Preparation method of high-purity vanadium electrolyte

Abstract

The invention discloses a preparation method of a high-purity vanadium electrolyte, particularly relates to a method for directly preparing the high-purity vanadium electrolyte from a high-acid vanadium-containing solution, and belongs to the technical field of hydrometallurgy. The method mainly comprises the steps of hydrogen peroxide-alkaline extractant synergistic extraction, catalyst catalysis hydrogen peroxide decomposition, sulfuric acid reextraction simple evaporation and concentration and the like. According to the method, only vanadium is extracted through synergistic extraction, impurity cations are not extracted, the vanadium purity of a loaded organic phase is improved, hydrogen peroxide is catalytically decomposed (the catalyst can be recycled), vanadium is reversely extracted through sulfuric acid, the procedures of reduction or oxidation and the like are omitted, material consumption and energy consumption are reduced, introduction of impurities is reduced, the purity of the obtained vanadium electrolyte is larger than 99.9%, and the impurity concentration is lower than 10 mg / L; compared with an existing vanadium-containing liquid vanadium purification and enrichment technology, the total vanadium recovery rate is increased by 10%-20%, the process is simplified by 50%, the production cost is reduced, the environment is protected, and the method has high application and popularization value.

Description

Technical Field

[0001] The invention relates to the technical field of nonferrous metal metallurgy, and relates to a method for preparing a high-purity vanadium electrolyte, and in particular to a method for directly preparing the high-purity vanadium electrolyte from a high-acid vanadium-containing solution. Background Art

[0002] The number of cycles of all-vanadium liquid flow batteries has obvious advantages over other liquid flow batteries. They are mainly used for peak shaving and valley filling of power grids, energy storage of new energy power stations, emergency power supply in remote areas, etc., and have great commercial application value. The core components of all-vanadium liquid flow batteries are positive and negative electrolytes, which are composed of solutions of different valence states of a single vanadium element. Based on the current research results in the field of vanadium batteries, the vanadium concentration and purity of the electrolyte are key factors affecting the performance of all-vanadium liquid flow batteries. Extracting vanadium from vanadium-containing primary or secondary resources and preparing vanadium electrolytes are currently hot research topics in the vanadium battery industry. How to extract vanadium greenly and how to purify and enrich vanadium with high efficiency and low consumption directly affect the production efficiency of the vanadium battery industry. At present, the main processes for extracting vanadium from vanadium-containing resources include roasting-acid leaching and full wet acid leaching. During the process, impurity metals such as iron, aluminum, molybdenum, sodium, potassium and silicon associated with vanadium-containing resources such as stone coal, steel slag and waste catalysts are leached together with vanadium, and the leachate also has the characteristics of high acid content and low vanadium content. Therefore, economically and efficiently purifying and enriching vanadium from such leachate is one of the core issues in the preparation of vanadium battery electrolyte.

[0003] Solvent extraction can selectively extract vanadium from complex leachate, and the P204 extraction system can effectively extract vanadium oxyacyl cations, but the current P204 extraction process has the following problems: ① The vanadium extraction process is long, including: high-valent vanadium, iron reduction → multi-stage extraction → multi-stage stripping → oxidation of V(IV) to V(V) in the stripping solution → adding ammonia water to adjust the solution pH to about 2.0 → hydrolyzing vanadium to polyammonium vanadate (red vanadium) → calcining red vanadium to obtain V205 product; ② The consumption of sulfuric acid and ammonia water is large, and the remaining free sulfuric acid of about 1.01 mol / L in the stripping solution needs to be neutralized to the pH of the solution = 2; ③ A large amount of ammonia wastewater is generated; ④ The extracted iron is extremely difficult to strip during the organic phase circulation process. Zhang Guiqing et al. have newly developed a P204 vanadium extraction process: high-valent vanadium, iron reduction → extraction → hydrogen peroxide stripping → high temperature (100°C) stripping solution hydrolyzes vanadium to obtain V205 product. Compared with the traditional process, this process is shorter and has lower material consumption, but there is still the problem of iron interfering with extraction. Alkaline anion extraction of vanadium is also a commonly used process. The main process is: adjust the solution pH to above 2.0 with ammonia water → multi-stage extraction → reduction of loaded organic phase vanadium V(V) to V(IV) → multi-stage stripping → oxidation of V(IV) to V(V) in the stripping solution → add ammonia water to adjust the solution pH to about 2.0 → hydrolyze the precipitated vanadium to polyammonium vanadate (red vanadium) → calcine red vanadium to obtain V205 product. This process has a good vanadium purification and enrichment effect, but there are problems of lengthy process and high material consumption due to repeated pH adjustment and repeated oxidation and reduction.

