Ultra-pure vanadium pentoxide and preparation method thereof

Abstract

The invention provides ultrapure vanadium pentoxide and a preparation method thereof, and the preparation method of the ultrapure vanadium pentoxide comprises the following steps: mixing vanadium oxide and sulfur to obtain a vanadium solution, stirring and heating until the vanadium solution is completely dissolved, cooling and reacting, and filtering to obtain vanadium-containing crystals; dissolving the vanadium-containing crystal to obtain a vanadium-containing crystal solution, and adding an ammonium source, a complexing agent and an oxidizing agent to convert vanadium into anions so as to further obtain ultrapure AMV; and drying, dehydrating, oxidizing and calcining to obtain the ultrapure vanadium pentoxide. The purity of the prepared ultrapure vanadium pentoxide is larger than or equal to 99.99%, the content of each impurity element of K, Na, Ca and S is within 10 ppm, the content of other impurity elements is within 5 ppm, and the total impurity content in the vanadium pentoxide does not exceed 100 ppm. With the development of an all-vanadium redox flow battery technology, the ultra-pure vanadium pentoxide has good application prospects and large-scale industrial popularization potential in the field of high-purity vanadium reagents.

Description

Technical Field

[0001] The invention relates to a preparation technology of ultrapure vanadium pentoxide, in particular to ultrapure vanadium pentoxide and a preparation method thereof. Background Art

[0002] Chinese patent CN105800689A discloses a method for preparing ultrapure vanadium pentoxide, which adopts the following process steps: first pre-removal of impurities, transfer phosphorus and silicon in the vanadium-containing solution to the solid phase for removal, then calcify and precipitate vanadium, transfer vanadium in the liquid phase to the calcium vanadate phase, remove impurities such as chromium, manganese, potassium, and sodium in the liquid phase, then dissolve the vanadium in the calcium vanadate into the liquid phase through ammonium bicarbonate and / or ammonium carbonate, remove calcium, phosphorus, silicon, iron, and magnesium in the solid phase, and then replace the residual trace cations in the liquid phase with ammonium ions through an ammonium cation exchange system to achieve deep purification, and then cool and precipitate vanadium and deammoniate and calcine to obtain vanadium pentoxide. The above technical solution has the following problems:

[0003] 1. The impurity removal process of this technical solution has many steps, a long and complicated process, and there will be a certain amount of vanadium loss in the solid-liquid conversion process.

[0004] 2. The purity of the vanadium pentoxide prepared is above 99.95%, but not above 99.99%;

[0005] 3. This technical solution uses 2-octanol and / or 1-octanol in the reaction process, which will increase the organic matter content in the precipitated calcium carbonate and pollute the environment.

[0006] Chinese patent CN102531054A discloses a method for purifying ammonium metavanadate and a method for preparing high-purity vanadium pentoxide, which mainly comprises the following steps: dissolving crude ammonium metavanadate in deionized water at 70 to 100°C, adjusting the pH value of the solution to 8 to 10, adding water-soluble magnesium salt and / or calcium salt to generate precipitation with impurity anions, further adjusting the pH value of the filtrate to 10 to 12 after filtering, so that impurity cations in the filtrate are precipitated, and adding Water-soluble ammonium salt or concentrated ammonia water, and the solution is cooled to room temperature to precipitate ammonium metavanadate, the obtained ammonium metavanadate is filtered and washed with deionized water, and then the obtained ammonium metavanadate is dissolved in deionized water at 70 to 100°C again, and water-soluble ammonium salt or concentrated ammonia water is added, and the insoluble matter is filtered, and then the solution is cooled to room temperature to generate ammonium metavanadate precipitation, and the obtained ammonium metavanadate is filtered and washed, and after dehydration, calcined at 210 to 650°C to obtain vanadium pentoxide with a purity greater than or equal to 99.9%. The above technical solution has the following problems:

[0007] 1. This method has great limitations in application. The chemical precipitation method uses water-soluble salts to remove impurities. The reagent must be of analytical purity or above and the amount used is large, so the implementation cost is extremely high.

[0008] 2. Due to the uncertainty of impurity composition, adding reagents may easily exceed the theoretical amount and introduce new impurities.

