TWI769901B - Method for chemical purification of ammonium metavanadate - Google Patents

Abstract

A method for manufacturing vanadium(V) oxide (V₂O₅) is used to solve the problem of water pollution caused by the conventional method with complicated steps. The method includes dissolving ammonium metavanadate (NH₄VO₃) in hot water and removing impurities by filtration to form a vanadium-containing solution including an ammonium ion (NH₄ ⁺) and a metavanadate ion (VO₃ ^-); and adding an ammonium salt into the vanadium-containing solution to form a mixture, followed by forming ammonium metavanadate precipitate from the ammonium ion and the metavanadate ion in the mixture.

Description

Chemical purification method of ammonium metavanadate

The present invention relates to a kind of purification method of ammonium metavanadate, especially a kind of chemical purification method of ammonium metavanadate.

Vanadium redox flow battery (VFB), also known as vanadium redox flow battery (VRFB), is an efficient way to store chemical potential energy by using vanadium ions in different oxidation states. Rechargeable flow batteries, vanadium flow batteries are well suited for large-scale power storage applications due to their enormous energy capacity.

The vanadium redox flow battery uses vanadium electrolyte as its electrolyte, which can be dissolved in sulfuric acid (sulfuric acid) by electrolysis of high-purity vanadium (V) oxide (V ₂ O ₅ ). acid, H ₂ SO ₄ ), so how to form high-purity vanadium pentoxide (eg, vanadium pentoxide with a purity of more than 99.5%) has become a major focus of manufacturing high-performance vanadium redox flow batteries.

Generally speaking, workers can use sodium roasting technology to make vanadium concentrate, vanadium slag, vanadium Ash, vanadium-containing catalyst and other vanadium materials form ammonium metavanadate (NH ₄ VO ₃ ), and then form vanadium pentoxide through a deamination reaction. When the purity of ammonium acid is not good (such as ammonium metavanadate with a purity of only 95~99%), even after ammonium metavanadate must be dissolved in hot water containing sodium hydroxide (NaOH), the Impurity removal agents such as aluminum sulfate (Al ₂ (SO ₄ ) ₂ ), magnesium chloride (MgCl ₂ ), and sodium carbonate (Na ₂ CO ₃ ) are used to remove impurities. , NaClO ₃ ) and hydrogen peroxide (hydrogen peroxide, H ₂ O ₂ ) and other oxidants are oxidized, and after filtration, finally ammonium chloride (ammonium chloride, NH ₄ Cl), ammonium sulfate (ammonium sulfate, (NH ₄ ) ) ₂ SO ₄ ) and other ammonium salts to reprecipitate ammonium metavanadate dissolved in water to improve the purity of ammonium metavanadate. An example of a chemical purification method similar to the conventional ammonium metavanadate has been disclosed in Chinese Patent No. 102849795.

In addition, as described in Chinese Patent Publication No. 107298461, ammonium metavanadate can also be dissolved in ammonia solution, and then purified by a basic anion exchange resin and an acidic cation exchange resin in sequence to purify The latter ammonium metavanadate is recrystallized in ammonia water to improve the purity of ammonium metavanadate (above 99.7%); HCl) aqueous solution, after extraction with tributyl phosphate, and then back-extraction with ammonia water, the obtained crystalline precipitate can form vanadium pentoxide after calcination, and then recrystallizes in ammonia water to form high-purity vanadium metabolites. Ammonium acid (99.99%).

In the chemical purification method of the above-mentioned conventional ammonium metavanadate, it is necessary to use a large amount of chemicals such as impurities removal agent, oxidant, extractant, and back-extraction agent, and the use of ion exchange resin will require the use of a large amount of solvent to carry out the ion exchange resin. Equilibration and flushing of the column make the waste water produced by the conventional chemical purification method of ammonium metavanadate may cause secondary pollution, and because the purification steps are cumbersome, the cost is increased, which is not economical. In view of this, the conventional chemical purification method of ammonium metavanadate still needs to be improved.

In order to solve the above-mentioned problems, the purpose of the present invention is to provide a chemical purification method of ammonium metavanadate, which can reduce the usage of chemical agents and reduce the secondary polluters caused by process wastewater.

