An ionic liquid-anion exchange system and a separation method for separating vanadium and chromium from vanadium-containing alkaline extraction solution

Abstract

The application discloses an ionic liquid-anion exchange system and a separation method for separating vanadium and chromium from an alkaline vanadium-containing extraction solution, and belongs to the technical field of vanadium and chromium separation. The ionic liquid-anion exchange system is composed of a carbonate of an organic amine and a diluent. The carbonate of the organic amine is a carbonic acid type acceptor ammonium salt. The diluent is a mixture of an alcohol compound and a hydrocarbon compound. The ionic liquid-anion exchange system is adopted to solve the problem of selective separation caused by high chromium concentration and similar chemical properties of vanadium and chromium in the alkaline vanadium-containing extraction solution. The system can efficiently and selectively extract vanadium, so that deep separation of vanadium and chromium is realized, the recovery rate of vanadium and the purity of products are significantly improved, and the process flow is green and environmentally-friendly.

Description

Technical Field

[0001] This invention relates to the field of vanadium-chromium separation technology, and in particular to an ionic liquid-anion exchange system and separation method for separating vanadium-chromium from vanadium-containing alkaline extracts. Background Technology

[0002] The application of vanadium in new energy (vanadium batteries), high-end alloys, and other fields has raised the purity requirement for vanadium products to over 99.5%, driving the development of vanadium-chromium separation technology. However, after vanadium is extracted from vanadium mud, the vanadium concentration in the vanadium solution is low. Direct precipitation results in a high chromium ion content, which seriously affects the purity of vanadium products and makes it difficult to obtain high-purity vanadium products.

[0003] Patent CN111235409A discloses a method for extracting vanadium from vanadium-containing sodium carbonate leachate. The method involves introducing a certain amount of carbon dioxide or adding a certain amount of sodium bicarbonate into the vanadium-containing sodium carbonate leachate to form a vanadium-containing sodium carbonate-sodium bicarbonate mixed solution. An organic phase containing N263, a modifier, and a diluent is then mixed with the vanadium-containing sodium carbonate-sodium bicarbonate solution and shaken. Afterward, the mixture is allowed to stand and separate into layers, with the upper layer being the vanadium-loaded organic phase and the lower layer being the raffinate. This method improves the vanadium extraction rate and achieves the separation and enrichment of vanadium, featuring high efficiency, low cost, high vanadium recovery rate, and recyclability of sodium carbonate. However, the modifier 2-octanol used is easily oxidized by pentavalent vanadium, which leads to a decrease in the recyclability of the extractant solution, a decrease in vanadium recovery rate, and low vanadium-chromium separation efficiency.

[0004] The patent with publication number CN115874051A discloses an extraction solvent and extraction method for extracting and recovering pentavalent vanadium from a solution using a synergistic extraction system. The extraction solvent consists of an ionic liquid, an amide extractant, and a diluent. The pentavalent vanadium is extracted by relying on the synergistic effect of the ionic liquid and the amide. Although this improves the vanadium recovery rate and avoids the oxidation of the modifier by pentavalent vanadium, the extraction system is not capable of separating vanadium and chromium from vanadium mud extract, and vanadium and chromium cannot be effectively separated.

[0005] Therefore, there is an urgent need for an efficient method for separating vanadium and chromium to meet the requirements for vanadium purity in industrial production. Summary of the Invention

[0006] The purpose of this invention is to provide an ionic liquid-anion exchange system and method for separating vanadium and chromium from vanadium-containing alkaline extracts. This system addresses the challenge of selective separation in alkaline vanadium-containing extracts due to high chromium concentration and the similar chemical properties of vanadium and chromium. The system can efficiently and selectively extract vanadium, thereby achieving deep separation of vanadium and chromium while significantly improving vanadium recovery rate and product purity. Furthermore, the process is environmentally friendly.

[0007] To achieve the above objectives, the present invention provides an ionic liquid-anion exchange system for separating vanadium and chromium from a vanadium-containing alkaline extract. The ionic liquid-anion exchange system is composed of an organic amine carbonate and a diluent, wherein the diluent is a mixture of alcohols and hydrocarbons.