[0009] Chinese patent CN103663557A discloses a method for preparing high-purity vanadium pentoxide from crude vanadium, in which crude vanadium is dissolved with caustic soda, the pH of the dissolution end point is controlled at 7-8.5, the ferric hydroxide colloid is removed by filtration, and then hydrogen peroxide is added to the filtrate for oxidation, and the colloid is removed by filtration; an anion exchange resin is then used, and after the resin is saturated, an acid solution is used for analysis, and ammonia water is added to the analysis solution to precipitate vanadium, and red vanadium is produced, filtered, washed with pure water, and the red vanadium is roasted to produce high-purity vanadium pentoxide with a purity greater than 99.9%. The above technical solution has the following problems:

[0010] 1. Limitations of this method in application: Conventional ion exchange methods use anion exchange resins for ion removal, which has the problem of non-specific selectivity. Anion impurities are easily adsorbed on the resin, which contaminates the vanadium solution after analysis.

[0011] 2. This method uses 3 to 5 times the volume of deionized water to wash the red vanadium for 3 to 5 times, which consumes a lot of washing water and causes high energy consumption in the subsequent concentration process. In addition, the vanadium precipitation tail liquid contains a large amount of Cl ions, and the concentration requires extremely high anti-corrosion performance of the equipment.

[0012] 3. The purity of the high-purity vanadium pentoxide product obtained by this method cannot reach 99.99% and the impurities in the product are difficult to stably control, which cannot fully meet the demand for high-end vanadium products.

[0013] With the development of technology, the application demand of ultrapure V2O5 is also gradually increasing, including reference reagents, target materials, etc. The purity level of V2O5 and the corresponding impurity element content indicators specified in the existing standards are difficult to meet the demand, especially ultrapure V2O5 cannot meet the market demand. This is mainly due to the lack of efficient preparation technology of ultrapure V2O5 with a purity of more than 99.99% at home and abroad, which leads to the high price of ultrapure V2O5. For example, the price of ultrapure V2O5 on the Sigma Reagent Network reaches 1,000 yuan / gram, and its purity requirement is only 99.95%. The low production capacity and the accompanying high price limit the widespread application of ultrapure V2O5. Summary of the invention

[0014] The purpose of the present invention is to propose a method for preparing ultra-pure vanadium pentoxide in view of the problem that the purity of vanadium pentoxide prepared by the existing method is low. The purity of the vanadium pentoxide prepared by the method is greater than or equal to 99.99%, each impurity element of K, Na, Ca, and S is within 10ppm, and other impurity elements are within 5ppm, and the total impurities in the vanadium pentoxide do not exceed 100ppm. With the development of all-vanadium liquid flow battery technology, the ultra-pure vanadium pentoxide of the present invention has good application prospects and large-scale industrial promotion potential in the field of high-purity vanadium reagents.

[0015] It should be noted that, in the present invention, unless otherwise specified, the specific meaning of "including" in relation to composition limitations and descriptions includes both open-ended "including", "comprising", etc. and similar meanings, as well as closed-ended "composed of", "composed of", etc. and similar meanings.

[0016] To achieve the above object, the technical solution adopted by the present invention is: a method for preparing ultrapure vanadium pentoxide, comprising the following steps:

[0017] Step 1: Mix vanadium oxide, high-purity water and acid, stir and heat to 70-100° C., react for 0.5-3 h to completely dissolve the vanadium solution, cool to 40-65° C., continue stirring and crystallizing for 5-20 h, and filter to obtain vanadium-containing crystals;

[0018] Step 2: dissolving the vanadium-containing crystals with high-purity water to obtain a vanadium-containing crystal solution with a V concentration of 0.5 to 3 mol / L;

[0019] Step 3: first add an ammonium source to the vanadium crystal solution to adjust the solution pH to 6-9; add a complexing agent, adjust the solution temperature to 40-80° C., then add an ammonium source and an oxidant simultaneously to ensure that the solution pH is 6-9, react for 0.5-2 hours, and obtain ultrapure AMV;

[0020] Step 4: drying and dehydrating the ultrapure AMV;

[0021] Step 5: oxidatively calcining the ultrapure AMV at a temperature of 450 to 650° C. for a time of 0.5 to 8 hours to obtain ultrapure vanadium pentoxide.

