A process for refining vanadium pentoxide

Abstract

The application relates to the technical field of purification, in particular to a refining process of vanadium pentoxide, which comprises the following steps: copolymerization of N-acryloyl morpholine, 3-acrylamido phenol and methyl methacrylate, solidification into balls, purification and acid activation to prepare a ternary chelating resin, enrichment of vanadium ions by using a fixed bed dynamic adsorption, alkaline desorption, hydrolysis precipitation and calcination to prepare vanadium pentoxide. By ball formation regulation and activation optimization, high-selectivity adsorption and high-efficiency desorption of vanadium ions can be realized, and the vanadium yield and product purity are effectively improved.

Description

Technical Field

[0001] This invention relates to the field of purification technology, and in particular to a refining process for vanadium pentoxide. Background Technology

[0002] Vanadium resources are widely distributed in nature but are of low grade, mainly occurring in raw materials such as vanadium-titanium magnetite, coal shale, and spent catalysts. The refining process requires specific techniques to separate and purify vanadium from these raw materials, ultimately yielding vanadium pentoxide. Currently, the mainstream industrial vanadium pentoxide refining processes are mainly divided into two categories: pyrometallurgical processes and hydrometallurgical processes. Both processes have undergone long-term practical application and have formed relatively mature technical routes, but many problems still need to be solved.

[0003] Pyrometallurgical refining is a traditional vanadium extraction technology. Its core idea is to convert vanadium in the raw material into soluble vanadium compounds through high-temperature roasting and other treatments, followed by leaching, separation, and purification steps to obtain vanadium pentoxide. Common pyrometallurgical processes include sodium roasting, calcification roasting, and smelting. The smelting process requires mixing vanadium-containing raw materials with other auxiliary materials and then smelting at high temperatures to form vanadium-enriched slag, which is then subjected to subsequent hydrometallurgical treatment. The advantage of this type of process is its strong adaptability to raw materials, capable of processing various types of vanadium-containing raw materials. However, it generally suffers from high energy consumption, complex equipment requirements, and the generation of harmful gases during high-temperature roasting or smelting, causing environmental pollution. Furthermore, the process flow is relatively lengthy, and vanadium loss may occur during subsequent slag-gold separation, affecting refining efficiency.

[0004] Hydrometallurgical refining is a clean extraction technology that has seen rapid development in recent years. Its main processes include raw material pretreatment, leaching, purification, vanadium precipitation, and calcination. It eliminates the need for high-temperature roasting, thus having a relatively small environmental impact. Depending on the leaching reagent, hydrometallurgical processes can be categorized into acid leaching, alkaline leaching, etc. Some processes also combine solvent extraction, ion exchange, and chemical precipitation to remove impurities such as iron, aluminum, silicon, and phosphorus from the leachate, thereby improving product purity. While hydrometallurgical processes offer advantages such as lower energy consumption and better environmental friendliness, they still have significant drawbacks in practical applications: impurities in the leachate can easily lead to emulsification and phase separation difficulties during extraction, affecting purification efficiency; some processes consume large amounts of reagents, increasing production costs and potentially generating large amounts of wastewater, which is difficult to treat subsequently; furthermore, hydrometallurgical processes require high-level pretreatment of raw materials, often making efficient extraction difficult for low-grade, high-impurity vanadium-containing raw materials, resulting in low vanadium recovery rates.

[0005] Furthermore, with increasing global demands for environmental protection and resource utilization efficiency, the shortcomings of existing refining processes are becoming increasingly apparent: pyrometallurgical processes, with their high energy consumption and pollution, contradict the concept of green development, while hydrometallurgical processes face challenges in impurity treatment and cost control, limiting their large-scale application. Simultaneously, with the growing demand for high-purity vanadium pentoxide in fields such as new energy and aerospace, existing processes struggle to fully meet the purity requirements of high-end applications. Therefore, it is essential to develop a vanadium pentoxide refining process that is energy-efficient, environmentally friendly, highly efficient, and capable of consistently producing high-purity products. Summary of the Invention

[0006] To address the problems mentioned in the background section, the present invention provides a vanadium pentoxide refining process.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] This invention discloses a refining process for vanadium pentoxide, specifically including the following steps:

[0009] S1: N-acryloylmorpholine, 3-acrylamidophenol and methyl methacrylate are dissolved in an organic solvent, and the total monomer concentration is controlled at 10%-20% (mass-volume ratio). After stirring until completely dissolved, a copolymerization reaction is carried out under the action of an initiator to obtain a copolymer solution. The copolymer solution is dropped into a dispersion to solidify into spheres. During the solidification process, stirring is maintained until the resin microspheres are formed. After purification, acid activation and drying, a ternary copolymer chelated resin is obtained.

