阅读说明：本技术 一种从含铬偏钒酸铵溶液中萃取分离铬的方法 (Method for extracting and separating chromium from chromium-containing ammonium metavanadate solution ) 是由 王少娜 杜浩 冯曼 刘彪 王欣然 于 2018-06-25 设计创作，主要内容包括：本发明提供了一种从含铬偏钒酸铵溶液中萃取分离铬的方法,所述方法包括以下步骤：将含有胺类萃取剂和改性剂的有机溶液与含铬偏钒酸铵溶液混合进行萃取,得到上层为含铬有机相、下层为含钒水相的分层体系；将得到的含铬有机相与反萃剂溶液混合进行反萃处理,得到下层含铬水相和上层有机相,所述上层有机相返回循环使用。本发明所述方法可实现含铬偏钒酸铵溶液中铬的高效萃取,铬的萃取率可接近100％,反萃率可达到100％,除铬后的溶液可以直接用于制备高纯偏钒酸铵；所述方法工艺流程简短,操作方便,无第三相生成,无需重复调节pH值,对弱碱性溶液和强碱性溶液都适用,萃取剂可循环使用,成本低廉。(The invention provides a method for extracting and separating chromium from a chromium-containing ammonium metavanadate solution, which comprises the following steps: mixing an organic solution containing an amine extractant and a modifier with a chromium-containing ammonium metavanadate solution for extraction to obtain a layered system with an upper layer containing a chromium organic phase and a lower layer containing a vanadium water phase; and mixing the obtained chromium-containing organic phase with a stripping agent solution for stripping treatment to obtain a lower chromium-containing aqueous phase and an upper organic phase, and returning the upper organic phase for recycling. The method can realize the high-efficiency extraction of chromium in the chromium-containing ammonium metavanadate solution, the extraction rate of the chromium can approach 100 percent, the back extraction rate can reach 100 percent, and the solution after chromium removal can be directly used for preparing high-purity ammonium metavanadate; the method has the advantages of short process flow, convenient operation, no generation of a third phase, no need of repeatedly adjusting the pH value, applicability to both weak alkaline solution and strong alkaline solution, recyclable extracting agent and low cost.)

1. A method for extracting and separating chromium from a chromium-containing ammonium metavanadate solution, which is characterized by comprising the following steps:

(1) mixing an organic solution containing an amine extractant and a modifier with a chromium-containing ammonium metavanadate solution for extraction to obtain a system with upper and lower layers of coexisting liquids, wherein the upper layer is a chromium-containing organic phase, and the lower layer is a vanadium-containing water phase;

(2) and (2) mixing the chromium-containing organic phase obtained in the step (1) with a stripping agent solution for stripping treatment to obtain a lower chromium-containing aqueous phase and an upper organic phase, and returning the upper organic phase to the step (1) for recycling.

2. The method of claim 1, wherein the amine-based extractant of step (1) comprises a tertiary and/or quaternary amine compound;

preferably, the amine extractant in step (1) comprises any one or a combination of at least two of dicyclohexylamine, trioctylamine or trioctylmethylammonium chloride, preferably trioctylmethylammonium chloride.

3. The process of claim 1 or 2, wherein the modifier of step (1) comprises a basic compound comprising a lewis base functional group;

preferably, the modifier of step (1) comprises any one or a combination of at least two of an organic phosphine oxide, a sulfone or a sulfoxide;

preferably, the organic phosphine oxide comprises any one of tributyl phosphate, tributyl phosphine oxide, trioctyl phosphine oxide, tris (2-ethylhexyl) phosphate or bis (2-ethylhexyl) phosphate, or a combination of at least two thereof, preferably trioctyl phosphine oxide;

preferably, the sulfone comprises any one or a combination of at least two of diphenyl sulfone, sulfolene, 4' -dihydroxydiphenyl sulfone, 4' -diaminodiphenyl sulfone, or 3,3' -diaminodiphenyl sulfone, preferably diphenyl sulfone;

preferably, the sulfoxide comprises diphenyl sulfoxide.