[0022] Furthermore, the vanadium oxide in step 1 is one or more of vanadium pentoxide, vanadium tetroxide, vanadium trioxide and vanadium dioxide, and the impurities contained in the vanadium oxide and their contents are: 80ppm≤K≤500ppm, 50ppm≤Na≤500ppm, 5ppm≤Cr≤100ppm, 10ppm≤Ca≤30ppm.

[0023] Furthermore, the acid in step 1 is one or more of sulfuric acid, hydrochloric acid, phosphoric acid and oxalic acid.

[0024] Furthermore, the acid in step 1 is preferably sulfuric acid, and the concentration of the sulfuric acid is not less than 92.5%, which is a high-quality concentrated sulfuric acid in GB / T 534.

[0025] Furthermore, in step 1, the V concentration in the vanadium solution is 2-6 mol / L, the molar ratio of anions in the acid to V is 1.1-3, the V concentration is preferably 5-6 mol / L, and the molar ratio of anions in the acid to V is preferably 1.4-2.0.

[0026] Furthermore, in step 1, the temperature is raised to 90-100° C. with stirring, and the mixture is reacted for 2-3 hours to completely dissolve the vanadium to obtain a vanadium solution.

[0027] Furthermore, in step 1, the temperature is cooled to 50-60° C., and the stirring crystallization time is 8-15 hours.

[0028] Furthermore, the cooling rate in step 1 is preferably 0.3-2°C / min. The cooling rate has an impact on the particle size of the crystals. Too fast a cooling rate will lead to small crystal size, difficulty in filtration, high water content, high impurities and other problems. The vanadium-containing crystals (such as VOSO4 crystals) obtained by crystallization at the above-mentioned specific cooling rate have large particle size, low water content and low impurity content.

[0029] Furthermore, the vanadium-containing crystals in step 1 are one or more of vanadium sulfate, vanadium oxysulfate, vanadium trichloride (VCl3), vanadium oxychloride (VOCl2), vanadium oxyoxalate (VOC2O4), vanadium oxyhydrogen phosphate (VOHPO4), vanadium phosphate (VPO4) and their hydrates.

[0030] Furthermore, the V concentration in the vanadium-containing crystal solution in step 2 is 1 to 1.5 mol / L.

[0031] Furthermore, the conductivity of the pure water in step 2 is ≤10uS / cm, preferably ≤5uS / cm.

[0032] Furthermore, in step 3, the vanadium crystal solution is first filtered to filter out the insoluble silicate and vanadium slag.

[0033] Furthermore, the complexing agent in step 3 is one or more of sodium tripolyphosphate, sodium pyrophosphate, sodium hexametaphosphate, monoethanolamine, diethanolamine, triethanolamine, sodium nitrilotriacetate (Na-NTA), disodium ethylenediaminetetraacetate (EDTA-2Na), diethylenetriamine pentacarboxylate (DTPA), tartaric acid, sodium gluconate and sodium alginate, preferably EDTA-2Na.

[0034] Furthermore, in step 3, the oxidant is one or more of air, oxygen, ozone, perchloric acid, sodium chlorate, potassium chlorate, potassium permanganate, ammonium persulfate, hydrogen peroxide, ammonium chloride and sodium persulfate. The oxidant is preferably hydrogen peroxide, and the concentration of hydrogen peroxide is 25-30%.

[0035] Furthermore, the ammonium source in step 3 is one or more of ammonia water, ammonium carbonate and ammonium bicarbonate. The ammonium source is preferably ammonia water with a concentration of 10-25%.

[0036] Furthermore, in step 3, the liquid-to-solid ratio of the vanadium-containing crystal solution to the complexing agent is 3000:0.1 to 3000:1, the liquid-to-solid ratio of the vanadium-containing crystal solution to the oxidant is 20:1 to 10:1, and the volume ratio of the vanadium-containing crystal solution to aqueous ammonia is 3:1 to 1:1.

[0037] Furthermore, in step 3, the solution temperature is adjusted to 50-80° C., and an ammonium source and an oxidant are added simultaneously to ensure that the pH value of the solution is 7-8. After all the solid precipitates in the solution reaction are oxidized to become a colorless or light yellow solution, the reaction is continued for 0.5-1 h to obtain ultrapure AMV.

