Preparation method of high-purity vanadium pentoxide

Abstract

The invention relates to a preparation method of high-purity vanadium pentoxide, in particular to the field of high-purity vanadium pentoxide, which comprises the following steps: adding an impurity removal agent into a phosphorus-containing vanadium solution to remove impurities, and then carrying out solid-liquid separation to obtain filtrate; the obtained filtrate is sequentially subjected to first pH value adjustment, second pH value adjustment, ammonium salt vanadium precipitation, dehydration, calcination deamination and melting, and high-purity vanadium pentoxide is obtained; wherein the impurity removing agent is prepared from calcium salt and a flocculating agent; the final pH value of the first pH value adjustment is 4.5-5.5; the final pH value of the second pH value adjustment is 1.8-2.2. According to the preparation method provided by the invention, the vanadium in the vanadium liquid is efficiently recovered by matching the metallographic phase specific impurity removal process of the vanadium liquid with pH value adjustment, the purity of the obtained vanadium product is greater than or equal to 99.9%, and the recovery rate of the vanadium is greater than or equal to 98%.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of high-purity vanadium pentoxide, and particularly relates to a preparation method of high-purity vanadium pentoxide. BACKGROUND

[0002] In the vanadium extraction industry, there are mainly two processes of fire method and wet method. According to different raw materials for vanadium extraction, the vanadium production process also has differences. The main production process of most enterprises is the indirect vanadium extraction method taking the converter vanadium slag as the raw material, also known as the fire method, which includes five processes of vanadium slag treatment, roasting, leaching, precipitation and melting, and the final product is flaky V2O5.

[0003] The V2O5 grade produced by domestic enterprises is mostly between 98.0-98.5%, and most of which is applied in the steel industry. The V2O5 with a grade of more than 99.0% is mainly applied in the fields of energy storage batteries, catalysts and aerospace, among which the total amount used for catalysts is greater than 1000 tons / year, and the total amount used for all-vanadium redox flow batteries is about 20,000 tons / year. With the rapid development of the energy storage industry, the consumption of high-purity vanadium is increasing year by year.

[0004] At present, the high-end products in the vanadium application field include aerospace-grade vanadium-aluminum alloy, all-vanadium flow battery electrolyte, nanoscale vanadium functional material, vanadium catalyst, vanadium luminescent material, etc. For example, in the field of aerospace, vanadium-aluminum alloy is mainly used to produce jet engines, high-speed aircraft skeletons and rocket engine casings, and the requirements for specific elements of the raw material master alloy are extremely harsh. In the field of all-vanadium flow batteries, the performance of the electrolyte directly affects the performance of the vanadium battery, and the fundamental factor that determines the performance of the electrolyte is the impurity content. Therefore, the purity of the prepared raw material vanadium pentoxide can effectively improve the energy efficiency, working stability and service life of the ion exchange membrane of the vanadium battery. In the field of vanadium catalysts, the use of high-purity vanadium pentoxide as a catalyst can greatly shorten the reaction time and improve the product conversion rate.

[0005] As can be seen from the above, the purity of the flaky V2O5 product at the present stage cannot meet the increasingly stringent use requirements, and there are defects such as low purity and low recovery rate of the flaky V2O5 obtained by ammonium salt vanadium precipitation. SUMMARY

[0006] In view of the problems in the prior art, the purpose of the present application is to provide a preparation method of high-purity vanadium pentoxide to solve the defects of low purity and low recovery rate of flaky V2O5 obtained by ammonium salt vanadium precipitation.

[0007] To achieve this purpose, the present application adopts the following technical solutions:

[0008] The present application provides a preparation method of high-purity vanadium pentoxide, which comprises:

[0009] The impurities are removed by adding a decontaminating agent to the vanadium solution containing phosphorus, and then performing solid-liquid separation to obtain a filtrate;

[0010] The obtained filtrate is sequentially subjected to first pH adjustment, second pH adjustment, ammonium salt vanadium precipitation, dehydration, calcination and ammonia removal, and melting to obtain high-purity vanadium pentoxide.

[0011] The decontaminating agent comprises calcium salt and flocculant; the end point pH value of the first pH adjustment is 4.5-5.5; and the end point pH value of the second pH adjustment is 1.8-2.2.

