A method for preparing a vanadium electrolyte

Abstract

The present application belongs to the technical field of all-vanadium redox flow battery, and relates to a preparation method of vanadium electrolyte, comprising: using vanadium molybdate solution as raw material, realizing extraction of vanadium and molybdenum elements in solution in sequence and recovery based on pH value adjustment of the solution; the composition of the extraction organic phase used for extraction of vanadium and molybdenum elements is the same; and the vanadium product recovered is purified to prepare vanadium electrolyte. The present application solves the problems in the prior art, such as difficulty in realizing simultaneous recovery of various vanadium and molybdenum elements, difficulty in recycling vanadium element, low vanadium recovery rate, low purity of recovered product, serious environmental pollution, high requirement for purity of vanadium raw material, complex preparation process steps of vanadium raw material purification, and difficulty in separating high-purity vanadium from vanadium-molybdenum homologous materials, and the like, greatly simplifies the vanadium purification process compared with the prior art, greatly expands the source of vanadium, reduces the cost and dependence on vanadium pentoxide.

Description

Technical Field

[0001] This invention relates to the field of vanadium redox flow battery technology, and more particularly to a method for preparing vanadium electrolyte. Background Technology

[0002] Vanadium redox flow batteries have seen rapid development in recent years due to their advantages such as high energy storage capacity, high cycle life, long service life, simple operation, safety, environmental friendliness, and low cost. Vanadium electrolyte is a crucial component of vanadium redox flow batteries, and its production cost largely determines the overall production cost. Therefore, reducing the cost of vanadium electrolyte preparation is a pressing issue that needs to be addressed for the widespread adoption and application of vanadium redox flow batteries.

[0003] Currently, the most common vanadium electrolyte preparation technologies are chemical reduction and electrolysis, with V2O5 as the vanadium raw material. On the one hand, this means that the price of vanadium electrolyte in vanadium redox flow batteries is greatly affected by fluctuations in the price of vanadium (V2O5). V2O5 is mostly prepared by leaching, separation, and precipitation of vanadium ore, which is a complex process with high production costs. On the other hand, molybdenum is a common associated element with similar chemical properties to vanadium. Leaching is a common method for processing vanadium ore, and the leachate contains both vanadium and molybdenum. Therefore, it is quite difficult to prepare vanadium electrolyte from vanadium ore through a short-process purification process.

[0004] In addition, vanadium molybdate solutions, represented by vanadium-molybdenum ore leaching solutions, are common waste liquids or industrial products. For example, they can also be solid waste treatment liquids containing molybdenum and vanadium. Since vanadium and molybdenum have similar chemical properties, how to effectively separate and extract molybdenum and vanadium and effectively recover and utilize vanadium has always been a difficult problem for the utilization of vanadium in vanadium molybdate solutions.

[0005] Existing technologies commonly use ammonium salt precipitation, sulfidation, ion exchange, and solvent extraction to separate vanadium and molybdenum. Ammonium salt precipitation involves using ammonium salts to precipitate vanadium as ammonium metavanadate under controlled experimental conditions, thus achieving vanadium-molybdenum separation. However, this method cannot deeply precipitate vanadium, resulting in generally poor separation and purification, and requires large amounts of ammonium salt. Ion exchange is complex, generates large amounts of acid and alkaline wastewater, and has limited resin adsorption capacity. Existing solvent extraction methods also suffer from lengthy processes, incomplete vanadium-molybdenum separation, and insufficient product quality. Existing technologies present significant challenges in separating vanadium from vanadium-molybdenum homologous materials (such as vanadium-molybdate solutions) and preparing vanadium battery electrolytes. Summary of the Invention

[0006] In view of the above analysis, the present invention aims to provide a method for preparing vanadium electrolyte to solve at least one of the following problems in the prior art: difficulty in simultaneously recovering various vanadium and molybdenum elements, difficulty in recovering and utilizing vanadium elements, low vanadium recovery rate, low purity of recovered products, large environmental pollution, high requirements for the purity of vanadium raw materials, complex purification and preparation process of vanadium raw materials, and difficulty in separating vanadium from vanadium-molybdenum homologous materials.

[0007] The objective of this invention is mainly achieved through the following technical solutions:

[0008] This invention discloses a method for preparing a vanadium electrolyte, comprising:

[0009] Using vanadium molybdate solution as raw material, the extraction organic phase is used to sequentially extract and recover vanadium and molybdenum elements from the solution based on pH adjustment. The composition of the extraction organic phase is the same for vanadium and molybdenum element extraction.

[0010] The recovered vanadium products are purified to prepare vanadium electrolyte.

[0011] Preferably, the method for preparing the vanadium electrolyte includes:

[0012] S1. Adjust the vanadium molybdate solution to alkaline, and use the extraction organic phase to extract the vanadium molybdate solution to obtain a vanadium-rich organic phase and a molybdenum-rich raffinate.

[0013] S2. Adjust the molybdenum-rich raffinate to acidity, and use an extractive organic phase to extract the molybdenum-rich raffinate to obtain a molybdenum-rich organic phase and raffinate.

[0014] S3. The vanadium-rich organic phase and the molybdenum-rich organic phase are back-extracted independently to obtain vanadium-rich back-extracting solution and molybdenum-rich back-extracting solution;

[0015] S4. Prepare molybdenum products from molybdenum-rich back-extraction solution; further prepare vanadium products or vanadium electrolyte products from vanadium-rich back-extraction solution.

[0016] Preferably, the reaction agent for the vanadium-rich organic back-extraction in S3 is an alkaline sulfate aqueous solution with a pH value > 11 or a sulfuric acid solution with a pH value < 1, and / or, the vanadium product is a vanadium-rich back-extraction solution, a vanadium product, or a vanadium oxysulfate back-extraction solution.

[0017] Preferably, the reaction agent for the vanadium-rich organic back-extraction in S3 is a sulfuric acid solution with a pH value <1, and a gaseous reducing agent is introduced simultaneously with the back-extraction to obtain a vanadium oxysulfate back-extraction solution.

[0018] Preferably, the gaseous reducing agent is SO2, and the SO2 gas flow rate is 1 to 1.5 times the theoretical consumption; and / or, the O / A ratio in the back-extraction phase of S3 is 5 to 10 / 1.

[0019] Preferably, the vanadium-rich organic back-extraction agent in S3 is an alkaline sulfate aqueous solution with a pH value > 11, to obtain a vanadium-rich back-extraction solution or to further prepare a vanadium product from the vanadium-rich back-extraction solution. A reducing agent B is added to the solution of the vanadium-rich back-extraction solution or the vanadium product to obtain a vanadium oxysulfate reducing solution.

[0020] Preferably, reducing agent B is one or more of sodium sulfide, sodium sulfite, sodium thiosulfate, sodium metabisulfite, sulfur dioxide, ascorbic acid, sodium nitrite, and oxalic acid reducing agent.

[0021] Preferably, the amount of reducing agent B added is 1 to 1.5 times the theoretical consumption.

[0022] Preferably, the purification process includes: pretreatment, extraction, washing, back-extraction, and regeneration.

[0023] The present invention also discloses a vanadium electrolyte prepared by the above preparation method, wherein the purity of the vanadium electrolyte product is ≥99.99%.

[0024] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0025] (1) This invention achieves the extraction and separation of vanadium from molybdate by adjusting the pH value in the vanadium molybdate solution and utilizing the selective change of vanadium and molybdenum elements in the extracting organic phase; and further prepares vanadium oxysulfate and vanadium electrolyte products that meet the requirements for vanadium electrolyte preparation and are superior to national standards through reduction and secondary purification. This invention realizes the separation and purification of vanadium from common industrial products or intermediate processing products vanadium-molybdenum mixed solutions and the preparation of vanadium electrolyte. Compared with the prior art, this invention greatly simplifies the vanadium purification process, greatly expands the sources of vanadium, and reduces costs and dependence on vanadium pentoxide.

