Process for the extraction and separation of vanadium from a vanadium-containing solution

Abstract

This invention relates to the field of vanadium metallurgy and discloses a method for extracting and separating vanadium from a vanadium-containing solution, comprising the following steps: S1, dissolving melamine in an aqueous solution containing urea to form a homogeneous solution; S2, adding the homogeneous solution to the vanadium-containing solution to carry out a vanadium precipitation reaction, obtaining the reacted material; S3, performing solid-liquid separation on the reacted material to obtain a vanadium precipitate, and calcining the vanadium precipitate to obtain vanadium pentoxide product. This invention achieves low-temperature, rapid, and high-utilization vanadium precipitation without generating ammonia nitrogen wastewater.

Description

Technical Field

[0001] This invention relates to the field of vanadium metallurgy, and more specifically to a method for extracting and separating vanadium from a vanadium-containing solution. Background Technology

[0002] Vanadium-titanium magnetite is the main mineral resource of vanadium. It is generally smelted in a blast furnace into vanadium-containing molten iron, which is then oxidized and blown in a converter to obtain vanadium slag. Vanadium slag is the main raw material for vanadium product preparation. It is usually roasted, leached, and impurity removed to obtain qualified vanadium solution. The qualified vanadium solution is then subjected to precipitation and calcination decomposition to obtain vanadium oxide products. In current industrial processes, the precipitation process of vanadium-containing solutions commonly uses ammonium salts (such as ammonium sulfate and ammonium chloride) as vanadium precipitants, recovering vanadium by generating ammonium metavanadate (NH4VO3) or ammonium polyvanadate (NH4VO3) precipitates. The ammonium salt precipitation process consumes a large amount of ammonium salt, with the molar ratio of ammonium salt to vanadium typically above 1.0, resulting in high reagent costs. Simultaneously, the vanadium precipitation wastewater contains NH4. + (Usually >5g / L) and high concentrations of SO4 2- The wastewater cannot be directly reused and requires the construction of an additional ammonia removal-evaporation concentration system, resulting in high investment and operating costs for the wastewater treatment process. To overcome the shortcomings of ammonium salt vanadium precipitation, many new vanadium precipitation technologies have emerged in recent years.

[0003] Patent CN111534698A discloses a method for preparing vanadium products by ammonium-free precipitation of vanadium from sodium vanadium solution. In this patent, organic acids (formic acid and / or acetic acid) are used for hydrolysis precipitation of vanadium at a pH of 6-8, achieving a precipitation rate of over 98%, and the resulting vanadium product contains over 56% vanadium. This technology eliminates the need for ammonium-containing vanadium precipitants, reducing ammonia nitrogen pollution. However, organic acids are expensive, and the wastewater treatment process for organic acids is not mentioned.

[0004] Patent CN104404274B discloses a method for precipitating and recovering vanadium from a vanadium-containing solution. In this patent, ammonium salt and hexamethylenetetramine are added to the oxidized vanadium-containing solution to react and precipitate ammonium polyvanadate crystals. The ammonium polyvanadate is then decomposed by heating to obtain vanadium pentoxide. This method has high vanadium precipitation efficiency, produces a high-density vanadium precipitate, and yields high-purity vanadium pentoxide. Furthermore, the operation is simple and the process is short. The use of hexamethylenetetramine allows vanadium in the solution to precipitate at room temperature, which helps reduce energy consumption during vanadium precipitation. However, under acidic conditions, hexamethylenetetramine decomposes to produce formaldehyde gas, necessitating consideration of formaldehyde recovery and disposal in industrial production.

