A method for preparing a vanadium electrolyte

Abstract

This invention belongs to the field of comprehensive utilization of metallurgical resources and relates to a method for preparing vanadium electrolyte, comprising the following steps: S1: Mixing vanadium-containing raw materials with a liquid medium to obtain a mixture. S2: Calcining the mixture under the action of an electric field and uniaxial pressure to obtain a solid-liquid mixture. S3: Washing the solid-liquid mixture, and obtaining a vanadium-containing crude liquid and solid residue after solid-liquid separation. S4: Removing impurities from the vanadium-containing crude liquid to obtain vanadium electrolyte. This invention, by pre-mixing vanadium-containing raw materials with a liquid medium and then calcining them under the coupling action of an electric field and uniaxial pressure, allows the vanadium phase in the raw materials to undergo structural transformation and dissolve into the liquid phase at a lower temperature, avoiding the need for high-temperature oxidation calcination to convert vanadium to V in traditional processes. 5+ The process.

Description

Technical Field

[0001] This invention relates to the field of comprehensive utilization technology of metallurgical resources, specifically a method for preparing vanadium electrolyte. Background Technology

[0002] Vanadium is an indispensable strategic metal resource in the fields of steel, alloys, and energy storage. Currently, it is mainly extracted from vanadium-containing raw materials such as vanadium slag, coal shale, and vanadium-titanium magnetite. The commonly used industrial method for vanadium extraction is the roasting-leaching process, which is based on high-temperature oxidative roasting: vanadium-containing raw materials are oxidized and roasted at temperatures above 700℃, causing vanadium to be extracted into vanadium. 3+ Vanadium in its formal presence transforms into V 5+ The process involves the formation of easily soluble vanadate phases, followed by water or acid leaching to obtain a vanadium-containing solution, which is then used as a basis for preparing solid products such as vanadium pentoxide. This traditional process is mature and reliable, but its process design always revolves around the production of solid vanadium oxides.

[0003] In recent years, the rise of vanadium redox flow battery technology has made vanadium electrolytes an important direction for the utilization of vanadium resources. Unlike traditional solid-state products, flow batteries have specific requirements for the valence state of vanadium, requiring that the vanadium in the electrolyte be mainly in the valence state of V. 3+ and / or V 4 + The vanadium-containing raw material exists in a low valence state. If the existing roasting-leaching route is used directly, the vanadium-containing raw material must first be converted into a high valence state V by high-temperature oxidative roasting. 5+ Then, a reduction process is introduced to reduce vanadium to the desired low valence state. This method of oxidation followed by reduction not only makes the overall process more lengthy, increasing equipment investment and reagent consumption, but also the high-temperature roasting process itself is energy-intensive. More importantly, traditional high-temperature oxidation roasting is carried out in an air atmosphere, and its oxidation reaction is irreversible; vanadium can only be oxidized to V in this process. 5+ And since it is fixed in a solid state, it is impossible to bypass the high oxidation state and directly obtain V-containing compounds. 3+ or V 4+ The solution is vanadium. This inherent characteristic dictates that existing processes must inevitably go through a repetitive path from low price to high price and then back to low price, posing a significant obstacle to the short-process, low-cost preparation of vanadium electrolytes.

[0004] Therefore, there is a need for a method that can avoid prior oxidation to V. 5+ The traditional reduction route directly extracts vanadium in V during the extraction process. 3+ and / or V 4+ A short-process method for vanadium dissolution is proposed to achieve low-energy and direct preparation of vanadium-containing raw materials into vanadium electrolyte. Summary of the Invention

[0005] (a) Technical problems to be solved

[0006] To address the issue that vanadium extraction from vanadium-containing raw materials in existing technologies requires high-temperature oxidation to V0, 5+ The present invention addresses the problems of lengthy processes and high energy consumption in obtaining low-valent vanadium electrolyte through reduction. It provides a method for preparing vanadium electrolyte.

[0007] (II) Technical Solution

[0008] To achieve the above objectives, the main technical solutions adopted by the present invention include:

[0009] This invention provides a method for preparing a vanadium electrolyte, comprising the following steps:

[0010] S1: Mix the vanadium-containing raw material with a liquid medium to obtain a mixture;

[0011] S2: Under the action of electric field and uniaxial pressure, the mixture is roasted to oxidize the trivalent vanadium in the vanadium-containing raw material in situ to tetravalent vanadium and dissolve it into the liquid phase to obtain a solid-liquid mixture;

[0012] S3: Wash the solid-liquid mixture, and after solid-liquid separation, obtain vanadium-containing crude liquid and solid residue;

[0013] S4: The crude vanadium solution containing both trivalent and tetravalent vanadium is subjected to impurity removal treatment to obtain vanadium electrolyte.

[0014] In the preparation method described above, preferably, in step S1, the vanadium-containing raw material is at least one of vanadium slag, coal shale, and vanadium-titanium magnetite.

[0015] In the preparation method described above, preferably, in step S1, the liquid medium is an acidic medium and / or an oxidizing medium, and the pH of the liquid medium is 1-5.

[0016] In the preparation method described above, preferably, in step S1, the acidic medium is an H2SO4 solution and the oxidizing medium is H2O2.

[0017] In the preparation method described above, preferably, in step S1, the mass ratio of particles with a particle size of less than 74 μm in the vanadium-containing raw material is ≥80%.

[0018] In the preparation method described above, preferably, in step S2, the calcination temperature is 100-800℃ and the calcination time is 0.1-2h.

[0019] In the preparation method described above, preferably, in step S2, the electric field is a pulsed DC electric field with a power of 5-37kW, a uniaxial pressure of 5-50kN, and a redox potential of 0.4-1.2V.

[0020] In the preparation method described above, preferably, in step S3, the solid-liquid mixture is washed with water or an acidic solution.

[0021] In the preparation method described above, preferably, in step S4, the pH value of the vanadium-containing crude solution is adjusted to reduce the Fe content in the solution. 3+ Al 3+ Ca 2+ Mg 2+ Mn 2+ Cr 3+ The content of one or more ions in it.

[0022] (III) Beneficial Effects

[0023] This invention premixes vanadium-containing raw materials with a liquid medium, followed by calcination under the coupling of an electric field and uniaxial pressure. This allows the vanadium phase in the raw material to undergo a structural transformation and dissolve into the liquid phase at a lower temperature, avoiding the need for high-temperature oxidation calcination to convert vanadium into V as required in traditional processes. 5+ Therefore, this invention eliminates the need for the circuitous path of first oxidizing to a high valence and then reducing it back to a low valence, thus saving the subsequent reduction process and significantly simplifying the overall preparation process from vanadium-containing raw materials to vanadium electrolyte.

