A method for preparing vanadium pentoxide from a vanadium-rich solution having a high content of impurities

Abstract

The present application relates to a kind of methods for preparing vanadic oxide with high impurity content vanadium-rich solution.The technical scheme is: adding hydrogen peroxide solution to high impurity content vanadium-rich solution, obtaining pretreatment solution;then using precipitant to adjust the pH value of pretreatment solution, carrying out first stirring, solid-liquid separation, obtaining iron-containing precipitate and vanadium-containing solution.Using oxidizing agent to oxidize the potential of vanadium-containing solution to-1100~‑1000mV, obtaining pentavalent vanadium solution, carrying out second stirring to the pentavalent vanadium solution, solid-liquid separation, obtaining sodium polyvanadate and vanadium precipitation mother liquor.Mixing the detergent with sodium polyvanadate, carrying out third stirring, solid-liquid separation, obtaining ammonium polyvanadate and washing waste liquid.Calcining the ammonium polyvanadate at 500~550℃ for 30~60min, obtaining vanadic oxide.The present application has the characteristics of good impurity removal effect, low ammonium consumption and environmental friendliness, and the prepared vanadic oxide has high purity.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of preparing vanadium pentoxide. Specifically, it relates to a method for preparing vanadium pentoxide from vanadium-rich liquid with high impurity content. BACKGROUND

[0002] Vanadium pentoxide, as the most stable vanadium oxide, is widely used in metallurgy, aerospace, electronics industry and electrochemical industry, etc. Some of these fields have higher requirements for the purity of vanadium products, such as being used as raw materials for all-vanadium redox flow batteries. Therefore, the preparation of high-purity vanadium pentoxide is of concern to those skilled in the art.

[0003] There are four methods for preparing vanadium pentoxide: hydrolysis precipitation, ammonium salt precipitation, iron salt precipitation and calcium salt precipitation. Ammonium salt precipitation has the advantages of high vanadium precipitation rate and high product purity. However, due to the high consumption of ammonium salt in the process of ammonium salt precipitation, a large amount of ammonium ions is introduced, which inevitably produces a large amount of high-concentration ammonia-nitrogen wastewater, causing serious environmental pollution. Iron salt precipitation and calcium salt precipitation have a smaller application range and produce products with lower purity, which are mainly used for the enrichment of vanadium intermediates. The hydrolysis precipitation method has little environmental pollution, but the vanadium pentoxide produced by this method has low purity (about 85%). The composition of the leaching solution obtained by acid leaching of vanadium shale is complex. Although extraction-reextraction enrichment is used to remove impurities, the content of impurity elements such as iron, aluminum and sodium in the vanadium-rich liquid is still high. The precipitate obtained by using the conventional vanadium precipitation method is still difficult to remove these impurities after washing, and the purity of the final vanadium pentoxide is basically around 97%. It is difficult to produce high-purity products. When the concentration of impurity ions in the vanadium-rich liquid is too high, the above four vanadium precipitation methods cannot produce high-purity vanadium pentoxide.

[0004] The patent technology "A method for cleaning and efficiently preparing 99-grade vanadium pentoxide" (CN114408971A) uses the hydrolysis precipitation method to prepare a hydrolysis precipitation product, and uses an ammonium salt solution to purify the hydrolysis precipitation product multiple times. After calcination, 99-grade vanadium pentoxide product can be prepared. The ammonium salt purification has an ammonium addition coefficient of 1-1.5, the ammonium consumption is small, and the sodium ions in the vanadium precipitation product can be removed by purification. However, the removal effect of other impurity ions is poor, and it is only suitable for vanadium-rich liquid with an iron ion concentration of less than 0.25 g / L.

