Purification method for preparing high-purity vanadium pentoxide from vanadate crude product

Abstract

The invention discloses a purification method for preparing high-purity vanadium pentoxide from a vanadate crude product, which comprises the following steps: adding the vanadate crude product into an acid leaching agent, stirring, dissolving and filtering to obtain an acid solution; mixing an extraction agent with a diluent to obtain an extraction agent solution; extracting vanadium in the acid solution by using an extracting agent solution to obtain a vanadium-containing loaded organic phase, washing the vanadium-containing loaded organic phase, carrying out reverse extraction to obtain a vanadium-containing reverse extraction solution and a reverse extraction organic phase, and regenerating the organic phase; ammonium vanadate is prepared from the vanadium-containing strip liquor through an ammonium salt precipitation method, and high-purity vanadium pentoxide is obtained through thermal decomposition. According to the method, the vanadate crude product serves as the raw material, high-purity vanadium pentoxide is efficiently prepared in a short process, the economic value of the vanadium product is remarkably improved, and the method has the technological advantages of being high in extraction efficiency, high in extraction rate, large in saturation capacity, easy to mechanically automation, environmentally friendly, green and the like.

Description

Technical Field

[0001] This invention relates to the field of separation and purification technology, and in particular to a purification method for preparing high-purity vanadium pentoxide from crude vanadate. Background Technology

[0002] High-purity vanadium metal is widely used in high-end technologies and emerging industries, such as superconducting materials, the electronics industry, and thin-film coatings. Its stable supply is a cornerstone for ensuring the development of modern industry in my country. High-purity vanadium pentoxide is an important raw material for producing high-purity vanadium metal. Precipitation is currently the mainstream process for producing vanadium pentoxide, but the purity of the product obtained is relatively low, failing to meet the raw material standards for producing high-purity vanadium metal. Therefore, it is necessary to propose a short-process method for producing high-purity vanadium pentoxide using crude vanadate as raw material, aiming to improve the economic value of vanadium products and simultaneously ensure a stable supply of raw materials for the production of high-purity vanadium metal.

[0003] To address the above issues, patent CN120646908A discloses a process for extracting high-purity vanadium pentoxide from ammonium polyvanadate, specifically including sodium hydroxide dissolution, pH adjustment, gradient impurity removal, precision filtration, and freezing. The process involves steps such as thawing circulation, high-purity water washing, centrifugal dehydration, and two-stage ignition, utilizing a gradient of magnesium chloride and calcium chloride for impurity removal, and precision filtration using ceramic membranes and high-density polyethylene filter tubes, followed by freezing. Thawing and cycling methods significantly improve the purity of vanadium products, but the process is complex and energy-intensive. Patent CN120717510A discloses a method for preparing high-purity vanadium oxide electrodes. The method involves pretreatment using an activated alumina adsorption column, followed by primary impurity removal using a composite impurity remover with modified lignin sulfonate as the main agent, secondary impurity removal using calcium hydroxide suspension and flocculant, purification of the secondary impurity filtrate using an ion exchange column, and finally ammonium salt precipitation followed by calcination to obtain high-purity vanadium pentoxide. This process requires a large amount of reagents and generates a significant amount of precipitated waste. Summary of the Invention

[0004] The present invention aims to at least partially solve one of the technical problems in the related art.

[0005] Therefore, embodiments of the present invention propose a purification method for preparing high-purity vanadium pentoxide from crude vanadate.

[0006] This invention proposes a purification method for preparing high-purity vanadium pentoxide from crude vanadate, comprising the following steps: S1: Add crude vanadate to the acid leaching agent, stir to dissolve and filter to obtain an acid solution; S2: Mix the extractant with the diluent to obtain an extractant solution; S3: The vanadium in the acid solution is extracted using the extractant solution to obtain a vanadium-loaded organic phase. The vanadium-loaded organic phase is washed and back-extracted to obtain a vanadium-loaded back-extractant and a back-extracted organic phase. The organic phase is then regenerated. S4: Ammonium vanadate is prepared from the vanadium-containing back-extraction solution by ammonium salt precipitation and then thermally decomposed to obtain high-purity vanadium pentoxide.

[0007] Furthermore, in step S1, 300-800g of acid leaching agent is added for every 10g of the crude vanadate product.

[0008] Furthermore, in step S1, the acid leaching agent is a hydrochloric acid solution with a mass concentration of 8% to 30%.

[0009] Furthermore, in step S1, the stirring and dissolving process involves stirring at a dissolution temperature of 3-95°C for 0.5-5 hours.

[0010] Furthermore, the crude vanadate product includes one or more of ammonium metavanadate, ammonium vanadate, ammonium polyvanadate, sodium metavanadate, sodium vanadate, sodium polyvanadate, calcium vanadate, and magnesium vanadate.

[0011] Furthermore, the extractant accounts for 3% to 90% of the mass, and the diluent accounts for 10% to 97% of the mass.

