Method for extracting vanadyl sulfate crystal from high-acid system

Abstract

The invention relates to the field of preparation of vanadyl sulfate crystals, in particular to a method for extracting vanadyl sulfate crystals from a high-acid system, which comprises the following steps: concentrating a solution containing vanadium ions to obtain a concentrated solution; the concentrated solution is loaded to a chromatographic column, adsorption tail liquid is obtained, and the stationary phase of the chromatographic column is anion exchange resin; crystals in the adsorption tail liquid are separated out, and vanadyl sulfate crystals are obtained. According to the method, the solution containing the vanadium ions in the high-acid system is treated through the anion exchange resin, sulfate radicals in the solution containing the vanadium ions are adsorbed through the anion exchange resin, meanwhile, hydroxyl radicals are released, the acidity of the solution containing the vanadium ions can be reduced, the viscosity of the solution can be reduced, subsequent nucleation and precipitation of vanadyl sulfate crystals are facilitated, and the purity of the solution containing the vanadium ions is improved. The method provided by the invention is simple and convenient to operate, the efficiency of extracting the vanadyl sulfate crystal is high, and the vanadyl sulfate crystal extracted by the method provided by the invention is obvious in particle, non-sticky and good in resolubility.

Description

Technical Field

[0001] The present invention relates to the field of preparation of vanadyl sulfate crystals, and particularly to a method for extracting vanadyl sulfate crystals from a high-acid system. Background Art

[0002] Vanadyl sulfate (chemical formula VOSO4) is an important vanadium-based compound. Due to its unique redox properties and the high catalytic activity of vanadium elements, it has a wide range of applications in fields such as all-vanadium redox flow batteries, catalysts, and pharmaceuticals and nutritional supplements. Especially in the field of long-duration new energy storage, the demand for vanadyl sulfate electrolyte exceeds the supply. However, vanadyl sulfate in a high-acid system has high acidity and high system viscosity, resulting in difficult crystallization, hard-to-control crystal purity and morphology, and great difficulty in reprocessing the formed vanadyl sulfate crystals into vanadium-containing electrolyte.

[0003] The prior art discloses a method for preparing solid vanadyl sulfate. The purification technology of solvent extraction is used to purify the tetravalent vanadium solution, which improves the purity of vanadyl sulfate. However, the prepared vanadyl sulfate crystals have high re-dissolution difficulty and long re-dissolution time. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present invention is to overcome the defects of high re-dissolution difficulty and long re-dissolution time of vanadyl sulfate crystals in the prior art, so as to provide a method for extracting vanadyl sulfate crystals from a high-acid system.

[0005] The present invention provides a method for extracting vanadyl sulfate crystals from a high-acid system, which includes the following steps: loading a vanadium ion-containing solution onto a chromatography column to obtain an adsorption tail liquid, wherein the stationary phase of the chromatography column is an anion exchange resin, and the vanadium ion concentration in the vanadium ion-containing solution is greater than or equal to 150 g / L; and precipitating crystals from the adsorption tail liquid to obtain vanadyl sulfate crystals.

[0006] In some embodiments, before loading the vanadium ion-containing solution onto the chromatography column, the anion exchange resin is treated with an inorganic reagent containing hydroxide.

[0007] In some embodiments, the vanadium ion concentration in the vanadium ion-containing solution is 150 g / L - 400 g / L, preferably 150 - 310 g / L.

[0008] In some embodiments, the anion exchange resin is treated with an inorganic reagent containing hydroxide, and then the anion exchange resin is treated with deionized water until the pH value of the solution at the outlet of the chromatography column is less than or equal to 10; preferably, the pH value of the solution at the outlet of the chromatography column is 7 - 10, more preferably 9 - 10.

[0009] In some embodiments, the inorganic reagent containing hydroxide includes at least one of an aqueous sodium hydroxide solution, ammonia water, and an aqueous lithium hydroxide solution.

[0010] In some of these embodiments, the vanadium ion-containing solution is obtained by subjecting the leaching solution of sodium-roasted vanadium slag to extraction and then to stripping.

[0011] In some of these embodiments, the anion exchange resin includes a strongly basic macroporous styrene-based anion exchange resin.

[0012] Preferably, the step of extracting the leaching solution of sodium-roasted vanadium slag includes immersing the sodium-roasted vanadium slag in a first acid solution to obtain a first mixture, adjusting the pH value, then adding a reducing agent to the first mixture to obtain a second mixture, and then adding an extractant to the second mixture to obtain a vanadium-containing extract.