[0005] The patent technology "A method for preparing high-purity vanadium pentoxide from high-concentration vanadium-containing solution" (CN118702145A) uses an alkaline vanadium-rich liquid obtained by sodium roasting and water leaching of vanadium slag and removal of impurities as raw material. The content of impurity ions is low. The pH of the solution is adjusted to 0.8-1.3 by sulfuric acid. Vanadium pentoxide product is prepared by hydrolysis precipitation-ammonium salt washing. Although the ammonium consumption is small, the sulfuric acid consumption is large, the impurity removal effect is poor, and it is only suitable for vanadium-rich liquid with low impurity ion content.

[0006] Document 1 (Zhang Liu et al., Preparation of high-purity vanadium pentoxide by urea precipitation of vanadium [J]. Nonferrous Metals, 2018-01-15) uses urea instead of conventional ammonium salt to precipitate vanadium with acid ammonium salt from vanadium-rich liquid, which can prepare high-purity vanadium pentoxide product. The method uses vanadium-rich liquid with low impurity ion content, and the prepared vanadium pentoxide particles are uniform, but the ammonium addition coefficient is 6.7, the ammonium salt consumption is large, and high-concentration ammonia water will pollute the environment.

[0007] Document 2 (Chen Chao et al., Research on preparation process technology of high-purity vanadium pentoxide [J]. World Nonferrous Metals, 2018-12) uses vanadium-rich liquid hydrolysis precipitation-vanadium precipitation-alkali solution impurity removal-magnesium chloride impurity removal-ammonium salt precipitation to prepare vanadium pentoxide product. Although the vanadium pentoxide prepared by the method using vanadium-rich liquid with low impurity ion content has high purity, the impurity removal steps are complex, the reagent consumption is large, the vanadium loss is large, and high-concentration ammonia-nitrogen wastewater pollutes the environment.

[0008] In summary, the existing vanadium pentoxide preparation process uses vanadium-rich liquid with low impurity content as raw material, which has the problems of poor impurity removal effect, high ammonium consumption and serious environmental pollution. SUMMARY

[0009] The present application aims to overcome the defects of the prior art, and aims to provide a method for preparing vanadium pentoxide from vanadium-rich liquid with high impurity content. The method uses vanadium-rich liquid with high impurity content as raw material, has good impurity removal effect, low ammonium consumption and environmental friendliness, and the prepared vanadium pentoxide has high purity.

[0010] To achieve the above-mentioned purpose, the technical solution adopted by the present application is as follows:

[0011] Step one, pretreatment of iron removal

[0012] The molar ratio of solute molecules in hydrogen peroxide solution to ferrous ions in vanadium-rich liquid with high impurity content is 14-18:1. Hydrogen peroxide solution is added to the vanadium-rich liquid with high impurity content to obtain a pretreatment solution. Then the pH value of the pretreatment solution is adjusted to 1.8-3.5 with a precipitating agent, and then the first stirring is carried out at a temperature of 25-50℃, and the solid-liquid separation is carried out to obtain iron-containing precipitate and vanadium-containing solution.

[0013] Step two, oxidation and vanadium precipitation

[0014] The potential of the vanadium-containing solution is oxidized to-1100 to-1000mV with an oxidizing agent to obtain a pentavalent vanadium solution. The second stirring is carried out at a temperature of 80-95℃, and the solid-liquid separation is carried out to obtain sodium polyvanadate and vanadium precipitation mother liquor.

[0015] Step three, ammonium salt washing

[0016] The washing agent and the sodium polyvanadate are mixed according to the mass ratio of ammonium ion in the washing agent to vanadium ion in the sodium polyvanadate of 0.5-1:1, and then the third stirring is carried out at a temperature of 30-60 DEG C, and solid-liquid separation is carried out, so as to obtain ammonium polyvanadate and washing waste liquid.

[0017] Step four, calcination

[0018] The ammonium polyvanadate is calcined at 500-550 DEG C for 30-60 min, so as to obtain vanadium pentoxide.

