extraction process. That is, in FIG. 4, first,
By the extraction step, an organic solvent containing an extracting agent is added to an aqueous hydrochloric acid solution (raw hydrochloric acid aqueous solution) containing iron (Fe) ions and impurity metal ions other than iron (Fe) ions (in FIG. 4, the organic solvent (extracting agent When mixing the indicated is) in), chlorine concentration of the raw material aqueous hydrochloric acid ([Cl ^-]) and, depending on the type of the organic solvent, the iron contained in the raw material aqueous hydrochloric acid (Fe) ions and manganese (Mn) ions Impurities such as metal ions are extracted to the side of the organic solvent containing the extractant (indicated by the organic solvent (extractant) in FIG. 4).

Next, iron (Fe) ions and manganese (M
n) When an organic solvent containing an impurity metal ion such as an ion is mixed with a second hydrochloric acid aqueous solution containing no metal ion, iron () contained in the organic solvent depends on the hydrochloric acid concentration of the second hydrochloric acid aqueous solution. Fe) ions are extracted into the second aqueous hydrochloric acid solution.

Then, the organic solvent containing the impurity metal ions and the aqueous hydrochloric acid solution containing the iron (Fe) ions are separated, and the aqueous hydrochloric acid solution containing the iron (Fe) ions is taken out as an electrolytic solution.

Further, the third invention comprises the following steps. (1) A step of preparing a first hydrochloric acid aqueous solution containing iron (Fe) ions, chromium (Cr) ions, and iron (Fe) ions and impurity metal ions other than chromium (Cr) ions is provided.

(2) An organic solvent is mixed with the first hydrochloric acid aqueous solution, iron (Fe) ions and impurity metal ions contained in the first hydrochloric acid aqueous solution are extracted into the organic solvent, and then iron (Fe) is added. A step of separating the organic solvent containing the ions and the impurity metal ions from the hydrochloric acid aqueous solution containing the chromium (Cr) ions and taking out the aqueous hydrochloric acid solution containing the chromium (Cr) ions as an electrolytic solution is provided.

(3) An organic solvent containing iron (Fe) ions and impurity metal ions is mixed with a second aqueous hydrochloric acid solution containing no metal ions to remove the iron (Fe) ions contained in the organic solvent. 2 into the aqueous hydrochloric acid solution, and then the organic solvent containing the impurity metal ions and the aqueous hydrochloric acid solution containing the iron (Fe) ions are separated, and the aqueous hydrochloric acid solution containing the iron (Fe) ions is taken out as the electrolytic solution. It has a process.

Referring to FIG. 4, the third invention applies the extraction process and the back extraction process.

In the third invention, the principle of the extraction step is the same as that of the first invention, and the principle of the back extraction step is the same as that of the second invention, so the description thereof will be omitted.

Next, referring to FIG. 5, the operation of the fourth to fifth inventions will be described below.

The fourth invention comprises the following steps. (1) A step of preparing a first hydrochloric acid aqueous solution containing iron (Fe) ions and impurity metal ions other than iron (Fe) ions is provided.

(2) A step of mixing an organic solvent with the first hydrochloric acid aqueous solution and extracting iron (Fe) ions contained in the first hydrochloric acid aqueous solution into the organic solvent is provided.

(3) An organic solvent containing iron (Fe) ions is mixed with a second aqueous hydrochloric acid solution containing no metal ions, and the iron (Fe) ions contained in the organic solvent are mixed in a second aqueous hydrochloric acid solution. To the organic solvent and iron (F
e) Separation from an aqueous hydrochloric acid solution containing ions to obtain iron (F
e) A step of extracting an aqueous hydrochloric acid solution containing ions as an electrolytic solution.

Referring to FIG. 5, the principle of solvent extraction shown by A in FIG. 5 is the same as that of the first invention, and therefore the description thereof is omitted here.

In FIG. 5, the principle of solvent extraction shown in B is as follows:
The fourth invention comprises a step of extraction and a step of back extraction.

That is, referring to B in FIG. 5, first,
Through the extraction step, the first hydrochloric acid aqueous solution (raw hydrochloric acid aqueous solution) containing iron (Fe) ions and impurity metal ions other than iron (Fe) ions is added to the organic solvent containing the extraction agent (see FIG. 5).
Among, when mixing the indicated are) in an organic solvent (extractant), chlorine concentration of the raw material aqueous hydrochloric acid ([Cl ^-]) and, depending on the type of the organic solvent, the iron contained in the raw material aqueous hydrochloric acid (F
e) The ions are selectively extracted with an organic solvent (FIG. 5).
Inside, the organic solvent (shown by the extraction agent) is extracted.

Next, when the second hydrochloric acid aqueous solution containing no metal ions is mixed with the organic solvent selectively extracted with iron (Fe) ions, depending on the chlorine concentration of the second hydrochloric acid aqueous solution, Iron (Fe) ions contained in the organic solvent are extracted into the second aqueous hydrochloric acid solution.

Then, the organic solvent and the aqueous hydrochloric acid solution containing iron (Fe) ions are separated, and the aqueous hydrochloric acid solution containing iron (Fe) ions is taken out as an electrolytic solution.

In the fourth invention, as described above,
An electrolyte solution for a redox flow battery is manufactured by the extraction step and the back extraction step.

In particular, the fourth invention includes a step of separating iron (Fe) ions and impurity metal ions other than iron (Fe) ions by the extraction step. Even manganese (Mn), which was impossible, can be easily separated and removed to a concentration not higher than the concentration allowed as an electrolytic solution of a redox flow battery.

Further, the fifth invention comprises the following steps. (1) A step of preparing a first hydrochloric acid aqueous solution containing iron (Fe) ions, chromium (Cr) ions, and iron (Fe) ions and impurity metal ions other than chromium (Cr) ions is provided.

(2) Iron (Fe) contained in the first hydrochloric acid aqueous solution by mixing the first organic solvent with the first hydrochloric acid aqueous solution.
Ions and impurity metal ions are extracted in a first organic solvent, and then a first organic solvent containing iron (Fe) ions and impurity metal ions and an aqueous hydrochloric acid solution containing chromium (Cr) ions are extracted. A step of separating and taking out a hydrochloric acid aqueous solution containing chromium (Cr) ions as an electrolytic solution is provided.

(3) Iron contained in the first organic solvent is obtained by mixing the first organic solvent containing iron (Fe) ions and the impurity metal ions with the second aqueous hydrochloric acid solution containing no metal ions. (Fe) ions and impurity metal ions
In a hydrochloric acid aqueous solution of, followed by the first organic solvent,
Second containing iron (Fe) ions and impurity metal ions
And a step of separating the aqueous hydrochloric acid solution to prepare an aqueous hydrochloric acid solution containing iron (Fe) ions and impurity metal ions.

(4) A second organic solvent is mixed with a hydrochloric acid aqueous solution containing iron (Fe) ions and impurity metal ions, and the iron (Fe) ions contained in the hydrochloric acid aqueous solution are mixed in the second organic solvent. And then separating the aqueous hydrochloric acid solution containing the impurity metal ions from the second organic solvent containing the iron (Fe) ions.

(5) Second containing iron (Fe) ion
And a third hydrochloric acid aqueous solution containing no metal ions are mixed with the organic solvent to extract the iron (Fe) ions contained in the second organic solvent into the third hydrochloric acid aqueous solution, and then the second organic solvent is added. A step of separating the solvent and the aqueous hydrochloric acid solution containing iron (Fe) ions and taking out the aqueous hydrochloric acid solution containing iron (Fe) ions as an electrolytic solution is provided.

Referring to FIG. 5, the fifth invention is a combination of the first invention and the fourth invention.

Referring to FIG. 5, the principle of the solvent extraction indicated by A in FIG. 5 is the same as that of the first invention as described above, but in the step of back extraction of A in FIG. A first organic solvent containing iron (Fe) ions and impurity metal ions (indicated by an organic solvent (extracting agent) in FIG. 5) is mixed with a second aqueous hydrochloric acid solution containing no metal ions, The iron (Fe) ion and the impurity metal ion contained in the first organic solvent are extracted into the second hydrochloric acid aqueous solution, and then the first organic solvent, the iron (Fe) ion and the impurity metal ion are contained. It is separated from the second aqueous hydrochloric acid solution.

In the fifth invention, the chlorine concentration ([Cl ⁻ ]) of the second aqueous hydrochloric acid solution containing iron (Fe) ions and impurity metal ions is determined in the step of extracting B in FIG. In the second organic solvent, iron (Fe) ions contained in the aqueous hydrochloric acid solution are selectively added to the organic solvent containing the extracting agent (indicated by the organic solvent (extracting agent) in FIG. 5). It is adjusted to be extracted.

Referring to FIG. 5, the principle of solvent extraction shown by B in FIG. 5 is the same as that of the fourth invention, and therefore its explanation is omitted.

[0122]

The present invention will be described in more detail with reference to the following examples.

Example 1 FIG. 1 is a process chart schematically showing a process for producing an electrolytic solution for a redox flow battery according to the present invention.