[0008] Preferably, the carbonate of the organic amine is a carbonate-type acceptor ammonium salt with the molecular formula R1NR2R3R4CO3, wherein R1, R2, R3, and R4 are independently selected from H or Cl-C. 10 One or more of the alkyl hydrocarbon groups.

[0009] Preferably, the alcohol compound has a carbon chain length of C6-C6. 10 The hydrocarbon compound is a straight-chain alcohol; the hydrocarbon compound is selected from one or more alkanes, aromatics or halogenated hydrocarbons.

[0010] Preferably, the volume ratio of the organic amine carbonate to the diluent is (0.1-10):1.

[0011] Preferably, the volume ratio of alcohols to hydrocarbons is 1:10 to 10:1.

[0012] This invention also provides a method for separating vanadium and chromium from a vanadium-containing alkaline extract using the above-described ionic liquid-anion exchange system, comprising the following steps: S1. Extraction and separation: The ionic liquid-anion exchange system is mixed with the vanadium-containing alkaline extract to carry out anion exchange reaction, and the ionic liquid phase loaded with vanadate and the chromium-containing aqueous phase after vanadium extraction are separated. S2. Purification and Chromium Removal: The ionic liquid phase loaded with vanadate is purified by circulating a purifying agent. The purified ionic liquid phase and the chromium-containing purification solution are separated. After the chromium concentration of the chromium-containing purification solution is close to that of the vanadium-containing alkaline extract, it is returned to step S1 for recycling. S3. Vanadium Extraction by Desorption: The purified ionic liquid phase is mixed with a desorption agent to carry out a desorption reaction, which breaks the bond between vanadate and the ionic liquid, and separates the vanadium-rich solution and the regenerated ionic liquid phase; the vanadium-rich solution is deoiled and crystallized to obtain the vanadate product. S4. System regeneration: The regenerated ionic liquid phase obtained in step S3 is mixed with the conversion agent to react and transform it into the initial ionic liquid-anion exchange system, which is then returned to step S1 for recycling. S5. Enrichment and recovery of chromium: The chromium-containing aqueous phase obtained after vanadium extraction in step S1 is mixed with vanadium mud to extract vanadium and chromium, and a vanadium-containing alkaline extract is prepared for recycling and returned to step S1; chromium is enriched in the system through multiple cycles, and the chromium-rich solution is post-treated to obtain chromate products.

[0013] Preferably, in step S1, the vanadium concentration in the vanadium-containing alkaline extract is ≤15g / L, the chromium concentration is ≤5g / L, and the pH is 8-12. When the chromium concentration in the chromium-containing aqueous phase after vanadium extraction is >5g / L, the chromate product is prepared after post-treatment.

[0014] Preferably, in step S5, the purity of the obtained chromate product reaches 98%, and in step S3, the purity of the obtained vanadate product reaches 99.5%.

[0015] Preferably, in step S1, the volume ratio of the ionic liquid-anion exchange system to the vanadium-containing alkaline extract is 1:10-10:1. In step S2, the volume ratio of the vanadate ionic liquid to the purifying agent is 1:10-10:1; In step S3, the volume ratio of the purified vanadate-containing ionic liquid to the eluent is (2-10):1.

[0016] Preferably, the purifying agent in step S2 is one or more of sodium hydroxide, sodium vanadate, and sodium metavanadate, with an alkali concentration of 0.2-1 mol / L and a vanadium concentration of 1-20 g / L. In step S3, the eluent is one or both of sodium hydroxide and sodium carbonate, the concentration of the eluent base is 2-6 mol / L, and the molar ratio of sodium ions in the eluent to vanadium in the purified vanadate-containing ionic liquid is 3:1. In step S4, the conversion agent is one or more of sodium bicarbonate and ammonium bicarbonate, the concentration of the conversion agent is 50-150 g / L, and the volume ratio of the regenerated ionic liquid phase to the conversion agent is (0.5-5):1.

