Method for preparing high-purity vanadium pentoxide
By combining ammonium bicarbonate and aluminum-based crystallization inhibitors, the crystallization process is controlled, solving the problems of chloride ion residue, organic phase contamination, and impurity introduction in the preparation of high-purity vanadium pentoxide in existing technologies. This achieves efficient and low-cost preparation of high-purity vanadium pentoxide, which is suitable for new energy, electronic information, and aerospace fields.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- PANZHIHUA IRON & STEEL RES INST OF PANGANG GROUP
- Filing Date
- 2025-12-29
- Publication Date
- 2026-04-17
AI Technical Summary
Existing methods for preparing high-purity vanadium pentoxide suffer from problems such as residual chloride ions, organic phase contamination, low exchange capacity, long processing cycles, and the introduction of new impurities by crystallization inhibitors, making it difficult to meet the demands for high purity and large-scale production.
High-purity vanadium pentoxide was prepared using ammonium bicarbonate and aluminum-based crystallization inhibitors. The process involved slurrying, resolution, impurity removal, hydrolysis, vanadium precipitation, and calcination. Artificial intelligence was used to optimize the addition strategy of the crystallization inhibitor, control the crystallization process, and improve the vanadium concentration and solution stability.
The preparation of high-purity vanadium pentoxide has been achieved, simplifying the process, reducing costs, improving vanadium yield and solution stability, and reducing the introduction of impurities. It is suitable for fields such as new energy, electronic information, and aerospace.
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Figure CN121872437A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of vanadium chemical industry, specifically relating to a method for preparing high-purity vanadium pentoxide. Background Technology
[0002] High-purity vanadium pentoxide (purity ≥ 99.9%) plays an irreplaceable role as a key strategic material in new energy, electronic information, and high-end manufacturing. In lithium-ion batteries, high-purity vanadium pentoxide is used to prepare high-performance cathode materials, and its purity directly affects the battery's energy density and cycle life. In vanadium redox flow batteries, as a precursor to the electrolyte solute, impurity content must be strictly controlled at the ppm level to ensure the battery's charge-discharge efficiency and stability. Furthermore, in semiconductor manufacturing and aerospace coatings, stringent requirements are placed on the purity and crystal form of vanadium pentoxide, driving the continuous development of high-purity preparation technologies. With the rapid expansion of the global new energy industry, the market demand for high-purity vanadium pentoxide is expected to grow at an average annual rate of over 15% by 2025, making the need for efficient and stable preparation technologies increasingly urgent.
[0003] Traditional methods for preparing high-purity vanadium pentoxide, such as ammonium salt precipitation, solvent extraction, and ion exchange, suffer from numerous technical bottlenecks. Ammonium salt precipitation involves precipitation with NH4Cl or NH4VO3 followed by high-temperature calcination, but this method suffers from severe chloride ion residue and high energy consumption, typically resulting in a product purity of only 99.5%-99.8%. Solvent extraction uses organic systems such as P2O4 / kerosene to separate vanadate ions, which can improve purity to some extent, but it also presents environmental problems such as organic phase pollution and highly toxic extractants. Ion exchange utilizes strongly alkaline resins to adsorb vanadate ions; however, its low exchange capacity and long processing cycle make it unsuitable for large-scale production. Furthermore, these methods struggle to effectively control crystal growth during crystallization, leading to impurity co-precipitation and affecting product purity and performance.
[0004] While the preparation of high-purity vanadium pentoxide using crystallization inhibitors holds great potential, it still faces numerous challenges: the compatibility of crystallization inhibitors varies significantly across different systems, requiring precise screening and optimization based on raw material characteristics and impurity composition; the dosage and timing of inhibitor addition significantly impact crystallization efficiency, and a systematic control method is lacking; furthermore, new impurities introduced by some crystallization inhibitors may affect product quality, necessitating complementary impurity removal technologies. In the future, developing novel, highly efficient, low-toxicity, and recyclable crystallization inhibitors, optimizing inhibitor addition strategies using artificial intelligence algorithms, and exploring the synergistic effects of crystallization inhibitors with other purification technologies will be key directions for improving high-purity vanadium pentoxide preparation technology.