The second object of the present invention is to provide a chemical purification method of ammonium metavanadate, which can simplify the purification method and reduce the purification cost.

Another object of the present invention is to provide a chemical purification method of ammonium metavanadate, which can prepare high-purity ammonium metavanadate.

The chemical purification method of ammonium metavanadate of the present invention may include: dissolving ammonium metavanadate in 10 to 40 times the weight of hot water, stirring at a speed of 50 to 200 rpm for 60 to 120 minutes, and filtering to remove impurities to A vanadium-containing solution is obtained, the vanadium-containing solution includes a monoammonium ion and a metavanadate ion, and the pH value of the hot water is between 6 and 8; and a monoammonium salt is dissolved in the vanadium-containing solution, A mixed solution is obtained, and the ammonium ions in the mixed solution react with the metavanadate ions to form ammonium metavanadate and precipitate.

Accordingly, the chemical purification method of ammonium metavanadate of the present invention can improve the water solubility of ammonium metavanadate by dissolving ammonium metavanadate in hot water, so that the obtained vanadium-containing solution can contain more The ammonium ion, the metavanadate ion, and the ammonium ion generated by the dissociation of the additionally added ammonium salt can drive the ammonium ion and the metavanadate ion to form ammonium metavanadate and precipitate . In this way, the chemical purification method of ammonium metavanadate of the present invention can avoid the use of chemical agents such as impurities removal agent, oxidant, extractant and back-extraction agent, and also does not need to use a large amount of solvent to balance and flush the ion exchange resin column, The secondary pollution of chemical agents in the process wastewater can be reduced, and the steps are simple, and the effects of preventing the occurrence of water body pollution and reducing the process cost can be achieved.

In addition, with proper stirring, the contact between the ammonium metavanadate particles and the hot water can be promoted, and the dissolution of the ammonium metavanadate can be accelerated.

In addition, by using hot water whose pH value can be between 6 and 8, not only the water solubility of ammonium metavanadate can be improved, but also the consumption of ammonium ions in the obtained vanadium-containing solution can be avoided. damage.

In the chemical purification method of ammonium metavanadate of the present invention, the temperature of the hot water can be between 60°C and 90°C. In this way, the water solubility of ammonium metavanadate can be improved by providing hot water with an appropriate temperature.

In the chemical purification method of ammonium metavanadate of the present invention, the ammonium metavanadate can be dissolved in hot water with a weight of at least 20 times. In this way, by supplying an appropriate amount of hot water, the ammonium metavanadate can be completely dissolved in the hot water.

In the chemical purification method of ammonium metavanadate of the present invention, the ammonium ion and the metavanadate ion can be separated from the ammonium ion and the metavanadate ion at a temperature between 50 and 80° C., preferably at a temperature above 60° C. The reaction forms ammonium metavanadate. In this way, by carrying out the reaction at an appropriate temperature, the formation of ammonium polyvanadate can be accelerated (for example, it only takes 1 to 4 hours to make all the metavanadate ions and the ammonium ions to form ammonium metavanadate. ).

The chemical purification method of ammonium metavanadate of the present invention, wherein, the ammonium salt can be ammonium sulfate or ammonium chloride. In this way, due to the larger dissociation constants of ammonium salts such as ammonium sulfate and ammonium chloride, it is easier to form sufficient ammonium ions in the mixture; and the aforementioned ammonium salts are neutral and partial when dissolved in water. Weak acidity, so that the pH value of the mixture will not change greatly (still close to the pH value of the vanadium-containing solution), which is beneficial to the subsequent precipitation of ammonium metavanadate.

The chemical purification method of ammonium metavanadate of the present invention further comprises: measuring the molar number of metavanadate ions in the vanadium-containing solution, and adding the ammonium salt to the vanadium-containing solution, so that the mixed solution contains the ammonium salt. The molar ratio of the metavanadate ion to the ammonium ion can be between 1:1.5 and 1:3, preferably more than 1:2. In this way, by controlling the molar ratio range of the ammonium ion to the metavanadate ion, the ammonium ion can effectively react with the metavanadate ion to generate ammonium metavanadate.

