A method for preparing vanadium pentoxide by using a vanadium liquid containing silicon and chromium

Abstract

This invention provides a method for preparing vanadium pentoxide using sodium vanadium tin oxide containing silicon chromium, comprising the following steps: S1, adjusting the pH of the vanadium solution, then adding a silicon remover, and after settling and filtration, obtaining a silicon-removed liquid and silicon-removed slag; S2, successively adjusting the temperature and pH of the silicon-removed liquid, then adding ammonium salt to obtain a primary reaction system for a primary reaction, and after filtration, obtaining SAV and a primary filtrate; S3, dissolving SAV by heat, adding ammonium salt to obtain a first-secondary reaction system for a first-secondary reaction, cooling and crystallizing, and after filtration, obtaining AMV and a first-secondary filtrate; or, dissolving SAV by acid, adding ammonium salt to obtain a second-secondary reaction system for a second-secondary reaction, and after filtration, obtaining a first APV and a second-secondary filtrate; S4, calcining AMV or the first APV to obtain vanadium pentoxide. The method of this invention features high vanadium yield, low Si, Na, and Cr content in vanadium pentoxide, stable quality, low vanadium loss, and low ammonium loss.

Description

Technical Field

[0001] This invention belongs to the field of vanadium pentoxide preparation, specifically relating to a method for preparing vanadium pentoxide using a sodium vanadium pentoxide solution containing silicon chromium. Background Technology

[0002] Vanadium is a very rare metallic element, mainly used in the steel industry to improve the strength and toughness of steel products. Vanadium also has wide applications in the chemical, energy storage, and pharmaceutical fields, giving it high economic value. Currently, the mainstream vanadium extraction process from vanadium slag involves sodium roasting and water leaching of the vanadium slag, followed by acidic ammonium salt precipitation of the sodium vanadium solution. Since some vanadium slag contains chromium, this chromium enters the sodium vanadium solution during sodium roasting and water leaching. Furthermore, the high pH of the leaching solution results in a high Si content in the sodium vanadium solution. The sodium salt addition ratio during sodium roasting is generally >20%, and the Na / V (mass ratio) in the sodium vanadium leachate is approximately 1. If traditional acidic ammonium salt precipitation of vanadium from sodium vanadium solution is used, the vanadium product will have high Si, Cr, and Na content, with V₂O₅ concentrated at 98%–99%. To obtain higher quality vanadium oxide products, Si, Cr, and Na need to be removed from the vanadium solution / vanadium intermediate to improve the quality of the vanadium oxide product.

[0003] Patent application CN116177601A, entitled "A Method for Preparing High-Purity Vanadium Pentoxide from Ammonium Polyvanadate," uses industrial ammonium polyvanadate as raw material. It employs a two-stage dissolution process—low-temperature controlled chromium dissolution and high-temperature vanadium dissolution—to effectively control impurities such as chromium, arsenic, and iron in the ammonium polyvanadate raw material. However, this method suffers from high vanadium loss during low-temperature controlled chromium dissolution, and the high-temperature vanadium dissolution requires the addition of reagents to dissolve the ammonium polyvanadate, resulting in a large amount of vanadium-containing wastewater.

[0004] Patent application CN114394619A discloses a method for preparing low-silicon sodium polyvanadate (SAV) through reduction precipitation and desilication. The method includes: providing a vanadium-containing solution; adding acid to the vanadium-containing solution to adjust the pH to 6-9, adding a reducing agent to carry out a reduction reaction, obtaining a reduced vanadium solution; adjusting the pH of the reduced vanadium solution to 4-6, adding ammonium salt to react for 0.5-3 hours; after the reaction is complete, filtering to obtain a vanadium-precipitated filter cake; washing the filter cake with deionized water; and then drying. This method requires the addition of a reducing agent, and the pH range for SAV precipitation is relatively narrow, resulting in significant vanadium loss during precipitation.

[0005] Furthermore, none of the above methods simultaneously remove sodium, silicon, and chromium. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a method for preparing vanadium pentoxide using a sodium vanadium vanadium hydroxide solution containing silicon chromium.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] This invention provides a method for preparing vanadium pentoxide using a sodium vanadium vanadium hydroxide solution containing silicon chromium, comprising the following steps:

[0009] S1, adjust the pH value of the vanadium solution, then add the desiliconizing agent, and after settling and filtration, obtain the desiliconized liquid and desiliconized slag;

[0010] S2, the temperature and pH of the desiliconized liquid were adjusted successively, and then ammonium salt was added to obtain a primary reaction system for primary reaction. After filtration, SAV and primary filtrate were obtained.

[0011] S3, after hot melting of SAV, adds ammonium salt to obtain a first- and second-order reaction system for the first- and second-order reaction, cools and crystallizes, and then filters to obtain AMV and the first- and second-order filtrate; or,

[0012] After acid dissolution of SAV, ammonium salt is added to obtain a second-secondary reaction system for the second-secondary reaction. After filtration, the first APV and the second-secondary filtrate are obtained.

[0013] S4, calcining AMV or the first APV to obtain vanadium pentoxide.

[0014] Further, in step S1,

[0015] The silicon removal temperature is 20℃~80℃, the pH value of the vanadium solution is adjusted to 9.8~10.5, the silicon removal agent is aluminum sulfate, the molar ratio of Si to Al is 0.8~1.2, the silicon removal stirring time is 20min~60min, and the standing time is ≥48h.

[0016] Furthermore, step S1 also includes the following steps:

[0017] The silicon slag is washed once with fresh production water. The amount of fresh production water used for washing is 1 / 20 of the amount of vanadium solution before silicon removal. The washing filtrate is then added to the solution after silicon removal.