[0017] In an ionic liquid-anion exchange system, carbonate ions undergo anion exchange with vanadate and chromate ions in the aqueous phase, with the selectivity enhanced by the hydroxyl groups of alcohols. By controlling the volume ratio of the ionic liquid to the vanadate-containing alkaline extract at the given pH conditions, the different selectivities of the ionic liquid-anion exchange system with vanadate and chromate ions allow chromate ions to remain in the chromium-containing aqueous phase. A small amount of chromate ions exchanged into the ionic liquid are purified to remove chromium, further purifying the vanadate ions in the ionic liquid load. The purified chromium-containing solution is then returned to the vanadate-containing alkaline extract to continue enriching chromium ions, thus achieving vanadium and chromium separation.

[0018] Therefore, the present invention employs the above-mentioned ionic liquid-anion exchange system and separation method for separating vanadium and chromium from vanadium-containing alkaline extracts, which has the following beneficial effects: (1) This method has high separation efficiency and high selectivity. It has extremely high selectivity for vanadium, with a vanadium separation rate of ≥98.5%, while the selectivity for chromium is relatively low, with a chromium separation rate of ≤5%, thus achieving complete separation of vanadium and chromium. The final product has extremely high purity, with vanadate purity reaching over 99.5% and chromate purity reaching over 95%.

[0019] (2) No solid or liquid waste is generated during the production process. All materials are efficiently recycled, which is a typical green and sustainable development route.

[0020] (3) This method is flexible, easy to scale up and operate continuously, and has significant economic benefits. The core ionic liquid-anion exchange system can be stably recycled through desorption and conversion, which greatly reduces production costs. The entire production process generates no waste, is environmentally friendly, and has the combined advantages of low cost, high quality and environmental friendliness, and has great prospects and potential for industrial application.

[0021] (4) This method has high analytical efficiency and can achieve high enrichment of vanadium. The vanadium concentration in the vanadium-rich solution obtained by analytical analysis can reach 70-100 g / L, which greatly reduces the energy and material consumption of subsequent precipitation, crystallization and other processes, and at the same time lays the foundation for the direct preparation of high-purity sodium vanadate products with a purity of more than 99.5%.

[0022] (5) High overall yield of vanadium and chromium. By returning the vanadium extraction solution to leach new vanadium mud, a closed-loop cycle of vanadium and chromium elements in the system is realized, making the final recovery rate of both close to 100%, which greatly improves the resource utilization rate.

[0023] The technical solution of the present invention will be further described in detail below through embodiments. Detailed Implementation

[0024] This invention provides an ionic liquid-anion exchange system for separating vanadium and chromium from a vanadium-containing alkaline extract. The system consists of an organic amine carbonate and a diluent, wherein the diluent is a mixture of alcohols and hydrocarbons.

[0025] The carbonates of organic amines are carbonate-type acceptor ammonium salts with the molecular formula R1NR2R3R4CO3, where R1, R2, R3, and R4 are independently selected from H or C1-C. 10 One or more of the alkyl hydrocarbon groups.

[0026] Alcohols are compounds with a carbon chain length of C6-C. 10 Straight-chain alcohols; hydrocarbon compounds are selected from one or more alkanes, aromatics, or halogenated hydrocarbons.

[0027] The volume ratio of organic amine carbonate to diluent is (0.1-10):1.

[0028] The volume ratio of alcohols to hydrocarbons is 1:10-10:1.

[0029] This invention also provides a method for separating vanadium and chromium from a vanadium-containing alkaline extract using the above-described ionic liquid-anion exchange system, comprising the following steps: S1. Extraction and separation: The ionic liquid-anion exchange system is mixed with the vanadium-containing alkaline extraction solution to carry out anion exchange reaction, and the ionic liquid phase loaded with vanadate and the chromium-containing aqueous phase after vanadium extraction are separated. S2. Purification and Chromium Removal: The ionic liquid phase loaded with vanadate is purified by circulating a purifying agent. The purified ionic liquid phase and the chromium-containing purification solution are separated. After the chromium concentration of the chromium-containing purification solution is close to that of the vanadium-containing alkaline extract, it is returned to step S1 for recycling. S3. Vanadium Extraction by Desorption: The purified ionic liquid phase is mixed with a desorption agent to carry out a desorption reaction, which breaks the bond between vanadate and the ionic liquid, and separates the vanadium-rich solution and the regenerated ionic liquid phase; the vanadium-rich solution is deoiled and crystallized to obtain the vanadate product. S4. System regeneration: The regenerated ionic liquid phase obtained in step S3 is mixed with the conversion agent to react and transform it into the initial ionic liquid-anion exchange system, which is then returned to step S1 for recycling. S5. Enrichment and recovery of chromium: The chromium-containing aqueous phase after vanadium extraction obtained in step S1 is mixed with vanadium mud to extract vanadium and chromium, and a vanadium-containing alkaline extract is prepared for recycling and returned to step S1; chromium is enriched in the system through multiple cycles, and the resulting chromium-rich solution is post-treated to obtain chromate products.