4. The method according to any one of claims 1 to 3, wherein the organic solution containing the amine extractant and the modifier of step (1) further comprises a diluent;

preferably, the diluent comprises C₆～C₁₀Alkane, C₇～C₈Of aromatic hydrocarbons or C₈～C₁₀Any one or a combination of at least two of the fatty alcohols of (a);

preferably, said C₆～C₁₀The alkane comprises any one or the combination of at least two of n-hexane, n-octane and n-decane, and is preferably n-octane;

preferably, said C₇～C₈The aromatic hydrocarbon of (a) includes toluene and/or o-xylene;

preferably, said C₈～C₁₀The fatty alcohol of (b) includes n-octanol and/or n-decanol, preferably n-octanol.

5. The method according to any one of claims 1 to 4, wherein the molar concentration of the amine extractant in the organic solution in the step (1) is 0.05 to 1.0mol/L, preferably 0.05 to 0.2 mol/L;

preferably, when the modifier in the step (1) is in a liquid phase, the volume fraction of the modifier in the organic solution is 0-75%, and preferably 5-50%;

preferably, when the modifier in the step (1) is in a solid phase, the molar concentration of the modifier in the organic solution is 0.05-1.0 mol/L, and preferably 0.05-0.2 mol/L.

6. The method according to any one of claims 1 to 5, wherein the pH value of the chromium-containing ammonium metavanadate solution in step (1) is 7 to 14, preferably 7 to 10;

preferably, the concentration of chromium in the chromium-containing ammonium metavanadate solution in the step (1) is 1-1000 mg/L, and preferably 10-300 mg/L;

preferably, the concentration of vanadium in the chromium-containing ammonium metavanadate solution in the step (1) is 0.03-30 g/L, and preferably 0.3-9 g/L.

7. The method according to any one of claims 1 to 6, wherein the volume ratio of the chromium-containing ammonium metavanadate solution in the step (1) to the organic solution is (1-50): (8-1), preferably (1-10): 1;

preferably, the extraction in the step (1) is at least one-stage countercurrent extraction, and preferably three-stage to eight-stage countercurrent extraction;

preferably, the back extraction in the step (2) is at least one stage of counter current back extraction, preferably two to five stages of counter current back extraction;

preferably, the time of the single-stage extraction in the step (1) and the single-stage extraction in the back extraction in the step (2) is independently at least 1min, preferably 5-60 min, and further preferably 20-40 min;

preferably, after the extraction in the step (1) and the back extraction in the step (2), the centrifugal and/or standing treatment is independently carried out to obtain a layered system;

preferably, the vanadium-containing aqueous phase in step (1) is used for preparing ammonium metavanadate;

preferably, the purity of the prepared ammonium metavanadate reaches more than 99.9 wt%.

8. The process according to any one of claims 1 to 7, wherein the stripping agent of step (2) comprises any one of alkali metal hydroxide, hydrochloric acid, sulfuric acid or nitric acid;

preferably, the alkali metal hydroxide is sodium hydroxide.

9. The process according to any one of claims 1 to 8, wherein the concentration of the stripping agent solution in the step (2) is 0.1 to 6.0mol/L, preferably 0.5 to 5.0 mol/L;

preferably, the volume ratio of the stripping agent solution in the step (2) to the chromium-containing organic phase obtained in the step (1) is 1 (1-50), and preferably 1 (1-30).

10. Method according to any of claims 1-9, characterized in that the method comprises the steps of:

(1) mixing an organic solution containing an amine extractant, a modifier and a diluent with a chromium-containing ammonium metavanadate solution with a pH value of 7-14 according to a volume ratio of (1-8) to (50-1) for extraction, wherein the molar concentration of the extractant in the organic solution is 0.05-1.0 mol/L, the volume fraction of the modifier in the organic solution is 0-75% when the modifier is a liquid phase, the molar concentration of the modifier in the organic solution is 0.05-1.0 mol/L when the modifier is a solid phase, the single-stage extraction time is at least 1min, centrifuging and/or standing to obtain a system with coexisting upper and lower layers of liquid, the upper layer is a chromium-containing organic phase, the lower layer is a vanadium-containing aqueous phase, and the vanadium-containing aqueous phase is used for preparing ammonium metavanadate;

(2) and (2) mixing the chromium-containing organic phase obtained in the step (1) with a stripping agent solution with the concentration of 0.1-6.0 mol/L according to the volume ratio of (1-50) to 1, carrying out stripping treatment, wherein the single-stage stripping time is at least 1min, centrifuging and/or standing to obtain a lower chromium-containing aqueous phase and an upper organic phase, and returning the upper organic phase to the step (1) for recycling.