[0038] Furthermore, the moisture content of the ultrapure AMV after drying in step 4 is ≤2%.

[0039] Furthermore, the calcination temperature in step 5 is 550-600° C., and the calcination time is 0.5-5 h.

[0040] Another object of the present invention is to disclose ultrapure vanadium pentoxide, which is prepared by the above method and has a purity greater than or equal to 99.99%.

[0041] Furthermore, the ultrapure vanadium pentoxide has a V2O4 content of ≤0.1%, an orange color, and no black spots. It should be noted that the vanadium tetroxide in the vanadium pentoxide is not an impurity but a low-valent vanadium. Too high a vanadium tetroxide content will affect the appearance of the vanadium pentoxide, which is black.

[0042] Furthermore, each impurity element of K, Na, Ca, and S in the ultra-pure vanadium pentoxide is controlled within 10 ppm, and other impurity elements can be controlled within 5 ppm, and the total impurities in the vanadium pentoxide do not exceed 100 ppm.

[0043] Furthermore, the bulk density of the ultrapure vanadium pentoxide is 0.8 to 1.2.

[0044] Furthermore, the ultrapure vanadium pentoxide has an agglomerated spherical shape and a particle size D90 of 200 to 400 μm.

[0045] Another object of the present invention is to disclose the use of ultra-pure vanadium pentoxide in the field of high-purity vanadium reagents and target materials.

[0046] The ultrapure vanadium pentoxide and the preparation method thereof of the present invention have the following advantages compared with the prior art:

[0047] 1) The method for preparing ultrapure vanadium pentoxide of the present invention is a method combining cation impurity removal, anion impurity removal and complex impurity removal. First, vanadium is converted into cations, and vanadium is separated from cationic impurities by a crystallization process; in the process of vanadium precipitation, a complexing agent is added to keep the impurity cations soluble, and an ammonium salt is added to precipitate vanadium in the form of ammonium metavanadate and separate it from the impurity anions. The present invention can achieve simultaneous deep impurity removal of anions and cations to obtain ultrapure vanadium products.

[0048] 2) The purity of the ultrapure vanadium pentoxide prepared by the present invention is 99.99% or above;

[0049] 3) The method for preparing ultrapure vanadium pentoxide of the present invention has a simple and reliable production process and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 The present invention is a flow chart of the preparation method of ultrapure vanadium pentoxide. DETAILED DESCRIPTION

[0051] The present invention is further described below with reference to the examples. 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:

[0052] Unless otherwise stated, the units used in this specification are all international standard units, and the numerical values ​​and numerical ranges appearing in the present invention should be understood to include the inevitable systematic errors in industrial production.

[0053] In this specification, the numerical range expressed using "a numerical value A to a numerical value B" means a range including the endpoints numerical values ​​A and B.

[0054] In the present specification, a numerical range expressed using "above" or "below" means a numerical range including the number.

[0055] In this specification, the word "may" means both performing a certain process and not performing a certain process.

[0056] In this specification, the use of "optional" or "optional" indicates that certain substances, components, execution steps, application conditions and other factors are used or not used.

[0057] In this specification, when "normal temperature" or "room temperature" is used, the temperature may be 15-25°C.

[0058] In this manual, the reagents or instruments used without indicating the manufacturer are all conventional products that can be obtained through commercial purchase.

[0059] Unless otherwise specified, % in the present invention refers to mass percentage.

[0060] Example 1

[0061] Example 1 discloses an ultrapure vanadium pentoxide, such as Figure 1 As shown, the preparation method thereof comprises the following steps:

[0062] Step 1: Add 403g of concentrated sulfuric acid to 300ml of high-purity water, then add 220g of vanadium tetroxide (the impurities and contents of vanadium tetroxide are: K 300ppm, Na 200ppm, Cr 18ppm, Ca 30ppm), stir and heat to 95°C, react for 3h to completely dissolve it, cool to 50°C, continue stirring and crystallizing for 10h, and filter to obtain vanadium sulfate crystals.

[0063] Step 2: dissolving vanadyl sulfate with high-purity water and adjusting V=1.2 mol / L to obtain a vanadium-containing crystal solution.

