An extraction solvent and an extraction method for extracting and recovering vanadium pentoxide in a solution by using a synergistic extraction system

Abstract

The present invention discloses an extraction solvent and an extraction method for extracting and recovering vanadium pentoxide in a solution by using a synergistic extraction system. The extraction solvent is composed of a mixture of an ionic liquid, an amide extractant, and a diluent; the ionic liquid is a quaternary ammonium salt ionic liquid, the amide extractant is an alkyl-substituted amide extractant, and the diluent is an inert organic solvent; the extraction method is as follows: preparing the above extraction solvent as an extraction organic phase; using the extraction organic phase to extract vanadium in a vanadium pentoxide-containing solution to obtain a loaded organic phase; using a salt solution A to wash the loaded organic phase to obtain a washed organic phase; using a salt solution B to perform back-extraction on the washed organic phase to obtain a back-extracted vanadium solution and a back-extracted organic phase; using a salt solution C to regenerate the back-extracted organic phase to obtain a regenerated organic phase, which is used as the extraction organic phase for recycling. The present invention can solve the problems of low recovery rate of vanadium pentoxide products, poor product purity, and poor recyclability of the extraction solution, etc.

Description

Technical Field

[0001] The present invention relates to the technical field of pentavalent vanadium extraction. Specifically, it is an extraction solvent and an extraction method for extracting and recovering pentavalent vanadium in a solution by using a synergistic extraction system. Background Art

[0002] Vanadium is the "monosodium glutamate" of modern industry, mainly used in the steel industry, and can also be used in fields such as medicine, aerospace, energy, and catalysts. At present, the process for producing vanadium mainly relies on the ammonium salt precipitation method; although this method has high efficiency, the product purity is not high and it cannot be used in high-end fine industries. At the same time, a large amount of vanadium precipitation mother liquor will be generated, posing a certain threat to the environment. Therefore, choosing a purification method to replace the ammonium salt precipitation method has economic value and environmental protection significance.

[0003] In response to the above problems, the patent with the publication number CN111235409A discloses a method for extracting vanadium from a sodium carbonate leaching solution containing vanadium. A certain amount of carbon dioxide is introduced into the sodium carbonate leaching solution containing vanadium or a certain amount of sodium bicarbonate is added to form a mixed solution of sodium carbonate - sodium bicarbonate containing vanadium; then, an organic phase containing a quaternary ammonium salt extractant, a modifier, and a diluent is mixed with the sodium carbonate - sodium bicarbonate solution containing vanadium and shaken; afterwards, it is left to stand for stratification, the upper layer is the organic phase loaded with vanadium, and the lower layer is the raffinate. This method improves the extraction rate of vanadium, realizes the separation and enrichment of vanadium, and has the characteristics of high efficiency, low cost, high vanadium recovery rate, and recyclability of sodium carbonate. However, the modifier sec-octanol used in it is easily oxidized by pentavalent vanadium, which will lead to a decrease in the recyclability of the extractant solution and a decrease in the vanadium recovery rate. The patent with the publication number CN102851500A discloses a method for extracting vanadium from a high-concentration sulfuric acid solution containing vanadium and the application of an extractant. In this process, the low-valent vanadium in the high-concentration sulfuric acid solution containing vanadium is first oxidized to pentavalent vanadium, and then the pentavalent vanadium in it is extracted with an oxime chelating extractant solution. The loaded organic phase is back-extracted with a sodium hydroxide solution to obtain a sodium vanadate solution; the back-extracted solution is directly precipitated to ammonium metavanadate without purification, and then calcined to obtain vanadium pentoxide with a purity of more than 98.5%. However, the antioxidant property of this oxime chelating extractant is not strong. Especially under strong acid conditions, the oxidizing property of pentavalent vanadium is relatively large, which will lead to poor recyclability of the extractant solution. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present invention is to provide an extraction solvent and an extraction method for extracting and recovering pentavalent vanadium in a solution by using a synergistic extraction system. The extraction solvent and the extraction method have the advantages of high synergistic extraction rate, fast extraction efficiency, stable extraction system, recyclability of the extraction solvent, and environmental friendliness, so as to solve the problems such as poor recyclability of the existing extraction solvent for pentavalent vanadium and unsatisfactory purity of the extracted vanadium product.

[0005] To solve the above technical problems, the present invention provides the following technical solutions:

[0006] An extraction solvent for extracting and recovering pentavalent vanadium in a solution using a synergistic extraction system, which is composed of an ionic liquid, an amide extractant, and a diluent; the ionic liquid is a quaternary ammonium salt ionic liquid, the amide extractant is an alkyl-substituted amide extractant, and the diluent is an inert organic solvent. The ionic liquid extracts vanadium through ionic association, and the amide extractant extracts vanadium through a neutral complexation method; when the extract is generated, the polarity of the extract is too large to dissolve in a general organic solvent; at this time, the ionic liquid and the amide extractant can dissolve the extract due to their strong polarity, making the reaction proceed more thoroughly, thereby improving the extraction rate.

[0007] For the above-mentioned extraction solvent for extracting and recovering pentavalent vanadium in a solution using a synergistic extraction system, the quaternary ammonium salt ionic liquid is a quaternary ammonium type quaternary ammonium salt ionic liquid, an imidazole type quaternary ammonium salt ionic liquid, or a pyridine type quaternary ammonium salt ionic liquid; or the quaternary ammonium salt ionic liquid is a mixture of any two or three of a quaternary ammonium type quaternary ammonium salt ionic liquid, an imidazole type quaternary ammonium salt ionic liquid, and a pyridine type quaternary ammonium salt ionic liquid;

[0008] The quaternary ammonium type quaternary ammonium salt ionic liquid is a single quaternary ammonium type quaternary ammonium salt ionic liquid, or a mixture composed of two or more quaternary ammonium type quaternary ammonium salt ionic liquids; the imidazole type quaternary ammonium salt ionic liquid is a single imidazole type quaternary ammonium salt ionic liquid, or a mixture composed of two or more imidazole type quaternary ammonium salt ionic liquids; the pyridine type quaternary ammonium salt ionic liquid is a single pyridine type quaternary ammonium salt ionic liquid, or a mixture composed of two or more pyridine type quaternary ammonium salt ionic liquids.

[0009] For the above-mentioned extraction solvent for extracting and recovering pentavalent vanadium in a solution using a synergistic extraction system, the structural formula of the quaternary ammonium type quaternary ammonium salt ionic liquid is:

[0010]

[0011] In structural formula (1), the cation is a quaternary ammonium ion; the anion is an inorganic acid root anion;

[0012] The structural formula of the imidazole type quaternary ammonium salt ionic liquid is:

[0013]

[0014] In structural formula (2), the cation is an imidazole ion or an imidazole ion derivative; the anion is an inorganic acid root anion;

[0015] The structural formula of the pyridine type quaternary ammonium salt ionic liquid is:

[0016]

[0017] In the structural formula (3), the cation is a pyridinium ion or a pyridinium ion derivative; the anion is an inorganic acid root anion;

[0018] R1 is a hydrogen ion or an alkyl group with 1 to 20 carbon atoms, R2 is a hydrogen ion or an alkyl group with 1 to 20 carbon atoms, R3 is a hydrogen ion or an alkyl group with 1 to 20 carbon atoms, R4 is a hydrogen ion or an alkyl group with 1 to 20 carbon atoms, R5 is a hydrogen ion or an alkyl group with 1 to 20 carbon atoms, R6 is a hydrogen ion or an alkyl group with 1 to 20 carbon atoms; the inorganic acid root anion is a sulfate anion, a chloride anion, a nitrate anion, a carbonate anion, a hydroiodide anion or a hydrobromide anion.