[0005] Patent CN104357671B discloses a method for separating and recovering vanadium and chromium from vanadium-chromium slag, comprising the following steps: (1) immersing the vanadium-chromium slag in a sulfuric acid solution, filtering to obtain a filtrate containing vanadium and chromium ions; (2) precipitating the filtrate under alkaline conditions to obtain a liquid-solid mixture slurry; (3) adding an excess of oxidant to the liquid-solid mixture slurry to obtain a mixed solution containing high-valence vanadium and high-valence chromium ions; (4) adding melamine, a vanadium precipitant, under acidic and heated conditions to obtain a vanadium-containing precipitate and a filtrate; (5) calcining the vanadium-containing precipitate to vanadium pentoxide; cooling and allowing the filtrate to stand to precipitate sodium sulfate crystals and separate the chromium-containing filtrate; (6) precipitating the chromium-containing filtrate under alkaline conditions, and then evaporating the resulting clear liquid to obtain sodium chromate crystals. The molar ratio of melamine to vanadium in the vanadium-chromium slag in this technology is 0.5–2, requiring a relatively large amount, and the vanadium precipitation temperature is relatively high.

[0006] Patent CN106319214B discloses a method for directly precipitating vanadium from an acidic, multi-impurity vanadium-containing solution. Specifically, the method involves first adding an oxidant to the vanadium-containing solution to oxidize it. The amount of oxidant added is 1.0 to 2.5 times the theoretical molar amount of oxidant required to oxidize all low-valent vanadium in the solution to pentavalent vanadium. Then, urea is added to the oxidized vanadium solution at a mass ratio of urea to vanadium pentoxide in the oxidized solution of (3-20):1. After stirring and solid-liquid separation, ammonium polyvanadate and vanadium precipitation mother liquor are obtained. The ammonium polyvanadate is then calcined at 450-650℃ for 0.5-3.0 hours to obtain vanadium pentoxide. This technology utilizes the slow decomposition of urea under heating conditions to generate ammonia and carbon dioxide. The ammonia gradually increases the pH of the solution and generates ammonium ions, which combine with vanadate ions to form ammonium vanadate precipitate. Essentially, it is still an ammonium salt precipitation of vanadium, and the generation of ammonia nitrogen wastewater cannot be avoided.

[0007] In contrast, there is more research on melamine as a novel vanadium precipitant. Existing literature (such as Wang B, Yang Q, Li T, et al. Rapid precipitation of vanadium from solution using melamine as precipitant with high efficiency[J]. Journal of Chemical Technology Biotechnolgy, 2024, 12(99): 2569-2581) shows that the vanadium precipitation product of melamine is a melamine-vanadate complex, which can directly obtain V2O5 after calcination, without generating ammonia nitrogen wastewater, making it environmentally friendly and beneficial for subsequent wastewater treatment.

[0008] However, melamine vanadium precipitation technology also has fatal flaws. Melamine has extremely low solubility, only 0.33 g / 100 mL at 20°C, and even at 90°C, it's only about 5 g / L. To obtain a high vanadium precipitation rate, excessive dosage is required (n(Mel) / n(V) = 0.6~0.8), resulting in a large amount of undissolved melamine solid being encapsulated in the vanadium precipitate, leading to an actual utilization rate of only 60%~70%. Furthermore, the melamine vanadium precipitation reaction kinetics are slow, requiring a high temperature of 60~100°C for 30~60 minutes, which is significantly less effective than the room-temperature vanadium precipitation of hexamethylenetetramine.

[0009] Therefore, the key technical problem that this invention aims to solve is how to achieve low-temperature, rapid, and high-utilization vanadium precipitation without generating ammonia nitrogen wastewater. Summary of the Invention

[0010] The main objective of this invention is to provide a method for extracting and separating vanadium from vanadium-containing solutions, thereby solving the technical problem of achieving low-temperature, rapid, and high-utilization-rate vanadium precipitation without generating ammonia nitrogen wastewater.

[0011] According to one aspect of the present invention, a method for extracting and separating vanadium from a vanadium-containing solution is provided, comprising the following steps: S1, dissolving melamine in an aqueous solution containing urea to form a homogeneous solution; S2, adding the homogeneous solution to the vanadium-containing solution to carry out a vanadium precipitation reaction to obtain a reacted material; S3, performing solid-liquid separation on the reacted material to obtain a vanadium precipitate, and calcining the vanadium precipitate to obtain a vanadium pentoxide product.