[0064] Step 3: First add 12% ammonia water to the vanadyl sulfate solution to adjust the solution pH to 8, add the complexing agent EDTA-2Na, adjust the solution temperature to 60°C, then add 12% ammonia water and perchloric acid at the same time to ensure that the solution pH is 7-8, and after all the solid precipitates in the solution reaction are oxidized to become a light yellow solution, continue the reaction for 1 hour to obtain ultrapure AMV. The liquid-to-solid ratio of the vanadyl sulfate solution to the complexing agent EDTA-2Na is 3000:0.5, the liquid-to-solid ratio of the vanadyl sulfate solution to perchloric acid is 15:1, and the volume ratio of the vanadyl sulfate solution to 12% ammonia water is 2:1.

[0065] Step 4: Dry and dehydrate the AMV until the moisture content is ≤2%, hereinafter referred to as ultrapure dry AMV.

[0066] Step 5: The ultrapure dry AMV is subjected to oxidation calcination in a dynamic tube furnace at a calcination temperature of 600° C. for 1 h to obtain ultrapure vanadium pentoxide with a purity of 99.995%.

[0067] The detection data of impurities in the vanadyl sulfate crystals of Example 1 are summarized in Table 1.

[0068] Table 1 Impurity detection data of vanadyl sulfate crystals

[0069]

[0070]

[0071] The impurity detection data of ultrapure dry AMV in Example 1 are summarized in Table 2.

[0072] Table 2 Ultrapure dry AMV impurity detection data

[0073] K (wt%) Na (wt%) Fe (wt%) Al (wt%) Cr (wt%) Ca (wt%) Mg (wt%) 0.0002 0.0002 0.0000 0.0002 0.0001 0.0000 0.0002

[0074] It can be seen from Table 2 that each impurity element such as K, Na, Ca, etc. in ultra-pure AMV is controlled within 3 pp m.

[0075] The test data of ultrapure vanadium pentoxide in Example 1 are summarized in Table 3.

[0076] Table 3 Ultrapure vanadium pentoxide test data

[0077]

[0078] It can be seen from Table 4 that the V2O5 content of the ultrapure vanadium pentoxide prepared in this embodiment can reach 99.995%, each impurity element such as K, Na, Ca, S can be controlled within 6 ppm, and the total impurities in the vanadium pentoxide do not exceed 100 ppm.

[0079] Example 2

[0080] Example 2 discloses an ultrapure vanadium pentoxide, such as Figure 1 As shown, the preparation method thereof comprises the following steps:

[0081] Step 1: Add 240g of vanadium pentoxide (the impurities and contents of vanadium pentoxide are: K 200ppm, Na 200ppm, Cr 20ppm, Ca 20ppm) to 300ml of high-purity water, then add 507g of oxalic acid dihydrate, stir and heat to 95°C, react for 3h to completely dissolve it, cool to 50°C, continue stirring and crystallizing for 12h, and filter to obtain vanadium oxalate crystals.

[0082] Step 2: dissolving vanadyl oxalate with high-purity water and adjusting V=1.4 mol / L to obtain a vanadium-containing crystal solution.

[0083] Step 3: First add ammonium carbonate to the vanadium oxalate solution to adjust the solution pH to 8, add the complexing agent ammonium alginate, adjust the solution temperature to 60°C, then add ammonium carbonate and ammonium persulfate at the same time to ensure that the solution pH is 7-8, and after all the solid precipitates in the solution reaction are oxidized to become a light yellow solution, continue the reaction for 0.8h to obtain ultrapure AMV. The liquid-solid ratio of the vanadium oxalate solution to the complexing agent sodium alginate is 3000:0.4, the liquid-solid ratio of the vanadium oxalate solution to ammonium persulfate is 13:1, and the volume ratio of the vanadium oxalate solution to ammonium carbonate is 3:1.

[0084] Step 4: Dry and dehydrate the AMV until the moisture content is ≤2%, hereinafter referred to as ultrapure dry AMV.

[0085] Step 5: The ultrapure dry AMV is subjected to oxidation calcination in a dynamic tube furnace at a calcination temperature of 590° C. for 1.5 h to obtain ultrapure vanadium pentoxide with a purity of 99.992%.

