High-purity and high-solubility vanadyl sulfate crystal as well as preparation method and application thereof

Abstract

The invention provides a high-purity and high-solubility vanadyl sulfate crystal and a preparation method and application thereof.The preparation method of the high-purity and high-solubility vanadyl sulfate crystal comprises the following steps that ammonium metavanadate or ammonium polyvanadate serves as a raw material and is roasted at the temperature of 600-900 DEG C under the inert gas protection and reducing atmosphere conditions, and vanadium oxide is obtained; dissolving the vanadyl sulfate in a mixed solution of pure water and sulfuric acid to obtain a high-concentration vanadyl sulfate solution or vanadyl sulfate slurry; the valence state of vanadium is adjusted to 3.9-4.1; cooling, crystallizing and filtering to obtain primary vanadyl sulfate crystals; dissolving the primary vanadyl sulfate crystal in pure water to obtain a vanadyl sulfate solution, and filtering; and adding sulfuric acid, adjusting the vanadium valence state of the solution to 3.99-4.01, cooling, crystallizing, and filtering to obtain the high-purity and high-solubility vanadyl sulfate crystal. The vanadyl sulfate crystal has the advantages of small particle size, high purity, good solubility and the like, and has good application prospects and large-scale popularization potential in the field of vanadium electrolyte.

Description

Technical Field

[0001] This invention relates to the preparation and purification technology of vanadium oxysulfate, and particularly to a high-purity, highly soluble vanadium oxysulfate crystal, its preparation method, and its applications. Background Technology

[0002] Vanadium redox flow batteries are a novel electrochemical energy storage technology. Energy in these batteries is generated by the conversion of vanadium ions between different oxidation states, achieving large-scale storage and release of electrical energy through the redox reactions of vanadium ions within the system. Vanadium redox flow batteries offer advantages such as long cycle life, high energy conversion efficiency, and deep charge / discharge capability, making them widely applicable in large-scale energy storage, peak power regulation, renewable energy grid integration, and microgrids.

[0003] Vanadium electrolyte, a key energy storage material in vanadium redox flow batteries, is mainly composed of vanadium oxysulfate and a mixture of vanadium sulfate and dilute sulfuric acid, or a mixture of vanadium oxysulfate and dilute sulfuric acid. Vanadium oxysulfate, as a crucial component of vanadium electrolyte, can reduce transportation and packaging costs through crystallization technology, thereby lowering the manufacturing cost of vanadium batteries and enhancing their competitiveness in the energy storage field.

[0004] Although some progress has been made in the preparation methods of vanadium oxysulfate crystals, the following core defects still exist:

[0005] Patent CN105776332A describes a process using sulfuric acid (V₂O₅, concentration 15-20 mol / L) as a raw material. Under closed conditions, a reducing gas is introduced, and the reaction is carried out at 250-300℃ to obtain a high-concentration vanadium oxysulfate solution. After cooling, vanadium oxysulfate crystals are obtained. This production process uses concentrated sulfuric acid at high temperatures, increasing operational difficulty and the inherent dangers of the process. The introduction of a heat source also increases production costs. Furthermore, all impurities in the vanadium oxysulfate crystals are inherited from the raw material, making it difficult to improve purity.

[0006] Patent CN106395900A describes a method for removing impurities from vanadium oxysulfate crystals. The method involves washing the crystals with anhydrous ethanol and a pure saturated vanadium oxysulfate solution to reduce the impurity content. However, this method only removes surface impurities and cannot deeply remove impurities introduced into the crystal during crystallization. Therefore, its impurity removal effect is limited, and it also carries the risk of introducing other impurity elements.

[0007] Currently, the main methods for preparing vanadium oxysulfate crystals are direct crystallization from a high-concentration vanadium oxysulfate solution or evaporation crystallization from a low-concentration vanadium oxysulfate solution. Impurities are removed by washing the vanadium oxysulfate crystals. These methods have disadvantages such as high operational risks, high product impurity content, and the introduction of other impurities during the washing process. Summary of the Invention

[0008] The purpose of this invention is to address the aforementioned problems by proposing a method for preparing high-purity, high-solubility vanadium oxysulfate crystals. This method employs a segmented crystallization process: the first crystallization uses a high-temperature method, resulting in primary vanadium oxysulfate crystals with advantages such as large particle size, high vanadium content, high purity, and low water of crystallization; the second crystallization uses a low-temperature method, resulting in secondary vanadium oxysulfate crystals with further improved purity and a smaller particle size compared to the primary vanadium oxysulfate crystals, thereby achieving higher dissolution efficiency. The high-purity, high-solubility vanadium oxysulfate crystals of this invention have promising application prospects and large-scale promotion potential in the field of vanadium electrolytes.