Referring to FIG. 1, the steps shown in steps (1) to (6) outline the method for producing an aqueous hydrochloric acid solution containing chromium (Cr) ions as an electrolytic solution for a redox flow battery. It is shown in the figure.

Referring to FIG. 1, first, in the step shown in step (1), starting materials are prepared. The starting material is not particularly limited to the following cases, but examples thereof include ferrochrome, chrome ore, and chrome ore reduced product.

When the starting material is solid, it may be crushed to have an appropriate particle size, if necessary.

Next, the starting material is dissolved in an aqueous hydrochloric acid solution.
This step may be normally performed in the air (in an oxygen atmosphere).

Chromium (Cr) and iron (F
e) reacts and dissolves in the air, for example, according to the reaction formula shown below.

[0129]

Embedded image

As a starting material, chromite (chro
In the case of using mite), for example, carbon (C) and chlorine gas (Cl ₂ ) are used and reacted and dissolved according to the reaction formula shown below.

[0131]

[Chemical 3]

In this step, in the hydrochloric acid aqueous solution, copper (Cu) contained in the starting raw material, in addition to chromium (Cr) and iron (Fe), varies depending on the type of raw material.
Elements such as manganese (Mn), cobalt (Co), and zinc (Zn) dissolve as impurity metal ions.

Next, in the process shown in step (2), iron (Fe) is obtained by filtering off residues such as carbon and silica which are contained in the starting material and are insoluble in hydrochloric acid.
Ion, chromium (Cr) ion, and aqueous hydrochloric acid solution containing impurity metal ions such as copper (Cu) ion, manganese (Mn) ion, cobalt (Co) ion, and zinc (Zn) ion (hereinafter referred to as raw hydrochloric acid solution). ) Is produced.

Next, in the step shown in step (3), an organic solvent is mixed with the raw hydrochloric acid aqueous solution prepared in step (2).

The organic solvent is iron (Fe) ions, and impurity metal ions such as copper (Cu) ions, manganese (Mn) ions, cobalt (Co) ions, and zinc (Zn) ions from the above raw material hydrochloric acid aqueous solution. Is used to extract.

The organic solvent usually contains an organic extractant and a diluent although it varies depending on the kind of the organic solvent.

In addition to the organic extractant and the diluent, the organic solvent is a component for solubilizing the intermediate product generated in the extraction reaction in the diluent and preventing the formation of the third phase or emulsion. The third different from the above-mentioned organic extractant and diluent
It may also contain a modifier which is an organic component of

The organic extractant is a drug (extracting reagent) for extracting metal ions contained in an aqueous hydrochloric acid solution into an organic solvent.

That is, the metal ions in the hydrochloric acid aqueous solution are
Since it has an electric charge and holds hydration water in an aqueous hydrochloric acid solution, it cannot be extracted into an organic solvent having a small polarity in this state.

The following two conditions are necessary for incorporating the metal ions in the aqueous hydrochloric acid solution into the organic solvent (organic phase).

Condition 1: Neutralize the charge of the metal ion to form an uncharged chemical species. Condition 2: Water of hydration coordinated to metal ions should be removed as much as possible.

When these two conditions are satisfied, the metal ions can be transferred into the organic solvent (organic phase).

The organic extractant is a drug used for binding the metal ion to give hydrophobicity and to give the above two conditions.

In this example, the organic extractant is not particularly limited to the following cases, but examples thereof include the extraction reagents shown below.

[0145]

[Chemical 4]

[Wherein R ¹ , R ² , and R ³ are R ¹ = R ^{2
_{= R 3 = CH 3 (CH}} 2) 7 - is a radical of the general name: trioctylmethylammonium chloride (Trioct
yl methylammonium chloride) Product name: Aliquat 336 (Henckel (He
nkel) manufactured) Abbreviation: TOMAC

[0147]

[Chemical 5]

[Wherein R ¹ , R ² , and R ³ are R ¹ = R ^{2
_{= R 3 = CH 3 (CH}} 2) 7 - is a radical of the general name: tri -n- octylamine (Trioctyl amine) Product Name: Alamine (Alamine) 336 (Henkel (Henk
el) product) Abbreviation: TOA

[0149]

[Chemical 6]

[Wherein R ¹ , R ² , and R ³ are R ¹ = R ²
= R ³ = C ₄ H ₉ is a group represented O-,] Generic name: tri n- butyl phosphate (Tri-n-butyl-ph
osphate) Abbreviation: TBP

[0151]

[Chemical 7]

[Wherein R ¹ , R ² , and R ³ are R ¹ = R ^{2
_{= R 3 = C 8 H 17}} - is a group represented by] Generic name: trioctyl phosphine oxide (Trioctyl
phosphine oxide) Molecular weight (MW): 386 External form: Off-white waxy solid (off-
white waxy solid) Physical properties: Solid mass at room temperature (Solid mass) Product name: Cyanex 921 (manufactured by Mitsui Cyanamid) Abbreviation: TOPO

[0153]

Embedded image

[Wherein R ¹ , R ² , and R ³ are R ¹ = R ^{2
_{= R 3 = C 8 H 17}} - is a group represented by] Generic name: bis (2,4,4-trimethylpentyl) octyl phosphine oxide (Bis (2,4,4-TriMet
hylpentyl) octyl phosphine oxide) Molecular weight (MW): 386 External form: colorless to pale amber liquid (Colorless to
light amber liquid)

[0155]

[Chemical 9]

[Wherein R ¹ , R ² , and R ³ are R ¹ = R ²
= R ³ = alkyl group] General name: mixture of trialkylphosphine oxide Average molecular weight (average MW): 348 External form: colorless to pale amber liquid (Colorless to
Light amber liquid) TOPO is a solid at room temperature and is very difficult to handle.

The compound shown in Chemical formula 8 and the compound shown in Chemical formula 9 are extraction reagents similar to TOPO.

The diluent is used for accelerating the separation of the organic solvent (organic phase) and the hydrochloric acid aqueous solution (aqueous phase) when the specific gravity of the above organic extractant is close to the specific gravity of the hydrochloric acid aqueous solution. .

As the diluent, an organic solvent insoluble in water is selected. Examples of such diluents include kerosene, hexane, benzene, chloroform, carbon tetrachloride and the like.

Examples of the modifying agent include 2ethyl-hexanol, nonylphenol, isodecanol, hexanol, dodecanol and the like.

As the organic extractant, the above chemical formulas 4-9 are used.
The reason for choosing was for the following reasons.

FIG. 3 shows a hydrochloric acid aqueous solution containing metal ions,
It is a figure which shows one specific example of the relationship with the extraction rate with respect to each metal of an organic solvent.

More specifically, FIG. 3 shows a specific example of the relationship between the aqueous solution (aqueous phase) having the following composition and the extraction ratio of each organic solvent (organic phase) having the composition to each metal. It is a figure which shows an example.

Composition of organic solvent (organic phase): Alamine 336 25% dodecanol (dodecanol) 15% Kerosene Remainder Composition of aqueous solution (aqueous phase): [Me] = 1 gram (g) / liter (liter) pH : ~ 2 CaCl ₂ solution [Me] represents various metals ionized and dissolved in the aqueous solution (aqueous phase).

CaCl ₂ was used to adjust the chlorine concentration ([Cl ⁻ ]) in the aqueous solution (aqueous phase).

Further, in FIG. 3, Alamine 3
One specific example of the organic solvent containing 36 is shown, but the above-mentioned organic solvent containing the extracting agent shown in Chemical formulas 4 and 6 to 9 shows a tendency similar to the extraction characteristics shown in FIG. Please note that.

In the step shown in step (3), the chlorine concentration ([Cl ⁻ ]) of the starting hydrochloric acid aqueous solution is 30
It is preferably 0 grams (g) / liter (liter) or less, and more preferably 230 grams (g) / liter (liter) or less.

In the step (3), the mixed solution of the raw material hydrochloric acid aqueous solution and the organic solvent may be stirred by using a known shaker or stirrer if necessary.

Referring again to FIG. 3, the concept of the present invention will be described. When the chlorine concentration ([Cl ⁻ ]) is 230 g (g) / liter (liter) or less, chromium in the starting hydrochloric acid aqueous solution is used. Almost no (Cr) ions are extracted into the organic solvent.

On the other hand, iron (Fe) ions and copper (C
u) ion, manganese (Mn) ion, cobalt (C
Impurity metal ions such as o) ions and zinc (Zn) ions have a chlorine concentration of 230 g (g) / liter (lite).
r) Extracted into organic solvent even if:

Next, in the step shown in step (4), by leaving the mixed solution of the raw material hydrochloric acid aqueous solution and the organic solvent for a while, a hydrochloric acid aqueous solution (aqueous solution phase) containing chromium (Cr) ions and iron ( Fe) ion, and
It is separated into an organic solvent (organic phase) containing impurity metal ions such as copper (Cu) ions, manganese (Mn) ions, cobalt (Co) ions, and zinc (Zn) ions.

Next, in the step shown in step (5), an aqueous hydrochloric acid solution containing chromium (Cr) ions is taken out, and copper (Cu) ions contained in the aqueous hydrochloric acid solution are added.
The amounts of impurity metal ions such as manganese (Mn) ions, cobalt (Co) ions, and zinc (Zn) ions are measured.