[0018] Further, in step S2, the first-order reaction includes the following steps:

[0019] S2.1 Take a certain volume of the desiliconized solution, adjust the temperature of the solution to 10℃~50℃, and then adjust the pH value to 0~3.0. The ammonium salt is ammonium sulfate, and the amount of ammonium sulfate added is NH4. + The mass ratio of TV to water is 1.2 to 2, and the reaction time is 5 min to 30 min.

[0020] S2.2, Add the same volume of the desiliconized liquid to step S2.1, the total NH4+ +The mass ratio of TV to the total TV is 0.6 to 1.2, the pH value is adjusted to 5.0 to 9.0, and the reaction time is 30 min to 60 min;

[0021] S2.3, after the reaction is complete and filtered, SAV and primary filtrate are obtained.

[0022] Further, in step S2.2,

[0023] If the Cr content in the vanadium solution is greater than 5 g / L, then ammonia should be added to adjust the pH to 9.5–11.

[0024] Furthermore, it also includes the following steps:

[0025] SAV is washed once with fresh production water at a temperature of 10℃~35℃. The volume of fresh production water used for washing is the same as that used for SAV, and the washing water is added to the primary filtrate.

[0026] Furthermore, step S3 also includes the following steps:

[0027] S3.1.1, the hot dissolution temperature of SAV is 80℃~95℃, and the amount of hot dissolution water of SAV is controlled so that the content of TV after all SAV is dissolved is 25g / L~35g / L;

[0028] S3.2.1 When SAV is completely dissolved, the temperature is lowered to ≤70℃, and then ammonium sulfate is added, with the mass ratio of ammonium sulfate to SAV being 0.5 to 0.8.

[0029] S3.3.1 After the reaction is complete, cool down to crystallize. The crystallization temperature is 20℃~50℃ and the crystallization time is 90min~240min.

[0030] S3.4.1 After crystallization, filter to obtain AMV and first and second stage filtrates.

[0031] Furthermore, it also includes the following steps:

[0032] AMV is washed once with fresh production water at a temperature of 10℃~35℃. The volume of fresh production water used for washing is the same as that of AMV, and the washing water is added to the first and second stage filtrates.

[0033] The first and second stage filtrates can be recycled and hot-dissolved SAV 4-8 times.

[0034] Furthermore, step S3 also includes the following steps:

[0035] S3.1.2, the pH value of SAV acid solubility is 1.8 to 2.5, and the amount of SAV acid solubility water is controlled so that the TV content is 25g / L to 80g / L after all SAV is dissolved;

[0036] S3.2.2, When SAV is completely dissolved, add ammonium sulfate, wherein the amount of ammonium sulfate added is:

[0037] If the vanadium content is ≤40g / L, the mass ratio of ammonium sulfate to TV is 0.

[0038] If vanadium content is 40 g / L < 60 g / L, the mass ratio of ammonium sulfate to TV is 0.2–0.5.

[0039] If the vanadium content is 60g / L to 80g / L, the mass ratio of ammonium sulfate to TV is 0.5 to 1.0;

[0040] S3.3.2 After adding the ammonium salt, raise the temperature to react. The reaction temperature is 80℃~95℃ and the reaction time is 60min~90min.

[0041] S3.4.2 After the reaction is complete, filter to obtain the first APV and the second secondary filtrate.

[0042] Furthermore, it also includes the following steps:

[0043] The first APV is washed once with fresh production water at a temperature of 80℃~95℃. The pH value of the fresh production water is 1.5~7.0. The volume of fresh production water used for washing is the same as that used for the first APV. The washing water is then added to the second and third stage filtrates.

[0044] The second and third stage filtrates can be recycled to acid dissolve SAV 2-3 times.

[0045] Further, in step S4,

[0046] The calcination temperature is 500℃~600℃, the calcination time is 120min~240min, and the oxygen content in the calcination atmosphere is >15%.

[0047] Furthermore, it also includes the step of precipitating APV by preparing vanadium solution of equal volume using primary filtrate, first-secondary filtrate, or second-secondary filtrate, respectively.

[0048] The first-stage filtrate is mixed with an equal volume of vanadium solution, the pH value is adjusted to 1.8-2.5, the precipitation temperature is 80℃-95℃, and the precipitation time is 60min-120min to obtain the second APV and the first and third-stage filtrates.

[0049] The first and second stage filtrates from a series of cyclic hot-dissolving SAVs are mixed with an equal volume of vanadium solution. The pH is adjusted to 1.8–2.5, the precipitation temperature is set at 80℃–95℃, and the precipitation time is set at 60 min–120 min to obtain the third APV and the second and third stage filtrates; or

[0050] The second and second stage filtrates of the SAV were cyclically acid-dissolved a certain number of times, and the same volume of vanadium solution was prepared. The pH value was adjusted to 1.8-2.5, the precipitation temperature was 80℃-95℃, and the precipitation time was 60min-120min to obtain the fourth APV and the third and third stage filtrates.

[0051] The obtained second, third, and fourth APVs were calcined to obtain vanadium pentoxide.

[0052] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0053] The method of this invention utilizes a desiliconizing agent to remove silicon from vanadium pentoxide solution. After desiliconization, the solution undergoes a two-stage reaction, increasing the vanadium precipitation rate of SAV and reducing the Cr content in SAV. After thermal dissolution of SAV, AMV precipitates, reducing the sodium content in the vanadium product. The primary and secondary filtrates are mixed with equal volumes of acidic ammonium salts from the vanadium solution for vanadium precipitation, reducing vanadium and ammonium losses. The SAV acid dissolution to APV conversion process has low energy consumption and low ammonium consumption. The method of this invention features high vanadium yield, low Si, Na, and Cr content in vanadium pentoxide, stable quality, low vanadium loss, and low ammonium loss. Furthermore, the method of this invention is simple to operate and requires minimal fixed investment. Attached Figure Description

[0054] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0055] Figure 1 This is a schematic flowchart of the method for preparing vanadium pentoxide using sodium vanadium tincture containing silicon chromium according to the present invention.

