Method for preparing high-purity magnesium metavanadate based on synergistic conversion of industrial byproducts

Abstract

The invention belongs to the technical field of resource utilization of industrial by-products and preparation of inorganic functional materials, and discloses a method for preparing high-purity magnesium metavanadate based on synergistic conversion of the industrial by-products. Ammonium metavanadate extracted from a chlorination process titanium dioxide byproduct hydrochloric acid, a thermal power plant magnesium desulfurization byproduct magnesium sulfite and an aluminum oxide process is used as a raw material, and the method sequentially comprises the following steps: dissolving ammonium metavanadate in hot water, and acidifying with the byproduct hydrochloric acid to obtain an acidic vanadium-containing solution; adding a byproduct magnesium sulfite under heating and stirring, carrying out a deep impurity removal reaction, and carrying out solid-liquid separation to obtain a purified solution; adjusting the pH value of the purified liquid to be nearly neutral to initiate a synthetic reaction; directional crystallization is carried out by adopting programmed cooling and combining seed crystal induction; and separating, washing and drying to obtain the high-purity magnesium metavanadate. According to the method, synergistic high-value utilization of three industrial byproducts is achieved, the process is simple, the cost is low, the method is environmentally friendly, the purity of the obtained product is larger than or equal to 99.2%, the crystal form is regular, and the method is suitable for catalysts or electrode materials.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of industrial by-product resource utilization and inorganic functional material preparation, and particularly relates to a method for preparing high-purity magnesium metavanadate based on industrial by-product synergic conversion. BACKGROUND

[0002] As an important vanadate functional material, magnesium metavanadate has a wide application prospect in the fields of catalysts, electrode materials, fluorescent materials and corrosion-resistant coatings. At present, the preparation method of magnesium metavanadate mostly uses pure chemical reagents as raw materials, such as magnesium oxide, magnesium carbonate and vanadium pentoxide or ammonium metavanadate for solid-phase reaction at high temperature, or is prepared by a solution coprecipitation method. For example, CN109534397A discloses a method for preparing high-purity magnesium metavanadate by using vanadate (ammonium metavanadate / ammonium polyvanadate) and magnesium carbonate as raw materials, through slurry reaction, filtration and evaporation crystallization. Although high-purity magnesium metavanadate can be prepared by the method, the method has the defects of sensitivity to conditions, high cost, potential environmental problems and industrialization challenges.

[0003] In the production process of chlorination titanium dioxide, about 0.2-0.3 tons of waste hydrochloric acid containing a small amount of metal impurities such as titanium and iron is produced per ton of titanium dioxide; magnesium sulfite produced in the desulfurization process of a thermal power plant is usually stored as solid waste and cannot be effectively utilized; and ammonium metavanadate extracted in the production process of aluminum oxide is also an intermediate product, and the high-value utilization way of the intermediate product is limited. At present, there is no report on the synergic utilization of the above three industrial by-products to prepare magnesium metavanadate. SUMMARY

[0004] The present application aims to provide a method for preparing high-purity magnesium metavanadate based on industrial by-product synergic conversion, and solve the blank and deficiency of the synergic utilization of the above three industrial by-products to prepare magnesium metavanadate.

[0005] In order to achieve the above-mentioned application purposes, the present application provides the following technical solutions: The present application provides a method for preparing high-purity magnesium metavanadate based on industrial by-product synergic conversion, comprising the following steps: The waste hydrochloric acid produced in the production process of chlorination titanium dioxide, the magnesium sulfite produced in the magnesium method desulfurization process of a thermal power plant and the ammonium metavanadate extracted in the production process of aluminum oxide are used as raw materials, and are respectively referred to as waste hydrochloric acid, waste magnesium sulfite and waste ammonium metavanadate; The waste ammonium metavanadate is dissolved in water, the waste hydrochloric acid is used to adjust the pH to 2.5-4, and an acidic vanadium-containing solution is obtained; Under stirring, the waste magnesium sulfite is added into the acidic vanadium-containing solution for impurity removal reaction, the end-point pH of the impurity removal reaction is controlled to be 5.2-6, and then maturation, solid-liquid separation are performed to obtain a purified filtrate; The purified filtrate is adjusted to pH 6.8-7.2 using an alkaline adjusting agent, then subjected to programmed cooling, magnesium metavanadate seed crystals are added to induce when the temperature is cooled to T1, and the slurry is aged at T2 after the temperature is cooled to T2, to obtain magnesium metavanadate crystal slurry; The magnesium metavanadate crystal slurry is subjected to solid-liquid separation, washing, and drying to obtain high-purity magnesium metavanadate, i.e., the preparation of high-purity magnesium metavanadate based on the synergistic conversion of industrial by-products is completed.

