Method for preparing high-purity vanadium oxide by purifying ammonium vanadate

Abstract

The invention relates to the field of chemical industry, and discloses a method for preparing high-purity vanadium oxide by purifying ammonium vanadate, which comprises the following steps: adding a carbonate solution into ammonium vanadate, stirring, and heating to 75-95 DEG C to obtain a vanadium-containing return solution; keeping the temperature of the vanadium-containing return solution, and adding a calcium salt impurity removal agent to obtain a vanadium-containing purified solution and first-stage impurity removal slag; oxalate is added into the vanadium-containing purified liquid, the temperature of the vanadium liquid is kept, and deeply-purified vanadium liquid and second-stage impurity removal slag are obtained; cooling the deeply purified vanadium liquid to 5-35 DEG C, stirring and reacting, and then carrying out solid-liquid separation to obtain ammonium metavanadate and secondary vanadium precipitation supernatant; adding pure water into the ammonium metavanadate product, pulping, stirring, and heating to 80-95 DEG C to obtain a secondary return solution; the pH of the secondary return solution is adjusted to 1.6-2.0, the temperature is raised to 95-98 DEG C, and ammonium polyvanadate and a third-section vanadium precipitation supernatant are obtained; and drying the ammonium polyvanadate, raising the temperature to 500-600 DEG C in an oxidizing atmosphere, and carrying out heat preservation and calcination to obtain a vanadium pentoxide product. The method can be used for preparing a high-purity vanadium pentoxide product.

Description

Technical Field

[0001] The invention relates to the field of chemical industry, and in particular to a method for purifying ammonium vanadate to prepare high-purity vanadium oxide. Background Art

[0002] High-purity vanadium oxide is the basic raw material for most vanadium chemical products and is widely used in the fields of chemical industry, medical treatment and battery. The main difficulty in the preparation of high-purity vanadium oxide lies in the process of removing impurities. At present, there are three main technical routes for the industrial preparation of high-purity vanadium pentoxide. The most important one is to use crude vanadium such as vanadium pentoxide or industrial-grade vanadate products as raw materials, and obtain it through dissolution, impurity removal and purification, vanadium precipitation and other processes. However, alkaline solution is mainly used for dissolution, and in order to achieve the impurity removal effect, multi-stage alkaline dissolution-precipitation operations are often required. The process flow is long, the reagent consumption is large, and some impurities are difficult to remove in alkaline solutions. Solvent extraction and ion exchange have the advantages of good impurity removal and adsorption effect and high product purity, but the purification cost is relatively high and it is only applicable to low-concentration vanadium solutions.

[0003] In the prior art, the relevant documents for preparing high-purity vanadium oxide are as follows: Patent CN201710339607.6 discloses a method for preparing high-purity ammonium metavanadate of a designated grade of 4N. The method uses industrial-grade ammonium metavanadate as raw material, adopts the process of acid dissolution-extraction purification-strip extraction crystallization to prepare crude vanadium pentoxide, and then alkali dissolution-crystallization of ammonium metavanadate product again. The product purity can reach 4N grade, but it needs to go through a multi-stage dissolution-extraction process, which has a long process, high reagent consumption, high production cost, and is difficult to achieve industrial production.

[0004] Patent CN117623383A discloses a method for preparing high-purity vanadium pentoxide. For the APV product obtained by the calcification vanadium extraction process, a process route of high-temperature dissolution of ammonia water - purification by aluminum salt / calcium salt - deep precipitation of impurities by adjusting the pH with carbon dioxide - precipitation of AMV is adopted. The purity of the final vanadium pentoxide product can reach 99.9%.

[0005] Patent CN116040680A discloses a high-purity ammonium metavanadate and its preparation method. After dissolving vanadium oxide with acid, ammonia water is added to adjust the pH to 7-9. After oxidation, the impurity content in the crystallized ammonium metavanadate product can reach below 30ppm. The process requires acid-base neutralization, and the consumption of reagents is large.

