Method for separating rare earth ions by extraction of liquid-liquid-liquid three-phase system

Abstract

The invention relates to a method for separating rare earth ions by extraction of a liquid-liquid-liquid three-phase system, and belongs to the technical field of rare earth extraction and separation. The method comprises the following steps of: adding a chemical complexing agent into an aqueous solution containing the rare earth ions, regulating the acidity of the solution, adding a water-soluble high polymer and an inorganic electrolyte salt, oscillating and mixing at room temperature, and obtaining a liquid phase system of upper and lower layers; adding a hydrophobic ionic liquid, fully mixing the solution at room temperature, and obtaining an insoluble three-liquid phase coexistence system of upper, middle and lower layers; and respectively taking the upper, middle and lower phases ofthe three-liquid phase system, and reclaiming the rare earth ions by using an electro-deposition method. According to the method, a volatile organic solvent is not used, so that the phase forming behavior and the phase separation process of the three-phase system are easily artificially controlled; and light, medium and heavy rare earth ions are selectively enriched or grouped and separated in three different liquid phases respectively. Compared with conventional oil-water two-phase separation, the method has the advantages that: the process flow is greatly simplified, the method is quick in phase separation and avoids emulsifying, and the hydrophilic and hydrophobic properties of the ionic liquid three-phase system are easily controlled.

Description

technical field

[0001] The invention belongs to the technical field of solvent extraction and separation of rare earth ions, and in particular relates to a liquid-liquid-liquid three-phase system extraction and separation method for rare earth ions. Background technique

[0002] Solvent extraction is the most important method for mutual separation and purification of rare earth elements. Due to the extremely similar chemical properties between rare earth elements, the separation coefficient between adjacent rare earth elements is extremely low. Traditional organic phase-aqueous two-liquid phase extraction systems generally improve the selectivity of separation by synthesizing high-efficiency rare earth extractants, screening extraction systems, and optimizing cascade extraction processes. However, for the complex system where multiple rare earths coexist, due to the changeable phase behavior during the extraction process, there are many factors affecting the extraction sele...

Examples

Embodiment 1

[0033] Dissolve the oxides of lanthanum, europium, and ytterbium with 5 mL of 0.1 mol / L aqueous hydrochloric acid solution to form a mixed solution containing lanthanum, europium, and ytterbium ions (the initial concentrations of the three rare earth metal ions are all 100 mg / L). EDTA is added, and the ratio of the added molar amount to the sum of the molar amounts of the three rare earth ions in the initial aqueous solution is 1:1. Adjust the pH of the mixed solution to 5, and stir thoroughly at room temperature. Then add EOPO 2500 and sodium sulfate, EOPO accounts for 20% by weight in the mixed solution, and sodium sulfate accounts for 30% by weight. After fully shaking and mixing at room temperature, centrifugation is carried out to obtain a two-liquid phase system in which upper and lower layers coexist. Then, 5 mL of ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate ([C4mim][PF6]) was added to the above-mentioned two-liquid phase system, and the mixture was ce...

Embodiment 2

[0035] Dissolve the oxides of lanthanum, europium, and lutetium with 5 mL of 0.1 mol / L nitric acid aqueous solution to prepare a mixed solution containing lanthanum, europium, and lutetium ions (the initial concentration of the three rare earth metal ions is 100 mg / L). EGTA is added, and the ratio of the added molar amount to the sum of the molar amounts of the three rare earth ions in the initial aqueous solution is 1.5:1. Adjust the pH of the mixed solution to 2, and stir thoroughly at room temperature. Then add PEG 2000 and potassium nitrate, PEG2000 accounts for 10% by weight in the mixed solution, and potassium nitrate accounts for 20% by weight. After fully shaking and mixing at room temperature, centrifugation is carried out to obtain a two-liquid phase system in which upper and lower layers coexist. Then, 10 mL of ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate ([C4mim][PF6]) was added to the above-mentioned two-liquid phase system, and the mixture was ce...

