Method for preparing vanadium pentoxide by using vanadium-rich liquid with relatively high impurity content

Abstract

The invention relates to a method for preparing vanadium pentoxide by using vanadium-rich liquid with relatively high impurity content. According to the technical scheme, the method comprises the following steps: adding a hydrogen peroxide solution into the vanadium-rich liquid with relatively high impurity content to obtain a pretreatment solution; the pH value of the pretreatment solution is reduced through a precipitator, first stirring is conducted, solid-liquid separation is conducted, and iron-containing precipitates and a vanadium-containing solution are obtained; and oxidizing the potential of the vanadium-containing solution to-1100 to-1000 mV by using an oxidizing agent to obtain a pentavalent vanadium solution, and carrying out secondary stirring and solid-liquid separation on the pentavalent vanadium solution to obtain sodium polyvanadate and a vanadium precipitation mother solution. And mixing the detergent with sodium polyvanadate, stirring for the third time, and carrying out solid-liquid separation to obtain ammonium polyvanadate and washing waste liquid. And calcining the ammonium polyvanadate at the temperature of between 500 and 550 DEG C for 30 to 60 minutes, so as to obtain the vanadium pentoxide. The method has the characteristics of good impurity removal effect, low ammonium consumption and environmental friendliness, and the prepared vanadium pentoxide is high in purity.

Description

Technical Field

[0001] The invention belongs to the technical field of preparing vanadium pentoxide, and specifically relates to a method for preparing vanadium pentoxide by using vanadium-rich liquid with high impurity content. Background Art

[0002] Vanadium pentoxide, as the most stable vanadium oxide, is widely used in metallurgy, aerospace, electronics industry, electrochemical industry and other fields. Some of these fields have higher requirements on the purity of vanadium products, such as as a raw material for all-vanadium liquid flow batteries. Therefore, the preparation of high-purity vanadium pentoxide is of concern to technicians in this field.

[0003] The vanadium precipitation methods for preparing vanadium pentoxide include: 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, but due to the high consumption of ammonium salt in the process of ammonium salt precipitation, a large amount of ammonium ions are introduced, which will inevitably produce a large amount of high-concentration ammonia nitrogen wastewater, causing serious environmental pollution. The application range of iron salt precipitation and calcium salt precipitation is relatively small, and the purity of the products produced is relatively low. They are mainly used for the enrichment of vanadium intermediates. The hydrolysis precipitation method has little environmental pollution, but the purity of the vanadium pentoxide produced by it is relatively low (about 85%). The leachate obtained by acid leaching of vanadium shale is complex in composition. Although it is enriched and removed by extraction-strip extraction, the content of impurity elements in the vanadium-rich solution is still relatively high, such as iron, aluminum, sodium, etc. It is still difficult to remove these impurities after washing the precipitate obtained by the conventional vanadium precipitation method. The purity of the vanadium pentoxide finally obtained is basically around 97%, and it is difficult to produce high-purity products. When the concentration of impurity ions in the vanadium-rich solution is too high, the above four vanadium precipitation methods cannot produce high-purity vanadium pentoxide.

[0004] The patented technology of "A method for preparing 99-grade vanadium pentoxide in a clean and efficient manner" (CN114408971A) adopts a hydrolysis vanadium precipitation method to prepare a hydrolysis vanadium precipitation product, and the hydrolysis vanadium precipitation product is purified multiple times with an ammonium salt solution. After calcination, a 99-grade vanadium pentoxide product can be prepared. The ammonium addition coefficient of ammonium salt purification is 1 to 1.5, and the ammonium consumption is small. The purification can remove sodium ions in the vanadium precipitation product, but the removal effect of other impurity ions is poor. It is only suitable for vanadium-rich solution with an iron ion concentration lower than 0.25g / L.