[0012] According to one embodiment of the present invention, in step S1, the molar ratio of urea to melamine is (3~10):1.

[0013] According to one embodiment of the present invention, in step S1, the mass fraction of urea in the homogeneous solution is 10% to 30%.

[0014] According to one embodiment of the present invention, in step S2, the pH of the vanadium-containing solution is adjusted to 1.5 to 2.5 before adding the homogeneous solution.

[0015] According to one embodiment of the present invention, in step S2, the reaction temperature is controlled to be 40~60°C.

[0016] According to one embodiment of the present invention, in step S2, the reaction time is controlled to be 10~30 min.

[0017] According to one embodiment of the present invention, in step S2, the molar ratio of melamine to vanadium in the vanadium-containing solution is (0.2~0.4):1.

[0018] According to one embodiment of the present invention, step S3 further includes: directly returning the vanadium-precipitated wastewater obtained after solid-liquid separation to step S1 as a urea-containing aqueous solution for recycling.

[0019] According to one embodiment of the present invention, in step S3, the calcination temperature is 450~550℃ and the calcination time is 2~3 hours.

[0020] According to one embodiment of the present invention, in step S3, the vanadium precipitate is washed and dried before calcination.

[0021] In the technical solution of this invention, urea is used as a physical solubilizer. By competitively disrupting the intermolecular hydrogen bond network of melamine, the solubility of melamine is significantly improved, thereby increasing the efficiency and utilization rate of the melamine-vanadium precipitation reaction. This allows melamine and vanadium to react rapidly at low temperatures, and the melamine-vanadium precipitation process does not produce ammonia nitrogen wastewater. Therefore, this invention achieves low-temperature, rapid, and highly efficient vanadium precipitation without generating ammonia nitrogen wastewater. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 A flowchart illustrating a method for extracting and separating vanadium from a vanadium-containing solution according to an embodiment of the present invention is shown. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be further described in detail below with reference to specific examples and the accompanying drawings.

[0025] It should be noted that all uses of "first" and "second" in the embodiments of the present invention are for the purpose of distinguishing two entities or parameters with the same name but different names. It is clear that "first" and "second" are only for the convenience of expression and should not be construed as limiting the embodiments of the present invention. Subsequent embodiments will not explain this in detail.

[0026] As mentioned in the background section above, this invention aims to solve the following technical problems existing in the prior art: (1) Melamine has low solubility, making it impossible to prepare a homogeneous solution, resulting in slow reaction kinetics and low utilization of vanadium precipitating agent. Melamine vanadium precipitation requires high temperature (60~100℃), resulting in high energy consumption; (2) Urea vanadium precipitation generates ammonia nitrogen wastewater, which has a heavy environmental burden. The prior art cannot simultaneously achieve "no ammonia nitrogen pollution" and "low temperature, rapid and high utilization rate". In order to solve the above problems in the prior art, this invention proposes a method for extracting and separating vanadium from vanadium-containing solutions, and in particular a process that uses urea as a physical solubilizer to improve the solubility of melamine and achieve low temperature and rapid vanadium precipitation.

[0027] refer to Figure 1 This invention proposes a method for extracting and separating vanadium from a vanadium-containing solution, comprising the following steps: S1, Melamine is dissolved in an aqueous solution containing urea to form a homogeneous solution; S2, a homogeneous solution is added to a vanadium-containing solution to carry out a vanadium precipitation reaction, and the reacted material is obtained; S3 involves solid-liquid separation of the reacted material to obtain vanadium precipitate, followed by calcination of the vanadium precipitate to obtain vanadium pentoxide product.