Embodiment 3

[0037] Dissolve the oxides of lanthanum, europium, and lutetium with 5 mL of 0.1 mol / L aqueous hydrochloric acid solution to form a mixed solution containing lanthanum, europium, and lutetium ions (the initial concentrations of the three rare earth metal ions are all 100 mg / L). Add PAA, the ratio of the added molar amount to the sum of the molar amounts of the three rare earth ions in the initial aqueous solution is 2:1. Adjust the pH of the mixed solution to 5, and stir thoroughly at room temperature. Then add EOPO 2500 and sodium chloride, EOPO2500 accounts for 30% by weight in the mixed solution, and sodium chloride accounts for 30% by weight. After fully shaking and mixing at room temperature, centrifugation is carried out to obtain a two-liquid phase system in which upper and lower layers coexist. Then, add 15mL ionic liquid [C to the above-mentioned two-liquid phase system 9 h 14 N][N(CF 3 SO 2 ) 2 ], fully oscillating and mixing at room temperature, and centrifugi...

technical field

[0001] The invention belongs to the technical field of solvent extraction and separation of rare earth ions, and in particular relates to a liquid-liquid-liquid three-phase system extraction and separation method for rare earth ions. Background technique

[0002] Solvent extraction is the most important method for mutual separation and purification of rare earth elements. Due to the extremely similar chemical properties between rare earth elements, the separation coefficient between adjacent rare earth elements is extremely low. Traditional organic phase-aqueous two-liquid phase extraction systems generally improve the selectivity of separation by synthesizing high-efficiency rare earth extractants, screening extraction systems, and optimizing cascade extraction processes. However, for the complex system where multiple rare earths coexist, due to the changeable phase behavior during the extraction process, there are many factors affecting the extraction sele...

Examples

Embodiment 1

[0033] Dissolve the oxides of lanthanum, europium, and ytterbium with 5 mL of 0.1 mol / L aqueous hydrochloric acid solution to form a mixed solution containing lanthanum, europium, and ytterbium ions (the initial concentrations of the three rare earth metal ions are all 100 mg / L). EDTA is added, and the ratio of the added molar amount to the sum of the molar amounts of the three rare earth ions in the initial aqueous solution is 1:1. Adjust the pH of the mixed solution to 5, and stir thoroughly at room temperature. Then add EOPO 2500 and sodium sulfate, EOPO accounts for 20% by weight in the mixed solution, and sodium sulfate accounts for 30% by weight. After fully shaking and mixing at room temperature, centrifugation is carried out to obtain a two-liquid phase system in which upper and lower layers coexist. Then, 5 mL of ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate ([C4mim][PF6]) was added to the above-mentioned two-liquid phase system, and the mixture was ce...

Embodiment 2

[0035] Dissolve the oxides of lanthanum, europium, and lutetium with 5 mL of 0.1 mol / L nitric acid aqueous solution to prepare a mixed solution containing lanthanum, europium, and lutetium ions (the initial concentration of the three rare earth metal ions is 100 mg / L). EGTA is added, and the ratio of the added molar amount to the sum of the molar amounts of the three rare earth ions in the initial aqueous solution is 1.5:1. Adjust the pH of the mixed solution to 2, and stir thoroughly at room temperature. Then add PEG 2000 and potassium nitrate, PEG2000 accounts for 10% by weight in the mixed solution, and potassium nitrate accounts for 20% by weight. After fully shaking and mixing at room temperature, centrifugation is carried out to obtain a two-liquid phase system in which upper and lower layers coexist. Then, 10 mL of ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate ([C4mim][PF6]) was added to the above-mentioned two-liquid phase system, and the mixture was ce...

Embodiment 3

[0037] Dissolve the oxides of lanthanum, europium, and lutetium with 5 mL of 0.1 mol / L aqueous hydrochloric acid solution to form a mixed solution containing lanthanum, europium, and lutetium ions (the initial concentrations of the three rare earth metal ions are all 100 mg / L). Add PAA, the ratio of the added molar amount to the sum of the molar amounts of the three rare earth ions in the initial aqueous solution is 2:1. Adjust the pH of the mixed solution to 5, and stir thoroughly at room temperature. Then add EOPO 2500 and sodium chloride, EOPO2500 accounts for 30% by weight in the mixed solution, and sodium chloride accounts for 30% by weight. After fully shaking and mixing at room temperature, centrifugation is carried out to obtain a two-liquid phase system in which upper and lower layers coexist. Then, add 15mL ionic liquid [C to the above-mentioned two-liquid phase system 9 h 14 N][N(CF 3 SO 2 ) 2 ], fully oscillating and mixing at room temperature, and centrifugi...

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