[0024] This invention achieves Vo in a single step during the calcination process by actively controlling the redox potential of the reaction system using a pulsed DC electric field. 3+ To V 4+ The in-situ directional conversion allows vanadium to dissolve directly into the liquid phase in the target valence state. This means that while extracting low-valence vanadium from vanadium-containing raw materials, the present invention simultaneously achieves in-situ control of the valence state. The resulting vanadium-containing crude solution can be directly used for the subsequent preparation of vanadium electrolyte without undergoing additional oxidation or reduction processes, fundamentally avoiding the need for high-temperature oxidation to V in traditional processes. 5+ By reverting to the roundabout path of the low-price state, the process steps were further compressed.

[0025] In terms of energy utilization, the electric field introduced in this invention during the roasting process changes the material heating method from traditional external heating to internal Joule heating effect, resulting in a fast heating rate and high energy utilization efficiency. Combined with the strengthening effect of uniaxial pressure on solid-liquid contact, the roasting step can be completed at a temperature significantly lower than that of traditional roasting, effectively reducing energy consumption.

[0026] This invention uses a mixture of vanadium-containing raw materials and a liquid medium as the processing target. The calcination product can be washed and separated to obtain a product rich in vanadium. 4+ The vanadium-containing crude solution is then purified to obtain vanadium electrolyte. The entire process aims at producing liquid electrolyte, and the process steps are compact and continuous. This provides a short-process and low-energy-consumption technical route for the direct preparation of vanadium redox flow battery electrolyte from vanadium-containing raw materials. Attached Figure Description

[0027] Figure 1 This is a diagram of the electric field-assisted pressure calcination apparatus used in this invention; wherein, Figure 1 a represents an electric field-assisted pressure calcination device. Figure 1 b is a graphite loading mold, where φ is 30mm.

[0028] Figure 2 The images show actual photos of the vanadium-containing leachates prepared in Examples 1-9.

[0029] Figure 3 The image shows the X-ray photoelectron spectrum of the vanadium electrolyte prepared in Example 1.

[0030] Figure 4 Comparison of scanning electron microscope morphology and EDS elemental distribution of the original vanadium slag and the leaching tailings prepared in Example 1.

[0031] Figure 5 Comparison of X-ray diffraction patterns of the original vanadium slag and the leaching tailings prepared in Example 1. Detailed Implementation

[0032] To better explain and facilitate understanding of the present invention, the invention will be described in detail below with reference to the accompanying drawings and embodiments.

[0033] This invention provides a method for preparing a vanadium electrolyte, comprising the following steps:

[0034] S1: Mix the vanadium-containing raw material with a liquid medium to obtain a mixture.

[0035] S2: Under the action of an electric field and uniaxial pressure, the mixture is roasted, so that the trivalent vanadium in the vanadium-containing raw material is partially oxidized in situ to tetravalent vanadium and dissolved into the liquid phase, resulting in a solid-liquid mixture.

[0036] S3: Wash the solid-liquid mixture, and after solid-liquid separation, obtain vanadium-containing crude liquid and solid residue.

[0037] S4: The crude vanadium solution containing both trivalent and tetravalent vanadium is subjected to impurity removal treatment to obtain vanadium electrolyte.

[0038] In step S1 above, the vanadium-containing raw material is pre-mixed with a liquid medium to ensure that the liquid medium fully wets the surface of the vanadium-containing raw material particles, providing a mass transfer basis for the interfacial reaction under the coupling of electric field and pressure in the subsequent step S2. Preferably, the vanadium-containing raw material in step S1 can be selected from at least one of common vanadium-containing materials such as vanadium slag, coal shale, and vanadium-titanium magnetite. In addition to containing vanadium-containing phases, these raw materials often contain various impurity components such as Fe2O3, SiO2, TiO2, Al2O3, MgO, and CaO. Taking typical vanadium slag as an example, vanadium is mainly in the form of V... 3+ The vanadium-containing material is present in the FeO·V₂O₃ phase of vanadium-iron spinel. To improve the efficiency of subsequent reactions and the mass transfer rate, the vanadium-containing raw material is preferably dried and pulverized before use, so that the mass ratio of particles with a particle size of less than 74 μm reaches more than 80%. Particle size control plays an important role. On the one hand, the finer particle size can significantly increase the contact area between the raw material and the liquid medium, which is conducive to the full progress of the interfacial reaction. On the other hand, fine particles are more likely to form a close packing under the uniaxial pressure in the subsequent step S2, enhancing the contact between particles and mass transfer. The uniaxial pressure mentioned in this invention refers to the directional mechanical load applied to the material along a single axis. In specific implementation, the pressure head can be driven by a hydraulic cylinder or a screw pressurizing mechanism to unidirectionally compress the mixture in a graphite loading mold. This uniaxial pressure application method is simple and controllable, and can drive the solid particles to rearrange in the direction of pressure and form a close packing, establishing an effective solid-solid and solid-liquid contact interface between the particles, thereby providing a continuous channel for interfacial charge transfer and vanadium ion mass transfer under the action of an electric field.

[0039] Table 1. Statistical table of main components of vanadium slag

[0040]

[0041] The vanadium slag composition used in all embodiments of the present invention is consistent with that in Table 1. In step S1, the selection of the liquid medium has a significant impact on the leaching behavior and valence state control of vanadium. The liquid medium is preferably an acidic medium, an oxidizing medium, or a combination thereof. The role of the acidic medium is to provide an acidic environment; the pH of the liquid medium is preferably 1-5 to promote the dissolution of vanadium in the vanadium-containing phase. H2SO4 solution is preferred, and its concentration can be adjusted within a wide range according to the characteristics of the raw materials. The role of the oxidizing medium is to assist in controlling the valence state transformation of vanadium during roasting; H2O2 is preferred. The introduction of H2O2 helps to partially leach vanadium under the action of an electric field. 3+ To V 4+Oxidation allows vanadium to enter the liquid phase in the target valence state. In a preferred embodiment, the solid-liquid mass ratio of the vanadium-containing raw material to the liquid medium can be controlled within a suitable range to ensure that the liquid medium can fully wet the raw material particles without causing excessive energy consumption during subsequent roasting due to excess liquid. More preferably, the mass fraction of the H2SO4 solution can be 5-25%, and the concentration of the hydrogen peroxide solution is 0.01-0.1 mol / L.

