Method for preparing high-purity vanadium pentoxide by dissolving ammonium vanadate and removing impurities

Abstract

The invention provides a method for preparing high-purity vanadium pentoxide by dissolving and purifying ammonium vanadate, which comprises the following steps: adding a vanadium-containing intermediate into a magnesium salt-carbonate composite reaction system to react to obtain a vanadium-containing return solution, and adding an impurity removing agent into the vanadium-containing return solution to react to obtain a vanadium-containing purified solution, and adding a complexing agent and an ammonium salt into the vanadium-containing purified liquid, cooling and reacting to obtain a vanadium precipitation product ammonium metavanadate, drying the vanadium precipitation product ammonium metavanadate, and calcining to obtain vanadium pentoxide. According to the method, the magnesium salt-carbonate composite reaction system is adopted to realize re-dissolution of vanadium, ammonium metavanadate is prepared through impurity removal and complexing crystallization, the vanadium pentoxide product with the purity of 99.5% or above is obtained through calcination, and the technical problems that an existing technology for preparing the high-purity vanadium product through dissolution chemical impurity removal is long in technological process and high in production cost are solved.

Description

Technical Field

[0001] This invention relates to the field of chemical technology, and in particular to a method for preparing high-purity vanadium pentoxide by dissolving and removing impurities from ammonium vanadate. Background Technology

[0002] The main challenge in preparing high-purity vanadium oxide lies in the efficient and low-cost removal of impurities. Furthermore, due to the stringent requirements for controlling impurity levels—generally requiring impurities to be below 0.01 wt% in vanadium pentoxide products with a purity of 99.5% or higher—the stability and ease of implementation of the impurity removal process are crucial constraints on high-purity vanadium production. Currently, the vanadium pentoxide purification technology used in production is the alkaline dissolution method. Its advantages include simple operation and low equipment requirements. However, to achieve the desired impurity removal effect, multiple stages of alkaline dissolution-precipitation operations are often required, resulting in a long process flow, high reagent consumption, low vanadium yield, and large wastewater treatment volume. This directly leads to high production costs, limiting the application and development of high-purity vanadium products.

[0003] Currently, the main technology for producing high-purity vanadium oxide still uses crude vanadium, such as vanadium pentoxide or industrial-grade vanadate products, as raw materials. After dissolving to obtain a vanadium-containing solution, impurities are removed and purified. Impurities removed include Al, Si, P, Fe, Mn, Ca, Cr, K, and Na. The purified vanadium solution is then precipitated again to obtain ammonium metavanadate with higher purity, which is finally calcined to produce vanadium pentoxide. Dissolution methods include using solvents such as sodium hydroxide, ammonia, ammonium carbonate, and sodium carbonate to obtain an alkaline vanadium solution, or using sulfuric acid to dissolve and reduce vanadium pentoxide to obtain an acidic tetravalent vanadium solution, which is then purified. Purification processes mainly employ extraction, ion exchange resin, and chemical impurity removal agents such as lanthanum, strontium, magnesium, and calcium salts. These methods differ significantly depending on the type of impurities and product requirements. Extraction and ion exchange techniques generally offer better impurity removal, controlling impurity ions to below 30 ppm, but the processes are more complex and the reagent costs are higher. Depending on the solution pH and the type of impurities, the vanadium precipitation process can employ alkaline ammonium salt precipitation technology and acidic ammonium salt precipitation technology to prepare ammonium metavanadate and ammonium polyvanadate products, respectively.

[0004] CN 106241873 B discloses a method for preparing high-purity vanadium pentoxide, which involves preparing a solution using crude ammonium metavanadate; adding sodium hydroxide and sodium carbonate to the solution to adjust its pH to 8.5–9.0; adding a purifying agent to the pH-adjusted solution and separating the solid and liquid phases to obtain a filtrate; adding ammonium chloride to the filtrate to obtain ammonium metavanadate precipitate, which is then washed and dehydrated to obtain ammonium metavanadate crystals; and calcining the ammonium metavanadate crystals at 500–550°C for 2–2.5 hours to obtain vanadium pentoxide. The purifying agent is one or a mixture of magnesium chloride and calcium chloride, with a pH of 4–5. This prior art, through a combination of physical and chemical methods for impurity removal, can quickly and effectively remove impurity ions, thus effectively improving the purity of the final product, vanadium pentoxide. However, the existing technology uses magnesium chloride / calcium chloride as the purifying agent, and then uses ammonium chloride washing solution to wash the ammonium metavanadate precipitate, which easily leads to the accumulation and residue of chloride ions, magnesium ions / calcium ions in the system, introducing secondary impurities. At the same time, excess ammonium chloride cannot be recovered, increasing the difficulty and cost of subsequent wastewater treatment.