〔this invention〕

S1: Dissolution step

S2: Vanadium precipitation step

S3: Determination step

[FIG. 1] A flow chart of a chemical purification method of ammonium metavanadate according to an embodiment of the present invention.

In order to make the above-mentioned and other objects, features and advantages of the present invention more obvious and easy to understand, the preferred embodiments of the present invention are exemplified below, and are described in detail as follows in conjunction with the accompanying drawings: please refer to Figure 1, The chemical purification method of ammonium metavanadate of the present invention may comprise: a dissolving step S1 and a vanadium precipitation step S2.

In the dissolving step S1, the worker can dissolve ammonium metavanadate (NH ₄ VO ₃ ) in hot water, so that ammonium metavanadate can be dissolved in hot water according to the following chemical reaction formula (Formula 1) As shown, a solution containing vanadium can be obtained by dissociating to form an ammonium ion (NH ₄ ⁺ ) and a metavanadate ion (VO ₃ ⁻ ).

It is worth noting that due to the poor water solubility of ammonium metavanadate in cold water (eg, the water solubility in water at 20°C is about 0.48 g/100 mL, and the water solubility in water at 30°C is about 0.84 g/100mL), so choose to use hot water to dissolve ammonium metavanadate. In this embodiment, the temperature of the hot water can be between 60 and 90° C., so that the water solubility of ammonium metavanadate can be increased to more than 2.42 g/100 mL. Also, in order to improve the water solubility of ammonium metavanadate, in the present embodiment, ammonium metavanadate is added to 10 to 40 times the weight of hot water, and stirred for 30 to 120 minutes (rotating speed is 50 to 200 rpm), to The vanadium-containing solution is obtained. In this way, with proper stirring, the contact between the ammonium metavanadate particles and the hot water can be promoted, and the dissolution of the ammonium metavanadate can be accelerated.

Furthermore, when the pH value is less than 6, the water solubility of ammonium metavanadate is not good, and when the pH value is greater than 9, the ammonium ions dissolved in the hot water will follow the following chemical reaction formula (formula 2). ) as shown in the form of ammonia gas (NH ₃ ) in gas form and escape, resulting in the loss of ammonium ions in the obtained vanadium-containing solution, so it is better to use heat with a pH value between 6 and 8. water.

Because ammonium metavanadate can be prepared from vanadium concentrates, vanadium slag, vanadium ash, vanadium-containing catalysts and other vanadium-containing metal vanadium materials, and can be prepared by sodium roasting technology (for example, the Republic of China Announcement No. I465579 No. patent case discloses that the vanadium-containing catalyst will be roasted with sodium salt, and after the hot water is poured out, the vanadium can be obtained by precipitating vanadium with ammonium salt), and the purity of the ammonium metavanadate at this time is about 95~ 99%, and may contain such as aluminum oxide (aluminum oxide, Al ₂ O ₃ ), calcium oxide (calcium oxide, CaO), iron oxide (ferric oxide, Fe ₂ O ₃ ), sodium chloride (sodium chloride, NaCl), sodium sulfate (Na ₂ SO ₄ ) and silicon dioxide (SiO ₂ ) and other impurities, after dissolving ammonium metavanadate in hot water, most of the impurities cannot be dissolved in hot water (For example, alumina, calcium oxide, iron oxide and silica are insoluble in hot water), which can be removed by filtration (such as using a mesh with a mesh size of 6 μm) that cannot be dissolved in hot water. impurities, so that the amount of impurities in the obtained vanadium-containing solution can be reduced.

In the vanadium precipitation step S2, the worker can make the ammonium ion and the metavanadate ion react to form ammonium metavanadate and precipitate according to the following chemical reaction formula (formula 3).

It is worth noting that, in order to accelerate the progress of the chemical reaction formula as shown in formula 2, in addition to adding ammonium salts such as ammonium sulfate and ammonium chloride to the vanadium-containing solution, the ammonium salt in the obtained mixed solution is The total amount of root ions is greater than the total amount of metavanadate, so as to drive the ammonium ions in the mixed solution to react with metavanadate ions to form ammonium metavanadate and precipitate out. The mixed solution is placed at a temperature between 50 and 80°C to accelerate the ammonium ion and the The metavanadate ion reaction. In this way, by carrying out the reaction at an appropriate temperature, the formation of ammonium metavanadate can be accelerated (for example, it only takes 1 to 4 hours to make all the metavanadate ions and the ammonium ions to form ammonium metavanadate. ).

