WO2015161660A1

WO2015161660A1 - Method for preparing low-silicon vanadium pentoxide from solution containing vanadium, chromium and silicon

Info

Publication number: WO2015161660A1
Application number: PCT/CN2014/093865
Authority: WO
Inventors: 宁朋歌; 曹宏斌; 张懿
Original assignee: 中国科学院过程工程研究所
Priority date: 2014-04-21
Filing date: 2014-12-15
Publication date: 2015-10-29
Also published as: CN103937998B; CN103937998A; RU2645535C1

Abstract

A method for recycling and preparing low-silicon high-purity vanadium pentoxide (V₂O₅) from a mixed solution containing vanadium, chromium and silicon. The method comprises the following steps: firstly, silicon is removed from a solution containing vanadium, chromium and silicon using an amphoteric metal salt and/or an alkali metal salt, then other introduced impurities are removed by adjusting the pH value, and solid-liquid separation is performed; the vast majority of the vanadium is selectively extracted into an organic phase using a primary amine extraction system, the vanadium in the vanadium-rich organic phase is stripped using an alkaline solution containing an ammonium salt, and ammonium metavanadate precipitates out, and a water phase, after stripping has been performed, is filtered or centrifuged to obtain a high-purity ammonium metavanadate solid, and after washing and drying, calcination is performed at a certain temperature to obtain a brick-red substance, V₂O₅, having a purity of more than 99.9% and a silicon content of less than 0.007%. No interlayer is formed in the extraction-stripping process.

Description

Method for preparing low silicon vanadium pentoxide from vanadium containing chromium silicon solution

Technical field

The invention belongs to the field of hydrometallurgy or wastewater treatment, and relates to a method for preparing low silicon V ₂ O ₅ , in particular to a process for preparing low silicon high purity V ₂ O ₅ from a vanadium chromium silicon solution.

Background technique

Vanadium is a non-ferrous metal and is a very important strategic resource. Vanadium pentoxide (V ₂ O ₅ ) is an important oxide of vanadium and is the most widely used oxide. Its application range has expanded from metallurgical, chemical and other industries to aerospace, electronics, electrochemistry, etc. The market demand for high-purity V ₂ O ₅ is increasing, and the purity requirements for V ₂ O ₅ are also increasing, especially the development of vanadium flow batteries and vanadium-aluminum alloys, and the purity of vanadium in high-purity vanadium. And the content of impurity silicon raises higher requirements. However, since the chemical properties of vanadium (V) and chromium (VI) are very similar, vanadium and chromium often coexist in minerals, and the separation is difficult, making it difficult to obtain high-purity vanadium products.

For the preparation of high-purity V ₂ O ₅ , it is generally obtained by using a cheap and readily available industrial V ₂ O ₅ or other vanadate as a raw material, through a series of purification steps and purification treatment. For example, Park Changlin uses crude V ₂ O ₅ with low chromium content as raw material to produce high purity vanadium with chromium, iron content <0.005% and vanadium grade >99.9% by molten salt electrolytic refining method. CN 102764894A uses a vanadium block as a raw material, and obtains high-purity vanadium powder by hydrogenation, grinding and dehydrogenation. The preparation methods of these high-purity vanadium are all based on the processed industrial grade products, the source is limited and the cost is high, and the high requirements on the raw materials limit the promotion of these methods. The vanadium-containing chromium solution has a wide range of sources and has a great impact on the environment. How to use the vanadium-containing chromium solution more effectively has become one of the current research topics.

