TW202034572A - Method for producing electrolyte solution for redox flow batteries using incineration ash as raw material - Google Patents

Abstract

Provided is a method for producing an electrolyte solution for redox flow batteries using incineration ash as a raw material, whereby it becomes possible to collect high-purity vanadium easily and with high efficiency to produce an electrolyte solution. The method comprises: a first step of adding an aqueous alkaline solution to incineration ash to perform the alkaline extraction of a vanadium-containing metal compound; a second step of separating the reaction product produced in the first step into a first filtrate and a first filtrated solid material; a third step of adding an alkaline earth metal salt to the first filtrate to convert a compound composed of an alkali metal and vanadium in the first filtrate to a compound composed of an alkaline earth metal and vanadium; a fourth step of separating the metal conversion product into a second filtrate and a second filtrated solid material while washing the metal conversion product with water; a fifth step of adding a reducing agent and an acid to the second filtrated solid material that contains a compound composed of the alkaline earth metal and vanadium to perform a dissolution/reduction reaction; and a sixth step of separating a reaction solution produced in the fifth step into a third filtrate containing a vanadium acidic solution as the main component and a third filtrated solid material containing the alkaline earth metal salt as the main component.

Description

Method for manufacturing electrolyte for redox flow battery using incineration ash as raw material

The invention relates to a method for manufacturing an electrolyte for a redox flow battery using incineration ash as a raw material.

The manufacturing method of using the incineration ash as a raw material to extract vanadium from the incineration ash to produce an electrolyte for a redox flow battery is known, for example, by the dust collector ash treatment method described in Patent Document 1, abbreviated as AMV As an intermediate product, ammonium metavanadate (NH ₄ VO ₃ ) is used as a raw material for the electrolyte through complicated steps. In Patent Document 1, first, water and sodium hydroxide are added to an incineration ash composed of dust collector ash to neutralize it, and a reducing agent is further added, and then solid-liquid separation is performed into a first filtrate and a first filtered solid component. Then, after adding water, sodium hydroxide, and an oxidizing agent to the first filtered solid component, sodium vanadate is oxidized to produce sodium vanadate, and then an acid is added to the liquid containing the sodium vanadate to neutralize the solid-liquid separation into the second The filtrate and the second filtered solid content. Then, by adding ammonium salt to the second filtrate containing sodium vanadate, and solid-liquid separation after heating and cooling, ammonium metavanadate is generated in the solid content of the third filtration.

In addition, for example, a manufacturing method described in Patent Document 2 has been proposed. In Patent Document 2, first, dust collector ash is used as a raw material, and an aqueous solution containing tetravalent vanadium is extracted through acid extraction and reduction procedures. The intermediate product vanadium hydroxide (VO(OH) ₂ ) is separated by solid-liquid separation to filter solid components. The form of separation and recycling. Then, using sulfur as a reducing agent, heating the recovered vanadium hydroxide to synthesize a trivalent vanadium compound, mixing the tetravalent vanadium compound (VO(OH) ₂ ) with the trivalent vanadium compound, adding sulfuric acid, and heating, Produce an electrolyte. [Prior Art Document] [Patent Document]

[Patent Document 1] Japanese Patent No. 3917222 [Patent Document 2] Japanese Patent No. 4567254

[The problem to be solved by the invention] However, if the ammonium metavanadate obtained by the dust collector dust treatment method described in Patent Document 1 is used as the raw material of the electrolyte, there are many ammonium components, so its removal takes a lot of time, and a reducing agent or an oxidizing agent must be used. A variety of medicines. Therefore, there is a problem of spending a lot of processing equipment or processing costs.

In addition, in the production method described in Patent Document 2, since a reduction reaction and extraction in the acidic range are performed, in addition to vanadium, metals such as nickel and iron are also extracted, and it is difficult to achieve high purity of vanadium. Furthermore, the intermediate product vanadium hydroxide is fine particles, so it is difficult to separate solid and liquid, and the loss in the separation step is likely to increase.

The present invention has been accomplished focusing on the above-mentioned problems, and aims to provide a method for producing an electrolyte for a redox flow battery using incineration ash as a raw material, which can conveniently and effectively recover high-purity vanadium and produce an electrolyte. [Means used to solve the problem]

The method for producing an electrolyte for a redox flow battery of the present invention has the first feature of having: a first step of adding an aqueous alkali solution to the raw material incineration ash, and subjecting the metal compound containing vanadium in the incineration ash to alkali extraction ; The second step, the solid-liquid separation of the reactant obtained in the aforementioned first step into the first filtrate and the first filtered solid content; the third step, the alkaline earth is added to the first filtrate separated in the aforementioned second step The metal salt converts the compound of alkali metal and vanadium in the first filtrate into a compound of alkaline earth metal and vanadium for the metal conversion reaction; the fourth step is to wash the metal conversion product obtained in the third step with water, At the same time, the solid-liquid is separated into a second filtrate and a second filtered solid component; in the fifth step, a reducing agent and an acid are added to the second filtered solid component containing a compound of alkaline earth metals and vanadium separated in the fourth step to Carry out the dissolution/reduction reaction; and in the sixth step, the solid-liquid separation of the reaction liquid obtained in the above-mentioned fifth step into a third filtrate mainly composed of a vanadium acid solution and a third filtrate mainly composed of alkaline earth metal salts The solid content is filtered, and this manufacturing method uses the vanadium acid solution obtained in the sixth step described above as an electrolyte for a redox flow battery.