[0086] The detection data of impurities in the vanadium oxalate crystals of Example 2 are summarized in Table 4.

[0087] Table 4 Impurity detection data of vanadium oxalate crystals

[0088] K (wt%) Na (wt%) Fe (wt%) Al (wt%) Cr (wt%) Ca (wt%) Mg (wt%) 0.0010 0.0008 0.0003 0.0008 0.0002 0.0005 0.0001

[0089] The impurity detection data of ultrapure dry AMV in Example 2 are summarized in Table 5.

[0090] Table 5 Ultrapure dry AMV impurity detection data

[0091] K (wt%) Na (wt%) Fe (wt%) Al (wt%) Cr (wt%) Ca (wt%) Mg (wt%) 0.0002 0.0000 0.0000 0.0002 0.0002 0.0000 0.0001

[0092] It can be seen from Table 2 that each impurity element such as K, Na, Ca, etc. in ultra-pure AMV is controlled within 3 pp m.

[0093] The test data of ultrapure vanadium pentoxide in Example 2 is summarized in Table 6.

[0094] Table 6 Ultrapure vanadium pentoxide test data

[0095]

[0096] It can be seen from Table 6 that the V2O5 content of the ultrapure vanadium pentoxide prepared in this embodiment is 99.992%, each impurity element such as K, Na, Ca, S can be controlled within 10 ppm, and the total impurities in the vanadium pentoxide do not exceed 100 ppm.

[0097] Example 3

[0098] Example 3 discloses an ultrapure vanadium pentoxide, such as Figure 1 As shown, the preparation method thereof comprises the following steps:

[0099] Step 1: Add 403g of concentrated sulfuric acid to 300ml of high-purity water, then add 200g of vanadium trioxide (the impurities and contents of vanadium trioxide are: K 250ppm, Na 200ppm, Cr 15ppm, Ca 20ppm), stir and heat to 95°C, react for 3h to completely dissolve it, cool to 50°C, continue stirring and crystallizing for 13h, and filter to obtain vanadium sulfate crystals.

[0100] Step 2: Dissolve vanadium sulfate with high-purity water and adjust V=1.3 mol / L to obtain a vanadium-containing crystal solution.

[0101] Step 3: First add ammonium bicarbonate to the vanadium sulfate solution to adjust the solution pH to 8, add the complexing agent sodium gluconate, adjust the solution temperature to 60°C, then add ammonium bicarbonate and sodium persulfate simultaneously to ensure that the solution pH is between 7 and 8, and after all the solid precipitates in the solution reaction are oxidized to become a light yellow solution, continue the reaction for 1 hour to obtain ultrapure AMV. The liquid-to-solid ratio of the vanadium sulfate solution to the complexing agent sodium gluconate is 3000:0.6, the liquid-to-solid ratio of the vanadium sulfate solution to sodium persulfate is 16:1, and the volume ratio of the vanadium sulfate solution to ammonium bicarbonate is 2:1.

[0102] Step 4: Dry and dehydrate the AMV until the moisture content is ≤2%, hereinafter referred to as ultrapure dry AMV.

[0103] Step 5: The ultrapure dry AMV is subjected to oxidation calcination in a dynamic tube furnace at a calcination temperature of 580° C. for 2 h to obtain ultrapure vanadium pentoxide with a purity of 99.994%.

[0104] The detection data of impurities in vanadium sulfate crystals of Example 3 are summarized in Table 7.

[0105] Table 7 Impurity detection data of vanadium sulfate crystals

[0106] K (wt%) Na (wt%) Fe (wt%) Al (wt%) Cr (wt%) Ca (wt%) Mg (wt%) 0.0008 0.0004 0.0002 0.0007 0.0002 0.0001 0.0001

[0107] The impurity detection data of ultrapure dry AMV in Example 3 are summarized in Table 8.

[0108] Table 8 Ultrapure dry AMV impurity detection data

[0109] K (wt%) Na (wt%) Fe (wt%) Al (wt%) Cr (wt%) Ca (wt%) Mg (wt%) 0.0000 0.0003 0.0000 0.0000 0.0001 0.0000 0.0001

[0110] It can be seen from Table 8 that each impurity element such as K, Na, Ca, etc. in the ultra-pure AMV is controlled within 5 pp m.