[0009] It should be noted that, in this invention, unless otherwise specified, the specific meaning of "comprising" in relation to composition and description includes both open-ended meanings such as "comprising," "including," etc., and closed-ended meanings such as "composed of," "consisting of," etc., and similar meanings.

[0010] To achieve the above objectives, the technical solution adopted by this invention is: a method for preparing high-purity, high-solubility vanadium oxysulfate crystals, comprising the following steps:

[0011] Step 1: Calcining ammonium metavanadate or ammonium polyvanadate under inert gas and reducing atmosphere conditions to obtain vanadium oxide. The calcination temperature is 500-900℃ and the calcination time is 1-5h.

[0012] Step 2: Mix vanadium oxide, pure water, and sulfuric acid to obtain a high-concentration vanadium oxysulfate solution or vanadium oxysulfate slurry. The mixing temperature is 80–150°C. The vanadium concentration C in the high-concentration vanadium oxysulfate solution or vanadium oxysulfate slurry is... (V) The concentration is 4.5–6.5 mol / L, and the molar ratio of sulfur to vanadium is C. (S / V) The range is 1 to 3;

[0013] Step 3: Adjust the valence state of vanadium in the high-concentration vanadium oxysulfate solution or vanadium oxysulfate slurry to 3.9–4.1, and react at 80–120℃ for 1–5 hours; the following ionic reactions occur:

[0014] VO2 + +V 3+ =2VO 2+

[0015] Step 4: Cooling and crystallization. The final temperature of cooling and crystallization is 30-50℃, and the cooling and crystallization time is 1-12 hours. A primary vanadium oxysulfate crystal slurry is obtained, which is then filtered to obtain primary vanadium oxysulfate crystals.

[0016] Step 5: Dissolve the vanadium oxysulfate crystals in pure water to prepare a 2-4 mol / L vanadium oxysulfate solution. Use a filter membrane to remove vanadium oxide and silicic acid from the vanadium oxysulfate solution.

[0017] Step 6: Add sulfuric acid to the filtered vanadium oxysulfate solution to adjust the valence state of vanadium. Then, cool and crystallize. After adding sulfuric acid, the molar ratio of sulfur to vanadium in the vanadium oxysulfate solution is 1–5, and the valence state of vanadium is adjusted to 3.99–4.01. The final cooling crystallization temperature is 0–40℃, and the cooling crystallization time is 12–24 hours, yielding a secondary vanadium oxysulfate crystal slurry. Filter to obtain secondary vanadium oxysulfate crystals, i.e., high-purity, high-solubility vanadium oxysulfate crystals. The reaction principle during the valence state adjustment process is the same as in Step 3. Further, the vanadium oxide in Step 1 is V₂O₅, VO₂, V₂O₃, V₂O₄, V₄O₇, and V₆O₇. 13 One or more of the following, i.e., vanadium oxide is a single compound or a mixture of different vanadium oxides. x Where x is 1.5 to 2.5. The vanadium oxide contains 56.02% to 67.97% V by mass, preferably 59% to 62%.

[0018] Furthermore, ammonium metavanadate is preferred in step 1.

[0019] Further, the inert gas mentioned in step 1 is one or more of nitrogen, argon and helium, preferably nitrogen and / or argon.

[0020] Further, the reducing atmosphere in step 1 is one or more of hydrogen, carbon monoxide, ammonia and methane, preferably hydrogen and / or ammonia.

[0021] Furthermore, the roasting temperature in step 1 is 600–700°C, and the roasting time is 1–3 hours.

[0022] Furthermore, the mixing temperature in step 2 is 90–110°C.

[0023] Furthermore, in step 2, the vanadium concentration C in the high-concentration vanadium oxysulfate solution or vanadium oxysulfate slurry... (V) The concentration is 5.0–5.8 mol / L.