[0006] Preferably, the molar ratio of MgSO3 in the by-product magnesium sulfite to the total metal ion impurities in the acidic vanadium-containing solution is 1.8-2.5:1.

[0007] Preferably, the temperature of the impurity removal reaction is 75-85℃.

[0008] Preferably, the temperature of the ripening is 75-85℃, and the time of the ripening is 1.5-2h.

[0009] Preferably, the rate of the programmed cooling is 0.8-1.2℃ / min, and the starting temperature of the programmed cooling is 70-75℃.

[0010] Preferably, the T1 temperature is 40-45℃, the T2 temperature is 15-20℃, and the time of the aging is 2-3h.

[0011] Preferably, the mass of the magnesium metavanadate seed crystals is 1-1.5% of the mass of the by-product ammonium metavanadate.

[0012] Preferably, the washing is first using 10-15℃ water, and then using anhydrous ethanol or acetone; the drying temperature is 95-105℃, and the drying time is 5-7h.

[0013] According to the above technical solution, compared with the prior art, the present application has the following advantages: (1) Raw material and cost advantage: The present application first integrates three different industrial waste by-products into the same product chain, realizing the "treasure from waste". The present application has a significant advantage in raw material cost compared to Ren Jun et al. (Magnesium Metavanadate Preparation Process, Ferroalloy, 2016(6)), which uses high-purity raw materials. This advantage is derived from the use of low-value vanadium-containing waste and the resource integration effect brought by the synergistic treatment of acid and magnesium-based waste.

[0014] (2) Process flow and efficiency improvement: The present application uses the "magnesium sulfite multifunctional coupling deep impurity removal" technology to simplify the traditional multi-step impurity removal to one step, greatly shortening the process flow, reducing equipment investment and operating time, and improving production efficiency.

[0015] (3) The product quality and performance are superior: the crystal morphology and particle size of the product are effectively controlled by the "programmed cooling-seed induced directional crystallization" technology. The purity of the magnesium metavanadate product obtained by the method is stable and is greater than or equal to 99.2%, and the product is a regular short columnar crystal, the particle size distribution (D50) is concentrated in 25-45 mu m, the angle of repose is small, the flowability is good, and the subsequent processing application is easy. The product obtained by the traditional precipitation method is mostly amorphous or small irregular particles, the purity is usually only 97-98%, and the filtration performance is poor.

[0016] (4) Environmentally friendly and green manufacturing: the overall process of the method realizes closed-loop utilization of waste, and almost no new harmful waste liquid is generated (the washed ethanol can be recycled). Compared with the prior art which only processes single waste, the method has stronger synergistic utilization capacity for multiple wastes, more significant environmental benefits, and conforms to the principle of green chemistry. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiment or prior art description.

[0018] Figure 1 The figure is a process flow diagram of the method for preparing high-purity magnesium metavanadate based on industrial by-products. DETAILED DESCRIPTION

[0019] The present application provides a method for preparing high-purity magnesium metavanadate based on industrial by-products, and the flow chart is as shown in Figure 1 The method comprises the following steps: The by-product hydrochloric acid, the by-product magnesium sulfite, and the by-product ammonium metavanadate extracted in the alumina process are used as raw materials, and are respectively referred to as the by-product hydrochloric acid, the by-product magnesium sulfite, and the by-product ammonium metavanadate. The by-product ammonium metavanadate is dissolved in water, the by-product hydrochloric acid is used to adjust the pH to 2.5-4, and an acidic vanadium-containing solution is obtained. The by-product magnesium sulfite is added to the acidic vanadium-containing solution under stirring to perform a removal reaction, the end point pH of the removal reaction is controlled to be 5.2-6, then maturation and solid-liquid separation are performed, and a purified filtrate is obtained. The pH of the purified filtrate is adjusted to 6.8-7.2 by using an alkaline adjusting agent, then programmed cooling is performed, the magnesium metavanadate crystal seeds are induced when the temperature is cooled to T1, and the aging is performed at T2 after the temperature is cooled to T2, and a magnesium metavanadate crystal slurry is obtained. The magnesium metavanadate crystal slurry is subjected to solid-liquid separation, washing, and drying, and high-purity magnesium metavanadate is obtained, and the method for preparing high-purity magnesium metavanadate based on industrial by-products is completed.