[0006] Patent CN202111589921.2 discloses a method for preparing high-purity vanadium by separating ammonium from ammonium metavanadate raw material vanadium. The AMV raw material containing impurities of cobalt / silicon / chromium / molybdenum is dissolved in acid and then heated to convert it into APV. The impurities are removed during the pickling process, and ammonium is separated from vanadium to reduce the ammonium content in ammonium vanadate. The amount of alkali used when dissolving vanadium can be effectively reduced, and the product can be used as a raw material for vanadium electrolyte.

[0007] Patent CN108217726A discloses a high-purity ammonium vanadate and a preparation method thereof. The pentavalent vanadium liquid is reduced to tetravalent vanadium by adding a reducing agent (sodium sulfite, oxalic acid, etc.), and then the vanadium is extracted to separate the vanadium from the impurities in the organic phase of the vanadium extract. The tetravalent vanadium liquid obtained by back extraction is added to ammonium salt for vanadium precipitation, and finally the product is further purified by two sedimentations to obtain high-purity ammonium vanadate. The purity of the vanadium product can reach 99.7%.

[0008] Patent CN112209441A discloses a method for purifying ammonium metavanadate to prepare high-purity vanadium pentoxide, wherein crude ammonium metavanadate is dissolved in alkali, heated and added to wood cellulose to remove impurities, acid is added to the solution to adjust the pH to precipitate a vanadium-containing filter cake, and finally ammonia water is added to dissolve the vanadium-containing filter cake again, and the temperature is reduced and crystallized to obtain high-purity ammonium metavanadate.

[0009] Patent CN201610740783.6 discloses a method for preparing high-purity vanadium pentoxide, wherein the crude ammonium metavanadate is dissolved, sodium hydroxide and sodium carbonate are added to adjust the pH to 8.5-9.0, magnesium chloride and calcium chloride are added as purifiers to remove impurities, and finally the ammonium metavanadate product is precipitated.

[0010] Patent CN102910676A discloses a method for preparing high-purity vanadium pentoxide. The invention uses red vanadium as raw material, dissolves it with sodium hydroxide, adds a mixture of lanthanum salt and strontium salt to remove impurities, separates impurities such as Fe, Al, Ca, Mg, P, S and As by coprecipitation, and precipitates vanadium again to separate soluble impurity elements such as potassium, sodium and silicon in the purified solution, so as to prepare a high-purity vanadium pentoxide product. However, the lanthanum salt and strontium salt impurity removers used are expensive and costly, and are not suitable for industrial-scale production.

[0011] Patent CN102923775A discloses a method for preparing high-purity vanadium pentoxide. The invention subjects crude vanadium to multi-stage alkaline solution dissolution and acidic vanadium precipitation, thereby achieving the purpose of removing metal cation impurities, and obtaining high-purity vanadium pentoxide with a content of less than 0.001% for various metal cation impurities and a vanadium pentoxide content of 99.99%.

[0012] Patent CN201010606950.0 discloses a method for purifying ammonium metavanadate and a method for preparing high-purity vanadium pentoxide. Crude ammonium metavanadate is dissolved in deionized water at 70 to 100°C, the pH of the solution is adjusted to 8-10, and then water-soluble magnesium salts and / or calcium salts are added to remove anionic impurities. After filtering, the pH value is further adjusted to 10-12 to achieve precipitation of cationic impurities. Finally, more than two stages of precipitation ammonium metavanadate-dissolution-reprecipitation process are performed to remove impurities, thereby preparing a vanadium pentoxide product with a purity of 99.9%.

[0013] Patent CN107298461A discloses a method for purifying ammonium metavanadate and high-purity ammonium metavanadate. The preparation method dissolves industrial-grade ammonium metavanadate in an alkaline solution, removes anionic impurities by vanadium adsorption through an alkaline anion exchange resin, and after impurity removal, contacts with an acidic cation exchange resin again to remove cationic impurities, obtains a purified vanadium-containing solution, precipitates vanadium to obtain primary ammonium metavanadate, and then dissolves, recrystallizes, and washes the primary ammonium metavanadate. The purity of the prepared ammonium metavanadate can reach more than 99.7%.

