A novel preparation method for controllable valence vanadium oxide

Abstract

The present invention relates to a novel preparation method of vanadium oxide with controllable valence state, comprising the following steps: S1, removing impurities and purifying vanadium-containing leaching solution of vanadium resources to obtain vanadium precipitation mother liquor, adjusting the pH, and obtaining a liquid to be reacted; wherein the vanadium in the vanadium precipitation mother liquor is pentavalent, the vanadium concentration is 0.5-50g / L, and the pH is adjusted in the range of 0-7; S2, slowly adding choline organic matter to the liquid to be reacted obtained in step S1, mixing, and fully reacting, wherein the amount of choline organic matter added is n 有机物 :n 钒 The reaction mixture obtained in step S2 is filtered, and the solid vanadium precipitate is washed, dried, and calcined to obtain a vanadium oxide product with a controllable valence state. The method of the present invention has a short process flow, high reaction efficiency, and simple operation. It is suitable for treating vanadium-containing solutions of various concentrations, and is particularly suitable for solutions with high vanadium concentrations.

Description

Technical Field

[0001] The invention belongs to the technical field of hydrometallurgy, and in particular relates to a novel preparation method of vanadium oxide with controllable valence. Background Art

[0002] Vanadium precipitation process is a key step in the vanadium production process. The vanadium precipitation rate and the impurity content in the precipitate are directly related to the economic benefits of the enterprise.

[0003] Traditional vanadium precipitation processes have numerous limitations. For example, the world's earliest hydrolysis vanadium precipitation process, which adjusts the pH of a vanadium-rich solution by adding an inorganic acid, hydrolyzes the vanadium in the solution under heating and stirring, producing a reddish-brown precipitate. This results in low product purity and high acid consumption. Calcium and iron salt vanadium precipitation processes, on the other hand, use calcium- or iron-based precipitants to convert the vanadium in the solution into low-solubility vanadates, enabling separation. This prevents direct production of the final vanadium product, resulting in complex subsequent processes and limited applicability. Currently, ammonium salt precipitation is primarily used industrially. By adding ammonium salts as vanadium precipitants, under heating and stirring, vanadate ions in the solution preferentially combine with ammonium ions to form a polyammonium vanadate precipitate. However, this process generates significant amounts of ammonia nitrogen wastewater, causing severe environmental pollution and significantly reducing both environmental and social benefits.

[0004] Based on the shortcomings of traditional vanadium precipitation process, some scholars have proposed several new vanadium precipitation processes:

[0005] 1. The advantages of the melamine vanadium precipitation process include low cost, no sodium sulfate byproduct, high vanadium precipitation rate, and easy-to-treat wastewater. However, the principle of vanadium precipitation and the impact of impurities are unclear, resulting in high requirements for impurity ions in the solution. Furthermore, melamine decomposes at around 300°C to produce cyanide gas, while the temperature required for calcination to produce vanadium oxide is generally greater than 450°C. Melamine that is not completely converted during the precipitation process may produce harmful gases during the subsequent calcination, increasing the environmental cost of treating the waste gas.

[0006] The advantage of the urea vanadium precipitation process is that it can reduce or even eliminate local over-concentration, thereby achieving high-purity vanadium products from vanadium-rich liquids with multiple impurities through a single precipitation step. This eliminates the need for impurity ion removal, greatly simplifies the process, and reduces reagent consumption. However, this process still produces ammonia nitrogen wastewater, presenting environmental risks and not in line with the concept of green production.

[0007] 3. The high-pressure hydrogen reduction vanadium precipitation process solves the ammonia nitrogen problem at its source, avoiding the generation of ammonia nitrogen wastewater and the emission of waste gas. It also enables the recycling of vanadium precipitation wastewater, and the resulting products have higher added value, offering favorable environmental and economic benefits. However, the catalyst, palladium chloride, is expensive and difficult to recover from vanadium precipitation products, and alternatives are difficult to find. Furthermore, hydrogen is flammable and explosive, and high-pressure experiments are highly hazardous. These factors hinder the industrial application of the high-pressure hydrogen reduction process in vanadium precipitation.

