Method for preparing vanadium electrolyte by using high-arsenic vanadium-containing material

Abstract

The application provides a method for preparing vanadium electrolyte by using high-arsenic vanadium-containing materials, which is characterized by three-stage synergistic deep arsenic removal and simultaneous preparation of vanadium electrolyte. Red vanadium, crude V2O5, ammonium polyvanadate and / or ammonium metavanadate with an arsenic content higher than 0.1 wt% are subjected to reduction roasting, in which As2O5 is reduced to As2O3 and removed in gaseous form to achieve first-stage arsenic removal. The roasted material is dissolved, and second-stage arsenic removal is achieved by cooling crystallization, and other impurity elements are simultaneously removed. After reduction and acid leaching of the high-purity vanadate after purification, a deep third-stage arsenic removal is achieved by adding an arsenic removal precipitant to obtain a V(IV) solution. After hydrolysis and sodium removal, the V(IV) solution is subjected to acid dissolution to obtain vanadium electrolyte.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of preparation of vanadium electrolyte, and particularly to a method for preparing vanadium electrolyte from high-arsenic vanadium-containing material. BACKGROUND

[0002] The high-arsenic vanadium-containing material refers to solid-state substances such as crude V2O5, red vanadium, ammonium polyvanadate, and ammonium metavanadate, with an arsenic content higher than 0.1 wt%, which is generally derived from waste SCR catalysts, stone coal, bauxite, and other raw materials. Due to the high content of arsenic, the high-arsenic vanadium-containing material is cheap but difficult to utilize.

[0003] Vanadium electrolyte for all-vanadium redox flow battery is a high-value vanadium product, which is mainly prepared from high-purity V2O5 with high price, however, this also leads to high cost of vanadium electrolyte. If high-arsenic vanadium-containing material is used to produce vanadium electrolyte, not only the high-value utilization of high-arsenic vanadium-containing material can be solved, but also the raw material cost of vanadium electrolyte production can be reduced. However, vanadium electrolyte directly determines the energy storage capacity and performance of vanadium battery. The national standard GB / T 37204-2018 has a very strict requirement on the arsenic concentration in vanadium electrolyte, which should be less than 1 ppm. Therefore, the arsenic must be purified and removed during the production of vanadium electrolyte from high-arsenic vanadium-containing material.

[0004] At present, the methods for purifying crude vanadium include ammonium precipitation method, chlorination method, crystallization method, and cation replacement method, etc. High-purity vanadium is prepared into vanadium electrolyte by chemical reduction method, electrolytic reduction method, and extraction method, etc. However, these methods do not involve how to achieve deep dearsenication of solid-state high-arsenic vanadium-containing material and preparation of vanadium electrolyte. Chinese patent CN 116536513 A discloses a method for separating and removing impurity arsenic in vanadium-containing solution raw material (1-100 mg / L) for producing electrolyte for all-vanadium redox flow battery. By adding calcium chloride and soluble barium salt into the vanadium-containing solution, arsenic and impurities such as phosphorus and silicon are removed at one time by filtration, and a vanadium-containing solution with deep dearsenication is obtained. This method has good dearsenication effect, but introduces calcium and barium ions, which still need to be further removed by extraction method. If the arsenic concentration in the solution is high, a large amount of vanadium will be lost, which is not suitable for deep dearsenication of high-arsenic vanadium-containing solution raw material. Ion exchange method can treat vanadium-containing solution with low arsenic content, but too high arsenic will cause poisoning and inactivation of ion exchange resin. At the same time, the above-mentioned methods are only suitable for dearsenication of vanadium-containing solution, and are not suitable for deep dearsenication and preparation of vanadium electrolyte from solid-state high-arsenic vanadium-containing material.

[0005] Chinese invention patent application with publication number CN 115747525 A provides a method for purifying crude vanadium by crystallization, dissolving crude vanadium in lye until saturation, adding ammonium salt to the saturated solution for vanadium precipitation treatment, and then precipitating ammonium metavanadate crystals. The ammonium metavanadate crystals are further purified by dissolution and cooling crystallization to obtain ammonium metavanadate with a purity of not less than 99%. However, this method introduces ammonium salt, producing ammonia-nitrogen wastewater that is difficult to treat and harmful to the environment. Chinese invention patent application with publication number CN 116404220 A provides a method for preparing high-concentration vanadium electrolyte by vanadate crystallization purification-chemical reduction, using crude vanadium and other vanadium-containing materials as raw materials, obtaining high-purity vanadate by alkali dissolution-crystallization purification, and then preparing vanadium electrolyte by chemical reduction of high-purity vanadate. The above two methods do not specify the arsenic content in crude vanadium and do not specifically provide a method for deep dearsenification, so they are not suitable for deep dearsenification and preparation of vanadium electrolyte from high-arsenic vanadium-containing raw materials.

[0006] In summary, the existing methods for purifying vanadium-containing raw materials and preparing electrolyte are not suitable for deep dearsenification and preparation of vanadium electrolyte from high-arsenic vanadium-containing raw materials. Therefore, there is an urgent need for a method for deep dearsenification and preparation of vanadium electrolyte from high-arsenic vanadium-containing raw materials. SUMMARY

[0007] To solve the problems in the prior art, the present application provides a method for preparing vanadium electrolyte from high-arsenic vanadium-containing material, which aims to purify and remove impurities from high-arsenic vanadium-containing material and prepare vanadium electrolyte, so that the obtained vanadium electrolyte meets the requirements of GB / T 37204-2018 for 4-valent vanadium electrolyte first-grade products, and the production cost of vanadium electrolyte is reduced.

[0008] Based on one aspect of the present application, a method for preparing vanadium electrolyte from high-arsenic vanadium-containing material is provided, which includes the following steps:

[0009] 1) Mix high-arsenic vanadium-containing material with dearsenification reducing agent in a ratio of 2-9 times the theoretical content of dearsenification reducing agent required for the reduction of As(V) to As(III), then press into blocks under a pressure of 50-150 MPa, and calcine in an inert atmosphere at a temperature of 200-700℃ for 1-6 h to obtain low-arsenic vanadium-containing material;

[0010] 2) Leach the low-arsenic vanadium-containing material with lye at 20-99℃, while stirring the solution at a speed of 50-200 r / min for 1-4 h, filter to obtain a vanadate solution, then cool the vanadate solution to 0-40℃ at a rate of 0.1-5℃ / min, stir the solution at a rate of ≤400 r / min during cooling, and filter to obtain vanadate crystals after cooling, then repeat step 2) multiple times with vanadate crystals replacing low-arsenic vanadium-containing material as raw material to obtain high-purity vanadate crystals;

[0011] 3) dissolving the high-purity vanadate crystal obtained in step 2) in acid and adjusting the pH value to 1-5, adding a reducing agent in an amount of 1.2-3 times the theoretical amount required for the reduction of V(V) to V(IV), and reacting at 20-99°C for 0.5-5 h to obtain a V(IV) solution, adjusting the pH value of the V(IV) solution to 1-5, adding an arsenic removal precipitant in an amount of 2-8 times the theoretical amount required for the removal of As(III) in multiple portions, and reacting at 20-99°C for 0.5-2 h to obtain an arsenic-removed solution, adjusting the pH value of the arsenic-removed solution to 5-12, and filtering to obtain VO(OH)2 solid, which is washed with acid and water, and the washed VO(OH)2 is dissolved with acid to prepare a vanadium electrolyte; wherein the reducing agent comprises one or more of sodium sulfide, elemental sulfur, sulfur dioxide, sulfite, oxalic acid, oxalate, glucose, fructose, sucrose, and formic acid.

[0012] As a preferred scheme of the method for preparing a vanadium electrolyte from high-arsenic vanadium-containing material according to the application, the high-arsenic vanadium-containing material comprises one or more of red vanadium, crude V2O5, ammonium polyvanadate, and ammonium metavanadate with an arsenic content of ≥0.1 wt%.