[0014] Patent CN202111497571.7 discloses a method for preparing high-purity ammonium metavanadate by seed decomposition. After the crude ammonium metavanadate is dissolved in hot water at 50-100°C, ammonia water is added to adjust the pH value to 8-9 for impurity removal. The purified vanadium-containing solution is added with high-purity ultrafine ammonium metavanadate seeds for recrystallization. The purity of the prepared ammonium metavanadate can reach more than 99.7%, and the theoretical recovery rate can reach 100%.

[0015] Patent CN118062893A discloses a method for purifying ammonium metavanadate to prepare high-purity vanadium pentoxide. The industrial-grade ammonium metavanadate raw material is heated and dissolved, and then NaOH is added and allowed to stand and filtered. The pH of the solution is adjusted to 9-10, and an anionic flocculant is first added, and then magnesium sulfate or magnesium chloride is added for purification and impurity removal. The purified liquid adopts a weak alkaline ammonium salt precipitation method to precipitate the ammonium metavanadate.

[0016] Patent CN 201610008559 discloses a method for purifying vanadium pentoxide, wherein crude vanadium pentoxide is reacted with anhydrous aluminum chloride under an inert atmosphere to obtain vanadium oxychloride, and the vanadium oxychloride gas is post-treated to obtain high-purity vanadium pentoxide.

[0017] Analysis of relevant patents related to the preparation of high-purity vanadium oxide shows that the current mainstream process for preparing high-purity vanadium oxide is to use ammonium metavanadate or vanadium pentoxide as raw materials for deep impurity removal, mainly by alkali dissolution-chemical impurity removal, but there are generally problems such as long process flow, complex process, and high consumption of reagents, resulting in high production costs and difficulty in industrial production. Chemical impurity removal is difficult to achieve one-time deep impurity removal, and the types and contents of impurities contained in different vanadium sources are different, resulting in incomplete impurity removal and unstable final product quality. Since the acid leaching solution obtained by the vanadium slag calcification vanadium extraction process has many types of impurities and generally high contents, the main impurities are K, Na, Mn, Ca, Al, Fe, Si, P, etc., which are very different from the types of impurities in other processes. Therefore, there is currently no feasible low-cost, short-process preparation technology for high-purity vanadium oxide products with a purity of more than 99.9%.

[0018] In view of this, the existing technology needs to be improved. Summary of the invention

[0019] In view of this, the purpose of the embodiment of the present invention is to propose a method for purifying ammonium vanadate to prepare high-purity vanadium oxide, which solves the problems of long process flow, complex process, large consumption of reagents, incomplete impurity removal, etc. in the process of preparing high-purity vanadium, and can achieve one-time deep impurity removal to prepare a high-purity vanadium pentoxide product.

[0020] Based on the above purpose, the embodiment of the present invention provides a method for purifying ammonium vanadate to prepare high-purity vanadium oxide, comprising: S1, adding carbonate solution to ammonium vanadate, stirring evenly, heating to 75°C-95°C, reacting for 15-60 minutes, and obtaining a vanadium-containing solution; S2, maintaining the temperature of the vanadium-containing return solution at 75-95°C, adding a calcium salt impurity remover, reacting for 15-60 minutes, and then performing solid-liquid separation to obtain a vanadium-containing purified solution and a first-stage impurity-removing slag; S3, adding oxalate to the vanadium-containing purified liquid, maintaining the temperature of the vanadium liquid at 75-95° C., reacting for 30-90 minutes, and then performing solid-liquid separation to obtain a deeply purified vanadium liquid and a second-stage impurity removal slag; S4, cooling the deep purified vanadium liquid to 5°C-35°C, stirring the reaction, and performing solid-liquid separation to obtain ammonium metavanadate and the second-stage vanadium precipitation upper layer liquid; S5, adding the ammonium metavanadate product to pure water for slurrying, stirring evenly, heating to 80°C-95°C, reacting for 30min-90min, and obtaining a secondary solution; S6, adjusting the pH of the secondary return solution to 1.6-2.0, raising the temperature to 95°C-98°C, reacting for 30min-90min, and then performing solid-liquid separation to obtain ammonium polyvanadate and a three-stage vanadium precipitation upper layer liquid; S7, drying the ammonium polyvanadate, heating it to 500-600°C in an oxidizing atmosphere, and calcining it at the temperature to obtain a vanadium pentoxide product.