[0056] Figure 2 This is another schematic diagram of the method for preparing vanadium pentoxide using sodium vanadium tincture containing silicon chromium according to the present invention. Detailed Implementation

[0057] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be further described in detail below with reference to specific examples and the accompanying drawings.

[0058] like Figure 1 As shown, the present invention provides a method for preparing vanadium pentoxide using a sodium vanadium vanadium hydroxide solution containing silicon chromium, comprising the following steps:

[0059] S1, adjust the pH value of the vanadium solution, then add the desiliconizing agent, and after settling and filtration, obtain the desiliconized liquid and desiliconized slag.

[0060] S2, the temperature and pH of the desiliconized liquid were adjusted successively, and then ammonium salt was added to obtain a primary reaction system for primary reaction. After filtration, SAV and primary filtrate were obtained.

[0061] S3, after hot melting of SAV, ammonium salt is added to obtain a first and second stage reaction system for the first and second stage reaction. After cooling and crystallization, and filtration, AMV and the first and second stage filtrates are obtained; or

[0062] After dissolving SAV in acid, ammonium salt is added to obtain a second-secondary reaction system for the second-secondary reaction. After filtration, the first APV and the second-secondary filtrate are obtained.

[0063] S4, calcining AMV or the first APV to obtain vanadium pentoxide.

[0064] In one embodiment of the present invention, in step S1, the desiliconization temperature is 20℃~80℃, and the pH value of the vanadium solution is adjusted to 9.8~10.5 before adding the desiliconizing agent. The desiliconizing agent is aluminum sulfate, and the amount added is 0.8~1.2 molar ratio of Si to Al. The desiliconization stirring time is 20min~60min. Then, the desiliconized slurry is allowed to stand for ≥48h and then filtered to obtain the desiliconized liquid and desiliconized slag.

[0065] In one embodiment of the present invention, step S1 further includes the following steps: washing the silicon slag once with fresh production water, wherein the amount of fresh production water used for washing is 1 / 20 of the vanadium solution before silicon removal, and the washing filtrate is incorporated into the solution after silicon removal.

[0066] In one embodiment of the present invention, in step S2, the first-order reaction includes the following steps:

[0067] S2.1, Take a certain volume of the desiliconized solution. Before adjusting the pH, adjust the temperature of the desiliconized solution to 10℃~50℃, and then adjust the pH to 0~3.0. The ammonium salt is ammonium sulfate, and the amount of ammonium sulfate added is NH4. + The mass ratio of TV to water is 1.2 to 2, and the reaction time is 5 min to 30 min.

[0068] S2.2, After the reaction in step S2.1, add the same volume of the desiliconized liquid (i.e., the same volume as the desiliconized liquid taken in step S2.1) to step S2.1, wherein the total NH4+... + The mass ratio of TV to water is 0.6 to 1.2, the pH value is adjusted to 5.0 to 9.0, and the reaction time is 30 min to 60 min.

[0069] S2.3, after the reaction is complete and filtered, SAV and primary filtrate are obtained.

[0070] In one embodiment of the present invention, in step S2.2, if the Cr in the vanadium solution is greater than 5 g / L, ammonia can be added to adjust the pH value to 9.5-11.

[0071] In one embodiment of the present invention, the following steps are also included: the SAV is washed once with fresh production water at a temperature of 10°C to 35°C, the volume of fresh production water used for washing is the same as that of the SAV, and the wash water is incorporated into the primary filtrate.

[0072] This invention utilizes sodium vanadium precipitate containing silicon chromium as the raw material for vanadium precipitation. In one embodiment of this invention, the composition and content of the vanadium precipitate are shown in Table 1.

[0073] Table 1. Composition and content of sodium vanadium chromium silicate solution

[0074]

[0075] The method of the present invention first adjusts the pH of the vanadium solution and then adds a desiliconizing agent to remove silicon, obtaining a desiliconized solution with Si < 0.01 g / L, thereby ensuring that the Si content in the vanadium product is < 0.03%. Then, a certain volume of the desiliconized solution is taken, and the pH is adjusted at a certain temperature (e.g., 10℃~50℃) (e.g., pH = 0~3.0), and an ammonium salt is added, reacting for a certain time. Afterwards, the same volume of the desiliconized solution is added again, and the pH is adjusted (e.g., pH = 5.0~9.0) to continue the reaction. Furthermore, depending on the Cr content in the vanadium solution, a portion of ammonia solution can be selectively added to adjust the pH (e.g., pH = 9.5~11).

[0076] The purpose of the above steps is to: (1) obtain SAV to avoid Cr entering the vanadium product; (2) if SAV is precipitated and filtered at around pH=4.0 according to conventional operation, impurities such as hydrolyzed vanadium may enter the SAV, affecting the vanadium product, and under higher pH conditions, the Cr in the SAV can be further reduced; (3) within the pH range of 4.0 to 5.0, the SAV precipitation reaction will occur rapidly, otherwise the SAV precipitation reaction will not occur. However, in actual operation, due to the large amount of reactants in the actual large-scale production process, when concentrated sulfuric acid is added to adjust the pH of the reactants, combined with the objective situation that the pH range of 4.0 to 5.0 is too narrow, the measured pH value will not match the actual pH value of the reactants. For example, the measured pH is in the range of 4.0 to 5.0, but the actual pH of the reactants may be less than 4.0. Therefore, it is difficult to accurately place the SAV precipitation reaction within the pH range of 4.0 to 5.0, and it is impossible to stably obtain SAV precipitation. This invention first adjusts the ammonium-containing reaction system to a low pH (pH = 0–3.0). Then, under this low pH condition, the desiliconized solution is added dropwise to adjust the ammonium-containing reaction system to a high pH (pH = 5.0–9.0). The transition from low to high pH inevitably passes through the pH range of 4.0–5.0, thus ensuring that SAV precipitation occurs rapidly and stably within this range. Furthermore, once SAV precipitate is formed, it will not dissolve at pH levels higher than 4.0–5.0 (SAV has low solubility above 4 and high solubility below 4), thereby reducing the impact of pH fluctuations (where SAV has high solubility) on the vanadium (SAV) precipitation rate under acidic conditions.