[0019] For the extraction solvent for extracting and recovering pentavalent vanadium in the solution using the synergistic extraction system, the amide extractant is an alkyl-substituted monodentate amide extractant, an alkyl-substituted bidentate amide extractant or an alkyl-substituted tridentate amide extractant; or the amide extractant is a mixture of any two or three of an alkyl-substituted monodentate amide extractant, an alkyl-substituted bidentate amide extractant and an alkyl-substituted tridentate amide extractant;

[0020] The alkyl-substituted monodentate amide extractant is a single alkyl-substituted monodentate amide extractant, or a mixture composed of two or more alkyl-substituted monodentate amide extractants; the alkyl-substituted bidentate amide extractant is a single alkyl-substituted bidentate amide extractant, or a mixture composed of two or more alkyl-substituted bidentate amide extractants; the alkyl-substituted tridentate amide extractant is a single alkyl-substituted tridentate amide extractant, or a mixture composed of two or more alkyl-substituted tridentate amide extractants.

[0021] For the extraction solvent for extracting and recovering pentavalent vanadium in the solution using the synergistic extraction system, the structural formula of the alkyl-substituted monodentate amide extractant is:

[0022]

[0023] The structural formula of the alkyl-substituted bidentate amide extractant is:

[0024]

[0025] The structural formula of the alkyl-substituted tridentate amide extractant is:

[0026]

[0027] R1 is an alkyl group with 1 to 15 carbon atoms; R2 is an alkyl group with 1 to 15 carbon atoms; R3 is an alkyl group with 1 to 15 carbon atoms; R4 is an alkyl group with 1 to 15 carbon atoms; R5 is an alkyl group with 1 to 15 carbon atoms; R6 is an alkyl group with 1 to 15 carbon atoms.

[0028] The extraction solvent for extracting and recovering pentavalent vanadium in a solution using a synergistic extraction system, wherein the inert organic solvent is sulfonated kerosene, a halogenated hydrocarbon compound or an aromatic compound; or the inert organic solvent is a mixture of any two or three of sulfonated kerosene, halogenated hydrocarbon compounds and aromatic compounds;

[0029] The halogenated hydrocarbon compound is a single halogenated hydrocarbon compound or a mixture composed of two or more halogenated hydrocarbon compounds; the aromatic compound is a single aromatic compound or a mixture composed of two or more aromatic compounds;

[0030] The sulfonated kerosene has 8 - 25 carbon atoms, the halogenated hydrocarbon compound is a chloroalkane, a bromoalkane or an iodoalkane; the aromatic compound is a mononuclear aromatic hydrocarbon or a polycyclic aromatic hydrocarbon.

[0031] The extraction solvent for extracting and recovering pentavalent vanadium in a solution using a synergistic extraction system, wherein the ionic liquid is 1 - 98 parts by weight, the amide extractant is 1 - 98 parts by weight, and the diluent is 1 - 98 parts by weight; at least one of the ionic liquid, the amide extractant and the diluent is liquid at room temperature.

[0032] The extraction method for extracting and recovering pentavalent vanadium in a solution using a synergistic extraction system includes the following steps:

[0033] Step (1) Preparation of the extraction organic phase: Prepare the extraction solvent for extracting and recovering pentavalent vanadium in a solution using a synergistic extraction system as the extraction organic phase;

[0034] Step (2) Extraction: Use the extraction organic phase to extract vanadium from the solution containing pentavalent vanadium. After the extraction is completed, a loaded organic phase is obtained;

[0035] Step (3) Washing: Wash the loaded organic phase with salt solution A. After the washing is completed, a washed organic phase is obtained;

[0036] Step (4) Stripping: Use salt solution B to strip the washed organic phase; after the stripping is completed, a stripped vanadium solution and a stripped organic phase are obtained;

[0037] Step (5) Regeneration: Use salt solution C to regenerate the stripped organic phase to obtain a regenerated organic phase, which is returned to step (2) and used as the extraction organic phase for recycling.

[0038] In the extraction method for extracting and recovering pentavalent vanadium in a solution using a synergistic extraction system, in step (2), the pH of the solution containing pentavalent vanadium is 5 - 13.5, and the extraction temperature is 15 - 90 °C; the volume ratio of the extraction organic phase to the solution containing pentavalent vanadium is 0.5 - 15:1; the extraction time is 1 - 60 min; the extraction method is countercurrent extraction, fractional extraction or cross - flow extraction, and the number of extraction stages is 1 - 25;

[0039] In step (3), the mass concentration of the salt in the salt solution A is 2 - 30 g / L; the pH of the salt solution A is adjusted to 7 - 13.5 with the hydroxide corresponding to the salt in the salt solution A [a pH less than 7 will result in poor washing effect], the washing temperature is 15 - 90 °C; the volume ratio of the loaded organic phase to the salt solution A is 0.5 - 15:1; the washing time is 1 - 60 min; the washing method is countercurrent washing, fractional washing or cross-flow washing, and the number of washing stages is 1 - 12;

[0040] In step (4), the mass concentration of the salt in the salt solution B is 10 - 150 g / L; the pH of the salt solution B is adjusted to 7 - 13.5 with the hydroxide corresponding to the salt in the salt solution B [a pH less than 7 will result in poor stripping effect], the stripping temperature is 15 - 90 °C; the volume ratio of the washing organic phase to the salt solution B is 0.5 - 15:1; the stripping time is 1 - 60 min; the stripping method is countercurrent stripping, fractional stripping or cross-flow stripping, and the number of stripping stages is 1 - 25;

[0041] In step (5), the salts in the salt solution C are soluble salts corresponding to the inorganic acid radicals in the quaternary ammonium salt ionic liquid in the extraction organic phase, the mass concentration of the salt solution C is 5 - 50 g / L; the regeneration temperature is 15 - 90 °C; the volume ratio of the stripping organic phase to the salt solution C is 0.15 - 15:1; the regeneration time is 1 - 60 min; the regeneration method is countercurrent regeneration, fractional regeneration or cross-flow regeneration, and the number of regeneration stages is 1 - 15.

[0042] For the above extraction method of extracting and recovering pentavalent vanadium in the solution using a synergistic extraction system, the salt solution A is one or a mixture of two or more of sodium carbonate solution, ammonium carbonate solution, potassium carbonate solution, sodium chloride solution, potassium chloride solution, ammonium chloride solution, sodium bromide solution, potassium bromide solution, ammonium bromide solution, sodium iodide solution, potassium iodide solution, ammonium iodide solution, sodium nitrate solution, potassium nitrate solution, ammonium nitrate solution, sodium sulfate solution, potassium sulfate solution or ammonium sulfate solution;

[0043] The salt solution B is one or a mixture of two or more of sodium chloride solution, ammonium chloride solution, potassium chloride solution, ammonium sulfate solution, potassium sulfate solution, sodium sulfate solution, ammonium carbonate solution, sodium carbonate solution, potassium carbonate solution, sodium nitrate solution, potassium nitrate solution, ammonium nitrate solution, ammonium bromide solution, sodium bromide solution, potassium bromide solution, sodium iodide solution, potassium iodide solution or ammonium iodide solution;

[0044] The salt solution C is one or a mixture of two or more of sodium chloride solution, ammonium chloride solution, potassium chloride solution, ammonium sulfate solution, potassium sulfate solution, sodium sulfate solution, ammonium carbonate solution, sodium carbonate solution, potassium carbonate solution, sodium nitrate solution, potassium nitrate solution, ammonium nitrate solution, ammonium bromide solution, sodium bromide solution, potassium bromide solution, sodium iodide solution, potassium iodide solution or ammonium iodide solution.