[0010] In step S1, the copolymerization reaction involves a mass ratio of N-acryloylmorpholine (CAS: 5117-12-4):3-acrylamidophenol (CAS: 13040-21-6):methyl methacrylate of 1:(0.72-0.81):(0.27-0.35). The organic solvent is N,N-dimethylformamide. The initiator is azobisisobutyronitrile, and its dosage is 0.5%-1.5% of the total monomer mass. The initiator is added in batches, with 50% added at the beginning of the reaction and the remaining 50% added after 2 hours of reaction. The copolymerization reaction is carried out under the protection of an inert gas, namely nitrogen or argon, with a gas flow rate controlled at 50-100 mL / min, a reaction temperature of 65-75℃, and a reaction time of 4-6 hours. The dispersion is a polyvinyl alcohol aqueous solution with a mass concentration of 1%-3%. The curing process involves adding the copolymer solution dropwise into the polyvinyl alcohol aqueous solution under stirring at a rate of 1-3 mL / min and a stirring speed of 200-300 r / min.

[0011] The purification process in step S1 specifically involves: placing the cured resin microspheres in a Soxhlet extractor and refluxing with methanol for 20-28 hours to remove unreacted monomers and oligomers, with the reflux rate controlled at 1-2 drops / second; the acid activation involves soaking the resin in a 1-2 mol / L hydrochloric acid solution for 12-24 hours, stirring every 4 hours during the soaking process, at a soaking temperature of 20-30℃; after soaking, washing with deionized water until the pH of the washing solution reaches 6.5-7.5. The drying process specifically involves: placing the acid-activated resin microspheres in a vacuum drying oven, controlling the vacuum level at 0.06-0.08 MPa, the drying temperature at 60-80℃, the drying time at 4-8 hours, and the drying heating rate at 3-5℃ / min; after drying, the resin microsphere particle size is 0.3-0.8 mm, and the particle size is measured using a laser particle size analyzer, with a particle size distribution deviation not exceeding ±0.1 mm.

[0012] S2: The vanadium-containing acidic leachate is passed into a fixed-bed ion exchange column packed with the ternary copolymer chelating resin for dynamic adsorption. Before adsorption, the leachate is filtered through a 0.22-0.45μm filter membrane to remove suspended impurities. The operating flow rate is controlled until the vanadium concentration in the effluent reaches the breakthrough point, thus completing the adsorption process.

[0013] In step S2, the vanadium-containing acidic leachate has a pH value of 0-1.5 and contains V (V) and Fe. 3+ and Al 3+ Ions, wherein the concentration of V(V) is 1-5 g / L, Fe 3+ Concentration of 0.5-2 g / L, Al 3+ The concentration is 0.3-1.5 g / L; the operating flow rate of the dynamic adsorption is 2-6 BV / h, the adsorption temperature is 20-35℃, and the column pressure is kept stable at 0.1-0.2 MPa during the adsorption process. The fixed-bed ion exchange column has a height-to-diameter ratio of 3-8:1, and the column material is polytetrafluoroethylene or glass. During the adsorption process, the vanadium concentration in the effluent is measured every 1-2 hours using spectrophotometry. The breakthrough point is defined as a vanadium concentration in the effluent reaching 0.1-0.3 g / L, and the criterion for determining the breakthrough point is that two consecutive concentration measurements both reach this range.

[0014] S3: Dynamically elute the saturated resin bed using an alkaline desorbent. Before elution, rinse the resin bed with deionized water for 2-3 BV to remove surface-adsorbed impurities and collect the vanadium-rich desorbate.

[0015] In step S3, the alkaline desorbent is a sodium hydroxide solution with a concentration of 0.2-0.5 mol / L; the desorption flow rate is 1-2 BV / h; the desorption temperature is 35-50℃; the amount of desorbent used is 3-5 BV; and the desorption endpoint is when the vanadium concentration in the effluent is lower than 0.05 g / L.

[0016] S4: Adjust the pH of the desorption solution to acidic. During the adjustment process, slowly add acid solution and stir continuously. Heat and hydrolyze to generate metavanadate precipitate. After solid-liquid separation, washing and calcination, vanadium pentoxide product is obtained.

[0017] Step S4 specifically includes: adjusting the pH of the desorption solution to 1.8-2.2 with sulfuric acid (concentration 1-2 mol / L), heating to 85-95℃ and stirring for 1-3 hours at a stirring speed of 200-300 r / min; filtering after cooling, washing the precipitate with deionized water, and then calcining it in a muffle furnace at 480-520℃ for 1-2 hours at a heating rate of 5-10℃ / min. The solid-liquid separation is performed using vacuum filtration at a pressure of 0.03-0.05 MPa, using a filter membrane with a pore size of 0.22-0.45 μm and made of polytetrafluoroethylene (PTFE); washing is stopped when the pH of the washing solution reaches 6.5-7.5, using small amounts of water multiple times, with each wash using 2-3 times the amount of precipitate.

[0018] The beneficial effects of this invention are:

[0019] 1. In step S1 of this invention, the terpolymer chelating resin prepared by copolymerizing N-acryloylmorpholine, 3-acrylamidophenol, and methyl methacrylate in a specific mass ratio possesses a specific functional group structure, which can specifically form a stable chelating effect with V(V) in the vanadium-containing acidic leachate, while inhibiting the coexisting Fe in the leachate. 3+ Al 3+ The adsorption capacity of impurity ions is extremely weak. Compared with the problems of emulsification, phase separation difficulties and incomplete impurity separation that are easy to occur in the extraction process of existing wet processes, this invention can achieve efficient separation of V (V) and impurity ions. Combined with the control of dynamic adsorption parameters in step S2 and the optimization of hydrolysis and washing processes in step S4, the impact of impurity residue on product purity can be effectively avoided.