So far, various techniques have been developed to treat vanadium-containing chromium solutions. One of the more traditional methods is chemical precipitation, that is, by adding various kinds of solutions to neutral or weakly alkaline conditions. Remove impurities, such as calcium chloride, magnesium chloride, aluminum chloride, aluminum sulfate, oxalic acid, sulfosalicylic acid, etc., remove impurities in the solution, and then add ammonium salts such as ammonium sulfate, ammonium chloride, etc. to precipitate vanadium, resulting in Ammonium metavanadate, ammonium metavanadate is then washed and recrystallized to produce high purity vanadium. This method is simple to operate, but the steps are cumbersome, the purity of the product is not high and the vanadium loss is large. Another ion exchange method is a relatively new method. Although its production process is simple, the reagent consumption is small, and the vanadium recovery rate is high, the impurities in the solution easily adhere to the resin surface during the ion exchange process, resulting in resin exchange. The decrease in capacity may even cause the resin to be "poisoned" and the operating conditions are harsh, which has not yet gained popularity in the industry.

Extraction is a widely used method. The extraction method has many advantages, such as good separation effect, high recovery rate, recyclable extractant, low production cost, high product purity, etc., but due to the influence of impurities, the extraction system forms a third phase. A number of extractants for vanadium extraction have been reported, including: Cyanex 272, PC88A, TR-83, Adongen 464, Aliquat 336, N263, and quaternary ammonium salts. Related technologies such as CN 101121962 use extraction, stripping, vanadium and other operations to completely recover vanadium chromium in vanadium chromium solution, but the purity of its product vanadate can only reach 99.5%. CN103540745A is used for extracting heteropoly acid in vanadium solution to purify vanadium solution, adding ammonium salt to form vanadium and calcining to obtain vanadium pentoxide with purity greater than 99.9%, but it is required to form phosphorus molybdenum tungsten, silicon molybdenum tungsten in the raw material liquid. Heteropolyacids are used for impurity removal, and are no longer suitable for other vanadium chromium solutions which are difficult to form heteropolyacids.

CN 102849795A uses crude ammonium metavanadate as raw material to obtain high-purity V ₂ O ₅ through alkali dissolution, impurity removal, multiple filtration, vanadium precipitation, calcination and the like, which not only has limited raw materials, but also has complicated operation and is unfavorable. Promote the application. CN 102923776A likewise uses crude ammonium metavanadate as raw material, and obtains 99.95% V ₂ O ₅ by alkali dissolution, pressurized ammonia, ultrasonic atomization, calcination, etc., but the requirements for equipment are relatively high, and the initial investment is relatively large. .

CN 100497675A discloses a novel process for completely recovering vanadium and chromium from a mixture of vanadium (V) chromium (VI). The main steps include: firstly using a secondary mixed amine amine extractant in a countercurrent contact with vanadium (V). The aqueous solution of chromium (VI) is contacted and extracted, and most of the vanadium and a small amount of chromium in the water are extracted into the organic phase, and most of the chromium remains in the aqueous phase; then the pH of the raffinate (aqueous phase) is adjusted with acid and added The reducing agent is subjected to a reduction reaction, and then the pH of the aqueous solution is adjusted by sodium hydroxide, and then filtered, and the obtained solid is hydrated chromium oxide, and the lye is used as a stripping agent to carry vanadium from the vanadium-rich organic phase by countercurrent contact. The mixture is extracted into the water; the vanadium is separated from the solution by ammonium ammonium metaphosphate method by ammonium salt precipitation method; finally, the vanadium-doped supernatant is treated by high-efficiency distillation technology, the concentrated ammonia water is obtained at the top of the tower, and the deammonia water is obtained from the tower. , return directly to the extraction process. The method can prepare vanadium pentoxide with a purity higher than 99.5%, wherein the impurity content is mainly silicon, sodium, sulfur, chromium and the like.

In the current report, there are few processes that require low raw material and separate and prepare low-silicon high-purity V ₂ O ₅ directly from the vanadium-containing solution, so find a suitable process flow and low-cost preparation of low-silicon high-purity. V ₂ O _{5 is in} urgent need of solution.

