Method for extracting and separating heavy rare earths

Abstract

The application discloses a method for extracting and separating heavy rare earth elements, which comprises the following steps: a. mixing a eutectic solvent and a diluent to obtain an extractant solution, wherein the eutectic solvent comprises an acidic phosphorus extractant and an amide extractant; b. extracting and separating the extractant solution and a solution containing heavy rare earth elements to obtain an aqueous phase and a loaded organic phase, and recovering heavy rare earth elements from the aqueous phase and the loaded organic phase, respectively. The method for extracting and separating heavy rare earth elements effectively improves the separation coefficient between heavy rare earth elements in the extraction process, reduces the fractionation extraction series, and reduces the water solubility of the organic phase by using a eutectic solvent for extracting and separating heavy rare earth elements.

Description

Technical Field

[0001] This invention relates to the field of heavy rare earth separation technology, and specifically to a method for extracting and separating heavy rare earth elements. Background Technology

[0002] Heavy rare earth elements have wide applications in optoelectronics, magnetism, and other fields, such as laser media, radiation sources, scintillation crystals, and magnetic materials, and have become indispensable strategic mineral resources for modern high-tech industries. Therefore, the recovery and separation of heavy rare earth elements from natural resources such as ores and secondary resources are important research directions. Currently, the main methods for separating heavy rare earth elements include ion exchange, solvent extraction, and adsorption. Among these, solvent extraction has become the core mainstream technology for the separation and purification of heavy rare earth elements due to its high processing efficiency, ease of continuous industrial production, and wide applicable concentration range. However, because heavy rare earth elements have very similar ionic radii and coordination chemistry, traditional extraction systems have poor selectivity for heavy rare earth elements, resulting in low separation coefficients between elements, often requiring hundreds of stages of fractionation extraction.

[0003] Therefore, it is necessary to conduct in-depth research on the separation methods of heavy rare earth elements. Summary of the Invention

[0004] This invention is based on the inventor's discovery and understanding of the following facts and problems: In the current related technologies, CN121023264A discloses a method for separating heavy rare earth ions. First, a vinyl complexing agent is used to selectively complex heavy rare earth ions in an aqueous phase to significantly improve the partition coefficient between different heavy rare earth ions. Then, the aqueous phase containing the heavy rare earth ion complex is extracted and separated from the different heavy rare earth ions by an organic phase containing an extractant, thus improving the separation efficiency. However, this technical solution requires a large amount of additional complexing agent, leading to a significant increase in cost. CN104195336A discloses an extraction and separation method for heavy rare earth elements, using a bifunctional ionic liquid extractant composed of one of the quaternary ammonium cations and quaternary phosphonium cations and a deprotonated acidic phosphine anion to extract rare earth enrichments and inorganic acid mixtures. This method can enhance the competitive interaction between the ionic liquid cations and rare earth ions, thereby improving the heavy rare earth extraction and separation coefficient. However, the ionic liquid has high water solubility and is costly.

[0005] This invention aims to at least partially solve one of the technical problems in related technologies. To this end, embodiments of this invention propose a method for the extraction and separation of heavy rare earth elements. By employing a hydrogen-bonded eutectic solvent for the extraction and separation of heavy rare earth elements, the separation coefficient between heavy rare earth elements during the extraction process is effectively improved, the number of fractionation extraction stages is reduced, and the water solubility of the organic phase is decreased.

[0006] The extraction and separation method for heavy rare earth elements according to embodiments of the present invention includes the following steps:

[0007] a. An extractant solution is obtained by mixing a eutectic solvent and a diluent, wherein the eutectic solvent includes acidic phosphorus extractants and amide extractants; b. Extract the extractant solution with a solution containing heavy rare earth elements to obtain an aqueous phase and a supported organic phase, and recover the heavy rare earth elements from the aqueous phase and the supported organic phase respectively.

[0008] The advantages and technical effects of the extraction and separation method for heavy rare earth elements in this embodiment of the invention are as follows: In the extraction solvent solution, the phosphate group of the acidic organophosphorus extractant acts as a proton donor, and the amide group of the amide extractant acts as a proton acceptor. The two are bonded by hydrogen bonds to form a eutectic solvent. The presence of hydrogen bonds can significantly affect the dissociation ability of hydrogen ions in the phosphate group, amplify the exchange capacity with different heavy rare earth elements, and effectively improve the selectivity for heavy rare earth elements. At the same time, the method of this embodiment of the invention can reduce the number of fractionation extraction stages and reduce the water solubility of the organic phase.