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

[0006] Reference 1 (Zhang Liuhong et al., Preparation of high-purity vanadium pentoxide by urea precipitation [J]. Nonferrous Metals, 2018-1-15) uses vanadium-rich liquid as raw material and uses urea to replace conventional ammonium salts for acidic ammonium salt precipitation of vanadium to prepare a vanadium pentoxide product with high purity. The vanadium-rich liquid used in this method has a low content of impurity ions. Although the prepared vanadium pentoxide particles are evenly distributed, the ammonium addition coefficient is 6.7, the ammonium salt consumption is large, and high-concentration ammonia water will be produced to pollute the environment.

[0007] Reference 2 (Chen Chao et al., Research on the Preparation Technology of High-Purity Vanadium Pentoxide [J]. World Nonferrous Metals, 2018-12) adopts the method of hydrolysis of vanadium-rich liquid to precipitate vanadium - alkali dissolution to remove impurities - magnesium chloride to remove impurities - ammonium salt precipitation to prepare vanadium pentoxide products. Although the vanadium pentoxide prepared by this method using vanadium-rich liquid with low impurity ion content has high purity, the impurity removal steps are complicated, the reagent consumption is large, the vanadium loss is large, and high-concentration ammonia nitrogen wastewater is generated to pollute the environment.

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

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

[0010] To achieve the above purpose, the specific steps of the technical solution adopted by the present invention are:

[0011] Step 1: Pretreatment to remove iron

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

[0013] Step 2: Oxidation and precipitation of vanadium

[0014] The potential of the vanadium-containing solution is oxidized to -1100--1000 mV by using an oxidant to obtain a pentavalent vanadium solution; the pentavalent vanadium solution is stirred for a second time at a temperature of 80-95° C., and solid-liquid separation is performed to obtain polysodium vanadate and a vanadium precipitation mother liquor.

[0015] Step 3: Ammonium salt washing

[0016] The detergent and the sodium polyvanadate are mixed at a mass ratio of ammonium ions in the detergent to vanadium ions in the sodium polyvanadate of 0.5 to 1:1, and then stirred for the third time at a temperature of 30 to 60° C. to separate the solid and the liquid to obtain ammonium polyvanadate and a washing waste liquid.

[0017] Step 4: Calcination

[0018] The polyammonium vanadate is calcined at 500-550° C. for 30-60 minutes to obtain vanadium pentoxide.

[0019] In the vanadium-rich liquid with a high impurity content, the vanadium ion concentration is 20-70 g / L, the ferrous ion concentration is 0.2-2 g / L, the aluminum ion concentration is 20-40 g / L, the sodium ion concentration is 10-30 g / L, and the zinc ion concentration is 5-15 g / L; the vanadium ions in the vanadium-rich liquid with a high impurity content exist 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 to 45 minutes, and the rotation speed is 400 to 500 r / min.

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

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

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

[0026] Due to the adoption of the above technical solution, the present invention has the following positive effects compared with the prior art:

[0027] 1. The present invention uses vanadium-rich liquid with high impurity content as raw material. The raw material not only has many types of impurity ions and high content, but also adds hydrogen peroxide solution to the vanadium-rich liquid with high impurity content for pretreatment and iron removal. The precipitate produced is mainly iron hydroxide colloid. The surface of iron hydroxide colloid is electronegative, which will adsorb other metal cations in the vanadium-rich liquid with high impurity content, so as to reduce the concentration of other impurity ions in the vanadium-rich liquid with high impurity content. 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, while the vanadium ion concentration after pretreatment and iron removal remains basically unchanged, reducing the influence of impurity ions on subsequent vanadium precipitation. Compared with the vanadium pentoxide product prepared from vanadium-containing solution, the purity of the vanadium pentoxide product prepared from vanadium-rich liquid can be increased from 85% to more than 99%, and the purification and impurity removal effect is good.

[0028] 2. The present invention adopts the method of vanadium pentoxide precipitation-ammonium salt washing to prepare vanadium pentoxide. Compared with the ammonium salt precipitation process under the same solution system, the ammonium addition coefficient of this method is reduced from 4 to 6 to 0.5 to 1, and the ammonium consumption is reduced by more than 80%. The ammonium consumption is low. Compared with the ammonium root ion concentration in the vanadium precipitation mother liquor of ammonium salt precipitation, the ammonium root ion concentration in the washing wastewater can be reduced from 10000 to 30000 mg / L to 100 to 300 mg / L, which effectively reduces the difficulty of wastewater treatment, reduces the cost of wastewater treatment, and is more environmentally friendly.

