Vanadium electrolyte and preparation method of solid vanadyl sulfate

Abstract

The invention belongs to the technical field of all-vanadium redox flow batteries, and relates to a preparation method of a vanadium electrolyte and solid vanadyl sulfate, and the preparation method of the vanadium electrolyte comprises the following steps: based on pH value adjustment in a vanadium molybdate solution and a reverse extraction reagent, realizing co-extraction of vanadium and molybdenum elements in the vanadium molybdate solution by extracting an organic phase and sequential reverse extraction and recovery of the molybdenum and vanadium elements, the extraction organic phases for extracting vanadium and molybdenum elements have the same composition; and purifying the recovered vanadium product to prepare the vanadium electrolyte. The problems that in the prior art, synchronous recovery of various vanadium and molybdenum elements is difficult to achieve, the vanadium element is difficult to recycle, the vanadium recovery rate is low, the purity of recovered products is low, environmental pollution is large, the requirement for the purity of vanadium raw materials is high, the steps of a vanadium raw material purification preparation process are complex, and vanadium is difficult to separate from vanadium and molybdenum homologous materials are solved. The method overcomes the defects of low yield and low product purity caused by poor separation effect of elements in the vanadium molybdate solution in the prior art.

Description

Technical Field

[0001] The invention relates to the technical field of all-vanadium liquid flow batteries, and in particular to a preparation method of a vanadium electrolyte and solid vanadyl sulfate. Background Art

[0002] All-vanadium flow batteries have developed rapidly in recent years due to their advantages such as high energy storage power, many cycles, long service life, simple operation, safety and environmental protection, and low cost. Vanadium electrolyte is one of the important components of all-vanadium flow batteries, and its production costs such as production, packaging, and transportation largely determine the production cost of all-vanadium flow batteries. Therefore, in addition to reducing the preparation cost of vanadium electrolyte, reducing its packaging and transportation costs is also an urgent problem to be solved in the promotion and application of all-vanadium flow batteries. The solid vanadium sulfate preparation technology derived from this has also become a key technology to reduce the preparation cost of all-vanadium flow batteries.

[0003] At present, the common vanadium electrolyte preparation technologies are mainly chemical reduction and electrolysis, and V2O5 is mostly used as the vanadium raw material: on the one hand, this causes the price of vanadium electrolyte in vanadium flow batteries to be greatly affected by the fluctuation of vanadium price (V2O5), and V2O5 is mostly prepared by leaching, separation and precipitation of vanadium ore, which has a complex preparation process and high production cost; on the other hand, molybdenum is a common associated element with similar chemical properties to vanadium, and leaching is a common way to process vanadium ore. Vanadium molybdate solution contains both vanadium and molybdenum elements. It is very difficult to prepare vanadium electrolyte by purification in a short process using vanadium ore as raw material.

[0004] In addition, vanadium molybdate solution represented by vanadium-molybdenum ore vanadium molybdate solution is a common waste liquid or industrial product. For example, it can also be a solid waste treatment liquid containing molybdenum and vanadium. Due to the similar chemical properties of vanadium and molybdenum, how to effectively separate and extract molybdenum, vanadium and other elements and effectively recover and utilize the vanadium element has always been a difficult problem that has plagued the utilization of vanadium in vanadium molybdate solution.

[0005] In the prior art, ammonium salt precipitation method, sulfidation method, ion exchange method, solvent extraction method, etc. are commonly used to separate vanadium and molybdenum. The ammonium salt precipitation method is to use ammonium salt to precipitate vanadium in the form of ammonium metavanadate by controlling certain experimental conditions, so as to achieve the purpose of vanadium-molybdenum separation, but this method cannot precipitate vanadium deeply, the separation and purification effect is general, and the amount of ammonium salt used is large; the ion exchange method is complicated to operate, the amount of acid and alkali wastewater is large, and the resin adsorption capacity is small; the existing solvent extraction method also has many problems such as lengthy process, incomplete vanadium-molybdenum separation and insufficient product quality. The prior art has great difficulties in separating vanadium from vanadium-molybdenum homologous materials (such as vanadium molybdate solution) and preparing vanadium battery electrolyte. Summary of the invention

[0006] In view of the above analysis, the present invention aims to provide a method for preparing vanadium electrolyte and solid vanadyl sulfate, so as to solve at least one of the problems in the prior art, such as the difficulty in synchronously recovering various vanadium and molybdenum elements, the difficulty in recycling vanadium elements, the low vanadium recovery rate, the low purity of the recovered product, the large environmental pollution, the high requirement for the purity of vanadium raw materials, the complex process steps for purifying and preparing vanadium raw materials, the difficulty in transporting vanadium electrolyte, and the difficulty in separating vanadium from vanadium-molybdenum homologous materials.

[0007] The object of the present invention is mainly achieved through the following technical solutions:

[0008] The present invention discloses a method for preparing vanadium electrolyte, including:

[0009] S1. Obtain a vanadate solution, adjust the vanadate solution to be acidic, and use an extraction organic phase to extract the vanadate solution to achieve co-extraction of molybdenum and vanadium to obtain a molybdenum-vanadium-rich extraction organic phase;

[0010] S2. Add a stripping reagent to strip molybdenum, adjust the stripping reagent to be alkaline, and use the stripping reagent to strip the molybdenum-vanadium-rich extraction organic phase to obtain a vanadium-rich organic phase and a molybdenum-rich stripping solution;

[0011] S3. Add a stripping reagent to strip vanadium, adjust the stripping reagent to be more alkaline than the stripping reagent in step S2, strip the vanadium-rich organic phase to obtain a vanadium-rich stripping solution or a vanadium product, and further reduce the dissolution solution of the vanadium-rich stripping solution or the vanadium product further prepared from the vanadium-rich stripping solution to a tetravalent vanadium solution to obtain a vanadyl sulfate reduction solution; or, add a reducing agent and strip in an acidic environment, so that vanadium is separated from the extraction organic phase and reduced to a tetravalent vanadium solution to obtain a vanadyl sulfate stripping solution;

[0012] S4. Treat the molybdenum-rich stripping solution to obtain a molybdenum product; prepare a vanadium electrolyte from the vanadyl sulfate reduction solution or the vanadyl sulfate stripping solution.

[0013] Preferably, step S4 includes: sequentially performing secondary extraction, secondary washing, and secondary stripping on the vanadyl sulfate reduction solution or the vanadyl sulfate stripping solution, and then obtaining a 3.5-valent vanadium electrolyte product through purification and oil removal and electrolytic formulation.

[0014] Preferably, the extractant for the secondary extraction is one or more of P204, P507, Cyanex272, Cyanex301, and Cyanex302; and / or, the co-extractant is one or more of TBP, sec-octanol, and isooctanol; and / or, the diluent is 260# solvent oil.

[0015] Preferably, the stripping agent for stripping the vanadium-rich organic phase in step S3 is an alkaline sulfate aqueous solution with a pH value > 11 or a sulfuric acid solution with a pH value < 1.

[0016] Preferably, the method for preparing the vanadium electrolyte includes: in step S3, the stripping agent for the reverse extraction of the vanadium-rich organic phase is a sulfuric acid solution with a pH value < 1. A reducing agent is added during the reverse extraction to obtain a tetravalent vanadyl sulfate reverse extraction solution.

[0017] Preferably, the method for preparing the vanadium electrolyte includes: in step S3, the stripping agent for the reverse extraction of the vanadium-rich organic phase is an alkaline sulfate aqueous solution with a pH value > 11. A reducing agent is added to the vanadium-rich reverse extraction solution or the dissolution solution of the vanadium product to obtain a vanadyl sulfate reduction solution.

[0018] Preferably, adding a reducing agent to the vanadium-rich reverse extraction solution or the dissolution solution of the vanadium product to obtain a vanadyl sulfate reduction solution includes: gradually adding acid to the reverse extraction solution or the dissolution solution of the vanadium product to an acidic environment.

[0019] A method for preparing solid vanadyl sulfate includes:

[0020] S1’, obtaining a vanadate solution, adjusting the vanadate solution to acidic, and using an extraction organic phase to extract the vanadate solution to achieve co-extraction of molybdenum and vanadium to obtain a molybdenum-vanadium-rich extraction organic phase;

[0021] S2’, adding a stripping reagent to strip molybdenum, adjusting the stripping reagent to alkaline, and using the stripping reagent to strip the molybdenum-vanadium-rich extraction organic phase to obtain a vanadium-rich organic phase and a molybdenum-rich stripping solution;

[0022] S3’, adding a stripping reagent to strip vanadium, adjusting the stripping reagent to a stronger alkaline than the stripping reagent in step S2, stripping the vanadium-rich organic phase to obtain a vanadium-rich stripping solution or a vanadium product, and further reducing the vanadium-rich stripping solution or the dissolution solution of the vanadium product further prepared from the vanadium-rich stripping solution to a tetravalent vanadium solution to obtain a vanadyl sulfate reduction solution; or, adding a reducing agent and stripping in an acidic environment to separate vanadium from the extraction organic phase and reduce it to a tetravalent vanadium solution to obtain a vanadyl sulfate stripping solution;

[0023] S4’, preparing solid vanadyl sulfate from the vanadyl sulfate reduction solution or vanadyl sulfate stripping solution obtained in step S3’.