Then, in the step shown in step (5),
Copper (Cu) ions and manganese (Mn) contained in the extracted hydrochloric acid aqueous solution containing chromium (Cr) ions.
Each of the concentrations of impurity metal ions such as ions, cobalt (Co) ions, and zinc (Zn) ions is allowed as an electrolytic solution of a redox flow type battery. Copper (Cu) ions, manganese (Mn) ions, cobalt ( It is compared with the respective concentrations of impurity metal ions such as Co) ions and zinc (Zn) ions.

The respective concentrations of impurity metal ions such as copper (Cu) ions, manganese (Mn) ions, cobalt (Co) ions and zinc (Zn) ions contained in the aqueous hydrochloric acid solution containing chromium (Cr) ions are determined. When the concentration of the impurity metal ions allowed as the electrolyte solution of the redox flow battery is less than or equal to, the hydrochloric acid aqueous solution containing chromium (Cr) ions is added to the electrolyte solution of the redox flow battery electrolyte in the step (6). Take out as.

The electrolytic solution obtained in this example may contain an organic substance (extractant or the like).
When it is necessary to remove the organic matter contained in the electrolytic solution, it is effective to pass the electrolytic solution containing the organic matter through activated carbon and to carry out an activated carbon treatment such as removing the organic matter contained in the electrolytic solution. .

On the other hand, copper (Cu) ions, manganese (Mn) ions, cobalt (Co) ions and zinc (Z) contained in the aqueous hydrochloric acid solution containing chromium (Cr) ions.
n) the respective concentrations of impurity metal ions such as ions are
When the concentration of the impurity metal ions is higher than the allowable concentration of the electrolytic solution for the redox flow battery, this hydrochloric acid aqueous solution is used as the starting hydrochloric acid aqueous solution, and the steps (2), (3) and (4) are performed once for one cool. A washing process is performed, and in step (5), copper (Cu) ions contained in a hydrochloric acid aqueous solution containing chromium (Cr) ions are again added,
It is determined whether the concentration of each impurity metal ion such as manganese (Mn) ion, cobalt (Co) ion, and zinc (Zn) ion is less than or equal to the impurity metal ion concentration allowed as the electrolytic solution of the redox flow battery.

In the cleaning step in which the steps (2), (3) and (4) are one cool, copper (Cu) ions contained in an aqueous hydrochloric acid solution containing chromium (Cr) ions,
Repeatedly until the concentration of each impurity metal ion such as manganese (Mn) ion, cobalt (Co) ion, zinc (Zn) ion becomes equal to or less than the concentration of the impurity metal ion allowed as the electrolyte of the redox flow battery. Done.

Referring again to FIG. 1, step (7)
The steps shown in (8) and (9) schematically show a method for producing an aqueous hydrochloric acid solution containing iron (Fe) ions as an electrolytic solution of a redox flow battery.

Referring to FIG. 1, first, in the step shown in step (7), iron (Fe) ions and copper (C) are added.
u) ion, manganese (Mn) ion, cobalt (C
o) Extraction of an organic solvent containing impurity metal ions such as ions and zinc (Zn) ions.

Next, in the step shown in step (8), iron (Fe) ions and impurity metals such as copper (Cu) ions, manganese (Mn) ions, cobalt (Co) ions and zinc (Zn) ions are used. An aqueous hydrochloric acid solution containing no metal ions is mixed with an organic solvent containing ions.

In the step shown in step (8), the hydrochloric acid concentration ([HC
l]) is 0.5 mol (mol) / liter (liter) or more and 1.5 mol (mol) / liter (liter) or less, iron (Fe) ions contained in the organic solvent are metal ions. It is extracted into a hydrochloric acid aqueous solution containing no.

In the step (8), iron (Fe) ions, copper (Cu) ions, manganese (Mn) ions, cobalt (Co) ions, zinc (Z)
n) a mixed solution of an organic solvent containing an impurity metal ion such as an ion and an aqueous hydrochloric acid solution containing no metal ion,
If necessary, using a known shaker or stirrer,
You may stir.

Next, in the process shown in step (9), iron (Fe) ions and impurity metals such as copper (Cu) ions, manganese (Mn) ions, cobalt (Co) ions, and zinc (Zn) ions are used. By leaving a mixed solution of an organic solvent containing ions and a hydrochloric acid aqueous solution containing no metal ions for a while, a hydrochloric acid aqueous solution (aqueous phase) containing iron (Fe) ions, copper (Cu) ions, manganese ( (Mn) ions, cobalt (Co) ions, zinc (Zn) ions, and other organic solvent (organic phase) containing impurity metal ions, and then an aqueous hydrochloric acid solution containing iron (Fe) ions is taken out as an electrolytic solution. .

The electrolytic solution obtained in this example may contain organic substances (extractants, etc.).
When it is necessary to remove the organic matter contained in the electrolytic solution, it is effective to pass the electrolytic solution containing the organic matter through activated carbon and to carry out an activated carbon treatment such as removing the organic matter contained in the electrolytic solution. .

An aqueous hydrochloric acid solution containing chromium (Cr) ions produced in the process shown in step (6), and produced in the process shown in step (9),
Each of the hydrochloric acid aqueous solutions containing iron (Fe) ions,
Copper (Cu), manganese (Mn) ions, cobalt (C
o) Since the concentration of each of the impurity metal ions such as ions and zinc (Zn) ions is equal to or lower than the concentration of the impurity metal ions allowed as the electrolytic solution of the redox flow battery, the hydrochloric acid concentration of each hydrochloric acid aqueous solution is It can be preferably used as an electrolytic solution of a redox flow type battery by adjusting or adjusting the chromium (Cr) ion concentration or the iron (Fe) ion concentration.

Further, in the step shown in step (10), an aqueous hydrochloric acid solution containing chromium (Cr) ions produced in the step shown in step (6) and produced in the step shown in step (9), A one-pack type electrolytic solution may be manufactured by mixing with a hydrochloric acid aqueous solution containing iron (Fe) ions.

Referring again to FIG. 1, in the step shown in step (9), the separated organic solvent (organic phase) containing the impurity metal ions is regenerated, and then the step (3) is performed. It can be used again in the steps shown.

More specifically, the organic solvent is regenerated by mixing an aqueous solution of hydrochloric acid with an organic solvent containing impurity metal ions and extracting the impurity metal ions contained in the organic solvent to the aqueous solution phase (aqueous phase) side. be able to.

Next, description will be made using concrete experimental data. Experimental Example 1 Experimental Example 1 shows a process of producing an aqueous hydrochloric acid solution containing chromium (Cr) ions, which can be preferably used as an electrolytic solution of a redox flow battery according to the first invention.

Ferrochrome was used as the starting material,
An aqueous hydrochloric acid solution was added to this, and ferrochrome was dissolved in the aqueous hydrochloric acid solution.

Next, the residues of carbon, silica, etc. contained in the ferrochrome and insoluble in hydrochloric acid were filtered off.

Next, the filtrate was diluted with water to prepare about 1 liter (liter) of a raw material hydrochloric acid aqueous solution having a hydrochloric acid concentration of 2.9 mol (mol) / liter (liter).

Next, the concentration of metal ions contained in this raw material aqueous hydrochloric acid solution was measured by ion chemiluminescence analysis (ICP). The results are shown in Table 1.

[0194]

[Table 1]

Table 2 shows the permissible concentrations of the impurity metal ions allowed as the electrolytic solution of the redox flow battery.

[0196]

[Table 2]

Next, manganese (Mn) ions, cobalt (Co) ions, and copper (C) contained in the raw material hydrochloric acid aqueous solution.
u) An organic solvent was prepared for extracting impurity metal ions such as ions from the starting aqueous solution of hydrochloric acid.

In this experimental example, a mixed solution containing an organic extractant, a diluent and a modifier was used as the organic solvent.

As the organic extractant, a nitrogen-based extraction reagent, more specifically, a quaternary ammonium compound trioctylmethylammonium chloride (trade name "Aliquat 336", manufactured by Henkel) is used. Using.

As a diluent, Solveso (Solv
esso) 150 was used. In addition, Solvesso
The component of 150 is kerosene.
"esso)" is a trade name of Esso.

As the modifier, 2-ethylhexanol was used.

The organic solvent was prepared by the following steps.
First, Solvesso 150 and trioctylmethylammonium chloride are mixed, and then 2
-Ethylhexanol, 2-ethylhexanol,
An organic solvent containing 0.5 mol (mol) / liter (tri) of trioctylmethylammonium chloride was prepared so as to be 20% by volume.

Next, the raw material hydrochloric acid aqueous solution and the organic solvent were mixed at a volume ratio of 1: 2. More specifically, about 200 cc of the organic solvent is added to about 100 cc of the raw material hydrochloric acid aqueous solution.
c were mixed to prepare a mixed solution of a raw material hydrochloric acid aqueous solution and an organic solvent.

Next, a mixture of the starting aqueous solution of hydrochloric acid and the organic solvent is sufficiently stirred using a known shaker or stirrer, and then left for a while to leave the aqueous solution phase and the organic solvent (organic phase). ) And then, the organic solvent (organic phase) was separated and removed, and the aqueous solution phase was taken out.