[0013] As a preferred scheme of the method for preparing a vanadium electrolyte from high-arsenic vanadium-containing material according to the application, the high-arsenic vanadium-containing material comprises 70-98 wt% V2O5; and the high-arsenic vanadium-containing material is obtained from the vanadium extraction process of waste SCR catalyst, stone coal, and / or bauxite.

[0014] As a preferred scheme of the method for preparing a vanadium electrolyte from high-arsenic vanadium-containing material according to the application, in step 1), the arsenic removal reducing agent comprises one or more of metallic vanadium, VO, V2O3, and VO2.

[0015] As a preferred scheme of the method for preparing a vanadium electrolyte from high-arsenic vanadium-containing material according to the application, in step 1), the inert atmosphere is an argon atmosphere.

[0016] As a preferred scheme of the method for preparing a vanadium electrolyte from high-arsenic vanadium-containing material according to the application, in step 2), the alkali solution comprises one or more of NaOH and KOH solutions with a concentration of 50-500 g / L.

[0017] As a preferred scheme of the method for preparing a vanadium electrolyte from high-arsenic vanadium-containing material according to the application, the multiple times in step 2) is 2-4 times.

[0018] As a preferred scheme of the method for preparing vanadium electrolyte from high-arsenic vanadium-containing material, the pH value adjustment specifically comprises: when the pH value needs to be lowered, adding one or more acids including sulfuric acid and hydrochloric acid into the solution for adjustment; and when the pH value needs to be raised, adding one or more bases including NaOH, KOH and NH3 into the solution for adjustment.

[0019] As a preferred scheme of the method for preparing vanadium electrolyte from high-arsenic vanadium-containing material, the arsenic removal precipitant comprises one or more of sodium sulfide, potassium sulfide, ammonium sulfide and hydrogen sulfide, and thiourea.

[0020] As a preferred scheme of the method for preparing vanadium electrolyte from high-arsenic vanadium-containing material, the multiple times in the step 3) is 3-5 times.

[0021] As a preferred scheme of the method for preparing vanadium electrolyte from high-arsenic vanadium-containing material, in the step 3), the reagent for pickling is dilute sulfuric acid with pH 5-7, the pickling washing times are 1-3 times, the washing times of water washing are 2-3 times, and the reagent for acid dissolution is sulfuric acid with a concentration of 4-6 mol / L.

[0022] The present application realizes three-stage cooperative deep arsenic removal and simultaneous preparation of vanadium electrolyte. Red vanadium, crude V2O5, ammonium polyvanadate and / or ammonium metavanadate with an arsenic content higher than 0.1 wt% are subjected to reduction roasting, in which As2O5 is reduced into As2O3 and removed in gaseous form to realize first-stage arsenic removal. The roasted material is dissolved, and second-stage arsenic removal is realized by using cooling crystallization, and other impurity elements are simultaneously removed. The purified high-purity vanadate is subjected to reduction acid leaching and then arsenic removal precipitant is added to realize third-stage deep arsenic removal, so as to obtain V(IV) solution. The V(IV) solution is subjected to hydrolysis sodium removal and then acid dissolution to obtain vanadium electrolyte.

[0023] In the technical scheme of the present application, the content is mass unless otherwise specified, As(V) refers to 5-valence arsenic, As(III) refers to 3-valence arsenic, V(V) refers to 5-valence vanadium, and V(IV) refers to 4-valence vanadium.

[0024] Compared with the prior art, the present application has the following beneficial effects:

[0025] 1、The present application realizes the deep removal of arsenic in high-arsenic vanadium-containing materials through reduction roasting, crystallization purification, and sulfidation precipitation, and the removal amount of arsenic meets the requirements for preparing vanadium electrolyte, compared with chemical precipitation method, ion exchange method, and single crystallization method, arsenic and other impurities are well removed, and the prepared vanadium electrolyte meets the requirements of GB / T 37204-2018 for 4-valence vanadium electrolyte first-grade product.

[0026] 2、The present application uses high-arsenic vanadium-containing materials as raw materials, compared with crude vanadium without arsenic and other industrial vanadium raw materials, the price is low, and no ammonium salt, organic extractant, chlorine, and other high-pollution and high-cost reagents are needed in the whole process, and the preparation process is clean and low-cost.

[0027] 3、The arsenic removal reductant and the precipitant used in the present application are original elements in the solution system, and no other impurity elements are introduced, and the purity of the vanadium electrolyte is not affected. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 Preparation method flowchart of the present application

[0029] Figure 2 Vanadium electrolyte prepared by the preparation method of the present application DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments 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, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0031] Embodiment 1

[0032] A method for preparing vanadium electrolyte from high-arsenic vanadium-containing materials, the main components of the high-arsenic vanadium-containing materials include V 53%, Al 0.1%, As 0.55%, Ca 0.1%, Fe 0.2%, K 0.1%, Mg 0.3%, Na 0.2%, and Si 1.5%, the method comprises the following steps:

[0033] 1) 100g of high-arsenic vanadium-containing materials is uniformly mixed with 4.4g of V2O3 (8 times the theoretical reaction amount), and then pressed into a block under a pressure of 100MPa, and then roasted at a temperature of 700℃ under an argon atmosphere for 4h, to obtain low-arsenic vanadium-containing materials with an arsenic content of 0.05 wt%;

[0034] 2) The low-arsenic vanadium-containing material is dissolved in 1 L of a 300 g / L NaOH solution at 60°C for leaching, with a stirring rate of 200 r / min and a leaching time of 2 h. A sodium vanadate solution is obtained by filtration, and then the sodium vanadate solution is cooled to 10°C at a rate of 0.5°C / min. The solution is stirred at a rate of 100 r / min during the cooling process. After cooling, sodium vanadate crystals are obtained by filtration. The low-arsenic vanadium-containing material is replaced with the sodium vanadate crystals as raw material, and step 2) is repeated twice to obtain 161 g of high-purity sodium vanadate crystals with an arsenic content of 0.01 wt% and a purity of 99.9%.

[0035] 3) The high-purity sodium vanadate crystals obtained in step 2) are dissolved in dilute sulfuric acid, and the pH value is adjusted to 0. 79.2 g of oxalic acid is added, and the mixture is reacted at 60°C for 2 h to obtain a V(IV) solution. The pH value of the V(IV) solution is adjusted to 2 with NaOH. 0.125 g of Na2S (0.041 g + 0.042 g + 0.042 g) is added in three portions, and the mixture is reacted at 60°C for 1 h. An arsenic-removed solution with an arsenic content of 5.5 ppm is obtained by filtration. The pH value of the arsenic-removed solution is adjusted to 6 with NaOH, and VO(OH)2 solid is obtained by filtration. The VO(OH)2 solid is washed twice with dilute sulfuric acid with a pH of 6, and then washed twice with pure water. The VO(OH)2 solid is dissolved in 500 ml of a 4 mol / L sulfuric acid solution to obtain a vanadium sulfate oxide electrolyte with a vanadium concentration of 1.6 mol / L and a sulfate concentration of 3.9 mol / L.

[0036] It is determined that the vanadium sulfate oxide electrolyte prepared in this embodiment has an arsenic content of 0.2 ppm, which meets the requirements of GB / T 37204-2018 "Electrolyte for all-vanadium redox flow battery" for 4-valent electrolyte first-grade products.

[0037] Example 2

[0038] A method for preparing a vanadium electrolyte from high-arsenic vanadium-containing material, wherein the main components of the high-arsenic vanadium-containing material include V 44%, Al 0.2%, As 0.34%, Ca 0.1%, Fe 0.1%, K 0.1%, Mg 0.2%, Na 0.2%, and Si 0.8%. The method comprises the following steps:

[0039] 1) 200 g of high-arsenic vanadium-containing material is mixed with 0.74 g of elemental vanadium powder, and then pressed into a block under a pressure of 120 MPa. The block is calcined at a temperature ranging from 500°C to 600°C for 2 h in an argon atmosphere to obtain low-arsenic vanadium-containing material with an arsenic content of 0.07 wt%.