[0020] In the present application, the by-product ammonium metavanadate is dissolved in water, preferably in water with a temperature of 60-80℃, further preferably 75℃, 80℃ or 85℃.

[0021] In the present application, the pH is adjusted using the by-product hydrochloric acid, preferably 2.5-4, further preferably 2.5, 3.0, 3.5 or 4.

[0022] In the present application, the purpose of preparing the acidic vanadium-containing solution is to convert the by-product ammonium metavanadate (NH4VO3) into vanadic acid (H3VO4 and its polymerized form) with higher reactivity, while utilizing the Cl - in the by-product hydrochloric acid to complex with part of the metal impurities (such as Fe 3+ ), inhibiting their premature hydrolysis, and creating favorable conditions for subsequent concentrated and deep impurity removal.

[0023] In the present application, the molar ratio of MgSO3 in the by-product magnesium sulfite to the total metal ion impurities in the acidic vanadium-containing solution is preferably 1.8-2.5:1, further preferably 1.8:1, 2:1, 2.3:1 or 2.5:1.

[0024] In the present application, the end pH of the impurity removal reaction is preferably 5.2-6, further preferably 5.2, 5.5, 5.8 or 6. If the end pH of the impurity removal reaction in the present application is too low, Al and Si will not be completely hydrolyzed; if the pH is too high (>6.5), it may lead to the premature formation of magnesium metavanadate or Mg(OH)2, which will encapsulate the impurities and affect the purity of the final product.

[0025] In the present application, the temperature of the impurity removal reaction is preferably 75-85℃, further preferably 75℃, 80℃ or 85℃.

[0026] In the present application, the temperature of the ripening is preferably 75-85℃, further preferably 75℃, 80℃ or 85℃; the time of the ripening is preferably 1.5-2h, further preferably 1.5h or 2h.

[0027] In the present application, the impurity removal reaction utilizes the unique properties of magnesium sulfite to achieve the simultaneous removal of multiple impurities in one operation unit. The mechanism is coupled (traditional impurity removal usually uses a step-by-step method, such as first adding an oxidizing agent to oxidize Fe 2+ to Fe 3+ , then adjusting the pH to precipitate, or adding a sulfidizing agent to precipitate heavy metals, with many steps): (1) Reducing-dissolving iron removal: SO3 2- , as a strong reducing agent, reduces the stable Fe 3+ in the solution to Fe 2+ with higher solubility. (2) Dissolved Fe 3+ + SO32- + H2O → 2Fe 2+ + SO4 2- + 2H + ); this makes iron still exist in the solution under the subsequent near-neutral conditions of magnesium metavanadate synthesis, rather than forming Fe(OH)3 precipitate to contaminate the product, which is fundamentally different from the traditional process using oxidation to remove iron; (2) Hydrolysis and precipitation to remove aluminum and silicon: under controlled pH (5.2-6) and temperature, Al 3+ and Si 4+ fully hydrolyze to form Al(OH)3 and H2SiO3 amorphous precipitates; the newly formed precipitates have strong adsorption capacity and can co-precipitate and adsorb trace heavy metals such as Cu 2+ , Pb 2+ , etc. (3) Precipitation to remove phosphorus: the introduced Mg 2+ reacts with PO4 3- in the solution to form extremely difficultly soluble Mg3(PO4)2 precipitate, effectively removing phosphorus impurities.

[0028] In the present application, the alkaline regulator is preferably 5-10% ammonia water in mass fraction, and further preferably 5%, 6%, 7%, 8%, 9% or 10%.

[0029] In the present application, the pH of the purified filtrate is preferably adjusted to 6.8-7.2 using an alkaline regulator, and further preferably to 6.8, 7.0 or 7.2.

[0030] In the present application, the rate of programmed cooling is preferably 0.8-1.2°C / min, and further preferably 0.8°C / min, 0.9°C / min, 1.0°C / min, 1.1°C / min or 1.2°C / min; the starting temperature of programmed cooling is preferably 70-75°C, and further preferably 70°C, 71°C, 72°C, 73°C, 74°C or 75°C.

[0031] In the present application, the T1 temperature is preferably 40-45°C, and further preferably 40°C, 41°C, 42°C, 43°C, 44°C or 45°C; the T2 temperature is preferably 15-20°C, and further preferably 15°C, 16°C, 17°C, 18°C, 19°C or 20°C; the aging time is preferably 2-3h, and further preferably 2h, 2.5h or 3h.

