CN109207724B - A kind of extraction solvent and extraction method for simultaneously extracting and separating vanadium and chromium from vanadium-chromium solution - Google Patents

Abstract

The invention relates to the technical field of hydrometallurgy, in particular to an extraction solvent and an extraction method for simultaneously extracting and separating vanadium and chromium from a solution containing vanadium and chromium. The extraction agent is that the solubility is lower than 0.5g/L water-soluble amide, the diluent is an inert organic solvent, and the extraction agent is N-alkylamide and N,N,N,N-tetraalkyldiamide Or contain one or more of low water-soluble amides such as multiple amide groups, and the diluent is one or more in inert organic solvents such as sulfonated kerosene, white oil and liquid halogenated hydrocarbon compounds at normal temperature. One or more, through the process steps of preparing extraction solvent, extraction, washing, stripping chromium, stripping vanadium to obtain high-purity vanadium solution or vanadium-containing precipitate and chromium-chromium solution, which has the advantages of simple process, strong extraction ability and fast balance. , good separation selectivity, easy stripping and economical and environmental protection.

Description

A kind of extraction solvent and extraction solvent for simultaneously extracting and separating vanadium and chromium from vanadium-chromium solution method

technical field

The invention relates to the technical field of hydrometallurgy, in particular to an extraction method for simultaneously extracting and separating vanadium and chromium from a vanadium-chromium solution, which is simple in process, strong in extraction capacity, fast in balance, good in selectivity, easy in stripping and separation, and economical and environmentally friendly. Solvents and methods of extraction.

Background technique

As we all know, both vanadium and chromium are important strategic resources, and they are widely used in various industries. However, the properties of vanadium and chromium are very similar, and they are generally symbiotic in vanadium-titanium magnetite. For the vanadium-chromium slag after roasting, the separation and purification of vanadium-chromium in the water immersion solution is a difficult problem to solve at present.

In view of the above problems, the patent publication number CN1073414 discloses a method for chemically treating vanadium-chromium waste liquid. First, ferric chloride and pentavalent vanadium are used to form precipitation in a weakly acidic solution, and after filtration, they are extracted with sulfuric acid and ammonium sulfate. However, this process avoids the simultaneous precipitation of vanadium and chromium, and can only have a good effect on low-concentration vanadium-chromium solutions. Chinese patent CN101121962A invents a method for extracting and separating vanadium and chromium with primary and secondary complex amines. The patent has good effect of separating vanadium and chromium, but the process is complicated and energy consumption is high. Chinese patent CN102127654 adopts the sub-molten salt method to extract vanadium and chromium, and obtains sodium vanadate and sodium chromate by fractional crystallization. The value of the product obtained by this process is higher, but the product is impure, consumes a lot of reagents, and the recovery rate is not high.

SUMMARY OF THE INVENTION

The object of the present invention is to solve the above-mentioned deficiencies of the prior art, and to provide a method for simultaneously extracting and separating vanadium and chromium from a vanadium-chromium solution, which is simple in process, strong in extraction ability, fast in balance, good in selectivity, easy to strip and separate, and economical and environmentally friendly. method.

The technical scheme adopted by the present invention to solve its technical problems is:

A kind of extraction solvent that simultaneously extracts and separates vanadium-chromium from vanadium-chromium solution, it is characterized in that this extraction solvent is made up of extraction agent and diluent mixing, and described extraction agent is the water-soluble amide whose solubility is lower than 0.5g/L, The diluent is an inert organic solvent.

The extraction agent of the present invention is one of N-alkylamide and N,N,N,N-tetraalkyldiamide or water-soluble amide containing multiple amide groups and the solubility is lower than 0.5g/L Or more, the diluent is one or more of sulfonated kerosene, white oil and inert organic solvent of halogenated hydrocarbon compound which is liquid at normal temperature.

When one of the extractant and the diluent described in the present invention is solid at 25°C or both are solid at 25°C, the mass ratio of the extractant in the extraction solvent is 2% to 100%, and the weight of the diluent is 2% to 100%. The mass ratio is 0~98%, when both the extractant and the diluent are liquid at 25°C; the volume ratio of the extractant in the extraction solvent is 5%-100%, and the volume ratio of the diluent is 0~95% .