[0005] CN 118062893 A discloses a method for purifying ammonium metavanadate to prepare high-purity vanadium pentoxide, comprising the following steps: S1: Adding industrial-grade ammonium metavanadate raw material to pure water, heating and stirring to dissolve, then adding NaOH, and after the reaction is complete, allowing it to stand and filter to obtain the supernatant solution; S2: Adjusting the pH of the above solution to 9-10, first adding an anionic flocculant, then adding magnesium sulfate or magnesium chloride, and after the reaction is complete, filtering to obtain a secondary purified solution; S3: Adjusting the pH of the secondary purified solution to 8-9, using a weakly alkaline ammonium salt precipitation method, adding ammonium chloride or ammonium sulfate to the heated secondary purified solution, and after the reaction is complete, cooling to room temperature and drying to obtain ammonium metavanadate; S4: Calcining the dried ammonium metavanadate in a muffle furnace to obtain high-purity vanadium pentoxide. This prior art uses a segmented chemical purification method to purify ammonium metavanadate, the entire process is carried out under alkaline or weakly alkaline conditions, with no acid consumption and a high impurity removal rate. However, the existing magnesium salt purification technology is prone to introducing residual ions, and the precipitation of vanadium ammonium salts requires a large amount of salt, resulting in serious waste, and it is difficult to guarantee that no new impurities are introduced.

[0006] CN 117623383 A discloses a method for preparing high-purity vanadium pentoxide, the method comprising the following steps: pulping ammonium polyvanadate obtained by vanadium precipitation using acidic ammonium salts in a vanadium calcification process with water to obtain a mixed slurry; heating the mixed slurry to 50-80℃ and adding ammonia to obtain a back solution of ammonium polyvanadate; maintaining the temperature of the back solution of ammonium polyvanadate at 50-80℃ and adding aluminum or calcium salts, stirring and reacting for a period of time; continuously introducing carbon dioxide gas until the pH of the solution becomes 6.5-7.5, and obtaining a purified ammonium polyvanadate solution through solid-liquid separation; cooling the purified ammonium polyvanadate solution to 10-25℃ to crystallize and precipitate ammonium metavanadate, and obtaining solid ammonium metavanadate and a vanadium precipitation supernatant through solid-liquid separation; calcining the solid ammonium metavanadate to obtain a high-purity vanadium pentoxide product. This existing technology uses ammonia to dissolve ammonium polyvanadate, avoiding the introduction of alkali metals such as K and Na, thus solving the problem of potassium and sodium-containing wastewater treatment at its source. By adding aluminum or calcium salts and introducing carbon dioxide gas, a one-stage composite impurity removal process is used to simultaneously remove impurities such as Mn, Ca, Fe, Si, and P, achieving high impurity removal efficiency. However, the impurity removal process design of this existing technology is unreasonable: after adding aluminum / calcium salts and introducing carbon dioxide, aluminum ions undergo double hydrolysis, and calcium ions and carbonate ions form carbonate precipitates. On the one hand, this consumes the impurity removal agent, reducing the impurity removal efficiency; on the other hand, the precipitates easily carry over vanadium ions, leading to a decrease in vanadium recovery rate.

[0007] CN 114180624 B discloses a method for preparing high-purity vanadium by separating vanadium and ammonium from ammonium metavanadate raw materials. This method uses one or more of high-cobalt AMV, high-silicon AMV, high-chromium AMV, and high-molybdenum AMV as raw materials. The raw material AMV is first converted into APV, and then the mother liquor and APV are treated separately. The final product can be used for the production of vanadium electrolyte, high-purity vanadium oxide, and vanadium compounds. This prior art separates ammonium and vanadium by acid washing, reducing the ammonium content in ammonium metavanadate. This effectively reduces the amount of alkali used when dissolving vanadium, lowers costs, optimizes the operating environment, and avoids ammonium loss during the conversion of ammonium into ammonia gas and subsequent acid absorption. However, this prior art has weak impurity removal targeting, a low upper limit for purity improvement, extremely high process complexity, extremely low error tolerance, high reagent consumption, and high costs.

[0008] Currently, the mainstream process for preparing high-purity vanadium pentoxide uses ammonium vanadate or ordinary vanadium pentoxide as raw materials. After dissolution, it undergoes deep impurity removal and then precipitation of high-purity ammonium metavanadate. Compared with extraction and ion exchange technologies, chemical impurity removal technology has the advantages of more stable impurity removal effect and is easier to implement for industrial production, thus it has been widely promoted for industrial use.