[0026] (2) This invention achieves selective changes in vanadium and molybdenum elements by adjusting the pH value in the vanadium molybdate solution. While ensuring the extraction and separation effect, it realizes the sequential extraction and recovery of vanadium and molybdenum elements in the solution. This overcomes the defects of low yield and low product purity caused by poor separation effect of each element in the vanadium molybdate solution in the existing technology. It achieves a vanadium recovery rate of ≥99.5%, and a vanadium mass fraction of ≥99.5% in the vanadium product after evaporation, concentration and crystallization; a molybdenum recovery rate of ≥99.5%, and a molybdenum mass fraction of ≥99.5% in the molybdenum product after evaporation, concentration and crystallization; at the same time, it improves the post-processing process of the recovered vanadium product and realizes the preparation of high-purity vanadium battery electrolyte (vanadium electrolyte product purity of ≥99.99%, and the content of major impurities is below 10mg / L).

[0027] (3) The present invention uses the reflux of the raffinate to prepare a vanadium molybdate solution. On the one hand, it avoids the waste of vanadium and molybdenum elements and improves the yield of vanadium and molybdenum elements; on the other hand, it achieves the enrichment of a variety of precious metal elements during the reflux of the raffinate, which facilitates the recovery of precious metal elements; at the same time, it reduces waste liquid discharge, environmental pollution and cost.

[0028] (4) This invention uses the same extraction organic phase to achieve extraction of two elements, avoiding pollution caused by the residual extraction phase in the raffinate when different elements use different extraction systems; at the same time, since the extraction organic phase is the same, the organic phase after back-extraction can be recycled and reused without worrying about mutual contamination of the extraction systems, thus reducing waste liquid discharge and environmental pollution.

[0029] (5) By controlling the pH value during washing the extraction phase, the present invention removes impurities while reducing the elution of vanadium and molybdenum during washing, thereby improving the yield of both elements.

[0030] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained through the embodiments described and the accompanying drawings. Attached Figure Description

[0031] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0032] Figure 1 This is a process flow diagram of the present invention for separating and purifying vanadium from vanadium molybdate solution and preparing vanadium electrolyte. Detailed Implementation

[0033] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which constitute a part of the present invention and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0034] On one hand, this invention discloses a method for preparing a vanadium electrolyte, comprising:

[0035] Using vanadium molybdate solution as raw material, the extraction organic phase is used to sequentially extract and recover vanadium and molybdenum elements from the solution based on pH adjustment. The composition of the extraction organic phase is the same for vanadium and molybdenum element extraction.

[0036] The recovered vanadium products are purified to prepare vanadium electrolyte.

[0037] In practice, this invention preferentially extracts vanadium under alkaline conditions to separate vanadium from molybdenum-rich raffinate and enrich vanadium; further, it extracts molybdenum under acidic conditions to separate molybdenum from raffinate and enrich molybdenum; and further still, it purifies the recovered vanadium product to prepare vanadium electrolyte.

[0038] Compared with existing technologies, this invention achieves vanadium extraction and separation from molybdenum by adjusting the pH value of the vanadium-molybdate solution and utilizing the selective alteration of vanadium and molybdenum elements in the extraction organic phase. Furthermore, through secondary purification, it prepares vanadium oxysulfate that meets the requirements for vanadium electrolyte preparation and vanadium electrolyte products that exceed national standards. This invention enables the separation and purification of vanadium from common industrial or intermediate processing products such as vanadium-molybdenum mixed solutions and the preparation of vanadium electrolytes. Compared with existing technologies, this invention greatly simplifies the vanadium purification process, significantly expands the sources of vanadium, and reduces costs and dependence on vanadium pentoxide.

[0039] Preferably, vanadium in the recovered vanadium products exists mostly in the form of V or IV valence; the average valence state of vanadium in the vanadium electrolyte is 3.5 valence; the preparation of vanadium electrolyte from the recovered vanadium products requires adjustment of the valence of vanadium.

[0040] It should be noted that vanadium in vanadium-molybdate solutions is mostly in the V-valence state, while the average valence state of vanadium in vanadium electrolytes is 3.5. When preparing vanadium electrolytes by extracting vanadium from organic solvents, it is necessary to adjust the valence state of vanadium.

[0041] Meanwhile, this invention alters the selectivity of the same extractable organic compound for vanadium and molybdenum by adjusting the pH value in the vanadium-molybdate solution. While ensuring the extraction and separation effect, it achieves the sequential extraction and recovery of vanadium and molybdenum in the solution. The vanadium recovery rate is ≥99.5%, and the vanadium product after evaporation, concentration, and crystallization has a vanadium salt mass fraction of ≥99.5%; the molybdenum recovery rate is ≥99.5%, and the molybdenum product after evaporation, concentration, and crystallization has a molybdate mass fraction of ≥99.5%. Furthermore, through secondary purification, it prepares vanadium oxysulfate that meets the requirements for vanadium electrolyte preparation and vanadium electrolyte products that exceed national standards. The purity of the vanadium electrolyte product is ≥99.99%. This invention overcomes the shortcomings of existing technologies, such as poor separation of elements in the leaching solution, resulting in low yield, low product purity, and difficulty in separating high-purity vanadium from vanadium-molybdenum homologous materials.

[0042] It should be noted that this invention achieves the extraction of two elements by using the same extraction organic phase, thus avoiding the pollution caused by the residual extraction phase in the raffinate when different elements are extracted using different extraction systems. At the same time, since the extraction organic phase is the same, the organic phase after back-extraction can be recycled without worrying about cross-contamination between extraction systems, thereby reducing waste liquid discharge and environmental pollution.

[0043] Specifically, the extractable organic phase includes quaternary ammonium salt extractants or a mixture of quaternary ammonium salt extractants and tertiary amine extractants.

[0044] Preferably, the tertiary amine extractant is one or more of the following: a tertiary amine with substituents of C8 to C10, a tertiary amine with substituents of isooctyl, and N2O8.

[0045] Preferably, the tertiary amine with C8-C10 substituents is any one of N235, Alamine336, Adogen364, HostarexA327 and TOA.

[0046] Preferably, the tertiary amine with isooctyl substituents is any one of Adogen381, Alamine308, HostarexA324 and Adogen382.

[0047] Preferably, the pH value of the solution required for extracting vanadium is 8-9; the pH value of the molybdenum-rich raffinate required for extracting molybdenum is 3-4.

[0048] It should be noted that when the pH value is 2-9, vanadium in the solution exists as V4O 12 4- , V3O9 3- , V2O7 4- , VO3 - and a variety of polymerized isopolyacid radical ions, such as HV 10 O 28 5- , H2V 10 O 28 4- and other forms, and the extraction organic phase has extremely high extraction selectivity for all the above existing forms. When pH<2 and pH>10, the extraction rate of vanadium by the extraction organic phase decreases significantly.

[0049] It should be noted that when pH<4, molybdenum in the molybdenum-rich raffinate exists as various polymerized isopolyacid radical ions, such as Mo2O7 2- , Mo3O 10 2- , Mo4O 13 2- , Mo7O 24 6- (or HMo7O 24 5- , H3Mo7O 24 3- ), Mo8O 26 4- and cationic polymer form under strong acidic conditions. The extraction organic phase has extremely high extraction selectivity for various polymerized isopolyacid radical ions. When 4<pH<8, the extraction rate of molybdenum by the extraction organic phase gradually decreases, and when pH>8, the extraction rate of molybdenum by the extraction organic phase decreases significantly.

[0050] It should also be noted that when vanadium and molybdenum are extracted in sequence as described above, the extraction order of vanadium and molybdenum cannot be adjusted. If the process is carried out in the manner described above, such as "molybdenum extraction first, then vanadium extraction", the separation effect of molybdenum and vanadium will be deteriorated, resulting in more vanadium impurities in the molybdenum product and reducing the purity of the molybdenum product.

[0051] Preferably, the extracted organic phase also includes an alcohol phase modifier with 7 to 10 carbon atoms.

[0052] Specifically, the alcohol phase modifier can be one or more of n-heptanol, n-octanol, sec-octanol, isooctanol, n-decanol, etc.