[0024] Furthermore, in step 2, the molar ratio C of sulfur to vanadium in the high-concentration vanadium oxysulfate solution or vanadium oxysulfate slurry... (S / V) It ranges from 1.3 to 1.8.

[0025] Furthermore, in step 3, the valence state of vanadium in the high-concentration vanadium oxysulfate solution or vanadium oxysulfate slurry is adjusted to 3.95–4.05.

[0026] Furthermore, in step 3, the reaction temperature is 80–100°C, and the reaction time is 1–3 hours.

[0027] Furthermore, the additives used to adjust the valence state in step 3 are V2O5, V2O3, V2(SO4)3 crystals, V(OH)3, V4O7, and V6O. 13One or more of the following solids, preferably one or more of V2O5, V2O3, and V2(SO4)3 crystals.

[0028] Furthermore, the cooling rate for crystallization in step 4 is 10–20 °C / h.

[0029] Furthermore, in step 4, the final crystallization temperature is 40–50°C, and the crystallization time is 2–8 hours.

[0030] Furthermore, in step 5, the vanadium oxysulfate crystals are dissolved in pure water to prepare C. (V) It is a 2.5–3.5 mol / L vanadium oxysulfate solution.

[0031] Furthermore, in step 5, the filter membrane precision is 0.5–5 μm.

[0032] Furthermore, the filter membrane precision in step 5 is preferably 0.5–2 μm.

[0033] Furthermore, in step 6, sulfuric acid is added to the filtered vanadium oxysulfate solution to adjust the molar ratio of sulfur to vanadium in the vanadium oxysulfate solution to 1–5.

[0034] Furthermore, after adding sulfuric acid in step 6, (VO2)2SO4 or V2(SO4)3 solution is added to adjust the vanadium valence state, ensuring that the vanadium valence state in the solution is 3.99 to 4.01. That is, the vanadium oxysulfate solution after adjusting the valence state is a pure vanadium oxysulfate solution or a near-pure vanadium oxysulfate solution, ensuring that the entrainment of (VO2)2SO4 or V2(SO4)3 is avoided or reduced during the crystallization process, thereby improving the purity of the vanadium oxysulfate crystal.

[0035] Furthermore, in step 6, the final crystallization temperature is 20–40°C, and the crystallization time is 18–24 h.

[0036] Another objective of this invention is to disclose a high-purity, highly soluble vanadium oxysulfate crystal, prepared using the method described above.

[0037] Furthermore, the purity of the high-purity, high-solubility vanadium oxysulfate crystals is ≥99.5%.

[0038] Furthermore, the high-purity, high-solubility vanadium oxysulfate crystals have a D90 < 100 μm.

[0039] Furthermore, the high-purity, high-solubility vanadium oxysulfate crystals dissolve in ≤5 min at 25°C.

[0040] Another objective of this invention is to disclose the application of high-purity, high-solubility vanadium oxysulfate crystals in the field of vanadium electrolytes. Vanadium oxysulfate crystallization technology can save on the transportation and packaging costs of vanadium electrolytes, thereby reducing the unit price of vanadium batteries and enhancing their competitiveness in the energy storage field.

[0041] Furthermore, a vanadium electrolyte is prepared using the aforementioned high-purity, high-solubility vanadium oxysulfate crystals: The vanadium oxysulfate crystals are dissolved in pure water, and then sulfuric acid is added to prepare C. (V) The concentration is 1.5–1.8 mol / L, C (S / V) It is a high-purity vanadium electrolyte with a purity of 2.2 to 3.0.

[0042] The present invention relates to high-purity, highly soluble vanadium oxysulfate crystals, their preparation method, and applications, which have the following advantages compared with existing technologies:

[0043] 1) This invention uses high-temperature crystallization and recrystallization processes to obtain high-purity vanadium oxysulfate crystals.

[0044] 2) The vanadium oxysulfate crystals prepared by this invention have the advantages of small particle size and fast dissolution rate, which can significantly improve the working efficiency of the vanadium electrolyte preparation process. This invention dissolves primary vanadium oxysulfate crystals and recrystallizes them under low-temperature conditions to obtain small-particle secondary vanadium oxysulfate crystals. The secondary vanadium oxysulfate crystals have even smaller particle size, and under the same dissolution amount and conditions, the secondary vanadium oxysulfate crystals dissolve faster, thus improving the electrolyte preparation efficiency.