Technical Field

The invention belongs to the technical field of hydrometallurgy, and relates to a method for extracting and separating chromium from a chromium-containing ammonium metavanadate solution.

Background

Vanadium and chromium are adjacent in position in the periodic table of elements, have similar properties and are often in natureThe vanadium slag is present in minerals such as chromite, vanadium titano-magnetite and the like in a co-associated form, more than 88% of the output of the vanadium titano-magnetite in the world comes from the vanadium titano-magnetite, the vanadium slag obtained by smelting the vanadium titano-magnetite is a main raw material for extracting vanadium in the vanadium chemical industry, and the vanadium slag generally contains 10-20% of V₂O₅3-6% of Cr₂O₃In the vanadium extraction process of the vanadium slag, part of chromium and vanadium have the same trend, enter the leaching solution together and then enter the subsequent preparation process of the vanadium product, and if chromium is not effectively removed, the quality of the vanadium product is greatly influenced.

In recent years, with the rapid development of the field of energy storage batteries, the demand for high-purity vanadium products, particularly high-purity ammonium metavanadate with the purity of more than 99.9% is increasing, and the demand for a method for efficiently removing chromium as an important impurity is becoming strong. At present, the method for separating vanadium and chromium from solution mainly comprises a precipitation method, a crystallization method, an ion exchange method, a solvent extraction method and the like.

The precipitation method mainly utilizes the difference of precipitation conditions of vanadium and chromium in the solution to precipitate vanadium and chromium in the solution step by controlling the pH value of the solution or adding a precipitator. CN 106186064A discloses a method for producing high-purity ammonium metavanadate by deeply removing chromium, which comprises the steps of regulating the pH value of a solution for three times, and respectively adding a precipitator, a reducing agent and another precipitator to realize deep removal of chromium. The crystallization method is similar to the precipitation method, and usually adopts fractional crystallization, namely a method of firstly cooling and crystallizing to obtain vanadate, and then evaporating and crystallizing to obtain chromate to realize the primary separation of vanadium and chromium. The method is generally suitable for extracting vanadium from vanadium slag or co-extracting vanadium and chromium from vanadium slag by adopting a strong alkaline solution, and for example, CN 102127655A, CN 102534232A and CN101812588A realize co-extraction of vanadium and chromium from vanadium slag. However, the fractional crystallization method is limited by separation efficiency and solution entrainment, and the obtained vanadate intermediate product can carry chromium, so that the subsequent conversion of the product is greatly influenced.

The ion exchange method is to separate vanadium and chromium in an aqueous solution by taking anion exchange resin as a separation medium, and the difference of the adsorption capacity of the ion exchange resin on the vanadium and chromium is regulated and controlled by controlling the pH value of the solution. Although the method has good effect of separating vanadium and chromium, the adsorption capacity of the resin is limited, the regeneration performance is not good, the problems of large resin consumption and high production cost can be caused, the operation is complex, and large-scale continuous production is not easy to realize. CN 107190155 a discloses a method for extracting vanadium and chromium from a mixed solution containing vanadium and chromium, which comprises adsorbing and separating vanadium in the solution by using exchange resin under acidic condition, desorbing vanadium and further precipitating vanadium to prepare vanadate, and precipitating chromium to obtain chromium product.

The solvent extraction method for separating vanadium and chromium has the advantages of good separation effect, large extraction capacity, easiness in continuous production and the like, but the existing vanadium and chromium separation method mostly focuses on the fact that a solution is acidic, neutral or weakly alkaline, and mainly extracts and separates vanadium. The pH value of the solution obtained after the vanadate is dissolved is more than 11-14, the concentration of vanadium in the solution is high, the concentration of chromium in the solution is low, the existing method is adopted, acid needs to be added firstly to adjust the pH value of the solution, the steps are complex, the vanadium-chromium separation efficiency is low, and efficient separation of chromium is difficult to achieve. CN 104694749 a discloses a method for extracting and separating vanadium and chromium from an alkaline aqueous solution, wherein an amine extractant is used to extract and separate vanadium and chromium from an alkaline aqueous solution, but the extraction saturation capacity of the extractant on vanadium is reduced by the impurities, and the impurities are precipitated together with vanadium in the subsequent vanadium precipitation operation to affect the purity of the product.