When an organic solvent containing trioctyl ammonium chloride is used as the organic solvent, the impurity metal ions contained in the starting hydrochloric acid aqueous solution are extracted into the organic solvent, for example, according to the following formula. .

[0206]

[Chemical 10]

In the formula, M represents an impurity metal and R represents CH.
₃ (CH _{2) 7} - is a group represented by, org is an organic phase, aq denotes the aqueous phase.

Regarding the aqueous phase prepared by the above steps, the concentration of metal ions such as manganese (Mn) ions, cobalt (Co) ions and copper (Cu) ions contained in the aqueous phase is determined by ion chemiluminescence analysis. Law (IC
P).

In the measurement by ion chemiluminescence analysis, in order to facilitate comparison with Table 2 above, the concentration of chromium (Cr) ions contained in the analytical sample taken out from the aqueous solution phase was 1. It was adjusted to be 0 mol / liter (liter).

Next, the concentration of impurity metal ions contained in the aqueous solution phase was compared with Table 2. When the concentration of the impurity metal ions contained in the aqueous solution phase is higher than the respective allowable concentrations of the impurity metal ions shown in Table 2, the aqueous solution phase, that is, chromium (Cr) ions and chromium (Cr)
About 200 cc of an organic solvent is newly mixed again with an aqueous hydrochloric acid solution containing an impurity metal ion other than ions, and the mixed solution is stirred and allowed to stand, after which the organic solvent is separated and removed to prepare an aqueous solution. The hydrochloric acid aqueous solution washing step was repeated, with the step of taking out the phases being one cool.

The above hydrochloric acid aqueous solution washing step was carried out at room temperature (RT). In this example, the concentration of impurity metal ions contained in the hydrochloric acid aqueous solution (aqueous solution phase) was below the allowable concentration shown in Table 2 when the above-described hydrochloric acid aqueous solution washing step was performed 10 times.

On the other hand, even after the step of washing the hydrochloric acid aqueous solution was repeated 10 times, the hydrochloric acid aqueous solution still contained chromium (C
r) ion is about 1 mol / mol (liter)
Was included.

Next, by passing the aqueous hydrochloric acid solution containing the chromium (Cr) ions through the activated carbon, the organic matter contained in the aqueous hydrochloric acid solution was adsorbed to the activated carbon and mixed in the above-mentioned aqueous hydrochloric acid solution washing step. The likely organics were removed.

Through the above steps, an aqueous hydrochloric acid solution containing chromium (Cr) ions, which can be suitably used as an electrolytic solution of a redox flow type battery, was obtained.

Experimental Example 2 In Experimental Example 2, iron (Fe) which can be suitably used as an electrolytic solution of a redox flow battery according to the second invention.
A process for producing an aqueous hydrochloric acid solution containing ions will be described.

Next, an organic solvent (organic phase) containing iron (Fe) ions and impurity metal ions other than iron (Fe) separated from the mixed solution prepared in Experimental Example 1 was used as a starting material, and this organic solvent was used. (Organic phase) About 100 cc was mixed with about 100 cc of an aqueous hydrochloric acid solution containing about 0.1 mol (mol) / liter (liter) of hydrochloric acid.

Then, a mixed solution of an organic solvent (organic phase) and an aqueous hydrochloric acid solution containing about 0.1 mol (mol) / liter (liter) of hydrochloric acid was used with a known shaker or stirrer. After sufficiently stirring, the mixture was left to stand to separate into an aqueous phase and an organic phase, and then the organic phase was separated and removed.

Regarding the aqueous solution phase (hydrochloric acid aqueous solution) produced by the above steps, manganese (Mn) ions, cobalt (Co) ions, copper (C
u) The concentration of impurity metal ions such as ions was measured by ion chemiluminescence analysis (ICP).

The results are shown in Table 3.

[0220]

[Table 3]

In order to facilitate the comparison with the above Table 2 in the measurement, when measuring the impurity metal ion concentration in the aqueous solution phase, the iron contained in the analytical sample taken out from the aqueous solution phase was measured. (Fe) ion concentration is 1 mol (mo
It was adjusted to be l) / liter.

The hydrochloric acid aqueous solution containing iron (Fe) ions produced by the above steps is compared with Table 2 and Table 3 to compare manganese (Mn) ions, copper (Cu) ions, cobalt (Co) ions, etc. It was clarified that each of the impurity metal ion concentrations of was less than or equal to the concentration of the impurity metal ions allowed as the electrolytic solution of the redox flow battery.

Next, the hydrochloric acid aqueous solution was passed through activated carbon to adsorb the organic substances contained in the hydrochloric acid aqueous solution onto the activated carbon, and remove the organic substances mixed in the hydrochloric acid aqueous solution.

Through the above steps, iron (F) which can be suitably used as the electrolytic solution of the redox flow type battery is obtained.
e) An aqueous hydrochloric acid solution containing ions was obtained.

Experimental Example 3 and Comparative Example Experimental Example 3 Experimental Example 3 shows an example in which the charge / discharge efficiency of the electrolytic solution of the redox flow type battery manufactured according to the present invention was measured.

Next, the concentration of chromium (Cr) ions in the aqueous hydrochloric acid solution containing the chromium (Cr) ions obtained in Experimental Example 1 was adjusted to 1.0 mol (mol) / liter (liter).

The iron (Fe) ion concentration of the aqueous hydrochloric acid solution containing iron (Fe) ions obtained in Experimental Example 2 was 1.0
It was adjusted to mol / liter.

Chromium (Cr) adjusted as described above
A hydrochloric acid aqueous solution containing ions and a hydrochloric acid aqueous solution containing iron (Fe) ions are mixed at a volume ratio of 1: 1 to mix chromium (Cr) ions and iron (Fe) ions. After the solution is prepared, hydrochloric acid is added to this mixed solution to adjust the hydrochloric acid concentration of this mixed solution to 4N, and this electrolytic solution is used as an electrolytic solution for a redox flow battery, and is composed of a small unit cell. A redox flow type battery was manufactured.

Next, the structure of this single-cell small redox flow type battery will be described below. Carbon cloth was used as an electrode material forming the positive electrode and the negative electrode.

The electrode area of the positive electrode and the negative electrode is 15 cm.
² A cation exchange membrane was used as the diaphragm.

A phenol resin-bonded carbon plate was used as the current collector plate for the single cell. Next, a charge / discharge test was conducted using this single-cell small redox flow battery.

As a result of a charge / discharge experiment at a temperature of 40 ° C. and a current of 0.6 A, the charge / discharge coulombic efficiency of this single-cell small redox flow battery was 97% and the charge / discharge voltage efficiency was 86%.

Comparative Example High-purity electrolytic chromium (Cr) was dissolved in hydrochloric acid to prepare an aqueous hydrochloric acid solution having a chromium (Cr) ion concentration of 1.0 mol (mol) / liter (liter).

Further, iron (Fe) as a special grade reagent is dissolved in hydrochloric acid to give an iron (Fe) ion concentration of 1.0 mol (mol) /
A liter aqueous hydrochloric acid solution was prepared.

Chromium (C
r) An aqueous hydrochloric acid solution containing ions and an aqueous hydrochloric acid solution containing iron (Fe) ions are mixed at a volume ratio of 1: 1 to contain chromium (Cr) ions and iron (Fe) ions. After preparing a mixed solution, a hydrochloric acid is added to this mixed solution to adjust the hydrochloric acid concentration of this mixed solution to 4N, and this electrolytic solution is used as an electrolytic solution of a redox flow type battery to form a single cell. A small redox flow battery was manufactured.

Since the structure of the single-cell small redox flow type battery is the same as that of the single-cell small redox flow type battery used in Experimental Example 3, description thereof will be omitted.

Using this single-cell small-sized redox flow battery, a charge / discharge test was conducted under the same conditions as in Experimental Example 3.

The charge / discharge coulombic efficiency of the comparative example is 97%,
The charge / discharge voltage efficiency was 86%. Experimental Example 3 showed high charge / discharge efficiency similar to that of Comparative Example.

In this experimental example, an organic solvent containing trioctylmethylammonium chloride was used as the organic solvent, but the extraction reagent (organic extractant) shown in Chemical formulas 5 to 9 was used. It should be additionally noted that even when an organic solvent is used, similar effects can be obtained.

Example 2 FIG. 2 is a process diagram schematically showing a process for producing an electrolytic solution for a redox flow battery according to the present invention.

Referring to FIG. 2, the steps shown in steps (1) to (6) outline the method for producing an aqueous hydrochloric acid solution containing chromium (Cr) ions as an electrolytic solution for a redox flow battery. It is shown in the figure. Note that the steps shown in steps (1) to (6) are the same as those in the first embodiment, and thus the description thereof is omitted here.

Example 2 differs from Example 1 in the method of producing an aqueous hydrochloric acid solution containing iron (Fe) ions as an electrolytic solution for a redox flow battery.