[0042] Step S2, by introducing the coupling effect of an electric field and uniaxial pressure during the roasting process, achieves a synergistic promotion of the phase structure transformation of vanadium-containing materials, the regulation of the vanadium valence state, and efficient dissolution. In traditional high-temperature oxidation roasting processes, vanadium-containing raw materials need to be roasted for a long time at temperatures above 700°C and in an air atmosphere, so that V... 3+ Irreversible oxidation to V 5+ This process is energy-intensive and cannot achieve in-situ control of the vanadium valence state. This invention fundamentally changes the heating method and reaction environment by introducing a pulsed DC electric field. In this step, the selective control of the vanadium valence state by the electric field is based on the following mechanism: under the action of the pulsed DC electric field, the acidic liquid medium in the mixture forms an ion-conducting network, and a large number of micro-current channels are formed inside the material. On the one hand, the electric field rapidly raises the material to the reaction temperature through the Joule heating effect; on the other hand, the electric field can generate a specific electrochemical environment at the solid-liquid interface, directly driving the oxidation of trivalent vanadium to tetravalent vanadium in the solid phase. By adjusting the electric field power, pulse parameters, etc., the oxidation potential window of the system can be precisely controlled to ensure that it exactly meets the Vo value. 3+ To V 4+ Thermodynamic and kinetic conditions of the transformation. Depending on the initial pH of the liquid medium, the in-situ generated V... 4+ Stabilize the complex or dissolve to obtain V 4+ The dominant vanadium-containing solution. In this process, the electric field is the core means to drive and maintain the formation of tetravalent vanadium, while the acidity or alkalinity of the initial liquid medium plays a synergistic role in stabilizing the valence state.

[0043] It is important to emphasize that the final valence state of vanadium in the roasting product is the result of the synergistic regulation of redox potential and the acidity / alkalinity of the liquid medium, rather than being determined by any single factor. If the acidity / alkalinity is too high, even if the redox potential is suitable, vanadium may be further oxidized to V. 5+ This forms polyvanadate ions such as HV. 10 O 28 5- This leads to vanadium existing in a high oxidation state. Conversely, if the acidity of the liquid medium is suitable, changes in the redox potential will also cause V... 3+ To V 4+The directional conversion efficiency will also decrease significantly, making it difficult to obtain a vanadium-containing solution dominated by tetravalent vanadium. This invention achieves Vo by controlling the redox potential at 0.4-1.2V and maintaining an initial acidic liquid medium with a pH of 1-5, thus simultaneously satisfying the driving force of electrochemical oxidation and the conditions for chemical stability. 3+ To V 4+ In-situ directional transformation and V 4+ The solution is kept stable to obtain a crude vanadium-containing solution in which tetravalent vanadium is predominant.

[0044] Applying uniaxial pressure to the material while simultaneously applying an electric field enhances the contact between the solid and liquid phases, promoting interfacial mass transfer. Under pressure, the contact between vanadium-containing raw material particles and between the particles and the liquid medium becomes tighter, and the distribution of the liquid medium in the particle gaps becomes more uniform. This facilitates the diffusion of active substances generated under the electric field into the particle interior and also promotes the migration of dissolved vanadium ions from the solid-phase interface to the bulk liquid phase. Simultaneously, uniaxial pressure helps maintain the stability of the particle packing structure during calcination, preventing uneven local reactions. The synergistic coupling effect of the electric field and pressure effectively reduces the activation energy of the reaction, allowing the structural transformation of the vanadium-containing phase and the dissolution of vanadium to proceed efficiently at temperatures significantly lower than those of traditional calcination.

[0045] The calcination process parameters in step S2 can be optimized according to the type of raw materials and the requirements of the target product. The preferred redox potential of the mixture is 0.4-1.2V, the preferred calcination temperature is 100-800℃, and the preferred calcination time is 0.1-2h. A shorter calcination time is beneficial for improving production efficiency. The preferred electric field power is 5-37kW, and the preferred uniaxial pressure is 5-50kN. Under the above process conditions, the electric field power and uniaxial pressure can be matched and adjusted according to specific needs. Appropriately increasing the electric field power can accelerate the heating rate and enhance the electrochemical control capability, while appropriately increasing the uniaxial pressure can strengthen the solid-liquid contact and mass transfer effect. It should be noted that the calcination process can be carried out in an air atmosphere, which differs from traditional processes that require operation in a strictly controlled oxidizing atmosphere, further simplifying the operating conditions. The calcination atmosphere of this invention can be argon, an argon / hydrogen mixture, or air.

[0046] After the electric field-pressure coupled low-temperature roasting treatment in step S2, the vanadium phase in the vanadium-containing raw material has undergone a significant structural transformation, with some vanadium changing to V2. 3+ and / or V 4+ The vanadate dissolves into the liquid phase, resulting in a solid-liquid mixture. Unlike the high-valence vanadate solids obtained by conventional calcination, the calcination product of this invention already contains a solution of vanadium ions in the target valence state, eliminating the need for subsequent reduction treatment.

[0047] Step S3 involves washing and separating the solid-liquid mixture obtained in step S2 to effectively separate the vanadium-containing solution from the solid residue. Water or a low-concentration acidic solution is preferred as the washing medium. Using a low-concentration acidic solution avoids hydrolysis and precipitation of dissolved vanadium ions due to a sudden increase in pH, thus maintaining the vanadium yield. Solid-liquid separation can be achieved through filtration, centrifugation, or other methods. After this step, a crude vanadium-containing solution and solid residue are obtained. The concentration and valence state of vanadium in the crude vanadium-containing solution depend on the process parameters controlled in step S2. Under optimal conditions, a high leaching rate can be achieved, and vanadium in the solution is mainly in the form of V... 3+ and / or V 4+ It exists in low-price forms.

[0048] Step S4 involves impurity removal from the vanadium-containing crude solution to remove impurity ions dissolved along with the vanadium, thereby obtaining a vanadium electrolyte that meets the requirements for industrial applications in vanadium redox flow batteries. Common impurity ions in the vanadium-containing crude solution include Fe. 3+ Al 3+ Ca 2 + Mg 2+ Mn 2+ Cr 3+ The main method of impurity removal is to adjust the pH of the solution, utilizing the differences in the hydrolytic precipitation characteristics of different metal ions to selectively precipitate and remove impurity ions. In practice, deionized water can be added to the vanadium-containing crude solution for dilution, gradually increasing the pH. During this process, Fe... 3+ Al 3+ Easily hydrolyzed ions will first form hydroxide precipitates. To further promote precipitation, an appropriate amount of oxalic acid (H₂C₂O₄) can be added. Oxalic acid can form insoluble oxalate precipitates with ions such as iron, aluminum, and calcium, thus enhancing the impurity removal effect.