[0020] 2. After purification and acid activation, the ternary copolymer chelating resin possesses stable adsorption capacity and efficiency. In step S2, controlling appropriate adsorption flow rate, temperature, and column parameters allows V(V) in the vanadium-containing acidic leachate to be fully adsorbed by the resin until the breakthrough point is reached, reducing vanadium loss during the adsorption process. Simultaneously, in step S3, using a specific concentration of sodium hydroxide solution as a desorbent and controlling the desorption flow rate and temperature allows for efficient desorption of saturated V(V), ensuring thorough desorption without causing resin performance degradation. Combined with the precise control of the hydrolysis and calcination processes in step S4, vanadium loss in subsequent processing is further reduced. Compared to the low vanadium recovery rate of existing wet processes, this invention can significantly improve the utilization rate of vanadium resources and reduce resource waste.

[0021] 3. This invention adopts a wet process route, eliminating the need for high-temperature roasting and smelting processes found in existing pyrometallurgical processes. This effectively reduces energy consumption and avoids the generation of harmful gases during high-temperature processes. Simultaneously, the optimization of the copolymerization reaction, solidification into spheres, and purification processes in step S1 reduces the residue of unreacted monomers and oligomers, minimizing reagent waste. The control of desorbent concentration and dosage in step S3 reduces wastewater generation, and the desorbent solution can be fully utilized through subsequent hydrolysis. The washing wastewater in step S4 can be recycled after simple treatment. Compared to the drawbacks of existing wet processes (high reagent consumption, difficult wastewater treatment), and pyrometallurgical processes (high pollution), this invention significantly reduces environmental pollution risks, simplifies wastewater treatment processes, and meets the requirements of green industrial production. Detailed Implementation

[0022] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] Example 1

[0024] A refining process for vanadium pentoxide includes the following steps:

[0025] S1: Dissolve 10g of N-acryloylmorpholine, 7.2g of 3-acrylamidophenol, and 2.7g of methyl methacrylate in 199mL of N,N-dimethylformamide, resulting in a total monomer mass of 19.9g and a mass-volume concentration of approximately 10%. Add 0.1g of azobisisobutyronitrile (AIBN), representing 0.5% of the total monomer mass, with 0.05g added at the start of the reaction and the remaining 0.05g added after 2 hours of reaction. Under nitrogen protection, with a gas flow rate controlled at 50mL / min, copolymerize at 65℃ for 4 hours to obtain a copolymer solution. Drop the copolymer solution dropwise at 1mL / min into 1000mL of a 1% (w / w) polyvinyl alcohol aqueous solution, while stirring at 200r / min, and solidify into spheres. The cured resin microspheres were placed in a Soxhlet extractor and extracted under reflux for 20 hours with 200 mL of methanol. They were then soaked in 100 mL of 1 mol / L hydrochloric acid solution for 12 hours. After soaking, the microspheres were repeatedly washed with deionized water until the pH of the washing solution reached 6.5. Finally, the resin microspheres were placed in a vacuum drying oven at a vacuum of 0.06 MPa and a drying temperature of 60 °C for 4 hours to obtain a terpolymer chelated resin with a particle size of 0.3 mm.

[0026] S2: Take 1000 mL of vanadium-containing acidic leachate with a pH of 0, containing 1 g V (V) and 0.5 g Fe. 3+and 0.3gAl 3+ The leachate was filtered through a 0.22 μm filter membrane and then passed into a fixed-bed ion exchange column made of polytetrafluoroethylene (PTFE) with a height-to-diameter ratio of 3:1. The column was packed with 50 g of the aforementioned terpolymer chelating resin. The operating flow rate was controlled at 2 BV / h, with the effluent volume per hour being twice the resin bed volume (approximately 50 mL), corresponding to a flow rate of 100 mL / h. The adsorption temperature was controlled at 20°C, and the column pressure was stabilized at 0.1 MPa. The vanadium concentration in the effluent was measured spectrophotometrically every hour. The adsorption process was considered complete when two consecutive measurements showed a concentration of 0.1 g / L, indicating the breakthrough point.

[0027] S3: First, rinse the saturated resin bed with 100 mL of deionized water (2 BV), resulting in a resin bed volume of 50 mL. Then, use a 0.2 mol / L sodium hydroxide solution as an alkaline desorbent, controlling the desorption flow rate at 1 BV / h (corresponding to a flow rate of 50 mL / h) and the desorption temperature at 35℃. Add 150 mL of the desorbent (3 BV). Stop desorption when the vanadium concentration in the effluent is below 0.05 g / L, and collect the vanadium-rich eluent.