[0030] In step S1, the vanadium concentration in the alkaline extract is ≤15g / L, the chromium concentration is ≤5g / L, and the pH is 8-12. When the chromium concentration in the aqueous phase containing chromium after vanadium extraction is >5g / L, the product is prepared by post-treatment.

[0031] In step S5, the purity of the obtained chromate product reaches 98%, and in step S3, the purity of the obtained vanadate product reaches 99.5%.

[0032] In step S1, the volume ratio of the ionic liquid-anion exchange system to the vanadium-containing alkaline extract is 1:10-10:1. In step S2, the volume ratio of the vanadate ionic liquid to the purifying agent is 1:10-10:1; In step S3, the volume ratio of the purified vanadate-containing ionic liquid to the eluent is (2-10):1.

[0033] In step S2, the purifying agent is one or more of sodium hydroxide, sodium vanadate, and sodium metavanadate, with an alkali concentration of 0.2-1 mol / L and a vanadium concentration of 1-20 g / L. In step S3, the eluent is one or two of sodium hydroxide and sodium carbonate, with an eluent concentration of 2-6 mol / L and a molar ratio of sodium ions in the eluent to vanadium in the purified ionic liquid containing vanadate of 3:1. In step S4, the conversion agent is one or more of sodium bicarbonate and ammonium bicarbonate, with a conversion agent concentration of 50-150 g / L and a volume ratio of the regenerated ionic liquid phase to the conversion agent of (0.5-3):1.

[0034] The technical solution of the present invention will be further described below through embodiments.

[0035] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0036] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can be appropriately combined to form other embodiments that can be understood by those skilled in the art. These other embodiments are also covered within the scope of protection of this invention.

[0037] Unless otherwise specified, the reagents, instruments, and equipment used in this invention are all commonly used by those skilled in the art, and the testing standards all use national or international standards commonly used in the field, without further explanation.

[0038] Example 1 This embodiment provides an ionic liquid-anion exchange system and separation method for separating vanadium and chromium from a vanadium-containing alkaline extract, including the following steps: (1) Preparation of ionic liquid-anion exchange system: Take CH3N(C8H 17 )2C7H 15 An ionic liquid-anion exchange system was prepared by mixing CO3 with n-octanol and D80 in a volume ratio of 3:2:5.

[0039] (2) Combining the ionic liquid-anion exchange system with vanadium: The ionic liquid-anion exchange system obtained in step (1) was mixed with the vanadium-containing alkaline extract at a volume ratio of 1:2, stirred at 40°C for 3 min, and allowed to stand for phase separation. The vanadium-containing alkaline extract had a vanadium concentration of 10.2 g / L, a chromium concentration of 0.5 g / L, and a pH of 11, resulting in an ionic liquid phase loaded with vanadate and a chromium-containing aqueous phase. The vanadium concentration in the chromium-containing aqueous phase was 115 ppm, the chromium concentration was 484 ppm, the vanadate separation rate was 98.87%, and the chromium separation rate was 3.2%.

[0040] (3) Purification of vanadate-containing ionic liquid: The vanadate-containing ionic liquid obtained in step (2) is mixed with a 24 g / L sodium metavanadate and a 0.7 mol / L sodium hydroxide solution at a volume ratio of 10:1 for purification. The mixture is stirred at 40°C for 3 min to purify the impurities in the vanadate-containing ionic liquid. The vanadate concentration of the chromium-containing purification solution is 10 g / L and the chromium concentration is 300 ppm. The chromium ion purification rate is 93.75%. After two cycles, the chromium concentration reaches 0.6 g / L. The chromium-containing purification solution after the cycle is returned to step (2).