[0049] During pH adjustment, precise control of the pH range is necessary. According to a preferred embodiment of the present invention, the final pH value of the impurity removal treatment is preferably controlled within the range of 1.8-2.2. This pH range is determined based on the following comprehensive considerations: when the pH is too low, Fe... 3+ Al 3+ Incomplete hydrolysis and precipitation resulted in poor impurity removal. While higher pH levels led to more thorough precipitation, vanadium ions risked hydrolysis and loss. This invention, through experiments, found that first diluting the vanadium-containing crude solution with water to approximately pH 3.0-3.2 to precipitate impurities, and then adjusting the pH back to an acidic range of 1.8-2.2 using H2SO4, effectively removed Fe. 3+ Al 3+ and some Cr 3+ While removing impurities, it maintains vanadium in a stable dissolved state, preventing vanadium loss. In addition, some Ca...2+ The oxalic acid can be used to remove the precipitate through complexation. The operating temperature for the purification process can be controlled within the range of 25-80℃; appropriate heating helps to accelerate the precipitation reaction rate and the aggregation and sedimentation of the precipitate particles. After the reaction is complete, the precipitate and the purified solution are obtained through solid-liquid separation. Experimental results show that after the above purification process, the Fe in the solution... 3+ Al 3+ Cr 3+ The content of major impurity ions has been significantly reduced, meeting the requirements for impurity content in vanadium redox flow battery electrolytes for engineering applications.

[0050] This invention constructs a complete short-process preparation route from vanadium-containing raw materials to vanadium electrolyte through the above four steps. The premixing in step S1 lays the foundation for mass transfer in subsequent reactions. The electric field-pressure coupled low-temperature calcination in step S2 achieves efficient vanadium extraction while simultaneously controlling the valence state in situ, which is the core innovation of this invention. The washing and separation in step S3 effectively separates vanadium from solid residues. The impurity removal treatment in step S4 ensures the high purity of the final product. Each step is synergistic and interconnected, collectively avoiding the high valence state V... 5+ The technical goal of directly obtaining low-valence vanadium electrolyte effectively solves the problem of the traditional process of first oxidizing to V at high temperature. 5+ Then we return to the problems of lengthy processes and high energy consumption that come with low prices.

[0051] Compared to the traditional roasting-leaching-reduction process that aims to produce solid vanadium pentoxide, this invention uses liquid vanadium electrolyte as the direct target product. The process steps are compact and sequential, eliminating the need for high-temperature oxidation roasting and subsequent reduction processes, resulting in significantly reduced energy consumption and substantial decreases in equipment investment and operating costs. Furthermore, this method is applicable to various vanadium-containing raw materials such as vanadium slag, coal shale, and vanadium-titanium magnetite, demonstrating strong adaptability and promising industrial application prospects and widespread value.

[0052] To address the high energy consumption issue associated with high-temperature roasting in existing vanadium electrolyte preparation technologies, some current research employs direct leaching of vanadium-containing raw materials using sulfuric acid with a mass concentration as high as 30-50%. This method utilizes high-concentration sulfuric acid to disrupt the vanadium-containing phase structure at relatively low temperatures, removing vanadium from the raw materials without roasting. 3+ Direct leaching yields a trivalent vanadium solution. However, this method has significant drawbacks: firstly, the high concentration of sulfuric acid causes a large amount of impurities such as Fe, Al, Ca, Mg, Mn, and Cr in the raw material to dissolve, resulting in an extremely high impurity content in the leachate, placing a heavy burden on subsequent impurity removal and causing significant vanadium loss. Secondly, this method can only obtain V... 3+ The solution is mainly composed of vanadium redox flow batteries, while the ideal electrolyte active material for all-vanadium redox flow batteries needs to be in the form of V... 4+However, to obtain tetravalent vanadium electrolyte, an additional oxidation process is still required, making the process still cumbersome.

[0053] Compared with the aforementioned high-concentration sulfuric acid direct leaching technology, this invention achieves a fundamental breakthrough in both technical means and effectiveness by introducing synergistic roasting with an electric field and uniaxial pressure: utilizing the Joule heating effect of the electric field to rapidly raise the temperature of the material, while actively controlling the redox potential of the reaction system, the sparingly soluble sulfuric acid in the raw material can be removed even in a low-concentration acid medium. 3+ In-situ selective oxidation to V 4+ It achieves stable dissolution, directly obtaining a vanadium-containing solution dominated by tetravalent vanadium in one step, fundamentally bypassing the circuitous path of first dissolving trivalent vanadium using high-concentration sulfuric acid and then additional oxidation. Furthermore, since this invention does not rely on high-concentration sulfuric acid, it significantly suppresses the dissolution of impurity ions from the source, significantly reducing the burden of subsequent impurity removal, ultimately achieving a short-process, low-impurity, direct preparation of a high-proportion tetravalent vanadium electrolyte.

[0054] To further clarify the present invention and its technological advancements, the following description is provided in conjunction with specific embodiments and technical effects.

[0055] Example 1

[0056] This embodiment provides a method for preparing vanadium electrolyte, including the following steps:

[0057] S1: The vanadium slag is crushed to ensure that the proportion of particles with a diameter less than 74μm reaches more than 80% by mass. Then, it is mixed with a liquid medium with a pH of 3 at a solid-liquid mass ratio of 1:0.3 to obtain a mixture. The liquid medium is a 15% (w / w) H2SO4 solution and a 0.05 mol / L H2O2 solution.

[0058] S2: Add the mixture Figure 1 The device shown includes Figure 1 The electric field-assisted pressure calcination device shown in figure a and Figure 1 The graphite loading mold shown in b is subjected to low-temperature calcination under a pulsed DC electric field. The power is set to 20kW and the uniaxial pressure to 30kN, so that the oxidation-reduction potential of the mixture is 0.8V. The mixture is calcined at 400℃ for 0.5h in an air atmosphere to obtain a solid-liquid mixture.

[0059] S3: Wash the calcined solid-liquid mixture with a small amount of water and filter it, such as... Figure 2 The vanadium-containing leaching solution and leaching tailings are shown.