Summary of the invention

The present invention is directed to a method of preparing low silicon high purity V ₂ O ₅ from a vanadium containing chromium silicon solution. Based on the analysis of the impurity removal behavior of each step of patent CN 100497675A, the invention focuses on the morphological chemistry of vanadium chromium silicon, and determines a series of basic data of ammonium metavanadate solubility for the ammonium vanadium precipitation process to establish a thermodynamic model. The solubility of ammonium metavanadate in the presence of different impurities was scientifically predicted, and the process adjustments such as changing the modifier composition, optimizing the desiliconization process step, and combining the stripping vanadium process were proposed. The method of the invention has the advantages of simple process, low cost and convenient industrialization. The high purity V ₂ O ₅ impurity prepared by the method of the invention has low impurity content, silicon content <0.007%, and purity can reach 99.9% or more.

The principle of the method of the invention is as follows: firstly, the silicon in the mixture of vanadium (V) chromium (VI) and other impurities is removed by using the amphoteric metal salt and/or the alkali metal salt, and no other impurities are introduced; then the primary amine extraction system is used. Selectively extracting most of the vanadium into the organic phase, and then extracting vanadium in the vanadium-rich organic phase with a mixture of alkali and ammonium salts and precipitating ammonium metavanadate, and the obtained ammonium metavanadate is washed and dried. After that, it is calcined at a certain temperature to obtain low-silicon high-purity V ₂ O ₅ , and the vanadium-bearing liquid can be returned to the vanadium raw liquid for re-treatment.

In order to achieve the above object, the present invention adopts the following technical solutions:

A method for preparing V ₂ O ₅ from a vanadium-containing chromium silicon solution, comprising the steps of:

1) mixing the amphoteric metal salt and/or the alkali metal salt with the vanadium-containing chromium silicon solution to remove most of the silicon silicon in the solution, and after cooling to room temperature, the other impurities in the solution are lowered by adjusting the pH, which is an amphoteric metal salt and / or metal impurities introduced by the alkali metal salt, and solid-liquid separation, collecting the supernatant; separating the solid liquid, most of the silicon in the water sinks in solid form, collecting the liquid;

2) Adjusting the pH of the supernatant obtained in the step 1) to an acidity, preferably 2 to 6, for example, 2.4, 3.1, 5, 5.8, etc., and then extracting with a primary amine extraction system, extracting vanadium into the organic phase, leaving chromium In the raffinate; most of the vanadium can be selectively extracted into the organic phase, and most of the chromium and other impurities remain in the raffinate;

Optionally, 3) adjusting the pH of the raffinate obtained in step 2) with an acid, adding a reducing agent to carry out a reduction reaction, and then adjusting the pH of the aqueous solution with an alkali to filter, thereby obtaining a solid hydrated chromium oxide;

4) Step 2) The obtained vanadium-rich organic phase is back-extracted with a mixture of an alkali solution and an ammonium salt and precipitates ammonium metavanadate;

The solution after optional vanadium is returned to step 1) and the treatment is carried out again; the solution obtained after the vanadium precipitation can be directly transported back to the vanadium raw liquid for the next round of separation and recovery process, which can recycle ammonia and save cost;

5) The ammonium metavanadate obtained in the step 4) is washed, dried, and calcined to obtain low-silicon high-purity V ₂ O ₅ .

According to a preferred embodiment of the present invention, the vanadium-containing chromium-silicon solution is a mixture of one or more of a vanadium-containing chromium-containing slag leaching solution, a vanadium-containing waste leaching liquid, and a plant-containing vanadium-containing wastewater. Non-industrial grade vanadate products, even with silicon, can obtain low silicon and high purity V ₂ O ₅ ;

As a preferred technical solution, in the method of the present invention, the amphoteric metal salt in the step 1) is an aluminum salt, preferably one of Al ₂ (SO ₄ ) ₃ , Al(OH) ₃ , AlCl ₃ or NaAlO ₂ . Or a mixture of two or more kinds; the invention can remove the silicon in the solution to less than 30 mg/L by using only the aluminum salt as the desiliconizing agent according to the morphological bonding mode and the route between the aluminum and the silicon, so that the subsequent extraction process runs smoothly and Technical support is provided for low-cost preparation of low-silicon high-purity vanadium, in which Al ₂ (SO ₄ ) ₃ , Al(OH) ₃ , and AlCl ₃ have achieved particularly good effects, and silicon can be removed to less than 10 mg/L. The alkali metal salt is one or a mixture of two or more of Ca(OH) ₂ , CaCl ₂ , CaO, NaOH, and KOH.