[0028] This invention breaks with traditional thinking, employing a synergistic mechanism of "urea physical solubilization - melamine chemical precipitation" to extract and separate vanadium from vanadium-containing solutions. In this invention's technical solution, urea is not used as a vanadium precipitant (to avoid the generation of NH4 through hydrolysis). + As a physical solubilizer, melamine significantly improves its solubility by competitively disrupting the intermolecular hydrogen bond network of melamine. Simultaneously, melamine acts as a chemical precipitant, reacting rapidly with vanadium in a homogeneous solution at low temperatures, and the precipitation of vanadium with melamine does not generate ammonia nitrogen wastewater. Therefore, this invention achieves low-temperature, rapid, and highly efficient vanadium precipitation without generating ammonia nitrogen wastewater. In embodiments of this invention, the vanadium-containing solution can be a vanadium-containing solution obtained from the slag of vanadium-containing minerals through smelting, after roasting, leaching, and impurity removal, or other suitable vanadium-containing solutions.

[0029] In this invention, urea can solubilize melamine, essentially through a hydrogen bond competition mechanism. Melamine molecules form a strong hydrogen bond network through the amino groups on the triazine rings, resulting in extremely low solubility in water (only 0.33 g / 100 mL at 20°C). Urea (NH2-CO-NH2), as a structurally similar small-molecule hydrogen bond donor / acceptor, can compete with melamine to form intermolecular hydrogen bonds, disrupting its self-assembled aggregates and allowing melamine to disperse in solution as monomers or oligomers, thereby significantly improving solubility. Simultaneously, urea's high water solubility (approximately 108 g / 100 mL at 20°C) and structural affinity for melamine (both containing primary amine groups) make it an ideal solubilizing agent. Furthermore, under acidic conditions, the degree of urea protonation decreases, enhancing its hydrogen bond acceptance capacity, further promoting the dissociation and dispersion of melamine.

[0030] On the other hand, the urea-melamine homogeneous solution can achieve low-temperature vanadium precipitation. From a thermodynamic perspective, the melamine vanadium precipitation reaction is essentially an electrostatic complexation precipitation between protonated melamine cations and polyvanadate anions. This process has ΔH < 0 and ΔS > 0 (driven by the release of a large number of coordinated water molecules from highly hydrated polyvanadate ions). According to the Gibbs free energy equation ΔG = ΔH - TΔS, the decrease in temperature actually reduces the TΔS term and makes ΔG more negative, thus thermodynamically more favorable for precipitation formation. At the same time, the melamine protonation equilibrium shifts positively at low temperatures, increasing the concentration of active vanadium species in the solution. Furthermore, vanadium polynuclear complexes are more stable at low temperatures. These factors together make low-temperature vanadium precipitation not only theoretically feasible, but may even yield higher vanadium precipitation rates and more complete crystal structures.

[0031] In some embodiments, in step S1, the molar ratio of urea to melamine is (3~10):1, preferably (5~8):1. Within a molar ratio range of 3:1 to 10:1, it ensures that each melamine molecule is surrounded by 3~10 urea molecules competing for hydrogen bonds, effectively disrupting its self-assembled network. When the molar ratio is below 3:1, the solubilization effect is insufficient, and a homogeneous solution cannot be formed; when the molar ratio is above 10:1, the urea concentration is too high, the solution viscosity increases, the mass transfer resistance increases, and the subsequent vanadium precipitation effect is affected.

[0032] In some embodiments, in step S1, the mass fraction of urea in the homogeneous solution is 10% to 30%, preferably 15% to 25%. A suitable concentration is beneficial to ensure reaction efficiency while taking into account the economic benefits of recycling vanadium precipitation wastewater.

[0033] In some embodiments, in step S2, the pH of the vanadium-containing solution is adjusted to 1.5-2.5 before adding the homogeneous solution. The inventors have found that when the pH < 1.5, the acidity is too strong, urea hydrolysis is accelerated, and vanadium is converted into VO2+. +The primary pH value is 1.5, which decreases the selectivity for vanadate precipitation. When pH > 2.5, the protonation degree of melamine decreases, reducing its ability to bind with vanadate and thus decreasing the vanadate precipitation rate. Therefore, the suitable pH range is 1.5–2.5.