According to the method for producing an electrolyte for a redox flow battery of the present invention, by using alkaline earth metal salts, even if ammonium metavanadate (AMV) is not produced in the form of an intermediate product as in the prior art, it can be derived from alkali metals and vanadium. The compound produced vanadium acid solution through the compound of alkaline earth metal and vanadium. Therefore, no complicated steps (procedures) will be passed, and therefore equipment investment and manufacturing costs can be reduced.

In addition, in the second step, nickel, iron, calcium, carbon, etc. as impurities can be easily separated by solid-liquid separation, which can improve the recovery rate and purity of vanadium.

In addition, the only chemicals used are alkaline aqueous solutions, acids, reducing agents, and alkali metal salts, and alkaline earth metal salts can be repeatedly recovered, so there is economic benefit.

Alkaline earth metal salts are cheap and safe as long as they use calcium salts which are particularly abundant in underground resources.

In addition, alkali extraction, metal conversion reaction, and dissolution/reduction reaction are performed at a temperature below the boiling temperature of each aqueous solution. Therefore, not only can the equipment cost of the reaction equipment be reduced, but it can also be processed with less energy, so it is more economical.

The second feature of the method for producing an electrolyte for a redox flow battery of the present invention is that the alkaline earth metal salt separated in the sixth step can be added to the first filtrate in the third step.

The method for producing an electrolyte for a redox flow battery of the present invention has the above-mentioned second feature and further exhibits the effect of reusing the alkaline earth metal salt added to the first filtrate.

The third feature of the method for producing an electrolyte for a redox flow battery of the present invention is that the alkaline earth metal may be at least one selected from calcium, magnesium, strontium, and barium.

The method for producing an electrolyte for a redox flow battery of the present invention has the above-mentioned third feature, and further uses metals other than calcium as alkaline earth metals, thereby exhibiting an effect of increasing diversity.

The fourth feature of the method for producing an electrolyte for a redox flow battery of the present invention is that the alkaline earth metal salt added in the third step can be selected from sulfate, phosphate, carbonate, and bicarbonate. At least one of salt and oxalate.

The method for producing an electrolyte for a redox flow battery of the present invention has the above-mentioned fourth feature, and further uses a wide variety of salts, thereby exhibiting an effect of increasing diversity.

The fifth feature of the method for producing an electrolyte for a redox flow battery of the present invention is that when the incineration ash is dust collector ash produced by incineration, preliminary solid-liquid separation can be performed before the first step Step, this preliminary solid-liquid separation step is to wash the dust from the dust collector with water, and separate the solid-liquid into a filtrate containing an ammonium sulfate ((NH ₄ ) ₂ SO ₄ ) solution and filter solid components.

The method for producing an electrolyte for a redox flow battery of the present invention has the fifth feature described above, and further, when the incineration ash is a dust collector ash generated by incineration, since it contains ammonium sulfate, it is Before the first step, the dust collector dust is washed with water to remove the filtrate containing the ammonium sulfate solution in advance, and the effect of smoothly performing the treatment after the first step can be exerted. [Effects of Invention]

According to the present invention, even if incineration ash is used as a raw material, high-purity vanadium can be recovered conveniently and effectively, and an electrolyte for a redox flow battery can be produced.

The following describes the embodiments of the present invention with reference to the attached drawings. The present invention relates to a method for extracting vanadium from incineration ash to produce electrolyte for redox flow battery. In addition, in the present invention, incineration ash refers to, for example, the incineration solid components produced by the burning of fossil fuels such as fuels such as heavy oil, tar, pitch, coal, etc., which are emulsified, except for this In addition, dust collector ash contained in exhaust gas is also included in incineration ash.