Preferably, the molar ratio of the combination of the amphoteric metal salt and/or the alkali metal salt to silicon is from 0.5:1 to 2.0:1, for example, 0.8:1, 1.1:1, 1.5:1, 1.9:1, etc. .

As a preferred technical solution, in the method of the present invention, the reaction temperature for removing silicon in the step 1) is 30 to 90 ° C, for example, 32 ° C, 45 ° C, 52 ° C, 60 ° C, 71 ° C, 80 ° C, 88 ° C, and the like. , the reaction time is 20 to 150 minutes, for example, 50 minutes, 90 minutes, 120 minutes, 145 minutes, etc.;

Preferably, the manner of mixing is shaking or agitation.

Preferably, the pH is 7.5 to 9.0, for example, 7.9, 8.2, 8.7, etc., and the temperature at the time of pH adjustment is 15 to 40 ° C, for example, 19 ° C, 25 ° C, 32 ° C, 37 ° C, and the like.

As a preferred technical solution, in the method of the present invention, the primary amine extraction system in step 2) is a mixture of a primary amine, a modifier and a diluent; wherein the primary amine may be a linear chain having 14 to 24 carbon atoms or A branched primary amine (such as LK-N21, JMT, N1923, N116, 7101, etc.) has a content of 3 to 30% by weight.

Preferably, the modifier may be an ester, preferably one or two of hexyl acetate, amyl acetate, ethyl p-methyl carbamate, t-butyl acetate, and diisopropyl succinate. combination.

The diluent may be a pure substance or a mixture of an organic substance such as sulfonated kerosene, cyclopentane, n-pentane, cyclohexane, n-hexane, benzene, toluene, xylene, chloroform or carbon tetrachloride; 4:1～1:4 (volume); the extraction temperature is 10-40 ° C, the equilibrium pH is 6.5-9.0, and the extraction time is 3-60 min;

Preferably, the modifier has a concentration of from 2 wt% to 10 wt%, for example, 4 wt%, 6 wt%, 9 wt%, and the like.

Preferably, the pH after pH adjustment in the step 3) is from 1 to 6, for example 1.5, 2.6, 3.5, 5.0, 5.8, etc., preferably from 2 to 4.

Preferably, the pH after adjusting the pH with a base is 7 to 10, for example, 7.3, 7.9, 8.5, 9.2, 9.9, etc., preferably 7 to 9.

As a preferred technical solution, in the method of the present invention, the stripping and vanadium precipitation are carried out simultaneously in the step 4), and the alkali solution is one or two kinds of NaOH solution, KOH solution, Ca(OH) ₂ solution or ammonia water. The above mixing, preferably at a concentration of 0.5 wt% to 6 wt%, for example, 0.8 wt%, 1.5 wt%, 2.0 wt%, 4.0 wt%, 5.5 wt%, etc.;

Preferably, the ammonium salt is one or a mixture of two or more of (NH ₄ ) ₂ CO ₃ , NH ₄ NO ₃ , NH ₄ Cl or (NH ₄ ) ₂ SO ₄ , preferably at a concentration of 0.05 to 0.6 M. For example, it is 0.0.2M, 0.25M, 0.4M, 0.5M, and the like.

The present invention is back-extracted in a vanadium-rich organic phase with a mixture of an alkali solution and an ammonium salt, such that stripping and vanadium precipitation are carried out simultaneously, as compared to the scheme disclosed in CN 100497675 A, which separates stripping and precipitation. The invention not only greatly simplifies the treatment process, but also has a lower silicon content in the prepared ammonium metavanadate and the subsequent vanadium pentoxide. The silicon in the vanadium pentoxide prepared under the optimal conditions is not detected, and the vanadium pentoxide particles are not detected. It is finer, has a larger specific surface area and uniform particles, and because of the addition of an appropriate amount of ammonium salt, the phenomenon of interface emulsification in the most frequently encountered stripping process does not occur, the oil-water interface is clear, easy to separate, and combined with silicon removal and selective extraction of vanadium. The process can obtain good technical effects, such as the purity of the product V ₂ O ₅ is over 99.9%.