[0034] In some embodiments, in step S2, the reaction temperature is controlled at 40~60℃, preferably 45~50℃. The inventors have found that when the temperature is below 40℃, the solubility of melamine is insufficient, and the solubilizing effect is limited; when the temperature is above 60℃, the urea hydrolysis rate increases significantly (when temperature > 60℃ and pH < 2.0, the urea hydrolysis half-life is << 2 hours), which may produce NH4. + This leads to ammonia nitrogen pollution. Therefore, maintaining urea at 40-60℃ ensures that it exists in molecular form without hydrolysis, only playing a physical solubilizing role, and also guarantees the solubility of melamine.

[0035] In some embodiments, in step S2, the reaction time is controlled to be 10-30 min, preferably 15-20 min, so as to ensure that the reaction is fully carried out while taking into account production efficiency.

[0036] In some embodiments, in step S2, the molar ratio of melamine to vanadium in the vanadium-containing solution is (0.2~0.4):1, preferably (0.3~0.4):1, thereby significantly reducing the amount of vanadium precipitant used while ensuring efficient vanadium precipitation.

[0037] In some embodiments, step S3 further includes: directly returning the vanadium-precipitated wastewater obtained after solid-liquid separation to step S1 as a urea-containing aqueous solution for recycling. After the vanadium precipitation reaction, the urea remains in the mother liquor and can be directly recycled, achieving zero discharge.

[0038] In some embodiments, in step S3, the vanadium precipitate is washed and dried before calcination. Washing removes soluble impurities, ensuring the acquisition of a high-purity vanadium pentoxide product. In some embodiments, in step S3, the calcination temperature is 450~550℃, and the calcination time is 2~3 hours, to achieve complete oxidation transformation of vanadium.

[0039] The method of this invention can be implemented in production as follows: First, a certain volume of deionized water is pumped into a homogeneous solution preparation tank, and a certain mass of urea (industrial grade, purity ≥99%) is added under stirring conditions, and the urea is stirred to dissolve; second, melamine (industrial grade, purity ≥99.5%) is added to the solution preparation tank, and a urea-melamine homogeneous solution is formed under stirring (a homogeneous solution can be formed at 40~60℃); then, a certain volume of vanadium-containing solution is pumped into a vanadium precipitation tank, and steam heating is started. The pH of the solution is adjusted using sulfuric acid or sodium hydroxide. A certain volume of homogeneous solution is pumped in according to the designed dosage, and the reaction is kept at a constant temperature for a period of time. Next, the slurry after the reaction is completed is placed into a collection tank and allowed to settle. Finally, the side flow valve of the collection tank is opened, and the upper layer liquid is placed into the vanadium precipitation wastewater tank. The bottom slurry is filtered and washed using a plate and frame filter or belt filter to obtain vanadium precipitate. The vanadium precipitate is washed, dried, and calcined in a rotary kiln to obtain vanadium pentoxide product. The vanadium precipitation wastewater is directly returned to the homogeneous solution preparation process and recycled as urea-water solution.

[0040] In summary, the present invention has the following advantages: (1) Urea is used as a physical solubilizer for the first time in the melamine vanadium precipitation system; (2) The vanadium precipitation process with low temperature (40~60℃), fast (10~20min), and low dosage (the molar ratio of melamine to vanadium is 0.2~0.4) is realized for the first time; (3) A synergistic recycling system of urea-melamine is established for the first time, with no ammonia nitrogen wastewater and a vanadium precipitation agent utilization rate of >90%.

[0041] The following description is based on specific embodiments and comparative examples.

[0042] The composition of the vanadium-containing solutions in each embodiment and comparative example is shown in Table 1.

