A method for separating heavy rare earth ions based on complexation with a phosphonic complexing agent

Abstract

The application belongs to the field of rare earth separation, and particularly discloses a method for separating heavy rare earth ions based on phosphoric acid-based complexing agent complexing. In the separation method, the phosphoric acid-based complexing agent can form heavy rare earth-phosphoric acid-based complex with each heavy rare earth, and the heavy rare earth-phosphoric acid-based complex in the water phase is extracted and separated from the organic phase to purify the heavy rare earth ions, so that the heavy rare earth ions are efficiently separated, and the method provides a key technical means for solving the green separation problem of heavy rare earth.

Description

Technical Field

[0001] This invention belongs to the field of rare earth separation, specifically relating to a method for separating heavy rare earth ions based on phosphate complexing agents. Background Technology

[0002] Heavy rare earth elements (Er, Tm, Yb, etc.) have very similar ionic radii and coordination chemistry due to the gradual contraction of their 4f electron shells (Yb...). 3+ With Tm 3+ The radius difference is <1 pm, resulting in a low single-stage separation coefficient (e.g., β) when traditional acidic phosphonate extraction systems (P204, P507, Cyanex 272, etc.) separate adjacent heavy rare earth elements. Yb / Tm <3), often requiring extraction stages of over 100 to separate the various heavy rare earth ions. Therefore, there is a need to develop more efficient heavy rare earth extraction and separation methods.

[0003] Complexation extraction is a separation technique that incorporates selective complexation reactions into the traditional liquid-liquid extraction process. In recent years, researchers have attempted to introduce aminopolycarboxylic acids or hydroxycarboxylic acids such as EDTA, DTPA, lactic acid, and citric acid into the aqueous phase to amplify interionic differences through pre-complexation. However, these complexing agents undergo severe protonation under high acidity, typically resulting in a 2-3 order of magnitude decrease in their complexation constants. Furthermore, they are only effective for light rare earth elements, offering limited improvement in the separation coefficient of adjacent heavy rare earth elements.

[0004] Phosphate compounds, due to their bifunctional P=O and P-OH sites, can form stable five- / six-membered ring chelate structures with rare earth ions, and the difference in electronegativity of the coordinating atoms can amplify subtle differences in the 4f electron cloud polarizability of heavy rare earths. However, existing phosphate complexing agents are mostly limited to the extractant itself (such as di(2-ethylhexyl)phosphoric acid, P204), which still cannot significantly improve the separation coefficient between different heavy rare earth ions. Summary of the Invention

[0005] To address the issues of low separation coefficients for different heavy rare earth ions in existing technologies involving complexation extraction, this invention provides a method for separating heavy rare earth ions based on phosphate-based complexing agents. In this method, a specific phosphate-based complexing agent is used to complex heavy rare earth ions in an aqueous phase, thereby significantly improving the separation coefficients between different heavy rare earth ions during the extraction process and enhancing the separation efficiency.

[0006] To achieve the above objectives, the following technical solutions are specifically included:

[0007] This invention provides a method for separating heavy rare earth ions based on phosphate complexing agents, comprising the following steps:

[0008] S1. An aqueous solution containing heavy rare earth ions is mixed with a complexing agent and subjected to a complexation reaction to obtain a first aqueous phase; the complexing agent includes at least one of aminomethylphosphonic acid (AMPA), chloromethylphosphonic acid (CMPA), 3-phosphonopropionic acid (3-PPA), phenylphosphonic acid (PhPA), or orthophosphoric acid (H3PO4);

[0009] S2. The extractant is mixed with an organic solvent to obtain the first organic phase;

[0010] S3. The first aqueous phase and the first organic phase are mixed, extracted and separated in sequence to obtain the second aqueous phase and the second organic phase.

[0011] S4. Recover heavy rare earth elements from the second aqueous phase and / or the second organic phase.