[0032] In the present application, the mass of the magnesium metavanadate seed crystal is preferably 1-1.5% of the mass of the by-product ammonium metavanadate, and further preferably 1%, 1.1%, 1.2%, 1.3%, 1.4% or 1.5%.

[0033] In the present application, after the addition of magnesium metavanadate seed crystal induction, the temperature is continuously lowered to T2 temperature and aged to ensure the ordered growth of solute on the surface of the seed crystal, effectively inhibit the secondary nucleation, thereby controlling the crystal morphology to be short columnar, and obtaining a concentrated particle size distribution.

[0034] In the present application, the washing is preferably first washed with 10-15℃ water, and then washed with anhydrous ethanol or acetone; the drying temperature is preferably 95-105℃, and further preferably 95℃, 100℃ or 105℃; the drying time is preferably 5-7h, and further preferably 5h, 6h or 7h.

[0035] In the present application, the preparation reaction equation of the high-purity magnesium metavanadate is: Mg 2+ + 2H3VO4→ Mg(VO3)2+ 2H + + 2H2O In the present application, the purity of the high-purity magnesium metavanadate is ≥99.2%, the crystal morphology is regular short columnar, the particle size distribution D50 is 25-45μm, and the particle size distribution span ((D90-D10) / D50) is less than 1.0; the iron (Fe) content of the high-purity magnesium metavanadate is less than 20ppm, the aluminum (Al) content is less than 25ppm, and the phosphorus (P) content is less than 15ppm.

[0036] The technical solutions in the embodiments of the present application will be described below in a clear and complete manner. Obviously, the described embodiments are only a part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0037] Embodiment 1

[0038] The present embodiment provides a method for preparing high-purity magnesium metavanadate based on synergistic conversion of industrial by-products, comprising the following steps: S1, raw material pretreatment and acidification activation of ammonium vanadate solution: 150 g (about 1.17 mol, purity about 91%) of crude ammonium metavanadate recovered from alumina red mud was weighed into a 2 L beaker, 1.2 L of 75 °C deionized water was added, and it was stirred and dissolved. Under stirring, titanium white powder by-product hydrochloric acid (concentration 18%, containing Ti 5100 mg / L, Fe 840 mg / L, Al 675 mg / L, Si 500 mg / L, Ca 1600 mg / L, Mg 720 mg / L, Na 575 mg / L, etc.) was slowly added dropwise until the solution pH stabilized at 3.2, obtaining about 1.4 L of an acidic vanadium-containing solution. The molar amount of total metal ion impurities (mainly including Fe 2520 mg / L, Al 2025 mg / L, Ca 457 mg / L, Mg 651 mg / L, Ti 1412 mg / L, Na 246 mg / L, etc.) in the acidic vanadium-containing solution was about 0.278 mol, detected by ICP-OES.

[0039] S2, magnesium sulfite multifunctional coupling deep impurity removal: the acidic vanadium-containing solution was transferred to a 2 L three-necked flask, heated to 80 °C in a water bath, and mechanically stirred at a speed of 300 rpm. 85 g (purity 82%, calculated as MgSO3, about 0.67 mol) of magnesium sulfite powder, a by-product of a thermal power plant, was accurately weighed and added in five equal batches within 1 h. The pH was monitored in real time during the addition, and the addition rate was adjusted to slow down when the pH approached 5.6, so that the pH reached 5.6 after the addition was completed. After the addition was completed, the stirring was continued at 80 °C for 1.5 h. Then, while hot, it was filtered with a Buchner funnel and the filter residue was washed with 100 mL of 80 °C hot water. The filtrate and wash were combined to obtain about 1.5 L of clear orange yellow purified solution.

[0040] S3, pH balance control: the purified solution was transferred to a 2 L programmed cooling crystallization kettle, and the initial stirring speed was set to 120 rpm. The solution pH was accurately adjusted to 7.0 by slowly titrating with 8% dilute ammonia water.

[0041] S4, programmed cooling-seed induction directional crystallization: the cooling program was set as follows: starting from 72 °C, cooling at a rate of 1.0 °C / min. When the temperature dropped to 42 °C, 2.0 g of high-purity magnesium metavanadate seed crystals were quickly added through the feeding port. The stirring speed was immediately adjusted to 70 rpm. Continue to cool to 18 °C and age at this temperature for 2.5 h to obtain magnesium metavanadate crystal slurry.