[0012] The preparation method provided by the application realizes efficient recovery of vanadium in the vanadium solution by the metallographic specific decontamination process and pH adjustment, and the purity of the obtained vanadium product is ≥99.9%, and the recovery rate of vanadium is ≥98%.

[0013] As a preferred technical solution of the application, the calcium salt comprises calcium chloride and / or calcium nitrate.

[0014] As a preferred technical solution of the application, the addition amount of the calcium salt is 1.2-1.5 times the molar amount of the precipitated phosphorus.

[0015] As a preferred technical solution of the application, the flocculant comprises one or a combination of at least two of polyacrylamide, sodium polyacrylate or polymeric ferric sulfate.

[0016] As a preferred technical solution of the application, the addition amount of the flocculant is 3-5‰ of the mass of the vanadium solution containing phosphorus.

[0017] As a preferred technical solution of the application, the mass concentration of vanadium in the filtrate is 24-28 g / L.

[0018] As a preferred technical solution of the application, the temperature of the solution when the ammonium salt is added in the ammonium salt vanadium precipitation is 50-70℃.

[0019] Preferably, the addition amount of the ammonium salt in the ammonium salt vanadium precipitation is 0.8-1 times the mass of total vanadium in the solution.

[0020] Preferably, the vanadium precipitation temperature of the ammonium salt vanadium precipitation is 90-100℃.

[0021] Preferably, the time of the ammonium salt vanadium precipitation is 30-50 min.

[0022] As a preferred technical solution of the application, the dehydration comprises dehydration at 100-120℃ for ≥1 h.

[0023] As a preferred technical solution of the application, the calcination and ammonia removal comprises calcination at a temperature of 580-620℃ for ≥1 h.

[0024] As a preferred technical scheme of the present application, the melting comprises: treating at a temperature of 850-900 DEG C for > 0.5 h.

[0025] Compared with the prior art, the present application has the following beneficial effects:

[0026] (1) The preparation method provided by the present application reduces the introduction of impurities in the production process of vanadium pentoxide, improves the research and application of vanadium pentoxide grade, effectively reduces the content of silicon, phosphorus, iron and other impurities in the product, opens up the application market of vanadium pentoxide in the field of vanadium battery energy storage, and improves the competitiveness of the product.

[0027] (2) The preparation method provided by the present application realizes the balance of the melting, flash evaporation and calcination system by dehydrating, decomposing and deaminating the ammonium polyvanadate obtained by vanadium precipitation of ammonium salt, and utilizing the flue gas waste heat of the melting furnace to the flash drying system, achieving "three balances", i.e. material balance, heat balance and airflow balance, and realizing environmental protection production.

[0028] The present application will be further described in detail below. However, the following examples are only simple examples of the present application and do not represent or limit the protection scope of the present application, and the protection scope of the present application is subject to the claims. DETAILED DESCRIPTION

[0029] In order to better illustrate the present application and facilitate understanding of the technical scheme of the present application, the typical but non-limiting embodiments of the present application are as follows:

[0030] The present embodiment provides a preparation method of high-purity vanadium pentoxide, which comprises:

[0031] A deimpurity agent is added to the phosphorus-containing vanadium solution to remove impurities, and then solid-liquid separation is performed to obtain a filtrate;

[0032] The obtained filtrate is sequentially subjected to first pH adjustment, second pH adjustment, ammonium salt vanadium precipitation, dehydration, calcination deamination and melting to obtain high-purity vanadium pentoxide.

[0033] In the present application, high purity refers to a purity of > 99.9%.

[0034] In the present application, the phosphorus-containing vanadium solution can be selected from leaching solution obtained by sodium roasting of vanadium slag by water leaching or alkali leaching, etc., and the pH value of the solution is > 8.

[0035] The deimpurity agent comprises calcium salt and flocculant.

[0036] The calcium salt comprises calcium chloride and / or calcium nitrate.

[0037] The addition amount of the calcium salt is 1.2-1.5 times the molar amount of the theoretical precipitated phosphorus, for example, it can be 1.2 times, 1.22 times, 1.24 times, 1.26 times, 1.28 times, 1.3 times, 1.32 times, 1.34 times, 1.36 times, 1.38 times, 1.4 times, 1.42 times, 1.44 times, 1.46 times, 1.48 times or 1.5 times, etc., but not limited to the listed values, other unlisted values within the range also meet the requirements.