[0040] 2) The low-arsenic vanadium-containing material is dissolved in 1.6 L of a KOH solution with a concentration of 400 g / L at 80°C, the stirring rate is 200 r / min, the leaching time is 1 h, and a potassium vanadate solution is obtained by filtration. Then, the potassium vanadate solution is cooled to 20°C at a rate of 2°C / min, the solution is stirred at a rate of 50 r / min during the cooling process, and potassium vanadate crystals are obtained by filtration after the cooling. Then, the low-arsenic vanadium-containing material is replaced by the potassium vanadate crystals as the raw material, and step 2) is repeated twice to obtain 280 g of high-purity potassium vanadate crystals with an arsenic content of 0.015 wt% and a purity of 99.93%.

[0041] 3) The high-purity sodium vanadate crystals obtained in step 2) are dissolved in dilute sulfuric acid, and the pH value is adjusted to -1. 150 g of sodium sulfite is added, and the reaction is carried out at 80°C for 1 h to obtain a V(IV) solution. The pH value of the V(IV) solution is adjusted to 0 with KOH, and 0.72 g of K2S (0.144 g each time) is added in five portions, and the reaction is carried out at 80°C for 1 h. An arsenic-removed solution with an arsenic content of 4.2 ppm is obtained by filtration. The pH value of the arsenic-removed solution is adjusted to 7 with KOH, and VO(OH)2 solid is obtained by filtration. The VO(OH)2 solid is washed twice with dilute sulfuric acid with a pH of 6.5, and then washed twice with pure water. The VO(OH)2 solid is dissolved in 400 ml of a 5 mol / L sulfuric acid solution to obtain a vanadium sulfate oxide electrolyte with a vanadium concentration of 2 mol / L and a sulfate concentration of 4.8 mol / L.

[0042] It is determined that the vanadium sulfate oxide electrolyte prepared in this embodiment has an arsenic content of 0.5 ppm, which meets the requirements of GB / T 37204-2018 "Electrolyte for all-vanadium redox flow battery" for 4-valent electrolyte first-grade products.

[0043] Example 3

[0044] A method for preparing a vanadium electrolyte by using high-arsenic vanadium-containing material, the main components of the high-arsenic vanadium-containing material include V 42%, Al 0.1%, As 0.44%, Ca 0.1%, Fe 0.1%, K 0.1%, Mg 0.2%, Na 0.2%, and Si 0.8%. The method comprises the following steps:

[0045] 1) 200 g of high-arsenic vanadium-containing material is mixed with 2.096 g of VO, and then pressed into a block under a pressure of 50 MPa and calcined at a temperature of 300°C in an argon atmosphere for 6 h to obtain low-arsenic vanadium-containing material with an arsenic content of 0.04 wt%;

[0046] 2) The low arsenic vanadium-containing material is dissolved in 1.5 L of a 250 g / L NaOH solution at 90°C, the stirring rate is 50 r / min, the leaching time is 3 h, a sodium vanadate solution is obtained by filtration, then the sodium vanadate solution is cooled to 5°C at a rate of 5°C / min, the solution is stirred at a rate of 300 r / min during the cooling, and a sodium vanadate crystal is obtained by filtration after the cooling, then the step 2) is repeated 4 times by replacing the low arsenic vanadium-containing material with the sodium vanadate crystal as a raw material, and 250 g of high-purity sodium vanadate crystal with an arsenic content of 0.025 wt% and a purity of 99.94% is obtained;

[0047] 3) The high-purity sodium vanadate crystal obtained in step 2) is dissolved in dilute sulfuric acid, the pH value is adjusted to 3, 10.86 g of elemental sulfur is added, and the reaction is carried out at 30°C for 5 h to obtain a V(IV) solution, the pH value of the V(IV) solution is adjusted to 4 with NaOH, 0.17 g of (NH4)2S (0.0425 g+0.0425 g+0.0425 g+0.0425 g) is added in four portions, and the reaction is carried out at 30°C for 2 h, a liquid after arsenic removal with an arsenic content of 6.7 ppm is obtained by filtration, the pH value of the liquid after arsenic removal is adjusted to 10 with NaOH, and a VO(OH)2 solid is obtained by filtration, the VO(OH)2 solid is washed once with dilute sulfuric acid with a pH value of 6.5 and three times with pure water, and is dissolved using 530 ml of a 5 mol / L sulfuric acid solution to obtain a vanadium sulfate oxide electrolyte with a vanadium concentration of 2.3 mol / L and a sulfate concentration of 4.8 mol / L.

[0048] It is determined that the vanadium sulfate oxide electrolyte prepared in the embodiment has an arsenic content of 0.3 ppm, which meets the requirements of GB / T 37204-2018 "Electrolyte for all-vanadium redox flow battery" for a 4-valent electrolyte first-grade product.

[0049] Example 4

[0050] A method for preparing a vanadium electrolyte by using a high-arsenic vanadium-containing material, the main components of the high-arsenic vanadium-containing material including V 51%, Al 0.1%, As 1.57%, Ca 0.1%, Fe 0.2%, K 0.1%, Mg 0.3%, Na 0.2%, and Si 1.5%, the method comprising the following steps:

[0051] 1) 50 g of the high-arsenic vanadium-containing material is mixed with 10.42 g of VO2, pressed into a block under a pressure of 100 MPa, and calcined at a temperature in the range of 400°C for 5 h under an argon atmosphere to obtain a low-arsenic vanadium-containing material with an arsenic content of 0.08 wt%;

[0052] 2) The low arsenic vanadium-containing material is dissolved in 500 mL of a KOH solution with a concentration of 250 g / L at 80°C, the stirring rate is 50 r / min, the leaching time is 1 h, a potassium vanadate solution is obtained by filtration, then the potassium vanadate solution is cooled to 2°C at a rate of 8°C / min, the solution is stirred at a rate of 80 r / min during the cooling, and a potassium vanadate crystal is obtained by filtration after the cooling, then the step 2) is repeated 4 times by replacing the low arsenic vanadium-containing material with the potassium vanadate crystal as a raw material, and 100 g of high-purity potassium vanadate crystal with an arsenic content of 0.07 wt% and a purity of 99.9% is obtained;

[0053] 3) The high-purity sodium vanadate crystal obtained in step 2) is dissolved in dilute sulfuric acid, the pH value is adjusted to 2.5, 48 g of potassium oxalate is added, and a V(IV) solution is obtained by reacting at 99°C for 0.5 h, the pH value of the V(IV) solution is adjusted to 0 with dilute sulfuric acid, 1.232 g of K2S (0.41 g+0.411 g+0.411 g) is added in three portions, and the reaction is carried out at 99°C for 1 h, a liquid after arsenic removal with an arsenic content of 4.5 ppm is obtained by filtration, the pH value of the liquid after arsenic removal is adjusted to 5 with KOH, and a VO(OH)2 solid is obtained by filtration, the VO(OH)2 solid is washed once with dilute sulfuric acid with a pH value of 6.5 and three times with pure water, and a vanadium concentration of 2 mol / L and a sulfate concentration of 5.8 mol / L are obtained by dissolving in 200 ml of a 6 mol / L sulfuric acid solution to obtain a vanadium sulfate oxide electrolyte.

[0054] It is determined that the vanadium sulfate oxide electrolyte prepared in the embodiment has an arsenic content of 0.5 ppm, which meets the requirements of GB / T 37204-2018 "Electrolyte for all-vanadium redox flow battery" for 4-valent electrolyte first-grade products.