Referring again to FIG. 2, step (101)
-The process shown by step (106) has shown roughly the method of manufacturing the hydrochloric acid aqueous solution containing iron (Fe) ion as an electrolytic solution of a redox flow type battery.

Referring to FIG. 2, first, in the step shown in step (7), iron (Fe) ions and copper (C
u) ion, manganese (Mn) ion, cobalt (C
o) organic solvent containing impurity metal ions such as zinc (Zn) ions (indicated by organic solvent A in FIG. 2)
Take out.

Next, in the step shown in step (101), iron (Fe) ions and copper (Cu) ions are added.
An organic solvent containing an impurity metal ion such as manganese (Mn) ion, cobalt (Co) ion, and zinc (Zn) ion (organic solvent A in FIG. 2) is mixed with a hydrochloric acid aqueous solution containing no metal ion.

In the step shown in step (101),
Hydrochloric acid concentration of hydrochloric acid solution containing no metal ions ([HC
l]) is 0.01 mol (mol) / liter (liter)
If the amount is 1.5 mol (mol) / liter (liter) or less, it is contained in the organic solvent (organic solvent A in FIG. 2).
Iron (Fe) ions, copper (Cu) ions, manganese (Mn) ions, cobalt (Co) ions, zinc (Z
n) Impurity metal ions such as ions are extracted into an aqueous hydrochloric acid solution containing no metal ions.

In the step (101), iron (Fe) ions and impurity metal ions such as copper (Cu) ions, manganese (Mn) ions, cobalt (Co) ions and zinc (Zn) ions are used. If necessary, a mixture of an organic solvent containing organic solvent (organic solvent A in FIG. 2) and a hydrochloric acid aqueous solution containing no metal ion may be stirred using a known shaker or stirrer. .

Next, in the process shown in step (102), iron (Fe) ions and copper (Cu) ions are added.
A mixed solution of an organic solvent containing an impurity metal ion such as manganese (Mn) ion, cobalt (Co) ion and zinc (Zn) ion (organic solvent A in FIG. 2) and a hydrochloric acid aqueous solution containing no metal ion is prepared. By leaving it for a while,
Iron (Fe) ions, copper (Cu) ions, manganese (Mn) ions, cobalt (Co) ions, zinc (Z
n) After separating into a hydrochloric acid aqueous solution (aqueous solution phase) containing impurity metal ions such as ions and an organic solvent (organic solvent A in FIG. 2), iron (Fe) ions and copper (Cu) ions, A hydrochloric acid aqueous solution (raw hydrochloric acid aqueous solution) containing impurity metal ions such as manganese (Mn) ions, cobalt (Co) ions, and zinc (Zn) ions is prepared.

Raw materials containing iron and the like may be further dissolved in this raw material hydrochloric acid aqueous solution. Next, the chlorine concentration ([Cl ⁻ ]) of this raw material hydrochloric acid aqueous solution is adjusted to 100 g (g) / liter (liter) or more and 300 g (g) / liter (liter) or less.

Also, the hydrochloric acid concentration ([HC
l]) is adjusted to 1 mol (mol) / liter (liter) or more and 5 mol (mol) / liter (liter) or less.

This is for the purpose of selectively extracting iron (Fe) ions in the organic solvent B in the process shown in step (103).

Next, in the process shown in step (103), iron (Fe) ions and copper (Cu) ions,
An organic solvent (shown as organic solvent B in FIG. 2) is mixed with a hydrochloric acid aqueous solution (raw hydrochloric acid aqueous solution) containing impurity metal ions such as manganese (Mn) ions, cobalt (Co) ions, and zinc (Zn) ions. To do.

In the step shown in step (103),
Iron (Fe) ions contained in the raw hydrochloric acid aqueous solution are selectively extracted into an organic solvent (indicated by organic solvent B in FIG. 2) in the organic solvent (organic solvent B in FIG. 2). To be done.

In the step (103), iron (Fe) ions and impurity metal ions such as copper (Cu) ions, manganese (Mn) ions, cobalt (Co) ions and zinc (Zn) ions are used. If necessary, a mixed solution of a hydrochloric acid aqueous solution containing an organic solvent (indicated by organic solvent B in FIG. 2) may be stirred using a known shaker or stirrer.

Next, in the process shown in step (104), iron (Fe) ions and copper (Cu) ions,
A hydrochloric acid aqueous solution containing impurity metal ions such as manganese (Mn) ions, cobalt (Co) ions, and zinc (Zn) ions, and an organic solvent (indicated by organic solvent B in FIG. 2).
By leaving the mixed liquid with and for a while, iron (Fe)
Ion-containing organic solvent (indicated by organic solvent B in FIG. 2) (organic phase), copper (Cu) ions, manganese (M
Aqueous hydrochloric acid solution containing impurity metal ions such as n) ions, cobalt (Co) ions, and zinc (Zn) ions (see FIG. 2).
Inside, shown as waste liquid). Next, step (10
In the step shown in 5), an aqueous hydrochloric acid solution containing no metal ions is mixed with an organic solvent containing iron (Fe) ions (indicated by organic solvent B in FIG. 2).

In the step shown in step (105),
Hydrochloric acid concentration of hydrochloric acid solution containing no metal ions ([HC
l]) is 0.01 mol (mol) / liter (liter) or more and 1.5 mol (mol) / liter (liter) or less, it is contained in the organic solvent (indicated by organic solvent B in FIG. 2). The iron (Fe) ions are extracted into a hydrochloric acid aqueous solution containing no metal ions.

In the step (105), a mixed solution of an organic solvent containing iron (Fe) ions (indicated by organic solvent B in FIG. 2) and an aqueous hydrochloric acid solution containing no metal ions is prepared. If necessary, a known shaker or a stirrer may be used for stirring.

Next, in the step shown in step (106), an organic solvent containing iron (Fe) ions (in FIG. 2,
By allowing a mixed solution of an organic solvent B) and a hydrochloric acid aqueous solution containing no metal ions to stand for a while, an aqueous hydrochloric acid solution containing iron (Fe) ions (aqueous phase),
Organic solvent (indicated by organic solvent B in FIG. 2) (organic phase)
After separating into and, an aqueous hydrochloric acid solution containing iron (Fe) ions is taken out as an electrolytic solution.

The electrolytic solution obtained in this example may contain an organic substance (extractant or the like). When it is necessary to remove the organic matter contained in the electrolytic solution, it is effective to pass the electrolytic solution containing the organic matter through activated carbon and to carry out an activated carbon treatment such as removing the organic matter contained in the electrolytic solution. .

The aqueous hydrochloric acid solution containing chromium (Cr) ions produced in the step (6) and the aqueous hydrochloric acid solution containing iron (Fe) ions produced in the step (106) Each of them has an impurity metal ion concentration such as copper (Cu) ion, manganese (Mn) ion, cobalt (Co) ion, and zinc (Zn) ion that is allowed as an electrolyte of a redox flow battery. Since it is below the ion concentration, the hydrochloric acid concentration of each hydrochloric acid aqueous solution,
Adjust or adjust chromium (Cr) ion concentration or iron (F
e) It can be suitably used as an electrolytic solution of a redox flow type battery by appropriately adjusting the ion concentration.

Further, in the step shown in step (107), the aqueous hydrochloric acid solution containing chromium (Cr) ions produced in the step shown in step (6) and the iron produced in the step shown in step (106). (Fe)
You may mix with the hydrochloric acid aqueous solution which contains an ion, and may manufacture a one-pack type electrolyte solution.

Referring again to FIG. 2, step (1
The organic solvent A separated in 01) can be regenerated and used again in the step shown in step (3), and in step (106), the separated organic solvent B can be regenerated in step (3). It can be used again in the step shown in (103).

In addition, in the method for producing the electrolyte solution of the redox flow battery shown in Example 2, when manganese (Mn) is contained as an impurity metal ion in the starting material in the step shown in step (1), The organic solvent A is preferably an organic solvent containing trioctylmethylammonium chloride as an extractant, and the organic solvent B is preferably an organic solvent containing tri-n-butyl phosphate as an extractant. Keep it.

Next, description will be made using concrete experimental data. Experimental Example 4 Experimental Example 4 is for confirming that an aqueous hydrochloric acid solution containing iron (Fe) ions, which can be suitably used as an electrolytic solution of a redox flow battery, can be produced according to the fourth invention. It was done to.

In the present experimental example, in order to facilitate the explanation, manganese (from the aqueous hydrochloric acid solution containing iron (Fe) ions and, particularly, manganese (Mn) ions which are difficult to separate and remove as impurity metal ions, was used. An example in which (Mn) is separated and removed is shown.

As a starting material, ferrous chloride (FeC
l ₂ ) and manganese (Mn) are used, an aqueous solution of hydrochloric acid is added thereto, and ferrous chloride (FeCl ₂ ) and manganese (M
n) and were dissolved in an aqueous hydrochloric acid solution.

Next, the concentration of metal ions contained in the raw hydrochloric acid aqueous solution prepared by the above steps was measured by the ion chemiluminescence analysis method (ICP).

The results are shown in Table 4. The hydrochloric acid concentration ([HCl]) of this raw material hydrochloric acid aqueous solution was 4.1 mol (mol)
/ Liter.

