A vanadium electrolyte and its preparation method and application

Abstract

The present invention provides a vanadium electrolyte and its preparation method and application. The preparation method of the vanadium electrolyte comprises: taking vanadium ore, adding sulfuric acid thereto, and mixing uniformly to obtain a mixture; slaking the mixture to obtain a slaking material; leaching the slaking material with water to obtain a vanadium-containing leachate; adding a first impurity remover to the vanadium-containing leachate to obtain a first purified liquid; adding an oxidizing agent, ferric phosphate dihydrate seed crystals, and a second impurity remover to the first purified liquid to obtain a second purified liquid; adding a reducing agent and a flocculant to the second purified liquid, and filtering to obtain a filtrate; mixing the filtrate with an extract to obtain a vanadium-loaded organic phase; stripping the vanadium-loaded organic phase to obtain a stripping solution; and removing the organic phase from the stripping solution to obtain a vanadium electrolyte. The preparation method of the vanadium electrolyte of the present invention significantly reduces the preparation cost of the electrolyte, has low energy consumption, and reduces pollution.

Description

Technical Field

[0001] The present invention relates to the technical field of metallurgy, and in particular to a vanadium electrolyte and a preparation method and application thereof. Background Art

[0002] As one of the fastest-growing green and environmentally friendly storage batteries, vanadium batteries offer features such as adjustable energy storage capacity and power, high-current, lossless deep discharge, simple operation and maintenance, high safety, excellent reliability, long service life, and low pollution. These batteries offer unparalleled advantages over other batteries for large-scale energy storage. However, their application has been limited by cost. Vanadium electrolyte, the core energy storage module of vanadium batteries, accounts for 41% of the total cost of the battery. Therefore, controlling electrolyte production costs is key to promoting the industrialization and large-scale application of vanadium batteries.

[0003] Currently, the method for preparing vanadium electrolyte is to use ammonium metavanadate or vanadium pentoxide to prepare high-purity vanadium pentoxide, and then prepare the electrolyte by low-temperature dissolution reduction, electrolysis, high-temperature reduction dissolution and other methods of the high-purity vanadium pentoxide.

[0004] These methods involve complex and costly processes for preparing electrolytes. Furthermore, ammonium metavanadate or vanadium pentoxide, as raw materials, are also obtained from vanadium ore or vanadium waste through a series of complex metallurgical processes, resulting in high costs and making it difficult to control the cost of vanadium electrolytes. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a vanadium electrolyte and a preparation method and application thereof, so as to solve the technical problems of the complicated preparation process and high cost of the vanadium electrolyte in the prior art.

[0006] In order to solve the above technical problems, the technical solutions of the present invention are as follows:

[0007] A method for preparing a vanadium electrolyte, comprising:

[0008] (1) taking vanadium ore, adding sulfuric acid thereto, and mixing uniformly to obtain a mixture;

[0009] (2) aging the mixed material obtained in step (1) to obtain a aging material;

[0010] (3) leaching the slaking material obtained in step (2) with water to obtain a vanadium-containing leachate;

[0011] (4) adding a first impurity remover to the vanadium-containing leachate obtained in step (3) to obtain a first purified solution;

[0012] (5) adding an oxidant, ferric phosphate dihydrate seed crystals, and a second impurity remover to the first purified liquid obtained in step (4) to obtain a second purified liquid;

[0013] (6) adding a reducing agent and a flocculant to the second purified liquid obtained in step (5), filtering the liquid to obtain a filtrate;

[0014] (7) mixing the filtrate obtained in step (6) with the extract to extract and obtain a vanadium-loaded organic phase;

[0015] (8) stripping the vanadium-loaded organic phase obtained in step (7) to obtain a stripping solution;

[0016] (9) removing the organic phase from the stripping solution obtained in step (8) to obtain a vanadium electrolyte.

[0017] Preferably, in step (1), the sulfuric acid is a sulfuric acid solution with a mass concentration of 90-98%;

[0018] Optionally, in step (1), the mass ratio of the sulfuric acid to the vanadium ore is 1:(4-20).

[0019] Preferably, in step (1), when adding the sulfuric acid, the temperature of the mixture is 50-130°C. Preferably, the addition rate of the sulfuric acid is 0.05-10 mL·min -1 ·g -1 .

[0020] Optionally, in step (1), water is added before adding the sulfuric acid. Preferably, the mass ratio of water to the vanadium ore is (0.001-0.2):1.

[0021] Preferably, step (1) further comprises the step of crushing the vanadium ore. Preferably, the vanadium ore is crushed into powder with a particle size of less than 2 mm, and the mass of the vanadium ore with a particle size within the range of 1-2 mm accounts for more than 50%.

[0022] Preferably, in step (2), the aging temperature is 40-130° C. and the aging time is greater than 12 hours. Further preferably, the aging is carried out in a moisturizing environment.

[0023] Preferably, step (2) further comprises the step of crushing the slaked material. Preferably, the slaked material is crushed to a particle size of less than 5 mm.

[0024] Preferably, in step (3), the mass ratio of water to the slaking material is (0.5-5):1.

[0025] Preferably, in step (3), the leaching temperature is 10-90°C.

[0026] Preferably, in step (4), the pH value of the vanadium-containing leachate is first adjusted to 1.0-2.0, and then the first impurity remover is added;

[0027] Optionally, the first impurity remover is one or more of sodium fluoride, potassium fluoride, ammonium fluoride, lithium fluoride, hydrofluoric acid, sodium hexafluorophosphate, and potassium hexafluorophosphate.

[0028] Preferably, the molar ratio of the first impurity remover to the aluminum ions in the vanadium-containing leachate is (0.5-10):1.