[0045] In the above extraction method for extracting and recovering pentavalent vanadium in a solution using a synergistic extraction system, the pentavalent vanadium-containing solution includes sodium roasted vanadium slag leaching solution, stone coal acid leaching solution, vanadium-containing waste catalyst leaching solution, etc.

[0046] The technical solution of the present invention has achieved the following beneficial technical effects:

[0047] The extraction solvent of the present invention is composed of a mixture of an ionic liquid, an amide extractant and a diluent. The ionic liquid is a quaternary ammonium salt ionic liquid, the amide extractant is an alkyl-substituted amide extractant, and the diluent is an inert organic solvent. The ionic liquid is one or more of a quaternary ammonium type ionic liquid, an imidazole type ionic liquid and a pyridine type ionic liquid. The amide extractant is an alkyl-substituted monodentate amide extractant, an alkyl-substituted bidentate amide extractant or an alkyl-substituted tridentate amide extractant; the diluent is one or more of inert organic solvents such as sulfonated kerosene, halogenated hydrocarbon compounds and aromatic compounds. The present invention obtains a high-purity vanadium-containing solution through the technological steps of preparing the extraction solvent, extraction, washing, back-extraction and regeneration, and has the advantages of high synergistic extraction rate, fast extraction efficiency, stable extraction system, recyclable extraction solvent and environmental friendliness. Detailed implementation mode

[0048] Example 1

[0049] In this example, the extraction solvent for extracting and recovering pentavalent vanadium in a solution using a synergistic extraction system is composed of 10 wt% of an ionic liquid, 10 wt% of an amide extractant and 80 wt% of a diluent; the ionic liquid is a quaternary ammonium salt ionic liquid, the amide extractant is an alkyl-substituted amide extractant, and the diluent is an inert organic solvent. In this example, the quaternary ammonium salt ionic liquid is a quaternary ammonium type quaternary ammonium salt ionic liquid, and its structural formula is as follows:

[0050]

[0051] The amide extractant is an alkyl-substituted monodentate amide extractant, and its structural formula is as follows:

[0052]

[0053] The diluent is the inert organic solvent dodecyl bromide.

[0054] In this example, the extraction method for extracting and recovering pentavalent vanadium in a solution using a synergistic extraction system includes the following steps:

[0055] Step (1) Preparation of the extraction organic phase: The extraction solvent used for extracting and recovering pentavalent vanadium in the solution by the synergistic extraction system above is used as the extraction organic phase in this example.

[0056] Step (2) Extraction: Use the extraction organic phase to extract vanadium from the solution containing pentavalent vanadium. After the extraction is completed, a loaded organic phase is obtained. In this example, the solution containing pentavalent vanadium is the leaching solution of sodium-roasted vanadium slag, and its pH is 8; the extraction temperature is 20 °C, the volume ratio of the extraction organic phase to the solution containing pentavalent vanadium is 3:1; the extraction time is 45 min; the extraction method is cross-flow extraction, and the number of extraction stages is 18.

[0057] Step (3) Washing: Wash the loaded organic phase with salt solution A. After the washing is completed, a washed organic phase is obtained. Salt solution A is a sodium carbonate solution, the mass concentration of the sodium carbonate solution is 15 g / L, adjust the pH of the sodium carbonate solution to 9, and the washing temperature is 60 °C; the volume ratio of the loaded organic phase to salt solution A is 10:1; the washing time is 30 min; the washing method is countercurrent washing, and the number of washing stages is 6.

[0058] Step (4) Stripping: Use salt solution B to strip the washed organic phase; after the stripping is completed, a high-purity vanadium-containing stripping solution and a stripped organic phase are obtained. Salt solution B is a sodium carbonate solution, the mass concentration of the sodium carbonate solution is 55 g / L, adjust the pH of the sodium carbonate solution to 9, and the stripping temperature is 35 °C; the volume ratio of the washed organic phase to salt solution B is 4:1; the stripping time is 45 min; the stripping method is fractional stripping, and the number of stripping stages is 10.

[0059] Step (5) Regeneration: Use salt solution C to regenerate the stripped organic phase to obtain a regenerated organic phase, which is returned to step (2) and used as the extraction organic phase for recycling; the salts in salt solution C are soluble salts corresponding to the inorganic acid radicals in the quaternary ammonium salt ionic liquid in the extraction organic phase. In this example, it is an ammonium carbonate solution, and the mass concentration of the ammonium carbonate solution is 8 g / L; the regeneration temperature is 30 °C; the volume ratio of the stripped organic phase to salt solution C is 2:1; the regeneration time is 50 min; the regeneration method is cross-flow regeneration, and the number of regeneration stages is 8.

[0060] In this example, the purity of the vanadium salt obtained after concentration and drying of the high-purity vanadium-containing stripping solution obtained after stripping in step (4) is 99.82%, and the total recovery rate of vanadium is 98.22%.

[0061] Example 2

[0062] In this embodiment, the extraction solvent for extracting and recovering pentavalent vanadium in the solution using a synergistic extraction system is composed of 30 wt% ionic liquid, 30 wt% amide extractant, and 40 wt% diluent; the ionic liquid is a quaternary ammonium salt ionic liquid, the amide extractant is an alkyl-substituted amide extractant, and the diluent is an inert organic solvent. In this embodiment, the quaternary ammonium salt ionic liquid is an imidazole-based quaternary ammonium salt ionic liquid, and its structural formula is as follows:

[0063]

[0064] The amide extractant is an alkyl-substituted tridentate amide extractant, and its structural formula is as follows:

[0065]

[0066] The diluent is an inert organic solvent sulfonated kerosene, and the number of carbon atoms in the sulfonated kerosene is 8 - 25.

[0067] In this embodiment, the extraction method for extracting and recovering pentavalent vanadium in the solution using a synergistic extraction system includes the following steps:

[0068] Step (1) Preparation of the extraction organic phase: Use the above-mentioned extraction solvent for extracting and recovering pentavalent vanadium in the solution as the extraction organic phase of this embodiment;

[0069] Step (2) Extraction: Use the extraction organic phase to extract vanadium from the solution containing pentavalent vanadium. After the extraction is completed, a loaded organic phase is obtained; in this embodiment, the solution containing pentavalent vanadium is a stone coal acid leaching solution with a pH of 6; the extraction temperature is 40 °C, the volume ratio of the extraction organic phase to the solution containing pentavalent vanadium is 1:1; the extraction time is 30 min; the extraction method is fractional extraction, and the number of extraction stages is 20;

[0070] Step (3) Washing: Wash the loaded organic phase with salt solution A. After the washing is completed, a washed organic phase is obtained; salt solution A is a sodium nitrate solution with a mass concentration of 12 g / L. Adjust the pH of the sodium nitrate solution to 10 using sodium hydroxide, and the washing temperature is 30 °C; the volume ratio of the loaded organic phase to salt solution A is 2:1; the washing time is 20 min; the washing method is fractional washing, and the number of washing stages is 8;