In summary, how to simply and efficiently separate chromium from an alkaline solution containing vanadium and chromium to facilitate the subsequent preparation of high-purity vanadium products is one of the problems to be solved in the current research.

Disclosure of Invention

Aiming at the problems in the prior art, the invention aims to provide a method for extracting and separating chromium from a chromium-containing ammonium metavanadate solution, the method extracts and separates chromium from the chromium-containing ammonium metavanadate solution by adopting an organic extraction solution, the chromium separation efficiency is high, and the solution after chromium separation can be directly used for preparing high-purity ammonium metavanadate; the method has simple process flow, recyclable organic extraction solution and low cost.

In order to achieve the purpose, the invention adopts the following technical scheme:

the invention provides a method for extracting and separating chromium from a chromium-containing ammonium metavanadate solution, which comprises the following steps:

(1) mixing an organic solution containing an amine extractant and a modifier with a chromium-containing ammonium metavanadate solution for extraction to obtain a system with upper and lower layers of coexisting liquids, wherein the upper layer is a chromium-containing organic phase, and the lower layer is a vanadium-containing water phase;

(2) and (2) mixing the chromium-containing organic phase obtained in the step (1) with a stripping agent solution for stripping treatment to obtain a lower chromium-containing aqueous phase and an upper organic phase, and returning the upper organic phase to the step (1) for recycling.

In the invention, the organic solution containing the amine extractant and the modifier is adopted to extract and separate chromium with relatively low content in the chromium-containing ammonium metavanadate solution, and the principle of extracting chromium is as follows: the apparent alkalinity of an extraction system is adjusted by adding modifiers with different alkalities into an amine extractant, so that the binding capacity of metavanadate ions and the extractant is weakened, the selective extraction and separation of vanadium and chromium are realized, the extraction rate of chromium is high, the separation effect is obvious, the dosage of the extractant is small, the extractant can be recycled, and the cost is low.

The following technical solutions are preferred but not limited to the technical solutions provided by the present invention, and the technical objects and advantages of the present invention can be better achieved and realized by the following technical solutions.

As a preferred technical scheme of the invention, the amine extractant in the step (1) comprises a tertiary amine and/or quaternary amine compound.

Preferably, the amine extractant of step (1) comprises any one of dicyclohexylamine, trioctylamine or trioctylmethylammonium chloride or a combination of at least two of them, typical but non-limiting examples of which are: a combination of dicyclohexylamine and trioctylamine, a combination of trioctylamine and trioctylmethylammonium chloride, a combination of dicyclohexylamine, trioctylamine and trioctylmethylammonium chloride, and the like, preferably trioctylmethylammonium chloride.

In the present invention, the amine extractants used include weakly basic, easily protonated lower amines including dicyclohexylamine, trioctylamine, etc., and strongly basic quaternary ammonium compounds including trioctylmethylammonium chloride, etc., which are preferred because: the quaternary ammonium compound is a strong-base cationic extractant, can react with oxyacid salt anions in a strong base system, and realizes high-efficiency extraction and separation of chromium.

As a preferred technical scheme of the invention, the modifier in the step (1) comprises a basic compound containing Lewis base functional groups.

Preferably, the modifier of step (1) comprises any one of, or a combination of at least two of, an organophosphine oxide, a sulfone or a sulfoxide, typical but non-limiting examples of such combinations being: combinations of organophosphine oxides and sulfones, sulfones and sulfoxides, combinations of organophosphine oxides, sulfones and sulfoxides, and the like.

Preferably, the organic phosphine oxide comprises any one of tributyl phosphate, tributyl phosphine oxide, trioctyl phosphine oxide, tris (2-ethylhexyl) phosphate or bis (2-ethylhexyl) phosphate, or a combination of at least two of these, typical but non-limiting examples being: a combination of tributyl phosphate and tributyl phosphine oxide, a combination of tributyl phosphine oxide and trioctyl phosphine oxide, a combination of tributyl phosphine oxide, trioctyl phosphine oxide and tris (2-ethylhexyl) phosphate, a combination of tributyl phosphate, trioctyl phosphine oxide and bis (2-ethylhexyl) phosphate, and the like, with trioctyl phosphine oxide being preferred.