[0013] Preferably, the stripping step includes mixing the vanadium-containing extract with a second acid solution to obtain a vanadium ion-containing solution.

[0014] In some of these embodiments, the aspect ratio of the resin is (0.5 to 10):1.

[0015] In some of these embodiments, during sample loading, the column temperature is 80 - 90 °C.

[0016] In some of these embodiments, the reducing agent includes at least one of sulfur dioxide, sodium sulfite, sodium metabisulfite, hydrogen sulfide, or potassium iodide.

[0017] In some of these embodiments, the extractant includes at least one of bis(2-ethylhexyl) phosphoric acid and 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester.

[0018] In some of these embodiments, the first acid solution and the second acid solution are independently selected from at least one of aqueous hydrochloric acid solution, aqueous sulfuric acid solution, and aqueous nitric acid solution. The concentration of the acid substance in the first acid solution is 5 - 10 wt%, and the concentration of the acid substance in the second acid solution is 4 - 6 mol / L.

[0019] In some of these embodiments, when the sodium-roasted vanadium slag is immersed in the first acid solution to obtain a first mixture, the adjusted pH value is 0 - 2.

[0020] It should be noted that before the vanadium ion-containing solution is loaded onto the resin, the pH value of the vanadium ion-containing solution is much less than 0. When the vanadium ion-containing solution passes through the resin, after being treated by the resin, the pH value of the solution at the outlet of the chromatography column rises to 2 - 4. However, as more and more feed liquid is added, the pH value of the solution at the outlet of the chromatography column will gradually decrease. When the pH value of the solution at the outlet of the chromatography column decreases to 0, the adsorption is stopped to avoid too high an acid value.

[0021] In some of these embodiments, the ratio of the vanadium slag to the first acid solution is 1:4 - 8, with the unit being g:mL.

[0022] In some of these embodiments, the ratio of the reducing agent to the first mixed solution is 1:10 - 50, with the unit being g:mL.

[0023] In some of these embodiments, the ratio of the extractant to the second mixed solution is 1:1 - 3, with the unit being g:mL.

[0024] In some of these embodiments, the volume ratio of the vanadium-containing extraction solution to the second acid solution is 5 - 15:1.

[0025] In some of these embodiments, the solution containing vanadium ions is obtained by subjecting the leaching solution of sodium-roasted vanadium slag to extraction, back-extraction, and concentration. The concentration is carried out by negative pressure concentration. The vacuum degree of the negative pressure concentration method is -0.1 to -0.08 MPa, the temperature is 60 - 90 °C, and the rotation speed is 20 - 60 rpm.

[0026] In some of these embodiments, the flow rate of the solution containing vanadium ions when loading onto the chromatography column is 0.5 - 3 BV / h.

[0027] In some of these embodiments, the crystallization method of cooling is used to precipitate crystals from the adsorption tail liquid. The specific steps are as follows: First, the adsorption tail liquid is stirred at a rotation speed of 30 - 120 rpm for 1 - 3 h in a water bath at a temperature of 80 - 90 °C, and then the temperature of the adsorption tail liquid is reduced to 45 - 55 °C at a cooling rate of 1 - 5 °C / h.

[0028] In some of these embodiments, the step of precipitating crystals from the adsorption tail liquid further includes solid-liquid separation of the solution containing vanadyl sulfate crystals.

[0029] In some of these embodiments, the solid-liquid separation includes at least one of filtration, the seeding method, or the solvent evaporation method. During filtration, the temperature of the solution containing vanadium ions is 45 - 55 °C.

[0030] In some of these embodiments, the filtrate obtained after the solid-liquid separation is recycled as the solution containing vanadium ions.

[0031] The technical solution of the present invention has the following advantages:

[0032] A method for extracting vanadyl sulfate crystals from a high-acid system provided by the present invention includes the following steps: loading a vanadium ion-containing solution onto a chromatography column to obtain an adsorption tail solution, where the stationary phase of the chromatography column is an anion exchange resin, and the concentration of vanadium ions in the vanadium ion-containing solution is greater than or equal to 150 g / L; precipitating crystals from the adsorption tail solution to obtain vanadyl sulfate crystals. By treating the vanadium ion-containing solution in a high-acid system with an anion exchange resin, the anion exchange resin adsorbs sulfate radicals in the vanadium ion-containing solution and releases hydroxide ions at the same time, which can not only reduce the acidity of the vanadium ion-containing solution, facilitating the nucleation and precipitation of subsequent vanadyl sulfate crystals. The method provided by the present invention is simple to operate, has a high efficiency in extracting vanadyl sulfate crystals, and the vanadyl sulfate crystals extracted by the method provided by the present invention have obvious particles, do not stick, and have good redissolvability.