[0038] The flocculant includes one or a combination of at least two of polyacrylamide, sodium polyacrylate or polymeric ferric sulfate.

[0039] In the present application, the molecular weight of the polyacrylamide used is 8-20 million.

[0040] In the present application, the molecular weight of the sodium polyacrylate used is 5-7 million.

[0041] In the present application, the polymerization degree of the polymeric ferric sulfate used is 10-30.

[0042] The addition amount of the flocculant is 3-5 ‰ of the mass of the vanadium-containing phosphorus solution, for example, it can be 3 ‰, 3.2 ‰, 3.4 ‰, 3.6 ‰, 3.8 ‰, 4 ‰, 4.2 ‰, 4.4 ‰, 4.6 ‰, 4.8 ‰ or 5 ‰, etc., but not limited to the listed values, other unlisted values within the range also meet the requirements.

[0043] The mass concentration of vanadium in the filtrate is 24-28 g / L, for example, it can be 24 g / L, 24.5 g / L, 25 g / L, 25.5 g / L, 26 g / L, 26.5 g / L, 27 g / L, 27.5 g / L or 28 g / L, etc., but not limited to the listed values, other unlisted values within the range also meet the requirements.

[0044] The end point pH value of the first pH value adjustment is 4.5-5.5, for example, it can be 4.5, 4.6, 4.7, 4.8, 4.9, 5, 5.1, 5.2, 5.3, 5.4 or 5.5, etc., but not limited to the listed values, other unlisted values within the range also meet the requirements.

[0045] The end point pH value of the second pH value adjustment is 1.8-2.2, for example, it can be 1.8, 1.82, 1.84, 1.86, 1.88, 1.9, 1.92, 1.94, 1.96, 1.98, 2.02, 2.04, 2.06, 2.08, 2.1, 2.12, 2.14, 2.16, 2.18 or 2.2, etc., but not limited to the listed values, other unlisted values within the range also meet the requirements.

[0046] In the present application, the pH value can be adjusted by using common pH value adjusting agents such as sulfuric acid, hydrochloric acid, nitric acid, etc.

[0047] The temperature of the solution when the ammonium salt is added in the ammonium salt vanadium precipitation is 50-70℃, for example, it can be 50℃, 52℃, 54℃, 56℃, 58℃, 60℃, 62℃, 64℃, 66℃, 68℃, or 70℃, etc., but not limited to the listed values, other values not listed in this range are also required.

[0048] The amount of ammonium salt added in the ammonium salt vanadium precipitation is 0.8-1 times the mass of vanadium in the solution, for example, it can be 0.8 times, 0.82 times, 0.84 times, 0.86 times, 0.88 times, 0.9 times, 0.92 times, 0.94 times, 0.96 times, 0.98 times, or 1 times, etc., but not limited to the listed values, other values not listed in this range are also required.

[0049] The vanadium precipitation temperature of the ammonium salt vanadium precipitation is 90-100℃, for example, it can be 90℃, 91℃, 92℃, 93℃, 94℃, 95℃, 96℃, 97℃, 98℃, 99℃, or 100℃, etc., but not limited to the listed values, other values not listed in this range are also required.

[0050] The time of the ammonium salt vanadium precipitation is 30-50min, for example, it can be 30min, 32min, 34min, 36min, 38min, 40min, 42min, 44min, 46min, 48min, or 50min, etc., but not limited to the listed values, other values not listed in this range are also required.

[0051] In the present application, the ammonium salt used in the ammonium salt vanadium precipitation is specifically selected according to conventional selection in the art, for example, ammonium sulfate, ammonium chloride, ammonium nitrate, etc.

[0052] The dehydration includes: dehydrating at 100-120℃ for ≥1h, the dehydration temperature can be 100℃, 105℃, 110℃, 115℃, or 120℃, etc., and the dehydration time can be 1h, 1.5h, 2h, 2.5h, or 3h, etc., but not limited to the listed values, other values not listed in this range are also required.

[0053] The calcination and deamination includes: calcining at a temperature of 580-620℃ for ≥1h, the temperature can be 580℃, 585℃, 590℃, 595℃, 600℃, 605℃, 610℃, 615℃, or 620℃, etc., and the time can be 1h, 1.5h, 2h, 2.5h, or 3h, etc., but not limited to the listed values, other values not listed in this range are also required.