[0055] Example 5

[0056] A method for preparing a vanadium electrolyte by using high-arsenic vanadium-containing material, the main components of the high-arsenic vanadium-containing material include V 48%, Al 0.1%, As 0.12%, Ca 0.1%, Fe 0.1%, K 0.1%, Mg 0.2%, Na 0.2%, and Si 0.8%, the method comprises the following steps:

[0057] 1) 300 g of high-arsenic vanadium-containing material is uniformly mixed with 3.24 g of V2O3, and then pressed into a block under a pressure of 150 MPa, and then calcined at a temperature in the range of 700°C under an argon atmosphere for 1 h to obtain a low-arsenic vanadium-containing material with an arsenic content of 0.01 wt%;

[0058] 2) The low arsenic vanadium-containing material is dissolved in 2.7 L of a 500 g / L NaOH solution at 99°C, the stirring rate is 200 r / min, the leaching time is 2 h, a sodium vanadate solution is obtained by filtration, then the sodium vanadate solution is cooled to 40°C at a rate of 10°C / min, the solution is stirred at a rate of 10 r / min during the cooling, and a sodium vanadate crystal is obtained by filtration after the cooling, then the step 2) is repeated twice by using the sodium vanadate crystal instead of the low arsenic vanadium-containing material as the raw material, and 482 g of high-purity sodium vanadate crystal with an arsenic content of 0.01 wt% and a purity of 99.95% is obtained;

[0059] 3) The high-purity sodium vanadate crystal obtained in step 2) is dissolved in dilute sulfuric acid, the pH value is adjusted to 5, 58.7 g of glucose is added, and the reaction is carried out at 20°C for 5 h to obtain a V(IV) solution, the pH value of the V(IV) solution is adjusted to 5 with dilute sulfuric acid, 0.225 g of Na2S is added in five portions (0.045 g each time), and the reaction is carried out at 20°C for 2 h, a solution after arsenic removal with an arsenic content of 3.7 ppm is obtained by filtration, the pH value of the solution after arsenic removal is adjusted to 12 with NaOH, and a VO(OH)2 solid is obtained by filtration, the VO(OH)2 solid is washed once with a dilute sulfuric acid solution with a pH value of 6.5 and three times with pure water, and 550 ml of a 6 mol / L sulfuric acid solution is used for dissolution to obtain a vanadium sulfate oxide electrolyte with a vanadium concentration of 3.5 mol / L and a sulfate concentration of 5.8 mol / L.

[0060] It is determined that the vanadium sulfate oxide electrolyte prepared in the embodiment has an arsenic content of 0.1 ppm, which meets the requirements of GB / T 37204-2018 "Electrolyte for all-vanadium redox flow battery" for the first-grade product of the 4-valence electrolyte.

[0061] Example 6

[0062] A method for preparing a vanadium electrolyte by using high-arsenic vanadium-containing material, the main components of the high-arsenic vanadium-containing material include V 43%, Al 0.1%, As 0.77%, Ca 0.1%, Fe 0.1%, K 0.1%, Mg 0.2%, Na 0.2%, and Si 0.8%, the method comprises the following steps:

[0063] 1) 100 g of high-arsenic vanadium-containing material is uniformly mixed with 0.42 g of elemental vanadium, pressed into a block under a pressure of 50 MPa, and calcined at a temperature in the range of 200°C for 6 h in an argon atmosphere to obtain a low-arsenic vanadium-containing material with an arsenic content of 0.05 wt%;

[0064] 2) The low-arsenic vanadium-containing material is dissolved in 750 mL of a 50 g / L KOH solution at 20 °C, the stirring rate is 200 r / min, the leaching time is 4 h, a potassium vanadate solution is obtained by filtration, then the potassium vanadate solution is cooled to 1 °C at a rate of 0.1 °C / min, the solution is stirred at a rate of 400 r / min during the cooling, and a potassium vanadate crystal is obtained by filtration after the cooling, then the step 2) is repeated twice by replacing the low-arsenic vanadium-containing material with the potassium vanadate crystal as the raw material, and 120 g of high-purity potassium vanadate crystal with an arsenic content of 0.06 wt% and a purity of 99.9% is obtained;

[0065] 3) The high-purity potassium vanadate crystal obtained in step 2) is dissolved in dilute sulfuric acid, the pH value is adjusted to -1, 15 g of formic acid is added, and the reaction is carried out at 50 °C for 2 h to obtain a V(IV) solution, the pH value of the V(IV) solution is adjusted to 5 with KOH, 1.26 g of K2S is added in four portions (0.315 g each time), and the reaction is carried out at 50 °C for 2 h, and an arsenic-removed solution with an arsenic content of 6 ppm is obtained by filtration, the pH value of the arsenic-removed solution is adjusted to 9 with KOH, and VO(OH)2 solid is obtained by filtration, the VO(OH)2 solid is washed twice with a dilute sulfuric acid solution with a pH of 6.5, and then washed three times with pure water, and 180 ml of a 5.5 mol / L sulfuric acid solution is used to dissolve the VO(OH)2 solid to obtain a vanadium sulfate oxide electrolyte with a vanadium concentration of 2.5 mol / L and a sulfate concentration of 5.2 mol / L.

[0066] It is determined that the vanadium sulfate oxide electrolyte prepared in the embodiment has an arsenic content of 0.2 ppm, which meets the requirements of GB / T 37204-2018 "Electrolyte for all-vanadium redox flow battery" for 4-valent electrolyte first-grade products.

[0067] Example 7

[0068] A method for preparing a vanadium electrolyte by using high-arsenic vanadium-containing material, the main components of the high-arsenic vanadium-containing material include V 52%, Al 0.1%, As 0.84%, Ca 0.1%, Fe 0.2%, K 0.1%, Mg 0.3%, Na 0.2%, Si 1.5%, the method comprises the following steps:

[0069] 1) 50 g of high-arsenic vanadium-containing material is mixed with 6.5 g of VO2, pressed into a block under a pressure of 100 MPa, and calcined at a temperature in the range of 450 °C for 5 h under an argon atmosphere to obtain a low-arsenic vanadium-containing material with an arsenic content of 0.07 wt%;

[0070] 2) The low-arsenic vanadium-containing material is dissolved in 500 mL of a KOH solution with a concentration of 250 g / L at 80°C, the stirring rate is 50 r / min, the leaching time is 1 h, and a potassium vanadate solution is obtained by filtration. Then, the potassium vanadate solution is cooled to 2°C at a rate of 8°C / min, the solution is stirred at a rate of 80 r / min during the cooling process, and potassium vanadate crystals are obtained by filtration after the cooling. Then, the step 2) is repeated twice by replacing the low-arsenic vanadium-containing material with the potassium vanadate crystals as the raw material, and 100 g of high-purity potassium vanadate crystals with an arsenic content of 0.06 wt% and a purity of 99.92% are obtained.

[0071] 3) The high-purity potassium vanadate crystals obtained in step 2) are dissolved in dilute sulfuric acid, and the pH value is adjusted to 2.5. Then, 48 g of potassium oxalate is added, and the reaction is carried out at 99°C for 0.5 h to obtain a V(IV) solution. The pH value of the V(IV) solution is adjusted to 0 with dilute sulfuric acid, and 1.056 g of K2S is added in three portions (0.352 g each portion). The reaction is carried out at 99°C for 1 h, and a solution after arsenic removal with an arsenic content of 4 ppm is obtained by filtration. The pH value of the solution after arsenic removal is adjusted to 5 with KOH, and VO(OH)2 solid is obtained by filtration. The VO(OH)2 solid is washed once with a dilute sulfuric acid solution with a pH of 6.5 and three times with pure water. Then, the VO(OH)2 solid is dissolved using 200 ml of a 6 mol / L sulfuric acid solution to obtain a vanadium sulfate solution with a vanadium concentration of 2 mol / L and a sulfate concentration of 5.8 mol / L.

[0072] It is determined that the vanadium sulfate solution prepared in the embodiment has an arsenic content of 0.4 ppm, which meets the requirements of GB / T 37204-2018 "Electrolyte for all-vanadium redox flow battery" for the first-grade product of the 4-valence electrolyte.