[0071] Step (4) Stripping: Use salt solution B to perform back-extraction on the washed organic phase; after the back-extraction is completed, a high-purity vanadium-containing back-extracted vanadium solution and a back-extracted organic phase are obtained; salt solution B is a potassium nitrate solution with a mass concentration of 85 g / L. Adjust the pH of the potassium nitrate solution to 11 using potassium hydroxide, and the back-extraction temperature is 20 °C; the volume ratio of the washed organic phase to salt solution B is 11:1; the back-extraction time is 20 min; the back-extraction method is cross-flow back-extraction, and the number of back-extraction stages is 22;

[0072] Step (5) Regeneration: The stripped organic phase is regenerated using salt solution C to obtain a regenerated organic phase, which is then returned to step (2) and used as the extraction organic phase for recycling; the salts in salt solution C are soluble salts corresponding to the inorganic acid radicals in the quaternary ammonium salt ionic liquid in the extraction organic phase. In this example, it is a potassium nitrate solution with a mass concentration of 10 g / L; the regeneration temperature is 30 °C; the volume ratio of the stripped organic phase to salt solution C is 2:1; the regeneration time is 10 min; the regeneration method is countercurrent regeneration, and the number of regeneration stages is 8 stages.

[0073] In this example, after concentration and drying treatment, the purity of the vanadium salt obtained from the high-purity vanadium-containing stripped vanadium solution obtained after step (4) back extraction is 99.64%, and the total recovery rate of vanadium is 98.82%.

[0074] Example 3

[0075] In this example, the extraction solvent for extracting and recovering pentavalent vanadium in the solution using a synergistic extraction system is composed of 15 wt% ionic liquid, 15 wt% amide extractant, and 70 wt% diluent; the ionic liquid is a quaternary ammonium salt ionic liquid, the amide extractant is an alkyl-substituted amide extractant, and the diluent is an inert organic solvent. In this example, the quaternary ammonium salt ionic liquid is a pyridine-type quaternary ammonium salt ionic liquid, and its structural formula is as follows:

[0076]

[0077] The amide extractant is an alkyl-substituted bidentate amide extractant, and its structural formula is as follows:

[0078]

[0079] The diluent is an inert organic solvent, 1-chloroundecane [1-chloroundecane, CAS: 2473-03-2].

[0080] In this example, the extraction method for extracting and recovering pentavalent vanadium in the solution using a synergistic extraction system includes the following steps:

[0081] Step (1) Preparation of the extraction organic phase: The extraction solvent for extracting and recovering pentavalent vanadium in the solution using the synergistic extraction system is used as the extraction organic phase in this example;

[0082] Step (2) Extraction: The vanadium in the pentavalent vanadium-containing solution is extracted using the extraction organic phase. After the extraction is completed, a loaded organic phase is obtained. In this example, the pentavalent vanadium-containing solution is a vanadium-containing waste catalyst leaching solution with a pH of 7; the extraction temperature is 80 °C, the volume ratio of the extraction organic phase to the pentavalent vanadium-containing solution is 9:1; the extraction time is 40 min; the extraction method is fractional extraction, and the number of extraction stages is 6 stages;

[0083] Step (3) Washing: Wash the loaded organic phase with salt solution A. After washing, the washed organic phase is obtained. Salt solution A is a sodium sulfate solution with a mass concentration of 17 g / L. Adjust the pH of the sodium sulfate solution to 10 with sodium hydroxide. The washing temperature is 70 °C. The volume ratio of the loaded organic phase to salt solution A is 9:1. The washing time is 35 min. The washing method is fractional washing, and the number of washing stages is 10 stages.

[0084] Step (4) Back-extraction: Perform back-extraction on the washed organic phase with salt solution B. After back-extraction, a high-purity vanadium-containing back-extracted vanadium solution and a back-extracted organic phase are obtained. Salt solution B is a sodium sulfate solution with a mass concentration of 75 g / L. Adjust the pH of the sodium sulfate solution to 12 with sodium hydroxide. The back-extraction temperature is 80 °C. The volume ratio of the washed organic phase to salt solution B is 9:1. The back-extraction time is 5 min. The back-extraction method is cross-flow back-extraction, and the number of back-extraction stages is 20 stages.

[0085] Step (5) Regeneration: Regenerate the back-extracted organic phase with salt solution C to obtain a regenerated organic phase, which is returned to step (2) for recycling as the extraction organic phase. The salts in salt solution C are soluble salts corresponding to the inorganic acid radicals in the quaternary ammonium salt ionic liquids in the extraction organic phase. In this example, it is a potassium sulfate solution with a mass concentration of 14 g / L. The regeneration temperature is 30 °C. The volume ratio of the back-extracted organic phase to salt solution C is 1:1. The regeneration time is 20 min. The regeneration method is cross-flow regeneration, and the number of regeneration stages is 12 stages.

[0086] In this example, the purity of the vanadium salt obtained after concentration and drying of the high-purity vanadium-containing back-extracted vanadium solution obtained by back-extraction in step (4) is 99.41%, and the total recovery rate of vanadium is 97.89%.

[0087] Example 4

[0088] In this example, the extraction solvent for extracting and recovering pentavalent vanadium in the solution using a synergistic extraction system is composed of 5 wt% ionic liquid, 5 wt% amide extractant, and 90 wt% diluent. The ionic liquid is a quaternary ammonium salt ionic liquid, the amide extractant is an alkyl-substituted amide extractant, and the diluent is an inert organic solvent. In this example, the quaternary ammonium salt ionic liquid is a quaternary ammonium type quaternary ammonium salt ionic liquid, and its structural formula is as follows:

[0089]

[0090] The amide extractant is an alkyl-substituted bidentate amide extractant, and its structural formula is as follows:

[0091]

[0092] The diluent is an inert organic solvent, sulfonated kerosene, and the number of carbon atoms in the sulfonated kerosene is 8-25.

[0093] In this embodiment, the extraction method for extracting and recovering pentavalent vanadium in the solution by using a synergistic extraction system includes the following steps:

[0094] Step (1) Preparation of the extraction organic phase: The extraction solvent for extracting and recovering pentavalent vanadium in the solution by using the synergistic extraction system is used as the extraction organic phase in this embodiment;

[0095] Step (2) Extraction: The vanadium in the pentavalent vanadium-containing solution is extracted by using the extraction organic phase. After the extraction is completed, a loaded organic phase is obtained. In this embodiment, the pentavalent vanadium-containing solution is a sodium-roasted vanadium slag leaching solution with a pH of 8; the extraction temperature is 50 °C, the volume ratio of the extraction organic phase to the pentavalent vanadium-containing solution is 14:1; the extraction time is 5 min; the extraction method is fractional extraction, and the number of extraction stages is 18;

[0096] Step (3) Washing: The loaded organic phase is washed with salt solution A. After the washing is completed, a washed organic phase is obtained. Salt solution A is an ammonium sulfate solution with a mass concentration of 15 g / L. The pH of the ammonium sulfate solution is adjusted to 9 with ammonia water. The washing temperature is 90 °C; the volume ratio of the loaded organic phase to salt solution A is 5:1; the washing time is 15 min; the washing method is fractional washing, and the number of washing stages is 10;