[0009] Based on this, there is room for improvement in simplifying the impurity removal process for preparing high-purity vanadium products using dissolution chemical impurity removal. Summary of the Invention

[0010] One of the technical problems that this invention aims to solve is that the process of preparing high-purity vanadium products by dissolution chemical purification is long and the production cost is high.

[0011] To solve the above-mentioned technical problems, embodiments of the present invention provide a method for preparing high-purity vanadium pentoxide by dissolving and removing impurities from ammonium vanadate, comprising: adding a vanadium-containing intermediate to a magnesium salt-carbonate composite reaction system to react and obtain a vanadium-containing return solution; adding an impurity remover to the vanadium-containing return solution and reacting to obtain a vanadium-containing purified solution; adding a complexing agent and an ammonium salt to the vanadium-containing purified solution and then cooling to react and obtain a vanadium-precipitated product, ammonium metavanadate; and drying and calcining the vanadium-precipitated product, ammonium metavanadate, to obtain vanadium pentoxide.

[0012] In one embodiment, the vanadium-containing intermediate is selected from ammonium metavanadate and ammonium polyvanadate.

[0013] The method for preparing high-purity vanadium pentoxide by dissolving and removing impurities from ammonium vanadate according to the present invention includes the following steps: Step 1: Add magnesium salt and carbonate to the solvent and stir until homogeneous to form a magnesium salt-carbonate composite reaction system; Step 2: Add the vanadium-containing intermediate to the magnesium salt-carbonate composite reaction system, stir evenly, and heat to 75-95℃. React until the vanadium-containing intermediate is completely dissolved to obtain a vanadium-containing return solution. Step 3: Maintain the temperature of the vanadium-containing return solution at 75-95℃ and add a vanadium-containing return solution to remove impurities. After reacting for 15-60 minutes, perform solid-liquid separation to obtain vanadium-containing purified solution and impurity-removed residue. Step 4: Add a complexing agent to the vanadium-containing purification solution, stir well, and then add ammonium salt to form a vanadium-containing solution; Step 5: Cool the vanadium-containing liquid to 5-35°C, stir the reaction and then perform solid-liquid separation to obtain the vanadium-precipitated product ammonium metavanadate and the vanadium-precipitating liquid. Step 6: After drying the vanadium precipitate ammonium metavanadate, heat it to 500-600℃ in an oxidizing atmosphere and calcine it to obtain vanadium pentoxide.

[0014] In one embodiment, in step 1, the magnesium salt is selected from at least one of magnesium oxide, magnesium hydroxide, and magnesium chloride, and the amount of magnesium salt added is 0.5 to 4 g / L based on the solvent volume.

[0015] In one embodiment, in step 1, the carbonate is selected from at least one of ammonium carbonate and ammonium bicarbonate, and the amount of carbonate added is 25-40 g / L based on the solvent volume, and the solvent is deionized water or distilled water.

[0016] In one embodiment, in step 3, the impurity remover is selected from at least one of aluminum sulfate, aluminum chloride, ferric sulfate, and ferric chloride, and the amount of impurity remover added is 0.1 to 1 g / L based on the volume of the vanadium-containing return solution.

[0017] In one embodiment, in step 4, the complexing agent is selected from at least one of ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, and hydroxyethylethylenediaminetriacetic acid; the amount of complexing agent added is 0.1 to 0.5 g / L based on the volume of the vanadium-containing purification liquid.

[0018] In one embodiment, in step 4, the ammonium salt is selected from at least one of ammonium carbonate and ammonium bicarbonate, and the amount of ammonium salt added is 8-12 g / L based on the volume of the vanadium-containing purification liquid.

[0019] In one embodiment, in step 5, the stirring reaction time is 6 to 7 hours.

[0020] In one embodiment, in step 6, the oxidizing atmosphere is an air atmosphere or an oxygen atmosphere, and the calcination time is 2 to 3 hours.

[0021] Through the above technical solution, the method for preparing high-purity vanadium pentoxide by dissolving and removing impurities from ammonium vanadate provided by the present invention uses a magnesium salt-carbonate composite reaction system to achieve the re-dissolution of vanadium. After impurity removal and complexation crystallization, ammonium metavanadate is prepared, and then calcined to obtain vanadium pentoxide product with a purity of over 99.5%. The impurity removal can be carried out by a one-step dissolution and impurity removal process to deeply remove impurities such as manganese, calcium, aluminum, iron, silicon, phosphorus, potassium, and sodium, thereby solving the technical problems of long process flow and high production cost in the preparation of high-purity vanadium products by dissolution and chemical impurity removal. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art 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.