[0043] Table 1 Composition of vanadium-containing solution / g·L -1

[0044] Example 1 This embodiment describes a urea-solubilized melamine low-temperature vanadium precipitation scheme, and the specific steps are as follows: First, dissolve 30g of urea in 56mL of water (based on a urea mass fraction of 30% in the homogeneous solution), heat to 50℃, then add 14g of melamine (molar ratio of urea to melamine is 4.5:1), and stir until completely dissolved to form a homogeneous solution for later use. Measure 200mL of vanadium-containing solution and adjust its pH to 1.5, then add 30.96g of the prepared homogeneous solution (molar ratio of melamine to vanadium is 0.4:1), and stir the reaction at 40℃ for 30min. After the reaction is complete, filter and wash the precipitate.

[0045] The upper layer is 258 mL, with a concentration of V of 0.136 g / L and NH4+. + The concentration was <0.1 g / L, and the vanadium precipitation rate was 99.20%. After calcination, the precipitate yielded 7.73 g of V2O5 with a purity of 99.12%.

[0046] Example 2 This embodiment describes a urea-solubilized melamine low-temperature vanadium precipitation scheme, and the specific steps are as follows: First, dissolve 20g of urea in 74mL of water (based on a urea mass fraction of 20% in the homogeneous solution), heat to 50℃, then add 6g of melamine (the molar ratio of urea to melamine is 7:1), and stir until completely dissolved to form a homogeneous solution for later use. Measure 200mL of vanadium-containing solution and adjust its pH to 2.5, then add 54.18g of the prepared homogeneous solution (the molar ratio of melamine to vanadium is 0.3:1), and stir the reaction at 50℃ for 20 minutes. After the reaction is complete, filter and wash the precipitate.

[0047] The upper layer is 290 mL, V concentration is 0.143 g / L, and NH4+ is present. + The concentration was <0.1 g / L, and the vanadium precipitation rate was 99.05%. After calcination, the precipitate yielded 7.78 g of V2O5 with a purity of 99.12%.

[0048] Example 3 This embodiment describes a urea-solubilized melamine low-temperature vanadium precipitation scheme, and the specific steps are as follows: First, dissolve 20g of urea in 176mL of water (based on a urea mass fraction of 10% in the homogeneous solution), heat to 50℃, then add 4.2g of melamine (the molar ratio of urea to melamine is 10:1), and stir until completely dissolved to form a homogeneous solution for later use. Measure 200mL of vanadium-containing solution and adjust its pH to 2.0, then add 103.2g of the prepared homogeneous solution (the molar ratio of melamine to vanadium is 0.2:1), and stir the reaction at 60℃ for 10 minutes. After the reaction is complete, filter and wash the precipitate.

[0049] 435 mL of upper layer, V concentration 0.1 g / L, NH4 + The concentration was <0.1 g / L, and the vanadium precipitation rate was 99.01%. After calcination, the precipitate yielded 7.68 g of V2O5 with a purity of 99.12%.

[0050] Comparative Example 1 This comparative example uses a traditional ammonium salt vanadium precipitation scheme, and the specific steps are as follows: Take 200 mL of the vanadium-containing solution in Table 1, add 8.77 g of ammonium sulfate (m(NH4)2SO4) / m(V) = 2.0:1), adjust the pH to 2.0, stir and react in a water bath at 95℃ (boiling) for 60 min, cool to room temperature and filter.

[0051] The upper layer is 228 mL, with a concentration of V of 0.154 g / L and NH4+. + The concentration was 8.24 g / L, and the vanadium precipitation rate was 99.2%. After calcination, the precipitate yielded 7.78 g of V2O5 with a purity of 99.21%.

[0052] Conventional acidic ammonium salt precipitation of vanadium requires high temperatures and generates ammonia nitrogen wastewater.