[0029] 3. The present invention adopts the method of pretreatment with hydrogen peroxide solution to remove iron-oxidation precipitation of vanadium-ammonium salt washing to prepare vanadium pentoxide products with a purity greater than 99%. The 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 by cooling crystallization, further reducing the concentration of ammonium ions and chloride ions in the washing wastewater and reducing pollution to the environment.

[0030] Therefore, the present invention uses vanadium-rich liquid with a high impurity content as a 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 THE DRAWINGS

[0031] Figure 1 The present invention shows an XRD diagram of vanadium pentoxide prepared by using a vanadium-rich solution with a high impurity content. DETAILED DESCRIPTION

[0032] The present invention is further described below in conjunction with specific implementation modes, but is not intended to limit the protection scope thereof.

[0033] A method for preparing vanadium pentoxide using a vanadium-rich solution with a high impurity content. The preparation method of this specific embodiment is:

[0034] Step 1: Pretreatment to remove iron

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

[0036] Step 2: Oxidation and precipitation of vanadium

[0037] The potential of the vanadium-containing solution is oxidized to -1100--1000 mV by using an oxidant to obtain a pentavalent vanadium solution; the pentavalent vanadium solution is stirred for a second time at a temperature of 80-95° C., and solid-liquid separation is performed to obtain polysodium vanadate and a vanadium precipitation mother liquor.

[0038] Step 3: Ammonium salt washing

[0039] The detergent and the sodium polyvanadate are mixed at a mass ratio of ammonium ions in the detergent to vanadium ions in the sodium polyvanadate of 0.5 to 1:1, and then stirred for the third time at a temperature of 30 to 60° C. to separate the solid and the liquid to obtain ammonium polyvanadate and a washing waste liquid.

[0040] Step 4: Calcination

[0041] The polyammonium vanadate is calcined at 500-550° C. for 30-60 minutes to obtain vanadium pentoxide.

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

[0043] The oxidant 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 to 45 minutes, and the rotation speed is 400 to 500 r / min.

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

[0047] The third stirring time is 20 to 40 minutes, and the rotation speed is 400 to 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] Example 1

[0050] A method for preparing vanadium pentoxide using a vanadium-rich solution with a high impurity content. The preparation method described in this embodiment is:

[0051] Step 1: Pretreatment to remove iron

[0052] According to the molar ratio of solute molecules in the hydrogen peroxide solution to ferrous ions in the vanadium-rich solution with a high impurity content of 15:1, the hydrogen peroxide solution is added to the vanadium-rich solution with a high impurity content to obtain a pretreatment solution; the pH value of the pretreatment solution is adjusted to 1.8 with a precipitant, and then the first stirring is carried out at a temperature of 50°C, and solid-liquid separation is carried out to obtain an iron-containing precipitate and a vanadium-containing solution.

[0053] Step 2: Oxidation and precipitation of vanadium

[0054] The potential of the vanadium-containing solution is oxidized to -1100 mV by using an oxidant to obtain a pentavalent vanadium solution; the pentavalent vanadium solution is stirred for a second time at a temperature of 95° C., and solid-liquid separation is performed to obtain polysodium vanadate and a vanadium precipitation mother liquor.

[0055] Step 3: Ammonium salt washing

[0056] The detergent and the sodium polyvanadate are mixed at a mass ratio of ammonium ions in the detergent to vanadium ions in the sodium polyvanadate of 0.5:1, and then stirred for the third time at a temperature of 30°C, and the solid-liquid separation is performed to obtain ammonium polyvanadate and washing waste liquid.

[0057] Step 4: Calcination

[0058] The polyammonium vanadate is calcined at 500° C. for 60 minutes to obtain vanadium pentoxide.