[0033] A method for extracting vanadyl sulfate crystals from a high-acid system provided by the present invention uses a hydroxide-containing reagent to treat the anion exchange resin, and then uses deionized water to treat the anion exchange resin until the pH value of the solution at the outlet of the chromatography column is less than or equal to 10. By treating the anion exchange resin with a hydroxide-containing reagent and maintaining the pH value of the resin less than or equal to 10, the sulfate radical ions in the vanadium ion-containing solution can be significantly reduced, thereby reducing the viscosity of the vanadium ion-containing solution and improving the redissolvability of vanadyl sulfate crystals. Description of the Drawings

[0034] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0035] Figure 1 is a physical diagram of the vanadyl sulfate crystals extracted in Example 1 of the present invention;

[0036] Figure 2 is a physical diagram of the vanadyl sulfate crystals extracted in Example 1 of the present invention after drying treatment. Detailed Embodiments

[0037] The following embodiments are provided to better further understand the present invention. They are not limited to the best embodiments, and do not limit the content and protection scope of the present invention. Any product obtained by anyone under the inspiration of the present invention or by combining the features of the present invention with other prior art features that is the same or similar to the present invention falls within the protection scope of the present invention.

[0038] If no specific experimental steps or conditions are specified in the examples, the conventional experimental steps or conditions described in the literature in the field can be used. If no manufacturer is specified for the reagents or instruments used, they are all conventional reagent products that can be obtained commercially.

[0039] The styrene-based strongly alkaline macroporous anion exchange resin in the embodiments of the present invention is produced by Xi'an Lanxiao Technology New Materials Co., Ltd.

[0040] The relative atomic mass of vanadium (V) is 50.94 g / mol.

[0041] Example 1

[0042] This embodiment provides a method for extracting vanadyl sulfate crystals from a high acid system, and the specific steps and methods are as follows:

[0043] (1) The sodium-calcined vanadium slag is immersed in an 8wt% sulfuric acid aqueous solution according to the ratio of vanadium slag to the first acid solution of 1:6, in g:mL, to obtain a first mixed solution, and the pH value of the first mixed solution is adjusted to 1, sulfur dioxide is added to the first mixed solution according to the ratio of reducing agent to the first mixed solution of 1:25, in g:mL, to fully react to obtain a second mixed solution, and an extractant is added to the second mixed solution according to the ratio of extractant to the second mixed solution of 1:2, the extractant is di(2-ethylhexyl)phosphoric acid (P204), the clarification is carried out, and the lower oil phase is taken as the vanadium-containing extract;

[0044] According to the mass and volume ratio of vanadium-containing extractant to sulfuric acid aqueous solution of 10:1, the vanadium-containing extract and sulfuric acid aqueous solution (the concentration of sulfuric acid aqueous solution is 5 mol / L) are mixed, and after stratification, the lower layer solution is taken to obtain a solution containing vanadium ions.

[0045] (2) Place 5 L of vanadyl sulfate sample solution in a rotary evaporator. The vanadium ion concentration in the sample solution is 3 mol / L. Set the rotary evaporation parameters as follows: vacuum degree of -0.08 MPa, temperature of 85°C, rotation speed of 60 rpm, and negative pressure evaporation until the volume of the concentrated solution is 2.5 L. The vanadium ion concentration in the concentrated solution is 6 mol / L.

[0046] (3) Weigh 100 mL of styrene-based strongly alkaline macroporous anion exchange resin and place it in a chromatography column (the height-to-diameter ratio of the chromatography column is 5:1). Rinse the chromatography column with 1 mol / L sodium hydroxide solution at a flow rate of 2 BV / h, and then rinse the chromatography column with deionized water at a flow rate of 2 BV / h until the pH value of the liquid at the outlet of the chromatography column is 10.

[0047] (4) loading the concentrated solution in step (1) onto the chromatography column (column temperature 85° C.) treated in step (2) at a rate of 2 BV / h. During the loading of the concentrated solution onto the chromatography column, the pH value of the adsorption tail liquid was monitored in real time. When the pH value of the adsorption tail liquid reached 0, the loading was stopped and the adsorption tail liquid was collected.