[0060] S4: Dilute the vanadium-containing leachate with deionized water to raise the pH to approximately 3. Continue adding oxalic acid and stir the reaction at 25°C for 1 hour. After the reaction, further dilute with deionized water to raise the pH to approximately 3.2 and stir the reaction at 80°C for 1 hour. Then, add a small amount of H₂SO₄ to adjust the pH to approximately 1.8 and stir the reaction at 80°C for 1 hour. Further adjust the amounts of deionized water and H₂SO₄ added to stabilize the pH at 2.0, and stir the reaction at 80°C for 1 hour. After solid-liquid separation, the vanadium electrolyte is obtained.

[0061] The leachate obtained in step S3 was analyzed using inductively coupled plasma optical emission spectrometry (ICP-OES). Calculations showed that the vanadium leaching rate in this embodiment was 88.5%. UV-Vis ultraviolet-visible absorption spectroscopy analysis revealed that the vanadium content in the vanadium-containing leachate obtained in step S3 was... 3+ The proportion was 4.7%, V 4+ The proportion was 95.3%.

[0062] Example 2

[0063] This embodiment provides a method for preparing vanadium electrolyte, including the following steps:

[0064] S1: Vanadium slag and coal shale are crushed to ensure that particles with a diameter less than 74 μm account for more than 80% of the total mass. Then, a liquid medium with a pH of 1 is added at a solid-liquid mass ratio of 1:0.3 and mixed to obtain a mixture. The liquid medium consists of a 15% (w / w) H2SO4 solution and a 0.05 mol / L H2O2 solution.

[0065] S2: Add the mixture Figure 1 In the device shown, low-temperature calcination is carried out under pulsed DC electric field conditions. The power is set to 25kW and the uniaxial pressure is 35kN, so that the oxidation-reduction potential of the mixture is 0.4V. The mixture is calcined at 300℃ for 1h in an argon atmosphere to obtain a solid-liquid mixture.

[0066] S3: The calcined solid-liquid mixture is washed and filtered with a 10% (w / w) H2SO4 solution, such as... Figure 2 The vanadium-containing leaching solution and leaching tailings are shown.

[0067] S4: Dilute the vanadium-containing leachate with deionized water to raise the pH to approximately 3.1. Continue adding oxalic acid and stir the reaction at 30°C for 1 hour. After the reaction, further dilute with deionized water to raise the pH to approximately 3.2 and stir the reaction at 75°C for 1 hour. Then, add a small amount of H₂SO₄ to adjust the pH to approximately 1.9 and stir the reaction at 75°C for 1 hour. Further adjust the amounts of deionized water and H₂SO₄ added to stabilize the pH at 1.8, and stir the reaction at 80°C for 1 hour. After solid-liquid separation, the vanadium electrolyte is obtained.

[0068] The leachate obtained in step S3 was analyzed using inductively coupled plasma optical emission spectrometry (ICP-OES). Calculations showed that the vanadium leaching rate in this embodiment was 68.4%. UV-Vis ultraviolet-visible absorption spectroscopy analysis revealed that the vanadium content in the vanadium-containing leachate obtained in step S3 was... 3+ The proportion was 12.2%, V 4+ The proportion was 87.8%.

[0069] Example 3

[0070] This embodiment provides a method for preparing vanadium electrolyte, including the following steps:

[0071] S1: Vanadium slag, coal shale, and vanadium-titanium magnetite are crushed to ensure that particles with a diameter less than 74 μm account for more than 80% of the total mass. Then, a liquid medium with a pH of 5 is added at a solid-liquid mass ratio of 1:0.3 to obtain a mixture. The liquid medium consists of a 15% (w / w) H₂SO₄ solution and a 0.05 mol / L H₂O₂ solution.

[0072] S2: Add the mixture Figure 1 In the device shown, low-temperature calcination is carried out under pulsed DC electric field conditions. The power is set to 5kW and the uniaxial pressure is 50kN, so that the oxidation-reduction potential of the mixture is 0.8V. The mixture is calcined at 450℃ for 2h in an atmosphere of argon and hydrogen to obtain a solid-liquid mixture.

[0073] S3: Wash the calcined solid-liquid mixture with a small amount of water and filter it, such as... Figure 2 The vanadium-containing leaching solution and leaching tailings are shown.

[0074] S4: Dilute the vanadium-containing leachate with deionized water to raise the pH to approximately 3. Continue adding oxalic acid and stir the reaction at 25°C for 1 hour. After the reaction, further dilute with deionized water to raise the pH to approximately 3.2 and stir the reaction at 80°C for 1 hour. Then, add a small amount of H₂SO₄ to adjust the pH to approximately 1.8 and stir the reaction at 80°C for 1 hour. Further adjust the amounts of deionized water and H₂SO₄ added to stabilize the pH at 2.1, and stir the reaction at 80°C for 1 hour. After solid-liquid separation, the vanadium electrolyte is obtained.

[0075] The leachate obtained in step S3 was analyzed using inductively coupled plasma optical emission spectrometry (ICP-OES). Calculations showed that the vanadium leaching rate in this embodiment was 90.8%. UV-Vis ultraviolet-visible absorption spectroscopy analysis revealed that the vanadium content in the vanadium-containing leachate obtained in step S3 was... 3+ The proportion was 6.1%, V 4+ The percentage was 93.9%.

[0076] Example 4

[0077] This embodiment provides a method for preparing vanadium electrolyte, including the following steps:

[0078] S1: Vanadium slag and vanadium-titanium magnetite are crushed to ensure that particles with a diameter less than 74 μm account for more than 80% of the total mass. Then, a liquid medium with a pH of 2 is added at a solid-liquid mass ratio of 1:0.3 to mix the mixture, resulting in a mixture. The liquid medium consists of a 15% (w / w) H2SO4 solution and a 0.05 mol / L H2O2 solution.

[0079] S2: Add the mixture Figure 1 In the device shown, low-temperature calcination is carried out under pulsed DC electric field conditions. The power is set to 10kW, the uniaxial pressure is 5kN, the oxidation-reduction potential of the mixture is 1V, and the mixture is calcined at 100℃ for 0.1h in an air atmosphere to obtain a solid-liquid mixture.

[0080] S3: Wash the calcined solid-liquid mixture with a small amount of water and filter it, such as... Figure 2 The vanadium-containing leaching solution and leaching tailings are shown.

[0081] S4: Dilute the vanadium-containing leachate with deionized water to raise the pH to approximately 3. Continue adding oxalic acid and stir the reaction at 25°C for 1 hour. After the reaction, further dilute with deionized water to raise the pH to approximately 3.2 and stir the reaction at 80°C for 1 hour. Then, add a small amount of H₂SO₄ to adjust the pH to approximately 1.8 and stir the reaction at 80°C for 1 hour. Further adjust the amounts of deionized water and H₂SO₄ added to stabilize the pH at 2.2, and stir the reaction at 80°C for 1 hour. After solid-liquid separation, the vanadium electrolyte is obtained.