[0024] A solid vanadyl sulfate, prepared by the above method for preparing solid vanadyl sulfate, and the purity of the solid vanadyl sulfate ≥ 99.99%.

[0025] An application of a vanadate solution includes: using the above method for preparing the vanadium electrolyte, or the above method for preparing solid vanadyl sulfate, and using the vanadium product obtained after separating vanadium and molybdenum elements in the vanadate solution to prepare a vanadium electrolyte or solid vanadyl sulfate.

[0026] Compared with the prior art, the present invention can at least achieve one of the following beneficial effects:

[0027] (1) By adjusting the pH value in the vanadium molybdate solution, the present invention realizes that the extraction organic phase has high selectivity for vanadium and molybdenum elements simultaneously, achieving the separation of vanadium and molybdenum elements from impurities; and further through secondary purification, solid vanadyl sulfate meeting the requirements for the preparation of vanadium electrolyte and a vanadium electrolyte product superior to the national standard requirements are prepared, realizing the separation and purification of vanadium from the common industrial products or intermediate processing product vanadium-molybdenum mixed solution and the preparation of vanadium electrolyte, greatly simplifying the vanadium purification process compared with the prior art, greatly expanding the source of vanadium, reducing the cost and the dependence on vanadium pentoxide.

[0028] (2) By adjusting the pH value in the vanadium molybdate solution, the present invention realizes that the extraction organic phase has high selectivity for vanadium and molybdenum elements simultaneously, achieving the separation of vanadium and molybdenum elements from impurities; improving the separation effect of vanadium and molybdenum elements from impurities and the purity; the recovery rate of molybdenum is greater than 99.5%, preferably greater than 99.75%; the mass fraction of molybdate in the molybdenum product after evaporation, concentration and crystallization is greater than 99.5%, preferably greater than 99.58%; the recovery rate of vanadium is greater than 99.5%, preferably greater than 99.82%; the mass fraction of vanadate in the vanadium product after evaporation, concentration and crystallization is greater than 99.5%, preferably greater than 99.59%; at the same time, improving the post-treatment process of vanadium products realizes the preparation of high-purity vanadium battery electrolyte (the purity of the vanadium electrolyte product is above 99.99% and the content of main impurities is below 10 mg / L) and the preparation of high-purity solid vanadyl sulfate (the purity of the solid vanadyl sulfate product is above 99.99%);

[0029] (3) The present invention prepares a vanadyl sulfate stripping solution during the vanadium stripping process or reduces a vanadium-rich stripping solution or a dissolution solution for further preparing vanadium products from the vanadium-rich stripping solution to prepare a vanadyl sulfate reduction solution, and further prepares solid vanadyl sulfate from the vanadyl sulfate stripping solution and the vanadyl sulfate reduction solution, and transports and stores the solid vanadyl sulfate as a raw material for the preparation of vanadium electrolyte, overcoming the defects of large volume and difficult transportation of vanadium electrolyte in the prior art;

[0030] (4) By further adjusting the pH value in the stripping reagent, the present invention realizes the change of the selectivity of the same extraction organic phase for vanadium and molybdenum elements. While ensuring the extraction separation effect, the sequential reverse extraction and recovery of molybdenum and vanadium in the vanadium molybdate solution are realized, and at the same time, the defects of low yield and low product purity caused by poor separation effect of each element in the vanadium molybdate solution in the prior art are overcome;

[0031] (5) The present invention refluxes the raffinate to prepare a vanadium molybdate solution. On the one hand, it avoids the waste of vanadium and molybdenum elements and improves the recovery rate of vanadium and molybdenum elements; on the other hand, the enrichment of various precious metal elements is realized during the reflux process of the raffinate, facilitating the recovery of precious metal elements; at the same time, the waste liquid discharge is reduced, and the environmental pollution and cost are lowered;

[0032] (6) The present invention realizes the co-extraction of two elements by using the same extraction organic phase, avoiding the pollution caused by the residual extraction phase in the raffinate when different extraction systems are used for different elements; at the same time, since the extraction organic phase is the same, the extraction organic phase after stripping treatment can be recycled without worrying about mutual contamination of the extraction systems, reducing waste liquid discharge and environmental pollution;

[0033] (7) The present invention controls the pH value during the washing and purification of the extraction phase, so as to reduce the elution of molybdenum and vanadium during washing and purification while removing impurities, and improve the recovery rates of the two elements.

[0034] In the present invention, the above technical solutions can also be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present invention will be described in the subsequent specification, and some advantages can be made obvious from the specification or understood by implementing the present invention. The objectives and other advantages of the present invention can be achieved and obtained from the content specifically pointed out in the embodiments of the specification and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The drawings are only for the purpose of showing specific embodiments and are not considered as limiting the present invention. Throughout the drawings, the same reference signs denote the same components.

[0036] Figure 1 It is a process flow diagram of the preparation method of the vanadium electrolyte of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0037] The following will specifically describe the preferred embodiments of the present invention with reference to the drawings. The drawings form a part of the present invention and are used together with the embodiments of the present invention to explain the principle of the present invention, rather than to limit the scope of the present invention.

[0038] In a first aspect, the present invention discloses a method for preparing a vanadium electrolyte, including:

[0039] Based on the pH value adjustment of the vanadate solution, realizing the co-extraction of vanadium and molybdenum elements in the vanadate solution by the extraction organic phase;

[0040] Based on the pH value adjustment of the stripping reagent, realizing the sequential stripping and recovery of molybdenum and vanadium elements; wherein, the compositions of the extraction organic phases for extracting vanadium and molybdenum elements are the same;

[0041] Purifying the recovered vanadium product and then preparing a vanadium electrolyte.

[0042] During implementation, the present invention preferentially realizes the co-extraction of vanadium and molybdenum elements in an acidic environment, and sequentially strips molybdenum and vanadium in an alkaline environment to realize the separation of molybdenum and vanadium; further, the recovered vanadium product is purified and then a vanadium electrolyte is prepared.

[0043] Compared with the prior art, the present invention realizes that the extraction organic phase has high selectivity for vanadium and molybdenum elements simultaneously by adjusting the pH value in the vanadomolybdate solution, and realizes the separation of vanadium and molybdenum elements from impurities; and further prepares solid vanadyl sulfate meeting the requirements for the preparation of vanadium electrolyte and a vanadium electrolyte product superior to the national standard requirements through secondary purification, realizing the separation and purification of vanadium from the common industrial products or intermediate processed product vanadium-molybdenum mixed solution and the preparation of vanadium electrolyte, greatly simplifying the vanadium purification process compared with the prior art, greatly expanding the source of vanadium, reducing the cost and the dependence on vanadium pentoxide.

[0044] Preferably, vanadium in the recovered vanadium product exists mostly in the form of V valence or IV valence; the average valence state of vanadium in the vanadium electrolyte is 3.5 valence, and the valence state of vanadium in vanadyl sulfate is 4 valence; it is necessary to adjust the valence of vanadium element when preparing vanadium electrolyte or vanadyl sulfate from the recovered vanadium product.

[0045] It should be noted that vanadium in the vanadomolybdate solution is mostly vanadium of V valence, the average valence state of vanadium in the vanadium electrolyte is 3.5 valence, and the valence state of vanadium in vanadyl sulfate is 4 valence. When using the extraction organic phase to extract vanadium in the solution and then prepare vanadium electrolyte or vanadyl sulfate, it is necessary to adjust the valence of vanadium.

[0046] Specifically, the preparation method of the vanadium electrolyte includes:

[0047] Realize the co-extraction of vanadium and molybdenum elements by using the extraction organic phase under acidic conditions;

[0048] Strip molybdenum under alkaline environment to realize the separation of molybdenum from the vanadium-rich extraction organic phase;

[0049] When stripping vanadium relative to molybdenum, strip vanadium under a stronger alkaline environment to separate vanadium from the extraction organic phase, and further reduce the dissolved solution of the vanadium-rich stripping solution or the vanadium product further prepared from the vanadium-rich stripping solution to a vanadium solution of IV valence to obtain a vanadyl sulfate reduction solution; or, add a reducing agent and strip under acidic environment to separate vanadium from the extraction organic phase and reduce it to a vanadium solution of IV valence to obtain a vanadyl sulfate stripping solution;

[0050] Prepare vanadium electrolyte from the vanadyl sulfate reduction solution and the vanadyl sulfate stripping solution.

[0051] Compared with the prior art, the present invention realizes the selective change of the same extraction organic phase for vanadium and molybdenum elements by further adjusting the pH value in the stripping reagent. While ensuring the extraction separation effect, the sequential separate stripping and recovery of molybdenum and vanadium in the vanadium molybdate solution are achieved. The recovery rate of vanadium is ≥99.5%, and the mass fraction of vanadate in the vanadium product after evaporation, concentration and crystallization is ≥99.5%; the recovery rate of molybdenum is ≥99.5%, and the mass fraction of molybdate in the molybdenum product after evaporation, concentration and crystallization is ≥99.5%. The present invention further prepares solid vanadyl sulfate meeting the requirements for the preparation of vanadium electrolyte and a vanadium electrolyte product superior to the national standard requirements through secondary purification. The purity of the vanadium electrolyte product is ≥99.99%, and the purity of the solid vanadyl sulfate product is ≥99.99%. At the same time, the defects of low yield and low product purity caused by poor separation effect of each element in the vanadium molybdate solution in the prior art are overcome.