[0028] S4: Slowly add 1 mol / L sulfuric acid solution dropwise to the above desorption solution, adjust the pH to 1.8, heat to 85℃ and stir at a constant speed of 200 r / min for 1 hour for hydrolysis. After cooling, perform solid-liquid separation by vacuum filtration, controlling the filtration pressure at 0.03 MPa. Use a 0.22 μm pore size filter membrane made of polytetrafluoroethylene. Wash the precipitate with deionized water in small amounts multiple times, each time using twice the amount of water as the precipitate, until the pH of the washing solution reaches 6.5. Place the precipitate in a muffle furnace and heat to 480℃ at a heating rate of 5℃ / min, calcine for 1 hour to obtain vanadium pentoxide product.

[0029] Example 2

[0030] A refining process for vanadium pentoxide includes the following steps:

[0031] S1: Dissolve 10g of N-acryloylmorpholine, 7.6g of 3-acrylamidophenol, and 3.1g of methyl methacrylate in 103.5mL of N,N-dimethylformamide, resulting in a total monomer mass of 20.7g and a mass-volume concentration of approximately 20%. Add 0.207g of azobisisobutyronitrile (AIBN), representing 1.0% of the total monomer mass, with 0.1035g added at the start of the reaction and the remaining 0.1035g added after 2 hours of reaction. Under argon protection, with a gas flow rate controlled at 75mL / min, copolymerize at 70℃ for 5 hours to obtain a copolymer solution. Add the copolymer solution dropwise at a rate of 2mL / min to 1000mL of a 2% (w / w) polyvinyl alcohol aqueous solution, while stirring at 250r / min, until solidified into spheres. The cured resin microspheres were placed in a Soxhlet extractor and extracted under reflux for 24 hours with 200 mL of methanol. They were then soaked in 100 mL of 1.5 mol / L hydrochloric acid solution for 18 hours. After soaking, the microspheres were repeatedly washed with deionized water until the pH of the washing solution reached 7.0. Finally, the resin microspheres were placed in a vacuum drying oven at a vacuum of 0.07 MPa and a drying temperature of 70 °C for 6 hours to obtain a terpolymer chelated resin with a particle size of 0.55 mm.

[0032] S2: Take 1000mL of vanadium-containing acidic leachate with a pH of 0.8, containing 3gV and 1.2gFe. 3+ and 0.9gAl 3+ The leachate was filtered through a 0.30 μm filter membrane and then passed into a fixed-bed ion exchange column made of glass with a height-to-diameter ratio of 5:1. The column was packed with 50 g of the aforementioned terpolymer chelating resin. The operating flow rate was controlled at 4 BV / h, corresponding to a flow rate of 200 mL / h, the adsorption temperature was controlled at 28℃, and the column pressure was stabilized at 0.15 MPa. The vanadium concentration in the effluent was measured spectrophotometrically every 1.5 hours. The adsorption process was considered complete when two consecutive measurements showed a concentration of 0.2 g / L, indicating the breakthrough point.

[0033] S3: First, rinse the saturated resin bed with 125 mL of deionized water (2.5 BV), resulting in a resin bed volume of 50 mL. Then, use a 0.35 mol / L sodium hydroxide solution as an alkaline desorbent, controlling the desorption flow rate at 1.5 BV / h (corresponding to a flow rate of 75 mL / h) and the desorption temperature at 42℃. Add 200 mL of desorbent (4 BV). Stop desorption when the vanadium concentration in the effluent is below 0.05 g / L, and collect the vanadium-rich eluent.

[0034] S4: Slowly add 1.5 mol / L sulfuric acid solution dropwise to the above desorption solution, adjust the pH to 2.0, heat to 90℃ and stir at a constant temperature of 250 r / min for 2 hours for hydrolysis. After cooling, perform solid-liquid separation by vacuum filtration, controlling the filtration pressure at 0.04 MPa. Use a 0.30 μm pore size filter membrane made of polytetrafluoroethylene. Wash the precipitate with deionized water in small amounts multiple times, each time using 2.5 times the amount of precipitate, until the pH of the washing solution reaches 7.0. Place the precipitate in a muffle furnace and heat to 500℃ at a heating rate of 7℃ / min, calcining for 1.5 hours to obtain vanadium pentoxide product.

[0035] Example 3

[0036] A refining process for vanadium pentoxide includes the following steps:

[0037] S1: Dissolve 10g of N-acryloylmorpholine, 8.1g of 3-acrylamidophenol, and 3.5g of methyl methacrylate in 108mL of N,N-dimethylformamide, resulting in a total monomer mass of 21.6g and a mass-volume concentration of approximately 20%. Add 0.324g of azobisisobutyronitrile (AIBN), representing 1.5% of the total monomer mass, with 0.162g added at the start of the reaction and the remaining 0.162g added after 2 hours of reaction. Under nitrogen protection, with a gas flow rate controlled at 100mL / min, perform a copolymerization reaction at 75℃ for 6 hours to obtain a copolymer solution. Drop the copolymer solution dropwise at a rate of 3mL / min into 1000mL of a 3% (w / w) polyvinyl alcohol aqueous solution, while stirring at 300r / min, and solidify into spheres. The cured resin microspheres were placed in a Soxhlet extractor and extracted under reflux for 28 hours with 200 mL of methanol. They were then soaked in 100 mL of 2 mol / L hydrochloric acid solution for 24 hours. After soaking, the microspheres were repeatedly washed with deionized water until the pH of the washing solution reached 7.5. Finally, the resin microspheres were placed in a vacuum drying oven at a vacuum of 0.08 MPa and a drying temperature of 80 °C for 8 hours to obtain a terpolymer chelated resin with a particle size of 0.8 mm.