As a preferred technical solution, in the method of the present invention, the volume ratio of the organic phase to the mixed solution of the alkali solution and the ammonium salt in the step 4) is 1:1 to 10:1, for example, 2:1, 5:1, 8: 1.

Preferably, the temperature of the stripping is 30 to 70 ° C, for example, 35 ° C, 40 ° C, 55 ° C, 62 ° C, etc., and the stripping time is 0.5 to 5 h, for example, 0.8 h, 1.2 h, 2.5 h, 3.4. h, 4.5h, etc.

As a preferred technical solution, the method of the present invention, the washing in the step 5) is repeated multiple times, preferably by centrifugal washing and/or filtering; the washing liquid may be (NH ₄ ) ₂ SO ₄ , NH ₄ Cl a solution of (NH ₄ ) ₂ CO ₃ or NH ₄ NO ₃ at a concentration of 0 to 0.4 M, for example, 0.1 M, 0.25 M, 0.3 M, 0.36 M, etc., and the amount of the washing liquid per time is 0.5 of the stripping solution. ~1 times, when it is 0, it can be washed with pure water.

Preferably, the drying temperature is 40 to 110 ° C, for example, 45 ° C, 60 ° C, 75 ° C, 86 ° C, 95 ° C, 105 ° C, and the like. Drying can be air drying or drying ammonium metavanadate.

As a preferred technical solution, in the method of the present invention, the calcination temperature in the step 5) is 200 to 600 ° C, for example, 240 ° C, 280 ° C, 350 ° C, 400 ° C, 520 ° C, etc., and the time is 1 to 4 h, for example, It is 1.3h, 2.2h, 3.0h, 3.5h, 3.8h, etc. After calcination, a brick red solid powder V ₂ O _{5 was obtained} .

The advantages of the method provided by the present invention are:

1) The invention uses an amphoteric metal salt or an alkali metal salt as a silicon removal agent, which can remove most silicon impurities in the solution, so that the silicon content in the solution is less than 10 mg/L, and the pH adjustment process can introduce almost no new ions. Compared with other aluminum salts such as NaAlO ₂ , not only the raw materials are easily available, but also the removal efficiency of silicon is better and the cost is lower.

2) The present invention uses a primary amine extraction system as an extractant to selectively separate vanadium and chromium at a low temperature, and has a good separation effect between vanadium and impurities, and has a simple process flow and low cost compared with other processes, and is suitable for large-scale industrial production.

3) The invention can obtain ultra-high purity low-silicon ammonium metavanadate by using silicon removal, selective extraction of vanadium, and combined with alkali and ammonium salt vanadium, which is convenient for subsequent operation to obtain other vanadium products.

4) Another advantage of the present invention is that the vanadium-bearing liquid can be directly returned to the silicon removal operation after deamination, so that the resources are fully recovered and utilized.

The invention can obtain low silicon high purity V ₂ O ₅ (such as silicon content <0.007%) and V ₂ O ₅ content ≥99.9% by de-siliconization, selective extraction of vanadium, and combined with ammonia precipitation vanadium calcination multi-process coupling. Greatly improve the quality and value of the product. The obtained high-purity V ₂ O ₅ can be widely used in the fields of catalysts, batteries, aerospace, electronic components and the like.