[0073] Comparative Example 1

[0074] A method for preparing a vanadium electrolyte by using high-arsenic vanadium-containing material, the main components of the high-arsenic vanadium-containing material include V 53%, Al 0.1%, As 0.55%, Ca 0.1%, Fe 0.2%, K 0.1%, Mg 0.3%, Na 0.2%, and Si 1.5%. The method comprises the following steps:

[0075] 1) 100 g of high-arsenic vanadium-containing material is mixed with 0.55 g of V2O3 (1 times the theoretical reaction amount), and then pressed into a block under a pressure of 100 MPa and calcined at a temperature in the range of 700°C under an argon atmosphere for 4 h to obtain low-arsenic vanadium-containing material with an arsenic content of 0.32 wt%;

[0076] 2) The low-arsenic vanadium-containing material is dissolved in 1 L of a 300 g / L NaOH solution at 60°C for leaching, with a stirring rate of 200 r / min and a leaching time of 2 h. A sodium vanadate solution is obtained by filtration, and then the sodium vanadate solution is cooled to 10°C at a rate of 0.5°C / min. The solution is stirred at a rate of 100 r / min during the cooling process. After cooling, sodium vanadate crystals are obtained by filtration. The low-arsenic vanadium-containing material is replaced with the sodium vanadate crystals as a raw material, and step 2) is repeated twice to obtain 161 g of high-purity sodium vanadate crystals with an arsenic content of 0.16 wt% and a purity of 99.74%.

[0077] 3) The high-purity sodium vanadate crystals obtained in step 2) are dissolved in dilute sulfuric acid, and the pH value is adjusted to 0. 79.2 g of oxalic acid is added, and the mixture is reacted at 60°C for 2 h to obtain a V(IV) solution. The pH value of the V(IV) solution is adjusted to 2 with NaOH. 0.125 g of Na2S (0.041 g + 0.042 g + 0.042 g) is added in three portions, and the mixture is reacted at 60°C for 1 h. A solution after arsenic removal with an arsenic content of 15.8 ppm is obtained by filtration. The pH value of the solution after arsenic removal is adjusted to 6 with NaOH. VO(OH)2 solid is obtained by filtration. The VO(OH)2 solid is washed twice with dilute sulfuric acid with a pH of 6, and then washed twice with pure water. The VO(OH)2 solid is dissolved in 500 ml of a 4 mol / L sulfuric acid solution to obtain a vanadium sulfate oxide electrolyte with a vanadium concentration of 1.6 mol / L and a sulfate concentration of 3.9 mol / L.

[0078] It is determined that the vanadium sulfate oxide electrolyte prepared in the present comparative example has an arsenic content of 3.3 ppm, which does not meet the requirements of GB / T 37204-2018 "Electrolyte for all-vanadium redox flow battery" for 4-valent electrolyte first-grade products. Compared with Example 1, the amount of arsenic removal reducing agent added in the present comparative example is too small, resulting in that most of the arsenic in the high-arsenic vanadium-containing material cannot react with the reducing agent to form gaseous As2O3 and be removed, leading to a high arsenic content in the low-arsenic vanadium-containing material. The subsequent crystallization and sulfidation precipitation processes are difficult to completely remove these arsenic, ultimately resulting in a high arsenic content in the vanadium electrolyte.

[0079] Comparative Example 2

[0080] A method for preparing a vanadium electrolyte from high-arsenic vanadium-containing material, wherein the main components of the high-arsenic vanadium-containing material include V 44%, Al 0.2%, As 0.34%, Ca 0.1%, Fe 0.1%, K 0.1%, Mg 0.2%, Na 0.2%, and Si 0.8%. The method comprises the following steps:

[0081] 1) 200 g of high-arsenic vanadium-containing material is mixed with 0.74 g of elemental vanadium powder, and then pressed into a block under a pressure of 120 MPa. The block is calcined at a temperature ranging from 150°C to 200°C for 2 h in an argon atmosphere to obtain a low-arsenic vanadium-containing material with an arsenic content of 0.33 wt%.

[0082] 2) The low-arsenic vanadium-containing material is dissolved in 1.6 L of a 400 g / L KOH solution at 80°C for leaching, with a stirring rate of 200 r / min and a leaching time of 1 h, and a potassium vanadate solution is obtained by filtration. Then the potassium vanadate solution is cooled to 20°C at a rate of 2°C / min, and the solution is stirred at a rate of 50 r / min during the cooling process. After cooling, the potassium vanadate crystals are obtained by filtration, and the low-arsenic vanadium-containing material is replaced with the potassium vanadate crystals as raw material to repeat step 2) twice, thereby obtaining 280 g of high-purity potassium vanadate crystals with an arsenic content of 0.13 wt% and a purity of 99.8%.

[0083] 3) The high-purity sodium vanadate crystals obtained in step 2) are dissolved in dilute sulfuric acid, and the pH value is adjusted to -1. 150 g of sodium sulfite is added, and the mixture is reacted at 80°C for 1 h to obtain a V(IV) solution. The pH value of the V(IV) solution is adjusted to 0 with KOH, and 0.72 g of K2S (0.144 g each time) is added in five portions, and the mixture is reacted at 80°C for 1 h. The arsenic-removed solution with an arsenic content of 22.1 ppm is obtained by filtration. The pH value of the arsenic-removed solution is adjusted to 7 with KOH, and the VO(OH)2 solid is obtained by filtration. The VO(OH)2 solid is washed twice with dilute sulfuric acid with a pH of 6.5, and then washed twice with pure water. The VO(OH)2 solid is dissolved in 400 ml of a 5 mol / L sulfuric acid solution to obtain a vanadium concentration of 2 mol / L and a sulfate concentration of 4.8 mol / L, thereby obtaining a vanadyl sulfate electrolyte.

[0084] It is determined that the vanadyl sulfate electrolyte prepared in the present comparative example has an arsenic content of 4.5 ppm, which does not meet the requirements of GB / T 37204-2018 "Electrolyte for all-vanadium redox flow battery" for the first-grade product of the 4-valence electrolyte. Compared with Example 2, the reduction roasting temperature in the present comparative example is too low, and the reaction temperature of As2O5 and the arsenic-removing reducing agent is not reached, so that the arsenic in the high-arsenic vanadium-containing material cannot be removed in the form of gaseous As2O3, and the arsenic content in the low-arsenic vanadium-containing material is high. It is difficult to completely remove these arsenic in the subsequent crystallization and sulfidation precipitation processes, and finally the arsenic content of the vanadium electrolyte is too high.

[0085] Comparative Example 3

[0086] A method for preparing a vanadium electrolyte from high-arsenic vanadium-containing material, wherein the main components of the high-arsenic vanadium-containing material include V 42%, Al 0.1%, As 0.44%, Ca 0.1%, Fe 0.1%, K 0.1%, Mg 0.2%, Na 0.2%, and Si 0.8%, and the method comprises the following steps:

[0087] 1) 200 g of high-arsenic vanadium-containing material was mixed with 2.096 g of V0, then pressed into a block under a pressure of 50 MPa, and calcined at a temperature in the range of 300 °C for 0.5 h under an argon atmosphere to obtain low-arsenic vanadium-containing material with an arsenic content of 0.24 wt%;

[0088] 2) The low-arsenic vanadium-containing material was leached in a 1.5 L NaOH solution with a concentration of 250 g / L at 90 °C for 3 h with a stirring rate of 50 r / min, and a sodium vanadate solution was obtained by filtration. Then the sodium vanadate solution was cooled to 5 °C at a rate of 5 °C / min, and the solution was stirred at a rate of 300 r / min during the cooling process. After cooling, sodium vanadate crystals were obtained by filtration. Then the step 2) was repeated 4 times by replacing the low-arsenic vanadium-containing material with the sodium vanadate crystals as raw material. 250 g of high-purity sodium vanadate crystals with an arsenic content of 0.12 wt% and a purity of 99.82% were obtained.