[0029] Preferably, step (4) further comprises the step of filtering after adding the first impurity remover.

[0030] Preferably, in step (4), after adding the first impurity remover, the impurity removal reaction is carried out at 5-90°C.

[0031] Preferably, in step (4), the pH value of the vanadium-containing leachate obtained in step (3) is adjusted to 1.0-2.0, and the vanadium ore in step (1) is used. After adjusting the pH value to 1.0-2.0, the vanadium-containing leachate and wet ore are obtained by solid-liquid separation.

[0032] Preferably, in step (5), the oxidant is one or more of sodium chlorate, sodium hypochlorite, and hydrogen peroxide;

[0033] Optionally, the second impurity remover is one or more of phosphoric acid, sodium phosphate, disodium hydrogen phosphate, monosodium hydrogen phosphate, potassium phosphate, dipotassium hydrogen phosphate, monopotassium hydrogen phosphate, and ammonium hydrogen phosphate.

[0034] Preferably, the molar ratio of the oxidant to the ferrous ions in the first purification solution is (0.2-1):1.

[0035] Preferably, the molar ratio of the second impurity remover to the iron ions in the first purification liquid is (0.5-2):1.

[0036] Preferably, the molar ratio of the ferric phosphate dihydrate seed crystals to the iron ions in the first purified liquid is (0.01-0.2):1.

[0037] Preferably, step (5) further comprises the step of adjusting the pH value of the first purified liquid to 1.5-2.5 after adding the oxidant.

[0038] Preferably, step (5) further comprises the step of filtering the obtained reaction solution after adding the second impurity remover.

[0039] Preferably, in step (5), after adding the second impurity remover, the impurity removal reaction is carried out at 5-90°C.

[0040] Preferably, in step (6), the reducing agent is one or more of sulfite, sulfur dioxide, elemental sulfur, zinc powder, organic sulfur compound, oxalate, ascorbic acid, and carbon monoxide;

[0041] Optionally, the flocculant is one or more of polyacrylamide and sodium polyacrylate.

[0042] Preferably, the molar ratio of the reducing agent to the pentavalent vanadium ions in the second purification liquid is (1-3):1.

[0043] Preferably, the molar ratio of the flocculant to the vanadium ions in the second purified liquid is (0.01-0.1):1.

[0044] Preferably, step (6) further comprises the step of adjusting the pH value of the second purified liquid to 1.7-2.2 after adding the reducing agent.

[0045] Preferably, in step (6), after adding the flocculant, the reaction is stirred for 1-2 hours, and filtered using an ultrafiltration membrane to obtain a filtrate.

[0046] Preferably, in step (7), the extracting liquid is a mixture of an extractant, tributyl phosphate, and sulfonated kerosene; and the extractant is one or more of P204, N235, and P507. P204 refers to di(2-ethylhexyl)phosphate. N235 refers to trioctylamine. P507 refers to 2-ethylhexyl phosphate.

[0047] Preferably, the extract comprises a mixture of the following raw materials in parts by weight:

[0048] 10-25 parts of extractant;

[0049] 4-10 parts of tributyl phosphate;

[0050] 65-86 parts of sulfonated kerosene.

[0051] Preferably, in step (7), the volume ratio of the filtrate to the extract is 1:(0.2-1).

[0052] Preferably, step (8) specifically comprises: washing the vanadium-loaded organic phase obtained in step (7) with a sulfuric acid solution having a pH value of 1.5-2.0, and then stripping with a 1.5-2.5 mol / L sulfuric acid solution to obtain a stripping solution.

[0053] Preferably, in step (8), the volume ratio of the sulfuric acid solution with a pH value of 1.5-2.0 to the vanadium-loaded organic phase is (0.5-5):1.

[0054] Preferably, in step (8), the volume ratio of the 1.5-2.5 mol / L sulfuric acid solution to the vanadium-loaded organic phase is (0.05-0.6):1.

[0055] Preferably, step (9) specifically comprises: performing diffusion dialysis on the stripping solution to obtain a dialyzate; then, extracting and stripping the obtained dialyzate to obtain a secondary stripping solution; and then passing the secondary stripping solution through an activated carbon adsorption column to remove the organic phase to obtain a vanadium electrolyte.

[0056] Preferably, in step (9), the sulfuric acid solution is recovered by a diffusion dialysis membrane. In the diffusion dialysis, the flow rate of the stripping solution is 0.15-0.30×10 -3 m 3 / (h·m 2 ); the flow rate ratio of water to the stripping solution is (0.5-1.5):1.

[0057] Preferably, step (9) further comprises the step of adding water and / or sulfuric acid solution to the vanadium electrolyte to adjust the vanadium ion concentration in the vanadium electrolyte to 1.3-1.8 mol / L and the sulfate ion concentration to 4.0-4.5 mol / L. The mass concentration of the sulfuric acid solution is 90-98%.

[0058] The present invention also provides a vanadium electrolyte prepared by the vanadium electrolyte preparation method.

[0059] The present invention also provides an application of the vanadium electrolyte in the field of batteries.

[0060] The above solution of the present invention includes at least the following beneficial effects:

[0061] (1) The preparation method of the vanadium electrolyte of the present invention comprises: taking vanadium ore, adding sulfuric acid thereto, and mixing uniformly to obtain a mixture; slaking the mixture to obtain a slaking material; leaching the slaking material with water to obtain a vanadium-containing leachate; adding a first impurity remover to the vanadium-containing leachate to obtain a first purified liquid; adding an oxidant, dihydrate iron phosphate seeds, and a second impurity remover to the first purified liquid to obtain a second purified liquid; adding a reducing agent and a flocculant to the second purified liquid, and filtering to obtain a filtrate; mixing the filtrate with an extract to extract an organic phase loaded with vanadium; stripping the organic phase loaded with vanadium to obtain a stripping solution; removing the organic phase from the stripping solution to obtain a vanadium electrolyte. The preparation method of the vanadium electrolyte of the present invention not only greatly reduces the preparation cost of the electrolyte, has low energy consumption and low pollution, but also has a high purity of the prepared electrolyte product, controllable impurity ions in the electrolyte, stable quality, strong applicability, and can adapt to various electrolyte application environments.