[0048] Deionized water was used for washing at a washing flow rate of 2 BV / h, and then 4 BV of 10 wt % sulfuric acid aqueous solution was used to wash the chromatography column.

[0049] (5) The adsorption tail liquid obtained in step (3) was stirred at 60 rpm for 1 h in a water bath at 85 ° C, and then cooled at a cooling rate of 5 ° C / h until the temperature dropped to 50 ° C to obtain a solution containing vanadyl sulfate crystals, the solid-liquid ratio of the solution was 1.3:1, and the solution containing vanadyl sulfate crystals was filtered using a sand core funnel to obtain vanadyl sulfate crystals and a filtrate. The actual picture of the vanadyl sulfate crystals is shown in Figure 1 , wherein the concentration of vanadium ions in the filtrate is 0.9 mol / L, and the filtrate is recycled to the vanadyl sulfate sample solution in step (1). The vanadyl sulfate crystals can be dried to obtain dry crystals. See the actual crystal picture. Figure 2 .

[0050] Example 2

[0051] This embodiment provides a method for extracting vanadyl sulfate crystals from a high acid system, and the specific steps and methods are as follows:

[0052] (1) The sodium-treated calcined vanadium slag is immersed in an 8wt% sulfuric acid aqueous solution according to a ratio of vanadium slag to the first acid solution of 1:6, in g:mL, to obtain a first mixed solution, and the pH value of the first mixed solution is adjusted to 2, sulfur dioxide is added to the first mixed solution according to a ratio of the reducing agent to the first mixed solution of 1:25, in g:mL, to fully react to obtain a second mixed solution, an extractant is added to the second mixed solution according to a ratio of the extractant to the second mixed solution of 1:2, the extractant is di(2-ethylhexyl)phosphoric acid (P204), the clarification is carried out, and the lower oil phase is taken as the vanadium-containing extract;

[0053] According to the mass and volume ratio of vanadium-containing extractant to sulfuric acid aqueous solution of 5:1, the vanadium-containing extract and sulfuric acid aqueous solution are mixed, and after stratification, the lower layer solution is taken to obtain a solution containing vanadium ions.

[0054] (2) Place 5 L of vanadyl sulfate sample solution in a rotary evaporator. The vanadium ion concentration in the sample solution is 3.2 mol / L. Set the rotary evaporation parameters as follows: vacuum degree of -0.1 MPa, temperature of 80°C, rotation speed of 50 rpm, and negative pressure evaporation until the volume of the concentrated solution is 3 L. The vanadium ion concentration in the concentrated solution is 5.33 mol / L.

[0055] (3) Weigh 100 mL of strongly basic macroporous styrene-based anion exchange resin, place it in a chromatography column, and wash the chromatography column with 1 mol / L sodium hydroxide solution at a flow rate of 2 BV / h according to a ratio of 2 BV, and then wash the chromatography column with deionized water at a flow rate of 2 BV / h until the pH value of the liquid at the outlet of the chromatography column is 10.

[0056] (4) Load the concentrated solution in step (1) onto the chromatography column processed in step (2) at a rate of 2 BV / h. During the process of loading the concentrated solution onto the chromatography column, monitor the pH value of the adsorption tail liquid in real time. When the pH value of the adsorption tail liquid reaches 0, stop loading and collect the adsorption tail liquid;

[0057] Wash with deionized water at a washing flow rate of 2 BV / h, and then wash the chromatography column with 4 BV sulfuric acid.

[0058] (5) Stir the adsorption tail liquid obtained in step (3) in a water bath at 80 °C at a rotation speed of 70 rpm for 1 h, and then cool it at a cooling rate of 3 °C / h until the temperature drops to 45 °C to obtain a solution containing vanadyl sulfate crystals. The solid-liquid ratio in the solution is 1:1. Filter the solution containing vanadyl sulfate crystals using a sintered glass funnel to obtain vanadyl sulfate crystals and filtrate. Among them, the concentration of vanadium ions in the filtrate is 1.02 mol / L. The filtrate is recycled to the vanadyl sulfate sample solution in step (1), and the vanadyl sulfate crystals can be dried to obtain dry crystals.

[0059] Example 3

[0060] This example provides a method for extracting vanadyl sulfate crystals from a high-acid system. The specific steps and methods are the same as those in Example 1, except that the pH value of the liquid at the outlet of the chromatography column in step (3) is 9.