[0052] It should be noted that the present invention uses the same extraction organic phase to extract two elements, avoiding the pollution caused by the residual extraction phase in the raffinate when different extraction systems are used for different elements. At the same time, due to the same extraction organic phase, the extraction organic phase after stripping treatment can be recycled without worrying about mutual pollution of the extraction systems, reducing waste liquid discharge and environmental pollution.

[0053] Preferably, the pH value of the vanadium molybdate solution required for the co-extraction of vanadium and molybdenum elements is 3-4.

[0054] It should be noted that the applicant's research found that when the pH value is 2-9, vanadium in the vanadium molybdate solution exists in the forms of V4O 12 4- , V3O9 3- , V2O7 4- , VO3 - and various polymerized polyacid anions, such as HV 10 O 28 5- , H2V 10 O 28 4- and so on. The extraction organic phase has extremely high extraction selectivity for its existing forms. When the pH value <2 and the pH value >10, the extraction rate of vanadium by the extraction organic phase drops significantly. When the pH value <4, molybdenum in the molybdenum-rich raffinate exists in various polymerized polyacid anions, such as Mo2O7 2- , Mo3O 10 2- , Mo4O 13 2- , Mo7O 24 6- (or HMo7O 24 5- , H3Mo7O 24 3- ), Mo8O26 4- and exists in the form of a cationic polymer under strong acidic conditions. The extraction organic phase has extremely high extraction selectivity for various polyacid root ions of its polymers. When 4 < pH < 8, the extraction rate of molybdenum by the extraction organic phase gradually decreases. When pH > 8, the extraction rate of molybdenum by the extraction organic phase drops significantly. Therefore, when the pH value of the vanadium molybdate solution is 3 - 4, the extraction organic phase has good selectivity for both molybdenum and vanadium, and the co - extraction of the two elements can be achieved.

[0055] Specifically, the extraction organic phase includes a quaternary ammonium salt extractant or a mixture of a quaternary ammonium salt extractant and a tertiary amine extractant.

[0056] Preferably, the volume ratio of the quaternary ammonium salt extractant to the tertiary amine extractant is 1.5 - 4:1.

[0057] Preferably, the tertiary amine extractant is one or more of a tertiary amine with substituents of C8 - C10, a tertiary amine with an isooctyl substituent, and N208.

[0058] Preferably, the tertiary amine with substituents of C8 - C10 is any one of N235, Alamine336, Adogen364, HostarexA327, and TOA.

[0059] Preferably, the tertiary amine with an isooctyl substituent is any one of Adogen381, Alamine308, HostarexA324, and Adogen382.

[0060] Preferably, the quaternary ammonium salt extractant is one or more of N263, Aliquat336, TOMAC, and Adogen464.

[0061] Preferably, the extraction organic phase further includes an alcohol phase regulator with 7 - 10 carbon atoms.

[0062] Specifically, the alcohol phase regulator can be one or more of n - heptanol, n - octanol, sec - octanol, isooctanol, and n - decanol.

[0063] It should be noted that on the one hand, the alcohol phase regulator can improve the performance of the extraction system and increase the extraction efficiency; on the other hand, it can reduce the water solubility of the extraction system and reduce the loss of the extractant; in addition, it can also optimize the extraction system to prevent emulsification and the formation of a third phase.

[0064] It should be noted that the alcohol phase regulator with 7 - 10 carbon atoms has the advantages of strong fluidity, low water solubility, and low cost.

[0065] Preferably, the extraction organic phase further includes a diluent with low viscosity, which is used to improve the relative fluidity of the organic phase and the aqueous phase during extraction, and enhance the contact and ion exchange effects.

[0066] Preferably, the diluent can be No. 260 solvent oil.

[0067] Specifically, the volume ratio of the extractant, phase regulator, and diluent in the extraction organic phase satisfies: extractant 10 - 40%; phase regulator 5 - 20%; diluent 40 - 85%.

[0068] Specifically, the volume fraction of the extractant in the extraction 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%.

[0069] Specifically, the volume fraction of the phase regulator in the extraction organic phase can be 5%, 6%, 7%, 8%, 9%, 10%, 12%, 14%, 15%, 16%, 18%, or 20%.

[0070] Specifically, the volume fraction of the diluent in the extraction 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%.

[0071] Specifically, as Figure 1 shown, the method for preparing the vanadium electrolyte includes:

[0072] S1. Obtain a vanadium molybdate solution, adjust the vanadium molybdate solution to be acidic, and use the extraction organic phase to extract the vanadium molybdate solution to achieve co - extraction of molybdenum and vanadium to obtain a molybdenum - vanadium - rich extraction organic phase;

[0073] S2. Add an anti - extraction reagent to anti - extract molybdenum, adjust the anti - extraction reagent to be alkaline, and use the anti - extraction reagent to anti - extract the molybdenum - vanadium - rich extraction organic phase to obtain a vanadium - rich organic phase and a molybdenum - rich anti - extraction solution;

[0074] S3. Add stripping reagent to strip vanadium, adjust the stripping reagent to a stronger alkaline than that in step S2, strip the vanadium-rich organic phase to obtain a vanadium-rich stripping solution or vanadium product, and further reduce the vanadium-rich stripping solution or the dissolution solution of the vanadium product further prepared from the vanadium-rich stripping solution to a vanadium solution of valence IV to obtain a vanadyl sulfate reduction solution; or, add a reducing agent and strip in an acidic environment so that vanadium is separated from the extraction organic phase and reduced to a vanadium solution of valence IV to obtain a vanadyl sulfate stripping solution;

[0075] S4. Treat the molybdenum-rich stripping solution to obtain a molybdenum product; prepare a vanadium electrolyte from the vanadyl sulfate reduction solution or the vanadyl sulfate stripping solution.

[0076] Specifically, in S1, adjust the pH value of the vanadium molybdate solution to 3-4.

[0077] Specifically, in S1, the phase ratio of extraction is O / A = 1:5-5:1, and the number of extraction stages is 2-5 stages.

[0078] Specifically, in S2, adjust the pH value of the stripping reagent to 8-9.

[0079] Specifically, in S2, the phase ratio of molybdenum stripping is O / A = 1-10:1, and the number of stages is 2-8 stages.

[0080] Specifically, in S3, adjust the pH value of the stripping reagent to >11.

[0081] Specifically, in S3, the phase ratio of vanadium stripping is O / A = 1-10:1, and the number of stripping stages is 2-5 stages.

[0082] Specifically, the stripping agent for stripping the vanadium-rich organic phase in S3 is an aqueous solution of alkaline sulfate with pH>11 or a sulfuric acid solution with pH<1.

[0083] It should be noted that when the pH value is <2 and the pH value is >10, the extraction rate of vanadium by the extraction organic phase drops significantly. Within this range, the stripping agent can strip vanadium compounds from the extraction organic phase to achieve the separation of vanadium from the organic phase and the enrichment of vanadium.

[0084] Specifically, the alkaline sulfate can be sodium sulfate or potassium sulfate.

[0085] In a preferred embodiment, the stripping agent for stripping the vanadium-rich organic phase in S3 is a sulfuric acid solution with pH<1, and a reducing agent is added during stripping to obtain a vanadyl sulfate stripping solution.

[0086] In another preferred embodiment, the stripping agent for stripping the vanadium-rich organic phase in S3 is an aqueous solution of alkaline sulfate with pH>11, and a reducing agent is added to the vanadium-rich stripping solution or the dissolution solution of the vanadium product to obtain a vanadyl sulfate reduction solution.

[0087] Specifically, the reducing agent can be one or more of sodium sulfide, sodium sulfite, sodium thiosulfate, sodium metabisulfite, sulfur dioxide, ascorbic acid, sodium nitrite, and oxalic acid. The rich-vanadium stripping solution or the dissolution solution of the vanadium product is gradually acidified to an acidic environment, during which the reducing agent can effectively reduce vanadium(V) to vanadium(IV).

[0088] Specifically, the feeding amount of the reducing agent is 1 to 1.5 times the theoretical consumption amount, and the stripping phase ratio O / A = 5 to 10 / 1.

[0089] Specifically, the rich-vanadium stripping solution or the dissolution solution of the vanadium product is acidified to an acidic environment with a final pH value of 1 to 1.5, which is conducive to the complete progress of the reduction reaction.

[0090] The above two implementation methods respectively obtain the vanadyl sulfate stripping solution and the vanadyl sulfate reduction solution. After filtration, secondary extraction, secondary washing, and secondary stripping are carried out in sequence, and then after purification and degreasing, and electrolytic formulation, a 3.5-valent vanadium electrolyte product is obtained with a purity of the vanadium electrolyte product ≥ 99.99%; or after filtration, secondary extraction, secondary washing, and secondary stripping are carried out in sequence, and then after purification and degreasing, and evaporation and concentration, a solid vanadyl sulfate product is obtained with a purity of the vanadyl sulfate product ≥ 99.99%.

[0091] Specifically, the pH value of the vanadyl sulfate stripping solution and the vanadyl sulfate reduction solution is adjusted to 2 to 3 and then filtered.