Preferably, the sulfone comprises any one or a combination of at least two of diphenyl sulfone, sulfolene, 4' -dihydroxydiphenyl sulfone, 4' -diaminodiphenyl sulfone or 3,3' -diaminodiphenyl sulfone, typical but non-limiting examples of which are: a combination of diphenyl sulfone and sulfolene, a combination of 4,4 '-dihydroxydiphenyl sulfone and 4,4' -diaminodiphenyl sulfone, a combination of sulfolene, 4,4 '-dihydroxydiphenyl sulfone and 3,3' -diaminodiphenyl sulfone, and the like, with diphenyl sulfone being preferred.

Preferably, the sulfoxide comprises diphenyl sulfoxide.

In the invention, the modifier is a basic compound with a stronger Lewis base functional group, and comprises organic phosphine oxide, sulfone or sulfoxide and the like, and can adjust the apparent alkalinity of an extraction system, so that the binding capacity of metavanadate ions and the extraction agent is weakened, and the binding capacity of chromate ions and the extraction agent is strengthened, thereby realizing the selective extraction of chromium.

In a preferred embodiment of the present invention, the organic solution containing the amine extractant and the modifier in step (1) further comprises a diluent.

In the present invention, the diluent is added to the extractant in order to reduce the concentration of the extract in the organic phase and prevent the supersaturated extract from accumulating at the oil-water two-phase interface, thereby hindering the extraction process.

Preferably, the diluent comprises C₆～C₁₀Alkane, C₇～C₈Of aromatic hydrocarbons or C₈～C₁₀Of any one or a combination of at least two of the fatty alcohols of (a), typical but non-limiting examples being: c₆～C₁₀Alkane and C₇～C₈Combinations of aromatic hydrocarbons of (2), C₇～C₈And C is an aromatic hydrocarbon₈～C₁₀A combination of fatty alcohols of (C)₆～C₁₀Alkane, C₇～C₈And C is an aromatic hydrocarbon₈～C₁₀Combinations of the fatty alcohols of (a) and the like.

In the invention, when the type of the diluent is selected, the organic diluent with reducibility such as kerosene, sulfonated kerosene and the like is avoided, because chromium exists in hexavalent form in the alkaline vanadium-chromium-containing solution and is easy to generate redox reaction when being contacted with a solvent with reducibility for a long time, the diluent is selected from C which is insoluble in water and has strong oxidation resistance₆～C₁₀Alkane, C₇～C₈Of aromatic hydrocarbons or C₈～C₁₀The fatty alcohol of (1).

Preferably, said C₆～C₁₀The alkane of (a) includes any one of n-hexane, n-octane or n-decane, or a combination of at least two thereof, as typical but non-limiting examples: a combination of n-hexane and n-octane, a combination of n-octane and n-decane, n-hexane, n-octane anda combination of n-decanes, etc., preferably n-octane.

Preferably, said C₇～C₈The aromatic hydrocarbon of (a) includes toluene and/or o-xylene.

Preferably, said C₈～C₁₀The fatty alcohol of (b) includes n-octanol and/or n-decanol, preferably n-octanol.

In a preferred embodiment of the present invention, the molar concentration of the amine extractant in the organic solution in step (1) is 0.05 to 1.0mol/L, for example, 0.05mol/L, 0.1mol/L, 0.15mol/L, 0.2mol/L, 0.3mol/L, 0.4mol/L, 0.5mol/L, 0.6mol/L, 0.8mol/L, or 1.0mol/L, but not limited to the above-mentioned values, and values not listed in this range are also applicable, and preferably 0.05 to 0.2 mol/L.

Preferably, when the modifier in step (1) is in a liquid phase, the volume fraction of the organic solution is 0 to 75%, for example, 0, 5%, 10%, 15%, 20%, 30%, 40%, 50%, 60%, 70%, or 75%, but not limited to the recited values, and values not recited in this range are also applicable, preferably 5 to 50%.