[0061] Example 4

[0062] This example provides a method for extracting vanadyl sulfate crystals from a high-acid system. The specific steps and methods are the same as those in Example 1, except that step (1) is not included, and the leaching solution of sodium-roasted vanadium slag is used as the vanadyl sulfate sample solution in step (2). The leaching solution of sodium-roasted vanadium slag is obtained by immersing sodium-roasted vanadium slag in an 8 wt% sulfuric acid aqueous solution to form a leaching solution.

[0063] Example 5

[0064] This example provides a method for extracting vanadyl sulfate crystals from a high-acid system. The specific steps and methods are the same as those in Example 1, except that the concentration of vanadium ions in the concentrated solution in step (2) is 150 g / L.

[0065] The concentration of vanadium ions in the filtrate after filtration in step (5) is 40 g / L.

[0066] Example 6

[0067] This embodiment provides a method for extracting vanadyl sulfate crystals from a high acid system. The specific steps and methods are the same as those in Example 1, except that the vanadium ion concentration in the concentrated solution in step (2) is 400 g / L.

[0068] After filtering in step (5), the vanadium ion concentration in the filtrate is 50 g / L.

[0069] Example 7

[0070] This embodiment provides a method for extracting vanadyl sulfate crystals from a high acid system. The specific steps and methods are the same as those in Example 1, except that the vanadium ion concentration in the concentrated solution in step (2) is 300 g / L.

[0071] After filtering in step (5), the vanadium ion concentration in the filtrate is 45 g / L.

[0072] Example 8

[0073] (1) According to the ratio of vanadium slag to the first acid solution of 1:4, the unit is g:mL, the sodium-treated calcined vanadium slag is immersed in a 10wt% hydrochloric acid aqueous solution to obtain a first mixed solution, and the pH value of the first mixed solution is adjusted to 2, according to the ratio of reducing agent to the first mixed solution of 1:50, the unit is g:mL, sodium sulfite is added to the first mixed solution for sufficient reaction to obtain a second mixed solution, according to the ratio of extractant to the second mixed solution of 1:1, extractant is added to the second mixed solution, the extractant is di(2-ethylhexyl)phosphoric acid (P204), the clarification is carried out, and the lower oil phase is taken as the vanadium-containing extract;

[0074] According to the mass and volume ratio of vanadium-containing extractant to sulfuric acid aqueous solution of 15:1, the vanadium-containing extract and nitric acid aqueous solution (the concentration of nitric acid aqueous solution is 4 mol / L) are mixed, and after stratification, the lower layer solution is taken to obtain a solution containing vanadium ions.

[0075] (2) Place 5 L of vanadyl sulfate sample solution in a rotary evaporator, the vanadium ion concentration in the sample solution is 100 g / L, set the rotary evaporation parameters: vacuum degree is -0.1 MPa, temperature is 60°C, speed is 50 rpm, and negative pressure evaporation is performed until the volume of the concentrated solution is 2.5 L and the vanadium ion concentration in the concentrated solution is 200 g / L.

[0076] (3) Weigh 100 mL of styrene-based strongly alkaline macroporous anion exchange resin and place it in a chromatography column (the height-to-diameter ratio of the chromatography column is 5:1). Rinse the chromatography column with 1 mol / L sodium hydroxide solution at a flow rate of 2 BV / h, and then rinse the chromatography column with deionized water at a flow rate of 2 BV / h until the pH value of the liquid at the outlet of the chromatography column is 10.

[0077] (4) loading the concentrated solution in step (1) onto the chromatography column (column temperature 85° C.) treated in step (2) at a rate of 2 BV / h. During the loading of the concentrated solution onto the chromatography column, the pH value of the adsorption tail liquid was monitored in real time. When the pH value of the adsorption tail liquid reached above 0, the loading was stopped and the adsorption tail liquid was collected.

[0078] Deionized water was used for washing at a flow rate of 2 BV / h, and 4 BV of 10 wt % sulfuric acid aqueous solution was used to wash the column.

[0079] (5) The adsorption tail liquid obtained in step (3) is stirred at 60 rpm for 3 h in a water bath at 80 ° C, and then cooled at a cooling rate of 1 ° C / h until the temperature drops to 45 ° C to obtain a solution containing vanadium sulfate crystals, wherein the solid-liquid ratio in the solution is 1.3:1, and the solution containing vanadium sulfate crystals is filtered using a sand core funnel to obtain vanadium sulfate crystals and a filtrate, wherein the concentration of vanadium ions in the filtrate is 0.9 mol / L, and the filtrate is reused in the vanadium sulfate sample solution in step (1), and the vanadium sulfate crystals can be dried to obtain dry crystals.