[0019] In the high-impurity-content vanadium-rich liquid, the concentration of vanadium ion is 20-70 g / L, the concentration of ferrous ion is 0.2-2 g / L, the concentration of aluminum ion is 20-40 g / L, the concentration of sodium ion is 10-30 g / L, and the concentration of zinc ion is 5-15 g / L; the vanadium ion in the high-impurity-content vanadium-rich liquid exists in the form of tetravalent vanadium.

[0020] The oxidant is sodium chlorate or sodium hypochlorite

[0021] The precipitant is one of sodium carbonate solution, sodium bicarbonate solution and sodium hydroxide solution; the mass fraction of the precipitant is 15-20%.

[0022] The first stirring time is 30-45 min, and the rotating speed is 400-500 r / min.

[0023] The second stirring time is 60-90 min, and the rotating speed is 400-500 r / min.

[0024] The third stirring time is 20-40 min, and the rotating speed is 400-500 r / min.

[0025] The washing agent is one of ammonium chloride solution, ammonium sulfate solution and ammonium bicarbonate solution; the mass fraction of the washing agent is 2-5%.

[0026] Compared with the prior art, the present application has the following positive effects:

[0027] 1、The present application adopts the vanadium-rich liquid with high impurity content as raw material, the raw material has many kinds of impurity ions and high content, hydrogen peroxide solution is added to the vanadium-rich liquid with high impurity content for pretreatment and iron removal, the generated precipitate is mainly iron hydroxide colloid, the surface of the iron hydroxide colloid is electronegative, can adsorb other metal cations in the vanadium-rich liquid with high impurity content, so that the concentration of other impurity ions in the vanadium-rich liquid with high impurity content is reduced. The impurity ion content in the vanadium-containing solution obtained after pretreatment and iron removal can be reduced to 20% compared with the impurity ion content in the vanadium-rich liquid with high impurity content, and the vanadium ion concentration after pretreatment and iron removal remains basically unchanged, reducing the influence of impurity ions on subsequent vanadium precipitation. The vanadium pentoxide product prepared from the vanadium-containing solution has a purity of more than 99%, which is higher than the vanadium pentoxide product prepared from the vanadium-rich liquid, and has good purification and impurity removal effect.

[0028] 2、The present application adopts the method of oxidation vanadium precipitation-ammonium salt washing to prepare vanadium pentoxide, compared with the ammonium salt vanadium precipitation process in the same solution system, the ammonium addition coefficient is reduced from 4-6 to 0.5-1, the ammonium consumption is reduced by more than 80%, and the ammonium consumption is low. The concentration of ammonium ion in the washing waste liquid can be reduced to 100-300 mg / L compared with the concentration of ammonium ion in the vanadium precipitation mother liquor of ammonium salt vanadium precipitation, effectively reducing the difficulty of wastewater treatment, reducing the cost of wastewater treatment, and being more friendly to the environment.

[0029] 3、The present application adopts the method of hydrogen peroxide solution pretreatment and iron removal-oxidation vanadium precipitation-ammonium salt washing to prepare vanadium pentoxide with a purity of more than 99%, which has the advantages of simple operation, good purification and impurity removal effect, low ammonium consumption, vanadium recovery rate of more than 99%, and high production efficiency. The ions in the washing waste liquid are mainly ammonium ion, sodium ion and chloride ion, which can be recovered by cooling crystallization, recycled, further reducing the concentration of ammonium ion and chloride ion in the washing waste water, and reducing the pollution to the environment.

[0030] Therefore, the present application uses the vanadium-rich liquid with high impurity content as raw material, has the characteristics of good impurity removal effect, low ammonium consumption and environmental friendliness, and the prepared vanadium pentoxide has high purity. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 It is an XRD graph of the present application for preparing vanadium pentoxide from vanadium-rich liquid with high impurity content. DETAILED DESCRIPTION

[0032] The present application will be further described in conjunction with specific embodiments, which are not limitations to the scope of protection.

[0033] A method for preparing vanadium pentoxide from vanadium-rich liquid with high impurity content. The preparation method of the present embodiment is:

[0034] Step one, pretreatment of iron removal

[0035] According to the molar ratio of solute molecules in hydrogen peroxide solution to ferrous ions in the high-impurity-content vanadium-rich solution of 14-18:1, hydrogen peroxide solution is added to the high-impurity-content vanadium-rich solution to obtain a pretreatment solution; then the pH value of the pretreatment solution is adjusted to 1.8-3.5 by using a precipitant, and then the first stirring is carried out at a temperature of 25-50℃, and solid-liquid separation is carried out to obtain iron-containing precipitate and vanadium-containing solution.

[0036] Step two, oxidation and vanadium precipitation

[0037] The potential of the vanadium-containing solution is oxidized to -1100--1000mV by using an oxidizing agent to obtain a pentavalent vanadium solution; the second stirring is carried out at a temperature of 80-95℃, and solid-liquid separation is carried out to obtain sodium polyvanadate and vanadium precipitation mother liquor.

[0038] Step three, ammonium salt washing

[0039] According to the mass ratio of ammonium ions in the washing agent to vanadium ions in the sodium polyvanadate of 0.5-1:1, the washing agent is mixed with the sodium polyvanadate, and then the third stirring is carried out at a temperature of 30-60℃, and solid-liquid separation is carried out to obtain ammonium polyvanadate and washing waste liquid.

[0040] Step four, calcination

[0041] The ammonium polyvanadate is calcined at 500-550℃ for 30-60min to prepare vanadium pentoxide.

[0042] In the high-impurity-content vanadium-rich solution: the concentration of vanadium ions is 20-70g / L, the concentration of ferrous ions is 0.2-2g / L, the concentration of aluminum ions is 20-40g / L, the concentration of sodium ions is 10-30g / L, and the concentration of zinc ions is 5-15g / L; the vanadium ions in the high-impurity-content vanadium-rich solution exist in the form of tetravalent vanadium.

[0043] The oxidizing agent is sodium chlorate or sodium hypochlorite.

[0044] The precipitant is one of sodium carbonate solution, sodium bicarbonate solution and sodium hydroxide solution; the mass fraction of the precipitant is 15-20%.

[0045] The first stirring time is 30-45min, and the rotation speed is 400-500r / min.

[0046] The second stirring time is 60-90min, and the rotation speed is 400-500r / min.

[0047] The third stirring time is 20-40 min, and the rotating speed is 400-500 r / min.

[0048] The detergent is one of ammonium chloride solution, ammonium sulfate solution and ammonium bicarbonate solution; the mass fraction of the detergent is 2-5%.

[0049] Embodiment 1

[0050] The embodiment discloses a method for preparing vanadium pentoxide from a vanadium-rich solution with high impurity content.

[0051] Step one, pretreatment and iron removal

[0052] According to the molar ratio of solute molecules in hydrogen peroxide solution to ferrous ions in the vanadium-rich solution with high impurity content, hydrogen peroxide solution is added to the vanadium-rich solution with high impurity content to obtain a pretreatment solution; then, a precipitant is used to adjust the pH value of the pretreatment solution to 1.8, and the pretreatment solution is stirred for the first time at a temperature of 50 ℃, and then solid-liquid separation is performed to obtain iron-containing precipitate and vanadium-containing solution.

[0053] Step two, oxidation and vanadium precipitation

[0054] The vanadium-containing solution is oxidized to-1100 mV by an oxidizing agent to obtain a pentavalent vanadium solution; the pentavalent vanadium solution is stirred for the second time at a temperature of 95 ℃, and then solid-liquid separation is performed to obtain sodium polyvanadate and vanadium precipitation mother liquor.