[0023] Figure 1 This is a flowchart of a method for preparing high-purity vanadium pentoxide by dissolving and removing impurities from ammonium vanadate, as disclosed in an embodiment of the present invention. Detailed Implementation

[0024] The embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and examples. The detailed description of the following embodiments and the accompanying drawings are used to illustrate the principles of the present invention by way of example, but should not be used to limit the scope of the present invention. The present invention can be implemented in many different forms and is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

[0025] These embodiments are provided to make the invention thorough and complete, and to fully express the scope of the invention to those skilled in the art. It should be noted that, unless otherwise specifically stated, the relative arrangement of components and steps, the composition of materials, numerical expressions, and values ​​set forth in these embodiments should be interpreted as merely exemplary and not as limiting. Words such as "comprising" or "including" mean that the element preceding the word encompasses the element listed after the word, and do not exclude the possibility of encompassing other elements as well.

[0026] The present invention provides a method for preparing high-purity vanadium pentoxide by dissolving and removing impurities from ammonium vanadate, comprising: adding a vanadium-containing intermediate to a magnesium salt-carbonate composite reaction system to obtain a vanadium-containing return solution; adding an impurity remover to the vanadium-containing return solution to obtain a vanadium-containing purified solution after reaction; adding a complexing agent and an ammonium salt to the vanadium-containing purified solution and then cooling the solution to obtain a vanadium-precipitated product, ammonium metavanadate; and drying and calcining the vanadium-precipitated product, ammonium metavanadate, to obtain vanadium pentoxide.

[0027] Compared with existing technologies, the method for preparing high-purity vanadium pentoxide by dissolving and removing impurities from ammonium vanadate of the present invention uses a magnesium salt-carbonate composite reaction system to achieve the re-dissolution of vanadium. After impurity removal and complexation crystallization, ammonium metavanadate is prepared, and then calcined to obtain vanadium pentoxide product with a purity of over 99.5%. The impurity removal can be carried out in a one-step dissolution and impurity removal process to deeply remove impurities such as manganese (Mn), calcium (Ca), aluminum (Al), iron (Fe), silicon (Si), phosphorus (P), potassium (K), and sodium (Na), thereby solving the technical problems of long process flow and high production cost in the preparation of high-purity vanadium products by dissolution and chemical impurity removal.

[0028] In one embodiment, the vanadium-containing intermediate is selected from ammonium metavanadate and ammonium polyvanadate. The vanadium-containing intermediate is ammonium metavanadate, with a mass fraction of less than 98%, corresponding to a vanadium element mass fraction of 30–42.69% in the ammonium metavanadate. The vanadium element mass fraction is detected using ICP-MS (inductively coupled plasma mass spectrometry). Here, the mass fraction of ammonium metavanadate refers to the mass percentage of ammonium metavanadate in the vanadium-containing intermediate, and the vanadium element mass fraction refers to the mass ratio of vanadium element in the ammonium metavanadate.

[0029] like Figure 1 As shown, the method for preparing high-purity vanadium pentoxide by dissolving and removing impurities from ammonium vanadate according to the present invention includes the following steps: Step 1: Add magnesium salt and carbonate to the solvent and stir until homogeneous to form a magnesium salt-carbonate composite reaction system; Step 2: Add the vanadium-containing intermediate to the magnesium salt-carbonate composite reaction system, stir evenly, and heat to 75-95℃. React until the vanadium-containing intermediate is completely dissolved to obtain a vanadium-containing return solution. Step 3: Maintain the temperature of the vanadium-containing return solution at 75-95℃ and add a vanadium-containing return solution to remove impurities. After reacting for 15-60 minutes, perform solid-liquid separation to obtain vanadium-containing purified solution and impurity-removed residue. Step 4: Add a complexing agent to the vanadium-containing purification solution, stir well, and then add ammonium salt to form a vanadium-containing solution; Step 5: Cool the vanadium-containing liquid to 5-35°C, stir the reaction and then perform solid-liquid separation to obtain the vanadium-precipitated product ammonium metavanadate and the vanadium-precipitating liquid. Step 6: After drying the vanadium precipitate ammonium metavanadate, heat it to 500-600℃ in an oxidizing atmosphere and calcine it to obtain vanadium pentoxide.