[0008] 4. The oxalic acid hydrothermal vanadium precipitation process solves the ammonia nitrogen problem at its source, avoiding the generation of ammonia nitrogen wastewater and the emission of waste gas. It also achieves a shortened process for the preparation of NaVO5 and VO2(B), significantly saving time and cost. The product has a higher added value, resulting in good economic and environmental benefits. However, this process is only effective when the vanadium concentration in the vanadium-rich solution is high, limiting its scope of application. Furthermore, the significant differences in the properties of different vanadium-rich solutions make the reaction process very complex, making it difficult to determine the reaction progress. Therefore, this process has not yet been widely adopted in industrial applications.

[0009] Therefore, efficient and clean vanadium precipitation processes are essential for the green and sustainable development of vanadium, thereby bringing direct comprehensive benefits and meeting the requirements of my country's modern industrial upgrading and environmental protection. In summary, we are actively seeking new, environmentally friendly and safe vanadium precipitation agents to replace ammonium salts, reduce the pressure placed by vanadium precipitation processes on subsequent water treatment processes, and produce high-value-added vanadium products. Summary of the Invention

[0010] The purpose of the present invention is to solve the above technical problems and provide a novel preparation method of controllable valence vanadium oxide which is pollution-free, economical, safe, environmentally friendly and has high product purity.

[0011] To achieve the above-mentioned purpose, the technical solution of the present invention is as follows: The technical solution of the present invention is: a new method for preparing vanadium oxide with controllable valence, comprising the following steps:

[0012] S1: After removing impurities and purifying the vanadium (V)-containing leachate from vanadium resources (vanadium-titanium magnetite, vanadium slag, vanadium-containing stone coal, vanadium potassium uranium ore, etc.), a vanadium precipitation mother liquor is obtained, and the pH is adjusted to obtain a reaction solution; the vanadium in the vanadium precipitation mother liquor is pentavalent, and the vanadium concentration is 0.5-50 g / L; the pH is adjusted in the range of 0-7.

[0013] S2: Slowly add a choline-based organic compound (such as choline chloride) to the reaction solution obtained in step S1, mixing and reacting. The ratio of the choline-based organic compound added is 0.1 to 10 (n(organic compound):n(vanadium). The reaction temperature is 70 to 100°C, and the reaction time is 0.5 to 3 hours. Choline chloride changes its properties in an acidic solution. The choline cations attract the negative charges on the surface of the vanadium oxy groups and form chemical bonds with them, thereby achieving a shape-changing effect.

[0014] S3: The reaction solution obtained in step S2 is filtered, and the solid vanadium precipitate is washed, dried, and calcined to obtain a vanadium oxide product with a controlled valence state. Deionized water or anhydrous ethanol is used for washing. The calcination temperature is 400-700°C, and the calcination time is 2-8 hours. The calcination atmosphere can be controlled to be air, oxygen, nitrogen, argon, etc.

[0015] The molar ratios used in the present invention are all molar ratios unless otherwise specified.

[0016] Compared with the prior art, the present invention has at least the following advantages:

[0017] 1. Using choline organic matter to precipitate vanadium, the product can be regulated by controlling the reaction conditions and calcination conditions, that is, vanadium oxides with different valence states can be obtained.

[0018] 2. Compared with the traditional vanadium precipitation agent ammonium salt, the nitrogen element contained in choline organic matter plays a major reactive role in the vanadium precipitation process, and the vanadium precipitation wastewater is easy to treat.

[0019] 3. The nitrogen in the choline organic matter reacts with the vanadium group to produce a substance with lower solubility that precipitates out, thereby achieving the extraction of vanadium.

[0020] 4. The calcination process controls the calcination atmosphere and the gas components produced are harmless to the environment.

[0021] 5. The method of the present invention has a short process flow, high reaction efficiency, and simple operation. It is applicable to the treatment of vanadium-containing liquids of various concentrations, and is particularly applicable to vanadium-containing liquids with high vanadium concentrations. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a simplified flow chart of the method of the present invention. DETAILED DESCRIPTION

[0023] The present invention is described in further detail below.

[0024] 1. Common low-valent vanadium oxides (such as V2O3 and VO2) require reduction of high-valent vanadium pentoxide (V2O5). The V2O5 production process generates large amounts of ammoniacal nitrogen wastewater and ammonia emissions. The reduction process also increases process complexity and financial investment. However, this invention eliminates the generation of large amounts of ammoniacal nitrogen wastewater and ammonia emissions during the production of low-valent oxides, making it more environmentally friendly. Furthermore, the absence of a reduction process makes it more economical and safer.