[0055] Step three, ammonium salt washing

[0056] According to the mass ratio of ammonium ions in the detergent to vanadium ions in the sodium polyvanadate, the detergent is mixed with the sodium polyvanadate, and then the mixture is stirred for the third time at a temperature of 30 ℃, and then solid-liquid separation is performed to obtain ammonium polyvanadate and washing waste liquid.

[0057] Step four, calcination

[0058] The ammonium polyvanadate is calcined at 500 ℃ for 60 min to obtain vanadium pentoxide.

[0059] In the vanadium-rich solution with high impurity content, the concentration of vanadium ions is 20 g / L, the concentration of ferrous ions is 0.4 g / L, the concentration of aluminum ions is 20 g / L, the concentration of sodium ions is 10 g / L, and the concentration of zinc ions is 5 g / L; the vanadium ions in the vanadium-rich solution with high impurity content exist in the form of tetravalent vanadium.

[0060] The oxidizing agent is sodium chlorate.

[0061] The precipitant is sodium carbonate solution; the mass fraction of the precipitant is 15%.

[0062] The first stirring time is 45 min, and the rotating speed is 400 r / min.

[0063] The second stirring time is 60 min, and the rotating speed is 430 r / min.

[0064] The third stirring time is 40 min, and the rotating speed is 460 r / min.

[0065] The washing agent is ammonium chloride solution, and the mass fraction of the washing agent is 2%.

[0066] The vanadium pentoxide prepared from the vanadium-rich solution with high impurity content is detected, and the vanadium precipitation rate is 99.034%, and the purity of the vanadium pentoxide product is 99.045%.

[0067] Example 2

[0068] A method for preparing vanadium pentoxide from a vanadium-rich solution with high impurity content. The preparation method described in this example is:

[0069] Step one, pretreatment of iron removal

[0070] According to the molar ratio of solute molecules in hydrogen peroxide solution to ferrous ions in the vanadium-rich solution with high impurity content is 16:1, hydrogen peroxide solution is added to the vanadium-rich solution with high impurity content to obtain a pretreatment solution; then the pH value of the pretreatment solution is adjusted to 2.3 by using a precipitating agent, and then the first stirring is carried out under the condition of temperature 40℃, solid-liquid separation is carried out, and iron-containing precipitate and vanadium-containing solution are obtained.

[0071] Step two, oxidation and vanadium precipitation

[0072] The potential of the vanadium-containing solution is oxidized to-1060 mV by using an oxidizing agent to obtain a pentavalent vanadium solution; the second stirring is carried out under the condition of temperature 90℃, solid-liquid separation is carried out, and sodium polyvanadate and vanadium precipitation mother liquor are obtained.

[0073] Step three, ammonium salt washing

[0074] According to the mass ratio of ammonium ions in the washing agent to vanadium ions in the sodium polyvanadate is 0.65:1, the washing agent is mixed with the sodium polyvanadate, and then the third stirring is carried out under the condition of temperature 40℃, solid-liquid separation is carried out, and ammonium polyvanadate and washing waste liquid are obtained.

[0075] Step four, calcination

[0076] The ammonium polyvanadate is calcined at 520℃ for 50 min to prepare vanadium pentoxide.

[0077] The high-impurity-content vanadium-rich solution has a vanadium ion concentration of 45 g / L, a ferrous ion concentration of 0.8 g / L, an aluminum ion concentration of 25 g / L, a sodium ion concentration of 15 g / L and a zinc ion concentration of 9 g / L; and the vanadium ions in the high-impurity-content vanadium-rich solution exist in the form of tetravalent vanadium.

[0078] The oxidizing agent is sodium hypochlorite

[0079] The precipitating agent is a sodium hydroxide solution, and the mass fraction of the precipitating agent is 16%.

[0080] The first stirring time is 40 min, and the rotating speed is 430 r / min.

[0081] The second stirring time is 70 min, and the rotating speed is 460 r / min.

[0082] The third stirring time is 35 min, and the rotating speed is 500 r / min.