[0038] S2: Take 1000 mL of vanadium-containing acidic leachate with a pH of 1.5, containing 5 g V (V) and 2 g Fe. 3+ and 1.5gAl 3+The leachate was filtered through a 0.45 μm filter membrane and then passed into a fixed-bed ion exchange column made of polytetrafluoroethylene (PTFE) with a height-to-diameter ratio of 8:1. The column was packed with 50 g of the aforementioned terpolymer chelating resin. The operating flow rate was controlled at 6 BV / h (corresponding to a flow rate of 300 mL / h), the adsorption temperature was controlled at 35℃, and the column pressure was stabilized at 0.2 MPa. The vanadium concentration in the effluent was measured spectrophotometrically every 2 hours. The adsorption process was considered complete when two consecutive measurements showed a concentration of 0.3 g / L, indicating the breakthrough point.

[0039] S3: First, rinse the saturated resin bed with 150 mL of deionized water (3 BV), resulting in a resin bed volume of 50 mL. Then, use a 0.5 mol / L sodium hydroxide solution as an alkaline desorbent, controlling the desorption flow rate at 2 BV / h (corresponding to a flow rate of 100 mL / h) and the desorption temperature at 50℃. Add 250 mL of desorbent (5 BV). Stop desorption when the vanadium concentration in the effluent is below 0.05 g / L, and collect the vanadium-rich eluent.

[0040] S4: A 2 mol / L sulfuric acid solution was slowly added dropwise to the above desorption solution to adjust the pH to 2.2. The solution was then heated to 95°C and hydrolyzed by constant stirring at 300 rpm for 3 hours. After cooling, solid-liquid separation was performed by vacuum filtration, controlling the filtration pressure at 0.05 MPa. The filter membrane used had a pore size of 0.45 μm and was made of polytetrafluoroethylene. The precipitate was washed with deionized water in small, repeated washes, each using three times the amount of water as the precipitate, until the pH of the washing solution reached 7.5. The precipitate was then placed in a muffle furnace and calcined at 520°C at a heating rate of 10°C / min for 2 hours to obtain vanadium pentoxide.

[0041] Comparative Example 1

[0042] The difference between this comparative example and Example 1 is that N-acryloylmorpholine is not added; instead, 7.2g of 3-acrylamidophenol and 2.7g of methyl methacrylate are used as monomers for the copolymerization reaction. The remaining steps and amounts are exactly the same as in Example 1.

[0043] Comparative Example 2

[0044] The difference between this comparative example and Example 2 is that hydrochloric acid solution is not added for acid activation treatment, and the resin microspheres are directly dried after purification. The remaining steps and dosages are exactly the same as in Example 2.

[0045] Comparative Example 3

[0046] The difference between this comparative example and Example 3 is that no polyvinyl alcohol aqueous solution is added; instead, the copolymer solution is directly dropped into distilled water to solidify into spheres. The remaining steps and amounts are exactly the same as in Example 3.

[0047] (a) Static adsorption performance test

[0048] Accurately weigh 0.50 g of each of the six chelating resins prepared in Examples 1-3 and Comparative Examples 1-3, and place them separately into 250 mL stoppered conical flasks. Measure 50 mL of a uniformly prepared simulated vanadium-containing acidic leachate (containing V(V) 3 g / L, Fe) using a graduated cylinder. 3+ 1.2g / L, Al 3+ Add 0.9 g / L (pH=0.8) to each conical flask and tighten the stopper. Place the conical flask in a constant temperature shaker at 25℃ and 150 r / min, and shake continuously for 24 hours until adsorption equilibrium is reached. After removal, let stand for 10 min, filter the supernatant through a 0.22 μm filter membrane, and transfer 5 mL of the filtrate to a volumetric flask. Dilute to 50 mL with deionized water. Determine the residual concentrations of V, Fe, and Al in the filtrate using inductively coupled plasma atomic emission spectrometry (ICP-AES). Perform three parallel measurements for each sample and take the average value. Calculate the equilibrium adsorption capacity using the following formula:

[0049]

[0050] In the formula: qe is the equilibrium adsorption capacity (mg / g), C0 is the initial concentration (mg / L), Ce is the equilibrium concentration (mg / L), V is the solution volume (L), and m is the dry mass of the resin (g).