[0025] 2. The invention's product examples include vanadium trioxide and vanadium pentoxide (V2O3, V2O5). ICP-OES analysis of the vanadium content in the precipitated products revealed vanadium recoveries of 97.99% and 95.46%, respectively, significantly exceeding the 80-90% recovery rate of vanadium precipitated by hydrolysis. Therefore, the invention's products possess a higher purity.

[0026] 3. The modification of choline organic compounds occurs after the solution pH is adjusted and is not a separate modification. In acidic solutions, the acid promotes the reaction between choline organic compounds and the surface of the substance. The cations in the choline organic compounds attract the negative charges on the surface of the substance and form chemical bonds with the substance, thus achieving the modification effect. At the same time, vanadium (V) forms polyvanadate ions in acidic solutions, carrying a large negative charge, which is more conducive to reaction with choline organic compounds.

[0027] Example 1: The raw material of this example is sodium metavanadate solution, and the vanadium concentration in the solution is 30 g / L.

[0028] The method of preparing vanadium oxide by precipitating vanadium from a sodium metavanadate solution in this embodiment comprises the following steps:

[0029] (1) preparing a vanadium precipitation mother solution with a vanadium concentration of 30 g / L and adjusting the pH to 1 to obtain a reaction solution;

[0030] (2) The reaction solution obtained in step (1) was mixed with choline chloride in a ratio of n(choline chloride):n(vanadium)=1.25, and reacted at a reaction temperature of 90° C. and a reaction time of 2 h.

[0031] (3) The reaction solution obtained in step (2) is filtered, and the solid vanadium precipitate product is washed with deionized water, dried, and calcined at 550° C. for 3 h under an argon atmosphere to obtain a vanadium trioxide product.

[0032] The recovery rate of vanadium was 97.99%.

[0033] The process steps of Examples 2-10 are the same as those of Example 1, except for the process parameters, as shown in Table 1:

[0034] Table 1

[0035]

[0036] Processes S1 and S2 have a significant impact on vanadium recovery, while process S3 has a relatively small impact. In S1, vanadium recovery increases with increasing vanadium concentration. pH not only affects the form of vanadium but also has a certain influence on the activity of organic matter. At lower pH, vanadium recovery changes little, showing a slight upward trend with increasing pH. It reaches its maximum at pH 1.5 and then decreases with further increases in pH. In process S2, the amount of organic matter added has a significant impact on vanadium recovery. At low addition levels, recovery remains high. With increasing addition levels, vanadium recovery initially shows a slight change, followed by a gradual decrease. After the addition level reaches 2, the recovery shows a decreasing trend. In S3, temperature and time have minimal impact, with the main difference being that vanadium recovery increases with increasing temperature and time. When the temperature exceeds 550°C and the time exceeds 3 hours, the impact of both on vanadium recovery remains minimal.

[0037] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the purpose and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A novel method for preparing vanadium oxide with controllable valence, characterized in that: The following steps are involved: S1: After removing impurities and purifying the vanadium-containing leachate from the vanadium resource, a vanadium precipitation mother liquor is obtained, and the pH is adjusted to obtain a reaction solution; wherein the vanadium in the vanadium precipitation mother liquor is pentavalent, the vanadium concentration is 20-50 g / L, and the pH is adjusted to a range of 0.5-4; S2: Slowly add choline chloride to the reaction solution obtained in step S1 to mix and fully react, wherein the amount of choline chloride added is n 氯化胆碱 :n 钒 0.1~2; S3: The reaction solution obtained in step S2 is filtered, and the solid vanadium precipitation product is washed, dried, and calcined to obtain a controllable valence vanadium oxide product. The calcination temperature is 500-700° C. and the calcination time is 3-8 h.

2. The novel method for preparing vanadium oxide with controllable valence according to claim 1, characterized in that: The reaction temperature in S2 is 70-100° C., and the reaction time is 0.5-3 h.

3. The novel method for preparing a controllable valence vanadium oxide according to claim 1, characterized in that: In step S3, deionized water or anhydrous ethanol is used for multiple washing.

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