Preferably, when the modifier in step (1) is in a solid phase, the molar concentration of the modifier in the organic solution is 0.05 to 1.0mol/L, such as 0.05mol/L, 0.1mol/L, 0.15mol/L, 0.2mol/L, 0.3mol/L, 0.4mol/L, 0.5mol/L, 0.6mol/L, 0.8mol/L, or 1.0mol/L, but not limited to the values listed, and values not listed in the range of the values are equally applicable, preferably 0.05 to 0.2 mol/L.

In the invention, the content of the diluent in the organic solution is adjusted according to the content of the extracting agent and the modifying agent so as to ensure the concentration of the extracting agent and the modifying agent.

In a preferred embodiment of the present invention, the pH of the chromium-containing ammonium metavanadate solution in the step (1) is 7 to 14, for example, 7, 8, 9, 10, 11, 12, 13, 14, etc., but the pH is not limited to the above-mentioned values, and values not listed in the above-mentioned range are also applicable, and preferably 7 to 10.

Preferably, the concentration of chromium in the chromium-containing ammonium metavanadate solution in the step (1) is 1-1000 mg/L, such as 1mg/L, 10mg/L, 50mg/L, 100mg/L, 200mg/L, 300mg/L, 400mg/L, 500mg/L, 600mg/L, 800mg/L or 1000mg/L, but not limited to the recited values, and values not recited in the range of values are also applicable, preferably 10-300 mg/L.

Preferably, the concentration of vanadium in the chromium-containing ammonium metavanadate solution in step (1) is 0.03-30 g/L, such as 0.03g/L, 0.1g/L, 0.3g/L, 0.5g/L, 1g/L, 3g/L, 5g/L, 9g/L, 15g/L, 20g/L, 25g/L or 30g/L, but is not limited to the recited values, and values not recited in this range are equally applicable, preferably 0.3-9 g/L.

In the invention, the pH value span of the chromium-containing ammonium metavanadate solution is large, which indicates that the method can treat the solution from alkalescence to strong alkalinity, and has a wide application range, wherein the content of vanadium is higher than that of chromium, so that the chromium is extracted by selecting a proper extracting agent during extraction, the using amount of the extracting agent can be greatly reduced, and the cost is reduced.

In a preferred embodiment of the present invention, the volume ratio of the chromium-containing ammonium metavanadate solution in the step (1) to the organic solution is (1 to 50): 8 to 1, for example, 1:8, 1:4, 1:1, 2:1, 5:1, 10:1, 20:1, 30:1, 40:1 or 50:1, but the present invention is not limited to the above-mentioned values, and values not listed in the above-mentioned value range are also applicable, and (1 to 10):1 is preferable.

Preferably, the extraction in step (1) is at least one stage of countercurrent extraction, such as one, two, three, four, five, six or eight stages, but not limited to the recited values, and values not recited in the range of values are equally applicable, preferably three to eight stages of countercurrent extraction.

Preferably, the stripping in step (2) is at least one stage of counter-current stripping, such as one stage, two stages, three stages, four stages, five stages, six stages or eight stages, but not limited to the recited values, and the values not recited in the range of the values are also applicable, and preferably two to five stages of counter-current stripping are used.

Preferably, the time of the single-stage extraction in the step (1) and the back extraction in the step (2) is independently at least 1min, such as 1min, 5min, 10min, 20min, 25min, 30min, 35min, 40min, 50min, 60min or 80min, but not limited to the enumerated values, and the same applies to the non-enumerated values in the range of the enumerated values, preferably 5 to 60min, and more preferably 20 to 40 min.

Preferably, after the extraction in the step (1) and the back extraction in the step (2), the centrifugal and/or standing treatment is independently carried out, so as to obtain a layered system.

In the invention, the purpose of the back extraction treatment is to back extract chromium from the organic phase, so that the chromium is convenient to recycle, and meanwhile, the amine group in the amine extractant is regenerated, thereby realizing the recycling of the extractant.

Preferably, the vanadium-containing aqueous phase of step (1) is used for preparing ammonium metavanadate.

Preferably, the purity of the ammonium metavanadate obtained is more than 99.9 wt%, such as 99.9 wt%, 99.92 wt%, 99.94 wt%, 99.96 wt% or 99.98 wt%, etc., but is not limited to the recited values, and values not recited in the range of values are also applicable.