DRAWINGS

1 is a process flow for preparing low silicon high purity V ₂ O ₅ from a vanadium chromium solution;

Figure 2 shows the extraction interface during the stripping + vanadium precipitation process.

detailed description

To facilitate an understanding of the invention, the invention is set forth below. It should be understood by those skilled in the art that the present invention is only to be construed as a

Example 1

A method for preparing high purity V ₂ O ₅ from a vanadium chromium silicon solution, comprising the following steps:

1) 250 ml of a solution containing pentavalent vanadium and hexavalent chromium is placed in a beaker, and heated to a temperature of 90 ° C in a water bath. After stabilization, 5.86 g of AlCl ₃ and 1.547 g of CaO are added, and the mixture is stirred for 30 minutes, and then cooled to room temperature. The pH was adjusted to 8.8 with sulfuric acid, and after stirring for 5 minutes, the solid solution was centrifuged;

2) The collected silicon removal solution is adjusted to 4.2 with sulfuric acid, and then mixed with a primary amine extractant (containing 10% JMT, 5% hexyl acetate and 85% kerosene) in a ratio of 1:1, and stirred at 30 ° C. 5min, let stand to completely separate the oil and water;

3) The raffinate (aqueous phase) is added with sulfuric acid to adjust the pH to 3, and then a theoretical amount of 1 times anhydrous sodium sulfite is added to the solution, and after 30 minutes of reaction, the pH is adjusted to 7 with NaOH, and hydrated chromium oxide is obtained by filtration;

4) The vanadium-rich organic phase was stirred with 50 ml of the stripping solution (ammonia 2%, NH ₄ Cl 0.1 M, NH ₄ NO ₃ 0.1 M) at 50 ° C for 30 min, and allowed to stand completely until the oil and water were completely separated. After filtration, ammonium metavanadate can be obtained; Figure 2 shows the extraction interface during the stripping + vanadium precipitation process, the extraction interface is clear, and the extraction phase separation is good;

5) After the ammonium metavanadate was dried at 50 ° C and calcined at 300 ° C for 1.5 h, a brick red product vanadium pentoxide (V ₂ O ₅ ) was obtained.

Its purity is ≥99.9% by analysis and silicon content is <0.007%.

Example 2

1) 500 ml of a solution containing pentavalent vanadium and hexavalent chromium is placed in a beaker, and after heating at a constant temperature in a water bath to 60 ° C, 5.86 g of Al ₂ (SO ₄ ) ₃ and 0.751 g of CaCl _{2 are added} , and the stirring paddle is stirred. After 40 min, cooled to room temperature, the pH was adjusted to 7.7 with sulfuric acid, and after stirring for another 10 minutes, the solid solution was centrifuged;

2) The collected silicon removal solution is adjusted to 3.6 with sulfuric acid, and then mixed with a primary amine extractant (containing 15% JMT, 5% p-methyl ethyl formate and 80% kerosene) in a ratio of 2:1, at 25 Stir at °C for 20min, let stand to completely separate the oil and water;

3) The raffinate (aqueous phase) is added with sulfuric acid to adjust the pH to 3.4, and then a theoretical amount of 1.03 times of anhydrous sodium sulfite is added to the solution, and after 40 minutes of reaction, the pH is adjusted to 7.2 with NaOH, and hydrated chromium oxide is obtained by filtration;

4) The vanadium-rich organic phase is stirred at 40 ° C for 60 min with 200 ml of the stripping solution (NaOH 2%, (NH ₄ ) ₂ SO ₄ is 0.3 M), and allowed to stand completely until the oil and water are completely separated. Obtaining ammonium metavanadate;

5) After the ammonium metavanadate was dried at 70 ° C, it was calcined at 400 ° C for 2 h to obtain a vanadium red product vanadium pentoxide (V ₂ O ₅ ).

Its purity is ≥99.9% by analysis and silicon content is <0.007%.