[0042] S5, separation, washing and drying of the product: the magnesium metavanadate crystal slurry was poured into a centrifuge and centrifuged. The crystals were washed with 500 mL of cold deionized water (10 °C) and 100 mL of anhydrous ethanol in sequence. The wet crystals were placed in an oven and dried at 100 °C for 6 h. After cooling, the white powder product was weighed, and a total of 185.5 g was obtained.

[0043] The product detection results of this example: ICP-OES analysis showed that the main content of the product (calculated as Mg(VO3)2) was 99.4%. The main impurity contents were: Fe <15 ppm, Al <20 ppm, Si <25 ppm, and P <10 ppm. Laser particle size analysis showed that D50=35.2 μm, and the span ((D90-D10) / D50)=0.81, indicating that the particle size distribution was concentrated. SEM observation showed regular short columnar crystals.

[0044] Example 2

[0045] This example provides a method for preparing high-purity magnesium metavanadate based on the synergistic conversion of industrial by-products, comprising the following steps: S1, raw material pretreatment and acidification and activation of ammonium vanadate solution: 120 g (about 0.92 mol, purity about 90%) of crude ammonium metavanadate recovered from alumina red mud was weighed into a 1.5 L beaker, 1.0 L of deionized water at 80°C was added, and it was stirred and dissolved. Under stirring, titanium dioxide by-product hydrochloric acid (concentration 18%, containing Ti 5100 mg / L, Fe 840 mg / L, Al 675 mg / L, Si 500 mg / L, Ca 1600 mg / L, Mg 720 mg / L, Na 575 mg / L, etc.) was slowly added dropwise until the solution pH stabilized at 2.8, obtaining an acidic vanadium-containing solution. ICP-OES detection showed that the molar amount of total metal ion impurities in the acidic vanadium-containing solution was about 0.22 mol.

[0046] S2, deep impurity removal by multifunctional coupling of magnesium sulfite: the acidic vanadium-containing solution was transferred to a 2 L three-necked flask, heated to 80°C in a water bath, and mechanically stirred at a speed of 300 rpm. 63 g (purity 80%, calculated as MgSO3, about 0.48 mol) of magnesium sulfite powder by-product from a thermal power plant was accurately weighed and added in five equal batches within 1 h. The pH was monitored in real time during the addition, and the addition rate was adjusted to slow down when the pH approached 5.6, so that the pH reached 5.7 after the addition was completed. After the addition was completed, the stirring was continued at 80°C for 2 h. Then, while hot, the filter cake was filtered with a Buchner funnel and washed with 100 mL of 80°C hot water. The filtrate and wash were combined to obtain a clear orange-yellow purified solution.

[0047] S3, pH balance control: the purified solution was transferred to a 2 L programmed cooling crystallization kettle, and the initial stirring speed was set to 120 rpm. The solution pH was accurately adjusted to 7.1 by slowly titrating with 8% dilute ammonia.

[0048] S4, Programmed cooling - seed induced directional crystallization: Set the cooling program: start from 70℃, cooling at a rate of 0.9℃ / min. When the temperature drops to 43℃, quickly add 1.5g high-purity magnesium metavanadate seed through the feeding port. Immediately adjust the stirring rate to 60rpm. Continue to cool to 16℃, and age at this temperature for 3h to obtain magnesium metavanadate crystal slurry.

[0049] S5, Separation, washing and drying of the product: Pour the magnesium metavanadate crystal slurry into a centrifuge and separate by centrifugation. Wash the crystals with 500mL of cold deionized water (10℃) and 100mL of anhydrous ethanol in turn. Place the wet crystals in an oven and dry at 100℃ for 6h. After cooling, weigh to obtain a total of 148.8g of white powder product.

[0050] Product detection results of this example: ICP-OES analysis showed that the main content of the product (calculated as Mg(VO3)2) was 99.2%. The main impurity contents were: Fe <18ppm, Al <22ppm, Si <25ppm, P <12ppm. Laser particle size analysis showed D50=29.5μm, span ((D90-D10) / D50)=0.85, indicating a concentrated particle size distribution. SEM observation showed regular short columnar crystals.