[0083] The washing agent is an ammonium sulfate solution, and the mass fraction of the washing agent is 3%.

[0084] The vanadium pentoxide prepared from the high-impurity-content vanadium-rich solution in the example is detected, and the vanadium precipitation rate is 99.068%, and the purity of the vanadium pentoxide product is 99.063%.

[0085] Example 3

[0086] A method for preparing vanadium pentoxide from a high-impurity-content vanadium-rich solution.

[0087] Step one, iron removal by pretreatment

[0088] According to a molar ratio of solute molecules in the hydrogen peroxide solution to ferrous ions in the high-impurity-content vanadium-rich solution of 17:1, hydrogen peroxide solution is added to the high-impurity-content vanadium-rich solution to obtain a pretreated solution; then a precipitating agent is used to adjust the pH value of the pretreated solution to 2.8, and then the first stirring is performed at a temperature of 30℃, and solid-liquid separation is performed to obtain iron-containing precipitates and vanadium-containing solution.

[0089] Step two, vanadium precipitation by oxidation

[0090] The potential of the vanadium-containing solution is oxidized to -1020 mV by using an oxidizing agent to obtain a pentavalent vanadium solution; the second stirring is performed at a temperature of 85℃, and solid-liquid separation is performed to obtain sodium polyvanadate and vanadium precipitation mother liquor.

[0091] Step three, ammonium salt washing

[0092] The detergent and the sodium polyvanadate are mixed according to the mass ratio of ammonium ion in the detergent to vanadium ion in the sodium polyvanadate of 0.85:1, and then the third stirring is carried out at a temperature of 50°C, and solid-liquid separation is carried out, so as to obtain ammonium polyvanadate and a washing waste liquid.

[0093] Step four, calcination

[0094] The ammonium polyvanadate is calcined at 540°C for 40 minutes, so as to obtain vanadium pentoxide.

[0095] In the high-impurity-content vanadium-rich solution, the concentration of vanadium ion is 55g / L, the concentration of ferrous ion is 1.4g / L, the concentration of aluminum ion is 30g / L, the concentration of sodium ion is 20g / L, and the concentration of zinc ion is 12g / L; and the vanadium ion in the high-impurity-content vanadium-rich solution exists in the form of tetravalent vanadium.

[0096] The oxidizing agent is sodium chlorate.

[0097] The precipitating agent is sodium bicarbonate solution; and the mass fraction of the precipitating agent is 18%.

[0098] The first stirring time is 35 minutes, and the rotating speed is 460r / min.

[0099] The second stirring time is 80 minutes, and the rotating speed is 500r / min.

[0100] The third stirring time is 30 minutes, and the rotating speed is 400r / min.

[0101] The detergent is ammonium bicarbonate solution; and the mass fraction of the detergent is 4%.

[0102] The vanadium pentoxide prepared from the high-impurity-content vanadium-rich solution in this embodiment is detected, and the results show that the vanadium precipitation rate is 99.076%, and the purity of the vanadium pentoxide product is 99.058%.

[0103] Example 4

[0104] A method for preparing vanadium pentoxide from a high-impurity-content vanadium-rich solution. The preparation method in this embodiment is as follows:

[0105] Step one, iron removal by pretreatment

[0106] According to the molar ratio of solute molecules in the hydrogen peroxide solution to ferrous ions in the high-impurity-content vanadium-rich solution of 18:1, the hydrogen peroxide solution is added to the high-impurity-content vanadium-rich solution, so as to obtain a pretreated solution; then the pH value of the pretreated solution is adjusted to 3.5 by using a precipitating agent, and then the first stirring is carried out at a temperature of 25°C, and solid-liquid separation is carried out, so as to obtain a ferrous precipitate and a vanadium-containing solution.