[0080] Example 9

[0081] (1) The sodium-treated calcined vanadium slag is immersed in a 5wt% sulfuric acid aqueous solution at a ratio of 1:8 to the first acid solution, and the pH value of the first mixed solution is adjusted to 0. Sulfur dioxide is added to the first mixed solution at a ratio of 1:10 to the first mixed solution, and the reaction is completed to obtain a second mixed solution. An extractant is added to the second mixed solution at a ratio of 1:3 to the second mixed solution, and the extractant is 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester. The mixture is clarified and separated into layers, and the lower oil phase is taken as the vanadium-containing extract;

[0082] According to the mass and volume ratio of vanadium-containing extractant to sulfuric acid aqueous solution of 10:1, the vanadium-containing extract and sulfuric acid aqueous solution (the concentration of sulfuric acid aqueous solution is 5 mol / L) are mixed, and after stratification, the lower layer solution is taken to obtain a solution containing vanadium ions.

[0083] (2) Place 5 L of vanadyl sulfate sample solution in a rotary evaporator, the vanadium ion concentration in the sample solution is 150 g / L, set the rotary evaporation parameters: vacuum degree is -0.08 MPa, temperature is 90°C, speed is 20 rpm, and negative pressure evaporation is performed until the volume of the concentrated solution is 2.5 L and the vanadium ion concentration in the concentrated solution is 300 g / L.

[0084] (3) Weigh 100 mL of strongly basic macroporous styrene-based anion exchange resin and place it in a chromatography column (the height-to-diameter ratio of the chromatography column is 10:1). Flush the chromatography column with 1 mol / L sodium hydroxide solution at a flow rate of 2 BV / h according to the ratio of 2 BV, and then flush the chromatography column with deionized water at a flow rate of 2 BV / h until the pH value of the liquid at the outlet of the chromatography column is 10.

[0085] (4) Load the concentrated solution in step (1) onto the chromatography column (column temperature 85 °C) treated in step (2) at a rate of 2 BV / h. During the process of loading the concentrated solution onto the chromatography column, monitor the pH value of the adsorption tail liquid in real time. When the pH value of the adsorption tail liquid reaches 0, stop loading and collect the adsorption tail liquid;

[0086] Wash with deionized water at a washing flow rate of 2 BV / h, and then wash the chromatography column with 4 BV of 10 wt% sulfuric acid aqueous solution.

[0087] (5) Stir the adsorption tail liquid obtained in step (3) at a speed of 60 rpm for 3 h under the water bath condition of 80 °C, and then cool it at a cooling rate of 1 °C / h until the temperature drops to 45 °C to obtain a solution containing vanadyl sulfate crystals. The solid-liquid ratio in the solution is 1.3:1. Filter the solution containing vanadyl sulfate crystals using a sintered glass funnel to obtain vanadyl sulfate crystals and filtrate. Among them, the concentration of vanadium ions in the filtrate is 0.9 mol / L. The filtrate is recycled to the vanadyl sulfate sample solution in step (1), and the vanadyl sulfate crystals can be dried to obtain dry crystals.

[0088] Comparative Example 1

[0089] This comparative example provides a method for extracting vanadyl sulfate crystals from a high-acid system. The specific steps and methods are the same as those in Example 1, except that steps (2)-(4) are not included. That is, the vanadium ion-containing solution obtained in step (1) is stirred at a speed of 60 rpm for 1 h under the water bath condition of 85 °C, and then cooled at a cooling rate of 5 °C / h until the temperature drops to 50 °C to obtain a solution containing vanadyl sulfate crystals.

[0090] However, due to the too high viscosity of the solution containing vanadyl sulfate crystals, it is impossible to filter. After the solution containing vanadyl sulfate crystals is cooled to room temperature, the mixture will form a block and it is impossible to separate and obtain vanadyl sulfate crystals.

[0091] Comparative Example 2

[0092] This comparative example provides a method for extracting vanadyl sulfate crystals from a high-acid system. The specific steps and methods are the same as those in Example 1, except that the vanadium ion concentration in the concentrated solution in step (2) is 140 g / L.