[0009] In some embodiments, the acidic phosphorus extractant includes at least one of di(2-ethylhexyl) phosphate, 2-ethylhexyl phosphate mono-2-ethylhexyl ester, or bis(2,4,4-trimethylpentyl)phosphonic acid.

[0010] In some embodiments, the amide extractant includes a monodentate amide extractant, the structural formula of which is shown in Formula I: Formula I R1, R2 and R3 are each independently selected from at least one of alkyl, aromatic, heteroatom-containing alkyl or heteroaromatic groups.

[0011] In some embodiments, the amide extractant comprises at least one of the following compounds: , , , , , , .

[0012] In some embodiments, the eutectic solvent contains 1-99% by mass of the acidic phosphorus extractant and 1-99% by mass of the amide extractant.

[0013] In some embodiments, the diluent includes at least one of halogenated hydrocarbons, solvent oils, and aromatic compounds.

[0014] In some embodiments, the halogenated hydrocarbon compound includes at least one of chlorinated hydrocarbons, bromine hydrocarbons, or iodinated hydrocarbons; the solvent oil includes at least one of 3# white oil, 5# white oil, D60, D80, Solvesso 150, or Solvesso 200; and the aromatic compound includes at least one of monobenzene aromatics or polycyclic aromatics.

[0015] In some embodiments, the extractant solution contains 5% to 99% by mass of the eutectic solvent and 1% to 95% by mass of the diluent.

[0016] In some embodiments, the solution containing heavy rare earth elements includes two or three of thulium, ytterbium, and lutetium.

[0017] In some embodiments, in step b, the pH of the solution containing heavy rare earth elements is adjusted to 1-7, the extraction temperature is 10-90 °C, the phase O / A ratio is 0.1-20, the extraction time is 0.5-60 min, and after extraction, the solution is allowed to stand for phase separation for 0.5-60 min. Detailed Implementation

[0018] The embodiments of the present invention are described in detail below. These embodiments are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0019] The extraction and separation method for heavy rare earth elements according to embodiments of the present invention includes the following steps: a. An extractant solution is obtained by mixing a eutectic solvent and a diluent, wherein the eutectic solvent includes acidic phosphorus extractants and amide extractants; b. Extract the extractant solution with a solution containing heavy rare earth elements to obtain an aqueous phase and a supported organic phase, and recover the heavy rare earth elements from the aqueous phase and the supported organic phase respectively.

[0020] In the method of this invention, the phosphate group of the acidic organophosphorus extractant acts as a proton donor and the amide group of the amide extractant acts as a proton acceptor in the extractant solution. The two are bonded by hydrogen bonds to form a eutectic solvent. The presence of hydrogen bonds can significantly affect the dissociation ability of hydrogen ions in the phosphate group, amplify the exchange capacity with different heavy rare earth elements, and effectively improve the selectivity for heavy rare earth elements. At the same time, the method of this invention can reduce the number of fractionation extraction stages and reduce the water solubility of the organic phase.

[0021] In some embodiments, the acidic phosphorus extractant includes at least one selected from di(2-ethylhexyl) phosphate, 2-ethylhexyl phosphate mono-2-ethylhexyl ester, or bis(2,4,4-trimethylpentyl)phosphonic acid. In these embodiments, an acidic phosphorus extractant is preferred, as it facilitates the formation of a eutectic solvent with amide extractants, thereby improving the selectivity for heavy rare earth elements and increasing the separation coefficient between heavy rare earth elements.

[0022] In some embodiments, the amide extractant includes a monodentate amide extractant, the structural formula of which is shown in Formula I: Formula I R1, R2, and R3 are each independently selected from at least one of alkyl, aromatic, heteroatom-containing alkyl, or heteroaromatic groups. The amide extractant in the embodiments of the present invention may be liquid or solid at room temperature.

[0023] Preferably, the amide extractant comprises at least one of the following compounds: , , , , , , .

[0024] In this embodiment of the invention, amide-based extractants are further preferred, which is beneficial for forming a eutectic solvent with acidic phosphorus-based extractants, thereby further improving the separation coefficient between heavy rare earth elements.