[0062] (2) The method for preparing a vanadium electrolyte of the present invention, in steps (1) to (3), uses vanadium ore as a raw material to directly prepare a finished vanadium electrolyte, and uses a aging method to ensure that the valence of vanadium in the vanadium-containing leachate is mainly tetravalent, and the entire process basically maintains the valence of vanadium consistent with the valence of the final product of the vanadium electrolyte, thereby reducing the redox cost in the process;

[0063] (3) The preparation method of the vanadium electrolyte of the present invention uses vanadium ore as raw material to directly prepare the finished vanadium electrolyte. Since it does not involve the vanadium precipitation process, the entire process does not generate ammonia nitrogen wastewater. The amount of process wastewater that needs to be treated in the entire preparation method is relatively small, and only the raffinate needs to be treated. The raffinate can also be fully reused after impurity removal treatment, achieving "zero" emissions and low processing costs.

[0064] (4) The method for preparing a vanadium electrolyte of the present invention, in step (1), further comprises crushing the vanadium ore. The vanadium ore is crushed into a powder with a particle size of less than 2 mm, wherein the vanadium ore with a particle size within the range of 1-2 mm accounts for more than 50% by weight. By controlling the particle size of the vanadium ore, the grinding cost can be reduced, and selective leaching of vanadium from the vanadium ore can be achieved, thereby reducing impurities in the leachate and lowering the cost of subsequent impurity removal.

[0065] (5) In the method for preparing the vanadium electrolyte of the present invention, in step (1), when adding the sulfuric acid, the temperature of the mixture is 50-130°C. The addition rate of the sulfuric acid is 0.05-10 mL·min -1 ·g -1 By controlling the feeding speed of the sulfuric acid, the temperature of the mixture is heated to 50-130°C. Then, in the aging process of step (2), the heat required for aging can be ensured by heat preservation without external heat energy. The heat release property of the sulfuric acid when it is added is fully utilized, which not only ensures the required aging temperature but also greatly reduces energy consumption costs.

[0066] (6) In the method for preparing a vanadium electrolyte of the present invention, in step (4), the pH value of the vanadium-containing leachate obtained in step (3) is adjusted to 1.0-2.0, and the vanadium ore in step (1) is used. The vanadium ore is used to neutralize the acid in the vanadium-containing leachate. On the one hand, the acid-consuming substances in the vanadium ore are consumed in advance, thereby reducing the acid consumption required for aging. On the other hand, the vanadium ore is used to replace other neutralizing agents, thereby reducing not only the neutralization cost and vanadium loss, but also the amount of waste residue.

[0067] (7) In the method for preparing the vanadium electrolyte of the present invention, in steps (4) to (6), a chemical precipitation method is used to remove aluminum, iron, and magnesium before the extraction in step (7). This not only solves the problem of co-extraction of aluminum, iron, magnesium, and vanadium, but also can obtain cryolite and ferric phosphate, thereby realizing resource recycling.

[0068] (8) In the method for preparing a vanadium electrolyte of the present invention, in step (6), after adding the flocculant, stirring the reaction for 1-2 hours, and filtering with an ultrafiltration membrane to obtain a filtrate. The combination of the flocculant and the ultrafiltration membrane can effectively remove small particles and some anions in the solution. This not only achieves purification and impurity removal, but also reduces emulsification during the extraction process.

[0069] (9) The method for preparing a vanadium electrolyte of the present invention comprises the following steps: in step (9), the stripping solution is subjected to diffusion dialysis to obtain a dialysis solution; then, the obtained dialysis solution is subjected to extraction and stripping to obtain a secondary stripping solution; and the secondary stripping solution is passed through an activated carbon adsorption column to remove the organic phase to obtain a vanadium electrolyte. The sulfuric acid in the stripping solution is recovered by diffusion dialysis. On the one hand, the concentration of sulfuric acid in the stripping solution is relatively high. The alkali neutralization method consumes a large amount of alkali. Moreover, since the solution itself has been purified many times, its impurity content is not high. The alkali neutralization method will bring in impurity ions, increase the loss of vanadium, and generate a large amount of waste residue. The sulfuric acid in the stripping solution is recovered by diffusion dialysis at a low cost, without bringing in impurity ions, with a small loss of vanadium and without generating waste residue. On the other hand, the sulfuric acid solution recovered by diffusion dialysis can be directly returned to the process for use without treatment, which will greatly reduce the sulfuric acid consumption in the process.

[0070] (10) In the method for preparing a vanadium electrolyte of the present invention, in step (9), the dialyzate obtained is subjected to extraction and stripping to obtain a secondary stripping solution. The secondary extraction not only removes impurity ions but also enriches the vanadium ion concentration to ensure that the vanadium ion concentration reaches the concentration required for the vanadium electrolyte.