[0051] (II) Dynamic adsorption-desorption performance test

[0052] 1. Dynamic adsorption breakthrough curve

[0053] Weigh 50.0 g (dry basis) of each of the six chelating resins prepared in Examples 1-3 and Comparative Examples 1-3, and pack them into a fixed-bed ion exchange column with a height-to-diameter ratio of 5:1. The column material is glass, with an inner diameter of 20 mm, and the resin bed volume is approximately 50 mL. After packing, rinse the bed with deionized water at a flow rate of 2 BV / h for 30 min to remove air bubbles and compact the bed. Take 1000 mL of a uniformly prepared simulated vanadium-containing acidic leachate, filter it through a 0.30 μm filter membrane, and use it as the feed solution. Adjust the peristaltic pump flow rate to 3 BV / h, corresponding to a flow rate of approximately 150 mL / h, control the adsorption temperature at 25 °C, and stabilize the column pressure at 0.15 MPa. Starting from the beginning of effluent collection, collect effluent samples every hour using an automatic fraction collector, and determine the vanadium concentration in the effluent at a wavelength of 380 nm using spectrophotometry. When the vanadium concentration in the effluent reaches 0.2 g / L twice consecutively, this moment is recorded as the breakthrough point, and feeding is stopped. A dynamic adsorption breakthrough curve is plotted with time on the x-axis and vanadium concentration in the effluent on the y-axis. The breakthrough adsorption capacity and saturation adsorption capacity are calculated. Each group of resins is tested twice in parallel, and the average value is taken as the dynamic adsorption test result for that sample.

[0054] 2. Desorption performance test

[0055] For each resin column that has been saturated with adsorption, the resin bed was first rinsed with 100 mL of deionized water at a flow rate of 2 BV / h to remove any remaining unadsorbed metal ions. Then, a 0.35 mol / L sodium hydroxide solution was used as the desorbent, with the desorption flow rate controlled at 1.5 BV / h (approximately 75 mL / h) and the desorption temperature at 35℃. The desorbed effluent was collected using an automatic fraction collector, once every 0.5 BV, for a total of 4 BV. The vanadium concentration in the desorbate was measured at each collection point, and the cumulative desorption amount and desorption rate were calculated.

[0056]

[0057] (III) Preparation and Testing of Vanadium Pentoxide Products

[0058] 1. Product Preparation

[0059] Vanadium-rich desorption solutions (combined first 4 BV solutions) from each group of desorption experiments in Examples 1-3 and Comparative Examples 1-3 were collected separately. The volume of the desorption solution was measured and the vanadium concentration was determined. The desorption solution was transferred to a 500 mL beaker, and 1.5 mol / L sulfuric acid solution was slowly added dropwise under magnetic stirring to adjust the pH to 2.0. The dropping rate was controlled at 1-2 drops per second to avoid excessive local acidity. The beaker was placed in a constant temperature water bath and heated to 90°C. Hydrolysis was carried out by stirring at 250 r / min for 2 hours. After the beaker was removed and allowed to cool naturally to room temperature, solid-liquid separation was performed using a vacuum filtration device. The filtration pressure was controlled at 0.04 MPa, and the filter membrane had a pore size of 0.30 μm and was made of polytetrafluoroethylene. The precipitate was washed with deionized water in small amounts multiple times, with each wash using 2.5 times the amount of precipitate. The washing was repeated 4-6 times until the pH of the washing solution reached 7.0. The washed precipitate was dried in a 105℃ drying oven for 2 hours, then transferred to a muffle furnace and heated to 500℃ at a rate of 7℃ / min for calcination for 1.5 hours. After cooling to room temperature, it was removed, weighed, and the vanadium pentoxide product was obtained and stored in a desiccator for later analysis.

[0060] 2. Product purity testing

[0061] Weigh approximately 0.20 g of vanadium pentoxide product from each group and place it in a 250 mL Erlenmeyer flask. Add 10 mL of sulfuric acid and heat to dissolve. After cooling, add 50 mL of deionized water. The V₂O₅ content is determined using the potassium permanganate oxidation-ferrous ammonium sulfate titration method: first, vanadium is oxidized to pentavalent oxidation state using potassium permanganate solution; excess potassium permanganate is reduced with sodium nitrite. Using N-phenyl-o-aminobenzoic acid as an indicator, titration is performed with ferrous ammonium sulfate standard solution until the solution changes from purple-red to bright green, which is the endpoint. Calculate the V₂O₅ purity using the following formula:

[0062]

[0063] In the formula: C is the concentration of ferrous ammonium sulfate standard solution (mol / L), V is the volume consumed in titration (mL), m is the sample mass (g), and 0.09094 is the millimolecular mass of V2O5 (g / mmol).

[0064] 3. Product Yield Calculation

[0065] Calculate the overall vanadium yield for each process group using the following formula:

[0066]

[0067] In the formula: m product is the mass of vanadium pentoxide (g), m total vanadium in the desorption solution is the total mass of vanadium in the desorption solution (g), MV2O5 is the molar mass of vanadium pentoxide (181.88 g / mol), and MV is the molar mass of vanadium (50.94 g / mol).