[0041] (4) Desorption of vanadate-containing ionic liquid: The purified vanadate-containing ionic liquid obtained in step (3) was mixed with 4.75 mol / L sodium hydroxide solution at a volume ratio of 4:1 and stirred at 40°C for 3 min to break the bond between vanadate and the ionic liquid-anion exchange system. The vanadate ions combined with sodium ions and transferred to the aqueous phase, and sodium vanadate crystals were obtained after degreasing and crystallization. The single-step vanadate desorption rate was 80.2%. After multiple desorptions, the vanadium concentration in the desorption solution was 80.7 g / L, the chromium concentration was 20 ppm, and the purity of sodium vanadate after crystallization was 99.7%.

[0042] (5) Convert the ionic liquid after analysis: Mix the ionic liquid after analysis in step (4) with 100 g / L sodium bicarbonate at a volume ratio of 1:1, stir at 40°C for 3 min, and the purified ionic liquid is completely converted into carbonate ammonium salt, in which the vanadium content is less than 3 ppm and the chromium content is less than 5 ppm. Then continue to ion exchange in the vanadium-containing alkaline extract to prepare vanadate-containing ionic liquid for recycling. After multiple cycles, when the chromium concentration in the chromium-rich solution in step (2) reaches 5 g / L, after post-treatment, the purity of sodium chromate is 98.5%.

[0043] Example 2 This embodiment provides an ionic liquid-anion exchange system and separation method for separating vanadium and chromium from a vanadium-containing alkaline extract, including the following steps: (1) Preparation of ionic liquid-anion exchange system: Take C2H5NC7H 15 C8H 17 C9H 19An ionic liquid-anion exchange system was prepared by mixing CO3 with n-decyl alcohol and hexadecane chloroin at a volume ratio of 2:3:5.

[0044] (2) Combining the ionic liquid-anion exchange system with vanadium: The ionic liquid-anion exchange system obtained in step (1) was mixed with the vanadium-containing alkaline extract at a volume ratio of 1:1, stirred at 40°C for 3 min, and allowed to stand for phase separation. The vanadium-containing alkaline extract had a vanadium concentration of 15 g / L, a chromium concentration of 2.0 g / L, and a pH of 12, resulting in an ionic liquid containing vanadate. The vanadium concentration in the chromium-containing aqueous phase was 177 ppm, the chromium concentration was 1918 ppm, the vanadate separation rate was 98.82%, and the chromium separation rate was 4.1%.

[0045] (3) Purification of vanadate-containing ionic liquid: The vanadate-containing ionic liquid obtained in step (2) is mixed with a 36 g / L sodium metavanadate and a 0.5 mol / L sodium hydroxide solution at a volume ratio of 8:1 for purification. The mixture is stirred at 40°C for 3 min to purify the impurities in the vanadate-containing ionic liquid. The vanadate concentration of the chromium-containing purification solution is 8.8 g / L, the chromium concentration is 640 ppm, and the chromium ion purification rate is 97.56%. After two cycles, the chromium concentration reaches 1.28 g / L. The chromium-containing purification solution after the cycle is returned to step (2).

[0046] (4) Desorption of vanadate-containing ionic liquid: The purified vanadate-containing ionic liquid obtained in step (3) was mixed with 2.89 mol / L sodium hydroxide solution at a volume ratio of 3.5:1 and stirred at 40℃ for 3 min to break the bond between vanadate and the ionic liquid-anion exchange system. The vanadate ions combined with sodium ions and transferred to the aqueous phase, and sodium vanadate crystals were obtained after deoiling and crystallization. The single-step vanadate desorption rate was 80.7%. After multiple desorptions, the concentration of the desorption solution was 51.5 g / L, and the purity of sodium vanadate after crystallization was 99.5%.