[0012] In the separation method of this invention, at least one of aminomethylphosphonic acid (AMPA), chloromethylphosphonic acid (CMPA), 3-phosphonopropionic acid (3-PPA), phenylphosphonic acid (PhPA), or orthophosphoric acid (H3PO4) is first used as a specific phosphate complexing agent. This agent contains P=O and P-OH functional groups as complexing groups, which are used to complex with heavy rare earth ions. This allows the specific phosphate complexing agent to selectively bind with each heavy rare earth ion, forming heavy rare earth-phosphate complexes with significantly different structures. Then, the aqueous phase containing the heavy rare earth-phosphate complexes is extracted with an organic phase. During the extraction process, different heavy rare earth ions are selectively extracted from the aqueous phase into the organic phase, resulting in significant changes in the concentration of different heavy rare earth ions in the aqueous and organic phases. This leads to the enrichment of one or more heavy rare earth ions in a particular phase, resulting in a higher ion concentration of these ions compared to the unextracted phase, thereby achieving the separation and purification of different heavy rare earth ions. In this process, the complexing agent and heavy rare earth ions form a heavy rare earth-phosphate complex, which replaces the traditional direct action of "extractant-hydrated ions". This changes the thermodynamic equilibrium and kinetic rate of the reaction, thereby significantly amplifying the distribution differences of each heavy rare earth element and significantly improving the separation coefficient between different heavy rare earth ions, thus achieving the goal of efficiently separating different heavy rare earth ions.

[0013] Preferably, in step S1, the aqueous solution containing heavy rare earth ions includes Ho. 3+ Er 3+ Y 3+ Tm 3+ Yb 3+ At least two of them.

[0014] More preferably, in step S1, the aqueous solution containing heavy rare earth ions includes at least two types of heavy rare earth ions with adjacent atomic numbers.

[0015] Preferably, in step S1, the concentration of heavy rare earth ions in the aqueous solution containing heavy rare earth ions is greater than or equal to 0.05 g / L, and more preferably 0.1-10 g / L.

[0016] Preferably, in step S1, the pH value of the aqueous solution containing heavy rare earth ions is less than or equal to 4, and further, it is 0.1-1.

[0017] In a specific embodiment, the aqueous solution containing heavy rare earth ions is prepared by dissolving heavy rare earth chloride salts in water, or heavy rare earth raw material solution can be used directly.

[0018] Preferably, in step S1, the pH value of the aqueous solution containing heavy rare earth ions is adjusted using hydrochloric acid solution.

[0019] When an aqueous solution containing heavy rare earth ions is prepared by dissolving the chloride salts of heavy rare earth elements in water, and then adjusted to acidity with hydrochloric acid solution, a heavy rare earth ion solution system containing HCl is formed. This solution is generally acidic. This solution is then complexed with a specific phosphate-based complexing agent and used as the aqueous phase for extraction. Finally, the aqueous phase is extracted with the organic phase, achieving the separation and purification of each heavy rare earth ion. It is evident that the specific complexing agent of this invention can form significantly different and reversibly reversible phosphate-based complexes with each heavy rare earth element in a weakly acidic to moderately acidic solution system. Matching this with a suitable extraction system can achieve the goal of efficiently separating each heavy rare earth ion.

[0020] More preferably, the chloride salt of the heavy rare earth includes at least one of HoCl3·6H2O, ErCl3·6H2O, YCl3·6H2O, TmCl3·6H2O, and YbCl3·6H2O.

[0021] Preferably, in step S1, the aqueous solution containing heavy rare earth ions includes Er 3+ Ho 3+ At that time, the Er 3+ and Ho 3+ The mass concentration ratio is (0.5-1.5):1.

[0022] Preferably, in step S1, the aqueous solution containing heavy rare earth ions includes Tm. 3+ Er 3+ At that time, the Tm 3+ and Er 3+ The mass concentration ratio is (0.5-1.5):1.

[0023] Preferably, in step S1, the aqueous solution containing heavy rare earth ions includes Yb. 3+ Y 3+ At that time, the Yb 3+ and Y 3+The mass concentration ratio is (90-110):1.

[0024] Preferably, in step S1, the aqueous solution containing heavy rare earth ions includes Yb. 3+ Tm 3+ At that time, the Yb 3+ and Tm 3+ The mass concentration ratio is (90-110):1:

[0025] Because the specific complexing agent of the present invention can form significantly different and reversible phosphate complexes with heavy rare earth ions that are adjacent or non-adjacent in atomic number, the separation method of the present invention can efficiently separate different heavy rare earth ions.

[0026] Preferably, in step S1, the molar ratio of heavy rare earth ions in the aqueous solution containing heavy rare earth ions to the complexing agent is 1:(1-30).

[0027] Preferably, in step S1, the complexation reaction takes 60-300 seconds.