[0071] (11) In the vanadium electrolyte of the present invention, the impurity ion concentrations of iron, aluminum, magnesium, calcium, sodium, and potassium are no more than 30 mg / L, and the silicon ion concentration is no more than 5 mg / L. Other impurity ions meet the first-class requirements of the standard "GB / T 37204-2018 - Electrolyte for All-Vanadium Redox Flow Batteries". Some impurities are far below the first-class requirements of the standard "GB / T 37204-2018 - Electrolyte for All-Vanadium Redox Flow Batteries". In particular, the relatively difficult to remove impurities such as iron, aluminum, calcium, sodium, potassium, silicon, chromium, and molybdenum are far below the first-class requirements of the standard "GB / T 37204-2018 - Electrolyte for All-Vanadium Redox Flow Batteries". DETAILED DESCRIPTION

[0072] In the examples of the present invention, if specific conditions are not specified, the experiments were carried out under conventional conditions or the conditions recommended by the manufacturer. Reagents or instruments used without specifying the manufacturer are all commercially available conventional products. Raw materials of different manufacturers and types do not affect the implementation of the technical solutions of the present invention and the achievement of the technical effects.

[0073] Example 1

[0074] The method for preparing the vanadium electrolyte of this embodiment comprises:

[0075] (1) Take vanadium ore and crush it into powder with a particle size of less than 2 mm, with the mass of the vanadium ore within the range of 1-2 mm accounting for more than 50%; add water to the vanadium ore and then -1 ·g -1 adding a sulfuric acid solution having a mass concentration of 90% at a speed of 1000 nm to the mixture, mixing the mixture at 50° C. to obtain a mixture;

[0076] The mass ratio of the water to the vanadium ore is 0.1:1. The mass ratio of the sulfuric acid solution to the vanadium ore is 1:12.

[0077] (2) slaking the mixed material obtained in step (1) to obtain a slaking material, and crushing the slaking material to a particle size of less than 5 mm;

[0078] The aging is carried out in a moisturizing environment, the aging temperature is 40° C., and the aging time is greater than 12 hours.

[0079] (3) leaching the slaking material obtained in step (2) with water at 10° C. to obtain a vanadium-containing leachate;

[0080] The mass ratio of water to the slaking material is 0.5:1. The vanadium-containing leachate can be obtained by solid-liquid separation. After solid-liquid separation, the vanadium-containing leachate and leach residue are obtained.

[0081] (4) first adjusting the pH value of the vanadium-containing leachate obtained in step (3) to 1.0, then adding a first impurity remover to the vanadium-containing leachate, performing an impurity removal reaction at 5° C., and filtering the reaction solution to obtain a first purified solution;

[0082] The first impurity remover is a mixture of sodium fluoride and ammonium fluoride in a weight ratio of 30:8. The molar ratio of the first impurity remover to the aluminum ions in the vanadium-containing leachate is 0.5:1. The aluminum ions are removed by the first impurity remover to obtain cryolite, i.e., sodium hexafluoroaluminate.

[0083] As a preferred implementation of this embodiment, the pH value of the vanadium-containing leachate obtained in step (3) is adjusted to 1.0, and the vanadium ore in step (1) is used. After adjusting the pH value to 1.0, solid-liquid separation is performed to obtain the vanadium-containing leachate and wet ore. It should be noted that as an alternative implementation of this embodiment, the pH value of the vanadium-containing leachate obtained in step (3) can also be adjusted to 1.0 using chemical reagents.

[0084] In order to fully utilize resources, the vanadium ore in step (1) may also be mixed with the wet ore produced in step (4).

[0085] (5) adding an oxidant to the first purified liquid obtained in step (4), adjusting the pH value of the first purified liquid to 2.5, adding ferric phosphate dihydrate seed crystals and a second impurity remover thereto, performing an impurity removal reaction at 5° C., and filtering the obtained reaction liquid to obtain a second purified liquid;

[0086] Wherein, the oxidant is sodium chlorate; and the molar ratio of the oxidant to the ferrous ions in the first purification liquid is 0.6:1.

[0087] The second impurity remover is sodium phosphate. The molar ratio of the second impurity remover to the iron ions in the first purified solution is 2:1. The iron ions are removed by the second impurity remover to obtain iron phosphate.

[0088] The molar ratio of the ferric phosphate dihydrate seed crystals to the iron ions in the first purified liquid is 0.1:1.

[0089] (6) adding a reducing agent to the second purified liquid obtained in step (5) to reduce the pentavalent vanadium in the second purified liquid to tetravalent vanadium, adjusting the pH value of the second purified liquid to 2.2, adding a flocculant thereto, stirring the reaction for 2 hours, and filtering with an ultrafiltration membrane to obtain a filtrate;

[0090] Wherein, the reducing agent is sodium sulfite; and the molar ratio of the reducing agent to the pentavalent vanadium ions in the second purification liquid is 3:1.

[0091] The flocculant is polyacrylamide, and the molar ratio of the flocculant to the vanadium ions in the second purified liquid is 0.01:1.

[0092] (7) mixing the filtrate obtained in step (6) with the extract to extract and obtain a vanadium-loaded organic phase;

[0093] It should be noted that raffinate is also produced during extraction. To fully utilize resources, the water after neutralization and impurity removal can be used as the water used for leaching in step (3) or the water added to the vanadium ore in step (1).

[0094] The extract comprises the following raw materials by weight: 25 parts extractant, 4 parts tributyl phosphate, and 65 parts sulfonated kerosene. The extractant is a mixture of P204 and P507 in a weight ratio of 1:9. The volume ratio of the filtrate to the extract is 1:0.5.

[0095] (8) The vanadium-loaded organic phase obtained in step (7) is washed with a sulfuric acid solution having a pH value of 1.5, and then stripped with a 2.0 mol / L sulfuric acid solution to obtain a stripping solution.

[0096] The volume ratio of the sulfuric acid solution with a pH value of 1.5 to the vanadium-loaded organic phase is 0.5:1.