[0047] (5) Conversion of the ionic liquid after analysis: The ionic liquid after analysis in step (4) is mixed with 120 g / L sodium bicarbonate at a volume ratio of 1.6:1 and stirred at 40°C for 3 min. The purified ionic liquid is completely converted into carbonate ammonium salt, with vanadium content below 10 ppm and chromium content below 8 ppm. It is then further processed in a vanadium-containing alkaline extract to prepare vanadate-containing ionic liquid for recycling. After multiple cycles, when the chromium concentration in the chromium-rich solution in step (2) reaches 5 g / L, the sodium chromate purity is 98.3% after post-treatment.

[0048] Example 3 This embodiment provides an ionic liquid-anion exchange system and separation method for separating vanadium and chromium from a vanadium-containing alkaline extract, including the following steps: (1) Preparation of ionic liquid-anion exchange system: Take CH3N (C8H) 17An ionic liquid-anion exchange system was prepared by mixing 3CO3 with n-nonanol and dodecylbenzene in a volume ratio of 4:3:3.

[0049] (2) Combining the ionic liquid-anion exchange system with vanadium: The ionic liquid-anion exchange system obtained in step (1) was mixed with the vanadium-containing alkaline extract at a volume ratio of 1:3, stirred at 40°C for 3 min, and allowed to stand for phase separation. The vanadium concentration in the vanadium-containing alkaline extract was 7.5 g / L, the chromium concentration was 3 g / L, and the pH was 9. The ionic liquid phase loaded with vanadate and the aqueous phase containing chromium were obtained. The vanadium concentration in the aqueous phase containing chromium was 92 ppm, the chromium concentration was 2.9 g / L, the vanadate separation rate was 98.77%, and the chromium separation rate was 3.3%.

[0050] (3) Purification of vanadate-containing ionic liquid: The vanadate-containing ionic liquid obtained in step (2) is mixed with a mixed solution of 18 g / L sodium metavanadate and 0.3 mol / L sodium hydroxide at a volume ratio of 10:1 for purification. The mixture is stirred at 40°C for 3 min to purify the impurities in the vanadate-containing ionic liquid. The vanadate concentration of the chromium-containing purification solution is 4.55 g / L and the chromium concentration is 2.98 g / L. The chromium ion purification rate is 99.3%. After two cycles, the chromium concentration reaches 7.8 g / L. The chromium-containing purification solution is then returned to step (2).

[0051] (4) Desorption of vanadate-containing ionic liquid: The purified vanadate-containing ionic liquid obtained in step (3) was mixed with 4.9 mol / L sodium hydroxide solution at a volume ratio of 3.7:1 and stirred at 40°C for 3 min to break the bond between vanadate and the ionic liquid-anion exchange system. The vanadate ions combined with sodium ions and transferred to the aqueous phase, and sodium vanadate crystals were obtained after deoiling and crystallization. The single-step vanadate desorption rate was 82.1%. After multiple desorptions, the concentration of the desorption solution was 83.2 g / L, and the purity of sodium vanadate after crystallization was 99.7%.

[0052] (5) Conversion of the ionic liquid after analysis: The ionic liquid after analysis in step (4) is mixed with 112 g / L sodium bicarbonate at a volume ratio of 1:1 and stirred at 40°C for 3 min. The purified ionic liquid is completely converted into carbonate-type ammonium salt, with vanadate content below 5 ppm and chromium content below 10 ppm. It is then further processed in a vanadium-containing alkaline extract to prepare vanadate-containing ionic liquid for recycling. After multiple cycles, when the chromium concentration in the chromium-rich solution in step (2) reaches 5 g / L, the sodium chromate purity is 98.9% after post-treatment.

[0053] Therefore, this invention employs an ionic liquid-anion exchange system to solve the problem of selective separation in alkaline vanadium-containing extracts caused by high chromium concentration and the similar chemical properties of vanadium and chromium. This system can efficiently and selectively extract vanadium, thereby achieving deep separation of vanadium and chromium while significantly improving vanadium recovery rate and product purity, and the process is green and environmentally friendly.