[0054] The melting includes: treating at a temperature of 850-900℃ for ≥0.5h, for example, the temperature can be 850℃, 855℃, 860℃, 865℃, 870℃, 875℃, 880℃, 885℃, 890℃, 895℃ or 900℃, and the time can be 0.5h, 1h, 1.5h, 2h, 2.5h or 3h, etc., but is not limited to the listed values, and other unlisted values in the range are also acceptable.

[0055] II. In order to illustrate the indexes that can be achieved by the vanadium product obtained by the preparation method of high-purity vanadium pentoxide provided by the present application, the following examples are used for illustration, as follows:

[0056] Example 1

[0057] The present example provides a preparation method of high-purity vanadium pentoxide, as follows:

[0058] A phosphorus-containing vanadium solution (the mass concentration of components is: V 25%, Na2O 24%, K2O 0.7%, P 10ppm, Si 300ppm, and the pH value is 8) is added with a decontaminating agent for decontamination, and then solid-liquid separation is performed to obtain a filtrate;

[0059] The obtained filtrate is sequentially subjected to first pH value adjustment, second pH value adjustment, ammonium salt vanadium precipitation, dehydration, calcination and deamination, and melting to obtain high-purity vanadium pentoxide;

[0060] The decontaminating agent includes: calcium salt and flocculating agent, the calcium salt is calcium chloride, the addition amount of the calcium salt is 1.4 times the molar amount of the precipitated phosphorus, and the flocculating agent is polyacrylamide (molecular weight is 10 million), and the addition amount of the flocculating agent is 4 ‰ of the mass of the phosphorus-containing vanadium solution;

[0061] The mass concentration of vanadium in the filtrate is 26g / L;

[0062] The end point pH value of the first pH value adjustment is 5, and the end point pH value of the second pH value adjustment is 2;

[0063] In the ammonium salt vanadium precipitation, the temperature of the solution when the ammonium salt is added is 60℃, the addition amount of the ammonium salt (ammonium sulfate) is 0.9 times the mass of total vanadium in the solution, the vanadium precipitation temperature is 95℃, and the time is 40min;

[0064] The dehydration is performed at 110℃ for 1h;

[0065] The calcination and deamination are performed at a temperature of 600℃ for 1h;

[0066] The melting is performed at a temperature of 880℃ for 0.5h.

[0067] Example 2

[0068] The embodiment provides a preparation method of high-purity vanadium pentoxide, and specifically as follows.

[0069] The impurity removing agent is added into the phosphorus-containing vanadium solution (the mass concentration of components is as follows: V 24%, Na2O 25%, K2O 0.8%, P 11 ppm, Si 350 ppm, and the pH value is 9) to remove impurities, and then solid-liquid separation is performed to obtain a filtrate;

[0070] The obtained filtrate is sequentially subjected to first pH value adjustment, second pH value adjustment, ammonium salt vanadium precipitation, dehydration, calcination and ammonia removal, and melting to obtain high-purity vanadium pentoxide.

[0071] The impurity removing agent comprises calcium salt and flocculating agent, the calcium salt is calcium nitrate, the adding amount of the calcium salt is 1.3 times of the molar amount of precipitated phosphorus, and the flocculating agent is sodium polyacrylate (the molecular weight is 6 million), and the adding amount of the flocculating agent is 4.5 ‰ of the mass of the phosphorus-containing vanadium solution.

[0072] The mass concentration of vanadium in the filtrate is 25 g / L.

[0073] The end point pH value of the first pH value adjustment is 5.2, and the end point pH value of the second pH value adjustment is 1.9.

[0074] In the ammonium salt vanadium precipitation, the temperature of the solution when the ammonium salt is added is 65 ℃, the adding amount of the ammonium salt (ammonium sulfate) is 0.95 times of the mass of total vanadium in the solution, the vanadium precipitation temperature is 98 ℃, and the time is 42 min.

[0075] The dehydration is performed at 115 ℃ for 1 h.

[0076] The calcination and ammonia removal are performed at 610 ℃ for 1 h.

[0077] The melting is performed at 860 ℃ for 0.5 h.

[0078] Embodiment 3

[0079] The embodiment provides a preparation method of high-purity vanadium pentoxide, and specifically as follows.