[0059] In the vanadium-rich liquid with a higher impurity content, the vanadium ion concentration is 20 g / L, the ferrous ion concentration is 0.4 g / L, the aluminum ion concentration is 20 g / L, the sodium ion concentration is 10 g / L, and the zinc ion concentration is 5 g / L; the vanadium ions in the vanadium-rich liquid with a higher 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 rotation speed is 400 r / min.

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

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

[0065] The detergent is an ammonium chloride solution; the mass fraction of the detergent is 2%.

[0066] The vanadium pentoxide prepared from the vanadium-rich solution with a high impurity content in this embodiment was tested to have a vanadium precipitation rate of 99.034% and a purity of vanadium pentoxide product of 99.045%.

[0067] Example 2

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

[0069] Step 1: Pretreatment to remove iron

[0070] According to the molar ratio of solute molecules in the hydrogen peroxide solution to ferrous ions in the vanadium-rich solution with a high impurity content of 16:1, the hydrogen peroxide solution is added to the vanadium-rich solution with a high impurity content to obtain a pretreatment solution; the pH value of the pretreatment solution is adjusted to 2.3 with a precipitant, and then the first stirring is carried out at a temperature of 40°C, and solid-liquid separation is carried out to obtain an iron-containing precipitate and a vanadium-containing solution.

[0071] Step 2: Oxidation and precipitation of vanadium

[0072] The potential of the vanadium-containing solution is oxidized to -1060 mV by using an oxidant to obtain a pentavalent vanadium solution; the pentavalent vanadium solution is stirred for a second time at a temperature of 90° C., and solid-liquid separation is performed to obtain polysodium vanadate and a vanadium precipitation mother liquor.

[0073] Step 3: Ammonium salt washing

[0074] The detergent and the sodium polyvanadate are mixed at a mass ratio of ammonium ions in the detergent to vanadium ions in the sodium polyvanadate of 0.65:1, and then stirred for the third time at a temperature of 40°C, and the solid-liquid separation is performed to obtain ammonium polyvanadate and washing waste liquid.

[0075] Step 4: Calcination

[0076] The polyammonium vanadate is calcined at 520° C. for 50 minutes to obtain vanadium pentoxide.

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

[0078] The oxidant is sodium hypochlorite

[0079] The precipitant is sodium hydroxide solution; the mass fraction of the precipitant is 16%.

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

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

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

[0083] The detergent is an ammonium sulfate solution; the mass fraction of the detergent is 3%.

[0084] The vanadium pentoxide prepared from the vanadium-rich solution with a high impurity content in this embodiment was tested to have a vanadium precipitation rate of 99.068% and a purity of vanadium pentoxide product of 99.063%.

[0085] Example 3

[0086] A method for preparing vanadium pentoxide using a vanadium-rich solution with a high impurity content. The preparation method described in this embodiment is:

[0087] Step 1: Pretreatment to remove iron

[0088] According to the molar ratio of solute molecules in the hydrogen peroxide solution to ferrous ions in the vanadium-rich solution with a high impurity content of 17:1, the hydrogen peroxide solution is added to the vanadium-rich solution with a high impurity content to obtain a pretreatment solution; the pH value of the pretreatment solution is adjusted to 2.8 with a precipitant, and then the first stirring is carried out at a temperature of 30° C., and solid-liquid separation is carried out to obtain an iron-containing precipitate and a vanadium-containing solution.

[0089] Step 2: Oxidation and precipitation of vanadium

[0090] The potential of the vanadium-containing solution is oxidized to -1020 mV by using an oxidant to obtain a pentavalent vanadium solution; the pentavalent vanadium solution is stirred for a second time at a temperature of 85° C., and solid-liquid separation is performed to obtain polysodium vanadate and a vanadium precipitation mother liquor.

[0091] Step 3: Ammonium salt washing

[0092] The detergent and the sodium polyvanadate are mixed at a mass ratio of ammonium ions in the detergent to vanadium ions in the sodium polyvanadate of 0.85:1, and then stirred for the third time at a temperature of 50°C, and the solid-liquid separation is performed to obtain ammonium polyvanadate and washing waste liquid.