[0004] In the face of these problems, it is necessary to develop new processes for preparing clean and efficient vanadium electrolytes through theoretical innovation. Summary of the invention

[0005] In view of the problems existing in the prior art, the present invention aims to achieve effective extraction and separation of vanadium impurities, establish a method for adjusting the presence form of vanadate ions, achieve effective separation of vanadium and metal impurities in the leaching solution, and provide a theoretical reference for the efficient and clean preparation of vanadium electrolyte in sulfuric acid medium. A method for preparing a high-purity vanadium electrolyte is provided, which adjusts the presence form of vanadate in the solution to obtain a vanadium electrolyte containing diperoxyvanadate anions VO(O2)2 - The solution, other metal ions in the solution still exist in the form of cations, thereby achieving effective separation of vanadium and metal ion impurities in the solution, and preparing a high-purity and high-concentration sulfate-based vanadium electrolyte. Compared with the traditional extraction method, the present invention can directly extract and separate vanadium impurities without adjusting pH, and impurities (especially iron) do not enter the organic phase, thereby greatly reducing the difficulty of extractant regeneration. To achieve this purpose, the present invention adopts the following technical solutions:

[0006] In a first aspect, the present invention provides a method for preparing a high-purity vanadium electrolyte, comprising the following steps:

[0007] (1) adding hydrogen peroxide to a highly acidic vanadium-containing metal impurity solution and reacting for 1-60 minutes to obtain a first reaction solution; the highly acidic vanadium-containing metal impurity solution has an acidity of 0.5-2.5 mol / L, a vanadium concentration of 0.1-20 g / L, a metal impurity concentration of 0.1-10 g / L, a mass concentration of hydrogen peroxide of 27.5%-30%, and an added amount of hydrogen peroxide of a molar ratio of H2O2:V=1-20:1.

[0008] (2) extracting vanadium from the first reaction solution with an alkaline anion extractant to obtain an organic phase loaded with vanadium oxyperoxide anions and a raffinate, wherein the anion extractant is one or two of N235, N1923, and N263, and a multi-stage countercurrent extraction is adopted, wherein the number of stages is 3-5 and the O / A ratio is 1:1-1:4; and the raffinate is recycled to step (1) for secondary use after supplementing the inorganic acid consumed in the leaching process.

[0009] (3) adding 5% to 10% by weight of a solid catalyst to the organic phase loaded with vanadium oxyperoxide anions, catalytically decomposing hydrogen peroxide, and fully reacting for 2 to 20 minutes to cleave the peroxide bonds therein, and without any loss of solid after the catalytic reaction, to obtain a second reaction liquid; the solid catalyst is one or two of manganese dioxide, ferric oxide, silver, and palladium, and the solid catalyst can be small particles, powder, or nanoparticles.

[0010] (4) filtering out the solid from the second reaction liquid to obtain a third reaction liquid, which is used for the catalytic reaction of the next batch of loaded organic phase;

[0011] (5) The loaded organic phase (i.e., the third reaction solution) after decomposition of hydrogen peroxide is stripped of vanadium with sulfuric acid, hydrochloric acid, or a mixed acid thereof to obtain a vanadium-containing solution. The stripping method is single-stage stripping. The acid concentration used for stripping is 2 mol / L-4 mol / L, and the stripping phase ratio O / A is 3:1-1:1.

[0012] (6) The vanadium-containing solution is evaporated and concentrated to obtain a high-purity vanadium electrolyte.

[0013] The beneficial effects of the present invention are:

[0014] 1. The present invention does not require any external chemical reagents that may introduce impurities, has a simple process, and has good vanadium removal and enrichment effects. Finally, a high-purity, high-concentration vanadium-containing solution is obtained, which can be directly used as an electrolyte for vanadium liquid flow batteries.