[0012] Furthermore, the extractant is divided into amide extractant and neutral phosphorus oxychloride extractant, wherein the amide extractant is one or more of monodentate amide extractant, bidentate amide extractant, and tridentate amide extractant, and the neutral phosphorus oxychloride extractant includes one or more of trialkyl phosphate extractant, dialkyl phosphonate extractant, dialkyl alkyl phosphonate extractant, and trialkylphosphine oxide extractant; the diluent is a low water-soluble inert organic compound, which includes at least one of sulfonated commercial solvent oil, halogenated hydrocarbon compounds, and aromatic compounds.

[0013] Furthermore, in step S3, the extraction temperature is 15–85°C, the O / A ratio is 0.5–15, the extraction time is 1–80 min, the extraction method is countercurrent extraction, fractional extraction, or cross-current extraction, and the number of extraction stages is 1–15.

[0014] Furthermore, in step S3, the vanadium-supported organic phase is washed with a high-purity hydrochloric acid solution, the mass concentration of which is 3% to 20%.

[0015] Furthermore, in step S3, the washing temperature is 15–85°C, the washing ratio O / A is 1–10, the washing time is 1–80 min, the washing method is countercurrent washing, fractional washing, or cross-flow washing, and the number of washing stages is 1–15.

[0016] Further, in step S3, the back-extraction is performed by back-extracting the washed vanadium-containing supported organic phase using a back-extracting agent. The pH of the back-extracting agent solution is 7-13, the back-extraction temperature is 15-95℃, the O / A ratio of the back-extraction phase is 0.5-20, the back-extraction time is 1-80 min, and the back-extraction method is countercurrent back-extraction, fractional back-extraction, or cross-current back-extraction. The number of back-extraction stages is 1-15.

[0017] Furthermore, the back-extraction agent includes one or more of high-purity water, superior-grade ammonia water, superior-grade ammonium carbonate, and superior-grade ammonium bicarbonate solution.

[0018] Further, in step S3, the organic phase is regenerated by using hydrochloric acid solution to back-extract the organic phase after back-extraction. The mass concentration of the hydrochloric acid solution is 3% to 18%, the regeneration temperature is 15 to 65°C, the regeneration ratio O / A is 1 to 15, the regeneration time is 1 to 45 min, and the regeneration method is countercurrent regeneration, fractional regeneration, or cross-flow regeneration. The number of regeneration stages is 1 to 15.

[0019] Furthermore, in step S4, the pyrolysis is performed at 450–600°C for 0.5–5 hours.

[0020] Furthermore, the ammonium salt used in the ammonium salt precipitation method in step S4 is one or more of the following: high-purity ammonia, high-purity ammonium carbonate, and high-purity ammonium bicarbonate.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention uses crude vanadate as raw material to produce high-purity vanadium pentoxide in a short and efficient process, which significantly improves the economic value of vanadium products. It has the advantages of high extraction efficiency, fast extraction rate, large saturation capacity, easy mechanical automation, and environmental friendliness. Attached Figure Description

[0022] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein: Figure 1 This is a flowchart of the purification method for preparing high-purity vanadium pentoxide from crude vanadate of the present invention; Figure 2 This is a schematic diagram of the structural formulas of the monodentate amide extractant, bidentate amide extractant, and tridentate amide extractant of the present invention; Figure 3 This is a schematic diagram of the structural formulas of the trialkyl phosphate extractant, dialkyl phosphonate extractant, dialkyl alkyl phosphonate extractant, and trialkylphosphine oxide extractant of the present invention. Figure 4 The structural formula of the neutral phosphorus oxygen extractant in Example 1 is shown below; Figure 5 The structural formula of the amide extractant in Example 3 is shown below; Figure 6 The structural formula of the amide extractant in Example 4 is shown below; Figure 7 The structural formula of the neutral phosphorus oxygen extractant in Example 4 is shown below; Figure 8 The structural formula of the amide extractant in Example 5 is shown below; Figure 9 The structural formulas of the two neutral phosphorus oxygen extractants in Example 6 are shown below; Figure 10 The structural formula of the amide extractant in Example 7 is shown below; Figure 11 The images show the infrared spectra of the organic phases before and after extraction in Example 2. Figure 12 The XRD patterns are of the crude ammonium vanadate and the prepared vanadium pentoxide from Example 4. Detailed Implementation

[0023] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0024] This invention proposes a purification method for preparing high-purity vanadium pentoxide from crude vanadate using crude vanadate as raw material, comprising the following steps: S1: Add crude vanadate to the acid leaching agent, stir to dissolve and filter to obtain an acid solution; S2: Mix the extractant with the diluent to obtain an extractant solution; S3: Vanadium in an acidic solution is extracted using an extractant solution to obtain a vanadium-loaded organic phase. The vanadium-loaded organic phase is washed and back-extracted to obtain a vanadium-loaded back-extractant and the back-extracted organic phase. The organic phase is then regenerated. S4: Ammonium vanadate is prepared from vanadium-containing back-extraction solution by ammonium salt precipitation and then thermally decomposed to obtain high-purity vanadium pentoxide.

[0025] In step S1, the crude vanadate product includes one or more of the following: ammonium metavanadate, ammonium vanadate, ammonium polyvanadate, sodium metavanadate, sodium vanadate, sodium polyvanadate, calcium vanadate, and magnesium vanadate.