[0030] In one embodiment, in step 1, the magnesium salt is selected from at least one of magnesium oxide, magnesium hydroxide, and magnesium chloride, and the amount of magnesium salt added is 0.5–4 g / L based on the solvent volume; the carbonate is selected from at least one of ammonium carbonate and ammonium bicarbonate, and the amount of carbonate added is 10–40 g / L based on the solvent volume. The magnesium salt-carbonate composite reaction system is in suspension state. The solvent is deionized water. The solvent can also be distilled water. Deionized water or distilled water can effectively avoid impurity ions interfering with the vanadium re-dissolution, impurity removal, and vanadium precipitation reaction, ensuring the purity of the vanadium precipitation products ammonium metavanadate and vanadium pentoxide.

[0031] In one embodiment, in step 1, the amount of carbonate added is 25-40 g / L based on the solvent volume.

[0032] In one embodiment, in step 2, the vanadium-containing intermediate is ammonium metavanadate, with a mass fraction of less than 98%. The ammonium metavanadate contains impurities Mn, Ca, Al, Fe, Si, P, K, Na, and other trace impurities, wherein the mass fractions of Mn, Ca, Al, Fe, Si, P, K, and Na each do not exceed 1 wt%, and the mass fractions of other trace impurities each do not exceed 0.05 wt%. Based on the volume of the magnesium salt-carbonate composite reaction system, the amount of vanadium-containing intermediate added is 20–60 g / L.

[0033] In one embodiment, in step 3, the impurity remover is selected from at least one of aluminum sulfate, aluminum chloride, ferric sulfate, and ferric chloride, and the amount of impurity remover added is 0.1 to 1 g / L based on the volume of the vanadium-containing return solution.

[0034] In some embodiments, in step 4, the complexing agent is selected from at least one of ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA), and hydroxyethylethylenediaminetriacetic acid (HEDTA). The amount of complexing agent added is 0.05–0.5 g / L, based on the volume of the vanadium-containing purified liquid.

[0035] In one embodiment, the amount of complexing agent added is 0.1 to 0.5 g / L, based on the volume of the vanadium-containing purified liquid.

[0036] In one embodiment, in step 4, the ammonium salt is selected from at least one of ammonium carbonate and ammonium bicarbonate, and the amount of ammonium salt added is 8-12 g / L based on the volume of the vanadium-containing purified liquid. Alternatively, a mixture of ammonium carbonate and ammonium bicarbonate can be used as the ammonium salt, which can achieve good impurity removal and vanadium stabilization effects. After adding the ammonium salt, the mixture is stirred again until homogeneous.

[0037] In one embodiment, the stirring reaction time in step 5 is 6–7 hours. The vanadium precipitation solution is mainly composed of the clarified supernatant of the vanadium precipitation solution, containing a small amount of accompanying vanadium-based suspended particles.

[0038] In one embodiment, in step 6, the oxidizing atmosphere is an air atmosphere or an oxygen atmosphere. The dried vanadium-precipitated product, ammonium metavanadate, is heated to 500–600°C under the oxidizing atmosphere and calcined for 2–3 hours to obtain vanadium pentoxide. The role of the oxidizing atmosphere is to isolate and consume the reducing gases in the calcination system, preventing the vanadium in the vanadium-precipitated product, ammonium metavanadate, from being reduced to low-valence vanadium compounds such as vanadium tetroxide (V₂O₄) and vanadium dioxide (VO₂) at high temperatures, thus ensuring that the valence state of the vanadium pentoxide product is qualified and its purity meets the standards.

[0039] The specific implementation of the method for preparing high-purity vanadium pentoxide by dissolving and removing impurities from ammonium vanadate according to the present invention is as follows: Example 1 Step 1: Add magnesium oxide and ammonium carbonate to deionized water and stir until homogeneous to form a suspension. Based on the volume of deionized water, the amount of magnesium oxide added is 1 g / L and the amount of ammonium carbonate added is 30 g / L. Step 2: Add ammonium metavanadate to the suspension, stir evenly, and heat to 95°C. React until the ammonium metavanadate is completely dissolved to obtain a vanadium-containing solution. The amount of ammonium metavanadate added is 50 g / L, based on the volume of the suspension. Step 3: Maintain the temperature of the vanadium-containing return solution at 95℃ and add aluminum sulfate to the vanadium-containing return solution. After reacting for 30 minutes, perform solid-liquid separation to obtain vanadium-containing purified solution and impurity-removed residue. The amount of aluminum sulfate added is 0.8 g / L based on the volume of the vanadium-containing return solution. Step 4: Add DTPA to the vanadium-containing purification solution and stir until homogeneous. Then add ammonium carbonate and stir until homogeneous to form a vanadium-containing solution. Based on the volume of the vanadium-containing purification solution, the amount of DTPA added is 0.2 g / L and the amount of ammonium carbonate added is 10 g / L. Step 5: Cool the vanadium-containing liquid to 5°C, stir and react for 6 hours, and then perform solid-liquid separation to obtain the vanadium-precipitated product ammonium metavanadate and the vanadium-precipitating liquid. Step 6: After drying the vanadium-precipitated product ammonium metavanadate, heat it to 550°C in an oxygen atmosphere and calcine it for 2 hours to obtain vanadium pentoxide.