[0015] 2. The present invention adopts a synergistic extraction method to extract only vanadium without extracting impurity cations, thereby improving the purity of vanadium in the loaded organic phase, catalytically decomposing hydrogen peroxide (the catalyst can be recycled) and stripping vanadium with sulfuric acid, eliminating the reduction or oxidation process, reducing material consumption and energy consumption, and reducing the introduction of impurities. The purity of the obtained vanadium electrolyte is greater than 99.9%, the impurity concentration is lower than 10 mg / L, and the total recovery rate of vanadium is greater than 95%. Compared with the existing vanadium-containing liquid vanadium purification and enrichment technology, the total recovery rate of vanadium is increased by 10-20%, the process is simplified by 50%, the production cost is reduced, the environment is protected, and it has a strong promotion and application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a flow chart of a method for preparing vanadium electrolyte provided in a specific embodiment of the present invention. DETAILED DESCRIPTION

[0017] The present invention is further described in detail below. However, the following examples are only simple examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention is subject to the claims. It should be clear that the use of the process provided by the embodiment of the present invention or the replacement or change of conventional data falls within the scope of protection and disclosure of the present invention.

[0018] Example 1

[0019] (1) A vanadium-containing leaching solution having a vanadium concentration of 2.5 g / L, an iron concentration of 1.5 g / L, a manganese concentration of 1.2 g / L, an aluminum concentration of 1.6 g / L, and a pH of 0.5 was mixed with 30% by mass hydrogen peroxide in a molar ratio of H2O2:V=10:1, and stirred at 40°C for 1 hour for reaction treatment to obtain a yellow transparent clear solution;

[0020] (2) The diperoxyvanadate-containing material was mixed with an organic extraction system (extractant N235:260# oil=20:80), and three-stage countercurrent extraction was performed at an O / A ratio of 1:3 and 30° C. The single-stage extraction reaction time was 10 min to obtain a loaded organic phase with a vanadium element concentration of 12.8 g / L;

[0021] (3) The vanadium-loaded organic phase is mixed with 5% by mass of manganese dioxide solid powder, bubbles are generated, and the mixture is stirred at 100 rpm for 10 minutes, then filtered to recover the manganese dioxide solid powder.

[0022] (4) The organic phase obtained after filtration is subjected to two-stage countercurrent stripping with 3 mol / L sulfuric acid with a ratio of O / A of 2:1 and 30°C, with a single-stage stripping time of 10 min, to obtain a pure vanadium-containing solution with a vanadium concentration of 42.4 g / L. The stripped organic phase obtained is regenerated and returned to the extraction process in step (2).

[0023] (5) The obtained pure vanadium-containing solution is concentrated by rotary evaporation for 60 minutes, and the solution is evaporated to 3 / 5, thereby obtaining a pure vanadium-containing solution with a vanadium concentration of about 70 g / L, which can be used as a vanadium electrolyte product. The purity of the obtained vanadium electrolyte is greater than 99.9%, the impurity concentration is less than 10 mg / L, and the total vanadium recovery rate is greater than 95%.

[0024] Example 2

[0025] (1) Vanadium concentration: 12.5 g / L, Iron concentration: 3.5 g / L, Manganese concentration: 2.2 g / L, Aluminum concentration: 1.6 g / L, c H+ =1.5 mol / L vanadium-containing leaching solution and 30% mass fraction hydrogen peroxide are mixed at a molar ratio of H2O2:V=20:1, and stirred at 40°C for 1 hour for reaction treatment to obtain a yellow transparent clear solution;

[0026] (2) The diperoxyvanadate-containing material was mixed with an organic extraction system (extractant N1923:260# oil=20:80), and three-stage countercurrent extraction was performed at an O / A ratio of 1:1 and 30° C. The single-stage extraction reaction time was 10 min, and a loaded organic phase with a vanadium element concentration of 12.1 g / L was obtained;

[0027] (3) The vanadium-loaded organic phase is mixed with 10% by mass of ferric oxide solid powder, bubbles are generated, and the mixture is stirred at 100 rpm for 10 minutes, then filtered to recover the ferric oxide solid powder.

[0028] (4) The organic phase obtained after filtration is subjected to single-stage stripping with 2 mol / L sulfuric acid at a ratio of 0 / A of 1:1 and 30° C. The single-stage stripping time is 10 min to obtain a pure vanadium-containing solution with a vanadium concentration of 12.0 g / L. The stripping organic phase obtained is regenerated and returned to the extraction process in step (2).