[0005] In addition, the use of ammonium bicarbonate for ammonium polyvanadate (APV) redissolution has the following problems: the solution system after redissolution is unstable, cannot be stored for too long, is prone to crystallization, resulting in a decrease in vanadium concentration, and is accompanied by the filtration of impurities at the end.
[0006] Therefore, existing technologies need to be improved. Summary of the Invention
[0007] The main objective of this invention is to address the shortcomings of the existing technology by providing a method for preparing high-purity vanadium pentoxide by adding a crystallization inhibitor to APV during back dissolution.
[0008] To achieve the above objectives, the present invention adopts the following technical solution: This invention provides a method for preparing high-purity vanadium pentoxide, which includes the following steps: S1: Pulping ammonium polyvanadate or red cake to obtain a slurry; S2: Add ammonium salt and aluminum crystallization inhibitor to the slurry for back dissolution to obtain a back solution, wherein the ammonium salt is one or more of ammonium carbonate, ammonium bicarbonate, and ammonia water; S3: Adjust the pH of the return solution to 9.0~11.0 with ammonia water to remove impurities, and obtain a purified solution through solid-liquid separation; S4: Adjust the pH of the purified solution to 7.0~8.2 using sulfuric acid, perform hydrolysis to remove aluminum, and obtain vanadium precipitation solution and aluminum removal slag through solid-liquid separation; S5: The vanadium precipitation solution is subjected to ammonium salt precipitation of vanadium, and after solid-liquid separation, ammonium metavanadate and vanadium precipitation supernatant are obtained; S6: Calcining the ammonium metavanadate yields high-purity vanadium pentoxide.
[0009] As a further implementation method, in step S1, the liquid-to-solid mass ratio of the pulp is 12.5 to 50:1.
[0010] As a further implementation method, in step S2, the remelting temperature is 70-95℃ and the remelting time is 1-3h.
[0011] As a further embodiment, in step S2, the amount of ammonium salt added is 1.0-3.1:1 based on the mass ratio of ammonium salt to ammonium polyvanadate or vanadium in red cake.
[0012] As a further embodiment, in step S2, the aluminum crystallization inhibitor is one or more of aluminum oxide, aluminum hydroxide, aluminum silicate, and aluminum sulfate.
[0013] As a further implementation, in step S2, the amount of aluminum crystallization inhibitor added is 1 to 10:1, calculated as the molar ratio of silicon in ammonium polyvanadate or red cake to aluminum in the aluminum crystallization inhibitor.
[0014] As a further implementation, in step S2, the amount of aluminum crystallization inhibitor added is 4~8:1, calculated as the molar ratio of silicon in ammonium polyvanadate or red cake to aluminum in the aluminum crystallization inhibitor.
[0015] As a further implementation method, in step S3, the impurity removal temperature is 70~95℃ and the impurity removal time is 1-3h.
[0016] As a further implementation, in step S4, the hydrolysis temperature is 70~95℃ and the hydrolysis time is 12-24h.
[0017] As a further embodiment, in step S5, the ammonium salt is one or more of ammonium sulfate, ammonium bicarbonate, and ammonium carbonate. The ammonium addition coefficient is 0~3.0∶1, calculated as the mass ratio of ammonium salt to ammonium polyvanadate or vanadium in red cake. The ammonium salt precipitation temperature is 20~40℃, and the ammonium salt precipitation time is 3~12h.
[0018] As a further implementation, in step S6, the calcination temperature is 580~610℃ and the calcination time is 2~4h.
[0019] As a further embodiment, the method for preparing high-purity vanadium pentoxide also includes: The aluminum slag obtained in step S4 is returned to step S2 for remelting; The vanadium supernatant obtained in step S5 is returned to step S1 for pulping.
[0020] By adopting the above technical solution, the present invention has at least one or more of the following beneficial effects compared with the prior art: (1) Simple operation and high product purity; (2) Adding crystallization inhibitors can effectively reduce the instability of the back-dissolved APV solution, increase the vanadium concentration, improve the solution stability, and facilitate the removal of impurities from the solution at the back end; (3) The process flow is short, easy to operate, and the process cost is low; (4) It has a good impurity removal effect. The aluminum slag can be reused, which is a way to make use of waste and save costs. Attached Figure Description
[0021] To more clearly illustrate the technical solution of the present invention, the accompanying drawings used in the description of the present invention will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other embodiments can be obtained based on these drawings without creative effort.