[0025] In some embodiments, the acidic phosphorus extractant in the eutectic solvent has a mass percentage content of 1-99%, preferably 20-80%, more preferably 35-80%, and the amide extractant has a mass percentage content of 1-99%, preferably 20-80%, more preferably 20-65%. In these embodiments, the amounts of acidic phosphorus extractant and amide extractant in the eutectic solvent are further optimized, which is beneficial for the formation of the eutectic solvent, thereby improving the selectivity for heavy rare earth elements and enhancing the extraction and separation effect.

[0026] In some embodiments, the diluent is a low-water-soluble inert organic compound. Preferably, the diluent includes at least one of halogenated hydrocarbons, solvent oils, and aromatic compounds. More preferably, the halogenated hydrocarbons include at least one of chlorinated hydrocarbons, bromine hydrocarbons, or iodocarbons; the solvent oils include at least one of 3# white oil, 5# white oil, D60, D80, Solvesso 150, or Solvesso 200; and the aromatic compounds include at least one of monobenzene aromatics or polycyclic aromatics. In these embodiments, there are no particular limitations on the diluent; commonly used extraction diluents in the prior art are all applicable to this invention.

[0027] In some embodiments, the eutectic solvent in the extractant solution has a mass percentage content of 5% to 99%, preferably 15% to 90%, and the diluent has a mass percentage content of 1% to 95%, preferably 10% to 85%.

[0028] In some embodiments, the solution containing heavy rare earth elements includes two or three of thulium, ytterbium, and lutetium. When the solution containing heavy rare earth elements contains any two of thulium, ytterbium, and lutetium, the method of this embodiment can achieve effective separation of the two heavy rare earth elements through a single extraction. When the solution containing heavy rare earth elements contains all three of thulium, ytterbium, and lutetium, the method of this embodiment separates ytterbium and lutetium into the organic phase and thulium into the aqueous phase through a single extraction, thus achieving separation of ytterbium and lutetium from thulium. Further, the ytterbium and lutetium in the organic phase are back-extracted with acid to allow them to enter the aqueous phase. Then, the solution containing ytterbium and lutetium is subjected to a second extraction separation using the method of this embodiment, achieving separation of ytterbium and lutetium. In this embodiment of the invention, by using a eutectic solvent formed by acidic phosphorus extractant and amide extractant as the extractant, the separation coefficient between heavy rare earth elements can be improved, and the effective separation of difficult-to-separate heavy rare earth elements such as thulium, ytterbium and lutetium can be achieved.

[0029] In some embodiments, in step b, the pH of the solution containing heavy rare earth elements is adjusted to 1-7, the extraction temperature is 10-90 °C, the phase O / A ratio is 0.1-20, the extraction time is 0.5-60 min, and after extraction, the solution is allowed to stand for phase separation for 0.5-60 min.

[0030] The present invention will now be described in detail with reference to the embodiments.

[0031] Example 1 (1) Preparation of eutectic solvent: Combine acidic phosphorus extractant 2-ethylhexyl phosphate mono-2-ethylhexyl ester and amide extractant The mixture is thoroughly stirred to form a eutectic solvent, in which the mass percentage of 2-ethylhexyl phosphate mono-2-ethylhexyl ester is 45%. The mass percentage content is 55%; (2) Preparation of the extractant solution: Mix the diluent Solvesso 150 with the eutectic solvent thoroughly to prepare the extractant solution. In the extractant solution, the mass percentage of the eutectic solvent is 60% and the mass percentage of Solvesso 150 is 40%. (3) Heavy rare earth solution: The heavy rare earth solution is a sulfuric acid solution containing thulium and ytterbium. Among the heavy rare earth elements, the mass percentage of thulium is 79.64% and the mass percentage of ytterbium is 20.36%. The pH value of the heavy rare earth solution is adjusted to 5.62. (4) Extraction and separation of heavy rare earth elements: The extractant solution from step (2) was used to extract and separate the heavy rare earth elements in the solution from step (3). The extraction temperature was 35 °C, the phase ratio O / A was 12, and the extraction time was 20 min. After extraction, the solution was allowed to stand for 15 min to separate the phases. After extraction and separation, an aqueous phase and a loaded organic phase were obtained. Most of the ytterbium elements entered the organic phase after extraction, while most of the thulium elements remained in the aqueous phase.

[0032] In this embodiment of the invention, the extraction rate of thulium was 87.19%, the extraction rate of ytterbium was 97.54%, and the separation coefficient β(ytterbium / thulium) was 5.83.