[0092] It should be noted that filtering after adjusting the pH value of the vanadyl sulfate stripping solution and the vanadyl sulfate reduction solution to 2 to 3 can further remove impurity ions.

[0093] It should be noted that the pre-extraction solution is obtained after adjusting the pH value of the vanadyl sulfate stripping solution and the vanadyl sulfate reduction solution and filtering.

[0094] Specifically, in the secondary extraction, vanadium in the pre-extraction solution of the secondary extraction is extracted with a phase ratio O / A = 1 to 3 / 1, and the extraction is carried out in 2 to 8 stages.

[0095] Specifically, the volume fractions of each component in the extraction organic phase in the secondary extraction include: 10% to 40% of phosphoric acid ester extractants, 5% to 20% of TBP, and 40% to 85% of 260# solvent oil.

[0096] Specifically, the extractant in the secondary extraction can be one or more of P204, P507, Cyanex272, Cyanex301, and Cyanex302; the synergistic extractant can be one or more of TBP, sec-octanol, and isooctanol; the diluent can be 260# solvent oil.

[0097] Specifically, after secondary extraction, a vanadium-containing load and a raffinate are obtained; the vanadium-containing load and the detergent for secondary washing are in an O / A ratio of 5-20 / 1, and after 2-10 stages of washing, a washed load and secondary washing effluent are obtained. The detergent for secondary washing is a dilute sulfuric acid solution with a pH value of 1-3. The washing effluent is combined into the secondary extraction section and used as the feed liquid for secondary extraction together with the pre-extraction liquid of secondary extraction. Secondary washing can elute some impurities entrained and extracted in the vanadium-containing load.

[0098] Specifically, the load after secondary washing and the stripping agent for secondary stripping are in an O / A ratio of 5-15 / 1, and after 2-10 stages of secondary stripping, a blank organic phase and a vanadyl sulfate stripping solution are obtained. The stripping agent is a sulfuric acid solution with a concentration of 3 mol / L to 5 mol / L, and the vanadium concentration in the vanadyl sulfate stripping solution > 1.7 mol / L.

[0099] Further preferably, after secondary stripping, the extraction organic phase is regenerated twice to obtain a recycled organic phase and regeneration water, and the regeneration water can be used for the preparation of the detergent and the stripping agent.

[0100] Specifically, the purification and oil removal process satisfies that the obtained vanadyl sulfate solution is subjected to adsorption treatment to obtain a vanadium solution after purification and oil removal, and at this time, the oil content in the vanadium solution < 1 ppm.

[0101] Specifically, the electrolysis and preparation include: after electrolysis treatment at a certain current density based on charge balance, a vanadium electrolyte product with a valence of 3.5 is obtained.

[0102] Preferably, before S1, it further includes:

[0103] S0. Acid-treat the extraction organic phase to transform it to obtain an activated quaternary ammonium salt.

[0104] Specifically, S0 includes:

[0105] S001. Mix the extractant, phase modifier, and diluent evenly according to a set volume ratio to obtain an extraction organic phase;

[0106] S002. Wash and treat the extraction organic phase obtained in S001 with a sulfuric acid solution with a concentration of 1 mol / L to 2 mol / L;

[0107] S003. Further wash the extraction organic phase treated in S002 until it is neutral.

[0108] Preferably, before S2, there is also a step of washing and removing impurities from the molybdenum-rich vanadium extraction organic phase, refluxing the washing effluent, and mixing it with the vanadate solution adjusted to acidity as the feed liquid for the water phase of the extraction section.

[0109] Specifically, the pH value of the detergent ≥ the pH value after adjustment of the vanadate solution in step S1.

[0110] Preferably, the pH value of the detergent is 4 to 4.5.

[0111] Preferably, the detergent is a sulfuric acid solution.

[0112] Specifically, when washing and removing impurities from the molybdenum-rich vanadium extraction organic phase, the phase ratio O / A = 5 to 15 / 1, and the number of stages is 1 to 5.

[0113] Preferably, after S2, there is also a step of purifying and removing impurities from the vanadium-rich extraction organic phase, adjusting the pH value of the purified effluent, and then refluxing it to the water phase inlet of the washing section to be used as a detergent.

[0114] Specifically, the purifying agent for the vanadium-rich extraction organic phase is an alkaline solution.

[0115] Specifically, when purifying and removing impurities from the vanadium-rich extraction organic phase, O / A = 5 to 15:1, and the number of stages is 1 to 5.

[0116] Specifically, the pH value of the purifying agent for the vanadium-rich extraction organic phase is ≥ the pH value of the stripping reagent for stripping molybdenum in S2.

[0117] Preferably, the pH value of the purifying agent for the vanadium-rich extraction organic phase can be 9 to 10.

[0118] It should be noted that within this pH range, while ensuring a relatively low elution efficiency for vanadium, it can effectively wash away the molybdenum entrained in the vanadium-rich organic phase, which is beneficial to enriching and purifying the vanadium-rich stripping solution at the back end. When pH < 9, there will be an incomplete molybdenum elution in the vanadium-rich organic phase, resulting in a decrease in the purity of the vanadium-rich stripping solution; when pH > 10, there will be a relatively high elution rate of vanadium in the vanadium-rich organic phase, resulting in a decrease in the vanadium recovery rate.

[0119] Preferably, the preparation method of the vanadium electrolyte and solid vanadyl sulfate further includes:

[0120] Washing and regenerating the blank organic phase obtained by S4 extraction with water and then refluxing it as the extraction organic phase.

[0121] Specifically, the phase ratio O / A for washing and regenerating the blank organic phase with water is 5 to 20:1, and the number of stages is 1 to 2. Preferably, the preparation method of the vanadium electrolyte and solid vanadyl sulfate further includes:

[0122] S5. Refluxing the raffinate for preparing a vanadate solution to recover the unextracted vanadium and molybdenum, and concentrating the other precious metals except vanadium and molybdenum.

[0123] 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 recovery rate of vanadium and molybdenum elements; at the same time, the other metal elements except vanadium and molybdenum in the vanadate solution are not extracted by the extraction organic phase and accumulate continuously during the reflux process of the raffinate, realizing the enrichment of various precious metal elements and providing a high-grade raw material for the recovery of the other precious metal elements.

[0124] Compared with the prior art, the present invention recycles the raffinate to prepare the vanadomolybdate solution. On the one hand, it avoids the waste of vanadium and molybdenum elements and improves the recovery rates of vanadium and molybdenum elements. On the other hand, during the recycling process of the raffinate, various precious metal elements are enriched, which is convenient for the recovery of precious metal elements.

[0125] In the second aspect, the present invention discloses a method for preparing solid vanadyl sulfate, which includes all the features of steps S0, S1, S2, S3 and S5 in the method for preparing vanadium electrolyte, and is different from the method for preparing vanadium electrolyte in that step S4 is replaced by the following step S4':

[0126] S4': Preparing solid vanadyl sulfate from the vanadyl sulfate reduction solution or vanadyl sulfate stripping solution obtained in step S3.

[0127] Specifically, in the evaporation and concentration process, the vanadium solution obtained after purification and degreasing is evaporated and concentrated and then cooled and crystallized to obtain a solid vanadyl sulfate product.

[0128] Compared with the prior art, the present invention realizes the selective change of the same extraction organic phase for vanadium and molybdenum elements by further adjusting the pH value in the stripping reagent. While ensuring the extraction and separation effect, it realizes the sequential stripping and recovery of molybdenum and vanadium in the vanadomolybdate solution. The recovery rate of vanadium is ≥99.5%, and the mass fraction of vanadate in the vanadium product after evaporation, concentration and crystallization is ≥99.5%; the recovery rate of molybdenum is ≥99.5%, and the mass fraction of molybdate in the molybdenum product after evaporation, concentration and crystallization is ≥99.5%. The present invention further prepares solid vanadyl sulfate that meets the requirements for preparing vanadium electrolyte through secondary purification, and the purity of the solid vanadyl sulfate product is ≥99.99%.

[0129] Compared with the prior art, the present invention prepares a vanadyl sulfate stripping solution during the vanadium stripping process or reduces the dissolution solution of the vanadium-rich stripping solution or the vanadium product further prepared from the vanadium-rich stripping solution to prepare a vanadyl sulfate reduction solution, and further prepares solid vanadyl sulfate from the vanadyl sulfate stripping solution and the vanadyl sulfate reduction solution, and transports and stores the solid vanadyl sulfate as a raw material for preparing vanadium electrolyte, overcoming the defects of large volume and difficult transportation of vanadium electrolyte in the prior art.

[0130] In the third aspect, the present invention discloses a solid vanadyl sulfate, which is prepared by the above method for preparing solid vanadyl sulfate.

[0131] In the fourth aspect, the present invention discloses an application of a vanadomolybdate solution, including: using the vanadium obtained after separating vanadium and molybdenum elements in the vanadomolybdate solution (such as HDS waste catalyst leaching solution or vanadinite leaching solution) by the above method to prepare vanadium electrolyte or solid vanadyl sulfate.