[0022] Figure 1 The flowchart shows the method for preparing high-purity vanadium pentoxide provided by the present invention. Detailed Implementation
[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.
[0024] Specific embodiments of the invention are disclosed herein as needed; however, it should be understood that the embodiments disclosed herein are merely examples of the invention that may be implemented in various alternative forms. In the following description, various operating parameters and components are described in several contemplated embodiments. These specific parameters and components are provided as examples only and are not intended to be limiting.
[0025] The endpoints and any values of the ranges disclosed in this invention 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 in this invention.
[0026] To achieve the aforementioned objectives, this invention provides a method for preparing high-purity vanadium pentoxide, such as... Figure 1 As shown, the method includes the following steps: S1: Pulping ammonium polyvanadate or red cake to obtain a slurry; S2: Add ammonium salt and aluminum crystallization inhibitor to the slurry for back dissolution to obtain a back solution, wherein the ammonium salt is one or more of ammonium carbonate, ammonium bicarbonate, and ammonia water; S3: The pH of the return solution is adjusted to 9.0~11.0 using ammonia water to remove impurities. After solid-liquid separation, a purified solution is obtained. S4: The pH of the purification solution is adjusted to 7.0~8.2 using sulfuric acid, and aluminum is deaerated by hydrolysis. After solid-liquid separation, vanadium precipitation solution and aluminum removal slag are obtained. S5: The vanadium precipitation solution is subjected to ammonium salt precipitation of vanadium, and after solid-liquid separation, ammonium metavanadate and vanadium precipitation supernatant are obtained; S6: Calcining ammonium metavanadate yields high-purity vanadium pentoxide.
[0027] In this invention, high-purity vanadium pentoxide is prepared by pulping, resolution, impurity removal, vanadium precipitation, and calcination of ammonium polyvanadate or red cake. In particular, by adding aluminum crystallization inhibitors during the resolution process, the vanadium concentration can be increased, the stability of the resolution solution can be improved, and the impurity removal of the solution at the downstream end can be facilitated. At the same time, it plays a flocculation role, condensing the silicon in the solution, which is convenient for removal during solid-liquid separation.
[0028] The present invention will be further described below for each step.
[0029] In step S1, ammonium polyvanadate or red cake is pulped according to a certain liquid-to-solid mass ratio. The "liquid-to-solid mass ratio" refers to the mass ratio of the pulping solution to the ammonium polyvanadate or red cake, and the mass of the pulping solution and the ammonium polyvanadate or red cake is usually measured in grams.
[0030] Ammonium polyvanadate or red cake can be the product obtained by calcification acid leaching of vanadium. In some embodiments, the V content of ammonium polyvanadate or red cake is 43% to 50%, the silicon content is 0.1% to 0.2%, and the iron content is 0.06% to 0.25%.
[0031] Preferably, the liquid-to-solid mass ratio of the pulp is 12.5 to 50:1. The liquid-to-solid mass ratio of the pulp can typically, but not limitedly, be set to 12.5:1, 15:1, 17.5:1, 20:1, 25:1, 30:1, 35:1, 40:1, 45:1, or 50:1.
[0032] In step S2, a certain amount of ammonium salt and a certain amount of aluminum crystallization inhibitor are added to the slurry at a certain temperature, and the reaction is carried out for a certain time to obtain a return solution. The dissolution product is mainly metavanadate, which has a stable pH range of 7-9. pH plays a key regulatory role in the whole process. By adding specific ammonium salts (ammonium carbonate, ammonium bicarbonate, and ammonia), a suitable pH environment is constructed on the one hand, and additional impurities are avoided on the other hand.
[0033] Preferably, the remelting temperature is 70-95℃, and the remelting time is 1-3h. The remelting temperature is typically, but not limited to, 70℃, 75℃, 80℃, 85℃, 90℃, and 95℃; the remelting time is typically, but not limited to, 1h, 2h, and 3h.