[0111] The test data of ultrapure vanadium pentoxide in Example 3 are summarized in Table 9.

[0112] Table 9 Ultrapure vanadium pentoxide test data

[0113]

[0114] It can be seen from Table 9 that the V2O5 content of the ultrapure vanadium pentoxide prepared in this embodiment is 99.994%, each impurity element such as K, Na, Ca, S can be controlled within 10 ppm, and the total impurities in the vanadium pentoxide do not exceed 100 ppm.

[0115] Example 4

[0116] Example 4 discloses an ultrapure vanadium pentoxide, such as Figure 1 As shown, the preparation method thereof comprises the following steps:

[0117] Step 1: Add 220g of phosphoric acid to 300ml of high-purity water, then add 220g of vanadium tetroxide (the impurities and contents of vanadium tetroxide are: K 100ppm, Na 200ppm, Cr 10ppm, Ca 20ppm), stir and heat to 95°C, react for 3h to completely dissolve it, cool to 50°C, continue stirring and crystallizing for 15h, and filter to obtain vanadium hydrogen phosphate crystals.

[0118] Step 2: Dissolve vanadium hydrogen phosphate with high-purity water and adjust V=1.5 mol / L to obtain a vanadium-containing crystal solution.

[0119] Step 3: first add ammonium carbonate to the vanadium hydrogen phosphate solution to adjust the solution pH to 8, add the complexing agent diethanolamine, adjust the solution temperature to 60°C, then add ammonium carbonate and sodium chlorate simultaneously to ensure that the solution pH is between 7 and 8, and after all the solid precipitates in the solution reaction are oxidized to become a light yellow solution, continue the reaction for 1 hour to obtain ultrapure AMV. The liquid-to-solid ratio of the vanadium hydrogen phosphate solution to the complexing agent diethanolamine is 3000:0.5, the liquid-to-solid ratio of the vanadium hydrogen phosphate solution to sodium chlorate is 18:1, and the volume ratio of the vanadium hydrogen phosphate solution to ammonium carbonate is 2:1.

[0120] Step 4: Dry and dehydrate the AMV until the moisture content is ≤2%, hereinafter referred to as ultrapure dry AMV.

[0121] Step 5: The ultrapure dry AMV is oxidatively calcined in a dynamic tube furnace at a calcination temperature of 600° C. for 2 hours to obtain ultrapure vanadium pentoxide with a purity of 99.995%.

[0122] The detection data of impurities in the vanadium hydrogen phosphate crystals of Example 4 are summarized in Table 10.

[0123] Table 10 Impurity detection data of vanadium hydrogen phosphate crystal

[0124] K (wt%) Na (wt%) Fe (wt%) Al (wt%) Cr (wt%) Ca (wt%) Mg (wt%) 0.0014 0.0008 0.0003 0.0008 0.0003 0.0007 0.0002

[0125] The impurity detection data of ultrapure dry AMV in Example 4 are summarized in Table 11.

[0126] Table 11 Ultrapure dry AMV impurity detection data

[0127] K (wt%) Na (wt%) Fe (wt%) Al (wt%) Cr (wt%) Ca (wt%) Mg (wt%) 0.0002 0.0001 0.0001 0.0001 0.0003 0.0000 0.0002

[0128] It can be seen from Table 11 that each impurity element such as K, Na, Ca, etc. in the ultra-pure AMV is controlled within 5 pp m.

[0129] The test data of ultrapure vanadium pentoxide in Example 4 is summarized in Table 12.

[0130] Table 12 Ultrapure vanadium pentoxide test data

[0131]

[0132] It can be seen from Table 12 that the V2O5 content of the ultrapure vanadium pentoxide prepared in this embodiment is 99.995%, each impurity element such as K, Na, Ca, S can be controlled within 10 ppm, and the total impurities in the vanadium pentoxide do not exceed 100 ppm.