[0093] Step 4: Calcination

[0094] The polyammonium vanadate is calcined at 540° C. for 40 minutes to obtain vanadium pentoxide.

[0095] In the vanadium-rich liquid with a higher impurity content, the vanadium ion concentration is 55 g / L, the ferrous ion concentration is 1.4 g / L, the aluminum ion concentration is 30 g / L, the sodium ion concentration is 20 g / L, and the zinc ion concentration is 12 g / L; the vanadium ions in the vanadium-rich liquid with a higher impurity content exist in the form of tetravalent vanadium.

[0096] The oxidant is sodium chlorate.

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

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

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

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

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

[0102] The vanadium pentoxide prepared from the vanadium-rich solution with a high impurity content in this embodiment was tested to have a vanadium precipitation rate of 99.076% and a purity of vanadium pentoxide product of 99.058%.

[0103] Example 4

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

[0105] Step 1: Pretreatment to remove iron

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

[0107] Step 2: Oxidation and precipitation of vanadium

[0108] The potential of the vanadium-containing solution is oxidized to -1000 mV by using an oxidant to obtain a pentavalent vanadium solution; the pentavalent vanadium solution is stirred for a second time at a temperature of 80° C., and solid-liquid separation is performed to obtain polysodium vanadate and a vanadium precipitation mother liquor.

[0109] Step 3: Ammonium salt washing

[0110] The detergent and the sodium polyvanadate are mixed in a mass ratio of ammonium ions in the detergent to vanadium ions in the sodium polyvanadate of 1:1, and then stirred for the third time at a temperature of 60°C, and the solid-liquid separation is performed to obtain ammonium polyvanadate and washing waste liquid.

[0111] Step 4: Calcination

[0112] The polyammonium vanadate is calcined at 550° C. for 30 minutes to obtain vanadium pentoxide.

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

[0114] The oxidant is sodium hypochlorite

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

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

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

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

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

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

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

[0122] 1. This specific implementation method uses a vanadium-rich liquid with a high impurity content as a raw material. The raw material not only has many types of impurity ions and high content, but also adds a hydrogen peroxide solution to the vanadium-rich liquid with a high impurity content for pretreatment to remove iron. The resulting precipitate is mainly iron hydroxide colloid. The surface of the iron hydroxide colloid is electronegative, and it will adsorb other metal cations in the vanadium-rich liquid with a high impurity content, thereby reducing the concentration of other impurity ions in the vanadium-rich liquid with a high impurity content. The impurity ion content in the vanadium-containing solution obtained after pretreatment to remove iron can be reduced to 20% compared with the impurity ion content in the vanadium-rich liquid with a high impurity content, while the vanadium ion concentration after pretreatment to remove iron remains basically unchanged, reducing the influence 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 more than 99% compared with the vanadium pentoxide product prepared from the vanadium-rich liquid with a high impurity content, and the purification and impurity removal effect is good. The vanadium pentoxide prepared in this specific implementation method is shown in the attached figure, Figure 1 The XRD diagram of the preparation of vanadium pentoxide using a vanadium-rich solution with a high impurity content in Example 1 is shown in FIG. Figure 1 It can be seen that the prepared vanadium pentoxide product has high crystallinity and contains only one phase of vanadium pentoxide, indicating that the vanadium pentoxide has high purity.

[0123] 2. This specific embodiment adopts the method of vanadium pentoxide precipitation-ammonium salt washing to prepare vanadium pentoxide. Compared with the ammonium salt precipitation process under the same solution system, the ammonium addition coefficient of this method is reduced from 4 to 6 to 0.5 to 1, and the ammonium consumption is reduced by more than 80%. The ammonium consumption is low. The ammonium ion concentration in the washing wastewater can be reduced from 10000 to 30000 mg / L to 100 to 300 mg / L compared with the ammonium ion concentration in the vanadium precipitation mother liquor of ammonium salt precipitation, which effectively reduces the difficulty of wastewater treatment, reduces the cost of wastewater treatment, and is more environmentally friendly.