[0045] 3) The high-purity, high-solubility vanadium oxysulfate crystals of this invention solve the problems of high impurity content and poor quality of products caused by evaporation and crystallization in traditional preparation methods.

[0046] 4) The high-purity, high-solubility vanadium oxysulfate crystals of this invention can be used to directly prepare vanadium electrolytes on-site. This solves the problem of high packaging and transportation costs associated with traditional vanadium electrolytes.

[0047] 5) The recrystallization of vanadium oxysulfate in this invention also provides an effective experimental method for the crystallization and purification of low-concentration vanadium oxysulfate solutions.

[0048] The high-purity, high-solubility vanadium oxysulfate crystals of this invention have good application prospects and large-scale promotion potential in the field of vanadium electrolytes. Attached Figure Description

[0049] Figure 1 The data for the primary vanadium oxysulfate crystals in Example 3 are as follows;

[0050] Figure 2 The results of SEM testing of vanadium oxysulfate crystals in Example 3 are shown below.

[0051] Figure 3The following is the particle size data for vanadium oxysulfate crystals in Example 3;

[0052] Figure 4 The results of SEM testing of vanadium oxysulfate crystals in Example 3 are shown below.

[0053] Figure 5 The results of XRD analysis of vanadium oxysulfate crystals in Example 3 are shown.

[0054] Figure 6 The performance of the vanadium electrolyte prepared from vanadium oxysulfate crystals in Example 4 was tested. Detailed Implementation

[0055] The present invention will be further described below with reference to embodiments. The description of the technical features described below is based on representative embodiments and specific examples of the present invention, but the present invention is not limited to these embodiments and specific examples. It should be noted that:

[0056] Unless otherwise stated, all units used in this specification are international standard units, and all numerical values ​​and ranges appearing in this invention should be understood to include systematic errors that are unavoidable in industrial production.

[0057] In this specification, the range of values ​​referred to as "value A to value B" refers to the range including the endpoint values ​​A and B.

[0058] In this specification, the numerical range indicated by "above" or "below" refers to the numerical range that includes the stated number.

[0059] In this specification, the word "may" has two meanings: to perform a certain process and not to perform a certain process.

[0060] In this specification, the terms "optional" or "optional" are used to indicate the use or omission of certain substances, components, procedures, application conditions, etc.

[0061] In this instruction manual, when "room temperature" or "room temperature" is used, the temperature can be 15-25℃.

[0062] Unless otherwise specified, all reagents or instruments used in this instruction manual are commercially available products.

[0063] Example 1

[0064] This embodiment discloses a high-purity, highly soluble vanadium oxysulfate crystal, its preparation method, and its applications, including the following steps:

[0065] (1) Using ammonium metavanadate as raw material, calcined at 600℃ under argon protection and hydrogen reduction for 2h, vanadium oxide solid with V content of 61.0% was obtained.

[0066] (2) Mix 450 ml of concentrated sulfuric acid and 300 ml of pure water, then add 460 g of vanadium oxide solid. Maintain the reaction temperature at 100 °C. After the reaction, add pure water to bring the volume to 1000 ml to obtain C. (V) It is 5.5 mol / L, C (S / V) The vanadium oxysulfate solution has a concentration of 1.36.

[0067] (3) Add 70g of vanadium sulfate crystals to the above vanadium oxysulfate solution, adjust the valence of V in the solution to 4.02, and react at 90℃ for 2h.

[0068] (4) Cool the vanadium oxysulfate solution after adjusting the valence state to crystallize. The cooling rate is 10℃ / h, the crystallization temperature is 40℃, and the crystallization time is 6h. A primary vanadium oxysulfate crystal slurry is obtained, and the primary vanadium oxysulfate crystal is obtained by filtration.

[0069] (5) Dissolve the vanadium oxysulfate crystals in pure water to prepare a 3.3 mol / L vanadium oxysulfate solution, and filter it using a 1 μm filter membrane.

[0070] (6) Add sulfuric acid to the filtered vanadium oxysulfate solution and cool to crystallize. The C in the vanadium oxysulfate solution after adding sulfuric acid... (S / V) The vanadium valence was adjusted to 4.006 by adding V2(SO4)3 solution to a value of 3.2. The crystallization endpoint temperature was 30℃ and the crystallization time was 18h to obtain a secondary vanadium oxysulfate crystal slurry. The secondary vanadium oxysulfate crystals were obtained by filtration, which are high-purity vanadium oxysulfate crystals with high solubility.