[0040] The main impurities and their mass fractions in ammonium metavanadate are shown in Table 1. The vanadium yield of the entire process was 90.5%, and the purity of vanadium pentoxide reached 99.91%. The mass fractions of the main impurities in vanadium pentoxide were as follows: K 0.005 wt%, Al 0.001 wt%, Ca 0.012 wt%, Fe 0.004 wt%, Mn 0.002 wt%, Si 0.012 wt%, and P 0.005 wt%. The mass fractions of other impurities were all below 0.005 wt%.

[0041] Example 2 Step 1: Add magnesium chloride and ammonium bicarbonate to deionized water and stir until homogeneous to form a suspension. Based on the volume of deionized water, the amount of magnesium chloride added is 1 g / L and the amount of ammonium bicarbonate added is 25 g / L. Step 2: Add ammonium metavanadate to the suspension, stir evenly, and heat to 85°C. React until the ammonium metavanadate is completely dissolved to obtain a vanadium-containing solution. The amount of ammonium metavanadate added is 40 g / L, based on the volume of the suspension. Step 3: Maintain the temperature of the vanadium-containing return solution at 85℃ and add aluminum chloride and ferric chloride to the vanadium-containing return solution. After reacting for 15 minutes, perform solid-liquid separation to obtain vanadium-containing purified solution and impurity-removed residue. Based on the volume of the vanadium-containing return solution, the amount of aluminum chloride and ferric chloride added is 0.2 g / L and 0.1 g / L, respectively. Step 4: Add EDTA to the vanadium-containing purification solution and stir until homogeneous. Then add ammonium bicarbonate and stir until homogeneous to form a vanadium-containing solution. Based on the volume of the vanadium-containing purification solution, the amount of EDTA added is 0.2 g / L and the amount of ammonium bicarbonate added is 8 g / L. Step 5: Cool the vanadium-containing liquid to 35°C, stir and react for 6 hours, then perform solid-liquid separation to obtain the vanadium-precipitated product ammonium metavanadate and the vanadium-precipitating liquid. Step 6: After drying the vanadium-precipitated product ammonium metavanadate, heat it to 600℃ in an oxygen atmosphere and calcine it for 2 hours to obtain vanadium pentoxide.

[0042] The main impurities and their mass fractions in ammonium metavanadate are shown in Table 1. The vanadium yield of the entire process was 92.0%, and the purity of vanadium pentoxide reached 99.89%. The mass fractions of the main impurities in vanadium pentoxide were as follows: K 0.006 wt%, Al 0.008 wt%, Ca 0.022 wt%, Fe 0.018 wt%, Mn 0.009 wt%, Si 0.016 wt%, and P 0.009 wt%. The mass fractions of other impurities were all below 0.005 wt%.

[0043] Example 3 Step 1: Add magnesium hydroxide, ammonium carbonate and ammonium bicarbonate to deionized water and stir until homogeneous to form a suspension. Based on the volume of deionized water, the amount of magnesium hydroxide added is 4 g / L, and the amounts of ammonium carbonate and ammonium bicarbonate added are 10 g / L and 20 g / L, respectively. Step 2: Add ammonium metavanadate to the suspension, stir evenly, and heat to 75°C. React until the ammonium metavanadate is completely dissolved to obtain a vanadium-containing solution. Based on the volume of the suspension, the amount of ammonium metavanadate added is 20 g / L. Step 3: Maintain the temperature of the vanadium-containing return solution at 75℃ and add ferric sulfate to the vanadium-containing return solution. After reacting for 30 minutes, perform solid-liquid separation to obtain the vanadium-containing purified solution and the impurity-removed residue. The amount of ferric sulfate added is 1 g / L based on the volume of the vanadium-containing return solution. Step 4: Add DTPA to the vanadium-containing purification solution and stir until homogeneous. Then add ammonium bicarbonate and stir until homogeneous to form a vanadium-containing solution. Based on the volume of the vanadium-containing purification solution, the amount of DTPA added is 0.1 g / L and the amount of ammonium bicarbonate added is 10 g / L. Step 5: Cool the vanadium-containing liquid to 15°C, stir and react for 6 hours, then perform solid-liquid separation to obtain the vanadium-precipitated product ammonium metavanadate and the vanadium-precipitating liquid. Step 6: After drying the vanadium-precipitated product ammonium metavanadate, heat it to 500℃ in an oxygen atmosphere and calcine it for 3 hours to obtain vanadium pentoxide.