[0034] Preferably, the amount of ammonium salt added is 1.0-3.1:1 based on the mass ratio of ammonium salt to ammonium polyvanadate or vanadium in red cake. The amount of ammonium salt added can typically, but not limitedly, be set to 1.0:1, 1.5:1, 2.0:1, 2.5:1, or 3.1:1.
[0035] Preferably, the aluminum crystallization inhibitor is one or more of aluminum oxide, aluminum hydroxide, aluminum silicate, and aluminum sulfate.
[0036] Preferably, the amount of aluminum crystallization inhibitor added is 1 to 10:1, calculated based on the molar ratio of silicon in ammonium polyvanadate or red cake to aluminum in the aluminum crystallization inhibitor. The amount of aluminum crystallization inhibitor added is typically, but not limited to, 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, or 10:1. The aluminum crystallization inhibitor is added in a significantly excessive manner to inhibit the rapid crystallization of ammonium vanadate salts through the action of aluminum ions and aluminum salt colloids.
[0037] More preferably, the amount of aluminum crystallization inhibitor added is 4~8:1.
[0038] In step S3, the core process involves using ammonia to adjust the pH for impurity removal, primarily targeting impurities such as Mn, Fe, Ca, and Mg. By adjusting the pH, ammonia synergizes with carbonate ions in the solution, causing these impurities to precipitate as hydroxides and carbonates. Simultaneously, this system undergoes adsorption and flocculation with the aluminum salts and aluminosilicate colloids from step S2, achieving co-precipitation and further enhancing the impurity removal effect. Ammonia is chosen because it does not introduce additional impurity elements, is inexpensive, and its ammonium ions provide favorable conditions for the subsequent vanadium precipitation process.
[0039] Preferably, the impurity removal temperature is 70~95℃, and the impurity removal time is 1-3h. The impurity removal temperature is typically, but not limited to, 70℃, 75℃, 80℃, 85℃, 90℃, and 95℃; the impurity removal time is typically, but not limited to, 1h, 2h, and 3h.
[0040] In step S4, sulfuric acid is used to adjust the pH for aluminum hydrolysis. Concentrated sulfuric acid allows for rapid and precise pH control, aiming to remove excess Al from the solution. Specifically, adjusting the pH value promotes Al... 3+ Hydrolysis generates Al(OH)3 precipitate, thus completing the aluminum removal process.
[0041] Preferably, the hydrolysis temperature is 70~95℃, and the hydrolysis time is 12-24h. The hydrolysis temperature is typically, but not limited to, 70℃, 75℃, 80℃, 85℃, 90℃, and 95℃; the hydrolysis time is typically, but not limited to, 12h, 15h, 18h, 21h, and 24h.
[0042] Preferably, the aluminum-removing slag obtained in step S4 is returned to step S2 for reuse. The aluminum-removing slag contains vanadium; returning it can increase vanadium yield and improve aluminum salt utilization.
[0043] In step S5, ammonium salt is added to the vanadium precipitation solution to precipitate ammonium metavanadate.
[0044] Preferably, the ammonium salt is one or more of ammonium sulfate, ammonium bicarbonate, and ammonium carbonate.
[0045] Preferably, the ammonium addition coefficient, calculated as the mass ratio of ammonium salt to vanadium in ammonium polyvanadate or red cake, is 0 to 3.0:1. The ammonium addition coefficient is typically, but not limited to, 0:1, 1.0:1, 2.0:1, and 3.0:1. A coefficient of 0:1 means that ammonium salt may not be added. In step S2, ammonium salt is used for back dissolution; provided that the ammonium ions in the solution are sufficient to meet the requirements for vanadium precipitation, no additional ammonium salt may be added in step S4.
[0046] Preferably, the ammonium salt vanadium precipitation temperature is 20~40℃, and the ammonium salt vanadium precipitation time is 3~12h. The ammonium salt vanadium precipitation temperature is typically, but not limited to, 20℃, 25℃, 30℃, 35℃, and 40℃; the ammonium salt vanadium precipitation time is typically, but not limited to, 3h, 6h, 9h, and 12h.
[0047] Preferably, the vanadium supernatant obtained in step S5 is returned to step S1 for pulping, thereby realizing the recycling of water. After several cycles, it is removed from the cycle for wastewater treatment.
[0048] In step S6, ammonium metavanadate is calcined to obtain high-purity vanadium pentoxide.