[0089] 3) The high-purity sodium vanadate crystals obtained in step 2) were dissolved in dilute sulfuric acid, and the pH value was adjusted to 3. 10.86 g of elemental sulfur was added and reacted at 30 °C for 5 h to obtain a V(IV) solution. The pH value of the V(IV) solution was adjusted to 4 with NaOH, and 0.17 g of (NH4)2S (0.0425 g + 0.0425 g + 0.0425 g + 0.0425 g) was added in four portions and reacted at 30 °C for 2 h. An arsenic-removed solution with an arsenic content of 13.2 ppm was obtained by filtration. The pH value of the arsenic-removed solution was adjusted to 10 with NaOH, and VO(OH)2 solid was obtained by filtration. The VO(OH)2 solid was washed once with dilute sulfuric acid with a pH of 6.5 and three times with pure water. The VO(OH)2 solid was dissolved in 530 ml of 5 mol / L sulfuric acid solution to obtain a vanadyl sulfate electrolyte with a vanadium concentration of 2.3 mol / L and a sulfate concentration of 4.8 mol / L.

[0090] It was determined that the vanadyl sulfate electrolyte prepared in the present example had an arsenic content of 1.5 ppm, which did not meet the requirements of GB / T 37204-2018 "Electrolyte for all-vanadium redox flow battery" for 4-valent electrolyte first-grade products. Compared with Example 3, the reduction calcination time in the present example was too short, resulting in that part of the arsenic in the high-arsenic vanadium-containing material could not be removed in time by reacting with the reducing agent to form gaseous As2O3, so that the arsenic content in the low-arsenic vanadium-containing material was relatively high, and the subsequent crystallization and sulfidation precipitation processes could not completely remove these arsenic, resulting in a too high arsenic content in the vanadium electrolyte.

[0091] Comparative Example 4

[0092] A method for preparing vanadium electrolyte by using high-arsenic vanadium-containing material, the main components of the high-arsenic vanadium-containing material include V 51%, Al 0.1%, As 1.57%, Ca 0.1%, Fe 0.2%, K 0.1%, Mg 0.3%, Na 0.2%, Si 1.5%, the method comprises the following steps:

[0093] 1) 50g high-arsenic vanadium-containing material is mixed with 10.42g VO2, then pressed into a block under a pressure of 100MPa, and calcined at a temperature range of 400℃ under an argon atmosphere for 5h, to obtain low-arsenic vanadium-containing material with an arsenic content of 0.08wt%;

[0094] 2) the low-arsenic vanadium-containing material is dissolved in 500mL KOH solution with a concentration of 250g / L at 80℃, the stirring rate is 50r / min, the leaching time is 1h, filtration is performed to obtain potassium vanadate solution, then the potassium vanadate solution is cooled to 2℃ at a rate of 8℃ / min, the solution is stirred at a rate of 80r / min during the cooling, and filtration is performed after the cooling to obtain potassium vanadate crystals, then step 2) is repeated 4 times by replacing the low-arsenic vanadium-containing material with the potassium vanadate crystals as raw material, to obtain 100g high-purity potassium vanadate crystals with an arsenic content of 0.07wt% and a purity of 99.9%;

[0095] 3) the high-purity sodium vanadate crystals obtained in step 2) are dissolved in dilute sulfuric acid, the pH value is adjusted to 2.5, 48g potassium oxalate is added, and the reaction is carried out at 99℃ for 0.5h to obtain V(IV) solution, the pH value of the V(IV) solution is adjusted to 0 with dilute sulfuric acid, 0.154g K2S (0.051g+0.051g+0.052g, theoretical reaction amount 1 times) is added in 3 portions, and the reaction is carried out at 99℃ for 1h, filtration is performed to obtain arsenic-removed solution with an arsenic content of 36ppm, the pH value of the arsenic-removed solution is adjusted to 5 with KOH, filtration is performed to obtain VO(OH)2 solid, the VO(OH)2 solid is washed once with dilute sulfuric acid with a pH value of 6.5, and then washed 3 times with pure water, and the VO(OH)2 solid is dissolved with 200ml 6mol / L sulfuric acid solution to obtain vanadium sulfate electrolyte with a vanadium concentration of 2mol / L and a sulfate concentration of 5.8mol / L.

[0096] It is determined that the arsenic content of the vanadium sulfate electrolyte prepared in the present comparative example is 5 ppm, which does not meet the requirements of GB / T 37204-2018 "Electrolyte for all-vanadium redox flow battery" for 4-valent electrolyte primary product. Compared with Example 4, the amount of precipitant added in the present comparative example is too low, and the arsenic in the V(IV) solution cannot be removed deeply, resulting in arsenic ions being included in the VO(OH)2 and entering the vanadium electrolyte, so that the arsenic content of the vanadium electrolyte exceeds the standard. 3+ Deep removal, resulting in arsenic ions being included in the VO(OH)2 and entering the vanadium electrolyte, so that the arsenic content of the vanadium electrolyte exceeds the standard.

[0097] Comparative Example 5

[0098] A method for preparing vanadium electrolyte using high-arsenic vanadium-containing material, wherein the main components of the high-arsenic vanadium-containing material include 48% V, 0.1% Al, 0.12% As, 0.1% Ca, 0.1% Fe, 0.1% K, 0.2% Mg, 0.2% Na, and 0.8% Si, and the method includes the following steps:

[0099] 1) Mix 300g of high arsenic vanadium-containing material with 3.24g of V2O3, press it into blocks under 150MPa pressure, and calcine it at 700℃ for 1h under argon atmosphere to obtain low arsenic vanadium-containing material with arsenic content of 0.01wt%.

[0100] 2) The low-arsenic vanadium-containing material was dissolved in 2.7L of 500g / L NaOH solution at 99℃ and leached with a stirring rate of 200r / min for 2h. The solution was filtered to obtain sodium vanadate solution. The sodium vanadate solution was then cooled to 40℃ at a rate of 10℃ / min, with the solution stirred at a rate of 10r / min during the cooling process. After cooling, the solution was filtered to obtain sodium vanadate crystals. The sodium vanadate crystals were then used to replace the low-arsenic vanadium-containing material as raw material, and step 2) was repeated twice to obtain 482g of high-purity sodium vanadate crystals with an arsenic content of 0.01wt% and a purity of 99.95%.

[0101] 3) Dissolve the high-purity sodium vanadate crystals obtained in step 2) in dilute sulfuric acid and adjust the pH to 5. Add 58.7g of glucose and react at 20℃ for 5h to obtain V(IV) solution. Adjust the pH of V(IV) solution to 9 with NaOH. Then add 0.225g of Na2S in 5 portions (0.045g each time) and react at 20℃ for 2h. Filter to obtain an arsenic-removed solution with an As content of 26.3ppm. Adjust the pH of the arsenic-removed solution to 12 with NaOH and filter to obtain VO(OH)2 solid. Wash the VO(OH)2 solid once with dilute sulfuric acid solution at pH 6.5, then wash it three times with pure water. Dissolve it in 550ml of 6mol / L sulfuric acid solution to obtain a vanadium oxysulfate electrolyte with a vanadium concentration of 3.5mol / L and a sulfate concentration of 5.8mol / L.

[0102] The As content in the vanadium oxysulfate electrolyte prepared in this comparative example was determined to be 4 ppm, which does not meet the requirements for Grade I tetravalent electrolytes in GB / T 37204-2018 "Electrolytes for Vanadium Redox Flow Batteries". Compared with Example 5, the pH of the sulfide precipitation in this comparative example was too high, and the As content was too high. 3+ Unable to meet with S 2- The formation of insoluble precipitate As2S3 means that arsenic ions in the V(IV) solution are not thoroughly removed, causing arsenic ions to be trapped in VO(OH)2 and enter the vanadium electrolyte, resulting in excessive arsenic content in the vanadium electrolyte.