[0028] Preferably, in step S2, the extractant includes at least one of 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (P507) or di(2-ethylhexyl) phosphate (P204).

[0029] Preferably, in step S2, the organic solvent includes at least one of n-heptane or sulfonated kerosene.

[0030] Preferably, in step S2, the volume percentage of the extractant in the first organic phase is 1%-15%.

[0031] Preferably, in step S3, the volume ratio of the first aqueous phase to the first organic phase is 1:(1-10).

[0032] Preferably, in step S3, the extraction is carried out under oscillation or stirring, and the extraction time is 6-12 hours.

[0033] Preferably, in step S3, the phase separation is performed by a static setting method, and the phase separation time is 5-10 minutes.

[0034] Compared with existing technologies, the present invention has the following beneficial effects: The method of the present invention constructs a system scheme of "aqueous phase complexation-organic phase extraction" synergistic design, wherein the phosphate complexing agent of the present invention can form significantly different and reversible heavy rare earth-phosphate complexes with each heavy rare earth, and then the aqueous phase containing the heavy rare earth-phosphate complex is extracted and separated from the organic phase to purify the heavy rare earth ions, thereby achieving the purpose of efficient separation of each heavy rare earth ion, which provides a key technical means to solve the problem of green separation of heavy rare earth. Attached Figure Description

[0035] Figure 1 Er in Examples 1-5 and Comparative Example 1 3+ and Ho 3+ The extraction rate and separation coefficient of the complex extraction separation system are shown in the figure. In the figure, Without represents Comparative Example 1, and AMPA, CMPA, 3-PPA, PhPA, and H3PO4 represent Example 1, Example 2, Example 3, Example 4, and Example 5, respectively.

[0036] Figure 2 Tm in Examples 6-10 and Comparative Example 2 3+ and Er 3+ The extraction rate and separation coefficient of the complex extraction separation system are shown in the figure. In the figure, Without represents Comparative Example 2, and AMPA, CMPA, 3-PPA, PhPA, and H3PO4 represent Examples 6, 7, 8, 9, and 10, respectively.

[0037] Figure 3 Yb in Examples 11-15 and Comparative Example 3 3+ and Y 3+ The extraction rate and separation coefficient of the complex extraction separation system are shown in the figure. In the figure, Without represents Comparative Example 3, and AMPA, CMPA, 3-PPA, PhPA, and H3PO4 represent Examples 11, 12, 13, 14, and 15, respectively.

[0038] Figure 4 Yb in Examples 16-20 and Comparative Example 4 3+ and Tm 3+ The extraction rate and separation coefficient of the complex extraction separation system are shown in the figure. In the figure, Without represents Comparative Example 4, and AMPA, CMPA, 3-PPA, PhPA, and H3PO4 represent Examples 16, 17, 18, 19, and 20, respectively. Detailed Implementation

[0039] To better illustrate the purpose, technical solution, and advantages of this invention, specific embodiments will be used to further explain the invention below. Unless otherwise specified, the test methods used in the embodiments and / or comparative examples are conventional methods; the materials and reagents used, unless otherwise specified, are commercially available.

[0040] Examples 1-5

[0041] Er and Ho at the same concentration of Er 3+ and Ho 3+ The complexation extraction separation system specifically includes the following steps:

[0042] (1) Dissolve ErCl3·6H2O and HoCl3·6H2O in water, so that ErCl3·6H2O ... 3+ and Ho 3+ The mass concentrations were 10 g / L and 10 g / L, respectively, and the pH of the solution was adjusted to 1.0 using 12 mol / L hydrochloric acid solution to prepare Er 3+ and Ho 3+ Heavy rare earth ion (Er) with a mass concentration ratio of 1:1 3+ and Ho 3+ A solution of ) was used to simulate the adjacent heavy rare earth raw material solution to be extracted and purified;

[0043] (2) According to Er 3+ The molar concentration ratio of the complexing agent to the complexing agent is 1:6, and the complexing agent is directed towards the heavy rare earth ion (Er)-containing complexing agent. 3+ and Ho 3+ A complexing agent was added to the solution of the rare earth ions and allowed to stand for 1 minute to allow it to fully complex with the heavy rare earth ions, thus obtaining the first aqueous phase. The complexing agents in Examples 1-5 were aminomethylphosphonic acid (AMPA), chloromethylphosphonic acid (CMPA), 3-phosphonopropionic acid (3-PPA), phenylphosphonic acid (PhPA), and orthophosphoric acid (H3PO4), respectively, and the concentration of the complexing agent in the first aqueous phase was 0.3 mol / L.