[0029] (5) The obtained pure vanadium-containing solution is concentrated by rotary evaporation for 60 minutes, and the solution is evaporated to 2 / 3, thereby obtaining a pure vanadium-containing solution with a vanadium concentration of about 18 g / L, which can be used as a vanadium electrolyte product. The purity of the obtained vanadium electrolyte is greater than 99.9%, the impurity concentration is less than 10 mg / L, and the total vanadium recovery rate is greater than 95%.

[0030] Example 3

[0031] (1) Vanadium concentration: 19.5 g / L, Iron concentration: 8.5 g / L, Manganese concentration: 1.2 g / L, Aluminum concentration: 4.6 g / L, c H+ =1.0 mol / L vanadium-containing leaching solution and 30% mass fraction hydrogen peroxide are mixed according to the molar ratio of H2O2:V=12:1, and stirred at 30°C for 1 hour for reaction treatment to obtain a yellow transparent clear solution;

[0032] (2) The diperoxyvanadate-containing material was mixed with an organic extraction system (extractant N263:260# oil=30:70), and four-stage countercurrent extraction was performed at an O / A ratio of 1:3 and 30° C. The single-stage extraction reaction time was 10 min to obtain a loaded organic phase with a vanadium element concentration of 54.8 g / L;

[0033] (3) The vanadium-loaded organic phase is mixed with 3% by mass of metal palladium solid powder, bubbles are generated, and the mixture is stirred at 100 rpm for 10 minutes, then filtered to recover the palladium solid powder.

[0034] (4) The organic phase obtained after filtration is subjected to two-stage countercurrent stripping with 4 mol / L sulfuric acid at a ratio of 1:1, 30° C., and a single-stage stripping time of 10 min to obtain a pure vanadium-containing solution with a vanadium concentration of 50.4 g / L. The stripped organic phase obtained is regenerated and returned to the extraction process in step (2).

[0035] (5) The obtained pure vanadium-containing solution is concentrated by rotary evaporation for 60 minutes, and the solution is evaporated to 3 / 5, thereby obtaining a pure vanadium-containing solution with a vanadium concentration of about 83 g / L, a purity greater than 99.9%, an impurity concentration less than 10 mg / L, and a total vanadium recovery rate greater than 95%.

[0036] Example 4

[0037] (1) Vanadium concentration 0.5 g / L, iron concentration 5.5 g / L, manganese concentration 4.2 g / L, aluminum concentration 5.6 g / L, c H+ = 2.5 mol / L vanadium-containing leaching solution and 27.5% mass fraction hydrogen peroxide are mixed in a molar ratio of H2O2:V=2:1, and stirred at 20°C for 1 hour for reaction treatment to obtain a yellow transparent clear solution;

[0038] (2) The diperoxyvanadate-containing material was mixed with an organic extraction system (extractant N235:260# oil=30:70), and three-stage countercurrent extraction was performed at an O / A ratio of 1:4 and 30° C. The single-stage extraction reaction time was 10 min to obtain a loaded organic phase with a vanadium element concentration of 3.8 g / L;

[0039] (3) The vanadium-loaded organic phase is mixed with 2% by mass of metallic silver powder, bubbles are generated, and the mixture is stirred at 100 rpm for 10 minutes, then filtered to recover the metallic silver powder.

[0040] (4) The organic phase obtained after filtration is subjected to three-stage countercurrent stripping with 3 mol / L sulfuric acid at a ratio of 0 / A of 3:1 and 30° C., with a single-stage stripping time of 10 min, to obtain a pure vanadium-containing solution with a vanadium concentration of 12.6 g / L. The stripped organic phase obtained is regenerated and returned to the extraction process in step (2).

[0041] (5) The obtained pure vanadium-containing solution is concentrated by rotary evaporation for 60 minutes, and the solution is evaporated to 1 / 3, thereby obtaining a pure vanadium-containing solution with a vanadium concentration of about 40 g / L, which can be used as a vanadium electrolyte product. The purity of the obtained vanadium electrolyte is greater than 99.9%, the impurity concentration is less than 10 mg / L, and the total vanadium recovery rate is greater than 95%.