Example 3

1) 1000 ml of a solution containing pentavalent vanadium and hexavalent chromium is placed in a beaker, and after heating at a constant temperature in a water bath to 70 ° C, 1.056 g of Al(OH) ₃ and 0.7 g of CaCl _{2 are added} , and the stirring paddle is stirred for 50 minutes. , cooled to room temperature, adjusted to pH 8.0 with sulfuric acid, stirred for another 10 minutes, and then centrifuged to separate the solid liquid;

2) The collected silicon removal solution was adjusted to 3.4 with sulfuric acid, and then mixed with a primary amine extractant (containing 15% N1923, 6% p-ethyl methyl formate and 79% kerosene) in a ratio of 3:1, at 20 Stir at °C for 30min, let stand to completely separate the oil and water;

3) The raffinate (aqueous phase) is added with sulfuric acid to adjust the pH to 2.5, and then a theoretical amount of 1.2 times anhydrous sodium sulfite is added to the solution, and after 30 minutes of reaction, the pH is adjusted to 8 with NaOH, and hydrated chromium oxide is obtained by filtration;

4) The vanadium-rich organic phase was stirred with a 500 ml stripping solution (KOH 3%, NH ₄ Cl 0.1 M, (NH ₄ ) ₂ SO ₄ 0.3 M) at 55 ° C for 60 min, and allowed to stand completely until the oil and water were completely separated. The solid in the phase is filtered to obtain ammonium metavanadate;

5) After the ammonium metavanadate is dried at 60 ° C and calcined at 500 ° C for 2 h, a brick red product vanadium pentoxide (V ₂ O ₅ ) is obtained.

Its purity is ≥99.9% by analysis and silicon content is <0.007%.

Example 4

1) 2000ml of a solution containing pentavalent vanadium and hexavalent chromium is placed in a beaker, heated to 80 ° C in a water bath, and then stabilized. Add 2.5 g of NaOH, 14.66 g of Al ₂ (SO ₄ ) ₃ , stir the paddle for 60 min. After cooling to room temperature, the pH was adjusted to 8.5 with sulfuric acid, and after stirring for 15 minutes, the solid solution was centrifuged;

2) The collected silicon removal solution is adjusted to 3.0 with sulfuric acid, and then mixed with a primary amine extractant (containing 20% N1923, 7% diisopropyl succinate and 73% kerosene) in a ratio of 4:1. Stir at 30 ° C for 40 min, let stand until the oil and water are completely separated;

3) The raffinate (aqueous phase) is added with sulfuric acid to adjust the pH to 3.5, and then a theoretical amount of 1.4 times of anhydrous sodium sulfite is added to the solution. After 40 minutes of reaction, the pH is adjusted to 7.5 with NaOH, and chlorination is obtained by filtration. chromium;

4) The vanadium-rich organic phase was stirred at 60 ° C for 2 h with 800 ml of the stripping solution (NaOH 4%, NH ₄ Cl 0.1 M, (NH ₄ ) ₂ C0 ₃ 0.3 M), and allowed to stand completely until the oil and water were completely separated. The solid in the phase is filtered to obtain ammonium metavanadate;

5) Ammonium metavanadate was dried at 700 ° C and calcined at 450 ° C for 2 h to obtain vanadium red pentoxide (V ₂ O ₅ ).

Its purity is ≥99.9% by analysis and silicon content is <0.007%.

Comparative example

A method for preparing high purity V ₂ O ₅ from a vanadium chromium silicon solution, the vanadium chromium silicon solution used is the same as in Example 4, and the treatment step is carried out in accordance with the method disclosed in CN 100497675A.

After testing, the obtained vanadium pentoxide purity is ≥99.6%, and the silicon content is <0.06%.

It can be seen that the product obtained by the treatment method of the invention has higher purity and lower impurity silicon content.

The Applicant declares that the present invention illustrates the detailed process equipment and process flow of the present invention by the above embodiments, but the present invention is not limited to the above detailed process equipment and process flow, that is, does not mean that the present invention must rely on the above detailed process equipment and The process can only be implemented. It should be apparent to those skilled in the art that any modifications of the present invention, equivalent substitution of the various materials of the products of the present invention, addition of auxiliary components, selection of specific means, and the like, are all within the scope of the present invention.