[0097] The volume ratio of the 2.0 mol / L sulfuric acid solution to the vanadium-loaded organic phase is 0.3:1.

[0098] In order to fully utilize resources, the water used for washing with the sulfuric acid solution can be used as the water for leaching in step (3).

[0099] (9) The stripping solution obtained in step (8) is subjected to diffusion dialysis, and the sulfuric acid solution is recovered through a diffusion dialysis membrane to obtain a dialyzate; then, the obtained dialyzate is subjected to extraction and stripping to obtain a secondary stripping solution; and the secondary stripping solution is passed through an activated carbon adsorption column to remove the organic phase to obtain a vanadium electrolyte.

[0100] To obtain a vanadium electrolyte with an appropriate concentration, water and / or sulfuric acid solution may be added to the vanadium electrolyte to adjust the vanadium ion concentration to 1.8 mol / L and the sulfate ion concentration to 4.5 mol / L. The mass concentration of the sulfuric acid solution is 98%.

[0101] Wherein, in the diffusion dialysis, the flow rate of the stripping solution is 0.30×10 -3 m 3 / (h·m 2 ); the flow rate ratio of water to the stripping solution is 1:1. In this embodiment, the extraction and stripping to obtain the secondary stripping solution can be carried out in the same manner as steps (7) and (8), or other reagents can be selected for extraction and stripping according to actual conditions.

[0102] In order to fully utilize resources, the sulfuric acid solution recovered by the diffusion dialysis membrane can be used for the water or sulfuric acid solution added in step (1).

[0103] Example 2

[0104] The method for preparing the vanadium electrolyte of this embodiment comprises:

[0105] (1) Take vanadium ore and crush it into powder with a particle size of less than 2 mm, with the mass of the vanadium ore within the range of 1-2 mm accounting for more than 50%; add water to the vanadium ore and then -1 ·g -1 adding a sulfuric acid solution having a mass concentration of 94% at a speed of 1000 rpm, mixing uniformly at 130° C., and obtaining a mixture;

[0106] The mass ratio of the water to the vanadium ore is 0.2:1. The mass ratio of the sulfuric acid solution to the vanadium ore is 1:4.

[0107] (2) slaking the mixed material obtained in step (1) to obtain a slaking material, and crushing the slaking material to a particle size of less than 5 mm;

[0108] The aging is carried out in a moisturizing environment, the aging temperature is 130° C., and the aging time is greater than 12 hours.

[0109] (3) leaching the slaked material obtained in step (2) with water at 50° C. to obtain a vanadium-containing leachate;

[0110] The mass ratio of water to the slaking material is 5:1. The vanadium-containing leachate can be obtained by solid-liquid separation. After solid-liquid separation, the vanadium-containing leachate and leach residue are obtained.

[0111] (4) first adjusting the pH value of the vanadium-containing leachate obtained in step (3) to 1.5, then adding a first impurity remover to the vanadium-containing leachate, performing an impurity removal reaction at 90° C., and filtering the reaction solution to obtain a first purified solution;

[0112] The first impurity remover is potassium fluoride. As an alternative to this embodiment, the first impurity remover can also be one or more of ammonium fluoride, lithium fluoride, hydrofluoric acid, sodium hexafluorophosphate, and potassium hexafluorophosphate. The molar ratio of the first impurity remover to the aluminum ions in the vanadium-containing leachate is 5:1. The aluminum ions are removed by the first impurity remover to produce cryolite, i.e., sodium hexafluoroaluminate.

[0113] As a preferred implementation of this embodiment, the pH value of the vanadium-containing leachate obtained in step (3) is adjusted to 1.5, and the vanadium ore in step (1) is used. After adjusting the pH value to 1.5, solid-liquid separation is performed to obtain the vanadium-containing leachate and wet ore. It should be noted that as an alternative implementation of this embodiment, the pH value of the vanadium-containing leachate obtained in step (3) can also be adjusted to 1.5 using chemical reagents.

[0114] In order to fully utilize resources, the vanadium ore in step (1) may also be mixed with the wet ore produced in step (4).

[0115] (6) adding an oxidant to the first purified liquid obtained in step (4), adjusting the pH value of the first purified liquid to 2.0, adding ferric phosphate dihydrate seed crystals and a second impurity remover thereto, performing an impurity removal reaction at 90° C., and filtering the obtained reaction liquid to obtain a second purified liquid;

[0116] Wherein, the oxidant is sodium hypochlorite; and the molar ratio of the oxidant to the ferrous ions in the first purification liquid is 0.2:1.

[0117] The second impurity remover is phosphoric acid. As an alternative implementation of this embodiment, the second impurity remover can also be one or more of sodium phosphate, disodium hydrogen phosphate, monosodium hydrogen phosphate, potassium phosphate, dipotassium hydrogen phosphate, monopotassium hydrogen phosphate, and ammonium hydrogen phosphate. The molar ratio of the second impurity remover to the iron ions in the first purified solution is 1.2:1. The second impurity remover removes the iron ions to produce iron phosphate.

[0118] The molar ratio of the ferric phosphate dihydrate seed crystals to the iron ions in the first purified liquid is 0.2:1.

[0119] (6) adding a reducing agent to the second purified liquid obtained in step (5) to reduce the pentavalent vanadium in the second purified liquid to tetravalent vanadium, adjusting the pH value of the second purified liquid to 1.7, adding a flocculant thereto, stirring the reaction for 2 hours, and filtering with an ultrafiltration membrane to obtain a filtrate;

[0120] The reducing agent is sulfur dioxide. As an alternative implementation of this embodiment, the reducing agent may also be one or more of elemental sulfur, zinc powder, an organic sulfur compound, an oxalate, ascorbic acid, and carbon monoxide; and the molar ratio of the reducing agent to the pentavalent vanadium ions in the second purification liquid is 1:1.