[0077] In one embodiment of the present invention, step S3 further includes the following step:

[0078] S3.1.1, the hot dissolution temperature of SAV is 80℃~95℃, and the amount of hot dissolution water for SAV is controlled so that the content of TV after all SAV is dissolved is 25g / L~35g / L.

[0079] S3.2.1 After SAV is completely dissolved, start cooling down to ≤70℃, and then add ammonium sulfate. The mass ratio of ammonium sulfate to SAV is 0.5 to 0.8.

[0080] S3.3.1 After the reaction is complete, cool down to crystallize AMV. The crystallization temperature is 20℃~50℃ and the crystallization time is 90min~240min.

[0081] S3.4.1 After crystallization, filter to obtain AMV and first and second stage filtrates.

[0082] In one embodiment of the present invention, the method further includes the following steps: AMV is washed once with fresh production water at a temperature of 10°C to 35°C, the volume of fresh production water used for washing is the same as the volume of AMV, and the wash water is incorporated into the first and second stage filtrates. In one embodiment of the present invention, the first and second stage filtrates can be recycled for hot dissolution of SAV 4 to 8 times. The high number of recycling cycles of the first and second stage filtrates during the hot dissolution conversion of SAV to AMV results in less wastewater.

[0083] In one embodiment of the present invention, step S3 further includes the following step:

[0084] S3.1.2, the pH value of SAV acid solubility is 1.8 to 2.5, and the amount of SAV acid solubility water is controlled so that the TV content is 25g / L to 80g / L after all SAV is dissolved;

[0085] S3.2.2, When SAV is completely dissolved, add ammonium sulfate, wherein the amount of ammonium sulfate added is:

[0086] If the vanadium content is ≤40g / L, the mass ratio of ammonium sulfate to TV is 0.

[0087] If vanadium content is 40 g / L < 60 g / L, the mass ratio of ammonium sulfate to TV is 0.2–0.5.

[0088] If the vanadium content is 60g / L to 80g / L, the mass ratio of ammonium sulfate to TV is 0.5 to 1.0;

[0089] S3.3.2 After adding the ammonium salt, raise the temperature to react. The reaction temperature is 80℃~95℃ and the reaction time is 60min~90min.

[0090] S3.4.2 After the reaction is complete, filter to obtain the first APV and the second secondary filtrate.

[0091] In one embodiment of the present invention, the following steps are also included:

[0092] The first APV is washed once with fresh production water at a temperature of 80℃~95℃. The pH value of the fresh production water is 1.5~7.0, and the volume of fresh production water used for washing is the same as that used for the first APV. This wash water is then incorporated into the second-stage filtrate. In one embodiment of the present invention, the second-stage filtrate can be circulated for acid dissolution of SAV 2-3 times.

[0093] In one embodiment of the present invention, in step S4, the calcination temperature is 500℃~600℃, the calcination time is 120min~240min, and the oxygen content in the calcination atmosphere is >15%.

[0094] In one embodiment of the present invention, the method further includes the step of precipitating APV using equal volumes of primary filtrate, first secondary filtrate, and second secondary filtrate. The primary filtrate is mixed with equal volumes of vanadium solution, the pH is adjusted to 1.8–2.5, the precipitation temperature is 80°C–95°C, and the precipitation time is 60–120 min to obtain second APV and first tertiary filtrate. The first and second secondary filtrates of SAV are cyclically hot-dissolved a certain number of times, mixed with equal volumes of vanadium solution, the pH is adjusted to 1.8–2.5, the precipitation temperature is 80°C–95°C, and the precipitation time is 60–120 min to obtain third APV and second and third tertiary filtrates. The second and second secondary filtrates of SAV are cyclically acid-dissolved a certain number of times, mixed with equal volumes of vanadium solution, the pH is adjusted to 1.8–2.5, the precipitation temperature is 80°C–95°C, and the precipitation time is 60–120 min to obtain fourth APV and third tertiary filtrate. The second, third, and fourth APVs obtained above were calcined to obtain vanadium pentoxide.

[0095] Mixing the primary filtrate with an equal volume of vanadium solution reduces the concentrations of vanadium (V) and sodium (Na) in the mixture, improving the quality of the second precipitated vanadium pentoxide (APV). Simultaneously, excess ammonium in the primary filtrate reduces vanadium loss. Dissolving SAV in hot water followed by adding ammonium salt and cooling to crystallize AMV effectively reduces the Na content in the vanadium product. The resulting primary and secondary filtrates, after a certain number of SAV dissolution cycles, are then mixed with an equal volume of vanadium solution to precipitate the third APV, achieving the same effect as the primary filtrate. Adding ammonium salt after acid dissolution of SAV results in a low-energy, low-ammonium reaction. The resulting secondary and secondary filtrates, after a certain number of SAV dissolution cycles, are then mixed with an equal volume of vanadium solution to precipitate the fourth APV. Finally, the second, third, and fourth APVs obtained from the above steps can be calcined to yield a high-quality vanadium pentoxide product.

[0096] In one embodiment of the present invention, the acid-adjusting medium in the above steps is 50% (by volume) sulfuric acid.