[0097] Step (4) Back-extraction: The washed organic phase is back-extracted with salt solution B; after the back-extraction is completed, a high-purity vanadium-containing back-extracted vanadium solution and a back-extracted organic phase are obtained. Salt solution B is a sodium sulfate solution with a mass concentration of 123 g / L. The pH of the sodium sulfate solution is adjusted to 10 with sodium hydroxide. The back-extraction temperature is 20 °C; the volume ratio of the washed organic phase to salt solution B is 7:1; the back-extraction time is 35 min; the back-extraction method is cross-flow back-extraction, and the number of back-extraction stages is 20;

[0098] Step (5) Regeneration: The back-extracted organic phase is regenerated with salt solution C to obtain a regenerated organic phase, which is returned to step (2) and used as the extraction organic phase for recycling; the salts in salt solution C are soluble salts corresponding to the inorganic acid radicals in the quaternary ammonium salt ionic liquid in the extraction organic phase. In this embodiment, it is a sodium sulfate solution with a mass concentration of 40 g / L; the regeneration temperature is 80 °C; the volume ratio of the back-extracted organic phase to salt solution C is 4:1; the regeneration time is 50 min; the regeneration method is countercurrent regeneration, and the number of regeneration stages is 10.

[0099] In this embodiment, the purity of the vanadium salt obtained after the concentration and drying treatment of the high-purity vanadium-containing back-extracted vanadium solution obtained by back-extraction in step (4) is 98.61%, and the total recovery rate of vanadium is 97.85%.

[0100] Example 5

[0101] In this example, the extraction solvent for extracting and recovering pentavalent vanadium in the solution using a synergistic extraction system is composed of 20 wt% ionic liquid, 10 wt% amide extractant, and 70 wt% diluent; the ionic liquid is a quaternary ammonium salt ionic liquid, the amide extractant is an alkyl-substituted amide extractant, and the diluent is an inert organic solvent. In this example, the quaternary ammonium salt ionic liquid is an imidazole-type quaternary ammonium salt ionic liquid, and its structural formula is as follows:

[0102]

[0103] The amide extractant is an alkyl-substituted monodentate amide extractant, and its structural formula is as follows:

[0104]

[0105] The diluent is an inert organic solvent, n-octyl chloride [CAS: 111-85-3].

[0106] In this example, the extraction method for extracting and recovering pentavalent vanadium in the solution using a synergistic extraction system includes the following steps:

[0107] Step (1) Preparation of the extraction organic phase: The extraction solvent for extracting and recovering pentavalent vanadium in the solution using the synergistic extraction system is used as the extraction organic phase in this example;

[0108] Step (2) Extraction: The vanadium in the pentavalent vanadium-containing solution is extracted using the extraction organic phase. After the extraction is completed, a loaded organic phase is obtained. In this example, the pentavalent vanadium-containing solution is a stone coal acid leaching solution with a pH of 13; the extraction temperature is 75 °C, the volume ratio of the extraction organic phase to the pentavalent vanadium-containing solution is 0.5:1; the extraction time is 10 min; the extraction method is fractional extraction, and the number of extraction stages is 13;

[0109] Step (3) Washing: The loaded organic phase is washed with salt solution A. After the washing is completed, a washed organic phase is obtained. Salt solution A is a sodium iodide solution with a mass concentration of 6 g / L. The pH of the sodium iodide solution is adjusted to 10 using sodium hydroxide. The washing temperature is 80 °C; the volume ratio of the loaded organic phase to salt solution A is 2:1; the washing time is 15 min; the washing method is cross-flow washing, and the number of washing stages is 9;

[0110] Step (4) Back-extraction: The washed organic phase is back-extracted with salt solution B; after the back-extraction is completed, a high-purity vanadium-containing back-extracted vanadium solution and a back-extracted organic phase are obtained; salt solution B is a sodium iodide solution, the mass concentration of the sodium iodide solution is 142 g / L, the pH of the sodium hydroxide-sodium iodide solution is adjusted to 12, the back-extraction temperature is 80 °C; the volume ratio of the washed organic phase to salt solution B is 1:1; the back-extraction time is 5 min; the back-extraction method is countercurrent back-extraction, and the number of back-extraction stages is 10 stages;

[0111] Step (5) Regeneration: The back-extracted organic phase is regenerated with salt solution C to obtain a regenerated organic phase, which is returned to step (2) and used as the extraction organic phase for recycling; the salts in salt solution C are soluble salts corresponding to the inorganic acid radicals in the quaternary ammonium salt ionic liquid in the extraction organic phase. In this example, it is an ammonium iodide solution, and the mass concentration of the ammonium iodide solution is 41 g / L; the regeneration temperature is 70 °C; the volume ratio of the back-extracted organic phase to salt solution C is 6:1; the regeneration time is 40 min; the regeneration method is fractional distillation regeneration, and the number of regeneration stages is 8 stages.

[0112] In this example, the purity of the vanadium salt obtained after concentration and drying of the high-purity vanadium-containing back-extracted vanadium solution obtained after step (4) back-extraction is 98.33%, and the total recovery rate of vanadium is 98.01%.

[0113] Example 6

[0114] In this example, the extraction solvent for extracting and recovering pentavalent vanadium in the solution using a synergistic extraction system is composed of 25 wt% ionic liquid, 25 wt% amide extractant, and 50 wt% diluent; the ionic liquid is a quaternary ammonium salt ionic liquid, the amide extractant is an alkyl-substituted amide extractant, and the diluent is an inert organic solvent. In this example, the quaternary ammonium salt ionic liquid is a pyridine-based quaternary ammonium salt ionic liquid, and its structural formula is as follows:

[0115]

[0116] The amide extractant is an alkyl-substituted tridentate amide extractant, and its structural formula is as follows:

[0117]

[0118] The diluent is an inert organic solvent sulfonated kerosene, and the number of carbon atoms in the sulfonated kerosene is 8 - 25.

[0119] In this example, the extraction method for extracting and recovering pentavalent vanadium in the solution using a synergistic extraction system includes the following steps:

[0120] Step (1) Preparation of the extraction organic phase: The extraction solvent for extracting and recovering pentavalent vanadium in the solution using the above synergistic extraction system is used as the extraction organic phase in this example;

[0121] Step (2) Extraction: Use the extraction organic phase to extract vanadium from the vanadium pentoxide-containing solution. After extraction, a loaded organic phase is obtained. In this example, the vanadium pentoxide-containing solution is the leaching solution of vanadium-containing waste catalyst, with a pH of 11. The extraction temperature is 65°C, the volume ratio of the extraction organic phase to the vanadium pentoxide-containing solution is 8:1. The extraction time is 25 min. The extraction method is cross-flow extraction, and the extraction stage number is 18 stages.

[0122] Step (3) Washing: Wash the loaded organic phase with salt solution A. After washing, a washed organic phase is obtained. Salt solution A is potassium carbonate solution, the mass concentration of potassium carbonate solution is 15 g / L, adjust the pH of potassium carbonate solution to 11.5, the washing temperature is 20°C. The volume ratio of the loaded organic phase to salt solution A is 8:1. The washing time is 15 min. The washing method is fractional washing, and the washing stage number is 10 stages.