[0071] Example 2

[0072] This embodiment discloses a high-purity, highly soluble vanadium oxysulfate crystal, its preparation method, and its applications, including the following steps:

[0073] (1) Using ammonium metavanadate as raw material, calcined at 600℃ under argon protection and hydrogen reduction for 2h, vanadium oxide solid with V content of 61.0% was obtained.

[0074] (2) Mix 450 ml of concentrated sulfuric acid and 300 ml of pure water, then add 460 g of vanadium oxide solid. Maintain the reaction temperature at 100 °C. After the reaction, add pure water to bring the volume to 1000 ml to obtain C. (V) It is 5.5 mol / L, C (S / V) The vanadium oxysulfate solution has a concentration of 1.36.

[0075] (3) Add 70g of vanadium sulfate crystals to the above vanadium oxysulfate solution, adjust the valence of V in the solution to 4.02, and react at 90℃ for 2h.

[0076] (4) Cool the vanadium oxysulfate solution after adjusting the valence state to crystallize. The cooling rate is 20℃ / h, the final crystallization temperature is 40℃, and the total crystallization time is 6h. A primary vanadium oxysulfate crystal slurry is obtained, and the primary vanadium oxysulfate crystal is obtained by filtration.

[0077] (5) Dissolve the vanadium oxysulfate crystals in pure water to prepare a 3.3 mol / L vanadium oxysulfate solution, and filter it using a 1 μm filter membrane.

[0078] (6) Add sulfuric acid to the filtered vanadium oxysulfate solution and cool to crystallize. The C in the vanadium oxysulfate solution after adding sulfuric acid... (S / V) The vanadium valence was adjusted to 4.006 by adding V2(SO4)3 solution to a value of 3.2. The crystallization endpoint temperature was 30℃ and the crystallization time was 18h to obtain a secondary vanadium oxysulfate crystal slurry. The secondary vanadium oxysulfate crystals were obtained by filtration, which are high-purity vanadium oxysulfate crystals with high solubility.

[0079] Comparative Example 1

[0080] Comparative Examples 1-2 disclose a method for preparing vanadium oxysulfate crystals, which is basically the same as that in Example 1, except that the cooling rate in step (4) is 30℃ / h.

[0081] Comparative Example 2

[0082] Comparative Examples 1-2 disclose a method for preparing vanadium oxysulfate crystals, which is basically the same as that in Example 1, except that the cooling rate in step (4) is 40℃ / h.

[0083] Elemental and particle size analyses were performed on the primary vanadium oxysulfate crystals of Examples 1-2 and Comparative Examples 1-2, respectively, and the results are shown in Table 1 and Table 2, respectively.

[0084] Table 1. Elemental analysis results of vanadium oxysulfate crystals in a single test.

[0085]

[0086] Table 2 Results of primary vanadium oxysulfate crystal particle size determination

[0087] Cooling rate (°C / h) D10(μm) D50(μm) D90(μm) Example 1 10 46.3 125 447 Example 2 20 42.5 117 432 Comparative Example 1 30 26.6 82.3 262 Comparative Example 2 40 25.2 81.6 258

[0088] As can be seen from Tables 1 and 2, when the cooling rate exceeds 20℃ / h, the particle size of vanadium oxysulfate crystals will decrease and the impurity content in the crystals will increase.

[0089] Example 3

[0090] This embodiment discloses a method for preparing high-purity, highly soluble vanadium oxysulfate crystals, including the following steps:

[0091] (1) Using ammonium metavanadate as raw material, calcined at 650℃ under nitrogen protection and ammonia reduction conditions for 3h, vanadium oxide solid with a V content of 62.3% was obtained.

[0092] (2) Mix 390 ml of concentrated sulfuric acid and 300 ml of pure water, then add 425 g of vanadium oxide solid. Maintain the reaction temperature at 95 °C. After the reaction, add pure water to bring the volume to 1000 ml to obtain C. (V) It is 5.2 mol / L, C (S / V) The vanadium oxysulfate solution has a strength of 1.40.