[0097] The method of this invention involves adding a desiliconizing agent to a vanadium solution to obtain a desiliconized solution, reducing the silicon content in the vanadium solution to below 0.01 g / L. Then, taking advantage of the low solubility of SAV (sodium ammonium vanadate) in cold water and under weakly alkaline conditions, a certain volume of the desiliconized solution is taken, and sulfuric acid is added to adjust the pH value. Then, ammonium salt is added and reacted for a certain period. Afterward, the same volume of the desiliconized solution is added again, and ammonia water can be selectively used to adjust the pH value. After the reaction, the solution is filtered to obtain SAV and a primary filtrate. The primary filtrate is mixed with an equal volume of vanadium solution to precipitate a second APV. SAV is dissolved in hot water to precipitate AMV. The resulting first and second filtrates can be recycled to dissolve SAV. After a certain number of recycling cycles, the resulting first and second filtrates can be mixed with an equal volume of vanadium solution to precipitate a third APV. Alternatively, SAV is acid-dissolved to precipitate APV. The resulting second and second filtrates can be recycled to acid-dissolve SAV. After a certain number of recycling cycles, the resulting second and second filtrates can be mixed with an equal volume of vanadium solution to precipitate a fourth APV. After calcination, AMV yields a vanadium pentoxide product with V2O5 > 99.5%, Na < 0.03%, Si < 0.03%, and Cr < 0.05%.

[0098] The method for preparing vanadium pentoxide using sodium vanadium tincture containing silicon chromium according to the present invention will be described in detail below with reference to specific embodiments.

[0099] Example 1

[0100] Take 5000ml of vanadium solution with a vanadium concentration (TV) of 40g / L, Na / V (mass ratio) = 0.95, Si content of 1.5g / L, and Cr content of 3g / L.

[0101] S1. Adjust the temperature of the vanadium solution to 70℃, adjust the pH of the vanadium solution to 10.0 with 50% (v / v) sulfuric acid, then add 71.40g of Al2(SO4)3·18H2O, stir for 30 minutes, let stand for 48 hours, and then filter to obtain the desiliconized solution and desiliconized slag. Wash the desiliconized slag with 250ml of fresh production water, and add the wash water to the desiliconized solution to obtain 5000ml of desiliconized solution.

[0102] S2, after desiliconization, the pH of the solution is 9.5. Take 500 ml of the desiliconized solution, adjust the temperature to 30℃, adjust the pH to 0.0, add 24 g of ammonium sulfate, and react for 10 min. Then add another 500 ml of the desiliconized solution, adjust the pH to 5.0, and continue reacting for 60 min. Filter to obtain SAV and primary filtrate. Wash the SAV once with the same volume of fresh production water at 20℃, and add the wash water to the primary filtrate (V = 3 g / L).

[0103] S3: Dissolve 62.5g of SAV in 1000ml of fresh production water at 90℃. After dissolution, cool to 70℃, then add 31.25g of ammonium sulfate. After the reaction is complete, cool to 30℃ and crystallize for 180min. Filter to obtain AMV and the first and second stage filtrates. Wash AMV once with the same volume of fresh production water at 20℃, and add the wash water to the first and second stage filtrates (V = 5g / L).

[0104] S4 and AMV were calcined at 600℃ for 120 min in an oxygen atmosphere with a content of 16% to obtain vanadium pentoxide. The vanadium pentoxide contained 99.89% V2O5, 0.015% Na, 0.023% Si, and 0.022% Cr.

[0105] S5: The primary filtrate is mixed with 1000 ml of vanadium solution to obtain 2000 ml of mixed solution, with a V of 21.5 g / L. The pH is directly adjusted to 2.0, and the mixture is precipitated at 85℃ for 90 min. Filtration yields the second APV and the first and third stage filtrates. The first and third stage filtrates are then used for large-scale production. The first and second stage filtrates from four cycles of hot-melt SAV are mixed with 1000 ml of vanadium solution to obtain 2000 ml of mixed solution, with a V of 22.5 g / L. The pH is directly adjusted to 2.5, and the mixture is precipitated at 90℃ for 60 min. Filtration yields the third APV and the second and third stage filtrates. The second and third stage filtrates are then used for large-scale production. The second and third APVs are calcined at 550℃ for 180 min to obtain vanadium pentoxide.

[0106] Example 2

[0107] Take 5000ml of vanadium solution with a vanadium concentration (TV) of 40g / L, Na / V (mass ratio) = 0.95, Si content of 1.5g / L, and Cr content of 10g / L.

[0108] S1. Adjust the temperature of the vanadium solution to 20℃, adjust the pH of the vanadium solution to 9.8 with 50% (v / v) sulfuric acid, then add 107.10 g of Al2(SO4)3·18H2O, stir for 60 min, let stand for 48 h, and then filter to obtain the desiliconized liquid and desiliconized slag. Wash the desiliconized slag with 250 ml of fresh production water, and add the wash water to the desiliconized liquid to obtain 5000 ml of desiliconized liquid.

[0109] S2, after desiliconization, the pH of the solution is 9.3. Take 500 ml of the desiliconized solution, adjust the temperature to 10℃, adjust the pH to 3.0, add 48 g of ammonium sulfate, and react for 5 min. Then add another 500 ml of the desiliconized solution, adjust the pH to 9.5, and continue reacting for 30 min. Filter to obtain SAV and primary filtrate. Wash the SAV once with the same volume of fresh production water at 10℃, and add the wash water to the primary filtrate (V = 8 g / L).

[0110] S3: Dissolve 87.5g of SAV in 1000ml of fresh production water at 80℃. After dissolution, cool to 60℃, then add 70g of ammonium sulfate. After the reaction is complete, cool to 30℃, crystallize for 180min, and then filter to obtain AMV and the first and second stage filtrates. Wash AMV once with the same volume of fresh production water at 10℃, and add the wash water to the first and second stage filtrates (V = 5g / L).