[0080] The impurity removing agent is added into the phosphorus-containing vanadium solution (the mass concentration of components is as follows: V 22%, Na2O 26%, K2O 0.6%, P 12 ppm, Si 400 ppm, and the pH value is 10) to remove impurities, and then solid-liquid separation is performed to obtain a filtrate.

[0081] The obtained filtrate is sequentially subjected to first pH value adjustment, second pH value adjustment, ammonium salt vanadium precipitation, dehydration, calcination and ammonia removal, and melting to obtain high-purity vanadium pentoxide.

[0082] The impurity removing agent includes calcium salt and flocculant, the calcium salt is calcium nitrate, the adding amount of the calcium salt is 1.2 times of the molar amount of the theoretical precipitated phosphorus, the flocculant is polymeric ferric sulfate (polymerization degree is 20), and the adding amount of the flocculant is 5‰ of the mass of the vanadium solution containing phosphorus;

[0083] The mass concentration of vanadium in the filtrate is 28 g / L;

[0084] The end point pH value of the first pH value adjustment is 5.5, and the end point pH value of the second pH value adjustment is 1.8;

[0085] In the ammonium salt vanadium precipitation, the temperature of the solution when the ammonium salt is added is 70 ℃, the adding amount of the ammonium salt (ammonium sulfate) is 0.8 times of the mass of total vanadium in the solution, the vanadium precipitation temperature is 100 ℃, and the time is 30 min;

[0086] The dehydration is carried out at 120 ℃ for 1 h;

[0087] The calcination and ammonia removal is carried out at 620 ℃ for 1 h;

[0088] The melting is carried out at 900 ℃ for 0.5 h.

[0089] Example 4

[0090] The embodiment provides a preparation method of high-purity vanadium pentoxide, and specifically as follows:

[0091] An impurity removing agent is added into a vanadium solution containing phosphorus (the mass concentration of components is as follows: V 26%, Na2O 22%, K2O 0.9%, P 8 ppm, Si 200 ppm, and the pH value is 11) to remove impurities, and then solid-liquid separation is carried out to obtain a filtrate;

[0092] The obtained filtrate is sequentially subjected to first pH value adjustment, second pH value adjustment, ammonium salt vanadium precipitation, dehydration, calcination and ammonia removal and melting to obtain high-purity vanadium pentoxide.

[0093] The impurity removing agent includes calcium salt and flocculant, the calcium salt is calcium nitrate, the adding amount of the calcium salt is 1.2 times of the molar amount of the theoretical precipitated phosphorus, the flocculant is polymeric ferric sulfate (polymerization degree is 20), and the adding amount of the flocculant is 5‰ of the mass of the vanadium solution containing phosphorus;

[0094] The mass concentration of vanadium in the filtrate is 24 g / L;

[0095] The end point pH value of the first pH value adjustment is 4.5, and the end point pH value of the second pH value adjustment is 2.2;

[0096] In the ammonium salt vanadium precipitation, the temperature of the solution when the ammonium salt is added is 70 ℃, the adding amount of the ammonium salt (ammonium sulfate) is 0.8 times of the mass of total vanadium in the solution, the vanadium precipitation temperature is 100 ℃, and the time is 30 min;

[0097] the dehydration is at 100°C for 1.5h;

[0098] the calcination is at 580°C for 2h;

[0099] the melting is at 850°C for 1h.

[0100] Comparative Example 1

[0101] The difference from Example 1 is only that no flocculant is added.

[0102] Comparative Example 2

[0103] The difference from Example 1 is only that the end pH value of the first pH adjustment is 6.

[0104] Comparative Example 3

[0105] The difference from Example 1 is only that the end pH value of the first pH adjustment is 3.

[0106] Comparative Example 4

[0107] The difference from Example 1 is only that the end pH value of the second pH adjustment is 2.5.

[0108] Comparative Example 5

[0109] The difference from Example 1 is only that the end pH value of the second pH adjustment is 1.5.

[0110] Example 5

[0111] The difference from Example 1 is only that the amount of flocculant added is 2% of the mass of the vanadium-containing phosphorus solution.

[0112] Example 6

[0113] The difference from Example 1 is only that the amount of flocculant added is 6% of the mass of the vanadium-containing phosphorus solution.