[0042] Example 5

[0043] (1) Vanadium element concentration 2.5 g / L, iron element concentration 2.5 g / L, manganese element concentration 2.5 g / L, aluminum element concentration 2.5 g / L, c H+ = 2.0 mol / L vanadium-containing leaching solution and 28% mass fraction hydrogen peroxide are mixed in a molar ratio of H2O2:V=10:1, and stirred at 40°C for 1 hour for reaction treatment to obtain a yellow transparent clear solution;

[0044] (2) The diperoxyvanadate-containing material was mixed with an organic extraction system (extractant N235: TBP: 260# oil = 20:10:70), and three-stage countercurrent extraction was performed at an O / A ratio of 1:3 and 30° C. The single-stage extraction reaction time was 10 min, and a loaded organic phase with a vanadium element concentration of 10.8 g / L was obtained;

[0045] (3) The vanadium-loaded organic phase is mixed with 6% by mass of manganese dioxide solid powder, bubbles are generated, and the mixture is stirred at 100 rpm for 10 minutes, then filtered to recover the manganese dioxide solid powder.

[0046] (4) The organic phase obtained after filtration is subjected to three-stage countercurrent stripping with 3 mol / L sulfuric acid at a ratio of O / A of 2:1 and 30°C, with a single-stage stripping time of 10 min to obtain a pure vanadium-containing solution with a vanadium concentration of 42.6 g / L. The stripped organic phase obtained is regenerated and returned to the extraction process in step (2).

[0047] (5) The obtained pure vanadium-containing solution is concentrated by rotary evaporation for 60 minutes, and the solution is evaporated to 2 / 3, thereby obtaining a pure vanadium-containing solution with a vanadium concentration of about 64 g / L, which can be used as a vanadium electrolyte product. The purity of the obtained vanadium electrolyte is greater than 99.9%, the impurity concentration is less than 10 mg / L, and the total vanadium recovery rate is greater than 95%.

[0048] The serial numbers of the above embodiments of the present invention are only for description and do not represent the advantages or disadvantages of the embodiments.

[0049] The above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solutions of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A method for preparing a high-purity vanadium electrolyte, comprising: (1) adding hydrogen peroxide to a highly acidic solution containing vanadium and metal impurities, allowing the solution to react sufficiently to obtain a first reaction solution; (2) extracting vanadium from the first reaction solution with an alkaline anion extractant to obtain an organic phase loaded with vanadium oxyperoxide anions and a raffinate, wherein the anion extractant is one or two of N235, N1923, and N263; (3) adding a solid catalyst to the organic phase loaded with vanadium oxyperoxide anion, mixing well and reacting for 2-20 minutes to obtain a second reaction solution; (4) filtering the second reaction liquid to obtain a third reaction liquid and a solid catalyst, and the solid catalyst is used for the catalytic reaction of the next batch of loaded organic phase; (5) extracting vanadium from the third reaction solution with acid to obtain a vanadium-containing solution; (6) The vanadium-containing solution is evaporated and concentrated to obtain a high-purity vanadium electrolyte.

2. The method according to claim 1, wherein: The highly acidic vanadium-containing impurity solution in step (1) has an acidity of 0.5-2.5 mol / L, a vanadium concentration of 0.1-20 g / L, and a metal impurity concentration of 0.1-10 g / L.

3. The method according to claim 1, wherein: The mass concentration of the hydrogen peroxide in step (1) is 27.5%-30%; the amount of hydrogen peroxide added is in a molar ratio of H2O2:V=1-20:1; and the sufficient reaction condition is a reaction at 20-40°C for 1-60 minutes.

4. The method according to claim 1, wherein: The extraction method of step (2) is multi-stage countercurrent extraction, the number of stages is 3-5, and the extraction phase O / A ratio is 1-1:

4.

5. The method according to claim 1, wherein: The raffinate in step (2) is recycled to step (1) for secondary use after replenishing the inorganic acid consumed in the leaching process.

6. The method according to claim 1, wherein: The amount of the solid catalyst in step (3) is 5% to 10% of the mass of the organic phase loaded with vanadium oxyperoxide anion; The solid catalyst is selected from: one or two of manganese dioxide, ferric oxide, silver and palladium.

7. The method according to claim 1, wherein: The stripping method in step (5) is single-stage stripping, and the stripping phase O / A ratio is 3-1:

1.

8. The method according to claim 1, wherein: The acid used in the stripping in step (5) is sulfuric acid, hydrochloric acid or a mixed acid thereof.

9. The method according to claim 8, wherein: The acid concentration used in the stripping is 2mol / L-4mol / L.

10. A high-purity vanadium electrolyte prepared according to the method of claims 1 to 9.

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