In the N-alkylamides and N,N,N,N-tetraalkyldiamides of the present invention or the water-soluble amides containing multiple amide groups and the solubility of which is lower than 0.5g/L, the alkyl group in the acyl group The number of carbon atoms is 1 to 18, and it may be a straight-chain alkyl group or a branched-chain alkyl group.

The number of carbon atoms in the alkyl group directly connected to the nitrogen atom in the N-alkylamide of the present invention is 1 to 18, and the N,N,N,N-tetraalkyldiamide is directly connected to the nitrogen atom. The two alkyl groups are the same alkyl group or different alkyl groups, and the carbon atoms of the two alkyl groups directly connected to the nitrogen atom are 1 to 18, which can be straight-chain or branched. Alkyl.

The carbon number of the sulfonated kerosene of the present invention is 11-17, the type of the white oil is 1#-7#, and the halogenated hydrocarbon compound that is liquid at room temperature is chlorinated hydrocarbon, brominated hydrocarbon or iodine One or more of the inert organic solvents that replace hydrocarbons.

A method for simultaneously extracting and separating vanadium and chromium from a vanadium-containing chromium solution is characterized in that the processing steps of this extraction and separation method are as follows:

(1). Preparation of extraction solvent: the extraction solvent is composed of a mixture of an extractant and a diluent. The extractant is a water-soluble amide with a solubility of less than 0.5 g/L, and the diluent is an inert organic solvent. The two are mixed. Dubbed extraction solvent as organic phase;

(2) Extraction: take the extraction solvent in step (1) to extract the vanadium-containing chromium solution, the PH of the vanadium-chromium-containing solution is 1.3-10, the extraction temperature is 10-90 ℃, compared with O/A=0.4-4.0, The time is 1-10 min, the extraction method is counter-current extraction, fractional extraction or cross-current extraction, and the number of extraction stages is 1-35 to obtain the loaded organic phase;

(3). Washing: washing the loaded organic phase obtained in step (2) with a solution, the pH of the solution is 1.2～9.0, the temperature is 10～90℃, the ratio O/A=0.4～40, and the time is 1～10 min, to obtain the organic phase after washing;

(4). Back-extraction of chromium: take the alkaline solution for back-extraction of the washed organic phase obtained in step (3), the extraction temperature is 10 ℃ ~ 60 ℃, compared with O/A = 1 ~ 20, and the time is 1 ~ 8 min, the pH of the alkaline solution is 7.2-10.0, the back-extraction method is counter-current extraction or cross-current extraction, and the number of extraction stages is 1-10, to obtain high-purity chromium solution and vanadium-loaded organic phase;

(5). Back-extraction of vanadium: take the alkaline solution for back-extraction of the vanadium-loaded organic phase obtained in step (4), the extraction temperature is 10 ℃ ~ 60 ℃, compared with O/A = 1 ~ 10, and the time is 1 ~ For 10 min, the pH of the alkaline solution is 7.5-13.5, the back-extraction method is counter-current extraction or cross-current extraction, and the extraction stages are 1-10 to obtain a high-purity vanadium solution.

The vanadium-containing chromium solution of the present invention includes vanadium titanomagnetite smelting waste slag leaching solution and a mixed solution of two or more polymetallic sulfuric acid media containing vanadium or chromium, wherein the solution contains both vanadium and chromium, or only Contains vanadium or chromium; the valence state of vanadium is tetravalent or pentavalent, or a mixture of tetravalent and pentavalent vanadium; the valence state of chromium is trivalent or hexavalent, or a mixture of trivalent and hexavalent.

In the step (4) and step (5) of the present invention, the alkaline substance is a mixture of ammonia water, sodium hydroxide, potassium hydroxide, calcium hydroxide, sodium carbonate, ammonium carbonate, potassium carbonate, ammonium chloride, and ammonium sulfate. species or a mixture of several.

The solution in the step (3) is an acidic solution, and the acidic solution includes inorganic acids that are not easily oxidized such as sulfuric acid or nitric acid, or a mixture containing one or both of these inorganic acids.