[0093] Comparative Example 3

[0094] This comparative example provides a method for extracting vanadyl sulfate crystals from a high-acid system. The specific steps and methods are the same as those in Example 1, except that steps (3)-(4) are not included. That is, the sample solution after concentration in step (2) is adjusted from negative-pressure concentration to atmospheric-pressure concentration for the crystallization of vanadyl sulfate. The specific steps are as follows:

[0095] Place 5 L of the concentrated sample solution in a rotary evaporator. The vanadium ion concentration in the sample solution is 6 mol / L. Set the rotary evaporation parameters: at atmospheric pressure, the temperature is 85 °C, and the rotation speed is 60 rpm. When the volume of the concentrated solution evaporates to 2.5 L, the feed liquid forms large chunks and cannot be filtered.

[0096] Comparative Example 4

[0097] This comparative example provides a method for extracting vanadyl sulfate crystals from a high-acid system. The specific steps and methods are the same as those in Example 1, except that steps (3)-(4) are not included. That is, the sample solution after concentration in step (2) is used to crystallize vanadyl sulfate by the following steps. The specific crystallization steps are as follows:

[0098] Place 5 L of the concentrated sample solution in a rotary evaporator. The vanadium ion concentration in the sample solution is 6 mol / L. Set the parameters: at atmospheric pressure, use an electric heating mantle to heat the temperature to 120 °C, and the rotation speed is 60 rpm. When the volume of the concentrated solution evaporates to 2 L, stop heating and cool down to 85 °C. The feed liquid shows a caking phenomenon.

[0099] Experimental Example

[0100] Detect the particle size range, re-solubility, and viscosity of the vanadyl sulfate crystals formed in Examples 1-9 and Comparative Examples 1-3. The results are shown in Table 1.

[0101] Among them, the detection of the particle size range is determined by laser particle size analysis method (Mastersizer 3000+Pro)

[0102] Method for detecting re-solubility: Take 10 g of vanadyl sulfate crystals. At 25 °C, put the vanadyl sulfate crystals into 100 mL of pure water. Record the time from when the vanadyl sulfate crystals are put into pure water to when the crystals dissolve as the re-solubility index. Stir appropriately when putting the vanadyl sulfate crystals into pure water, and no stirring is required during the dissolution process.

[0103] Test method for the content of sulfate ions on the surface of vanadyl sulfate crystals: Take a certain amount of vanadyl sulfate crystals, quickly wash the surface of the vanadyl sulfate crystals with absolute ethanol, collect the washing solution, and pour the washing solution into a solution containing barium chloride to cause the sulfate ions in the washing solution to react with barium ions to form barium sulfate precipitate. After filtering, washing, drying, and roasting the precipitate, the number of moles of barium sulfate obtained is the number of moles of sulfate radicals attached to the crystal surface. The content of sulfate ions on the vanadyl sulfate crystal % = (number of moles of sulfate radicals) / (number of moles of vanadyl sulfate crystals) × 100%;

[0104] Content of free water on the surface of vanadyl sulfate crystals: Dry the vanadyl sulfate crystals at 80 °C for 10 h and weigh them. The content of free water on the vanadyl sulfate crystals % = (weight of vanadyl sulfate crystals before drying - weight of vanadyl sulfate crystals after drying) / (weight of vanadyl sulfate crystals before drying) × 100%.

[0105] Table 1 Properties of vanadyl sulfate crystals

[0106]

[0107]

[0108] Since crystals cannot be produced in Comparative Examples 1-4, it is impossible to detect the crystal particle size, re-solubility, and viscosity of Comparative Examples 1-4. However, according to the data in Table 1, it can be seen that the particle size of the vanadyl sulfate crystals obtained by the method for extracting vanadyl sulfate crystals from a high-acid system provided by the present invention is between 70 and 100 μm, and can be fully dissolved within 4 min, improving the re-solubility of the vanadyl sulfate crystals. At the same time, the surface sulfate content of the vanadyl sulfate crystals extracted in the examples of the present invention is 14-26%, and the free water content is 18-22%, which proves that the extraction method provided by the present invention can significantly reduce the surface viscosity of the vanadyl sulfate crystals.

[0109] Obviously, the above embodiments are merely examples for clear illustration and are not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation manners here. And the obvious changes or modifications derived therefrom are still within the protection scope of the present invention.

Claims

1. A method for extracting vanadyl sulfate crystals from a high acid system, characterized in that: The following steps are included: Loading a vanadium ion-containing solution onto a chromatography column to obtain an adsorption tail liquid, wherein the stationary phase of the chromatography column is an anion exchange resin, and the vanadium ion concentration in the vanadium ion-containing solution is greater than or equal to 150 g / L; The crystals in the adsorption tail liquid are precipitated to obtain vanadyl sulfate crystals.