[0053] It should be noted that alcohol phase modifiers can improve the performance of the extraction system and increase extraction efficiency; they can also reduce the water solubility of the extraction system and reduce extractant loss; in addition, they can optimize the extraction system and prevent emulsification and the formation of a third phase.

[0054] It should be noted that alcohol phase modifiers with 7 to 10 carbon atoms have the advantages of high fluidity, low water solubility, and low cost.

[0055] Preferably, the extraction organic phase also includes a low-viscosity diluent to improve the relative fluidity of the organic phase and the aqueous phase during extraction, thereby enhancing contact and ion exchange effects.

[0056] Preferably, the diluent can be 260# solvent oil.

[0057] Specifically, the volume ratio of extractant, phase modifier, and diluent in the extracted organic phase satisfies the following: extractant 10–40%; phase modifier 5–20%; diluent 40–85%.

[0058] Specifically, the volume fraction of the extractant in the organic phase can be 10%, 12%, 14%, 15%, 16%, 18%, 20%, 21%, 22%, 24%, 25%, 26%, 28%, 30%, 32%, 33%, 34%, 35%, 37%, 38%, 39%, or 40%.

[0059] Specifically, the volume fraction of the phase modifier in the extracted organic phase can be 5%, 6%, 7%, 8%, 9%, 10%, 12%, 14%, 15%, 16%, 18%, or 20%.

[0060] Specifically, the volume fraction of the diluent in the extracted organic phase can be 40%, 42%, 43%, 44%, 45%, 47%, 48%, 49%, 50%, 50%, 52%, 53%, 54%, 55%, 57%, 58%, 59%, 60%, 60%, 62%, 63%, 64%, 65%, 67%, 68%, 69%, 70%, 72%, 73%, 74%, 75%, 77%, 78%, 79%, 80%, 82%, 83%, 84%, or 85%.

[0061] Specifically, the method for clean separation and recovery of vanadium and molybdenum from the vanadium-molybdate solution includes:

[0062] S1. Adjust the vanadium molybdate solution to alkaline, and use the extraction organic phase to extract the vanadium molybdate solution to obtain a vanadium-rich organic phase and a molybdenum-rich raffinate.

[0063] S2. Adjust the molybdenum-rich raffinate to acidity, and use an extractive organic phase to extract the molybdenum-rich raffinate to obtain a molybdenum-rich organic phase and raffinate.

[0064] S3. The vanadium-rich organic phase and the molybdenum-rich organic phase are back-extracted independently to obtain vanadium-rich back-extracting solution and molybdenum-rich back-extracting solution;

[0065] S4. Prepare molybdenum products from molybdenum-rich back-extraction solution; further prepare vanadium products or vanadium electrolyte products from vanadium-rich back-extraction solution.

[0066] Specifically, the pH of the vanadium molybdate solution in S1 is adjusted to 8-9.

[0067] Specifically, the extraction ratio in S1 is O / A = 1:5 to 5:1, and the number of extraction stages is 2 to 10.

[0068] Specifically, in S2, the pH of the molybdenum-rich raffinate is adjusted to 3-4.

[0069] Specifically, the extraction ratio in S2 is O / A = 1:5 to 5:1, and the number of extraction stages is 2 to 8.

[0070] Specifically, the ratio of back-extraction in molybdenum-rich organic compounds in S3 is O / A = 1 to 10:1, and the number of back-extraction stages is 2 to 10.

[0071] Preferably, before step S3, there are steps of washing the vanadium-rich organic phase and refluxing the washing liquid to the vanadium extraction section, and washing the molybdenum-rich organic phase and refluxing the washing liquid to the molybdenum extraction section.

[0072] Specifically, the vanadium-rich organic phase and molybdenum-rich organic phase detergents are sulfate aqueous solutions.

[0073] Specifically, the washing ratio of vanadium-rich organic phase and molybdenum-rich organic phase is 5 to 10:1.

[0074] Specifically, the pH value of the vanadium-rich organic phase detergent is ≥ the pH value of the vanadium molybdate solution in S1 after adjustment.

[0075] Preferably, the pH value of the vanadium-rich organic phase detergent can be selected as 8 to 9.5.

[0076] It should be noted that within this pH range, while ensuring a relatively low vanadium elution efficiency, other impurities entrained in the vanadium-rich organic phase can be effectively washed away, which is beneficial for enriching and purifying the downstream vanadium-rich back-extraction solution. When pH < 8, incomplete molybdenum elution may occur in the vanadium-rich organic phase, leading to a decrease in the purity of the vanadium-rich back-extraction solution; when pH > 9.5, vanadium in the vanadium-rich organic phase will have a high elution rate, resulting in a decrease in vanadium yield.

[0077] Specifically, the sulfate concentration of the vanadium-rich organic phase detergent is 0.05 mol / L to 0.5 mol / L.

[0078] Specifically, the pH value of the molybdenum-rich organic phase detergent is ≥ the pH value of the molybdenum-rich raffinate in S2 after adjustment.

[0079] Preferably, the pH value of the molybdenum-rich organic phase detergent can be selected as 3 to 5.

[0080] It should be noted that within this pH range, while ensuring a relatively low elution efficiency for molybdenum, it effectively removes other impurities entrained in the molybdenum-rich organic phase, which is beneficial for enriching and purifying the downstream molybdenum-rich back-extraction solution. When pH < 3, more acid will be consumed, increasing costs; when pH > 5, molybdenum in the molybdenum-rich organic phase will have a high elution rate, leading to a decrease in molybdenum yield.

[0081] Specifically, the sulfate concentration of the molybdenum-rich organic phase detergent is 0.05 mol / L to 0.5 mol / L.

[0082] Preferably, the method for cleaning, separating, and recovering vanadium and molybdenum from the leachate further includes:

[0083] The blank organic phase obtained from S3 back-extraction was washed and regenerated with water and used as the reflux for extraction organic phase.

[0084] Specifically, the ratio of O / A to O / A in the blank organic phase water washing regeneration is 1 to 10:1, and the number of stages is 1 to 2.

[0085] Specifically, the reaction agent for the vanadium-rich organic reverse extraction in S3 is an alkaline sulfate aqueous solution with a pH value > 11 or a sulfuric acid solution with a pH value < 1.

[0086] It should be noted that when the pH value is <2 and the pH value is >10, the extraction rate of vanadium from the organic phase decreases significantly. Within this range, the reagent can back-extract vanadium compounds from the organic phase, achieving separation of vanadium from the organic phase and enrichment of vanadium.

[0087] Specifically, alkaline sulfates can be sodium sulfate or potassium sulfate.

[0088] In a preferred embodiment, the reaction agent for the vanadium-rich organic back-extraction in S3 is a sulfuric acid solution with a pH value <1, and a gaseous reducing agent is introduced simultaneously with the back-extraction to obtain a vanadium oxysulfate back-extraction solution.

[0089] Specifically, the gaseous reducing agent can be sulfur dioxide gas, which can effectively reduce V-valent vanadium to IV-valent vanadium in an acidic environment.

[0090] Specifically, the SO2 gas flow rate is 1 to 1.5 times the theoretical consumption, and the back-extraction ratio O / A = 5 to 10 / 1.

[0091] In another preferred embodiment, the vanadium-rich organic back-extraction agent in S3 is an alkaline sulfate aqueous solution with a pH value > 11, to obtain a vanadium-rich back-extraction solution or to further prepare a vanadium product from the vanadium-rich back-extraction solution. A reducing agent B is added to the solution of the vanadium-rich back-extraction solution or the vanadium product to obtain a vanadium oxysulfate reducing solution.

[0092] Specifically, reducing agent B can be one or more of sodium sulfide, sodium sulfite, sodium thiosulfate, sodium metabisulfite, sulfur dioxide, ascorbic acid, sodium nitrite, and oxalic acid. The vanadium-rich back-extraction solution or the solution of vanadium products is gradually acidified to an acidic environment. In this process, the reducing agent can effectively reduce V-valent vanadium to IV-valent vanadium.

[0093] Specifically, the amount of reducing agent B introduced is 1 to 1.5 times the theoretical consumption, and the O / A ratio in the back-extraction of S3 is 5 to 10 / 1.