[0132] Specifically, the HDS waste catalyst or vanadinite and its leaching solution in the present invention satisfy Table 1:

[0133] Table 1 Composition Table of HDS Waste Catalyst or Vanadinite and Its Leaching Solution

[0134]

[0135]

[0136] Example 1

[0137] This example discloses a preparation method of vanadium electrolyte, as Figure 1 shown, including:

[0138] 1. Solution pretreatment (vanadomolybdate): The vanadomolybdate solution is obtained by subjecting the HDS waste catalyst to alkali leaching treatment and performing conventional industrial impurity removal, and adjusting the pH of the solution to 3.8 with concentrated sulfuric acid. The Mo content in the solution is 11.3 g / L, and the V content is 6.9 g / L;

[0139] 2. Organic phase pretreatment: The organic phase is composed of a mixture of 5% by volume of Alamine 336, 20% of N263, 10% of sec-octanol, and 65% of solvent oil 260#; The organic phase is treated 6 times with 2 mol / L sulfuric acid solution at a phase ratio of O / A = 1 / 1, and then washed with deionized water until nearly neutral;

[0140] 3. Extraction: The pretreated organic phase is mixed and extracted with the pretreated vanadomolybdate solution at a phase ratio of O / A = 1.3 / 1, and the extraction stage number is 3 stages, obtaining vanadium-molybdenum loaded 1 and raffinate. The vanadium content in the raffinate is 6 ppm, and the molybdenum content is 13 ppm;

[0141] 4. Washing: The washing agent used for washing is a dilute sulfuric acid solution with a pH of 4.2, the washing phase ratio O / A = 10 / 1, and the washing stage number is 3 stages, obtaining vanadium-molybdenum loaded 2 and wash water. The wash water is refluxed to the water phase inlet of the extraction section and enters the extraction section together with the solution after pretreatment;

[0142] 5. Anti-molybdenum: The anti-agent used for anti-molybdenum is a sodium sulfate solution with a pH of 8.7, the sodium sulfate concentration is 0.15 mol / L, the phase ratio O / A = 5 / 1, and the stage number is 6 stages, obtaining vanadium loaded 1 and molybdenum-rich stripping solution. The molybdenum concentration in the molybdenum-rich stripping solution is 43.41 g / L, and the corresponding molybdenum recovery rate is 99.88%. The mass fraction of molybdate in the solid after evaporation, concentration, and crystallization is 99.62%;

[0143] 6. Purification: The purifying agent used for purification is an alkaline solution with a pH of 9.6. With a phase ratio of O / A = 10 / 1 and a purification stage of 3, a vanadium-loaded phase 2 and a purified solution are obtained. After adjusting the pH of the purified solution, it is recycled to the water phase inlet of the washing section as a detergent for recycling.

[0144] 7. Selection of the stripping route for stripping vanadium 1A: The stripping agent used for stripping vanadium 1A is a sodium sulfate solution with a pH of 12.8 and a sodium sulfate concentration of 0.15 mol / L. With a phase ratio of O / A = 5 / 1 and a stage of 3, a blank organic phase and a vanadium-rich stripping solution are obtained. The vanadium concentration in the vanadium-rich stripping solution is 26.52 g / L, and the corresponding vanadium recovery rate is 99.91%. The mass fraction of vanadate in the solid after evaporation, concentration, and crystallization is 99.59%.

[0145] 8. Regeneration of 1A: Pure water is used for the regeneration of 1A with a phase ratio of O / A = 6 / 1 and a regeneration stage of 1. The pH of the effluent from the regeneration of 1A is controlled to be near neutral to obtain a recycled organic phase after regeneration. Without repeating the pretreatment of the organic phase, it can be directly returned to the organic phase inlet of the extraction section for recycling.

[0146] 9. Purification of 1A:

[0147] The vanadium-rich stripping solution obtained by stripping 1A in step 7 is treated by purification of 1A to obtain a vanadyl sulfate solution.

[0148] Purification of 1A includes pretreatment, extraction, washing, stripping, and regeneration steps.

[0149] A Pretreatment:

[0150] After dissolving the vanadium-rich stripping solution obtained by stripping 1A or vanadium products, sodium sulfite is added as a reducing agent at 1.2 times the theoretical dosage; 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 2.3 and filtration is carried out to obtain a solution before extraction.

[0151] A Extraction:

[0152] A extraction extracts vanadium from the solution before extraction with a phase ratio of O / A = 1.5 / 1 through 5 stages of extraction; the volume fractions of each component in the extraction organic phase during A extraction include: 15% P204, 15% P507, 5% TBP, and 65% solvent oil 260#.

[0153] A Washing:

[0154] After A extraction, a vanadium-loaded phase and a raffinate are obtained; the vanadium-loaded phase and the detergent for A washing are in a phase ratio of O / A = 15 / 1, and after 7 stages of washing, a washed load and the effluent from A washing are obtained. The detergent for A washing is a dilute sulfuric acid solution with a pH value of 3, and the effluent is combined into the A extraction section and used as the feed liquid for A extraction together with the solution before A extraction. A washing can elute some impurities entrained and extracted in the vanadium-loaded phase.

[0155] A stripping:

[0156] The loaded organic phase after washing and the stripping agent for A stripping are in a ratio of O / A = 6 / 1. After 6 - stage A stripping, a blank organic phase and a vanadyl sulfate solution are obtained. The stripping agent is a 4 mol / L sulfuric acid solution, and the vanadium concentration in the vanadyl sulfate solution is 2.08 mol / L;

[0157] A regeneration:

[0158] The blank organic phase after A stripping is regenerated to obtain a recycled organic phase and regenerated water, and the regenerated water can be used for the preparation of the detergent and the stripping agent.

[0159] 10. Purification and oil removal 1A: The vanadyl sulfate solution enters the purification and oil removal system. After purification and oil removal, the oil content in the vanadyl sulfate solution is < 1 ppm;

[0160] 11. Electrolytic preparation 1A: The vanadyl sulfate solution after oil removal is electrolytically prepared to obtain a vanadium electrolyte product with a valence of 3.5.

[0161] The purity of the prepared vanadium electrolyte with a valence of 3.5 is > 99.99%, and the main impurity contents are shown in the following table.

[0162]

[0163] This example also discloses a preparation method of solid vanadyl sulfate, which is different from the preparation method of the vanadium electrolyte in that:

[0164] Vanadyl sulfate is prepared from the vanadyl sulfate reduction solution obtained above; during the evaporation and concentration process, the vanadium solution obtained after purification and oil removal is evaporated and concentrated and then cooled and crystallized to obtain a solid vanadyl sulfate product, and the purity of the solid vanadyl sulfate is ≥ 99.99%.

[0165] This example also discloses a solid vanadyl sulfate prepared by the above - mentioned preparation method of solid vanadyl sulfate.

[0166] This example also discloses an application of a vanadate solution, including: using the vanadium product obtained after separating vanadium and molybdenum elements in the vanadate solution (such as the leaching solution of HDS waste catalyst or the leaching solution of vanadinite) by the above method to prepare a vanadium electrolyte or solid vanadyl sulfate.

[0167] Example 2

[0168] This example discloses a preparation method of a vanadium electrolyte, as Figure 1 shown, including:

[0169] 1. Pretreatment of the solution (vanadomolybdate): The vanadomolybdate solution is obtained by treating vanadinite with the acid leaching method to recover Pb and performing conventional industrial impurity removal. The pH of the solution is adjusted to 3.5. The Mo content in the solution is 9.3 g / L, and the V content is 13.2 g / L.

[0170] 2. Pretreatment of the organic phase: The organic phase is composed of 10% (by volume) of Alamine 308, 15% of Aliquat 336, 10% of n-decanol, and 65% of solvent oil 260#. The organic phase is treated 6 times with 1.5 mol / L sulfuric acid solution at a phase ratio of O / A = 1 / 1, and then washed with deionized water until it is nearly neutral.

[0171] 3. Extraction: The pretreated organic phase is mixed and extracted with the pretreated vanadomolybdate solution at a phase ratio of O / A = 1.5 / 1. The extraction stage number is 4, obtaining vanadium-molybdenum loaded phase 1 and raffinate. The V content in the raffinate is 10 ppm, and the Mo content is 12 ppm.

[0172] 4. Washing: The washing agent used for washing is a dilute sulfuric acid solution with a pH of 4.3. The washing phase ratio is O / A = 8 / 1, and the washing stage number is 4, obtaining vanadium-molybdenum loaded phase 2 and wash water. The wash water is refluxed to the water phase inlet of the extraction section and enters the extraction section together with the pretreated solution.

[0173] 5. Stripping of molybdenum: The stripping agent used for molybdenum stripping is a potassium sulfate solution with a pH of 8.5, and the potassium sulfate concentration is 0.1 mol / L. The phase ratio is O / A = 6 / 1, and the stage number is 5, obtaining vanadium loaded phase 1 and molybdenum-rich stripping solution. The Mo concentration in the molybdenum-rich stripping solution is 37.15 g / L, and the corresponding recovery rate of molybdenum is 99.87%. The mass fraction of molybdate in the solid after evaporation, concentration, and crystallization is 99.58%.

[0174] 6. Purification: The purifying agent used for purification is an alkaline solution with a pH of 9.5. The phase ratio is O / A = 8 / 1, and the purification stage number is 3, obtaining vanadium loaded phase 2 and purified solution. After adjusting the pH of the purified solution, it is refluxed to the water phase inlet of the washing section as a washing agent and used cyclically.