[0269]

[Table 4]

Next, the raw material hydrochloric acid solution contained in
An organic solvent was prepared for selectively extracting iron (Fe) ions from the starting aqueous hydrochloric acid solution.

In this experimental example, a mixed solution containing an organic extractant, a diluent and a modifier was used as the organic solvent.

As the organic extractant, a nitrogen-based extraction reagent, more specifically, a tertiary amine compound tri-n-octylamine (trade name "Almine 336", manufactured by Henkel) is used. Was used.

As a diluent, Solveso (Solv
esso) 150 was used. Further, 2ethyl-hexanol was used as a modifier.

The organic solvent was prepared by the following steps.
First, Solvesso 150 and tri-n-octylamine were mixed, and then 2-ethylhexanol was added so that the content of 2-ethylhexanol was 20% by volume, and 0.75 mol (mol) was added. / Liter (lite
An organic solvent containing r-) of tri-n-octylamine was prepared.

Next, the raw material hydrochloric acid aqueous solution and the organic solvent were mixed in a volume ratio of 1: 2. More specifically, about 200 cc of the organic solvent is added to about 100 cc of the raw material hydrochloric acid aqueous solution.
c were mixed to prepare a mixed solution of a raw material hydrochloric acid aqueous solution and an organic solvent.

Next, the mixture of the starting aqueous solution of hydrochloric acid and the organic solvent was thoroughly stirred using a known shaker and left for a while to separate into an aqueous solution phase and an organic solvent (organic phase). did.

Next, iron (Fe) was extracted once with an organic solvent containing tri-n-octylamine, and then ferric chloride ions in the aqueous solution phase (aqueous phase) and the starting aqueous solution of hydrochloric acid were added. Ionized and dissolved manganese (Mn)
Was measured by ion chemiluminescence analysis (ICP).

The results are shown in Table 5.

[0279]

[Table 5]

With reference to Tables 4 and 5, from the results of Tables 4 and 5, tri-n-
Mixing an organic solvent containing octylamine and extracting with the organic solvent once, the organic solvent side is about 10%.
It means that iron (Fe) has been extracted.

On the other hand, it is found that manganese (Mn) is hardly extracted into the organic solvent.

In the following, the step of mixing the starting aqueous hydrochloric acid solution with an organic solvent containing tri-n-octylamine and extracting iron (Fe) into the organic solvent is repeated as many times as necessary, for example, 20 to 20 times. Repeated about 30 times, iron (Fe) is selectively extracted into an organic solvent.

Next, about 100 cc of an organic solvent (organic phase) containing iron (Fe) is added with about 100 mol of an aqueous hydrochloric acid solution containing about 0.1 mol (mol) / liter (liter) of hydrochloric acid.
cc mixed.

Next, a mixture of an organic solvent (organic phase) and an aqueous hydrochloric acid solution containing about 0.1 mol (mol) / liter (liter) of hydrochloric acid was thoroughly stirred using a known shaker. After that, it was left to separate into an aqueous phase and an organic phase, and then the organic phase was separated and removed.

With respect to the aqueous solution phase (hydrochloric acid aqueous solution) produced by the above steps, the concentration of manganese (Mn) ions contained in the aqueous hydrochloric acid solution was measured by ion chemical spectroscopy (I
CP).

The results are shown in Table 6.

[0287]

[Table 6]

In the measurement, in order to facilitate comparison with Table 2 above, manganese (M
n) When measuring the ion concentration, determine the iron (Fe) ion concentration contained in the analytical sample taken out from the aqueous solution phase as 1
It was adjusted to be mol / liter.

The hydrochloric acid aqueous solution containing iron (Fe) ions produced by the above steps shows that the concentration of manganese (Mn) ions is acceptable as an electrolytic solution for redox flow type batteries by comparison with Table 2 and Table 6. It was revealed that the concentration was not higher than the concentration of manganese (Mn) ions.

Next, the aqueous hydrochloric acid solution was passed through activated carbon to adsorb the organic substances contained in the aqueous hydrochloric acid solution onto the activated carbon, and remove the organic substances mixed in the aqueous hydrochloric acid solution.

Through the above steps, iron (F) which can be suitably used as the electrolytic solution of the redox flow type battery is obtained.
e) An aqueous hydrochloric acid solution containing ions was obtained.

According to Experimental Example 4, manganese (Mn), which was technically impossible by the conventional method, more specifically, the conventional electrochemical method, was used as an electrolytic solution for a redox flow battery. It was found that separation and removal are possible up to an allowable concentration or less.

Example 3 Example 3 was carried out to examine the extraction characteristics of various organic solvents.

In Example 3, iron (Fe) and manganese (Mn), which are various organic solvents, are used for ease of explanation.
The extraction characteristics for and will be mainly described.

Experimental Example 5 to Experimental Example 8 (1) Preparation of Starting Hydrochloric Acid Aqueous Solution A starting hydrochloric acid aqueous solution whose composition is shown in Table 7 was prepared.

As the active material, ferrous chloride (FeCl ₂ ) was used as a starting material of iron (Fe) ionized and dissolved in the starting aqueous hydrochloric acid solution.

[0297]

[Table 7]

(2) Preparation of Organic Solvent In this experimental example, a mixed solution containing an organic extractant, a diluent and a modifier was used as the organic solvent.

Table 8 shows the type and concentration of the organic extractant of the organic solvent used in this experimental example. Further, Solvesso 150 was used as the diluent.

As the modifier, 2-ethylhexanol was used.

[0301]

[Table 8]

(3) Extraction Characteristics of Various Organic Solvents In the same manner as in Example 4, the raw material hydrochloric acid aqueous solution having the composition shown in Table 7 was mixed with the organic solvent having the composition shown in Table 8 to prepare the raw material hydrochloric acid. Various metals were extracted from the aqueous solution.

Next, the extraction of various metals with various organic solvents was carried out once, and the concentration of ferrous chloride ions in the aqueous solution phase (aqueous phase) and the aqueous solution phase (aqueous phase) were ionized. The concentrations of various dissolved metals were measured by ion chemiluminescence analysis (ICP).

The results are shown in Table 9.

[0305]

[Table 9]

The extraction ratio of iron (Fe) and manganese (Mn) into the organic solvent was calculated.

The results are shown in Table 10.

[0308]

[Table 10]

From the results shown in Table 10, the organic solvent containing tri-n-butyl phosphate used in Example 8 hardly extracts manganese (Mn) ions to the organic solvent phase (organic phase) side.

On the other hand, the organic solvent containing trioctylmethylammonium chloride used in Experimental Example 5 contained iron (Fe) ions and manganese (Mn) ions contained in the starting aqueous hydrochloric acid solution as the organic solvent phase (organic phase). ) Side,
It has excellent extraction characteristics.

From the above results, according to the first invention, in the method for producing an electrolyte solution of a redox flow battery using a hydrochloric acid aqueous solution containing chromium (Cr) ions as an electrolyte solution, manganese ( M
It was revealed that it is preferable to use an organic solvent containing trioctylmethylammonium chloride when separating and removing n).

Further, according to the fourth aspect of the invention, in the method for producing an electrolytic solution of a redox flow type battery using an aqueous hydrochloric acid solution containing iron (Fe) ions as an electrolytic solution, impurity metal ions, particularly manganese (Mn) is separated and removed. In doing so, it became clear that it is preferable to use an organic solvent containing tri-n-butyl phosphate.

[0313]

As described in detail above, the method for producing the electrolytic solution of the redox flow battery according to the first invention is
A redox flow can be easily and easily formed by extracting an impurity metal ion into an organic solvent from an aqueous hydrochloric acid solution containing a chromium (Cr) ion and an impurity metal ion other than the chromium (Cr) ion using an organic solvent. An aqueous hydrochloric acid solution containing chromium (Cr) ions, which can be suitably used as an electrolytic solution of a battery, can be produced.

More specifically, the method for producing the electrolytic solution of the redox flow type battery according to the first aspect of the present invention uses chromium (Cr).
As a result of having a constitution in which an impurity metal ion is extracted into an organic solvent from an aqueous hydrochloric acid solution containing ions and an impurity metal ion other than chromium (Cr) ion in the organic solvent, a conventional chromium ore or a chromium ore reduced product In the method of producing an electrolyte for a redox flow battery from a starting material such as ferrochrome, it was technically almost impossible.
Chromium (Cr) ions and manganese (Mn) ions can be separated.

Therefore, the electrolytic solution of the redox flow type battery manufactured according to the first invention is manganese (M
n) Since the concentration of the impurity metal ions contained in the electrolytic solution including the ions can be set to be equal to or lower than the concentration of the impurity metal ions allowed as the electrolytic solution of the redox flow type battery, it is manufactured according to the first invention. The redox flow battery using the electrolyte of the redox flow battery is
It has high charge / discharge efficiency.