[0114] Example 7

[0115] The difference from Example 1 is only that the temperature of the solution when the ammonium salt is added in the ammonium salt vanadium precipitation is 40°C.

[0116] Example 8

[0117] The difference from Example 1 is only that the temperature of the solution when the ammonium salt is added in the ammonium salt vanadium precipitation is 80°C.

[0118] Table 1

[0119]

[0120]

[0121] From Table 1, we can see that:

[0122] I. Examples (1-4): High-efficiency purification effect under optimized process

[0123] Examples 1-4 strictly follow the core process conditions of the application (impurity removal agent combination, pH adjustment range, vanadium precipitation parameters, etc.), and the results show that:

[0124] Purity: All reached ≥99.9%, among which Example 4 had the highest purity (99.98%), followed by Example 2 (99.96%), both meeting the definition of "high purity" (purity ≥99.9%).

[0125] Recovery rate: All remained above 98%, with Example 3 having the highest recovery rate (98.8%), and Examples 1, 2, and 4 having recovery rates of 98.5%, 98.4%, and 98.6% respectively, achieving efficient recovery of vanadium.

[0126] In the impurity removal stage, calcium salt (calcium chloride / calcium nitrate) + polyacrylamide composite impurity removal was used, with calcium salt added at 1.2-1.5 times the theoretical amount to effectively precipitate phosphorus impurities; flocculant was added at 3-5‰ to strengthen the settlement separation of colloidal impurities (iron, aluminum, silicon, etc.).

[0127] The pH adjustment was strictly controlled at a first pH value of 4.5-5.5 and a second pH value of 1.8-2.2 to avoid loss of vanadium ions due to hydrolysis and to inhibit the dissolution of impurities.

[0128] The ammonium salt vanadium precipitation parameters (temperature 50-70℃ for adding ammonium salt, 90-100℃ for vanadium precipitation, time 30-50min) optimized the crystallization efficiency of ammonium polyvanadate, reducing vanadium loss.

[0129] II. Comparative Example (1-5): Performance decline due to deviation from key process

[0130] By changing the core process parameters, the comparative example showed that both purity and recovery rate were significantly reduced (purity ≤97.45%, recovery rate ≤86.9%), with the specific reasons as follows:

[0131] Comparative Example 1 (without adding flocculant): purity was only 95.33% and recovery rate was 85.3%.

[0132] After missing the flocculant, colloidal impurities (such as Fe(OH)3, Al(OH)3 colloids) in the vanadium solution could not be effectively aggregated and settled, and the solid-liquid separation was not complete, resulting in impurity residues and causing purity to decrease, while colloidal adsorption of vanadium ions caused recovery rate to decrease.

[0133] Comparative Example 2 (first pH value is 6), Comparative Example 3 (first pH value is 3): the purity is 96.35%, 97.45% respectively, and the recovery rate is 86.7%, 85.1% respectively; the first pH value deviates from the range of 4.5-5.5: if the pH value is too high (pH value = 6), vanadium ion hydrolysis precipitation loss will be caused; if the pH value is too low (pH value = 3), part of impurities (such as aluminum ion) cannot be effectively precipitated, the residual amount of impurities increases, and the quality of the final product is affected.

[0134] Comparative Example 4 (second pH value is 2.5), Comparative Example 5 (second pH value is 1.5): the purity is 96.32%, 95.36% respectively, and the recovery rate is 84.5%, 86.9% respectively; the second pH value deviates from the range of 1.8-2.2: if the pH value is too high (pH value = 2.5), vanadium precipitation will not be complete, and vanadium will remain in the solution; if the pH value is too low (pH value = 1.5), excessive acid impurities will be introduced, and equipment corrosion will be aggravated, which indirectly affects the purity.

[0135] III. Examples (5-8): Influence of Non-core Parameter Fine-tuning

[0136] Examples 5-8 fine-tune non-key parameters within the core process framework, and the results show that the purity and recovery rate decrease slightly (purity 95.44%-98.72%, recovery rate 88.4%-89.5%), but are still better than those of the comparative examples, as follows:

[0137] Example 5 (flocculant addition amount is 2‰), Example 6 (flocculant addition amount is 6‰): the purity is 98.61%, 98.72% respectively, and the recovery rate is 89.5%, 88.4% respectively; the flocculant addition amount deviates from the range of 3-5‰: if the amount is insufficient (2‰), colloidal coagulation will not be complete; if the amount is excessive (6‰), foam will be easily produced, the solution viscosity will be increased, and the solid-liquid separation efficiency will be affected, and in both cases, the residual amount of impurities will increase slightly.