The method for producing an electrolyte for a redox flow battery of this embodiment, as shown in FIG. 1, has: a first step of adding an aqueous alkali solution to the raw material incineration ash to remove the vanadium-containing metal compound in the incineration ash Extraction with alkali; the second step, the solid-liquid separation of the reactant obtained in the first step into the first filtrate and the first filtered solid component; the third step, in the first filtrate separated in the second step Add alkaline earth metal salt to convert the compound of alkali metal and vanadium in the first filtrate into a compound of alkaline earth metal and vanadium for the metal conversion reaction; the fourth step is to convert the metal conversion product obtained in the third step Wash with water and separate solid-liquid into a second filtrate and a second filtered solid component; in the fifth step, add a reducing agent and an acid to the second filtered solid component containing a compound of alkaline earth metals and vanadium separated in the fourth step, To carry out the dissolution/reduction reaction; and in the sixth step, the solid-liquid separation of the reaction liquid obtained in the fifth step into a third filtrate mainly composed of a vanadium acid solution and a third filtrate mainly composed of alkaline earth metal salts The solid content is filtered, and the vanadium acid solution obtained in the sixth step is electrolytically reduced to use it as an electrolyte for a redox flow battery.

In the first step, by adding an alkaline aqueous solution such as sodium hydroxide (NaOH) aqueous solution to the incineration ash, the metal compound containing vanadium will be converted to the sodium salt of vanadium (NaVO ₃ , Na ₆ V ₂ O ₈ , Na ₄ V ₂ O _7, etc.) are extracted by alkali. In contrast, other metals (such as nickel (Ni), iron (Fe), calcium (Ca)), or carbon (C) are insoluble The material form exists in the aqueous solution.

In the second step, the solid-liquid separation of the reactants obtained in the first step is performed. This can be separated into a first filtrate containing a sodium salt of vanadium; and a first filtered solid component containing nickel, iron, calcium, carbon, etc.

In the third step, an alkaline earth metal salt such as calcium sulfate (CaSO ₄ ) is added to the first filtrate recovered in the second step. As a result, a metal conversion reaction occurs. In the sodium salt of vanadium in the first filtrate, sodium (Na) will be replaced by calcium (Ca) to change into calcium salt of vanadium (Ca(VO ₃ ) ₂ , Ca ₃ (VO ₄₎ ) ₂ , Ca ₂ V ₂ O _7, etc.) metal conversion products.

In the fourth step, the metal conversion material obtained in the third step is washed with water, and at the same time, solid-liquid separation is performed into a second filtrate and a second filtered solid component. Thereby, the second filtrate is discarded as an alkali waste liquid containing sodium sulfate (Na ₂ SO ₄ ), and the second filtered solid component composed of the calcium salt of vanadium is recovered.

In the fifth step, the reducing agent, sulfuric acid (H ₂ SO ₄ ), phosphoric acid (H ₃ PO ₄ ), carbonic acid (H ₂ CO ₃ ), bicarbonate and other acids are used to make the recovered in the fourth step The second filtered solid component composed of the calcium salt of vanadium undergoes a dissolution/reduction reaction.

In the sixth step, the solid-liquid separation of the reaction liquid obtained in the fifth step into a third filtrate mainly composed of vanadium acid solution (VO(SO ₄ )); and alkaline earth metal salt (calcium sulfate ( CaSO ₄ )) the third filtered solid content as the main component. In addition, the main component means the highest content in the third filtrate or the third filtered solid component, respectively.

The vanadium acid solution (VO(SO ₄ )) in the third filtrate recovered in the sixth step can be used as an electrolyte for a redox flow battery by electrolytic reduction. In addition, in the sixth step, the alkaline earth metal salt (calcium sulfate (CaSO ₄ )) recovered as the solid content of the third filter is supplied to the third step as the alkaline earth metal salt added to the first filtrate Reuse.

According to the method for producing an electrolyte for a redox flow battery of this embodiment, by using alkaline earth metal salts, even if ammonium metavanadate (AMV) is not produced as an intermediate product as in the prior art, it can be derived from alkali metals. The compound with vanadium generates a vanadium acid solution through the compound of alkaline earth metal and vanadium. Therefore, since there are no complicated steps (procedures), it is possible to achieve a reduction in equipment investment and a reduction in manufacturing costs.

In addition, the only chemicals used are alkaline aqueous solutions, acids, reducing agents, and alkali metal salts, and alkaline earth metal salts can be repeatedly recovered, so there is economic benefit.

Alkaline earth metal salts are cheap and safe as long as they use calcium salts which are particularly abundant in underground resources.

In addition, the alkali extraction, metal conversion reaction, and dissolution/reduction reaction are performed at a temperature below the boiling temperature of each aqueous solution. Therefore, not only can the equipment cost of the reaction equipment be reduced, but also can be processed with less energy, so it is more economical.

The foregoing has described one of the embodiments of the present invention. However, the present invention is not limited to the above-mentioned embodiments, and various changes can be made without departing from the spirit thereof.

For example, in addition to sodium hydroxide (NaOH) aqueous solution, potassium hydroxide (KOH) aqueous solution can also be used for the alkali aqueous solution added in the 1st step.