The method for producing an electrolytic solution for a redox flow battery according to the second aspect of the present invention is the method for producing an iron solution from a first hydrochloric acid aqueous solution containing iron (Fe) ions and impurity metal ions other than iron (Fe) ions. The (Fe) ion and the impurity metal ion are extracted in an organic solvent using an organic solvent to obtain iron (F
e) An organic solvent containing ions and impurity metal ions is mixed with a second aqueous hydrochloric acid solution containing no metal ions, and iron (Fe) ions contained in the organic solvent are extracted into the second aqueous hydrochloric acid solution. With such a configuration, an aqueous hydrochloric acid solution containing iron (Fe) ions, which can be suitably used as an electrolytic solution of a redox flow battery, can be easily and easily produced.

More specifically, the method for producing the electrolytic solution of the redox flow battery according to the second aspect of the present invention comprises the steps of preparing a first hydrochloric acid aqueous solution containing iron (Fe) ions and impurity metal ions other than iron (Fe) ions. , Iron (Fe) ions and impurity metal ions are extracted into an organic solvent using an organic solvent,
An organic solvent containing iron (Fe) ions and impurity metal ions is mixed with a second aqueous hydrochloric acid solution containing no metal ions, and the iron (Fe) ions contained in the organic solvent are added to the second aqueous hydrochloric acid solution. As a result of having a constitution of extracting, iron (Fe) was technically almost impossible by the conventional method for producing an electrolyte solution of a redox flow battery from a starting material such as a chromium ore, a chromium ore reduction product, and ferrochrome. )
Ions and manganese (Mn) ions can be separated.

Therefore, the electrolyte of the redox flow type battery manufactured according to the second invention is manganese (M
n) Since the concentration of the impurity metal ions contained in the electrolytic solution including the ions can be set to be equal to or lower than the concentration of the impurity metal ions allowed as the electrolytic solution of the redox flow type battery, it was manufactured according to the second invention. A redox flow battery using an electrolytic solution has high charge / discharge efficiency.

Further, according to the third aspect of the present invention, there is provided a method for producing an electrolytic solution for a redox flow type battery, comprising: iron (Fe) ions, chromium (Cr) ions; and impurities other than iron (Fe) ions and chromium (Cr) ions. Iron (Fe) ions and impurity metal ions are extracted from the first aqueous hydrochloric acid solution containing metal ions into an organic solvent using an organic solvent, and thereafter,
A configuration in which an organic solvent containing iron (Fe) ions and impurity metal ions and an aqueous hydrochloric acid solution containing chromium (Cr) ions are separated, and an aqueous hydrochloric acid solution containing chromium (Cr) ions is taken out as an electrolytic solution. Thus, a hydrochloric acid aqueous solution containing chromium (Cr) ions, which can be suitably used as an electrolytic solution of a redox flow battery, can be easily and easily produced, and iron (Fe) ions and impurity metal ions can be produced. A second hydrochloric acid aqueous solution containing no metal ions is mixed with an organic solvent containing and the iron (Fe) ions contained in the organic solvent are extracted into the second hydrochloric acid aqueous solution, thereby easily and easily. An aqueous hydrochloric acid solution containing iron (Fe) ions, which can be suitably used as an electrolytic solution of a redox flow battery, can be produced.

More specifically, in the method for producing an electrolyte for a redox flow battery according to the third invention, the electrolyte for a redox flow battery is produced from a conventional starting material such as chromium ore, a chromium ore reduction product, and ferrochrome. With the method, it is possible to separate chromium (Cr) ions and manganese (Mn) ions and to separate iron (Fe) ions and manganese (Mn) ions, which was almost impossible technically. You can

Therefore, the electrolytic solution of the redox flow battery manufactured according to the third invention is manganese (M
n) Since the concentration of the impurity metal ions contained in the electrolytic solution including the ions can be set to be equal to or lower than the concentration of the impurity metal ions allowed as the electrolytic solution of the redox flow type battery, it is manufactured according to the third invention. The redox flow type battery using the electrolytic solution has high charge / discharge efficiency.

Further, the method for producing an electrolytic solution for a redox flow type battery according to the fourth aspect of the present invention is a method for producing an iron solution from a first hydrochloric acid aqueous solution containing iron (Fe) ions and impurity metal ions other than iron (Fe) ions. (Fe) ions are selectively extracted into an organic solvent using an organic solvent, and an organic solvent containing iron (Fe) ions is mixed with a second aqueous hydrochloric acid solution containing no metal ions to form an organic solvent. Iron (Fe) contained in
With the configuration in which ions are extracted into the second aqueous hydrochloric acid solution, it is possible to easily and easily produce an aqueous hydrochloric acid solution containing iron (Fe) ions, which can be suitably used as an electrolytic solution of a redox flow battery. it can.

More specifically, the method for producing the electrolytic solution for the redox flow battery according to the fourth aspect of the present invention comprises the steps of preparing a first hydrochloric acid aqueous solution containing iron (Fe) ions and impurity metal ions other than iron (Fe) ions. , Iron (Fe) ions are extracted into an organic solvent by using an organic solvent, and the organic solvent containing iron (Fe) ions is mixed with a second aqueous hydrochloric acid solution containing no metal ions and contained in the organic solvent. As a result of having a configuration of extracting iron (Fe) ions to the second aqueous hydrochloric acid solution, the conventional method for producing an electrolytic solution of a redox flow battery from a starting material such as chromium ore, a chromium ore reduction product, and ferrochrome is It is possible to separate iron (Fe) ions and manganese (Mn) ions, which was almost impossible technically.

Further, in the method for producing an electrolytic solution for a redox flow type battery according to the fourth invention, iron (Fe) ions and impurity metal ions other than iron (Fe) ions are extracted in the extraction step and the back extraction step. As a result of the separation, the iron (Fe) ions and the manganese (Mn) ions can be further separated as compared with the first invention.

Therefore, the electrolytic solution of the redox flow type battery manufactured according to the fourth invention is manganese (M
n) Since the concentration of the impurity metal ions contained in the electrolytic solution including the ions can be set to be equal to or lower than the concentration of the impurity metal ions allowed as the electrolytic solution of the redox flow type battery, it was manufactured according to the fourth invention. A redox flow battery using an electrolytic solution has high charge / discharge efficiency.

The method for producing the electrolytic solution of the redox flow type battery according to the fifth aspect of the present invention includes iron (Fe) ions, chromium (Cr) ions, and impurities other than iron (Fe) ions and chromium (Cr) ions. Iron (Fe) ions and impurity metal ions are extracted from the first hydrochloric acid aqueous solution containing metal ions into the first organic solvent using the first organic solvent, and then the iron (Fe) ions and impurities are extracted. The first organic solvent containing metal ions and the aqueous hydrochloric acid solution containing chromium (Cr) ions are separated, and the aqueous hydrochloric acid solution containing chromium (Cr) ions is taken out as an electrolytic solution. Chromium (Cr), which can be easily and suitably used as an electrolytic solution of a redox flow battery.
An aqueous hydrochloric acid solution containing ions can be produced, and a first organic solvent containing iron (Fe) ions and impurity metal ions is mixed with a second aqueous hydrochloric acid solution containing no metal ions. Iron (F) contained in the organic solvent of No. 1
e) Ions and impurity metal ions are extracted into a second aqueous hydrochloric acid solution, and then the first organic solvent and a second aqueous hydrochloric acid solution containing iron (Fe) ions and impurity metal ions are separated. To prepare an aqueous hydrochloric acid solution containing iron (Fe) ions and impurity metal ions, and mixing the second organic solvent with the aqueous hydrochloric acid solution containing iron (Fe) ions and the impurity metal ions. Iron (Fe) ions contained in the second organic solvent are extracted into a second organic solvent, and then the aqueous hydrochloric acid solution containing the impurity metal ions and the second organic solvent containing the iron (Fe) ions are separated. The second organic solvent containing (Fe) ions is mixed with a third aqueous hydrochloric acid solution containing no metal ions, and the iron (Fe) ions contained in the second organic solvent are mixed in the third aqueous hydrochloric acid solution. Extracted and then with a second organic solvent Suitable for use as an electrolytic solution of a redox flow battery simply and easily by a structure in which an aqueous hydrochloric acid solution containing iron (Fe) ions is separated and an aqueous hydrochloric acid solution containing iron (Fe) ions is taken out as an electrolytic solution. An aqueous hydrochloric acid solution containing iron (Fe) ions that can be used can be produced.

More specifically, in the method for producing an electrolyte for a redox flow battery according to the fifth aspect of the invention, the electrolyte for a redox flow battery is produced from a conventional starting material such as chromium ore, a chromium ore reduction product, and ferrochrome. With the method, it is possible to separate chromium (Cr) ions and manganese (Mn) ions and to separate iron (Fe) ions and manganese (Mn) ions, which was almost impossible technically. You can

Therefore, the electrolytic solution of the redox flow battery manufactured according to the fifth invention is manganese (M
n) Since the concentration of the impurity metal ions contained in the electrolytic solution including the ions can be set to be equal to or lower than the concentration of the impurity metal ions allowed as the electrolytic solution of the redox flow type battery, it is manufactured according to the fifth invention. The redox flow type battery using the electrolytic solution has high charge / discharge efficiency.

Further, the method for producing an electrolytic solution for a redox flow type battery according to the fifth invention is superior to the third invention in that iron (Fe) ions and manganese (Mn) ions are separated. It is added that it is a thing.