[0094] Specifically, the vanadium-rich back-extraction solution or the solution of vanadium products is acidified to an acidic environment with a final pH of 1 to 1.5, which is conducive to the complete reduction reaction.

[0095] The above two methods yield vanadium oxysulfate back-extraction solution and vanadium oxysulfate reduction solution, respectively. After filtration, they are subjected to secondary extraction, secondary washing and secondary back-extraction in sequence. After purification, oil removal and electrolytic preparation, a vanadium 3.5 valence electrolyte product is obtained with a purity of ≥99.99%.

[0096] Specifically, the pH of the vanadium oxysulfate back-extraction solution and the vanadium oxysulfate reduction solution is adjusted to 2-3 and then filtered.

[0097] It should be noted that adjusting the pH of the vanadium oxysulfate back-extraction solution and the vanadium oxysulfate reduction solution to 2-3 before filtration can further remove impurity ions.

[0098] It should be noted that the pre-extraction solution is obtained after adjusting the pH value and filtering the vanadium oxysulfate back-extraction solution and the vanadium oxysulfate reduction solution.

[0099] Specifically, the second extraction extracts vanadium from the pre-extraction solution of the second extraction at a ratio of O / A = 1 to 3 / 1, followed by 2 to 8 stages of extraction.

[0100] Specifically, the volume fraction of each component in the extracted organic phase during the secondary extraction includes: 10%–40% extractant, 2%–20% co-extractant, and 40%–88% diluent.

[0101] Specifically, the extractant can be one or more of P204, P507, Cyanex272, Cyanex301, and Cyanex302; the co-extractant can be one or more of TBP, 2-octanol, and isooctanol; and the diluent can be 260# solvent oil.

[0102] Specifically, after secondary extraction, vanadium-containing load and raffinate are obtained; the vanadium-containing load and the detergent used for secondary washing are washed in a ratio of O / A = 5 to 20 / 1, and then washed in 2 to 10 stages to obtain the secondary washed load and the secondary washed effluent. The detergent used for secondary washing is a dilute sulfuric acid solution with a pH of 1 to 3. The effluent is combined with the pre-extraction liquid of secondary extraction and used as the feed liquid for secondary extraction. Secondary washing can remove some impurities entrained in and extracted from the vanadium-containing load.

[0103] Specifically, after secondary washing, the loading and the reaction agent from secondary back-extraction are at a ratio of O / A = 5 to 15 / 1. After 2 to 10 stages of secondary back-extraction, a blank organic phase and a vanadium oxysulfate solution are obtained, wherein the reaction agent is a sulfuric acid solution of 3 mol / L to 5 mol / L, and the vanadium concentration in the vanadium oxysulfate solution is >1.7 mol / L.

[0104] More preferably, after secondary back-extraction, the extracted organic phase is regenerated twice to obtain a recycled organic phase and regenerated water, which can be used for the formulation of detergents and counteractors.

[0105] Specifically, the purification and degreasing process satisfies the requirement that the obtained vanadium sulfate oxysulfate solution is adsorbed to obtain a purified and degreased vanadium solution, at which point the oil content in the vanadium solution is <1ppm.

[0106] Specifically, the electrolytic preparation includes: electrolyzing the product at a certain current density based on charge balance calculations to obtain a vanadium electrolyte product with a vanadium valence of 3.5 valence.

[0107] Preferably, S1 further includes:

[0108] S0. The organic phase of the extract is treated with acid to transform it into activated quaternary ammonium salt.

[0109] Specifically, S0 includes:

[0110] S001. Mix the extractant, phase modifier, and diluent evenly according to the set volume ratio to obtain the extractable organic phase;

[0111] S002. The extracted organic phase obtained in S001 is washed with a sulfuric acid solution of 1 mol / L to 2 mol / L.

[0112] S003. Further wash the extracted organic phase treated with S002 until it is neutral.

[0113] Preferably, the method for the clean separation and recovery of vanadium and molybdenum from the vanadium-molybdate solution further includes:

[0114] S5. The raffinate is refluxed to prepare a vanadium-molybdate solution, recovering the unextracted vanadium and molybdenum, and concentrating the remaining precious metals except for vanadium and molybdenum.

[0115] During implementation, the unextracted vanadium and molybdenum further participate in the extraction of vanadium and molybdenum, avoiding the waste of vanadium and molybdenum elements and helping to improve the yield of vanadium and molybdenum elements; at the same time, the other metal elements in the leachate, except for vanadium and molybdenum, are not extracted by the organic phase and accumulate continuously during the reflux process of the raffinate, realizing the enrichment of multiple precious metal elements and providing high-grade raw materials for the recovery of other precious metal elements.

[0116] Compared with the prior art, the present invention uses the reflux of the raffinate to prepare a vanadium-molybdate solution. On the one hand, this avoids the waste of vanadium and molybdenum elements and improves the yield of vanadium and molybdenum elements. On the other hand, the reflux of the raffinate achieves the enrichment of various precious metal elements, which facilitates the recovery of precious metal elements.

[0117] To better illustrate the present invention, the following embodiments and comparative examples are provided:

[0118] Example 1

[0119] This embodiment discloses a method for preparing a vanadium electrolyte, such as... Figure 1 As shown, it includes:

[0120] 1. Solution pretreatment: The solution is a commercially available vanadium-molybdate mixture. The pH of the solution was adjusted to 8.8 using concentrated sulfuric acid. The Mo content in the vanadium-molybdenum solution was 23.4 g / L, and the V content was 13.8 g / L.

[0121] 2. Organic phase pretreatment: The organic phase is a mixture of 10% Alamine 336, 15% N263, 10% 2-octanol and 65% 260# solvent oil by volume. The organic phase is treated 6 times with 2 mol / L sulfuric acid solution at a ratio O / A = 1 / 1, and then washed with deionized water until it is near neutral.

[0122] 3. Vanadium extraction: The pretreated organic phase was mixed with the pretreated solution at a ratio of O / A = 1 / 1.5 for extraction. The extraction stage was 5 stages, resulting in vanadium-loaded 1 and molybdenum-rich raffinate, wherein the vanadium content in the molybdenum-rich raffinate was 16 ppm.

[0123] 4. Washing 1: The detergent used for washing 1 is a sodium sulfate solution with a pH of 9.2 and a sodium sulfate concentration of 0.3 mol / L. The ratio of O / A in washing 1 is 8 / 1, and the number of washing stages in washing 1 is 8. Vanadium-containing load 2 and wash water 1 are obtained. Wash water 1 is combined with the vanadium extraction section and enters the vanadium extraction section together with the pretreated solution.

[0124] 5. Selection of the back-extraction route for back-extraction 1A: The reaction agent used for back-extraction 1A is an alkaline sodium sulfate solution, in which OH... - The concentration was 0.16 mol / L, the sodium sulfate concentration was 0.25 mol / L, the ratio of O / A to 1 / 1 in back-extraction 1A was 6 stages, and a blank organic phase and a vanadium-rich back-extraction solution were obtained. The vanadium concentration in the vanadium-rich back-extraction solution was 20.68 g / L, corresponding to a vanadium recovery rate of 99.88%. The vanadium product after evaporation, concentration and crystallization had a vanadate mass fraction of 99.68%.

[0125] 6. Regeneration 1A: Regeneration 1A uses pure water. Compared with O / A = 6 / 1, the number of stages for regeneration 1A is 1. The pH of the effluent from regeneration 1A is controlled at near neutral. The regenerated organic phase is obtained. There is no need to repeat the organic phase pretreatment. It can be directly returned to the extraction system for recycling.

[0126] 7. Molybdenum extraction: The pH of the molybdenum-rich raffinate was adjusted to 3.8 using sulfuric acid. The pretreated organic phase was mixed with the pH-adjusted molybdenum-rich raffinate at a ratio of O / A = 1.5 / 1 for extraction. The extraction stage was 4 stages, resulting in molybdenum-loaded 1 and raffinate. The molybdenum content in the raffinate was 22 ppm. The raffinate was returned to the front end for the preparation of vanadium molybdate solution.