[0044] (3) Mix and dilute 50 mL of P507 with 450 mL of n-heptane to obtain a first organic phase with a concentration of 10 vol% P507;

[0045] (4) Add the first organic phase to the first aqueous phase at a volume ratio of 1:1 and shake for 6 hours to ensure full contact for extraction;

[0046] (5) After shaking, let stand for 10 minutes to allow the organic phase and aqueous phase to fully separate into two layers, and obtain the second aqueous phase and the second organic phase after extraction;

[0047] (6) The heavy rare earth ions in the two phases above are recovered respectively. The recovered heavy rare earth can be used to prepare rare earth oxides, etc.

[0048] After extraction, the two heavy rare earth ions in the aqueous phase were selectively extracted into the organic phase, resulting in the presence of some Er in both phases. 3+ and Ho 3+ However, the different concentration ratios of the two heavy rare earth ions in the two phases cause variations in the concentrations of the two rare earth ions in the aqueous and organic phases, thereby achieving the purification of a certain heavy rare earth element. The concentrations of each heavy rare earth ion in the two phases were measured separately, and the extraction rates and separation coefficients of the two heavy rare earth ions were calculated, as shown in Table 1.

[0049] Examples 6-10

[0050] Tm and Er at the same concentration of Tm 3+ and Er 3+ The complexation extraction separation system specifically includes the following steps:

[0051] (1) Dissolve TmCl3·6H2O and ErCl3·6H2O in water to make Tm 3+ and Er 3+ The mass concentrations were 10 g / L and 10 g / L, respectively, and the pH of the solution was adjusted to 1.0 using 12 mol / L hydrochloric acid solution to prepare Tm. 3+ and Er 3+ Heavy rare earth ion (Tm) with a mass concentration ratio of 1:1 3+ and Er 3+ A solution of ) was used to simulate the adjacent heavy rare earth raw material solution to be extracted and purified;

[0052] (2) According to Tm 3+ The molar concentration ratio of the complexing agent to the complexing agent is 1:6, and the complexing agent is added to the complexing agent containing heavy rare earth ions (Tm). 3+ and Er 3+ A complexing agent was added to the solution of the rare earth ions and allowed to stand for 1 minute to allow it to fully complex with the heavy rare earth ions, thus obtaining the first aqueous phase. The complexing agents in Examples 6-10 were aminomethylphosphonic acid (AMPA), chloromethylphosphonic acid (CMPA), 3-phosphonopropionic acid (3-PPA), phenylphosphonic acid (PhPA), and orthophosphoric acid (H3PO4), respectively, and the concentration of the complexing agent in the first aqueous phase was 0.3 mol / L.

[0053] (3) Mix and dilute 50 mL of P507 with 450 mL of n-heptane to obtain a first organic phase with a concentration of 10 vol% P507;

[0054] (4) Add the first organic phase to the first aqueous phase at a volume ratio of 1:1 and shake for 6 hours to ensure full contact for extraction;

[0055] (5) After shaking, let stand for 10 minutes to allow the organic phase and aqueous phase to fully separate into two layers, and obtain the second aqueous phase and the second organic phase after extraction;

[0056] (6) The heavy rare earth ions in the two phases above are recovered respectively. The recovered heavy rare earth can be used to prepare rare earth oxides, etc.

[0057] After extraction, the two heavy rare earth ions in the aqueous phase were selectively extracted into the organic phase, resulting in the presence of some Tm in both phases. 3+ and Er 3+However, the different concentration ratios of the two heavy rare earth ions in the two phases cause variations in the concentrations of the two rare earth ions in the aqueous and organic phases, thereby achieving the purification of a certain heavy rare earth element. The concentrations of each heavy rare earth ion in the two phases were measured separately, and the extraction rates and separation coefficients of the two heavy rare earth ions were calculated, as shown in Table 1.