In the present invention, because the extraction solvent is composed of an extractant and a diluent, the extractant is a water-soluble amide with a solubility lower than 0.5 g/L, the diluent is an inert organic solvent, and the extractant is N- The solubility of alkylamide and N,N,N,N-tetraalkyldiamide is lower than one or more of 0.5g/L water-soluble amide, and the diluent is sulfonated kerosene, white oil and normal temperature One or more of inert organic solvents such as liquid halogenated hydrocarbon compounds, etc., obtain high-purity vanadium liquid and chromium liquid through the process steps of preparing extraction solvent, extraction, washing, back-extracting chromium, and back-extracting vanadium, The extractant and diluent used in the above steps are easy to obtain, have strong vanadium-chromium extraction ability and good selectivity, and are easy to strip and separate vanadium and chromium to obtain high-purity vanadium liquid and chromium liquid; an organic phase washing process is added to effectively remove the Other impurities that may be contained in the organic phase are loaded; the organic phase can be recycled and regenerated, and the extraction reaction can be carried out multiple times, which is beneficial to cost reduction. advantage.

Detailed ways

A kind of extraction solvent that simultaneously extracts and separates vanadium-chromium from vanadium-chromium solution, it is characterized in that this extraction solvent is made up of extraction agent and diluent mixing, and described extraction agent is the water-soluble amide whose solubility is lower than 0.5g/L, The diluent is an inert organic solvent, and the extractant is one of the water-soluble amides of N-alkylamide and N,N,N,N-tetraalkyldiamide whose solubility is lower than 0.5g/L. One or more, preferably, the single-substituted amide, wherein the number of carbon atoms in the alkyl R is 6~10, preferably, the two-substituted amide, wherein the two alkyl R can be the same or different ; The number of carbon atoms in the alkyl R is 6～10, and the described diluent is one or more of inert organic solvents such as sulfonated kerosene, white oil and liquid halogenated hydrocarbon compounds at normal temperatures, and the described When one of the extractant and diluent is solid at 25°C or both are solid at 25°C, the mass ratio of the extractant in the extraction solvent is 2%~100%, and the mass ratio of the diluent is 0~98%, when both the extractant and the diluent are liquid at 25°C; the volume ratio of the extractant in the extraction solvent is 5%-100%, and the volume ratio of the diluent is 0~95%. The solubility of N-alkylamide and N,N,N,N-tetraalkyldiamide is lower than 0.5g/L water-soluble amide, the number of carbon atoms in the alkyl group in the acyl group is 1-18, which can be straight chain alkane The alkyl group can also be a branched chain alkyl group. The number of carbon atoms in the alkyl group directly connected to the nitrogen atom in the N-alkyl amide is 1 to 18, which can be a straight chain alkyl group or a branched chain alkyl group. The two alkyl groups directly connected to the nitrogen atom in the N,N,N,N-tetraalkyldiamide are the same alkyl group or different alkyl groups, and the two alkyl groups directly connected to the nitrogen atom are the same alkyl group or different alkyl groups. The number of carbon atoms of the base is 1-18 respectively, which can be a straight-chain alkyl group or a branched-chain alkyl group. The carbon number of the sulfonated kerosene is 11-17, and the type of the white oil is 1#-7# , the halogenated hydrocarbon compounds that are liquid at room temperature are one or more of inert organic solvents such as chlorinated hydrocarbons, brominated hydrocarbons or iodo hydrocarbons, and the process steps of the extraction and separation method are as follows: (1). Preparation of extraction solvent: the extraction solvent is composed of an extraction agent and a diluent. The extraction agent is a water-soluble amide with a solubility of less than 0.5 g/L, and the diluent is an inert organic solvent. The two are mixed to form an extraction solvent as Organic phase; (2). Extraction: take the extraction solvent in step (1) to extract the vanadium-containing chromium solution, preferably an acidic solution, the PH of the vanadium-chromium solution is 1.3～5, the extraction temperature is 10 ℃～70 ℃, phase The ratio O/A=0.4～3, the time is 1～8min, and the loaded organic phase is obtained. The extraction method is countercurrent extraction, fractional distillation extraction or cross-flow extraction, and the number of extraction stages is 1～10, and the loaded organic phase is obtained; (3) .washing: washing the loaded organic phase obtained in step (2) with an acidic solution, the pH of the acidic solution is 1.2～5, the temperature is 10℃～70℃, the ratio O/A=0.4～2, and the time is 1～8 min, to obtain the washed organic phase; (4). Reverse Chromium extraction: take the washed organic phase obtained in the alkaline solution back extraction step (3), the extraction temperature is 10 ℃ ~ 60 ℃, compared with O/A = 1 ~ 15, the time is 1 ~ 8 min, the said The pH of the alkaline solution is 7.2-9.0, the back-extraction method is counter-current extraction or cross-current extraction, and the number of extraction stages is 1-10 to obtain high-purity chromium solution and vanadium-loaded organic phase; (5). Back-extraction of vanadium: Take the vanadium-loaded organic phase obtained in the back-extraction step (4) with an alkaline solution. The pH of the solution is 7.5-13.5, the back-extraction method is counter-current extraction or cross-current extraction, and the number of extraction stages is 1-10 to obtain a high-purity vanadium solution. The vanadium-chromium solution includes vanadium-titanium magnetite smelting waste residue leachate, Mixed solution of two or more kinds of polymetallic sulfuric acid medium containing vanadium or chromium, wherein the solution contains both vanadium and chromium, or only contains vanadium or chromium; the valence state of vanadium is tetravalent or pentavalent, or tetravalent The mixture of valence and pentavalent vanadium; the valence of chromium is trivalent or hexavalent, or a mixture of trivalent and hexavalent, and the alkaline substances in the steps (4) and (5) are ammonia water, hydroxide One or more mixtures of sodium, potassium hydroxide, calcium hydroxide, sodium carbonate, ammonium carbonate, potassium carbonate, ammonium chloride, and ammonium sulfate, the acidic solution in the step (3), including sulfuric acid or nitric acid, is not easily absorbed. Oxidized inorganic acids, or a mixture containing one or both of these inorganic acids.