[0127] 8. Washing 2: The detergent used in washing 2 is a sodium sulfate solution with a pH of 4 and a sodium sulfate concentration of 0.15 mol / L. The ratio of O / A in washing 2 is 7 / 1. The number of washing stages in washing 2 is 5, resulting in molybdenum-containing load 2 and wash water 2. Wash water 2 is combined into the molybdenum extraction section and enters the molybdenum extraction section together with the molybdenum-rich raffinate after pH adjustment.

[0128] 9. Back-extraction 2: The reaction agent used in back-extraction 2 is an alkaline sodium sulfate solution, in which OH... - The concentration was 0.41 mol / L, the sodium sulfate concentration was 0.25 mol / L, the O / A ratio of the back-extraction phase 2 was 4 / 1, the back-extraction phase 2 had 6 stages, and a blank organic phase and a molybdenum-rich back-extraction solution were obtained. The Mo concentration in the molybdenum-rich back-extraction solution was 62.34 g / L, corresponding to a molybdenum recovery rate of 99.91%. The molybdenum product after evaporation, concentration and crystallization had a molybdate mass fraction of 99.70%.

[0129] 10. Regeneration 2: Regeneration 2 uses pure water. Compared with O / A = 6 / 1, Regeneration 2 is a single stage. The pH of the effluent from Regeneration 2 is controlled at near neutral. The regenerated organic phase is obtained. There is no need to repeat the organic phase pretreatment. It can be directly returned to the extraction system for recycling.

[0130] 11. Purification of 1A:

[0131] The vanadium product obtained by back-extraction of 1A in step 5 is purified by 1A to obtain vanadium oxysulfate solution;

[0132] Purification of 1A includes pretreatment, extraction, washing, back-extraction, and regeneration steps;

[0133] A. Preprocessing:

[0134] After the vanadium product obtained by back-extraction 1A is dissolved, sodium sulfite (1.1 times the theoretical amount) is added as a reducing agent; acid is added for reduction, and the final pH value of the reaction is between 1 and 1.5; then alkali is added to adjust the pH value to 2 and the mixture is filtered to obtain the pre-extraction solution.

[0135] A Extraction:

[0136] Extraction A extracts vanadium from the pre-extraction solution at a ratio of O / A = 1.5 / 1, followed by 5 stages of extraction. The volume fractions of the components extracted in the organic phase during extraction A include: 15% P2O4, 10% P5O7, 10% TBP, and 65% 260# solvent oil.

[0137] A. Washing:

[0138] After A extraction, vanadium-containing load and raffinate are obtained; the vanadium-containing load and the detergent used in A washing are washed in a ratio of O / A = 10 / 1, and after 10 stages of washing, the washed load and the wash water from A washing are obtained. The detergent used in A washing is a dilute sulfuric acid solution with a pH of 3. The wash water is combined with the pre-extraction liquid of A extraction and used as the feed liquid for A extraction. A washing can remove some impurities entrained in the vanadium-containing load and some of the extracted impurities.

[0139] A stripping:

[0140] After washing A, the loading and the reaction agent of A back-extraction were compared with O / A = 7 / 1. After 6 stages of A back-extraction, a blank organic phase and a vanadium oxysulfate solution were obtained, in which the reaction agent was a 3.5 mol / L sulfuric acid solution and the vanadium concentration in the vanadium oxysulfate solution was 1.89 mol / L.

[0141] A regeneration:

[0142] After back-extraction, the blank organic phase is regenerated to obtain a recycled organic phase and regenerated water. The regenerated water can be used for the formulation of detergents and reaction agents.

[0143] 12. Purification and oil removal 1A: Vanadium oxysulfate solution enters the purification and oil removal system. After purification and oil removal, the oil content in the vanadium oxysulfate solution is <1ppm.

[0144] 13. Electrolytic Preparation 1A: The degreased vanadium oxysulfate solution is electrolytically prepared to obtain a vanadium electrolyte product with a 3.5 valence.

[0145] The purity of the prepared vanadium 3.5 electrolyte is >99.99%, and the contents of the main impurities are shown in the table below.

[0146]

[0147] Example 2

[0148] This embodiment discloses a method for preparing a vanadium electrolyte, such as... Figure 1 As shown, it includes:

[0149] 1. Solution pretreatment: The solution is a vanadium molybdate solution obtained by acid leaching of waste vanadium-molybdenum catalyst. The pH of the leachate is adjusted to 8.2 using liquid alkali. The Mo content in the leachate is 8.26 g / L and the V content is 6.79 g / L.

[0150] 2. Organic phase pretreatment: The organic phase is a mixture of 5% Alamine 308, 15% Aliquat 336, 10% n-decyl alcohol and 70% 260# solvent oil by volume. The organic phase is treated 6 times with 1.5 mol / L sulfuric acid solution at a ratio O / A = 1 / 1, and then washed with deionized water until it is near neutral.

[0151] 3. Vanadium extraction: The pretreated organic phase was mixed with the pretreated solution at a ratio of O / A = 1 / 3 for extraction. The extraction stage was 7 stages, resulting in vanadium-loaded 1 and molybdenum-rich raffinate, wherein the vanadium content in the molybdenum-rich raffinate was 9 ppm.

[0152] 4. Washing 1: The detergent used for washing 1 is a potassium sulfate solution with a pH of 8.7 and a potassium sulfate concentration of 0.1 mol / L. The ratio of O / A in washing 1 is 6 / 1, and the number of washing stages is 6. Vanadium-containing load 2 and wash water 1 are obtained. Wash water 1 is combined with the vanadium extraction section and enters the vanadium extraction section together with the pretreated solution.

[0153] 5. For the selection of back-extraction 1A: The reaction agent used in back-extraction 1A is an alkaline potassium sulfate solution, in which OH... - The concentration was 0.41 mol / L, the potassium sulfate concentration was 0.2 mol / L, the ratio of O / A to back-extraction 1A was 1.5 / 1, the number of back-extraction stages 1A was 5, and a blank organic phase and a vanadium-rich back-extraction solution were obtained. The vanadium concentration in the vanadium-rich back-extraction solution was 30.51 g / L, corresponding to a vanadium recovery rate of 99.87%. The vanadium product after evaporation, concentration and crystallization had a vanadate mass fraction of 99.50%.

[0154] 6. Regeneration 1A: Regeneration 1A uses pure water. Compared with O / A = 5 / 1, the number of stages for regeneration 1A is 2. The pH of the effluent from regeneration 1A is controlled at near neutral. The regenerated organic phase is obtained. There is no need to repeat the organic phase pretreatment. It can be directly returned to the extraction system for recycling.

[0155] 7. Extraction of molybdenum: The pH of the molybdenum-rich raffinate was adjusted to 3.2 using sulfuric acid. The pretreated organic phase was mixed with the pH-adjusted molybdenum-rich raffinate at a ratio of O / A = 1 / 2 for extraction. The extraction stage was 5 stages, resulting in molybdenum-loaded 1 and raffinate. The molybdenum content in the raffinate was 14 ppm. The raffinate was returned to the front end for the preparation of vanadium molybdate solution.

[0156] 8. Washing 2: The detergent used in washing 2 is a potassium sulfate solution with a pH of 3.7 and a potassium sulfate concentration of 0.08 mol / L. The ratio of O / A in washing 2 is 6 / 1, and the number of washing stages in washing 2 is 3. The resulting molybdenum-containing load 2 and wash water 2 are obtained. Wash water 2 is combined with the molybdenum extraction section and enters the molybdenum extraction section together with the pH-adjusted molybdenum-rich raffinate.

[0157] 9. Back-extraction 2: The reaction agent used in back-extraction 2 is an alkaline potassium sulfate solution, in which OH... - The concentration was 0.67 mol / L, the potassium sulfate concentration was 0.2 mol / L, the O / A ratio of the back-extraction phase 2 was 5 / 1, the back-extraction phase 2 had 5 stages, and a blank organic phase and a molybdenum-rich back-extraction solution were obtained. The Mo concentration in the molybdenum-rich back-extraction solution was 82.46 g / L, corresponding to a molybdenum recovery rate of 99.83%. The molybdate mass fraction in the molybdenum product after evaporation, concentration and crystallization was 99.75%.