Further, according to the method for producing an electrolyte for a redox flow battery according to the first to fifth inventions, it is possible to use an inexpensive raw material such as chrome ore, a chromite reduction product, and ferrochrome as a starting material. Therefore, it is possible to significantly reduce the manufacturing cost of the electrolytic solution of the redox flow battery as compared with the conventional method of manufacturing the electrolytic solution of the redox flow battery by dissolving high-purity electrolytic chromium in hydrochloric acid.

As described above, the method for manufacturing a redox flow type battery according to the first to fifth aspects of the invention can reduce the manufacturing cost of the electrolytic solution of the redox flow type battery, and the first to fifth aspects of the invention. The electrolyte produced according to
When used as an electrolytic solution for a redox flow battery, it has high charge / discharge efficiency.

Therefore, the method for producing an electrolyte solution for a redox flow battery according to the first to fifth inventions is economical as a method for producing an electrolyte solution for a redox flow battery as a power storage battery, where economic efficiency is important. Also, in terms of charge and discharge efficiency, this is a manufacturing method suitable for industrialization.

Further, the method for producing the electrolytic solution of the redox flow battery according to the first to fifth inventions is as described above.
It is a method that can be easily carried out at normal temperature and pressure, and it is extremely easy to carry out because it does not use dangerous chemical substances and does not involve dangerous reactions, and it has great practical significance in terms of safe operation. Is.

[Brief description of drawings]

FIG. 1 is a process diagram schematically showing a process for producing an electrolytic solution of a redox flow battery according to the present invention.

FIG. 2 is a process diagram schematically showing a process for producing an electrolyte solution of a redox flow battery according to the present invention.

FIG. 3 is a diagram showing the relationship between the chlorine concentration of a hydrochloric acid aqueous solution containing metal ions and the extraction ratio of an organic solvent for each metal.

FIG. 4 is a diagram schematically showing the principle of solvent extraction according to the present invention.

FIG. 5 schematically shows the principle of solvent extraction according to the present invention.

FIG. 6 is a configuration diagram schematically showing a specific example of a redox flow battery.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Nobuyuki Tokuda 3-3-22 Nakanoshima, Kita-ku, Osaka City, Osaka Prefecture Kansai Electric Power Co., Inc. Incorporated KN Lab Analysis Amagasaki Plant (72) Inventor Soji Kishida 1-1 Ohamacho Amagasaki City Hyogo Prefecture KN Lab Analysis Amagasaki Plant

Claims (5)

[Claims] 1. A method for producing an electrolytic solution for a redox flow type battery, which comprises using an aqueous hydrochloric acid solution containing chromium (Cr) ions as an electrolytic solution, which comprises a chromium (Cr) ion and an impurity metal ion other than the chromium (Cr) ion. And a step of preparing an aqueous hydrochloric acid solution containing, mixing an organic solvent to the aqueous hydrochloric acid solution, and extracting the impurity metal ions contained in the aqueous hydrochloric acid solution into the organic solvent, and then containing the impurity metal ions Of the electrolytic solution of the redox flow type battery, comprising the step of separating the organic solvent and the aqueous hydrochloric acid solution containing chromium (Cr) ions and taking out the aqueous hydrochloric acid solution containing chromium (Cr) ions as an electrolytic solution. Production method. 2. A method for producing an electrolytic solution of a redox flow type battery, which uses an aqueous hydrochloric acid solution containing iron (Fe) ions as an electrolytic solution, which comprises iron (Fe) ions and impurity metals other than iron (Fe) ions. A step of preparing a first hydrochloric acid aqueous solution containing ions, an organic solvent is mixed with the first hydrochloric acid aqueous solution, and the iron (Fe) ions and the impurity metal ions contained in the first hydrochloric acid aqueous solution. In the organic solvent, a second hydrochloric acid aqueous solution containing no metal ions is mixed with an organic solvent containing the iron (Fe) ions and the impurity metal ions, and the mixture is contained in the organic solvent. Iron (Fe) ions to be extracted into the second aqueous hydrochloric acid solution, and then the organic solvent containing the impurity metal ions and the aqueous hydrochloric acid solution containing iron (Fe) ions are separated to obtain the iron (F
e) a step of extracting an aqueous hydrochloric acid solution containing ions as an electrolytic solution, a method for producing an electrolytic solution of a redox flow battery. 3. A redox flow battery using a hydrochloric acid aqueous solution containing iron (Fe) ions as an electrolytic solution as a positive electrode active material and using a hydrochloric acid aqueous solution containing chromium (Cr) ions as an electrolytic solution as a negative electrode active material. The method for producing an electrolytic solution according to claim 1, wherein the first hydrochloric acid aqueous solution contains iron (Fe) ions, chromium (Cr) ions, and iron (Fe) ions and impurity metal ions other than chromium (Cr) ions. A step of preparing, mixing an organic solvent with the first hydrochloric acid aqueous solution, extracting the iron (Fe) ions and the impurity metal ions contained in the first hydrochloric acid aqueous solution into the organic solvent, and then ,
An organic solvent containing the iron (Fe) ions and the impurity metal ions is separated from an aqueous hydrochloric acid solution containing chromium (Cr) ions, and the aqueous hydrochloric acid solution containing the chromium (Cr) ions is used as an electrolytic solution. A step of extracting, and a second aqueous hydrochloric acid solution containing no metal ions is mixed with an organic solvent containing the iron (Fe) ions and the impurity metal ions to remove the iron (Fe) ions contained in the organic solvent. The aqueous hydrochloric acid solution containing the iron (Fe) ions is extracted by extracting into the second aqueous hydrochloric acid solution, and then separating the organic solvent containing the impurity metal ions and the aqueous hydrochloric acid solution containing the iron (Fe) ions. And a step of taking out as an electrolytic solution. 4. A method for producing an electrolytic solution for a redox flow type battery, which uses an aqueous hydrochloric acid solution containing iron (Fe) ions as an electrolytic solution, which comprises iron (Fe) ions and impurity metals other than iron (Fe) ions. A step of preparing a first hydrochloric acid aqueous solution containing ions and an organic solvent is mixed with the first hydrochloric acid aqueous solution, and the iron (Fe) ions contained in the first hydrochloric acid aqueous solution are mixed in the organic solvent. And a second aqueous hydrochloric acid solution containing no metal ions is mixed with the organic solvent containing the iron (Fe) ions, and the iron (Fe) ions contained in the organic solvent are mixed into the second solvent. It is extracted into an aqueous solution of hydrochloric acid, and then the organic solvent and an aqueous solution of hydrochloric acid containing iron (Fe) ions are separated to obtain the iron (F
e) a step of extracting an aqueous hydrochloric acid solution containing ions as an electrolytic solution, a method for producing an electrolytic solution of a redox flow battery. 5. A redox flow battery in which a hydrochloric acid aqueous solution containing iron (Fe) ions is used as an electrolytic solution as a positive electrode active material, and a hydrochloric acid aqueous solution containing chromium (Cr) ions is used as an electrolytic solution as a negative electrode active material. The method for producing an electrolytic solution according to claim 1, wherein the first hydrochloric acid aqueous solution contains iron (Fe) ions, chromium (Cr) ions, and iron (Fe) ions and impurity metal ions other than chromium (Cr) ions. A step of preparing, mixing a first organic solvent with the first aqueous hydrochloric acid solution, and adding the iron (Fe) ions and the impurity metal ions contained in the first aqueous hydrochloric acid solution to the first organic solvent And then extracted into the first organic solvent containing the iron (Fe) ions and the impurity metal ions, and a hydrochloric acid aqueous solution containing chromium (Cr) ions to separate the first organic solvent, A step of extracting an aqueous hydrochloric acid solution containing (Cr) ions as an electrolytic solution; and a second aqueous hydrochloric acid solution containing no metal ions in the first organic solvent containing the iron (Fe) ions and the impurity metal ions. The iron (Fe) ions and the impurity metal ions contained in the first organic solvent are mixed and mixed in the second organic solvent.
In a hydrochloric acid aqueous solution of, followed by the first organic solvent,
Separating the second aqueous hydrochloric acid solution containing the iron (Fe) ions and the impurity metal ions to prepare an aqueous hydrochloric acid solution containing the iron (Fe) ions and the impurity metal ions; A second organic solvent is mixed with a hydrochloric acid aqueous solution containing iron (Fe) ions and the impurity metal ions, and the iron (Fe) ions contained in the hydrochloric acid aqueous solution are extracted into the second organic solvent. Then, a step of separating the aqueous hydrochloric acid solution containing the impurity metal ions and a second organic solvent containing iron (Fe) ions, and a second organic solvent containing the iron (Fe) ions. , A third aqueous hydrochloric acid solution containing no metal ions is mixed, iron (Fe) ions contained in the second organic solvent are extracted into the third aqueous hydrochloric acid solution, and then the second organic solvent is mixed. And iron (Fe) It separates the hydrochloric acid aqueous solution containing one, and a step of taking out the aqueous hydrochloric acid solution containing the iron (Fe) ions as an electrolytic solution, the manufacturing method of the electrolyte redox flow type battery.