[0093] (3) Add 40g of vanadium pentoxide (V2O5) to the above vanadium oxysulfate concentrate, adjust the oxidation state of V in the solution to 3.96, and react at 90℃ for 1.5h.

[0094] (4) The solution after valence adjustment was cooled at a rate of 10℃ / h, with a crystallization endpoint temperature of 50℃ and a total crystallization time of 5h, yielding a primary vanadium oxysulfate crystal slurry. The slurry was filtered to obtain primary vanadium oxysulfate crystals. Elemental analysis results are shown in Table 3, and particle size analysis results are detailed in [Table 3]. Figure 1 For detailed SEM test results, please refer to [link / reference]. Figure 2 .

[0095] (5) Dissolve the vanadium oxysulfate crystals in pure water to prepare a 3.5 mol / L vanadium oxysulfate solution, and filter it using a 0.5 μm filter membrane.

[0096] (6) Add sulfuric acid to the filtered vanadium oxysulfate solution and cool to crystallize. The C in the vanadium oxysulfate solution after adding sulfuric acid... (S / V) The vanadium valence was adjusted to 3.997 by adding (VO2)2SO4 solution. The crystallization endpoint temperature was 25℃, and the crystallization time was 20 h, yielding a secondary vanadium oxysulfate crystal slurry. Filtration yielded secondary vanadium oxysulfate crystals, i.e., high-purity, high-solubility vanadium oxysulfate crystals. Elemental analysis results are shown in Table 3, and particle size analysis results are detailed in […]. Figure 3 For detailed SEM test results, please refer to [link / reference]. Figure 4 For detailed XRD test results, please refer to [link / reference]. Figure 5 .

[0097] Comparative Example 3

[0098] Comparative Example 3 discloses a method for preparing vanadium oxysulfate crystals, which is basically the same as that of Example 3, except that the valence state was not adjusted before crystallization in step (6), and the valence state of the solution was kept at 3.95.

[0099] Table 3 Elemental Analysis

[0100]

[0101] Example 4

[0102] This embodiment discloses a method for preparing high-purity, highly soluble vanadium oxysulfate crystals, including the following steps:

[0103] (1) Using ammonium polyvanadate as raw material, calcined at 630℃ under nitrogen protection and hydrogen reduction conditions for 3h, vanadium oxide solid with V content of 60.8% was obtained.

[0104] (2) Mix 510 ml of concentrated sulfuric acid and 300 ml of pure water, then add 460 g of vanadium oxide solid. Maintain the reaction temperature at 100 °C. After the reaction, add pure water to bring the total volume to 1000 ml to obtain C. (V) It is 5.5 mol / L, C (S / V) The vanadium oxysulfate solution has a concentration of 1.69.

[0105] (3) Add 80g of vanadium trioxide (V2O3) to the above vanadium oxysulfate concentrate, adjust the valence state of V in the solution to 4.06, the reaction temperature is 95℃, and the reaction time is 2h.

[0106] (4) Cool the solution after valence adjustment at a rate of 20℃ / h, the crystallization endpoint temperature is 45℃, and the total crystallization time is 6h to obtain a primary vanadium oxysulfate crystal slurry. Filter to obtain primary vanadium oxysulfate crystals.

[0107] (5) Dissolve the vanadium oxysulfate crystals in pure water to prepare a 3.0 mol / L vanadium oxysulfate solution, and filter it using a 0.1 μm filter membrane.

[0108] (6) Add sulfuric acid to the filtered vanadium oxysulfate solution and cool to crystallize. The C in the vanadium oxysulfate solution after adding sulfuric acid... (S / V) The concentration was 3.5, the crystallization endpoint temperature was 30℃, and the crystallization time was 16h, resulting in a secondary vanadium oxysulfate crystal slurry; filtration yielded secondary vanadium oxysulfate crystals, namely high-purity vanadium oxysulfate crystals with high solubility.

[0109] The dissolution times of primary and secondary vanadium oxysulfate crystals in pure water were compared, and the dissolution times are detailed in Table 4.

[0110] Electrolyte performance was tested using a vanadium oxysulfate solution obtained after dissolving vanadium oxysulfate crystals in a secondary solution; the results are detailed below. Figure 6 .