[0058] Examples 11-15

[0059] High concentration of Yb 3+ and Y 3+ The complexation extraction separation system specifically includes the following steps:

[0060] (1) Dissolve YbCl3·6H2O and YCl3·6H2O in water, so that Yb 3+ and Y 3+ The mass concentrations were 10 g / L and 0.1 g / L, respectively, and the pH of the solution was adjusted to 1.0 using 12 mol / L hydrochloric acid solution to prepare Yb. 3+ and Y 3+ A concentration ratio of 100:1 containing heavy rare earth ions (Yb) 3+ and Y 3+ A solution of ) was used to simulate the heavy rare earth raw material solution to be extracted and purified;

[0061] (2) According to Yb 3+ The molar concentration ratio of the complexing agent to the complexing agent is 1:6, and the complexing agent is added to the complexing agent containing heavy rare earth ions (Yb). 3+ and Y 3+ A complexing agent was added to the solution of the rare earth ions and allowed to stand for 1 minute to allow it to fully complex with the heavy rare earth ions, thus obtaining the first aqueous phase. The complexing agents in Examples 11-15 were aminomethylphosphonic acid (AMPA), chloromethylphosphonic acid (CMPA), 3-phosphonopropionic acid (3-PPA), phenylphosphonic acid (PhPA), and orthophosphoric acid (H3PO4), respectively, and the concentration of the complexing agent in the first aqueous phase was 0.3 mol / L.

[0062] (3) Mix and dilute 50 mL of P507 with 450 mL of n-heptane to obtain a first organic phase with a concentration of 10 vol% P507;

[0063] (4) Add the first organic phase to the first aqueous phase at a volume ratio of 1:1 and shake for 6 hours to ensure full contact for extraction;

[0064] (5) After shaking, let stand for 10 minutes to allow the organic phase and aqueous phase to fully separate into two layers, and obtain the second aqueous phase and the second organic phase after extraction;

[0065] (6) The heavy rare earth ions in the two phases above are recovered respectively. The recovered heavy rare earth can be used to prepare rare earth oxides, etc.

[0066] After extraction, the two heavy rare earth ions in the aqueous phase were selectively extracted into the organic phase, resulting in the presence of some Yb in both phases. 3+ and Y 3+ However, the different concentration ratios of the two heavy rare earth ions in the two phases cause variations in the concentrations of the two rare earth ions in the aqueous and organic phases, thereby achieving the purification of a certain heavy rare earth element. The concentrations of each heavy rare earth ion in the two phases were measured separately, and the extraction rates and separation coefficients of the two heavy rare earth ions were calculated, as shown in Table 1.

[0067] Examples 16-20

[0068] High concentration of Yb 3+ and Tm 3+ The complexation extraction separation system specifically includes the following steps:

[0069] (1) Dissolve YbCl3·6H2O and TmCl3·6H2O in water, so that Yb 3+ and Tm 3+ The mass concentrations were 10 g / L and 0.1 g / L, respectively, and the pH of the solution was adjusted to 1.0 using 12 mol / L hydrochloric acid solution to prepare Yb. 3+ and Tm 3+ Heavy rare earth ion (Yb) with a mass concentration ratio of 100:1 3+ and Tm 3+ A solution of ) was used to simulate the adjacent heavy rare earth raw material solution to be extracted and purified;

[0070] (2) According to Yb 3+ The molar concentration ratio of the complexing agent to the complexing agent is 1:6, and the complexing agent is added to the complexing agent containing heavy rare earth ions (Yb). 3+ and Tm 3+ A complexing agent was added to the solution of the rare earth ions and allowed to stand for 1 minute to allow it to fully complex with the heavy rare earth ions, thus obtaining the first aqueous phase. The complexing agents in Examples 16-20 were aminomethylphosphonic acid (AMPA), chloromethylphosphonic acid (CMPA), 3-phosphonopropionic acid (3-PPA), phenylphosphonic acid (PhPA), and orthophosphoric acid (H3PO4), respectively, and the concentration of the complexing agent in the first aqueous phase was 0.3 mol / L.

[0071] (3) Mix and dilute 50 mL of P507 with 450 mL of n-heptane to obtain a first organic phase with a concentration of 10 vol% P507;

[0072] (4) Add the first organic phase to the first aqueous phase at a volume ratio of 1:1 and shake for 6 hours to ensure full contact for extraction;

[0073] (5) After shaking, let stand for 10 minutes to allow the organic phase and aqueous phase to fully separate into two layers, and obtain the second aqueous phase and the second organic phase after extraction;

[0074] (6) The heavy rare earth ions in the two phases above are recovered respectively. The recovered heavy rare earth can be used to prepare rare earth oxides, etc.