[0107] Step two, vanadium precipitation

[0108] Oxidizing the potential of the vanadium-containing solution to -1000mV with an oxidizing agent to obtain a pentavalent vanadium solution; stirring the pentavalent vanadium solution for a second time at a temperature of 80℃, and solid-liquid separation to obtain sodium polyvanadate and a vanadium precipitation mother liquor.

[0109] Step three, ammonium salt washing

[0110] Mixing the washing agent with the sodium polyvanadate according to a mass ratio of ammonium ions in the washing agent to vanadium ions in the sodium polyvanadate of 1:1, stirring the mixture for a third time at a temperature of 60℃, and solid-liquid separation to obtain ammonium polyvanadate and a washing waste liquid.

[0111] Step four, calcination

[0112] Calcining the ammonium polyvanadate at 550℃ for 30min to obtain vanadium pentoxide.

[0113] In the vanadium-rich solution with a high impurity content, the concentration of vanadium ions is 70g / L, the concentration of ferrous ions is 2g / L, the concentration of aluminum ions is 40g / L, the concentration of sodium ions is 30g / L, and the concentration of zinc ions is 15g / L; the vanadium ions in the vanadium-rich solution with a high impurity content exist in the form of tetravalent vanadium.

[0114] The oxidizing agent is sodium hypochlorite

[0115] The precipitant is a sodium carbonate solution; the mass fraction of the precipitant is 20%.

[0116] The first stirring time is 30min, and the rotation speed is 500r / min.

[0117] The second stirring time is 90min, and the rotation speed is 400r / min.

[0118] The third stirring time is 20min, and the rotation speed is 430r / min.

[0119] The washing agent is an ammonium chloride solution; the mass fraction of the washing agent is 5%.

[0120] The vanadium pentoxide prepared from the vanadium-rich solution with a high impurity content in this example is detected to have a vanadium precipitation rate of 99.082% and a vanadium pentoxide product purity of 99.087%.

[0121] Compared with the prior art, the specific embodiment has the following positive effects:

[0122] 1. This specific embodiment uses a vanadium-rich solution with a high impurity content as raw material. This raw material not only contains a variety of impurity ions but also has a high content. Hydrogen peroxide solution is added to the vanadium-rich solution for pretreatment to remove iron. The resulting precipitate is mainly ferric hydroxide colloid. The ferric hydroxide colloid has an electronegative surface and adsorbs other metal cations from the vanadium-rich solution, thus reducing the concentration of other impurity ions. The impurity ion content in the vanadium-containing solution obtained after pretreatment to remove iron can be reduced by up to 20% compared to the impurity ion content in the vanadium-rich solution with a high impurity content, while the vanadium ion concentration remains essentially unchanged, mitigating the impact of impurity ions on subsequent vanadium precipitation. The purity of the vanadium pentoxide product prepared from the vanadium-containing solution can be increased from 85% to over 99% compared to the vanadium pentoxide product prepared from the vanadium-rich solution with a high impurity content, demonstrating excellent purification and impurity removal effects. The vanadium pentoxide prepared in this specific embodiment is shown in the attached figure. Figure 1 This is the XRD pattern of vanadium pentoxide prepared from a vanadium-rich solution with a high impurity content in Example 1. Figure 1 It can be seen that the prepared vanadium pentoxide product has high crystallinity and only contains vanadium pentoxide as a phase, indicating that the vanadium pentoxide has high purity.

[0123] 2. This specific embodiment uses a vanadium oxide precipitation-ammonium salt washing method to prepare vanadium pentoxide. Compared with the ammonium salt precipitation process in the same solution system, this method reduces the ammonium addition coefficient from 4-6 to 0.5-1, reducing ammonium consumption by more than 80%, resulting in lower ammonium consumption. The ammonium ion concentration in the washing wastewater is reduced from 10,000-30,000 mg / L to 100-300 mg / L compared to the ammonium ion concentration in the vanadium precipitation mother liquor, effectively reducing wastewater treatment difficulty and costs, and is more environmentally friendly.