[0111] Table 4 Comparison of dissolution times

[0112] Crystal type solvent Dissolution temperature Stirring speed Dissolution time Dissolving effect Vanadium oxysulfate crystals pure water 25℃ 120r / min 8min 100% Dissolved Vanadium oxysulfate crystals pure water 25℃ 120r / min 5min 100% Dissolved

[0113] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing high-purity, highly soluble vanadium oxysulfate crystals, characterized in that, Includes the following steps: Step 1: Calcining ammonium metavanadate or ammonium polyvanadate under inert gas and reducing atmosphere conditions to obtain vanadium oxide. The calcination temperature is 500-900℃ and the calcination time is 1-5h. Step 2: Mix vanadium oxide, pure water and sulfuric acid to obtain a high-concentration vanadium oxysulfate solution or vanadium oxysulfate slurry. The mixing temperature is 80-150℃. The vanadium concentration in the high-concentration vanadium oxysulfate solution or vanadium oxysulfate slurry is 4.5-6.5 mol / L, and the molar ratio of sulfur to vanadium is 1-3. Step 3: Adjust the valence state of vanadium in the high-concentration vanadium oxysulfate solution or vanadium oxysulfate slurry to 3.9-4.1, and react at 80-120℃ for 1-5 hours; Step 4: Cooling and crystallization. The final temperature of cooling and crystallization is 30-50℃, and the cooling and crystallization time is 1-12 hours to obtain primary vanadium oxysulfate crystal slurry. After filtration, primary vanadium oxysulfate crystals are obtained. Step 5: Dissolve the vanadium oxysulfate crystals in pure water to prepare a 2-4 mol / L vanadium oxysulfate solution. Use a filter membrane to remove vanadium oxide and silicic acid from the vanadium oxysulfate solution. Step 6: Add sulfuric acid to the filtered vanadium oxysulfate solution to adjust the valence state of vanadium, and then cool and crystallize. After adding sulfuric acid, the molar ratio of sulfur to vanadium in the vanadium oxysulfate solution is 1-5, and the valence state of vanadium is adjusted to 3.99-4.

01. The final temperature of cooling and crystallization is 0-40℃, and the cooling and crystallization time is 12-24h, to obtain a secondary vanadium oxysulfate crystal slurry; filter to obtain high-purity vanadium oxysulfate crystals with high solubility.

2. The method for preparing high-purity, high-solubility vanadium oxysulfate crystals according to claim 1, characterized in that, In step 1, vanadium oxide is prepared as V₂O₅, VO₂, V₂O₃, V₂O₄, V₄O₇, and V₆O₅. 13 One or more of them.

3. The method for preparing high-purity, high-solubility vanadium oxysulfate crystals according to claim 1, characterized in that, The inert gas mentioned in step 1 is one or more of nitrogen, argon, and helium; And / or, the reducing atmosphere is one or more of hydrogen, carbon monoxide, ammonia, and methane.

4. The method for preparing high-purity, high-solubility vanadium oxysulfate crystals according to claim 1, characterized in that, Step 3 involves adjusting the valence state of vanadium in a high-concentration vanadium oxysulfate solution or vanadium oxysulfate slurry by adding vanadium compounds, wherein the vanadium compounds are V₂O₅, V₂O₃, V₂(SO₄)₃ crystals, V₄O₇, or V₆O₅. 13 One or more of V(OH)3 solid.

5. The method for preparing high-purity, high-solubility vanadium oxysulfate crystals according to claim 1, characterized in that, Step 4: The cooling rate is 10-20℃ / h.

6. The method for preparing high-purity, high-solubility vanadium oxysulfate crystals according to claim 1, characterized in that, In step 5, the filter membrane accuracy is 0.5–5 μm.

7. A high-purity, highly soluble vanadium oxysulfate crystal, characterized in that, It is prepared by the method described in any one of claims 1-7.

8. The high-purity, high-solubility vanadium oxysulfate crystal according to claim 8, characterized in that, The purity of the high-purity, high-solubility vanadium oxysulfate crystals is ≥99.5%.

9. The high-purity, high-solubility vanadium oxysulfate crystal according to claim 8, characterized in that, The high-purity, high-solubility vanadium oxysulfate crystals have a D90 < 100 μm.

10. The application of the high-purity, high-solubility vanadium oxysulfate crystals as described in any one of claims 7-9 in the field of vanadium electrolytes.

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