[0026] In step S1, the acid leaching agent is a hydrochloric acid solution with a mass concentration of 8% to 30%, and the amount of hydrochloric acid used is 300 to 800 g per 10 g of vanadate. It can be understood that the mass concentration of the hydrochloric acid solution can be 8%, 10%, 15%, 20%, 25%, 30%, or any combination of two values. The amount of hydrochloric acid used per 10 g of vanadate is 300, 500, 600, 800, or any combination of two values.

[0027] In step S1, the stirring and dissolving process involves stirring at a dissolution temperature of 3~95℃ for 0.5~5 hours, followed by filtration to obtain an acid solution.

[0028] In step S2, the extractant accounts for 3% to 90% of the total mass, and the diluent accounts for 10% to 97%. The extractant is classified into amide extractants and neutral phosphorus-oxygen extractants. The amide extractant is one or more of monodentate amide, bidentate amide, and tridentate amide extractants. The structural formulas of monodentate amide, bidentate amide, and tridentate amide extractants are as follows: Figure 2 As shown in Formulas 1, 2, and 3, the substituents in Formulas 1, 2, and 3 are one or more of alkyl, aromatic, heteroatom-containing alkyl, and heteroaromatic groups. Neutral phosphorus oxyphosphate extractants include one or more of trialkyl phosphate extractants, dialkyl phosphonate extractants, dialkyl alkyl phosphonate extractants, and trialkylphosphine oxyphosphate extractants. The structural formulas of trialkyl phosphate extractants, dialkyl phosphonate extractants, dialkyl alkyl phosphonate extractants, and trialkylphosphine oxyphosphate extractants are shown below. Figure 3 As shown in Formulas 4, 5, 6, and 7, the substituent alkyl groups in Formulas 4, 5, 6, and 7 can be the same alkyl group or different alkyl groups, and the number of carbon atoms in the alkyl group is 1 to 20.

[0029] The diluent is a low-water-soluble inert organic compound, which includes at least one of sulfonated commercial solvent oils and halogenated hydrocarbon compounds. Sulfonated commercial solvent oils include D60, D80, No. 3 white oil, No. 5 white oil, Solvesso 150 (high-boiling-point aromatic solvent), and Solvesso 200 (high-purity aromatic solvent); halogenated hydrocarbon compounds include chlorinated hydrocarbons, bromine hydrocarbons, or iodinated hydrocarbons; aromatic compounds include monobenzene aromatics and polycyclic aromatic hydrocarbons. D60 solvent oil is a commonly used organic solvent composed of a mixture of short-chain alkanes; solvent oil D80 is a light petroleum fraction with a distillation range of around 80°C, mainly composed of C6-C10 alkanes, cycloalkanes, and a small amount of aromatic hydrocarbons.

[0030] In step S3, when extracting vanadium from the acid solution using the extractant solution, the extraction temperature is 15–85℃, the O / A ratio is 0.5–15, the extraction time is 1–80 min, the extraction method is countercurrent extraction, fractional extraction or cross-current extraction, and the number of extraction stages is 1–15. The extraction yields a vanadium-loaded organic phase and raffinate.

[0031] The vanadium-supported organic phase was washed with a superior purity hydrochloric acid solution. The mass percentage of HCl in the hydrochloric acid solution was 3%–20%, the washing temperature was 15–85℃, the washing ratio of O / A was 1–10, the washing time was 1–80 min, and the washing method was countercurrent washing, fractional washing, or cross-flow washing. The number of washing stages was 1–15, resulting in the washed vanadium-supported organic phase.

[0032] In step S3, back-extraction involves using a back-extraction agent to back-extract the washed vanadium-containing supported organic phase. The pH of the back-extraction agent solution is 7–13, the back-extraction temperature is 15–95℃, the O / A ratio in the back-extraction phase is 0.5–20, the back-extraction time is 1–80 min, and the back-extraction method is countercurrent back-extraction, fractional back-extraction, or cross-current back-extraction. The number of back-extraction stages is 1–15, yielding a high-purity vanadium-containing solution and the back-extracted organic phase. The back-extraction agent includes one or more of high-purity water, analytical grade ammonia, analytical grade ammonium carbonate, and analytical grade ammonium bicarbonate solutions.

[0033] In step S3, the organic phase is regenerated by using hydrochloric acid solution to back-extract the organic phase. The mass concentration of the hydrochloric acid solution is 3% to 18%, the regeneration temperature is 15 to 65°C, the regeneration ratio O / A is 1 to 15, the regeneration time is 1 to 45 min, and the regeneration method is countercurrent regeneration, fractional regeneration, or cross-current regeneration. The number of regeneration stages is 1 to 15. The regenerated organic phase obtained is recycled during the extraction process.

[0034] In step S4, ammonium vanadate is prepared from the vanadium-containing back-extraction solution using an ammonium salt precipitation method. After filtration and drying, it is thermally decomposed at 450–600℃ for 0.5–5 hours to obtain high-purity vanadium pentoxide. The ammonium salt used in the ammonium salt precipitation method is one or more of the following: superior grade ammonia, superior grade ammonium carbonate, and superior grade ammonium bicarbonate.