[0103] Comparative Example 6

[0104] A method for preparing vanadium electrolyte by using high-arsenic vanadium-containing material, the main components of the high-arsenic vanadium-containing material include V 43%, Al 0.1%, As 0.77%, Ca 0.1%, Fe 0.1%, K 0.1%, Mg 0.2%, Na 0.2%, Si 0.8%, the method comprises the following steps:

[0105] 1) 100g high-arsenic vanadium-containing material is mixed with 0.42g elemental vanadium, then pressed into a block under a pressure of 50MPa, and calcined at a temperature ranging from 200℃ to 200℃ under an argon atmosphere for 6h, to obtain low-arsenic vanadium-containing material with an arsenic content of 0.05wt%;

[0106] 2) the low-arsenic vanadium-containing material is dissolved in 750mL KOH solution with a concentration of 50g / L at 20℃, the stirring rate is 200r / min, the leaching time is 4h, filtration is performed to obtain potassium vanadate solution, then the potassium vanadate solution is cooled to 1℃ at a rate of 0.1℃ / min, the solution is stirred at a rate of 400r / min during the cooling process, and filtration is performed after the cooling to obtain potassium vanadate crystals, then the step 2) is repeated twice by replacing the low-arsenic vanadium-containing material with the potassium vanadate crystals as raw material, to obtain 120g high-purity potassium vanadate crystals with an arsenic content of 0.06wt% and a purity of 99.9%;

[0107] 3) the high-purity potassium vanadate crystals obtained in step 2) are dissolved in dilute sulfuric acid, the pH value is adjusted to -1, 15g formic acid is added, and the reaction is carried out at 50℃ for 2h to obtain V(IV) solution, the pH value of the V(IV) solution is adjusted to 5 with KOH, 1.26g K2S is added in 4 portions (0.315g each time), and the reaction is carried out at 2℃ for 1h, filtration is performed to obtain arsenic-removed solution with an arsenic content of 31.2ppm, the pH value of the arsenic-removed solution is adjusted to 9 with KOH, and filtration is performed to obtain VO(OH)2 solid, the VO(OH)2 solid is washed twice with dilute sulfuric acid solution with a pH value of 6.5, then washed three times with pure water, and dissolved using 180ml 5.5mol / L sulfuric acid solution to obtain vanadyl sulfate electrolyte with a vanadium concentration of 2.5mol / L and a sulfate concentration of 5.2mol / L.

[0108] It is determined that the arsenic content in the vanadyl sulfate electrolyte prepared in the present comparative example is 1.5ppm, which does not meet the requirements of GB / T 37204-2018 "Electrolyte for all-vanadium redox flow battery" for 4-valent electrolyte primary product. Compared with Example 6, the temperature of sulfidation precipitation in the present comparative example is too low, the As in the V(IV) solution is not removed in time by generating precipitate, and the arsenic ion is mixed in the VO(OH)2 to enter the vanadium electrolyte, resulting in that the arsenic content of the vanadium electrolyte exceeds the standard. 3+ S 2- reactivity is poor, and the precipitate cannot be generated in time to remove the arsenic ion, resulting in that the arsenic ion is mixed in the VO(OH)2 to enter the vanadium electrolyte, and the arsenic content of the vanadium electrolyte exceeds the standard.

[0109] Comparative Example 7

[0110] A method for preparing a vanadium electrolyte from high-arsenic vanadium-containing material, the main components of the high-arsenic vanadium-containing material including V 52%, Al 0.1%, As 0.84%, Ca 0.1%, Fe 0.2%, K 0.1%, Mg 0.3%, Na 0.2%, Si 1.5%, the method comprising the following steps:

[0111] 1) After mixing 50 g of high-arsenic vanadium-containing material with 6.5 g of VO2, briquetting under a pressure of 100 MPa, and roasting at a temperature in the range of 450°C under an argon atmosphere for 5 h, a low-arsenic vanadium-containing material with an arsenic content of 0.07 wt% is obtained;

[0112] 2) The low-arsenic vanadium-containing material is leached in 500 mL of a KOH solution with a concentration of 250 g / L at 80°C, the stirring rate is 50 r / min, the leaching time is 1 h, filtration is performed to obtain a potassium vanadate solution, then the potassium vanadate solution is cooled to 2°C at a rate of 8°C / min, the solution is stirred at a rate of 80 r / min during the cooling, and after cooling, filtration is performed to obtain potassium vanadate crystals, then step 2) is repeated twice with the potassium vanadate crystals replacing the low-arsenic vanadium-containing material as raw material, and 100 g of high-purity potassium vanadate crystals with an arsenic content of 0.06 wt% and a purity of 99.92% are obtained;

[0113] 3) The high-purity potassium vanadate crystals obtained in step 2) are dissolved in dilute sulfuric acid, the pH value is adjusted to 2.5, 48 g of potassium oxalate is added, and the reaction is carried out at 99°C for 0.5 h to obtain a V(IV) solution, the pH value of the V(IV) solution is adjusted to 0 with dilute sulfuric acid, 1.056 g of K2S is added at once, and the reaction is carried out at 99°C for 1 h, filtration is performed to obtain an arsenic-removed solution with an arsenic content of 16 ppm, the pH value of the arsenic-removed solution is adjusted to 5 with KOH, and filtration is performed to obtain VO(OH)2 solids, the VO(OH)2 solids are washed once with a dilute sulfuric acid solution with a pH value of 6.5 and then three times with pure water, and the VO(OH)2 solids are dissolved using 200 ml of a 6 mol / L sulfuric acid solution to obtain a vanadyl sulfate electrolyte with a vanadium concentration of 2 mol / L and a sulfate concentration of 5.8 mol / L.

[0114] It is determined that the vanadyl sulfate electrolyte prepared in this comparative example has an arsenic content of 2.6 ppm, which does not meet the requirements of GB / T 37204-2018 "Electrolyte for all-vanadium redox flow battery" for 4-valent electrolyte first-grade products. Compared with Example 7, the arsenic removal precipitant in this comparative example is added at once, which causes the S 2- concentration in the V(IV) solution to instantaneously increase, the H 2- in the solution reacts with S + to rapidly generate H2S gas, thereby reducing the amount of S 2- in the solution, and causing the As 3+Failed to effectively precipitate to achieve deep removal, As 3+ Inclusion in VO(OH)2 into electrolyte, leading to vanadium electrolyte arsenic content exceeding standard.

[0115] Comparative Example 8

[0116] A method for preparing vanadium electrolyte from high-arsenic vanadium-containing material, the main components of the high-arsenic vanadium-containing material including V 52%, Al 0.1%, As 0.84%, Ca 0.1%, Fe 0.2%, K 0.1%, Mg 0.3%, Na 0.2%, Si 1.5%, the method comprising the following steps:

[0117] 1) 50g high-arsenic vanadium-containing material was dissolved in 500mL KOH solution with a concentration of 250g / L at 80℃, the stirring rate was 50r / min, the leaching time was 1h, and the potassium vanadate solution was obtained by filtration, then the potassium vanadate solution was cooled to 2℃ at a rate of 8℃ / min, the solution was stirred at a rate of 80r / min during cooling, and the potassium vanadate crystal was obtained by filtration after cooling, then the step 2) was repeated twice by replacing the low-arsenic vanadium-containing material with the potassium vanadate crystal as raw material, and 100g high-purity potassium vanadate crystal with an arsenic content of 0.4wt% and a purity of 99.8% was obtained;

[0118] 2) The high-purity potassium vanadate crystal obtained in step 1) was dissolved in dilute sulfuric acid, and the pH value was adjusted to 2.5, 48g potassium oxalate was added, and reacted at 99℃ for 0.5h to obtain V(IV) solution, the pH value of the V(IV) solution was adjusted to 0 with dilute sulfuric acid, 1.056g K2S was added in 3 portions (0.352g each time), and reacted at 99℃ for 1h, and the arsenic-removed solution with an arsenic content of 40ppm was obtained by filtration, the pH value of the arsenic-removed solution was adjusted to 5 with KOH, and the VO(OH)2 solid was obtained by filtration, the VO(OH)2 solid was washed once with dilute sulfuric acid solution with a pH of 6.5, and then washed three times with pure water, and dissolved with 200ml 6mol / L sulfuric acid solution to obtain vanadium sulfate solution with a vanadium concentration of 2mol / L and a sulfate concentration of 5.8mol / L.