[0082] The leachate obtained in step S3 was analyzed using inductively coupled plasma optical emission spectrometry (ICP-OES). Calculations showed that the vanadium leaching rate in this embodiment was 75.6%. UV-Vis ultraviolet-visible absorption spectroscopy analysis revealed that the vanadium content in the vanadium-containing leachate obtained in step S3 was... 3+ The proportion was 13.4%, V 4+ The proportion was 86.6%.

[0083] Example 5

[0084] This embodiment provides a method for preparing vanadium electrolyte, including the following steps:

[0085] S1: The vanadium slag is crushed to ensure that the proportion of particles with a diameter less than 74μm reaches more than 80% by mass. Then, it is mixed with a liquid medium with a pH of 1.1 at a solid-liquid mass ratio of 1:0.3 to obtain a mixture. The liquid medium is a 15% (w / w) H2SO4 solution and a 0.05 mol / L H2O2 solution.

[0086] S2: Add the mixture Figure 1 In the device shown, low-temperature calcination is carried out under pulsed DC electric field conditions. The power is set to 37kW and the uniaxial pressure is 50kN, so that the oxidation-reduction potential of the mixture is 1.2V. The mixture is calcined at 800℃ for 0.5h in an air atmosphere to obtain a solid-liquid mixture.

[0087] S3: Wash the calcined solid-liquid mixture with a small amount of water and filter it, such as... Figure 2 The vanadium-containing leaching solution and leaching tailings are shown.

[0088] S4: Dilute the vanadium-containing leachate with deionized water to raise the pH to approximately 3. Continue adding oxalic acid and stir the reaction at 25°C for 1 hour. After the reaction, further dilute with deionized water to raise the pH to approximately 3.2 and stir the reaction at 80°C for 1 hour. Then, add a small amount of H₂SO₄ to adjust the pH to approximately 1.8 and stir the reaction at 80°C for 1 hour. Further adjust the amounts of deionized water and H₂SO₄ added to stabilize the pH at 1.8, and stir the reaction at 80°C for 1 hour. After solid-liquid separation, the vanadium electrolyte is obtained.

[0089] The leachate obtained in step S3 was analyzed using inductively coupled plasma optical emission spectrometry (ICP-OES). Calculations showed that the vanadium leaching rate in this embodiment was 89.9%. UV-Vis ultraviolet-visible absorption spectroscopy analysis revealed that the vanadium content in the vanadium-containing leachate obtained in step S3 was... 3+ The proportion was 7.4%, V 4+ The proportion was 92.6%.

[0090] Example 6

[0091] This embodiment provides a method for preparing vanadium electrolyte, including the following steps:

[0092] S1: The vanadium slag is crushed to ensure that the proportion of particles with a diameter less than 74μm reaches more than 80% by mass. Then, it is mixed with a liquid medium with a pH of 2 at a solid-liquid mass ratio of 1:0.3 to obtain a mixture. The liquid medium is a 5% (w / w) H2SO4 solution and a 0.05 mol / L H2O2 solution.

[0093] S2: Add the mixture Figure 1 In the device shown, low-temperature calcination is carried out under pulsed DC electric field conditions. The power is set to 20kW and the uniaxial pressure is 30kN, so that the oxidation-reduction potential of the mixture is 1V. The mixture is calcined at 400℃ for 0.5h in an air atmosphere to obtain a solid-liquid mixture.

[0094] S3: Wash the calcined solid-liquid mixture with a small amount of water and filter it, such as... Figure 2 The vanadium-containing leaching solution and leaching tailings are shown.

[0095] S4: Dilute the vanadium-containing leachate with deionized water to raise the pH to approximately 3. Continue adding oxalic acid and stir the reaction at 20°C for 1 hour. After the reaction, further dilute with deionized water to raise the pH to approximately 3.2 and stir the reaction at 60°C for 1 hour. Then, add a small amount of H₂SO₄ to adjust the pH to approximately 1.8 and stir the reaction at 60°C for 1 hour. Further adjust the amounts of deionized water and H₂SO₄ added to stabilize the pH at 1.9, and stir the reaction at 60°C for 1 hour. After solid-liquid separation, the vanadium electrolyte is obtained.

[0096] The leachate obtained in step S3 was analyzed using inductively coupled plasma optical emission spectrometry (ICP-OES). Calculations showed that the vanadium leaching rate in this embodiment was 62.3%. UV-Vis ultraviolet-visible absorption spectroscopy analysis revealed that the vanadium content in the vanadium-containing leachate obtained in step S3 was... 3+ The proportion was 18.7%, V 4+ The proportion was 81.3%.

[0097] Example 7

[0098] This embodiment provides a method for preparing vanadium electrolyte, including the following steps:

[0099] S1: The vanadium slag is crushed to ensure that the proportion of particles with a diameter less than 74μm reaches more than 80% by mass. Then, it is mixed with a liquid medium with a pH of 2.5 at a solid-liquid mass ratio of 1:0.3 to obtain a mixture. The liquid medium is a 25% (w / w) H2SO4 solution and a 0.05 mol / L H2O2 solution.

[0100] S2: Add the mixture Figure 1 In the device shown, low-temperature calcination is carried out under pulsed DC electric field conditions. The power is set to 25kW and the uniaxial pressure is 28kN, so that the oxidation-reduction potential of the mixture is 0.85V. The mixture is calcined at 400℃ for 0.1-2h in an air atmosphere to obtain a solid-liquid mixture.

[0101] S3: Wash the calcined solid-liquid mixture with a small amount of water and filter it, such as... Figure 2 The vanadium-containing leaching solution and leaching tailings are shown.

[0102] S4: Dilute the vanadium-containing leachate with deionized water to raise the pH to approximately 3.1. Continue adding oxalic acid and stir the reaction at 20°C for 1 hour. After the reaction, further dilute with deionized water to raise the pH to approximately 3.2 and stir the reaction at 70°C for 1 hour. Then, add a small amount of H₂SO₄ to adjust the pH to approximately 1.9 and stir the reaction at 70°C for 1 hour. Further adjust the amounts of deionized water and H₂SO₄ added to stabilize the pH at 1.8, and stir the reaction at 70°C for 1 hour. After solid-liquid separation, the vanadium electrolyte is obtained.