[0068] The results are shown in Table 1:

[0069] Table 1. Experimental results of different embodiments and comparative examples

[0070]

[0071] As shown in Table 1, the equilibrium adsorption capacity of the ternary copolymer chelating resins prepared in Examples 1-3 for V(V) was between 89.67 mg / g and 98.75 mg / g, and the dynamic saturated adsorption capacity was between 55.34 mg / g and 63.78 mg / g. The desorption rates were all higher than 92%, and the purity of the final vanadium pentoxide product was all above 98.67%, with a vanadium yield all above 86%. Simultaneously, the resins also showed good performance in adsorbing Fe. 3+ Al 3+ The equilibrium adsorption capacities of impurity ions were all below 2.5 mg / g, indicating that the ternary copolymer chelating resin prepared in the examples possesses excellent vanadium adsorption selectivity, high adsorption capacity, and stable desorption and regeneration performance, enabling efficient and high-purity refining of vanadium pentoxide. This invention introduces two core chelating functional groups—tertiary amine groups of the morpholine ring and phenolic hydroxyl groups—into the resin skeleton through the ternary copolymerization of N-acryloylmorpholine, 3-acrylamidophenol, and methyl methacrylate. These two groups can form stable five- or six-membered chelate rings with V(V) in the acidic leachate through coordination bonds, achieving specific and strong adsorption of V(V). Simultaneously, the steric hindrance and charge repulsion effect of the functional groups effectively shield Fe... 3+ Al 3+The non-specific adsorption of impurity ions significantly improved the vanadium adsorption selectivity of the resin. Simultaneously, a suspension-curing spherical process controlled by polyvinyl alcohol aqueous solution was used to prepare spherical resins with uniform particle size and interconnected pore structures, effectively reducing the mass transfer resistance of vanadium ions within the resin and improving adsorption kinetics and desorption efficiency. Further activation treatment with hydrochloric acid fully unblocked the resin pores and activated the coordination activity of functional groups, further enhancing the resin's adsorption capacity and desorption / regeneration stability, ultimately achieving efficient enrichment of vanadium and the preparation of high-purity vanadium pentoxide products.

[0072] Comparative Example 1 omitted the addition of N-acryloylmorpholine monomer and used only 3-acrylamidophenol and methyl methacrylate for binary copolymerization. Its equilibrium adsorption capacity for V(V) was only 62.15 mg / g, a decrease of 30.7% compared to Example 1. The dynamic saturated adsorption capacity was only 38.76 mg / g, and the desorption rate decreased to 82.15%. The final product purity and vanadium yield also decreased to 95.23% and 72.15%, respectively. Meanwhile, the Fe... 3+ Al 3+ The impurity adsorption capacity was more than double that of Example 1. This is because the tertiary amine group of the morpholine ring introduced by N-acryloylmorpholine is the core functional group for the resin to specifically chelate and adsorb V(V). Without this group, the chelating coordination ability of the resin is greatly reduced, and the adsorption capacity and adsorption selectivity for V(V) are significantly reduced. At the same time, the steric hindrance effect of the morpholine ring disappears, and it is unable to effectively block the binding of impurity ions to the adsorption sites inside the resin, resulting in a significant increase in non-specific adsorption of impurities, ultimately leading to a decrease in product purity and a decrease in vanadium yield.

[0073] Comparative Example 2 omitted the hydrochloric acid activation step. The resin microspheres were directly dried after purification and used. The equilibrium adsorption capacity for V(V) was 78.43 mg / g, a decrease of 17.7% compared to Example 2. The dynamic saturated adsorption capacity was only 46.89 mg / g, the desorption rate decreased to 88.67%, and the final vanadium yield decreased to 78.43%. The amount of impurities adsorbed also increased significantly. This is because hydrochloric acid activation is a crucial step in fully activating the resin's adsorption performance. Acid soaking removes unreacted monomers, oligomers, and other impurities remaining from the resin synthesis process, clears the internal pore structure of the resin, and significantly increases the specific surface area and the number of effective adsorption sites. Simultaneously, acid activation protonates the functional groups such as amine and phenolic hydroxyl groups in the resin, enhancing their electron-donating ability and coordination chelation efficiency, further strengthening the repulsion effect against impurity ions. Without the acid activation step, the internal pores of the resin were blocked by residual impurities, resulting in insufficient effective adsorption sites and insufficient activation of the coordination activity of functional groups. This led to a significant decrease in adsorption capacity, selectivity, and desorption efficiency, ultimately resulting in a significantly lower vanadium yield.

[0074] Comparative Example 3 omitted the addition of polyvinyl alcohol aqueous solution, and directly added the copolymer solution to distilled water to solidify into spheres. Its equilibrium adsorption capacity for V(V) was 72.89 mg / g, a decrease of 26.2% compared to Example 3. The dynamic saturated adsorption capacity was only 42.34 mg / g, the desorption rate decreased to 85.32%, and the final product purity and vanadium yield decreased to 95.89% and 75.67%, respectively. The amount of impurities adsorbed also increased significantly. This is because polyvinyl alcohol is a typical nonionic surfactant. During the copolymer solidification process, it can inhibit the aggregation and adhesion of copolymer droplets through steric hindrance and emulsification, ensuring uniform droplet dispersion and ultimately forming resin microspheres with uniform particle size and good sphericity. Simultaneously, it can regulate the copolymer solidification rate, causing the resin to form a uniform and interconnected pore structure, avoiding pore collapse and structural densification caused by excessively rapid solidification. Without the regulatory effect of polyvinyl alcohol, copolymer droplets are prone to agglomeration and adhesion during the curing process. The resulting resin microspheres have poor sphericity, uneven particle size distribution, and dense internal pore structure with poor permeability. This not only leads to a significant decrease in the specific surface area of ​​the resin and the number of effective adsorption sites, but also causes a significant increase in the mass transfer resistance of vanadium ions inside the resin. Vanadium desorption is incomplete during the desorption process, ultimately resulting in a significant decrease in adsorption capacity, desorption rate and selectivity, as well as a decrease in product purity and vanadium yield.