In addition, for alkaline earth metals, in addition to calcium (Ca), magnesium (Mg), strontium (Sr), and barium (Ba) can be used. For the alkaline earth metal salt added in the second step, one of the above alkaline earth metals can be used. Sulfate, phosphate, carbonate, bicarbonate, oxalate, etc.

In addition, as the reducing agent used in the fifth step, organic acids (oxalic acid, acetic acid, formic acid, etc.), hydrogen peroxide (H ₂ O ₂ ), hydrogen (H ₂ ), sulfurous acid gas (H ₂ S), etc. can be used.

In addition, when the incineration ash as a raw material is dust collector ash produced by incineration, the dust collector ash can be washed with water before the first step, and the solid-liquid separation is divided into filtrate containing ammonium sulfate ((NH ₄ ) ₂ SO ₄ ) solution And the preliminary solid-liquid separation step of filtering solid components. Since the dust collector ash contains ammonium sulfate, the dust collector ash is washed with water before the first step, and the filtrate containing the ammonium sulfate solution is removed in advance, so that the processing after the first step can be smoothly performed. [Example]

The following describes the embodiments of the present invention. In addition, the present invention is not limited to the following examples.

[Example 1] For the metal conversion reaction in the third step, it was confirmed that the reaction time caused by the temperature is different. As a result, the metal conversion reaction proceeds at room temperature (25-40°C), as shown in Figure 2, especially at 40°C. It progressed more quickly than at 25°C, and it was confirmed that the reaction was completed in 1 hour. In addition, it is not necessary to add chemicals such as pH adjustment in this reaction.

[Example 2] Regarding the dissolution/reduction reaction in the fifth step, it can be completely carried out at a low temperature where the aqueous solution does not boil. However, the reaction rate depends on the reaction temperature. Therefore, when the reaction temperature is 60°C to 90°C, the reaction time is set to 1 to 4 About hours.

That is, as shown in Fig. 3, the reaction is carried out at a reaction temperature of 60°C or higher, and in the actual reaction time, 70°C to 90°C is appropriate.

In addition, it did not dissolve into an aqueous solution within 2 hours at 50°C. In addition, there are concerns about boiling at 100°C, so it is not suitable.

Fig. 1 is a flowchart showing the processing steps of a method of manufacturing an electrolyte for a redox flow battery according to an embodiment of the present invention. Fig. 2 is a graph showing changes in processing temperature and time in a metal conversion reaction. Fig. 3 is a graph showing changes in reaction temperature and reaction time vs. reaction rate in a dissolution/reduction reaction.

Claims (5)

A manufacturing method of electrolyte for redox flow battery using incineration ash as raw material, including: In the first step, an alkaline aqueous solution is added to the incineration ash, and the metal compound containing vanadium in the incineration ash is subjected to alkaline extraction; In the second step, the solid-liquid separation of the reactant obtained in the first step described above into a first filtrate and a first filtered solid component; In the third step, the alkaline earth metal salt is added to the first filtrate separated in the second step, and the compound of the alkali metal and vanadium in the first filtrate is converted into the compound of the alkaline earth metal and vanadium for the metal conversion reaction ； In the fourth step, the metal conversion product obtained in the third step is washed with water, and solid-liquid separation is simultaneously separated into a second filtrate and a second filtered solid component; In the fifth step, a reducing agent and an acid are added to the second filtered solid component of the compound containing alkaline earth metals and vanadium separated in the aforementioned fourth step to perform a dissolution/reduction reaction; and In the sixth step, the solid-liquid separation of the reaction liquid obtained in the above-mentioned fifth step into a third filtrate mainly composed of vanadium acidic liquid and a third filtered solid component mainly composed of alkaline earth metal salts, and, The vanadium acid solution obtained in the sixth step is used in the electrolyte for redox flow batteries. For example, the method for manufacturing an electrolyte for a redox flow battery using incineration ash as a raw material of claim 1 is to add the alkaline earth metal salt separated in the sixth step to the first step in the third step. filtrate. According to claim 1 or 2, the method for producing an electrolyte for a redox flow battery using incineration ash as a raw material, wherein the alkaline earth metal is at least one selected from calcium, magnesium, strontium, and barium. The method for manufacturing an electrolyte for a redox flow battery using incineration ash as a raw material in any one of claims 1 to 3, wherein the alkaline earth metal salt added in the third step is selected from sulfate, phosphoric acid At least one of salt, carbonate, bicarbonate and oxalate. Such as the method for manufacturing electrolyte for redox flow battery using incineration ash as raw material in any one of claims 1 to 4, wherein when the incineration ash is dust collector ash produced by incineration, Before the first step, a preliminary solid-liquid separation step is performed. The preliminary solid-liquid separation step is to wash the dust collector dust with water and separate the solid-liquid into a filtrate containing an ammonium sulfate solution and a filtered solid component.

Images