[0035] The present invention will now be described in detail with reference to specific embodiments.

[0036] Example 1 (1) Dissolution of crude ammonium vanadate: Weigh out crude ammonium vanadate, use hydrochloric acid solution as acid leaching agent, add 650g of hydrochloric acid solution per 10g of ammonium vanadate, the mass percentage of HCl in the hydrochloric acid solution is 25%, the dissolution temperature is 25℃, the stirring time is 3.5h, stir to dissolve and filter to obtain acid solution; (2) Preparation of the extractant solution: The extractant solution is composed of a mixture of extractant and diluent. The extractant is a neutral phosphorus-oxygen extractant, and its structural formula is as follows: Figure 4 As shown, the diluent is D80, the extractant has a mass ratio of 55%, and the diluent has a mass ratio of 45%. The two are thoroughly mixed to prepare an extractant solution. (3) Extracting acid solution: Take the extractant solution in step (2) to extract the acid solution in step (1). The extraction temperature is 35℃, the phase O / A ratio is 8, the time is 20min, the extraction method is fractional extraction, the extraction stage is 10 stages, and vanadium-loaded organic phase and raffinate are obtained. (4) Washing the vanadium-loaded organic phase: Wash the vanadium-loaded organic phase obtained in step (3) with high-purity hydrochloric acid solution. The mass ratio of HCl in the hydrochloric acid solution is 10%, the washing temperature is 20℃, the washing ratio of O / A is 7, the washing time is 55min, the washing method is cross-flow washing, and the washing stage is 6.5 stages to obtain the washed vanadium-loaded organic phase. (5) Back-extraction of vanadium-loaded organic phase: Back-extract the washed vanadium-loaded organic phase obtained in step (4) using a back-extracting agent. The back-extracting agent solution is a super-pure ammonia solution with a pH of 12, a back-extraction temperature of 75°C, a back-extraction phase O / A ratio of 4, a back-extraction time of 60 min, a back-extraction method of fractional back-extraction, and a back-extraction stage of 10 stages to obtain a high-purity vanadium-loaded solution and a back-extracted organic phase. (6) Preparation of high-purity vanadium pentoxide: using high-grade pure ammonia water as a precipitant, ammonium vanadate was prepared from vanadium-containing back-extraction solution by ammonium salt precipitation method. After filtration and drying, high-purity vanadium pentoxide was prepared by thermal decomposition at 550℃ for 2 hours with a purity of 99.72%.

[0037] (7) Recycle the organic phase: Take the organic phase obtained after back-extraction in the hydrochloric acid solution regeneration step (6), the HCl mass ratio in the hydrochloric acid solution is 15%, the regeneration temperature is 15℃, the regeneration phase O / A ratio is 3.5, the regeneration time is 30min, the regeneration method is countercurrent regeneration, the regeneration stage is 8 stages, and the regenerated organic phase is recycled in step (3).

[0038] Example 2 (1) Dissolution of crude vanadate: Weigh out crude ammonium polyvanadate, use hydrochloric acid solution as acid leaching agent, add 800g of hydrochloric acid solution per 10g of ammonium polyvanadate, the mass ratio of HCl in the hydrochloric acid solution is 10%, the dissolution temperature is 85℃, the stirring time is 2.5h, stir to dissolve and filter to obtain acid solution; (2) Preparation of extractant solution: The extractant solution is composed of a mixture of extractant and diluent. The extractant is a neutral phosphorus oxygen extractant TRPO, and the diluent is 1-chlorooctane. The mass ratio of the extractant is 30%, and the mass ratio of the diluent is 70%. The two are thoroughly mixed to prepare the extractant solution. (3) Extraction of acid solution: Take the extractant solution from step (2) to extract the acid solution from step (1). The extraction temperature is 70℃, the ratio of O / A is 6, the extraction time is 50 min, the extraction method is countercurrent extraction, and the extraction stage is 12 stages. The vanadium-loaded organic phase and raffinate are obtained. The infrared spectra of the organic phase before and after extraction are shown in the figure. Figure 11 As shown; (4) Washing the vanadium-loaded organic phase: Wash the vanadium-loaded organic phase obtained in step (3) with high-purity hydrochloric acid solution. The mass percentage of HCl in the hydrochloric acid solution is 15%, the washing temperature is 25℃, the washing ratio of O / A is 9, the washing time is 45min, the washing method is fractional washing, and the number of washing stages is 12. The washed vanadium-loaded organic phase is obtained. (5) Back-extraction of vanadium-loaded organic phase: Back-extract the washed vanadium-loaded organic phase obtained in step (4) using a back-extractant. The back-extractant solution is a high-purity ammonium carbonate solution with a pH of 11, a back-extraction temperature of 65℃, a back-extraction phase O / A ratio of 0.5, a back-extraction time of 5 min, a countercurrent back-extraction method, and a back-extraction stage of 3 stages to obtain a high-purity vanadium-loaded solution and a back-extracted organic phase. (6) Preparation of high-purity vanadium pentoxide: using high-purity ammonium carbonate as a precipitant, ammonium vanadate was prepared from vanadium-containing back-extraction solution by ammonium salt precipitation method. After filtration and drying, high-purity vanadium pentoxide was prepared by thermal decomposition at 480℃ for 1 h with a purity of 99.68%.