N-alkylamides (structural formula) are as follows:

N,N,N,N-Tetraalkyldiamides (structural formula) are as follows:

N,N,N,N-tetraalkyldiamides have the following structural formula:

Example 1

+90%磺化 煤油混合配成萃取溶剂作为有机相； (1). Preparation of extraction solvent: 10% by mass

+90% sulfonated kerosene is mixed to prepare extraction solvent as organic phase;

(2). Extraction: take the extraction solvent in step (1), 4-stage countercurrent extraction pH is 1.9 sodium roasting vanadium-chromium slag leaching solution, temperature is 60 ℃, compared to O/A=0.4, time is 1 min, get load organic phase;

(3). Washing: wash the loaded organic phase of step (2) with sulfuric acid solution, pH is 1.4, temperature is 60°C, compared to O/A=3, time is 5 min, to obtain the washed organic phase;

(4). Back-extraction of chromium: 8-stage cross-flow back-extraction of the organic phase of step (3) with an ammonia solution with a pH of 7.5 at a temperature of 40 °C, compared with O/A = 2, and a time of 6 min, the purity is 99.25% chromium solution and vanadium-loaded organic phase;

(5). Back-extraction of vanadium: 9-stage countercurrent back-extraction of the vanadium-loaded organic phase in step (4) with an aqueous ammonia solution with a pH of 12.5 at a temperature of 30°C, compared with O/A=2, and a time of 8 minutes to obtain the purity It is 99.87% vanadium solution.

Example 2

+80%磺化煤油 混合配成萃取溶剂作为有机相； (1). Preparation of extraction solvent: 20% by mass

+80% sulfonated kerosene is mixed to prepare extraction solvent as organic phase;

(2). Extraction: take the extraction solvent in step (1), 3-stage countercurrent extraction pH is 1.7 sodium roasting vanadium-chromium slag leaching solution, the temperature is 50 ℃, the ratio O/A=0.5, the time is 3min, and the load is obtained. The organic phase;

(3). Washing: washing the organic phase of step (2) with sulfuric acid solution, the pH is 1.6, the temperature is 40°C, compared with O/A=2, the time is 1 min, and the washed organic phase is obtained;

(4). Back-extraction of chromium: 7-stage cross-flow back-extraction of the organic phase of step (3) with an ammonia solution with a pH of 7.7 at a temperature of 20 °C, compared with O/A = 1, and a time of 4 min, the obtained purity is 99.37% chromium solution and vanadium-loaded organic phase;

(5). Back-extraction of vanadium: 7-stage countercurrent back-extraction of the organic phase of step (4) with an ammonia solution with a pH of 12.9, a temperature of 20 °C, a comparison of O/A=5, a time of 9 min, and a purity of 99.82 % vanadium solution.