[0044] The main impurities and their mass fractions in ammonium metavanadate are shown in Table 1. The vanadium yield of the entire process was 88.5%, and the purity of vanadium pentoxide reached 99.79%. The mass fractions of the main impurities in vanadium pentoxide were as follows: K 0.010 wt%, Al 0.005 wt%, Ca 0.025 wt%, Fe 0.038 wt%, Mn 0.009 wt%, Si 0.026 wt%, and P 0.016 wt%. The mass fractions of other impurities were all below 0.005 wt%.

[0045] Example 4 Step 1: Add magnesium oxide and ammonium carbonate to deionized water and stir until homogeneous to form a suspension. Based on the volume of deionized water, the amount of magnesium oxide added is 0.5 g / L and the amount of ammonium carbonate added is 40 g / L. Step 2: Add ammonium metavanadate to the suspension, stir evenly, and heat to 95°C. React until the ammonium metavanadate is completely dissolved to obtain a vanadium-containing solution. Based on the volume of the suspension, the amount of ammonium metavanadate added is 60 g / L. Step 3: Maintain the temperature of the vanadium-containing return solution at 95℃ and add aluminum chloride to the vanadium-containing return solution. After reacting for 60 minutes, perform solid-liquid separation to obtain vanadium-containing purified solution and impurity-removed residue. The amount of aluminum chloride added is 0.1 g / L based on the volume of the vanadium-containing return solution. Step 4: Add HEDTA to the vanadium-containing purification solution and stir until homogeneous. Then add ammonium carbonate and stir until homogeneous to form a vanadium-containing solution. Based on the volume of the vanadium-containing purification solution, the amount of HEDTA added is 0.5 g / L and the amount of ammonium carbonate added is 12 g / L. Step 5: Cool the vanadium-containing liquid to 25°C, stir and react for 7 hours, then perform solid-liquid separation to obtain the vanadium-precipitated product ammonium metavanadate and the vanadium-precipitating liquid. Step 6: After drying the vanadium precipitate ammonium metavanadate, heat it to 550°C in an oxygen atmosphere and calcine it for 3 hours to obtain vanadium pentoxide.

[0046] The main impurities and their mass fractions in ammonium metavanadate are shown in Table 1. The overall vanadium yield was 91.0%, and the purity of vanadium pentoxide reached 99.85%. The mass fractions of the main impurities in vanadium pentoxide were as follows: K 0.008 wt%, Al 0.006 wt%, Ca 0.017 wt%, Fe 0.029 wt%, Mn 0.005 wt%, Si 0.021 wt%, and P 0.011 wt%. The mass fractions of other impurities were all below 0.005 wt%.

[0047] Table 1

[0048] This invention provides a method for preparing high-purity vanadium pentoxide by dissolving and removing impurities from ammonium vanadate. Addressing the problems of long processing flow, low impurity removal efficiency, unstable product quality, and high production costs associated with vanadium oxide products with a purity of 99.5% or higher, this method proposes a one-step method to remove multiple impurities. Using ordinary ammonium metavanadate (purity below 98%) as raw material, chemical impurity removal is employed. Through a one-step dissolution and impurity removal process, highly efficient and deep removal of impurities such as Mn, Ca, Al, Fe, Si, P, K, Na, and Cr is achieved, producing high-purity vanadium oxide products with a purity of 99.5% or higher. The impurity removal process is simplified, the process flow is shortened, the impurity removal effect is stable, and the vanadium yield is improved. The vanadium yield is increased to over 90%, and multiple impurities are removed in one step, reducing reagent consumption and facilitating industrial implementation. This significantly reduces the production cost of 99.5% pure vanadium oxide and possesses high production application value.

[0049] Although various embodiments of the present invention have been described in detail, some details known in the art have not been described in order to avoid obscuring the concept of the invention. Those skilled in the art will fully understand how to implement the technical solutions disclosed herein based on the above description.

[0050] While specific embodiments of the present invention have been described in detail by way of examples, those skilled in the art should understand that the above examples are for illustrative purposes only and are not intended to limit the scope of the invention. Those skilled in the art should understand that modifications can be made to the above embodiments or equivalent substitutions can be made to some technical features without departing from the scope and spirit of the invention. In particular, as long as there is no structural conflict, the various technical features mentioned in the embodiments can be combined in any manner.