[0075] After extraction, the two heavy rare earth ions in the aqueous phase were selectively extracted into the organic phase, resulting in the presence of some Yb in both phases. 3+ and Tm 3+ However, the different concentration ratios of the two heavy rare earth ions in the two phases cause variations in the concentrations of the two rare earth ions in the aqueous and organic phases, thereby achieving the purification of a certain heavy rare earth element. The concentrations of each heavy rare earth ion in the two phases were measured separately, and the extraction rates and separation coefficients of the two heavy rare earth ions were calculated, as shown in Table 1.

[0076] Example 21

[0077] Compared with Example 1, this example replaces the extractant P507 in the first organic phase with P204 by an equal volume, while the rest remains the same.

[0078] Comparative Example 1

[0079] Compared with Example 1, the difference is that this comparative example lacks step (2), while the rest are the same.

[0080] Comparative Example 2

[0081] Compared with Example 6, the difference is that this comparative example lacks step (2), but the rest is the same.

[0082] Comparative Example 3

[0083] Compared with Example 11, the difference is that this comparative example lacks step (2), but the rest is the same.

[0084] Comparative Example 4

[0085] Compared with Example 16, the difference is that this comparative example lacks step (2), but the rest is the same.

[0086] Comparative Example 5

[0087] Compared with Example 1, the difference is that the complexing agent in step (2) of this comparative example is replaced with citric acid (CA) in equal amounts, while the rest is the same.

[0088] Comparative Example 6

[0089] Compared with Example 1, the difference is that the complexing agent in step (2) of this comparative example is replaced by an equal amount of ethylenediaminetetraacetic acid (EDTA), and the rest is the same.

[0090] Let M represent a heavy rare earth element, and M1 and M2 represent the first and second heavy rare earth elements, respectively. This pattern continues for other heavy rare earth elements. In this paper, the extraction rate (%) = c1 / c0 × 100, where c0 is the concentration of M ions in the first aqueous phase and c1 is the concentration of M ions in the second organic phase. Different heavy rare earth elements are calculated independently. A higher extraction rate indicates a higher purity of a certain heavy rare earth ion in the second aqueous phase after extraction. The separation coefficient β is used to measure the separation and purification of two heavy rare earth element ions (represented by M1 and M2). M1 / M2 =(C M1O / C M1W ) / (C M2O / C M2W ), where C M1O C M1W C represents the concentration of M1 ions in the second organic phase and the second aqueous phase, respectively. M2O C M2W β represents the M2 ion concentration in the second organic phase and the M2 ion concentration in the second aqueous phase, respectively. M1 / M2 The higher the value, the higher the separation efficiency of the two heavy rare earth elements, M1 and M2. Meanwhile, for simpler labeling, the separation coefficient β is... M1 / M2 When valence states of heavy rare earth ions are omitted, for example, Er 3+ with Ho 3+ The separation coefficient is expressed as β Er / Ho .

[0091] Table 1

[0092]

[0093] From Examples 1-5 and Comparative Example 1 Figure 1 As shown in Table 1, after adding the complexing agent, the Er obtained by complexation extraction... 3+ and Ho 3+ Separation coefficient β Er / Ho Compared to the original extraction reaction system in Comparative Example 1, the β-resistance in Examples 1-5 was significantly improved. Er / Ho The value increases by approximately 8% to 18%.

[0094] From Examples 6-10 and Comparative Example 2 Figure 2 As shown in Table 1, after adding the complexing agent, the Tm obtained by complexation extraction... 3+ and Er 3+ Separation coefficient β Tm / ErCompared to the original extraction reaction system in Comparative Example 2, the β-resistance in Examples 6-10 was significantly improved. Tm / Er The value increases by approximately 6% to 20%.

[0095] Examples 11-15 and Comparative Example 3 Figure 3 As shown in Table 1, after adding the complexing agent, the Yb obtained by complexation extraction... 3+ and Y 3+ Separation coefficient β Yb / Y Compared to the original extraction reaction system in Comparative Example 3, the β-resistance in Examples 11-15 was significantly improved. Yb / Y The value increased by approximately 63% to 82%.