[0053] Comparative Example 2 This comparative example demonstrates a vanadium precipitation scheme using melamine alone. The specific steps are as follows: Take 200 mL of the vanadium-containing solution from Table 1, add 6.50 g of melamine (n(Mel) / n(V) = 0.6:1), adjust the pH of the solution to 2.0, stir the reaction in a 90℃ water bath for 60 min, cool to room temperature, filter and wash.

[0054] 235 mL of upper layer, V concentration 0.205 g / L, NH4 + The concentration was 0.25 g / L, and the vanadium precipitation rate was 98.9%. After calcination, the precipitate yielded 7.65 g of V2O5 with a purity of 99.08%.

[0055] Melamine precipitation requires high temperature and long reaction time, and a large amount of melamine is encapsulated in the precipitate, resulting in low utilization rate.

[0056] Comparative Example 3 This comparative example demonstrates a vanadium precipitation scheme using urea alone. The specific steps are as follows: Take 200 mL of the vanadium-containing solution in Table 1, add 39.13 g of urea (m(urea) / m(V2O5)=5:1), adjust the pH of the solution to 2.0, stir the reaction in a 90℃ water bath for 120 min, cool to room temperature, filter and wash.

[0057] 216 mL of upper layer, V concentration 0.305 g / L, NH4 + The concentration was 6.85 g / L, and the vanadium precipitation rate was 98.5%. After calcination, the precipitate yielded 7.72 g of V2O5 with a purity of 98.90%.

[0058] Urea hydrolyzes at high temperatures to produce NH4. + The essence is still ammonium salt precipitation of vanadium; the reaction time is extremely long, the efficiency is low, and ammonia nitrogen wastewater is generated at the same time.

[0059] Compared with Comparative Examples 1-3, Examples 1-3 use urea to solubilize melamine, which can achieve the extraction and separation of vanadium in vanadium-containing solutions at low temperatures, and the upper layer does not contain ammonia nitrogen, making it easy to recover and process.

[0060] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention (including the claims) is limited to these examples. Within the framework of the invention, technical features of the above embodiments or different embodiments can be combined, and many other variations of the different aspects of the invention as described above exist, which are not provided in the details for the sake of brevity. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the invention should be included within the protection scope of the invention.

Claims

1. A method for extracting and separating vanadium from a vanadium-containing solution, characterized in that, Includes the following steps: S1, Melamine is dissolved in an aqueous solution containing urea to form a homogeneous solution; S2, the homogeneous solution is added to a vanadium-containing solution to carry out a vanadium precipitation reaction, and the reacted material is obtained; S3, the reacted material is subjected to solid-liquid separation to obtain vanadium precipitate, and the vanadium precipitate is calcined to obtain vanadium pentoxide product.

2. The method according to claim 1, characterized in that, In step S1, the molar ratio of urea to melamine is (3~10):

1.

3. The method according to claim 1, characterized in that, In step S1, the mass fraction of urea in the homogeneous solution is 10% to 30%.

4. The method according to claim 1, characterized in that, In step S2, before adding the homogeneous solution, the pH of the vanadium-containing solution is adjusted to 1.5~2.

5.

5. The method according to claim 1, characterized in that, In step S2, the reaction temperature is controlled at 40~60℃.

6. The method according to claim 1, characterized in that, In step S2, the reaction time is controlled to be 10~30 min.

7. The method according to claim 1, characterized in that, In step S2, the molar ratio of melamine to vanadium in the vanadium-containing solution is (0.2~0.4):

1.

8. The method according to claim 1, characterized in that, Step S3 further includes: directly returning the vanadium-precipitated wastewater obtained after solid-liquid separation to step S1 as the urea-containing aqueous solution for recycling.

9. The method according to claim 1, characterized in that, In step S3, the calcination temperature is 450~550℃ and the calcination time is 2~3 hours.

10. The method according to claim 1, characterized in that, In step S3, the vanadium precipitate is washed and dried before calcination.

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