[0124] 3. This specific embodiment employs a hydrogen peroxide solution pretreatment process for iron removal, followed by vanadium oxide precipitation and ammonium salt washing to prepare vanadium pentoxide products with a purity greater than 99%. This method is simple to operate, has good purification and impurity removal effects, low ammonium consumption, a vanadium recovery rate greater than 99%, and high production efficiency. The ions in the washing wastewater are mainly ammonium ions, sodium ions, and chloride ions. Ammonium chloride can be recovered and recycled through cooling crystallization, further reducing the concentration of ammonium ions and chloride ions in the washing wastewater and mitigating environmental pollution.

[0125] Therefore, this specific embodiment uses vanadium-rich liquid with high impurity content as raw material, which has the characteristics of good impurity removal effect, low ammonium consumption and environmental friendliness, and the vanadium pentoxide prepared has high purity.

Claims

1. A method for preparing vanadium pentoxide from a vanadium-rich solution having a high content of impurities, characterized in that The method for preparing the vanadium pentoxide is: Step one, iron removal by pretreatment According to the molar ratio of the solute molecules in the hydrogen peroxide solution to the ferrous ions in the vanadium-rich solution with high impurity content of 14-18:1, the hydrogen peroxide solution is added to the vanadium-rich solution with high impurity content to obtain a pretreated solution; then the pH value of the pretreated solution is adjusted to 1.8-3.5 by using a precipitant, and then the first stirring is carried out at a temperature of 25-50°C, and solid-liquid separation is carried out to obtain an iron-containing precipitate and a vanadium-containing solution; Step two, vanadium precipitation by oxidation The potential of the vanadium-containing solution is oxidized to-1100--1000mV by using an oxidizing agent to obtain a pentavalent vanadium solution; the second stirring is carried out at a temperature of 80-95°C, and solid-liquid separation is carried out to obtain sodium polyvanadate and a vanadium precipitation mother liquor; Step three, ammonium salt washing According to the mass ratio of the ammonium ions in the washing agent to the vanadium ions in the sodium polyvanadate of 0.5-1:1, the washing agent is mixed with the sodium polyvanadate, and then the third stirring is carried out at a temperature of 30-60°C, and solid-liquid separation is carried out to obtain ammonium polyvanadate and a washing waste liquid; Step four, calcination The ammonium polyvanadate is calcined at 500-550°C for 30-60 min to prepare vanadium pentoxide; The oxidizing agent is sodium chlorate or sodium hypochlorite; The precipitant is one of sodium carbonate solution, sodium bicarbonate solution and sodium hydroxide solution, and the mass fraction of the precipitant is 15-20%; The washing agent is one of ammonium chloride solution, ammonium sulfate solution and ammonium bicarbonate solution, and the mass fraction of the washing agent is 2-5%.

2. The process for preparing vanadium pentoxide from a high impurity containing vanadium-rich solution as claimed in claim 1, wherein, In the vanadium-rich solution with high impurity content: the concentration of vanadium ions is 20-70g / L, the concentration of ferrous ions is 0.2-2g / L, the concentration of aluminum ions is 20-40g / L, the concentration of sodium ions is 10-30g / L, and the concentration of zinc ions is 5-15g / L; the vanadium ions in the vanadium-rich solution with high impurity content exist in the form of tetravalent vanadium.

3. The process for preparing vanadium pentoxide from a high impurity containing vanadium-rich solution as claimed in claim 1, wherein, The first stirring time is 30-45min, and the rotation speed is 400-500r / min.

4. The process for preparing vanadium pentoxide from a high impurity containing vanadium-rich solution as claimed in claim 1, wherein, The second stirring time is 60-90min, and the rotation speed is 400-500r / min.

5. The process for preparing vanadium pentoxide from a high impurity containing vanadium rich solution as claimed in claim 1 wherein, The third stirring time is 20-40min, and the rotation speed is 400-500r / min. ​

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