[0096] From Examples 16-20 and Comparative Example 4 Figure 4 As shown in Table 1, after adding the complexing agent, the Yb obtained by complexation extraction... 3+ and Tm 3+ Separation coefficient β Yb / Tm Compared to the original extraction reaction system in Comparative Example 4, the β-resistance in Examples 16-20 was significantly improved. Yb / Tm The value increased by approximately 14% to 31%.

[0097] As can be seen from Example 1 and Comparative Examples 5-6, using other types of organic acids as complexing agents, Er 3+ and Ho 3+ The separation coefficient is significantly low. Based on the above examples and comparative examples, it can be confirmed that the present invention, using aminomethylphosphonic acid (AMPA), chloromethylphosphonic acid (CMPA), 3-phosphonopropionic acid (3-PPA), phenylphosphonic acid (PhPA), or orthophosphoric acid (H3PO4) as complexing agents, can significantly improve the separation coefficient and efficiency between different heavy rare earth ions.

[0098] It should be noted that the above embodiments are only some embodiments of the present invention. In specific implementation, the present invention obtains the products corresponding to each embodiment by changing the type and mixing ratio of rare earth chloride salt in step (1), changing the type and concentration of extractant in step (3), changing the molar concentration ratio of rare earth ions to complexing agent in step (2), and changing the volume ratio of organic phase to aqueous phase in step (4). Then, each product is characterized, the separation performance of adjacent heavy rare earth elements in each embodiment is studied, and the optimal operating parameters are selected based on the performance comparison results.

[0099] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for separating heavy rare earth ions complexed with a phosphoric acid-based complexing agent, characterized by, The method comprises the following steps: S1, mixing and complexing an aqueous solution containing heavy rare earth ions with a complexing agent to obtain a first aqueous phase; the complexing agent comprises at least one of aminomethyl phosphonic acid, chloromethyl phosphonic acid, 3-phosphonopropionic acid, phenyl phosphonic acid or orthophosphoric acid; S2, mixing an extractant with an organic solvent to obtain a first organic phase; S3, sequentially mixing, extracting and phase separating the first aqueous phase and the first organic phase to obtain a second aqueous phase and a second organic phase; S4, recovering heavy rare earth elements from the second aqueous phase and / or the second organic phase.

2. The method for separating the heavy rare earth ions complexed with the phosphoric group complexing agent according to claim 1, characterized by, In step S1, the aqueous solution containing heavy rare earth ions includes at least two of Ho 3+ , Er 3+ , Y 3+ , Tm 3+ , Yb 3+ .

3. The method for separating the heavy rare earth ions complexed with the phosphoric group complexing agent according to claim 1, wherein In step S1, the molar ratio of heavy rare earth ions in the aqueous solution containing heavy rare earth ions to the complexing agent is 1: (1-30).

4. The method for separating the heavy rare earth ions complexed with the phosphoric group complexing agent according to claim 1, wherein In step S1, the complexing reaction time is 60-300 s, and the pH value of the aqueous solution containing heavy rare earth ions is less than or equal to 4.

5. The method for separating the heavy rare earth ions complexed with the phosphato-based complexing agent according to claim 1, wherein In step S2, the extractant comprises at least one of 2-ethylhexyl phosphonic acid mono 2-ethylhexyl ester or di (2-ethylhexyl) phosphate ester.

6. The method for separating the heavy rare earth ions complexed with the phosphato-based complexing agent according to claim 1, wherein In step S2, the organic solvent comprises at least one of n-heptane or sulfonated kerosene.

7. The method for separating the heavy rare earth ions complexed with the phosphato-based complexing agent according to claim 1, wherein In step S2, the volume percentage content of the extractant in the first organic phase is 1%-15%.

8. The method for separating the heavy rare earth ions complexed with the phosphato-based complexing agent according to claim 1, wherein In step S3, the volume ratio of the first aqueous phase to the first organic phase is 1: (1-10).

9. The method for separating the heavy rare earth ions complexed with the phosphato-based complexing agent according to claim 1, wherein In step S3, the extraction is carried out under oscillation or stirring, and the extraction time is 6-12 h.

10. The method for separating the heavy rare earth ions complexed with the phosphato-based complexing agent according to claim 1, wherein In step S3, the phase separation is carried out by static method, and the phase separation time is 5-10 min.

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