[0158] 10. Regeneration 2: Regeneration 2 uses pure water. Compared with O / A = 5 / 1, Regeneration 2 has 2 stages. The pH of the effluent from Regeneration 2 is controlled at near neutral. The regenerated organic phase is obtained. There is no need to repeat the organic phase pretreatment. It can be directly returned to the extraction system for recycling.

[0159] 11. Purification of 1A:

[0160] In step 5, the vanadium-rich back-extraction solution obtained by back-extraction 1A is purified to obtain vanadium oxysulfate solution.

[0161] Purification of 1A includes pretreatment, extraction, washing, back-extraction, and regeneration steps;

[0162] A. Preprocessing:

[0163] The vanadium-rich back-extraction solution obtained from back-extraction 1A was added with sodium thiosulfate at 1.2 times the theoretical amount as a reducing agent; acid was added for reduction, and the final pH value of the reaction was between 1 and 1.5; then alkali was added to adjust the pH value to 2.4 and the solution was filtered to obtain the pre-extraction solution;

[0164] A Extraction:

[0165] A extraction was performed to extract vanadium from the pre-extraction solution at a ratio of O / A = 2 / 1, followed by 5 stages of extraction. The volume fractions of each component in the extracted organic phase during A extraction included: 20% P2O4, 5% Cyanex 272, 5% 2-octanol, and 70% 260# solvent oil.

[0166] A. Washing:

[0167] After A extraction, vanadium-containing load and raffinate are obtained; the vanadium-containing load and the detergent used in A washing are washed in a ratio of O / A = 12 / 1, and the 8-stage washing process is used to obtain washed load and A washing effluent. The detergent used in A washing is a dilute sulfuric acid solution with a pH of 2. The effluent is combined with the A extraction section and used together with the pre-extraction liquid of A extraction as the feed liquid for A extraction. A washing can remove some impurities entrained in the vanadium-containing load and some of the extracted impurities.

[0168] A stripping:

[0169] After washing A, the loading and the reaction agent of A back-extraction were compared with O / A = 6.5 / 1. After 5 stages of A back-extraction, a blank organic phase and a vanadium oxysulfate solution were obtained, in which the reaction agent was a 4 mol / L sulfuric acid solution and the vanadium concentration in the vanadium oxysulfate solution was 1.95 mol / L.

[0170] A regeneration:

[0171] After back-extraction, the blank organic phase is regenerated to obtain a recycled organic phase and regenerated water. The regenerated water can be used for the formulation of detergents and reaction agents.

[0172] 12. Purification and oil removal 1A: Vanadium oxysulfate solution enters the purification and oil removal system. After purification and oil removal, the oil content in the vanadium oxysulfate solution is <1ppm.

[0173] 13. Electrolytic Preparation 1A: The degreased vanadium oxysulfate solution is electrolytically prepared to obtain a vanadium electrolyte product with a 3.5 valence.

[0174] The purity of the prepared vanadium 3.5 electrolyte is >99.99%, and the contents of the main impurities are shown in the table below.

[0175]

[0176] Example 3

[0177] This embodiment discloses a method for preparing a vanadium electrolyte, such as... Figure 1 As shown, it includes:

[0178] 1. Solution pretreatment: The solution is a vanadium molybdate solution obtained from the leaching of vanadium-molybdenum-lead ore. The pH of the leaching solution is adjusted to 8.5 using sulfuric acid. The Mo content in the solution is 14.32 g / L and the V content is 21.09 g / L.

[0179] 2. Organic phase pretreatment: The organic phase is a mixture of 10% N2O8, 15% Adogen464, 15% n-heptanol and 60% 260# solvent oil by volume. The organic phase is treated 6 times with 1 mol / L sulfuric acid solution at a ratio O / A = 1 / 1, and then washed with deionized water until it is nearly neutral.

[0180] 3. Vanadium extraction: The pretreated organic phase was mixed with the pretreated solution at a ratio of O / A = 1.1 / 1 for extraction. The extraction stage was 8 stages, resulting in vanadium-loaded 1 and molybdenum-rich raffinate, wherein the vanadium content in the molybdenum-rich raffinate was 11 ppm.

[0181] 4. Washing 1: The detergent used for washing 1 is a sodium sulfate solution with a pH of 9.5 and a sodium sulfate concentration of 0.2 mol / L. The ratio of O / A in washing 1 is 5 / 1, and the number of washing stages is 5. Vanadium-containing load 2 and wash water 1 are obtained. Wash water 1 is combined with the vanadium extraction section and enters the vanadium extraction section together with the pretreated solution.

[0182] 5. Choosing the route for back-extraction 1A: The reactant used in back-extraction 1A is an alkaline sodium sulfate solution, in which OH... - The concentration was 0.31 mol / L, the sodium sulfate concentration was 0.2 mol / L, the ratio of O / A to 1.2 / 1 for back-extraction 1A, the number of back-extraction stages for 1A was 5, and a blank organic phase and a vanadium-rich back-extraction solution were obtained. The vanadium concentration in the vanadium-rich back-extraction solution was 23.0 g / L, corresponding to a vanadium recovery rate of 99.95%. The vanadium product after evaporation, concentration and crystallization had a vanadate mass fraction of 99.71%.

[0183] 6. Regeneration 1A: Regeneration 1A uses pure water. Compared to O / A = 7 / 1, the number of stages for regeneration 1A is 1. The pH of the effluent from regeneration 1A is controlled at near neutral. The regenerated organic phase is obtained. There is no need to repeat the organic phase pretreatment. It can be directly returned to the extraction system for recycling.

[0184] 7. Extraction of molybdenum: The pH of the molybdenum-rich raffinate was adjusted to 3.5 using sulfuric acid. The pretreated organic phase was mixed with the pH-adjusted molybdenum-rich raffinate at a ratio of O / A = 1 / 1 for extraction. The extraction stage was 6 stages, resulting in molybdenum-loaded 1 and raffinate. The molybdenum content in the raffinate was 17 ppm. The raffinate was returned to the front end for the preparation of vanadium molybdate solution.

[0185] 8. Washing 2: The detergent used in washing 2 is a sodium sulfate solution with a pH of 4.5 and a sodium sulfate concentration of 0.13 mol / L. The ratio of O / A in washing 2 is 8 / 1, and the number of washing stages in washing 2 is 5. The resulting molybdenum-containing load 2 and wash water 2 are obtained. Wash water 2 is combined with the molybdenum extraction section and enters the molybdenum extraction section together with the pH-adjusted molybdenum-rich raffinate.

[0186] 9. Back-extraction 2: The reaction agent used in back-extraction 2 is an alkaline sodium sulfate solution, in which OH... - The concentration was 0.51 mol / L, the sodium sulfate concentration was 0.25 mol / L, the O / A ratio of the back-extraction phase 2 was 5 / 1, the back-extraction phase 2 had 4 stages, and a blank organic phase and a molybdenum-rich back-extraction solution were obtained. The Mo concentration in the molybdenum-rich back-extraction solution was 71.52 g / L, corresponding to a molybdenum recovery rate of 99.88%. The molybdate mass fraction in the molybdenum product after evaporation, concentration and crystallization was 99.61%.

[0187] 10. Regeneration 2: Regeneration 2 uses pure water. Compared with O / A = 7 / 1, Regeneration 2 is a single stage. The pH of the effluent from Regeneration 2 is controlled at near neutral. The regenerated organic phase is obtained. There is no need to repeat the organic phase pretreatment. It can be directly returned to the extraction system for recycling.

[0188] 11. Purification of 1A:

[0189] In step 5, the vanadium-rich back-extraction solution obtained by back-extraction 1A is purified to obtain vanadium oxysulfate solution.