In addition, in the vanadium-containing solution, although sodium ions (sodium ion, Na ⁺ , from sodium chloride and sodium sulfate) dissolved in hot water are also included, even if sodium ions and the metavanadate ions can be chemically The reaction formula (formula 4) is shown to form sodium metavanadate (NaVO ₃ ), but because in the vanadium-containing solution, the sodium ion content is much lower than the ammonium ion content, and the sodium ion and The ability of the metavanadate ion to bind is also lower than the ability of the ammonium ion to bind to the vanadate ion, so the precipitation of sodium metavanadate will not occur.

Furthermore, in order to improve the formation efficiency of ammonium metavanadate, between the dissolving step S1 and the vanadium precipitation step S2, the worker can additionally perform a measuring step S3, which is to measure the concentration of metavanadate ions in the vanadium-containing solution and the volume of the vanadium-containing solution, and then convert the total moles of the metavanadate ion.

Next, in the vanadium precipitation step S2, according to the total molar number of metavanadate ions in the vanadium-containing solution, an appropriate amount of ammonium salt is added to the vanadium-containing solution to make the total molar of the metavanadate ions in the vanadium-containing solution. The number of moles, the total mole number of the ammonium ion generated by the dissociation of the ammonium salt in the vanadium-containing solution and the total mole number of the ammonium group ion generated by the dissociation of ammonium metavanadate, the mole number ratio of the two can be between 1: Between 1.5 and 1:3 (metavanadate ion: ammonium ion), the ammonium ion can effectively react with the metavanadate ion to produce ammonium metavanadate.

According to the high-purity ammonium metavanadate obtained by the chemical purification method of above-mentioned ammonium metavanadate, through a deamination reaction (deamination), it is shown in the following chemical reaction formula (formula four) to form vanadium pentoxide ( Vanadium (V)Oxide, V ₂ O ₅ ).

2 NH ₄ VO _{3( s )} → V ₂ O _{5( s )} + 2 NH _{3( g )} + H ₂ O _{( l )} chemical reaction formula (Formula 4).

For example, after collecting the precipitated ammonium metavanadate, the worker can calcination (calcination) ammonium metavanadate for 1 to 4 hours at a temperature of 450 to 600° C. to form vanadium pentoxide; metavanadic acid The formation of vanadium pentoxide by ammonium through the deamination reaction is the common knowledge of those skilled in the art, so those skilled in the art should be able to adjust the temperature and time of the calcination reaction by themselves to optimize the formation efficiency of vanadium pentoxide. Repeat.

In order to confirm that according to the chemical purification method of ammonium metavanadate of the present embodiment, high-purity ammonium metavanadate can indeed be obtained, which is suitable for the manufacture of vanadium pentoxide that can be used as a raw material for vanadium electrolyte The weight percentage is 0.04% aluminum (aluminum, Al), 0.06% calcium (calcium, Ca), 0.10% iron (iron, Fe), 0.60% sodium (sodium, Na), 0.03% silicon (silicon) , Si), 42.10% vanadium (vanadium, V), and other proportions of impurity ammonium metavanadate (purity is about 96.5%), and the following tests were carried out:

(A) The amount of hot water in the dissolving step S1

This test is to take hot water with a temperature of 90 ° C, add 1 kg of ammonium metavanadate to the hot water of the weight shown in Table 1, and after stirring for 60 minutes, filter to remove impurities that cannot be dissolved in the hot water. And measure the content of each element such as aluminum, calcium, iron, sodium, silicon and vanadium in the obtained vanadium-containing solution, and convert its recovery rate.

As shown in the above-mentioned first table, ammonium metavanadate is dissolved in 10～40 times of hot water by weight, and the recovery rate of vanadium in the obtained vanadium-containing solution can all reach more than 90% (group A1～A4), And when the weight of hot water is more than 20 times the weight of ammonium metavanadate, the recovery rate of vanadium can reach more than 95% (groups A2 to A4). In addition, in groups A1 to A4, except for sodium, the removal rate of aluminum, calcium, iron, silicon and other elements can reach 90%.