[0039] (7) Recycle the organic phase: Take the organic phase obtained after back-extraction in the hydrochloric acid solution regeneration step (6), the HCl mass ratio in the hydrochloric acid solution is 5%, the regeneration temperature is 25℃, the regeneration ratio O / A is 10, the regeneration time is 20min, the regeneration method is fractional regeneration, the regeneration stage is 5 stages, and the regenerated organic phase obtained is recycled in step (3).

[0040] Example 3 (1) Dissolution of crude sodium vanadate: Weigh out crude sodium vanadate, use hydrochloric acid solution as acid leaching agent, add 500g of hydrochloric acid solution per 10g sodium vanadate, the mass ratio of HCl in the hydrochloric acid solution is 15%, the dissolution temperature is 75℃, the stirring time is 0.5h, stir to dissolve and filter to obtain acid solution; (2) Preparation of the extractant solution: The extractant solution is composed of a mixture of extractant and diluent. The extractant is an amide extractant, and its structural formula is as follows: Figure 5 As shown, the diluent is toluene, the extractant has a mass ratio of 80%, and the diluent has a mass ratio of 20%. The two are thoroughly mixed to prepare an extractant solution. (3) Extracting acid solution: Take the extractant solution from step (2) to extract the acid solution from step (1). The extraction temperature is 25℃, the ratio of O / A is 2, the time is 5min, the extraction method is cross-flow extraction, and the extraction stage is 5 stages to obtain vanadium-loaded organic phase and raffinate. (4) Washing the vanadium-loaded organic phase: Wash the vanadium-loaded organic phase obtained in step (3) with high-purity hydrochloric acid solution. The mass percentage of HCl in the hydrochloric acid solution is 15%, the washing temperature is 75℃, the washing ratio of O / A is 4, the washing time is 10min, the washing method is fractional washing, and the washing stage is 5 stages to obtain the washed vanadium-loaded organic phase. (5) Back-extraction of vanadium-loaded organic phase: Back-extract the washed vanadium-loaded organic phase obtained in step (4) using a back-extracting agent. The back-extracting agent solution is a super-pure ammonia solution with a pH of 12, a back-extraction temperature of 75°C, a back-extraction phase O / A ratio of 10, a back-extraction time of 75 min, a back-extraction method of fractional back-extraction, and a back-extraction stage of 6 stages to obtain a high-purity vanadium-containing solution and a back-extracted organic phase. (6) Preparation of high-purity vanadium pentoxide: using high-purity ammonium bicarbonate as a precipitant, ammonium vanadate was prepared from vanadium-containing back-extraction solution by ammonium salt precipitation method. After filtration and drying, high-purity vanadium pentoxide was prepared by thermal decomposition at 550℃ for 3h with a purity of 99.91%.

[0041] (7) Recycle the organic phase: Take the organic phase obtained after back-extraction in the hydrochloric acid solution regeneration step (6), the HCl mass ratio in the hydrochloric acid solution is 16%, the regeneration temperature is 65℃, the regeneration ratio O / A is 10, the regeneration time is 15min, the regeneration method is cross-flow regeneration, the regeneration stage is 4 stages, and the regenerated organic phase obtained is recycled in step (3).

[0042] Example 4 (1) Dissolution of crude vanadate: Weigh out crude calcium vanadate, use hydrochloric acid solution as acid leaching agent, add 400g of hydrochloric acid solution per 10g of calcium vanadate, the mass ratio of HCl in the hydrochloric acid solution is 20%, the dissolution temperature is 75℃, the stirring time is 2h, after stirring to dissolve and filtering, the acid solution is obtained. (2) Preparation of the extractant solution: The extractant solution is composed of a mixture of extractant and diluent, wherein the extractant is an amide extractant (its structural formula is as follows). Figure 6 (as shown) and neutral phosphorus oxygen extractant (its structural formula is shown) Figure 7 The mixture (shown) is a mixture in which the diluent is 5# white oil, the extractant has a mass ratio of 65%, and the diluent has a mass ratio of 35%. The two are thoroughly mixed to form an extractant solution. (3) Extracting acid solution: Take the extractant solution in step (2) to extract the acid solution in step (1). The extraction temperature is 45℃, the ratio of O / A is 10, the time is 55min, the extraction method is fractional extraction, the number of extraction stages is 10, and the vanadium-loaded organic phase and raffinate are obtained. (4) Washing the vanadium-loaded organic phase: Wash the vanadium-loaded organic phase obtained in step (3) with high-purity hydrochloric acid solution. The mass ratio of HCl in the hydrochloric acid solution is 10%, the washing temperature is 70℃, the washing ratio of O / A is 2, the washing time is 4min, the washing method is cross-flow washing, and the washing stage is 3 stages to obtain the washed vanadium-loaded organic phase. (5) Back-extraction of vanadium-loaded organic phase: Back-extract the washed vanadium-loaded organic phase obtained in step (4) using a back-extracting agent. The back-extracting agent solution is a mixed solution of high-purity ammonium carbonate and high-purity ammonium bicarbonate. The pH of the back-extracting agent solution is 12.5, the back-extraction temperature is 80℃, the back-extraction phase O / A ratio is 4, the back-extraction time is 65min, the back-extraction method is fractional back-extraction, and the number of back-extraction stages is 10, to obtain a high-purity vanadium-loaded solution and the back-extracted organic phase. (6) Preparation of high-purity vanadium pentoxide: Using a mixture of superior-grade ammonium carbonate and superior-grade ammonium bicarbonate as a precipitant, ammonium vanadate was prepared from the vanadium-containing back-extraction solution by ammonium salt precipitation. After filtration and drying, high-purity vanadium pentoxide was prepared by thermal decomposition at 500℃ for 2 hours, with a purity of 99.58%. The XRD patterns of ammonium vanadate and vanadium pentoxide are shown below. Figure 12 As shown.