[0123] Step (4) Back-extraction: Use salt solution B to perform back-extraction on the washed organic phase. After back-extraction, a high-purity vanadium-containing back-extracted vanadium solution and a back-extracted organic phase are obtained. Salt solution B is sodium carbonate solution, the mass concentration of sodium carbonate solution is 115 g / L, adjust the pH of sodium carbonate solution to 12, the back-extraction temperature is 80°C. The volume ratio of the washed organic phase to salt solution B is 0.5:1. The back-extraction time is 5 min. The back-extraction method is cross-flow back-extraction, and the back-extraction stage number is 3 stages.

[0124] Step (5) Regeneration: Use salt solution C to regenerate the back-extracted organic phase to obtain a regenerated organic phase, which is returned to step (2) for recycling as the extraction organic phase. The salts in salt solution C are soluble salts corresponding to the inorganic acid radicals in the quaternary ammonium salt ionic liquid in the extraction organic phase. In this example, it is ammonium carbonate solution, and the mass concentration of ammonium carbonate solution is 26 g / L. The regeneration temperature is 70°C. The volume ratio of the back-extracted organic phase to salt solution C is 12:1. The regeneration time is 15 min. The regeneration method is fractional regeneration, and the regeneration stage number is 11 stages.

[0125] In this example, the purity of the vanadium salt obtained after concentration and drying of the high-purity vanadium-containing back-extracted vanadium solution obtained by back-extraction in step (4) is 99.43%, and the total recovery rate of vanadium is 97.81%.

[0126] Example 7

[0127] In this example, the extraction solvent for extracting and recovering vanadium pentoxide in the solution using a synergistic extraction system is composed of 50 wt% ionic liquid, 10 wt% amide extractant, and 40 wt% diluent. The ionic liquid is a quaternary ammonium salt ionic liquid, the amide extractant is an alkyl-substituted amide extractant, and the diluent is an inert organic solvent. In this example, the quaternary ammonium salt ionic liquid is a quaternary ammonium type quaternary ammonium salt ionic liquid, and its structural formula is as follows:

[0128]

[0129] The amide extractant is an alkyl-substituted bidentate amide extractant, and its structural formula is as follows:

[0130]

[0131] The diluent is an inert organic solvent toluene.

[0132] In this embodiment, the extraction method for extracting and recovering pentavalent vanadium in the solution using a synergistic extraction system includes the following steps:

[0133] Step (1) Preparation of the extraction organic phase: Use the above extraction solvent for extracting and recovering pentavalent vanadium in the solution using a synergistic extraction system as the extraction organic phase of this embodiment;

[0134] Step (2) Extraction: Use the extraction organic phase to extract vanadium from the solution containing pentavalent vanadium. After the extraction is completed, a loaded organic phase is obtained. In this embodiment, the solution containing pentavalent vanadium is the leaching solution of sodium-roasted vanadium slag, and its pH is 12; the extraction temperature is 40 °C, the volume ratio of the extraction organic phase to the solution containing pentavalent vanadium is 9:1; the extraction time is 15 min; the extraction method is fractional extraction, and the number of extraction stages is 9;

[0135] Step (3) Washing: Wash the loaded organic phase with salt solution A. After the washing is completed, a washed organic phase is obtained. Salt solution A is a sodium chloride solution, the mass concentration of the sodium chloride solution is 18 g / L, and the pH of the sodium chloride solution is adjusted to 12 with sodium hydroxide. The washing temperature is 75 °C; the volume ratio of the loaded organic phase to salt solution A is 8:1; the washing time is 45 min; the washing method is cross-flow washing, and the number of washing stages is 11;

[0136] Step (4) Stripping: Use salt solution B to strip the washed organic phase; after the stripping is completed, a high-purity vanadium-containing stripping solution and a stripped organic phase are obtained. Salt solution B is a potassium chloride solution, the mass concentration of the potassium chloride solution is 118 g / L, and the pH of the potassium chloride solution is adjusted to 8 with potassium hydroxide. The stripping temperature is 20 °C; the volume ratio of the washed organic phase to salt solution B is 11:1; the stripping time is 60 min; the stripping method is cross-flow stripping, and the number of stripping stages is 3;

[0137] Step (5) Regeneration: Use salt solution C to regenerate the stripped organic phase to obtain a regenerated organic phase, which is returned to step (2) and used as the extraction organic phase for recycling; the salts in salt solution C are soluble salts corresponding to the inorganic acid radicals in the quaternary ammonium salt ionic liquids in the extraction organic phase. In this embodiment, it is an ammonium chloride solution, and the mass concentration of the ammonium chloride solution is 35 g / L; the regeneration temperature is 80 °C; the volume ratio of the stripped organic phase to salt solution C is 12:1; the regeneration time is 35 min; the regeneration method is fractional regeneration, and the number of regeneration stages is 3.

[0138] In this embodiment, the purity of the vanadium salt obtained after the back extraction in step (4) and through concentration and drying of the high-purity vanadium-containing back extraction solution is 99.53%, and the total recovery rate of vanadium is 98.61%.

[0139] Example 8

[0140] In this embodiment, the extraction solvent for extracting and recovering pentavalent vanadium in the solution using the synergistic extraction system is composed of 30 wt% ionic liquid, 10 wt% amide extractant, and 60 wt% diluent; the ionic liquid is a quaternary ammonium salt ionic liquid, the amide extractant is an alkyl-substituted amide extractant, and the diluent is an inert organic solvent. In this embodiment, the quaternary ammonium salt ionic liquid is an imidazole-type quaternary ammonium salt ionic liquid, and its structural formula is as follows:

[0141]

[0142] The amide extractant is an alkyl-substituted tridentate amide extractant, and its structural formula is as follows:

[0143]

[0144] The diluent is an inert organic solvent, iodohexane [CAS: 638-45-9].

[0145] In this embodiment, the extraction method for extracting and recovering pentavalent vanadium in the solution using the synergistic extraction system includes the following steps:

[0146] Step (1) Preparation of the extraction organic phase: Use the above-mentioned extraction solvent for extracting and recovering pentavalent vanadium in the solution using the synergistic extraction system as the extraction organic phase of this embodiment;

[0147] Step (2) Extraction: Use the extraction organic phase to extract vanadium in the pentavalent vanadium-containing solution. After the extraction is completed, a loaded organic phase is obtained; in this embodiment, the pentavalent vanadium-containing solution is a stone coal acid leaching solution with a pH of 12; the extraction temperature is 45 °C, the volume ratio of the extraction organic phase to the pentavalent vanadium-containing solution is 0.5:1; the extraction time is 20 min; the extraction method is cross-flow extraction, and the number of extraction stages is 20;

[0148] Step (3) Washing: Wash the loaded organic phase with salt solution A. After the washing is completed, a washed organic phase is obtained; salt solution A is an ammonium bromide solution with a mass concentration of 18 g / L. Adjust the pH of the ammonium bromide solution to 8 using ammonia water. The washing temperature is 70 °C; the volume ratio of the loaded organic phase to salt solution A is 12:1; the washing time is 20 min; the washing method is fractional washing, and the number of washing stages is 10;

[0149] Step (4) Back-extraction: The washed organic phase is back-extracted with salt solution B; after the back-extraction is completed, a high-purity vanadium-containing back-extracted vanadium solution and a back-extracted organic phase are obtained; salt solution B is an ammonium bromide solution, the mass concentration of the ammonium bromide solution is 100 g / L, the pH of the ammonium bromide solution is adjusted to 10 with ammonia water, the back-extraction temperature is 40 °C; the volume ratio of the washed organic phase to salt solution B is 6:1; the back-extraction time is 20 min; the back-extraction method is cross-flow back-extraction, and the number of back-extraction stages is 12;

[0150] Step (5) Regeneration: The back-extracted organic phase is regenerated with salt solution C to obtain a regenerated organic phase, which is returned to step (2) and used as the extraction organic phase for recycling; the salts in salt solution C are soluble salts corresponding to the inorganic acid radicals in the quaternary ammonium salt ionic liquid in the extraction organic phase. In this example, it is an ammonium bromide solution, and the mass concentration of the ammonium bromide solution is 40 g / L; the regeneration temperature is 20 °C; the volume ratio of the back-extracted organic phase to salt solution C is 6:1; the regeneration time is 40 min; the regeneration method is cross-flow regeneration, and the number of regeneration stages is 8.