(B) Time of dissolving step S1

This test is to take hot water with a temperature of 90 ° C, add 1 kg of ammonium metavanadate to 20 kg of hot water, and after stirring for the time shown in Table 2, filter to remove impurities that cannot be dissolved in hot water. And measure the content of each element such as aluminum, calcium, iron, sodium, silicon and vanadium in the obtained vanadium-containing solution, and convert its recovery rate.

As shown in the above table 2, after dissolving ammonium metavanadate in hot water, no matter stirring for 30-120 minutes, the recovery rate of vanadium in the obtained vanadium-containing solution can reach more than 90% (groups B1-B4) , and when the stirring time is more than 60 minutes, the recovery rate of vanadium can reach more than 95% (groups B2~B4). In addition, in groups B1~B4, except for sodium, the removal rate of aluminum, calcium, iron, silicon and other elements can reach 90%.

(C) pH value of vanadium precipitation step S2

This test is the vanadium-containing solution (1,000 mL) of the aforementioned group B2, and the molar number of metavanadate ions in the vanadium-containing solution (about 8 moles) is converted according to the following formula (1).

Mole number (mole) = ^{(vanadium element content (g))} / _50.94 Formula (1).

Next, ammonium sulfate was added to the vanadium-containing solution so that the mixed solution had the molar ratio of the metavanadate ion to the ammonium ion as shown in Table 3, and the reaction was carried out at a temperature of 60° C. for 2 hours. , and measure the content of calcium, iron, sodium, silicon and vanadium in the obtained ammonium metavanadate, and convert the purity of ammonium metavanadate according to the following formula (2).

Purity (%) = ^{(vanadium element content (%))} / _43.59 Formula (2).

As shown in the third table above, metavanadate ions and ammonium ions whose molar ratio is between 1:1.5 and 1:3.0 can effectively form ammonium metavanadate, and the obtained ammonium metavanadate The purity of ammonium metavanadate can reach more than 98.0% (groups C1~C4), and when the molar ratio is more than 1:2.0, the purity of ammonium metavanadate can reach more than 99.5% (groups C2~C4).

(D) temperature of vanadium precipitation step S2

This test is the vanadium-containing solution (1,000 mL) of the aforementioned group B2. After measuring the molar number of metavanadate ions in the vanadium-containing solution, ammonium sulfate is added to the vanadium-containing solution to make the partial vanadium in the mixed solution. The molar ratio of vanadate ion to ammonium ion was 1:2, and then reacted at the temperature shown in Table 4 for 2 hours, and measured in the obtained ammonium metavanadate, calcium, iron, sodium, The content of each element such as silicon and vanadium is converted into the purity of ammonium metavanadate.

As shown in Table 4 above, the purity of the ammonium metavanadate obtained in the temperature range of 40~80°C can reach more than 99.0% (group D1~D5), and when the reaction temperature is above 50°C, The purity of ammonium metavanadate can reach more than 99.5% (group D2~D5).

(E) time of vanadium precipitation step S2

This test is the vanadium-containing solution (1,000 mL) of the aforementioned group B2. After measuring the molar number of metavanadate ions in the vanadium-containing solution, ammonium sulfate is added to the vanadium-containing solution to make the partial vanadium in the mixed solution. The molar ratio of vanadate ion to ammonium ion was 1:2, and then reacted at a temperature of 60 ° C for the time shown in Table 5, and measured the ammonium metavanadate obtained, calcium, iron, The content of each element such as sodium, silicon and vanadium, and the purity of ammonium metavanadate is converted.

As shown in the above-mentioned 5th table, the purity of the ammonium metavanadate obtained between 1 and 4 hours in the reaction time can all reach more than 99.5% (group E1 to E4), and when the reaction time is more than 2 hours , the purity of ammonium metavanadate can reach more than 99.7% (group E2~E4).

(F) Selection of Ammonium Chloride

This test is the vanadium-containing solution (1,000 mL) of the aforementioned Group B2, and the vanadium-containing solution (1,000 mL) is measured After the molar number of metavanadate ions in the solution, ammonium chloride is added to the vanadium-containing solution, so that the molar ratio of metavanadate ions and ammonium ions in the mixed solution is 1:2, and then The reaction was carried out at a temperature of 60° C. for 2 hours, and the contents of calcium, iron, sodium, silicon, vanadium and other elements in the obtained ammonium metavanadate were measured, and the purity of ammonium metavanadate was converted.