[0021] According to one embodiment of the present invention, in step S1, ammonium vanadate is produced by a vanadium slag calcification vanadium extraction process, and the main impurities are Mn, Ca, Al, Fe, Si, P, K, and Na. The content of the main impurities does not exceed 1wt%, and the content of other impurities except the main impurities does not exceed 0.05wt%.

[0022] According to one embodiment of the present invention, in step S1, the carbonate is one or more of ammonium carbonate and ammonium bicarbonate, and the added amount is 10-40 g / L.

[0023] According to one embodiment of the present invention, in step S2, the calcium salt impurity remover is one or more of calcium oxide and calcium hydroxide, and the added amount is 2-10 g / L.

[0024] According to one embodiment of the present invention, in step S3, the oxalate is one or more of oxalic acid, ammonium oxalate, sodium oxalate, and potassium oxalate, and the added amount is 1-5 g / L.

[0025] According to one embodiment of the present invention, in step S1, the liquid-to-solid ratio of ammonium vanadate to carbonate solution is 15-30:1 mL / g.

[0026] According to one embodiment of the present invention, in step S5, the liquid-to-solid ratio of the ammonium metavanadate product to pure water is 15-30:1 mL / g. According to one embodiment of the present invention, in step S4, the stirring reaction time is 180 min-360 min.

[0027] According to one embodiment of the present invention, in step S7, the heat preservation and calcination time is 60 min-150 min.

[0028] According to an embodiment of the present invention, the method further includes: repeating step S1-7, and directly using the upper layer of the second stage vanadium precipitation liquid for the re-dissolution of ammonium vanadate.

[0029] The present invention has at least the following beneficial technical effects: The invention solves the problems of long process flow, complicated process, large reagent consumption, incomplete impurity removal and the like in the process of preparing high-purity vanadium. The invention uses ordinary purity ammonium vanadate as a raw material, adopts chemical impurity removal, and realizes sufficient removal of Mn, Ca, Al, Fe, Si, P, K and Na impurities through two steps of dissolution-impurity removal-precipitation, and prepares a high-purity vanadium oxide product with a purity of more than 99.95%. The invention shortens the process flow, improves the vanadium yield, reduces the reagent consumption, and significantly reduces the production cost of the high-purity vanadium oxide product. The process water can be recycled for multiple times, and the amount of wastewater treatment is significantly reduced. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0031] As required, specific embodiments of the present invention are disclosed in the present specification; however, it should be understood that the embodiments disclosed herein are merely examples of the present invention that can be implemented in multiple, alternative forms. In the following description, multiple operating parameters and components are described in multiple embodiments contemplated. These specific parameters and components are only used as examples in this specification and are not meant to be limiting.