[0033] Example 2 (1) Preparation of eutectic solvent: Combine acidic phosphorus extractant di(2-ethylhexyl) phosphate and amide extractant The mixture is thoroughly stirred to form a eutectic solvent, in which the mass percentage of di(2-ethylhexyl) phosphate is 65%. The mass percentage content is 35%; (2) Preparation of extractant solution: Mix diluent D80 solvent oil and eutectic solvent thoroughly to prepare extractant solution. In extractant solution, the mass percentage of eutectic solvent is 50% and the mass percentage of D80 solvent oil is 50%. (3) Heavy rare earth solution: The heavy rare earth solution is a sulfuric acid solution containing ytterbium and lutetium. Among the heavy rare earth elements, the mass percentage of ytterbium is 82.64% and the mass percentage of lutetium is 17.36%. The pH value of the heavy rare earth solution is adjusted to 4.89. (4) Extraction and separation of heavy rare earth elements: The extractant solution from step (2) was used to extract and separate the heavy rare earth elements in the solution from step (3). The extraction temperature was 45 °C, the phase ratio O / A was 5, and the extraction time was 18 min. After extraction, the solution was allowed to stand for 5 min to separate the phases. After extraction and separation, an aqueous phase and a loaded organic phase were obtained. Most of the lutetium elements were extracted into the organic phase, while most of the ytterbium elements remained in the aqueous phase.

[0034] In this embodiment of the invention, the extraction rate of ytterbium was 84.44%, the extraction rate of lutetium was 97.35%, and the separation coefficient β(lutetium / ytterbium) was 6.77.

[0035] Example 3 (1) Preparation of eutectic solvent: Combine acidic phosphorus extractant 2-ethylhexyl phosphate mono-2-ethylhexyl ester and amide extractant The mixture is thoroughly stirred to form a eutectic solvent, in which the mass percentage of 2-ethylhexyl phosphate mono-2-ethylhexyl ester is 80%. The mass percentage content is 20%; (2) Preparation of extractant solution: Mix diluent 5# white oil and eutectic solvent thoroughly to prepare extractant solution. In extractant solution, the mass percentage of eutectic solvent is 20% and the mass percentage of 5# white oil is 80%. (3) Heavy rare earth solution: The heavy rare earth solution is a hydrochloric acid solution containing thulium and lutetium. Among the heavy rare earth elements, the mass percentage of thulium is 68.54% and the mass percentage of lutetium is 31.46%. The pH value of the heavy rare earth solution is adjusted to 6.84. (4) Extraction and separation of heavy rare earth elements: The extractant solution from step (2) was used to extract and separate the heavy rare earth elements in the solution from step (3). The extraction temperature was 85 °C, the phase O / A ratio was 6.5, and the extraction time was 3 min. After extraction, the solution was allowed to stand for 10 min to separate the phases. After extraction and separation, an aqueous phase and a loaded organic phase were obtained. Most of the lutetium elements entered the organic phase after extraction, while most of the thulium elements remained in the aqueous phase.

[0036] In this embodiment of the invention, the extraction rate of thulium was 83.28%, the extraction rate of lutetium was 97.27%, and the separation coefficient β(lutetium / thulium) was 7.14.

[0037] Example 4 (1) Preparation of eutectic solvent: Combine acidic phosphorus extractant bis(2,4,4-trimethylpentyl)phosphonic acid and amide extractant The mixture is thoroughly stirred to form a eutectic solvent, in which the mass percentage of bis(2,4,4-trimethylpentyl)phosphonic acid is 70%. The mass percentage content is 30%; (2) Preparation of extractant solution: Mix the diluent toluene and the eutectic solvent thoroughly to prepare the extractant solution. In the extractant solution, the mass percentage of the eutectic solvent is 90% and the mass percentage of toluene is 10%. (3) Heavy rare earth solution: The heavy rare earth solution is a sulfuric acid solution containing thulium and ytterbium. Among the heavy rare earth elements, the mass percentage of thulium is 84.14% and the mass percentage of ytterbium is 15.86%. The pH value of the heavy rare earth solution is adjusted to 3.22. (4) Extraction and separation of heavy rare earth elements: The extractant solution from step (2) was used to extract and separate the heavy rare earth elements in the solution from step (3). The extraction temperature was 15 °C, the phase ratio O / A was 0.5, and the extraction time was 30 min. After extraction, the solution was allowed to stand for 40 min to separate the phases. After extraction and separation, an aqueous phase and a loaded organic phase were obtained. Most of the ytterbium elements entered the organic phase after extraction, while most of the thulium remained in the aqueous phase.