[0121] The flocculant is sodium polyacrylate, and the molar ratio of the flocculant to the vanadium ions in the second purified liquid is 0.1:1.

[0122] (7) mixing the filtrate obtained in step (6) with the extract to extract and obtain a vanadium-loaded organic phase;

[0123] It should be noted that raffinate is also produced during extraction. To fully utilize resources, the water after neutralization and impurity removal can be used as the water used for leaching in step (3) or the water added to the vanadium ore in step (1).

[0124] The extract comprises the following raw materials in parts by weight: 18 parts of an extractant, 7 parts of tributyl phosphate, and 86 parts of sulfonated kerosene. The extractant is N235. The volume ratio of the filtrate to the extract is 1:0.2.

[0125] (8) The vanadium-loaded organic phase obtained in step (7) is washed with a sulfuric acid solution having a pH value of 2.0, and then stripped with a 2.5 mol / L sulfuric acid solution to obtain a stripping solution.

[0126] The volume ratio of the sulfuric acid solution with a pH value of 2.0 to the vanadium-loaded organic phase is 5:1.

[0127] The volume ratio of the 2.5 mol / L sulfuric acid solution to the vanadium-loaded organic phase is 0.05:1.

[0128] In order to fully utilize resources, the water used for washing with the sulfuric acid solution can be used as the water for leaching in step (3).

[0129] (9) The stripping solution obtained in step (8) is subjected to diffusion dialysis, and the sulfuric acid solution is recovered through a diffusion dialysis membrane to obtain a dialyzate; then, the obtained dialyzate is subjected to extraction and stripping to obtain a secondary stripping solution; and the secondary stripping solution is passed through an activated carbon adsorption column to remove the organic phase to obtain a vanadium electrolyte.

[0130] To obtain a vanadium electrolyte with an appropriate concentration, water and / or sulfuric acid solution may be added to the vanadium electrolyte to adjust the vanadium ion concentration to 1.3 mol / L and the sulfate ion concentration to 4.2 mol / L. The mass concentration of the sulfuric acid solution is 94%.

[0131] Wherein, in the diffusion dialysis, the flow rate of the stripping solution is 0.15×10 -3 m 3 / (h·m 2 ); the flow rate ratio of water to the stripping solution is 0.5:1.

[0132] In order to fully utilize resources, the sulfuric acid solution recovered by the diffusion dialysis membrane can be used for the water or sulfuric acid solution added in step (1).

[0133] Example 3

[0134] The method for preparing the vanadium electrolyte of this embodiment comprises:

[0135] (1) Take vanadium ore and crush it into powder with a particle size of less than 2 mm, with the mass of the vanadium ore within the range of 1-2 mm accounting for more than 50%; add water to the vanadium ore and then -1 ·g -1 adding a sulfuric acid solution having a mass concentration of 98% at a speed of 1000 nm to the mixture, mixing the mixture at 90° C. to obtain a mixture;

[0136] The mass ratio of the water to the vanadium ore is 0.1:1. The mass ratio of the sulfuric acid solution to the vanadium ore is 1:20.

[0137] (2) slaking the mixed material obtained in step (1) to obtain a slaking material, and crushing the slaking material to a particle size of less than 5 mm;

[0138] The aging is carried out in a moisturizing environment, the aging temperature is 85° C., and the aging time is greater than 12 hours.

[0139] (3) leaching the slaking material obtained in step (2) with water at 90° C. to obtain a vanadium-containing leachate;

[0140] The mass ratio of water to the slaking material is 2.5:1. The vanadium-containing leachate can be obtained by solid-liquid separation. After solid-liquid separation, the vanadium-containing leachate and leach residue are obtained.

[0141] (4) first adjusting the pH value of the vanadium-containing leachate obtained in step (3) to 2.0, then adding a first impurity remover to the vanadium-containing leachate, performing an impurity removal reaction at 47° C., and filtering the reaction solution to obtain a first purified solution;

[0142] The first impurity remover is sodium hexafluorophosphate. The molar ratio of the first impurity remover to the aluminum ions in the vanadium-containing leachate is 10:1. The aluminum ions are removed by the first impurity remover to obtain cryolite, i.e., sodium hexafluoroaluminate.

[0143] As a preferred implementation of this embodiment, the pH value of the vanadium-containing leachate obtained in step (3) is adjusted to 2.0, and the vanadium ore in step (1) is used. After adjusting the pH value to 2.0, solid-liquid separation is performed to obtain the vanadium-containing leachate and wet ore. It should be noted that as an alternative implementation of this embodiment, the pH value of the vanadium-containing leachate obtained in step (3) can also be adjusted to 2.0 using chemical reagents.

[0144] In order to fully utilize resources, the vanadium ore in step (1) may also be mixed with the wet ore produced in step (4).

[0145] (7) adding an oxidant to the first purified liquid obtained in step (4), adjusting the pH value of the first purified liquid to 1.5, adding ferric phosphate dihydrate seed crystals and a second impurity remover thereto, performing an impurity removal reaction at 45° C., and filtering the obtained reaction liquid to obtain a second purified liquid;

[0146] Wherein, the oxidant is hydrogen peroxide; the molar ratio of the oxidant to the ferrous ions in the first purification liquid is 1:1.

[0147] The second impurity remover is potassium phosphate. The molar ratio of the second impurity remover to the iron ions in the first purified solution is 0.5:1. The iron ions are removed by the second impurity remover to obtain iron phosphate.