[0133] Finally, it should be noted that 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 aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements 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 ultrapure vanadium pentoxide, characterized in that: The following steps are involved: Step 1: Mix vanadium oxide, high-purity water and acid, stir and heat to 70-100° C., react for 0.5-3 h to completely dissolve the vanadium solution, cool to 40-65° C., continue stirring and crystallizing for 5-20 h, and filter to obtain vanadium-containing crystals; Step 2: dissolving the vanadium-containing crystals with high-purity water to obtain a vanadium-containing crystal solution with a V concentration of 0.5 to 3 mol / L; Step 3: first add an ammonium source to the vanadium crystal solution to adjust the solution pH to 6-9, add a complexing agent, adjust the solution temperature to 40-80° C., then add an ammonium source and an oxidant simultaneously to ensure that the solution pH is 6-9, react for 0.5-2 hours, and obtain ultrapure AMV; Step 4: drying and dehydrating the ultrapure AMV; Step 5: oxidatively calcining the ultrapure AMV at a temperature of 450 to 650° C. for a time of 0.5 to 8 hours to obtain ultrapure vanadium pentoxide.

2. The method for preparing ultrapure vanadium pentoxide according to claim 1, characterized in that: The vanadium oxide in step 1 is one or more of vanadium pentoxide, vanadium tetroxide, vanadium trioxide and vanadium dioxide; And / or, the impurities and contents of the vanadium oxide are: 80ppm≤K≤500ppm, 50ppm≤Na≤500ppm, 5ppm≤Cr≤100ppm, 10ppm≤Ca≤30ppm; and / or, the acid is one or more of sulfuric acid, hydrochloric acid, phosphoric acid and oxalic acid; and / or, the V concentration in the vanadium solution is 2-6 mol / L, and the molar ratio of anions to V in the acid is 1.1-3; And / or, the cooling rate is 0.1-5°C / min.

3. The method for preparing ultrapure vanadium pentoxide according to claim 1, characterized in that: The vanadium-containing crystals in step 1 are one or more of vanadium sulfate, vanadium oxysulfate, vanadium trichloride, vanadium oxychloride, vanadium oxyoxalate, vanadium oxyhydrogen phosphate, vanadium phosphate, and hydrates thereof.

4. The method for preparing ultrapure vanadium pentoxide according to claim 1, characterized in that: The conductivity of the pure water in step 2 is ≤10uS / cm.

5. The method for preparing ultrapure vanadium pentoxide according to claim 1, characterized in that: The complexing agent in step 3 is one or more of sodium tripolyphosphate, sodium pyrophosphate, sodium hexametaphosphate, monoethanolamine, diethanolamine, triethanolamine, sodium nitrilotriacetate, disodium ethylenediaminetetraacetate, diethylenetriamine pentacarboxylate, tartaric acid, sodium gluconate and sodium alginate; and / or, the oxidant is one or more of air, oxygen, ozone, perchloric acid, sodium chlorate, potassium chlorate, potassium permanganate, ammonium persulfate, hydrogen peroxide, ammonium chloride and sodium persulfate; And / or, the ammonium source is one or more of aqueous ammonia, ammonium carbonate and ammonium bicarbonate; And / or, the liquid-solid ratio of the vanadium-containing crystal solution to the complexing agent is 3000:0.1-3000:1, the liquid-solid ratio of the vanadium-containing crystal solution to the oxidant is 20:1-10:1, and the volume ratio of the vanadium-containing crystal solution to ammonia water is 3:1-1:

1.

6. The method for preparing ultrapure vanadium pentoxide according to claim 1, characterized in that: The moisture content of the ultrapure AMV after drying in step 4 is ≤2%.

7. The method for preparing ultrapure vanadium pentoxide according to claim 1, characterized in that: The calcination temperature in step 5 is 550-600° C., and the calcination time is 0.5-5 h.

8. An ultrapure vanadium pentoxide, characterized in that: The product is prepared by the above method and has a purity greater than or equal to 99.99%.

9. The ultrapure vanadium pentoxide according to claim 8, characterized in that: Each impurity element of K, Na, Ca, and S in ultra-pure vanadium pentoxide is controlled within 10ppm, and other impurity elements are controlled within 5ppm. The total impurities in vanadium pentoxide do not exceed 100ppm.

10. The ultrapure vanadium pentoxide according to claim 8, characterized in that: The bulk density of ultrapure vanadium pentoxide is 0.8 to 1.2.

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