[0038] In this embodiment of the invention, the extraction rate of thulium was 79.25%, the extraction rate of ytterbium was 97.16%, and the separation coefficient β(ytterbium / thulium) was 8.97.

[0039] Example 5 (1) Preparation of eutectic solvent: acidic phosphorus extractants di(2-ethylhexyl) phosphate and 2-ethylhexyl phosphate mono-2-ethylhexyl ester are combined with amide extractants The mixture is thoroughly stirred to form a eutectic solvent, in which the mass percentage of di(2-ethylhexyl) phosphate is 15% and the mass percentage of 2-ethylhexyl phosphate mono-2-ethylhexyl ester is 20%. The mass percentage content is 65%; (2) Preparation of extractant solution: Mix the diluent Solvesso 200 and the eutectic solvent thoroughly to prepare the extractant solution. In the extractant solution, the mass percentage of the eutectic solvent is 75% and the mass percentage of Solvesso 200 is 25%. (3) Heavy rare earth solution: The heavy rare earth solution is a sulfuric acid solution containing thulium, ytterbium and lutetium. Among the heavy rare earth elements, the mass percentage of thulium is 24.86%, the mass percentage of ytterbium is 59.63%, and the mass percentage of lutetium is 15.51%. The pH value of the heavy rare earth solution is adjusted to 1.83. (4) Extraction and separation of heavy rare earth elements: The extractant solution from step (2) was used to extract and separate the heavy rare earth elements from the solution in step (3). The extraction temperature was 20 °C, the phase O / A ratio was 2, and the extraction time was 35 min. After extraction, the solution was allowed to stand for 4.5 min to separate the phases. After extraction and separation, an aqueous phase and a loaded organic phase were obtained. Most of the lutetium and ytterbium elements entered the organic phase after extraction, while most of the thulium remained in the aqueous phase.

[0040] In this embodiment of the invention, the extraction rate of thulium was 82.06%, the extraction rate of ytterbium was 96.90%, the extraction rate of lutetium was 98.19%, the separation coefficient β(ytterbium / thulium) was 6.83, the separation coefficient β(lutetium / thulium) was 11.89, and the separation coefficient β(lutetium / ytterbium) was 1.74.

[0041] Example 6 (1) Preparation of eutectic solvent: Combine the acidic phosphorus extractant di(2-ethylhexyl) phosphate with the amide extractant and The mixture is thoroughly stirred to form a eutectic solvent, in which the mass percentage of di(2-ethylhexyl) phosphate is 68%. The mass percentage content is 12%. The mass percentage content is 20%; (2) Preparation of extractant solution: Mix 1-chlorooctane diluent with eutectic solvent thoroughly to prepare extractant solution. In extractant solution, the mass percentage of eutectic solvent is 15% and the mass percentage of 1-chlorooctane is 85%. (3) Heavy rare earth solution: The heavy rare earth solution is a hydrochloric acid solution containing thulium and ytterbium. Among the heavy rare earth elements, the mass percentage of thulium is 12.62% and the mass percentage of ytterbium is 87.38%. The pH value of the heavy rare earth solution is adjusted to 4.89. (4) Extraction and separation of heavy rare earth elements: The extractant solution from step (2) was used to extract and separate the heavy rare earth elements in the solution from step (3). The extraction temperature was 10 °C, the phase O / A ratio was 18, and the extraction time was 40 min. After extraction, the solution was allowed to stand for 3 min to separate the phases. After extraction and separation, an aqueous phase and a loaded organic phase were obtained. Most of the ytterbium elements entered the organic phase after extraction, while most of the thulium elements remained in the aqueous phase.

[0042] In this embodiment of the invention, the extraction rate of thulium was 87.56%, the extraction rate of ytterbium was 98.60%, and the separation coefficient β(ytterbium / thulium) was 10.03.