Claims

1. A method for preparing high-purity vanadium pentoxide by dissolving and removing impurities from ammonium vanadate, characterized in that, include: A vanadium-containing intermediate is added to a magnesium salt-carbonate composite reaction system to obtain a vanadium-containing return solution. A purification agent is added to the vanadium-containing return solution to obtain a vanadium-containing purified solution. A complexing agent and an ammonium salt are added to the vanadium-containing purified solution, and the solution is cooled to obtain a vanadium-precipitated product, ammonium metavanadate. The vanadium-precipitated product, ammonium metavanadate, is dried and calcined to obtain vanadium pentoxide.

2. The method for preparing high-purity vanadium pentoxide by dissolving and removing impurities from ammonium vanadate according to claim 1, characterized in that, The vanadium-containing intermediate is selected from ammonium metavanadate and ammonium polyvanadate.

3. The method for preparing high-purity vanadium pentoxide by dissolving and removing impurities from ammonium vanadate according to claim 1, characterized in that, Includes the following steps: Step 1: Add magnesium salt and carbonate to solvent and stir until homogeneous to form the magnesium salt-carbonate composite reaction system; Step 2: Add the vanadium-containing intermediate to the magnesium salt-carbonate composite reaction system, stir evenly, and heat to 75-95°C. React until the vanadium-containing intermediate is completely dissolved to obtain the vanadium-containing return solution. Step 3: Maintain the temperature of the vanadium-containing return solution at 75-95°C and add the impurity removal agent to the vanadium-containing return solution. After reacting for 15-60 minutes, perform solid-liquid separation to obtain the vanadium-containing purified solution and the impurity removal residue. Step 4: Add the complexing agent to the vanadium-containing purification solution, stir evenly, and then add the ammonium salt to form a vanadium-containing solution; Step 5: Cool the vanadium-containing liquid to 5-35°C, stir and react, and then perform solid-liquid separation to obtain the vanadium precipitation product ammonium metavanadate and the vanadium precipitation liquid. Step 6: After drying the vanadium precipitation product ammonium metavanadate, heat it to 500-600°C in an oxidizing atmosphere and calcine it to obtain vanadium pentoxide.

4. The method for preparing high-purity vanadium pentoxide by dissolving and removing impurities from ammonium vanadate according to claim 3, characterized in that, In step 1, the magnesium salt is selected from at least one of magnesium oxide, magnesium hydroxide, and magnesium chloride, and the amount of magnesium salt added is 0.5 to 4 g / L based on the solvent volume.

5. The method for preparing high-purity vanadium pentoxide by dissolving and removing impurities from ammonium vanadate according to claim 4, characterized in that, In step 1, the carbonate is selected from at least one of ammonium carbonate and ammonium bicarbonate, and the amount of carbonate added is 25-40 g / L based on the volume of the solvent. The solvent is deionized water or distilled water.

6. The method for preparing high-purity vanadium pentoxide by dissolving and removing impurities from ammonium vanadate according to claim 3, characterized in that, In step 3, the impurity remover is selected from at least one of aluminum sulfate, aluminum chloride, ferric sulfate, and ferric chloride, and the amount of the impurity remover added is 0.1 to 1 g / L based on the volume of the vanadium-containing return solution.

7. The method for preparing high-purity vanadium pentoxide by dissolving and removing impurities from ammonium vanadate according to claim 3, characterized in that, In step 4, the complexing agent is selected from at least one of ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, and hydroxyethylethylenediaminetriacetic acid; based on the volume of the vanadium-containing purified liquid, the amount of complexing agent added is 0.1 to 0.5 g / L.

8. The method for preparing high-purity vanadium pentoxide by dissolving and removing impurities from ammonium vanadate according to claim 3, characterized in that, In step 4, the ammonium salt is selected from at least one of ammonium carbonate and ammonium bicarbonate, and the amount of ammonium salt added is 8-12 g / L based on the volume of the vanadium-containing purified liquid.

9. The method for preparing high-purity vanadium pentoxide by dissolving and removing impurities from ammonium vanadate according to claim 3, characterized in that, In step 5, the stirring reaction time is 6 to 7 hours.

10. The method for preparing high-purity vanadium pentoxide by dissolving and removing impurities from ammonium vanadate according to claim 3, characterized in that, In step 6, the oxidizing atmosphere is an air atmosphere or an oxygen atmosphere, and the heat preservation and calcination time is 2 to 3 hours.

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