[0103] The leachate obtained in step S3 was analyzed using inductively coupled plasma optical emission spectrometry (ICP-OES). Calculations showed that the vanadium leaching rate in this embodiment was 91.2%. UV-Vis ultraviolet-visible absorption spectroscopy analysis revealed that the vanadium content in the vanadium-containing leachate obtained in step S3 was... 3+ The proportion was 4.9%, V 4+ The percentage was 95.1%.

[0104] Example 8

[0105] This embodiment provides a method for preparing vanadium electrolyte, including the following steps:

[0106] S1: The vanadium slag is crushed to ensure that the proportion of particles with a diameter less than 74μm reaches more than 80% by mass. Then, it is mixed with a liquid medium with a pH of 4 at a solid-liquid mass ratio of 1:0.3 to obtain a mixture. The liquid medium is a 15% (w / w) H2SO4 solution and a 0.01 mol / L H2O2 solution.

[0107] S2: Add the mixture Figure 1 In the device shown, low-temperature calcination is carried out under pulsed DC electric field conditions. The power is set to 15kW and the uniaxial pressure is 20kN, so that the oxidation-reduction potential of the mixture is 0.65V. The mixture is calcined at 400℃ for 0.8h in an air atmosphere to obtain a solid-liquid mixture.

[0108] S3: Wash the calcined solid-liquid mixture with a small amount of water and filter it, such as... Figure 2 The vanadium-containing leaching solution and leaching tailings are shown.

[0109] S4: Dilute the vanadium-containing leachate with deionized water to raise the pH to approximately 3. Continue adding oxalic acid and stir the reaction at 25°C for 1 hour. After the reaction, further dilute with deionized water to raise the pH to approximately 3.2 and stir the reaction at 80°C for 1 hour. Then, add a small amount of H₂SO₄ to adjust the pH to approximately 1.8 and stir the reaction at 80°C for 1 hour. Further adjust the amounts of deionized water and H₂SO₄ added to stabilize the pH at 1.8, and stir the reaction at 80°C for 1 hour. After solid-liquid separation, the vanadium electrolyte is obtained.

[0110] The leachate obtained in step S3 was analyzed using inductively coupled plasma optical emission spectrometry (ICP-OES). Calculations showed that the vanadium leaching rate in this embodiment was 80.1%. UV-Vis ultraviolet-visible absorption spectroscopy analysis revealed that the vanadium content in the vanadium-containing leachate obtained in step S3 was... 3+ The proportion was 9.6%, V 4+ The proportion is 90.4%.

[0111] Example 9

[0112] This embodiment provides a method for preparing vanadium electrolyte, including the following steps:

[0113] S1: The vanadium slag is crushed to ensure that the proportion of particles with a diameter less than 74μm reaches more than 80% by mass. Then, it is mixed with a liquid medium with a pH of 2.9 at a solid-liquid mass ratio of 1:0.3 to obtain a mixture. The liquid medium is a 15% (w / w) H2SO4 solution and a 0.1 mol / L H2O2 solution.

[0114] S2: Add the mixture Figure 1 In the device shown, low-temperature calcination is carried out under pulsed DC electric field conditions. The power is set to 15kW and the uniaxial pressure is 20kN, so that the oxidation-reduction potential of the mixture is 0.9V. The mixture is calcined at 400℃ for 0.8h in an air atmosphere to obtain a solid-liquid mixture.

[0115] S3: Wash the calcined solid-liquid mixture with a small amount of water and filter it, such as... Figure 2 The vanadium-containing leaching solution and leaching tailings are shown.

[0116] S4: Dilute the vanadium-containing leachate with deionized water to raise the pH to approximately 3. Continue adding oxalic acid and stir the reaction at 25°C for 1 hour. After the reaction, further dilute with deionized water to raise the pH to approximately 3.2 and stir the reaction at 80°C for 1 hour. Then, add a small amount of H₂SO₄ to adjust the pH to approximately 1.8 and stir the reaction at 80°C for 1 hour. Further adjust the amounts of deionized water and H₂SO₄ added to stabilize the pH at 1.8, and stir the reaction at 80°C for 1 hour. After solid-liquid separation, the vanadium electrolyte is obtained.

[0117] The leachate obtained in step S3 was analyzed using inductively coupled plasma optical emission spectrometry (ICP-OES). Calculations showed that the vanadium leaching rate in this embodiment was 89.7%. UV-Vis ultraviolet-visible absorption spectroscopy analysis revealed that the vanadium content in the vanadium-containing leachate obtained in step S3 was... 3+ The proportion was 8.7%, V 4+ The proportion was 91.3%.

[0118] Example 10

[0119] This embodiment provides a method for preparing vanadium electrolyte. The difference from Embodiment 1 is that in step S4, deionized water is added to the vanadium-containing leachate to dilute it, raising the pH of the solution to approximately 3. Oxalic acid is then added, and the mixture is stirred at 25°C for 1 hour. After the reaction is complete, the mixture is allowed to stand and solid-liquid separation is performed to obtain the vanadium electrolyte.

[0120] Example 11

[0121] This embodiment provides a method for preparing vanadium electrolyte. The difference from Embodiment 1 is that in step S4, deionized water is added to the vanadium-containing leachate to dilute it, raising the pH of the solution to approximately 3. Oxalic acid is then added, and the mixture is stirred at 25°C for 1 hour. Next, deionized water is added again to dilute the solution, raising the pH to approximately 3.2, and the mixture is stirred at 80°C for 1 hour. After the reaction is complete, the mixture is allowed to stand and solid-liquid separation is performed to obtain the vanadium electrolyte.

[0122] Example 12

[0123] This embodiment provides a method for preparing vanadium electrolyte. The difference from Embodiment 1 is that in step S4, deionized water is added to the vanadium-containing leachate to dilute it, raising the pH to approximately 3. Oxalic acid is then added, and the mixture is stirred at 25°C for 1 hour. Next, deionized water is added again to dilute the solution, raising the pH to approximately 3.2, and the mixture is stirred at 80°C for 1 hour. A small amount of H₂SO₄ is then added to the solution to adjust the pH to approximately 1.8, and the mixture is stirred at 80°C for 1 hour. After the reaction is complete, the mixture is allowed to stand and solid-liquid separation is performed to obtain the vanadium electrolyte.

[0124] Comparative Example 1

[0125] This comparative example provides a conventional method for preparing a vanadium-containing solution by direct leaching with high-concentration sulfuric acid. The difference from Example 1 is that the liquid medium is a 40% (w / w) H₂SO₄ solution. After the H₂SO₄ solution and vanadium slag are mixed evenly, the mixture is stirred and leached at 200°C for 2 hours without applying an electric field or uniaxial pressure. After leaching, the solution is washed with water and filtered to obtain a vanadium-containing leachate.