[0054] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for separating vanadium and chromium from a vanadium-containing alkaline extract, characterized in that, This is achieved by mixing an ionic liquid-anion exchange system with a vanadium-containing alkaline extract and then performing post-treatment. The ionic liquid-anion exchange system consists of carbonates of organic amines and a diluent, wherein the diluent is a mixture of alcohols and hydrocarbons. The carbonate of the organic amine is a carbonate-type acceptor ammonium salt with the molecular formula R1NR2R3R4CO3, wherein R1, R2, R3, and R4 are independently selected from H or Cl-C. 10 One or more of the alkyl hydrocarbon groups; The alcohol compounds have a carbon chain length of C6-C6. 10 Straight-chain alcohols; Includes the following steps: S1. Extraction and separation: The ionic liquid-anion exchange system is mixed with the vanadium-containing alkaline extract to carry out anion exchange reaction, and the ionic liquid phase loaded with vanadate and the chromium-containing aqueous phase after vanadium extraction are separated. S2. Purification and Chromium Removal: The ionic liquid phase loaded with vanadate is purified by circulating a purifying agent. The purified ionic liquid phase and the chromium-containing purification solution are separated. After the chromium concentration of the chromium-containing purification solution is close to that of the vanadium-containing alkaline extract, it is returned to step S1 for recycling. S3. Vanadium Extraction by Desorption: The purified ionic liquid phase is mixed with a desorption agent to carry out a desorption reaction, which breaks the bond between vanadate and the ionic liquid, and separates the vanadium-rich solution and the regenerated ionic liquid phase; the vanadium-rich solution is deoiled and crystallized to obtain the vanadate product. S4. System regeneration: The regenerated ionic liquid phase obtained in step S3 is mixed with the conversion agent to react and transform it into the initial ionic liquid-anion exchange system, which is then returned to step S1 for recycling. S5. Enrichment and recovery of chromium: The chromium-containing aqueous phase after vanadium extraction obtained in step S1 is mixed with vanadium mud to extract vanadium and chromium, and a vanadium-containing alkaline extract is prepared for recycling and returned to step S1; chromium is enriched in the system through multiple cycles, and the resulting chromium-rich solution is post-treated to obtain chromate products. In step S1, the volume ratio of the ionic liquid-anion exchange system to the vanadium-containing alkaline extract is 1:10-10:

1. In step S2, the volume ratio of the vanadate ionic liquid to the purifying agent is 1:10-10:1; In step S3, the volume ratio of the purified vanadate-containing ionic liquid to the eluent is (2-10):1; The purifying agent in step S2 is one or more of sodium hydroxide, sodium vanadate, and sodium metavanadate, with an alkali concentration of 0.2-1 mol / L and a vanadium concentration of 1-20 g / L. In step S3, the eluent is one or both of sodium hydroxide and sodium carbonate, the concentration of the eluent base is 2-6 mol / L, and the molar ratio of sodium ions in the eluent to vanadium in the purified vanadate-containing ionic liquid is 3:

1. In step S4, the conversion agent is one or more of sodium bicarbonate and ammonium bicarbonate, the concentration of the conversion agent is 50-150 g / L, and the volume ratio of the regenerated ionic liquid phase to the conversion agent is (0.5-3):

1.

2. The separation method for separating vanadium and chromium from a vanadium-containing alkaline extract according to claim 1, characterized in that, The hydrocarbon compounds are selected from one or more of alkanes, aromatics, or halogenated hydrocarbons.

3. The separation method for separating vanadium and chromium from a vanadium-containing alkaline extract according to claim 1, characterized in that, The volume ratio of the organic amine carbonate to the diluent is (0.1-10):

1.

4. The separation method for separating vanadium and chromium from a vanadium-containing alkaline extract according to claim 1, characterized in that, The volume ratio of alcohols to hydrocarbons is 1:10-10:

1.

5. The separation method for separating vanadium and chromium from a vanadium-containing alkaline extract according to claim 1, characterized in that, In step S1, the vanadium concentration in the alkaline extract is ≤15g / L, the chromium concentration is ≤5g / L, and the pH is 8-12. When the chromium concentration in the aqueous phase containing chromium after vanadium extraction is >5g / L, the product is prepared by post-treatment.

6. The separation method for separating vanadium and chromium from a vanadium-containing alkaline extract according to claim 1, characterized in that, In step S5, the purity of the obtained chromate product reaches 98%, and in step S3, the purity of the obtained vanadate product reaches 99.5%.