[0043] (7) Recycle the organic phase: Take the organic phase obtained after back-extraction in the hydrochloric acid solution regeneration step (6), the HCl mass ratio in the hydrochloric acid solution is 10%, the regeneration temperature is 35℃, the regeneration ratio O / A is 6, the regeneration time is 5min, the regeneration method is fractional regeneration, the number of regeneration stages is 12, and the regenerated organic phase obtained is recycled in step (3).

[0044] Example 5 (1) Dissolution of crude magnesium vanadate: Weigh out crude magnesium vanadate, use hydrochloric acid solution as acid leaching agent, add 350g of hydrochloric acid solution per 10g magnesium vanadate, the mass percentage of HCl in the hydrochloric acid solution is 22%, the dissolution temperature is 55℃, the stirring time is 2.5h, stir to dissolve and filter to obtain acid solution; (2) Preparation of the extractant solution: The extractant solution is composed of a mixture of extractant and diluent. The extractant is an amide extractant, and its structural formula is as follows: Figure 8 As shown, the diluent is a mixture of No. 3 white oil and Solvesso 150, with the extractant accounting for 15% by mass and the diluent accounting for 85% by mass. The two are thoroughly mixed to prepare an extractant solution. (3) Extracting acid solution: Take the extractant solution in step (2) to extract the acid solution in step (1). The extraction temperature is 50℃, the phase O / A ratio is 8, the time is 10min, the extraction method is countercurrent extraction, and the extraction stage is 8 stages to obtain vanadium-loaded organic phase and raffinate. (4) Washing the vanadium-loaded organic phase: Wash the vanadium-loaded organic phase obtained in step (3) with high-purity hydrochloric acid solution. The mass ratio of HCl in the hydrochloric acid solution is 10%, the washing temperature is 20℃, the washing ratio of O / A is 3, the washing time is 10min, the washing method is cross-flow washing, and the washing stage is 3 stages to obtain the washed vanadium-loaded organic phase. (5) Back-extraction of vanadium-loaded organic phase: Back-extract the washed vanadium-loaded organic phase obtained in step (4) using a back-extractant solution of high-purity water, a back-extraction temperature of 95℃, a back-extraction phase O / A ratio of 3, a back-extraction time of 60 min, a cross-flow back-extraction method, and a back-extraction stage of 3 stages to obtain a high-purity vanadium-containing solution and a back-extracted organic phase; (6) Preparation of high-purity vanadium pentoxide: using high-purity ammonium carbonate as a precipitant, ammonium vanadate was prepared from vanadium-containing back-extraction solution by ammonium salt precipitation method. After filtration and drying, high-purity vanadium pentoxide was prepared by thermal decomposition at 600℃ for 3.5h with a purity of 99.69%.

[0045] (7) Recycle the organic phase: Take the organic phase obtained after back-extraction in the hydrochloric acid solution regeneration step (6), the HCl mass ratio in the hydrochloric acid solution is 14%, the regeneration temperature is 55℃, the regeneration phase O / A ratio is 6.5, the regeneration time is 40min, the regeneration method is fractional regeneration, the regeneration stage is 12 stages, and the regenerated organic phase is recycled in step (3).