[0190] Purification of 1A includes pretreatment, extraction, washing, back-extraction, and regeneration steps;

[0191] A. Preprocessing:

[0192] The vanadium-rich back-extraction solution obtained from back-extraction 1A was mixed with sodium sulfide at 1.3 times the theoretical amount as a reducing agent; acid was added for reduction, and the final pH of the reaction was between 1 and 1.5; then alkali was added to adjust the pH to 2.3 and the solution was filtered to obtain the pre-extraction solution.

[0193] A Extraction:

[0194] Extraction A extracts vanadium from the pre-extraction solution at a ratio of O / A = 1.5 / 1, followed by four stages of extraction. The volume fractions of each component in the organic phase extracted in extraction A include: 20% P507, 5% Cyanex301, 5% isooctanol, and 70% 260# solvent oil.

[0195] A. Washing:

[0196] After A extraction, vanadium-containing load and raffinate are obtained; the vanadium-containing load and the detergent used in A washing are washed in a ratio of O / A = 9 / 1, and the washing is carried out in 7 stages to obtain washed load and A washing effluent. The detergent used in A washing is a dilute sulfuric acid solution with a pH of 1.5. The effluent is combined with the A extraction section and used together with the pre-extraction liquid of A extraction as the feed liquid for A extraction. A washing can remove some impurities entrained in the vanadium-containing load and some of the extracted impurities.

[0197] A stripping:

[0198] After washing A, the loading and the reaction agent of A back-extraction were compared with O / A = 6 / 1. After 4 stages of A back-extraction, a blank organic phase and a vanadium oxysulfate solution were obtained, in which the reaction agent was a 3 mol / L sulfuric acid solution and the vanadium concentration in the vanadium oxysulfate solution was 1.81 mol / L.

[0199] A regeneration:

[0200] After back-extraction, the blank organic phase is regenerated to obtain a recycled organic phase and regenerated water. The regenerated water can be used for the formulation of detergents and reaction agents.

[0201] 12. Purification and oil removal 1A: Vanadium oxysulfate solution enters the purification and oil removal system. After purification and oil removal, the oil content in the vanadium oxysulfate solution is <1ppm.

[0202] 13. Electrolytic Preparation 1A: The degreased vanadium oxysulfate solution is electrolytically prepared to obtain a vanadium electrolyte product with a 3.5 valence.

[0203] The purity of the prepared vanadium 3.5 electrolyte is >99.99%, and the contents of the main impurities are shown in the table below.

[0204]

[0205] Example 4

[0206] This embodiment discloses a method for preparing vanadium electrolyte, which differs from Example 2 in that: the organic phase is a mixture of 10% Hostarex A324, 15% TOMAC, 15% n-heptanol and 60% 260# solvent oil by volume; in step 5, the reactant is replaced by sulfuric acid instead of alkaline sodium sulfate.

[0207] 5. Select the 1B route for back-extraction: The back-extraction agent for vanadium-rich organic back-extraction is a sulfuric acid solution with a pH value <1. Sulfur dioxide gas is introduced simultaneously during back-extraction to obtain vanadium oxysulfate back-extraction solution; the SO2 gas introduction rate is 1.5 times the theoretical consumption, and the O / A ratio of back-extraction is 1.5 / 1 to obtain vanadium oxysulfate back-extraction solution.

[0208] Steps 6-10 are the same as in Example 2;

[0209] 11. Purification of 1B:

[0210] The vanadium oxysulfate back-extraction solution obtained in step 5 is subjected to pH adjustment, filtration, secondary extraction, secondary washing, and secondary back-extraction to obtain a vanadium oxysulfate solution.

[0211] B Pre-processing:

[0212] The vanadium oxysulfate back-extraction solution obtained from back-extraction 1B was adjusted to pH 3 with alkali and then filtered to obtain the pre-extraction solution.

[0213] B Extraction:

[0214] B extraction uses a ratio of O / A = 2 / 1 to extract vanadium from the pre-extraction solution, and involves 5 stages of extraction. The volume fractions of each component in the extracted organic phase during B extraction include: 10% P2O4, 10% P5O7, 5% Cyanex 3O2, 5% TBP, and 70% 260# solvent oil.

[0215] B Washing:

[0216] After B extraction, vanadium-containing load and raffinate are obtained; the vanadium-containing load and the detergent used for B washing are washed in a ratio of O / A = 12 / 1, and the washing is carried out in 8 stages to obtain washed load and B washing effluent. The detergent used for B washing is a dilute sulfuric acid solution with a pH of 2. The effluent is combined with the B extraction section and used together with the pre-extraction liquid of B extraction as the feed liquid for B extraction. B washing can remove some impurities entrained in the vanadium-containing load and some of the extracted impurities.

[0217] B-reverse extraction:

[0218] After washing with B, the loading and the reaction agent of B back-extraction were compared with O / A = 6.5 / 1. After 5 stages of B back-extraction, a blank organic phase and a vanadium oxysulfate solution were obtained, in which the reaction agent was a 4 mol / L sulfuric acid solution and the vanadium concentration in the vanadium oxysulfate solution was 1.95 mol / L.

[0219] B Regeneration:

[0220] After B back-extraction, the blank organic phase is regenerated to obtain a recycled organic phase and regenerated water. The regenerated water can be used for the formulation of detergents and reaction agents.

[0221] The rest is the same as in Example 2.

[0222] Vanadium recovery rate >99.5%, molybdenum recovery rate 99.5%, and molybdate mass fraction in the solid after evaporation, concentration and crystallization >99.5%;

[0223] The purity of the prepared vanadium 3.5 electrolyte is >99.99%, and the contents of the main impurities are shown in the table below.

[0224]

[0225] Comparative Example 1

[0226] This comparative example discloses a method for preparing a vanadium electrolyte, which differs from Example 1 in that the pH of the vanadium molybdate solution is adjusted to 10 before vanadium extraction.

[0227] Under these conditions, the recovery rates of vanadium and molybdenum are both <50%, and the mass fraction of molybdate in the molybdenum product after evaporation, concentration and crystallization is only about 60%.

[0228] The vanadium concentration in the prepared vanadium electrolyte was <1.7 mol / L, and the purity of the vanadium electrolyte was basically the same as that in Example 1.

[0229] Comparative Example 2

[0230] This comparative example discloses a method for preparing a vanadium electrolyte, which differs from Example 1 in that the pH of the vanadium molybdate solution is adjusted to 5 before vanadium extraction.

[0231] Under these conditions, the recovery rate of vanadium and molybdenum is about 50%, and the mass fraction of vanadate and molybdate in the vanadium-molybdenum product after evaporation, concentration and crystallization is about 60%.

[0232] The vanadium concentration in the prepared vanadium electrolyte is <1.7 mol / L, and the purity of the vanadium electrolyte is about 70%, which is far below the product purity requirement (purity of Grade I vanadium electrolyte ≥99.9%).

[0233] Comparative Example 3

[0234] This comparative example discloses a method for preparing vanadium electrolyte. The difference from Example 1 is that the pH adjustment before vanadium extraction with vanadium molybdate solution is the same as in Example 1, while the pH of the molybdenum-rich raffinate is adjusted to 2 before molybdenum extraction. Under these conditions, the acid consumption and cost are increased, but the results have virtually no impact.

[0235] Comparative Example 4

[0236] This comparative example discloses a method for preparing vanadium electrolyte, which differs from Example 3 in that the pH value of the sodium sulfate solution in the detergent used for washing 1 is adjusted to 7;

[0237] Under these conditions, the recovery rates of vanadium and molybdenum decreased. The vanadium recovery rate was approximately 90%, with the vanadium product after evaporation, concentration, and crystallization containing approximately 90% vanadate by mass. The molybdenum recovery rate was approximately 80%, with the molybdenum product after evaporation, concentration, and crystallization containing approximately 90% molybdate by mass.

[0238] The vanadium concentration in the prepared vanadium electrolyte is <1.7 mol / L, and the purity of the vanadium electrolyte is about 90%, which is lower than the product purity requirement (purity of Grade I vanadium electrolyte ≥99.9%).

[0239] Comparative Example 5

[0240] This comparative example discloses a method for preparing vanadium electrolyte. The difference from Example 3 is that the pH value of the sodium sulfate solution in the detergent used in washing 2 is adjusted to 2. Under this condition, the acid consumption is increased, and the cost is increased.