Claims

A method for preparing V 2 O 5 from a vanadium-containing chromium silicon solution, comprising the steps of:

1) mixing the amphoteric metal salt and/or the alkali metal salt with the vanadium-containing chromium silicon solution to remove silicon, and after cooling to room temperature, reducing the introduction amount of other impurities in the solution by adjusting the pH value, and performing solid-liquid separation, collecting the supernatant liquid;

2) adjusting the pH of the supernatant obtained in the step 1) to acidity, extracting with a primary amine extraction system, extracting vanadium into the organic phase, and leaving the chromium in the raffinate;

Optionally, 3) adjusting the pH of the raffinate obtained in step 2) with an acid, adding a reducing agent to carry out a reduction reaction, and then adjusting the pH of the aqueous solution with a base, followed by filtration to obtain a solid hydrated chromium oxide;

4) Step 2) The obtained vanadium-rich organic phase is back-extracted with a mixture of an alkali solution and an ammonium salt and precipitates ammonium metavanadate;

The solution after optionally adding vanadium is returned to step 1) and processed again;

5) The ammonium metavanadate obtained in the step 4) is washed, dried, and calcined to obtain low-silicon high-purity V 2 O 5 .
The method according to claim 1, wherein the vanadium-containing chromium-silicon solution is a mixture of one or more of vanadium-containing chromium-containing slag leachate, vanadium-containing waste leachate, and plant vanadium-containing waste water.
The method according to claim 1, wherein said amphoteric metal salt in step 1) is an aluminum salt, preferably 1 of Al 2 (SO 4 ) 3 , Al(OH) 3 , AlCl 3 or NaAlO 2 . a mixture of two or more kinds; the alkali metal salt is one or a mixture of two or more of Ca(OH) 2 , CaCl 2 , CaO, NaOH, and KOH;

Preferably, the molar ratio of the combination of the amphoteric metal salt and/or the alkali metal salt to silicon is from 0.5:1 to 2.0:1.
The method according to claim 1, wherein the reaction temperature for removing silicon in step 1) is 30 to 90 ° C, and the reaction time is 20 to 150 min;

Preferably, the manner of mixing is shaking or stirring;

Preferably, the pH is 7.5 to 9.0, and the temperature at the time of pH adjustment is 15 to 40 °C.
The method of claim 1 wherein the primary amine extraction system in step 2) is a mixture of a primary amine, a modifier and a diluent;

Preferably, the modifier is an ester, preferably a combination of one or two of hexyl acetate, amyl acetate, ethyl p-methyl carbamate, t-butyl acetate, and diisopropyl succinate. ;

Preferably, the modifier has a concentration of from 2% by weight to 10% by weight.
The method according to claim 1, wherein the pH after the pH adjustment in the step 3) is 1 to 6, preferably 2 to 4;

Preferably, the pH after adjusting the pH with a base is from 7 to 10, preferably from 7 to 9.
The method according to claim 1, wherein in step 4), the stripping and vanadium precipitation are carried out simultaneously, and the alkali solution is one or two of NaOH solution, KOH solution, Ca(OH) 2 solution or ammonia water. More than the above mixing, preferably in a concentration of 0.5 wt% to 6 wt%;

Preferably, the ammonium salt is one or a mixture of two or more of (NH 4 ) 2 CO 3 , NH 4 NO 3 , NH 4 Cl or (NH 4 ) 2 SO 4 , preferably at a concentration of 0.05 to 0.6 M. .
The method according to claim 1, wherein the volume ratio of the organic phase to the mixture of the alkali solution and the ammonium salt in step 4) is from 1:1 to 10:1;

Preferably, the temperature of the stripping is 30 to 70 ° C, and the time of stripping is 0.5 to 5 h.
The method of claim 1 wherein said washing in step 5) is repeated multiple times, preferably by centrifugation and/or filtration;

Preferably, the drying temperature is 40 to 110 °C.
The method of claim 1 wherein the calcination temperature in step 5) is from 200 to 600 ° C for a period of from 1 to 4 hours.