[0175] 7. Selection of the stripping route for vanadium 1A: The stripping agent used for vanadium 1A stripping is a potassium sulfate solution with a pH of 13.5, and the potassium sulfate concentration is 0.1 mol / L. The phase ratio is O / A = 3.5 / 1, and the stage number is 4, obtaining blank organic phase and vanadium-rich stripping solution. The V concentration in the vanadium-rich stripping solution is 30.78 g / L, and the corresponding recovery rate of vanadium is 99.92%. The mass fraction of vanadate in the solid after evaporation, concentration, and crystallization is 99.71%.

[0176] 8. Regeneration 1A: Pure water is used in Regeneration 1A. Compared with O / A = 5 / 1, the number of regeneration stages is 1. The pH of the effluent from Regeneration 1A is controlled to be near neutral, obtaining the recycled organic phase after regeneration. There is no need to repeat the pretreatment of the organic phase and it can be directly returned to the inlet of the organic phase in the extraction section for recycling.

[0177] 9. Purification 1A:

[0178] The vanadate product obtained from the stripping 1A in Step 7 is processed by Purification 1A to obtain a vanadyl sulfate solution;

[0179] Purification 1A includes pretreatment, extraction, washing, stripping, and regeneration steps;

[0180] A Pretreatment:

[0181] The vanadate product obtained from the stripping 1A is dissolved and sodium thiosulfate with a theoretical dosage of 1.3 times 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 2.4 and filtration is carried out to obtain the pre-extraction solution;

[0182] A Extraction:

[0183] A extraction extracts vanadium from the pre-extraction solution with a phase ratio of O / A = 2 / 1 and undergoes 5 stages of extraction; in A extraction, the volume fractions of each component in the extraction organic phase include: 20% P204, 10% Cyanex301, 5% sec-octanol, and 65% solvent oil 260#;

[0184] A Washing:

[0185] After A extraction, a vanadium-loaded phase and a raffinate are obtained; the vanadium-loaded phase and the detergent for A washing are in a phase ratio of O / A = 12 / 1, and after 8 stages of washing, a washed-loaded phase and the wash water from A washing are obtained. The detergent for A washing is a dilute sulfuric acid solution with a pH value of 2, and the wash water is combined into the A extraction section and used as the feed liquid for A extraction together with the pre-extraction solution of A extraction. A washing can elute some of the impurities entrained and extracted in the vanadium-loaded phase;

[0186] A Stripping:

[0187] The washed-loaded phase from A and the stripping agent for A stripping are in a phase ratio of O / A = 7 / 1, and after 6 stages of A stripping, a blank organic phase and a vanadyl sulfate solution are obtained. The stripping agent is a 4.5 mol / L sulfuric acid solution, and the vanadium concentration in the vanadyl sulfate solution is 2.11 mol / L;

[0188] A Regeneration:

[0189] The blank organic phase after A stripping is regenerated to obtain a recycled organic phase and regeneration water, and the regeneration water can be used for the preparation of the detergent and the stripping agent.

[0190] 10. Purification and oil removal 1A: The vanadyl sulfate solution enters the purification and oil removal system. After purification and oil removal, the oil content in the vanadyl sulfate solution is < 1 ppm;

[0191] 11. Electrolytic preparation 1A: The vanadyl sulfate solution after oil removal is subjected to electrolytic preparation to obtain a vanadium electrolyte product with a valence of 3.5.

[0192] The purity of the prepared vanadium electrolyte with a valence of 3.5 is > 99.99%, and the main impurity contents are shown in the following table.

[0193]

[0194] This embodiment also discloses a preparation method of solid vanadyl sulfate, which is different from the preparation method of vanadium electrolyte in that:

[0195] Vanadyl sulfate is prepared from the vanadyl sulfate reduction solution obtained above; in the evaporation and concentration process, the vanadium solution obtained after purification and oil removal is evaporated and concentrated and then cooled and crystallized to obtain a solid vanadyl sulfate product, and the purity of the solid vanadyl sulfate is ≥ 99.99%.

[0196] This embodiment also discloses a solid vanadyl sulfate, which is prepared by the above preparation method of solid vanadyl sulfate.

[0197] This embodiment also discloses an application of a vanadate solution, including: using the vanadium product obtained after separating vanadium and molybdenum elements in the vanadate solution (such as HDS waste catalyst leaching solution or vanadinite leaching solution) by the above method to prepare vanadium electrolyte or solid vanadyl sulfate.

[0198] Example 3

[0199] This embodiment discloses a preparation method of vanadium electrolyte, as Figure 1 shown, including:

[0200] 1. Solution pretreatment (vanadate): The vanadate solution is the solution obtained by acid leaching HDS waste catalyst and performing conventional industrial impurity removal, adjusting the solution pH to 3.6, with the Mo content in the solution being 22.4 g / L and the V content being 14.8 g / L;

[0201] 2. Organic phase pretreatment: The organic phase is composed of a compound of 10% by volume of N208, 15% of Adogen464, 15% of n-heptanol, and 60% of 260# solvent oil; the organic phase is treated 6 times with 1 mol / L sulfuric acid solution at a phase ratio of O / A = 1 / 1, and then washed with deionized water until nearly neutral;

[0202] 3. Extraction: The pretreated organic phase is mixed and extracted with the pretreated vanadomolybdate solution at a phase ratio of O / A = 3 / 1. The extraction stage is 5, obtaining vanadium and molybdenum loaded 1 and raffinate. The vanadium content in the raffinate is 18 ppm and the molybdenum content is 23 ppm.

[0203] 4. Washing: The detergent used for washing is a dilute sulfuric acid solution with a pH of 4.1. The washing phase ratio is O / A = 7 / 1 and the washing stage is 5, obtaining vanadium and molybdenum loaded 2 and wash water. The wash water is refluxed to the water phase inlet of the extraction section and enters the extraction section together with the pretreated solution.

[0204] 5. Demolybdenation: The demolybdenation agent used is a sodium sulfate solution with a pH of 8.8 and a sodium sulfate concentration of 0.2 mol / L. The phase ratio is O / A = 5 / 1 and the stage is 7, obtaining vanadium loaded 1 and molybdenum-rich stripping solution. The molybdenum concentration in the molybdenum-rich stripping solution is 37.3 g / L, and the corresponding molybdenum recovery rate is 99.90%. The mass fraction of molybdate in the solid after evaporation, concentration and crystallization is 99.63%.

[0205] 6. Purification: The purification agent used for purification is an alkali solution with a pH of 9.7. The phase ratio is O / A = 7 / 1 and the purification stage is 5, obtaining vanadium loaded 2 and purified solution. The purified solution is adjusted to pH and refluxed to the water phase inlet of the washing section as a detergent for recycling.

[0206] 7. Select the stripping route of stripping vanadium 1A: The stripping agent used for stripping vanadium 1A is a sodium sulfate solution with a pH of 13 and a sodium sulfate concentration of 0.1 mol / L. The phase ratio is O / A = 4 / 1 and the stage is 4, obtaining blank organic phase and vanadium-rich stripping solution. The vanadium concentration in the vanadium-rich stripping solution is 19.71 g / L, and the corresponding vanadium recovery rate is 99.88%. The mass fraction of vanadate in the solid after evaporation, concentration and crystallization is 99.64%.

[0207] 8. Regeneration 1A: Pure water is used for regeneration 1A. The phase ratio is O / A = 7 / 1 and the regeneration stage is 1. The pH of the effluent of regeneration 1A is controlled near neutrality, obtaining the recycled organic phase after regeneration. There is no need to repeat the pretreatment of the organic phase, and it can be directly returned to the organic phase inlet of the extraction section for recycling.

[0208] 9. Purification 1A:

[0209] The vanadium-rich stripping solution obtained by stripping 1A in step 7 is treated by purification 1A to obtain a vanadyl sulfate solution.

[0210] Purification 1A includes pretreatment, extraction, washing, stripping and regeneration steps.

[0211] A Pretreatment:

[0212] The vanadium-rich stripping solution obtained from stripping 1A is added with sodium sulfide at 1.1 times the theoretical dosage as a reducing agent; acid is replenished 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 2.1 and filtration treatment is carried out to obtain the solution before extraction;

[0213] A extraction:

[0214] In A extraction, vanadium in the solution before extraction is extracted at an organic / aqueous phase ratio of O / A = 1.5 / 1 and undergoes 5-stage extraction; the volume fractions of each component in the extraction organic phase in A extraction include: 10% Cyanex302, 10% P507, 10% TBP, and 70% solvent oil 260#;

[0215] A scrubbing:

[0216] After A extraction, a vanadium-loaded phase and a raffinate are obtained; the vanadium-loaded phase and the scrubbing agent for A scrubbing are at an organic / aqueous phase ratio of O / A = 10 / 1, and after 6-stage scrubbing, a scrubbed loaded phase and the scrubbing effluent of A scrubbing are obtained. The scrubbing agent for A scrubbing is a dilute sulfuric acid solution with a pH value of 1, and the scrubbing effluent is merged into the A extraction section and used as the feed liquid for A extraction together with the solution before extraction in A extraction. A scrubbing can elute some of the impurities entrained and extracted in the vanadium-loaded phase;

[0217] A stripping:

[0218] The scrubbed loaded phase in A and the stripping agent in A stripping are at an organic / aqueous phase ratio of O / A = 8 / 1, and after 6-stage A stripping, a blank organic phase and a vanadyl sulfate solution are obtained. The stripping agent is a 3.5 mol / L sulfuric acid solution, and the vanadium concentration in the vanadyl sulfate solution is 2.06 mol / L;

[0219] A regeneration:

[0220] After regeneration of the blank organic phase after A stripping, a recycled organic phase and regenerated water are obtained, and the regenerated water can be used for the preparation of the scrubbing agent and the stripping agent.