[0241] Comparative Example 6

[0242] This comparative example discloses a method for preparing vanadium electrolyte, which differs from Example 3 in that: molybdenum is extracted first, and the molybdenum extraction residue is used for vanadium extraction.

[0243] Under these conditions, the recovery rates of vanadium and molybdenum are both <50%, and the mass fraction of vanadate in the vanadium product after evaporation, concentration, and crystallization is approximately 70%; the mass fraction of molybdate in the molybdenum product after evaporation, concentration, and crystallization is approximately 20%.

[0244] The vanadium concentration in the prepared vanadium electrolyte is <1.7 mol / L, and the purity of the vanadium electrolyte is about 70%, which is lower than the product purity requirement (purity of Grade I vanadium electrolyte ≥99.9%).

[0245] Comparative Example 7

[0246] This comparative example discloses a method for preparing vanadium electrolyte, which differs from Example 1 in that: a mixed extractant of quaternary ammonium salt and tertiary amine (R3N) extractant is used. The quaternary ammonium salt is the same as in Example 1, and the tertiary amine (R3N) is a tertiary amine extractant with a substituent C6 alkane group, and does not belong to one or more of the following: R=C8~C10 tertiary amine, R=isooctyl tertiary amine and N2O8.

[0247] Under these conditions, the recovery rates of vanadium and molybdenum decreased. The vanadium recovery rate was approximately 70%, and the mass fraction of vanadate in the vanadium product after evaporation, concentration, and crystallization was approximately 85%. The molybdenum recovery rate was approximately 50%, and the mass fraction of molybdate in the molybdenum product after evaporation, concentration, and crystallization was approximately 70%.

[0248] The vanadium concentration in the prepared vanadium electrolyte is <1.7 mol / L, and the purity of the vanadium electrolyte is about 90%, which is lower than the product purity requirement (purity of Grade I vanadium electrolyte ≥99.9%).

[0249] Comparative Example 8

[0250] This comparative example discloses a method for preparing vanadium electrolyte, which differs from Example 1 in that: a mixed extractant of quaternary ammonium salt and tertiary amine (R3N) is used. The tertiary amine (R3N) is the same as in Example 1. The substituent of the quaternary ammonium salt is a C6 alkane group, which does not belong to N263, Aliquat336, TOMAC or Adogen464.

[0251] Under these conditions, the recovery rates of vanadium and molybdenum decrease significantly. The vanadium recovery rate is approximately 35%, and the mass fraction of vanadate in the vanadium product after evaporation, concentration, and crystallization is approximately 60%. The molybdenum recovery rate is approximately 15%, and the mass fraction of molybdate in the molybdenum product after evaporation, concentration, and crystallization is approximately 35%.

[0252] The vanadium concentration in the prepared vanadium electrolyte is <1.7 mol / L, and the purity of the vanadium electrolyte is about 65%, which is lower than the product purity requirement.

[0253] Analysis of the above results shows that:

[0254] Examples 1-4 illustrate that this invention utilizes a limited extraction method to recover vanadium and molybdenum from the organic relative leachate, achieving a vanadium recovery rate ≥99.5%, with a vanadate mass fraction ≥99.5% in the vanadium product after evaporation, concentration, and crystallization; a molybdenum recovery rate ≥99.5%, with a molybdate mass fraction ≥99.5% in the molybdenum product after evaporation, concentration, and crystallization; a vanadium concentration >1.7 mol / L in the prepared vanadium electrolyte, and a vanadium electrolyte product purity ≥99.99%.

[0255] Comparing Example 1 and Comparative Examples 1-3, it can be seen that when the pH value of the vanadium-molybdenum extraction organic phase system is within a certain range, it helps to ensure that vanadium-molybdenum has good yield and purity at the same time, and has good overall economic efficiency.

[0256] Comparative Examples 3 and 4-5 show that when the pH value of the vanadium-molybdenum detergent is within a certain range, it helps to ensure that the vanadium-molybdenum has a good yield and purity, as well as good economic efficiency.

[0257] Comparing Example 3 and Comparative Example 6, it can be seen that Comparative Example 6 first extracts molybdenum and then uses the molybdenum extraction raffinate for vanadium extraction. Compared with Example 3, the molybdenum and vanadium yields and product purity are significantly lower, and the concentration and purity of the vanadium electrolyte also fail to meet the product qualification requirements.

[0258] Comparing Example 1 and Comparative Examples 7-8, it can be seen that Comparative Examples 7-8 used an undefined extraction method to recover vanadium and molybdenum elements from vanadium-molybdate solutions. Compared with Example 1, the yield of molybdenum and vanadium and the purity of the product were significantly lower, and the concentration and purity of the vanadium electrolyte also failed to meet the product qualification requirements.

[0259] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a vanadium electrolyte, characterized in that, include: Using vanadium molybdate solution as raw material, the extraction organic phase is used to sequentially extract and recover vanadium and molybdenum elements from the solution based on pH adjustment. The composition of the extraction organic phase is the same for vanadium and molybdenum element extraction. The recovered vanadium products are purified to prepare vanadium electrolyte.

2. The method for preparing vanadium electrolyte according to claim 1, characterized in that, The method for preparing the vanadium electrolyte includes: S1. Adjust the vanadium molybdate solution to alkaline, and use the extraction organic phase to extract the vanadium molybdate solution to obtain a vanadium-rich organic phase and a molybdenum-rich raffinate. S2. Adjust the molybdenum-rich raffinate to acidity, and use an extractive organic phase to extract the molybdenum-rich raffinate to obtain a molybdenum-rich organic phase and raffinate. S3. The vanadium-rich organic phase and the molybdenum-rich organic phase are back-extracted independently to obtain vanadium-rich back-extracting solution and molybdenum-rich back-extracting solution; S4. Prepare molybdenum products from molybdenum-rich back-extraction solution; further prepare vanadium products or vanadium electrolyte products from vanadium-rich back-extraction solution.

3. The method for preparing vanadium electrolyte according to claim 2, characterized in that, The vanadium-rich organic back-extraction agent in S3 is an alkaline sulfate aqueous solution with a pH value >11 or a sulfuric acid solution with a pH value <1, and / or the vanadium product is a vanadium-rich back-extraction solution, a vanadium product, or a vanadium oxysulfate back-extraction solution.

4. The method for preparing vanadium electrolyte according to claim 3, characterized in that, The vanadium-rich organic back-extraction agent in S3 is a sulfuric acid solution with a pH value <1. A gaseous reducing agent is introduced during back-extraction to obtain vanadium oxysulfate back-extraction solution.

5. The method for preparing vanadium electrolyte according to claim 4, characterized in that, The gaseous reducing agent is SO2, and the SO2 gas flow rate is 1 to 1.5 times the theoretical consumption; and / or, the O / A ratio in the back-extraction phase of S3 is 5 to 10 / 1.

6. The method for preparing vanadium electrolyte according to claim 3, characterized in that, The vanadium-rich organic back-extraction agent in S3 is an alkaline sulfate aqueous solution with a pH value > 11. Reducing agent B is added to the vanadium-rich back-extraction solution or the solution of the vanadium product to obtain vanadium oxysulfate reducing solution.

7. The method for preparing vanadium electrolyte according to claim 6, characterized in that, Reducing agent B is one or more of the following: sodium sulfide, sodium sulfite, sodium thiosulfate, sodium metabisulfite, sulfur dioxide, ascorbic acid, sodium nitrite, and oxalic acid.

8. The method for preparing vanadium electrolyte according to claim 7, characterized in that, The amount of reducing agent B introduced is 1 to 1.5 times the theoretical consumption.

9. The method for preparing vanadium electrolyte according to any one of claims 1-8, characterized in that, The purification process includes: pretreatment, extraction, washing, back-extraction, and regeneration.

10. A vanadium electrolyte, characterized in that, The vanadium electrolyte product prepared by the preparation method according to any one of claims 1-9 has a purity of ≥99.99%.

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