The results show that the calcium content of the obtained ammonium metavanadate is 0.003%, the iron content is 0.001%, the sodium content is 0.006%, the silicon content is 0.019%, and the vanadium content is 43.45%. The purity is 99.6%.

To sum up, the chemical purification method of ammonium metavanadate of the present invention can improve the water solubility of ammonium metavanadate by dissolving ammonium metavanadate in hot water, so that the obtained vanadium-containing solution can contain More the ammonium ion, the metavanadate ion, and the ammonium ion generated by the dissociation of the additionally added ammonium salt can drive the ammonium ion and the metavanadate ion to form ammonium metavanadate together and precipitation. In this way, the chemical purification method of ammonium metavanadate of the present invention can avoid the use of chemical agents such as impurities removal agent, oxidant, extractant and back-extraction agent, and also does not need to use a large amount of solvent to balance and flush the ion exchange resin column, The secondary pollution of chemical agents in the process wastewater can be reduced, and the steps are simple, and the effects of preventing the occurrence of water body pollution and reducing the process cost can be achieved.

Moreover, through the adjustment of various process parameters, impurities such as alumina, calcium oxide, iron oxide and silicon dioxide in ammonium metavanadate can be effectively removed, and high-purity ammonium metavanadate (more than 99.5%) can be effectively formed. ), and then high-purity vanadium pentoxide can be obtained after the deamination reaction, which can be applied to manufacture the vanadium electrolyte of a high-performance vanadium redox flow battery, which is the effect of the present invention.

Although the present invention has been disclosed by the above-mentioned preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make various changes and modifications relative to the above-mentioned embodiments without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the patent application attached hereto.

S1: Dissolution step

S2: Vanadium precipitation step

S3: Determination step

Claims (10)

A chemical purification method for ammonium metavanadate, comprising: dissolving ammonium metavanadate in 10 to 40 times the weight of hot water, stirring at a speed of 50 to 200 rpm for 60 to 120 minutes, and filtering to remove impurities to obtain a A vanadium solution, the vanadium-containing solution contains an ammonium ion and a metavanadate ion, and the pH value of the hot water is between 6 and 8; and a monoammonium salt is dissolved in the vanadium-containing solution to obtain a mixed solution solution, the ammonium ions in the mixed solution react with the metavanadate ions to form ammonium metavanadate and precipitate. The chemical purification method of ammonium metavanadate according to claim 1, wherein the temperature of the hot water is between 60°C and 90°C. The chemical purification method of ammonium metavanadate according to claim 1, wherein the ammonium metavanadate is dissolved in hot water with a weight of at least 20 times. The chemical purification method of ammonium metavanadate according to claim 1, wherein, at a temperature between 50 and 80° C., the ammonium ion and the metavanadate ion are reacted to form ammonium metavanadate. The chemical purification method of ammonium metavanadate according to claim 4, wherein the ammonium ion and the metavanadate ion are reacted to form ammonium metavanadate at a temperature above 60°C. The chemical purification method of ammonium metavanadate according to claim 1, wherein, the ammonium ion and the metavanadate ion are reacted for 1 to 4 hours to form ammonium metavanadate. The chemical purification method of ammonium metavanadate according to claim 6, wherein the ammonium ion and the metavanadate ion are reacted for at least 2 hours to form ammonium metavanadate. The chemical purification method of ammonium metavanadate according to claim 1, wherein the ammonium salt is ammonium sulfate or ammonium chloride. The chemical purification method of ammonium metavanadate as claimed in claim 1, further comprising: measuring the molar number of metavanadate ions in the vanadium-containing solution, adding the ammonium salt to the vanadium-containing solution, and making the mixed solution The molar ratio of the metavanadate ion to the ammonium ion is between 1:1.5 and 1:3. The chemical purification method of ammonium metavanadate according to claim 9, wherein the molar ratio of the metavanadate ion to the ammonium ion in the mixed solution is 1:2 or more.

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