[0138] Example 7 (ammonium salt addition temperature is 40℃), Example 8 (ammonium salt addition temperature is 80℃): the purity is 95.44%, 98.35% respectively, and the recovery rate is 89.3%, 88.9% respectively; the ammonium salt addition temperature deviates from the range of 50-70℃: if the temperature is too low (40℃), the ammonium salt will not be completely dissolved, and the vanadium precipitation reaction will not be complete; if the temperature is too high (80℃), the ammonium salt will be decomposed, the vanadium precipitation efficiency will be reduced, and in both cases, the vanadium recovery rate will decrease.

[0139] IV. Conclusion

[0140] The data in Table 1 fully verifies the scientificity of the process parameters of the present application:

[0141] The flocculant is the key to impurity removal: the amount of polyacrylamide is 3-5‰, otherwise colloidal impurities cannot be effectively removed.

[0142] Control of pH value is the core: precise control of the first pH value of 4.5-5.5 and the second pH value of 1.8-2.2 is the prerequisite to ensure purity and recovery rate.

[0143] Parameter synergy: the combination of impurity removal agent, pH adjustment, vanadium precipitation temperature and other parameters need to be optimized synergistically, and any deviation of key parameters will significantly reduce product quality.

[0144] The above describes the preferred embodiments of the present application, but the present application is not limited to the specific details in the above-described embodiments, and various simple modifications can be made to the technical solutions of the present application within the technical concept of the present application, and these simple modifications all belong to the protection scope of the present application.

[0145] In addition, it should be noted that various specific technical features described in the above specific embodiments can be combined in any appropriate manner without contradiction, and in order to avoid unnecessary repetition, the present application will not further describe various possible combinations.

[0146] In addition, various different embodiments of the present application can also be combined in any manner, as long as it does not deviate from the idea of the present application, and it should also be considered as disclosed by the present application.

Claims

1. A method for preparing high-purity vanadium pentoxide, characterized in that, The preparation method includes: A purifying agent was added to the phosphorus-vanadium solution to remove impurities, followed by solid-liquid separation to obtain the filtrate; The obtained filtrate was subjected to a first pH adjustment, a second pH adjustment, ammonium salt precipitation of vanadium, dehydration, calcination to remove ammonia, and melting in sequence to obtain high-purity vanadium pentoxide; The impurity removal agent includes calcium salt and flocculant; the endpoint pH value of the first pH adjustment is 4.5-5.5; and the endpoint pH value of the second pH adjustment is 1.8-2.

2.

2. The preparation method according to claim 1, characterized in that, The calcium salts include: calcium chloride and / or calcium nitrate.

3. The preparation method according to claim 1, characterized in that, The amount of calcium salt added is 1.2-1.5 times the theoretical molar amount of precipitated phosphorus.

4. The preparation method according to claim 1, characterized in that, The flocculant includes one or a combination of at least two of the following: polyacrylamide, sodium polyacrylate, or polyferric sulfate.

5. The preparation method according to claim 1, characterized in that, The amount of flocculant added is 3-5‰ of the mass of the vanadium-phosphorus solution.

6. The preparation method according to claim 1, characterized in that, The vanadium concentration in the filtrate is 24-28 g / L.

7. The preparation method according to any one of claims 1-6, characterized in that, The temperature of the solution when adding ammonium salt to the ammonium salt vanadium precipitation process is 50-70℃; Preferably, the amount of ammonium salt added in the ammonium salt precipitation is 0.8-1 times the total mass of vanadium in the solution; Preferably, the precipitation temperature of the ammonium salt vanadium is 90-100℃; Preferably, the ammonium salt precipitation time is 30-50 minutes.

8. The preparation method according to claim 1, characterized in that, The dehydration includes dehydration at 100-120℃ for ≥1 hour.

9. The preparation method according to claim 1, characterized in that, The calcination deammoniation process includes calcination at a temperature of 580-620℃ for ≥1 hour.

10. The preparation method according to claim 1, characterized in that, The melting process includes: processing at a temperature of 850-900℃ for ≥0.5h.

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