[0032] According to the present invention, a method for purifying ammonium vanadate to prepare high-purity vanadium oxide is provided, which comprises the following steps: S1, adding carbonate solution to ammonium vanadate, stirring evenly, heating to 75°C-95°C, reacting for 15-60 minutes, and obtaining a vanadium-containing solution; S2, maintaining the temperature of the vanadium-containing return solution at 75-95°C, adding a calcium salt impurity remover, reacting for 15-60 minutes, and then performing solid-liquid separation to obtain a vanadium-containing purified solution and a first-stage impurity-removing slag; S3, adding oxalate to the vanadium-containing purified liquid, maintaining the temperature of the vanadium liquid at 75-95° C., reacting for 30-90 minutes, and then performing solid-liquid separation to obtain a deeply purified vanadium liquid and a second-stage impurity removal slag; S4, cooling the deep purified vanadium liquid to 5°C-35°C, stirring the reaction, and performing solid-liquid separation to obtain ammonium metavanadate and the second-stage vanadium precipitation upper layer liquid; S5, adding the ammonium metavanadate product to pure water for slurrying, stirring evenly, heating to 80°C-95°C, reacting for 30min-90min, and obtaining a secondary solution; S6, adjusting the pH of the secondary return solution to 1.6-2.0, raising the temperature to 95°C-98°C, reacting for 30min-90min, and then performing solid-liquid separation to obtain ammonium polyvanadate and a three-stage vanadium precipitation upper layer liquid; S7, drying the ammonium polyvanadate, heating it to 500-600°C in an oxidizing atmosphere, and calcining it at the temperature to obtain a vanadium pentoxide product.

[0033] In some embodiments, in step S1, ammonium vanadate is produced by a vanadium slag calcification vanadium extraction process, and its main impurities are Mn, Ca, Al, Fe, Si, P, K, and Na. The content of the main impurities does not exceed 1wt%, and the content of other impurities except the main impurities does not exceed 0.05wt%.

[0034] In some embodiments, in step S1, the carbonate is one or more of ammonium carbonate and ammonium bicarbonate, and the added amount is 10-40 g / L.

[0035] In some embodiments, in step S2, the calcium salt impurity remover is one or more of calcium oxide and calcium hydroxide, and the added amount is 2-10 g / L.

[0036] In some embodiments, in step S3, the oxalate is one or more of oxalic acid, ammonium oxalate, sodium oxalate, and potassium oxalate, and the added amount is 1-5 g / L.

[0037] In some embodiments, in step S1, the liquid-to-solid ratio of ammonium vanadate to carbonate solution is 15-30:1 mL / g.

[0038] In some embodiments, in step S5, the liquid-to-solid ratio of the ammonium metavanadate product to pure water is 15-30:1 mL / g. In some embodiments, in step S4, the stirring reaction time is 180 min-360 min.

[0039] In some embodiments, in step S7, the heat preservation and calcination time is 60 min-150 min.

[0040] In some embodiments, the method further includes: repeating step S1-7, and directly using the upper layer of the second stage vanadium precipitation liquid for the re-dissolution of ammonium vanadate.

[0041] In some embodiments, the impurity content of Mn, Ca, Al, Fe, Si, P, K, and Na in ordinary ammonium vanadate (purity <99%) is high, and the technical difficulty and high production cost of preparing vanadium oxide products with a purity of 99.9% or more are high. The present invention can remove the impurities of Mn, Ca, Al, Fe, Si, P, K, and Na in ordinary ammonium vanadate at one time by adding ordinary ammonium vanadate to a carbonate solution, heating and dissolving, and then removing impurities, so that the impurity concentration is reduced to less than 0.005g / L, and after vanadium is precipitated to obtain ammonium metavanadate, it is dissolved again and the pH is adjusted to acidic, and ammonium polyvanadate is recrystallized and precipitated to remove the impurities of K, Na, and Si with high solubility. A high-purity vanadium pentoxide product with a purity of more than 99.95% can be prepared by the ammonium polyvanadate, and the process water can be recycled for multiple times, which significantly reduces the amount of wastewater treatment.

[0042] The invention solves the problems of long process flow, complicated process, large reagent consumption, incomplete impurity removal and the like in the process of preparing high-purity vanadium. The invention uses ordinary purity ammonium vanadate as a raw material, adopts chemical impurity removal, and realizes sufficient removal of Mn, Ca, Al, Fe, Si, P, K and Na impurities through two steps of dissolution-impurity removal-precipitation, and prepares a high-purity vanadium oxide product with a purity of more than 99.95%. The invention shortens the process flow, improves the vanadium yield, reduces the reagent consumption, and significantly reduces the production cost of the high-purity vanadium oxide product. The process water can be recycled for multiple times, and the amount of wastewater treatment is significantly reduced.