[0119] It was determined that the arsenic content in the vanadium sulfate solution prepared in this comparative example was 16.9ppm, which did not meet the requirements of GB / T 37204-2018 "Electrolyte for all-vanadium redox flow battery" for 4-valent electrolyte first-grade product. Compared with Example 7, this comparative example did not have the reduction roasting arsenic removal step to remove arsenic in the high-arsenic vanadium-containing material, and only relied on the crystallization and precipitation method to remove arsenic, resulting in reduced arsenic removal effect and exceeding the arsenic content in the vanadium electrolyte.

[0120] Comparative Example 9

[0121] A method for preparing vanadium electrolyte by using high-arsenic vanadium-containing material, the main components of the high-arsenic vanadium-containing material include V 52%, Al 0.1%, As 0.84%, Ca 0.1%, Fe 0.2%, K 0.1%, Mg 0.3%, Na 0.2%, Si 1.5%, the method comprises the following steps:

[0122] 1) 50g high-arsenic vanadium-containing material is mixed with 6.5g VO2, then pressed into a block under a pressure of 100MPa, and calcined at a temperature range of 450℃ under an argon atmosphere for 5h, to obtain low-arsenic vanadium-containing material with an arsenic content of 0.07wt%;

[0123] 2) the low-arsenic vanadium-containing material is dissolved in 500mL KOH solution with a concentration of 250g / L at 80℃, the stirring rate is 50r / min, the leaching time is 1h, filtration is performed to obtain a potassium vanadate solution, then the potassium vanadate solution is cooled to 2℃ at a rate of 8℃ / min, the solution is stirred at a rate of 80r / min during the cooling, and filtration is performed after the cooling to obtain potassium vanadate crystals, then step 2) is repeated twice by replacing the low-arsenic vanadium-containing material with the potassium vanadate crystals as raw material, to obtain 100g high-purity potassium vanadate crystals with an arsenic content of 0.06wt% and a purity of 99.92%;

[0124] 3) the high-purity potassium vanadate crystals obtained in step 2) are dissolved in dilute sulfuric acid, the pH value is adjusted to 2.5, 48g potassium oxalate is added, and the mixture is reacted at 99℃ for 0.5h to obtain a V(IV) solution with an As content of 21ppm, the pH value of the V(IV) solution is adjusted to 5 with KOH, filtration is performed to obtain VO(OH)2 solid, the VO(OH)2 solid is washed once with a dilute sulfuric acid solution with a pH of 6.5, and then washed three times with pure water, and the VO(OH)2 solid is dissolved using 200ml 6mol / L sulfuric acid solution to obtain vanadyl sulfate electrolyte with a vanadium concentration of 2mol / L and a sulfate concentration of 5.8mol / L.

[0125] It is determined that the As content of the vanadyl sulfate electrolyte prepared in the present comparative example is 5.5ppm, which does not meet the requirements of GB / T 37204-2018 "Electrolyte for all-vanadium redox flow battery" for the first-grade product of 4-valence electrolyte. Compared with example 7, the present comparative example does not have the arsenic removal step by precipitation, so that the residual arsenic in the V(IV) solution cannot be removed deeply, and the arsenic content in the vanadium electrolyte exceeds the standard.

[0126] It should be noted that according to the above-mentioned embodiments of the present application, the person skilled in the art can fully realize the scope of the independent claims and dependent claims of the present application, and the implementation process and method are the same as the above-mentioned embodiments; and the part not elaborated in the present application belongs to the known technology in the art. However, the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think of changes or replacements within the technical scope disclosed by the present application, which should be covered within the protection scope of the present application.

Claims

1. A method for preparing vanadium electrolyte from high-arsenic vanadium-containing material, characterized in that, The method comprises the following steps: 1) mixing high-arsenic vanadium-containing material with dearsenification reducing agent in a ratio of 2-9 times the theoretical amount of dearsenification reducing agent required for reducing As(V) to As(III), and then pressing the mixture into blocks under a pressure of 50-150 MPa, and then roasting the blocks in an inert atmosphere at a temperature of 200-700 ℃ for 1-6 h to obtain low-arsenic vanadium-containing material; 2) leaching the low-arsenic vanadium-containing material with lye at 20-99 ℃ while stirring the solution at a speed of 50-200 r / min for 1-4 h, filtering to obtain a vanadate solution, and then cooling the vanadate solution to 0-40 ℃ at a rate of 0.1-5 ℃ / min, stirring the solution at a rate of ≤400 r / min during the cooling, and filtering to obtain vanadate crystals after the cooling, and then repeating step 2) multiple times with the vanadate crystals replacing the low-arsenic vanadium-containing material as raw material to obtain high-purity vanadate crystals; 3) dissolving the high-purity vanadate crystals obtained in step 2) in acid and adjusting the pH value to 1-5, adding reducing agent in an amount of 1.2-3 times the theoretical amount of reducing agent required for reducing V(V) to V(IV), and reacting at 20-99 ℃ for 0.5-5 h to obtain a V(IV) solution, adjusting the pH value of the V(IV) solution to -1-5, adding dearsenification precipitant in an amount of 2-8 times the theoretical amount of dearsenification precipitant required for removing As(III) in multiple portions, and reacting at 20-99 ℃ for 0.5-2 h to obtain a dearsenification post-liquid, adjusting the pH value of the dearsenification post-liquid to 5-12, and filtering to obtain VO(OH)2 solid, and then washing the VO(OH)2 solid with acid and water, dissolving the washed VO(OH)2 with acid, and preparing a vanadium electrolyte; wherein the reducing agent comprises one or more of sodium sulfide, elemental sulfur, sulfur dioxide, sulfite, oxalic acid, oxalate, glucose, fructose, sucrose, and formic acid.

2. The method of claim 1, wherein, The high-arsenic vanadium-containing material comprises one or more of red vanadium, crude V2O5, ammonium polyvanadate, and ammonium metavanadate with an arsenic content of ≥0.1 wt%.

3. The method of claim 1, wherein, The high-arsenic vanadium-containing material contains 70-98 wt% of V2O5, and the high-arsenic vanadium-containing material is obtained from a vanadium extraction process of waste SCR catalyst, stone coal, and / or bauxite.

4. The method of claim 1, wherein, In step 1), the dearsenification reducing agent comprises one or more of metallic vanadium, VO, V2O3, and VO2.

5. The method according to any one of claims 1 to 4, characterized in that, In step 2), the lye comprises one or more of NaOH and KOH solutions with a concentration of 50-500 g / L.

6. The method according to any one of claims 1 to 4, wherein The multiple times in step 2) is 2-4 times.

7. The method according to any one of claims 1 to 4, wherein The adjustment of the pH value is specifically: when it is necessary to lower the pH value, an acid comprising one or more of sulfuric acid and hydrochloric acid is added to the solution for adjustment, and when it is necessary to raise the pH value, a base comprising one or more of NaOH, KOH, and NH3 is added to the solution for adjustment.

8. The method of any one of claims 1-4, wherein, The dearsenification precipitant comprises one or more of sodium sulfide, potassium sulfide, ammonium sulfide, hydrogen sulfide, and thiourea.

9. The method of any one of claims 1-4, wherein, The multiple times in step 3) is 3-5 times.

10. The method of any one of claims 1-4, wherein, In step 3), the reagent used in the pickling is dilute sulfuric acid with pH 5-7, the pickling is performed for 1-3 times, and the water washing is performed for 2-3 times; the reagent used in the acid dissolution is sulfuric acid with a concentration of 4-6 mol / L.

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