[0111] S4 and AMV were calcined at 500℃ for 240 min in an oxygen atmosphere with a content of 16% to obtain vanadium pentoxide. The vanadium pentoxide contained 99.91% V2O5, 0.015% Na, 0.023% Si, and 0.020% Cr.

[0112] S5: The primary filtrate is mixed with 1000 ml of vanadium solution to obtain 2000 ml of mixed solution, with a V of 24.0 g / L. The pH is directly adjusted to 1.8, and the mixture is precipitated at 80℃ for 120 min. Filtration yields the second APV and the first and third stage filtrates. The first and third stage filtrates are then used for large-scale production. After eight cycles of hot dissolution of SAV, the first and second stage filtrates are mixed with 1000 ml of vanadium solution to obtain 2000 ml of mixed solution, with a V of 22.5 g / L. The pH is directly adjusted to 2.5, and the mixture is precipitated at 90℃ for 60 min. Filtration yields the third APV and the second and third stage filtrates. The second and third stage filtrates are then used for large-scale production. The second and third APVs are calcined at 600℃ for 120 min to obtain vanadium pentoxide.

[0113] Example 3

[0114] Vanadium pentoxide was prepared according to the method of Example 1. The difference between Example 3 and Example 1 is that the vanadium concentration TV is 30 g / L, the Na / V (mass ratio) is 1, the Si content is 0.8 g / L, and the Cr content is 1 g / L.

[0115] In step S1, 47.60g of Al2(SO4)3.18H2O is added.

[0116] In step S2, 18g of ammonium sulfate is added, and the wash water is added to the primary filtrate (V is 5g / L).

[0117] In step S3, 62.5g of SAV is dissolved by heat, 12.5g of ammonium sulfate is added, and the washing water is added to the first and second stage filtrates (V is 6g / L).

[0118] In step S4, vanadium pentoxide contains 99.88% V2O5, 0.023% Na, 0.024% Si, and 0.009% Cr.

[0119] In step S5, when the primary filtrate is mixed with 1000 ml of vanadium solution, V is 17.5 g / L. When the SAV is mixed with 1000 ml of vanadium solution, V is 18 g / L.

[0120] Example 4

[0121] Take 5000ml of vanadium solution with a vanadium concentration (TV) of 40g / L, Na / V (mass ratio) = 0.95, Si content of 1.5g / L, and Cr content of 3g / L.

[0122] S1. Adjust the temperature of the vanadium solution to 50℃, adjust the pH of the vanadium solution to 10.5 using 50% (v / v) sulfuric acid, then add 89.25g of Al2(SO4)3·18H2O, stir for 30 minutes, let stand for 48 hours, and then filter to obtain the desiliconized solution and desiliconized slag. Wash the desiliconized slag with 250ml of fresh production water, and add the wash water to the desiliconized solution to obtain 5000ml of desiliconized solution.

[0123] S2, after desiliconization, the pH of the solution is 10. Take 500 ml of the desiliconized solution, adjust the temperature to 50℃, adjust the pH to 2.0, add 40.0 g of ammonium sulfate, and react for 30 min. Then add another 500 ml of the desiliconized solution, adjust the pH to 7.5, and continue reacting for 50 min. Filter to obtain SAV and primary filtrate. Wash the SAV once with the same volume of fresh production water at 35℃, and add the wash water to the primary filtrate (V = 5 g / L).

[0124] S3: Dissolve 80g of SAV in 1000ml of fresh production water at 30℃ and pH=2.0, then add 0g of ammonium sulfate, heat to 90℃ and react for 60min, then filter to obtain the first APV and the second secondary filtrate. Wash the first APV once with the same volume of fresh production water at 90℃, and add the wash water to the second secondary filtrate (V=0.2g / L).

[0125] S4, the first APV was calcined at 600℃ for 120 min with an oxygen content of 16% in the calcination atmosphere to obtain vanadium pentoxide. The vanadium pentoxide contained 99.89% V2O5, 0.025% Na, 0.023% Si, and 0.012% Cr.

[0126] S5: The primary filtrate is diluted with 1000 ml of vanadium solution to obtain 2000 ml of mixed solution, with a V of 22.5 g / L. The pH is directly adjusted to 2.0, and the mixture is precipitated at 85℃ for 90 min. Filtration yields the second APV and the first and third stage filtrates. The first and third stage filtrates are then used for large-scale production. The second and second stage filtrates, after three cycles of acid dissolution of SAV, are diluted with 1000 ml of vanadium solution to obtain 2000 ml of mixed solution, with a V of 20.1 g / L. The pH is directly adjusted to 2.5, and the mixture is precipitated at 90℃ for 60 min. Filtration yields the fourth APV and the third stage filtrate. The third stage filtrate is then used for large-scale production. The second and fourth APVs are calcined at 500℃ for 240 min to obtain vanadium pentoxide.

[0127] Example 5

[0128] Take 5000ml of vanadium solution with a vanadium concentration (TV) of 60g / L, Na / V (mass ratio) = 1.1, Si content of 2.0g / L, and Cr content of 7g / L.

[0129] S1. Adjust the temperature of the vanadium solution to 50℃, adjust the pH of the vanadium solution to 10.5 with 50% (v / v) sulfuric acid, then add 238g of Al2(SO4)3·18H2O, stir for 30 minutes, let stand for 48 hours, and then filter to obtain the desiliconized liquid and desiliconized slag. Wash the desiliconized slag with 250ml of fresh production water, and add the wash water to the desiliconized liquid to obtain 5000ml of desiliconized liquid.

[0130] S2, after desiliconization, the pH of the solution is 10. Take 500 ml of the desiliconized solution, adjust the temperature to 50℃, adjust the pH to 2.0, add 72 g of ammonium sulfate, and react for 30 min. Then add another 500 ml of the desiliconized solution, pH 8.5, and then add ammonia water (30% mass fraction) to adjust the pH to 11.0. Continue to react for 50 min, then filter to obtain SAV and primary filtrate. Wash the SAV once with the same volume of fresh production water at 35℃, and add the wash water to the primary filtrate (V = 4 g / L).

[0131] S3: Dissolve 125g of SAV in 1000ml of fresh production water at 30℃ and pH=2.0, then add 15g of ammonium sulfate, heat to 90℃ and react for 60min, then filter to obtain the first APV and the second secondary filtrate. Wash the first APV once with the same volume of fresh production water at 90℃, and add the wash water to the second secondary filtrate (V=0.1g / L).

[0132] S4, the first APV was calcined at 600℃ for 120 min with an oxygen content of 16% in the calcination atmosphere to obtain vanadium pentoxide, in which V2O5 was 99.90%, Na was 0.020%, Si was 0.01%, and Cr was 0.01%.

[0133] S5: The primary filtrate is mixed with 1000 ml of vanadium solution to obtain 2000 ml of mixed solution, with a concentration (V) of 32 g / L. The pH is directly adjusted to 2.0, and the mixture is precipitated at 85℃ for 90 min. Filtration yields the second APV and the first and third stage filtrates. The first and third stage filtrates are then used for large-scale production. The second and second stage filtrates, after three cycles of acid dissolution of SAV, are mixed with 1000 ml of vanadium solution to obtain 2000 ml of mixed solution, with a concentration (V) of 30.05 g / L. The pH is directly adjusted to 2.5, and the mixture is precipitated at 90℃ for 60 min. Filtration yields the fourth APV and the third stage filtrate. The third stage filtrate is then used for large-scale production. The second and fourth APVs are calcined at 500℃ for 240 min to obtain vanadium pentoxide.

[0134] Example 6

[0135] Take 5000ml of vanadium solution with a vanadium concentration (TV) of 70 g / L, a Na / V (mass ratio) of 0.75, a Si content of 1.5 g / L, and a Cr content of 3 g / L.

[0136] S1. Adjust the temperature of the vanadium solution to 50℃, adjust the pH of the vanadium solution to 10.5 with 50% (v / v) sulfuric acid, then add 71.40g of Al2(SO4)3·18H2O, stir for 30 minutes, let stand for 48 hours, and then filter to obtain the desiliconized solution and desiliconized slag. Wash the desiliconized slag with 250ml of fresh production water, and add the wash water to the desiliconized solution to obtain 5000ml of desiliconized solution.

[0137] S2, after desiliconization, the pH of the solution is 10. Take 500 ml of the desiliconized solution, adjust the temperature to 50℃, adjust the pH to 2.0, add 42 g of ammonium sulfate, and react for 30 min. Then add another 500 ml of the desiliconized solution, adjust the pH to 7.5, and continue reacting for 50 min. Filter to obtain SAV and primary filtrate. Wash the SAV once with the same volume of fresh production water at 35℃, and add the wash water to the primary filtrate (V = 3 g / L).

[0138] S3: Dissolve 100g of SAV in 500ml of fresh production water at 30℃ and pH=2.0, then add 40g of ammonium sulfate, heat to 90℃ and react for 60min, then filter to obtain the first APV and the second secondary filtrate. Wash the first APV once with the same volume of fresh production water at 90℃, and add the wash water to the second secondary filtrate (V=0.02g / L).

[0139] S4, the first APV was calcined at 600℃ for 120 min with an oxygen content of 16% in the calcination atmosphere to obtain vanadium pentoxide. The vanadium pentoxide contained 99.86% V2O5, 0.033% Na, 0.023% Si, and 0.021% Cr.

[0140] S5: The primary filtrate is diluted with 1000 ml of vanadium solution to obtain 2000 ml of mixed solution, with a V of 36.5 g / L. The pH is directly adjusted to 2.0, and the mixture is precipitated at 85℃ for 90 min. Filtration yields the second APV and the first and third stage filtrates. The first and third stage filtrates are then used for large-scale production. The second and second stage filtrates, after three cycles of acid dissolution of SAV, are diluted with 1000 ml of vanadium solution to obtain 2000 ml of mixed solution, with a V of 35.1 g / L. The pH is directly adjusted to 2.5, and the mixture is precipitated at 90℃ for 60 min. Filtration yields the fourth APV and the third stage filtrate. The third stage filtrate is then used for large-scale production. The second and fourth APVs are calcined at 500℃ for 240 min to obtain vanadium pentoxide.

[0141] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0142] The terms "comprising" and "having," and any variations thereof, used in the specification, claims, and accompanying drawings of this invention are intended to cover non-exclusive inclusion; the terms "first," "second," etc., used in the specification, claims, and accompanying drawings are used to distinguish different objects, not to describe a particular order. "A plurality of" means two or more, unless otherwise explicitly specified.

[0143] It should be noted that the components or steps in the above embodiments can be interchanged, substituted, added, or deleted. Therefore, the combinations formed by these reasonable permutations and transformations should also fall within the protection scope of this invention, and the protection scope of this invention should not be limited to the above embodiments.

[0144] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention (including the claims) is limited to these examples. Within the framework of the invention, technical features of the above embodiments or different embodiments can be combined, and many other variations of the different aspects of the invention as described above exist, which are not provided in the details for the sake of brevity. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the invention should be included within the protection scope of the invention.