[0043] The present invention is further explained below in conjunction with specific embodiments and comparative examples.

[0044] Example 1 Step 1: Add carbonate solution to ammonium vanadate at a liquid-solid ratio of 30:1 mL / g, stir evenly, heat to 75°C, and react for 45 minutes to obtain a vanadium-containing solution; Step 2: Keep the temperature of the vanadium-containing return solution at 75°C, add a calcium salt impurity remover, react for 30 minutes, and then perform solid-liquid separation to obtain a vanadium-containing purified solution and a first-stage impurity-removing slag; Step 3: adding oxalate to the vanadium-containing purified liquid, maintaining the temperature of the vanadium liquid at 75°C, reacting for 60 minutes, and then performing solid-liquid separation to obtain a deeply purified vanadium liquid and a second-stage impurity-removing slag; Step 4: Cool the deep purified vanadium solution to 5°C, stir and react for 240 minutes, and then perform solid-liquid separation to obtain ammonium metavanadate and the second-stage vanadium precipitation upper layer liquid; Step 5: Add the ammonium metavanadate product to pure water at a liquid-solid ratio of 15:1 mL / g for slurrying, stir evenly, heat to 95°C, react for 30 minutes, and obtain a secondary solution; Step 6: The pH of the secondary return solution is adjusted to 1.8, the temperature is raised to 95°C, and the reaction is carried out for 60 minutes before solid-liquid separation to obtain ammonium polyvanadate and the upper layer liquid of the third-stage vanadium precipitation; Step 7: After drying the ammonium polyvanadate, the temperature is raised to 550° C. in an oxidizing atmosphere, and the temperature is kept for calcination for 90 minutes to obtain a vanadium pentoxide product; Step 8: Repeat steps 1-7, and use the upper layer of the second stage vanadium precipitation liquid directly for the dissolution of ammonium vanadate, so as to realize the recycling of water, reduce vanadium loss and wastewater treatment volume.

[0045] Wherein, in step 1, ammonium vanadate is produced by vanadium slag calcification vanadium extraction process, and the main impurities are Mn, Ca, Al, Fe, Si, P, K, and Na, and the content is no more than 1wt%, and the other contents are no more than 0.05wt%. The specific component contents are shown in Table 1. In step 1, the carbonate is ammonium bicarbonate, and the addition amount is 10g / L. In step 2, the calcium salt impurity remover is calcium hydroxide, and the addition amount is 6g / L. The oxalate described in step 3 is ammonium oxalate, and the addition amount is 2g / L.

[0046] Table 1 Main impurity components of common ammonium vanadate raw materials wt%

[0047] The purity of the prepared vanadium pentoxide product reached 99.95%, the vanadium yield of the whole process reached 90.2%, the main impurities K content was 0.003wt%, Al content was 0.001wt%, Ca content was 0.002wt%, Fe content was 0.001wt%, Mn content was 0.001wt%, Si content was 0.002wt%, P content was 0.001wt%, and the contents of other impurities were all lower than 0.002wt%.