Example 3

+70% 3#白油 混合配成萃取溶剂作为有机相； (1). Preparation of extraction solvent: 30% by mass

+70% 3# white oil is mixed into extraction solvent as organic phase;

(2). Extraction: take the extraction solvent in step (1), and extract the calcified vanadium-chromium slag with an acidity of pH 1.6 in a three-stage countercurrent extraction at a temperature of 40 °C, a ratio of O/A = 0.7, and a time of 1 min. , to obtain a loaded organic phase;

(3). Washing: wash the organic phase of step (2) with sulfuric acid solution, pH is 1.5, temperature is 30°C, compared with O/A=1, time is 4 min, and the washed organic phase is obtained;

(4). Back-extraction of chromium: 7-stage counter-current back-extraction of the organic phase of step (3) with an ammonia solution with pH 7.9, the temperature is 30 °C, compared to O/A=4, the time is 8 min, and the purity is 99.41 % chromium solution and vanadium-loaded organic phase;

(5). Back-extraction of vanadium: 8-stage countercurrent back-extraction of the organic phase of step (4) with an ammonia solution with a pH of 12.7, a temperature of 50 °C, a comparison of O/A=4, a time of 5 min, and a purity of 99.79 % vanadium solution.

Example 4

+60% 5#白油混合配成萃 取溶剂作为有机相； (1). Preparation of extraction solvent: 40% by mass

+60% 5# white oil is mixed into extraction solvent as organic phase;

(2). Extraction: take the extraction solvent in step (1), and extract the calcified vanadium-chromium slag leaching solution with a pH of 1.5 in a second-stage cross-flow extraction at a temperature of 30 °C, a ratio of O/A=1, and a time of 3 min , to obtain a loaded organic phase;

(3). Washing: wash the organic phase of step (1) with sulfuric acid solution, pH is 1.8, temperature is 50°C, compared with O/A=4, time is 2 min, and the washed organic phase is obtained;

(4). Back-extraction of chromium: 5-stage cross-flow back-extraction of the organic phase of step (2) with an ammonia solution with a pH of 8.0 at a temperature of 10 °C, compared with O/A = 5, and a time of 7 min, the obtained purity is 99.19% chromium solution and vanadium-loaded organic phase;

(5). Back-extraction of vanadium: 5-stage countercurrent back-extraction of the organic phase of step (3) with an ammonia solution with a pH of 13.0 at a temperature of 10 °C, compared with O/A=6, and a time of 2 min, the purity is 99.90 % vanadium solution.

Example 5

+50%氯庚烷混合配成萃取 溶剂作为有机相； (1). Preparation of extraction solvent: 50% by mass

+50% chloroheptane is mixed to prepare extraction solvent as organic phase;

(2). Extraction: take the extraction solvent in step (1), first-stage cross-flow extraction pH 1.4 calcification roasting vanadium-chromium slag leaching solution, temperature is 20 ℃, compared to O/A=1.1, time is 4 min, get load organic phase;

(3). Washing: wash the organic phase of step (2) with sulfuric acid solution, pH is 1.7, temperature is 10°C, compared to O/A=2.5, time is 4 min, and the washed organic phase is obtained;

(4). Back-extraction of chromium: 4-stage countercurrent back-extraction of the organic phase of step (3) with an ammonia solution with a pH of 8.3 at a temperature of 60 °C, compared with O/A=3, and a time of 2 minutes, the purity is 99.35%. Chromium solution and vanadium-loaded organic phase;

(5). Back-extraction of vanadium: 3-stage countercurrent back-extraction of the organic phase of step (4) with an ammonia solution with a pH of 13.1, a temperature of 40 °C, a comparison of O/A=1, a time of 7 min, and a purity of 99.83 % vanadium solution.

Example 6

+40%溴己烷混合配成 萃取溶剂作为有机相； (1). Preparation of extraction solvent: 60% by mass

+40% bromohexane is mixed to prepare extraction solvent as organic phase;

(2). Extraction: take the extraction solvent in step (1), the first-stage countercurrent extraction acidity is 1.3 vanadium-chromium mixed acid solution, the temperature is 10 ° C, the ratio O/A=1.2, the time is 5 min, and the loaded organic Mutually;

(3). Washing: wash the organic phase of step (2) with sulfuric acid solution, pH is 1.6, temperature is 35°C, compared with O/A=3.5, time is 3 min, and the washed organic phase is obtained;

(4). Back-extraction of chromium: 2-stage countercurrent back-extraction of the organic phase of step (3) with an aqueous ammonia solution with a pH of 8.5, the temperature is 55 °C, the ratio of O/A=2.5, the time is 5 min, and the purity is 99.36 % chromium solution and vanadium-loaded organic phase;

(5). Back-extraction of vanadium: 2-stage countercurrent back-extraction of the organic phase of step (4) with an aqueous ammonia solution with a pH of 13.2 at a temperature of 55 °C, compared with O/A=6, and a time of 3 min, the purity is 99.91 % vanadium solution.