[0075] In summary, this invention constructs a chelating resin through ternary copolymerization of N-acryloylmorpholine, 3-acrylamidophenol, and methyl methacrylate, and combines it with polyvinyl alcohol to regulate the spherical structure and hydrochloric acid activation to optimize the adsorption sites, thereby achieving highly selective adsorption and efficient desorption of vanadium ions, ensuring vanadium yield and product purity.

[0076] In the description of this specification, the terms "preparation example," "example," "various examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that example or preparation example, which are included in at least one example or preparation example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same example or preparation example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more examples or preparation examples.

[0077] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A refining process for vanadium pentoxide, characterized in that, Includes the following steps: S1: N-acryloylmorpholine, 3-acrylamidophenol and methyl methacrylate are dissolved in an organic solvent and copolymerized under the action of an initiator to obtain a copolymer solution; the copolymer solution is dropped into a dispersion to solidify into spheres, and after purification, acid activation and drying, a terpolymer chelating resin is obtained; S2: The vanadium-containing acidic leachate is passed into a fixed-bed ion exchange column filled with the ternary copolymer chelating resin for dynamic adsorption. The operating flow rate is controlled until the vanadium concentration in the effluent reaches the breakthrough point, thus completing the adsorption process. S3: Use an alkaline desorbent to dynamically elute the saturated resin bed and collect the vanadium-rich desorbent. S4: Adjust the pH of the desorption solution to acidic, heat and hydrolyze to generate metavanadate precipitate, and after solid-liquid separation, washing and calcination, obtain vanadium pentoxide product.

2. The vanadium pentoxide refining process according to claim 1, characterized in that, In the copolymerization reaction described in step S1, the mass ratio of N-acryloylmorpholine: 3-acrylamidophenol: methyl methacrylate is 1:(0.72-0.81):(0.27-0.35); the organic solvent is N,N-dimethylformamide; and the initiator is azobisisobutyronitrile, the amount of which is 0.5%-1.5% of the total mass of the monomers.

3. The vanadium pentoxide refining process according to claim 2, characterized in that, The copolymerization reaction in step S1 is carried out under inert gas protection, at a reaction temperature of 65-75℃, and for a reaction time of 4-6 hours; the dispersion is a polyvinyl alcohol aqueous solution, and the curing is performed by adding the copolymer solution dropwise into the polyvinyl alcohol aqueous solution under stirring at a rate of 1-3 mL / min.

4. The vanadium pentoxide refining process according to claim 1, characterized in that, The purification process in step S1 specifically involves: placing the cured resin microspheres in a Soxhlet extractor and refluxing with methanol for 20-28 hours to remove unreacted monomers and oligomers; the acid activation involves soaking the resin in a 1-2 mol / L hydrochloric acid solution for 12-24 hours.

5. The vanadium pentoxide refining process according to claim 1, characterized in that, The vanadium-containing acidic leachate in step S2 has a pH value of 0-1.5 and contains V (V) and Fe. 3+ and Al 3+ Ions; the operating flow rate of the dynamic adsorption is 2-6 BV / h, and the adsorption temperature is 20-35℃.

6. The vanadium pentoxide refining process according to claim 1, characterized in that, The alkaline desorbent in step S3 is a sodium hydroxide solution with a concentration of 0.2-0.5 mol / L; the desorption flow rate is 1-2 BV / h, and the desorption temperature is 35-50℃.

7. The vanadium pentoxide refining process according to claim 1, characterized in that, Step S4 specifically includes: adjusting the pH of the desorption solution to 1.8-2.2 with sulfuric acid, heating it to 85-95℃ and stirring for 1-3 hours; filtering after cooling, washing the precipitate with deionized water, and then calcining it in a muffle furnace at 480-520℃ for 1-2 hours.

8. The vanadium pentoxide refining process according to claim 4, characterized in that, The drying process in step S1 specifically involves placing the acid-activated resin microspheres in a vacuum drying oven, controlling the vacuum level at 0.06-0.08 MPa, the drying temperature at 60-80℃, and the drying time at 4-8 hours. After drying, the particle size of the resin microspheres is 0.3-0.8 mm.

9. The vanadium pentoxide refining process according to claim 5, characterized in that, In step S2, the fixed-bed ion exchange column has a height-to-diameter ratio of 3-8:

1. During the adsorption process, the vanadium concentration in the effluent is measured every 1-2 hours. The breakthrough point is when the vanadium concentration in the effluent reaches 0.1-0.3 g / L.

10. The vanadium pentoxide refining process according to claim 7, characterized in that, The solid-liquid separation in step S4 is performed by vacuum filtration with a filtration pressure of 0.03-0.05 MPa and a filter membrane pore size of 0.22-0.45 μm. The washing process is stopped when the pH of the washing solution reaches 6.5-7.5.

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