[0048] Example 2 Step 1: Add carbonate solution to ammonium vanadate at a liquid-solid ratio of 20:1 mL / g, stir evenly, heat to 85°C, and react for 15 minutes to obtain a vanadium-containing solution; Step 2: Keep the temperature of the vanadium-containing return solution at 85°C, add a calcium salt impurity remover, react for 60 minutes, separate the solid and liquid, and obtain a vanadium-containing purified solution and a first-stage impurity-removing slag; Step 3: adding oxalate to the vanadium-containing purified liquid, maintaining the temperature of the vanadium liquid at 85°C, reacting for 45 minutes, and then separating the solid and the liquid to obtain a deeply purified vanadium liquid and a second-stage impurity-removing slag; Step 4: Cool the deep purified vanadium solution to 15°C, stir and react for 180 minutes, and then perform solid-liquid separation to obtain ammonium metavanadate and the second-stage vanadium precipitation upper layer liquid; Step 5: Add the ammonium metavanadate product to pure water at a liquid-to-solid ratio of 20:1 mL / g for slurrying, stir evenly, heat to 85°C, react for 90 minutes, and obtain a secondary solution; Step 6: The pH of the secondary return solution is adjusted to 1.6, the temperature is raised to 98°C, and the reaction is performed for 90 minutes before solid-liquid separation to obtain ammonium polyvanadate and the upper layer liquid of the third-stage vanadium precipitation; Step 7: After drying the ammonium polyvanadate, the temperature is raised to 600° C. in an oxidizing atmosphere, and the temperature is kept for calcining for 60 minutes to obtain a vanadium pentoxide product; Step 8: Repeat steps 1-7, and use the upper layer of the second stage vanadium precipitation liquid directly for the dissolution of ammonium vanadate, so as to realize the recycling of water, reduce vanadium loss and wastewater treatment volume.

[0049] Among them, the ammonium vanadate in step 1 is produced by the vanadium slag calcification vanadium extraction process, and the main impurities are Mn, Ca, Al, Fe, Si, P, K, and Na, and the content is no more than 1wt%, and the other contents are no more than 0.05wt%. The specific component contents are shown in Table 1. The carbonate in step 1 is ammonium bicarbonate, and the addition amount is 30g / L. The calcium salt impurity remover in step 2 is one or more of calcium oxide and calcium hydroxide, and the addition amount is 2g / L. The oxalate in step 3 is sodium oxalate, and the addition amount is 1g / L; The purity of the prepared vanadium pentoxide product reached 99.98%, the vanadium yield of the whole process reached 89.4%, the main impurities K content was 0.002wt%, Al content was 0.001wt%, Ca content was 0.002wt%, Fe content was 0.001wt%, Mn content was 0.001wt%, Si content was 0.002wt%, P content was 0.001wt%, and the contents of other impurities were all lower than 0.002wt%.

[0050] Example 3 Step 1: Add carbonate solution to ammonium vanadate at a liquid-solid ratio of 15:1 mL / g, stir evenly, heat to 95°C, and react for 60 minutes to obtain a vanadium-containing solution; Step 2: Keep the temperature of the vanadium-containing return solution at 95°C, add a calcium salt impurity remover, react for 15 minutes, separate the solid and liquid, and obtain a vanadium-containing purified solution and a first-stage impurity-removing slag; Step 3: Add oxalate to the vanadium-containing purified liquid, keep the temperature of the vanadium liquid at 95°C, react for 15 minutes, separate the solid and liquid, and obtain a deeply purified vanadium liquid and a second-stage impurity-removing slag; Step 4: Cool the deep purified vanadium solution to 35°C, stir and react for 360 minutes, and then perform solid-liquid separation to obtain ammonium metavanadate and the second-stage vanadium precipitation upper layer liquid; Step 5: Add the ammonium metavanadate product to pure water at a liquid-solid ratio of 30:1 mL / g for slurrying, stir evenly, heat to 80°C, and react for 30 minutes to obtain a secondary solution; Step 6: The pH of the secondary return solution is adjusted to 2.0, the temperature is raised to 98°C, and the reaction is carried out for 30 minutes before solid-liquid separation to obtain ammonium polyvanadate and the upper layer liquid of the third stage vanadium precipitation; Step 7: After drying the ammonium polyvanadate, heating to 500° C. in an oxidizing atmosphere, and calcining for 150 minutes to obtain a vanadium pentoxide product; Step 8: Repeat steps 1-7, and use the upper layer of the second stage vanadium precipitation liquid directly for the dissolution of ammonium vanadate, so as to realize the recycling of water, reduce vanadium loss and wastewater treatment volume.