Example 7

+80%磺化煤油混合配成萃取溶剂作为有 机相； (1). Preparation of extraction solvent: 20% by mass

+80% sulfonated kerosene is mixed to prepare extraction solvent as organic phase;

(2). Extraction: take the extraction solvent in step (1), 3-stage countercurrent extraction of a vanadium-chromium mixed acid solution with an acidity of 1.6, a temperature of 30 °C, a ratio of O/A = 1.8, and a time of 6 min, to obtain a loaded organic Mutually;

(3). Washing: washing the organic phase of step (2) with sulfuric acid solution, pH is 1.5, temperature is 55°C, compared to O/A=3.0, time is 6 min, and the washed organic phase is obtained;

(4). Back-extraction of chromium: 2-stage countercurrent back-extraction of the organic phase of step (3) with an aqueous ammonia solution with a pH of 8.0, the temperature is 45 °C, the ratio of O/A=2.0, the time is 6 min, and the purity is 99.46 % chromium solution and vanadium-loaded organic phase;

(5). Back-extraction of vanadium: 4-stage countercurrent back-extraction of the organic phase of step (4) with an ammonia solution with a pH of 13.0 at a temperature of 45 °C, compared with O/A=5, and a time of 4 min, the purity is 99.93 % vanadium solution.

Example 8

+70%4#白油混合配成萃取溶剂作为有机 相； (1). Preparation of extraction solvent: 30% by mass

+70% 4# white oil is mixed into extraction solvent as organic phase;

(2). Extraction: take the extraction solvent in step (1), 4-stage countercurrent extraction of a mixed acid solution of vanadium and chromium with an acidity of PH of 1.9, a temperature of 40°C, a ratio of O/A = 1.8, and a time of 2 minutes to obtain a load The organic phase;

(3). Washing: washing the organic phase of step (2) with sulfuric acid solution, the pH is 1.5, the temperature is 40°C, the comparison O/A=2.5, the time is 3 min, and the washed organic phase is obtained;

(4). Back-extraction of chromium: 2-stage countercurrent back-extraction of the organic phase of step (3) with an aqueous ammonia solution with a pH of 8.0, the temperature is 35 °C, the ratio of O/A=3.0, the time is 2 min, and the purity is 99.46 % chromium solution and vanadium-loaded organic phase;

(5). Back-extraction of vanadium: 6-stage countercurrent back-extraction of the organic phase of step (4) with an ammonia solution with a pH of 12.8 at a temperature of 25 °C, compared with O/A=4, and a time of 1 min, the purity is 99.93 % vanadium solution.

To sum up, using the process method of the present invention, high-purity vanadium liquid and chromium liquid can be obtained.

Claims (5)