[0049] Preferably, the calcination temperature is 580~610℃, and the calcination time is 2~4h. The calcination temperature is typically, but not limited to, 580℃, 590℃, 600℃, and 610℃; the calcination time is typically, but not limited to, 2h, 3h, and 4h.
[0050] In some embodiments, this method can be implemented in production as follows: APV (V content 43%~50%, silicon content 0.1%-0.2%, iron content 0.06%-0.25%) obtained by calcification acid leaching of vanadium is pulped at a liquid-to-solid mass ratio of 12.5~50:1; ammonium bicarbonate (ammonium bicarbonate / vanadium = 1.0-3.1 (mass ratio)) and a crystallization inhibitor (a crystallization inhibitor is one of alumina, aluminum hydroxide, or aluminum silicate, added in an amount such that the Si / Al ratio of the APV is 1~10, preferably Si / Al = 4~8 (molar amount)) are added at a temperature of 70-95°C, and the reaction is carried out for 1-3 hours; after resolution, the solution is purified, and ammonia is added to adjust the pH to 9-11, while the temperature is 70~95°C. After standing for 1-3 hours to remove iron, Mn, Ca, and Mg, a purified solution is obtained. The pH of the purified solution is adjusted to 7.0-8.2 using concentrated sulfuric acid (98%) at a temperature of 70-95℃. After standing for 12-24 hours, aluminum is deaerated. After solid-liquid separation, the aluminum slag is returned to the remelting process for reuse. Ammonium salts are added to the vanadium precipitation solution to precipitate ammonium metavanadate. The ammonium salt can be one or more of ammonium sulfate, ammonium bicarbonate, and ammonium carbonate. The ammonium salt / vanadium ratio is 0-3.0 (mass ratio) at a temperature of 20-40℃ and a precipitation time of 3-12 hours. The supernatant of the vanadium precipitation solution after solid-liquid separation is returned to the pulping process for recycling. After 4 cycles, wastewater is treated. The precipitated ammonium metavanadate is calcined at 580-610℃ for 2-4 hours to obtain vanadium pentoxide.
[0051] The following describes the process methods mentioned in this invention with specific embodiments, but this invention is not limited to the following embodiments.
[0052] Example 1 The vanadium-containing polymer (APV) obtained by calcification and acid leaching of vanadium (V content 43%, silicon content 0.1%, iron content 0.06%) was pulped at a liquid-to-solid mass ratio of 12.5:1. Ammonium bicarbonate (ammonium bicarbonate / vanadium = 1.0 (mass ratio)) and a crystallization inhibitor (alumina, added in an amount equal to the silicon content of the APV, Si / Al = 4) were added at 70°C, and the reaction was carried out for 1 hour. After resolubilization, the solution was purified by adding ammonia to adjust the pH to 9, and the temperature was maintained at 70°C. The solution was allowed to stand for 1 hour to remove iron, Mn, Ca, and Mg, yielding the desired product. Purification solution: The pH of the purification solution was adjusted to 7.0 using concentrated sulfuric acid (98%) at 70℃. After standing for 12 hours, aluminum was degraded. After solid-liquid separation, the aluminum slag was returned to the remelting process for reuse. Ammonium sulfate was added to the vanadium precipitation solution to precipitate ammonium metavanadate. The ammonium sulfate addition coefficient was 1 (mass ratio of ammonium sulfate to vanadium sulfate). The precipitation temperature was 20℃, and the precipitation time was 3 hours. The supernatant of the vanadium precipitation solution was returned to the pulping process for recycling. After 4 cycles, wastewater was treated. The precipitated ammonium metavanadate was calcined at 580℃ for 2 hours to obtain vanadium pentoxide. The purity of vanadium pentoxide was 99.96%.
[0053] Example 2 The vanadium-containing polymer (APV) obtained by calcification and acid leaching of vanadium (V content 47%, silicon content 0.15%, iron content 0.15%) was pulped at a liquid-to-solid mass ratio of 30:1. Ammonium bicarbonate (ammonium bicarbonate / vanadium = 2 by mass) and a crystallization inhibitor (aluminum hydroxide, added in an amount equal to the silicon content of the APV, Si / Al = 6 by mole) were added at 80°C, and the reaction was carried out for 2 hours. After resolubilization, the solution was purified by adding ammonia to adjust the pH to 10, and the temperature was maintained at 80°C for 2 hours to remove iron, Mn, Ca, and Mg, yielding the desired product. The purified solution was prepared by adjusting the pH to 7.6 with concentrated sulfuric acid (98%) at 80°C and allowing it to stand for 18 hours to hydrolyze the aluminum. After solid-liquid separation, the aluminum slag was returned to the remelting process for reuse. Ammonium salt was added to the vanadium precipitation solution to precipitate ammonium metavanadate. The ammonium salt could be ammonium bicarbonate, with an ammonium salt / vanadium ratio of 2 (mass ratio). The precipitation time was 8 hours at 30°C. The supernatant from the vanadium precipitation was returned to the pulping process for recycling. After four cycles, the precipitated ammonium metavanadate was treated as wastewater. The calcined ammonium metavanadate was calcined at 600°C for 3 hours to obtain vanadium pentoxide. The purity of vanadium pentoxide was 99.95%.
[0054] Example 3 The vanadium-containing polyvinyl chloride (PV) obtained by calcification and acid leaching (V content 50%, silicon content 0.2%, iron content 0.25%) was pulped at a liquid-to-solid mass ratio of 50:1. Ammonium bicarbonate (ammonium bicarbonate / vanadium = 3.1 by mass) and a crystallization inhibitor (aluminum silicate, added in an amount equal to the silicon content of the PV, Si / Al = 8 by mole) were added at 95°C, and the reaction was carried out for 3 hours. After resolution, the solution was purified by adding ammonia to adjust the pH to 11, maintaining the temperature at 95°C, and allowing it to stand for 3 hours to remove iron, Mn, Ca, and Mg, obtaining a purified solution. The pH of the leaching solution was adjusted to 8.2 using concentrated sulfuric acid (98%), and the temperature was 95℃. After standing for 24 hours, aluminum was degraded. After solid-liquid separation, the aluminum slag was returned to the remelting process for reuse. Ammonium salts were added to the vanadium precipitation solution to precipitate ammonium metavanadate. The ammonium salt can be one or more of ammonium carbonates, with an ammonium salt / vanadium ratio of 3.0 (mass ratio). The temperature was 40℃, and the precipitation time was 12 hours. The supernatant of the vanadium precipitation solution was returned to the pulping process for recycling. After four cycles, wastewater was treated. The precipitated ammonium metavanadate was calcined at 610℃ for 2-4 hours to obtain vanadium pentoxide. The purity of vanadium pentoxide was 99.98%.
[0055] Comparative Example 1 The APV (vanadium peroxide, silicon, and iron content) obtained from calcified acid leaching of vanadium (43% vanadium, 0.1% silicon, and 0.06% iron) was pulped at a liquid-to-solid mass ratio of 12.5:1. Ammonium bicarbonate (ammonium bicarbonate / vanadium = 1.0 by mass) was added at 70°C, without adding any crystallization inhibitors, and the reaction was allowed to proceed for 1 hour. After resolution, the solution was purified by adding ammonia to adjust the pH to 9, maintaining the temperature at 70°C, and allowing it to stand for 1 hour to remove Fe, Mn, Ca, and Mg, resulting in a purified solution. Due to the absence of crystallization inhibitors, 36% of the vanadium precipitated prematurely and was included in the impurity removal residue. Vanadium loss occurred. The purification solution was adjusted to pH 7.0 with concentrated sulfuric acid (98%) at 70℃ and allowed to stand for 12 hours to hydrolyze the aluminum. After solid-liquid separation, the aluminum slag was returned to the remelting process for reuse. Ammonium sulfate was added to the vanadium precipitation solution to precipitate ammonium metavanadate. The ammonium sulfate addition coefficient was ammonium salt / vanadium = 1 (mass ratio). The temperature was 20℃ and the precipitation time was 3 hours. The supernatant from the vanadium precipitation after solid-liquid separation was returned to the pulping process for recycling. After four cycles, wastewater was treated. The precipitated ammonium metavanadate was calcined at 580℃ for 2 hours to obtain vanadium pentoxide. The purity of vanadium pentoxide was 99.82%, and the Si content was 0.06%, exceeding the control standard of ≤0.01%.
[0056] In summary, the present invention has the following advantages compared with the prior art: (1) Simple operation and high product purity; (2) Adding crystallization inhibitors can effectively reduce the instability of ammonium bicarbonate re-dissolving APV solution, increase vanadium concentration, improve solution stability, and facilitate the removal of impurities from the solution at the downstream end. (3) The process flow is short, easy to operate, and the process cost is low; (4) It has a good impurity removal effect. The aluminum slag can be reused, which is a way to make use of waste and save costs.
[0057] Finally, it should be noted that the embodiments described above are only some, not all, of the embodiments of the present invention. The detailed description of the embodiments of the present invention is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.
Claims
1. A method for preparing high-purity vanadium pentoxide, characterized in that, Includes the following steps: S1: Pulping ammonium polyvanadate or red cake to obtain a slurry; S2: Add ammonium salt and aluminum crystallization inhibitor to the slurry for back dissolution to obtain a back solution, wherein the ammonium salt is one or more of ammonium carbonate, ammonium bicarbonate, and ammonia water; S3: Adjust the pH of the return solution to 9.0~11.0 with ammonia water to remove impurities, and obtain a purified solution through solid-liquid separation; S4: Adjust the pH of the purified solution to 7.0~8.2 using sulfuric acid, perform hydrolysis to remove aluminum, and obtain vanadium precipitation solution and aluminum removal slag through solid-liquid separation; S5: The vanadium precipitation solution is subjected to ammonium salt precipitation of vanadium, and after solid-liquid separation, ammonium metavanadate and vanadium precipitation supernatant are obtained; S6: Calcining the ammonium metavanadate yields high-purity vanadium pentoxide.
2. The method for preparing high-purity vanadium pentoxide according to claim 1, characterized in that, In step S1, the liquid-to-solid mass ratio of the pulp is 12.5~50:
1.
3. The method for preparing high-purity vanadium pentoxide according to claim 1, characterized in that, In step S2, the remelting temperature is 70-95℃, the remelting time is 1-3h, and the amount of ammonium salt added is 1.0-3.1:1 based on the mass ratio of ammonium salt to ammonium polyvanadate or vanadium in red cake.
4. The method for preparing high-purity vanadium pentoxide according to claim 1, characterized in that, In step S2, the aluminum crystallization inhibitor is one or more of aluminum oxide, aluminum hydroxide, aluminum silicate, and aluminum sulfate, and the amount of aluminum crystallization inhibitor added is 1 to 10:1 based on the molar ratio of silicon in ammonium polyvanadate or red cake to aluminum in the aluminum crystallization inhibitor.
5. The method for preparing high-purity vanadium pentoxide according to claim 4, characterized in that, In step S2, the amount of aluminum crystallization inhibitor added is 4~8:1, calculated as the molar ratio of silicon in ammonium polyvanadate or red cake to aluminum in the aluminum crystallization inhibitor.
6. The method for preparing high-purity vanadium pentoxide according to claim 1, characterized in that, In step S3, the impurity removal temperature is 70~95℃ and the impurity removal time is 1-3h.
7. The method for preparing high-purity vanadium pentoxide according to claim 1, characterized in that, In step S4, the hydrolysis temperature is 70~95℃, and the hydrolysis time is 12-24h.
8. The method for preparing high-purity vanadium pentoxide according to claim 1, characterized in that, In step S5, the ammonium salt is one or more of ammonium sulfate, ammonium bicarbonate, and ammonium carbonate. The ammonium addition coefficient is 0~3.0∶1, calculated as the mass ratio of ammonium salt to ammonium polyvanadate or vanadium in red cake. The ammonium salt precipitation temperature is 20~40℃, and the ammonium salt precipitation time is 3~12h.
9. The method for preparing high-purity vanadium pentoxide according to claim 1, characterized in that, In step S6, the calcination temperature is 580~610℃ and the calcination time is 2~4h.
10. The method for preparing high-purity vanadium pentoxide according to claim 1, characterized in that, Also includes: The aluminum slag obtained in step S4 is returned to step S2 for remelting; The vanadium supernatant obtained in step S5 is returned to step S1 for pulping.