[0046] Example 6 (1) Dissolution of crude vanadate: Weigh out crude ammonium metavanadate, use hydrochloric acid solution as acid leaching agent, add 650g of hydrochloric acid solution per 10g of ammonium metavanadate, the mass percentage of HCl in the hydrochloric acid solution is 15%, the dissolution temperature is 15℃, the stirring time is 4h, after stirring to dissolve and filtering, the acid solution is obtained. (2) Preparation of the extractant solution: The extractant solution is composed of a mixture of extractant and diluent. The extractant is a mixture of two different types of neutral phosphorus-oxygen extractants, and their structural formulas are as follows: Figure 9 (a) and Figure 9 As shown in (b), the diluent is hexadecane chloro, the extractant has a mass ratio of 70%, the diluent has a mass ratio of 30%, and the two are thoroughly mixed to prepare an extractant solution; (3) Extracting acid solution: Take the extractant solution in step (2) to extract the acid solution in step (1). The extraction temperature is 20℃, the ratio of O / A is 12, the time is 50min, the extraction method is cross-flow extraction, the extraction stage is 3 stages, and vanadium-loaded organic phase and raffinate are obtained. (4) Washing the vanadium-loaded organic phase: Wash the vanadium-loaded organic phase obtained in step (3) with high-purity hydrochloric acid solution. The mass percentage of HCl in the hydrochloric acid solution is 5%, the washing temperature is 25℃, the washing phase O / A ratio is 5.5, the washing time is 60min, the washing method is countercurrent washing, and the washing stage is 6 stages to obtain the washed vanadium-loaded organic phase. (5) Back-extraction of vanadium-loaded organic phase: Back-extract the washed vanadium-loaded organic phase obtained in step (4) using a back-extractant. The back-extractant solution is a high-purity ammonium bicarbonate solution with a pH of 10.5, a back-extraction temperature of 45℃, a back-extraction ratio of O / A of 10, a back-extraction time of 70 min, a cross-flow back-extraction method, and a back-extraction stage of 6 stages to obtain a high-purity vanadium-loaded solution and a back-extracted organic phase. (6) Preparation of high-purity vanadium pentoxide: using high-purity ammonium carbonate as a precipitant, ammonium vanadate was prepared from vanadium-containing back-extraction solution by ammonium salt precipitation method. After filtration and drying, high-purity vanadium pentoxide was prepared by thermal decomposition at 460℃ for 1 h with a purity of 99.84%.

[0047] (7) Recycle the organic phase: Take the organic phase obtained after back-extraction in the hydrochloric acid solution regeneration step (6), the HCl mass ratio in the hydrochloric acid solution is 18%, the regeneration temperature is 55℃, the O / A ratio in the regeneration phase is 9, the regeneration time is 40min, the regeneration method is fractional regeneration, the number of regeneration stages is 3, and the regenerated organic phase obtained is recycled in step (3).

[0048] Example 7 (1) Dissolution of crude vanadate: Weigh out crude sodium metavanadate and magnesium vanadate, use hydrochloric acid solution as acid leaching agent, add 500g of hydrochloric acid solution of 10g mixed sodium metavanadate and magnesium vanadate, the mass ratio of HCl in the hydrochloric acid solution is 20%, the dissolution temperature is 45℃, the stirring time is 1h, and after stirring to dissolve and filtering, the acid solution is obtained. (2) Preparation of the extractant solution: The extractant solution is composed of a mixture of extractant and diluent. The extractant is an amide extractant, and its structural formula is as follows: Figure 10 As shown, the diluent is Solvesso 200, the extractant has a mass ratio of 60%, and the diluent has a mass ratio of 40%. The two are thoroughly mixed to prepare an extractant solution. (3) Extracting acid solution: Take the extractant solution in step (2) to extract the acid solution in step (1). The extraction temperature is 55℃, the ratio O / A is 1, the time is 12min, the extraction method is countercurrent extraction, and the extraction stage is 10 stages to obtain vanadium-loaded organic phase and raffinate. (4) Washing the vanadium-loaded organic phase: Wash the vanadium-loaded organic phase obtained in step (3) with high-purity hydrochloric acid solution. The mass ratio of HCl in the hydrochloric acid solution is 18%, the washing temperature is 15℃, the washing ratio of O / A is 10, the washing time is 75min, the washing method is cross-flow washing, and the washing stage is 2 stages to obtain the washed vanadium-loaded organic phase. (5) Back-extraction of vanadium-loaded organic phase: Back-extract the washed vanadium-loaded organic phase obtained in step (4) using a back-extractant. The back-extractant solution is a high-purity ammonium carbonate solution with a pH of 11.5, a back-extraction temperature of 45℃, a back-extraction phase O / A ratio of 12, a back-extraction time of 60 min, a countercurrent back-extraction method, and 8 back-extraction stages to obtain a high-purity vanadium-loaded solution and a back-extracted organic phase. (6) Preparation of high-purity vanadium pentoxide: using high-grade pure ammonia water as a precipitant, ammonium vanadate was prepared from vanadium-containing back-extraction solution by ammonium salt precipitation method. After filtration and drying, high-purity vanadium pentoxide was prepared by thermal decomposition at 550℃ for 4.5h with a purity of 99.94%.

[0049] (7) Recycle the organic phase: Take the organic phase obtained after back-extraction in the hydrochloric acid solution regeneration step (6), the HCl mass ratio in the hydrochloric acid solution is 15%, the regeneration temperature is 55℃, the regeneration phase O / A ratio is 1, the regeneration time is 40min, the regeneration method is fractional regeneration, the regeneration stage is 10 stages, and the regenerated organic phase obtained is recycled in step (3).

[0050] Experimental Example 1 Infrared spectroscopy was performed on the organic phases before and after extraction in Example 2. The test results are as follows: Figure 11 As shown. From Figure 11 As can be seen from the data, the absorption peak of the stretching vibration of the phosphorus-oxygen double bond (P=O) before extraction appears at 1168.65 cm⁻¹. -1 After extraction, the absorption peak red-shifted to 1095.37 cm⁻¹. -1 This means that the phosphoxy group participated in the extraction reaction. Compared with the spectrum of the blank extractant solution, the spectrum of the supported organic phase was at 952.67 cm⁻¹. -1 The peak appearing at the point is attributed to the ν (V=O) of the vanadium ion, proving that the extractant reacted with vanadium to form an extract.