Claims

1. A method for preparing vanadium pentoxide using a sodium vanadium vanadium hydroxide solution containing silicon chromium, characterized in that, Includes the following steps: S1, adjust the pH of the vanadium solution to 9.8~10.5, then add aluminum sulfate as a desiliconizing agent, and after settling and filtration, obtain the desiliconized liquid and desiliconized slag; S2, adjust the temperature and pH of the desiliconized solution successively, then add ammonium salt to obtain a first-order reaction system for the first-order reaction. The first-order reaction includes the following steps: S2.1 Take a certain volume of the desiliconized liquid, adjust the temperature of the desiliconized liquid to 10℃~50℃, and then adjust the pH value to 0~3.0, and react for 5min~30min; S2.2, Add the same volume of the desiliconized solution to step S2.1, adjust the pH value to 5.0~9.0, and react for 30min~60min; S2.3, after the reaction is complete and filtered, SAV and primary filtrate are obtained; S3, after hot dissolving SAV, adds ammonium salt to obtain a first and second secondary reaction system for the first and second secondary reactions, cools and crystallizes, and then filters to obtain AMV and the first and second secondary filtrate; or, After dissolving SAV in acid, ammonium salt is added to obtain a second-secondary reaction system for the second-secondary reaction. After filtration, the first APV and the second-secondary filtrate are obtained. S4, calcining AMV or the first APV to obtain vanadium pentoxide.

2. The method according to claim 1, characterized in that, In step S1, The desiliconization temperature is 20℃~80℃, the molar ratio of Si to Al is 0.8~1.2, the desiliconization stirring time is 20min~60min, and the standing time is ≥48h.

3. The method according to claim 2, characterized in that, Step S1 also includes the following steps: The silicon slag is washed once with fresh production water. The amount of fresh production water used for washing is 1 / 20 of the amount of vanadium solution before silicon removal. The washing filtrate is then added to the solution after silicon removal.

4. The method according to claim 1, characterized in that, In step S2, the ammonium salt is ammonium sulfate; In step S2.1, the amount of ammonium sulfate added is NH4. + The quality ratio compared to TV is 1.2~2; In step S2.2, the total NH4 + The quality ratio compared to TV is 0.6~1.

2.

5. The method according to claim 4, characterized in that, In step S2.2, If the Cr content in the vanadium solution is greater than 5 g / L, then ammonia should be added to adjust the pH to 9.5-11.

6. The method according to claim 4, characterized in that, It also includes the following steps: SAV is washed once with fresh production water at a temperature of 10℃~35℃. The volume of fresh production water used for washing is the same as that used for SAV, and the washing water is added to the primary filtrate.

7. The method according to claim 1, characterized in that, Step S3 also includes the following steps: S3.1.1, the hot dissolution temperature of SAV is 80℃~95℃, and the amount of hot dissolution water of SAV is controlled so that the content of TV after all SAV is dissolved is 25g / L~35g / L; S3.2.1 When SAV is completely dissolved, the temperature is lowered to ≤70℃, and then ammonium sulfate is added, with the mass ratio of ammonium sulfate to SAV being 0.5~0.8; S3.3.1 After the reaction is complete, cool down to crystallize. The crystallization temperature is 20℃~50℃ and the crystallization time is 90min~240min. S3.4.1 After crystallization, filter to obtain AMV and first and second stage filtrates.

8. The method according to claim 7, characterized in that, It also includes the following steps: AMV is washed once with fresh production water at a temperature of 10℃~35℃. The volume of fresh production water used for washing is the same as that of AMV, and the washing water is added to the first and second stage filtrates. The first and second stage filtrates can be recycled and hot-dissolved SAV 4-8 times.

9. The method according to claim 1, characterized in that, Step S3 also includes the following steps: S3.1.2, the pH value for SAV acid dissolution is 1.8~2.5, and the amount of SAV acid dissolution water is controlled so that the TV content is 25g / L~80g / L after all SAV is dissolved; S3.2.2, When SAV is completely dissolved, add ammonium sulfate, wherein the amount of ammonium sulfate added is: If the vanadium content is ≤40g / L, the mass ratio of ammonium sulfate to TV is 0. If vanadium content is 40g / L < 60g / L, the mass ratio of ammonium sulfate to TV is 0.2~0.5; If the vanadium content is 60g / L~80g / L, the mass ratio of ammonium sulfate to TV is 0.5~1.0; S3.3.2 After adding the ammonium salt, raise the temperature to react. The reaction temperature is 80℃~95℃ and the reaction time is 60min~90min. S3.4.2 After the reaction is complete, filter to obtain the first APV and the second secondary filtrate.

10. The method according to claim 9, characterized in that, It also includes the following steps: The first APV is washed once with fresh production water at a temperature of 80℃~95℃. The pH value of the fresh production water is 1.5~7.

0. The volume of fresh production water used for washing is the same as that used for the first APV. The washing water is then added to the second and third stage filtrates. The second and third stage filtrates can be recycled to acid dissolve SAV 2-3 times.

11. The method according to claim 1, characterized in that, In step S4, The calcination temperature is 500℃~600℃, the calcination time is 120min~240min, and the oxygen content in the calcination atmosphere is >15%.

12. The method according to claim 1, characterized in that, It also includes the step of precipitating APV by preparing equal volumes of vanadium solution using primary filtrate, first-secondary filtrate, or second-secondary filtrate, respectively. The first-stage filtrate is mixed with an equal volume of vanadium solution, the pH value is adjusted to 1.8~2.5, the precipitation temperature is 80℃~95℃, and the precipitation time is 60min~120min to obtain the second APV and the first and third-stage filtrates. The first and second stage filtrates of the cyclic hot dissolution SAV are mixed with the same volume of vanadium solution after a certain number of cycles. The pH is adjusted to 1.8~2.5, the precipitation temperature is 80℃~95℃, and the precipitation time is 60min~120min to obtain the third APV and the second and third stage filtrates; or The second and second stage filtrates of the SAV were cyclically acid-dissolved a certain number of times, and the same volume of vanadium solution was prepared. The pH value was adjusted to 1.8~2.5, the precipitation temperature was 80℃~95℃, and the precipitation time was 60min~120min to obtain the fourth APV and the third and third stage filtrates. The obtained second, third, and fourth APVs were calcined to obtain vanadium pentoxide.

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