1. a kind of extraction solvent that extracts and separates vanadium-chromium simultaneously from vanadium-chromium solution, it is characterized in that this extraction solvent is mixed by extraction agent and thinner and forms, and described extraction agent is the water solubility that solubility is lower than 0.5g/L Amide, the diluent is an inert organic solvent, the extractant is N-alkylamide and N,N,N,N-tetraalkyldiamide or the solubility of multiple amide groups is less than 0.5g /L one or more of the water-soluble amides, the alkyl group is a straight-chain alkyl group or a branched-chain alkyl group, and the diluent is a sulfonated kerosene, white oil and a liquid halogenated One or more of the inert organic solvents for hydrocarbon compounds, when one of the extractant and the diluent is solid at 25°C or both are solid at 25°C, the amount of the extractant in the extraction solvent is solid. The mass ratio is 2%~100%, and the mass ratio of the diluent is 0~98%. When both the extractant and the diluent are liquid at 25℃; the volume ratio of the extractant in the extraction solvent is 5%-100%. %, the volume ratio of the diluent is 0~95%, and the solubility of the N-alkylamide and N,N,N,N-tetraalkyldiamide or containing multiple amide groups is lower than 0.5g/ In the water-soluble amide of L, the number of carbon atoms in the alkyl group in the acyl group is 1-18, the number of carbon atoms in the alkyl group directly connected to the nitrogen atom in the N-alkyl amide is 1-18, and the number of carbon atoms in the alkyl group in the N-alkylamide is 1-18. , N,N,N-tetraalkyldiamide or the alkyl group directly connected to the nitrogen atom in multiple amide groups is the same alkyl group or a different alkyl group, and these two directly connected to the nitrogen atom The number of carbon atoms of each alkyl group is 1-18, the carbon number of the sulfonated kerosene is 11-17, the type of the white oil is 1#-7#, and the halogenated hydrocarbons that are liquid at room temperature The compound is one or more of chlorinated hydrocarbons, brominated hydrocarbons or iodohydrocarbons inert organic solvents. 2. a method for simultaneously extracting and separating vanadium and chromium from a vanadium-containing chromium solution, is characterized in that the processing steps of this extraction and separation method are as follows: (1). Preparation of extraction solvent: the extraction solvent is composed of a mixture of an extractant and a diluent. The extractant is a water-soluble amide with a solubility of less than 0.5 g/L, and the diluent is an inert organic solvent. The two are mixed. Dubbed extraction solvent as organic phase; (2) Extraction: take the extraction solvent in step (1) to extract the vanadium-containing chromium solution, the PH of the vanadium-chromium-containing solution is 1.3-10, the extraction temperature is 10-90 ℃, compared with O/A=0.4-4.0, The time is 1-10 min, the extraction method is counter-current extraction, fractional extraction or cross-current extraction, and the number of extraction stages is 1-35 to obtain the loaded organic phase; (3). Washing: washing the loaded organic phase obtained in step (2) with a solution, the pH of the solution is 1.2～9.0, the temperature is 10～90℃, the ratio O/A=0.4～40, and the time is 1～10 min, to obtain the organic phase after washing; (4). Back-extraction of chromium: take the alkaline solution for back-extraction of the washed organic phase obtained in step (3), the extraction temperature is 10 ℃ ~ 60 ℃, compared with O/A = 1 ~ 20, and the time is 1 ~ 8 min, the pH of the alkaline solution is 7.2-10.0, the back-extraction method is counter-current extraction or cross-current extraction, and the number of extraction stages is 1-10, to obtain high-purity chromium solution and vanadium-loaded organic phase; (5). Back-extraction of vanadium: take the alkaline solution for back-extraction of the vanadium-loaded organic phase obtained in step (4), the extraction temperature is 10 ℃ ~ 60 ℃, compared with O/A = 1 ~ 10, and the time is 1 ~ For 10 min, the pH of the alkaline solution is 7.5-13.5, the back-extraction method is counter-current extraction or cross-current extraction, and the extraction stages are 1-10 to obtain a high-purity vanadium solution. 3. a kind of method that simultaneously extracts and separates vanadium and chromium from vanadium-containing chromium solution according to claim 2, it is characterized in that described vanadium-containing chromium solution comprises vanadium-titanium magnetite smelting waste residue leaching solution, two kinds and two kinds The mixed solution of the above polymetallic sulfuric acid medium containing vanadium or chromium, wherein the solution contains both vanadium and chromium; the valence of vanadium is tetravalent or pentavalent, or a mixture of tetravalent and pentavalent vanadium; the valence state of chromium Is trivalent or hexavalent, or a mixture of trivalent and hexavalent. 4. a kind of method for simultaneously extracting and separating vanadium and chromium from vanadium-chromium solution according to claim 2, is characterized in that in described step (4) and step (5), alkaline substance is ammoniacal liquor, sodium hydroxide , one or several mixtures of potassium hydroxide, calcium hydroxide, sodium carbonate, ammonium carbonate, potassium carbonate, ammonium chloride, and ammonium sulfate. 5. A method for simultaneously extracting and separating vanadium and chromium from a vanadium-chromium solution according to claim 2, wherein the solution in the step (3) is an acidic solution, and the acidic solution comprises sulfuric acid or nitric acid, which is not easily Oxidized inorganic acids, or a mixture containing one or both of these inorganic acids.