[0221] 10. Purification and oil removal 1A: The vanadyl sulfate solution enters the purification and oil removal system. After purification and oil removal, the oil content in the vanadyl sulfate solution < 1 ppm;

[0222] 11. Electrolytic preparation 1A: The oil-removed vanadyl sulfate solution undergoes electrolytic preparation to obtain a vanadium electrolyte product with a valence of 3.5.

[0223] The purity of the prepared vanadium electrolyte with a valence of 3.5 > 99.99%, and the main impurity contents are shown in the following table.

[0224]

[0225] This embodiment also discloses a preparation method of solid vanadyl sulfate, which is different from the preparation method of the vanadium electrolyte in that:

[0226] Prepare vanadyl sulfate from the obtained vanadyl sulfate reduction solution above; in the evaporation and concentration process, evaporate and concentrate the vanadium solution obtained after purification and degreasing, and then cool and crystallize to obtain a solid vanadyl sulfate product, and the purity of the solid vanadyl sulfate is ≥99.99%.

[0227] This example also discloses a solid vanadyl sulfate, which is prepared by the above-mentioned preparation method of solid vanadyl sulfate.

[0228] This example also discloses an application of a vanadate solution, including: using the vanadium product obtained after separating vanadium and molybdenum elements in the vanadate solution (such as HDS waste catalyst leaching solution or vanadinite leaching solution) by the above method to prepare vanadium electrolyte or solid vanadyl sulfate.

[0229] Example 4

[0230] This example discloses a preparation method of a vanadium electrolyte. The difference compared with Example 3 is that the organic phase is composed of 10% by volume of Hostarex A324, 15% of TOMAC, 15% of n-heptanol, and 60% of 260# solvent oil; in step 7, the stripping agent is replaced by sulfuric acid from basic sodium sulfate;

[0231] 7. Select the stripping route of stripping vanadium 1B: The stripping agent used for stripping vanadium 1B is a sulfuric acid solution with a pH value <1. Sodium metabisulfite is added during stripping to obtain a tetravalent vanadyl sulfate solution; the addition amount of sodium metabisulfite is 1.3 times the theoretical consumption, and the stripping phase ratio O / A = 4 / 1 to obtain a vanadyl sulfate stripping solution;

[0232] 9. Purification 1B:

[0233] The vanadyl sulfate stripping solution obtained by stripping 1B in step 7 is treated by purification 1B to obtain a vanadyl sulfate solution;

[0234] Purification 1B includes pretreatment, extraction, washing, stripping, and regeneration steps;

[0235] B Pretreatment:

[0236] Adjust the pH of the vanadyl sulfate stripping solution obtained by stripping 1B to 2.2 with alkali and filter it;

[0237] B Extraction:

[0238] B Extraction extracts vanadium in the pre-stripping solution with a phase ratio O / A = 1.5 / 1 and undergoes 5-stage extraction; in B extraction, the volume fractions of each component in the extraction organic phase include: 10% P204, 10% cy272, 5% isooctanol, and 75% 260# solvent oil;

[0239] B Washing:

[0240] After extraction with B, a vanadium-loaded phase and a raffinate are obtained; the vanadium-loaded phase and the detergent for B washing are in a ratio of O / A = 10 / 1. After 6-stage washing, a washed-loaded phase and B-washing effluent are obtained. The detergent for B washing is a dilute sulfuric acid solution with a pH of 1, and the effluent is combined into the B extraction section and used as the feed solution for B extraction together with the pre-extraction solution for B extraction. B washing can elute some of the impurities entrained and extracted in the vanadium-loaded phase;

[0241] B stripping:

[0242] The B-washed loaded phase and the stripping agent for B stripping are in a ratio of O / A = 7.5 / 1. After 6-stage B stripping, a blank organic phase and a vanadyl sulfate solution are obtained. The stripping agent is a 3.5 mol / L sulfuric acid solution, and the vanadium concentration in the vanadyl sulfate solution is 1.93 mol / L;

[0243] B regeneration:

[0244] After regeneration of the blank organic phase after B stripping, a recycled organic phase and regenerated water are obtained, and the regenerated water can be used for the preparation of the detergent and the stripping agent.

[0245] The remaining steps are the same as in Example 3.

[0246] The recovery rate of vanadium > 99.5%, the recovery rate of molybdenum > 99.5%, and the mass fraction of molybdate in the solid after evaporation, concentration, and crystallization > 99.5%;

[0247] The purity of the prepared trivalent vanadium electrolyte > 99.99%, and the main impurity contents are shown in the following table.

[0248]

[0249] This example also discloses a method for preparing solid vanadyl sulfate, which is different from the method for preparing vanadium electrolyte in that:

[0250] Vanadyl sulfate is prepared from the vanadyl sulfate stripping solution obtained above; during the evaporation and concentration process, the vanadium solution obtained after purification and degreasing is evaporated and concentrated and then cooled and crystallized to obtain a solid vanadyl sulfate product, and the purity of the solid vanadyl sulfate ≥ 99.99%.

[0251] This example also discloses a solid vanadyl sulfate prepared by the above method for preparing solid vanadyl sulfate.

[0252] This example also discloses an application of a vanadium molybdate solution, including: using the vanadium product obtained after separating vanadium and molybdenum elements in the vanadium molybdate solution (such as the leaching solution of HDS waste catalyst or the leaching solution of vanadium molybdate lead ore) by the above method for preparing vanadium electrolyte or solid vanadyl sulfate.

[0253] Comparative Example 1

[0254] This comparative example discloses a method for preparing vanadium electrolyte. The difference compared with Example 1 is that the pH of the vanadomolybdate solution required for co-extracting vanadium and molybdenum elements is adjusted to 2. Under this condition, it has basically no influence on the extraction effect, but increases the acid consumption and cost. The purity of the vanadium electrolyte is basically the same as that of Example 1, and other various result indexes have basically no change relative to 1.

[0255] This comparative example also discloses a method for preparing solid vanadyl sulfate. The difference from the method for preparing vanadium electrolyte is that:

[0256] Vanadyl sulfate is prepared from the vanadyl sulfate reduction solution obtained above; in the evaporation and concentration process, the vanadium solution obtained after purification and degreasing is evaporated and concentrated and then cooled and crystallized to obtain a solid vanadyl sulfate product.

[0257] This comparative example also discloses a solid vanadyl sulfate prepared by the above method for preparing solid vanadyl sulfate.

[0258] This comparative example also discloses an application of a vanadomolybdate solution, including: using the vanadium product obtained after separating vanadium and molybdenum elements in the vanadomolybdate solution (such as HDS waste catalyst leaching solution or vanadinite leaching solution) by the above method to prepare vanadium electrolyte or solid vanadyl sulfate.

[0259] Comparative Example 2

[0260] This comparative example discloses a method for preparing vanadium electrolyte. The difference compared with Example 1 is that the pH of the vanadomolybdate solution required for co-extracting vanadium and molybdenum elements is adjusted to 5. Under this condition, the recovery rate of molybdenum will be reduced to about 80%, and other various result indexes have basically no influence.

[0261] This comparative example also discloses a method for preparing solid vanadyl sulfate. The difference from the method for preparing vanadium electrolyte is that:

[0262] Vanadyl sulfate is prepared from the vanadyl sulfate reduction solution obtained above; in the evaporation and concentration process, the vanadium solution obtained after purification and degreasing is evaporated and concentrated and then cooled and crystallized to obtain a solid vanadyl sulfate product.

[0263] This comparative example also discloses a solid vanadyl sulfate prepared by the above method for preparing solid vanadyl sulfate.

[0264] This comparative example also discloses an application of a vanadomolybdate solution, including: using the vanadium product obtained after separating vanadium and molybdenum elements in the vanadomolybdate solution (such as HDS waste catalyst leaching solution or vanadinite leaching solution) by the above method to prepare vanadium electrolyte or solid vanadyl sulfate.

[0265] Comparative Example 3

[0266] This comparative example discloses a method for preparing vanadium electrolyte. The difference compared with Example 1 is that the pH of the detergent used in the washing section is adjusted to 6. Under this condition, phase separation and emulsification problems will occur in the washing section, and the experiment cannot be carried out normally.

[0267] Comparative Example 4

[0268] This comparative example discloses a method for preparing vanadium electrolyte. The difference compared with Example 1 is that the pH of the purifying agent in the purification section is adjusted to 11. Under this condition, the recovery rate of vanadium will drop to 85% - 90%, the vanadium concentration in the prepared vanadium electrolyte is < 1.7 mol / L, and the cost will increase when evaporating and concentrating to prepare solid vanadyl sulfate.

[0269] Comparative Example 5

[0270] This comparative example discloses a method for preparing vanadium electrolyte. The difference compared with Example 1 is that first, vanadium is reversed, and then molybdenum is reversed. Under this condition, during the reversal of vanadium, both molybdenum and vanadium will be back-extracted, and it is impossible to separate and purify vanadium and molybdenum, nor can qualified vanadium electrolyte and solid vanadyl sulfate be prepared.