[0051] Among them, the ammonium vanadate in step 1 is produced by the vanadium slag calcification vanadium extraction process, and the main impurities are Mn, Ca, Al, Fe, Si, P, K, and Na, and the content is no more than 1wt%, and the other contents are no more than 0.05wt%. The specific component contents are shown in Table 1. The carbonate in step 1 is ammonium carbonate, and the addition amount is 40g / L. The calcium salt impurity remover in step 2 is one or more of calcium oxide and calcium hydroxide, and the addition amount is 10g / L. The oxalate in step 3 is oxalic acid, and the addition amount is 5g / L; The purity of the prepared vanadium pentoxide product reached 99.97%, the vanadium yield of the whole process reached 85.5%, the main impurities K content was 0.002wt%, Al content was 0.002wt%, Ca content was 0.003wt%, Fe content was 0.001wt%, Mn content was 0.001wt%, Si content was 0.003wt%, P content was 0.001wt%, and the contents of other impurities were all lower than 0.002wt%.

Claims

1. A method for purifying ammonium vanadate to prepare high-purity vanadium oxide, characterized in that: include: S1, adding carbonate solution to ammonium vanadate, stirring evenly, heating to 75°C-95°C, reacting for 15-60 minutes, and obtaining a vanadium-containing solution; S2, maintaining the temperature of the vanadium-containing return solution at 75-95°C, adding a calcium salt impurity remover, reacting for 15-60 minutes, and then performing solid-liquid separation to obtain a vanadium-containing purified solution and a first-stage impurity-removing slag; S3, adding oxalate to the vanadium-containing purified liquid, maintaining the temperature of the vanadium liquid at 75-95° C., reacting for 30-90 minutes, and then performing solid-liquid separation to obtain a deeply purified vanadium liquid and a second-stage impurity removal slag; S4, cooling the deep purified vanadium liquid to 5°C-35°C, stirring the reaction, and performing solid-liquid separation to obtain ammonium metavanadate and the second-stage vanadium precipitation upper layer liquid; S5, adding the ammonium metavanadate product to pure water for slurrying, stirring evenly, heating to 80°C-95°C, reacting for 30min-90min, and obtaining a secondary solution; S6, adjusting the pH of the secondary return solution to 1.6-2.0, raising the temperature to 95°C-98°C, reacting for 30min-90min, and then performing solid-liquid separation to obtain ammonium polyvanadate and a three-stage vanadium precipitation upper layer liquid; S7, drying the ammonium polyvanadate, heating it to 500-600° C. in an oxidizing atmosphere, and calcining it at the temperature to obtain a vanadium pentoxide product.

2. The method according to claim 1, characterized in that: In step S1, ammonium vanadate is produced by vanadium slag calcification vanadium extraction process, and its main impurities are Mn, Ca, Al, Fe, Si, P, K, and Na. The content of the main impurities does not exceed 1wt%, and the content of other impurities except the main impurities does not exceed 0.05wt%.

3. The method according to claim 1, characterized in that In step S1, the carbonate is one or more of ammonium carbonate and ammonium bicarbonate, and the added amount is 10-40 g / L.

4. The method according to claim 1, characterized in that In step S2, the calcium salt impurity remover is one or more of calcium oxide and calcium hydroxide, and the added amount is 2-10 g / L.

5. The method according to claim 1, characterized in that In step S3, the oxalate is one or more of oxalic acid, ammonium oxalate, sodium oxalate, and potassium oxalate, and the added amount is 1-5 g / L.

6. The method according to claim 1, characterized in that In step S1, the liquid-to-solid ratio of ammonium vanadate to carbonate solution is 15-30:1 mL / g.

7. The method according to claim 1, characterized in that In step S5, the liquid-to-solid ratio of the ammonium metavanadate product to pure water is 15-30:1 mL / g.

8. The method according to claim 1, characterized in that In step S4, the stirring reaction time is 180 min-360 min.

9. The method according to claim 1, characterized in that: In step S7, the heat preservation calcination time is 60 min-150 min.

10. The method according to claim 1, characterized in that Also includes: Repeat step S1-7, and use the upper layer of the second stage vanadium precipitation liquid directly for the re-dissolution of ammonium vanadate.

Images