[0151] In this example, the purity of the vanadium salt obtained after concentration and drying of the high-purity vanadium-containing back-extracted vanadium solution obtained by back-extraction in step (4) is 99.45%, and the total recovery rate of vanadium is 99.23%.

[0152] Example 9

[0153] In this example, the extraction solvent for extracting and recovering pentavalent vanadium in the solution using a synergistic extraction system is composed of 15 wt% ionic liquid, 50 wt% amide extractant, and 35 wt% diluent; the ionic liquid is a quaternary ammonium salt ionic liquid, the amide extractant is an alkyl-substituted amide extractant, and the diluent is an inert organic solvent. In this example, the quaternary ammonium salt ionic liquid is a pyridine-type quaternary ammonium salt ionic liquid, and its structural formula is as follows:

[0154]

[0155] The amide extractant is an alkyl-substituted monodentate amide extractant, and its structural formula is as follows:

[0156]

[0157] The diluent is an inert organic solvent, pentadecyl bromide, CAS No. 629-72-1.

[0158] In this example, the extraction method for extracting and recovering pentavalent vanadium in the solution using a synergistic extraction system includes the following steps:

[0159] Step (1) Preparation of the extraction organic phase: The extraction solvent for extracting and recovering pentavalent vanadium in the solution using the above synergistic extraction system is used as the extraction organic phase in this example;

[0160] Step (2) Extraction: Use the extraction organic phase to extract vanadium from the vanadium pentoxide-containing solution. After the extraction is completed, a loaded organic phase is obtained. In this example, the vanadium pentoxide-containing solution is the leaching solution of vanadium-containing waste catalyst, and its pH is 11. The extraction temperature is 45 °C, the volume ratio of the extraction organic phase to the vanadium pentoxide-containing solution is 12:1. The extraction time is 55 min. The extraction method is fractional extraction, and the number of extraction stages is 20 stages.

[0161] Step (3) Washing: Wash the loaded organic phase with salt solution A. After the washing is completed, a washed organic phase is obtained. Salt solution A is a potassium chloride solution, and the mass concentration of the potassium chloride solution is 17 g / L. Use potassium hydroxide to adjust the pH of the potassium chloride solution to 13.5. The washing temperature is 90 °C. The volume ratio of the loaded organic phase to salt solution A is 9:1. The washing time is 20 min. The washing method is cross-flow washing, and the number of washing stages is 10 stages.

[0162] Step (4) Back-extraction: Perform back-extraction on the washed organic phase with salt solution B. After the back-extraction is completed, a high-purity vanadium-containing back-extracted vanadium solution and a back-extracted organic phase are obtained. Salt solution B is a potassium chloride solution, and the mass concentration of the potassium chloride solution is 142 g / L. Use potassium hydroxide to adjust the pH of the potassium chloride solution to 11. The back-extraction temperature is 85 °C. The volume ratio of the washed organic phase to salt solution B is 9:1. The back-extraction time is 55 min. The back-extraction method is fractional back-extraction, and the number of back-extraction stages is 5 stages.

[0163] Step (5) Regeneration: Regenerate the back-extracted organic phase with salt solution C to obtain a regenerated organic phase, which is returned to step (2) for recycling as the extraction organic phase. The salts in salt solution C are soluble salts corresponding to the inorganic acid radicals in the quaternary ammonium salt ionic liquid in the extraction organic phase. In this example, it is an ammonium chloride solution, and the mass concentration of the ammonium chloride solution is 25 g / L. The regeneration temperature is 80 °C. The volume ratio of the back-extracted organic phase to salt solution C is 8:1. The regeneration time is 15 min. The regeneration method is cross-flow regeneration, and the number of regeneration stages is 12 stages.

[0164] In this example, the purity of the vanadium salt obtained after concentration and drying of the high-purity vanadium-containing back-extracted vanadium solution obtained by back-extraction in step (4) is 99.55%, and the total recovery rate of vanadium is 99.41%.

[0165] Obviously, the above examples are only for clearly illustrating the examples and are not limitations on the implementation modes. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation modes here. And the obvious changes or modifications derived therefrom are still within the protection scope of the claims of this patent application.

Claims

1. An extraction solvent for extracting and recovering vanadium pentoxide in a solution by using a synergistic extraction system, characterized in that, It is composed of a mixture of an ionic liquid, an amide extractant, and a diluent; the ionic liquid is a quaternary ammonium salt ionic liquid, the amide extractant is an alkyl-substituted amide extractant, and the diluent is an inert organic solvent; The quaternary ammonium salt ionic liquid is a quaternary ammonium type quaternary ammonium salt ionic liquid, an imidazole type quaternary ammonium salt ionic liquid, or a pyridine type quaternary ammonium salt ionic liquid; or the quaternary ammonium salt ionic liquid is a mixture of any two or three of a quaternary ammonium type quaternary ammonium salt ionic liquid, an imidazole type quaternary ammonium salt ionic liquid, and a pyridine type quaternary ammonium salt ionic liquid; The quaternary ammonium type quaternary ammonium salt ionic liquid is a single quaternary ammonium type quaternary ammonium salt ionic liquid, or a mixture composed of two or more quaternary ammonium type quaternary ammonium salt ionic liquids; the imidazole type quaternary ammonium salt ionic liquid is a single imidazole type quaternary ammonium salt ionic liquid, or a mixture composed of two or more imidazole type quaternary ammonium salt ionic liquids; the pyridine type quaternary ammonium salt ionic liquid is a single pyridine type quaternary ammonium salt ionic liquid, or a mixture composed of two or more pyridine type quaternary ammonium salt ionic liquids; The structural formula of the quaternary ammonium type quaternary ammonium salt ionic liquid is: In structural formula (1), the cation is a quaternary ammonium ion; the anion is an inorganic acid root anion; The structural formula of the imidazole type quaternary ammonium salt ionic liquid is: In structural formula (2), the cation is an imidazole ion or an imidazole ion derivative; the anion is an inorganic acid root anion; The structural formula of the pyridine type quaternary ammonium salt ionic liquid is: In structural formula (3), the cation is a pyridine ion or a pyridine ion derivative; the anion is an inorganic acid root anion; R1 is a hydrogen ion or an alkyl group with 1 to 20 carbon atoms, R2 is a hydrogen ion or an alkyl group with 1 to 20 carbon atoms, R3 is a hydrogen ion or an alkyl group with 1 to 20 carbon atoms, R4 is a hydrogen ion or an alkyl group with 1 to 20 carbon atoms, R5 is a hydrogen ion or an alkyl group with 1 to 20 carbon atoms, R6 is a hydrogen ion or an alkyl group with 1 to 20 carbon atoms; the inorganic acid root anion is a sulfate anion, a chloride anion, a nitrate anion, a carbonate anion, a hydroiodide anion, or a hydrobromide anion; The amide extractant is an alkyl-substituted monodentate amide extractant, an alkyl-substituted bidentate amide extractant, or an alkyl-substituted tridentate amide extractant; or the amide extractant is a mixture of any two or three of an alkyl-substituted monodentate amide extractant, an alkyl-substituted bidentate amide extractant, and an alkyl-substituted tridentate amide extractant; The alkyl-substituted monodentate amide extractant is a single alkyl-substituted monodentate amide extractant, or a mixture composed of two or more alkyl-substituted monodentate amide extractants; the alkyl-substituted bidentate amide extractant is a single alkyl-substituted bidentate amide extractant, or a mixture composed of two or more alkyl-substituted bidentate amide extractants; the alkyl-substituted tridentate amide extractant is a single alkyl-substituted tridentate amide extractant, or a mixture composed of two or more alkyl-substituted tridentate amide extractants; The structural formula of the alkyl-substituted monodentate amide extractant is: The structural formula of the alkyl-substituted bidentate amide extractant is: The structural formula of the alkyl-substituted tridentate amide extractant is: R1 is an alkyl group with 1 to 15 carbon atoms; R2 is an alkyl group with 1 to 15 carbon atoms; R3 is an alkyl group with 1 to 15 carbon atoms; R4 is an alkyl group with 1 to 15 carbon atoms; R5 is an alkyl group with 1 to 15 carbon atoms; R6 is an alkyl group with 1 to 15 carbon atoms.