[0148] The molar ratio of the ferric phosphate dihydrate seed crystals to the iron ions in the first purified liquid is 0.01:1.

[0149] (6) adding a reducing agent to the second purified liquid obtained in step (5) to reduce the pentavalent vanadium in the second purified liquid to tetravalent vanadium, adjusting the pH value of the second purified liquid to 2.0, adding a flocculant thereto, stirring the reaction for 1 hour, and filtering with an ultrafiltration membrane to obtain a filtrate;

[0150] The reducing agent is a mixture of elemental sulfur and zinc powder in a weight ratio of 1:1; and the molar ratio of the reducing agent to the pentavalent vanadium ions in the second purified liquid is 2:1.

[0151] The flocculant is polyacrylamide, and the molar ratio of the flocculant to the vanadium ions in the second purified liquid is 0.05:1.

[0152] (7) mixing the filtrate obtained in step (6) with the extract to extract and obtain a vanadium-loaded organic phase;

[0153] It should be noted that raffinate is also produced during extraction. To fully utilize resources, the water after neutralization and impurity removal can be used as the water used for leaching in step (3) or the water added to the vanadium ore in step (1).

[0154] The extract comprises the following raw materials by weight: 10 parts extractant, 10 parts tributyl phosphate, and 76 parts sulfonated kerosene. The extractant is a mixture of P204, N235, and P507 in a weight ratio of 1:3:1. The volume ratio of the filtrate to the extract is 1:1.

[0155] (8) The vanadium-loaded organic phase obtained in step (7) is washed with a sulfuric acid solution having a pH value of 1.8, and then stripped with a 1.5 mol / L sulfuric acid solution to obtain a stripping solution.

[0156] The volume ratio of the sulfuric acid solution with a pH value of 1.8 to the vanadium-loaded organic phase is 2.7:1.

[0157] The volume ratio of the 1.5 mol / L sulfuric acid solution to the vanadium-loaded organic phase is 0.6:1.

[0158] In order to fully utilize resources, the water used for washing with the sulfuric acid solution can be used as the water for leaching in step (3).

[0159] (9) The stripping solution obtained in step (8) is subjected to diffusion dialysis, and the sulfuric acid solution is recovered through a diffusion dialysis membrane to obtain a dialyzate; then, the obtained dialyzate is subjected to extraction and stripping to obtain a secondary stripping solution; and the secondary stripping solution is passed through an activated carbon adsorption column to remove the organic phase to obtain a vanadium electrolyte.

[0160] To obtain a vanadium electrolyte with an appropriate concentration, water and / or sulfuric acid solution may be added to the vanadium electrolyte to adjust the vanadium ion concentration to 1.5 mol / L and the sulfate ion concentration to 4.0 mol / L. The mass concentration of the sulfuric acid solution is 90%.

[0161] Wherein, in the diffusion dialysis, the flow rate of the stripping solution is 0.22×10 -3 m 3 / (h·m 2 ); the flow rate ratio of water to the stripping solution is 1.5:1.

[0162] In order to fully utilize resources, the sulfuric acid solution recovered by the diffusion dialysis membrane can be used for the water or sulfuric acid solution added in step (1).

[0163] Example 4

[0164] This embodiment adopts the same method for preparing the vanadium electrolyte as that of Example 1, with the only difference being that in step (9), no secondary extraction or back extraction is performed.

[0165] In this embodiment, step (9) specifically comprises: performing diffusion dialysis on the stripping solution obtained in step (8), recovering the sulfuric acid solution through a diffusion dialysis membrane, and obtaining a dialyzate; then, removing the organic phase from the obtained dialyzate through an activated carbon adsorption column to obtain a vanadium electrolyte.

[0166] Example 5

[0167] This embodiment adopts the same method for preparing the vanadium electrolyte as that of Example 1, with the only difference being that the vanadium ore in step (1) is mixed with the wet ore produced in step (4) to form a vanadium ore mixture; and the mass ratio of the water to the vanadium ore and the mass ratio of the sulfuric acid to the vanadium ore mixture are changed.

[0168] In this embodiment, step (1) specifically comprises: taking vanadium ore, crushing the vanadium ore into powder with a particle size of less than 2 mm, wherein the mass of the vanadium ore with a particle size within the range of 1-2 mm accounts for more than 50%; mixing the crushed vanadium ore with the wet ore produced in step (4) at a mass ratio of 1:2.5 to obtain a vanadium ore mixture; adding water to the vanadium ore mixture, and then stirring at 0.05 mL·min -1 ·g -1 adding a sulfuric acid solution having a mass concentration of 90% at a speed of 1000 nm to the mixture, mixing the mixture at 50° C. to obtain a mixture;

[0169] The mass ratio of the water to the vanadium ore mixture is 0.001:1. The mass ratio of the sulfuric acid solution to the vanadium ore mixture is 1:13.

[0170] Example 6

[0171] This embodiment adopts the same method for preparing a vanadium electrolyte as that of Example 1, with the only difference being that the vanadium ore in step (1) is further mixed with the wet ore produced in step (4) to form a vanadium ore mixture; at the same time, the added water is replaced with the sulfuric acid solution recovered by the countercurrent diffusion dialysis membrane in step (9), and the mass ratio of the sulfuric acid solution with a mass concentration of 90% to the vanadium ore is changed.