[0043] Example 7 (1) Preparation of eutectic solvent: acidic phosphorus extractant di(2-ethylhexyl) phosphate and bis(2,4,4-trimethylpentyl)phosphonic acid are combined with amide extractant The mixture is thoroughly stirred to form a eutectic solvent, in which the mass percentage of di(2-ethylhexyl) phosphate is 5% and the mass percentage of bis(2,4,4-trimethylpentyl)phosphonic acid is 35%. The mass percentage content is 60%; (2) Preparation of extractant solution: Mix diluent 3# white oil and D60 solvent oil with eutectic solvent thoroughly to prepare extractant solution. In extractant solution, the mass percentage of eutectic solvent is 40%, the mass percentage of 3# white oil is 30%, and the mass percentage of D60 solvent oil is 30%. (3) Heavy rare earth solution: The heavy rare earth solution is a sulfuric acid solution containing thulium, ytterbium and lutetium. Among the heavy rare earth elements, the mass percentage of thulium is 14.86%, the mass percentage of ytterbium is 70.56%, and the mass percentage of lutetium is 14.58%. The pH value of the heavy rare earth solution is adjusted to 5.08. (4) Extraction and separation of heavy rare earth elements: The extractant solution from step (2) was used to extract and separate the heavy rare earth elements in the solution from step (3). The extraction temperature was 75℃, the phase O / A ratio was 18, and the extraction time was 55 min. After extraction, the solution was allowed to stand for 20 min to separate the phases. After extraction and separation, an aqueous phase and a loaded organic phase were obtained. Most of the lutetium and ytterbium elements entered the organic phase after extraction, while most of the thulium remained in the aqueous phase.

[0044] In this embodiment of the invention, the extraction rate of thulium is 90.17%, the extraction rate of ytterbium is 98.93%, the extraction rate of lutetium is 99.18%, the separation coefficient β(ytterbium / thulium) is 10.14, the separation coefficient β(lutetium / thulium) is 13.13, and the separation coefficient β(lutetium / ytterbium) is 1.29.

[0045] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0046] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for extracting and separating heavy rare earth elements, characterized in that, Includes the following steps: a. An extractant solution is obtained by mixing a eutectic solvent and a diluent, wherein the eutectic solvent includes acidic phosphorus extractants and amide extractants; b. Extract the extractant solution with a solution containing heavy rare earth elements to obtain an aqueous phase and a supported organic phase, and recover the heavy rare earth elements from the aqueous phase and the supported organic phase respectively.

2. The method for extraction and separation of heavy rare earth elements according to claim 1, characterized in that, The acidic phosphorus extractant includes at least one of di(2-ethylhexyl) phosphate, 2-ethylhexyl phosphate mono-2-ethylhexyl ester, or bis(2,4,4-trimethylpentyl)phosphonic acid.

3. The method for extraction and separation of heavy rare earth elements according to claim 1, characterized in that, The amide extractant includes a monodentate amide extractant, the structural formula of which is shown in Formula I: Equation I R1, R2 and R3 are each independently selected from at least one of alkyl, aromatic, heteroatom-containing alkyl or heteroaromatic groups.

4. The method for extraction and separation of heavy rare earth elements according to claim 3, characterized in that, The amide extractant includes at least one of the following compounds: 、 、 、 、 、 、 。 5. The method for extraction and separation of heavy rare earth elements according to any one of claims 1-4, characterized in that, In the eutectic solvent, the mass percentage of the acidic phosphorus extractant is 1-99%, and the mass percentage of the amide extractant is 1-99%.

6. The method for extraction and separation of heavy rare earth elements according to claim 1, characterized in that, The diluent includes at least one of halogenated hydrocarbons, solvent oils, and aromatic compounds.

7. The method for extraction and separation of heavy rare earth elements according to claim 6, characterized in that, The halogenated hydrocarbons include at least one of chlorinated hydrocarbons, bromine hydrocarbons, or iodinated hydrocarbons; the solvent oil includes at least one of 3# white oil, 5# white oil, D60, D80, Solvesso 150, or Solvesso 200; the aromatic compounds include at least one of monobenzene aromatics or polycyclic aromatics.

8. The method for extraction and separation of heavy rare earth elements according to claim 1, characterized in that, In the extractant solution, the mass percentage of the eutectic solvent is 5% to 99%, and the mass percentage of the diluent is 1% to 95%.

9. The method for extraction and separation of heavy rare earth elements according to claim 1, characterized in that, The solution containing heavy rare earth elements includes two or three of the following: thulium, ytterbium, and lutetium.

10. The method for extraction and separation of heavy rare earth elements according to claim 1, characterized in that, In step b, the pH of the solution containing heavy rare earth elements is adjusted to 1-7, the extraction temperature is 10-90 ℃, the phase O / A ratio is 0.1-20, the extraction time is 0.5-60 min, and after extraction, the solution is allowed to stand for phase separation for 0.5-60 min.

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