2. The extraction solvent for extracting and recovering pentavalent vanadium in a solution by using a synergistic extraction system according to claim 1, characterized in that, The inert organic solvent is sulfonated kerosene, a halogenated hydrocarbon compound or an aromatic compound; or the inert organic solvent is a mixture of any two or three of sulfonated kerosene, halogenated hydrocarbon compounds and aromatic compounds; The halogenated hydrocarbon compound is a single halogenated hydrocarbon compound, or a mixture composed of two or more halogenated hydrocarbon compounds; the aromatic compound is a single aromatic compound, or a mixture composed of two or more aromatic compounds; The sulfonated kerosene has 8 to 25 carbon atoms, the halogenated hydrocarbon compound is a chloroalkane, a bromoalkane or an iodoalkane; the aromatic compound is a monobenzene aromatic hydrocarbon or a polycyclic aromatic hydrocarbon.

3. The extraction solvent for extracting and recovering pentavalent vanadium in a solution by using a synergistic extraction system according to claim 1, characterized in that, The ionic liquid is 1 to 98 parts by weight, the amide extractant is 1 to 98 parts by weight, and the diluent is 1 to 98 parts by weight; at least one of the ionic liquid, amide extractant and diluent is liquid at room temperature.

4. An extraction method for extracting and recovering vanadium pentoxide in a solution by using a synergistic extraction system, characterized in that, It includes the following steps: Step (1) Preparation of the extraction organic phase: Prepare the extraction solvent for extracting and recovering pentavalent vanadium in the solution by using the synergistic extraction system as described in claim 1 as the extraction organic phase; Step (2) Extraction: Use the extraction organic phase to extract vanadium in the pentavalent vanadium-containing solution. After the extraction is completed, a loaded organic phase is obtained; Step (3) Washing: Wash the loaded organic phase with salt solution A. After the washing is completed, a washed organic phase is obtained; Step (4) Back-extraction: Perform back-extraction on the washed organic phase with salt solution B; after the back-extraction is completed, a back-extracted vanadium solution and a back-extracted organic phase are obtained; Step (5) Regeneration: Regenerate the back-extracted organic phase with salt solution C to obtain a regenerated organic phase, and return it to step (2) for recycling as the extraction organic phase.

5. The extraction method for extracting and recovering vanadium pentoxide in a solution by using a synergistic extraction system according to claim 4, wherein In step (2), the pH of the pentavalent vanadium-containing solution is 5 to 13.5, and the extraction temperature is 15 to 90 °C; the volume ratio of the extraction organic phase to the pentavalent vanadium-containing solution is 0.5 to 15:1; the extraction time is 1 to 60 min; the extraction method is countercurrent extraction, fractional extraction or cross-flow extraction, and the number of extraction stages is 1 to 25; In step (3), the mass concentration of the salt in salt solution A is 2 to 30 g / L; the pH of salt solution A is adjusted to 7 to 13.5 with the hydroxide corresponding to the salt in salt solution A, and the washing temperature is 15 to 90 °C; the volume ratio of the loaded organic phase to salt solution A is 0.5 to 15:1; the washing time is 1 to 60 min; the washing method is countercurrent washing, fractional washing or cross-flow washing, and the number of washing stages is 1 to 12; In step (4), the mass concentration of the salt in the salt solution B is 10-150 g / L; the pH of the salt solution B is adjusted to 7-13.5 by using the hydroxide corresponding to the salt in the salt solution B, and the stripping temperature is 15-90 °C; the volume ratio of the washing organic phase to the salt solution B is 0.5-15:1; the stripping time is 1-60 min; the stripping method is countercurrent stripping, fractional stripping or cross-flow stripping, and the stripping stage number is 1-25 stages; In step (5), the salts in the salt solution C are soluble salts corresponding to the inorganic acid radicals in the quaternary ammonium salt ionic liquid in the extraction organic phase, and the mass concentration of the salt solution C is 5-50 g / L; the regeneration temperature is 15-90 °C; the volume ratio of the stripping organic phase to the salt solution C is 0.15-15:1; the regeneration time is 1-60 min; the regeneration method is countercurrent regeneration, fractional regeneration or cross-flow regeneration, and the regeneration stage number is 1-15 stages.

6. The extraction method for extracting and recovering pentavalent vanadium in a solution by using a synergistic extraction system according to claim 4, characterized in that, The salt solution A is one or a mixture of two or more of sodium carbonate solution, ammonium carbonate solution, potassium carbonate solution, sodium chloride solution, potassium chloride solution, ammonium chloride solution, sodium bromide solution, potassium bromide solution, ammonium bromide solution, sodium iodide solution, potassium iodide solution, ammonium iodide solution, sodium nitrate solution, potassium nitrate solution, ammonium nitrate solution, sodium sulfate solution, potassium sulfate solution or ammonium sulfate solution; The salt solution B is one or a mixture of two or more of sodium chloride solution, ammonium chloride solution, potassium chloride solution, ammonium sulfate solution, potassium sulfate solution, sodium sulfate solution, ammonium carbonate solution, sodium carbonate solution, potassium carbonate solution, sodium nitrate solution, potassium nitrate solution, ammonium nitrate solution, ammonium bromide solution, sodium bromide solution, potassium bromide solution, sodium iodide solution, potassium iodide solution or ammonium iodide solution; The salt solution C is one or a mixture of two or more of sodium chloride solution, ammonium chloride solution, potassium chloride solution, ammonium sulfate solution, potassium sulfate solution, sodium sulfate solution, ammonium carbonate solution, sodium carbonate solution, potassium carbonate solution, sodium nitrate solution, potassium nitrate solution, ammonium nitrate solution, ammonium bromide solution, sodium bromide solution, potassium bromide solution, sodium iodide solution, potassium iodide solution or ammonium iodide solution.

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