2. The method for extracting vanadyl sulfate crystals from a high acid system according to claim 1, characterized in that: Before loading the vanadium ion-containing solution onto the chromatography column, treating the anion exchange resin with an inorganic reagent containing hydroxide; and / or, The vanadium ion concentration in the vanadium ion-containing solution is 150 g / L-400 g / L, preferably 150-310 g / L.

3. The method for extracting vanadyl sulfate crystals from a high acid system according to claim 1, characterized in that: Treating the anion exchange resin with an inorganic reagent containing hydroxide, and then treating the anion exchange resin with deionized water until the pH value of the solution at the outlet of the chromatography column is less than or equal to 10; and / or, The inorganic reagent containing hydroxide includes at least one of sodium hydroxide aqueous solution, ammonia water, and lithium hydroxide aqueous solution.

4. The method for extracting vanadyl sulfate crystals from a high acid system according to claim 1, characterized in that: The vanadium ion-containing solution comprises a sodium-roasted vanadium slag leaching solution obtained by extraction and stripping; and / or, The anion exchange resin comprises a styrene-based strongly basic macroporous anion exchange resin; and / or, The height-to-diameter ratio of the resin is (0.5-10):

1.

5. The method for extracting vanadyl sulfate crystals from a high acid system according to claim 4, characterized in that: The step of extracting the leaching solution of the sodium-roasted vanadium slag comprises immersing the sodium-roasted vanadium slag into a first acid solution to obtain a first mixed solution, adjusting the pH value, adding a reducing agent to the first mixed solution to obtain a second mixed solution, and then adding an extractant to the second mixed solution to obtain a vanadium-containing extract; and / or, The stripping step includes mixing the vanadium-containing extract with a second acid solution to obtain a solution containing vanadium ions; When loading the sample, the column temperature was 80-90°C.

6. The method for extracting vanadyl sulfate crystals from a high acid system according to claim 5, characterized in that: The reducing agent comprises at least one of sulfur dioxide, sodium sulfite, sodium pyrosulfite, hydrogen sulfide or potassium iodide; and / or, The extractant comprises at least one of di(2-ethylhexyl)phosphoric acid and 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester; and / or, The first acid solution and the second acid solution are independently selected from at least one of a hydrochloric acid solution, a sulfuric acid solution, and a nitric acid solution, the concentration of the acid substance in the first acid solution is 5-10 wt %, and the concentration of the acid substance in the second acid solution is 4-6 mol / L; and / or, Immersing the sodium-roasted vanadium slag into a first acid solution to obtain a first mixed solution, and adjusting the pH value to 0-2; and / or, The ratio of the vanadium slag to the first acid solution is 1:4-8, in g:mL; and / or, The ratio of the reducing agent to the first mixed solution is 1:10-50, in g:mL; and / or, The ratio of the extractant to the second mixed solution is 1:1-3, in g:mL; and / or, The volume ratio of the vanadium-containing extract to the second acid solution is 5-15:

1.

7. The method for extracting vanadyl sulfate crystals from a high acid system according to claim 6, characterized in that: The vanadium ion-containing solution is obtained by extracting, stripping and concentrating the sodium-roasted vanadium slag leaching solution, wherein the concentration adopts a negative pressure concentration method, the vacuum degree of the negative pressure concentration method is -0.1 to -0.08 MPa, the temperature is 60-90° C., and the rotation speed is 20-60 rpm; and / or, The flow rate of loading the solution containing vanadium ions onto the chromatography column is 0.5-3 BV / h.

8. The method for extracting vanadyl sulfate crystals from a high acid system according to claim 1, characterized in that: The crystals in the adsorption tail liquid are precipitated by the cooling crystallization method. The specific steps are: first, the adsorption tail liquid is stirred at a water bath temperature of 80-90°C at a speed of 30-120rpm for 1-3h, and then the temperature of the adsorption tail liquid is reduced to 45-55°C at a cooling rate of 1-5°C / h.

9. The method for extracting vanadyl sulfate crystals from a high acid system according to claim 8, characterized in that: The step of separating the crystals from the adsorption tail liquid also includes solid-liquid separation of the solution containing the vanadyl sulfate crystals.

10. The method for extracting vanadyl sulfate crystals from a high acid system according to claim 9, characterized in that: The solid-liquid separation comprises at least one of filtration, seed crystal method or solvent volatilization method, During filtration, the temperature of the solution containing vanadium ions is 45-55°C; The filtrate obtained after the solid-liquid separation is recycled as a solution containing vanadium ions.

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