[0051] Comparative Example 1

[0052] Take equimolar analytical pure ammonium metavanadate (i.e. 1.17mol) and 0.585mol of analytical pure magnesium chloride hexahydrate (MgCl2·6H2O) as raw materials. Dissolve the ammonium metavanadate in 1.2L of deionized water at 75℃, and stir to dissolve. Slowly add analytical pure hydrochloric acid (concentration 36%-38%) under stirring to adjust the pH to 3.2 to obtain an acidic vanadium-containing solution. Heat the solution to 80℃, add 5mL of 30% hydrogen peroxide, stir for 30min, and then adjust the pH to 5.5 with dilute ammonia water to precipitate Fe(OH)3, etc., and filter. Add about 10mL of 0.5mol / L Na2S solution to the filtrate to precipitate heavy metals, and filter again. Finally, mix the purified vanadium solution with the previously prepared magnesium chloride hexahydrate solution, adjust the pH to 7.0 with ammonia water to precipitate magnesium metavanadate, and naturally cool, filter, and dry.

[0053] Product detection results of the comparative example: ICP-OES analysis showed that the main content of the product (calculated as Mg(VO3)2) was 99.5%. The main impurity contents were: Fe <10ppm, Al <15ppm, Si <18ppm, P <7ppm. Laser particle size analysis showed D50=34μm, span ((D90-D10) / D50)=0.80. The process steps of the comparative example are complicated, analytical pure raw materials are used, and additional chemicals are used, resulting in higher cost.

[0054] The above merely describes the preferred embodiments of the present application, and it should be pointed out that, for those skilled in the art, several improvements and refinements can be made without departing from the principles of the present application, and these improvements and refinements should also be considered as falling within the protection scope of the present application.

Claims

1. A method for preparing high-purity magnesium metavanadate based on the co- transformation of industrial by-products, characterized by, The method comprises the following steps: The by-product hydrochloric acid is obtained from the chlorination method of titanium dioxide, the by-product magnesium sulfite is obtained from the magnesium method of thermal power plant desulfurization, and the by-product ammonium metavanadate is obtained from the extraction of the process of aluminum oxide, which are respectively referred to as by-product hydrochloric acid, by-product magnesium sulfite and by-product ammonium metavanadate; The by-product ammonium metavanadate is dissolved in water, and the by-product hydrochloric acid is used to adjust the pH to 2.5-4 to obtain an acidic vanadium-containing solution; The by-product magnesium sulfite is added to the acidic vanadium-containing solution under stirring to perform a purification reaction, and the end point pH of the purification reaction is controlled to be 5.2-6, and then aging and solid-liquid separation are performed to obtain a purified filtrate; The pH of the purified filtrate is adjusted to 6.8-7.2 by using an alkaline adjusting agent, and then programmed cooling is performed, the magnesium metavanadate seed crystal is induced when the programmed cooling is cooled to T1 temperature, and aging is performed at T2 temperature after the programmed cooling is cooled to T2 temperature to obtain a magnesium metavanadate crystal slurry; The magnesium metavanadate crystal slurry is subjected to solid-liquid separation, washing and drying to obtain high-purity magnesium metavanadate, and the preparation of high-purity magnesium metavanadate based on industrial by-products is completed.

2. The method for preparing high-purity magnesium metavanadate through synergistic conversion based on industrial by-products according to claim 1, characterized in that, The molar ratio of MgSO3 in the by-product magnesium sulfite to the total metal ion impurities in the acidic vanadium-containing solution is 1.8-2.5:

1.

3. The method for preparing high-purity magnesium metavanadate through synergistic conversion based on industrial by-products according to claim 2, characterized in that, The temperature of the purification reaction is 75-85℃.

4. The method for preparing high-purity magnesium metavanadate through synergistic conversion based on industrial by-products according to claim 3, characterized in that, The temperature of the aging is 75-85℃, and the time of the aging is 1.5-2h.

5. The method for preparing high-purity magnesium metavanadate through synergistic conversion based on industrial by-products according to claim 4, characterized in that, The rate of the programmed cooling is 0.8-1.2℃ / min, and the starting temperature of the programmed cooling is 70-75℃.

6. The method for preparing high-purity magnesium metavanadate through synergistic conversion based on industrial by-products according to claim 5, characterized in that, The T1 temperature is 40-45℃, the T2 temperature is 15-20℃, and the time of the aging is 2-3h.

7. The method for preparing high-purity magnesium metavanadate through synergistic conversion based on industrial by-products according to claim 6, characterized in that, The mass of the magnesium metavanadate seed crystal is 1-1.5% of the mass of the by-product ammonium metavanadate.

8. The method for preparing high-purity magnesium metavanadate through synergic conversion based on industrial by-products according to claim 1, characterized in that, The washing is first washing with water at 10-15℃, and then washing with anhydrous ethanol or acetone, the drying temperature is 95-105℃, and the drying time is 5-7h.

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