[0126] Testing showed that the vanadium leaching rate in this comparative example was 87.7%, but the vanadium in the leachate was mainly in the form of V. 3+ Form exists, V 4+ The content was less than 5%, and the leachate exhibited a typical trivalent vanadium blue-green color. Regarding impurity content, the concentrations of Fe³⁺, Al³⁺, and Ca²⁺ in the leachate were significantly higher than in Example 1.

[0127] Comparative Example 2

[0128] This embodiment provides a method for preparing vanadium electrolyte, which differs from Embodiment 1 in that the pH of the liquid medium is 6.5 in step S1.

[0129] Testing revealed that the vanadium leaching rate in the vanadium-containing leachate prepared in this comparative example was 51.6%, but the vanadium in the leachate was mainly in the form of V. 5+ It exists in form.

[0130] The vanadium-containing leachate prepared in Examples 1-9 is as follows: Figure 2As shown in Table 2, the ions in the vanadium-containing leachates prepared in Examples 1-9 were further detected. The ions in the vanadium electrolytes prepared in Examples 1-12 after impurity removal were detected.

[0131] Table 2. Statistical table of vanadium and impurity content in vanadium-containing leachates prepared in Examples 1-9

[0132]

[0133] Table 3. Statistical table of impurity content after impurity removal in each embodiment.

[0134]

[0135] The vanadium electrolyte obtained in Example 1 was analyzed by X-ray photoelectron spectroscopy to determine the valence state of vanadium in the solution. Figure 3 . Figure 3 V2P 2 / 3 The peak position is the main basis for judging the valence state of V. 5+ V2p 2 / 3 It appears at a position of 517-517.5 eV. In this embodiment, V2p... 2 / 3 The highest peak occurred at 516.5 eV, indicating that V in the embodiment was at V. 3+ or V 4+ The specific valence state requires further detection using more advanced equipment, but given that the objective of this invention is to obtain a low valence state V, therefore... Figure 3 This is sufficient to demonstrate that Example 1 achieved its intended purpose. Therefore, Figure 3 The test results show that vanadium in the solution mainly exists as V 3+ and V 4+ The form exists, in which V 4+ The dominant valence state is V0. This indicates that the vanadium valence state was effectively controlled during the electric field-pressure coupled low-temperature calcination and subsequent pH adjustment. Furthermore, testing showed that vanadium in the vanadium electrolytes prepared in Examples 2-12 was also primarily in the V0 state. 3+ and V 4 + Form exists, V 4+ This is the primary valence state.

[0136] The original vanadium slag used in the examples and the leaching tailings prepared in Example 1 were respectively analyzed for morphology and elemental distribution using scanning electron microscopy. The results are shown in the figure. Figure 4 . Figure 4 The distribution of V in the original vanadium slag is relatively obvious, with some concentrated granular areas, but its distribution in the leaching tailings is very indistinct, and there is no concentrated granular distribution. Figure 4The test results show that, compared with the original vanadium slag, vanadium signals are almost undetectable in the leaching tailings, indicating that vanadium has migrated from the solid phase to the liquid phase. Furthermore, vanadium signals are also almost undetectable in the vanadium slag obtained in Examples 2-9, or very little vanadium remains.

[0137] The original vanadium slag used in the examples and the leaching tailings prepared in Example 1 were respectively subjected to phase analysis by X-ray diffraction, and the results are shown in the figure. Figure 5 . Figure 5 In the original vanadium slag, V was mainly distributed in spinel FeO•V₂O₃. After treatment in Example 1, the diffraction peaks of the V compounds disappeared, proving that V was enriched in the leachate. Therefore, through... Figure 5 The test results show that, compared with the original vanadium slag, the vanadium-related diffraction peaks in the leaching tailings are significantly weakened or disappeared, indicating that vanadium has been effectively introduced into the leachate. Similarly, X-ray diffraction phase analysis was performed on the original vanadium-containing raw materials and leaching tailings applicable to Examples 2-9, and the conclusions were consistent with those of Example 1. In summary, this invention achieves efficient extraction of vanadium from vanadium-containing raw materials through an electric field-pressure coupled low-temperature roasting method under relatively low temperature and short time conditions, and directly obtains vanadium in V... 3+ and V 4+ The electrolyte is primarily composed of vanadium. After impurity removal treatment, the impurity content in the resulting solution is significantly reduced, meeting the industrial application requirements for vanadium redox flow battery electrolytes.

[0138] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a vanadium electrolyte, characterized in that Includes the following steps: S1: Mix the vanadium-containing raw material with a liquid medium to obtain a mixture; S2: Under the action of electric field and uniaxial pressure, the mixture is roasted to oxidize the trivalent vanadium in the vanadium-containing raw material in situ to tetravalent vanadium and dissolve it into the liquid phase to obtain a solid-liquid mixture; S3: Wash the solid-liquid mixture, and after solid-liquid separation, obtain vanadium-containing crude liquid and solid residue; S4: The crude vanadium solution containing both trivalent and tetravalent vanadium is subjected to impurity removal treatment to obtain vanadium electrolyte.

2. The production method according to claim 1, characterized by, In step S1, the vanadium-containing raw material is at least one of vanadium slag, coal shale, and vanadium-titanium magnetite.

3. The preparation method according to claim 1, characterized in that, In step S1, the liquid medium is an acidic medium and / or an oxidizing medium, and the pH of the liquid medium is 1-5.

4. The method of claim 1, wherein, In step S1, the acidic medium is an H2SO4 solution, and the oxidizing medium is H2O2.

5. The preparation method according to claim 1, characterized in that, In step S1, the mass ratio of particles with a diameter of less than 74 μm in the vanadium-containing raw material is ≥80%.

6. The method of claim 1, wherein, In step S2, the calcination temperature is 100-800℃ and the calcination time is 0.1-2h.

7. The preparation method according to claim 1, characterized in that, In step S2, the electric field is a pulsed DC electric field with a power of 5-37kW, a uniaxial pressure of 5-50kN, and a redox potential of 0.4-1.2V.

8. The method of claim 1, wherein, In step S3, the solid-liquid mixture is washed with water or an acidic solution.

9. The method of claim 1, wherein, In step S4, the content of one or more ions of Fe 3+ , Al 3+ , Ca 2+ , Mg 2+ , Mn 2+ , Cr 3+ in the solution is reduced by adjusting the pH of the vanadium-containing crude solution.

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