[0271] Comparative Example 6

[0272] This comparative example discloses a method for preparing vanadium electrolyte. The difference compared with Example 1 is that a mixed extractant of a quaternary ammonium salt and a tertiary amine (R3N) extractant is used. The quaternary ammonium salt is the same as that in Example 1, and the tertiary amine (R3N) is a tertiary amine extractant with a substituent C6 alkyl group, which does not belong to one or more of tertiary amines with R = C8 - C10, tertiary amines with R = isooctyl group, and N208.

[0273] Under this condition, the recovery rates of vanadium and molybdenum drop to < 80%, among which the vanadium recovery rate is 76% and the molybdenum recovery rate is 74%. 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 (the purity of Grade I vanadium electrolyte ≥ 99.9%).

[0274] This comparative example also discloses a method for preparing solid vanadyl sulfate. The difference from the method for preparing vanadium electrolyte is that:

[0275] Vanadyl sulfate is prepared from the vanadyl sulfate reduction solution obtained above; during the evaporation and concentration process, the vanadium solution obtained after purification and degreasing is evaporated and concentrated and then cooled and crystallized to obtain a solid vanadyl sulfate product, and the product purity is lower than the qualified requirement.

[0276] Comparative Example 7

[0277] This comparative example discloses a method for preparing vanadium electrolyte. The difference compared with Example 1 is that a mixed extractant of quaternary ammonium salt and tertiary amine (R3N) is used. The tertiary amine (R3N) is the same as that in Example 1, and the substituent of the quaternary ammonium salt is a C6 alkyl group, which does not belong to N263, Aliquat336, TOMAC or Adogen464.

[0278] Under this condition, the recovery rates of vanadium and molybdenum decrease to <40%, among which the recovery rate of vanadium is 34% and the recovery rate of molybdenum is 38%. 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, and the purity of vanadyl sulfate is lower than the qualified requirement.

[0279] Analyzing the above results, it can be seen that:

[0280] Examples 1 - 4 illustrate that the present invention uses a defined extraction organic phase to recover molybdenum and vanadium elements from a vanadium molybdate solution, achieving a vanadium recovery rate ≥99.5%, and the mass fraction of vanadate in the solid after evaporation, concentration and crystallization ≥99.5%; the molybdenum recovery rate ≥99.5%, and the mass fraction of molybdate in the solid after evaporation, concentration and crystallization ≥99.5%; the vanadium concentration in the prepared vanadium electrolyte >1.7 mol / L, and the purity of vanadium electrolyte in the vanadium electrolyte ≥99.99%.

[0281] Comparing Example 1, Comparative Example 1 and Comparative Example 2, it can be seen that the pH of the vanadium molybdate solution required for the co-extraction of vanadium and molybdenum elements has a significant impact on the recovery rate of molybdenum. The optimal pH of the vanadium molybdate solution required for the co-extraction of vanadium and molybdenum elements is 3 - 4.

[0282] Comparing Example 1, Comparative Example 3 and Comparative Example 4, it can be seen that the pH in the washing and purification stages has a significant impact on the separation of vanadium and molybdenum, as well as the recovery rates of vanadium and molybdenum.

[0283] Comparing Example 1 and Comparative Example 5, it can be seen that only by stripping molybdenum first and then stripping vanadium can the separation and purification of vanadium and molybdenum be achieved; stripping vanadium first and then stripping molybdenum cannot achieve the separation and purification of vanadium and molybdenum.

[0284] Comparing Example 1, Comparative Example 6 and Comparative Example 7, it can be seen that different types of extractants and extractant substituents have a significant impact on the recovery rates of vanadium and molybdenum. The recovery rates of vanadium and molybdenum, the purity of the vanadium electrolyte and the purity of vanadyl sulfate decrease significantly when the extractant does not meet the defined range of the present invention.

[0285] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for preparing a vanadium electrolyte, characterized in that: include: S1, obtaining a vanadium molybdate solution, adjusting the vanadium molybdate solution to acidity, and extracting the vanadium molybdate solution with an extraction organic phase to achieve molybdenum-vanadium co-extraction to obtain a molybdenum-vanadium-rich extraction organic phase; S2, adding a stripping agent to strip molybdenum, adjusting the stripping agent to alkalinity, and stripping the molybdenum-rich vanadium extraction organic phase with the stripping agent to obtain a vanadium-rich organic phase and a molybdenum-rich stripping solution; S3, adding a stripping agent to strip vanadium, adjusting the stripping agent to a stronger alkalinity than the stripping agent in step S2, stripping the vanadium-rich organic phase to obtain a vanadium-rich stripping solution or a vanadium product, and further reducing the vanadium-rich stripping solution or the dissolved solution of the vanadium product further prepared from the vanadium-rich stripping solution to a IV-valent vanadium solution to obtain a vanadyl sulfate reduced solution; Or, adding a reducing agent and stripping in an acidic environment, so that vanadium is separated from the extracted organic phase and reduced to a IV-valent vanadium solution to obtain a vanadyl sulfate stripping solution; S4, treating the molybdenum-rich stripping solution to obtain a molybdenum product; and preparing a vanadium electrolyte from the vanadyl sulfate reducing solution or the vanadyl sulfate stripping solution.

2. The method for preparing a vanadium electrolyte according to claim 1, characterized in that: Step S4 comprises: subjecting the vanadyl sulfate reduction solution or the vanadyl sulfate stripping solution to secondary extraction, secondary washing and secondary stripping in sequence, and then purifying and removing oil, and electrolyzing and preparing to obtain a 3.5-valent vanadium electrolyte product.

3. The method for preparing a vanadium electrolyte according to claim 2, characterized in that: The extractant of the secondary extraction is one or more of P204, P507, Cyanex272, Cyanex301, and Cyanex302; and / or, the synergist is one or more of TBP, sec-octanol, and isooctyl alcohol; and / or, the diluent is 260# solvent oil.

4. The method for preparing a vanadium electrolyte according to claim 1, characterized in that: The counter agent for the vanadium-rich organic phase reverse extraction in step S3 is an alkaline sulfate aqueous solution with a pH value > 11 or a sulfuric acid solution with a pH value < 1.

5. The method for preparing a vanadium electrolyte according to claim 4, characterized in that: The method for preparing the vanadium electrolyte comprises: in step S3, the counter agent for the back extraction of the vanadium-rich organic phase is a sulfuric acid solution with a pH value of less than 1, and a reducing agent is added during the back extraction to obtain a vanadyl sulfate back extraction solution.

6. The method for preparing a vanadium electrolyte according to claim 4, characterized in that: The method for preparing the vanadium electrolyte comprises: in step S3, the counter agent for the vanadium-rich organic back-extraction is an alkaline sulfate aqueous solution with a pH value greater than 11, and a reducing agent is added to the vanadium-rich back-extraction solution or the dissolved solution of the vanadium product to obtain a vanadyl sulfate reduction solution.

7. The method for preparing a vanadium electrolyte according to claim 6, characterized in that: Adding a reducing agent to the vanadium-rich stripping solution or the dissolved solution of the vanadium product to obtain the vanadyl sulfate reduced solution includes: gradually acidifying the stripping solution or the dissolved solution of the vanadium product to an acidic environment.

8. A method for preparing solid vanadyl sulfate, characterized in that: include: S1', obtaining a vanadium molybdate solution, adjusting the vanadium molybdate solution to acidity, and extracting the vanadium molybdate solution with an extraction organic phase to achieve molybdenum-vanadium co-extraction to obtain a molybdenum-vanadium-rich extraction organic phase; S2', adding a stripping agent to strip molybdenum, adjusting the stripping agent to alkalinity, and stripping the molybdenum- and vanadium-rich organic phase with the stripping agent to obtain a vanadium-rich organic phase and a molybdenum-rich stripping solution; S3', adding a stripping agent to strip vanadium, adjusting the stripping agent to a stronger alkalinity than the stripping agent in step S2, stripping the vanadium-rich organic phase to obtain a vanadium-rich stripping solution or a vanadium product, and further reducing the vanadium-rich stripping solution or the dissolved solution of the vanadium product further prepared from the vanadium-rich stripping solution to a IV-valent vanadium solution to obtain a vanadyl sulfate reduced solution; Or, adding a reducing agent and stripping in an acidic environment, so that vanadium is separated from the extracted organic phase and reduced to a IV-valent vanadium solution to obtain a vanadyl sulfate stripping solution; S4', preparing solid vanadyl sulfate from the vanadyl sulfate reduction solution or vanadyl sulfate stripping solution obtained in step S3'.

9. A solid vanadyl sulfate, characterized in that: The solid vanadyl sulfate is prepared by the preparation method of solid vanadyl sulfate according to claim 8, and the purity of the solid vanadyl sulfate is ≥99.99%.

10. An application of a vanadium molybdate solution, characterized in that: include: Using the method for preparing a vanadium electrolyte as described in any one of claims 1 to 7, or the method for preparing solid vanadyl sulfate as described in claim 8, the vanadium product obtained after separation of vanadium and molybdenum elements in a vanadium molybdate solution is used to prepare a vanadium electrolyte or solid vanadyl sulfate.

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