[0172] In this embodiment, step (1) specifically comprises: taking vanadium ore, crushing the vanadium ore into powder with a particle size of less than 2 mm, wherein the mass of the vanadium ore with a particle size within the range of 1-2 mm accounts for more than 50%; mixing the crushed vanadium ore with the wet ore produced in step (4) at a mass ratio of 1:0.6 to obtain a vanadium ore mixture; adding the sulfuric acid solution recovered by the countercurrent diffusion dialysis membrane in step (9) to the vanadium ore mixture, and then dialysis at a rate of 0.05 mL·min -1 ·g -1 adding a sulfuric acid solution having a mass concentration of 90% at a speed of 1000 nm to the mixture, mixing the mixture at 50° C. to obtain a mixture;

[0173] The sulfuric acid solution recovered by the countercurrent diffusion dialysis membrane has a concentration of 1.1 mol / L and a mass ratio of 0.04:1 to the vanadium ore mixture. The mass ratio of the sulfuric acid solution with a mass concentration of 90% to the vanadium ore mixture is 1:14.

[0174] Adding the sulfuric acid solution recovered by the countercurrent diffusion dialysis membrane in step (9) can, on the one hand, replace the step of adding water, and on the other hand, can also reduce the amount of sulfuric acid solution with a mass concentration of 90%.

[0175] Effect comparison ratio

[0176] In order to verify the technical effect of the method for preparing the vanadium electrolyte of the present invention, the following experiments were conducted:

[0177] The vanadium electrolytes obtained in Examples 1-4 and Comparative Examples 1-3 were tested according to the method specified in GB / T 37204-2018 "Electrolyte for All-Vanadium Redox Flow Batteries" to determine the composition of the vanadium electrolytes.

[0178] After experimentation, the results are as follows:

[0179]

[0180]

[0181]

[0182]

[0183]

[0184]

[0185]

[0186]

[0187] In the above examples, Example 4 demonstrates that, if only a single extraction is performed, some impurity ions in the electrolyte will hardly meet the requirements of the GB / T 37204-2018 "Electrolyte for All-Vanadium Redox Flow Batteries" standard. However, the impurity ions in the remaining examples all met the first-grade requirements of the GB / T 37204-2018 "Electrolyte for All-Vanadium Redox Flow Batteries" standard, with no significant differences. In Examples 5-6, while meeting the first-grade requirements of the GB / T 37204-2018 "Electrolyte for All-Vanadium Redox Flow Batteries" standard, the amounts of acid and water used for aging were reduced to a certain extent. Compared to Example 1, the amount of the 90% mass concentration sulfuric acid solution used was significantly reduced, thereby achieving better resource utilization.

[0188] It is understood from common technical knowledge that the present invention may be implemented by other embodiments that do not depart from its spirit or essential features. Therefore, the embodiments disclosed above are, in all respects, merely illustrative and not exclusive. All modifications within the scope of the present invention or equivalent to the scope of the present invention are intended to be encompassed by the present invention.

Claims

1. A method for preparing a vanadium electrolyte, characterized in that: include: (1) taking vanadium ore, adding sulfuric acid with a mass concentration of 90-98% thereto, and mixing uniformly to obtain a mixture; (2) aging the mixed material obtained in step (1) to obtain a aging material; (3) leaching the slaked material obtained in step (2) with water to obtain a vanadium-containing leachate; (4) using the vanadium ore of step (1) to adjust the pH value of the vanadium-containing leachate obtained in step (3) to 1.0-2.0, and then adding a first impurity remover to obtain a first purified liquid; the first impurity remover is one or more of sodium fluoride, potassium fluoride, ammonium fluoride, lithium fluoride, hydrofluoric acid, sodium hexafluorophosphate, and potassium hexafluorophosphate; (5) adding an oxidant, ferric phosphate dihydrate seed crystals, and a second impurity remover to the first purified liquid obtained in step (4); obtaining a second purified liquid; The oxidant is one or more of sodium chlorate, sodium hypochlorite, and hydrogen peroxide; The second impurity remover is one or more of phosphoric acid, sodium phosphate, disodium hydrogen phosphate, monosodium hydrogen phosphate, potassium phosphate, dipotassium hydrogen phosphate, monopotassium hydrogen phosphate, and ammonium hydrogen phosphate; (6) adding a reducing agent and a flocculant to the second purified liquid obtained in step (5), and filtering to obtain a filtrate; The reducing agent is one or more of sulfite, sulfur dioxide, elemental sulfur, zinc powder, organic sulfur compound, oxalate, ascorbic acid, and carbon monoxide; The flocculant is one or more of polyacrylamide and sodium polyacrylate; (7) mixing the filtrate obtained in step (6) with the extract to extract and obtain a vanadium-loaded organic phase; (8) stripping the vanadium-loaded organic phase obtained in step (7) to obtain a stripping solution; (9) removing the organic phase from the stripping solution obtained in step (8) to obtain a vanadium electrolyte; Step (9) specifically comprises: performing diffusion dialysis on the stripping solution, recovering the sulfuric acid solution through a diffusion dialysis membrane, and obtaining a dialyzate; Then, the obtained dialyzate is subjected to extraction and stripping to obtain a secondary stripping solution; and the secondary stripping solution is passed through an activated carbon adsorption column to remove an organic phase to obtain a vanadium electrolyte.

2. The method for preparing a vanadium electrolyte according to claim 1, wherein: The mass ratio of the sulfuric acid to the vanadium ore in step (1) is 1: (4-20).

3. The method for preparing a vanadium electrolyte according to claim 1, wherein: Before adding the sulfuric acid in step (1), water is added.

4. The method for preparing a vanadium electrolyte according to claim 1, wherein: In step (2), the aging temperature is 40-130° C. and the time is greater than 12 hours.

5. The method for preparing a vanadium electrolyte according to claim 1, wherein: In step (7), the extracting liquid is a mixture of an extracting agent, tributyl phosphate, and sulfonated kerosene; the extracting agent is one or more of P204, N235, and P507.

Images