[0051] Experimental Example 2 XRD tests were performed on ammonium vanadate and the prepared vanadium pentoxide in Example 4. The test results are as follows: Figure 12 As shown. From Figure 12As can be seen from the comparison with card PDF#01-079-2051, the yellow crystals obtained by drying at 105℃ were identified as ammonium vanadate, with obvious diffraction peaks and high intensity; when the thermal decomposition temperature is 500℃, compared with card PDF#04-002-2453, the thermal decomposition product was identified as V2O5, with obvious diffraction peaks and no impurity peaks, thus the preparation of ammonium vanadate to vanadium pentoxide was achieved through thermal decomposition.

[0052] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms may refer to different embodiments or examples. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0053] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0054] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A purification method for preparing high-purity vanadium pentoxide from crude vanadate, characterized in that, Includes the following steps: S1: Add crude vanadate to the acid leaching agent, stir to dissolve and filter to obtain an acid solution; S2: Mix the extractant with the diluent to obtain an extractant solution; S3: The vanadium in the acid solution is extracted using the extractant solution to obtain a vanadium-loaded organic phase. The vanadium-loaded organic phase is washed and back-extracted to obtain a vanadium-loaded back-extractant and a back-extracted organic phase. The organic phase is then regenerated. S4: Ammonium vanadate is prepared from the vanadium-containing back-extraction solution by ammonium salt precipitation and then thermally decomposed to obtain high-purity vanadium pentoxide.

2. The method as described in claim 1, characterized in that, In step S1, 300-800g of acid leaching agent is added to every 10g of the crude vanadate product; And / or, in step S1, the acid leaching agent is a hydrochloric acid solution with a mass concentration of 8% to 30%; And / or, in step S1, the stirring and dissolving process is carried out at a dissolution temperature of 3~95℃ for 0.5~5 hours; And / or, the crude vanadate product includes one or more of ammonium metavanadate, ammonium vanadate, ammonium polyvanadate, sodium metavanadate, sodium vanadate, sodium polyvanadate, calcium vanadate, and magnesium vanadate.

3. The method as described in claim 1, characterized in that, The extractant has a mass percentage of 3% to 90%, and the diluent has a mass percentage of 10% to 97%.

4. The method as described in claim 1, characterized in that, The extractant is divided into amide extractant and neutral phosphorus oxychloride extractant. The amide extractant is one or more of monodentate amide extractant, bidentate amide extractant, and tridentate amide extractant. The neutral phosphorus oxychloride extractant includes one or more of trialkyl phosphate extractant, dialkyl phosphonate extractant, dialkyl alkyl phosphonate extractant, and trialkylphosphine oxide extractant. The diluent is a low-water-soluble inert organic compound, which includes at least one of sulfonated commercial solvent oil, halogenated hydrocarbon compounds, and aromatic compounds.

5. The method as described in claim 1, characterized in that, In step S3, the extraction temperature is 15–85°C, the O / A ratio is 0.5–15, the extraction time is 1–80 min, the extraction method is countercurrent extraction, fractional extraction, or cross-current extraction, and the number of extraction stages is 1–15.

6. The method as described in claim 1, characterized in that, In step S3, the vanadium-supported organic phase is washed with a high-purity hydrochloric acid solution with a mass concentration of 3% to 20%.

7. The method as described in claim 1, characterized in that, In step S3, the washing temperature is 15–85°C, the washing ratio O / A is 1–10, the washing time is 1–80 min, the washing method is countercurrent washing, fractional washing, or cross-flow washing, and the number of washing stages is 1–15.

8. The method as described in claim 1, characterized in that, In step S3, the back-extraction is performed by back-extracting the washed vanadium-containing supported organic phase using a back-extracting agent. The pH of the back-extracting agent solution is 7–13, the back-extraction temperature is 15–95°C, the O / A ratio of the back-extraction phase is 0.5–20, the back-extraction time is 1–80 min, and the back-extraction method is countercurrent back-extraction, fractional back-extraction, or cross-current back-extraction. The number of back-extraction stages is 1–15. The back-extracting agent includes one or more of high-purity water, superior-grade ammonia water, superior-grade ammonium carbonate, and superior-grade ammonium bicarbonate solution.

9. The method as described in claim 1, characterized in that, In step S3, the organic phase is regenerated by using hydrochloric acid solution to back-extract the organic phase after back-extraction. The mass concentration of the hydrochloric acid solution is 3% to 18%, the regeneration temperature is 15 to 65°C, the regeneration ratio O / A is 1 to 15, the regeneration time is 1 to 45 minutes, and the regeneration method is countercurrent regeneration, fractional regeneration, or cross-flow regeneration. The number of regeneration stages is 1 to 15.

10. The method as described in claim 1, characterized in that, In step S4, the pyrolysis is performed at 450–600°C for 0.5–5 hours. And / or, the ammonium salt used in the ammonium salt precipitation method in step S4 is one or more of the following: high-purity ammonia, high-purity ammonium carbonate, and high-purity ammonium bicarbonate.

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