[0124] 3. This specific implementation adopts the method of pretreatment with hydrogen peroxide solution to remove iron-oxidation precipitation of vanadium-ammonium salt washing to prepare vanadium pentoxide products with a purity greater than 99%. The 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 by cooling crystallization, further reducing the concentration of ammonium ions and chloride ions in the washing wastewater and reducing pollution to the environment.

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

Claims

1. A method for preparing vanadium pentoxide using a vanadium-rich solution with a high impurity content, characterized in that The method for preparing vanadium pentoxide is: Step 1: Pretreatment to remove iron According to the molar ratio of solute molecules in the hydrogen peroxide solution to ferrous ions in the vanadium-rich solution with a high impurity content of 14 to 18:1, the hydrogen peroxide solution is added to the vanadium-rich solution with a high impurity content to obtain a pretreatment solution; the pH value of the pretreatment solution is adjusted to 1.8 to 3.5 with a precipitant, and then the pretreatment solution is stirred for the first time at a temperature of 25 to 50° C., and solid-liquid separation is performed to obtain an iron-containing precipitate and a vanadium-containing solution; Step 2: Oxidation and precipitation of vanadium The vanadium-containing solution is oxidized to a potential of -1100 to -1000 mV by using an oxidant to obtain a pentavalent vanadium solution; the pentavalent vanadium solution is stirred for a second time at a temperature of 80 to 95° C., and solid-liquid separation is performed to obtain polysodium vanadate and a vanadium precipitation mother solution; Step 3: Ammonium salt washing The detergent and the sodium polyvanadate are mixed in a mass ratio of ammonium ions in the detergent to vanadium ions in the sodium polyvanadate of 0.5 to 1:1, and then stirred for a third time at a temperature of 30 to 60° C. to separate the solid and the liquid to obtain ammonium polyvanadate and a washing waste liquid; Step 4: Calcination The polyammonium vanadate is calcined at 500-550° C. for 30-60 minutes to obtain vanadium pentoxide.

2. The method for preparing vanadium pentoxide using a vanadium-rich solution with a high impurity content according to claim 1, characterized in that: In the vanadium-rich liquid with a high impurity content, the vanadium ion concentration is 20-70 g / L, the ferrous ion concentration is 0.2-2 g / L, the aluminum ion concentration is 20-40 g / L, the sodium ion concentration is 10-30 g / L, and the zinc ion concentration is 5-15 g / L; the vanadium ions in the vanadium-rich liquid with a high impurity content exist in the form of tetravalent vanadium.

3. The method for preparing vanadium pentoxide using vanadium-rich liquid with high impurity content according to claim 1, characterized in that: The oxidant is sodium chlorate or sodium hypochlorite.

4. The method for preparing vanadium pentoxide using vanadium-rich liquid with high impurity content according to claim 1, characterized in that: The precipitant is one of sodium carbonate solution, sodium bicarbonate solution and sodium hydroxide solution; the mass fraction of the precipitant is 15-20%.

5. The method for preparing vanadium pentoxide using vanadium-rich liquid with high impurity content according to claim 1, characterized in that: The first stirring time is 30 to 45 minutes, and the rotation speed is 400 to 500 r / min.

6. The method for preparing vanadium pentoxide using vanadium-rich liquid with high impurity content according to claim 1, characterized in that: The second stirring time is 60 to 90 minutes, and the rotation speed is 400 to 500 r / min.

7. The method for preparing vanadium pentoxide using vanadium-rich liquid with high impurity content according to claim 1, characterized in that: The third stirring time is 20 to 40 minutes, and the rotation speed is 400 to 500 r / min.

8. The method for preparing vanadium pentoxide using vanadium-rich liquid with high impurity content according to claim 1, characterized in that: The detergent is one of ammonium chloride solution, ammonium sulfate solution and ammonium bicarbonate solution; the mass fraction of the detergent is 2-5%.

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