As a preferable technical scheme of the invention, the stripping agent in the step (2) comprises any one of alkali metal hydroxide, hydrochloric acid, sulfuric acid or nitric acid.

Preferably, the alkali metal hydroxide is sodium hydroxide.

As a preferred embodiment of the present invention, the concentration of the stripping solution in step (2) is 0.1 to 6.0mol/L, for example, 0.1mol/L, 0.5mol/L, 1.0mol/L, 1.5mol/L, 2.0mol/L, 2.5mol/L, 3.0mol/L, 3.5mol/L, 4.0mol/L, 5.0mol/L or 6.0mol/L, but not limited to the above-mentioned values, and the values not listed in the above-mentioned value range are also applicable, and preferably 0.5 to 5.0 mol/L.

Preferably, the volume ratio of the stripping agent solution in the step (2) to the chromium-containing organic phase obtained in the step (1) is 1 (1-50), such as 1:1, 1:3, 1:6, 1:10, 1:15, 1:20, 1:25, 1:30, 1:40 or 1:50, but not limited to the recited values, and the same applies to the values not recited in the range of the recited values, and preferably 1 (1-30).

As a preferred technical scheme of the invention, the method comprises the following steps:

(1) mixing an organic solution containing an amine extractant, a modifier and a diluent with a chromium-containing ammonium metavanadate solution with a pH value of 7-14 according to a volume ratio of (1-8) to (50-1) for extraction, wherein the molar concentration of the extractant in the organic solution is 0.05-1.0 mol/L, the volume fraction of the modifier in the organic solution is 0-75% when the modifier is a liquid phase, the molar concentration of the modifier in the organic solution is 0.05-1.0 mol/L when the modifier is a solid phase, the single-stage extraction time is at least 1min, centrifuging and/or standing to obtain a system with coexisting upper and lower layers of liquid, the upper layer is a chromium-containing organic phase, the lower layer is a vanadium-containing aqueous phase, and the vanadium-containing aqueous phase is used for preparing ammonium metavanadate;

(2) and (2) mixing the chromium-containing organic phase obtained in the step (1) with a stripping agent solution with the concentration of 0.1-6.0 mol/L according to the volume ratio of (1-50) to 1, carrying out stripping treatment, wherein the single-stage stripping time is at least 1min, centrifuging and/or standing to obtain a lower chromium-containing aqueous phase and an upper organic phase, and returning the upper organic phase to the step (1) for recycling.

Compared with the prior art, the invention has the following beneficial effects:

(1) the method can realize the high-efficiency extraction of chromium and the zero extraction of vanadium in the alkaline chromium-containing ammonium metavanadate solution, the vanadium-chromium separation effect is obvious, the extraction rate of chromium can approach 100 percent, the back extraction rate of chromium can reach 100 percent, the solution after chromium removal can be directly used for preparing high-purity ammonium metavanadate, and the purity of ammonium metavanadate can reach more than 99.9 weight percent;

(2) the method has the advantages of short process flow, convenient operation, no generation of a third phase, no need of repeatedly adjusting the pH value, applicability to both weak alkaline solution and strong alkaline solution, recyclable extracting agent and low cost.

Detailed Description

In order to better illustrate the present invention and facilitate the understanding of the technical solutions, the present invention is further described in detail below. The following examples are merely illustrative of the present invention and do not represent or limit the scope of the claims, which are defined by the claims.

In part, embodiments of the invention provide a method for extracting and separating chromium from a chromium-containing ammonium metavanadate solution, comprising the steps of:

(1) mixing an organic solution containing an amine extractant and a modifier with a chromium-containing ammonium metavanadate solution for extraction to obtain a system with upper and lower layers of coexisting liquids, wherein the upper layer is a chromium-containing organic phase, and the lower layer is a vanadium-containing water phase;

(2) and (2) mixing the chromium-containing organic phase obtained in the step (1) with a stripping agent solution for stripping treatment to obtain a lower chromium-containing aqueous phase and an upper organic phase, and returning the upper organic phase to the step (1) for recycling.

The following are typical but non-limiting examples of the invention: